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  • 101. Casas-Ruiz, Joan P.
    et al.
    Catalan, Nuria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Gomez-Gener, Lluis
    von Schiller, Daniel
    Obrador, Biel
    Kothawala, Dolly
    Swedish University of Agricultural Sciences.
    Lopez, Pilar
    Sabater, Sergi
    Marce, Rafael
    A tale of pipes and reactors: Controls on the in-stream dynamics of dissolved organic matter in rivers2017Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 62, s. S85-S94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The potential for rivers to alter the flux of dissolved organic matter (DOM) from land to ocean is widely accepted. Yet anticipating when and where rivers behave as active reactors vs. passive pipes of DOM stands as a major knowledge gap in river biogeochemistry, resulting in uncertainties for global carbon models. Here, we investigate the controls on in-stream DOM dynamics by evaluating changes in DOM concentration and composition along several reaches of a medium-sized river network over one full hydrological year. Roughly half of the observations over time and space showed active reactor conditions and, among these, similar pro-portion of gains and losses was measured. High water residence times promoted the active over passive behavior of the reaches, while DOM properties and nitrate availability determined whether they supplied or removed DOM from the river. Among different DOM fractions, protein-like DOM both of terrestrial and aquatic origin seemed to drive bulk DOM patterns. Our study emphasizes the role of water residence time as a physical constraint for in-stream processes, and provides new insights into the key factors governing the net balance between in-stream gains and losses of DOM in rivers.

  • 102.
    Casas-Ruiz, Joan P.
    et al.
    Catalan Inst Water Res ICRA, Emili Grahit 101, Girona 17003, Spain..
    Tittel, Joerg
    UFZ Helmholtz Ctr Environm Res, Dept Lake Res, Bruckstr 3a, D-39114 Magdeburg, Germany..
    von Schiller, Daniel
    Univ Basque Country, Fac Sci & Technol, Dept Plant Biol & Ecol, Apdo 644, Bilbao 48080, Spain..
    Catalan, Nuria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Obrador, Biel
    Univ Barcelona, Dept Ecol, Av Diagonal 643, E-08028 Barcelona, Spain..
    Gomez-Gener, Lluis
    Univ Barcelona, Dept Ecol, Av Diagonal 643, E-08028 Barcelona, Spain..
    Zwirnmann, Elke
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Muggelseedamm 301, D-12587 Berlin, Germany..
    Sabater, Sergi
    Catalan Inst Water Res ICRA, Emili Grahit 101, Girona 17003, Spain.;Univ Girona, Inst Aquat Ecol, Girona 17071, Spain..
    Marce, Rafael
    Catalan Inst Water Res ICRA, Emili Grahit 101, Girona 17003, Spain..
    Drought-induced discontinuities in the source and degradation of dissolved organic matter in a Mediterranean river2016Inngår i: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 127, nr 1, s. 125-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The composition of dissolved organic matter (DOM) in rivers results from the different sources and in-stream transformations along the land to ocean aquatic continuum. Riverine DOM sources are highly dependent on the hydrological connection between the river channel and the surrounding terrestrial ecosystems, but how the lack of this connectivity (e.g., during drought episodes) affects the sources and biodegradation of DOM in rivers remains unclear. Here we identified the DOM sources as well as the different DOM pools that are respired along a Mediterranean river during drought by combining absorbance-fluorescence spectroscopy, size-exclusion chromatography, biodegradation assays, and stable and radiocarbon isotopes. DOM composition was highly heterogeneous along the river in response to different sources and in-stream processes in each distinct aquatic environment (i.e., isolated water pools, running waters, and impounded waters in weirs). The reduced hydrological connectivity with terrestrial ecosystems promoted the influence of autochthonous DOM sources. Still, tree leaves from overhanging canopies stood out as an important terrestrial DOM source, especially in sites where water residence time was high such as isolated pools and weirs. Degradation of leaf leachates was a relevant process in these sites, whereas autochthonous DOM and groundwater millennial DOM (> 1300 year B.P.) seemed to be degraded in running waters. Overall, our results highlight that the drought-induced hydrological disconnection entails a great spatial heterogeneity in the sources of DOM, which at the same time determines the different DOM pools that are respired in each environment along the river.

  • 103.
    Catalan, N.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Catalan Inst Water Res ICRA, Girona, Spain.
    Casas-Ruiz, J. P.
    Catalan Inst Water Res ICRA, Girona, Spain..
    von Schiller, D.
    Univ Basque Country, Fac Sci & Technol, Dept Plant Biol & Ecol, Bilbao, Spain..
    Proia, L.
    Univ Libre Bruxelles, ESA, Brussels, Belgium..
    Obrador, B.
    Univ Barcelona, Dept Ecol, Barcelona, Spain..
    Zwirnmann, E.
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Berlin, Germany..
    Marce, R.
    Catalan Inst Water Res ICRA, Girona, Spain..
    Biodegradation kinetics of dissolved organic matter chromatographic fractions in an intermittent river2017Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, nr 1, s. 131-144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Controls on the degradation of dissolved organic matter (DOM) are complex but key to understand the role of freshwaters in the carbon cycle. Both the origin and previous degradation history have been suggested to determine DOM reactivity, but it is still a major challenge to understand the links between DOM composition and biodegradation kinetics. An appropriate context to study these links are intermittent rivers, as summer drought naturally diversifies DOM sources and sinks. Here we investigated the biodegradation kinetics of DOM in the main aquatic environments present in a temporary river. During dark incubations we traced the dynamics of bulk DOM and its main chromatographic fractions defined using LC-OCD: high molecular weight substances (HMWS), low molecular weight substances (LMWS), and humic substances and building blocks. Bulk DOM decay patterns were successfully fitted to the reactivity continuum (RC) biodegradation model. The RC parameters depicted running waters as the sites presenting a more reactive DOM, and temporary pools, enriched in leaf litter, as the ones with slowest DOM decay. The decay patterns of each DOM fraction were consistent throughout sites. LMWS and HMWS decayed in all cases and could be modeled using the RC model. Notably, the dynamics of LMWS controlled the bulk DOM kinetics. We discuss the mechanistic basis for the chromatographic fractions' kinetics during biodegradation and the implications that preconditioning and summer drought can have for DOM biodegradation in intermittent rivers.

  • 104.
    Catalan, Nuria
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Marce, Rafael
    Catalan Inst Water Res ICRA, Emili Grahit 101, Girona 17003, Spain..
    Kothawala, Dolly N.
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, S-75007 Uppsala, Sweden..
    Tranvik, Lars. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Organic carbon decomposition rates controlled by water retention time across inland waters2016Inngår i: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 9, nr 7, s. 501-504Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The loss of organic carbon during passage through the continuum of inland waters from soils to the sea is a critical component of the global carbon cycle(1-3). Yet, the amount of organic carbon mineralized and released to the atmosphere during its transport remains an open question(2,4-6), hampered by the absence of a common predictor of organic carbon decay rates(1,7). Here we analyse a compilation of existing field and laboratory measurements of organic carbon decay rates and water residence times across a wide range of aquatic ecosystems and climates. We find a negative relationship between the rate of organic carbon decay and water retention time across systems, entailing a decrease in organic carbon reactivity along the continuum of inland waters. We find that the half-life of organic carbon is short in inland waters (2.5 +/- 4.7 yr) compared to terrestrial soils and marine ecosystems, highlighting that freshwaters are hotspots of organic carbon degradation. Finally, we evaluate the response of organic carbon decay rates to projected changes in runoff(8). We calculate that regions projected to become drier or wetter as the global climate warms will experience changes in organic carbon decay rates of up to about 10%, which illustrates the influence of hydrological variability on the inland waters carbon cycle.

  • 105.
    Catalan, Nuria
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    von Schiller, Daniel
    Marce, Rafael
    Koschorreck, Matthias
    Gomez-Gener, Lluis
    Obrador, Biel
    Carbon dioxide efflux during the flooding phase of temporary ponds2014Inngår i: LIMNETICA, ISSN 0213-8409, Vol. 33, nr 2, s. 349-359Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Small water bodies, such as temporary ponds, have a high carbon processing potential. Nevertheless, despite the global occurrence of these systems, the carbon effluxes from such water bodies have been largely overlooked. In this study, we examined the intra- and intersystem variability of carbon dioxide (CO2) effluxes from a set of Mediterranean temporary ponds during the flooding phase, a hot-spot for biogeochemical cycling in temporary systems. The CO2 effluxes showed higher variability among the various sections of each pond (i.e., inundated, emerged-unvegetated and emerged-vegetated) than among the ponds. The emerged-vegetated sections showed the highest CO2 effluxes per unit area and tended to drive the total effluxes at the whole-ecosystem scale. The mean CO2 efflux (121.3 +/- 138.1 mmol m(-2) d(-1)) was in the upper range for freshwater ecosystems. The CO2 effluxes were not related to catchment properties but rather to the organic content of the sediments, especially in the emerged sections of the ponds. Our results indicate that temporary ponds, especially their emerged sections, are important sources of CO2 to the atmosphere, highlighting the need to include the dry phases of these and other temporary aquatic systems in regional carbon budgets.

  • 106.
    Catalán, Núria
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Catalan Inst Water Res ICRA, Girona, Spain.
    Casas-Ruiz, J. P.
    Univ Quebec Montreal, Dept Biol Sci, Grp Rech Interuniv Limnol, Montreal, PQ, Canada.
    Arce, M. I.
    Ctr Edafol & Apply Biol Segura CEBAS CSIC, Murcia, Spain.
    Abril, M.
    Univ Vic Cent Univ Catalonia, Aquat Ecol Grp, BETA Technol Ctr, Barcelona, Spain.
    Bravo, A. G.
    CSIC, Inst Environm Assessment & Water Res IDAEA, Dept Environm Chem, Barcelona, Spain.
    del Campo, R.
    Univ Murcia, Fac Biol, Dept Ecol & Hydrol, Reg Campus Int Excellence Campus Mare Nostrum, Murcia, Spain.
    Estevez, E.
    Univ Cantabria, Environm Hydraul Inst, Santander, Spain.
    Freixa, A.
    Gimenez-Grau, P.
    CREAF CSIC, Cerdanyola Del Valles, Spain.
    Gonzalez-Ferreras, A. M.
    Univ Cantabria, Environm Hydraul Inst, Santander, Spain.
    Gomez-Gener, Ll.
    Umea Univ, Dept Ecol & Environm Sci, Umea, Sweden.
    Lupon, A.
    Swedish Univ Agr Sci, Dept Forest Ecol & Management, Umea, Sweden.
    Martinez, A.
    Univ Basque Country UPV EHU, Dept Plant Biol & Ecol, Lab Stream Ecol, Bilbao, Spain.
    Palacin-Lizarbe, C.
    CREAF CSIC, Cerdanyola Del Valles, Spain.
    Poblador, S.
    Univ Barcelona, Fac Biol, Dept Biol Evolut Ecol & Ciencies Ambientals, Barcelona, Spain.
    Rasines-Ladero, R.
    Univ Alcala De Henares, Parque Cient Tecnol, iMdea Water Inst, De Henares, Spain.
    Reyes, M.
    Eawag, Swiss Fed Inst Aquat Sci & Technol, Dept Aquat Ecol, Dubendorf, Switzerland.
    Rodriguez-Castillo, T.
    Univ Cantabria, Environm Hydraul Inst, Santander, Spain.
    Rodriguez-Lozano, P.
    Univ Calif Berkeley, Dept Environm Sci Policy & Management, Berkeley, CA 94720 USA.
    Sanpera-Calbet, I.
    Univ Barcelona, Fac Biol, Dept Biol Evolut Ecol & Ciencies Ambientals, Barcelona, Spain.
    Tornero, I.
    Univ Girona, Inst Aquat Ecol, GRECO, Girona, Spain.
    Pastor, A.
    Aarhus Univ, Dept Biosci, Aarhus, Denmark.
    Behind the Scenes: Mechanisms Regulating Climatic Patterns of Dissolved Organic Carbon Uptake in Headwater Streams2018Inngår i: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 32, nr 10, s. 1528-1541Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Large variability in dissolved organic carbon (DOC) uptake rates has been reported for headwater streams, but the causes of this variability are still not well understood. Here we assessed acetate uptake rates across 11 European streams comprising different ecoregions by using whole-reach pulse acetate additions. We evaluated the main climatic and biogeochemical drivers of acetate uptake during two seasonal periods. Our results show a minor influence of sampling periods but a strong effect of climate and dissolved organic matter (DOM) composition on acetate uptake. In particular, mean annual precipitation explained half of the variability of the acetate uptake velocities (Vf(Acetate)) across streams. Temperate streams presented the lowest Vf(Acetate), together with humic-like DOM and the highest stream respiration rates. In contrast, higher Vf(Acetate) were found in semiarid streams, with protein-like DOM, indicating a dominance of reactive, labile compounds. This, together with lower stream respiration rates and molar ratios of DOC to nitrate, suggests a strong C limitation in semiarid streams, likely due to reduced inputs from the catchment. Overall, this study highlights the interplay of climate and DOM composition and its relevance to understand the biogeochemical mechanisms controlling DOC uptake in streams. Plain Language Summary Headwater streams receive and degrade organic carbon and nutrients from the surrounding catchments. That degradation can be assessed by measuring the uptake of simple compounds of carbon or nitrogen such as acetate or nitrate. Here we determine the variability in acetate and nitrate uptake rates across headwater streams and elucidate the mechanisms behind that variability. The balance between nutrients, the composition of the organic materials present in the streams, and the climatic background is at interplay.

  • 107.
    Catalán, Núria
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Herrero Ortega, S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Gröntoft, H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hilmarsson, T. G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Wu, Pianpian
    Levanoni, Oded
    Bishop, K.
    Garcia Bravo, Andrea
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Effects of beaver impoundments on dissolved organic matter quality and biodegradability in boreal riverine systems2017Inngår i: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 793, nr 1, s. 135-148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Beaver impoundments modify the structure of river reaches and lead to changes in ecosystem function and biogeochemical processes. Here, we assessed the changes in dissolved organic matter (DOM) quality and the biodegradation patterns in a set of beaver systems across Sweden. As the effect of beaver impoundments might be transient and local, we compared DOM quality and biodegradability of both pond and upstream sections of differentially aged beaver systems. Newly established dams shifted the sources and DOM biodegradability patterns. In particular, humic-like DOM, most likely leached from surrounding soils, characterized upstream sections of new beaver impoundments. In contrast, autochthonous and processed compounds, with both higher biodegradation rates and a broader spectrum of reactivities, differentiated DOM in ponds. DOM in recently established ponds seemed to be more humic and less processed compared to older ponds, but system idiosyncrasies determined by catchment particularities influenced this ageing effect.

  • 108.
    Catalán, Núria
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Kellerman, Anne M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Peter, Hannes
    Carmona, Francesc
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Absence of a priming effect on dissolved organic carbon degradation in lake water2015Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 60, nr 1, s. 159-168Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The idea that small amounts of labile organic carbon might trigger the degradation of previously unreactive organic matter has attracted increasing scientific interest across multiple disciplines. Although this phenomenon, referred to as priming, has been widely reported in soils, evidence in freshwater systems is scarce and inconclusive. Here, we use a multifactorial microcosm experiment to test the conditions under which priming may be observed in freshwater ecosystems. We assessed the effect of pulse additions of three labile carbon sources (acetate, glucose, and cellobiose) on dissolved organic carbon (DOC) consumption using water from lakes with different trophic states (eutrophic to oligotrophic and clear to brownwater lakes). We further analyzed the effect of nutrient availability and the role of attachment of cells to surfaces. Despite the range of conditions tested, we found no clear evidence of a priming effect on DOC degradation, indicating that priming in freshwater systems may be of limited importance.

  • 109.
    Cayón, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för biologisk grundutbildning.
    Different anti-predator defenses induced by roach and signal crayfish in the invader zebra mussel2010Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 110.
    Chmiel, Hannah Elisa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    The role of sediments in the carbon cycle of boreal lakes2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Inland waters are active sites of carbon (C) processing and emitters of carbon dioxide (CO2) and methane (CH4) to the atmosphere. In the boreal zone, where surface waters receive large quantities of organic carbon (OC) from surrounding forests and wetlands, lakes and streams act as strong sources of these greenhouse gases. Lake sediments provide the only long-term sink of C in boreal inland waters, through burial of OC. However, mineralization of OC counteracts the efficiency of lake sediments in removing C from the short-term C cycle. In this context, this thesis provides a better insight into the dual role of boreal lake sediments as C source and C sink.

    The presented work is based on empirical assessments of OC burial and OC mineralization rates in boreal lakes. The temporal variability of OC burial and the stability of the buried OC was assessed on both centennial and millennial timescales. The quantitative importance of sediment OC burial and mineralization in comparison both to other C fluxes within the lake, and to C fluxes within the tributary stream network, was quantified. By simulating the effect of climate change on water temperature, we also gauged the potential future efficiency of lake sediments in storing C.

    The results demonstrate that OC mineralization in sediments dominates three-fold over OC burial when observed at a whole-basin and annual scale. The contribution of sediment OC mineralization to annual C emission from the assessed study lake was, however, found to be small (16%), when compared to OC mineralization in the water column (37%) and catchment import of C (47%). Furthermore, C emission from headwater streams was found to dominate greatly over the lake C emission, mainly triggered by the higher gas transfer velocity of streams compared to lakes.

    On a long-term (Holocene) scale, the continuous OC burial flux results in a large amount of C stored in sediments. The temporal variability of this OC accumulation was found to vary across lakes, with, however, time-dependent patterns: On a millennial scale, smaller lakes exhibited a higher variability than larger lakes of the study area. For the last century, similar variability and a trend to increased OC accumulation was found for most study lakes, irrespective of their size. Analysis of lignin phenols in the accumulated OC did not indicated post-depositional degradation, independent of the age of the sediment OC, implying that sediments are a very stable sink for land-derived OC in boreal lakes.

    Simulation of warming water temperatures in boreal lakes resulted in declines of the OC burial efficiency BE (OCBE; OC burial/OCdeposition) up to 16%, depending, however, on basin morphometry. Predicted declines in OCBE were higher for the more shallow lake compared to the deeper lake.

    In conclusion, this thesis illustrates that sediments play, despite a small quantitative impact on aquatic C cycling, an important role as a very stable C sink in boreal lakes. However, the efficiency of this C sink is likely to be reduced in the future.

    Delarbeid
    1. Uncoupled organic matter burial and quality in boreal lake sediments over the Holocene
    Åpne denne publikasjonen i ny fane eller vindu >>Uncoupled organic matter burial and quality in boreal lake sediments over the Holocene
    Vise andre…
    2015 (engelsk)Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 120, nr 9, s. 1751-1763Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Boreal lake sediments are important sites of organic carbon (OC) storage, which have accumulated substantial amounts of OC over the Holocene epoch; the temporal evolution and the strength of this Holocene carbon (C) sink is, however, not well constrained. In this study we investigated the temporal record of carbon mass accumulation rates (CMARs), and assessed qualitative changes of terrestrially derived OC in the sediment profiles of seven Swedish boreal lakes, in order to evaluate the variability of boreal lake sediments as a C sink over time.

    CMARs were resolved on a short-term (centennial) and long-term (i.e. over millennia of the Holocene) time scale, using radioactive lead (210 Pb) and carbon (14C) isotope dating. Sources and degradation state of terrestrially derived OC were identified and characterized by molecular analyses of lignin phenols.

    We found that CMARs varied substantially on both short-term and long-term scales, and that the variability was mostly attributed to sedimentation rates and uncoupled from the OC content in the sediment profiles. The lignin phenol analyses revealed that woody material from gymnosperms was a dominant and constant OC source to the sediments over the Holocene. Furthermore, lignin-based degradation indices, such as acid-to-aldehyde ratios, indicated that post-depositional degradation in the sediments was very limited on longer time scales, implying that terrestrial OC is stabilized in the sediments on a permanent basis.

    Emneord
    organic carbon, accumulation rates, radiocarbon dating, lead dating, lignin phenols, carbon sink
    HSV kategori
    Forskningsprogram
    Biologi med inriktning mot limnologi
    Identifikatorer
    urn:nbn:se:uu:diva-260660 (URN)10.1002/2015JG002987 (DOI)000363332900004 ()
    Forskningsfinansiär
    Swedish Research Council Formas
    Tilgjengelig fra: 2015-09-07 Laget: 2015-08-21 Sist oppdatert: 2018-05-21bibliografisk kontrollert
    2. The role of sediments in the carbon budget of a small boreal lake
    Åpne denne publikasjonen i ny fane eller vindu >>The role of sediments in the carbon budget of a small boreal lake
    Vise andre…
    2016 (engelsk)Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 61, nr 5, s. 1814-1825Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We investigated the role of lake sediments as carbon (C) source and sink in the annual C budget of a small (0.07 km2), shallow (mean depth 3.4 m), and humic lake (mean DOC concentration 17 mg L-1) in boreal Sweden. Organic carbon (OC) burial and mineralization in sediments were quantified from 210Pb-dated sediment and laboratory sediment incubation experiments, respectively, and upscaled to the entire basin and to one whole year, by using sediment thickness derived sub-bottom profiling, basin morphometry, and water column monitoring data of temperature and oxygen concentration. Furthermore, catchment C import, open water metabolism, photochemical mineralization as well as carbon dioxide (CO2) and methane (CH4) emissions to the atmosphere, were quantified to relate sediment processes to other lake C fluxes. We found that on a whole-basin and annual scale, sediment OC mineralization was three times larger than OC burial, and contributed about 16% to the annual CO2 emission from the lake to the atmosphere. Remaining contributions to the CO2 emission were attributed to water column metabolism (31%), photochemical mineralization (6%), and catchment imports via inlet streams and inflow of shallow groundwater (47%). We conclude that on an annual and whole-basin scale 1) sediment OC mineralization dominated over OC burial, 2) water column OC mineralization contributed more than sediments to lake CO2 emission, and 3) catchment import of C to the lake was greater than lake-internal C cycling. 

    Emneord
    mineralization, burial, carbon dioxide, methane, emission, photomineralization
    HSV kategori
    Forskningsprogram
    Biologi med inriktning mot limnologi
    Identifikatorer
    urn:nbn:se:uu:diva-260666 (URN)10.1002/lno.10336 (DOI)000383621800019 ()
    Forskningsfinansiär
    EU, European Research CouncilSwedish Research Council FormasSwedish Research Council
    Tilgjengelig fra: 2015-09-07 Laget: 2015-08-21 Sist oppdatert: 2018-05-21bibliografisk kontrollert
    3. Carbon dioxide evasion from headwater systems strongly contributes to the total export of carbon from a small boreal lake catchment
    Åpne denne publikasjonen i ny fane eller vindu >>Carbon dioxide evasion from headwater systems strongly contributes to the total export of carbon from a small boreal lake catchment
    Vise andre…
    2015 (engelsk)Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 120, nr 1, s. 13-28Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Inland waters are hotspots for carbon (C) cycling and therefore important for landscape C budgets. Small streams and lakes are particularly important; however, quantifying C fluxes is difficult and has rarely been done for the entire aquatic continuum, composed of connected streams and lakes within the same catchment. We investigated carbon dioxide (CO2) evasion and fluvial fluxes of dissolved inorganic carbon and dissolved organic carbon (DIC and DOC) in stream and lake systems within the 2.3km(2) catchment of a small boreal lake. Our results show pronounced spatial and temporal variability in C fluxes even at a small spatial scale. C loss from the catchment through CO2 evasion from headwaters for the total open water-sampling period was 9.7g C m(-2) catchment, dominating the total catchment C loss (including CO2 evasion, DIC, and DOC export from the lake, which were 2.7, 0.2, and 5.2g C m(-2) catchment, respectively). Aquatic CO2 evasion was dominated by headwater streams that occupy similar to 0.1% of the catchment but contributed 65% to the total aquatic CO2 evasion from the catchment. The importance of streams was mainly an effect of the higher gas transfer velocities than compared to lakes (median, 67 and 2.2cmh(-1), respectively). Accurately estimating the contribution of C fluxes from headwater streams, particularly the temporal and spatial dynamics in their gas transfer velocity, is key to landscape-scale C budgets. This study demonstrates that CO2 evasion from headwaters can be the major pathway of C loss from boreal catchments, even at a small spatial scale.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-241585 (URN)10.1002/2014JG002706 (DOI)000349899200002 ()
    Tilgjengelig fra: 2015-01-13 Laget: 2015-01-13 Sist oppdatert: 2018-05-21bibliografisk kontrollert
    4. Decreased efficiency of sediment carbon burial in boreal lakes at warming lake water temperatures
    Åpne denne publikasjonen i ny fane eller vindu >>Decreased efficiency of sediment carbon burial in boreal lakes at warming lake water temperatures
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Organic carbon (OC) burial in lake sediments is a fundamental process for aquatic carbon (C) cycling since it removes C from the active cycling pool. Here, we address the effect of lake warming on the OC burial efficiency (OCBE) of sediments in boreal humic lakes to evaluate the impact of warmer water temperatures and altered water column stratification patterns on the OCBE with respect to future climate change. Present-day water column conditions of temperature and oxygen concentration were monitored in two small (<0.1 km2) boreal lakes in central and southwestern Sweden over an annual cycle. Furthermore, OC burial, sediment OC mineralization, the OCBE, and lake CO2 and CH4 emission to the atmosphere, were quantified on a whole-basin scale and for a whole year. Then, future temperature and stratification patterns were simulated in both lakes by adjusting present-day temperature and oxygen conditions according to projected air temperature warming scenarios, in order to quantify the net effect on the OCBE. Present-day conditions were found to be similar in the two study lakes, with annual OC mineralization (~1 t C yr-1) exceeding annual OC burial (<0.5 t C yr-1) at least by a factor of two, returning whole-basin OC burial efficiencies of 28 and 25%, respectively. Also, annual CO2 and CH4 emission was found to be of similar magnitude in both study lakes (6-7 t C yr-1) surpassing sediment C fluxes by at least 5 times. The different lake warming scenarios (RCP 2.6, 4.5 and 8.5, corresponding to increase in annual mean air temperature of 1.5-4.5 °C) caused moderate decreases in the OCBE of 5-16% and 3-11% for each lake, respectively. The more pronounced decreases in OCBE were obtained for the more shallow lake, related to a higher proportion of sediments being affected by warming in the epilimnion. Our results suggest that warmer surface water temperatures in the future are likely to reduce the efficiency of the lake sediment C sink, thereby affecting the long-term C balance of the boreal forest biome.

    HSV kategori
    Forskningsprogram
    Biologi med inriktning mot limnologi
    Identifikatorer
    urn:nbn:se:uu:diva-260668 (URN)
    Tilgjengelig fra: 2015-09-07 Laget: 2015-08-21 Sist oppdatert: 2015-10-01
  • 111.
    Chmiel, Hannah Elisa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Kokic, Jovana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Denfeld, Blaize Amber
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Einarsdóttir, Karólina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Wallin, Marcus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Köhler, Birgit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Isidorova, Anastasija
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bastviken, David
    Linköping University.
    Ferland, Marie-Ève
    Université du Québec à Montréal, Québec, Canada.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    The role of sediments in the carbon budget of a small boreal lake2016Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 61, nr 5, s. 1814-1825Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated the role of lake sediments as carbon (C) source and sink in the annual C budget of a small (0.07 km2), shallow (mean depth 3.4 m), and humic lake (mean DOC concentration 17 mg L-1) in boreal Sweden. Organic carbon (OC) burial and mineralization in sediments were quantified from 210Pb-dated sediment and laboratory sediment incubation experiments, respectively, and upscaled to the entire basin and to one whole year, by using sediment thickness derived sub-bottom profiling, basin morphometry, and water column monitoring data of temperature and oxygen concentration. Furthermore, catchment C import, open water metabolism, photochemical mineralization as well as carbon dioxide (CO2) and methane (CH4) emissions to the atmosphere, were quantified to relate sediment processes to other lake C fluxes. We found that on a whole-basin and annual scale, sediment OC mineralization was three times larger than OC burial, and contributed about 16% to the annual CO2 emission from the lake to the atmosphere. Remaining contributions to the CO2 emission were attributed to water column metabolism (31%), photochemical mineralization (6%), and catchment imports via inlet streams and inflow of shallow groundwater (47%). We conclude that on an annual and whole-basin scale 1) sediment OC mineralization dominated over OC burial, 2) water column OC mineralization contributed more than sediments to lake CO2 emission, and 3) catchment import of C to the lake was greater than lake-internal C cycling. 

  • 112.
    Chmiel, Hannah Elisa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Natchimuthu, Sivakiruthika
    Linköping University.
    Bastviken, David
    Linköping University.
    Decreased efficiency of sediment carbon burial in boreal lakes at warming lake water temperaturesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Organic carbon (OC) burial in lake sediments is a fundamental process for aquatic carbon (C) cycling since it removes C from the active cycling pool. Here, we address the effect of lake warming on the OC burial efficiency (OCBE) of sediments in boreal humic lakes to evaluate the impact of warmer water temperatures and altered water column stratification patterns on the OCBE with respect to future climate change. Present-day water column conditions of temperature and oxygen concentration were monitored in two small (<0.1 km2) boreal lakes in central and southwestern Sweden over an annual cycle. Furthermore, OC burial, sediment OC mineralization, the OCBE, and lake CO2 and CH4 emission to the atmosphere, were quantified on a whole-basin scale and for a whole year. Then, future temperature and stratification patterns were simulated in both lakes by adjusting present-day temperature and oxygen conditions according to projected air temperature warming scenarios, in order to quantify the net effect on the OCBE. Present-day conditions were found to be similar in the two study lakes, with annual OC mineralization (~1 t C yr-1) exceeding annual OC burial (<0.5 t C yr-1) at least by a factor of two, returning whole-basin OC burial efficiencies of 28 and 25%, respectively. Also, annual CO2 and CH4 emission was found to be of similar magnitude in both study lakes (6-7 t C yr-1) surpassing sediment C fluxes by at least 5 times. The different lake warming scenarios (RCP 2.6, 4.5 and 8.5, corresponding to increase in annual mean air temperature of 1.5-4.5 °C) caused moderate decreases in the OCBE of 5-16% and 3-11% for each lake, respectively. The more pronounced decreases in OCBE were obtained for the more shallow lake, related to a higher proportion of sediments being affected by warming in the epilimnion. Our results suggest that warmer surface water temperatures in the future are likely to reduce the efficiency of the lake sediment C sink, thereby affecting the long-term C balance of the boreal forest biome.

  • 113.
    Chmiel, Hannah Elisa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Niggemann, Jutta
    University of Oldenburg, Germany.
    Kokic, Jovana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Ferland, Marie-Ève
    Université du Québec à Montréal, Québec, Canada.
    Dittmar, Thorsten
    University of Oldenburg, Germany.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Uncoupled organic matter burial and quality in boreal lake sediments over the Holocene2015Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 120, nr 9, s. 1751-1763Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Boreal lake sediments are important sites of organic carbon (OC) storage, which have accumulated substantial amounts of OC over the Holocene epoch; the temporal evolution and the strength of this Holocene carbon (C) sink is, however, not well constrained. In this study we investigated the temporal record of carbon mass accumulation rates (CMARs), and assessed qualitative changes of terrestrially derived OC in the sediment profiles of seven Swedish boreal lakes, in order to evaluate the variability of boreal lake sediments as a C sink over time.

    CMARs were resolved on a short-term (centennial) and long-term (i.e. over millennia of the Holocene) time scale, using radioactive lead (210 Pb) and carbon (14C) isotope dating. Sources and degradation state of terrestrially derived OC were identified and characterized by molecular analyses of lignin phenols.

    We found that CMARs varied substantially on both short-term and long-term scales, and that the variability was mostly attributed to sedimentation rates and uncoupled from the OC content in the sediment profiles. The lignin phenol analyses revealed that woody material from gymnosperms was a dominant and constant OC source to the sediments over the Holocene. Furthermore, lignin-based degradation indices, such as acid-to-aldehyde ratios, indicated that post-depositional degradation in the sediments was very limited on longer time scales, implying that terrestrial OC is stabilized in the sediments on a permanent basis.

  • 114.
    Chmiel, Hannah
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hofmann, Hilmar
    Environmental Physics Group, Limnological Institute, University of Konstanz, Konstanz, Germany.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Efremova, Tatyana
    Northern Water Problems Institute, Karelian Research Centre, Russian Academy of Sciences, Petrozavodsk, Russia.
    Pasche, Natacha
    Physics of Aquatic Systems Laboratory, Margaretha Kamprad Chair, ENAC, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Limnology Center, ENAC, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
    Where does the river end ?: Drivers of spatiotemporal variability in CO2 concentration and flux in the inflow area of a large boreal lake2019Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    River inflow affects the spatiotemporal variability of carbon dioxide (CO2) in the water column of lakes and may locally influence CO2 gas exchange with the atmosphere. However, spatiotemporal CO2 variability at river inflow sites is often unknown leaving estimates of lake‐wide CO2 emission uncertain. Here, we investigated the CO2 concentration and flux variability along a river‐impacted bay and remote sampling locations of Lake Onego. During 3 years, we resolved spatial CO2 gradients between river inflow and central lake and recorded the temporal course of CO2 in the bay from the ice‐covered period to early summer. We found that the river had a major influence on the spatial CO2 variability during ice‐covered periods and contributed ~ 35% to the total amount of CO2 in the bay. The bay was a source of CO2 to the atmosphere at ice‐melt each year emitting 2–15 times the amount as an equally sized area in the central lake. However, there was large interannual variability in the spring CO2 emission from the bay related to differences in discharge and climate that affected the hydrodynamic development of the lake during spring. In early summer, the spatial CO2 variability was unrelated to the river signal but correlated negatively with dissolved oxygen concentrations instead indicating a stronger biological control on CO2. Our study reveals a large variability of CO2 and its drivers at river inflow sites at the seasonal and at the interannual time scale. Understanding these dynamics is essential for predicting lake‐wide CO2 fluxes more accurately under a warming climate.

    Fulltekst tilgjengelig fra 2020-11-20 09:28
  • 115.
    Choudary, Preetam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Routh, Joyanto
    Department of Water and Environmental Studies, Linköping University.
    Chakrapani, Govind
    Department of Earth Sciences, Indian Institute of Technology, Roorkee.
    A 100-year record of changes in organic matter characteristics and productivity in Lake Bhimtal in the Kumaon Himalaya, NW India2013Inngår i: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 49, nr 2, s. 129-143Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sediment variables total organic carbon (TOC), total nitrogen (TN), total sulfur (TS), as well as their accumulation rates and atomic ratios (C/N and C/S), were studied along with stable isotopes (δ13C, δ15N, and δ34S), and specific biomarkers (n-alkanes and pigments) in a 35-cm-long sediment core from Lake Bhimtal, NW India. The average sedimentation rate is 3.6 mm year−1, and the core represents a provisional record of ~100 years of sedimentation history. Bulk elemental records and their ratios indicate that sediment organic matter (OM) is derived primarily from algae. In-lake productivity increased sharply over the last two decades, consistent with paleoproductivity reconstructions from other lakes in the area. An up-core decrease in δ13C values, despite other evidence for an increase in lake productivity, implies that multiple biogeochemical processes (e.g. external input of sewage or uptake of isotopically depleted CO2 as a result of fossil fuel burning) influence the C isotope record in the lake. The δ15N values (−0.2 to −3.9 ‰) reflect the presence of N-fixing cyanobacteria, and an increase in lake productivity. The δ34S profile shows enrichment of up to 5.6 ‰, and suggests that sulfate reduction occurred in these anoxic sediments. Increases in total n-alkane concentrations and their specific ratios, such as the Carbon Preference Index (CPI) and Terrestrial Aquatic Ratio (TAR), imply in-lake algal production. Likewise, pigments indicate an up-core increase in total concentration and dominance of cyanobacteria over other phytoplankton. Geochemical trends indicate a recent increase in the lake’s trophic state as a result of human-induced changes in the catchment. The study highlights the vulnerability of mountain lakes in the Himalayan region to both natural and anthropogenic processes, and the difficulties associated with reversing trophic state and ecological changes.

  • 116.
    Choudhury, Maidul I.
    et al.
    Lund Univ, Dept Biol Aquat Ecol, Ecol Bldg, SE-22362 Lund, Sweden;Swedish Univ Agr Sci, Dept Aquat Sci & Environm Assessment, Box 7050, S-75007 Uppsala, Sweden.
    Urrutia Cordero, Pablo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. HIFMB, Ammerlander Heerstr 231, D-26129 Oldenburg, Germany;Carl von Ossietzky Univ Oldenburg, Inst Chem & Biol Marine Environm ICBM, Schleusenstr 1, D-26382 Wilhelmshaven, Germany.
    Zhang, Huan
    Lund Univ, Dept Biol Aquat Ecol, Ecol Bldg, SE-22362 Lund, Sweden;Chinese Acad Sci, Inst Hydrobiol, Wuhan 430072, Hubei, Peoples R China.
    Ekvall, Mattias K.
    Lund Univ, Dept Biol Aquat Ecol, Ecol Bldg, SE-22362 Lund, Sweden;Cty Adm Board Skane Environm & Climate, Sodergaten 5, S-20515 Malmo, Sweden.
    Medeiros, Leonardo Rafael
    Lund Univ, Dept Biol Aquat Ecol, Ecol Bldg, SE-22362 Lund, Sweden;Fed Inst Educ Sci & Technol Rio Grande do Norte I, BR-59508000 Mossoro, RN, Brazil.
    Hansson, Lars-Anders
    Lund Univ, Dept Biol Aquat Ecol, Ecol Bldg, SE-22362 Lund, Sweden.
    Charophytes collapse beyond a critical warming and brownification threshold in shallow lake systems2019Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 661, s. 148-154Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Charophytes play a critical role for the functioning of shallow lake ecosystems. Although growth of charophytes can be limited by many factors, such as temperature, nutrients and light availability, our understanding about concomitant effects of climate warming and other large-scale environmental perturbations, e.g. increases in humic matter content ('brownification') is still limited. Here we conducted an outdoor mesocosm experiment during 71 days with a common charophyte species, Chara vulgaris, along an increasing gradient of temperature and brownification. We hypothesized the growth of C. vulgaris to increase with temperature, but to level off along the combined temperature and brownification gradient when reaching a critical threshold for light limitation via brownification. We show that C. vulgaris increases the relative growth rate (RGR), main and total shoot elongation, as well as number of lateral shoots when temperature and brownification increased by +2 degrees C and + 100%, respectively above today's levels. However, the RGR, shoot elongation and number of lateral shoots declined at further increment of temperature and brownification. Macrophyte weight-length ratio decreased with increased temperature and brownification, indicating that C. vulgaris allocate more resources or energy for shoot elongation instead of biomass increase at warmer temperatures and higher brownification. Our study shows that C. vulgaris will initially benefit from warming and brownification but will then decline as a future scenario of increased warming and brownification reaches a certain threshold level, in case of our experiment at +4 degrees C and a 2-fold increase in brownification above today's levels. 

  • 117.
    Christel, Stephan
    et al.
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMiS, S-39182 Kalmar, Sweden..
    Fridlund, Jimmy
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMiS, S-39182 Kalmar, Sweden..
    Buetti-Dinh, Antoine
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMiS, S-39182 Kalmar, Sweden..
    Buck, Moritz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Watkin, Elizabeth L.
    Curtin Univ, Sch Biomed Sci, CHIRI Biosci, Perth, WA 6845, Australia..
    Dopson, Mark
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMiS, S-39182 Kalmar, Sweden..
    RNA transcript sequencing reveals inorganic sulfur compound oxidation pathways in the acidophile Acidithiobacillus ferrivorans2016Inngår i: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 363, nr 7, artikkel-id fnw057Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Acidithiobacillus ferrivorans is an acidophile implicated in low-temperature biomining for the recovery of metals from sulfide minerals. Acidithiobacillus ferrivorans obtains its energy from the oxidation of inorganic sulfur compounds, and genes encoding several alternative pathways have been identified. Next-generation sequencing of At. ferrivorans RNA transcripts identified the genes coding for metabolic and electron transport proteins for energy conservation from tetrathionate as electron donor. RNA transcripts suggested that tetrathionate was hydrolyzed by the tetH1 gene product to form thiosulfate, elemental sulfur and sulfate. Despite two of the genes being truncated, RNA transcripts for the SoxXYZAB complex had higher levels than for thiosulfate quinone oxidoreductase (doxDA genes). However, a lack of heme-binding sites in soxX suggested that DoxDA was responsible for thiosulfate metabolism. Higher RNA transcript counts also suggested that elemental sulfur was metabolized by heterodisulfide reductase (hdr genes) rather than sulfur oxygenase reductase (sor). The sulfite produced as a product of heterodisulfide reductase was suggested to be oxidized by a pathway involving the sat gene product or abiotically react with elemental sulfur to form thiosulfate. Finally, several electron transport complexes were involved in energy conservation. This study has elucidated the previously unknown At. ferrivorans tetrathionate metabolic pathway that is important in biomining.

  • 118. Cole, J.J.
    et al.
    Prairie, Y. T.
    Caraco, N. F.
    McDowell, W. H.
    Tranvik, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Striegl, R. G.
    Duarte, C. M.
    Kortelainen, P.
    Downing, J. A.
    Middelburg, J. J.
    Melack, J.
    Plumbing the global carbon cycle: Integrating inland waters into the terrestrial carbon budget2007Inngår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 10, nr 1, s. 172-185Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Because freshwater covers such a small fraction of the Earth’s surface area, inland freshwater ecosystems (particularly lakes, rivers, and reservoirs) have rarely been considered as potentially important quantitative components of the carbon cycle at either global or regional scales. By taking published estimates of gas exchange, sediment accumulation, and carbon transport for a variety of aquatic systems, we have constructed a budget for the role of inland water ecosystems in the global carbon cycle. Our analysis conservatively estimates that inland waters annually receive, from a combination of background and anthropogenically altered sources, on the order of 1.9 Pg C y−1 from the terrestrial landscape, of which about 0.2 is buried in aquatic sediments, at least 0.8 (possibly much more) is returned to the atmosphere as gas exchange while the remaining 0.9 Pg y−1 is delivered to the oceans, roughly equally as inorganic and organic carbon. Thus, roughly twice as much C enters inland aquatic systems from land as is exported from land to the sea. Over prolonged time net carbon fluxes in aquatic systems tend to be greater per unit area than in much of the surrounding land. Although their area is small, these freshwater aquatic systems can affect regional C balances. Further, the inclusion of inland, freshwater ecosystems provides useful insight about the storage, oxidation and transport of terrestrial C, and may warrant a revision of how the modern net C sink on land is described.

  • 119.
    Comte, Jerome
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Lindström, Eva
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Eiler, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Langenheder, Silke
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Can marine bacteria be recruited from freshwater sources and the air?2014Inngår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 8, nr 12, s. 2423-2430Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is now clear evidence that microorganisms present biogeographic patterns, yet the processes that create and maintain them are still not well understood. In particular, the contribution of dispersal and its exact impact on local community composition is still unclear. For example, dispersing cells may not thrive in recipient environments, but may still remain part of the local species pool. Here, we experimentally tested if marine bacteria can be retrieved from freshwater communities (pelagic and sediment) and the atmosphere by exposing bacteria from three lakes, that differ in their proximity to the Norwegian Sea, to marine conditions. We found that the percentage of freshwater taxa decreased with increasing salinities, whereas marine taxa increased along the same gradient. Our results further showed that this increase was stronger for lake and sediment compared with air communities. Further, significant increases in the average niche breadth of taxa were found for all sources, and in particular lake water and sediment communities, at higher salinities. Our results therefore suggests that marine taxa can readily grow from freshwater sources, but that the response was likely driven by the growth of habitat generalists that are typically found in marine systems. Finally, there was a greater proportion of marine taxa found in communities originating from the lake closest to the Norwegian Sea. In summary, this study shows that the interplay between bacterial dispersal limitation and dispersal from internal and external sources may have an important role for community recovery in response to environmental change.

  • 120.
    Comte, Jérôme
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Berga, Mercè
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Biological Oceanography, Leibniz-Institute for Baltic Sea Research, Germany.
    Severin, Ina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Logue, Jürg Brendan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Contribution of different bacterial dispersal sources to lakes: Population and community effects in different seasons2017Inngår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 19, nr 6, s. 2391-2404Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The diversity and composition of lake bacterial communities are driven by the interplay between local contemporary environmental conditions and dispersal of cells from the surroundings, i.e. the metacommunity. Still, a conceptual understanding ofthe relative importance of the two types of factors is lacking. For instance, it is unknown which sources ofdispersal are most important and under which circumstances. Here, we investigated the seasonal variation in the importance of dispersal from different sources (mixing, precipitation, surface runoff and sediment resuspension) for lake bacterioplankton community and population dynamics. For that purpose, two small forest lakes and their dispersal sources were sampled over a period of 10 months.The influence of dispersal on communities and populations was determined by 454 sequencing of the 16S rRNA gene and Source Tracker analysis. On the community level direct effects of dispersal were questionable from all sources. Instead we found that the community of the preceding sampling occasion, representing growth of resident bacteria, was of great importance. On the population level, however, dispersal of individual taxa from the inlet could be occasionally important even under low water flow. The effect of sediment resuspension and precipitation appeared small.

  • 121.
    Comte, Jérôme
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Environm & Climate Change Canada, Canada Ctr Inland Waters, Watershed Hydrol & Ecol Res Div, Water Sci & Technol, Burlington, ON L7S 1A1, Canada..
    Langenheder, Silke
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Berga, Mercè
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Leibniz Inst Balt Sea Res, Biol Oceanog, Seestr 15, D-18119 Rostock, Germany..
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Contribution of different dispersal sources to the metabolic response of lake bacterioplankton following a salinity change2017Inngår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 19, nr 1, s. 251-260Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dispersal can modify how bacterial community composition (BCC) changes in response to environmental perturbations, yet knowledge about the functional consequences of dispersal is limited. Here we hypothesize that changes in bacterial community production in response to a salinity disturbance depend on the possibility to recruit cells from different dispersal sources. To investigate this, we conducted an in situ mesocosm experiment where bacterial communities of an oligotrophic lake were exposed to different salinities (0, 18, 36 psu) for two weeks and subjected to dispersal of cells originating from sediments, air (mesocosms open to air deposition), both or none. BCC was determined using 454 pyrosequencing of the 16S rRNA gene and bacterial production was measured by 3H leucine uptake. Bacterial production differed significantly among salinity treatments and dispersal treatments, being highest at high salinity. These changes were associated with changes in BCC and it was found that the identity of the main functional contributors differed at different salinities. Our results further showed that after a salinity perturbation, the response of bacterial communities depended on the recruitment of taxa, including marine representatives (e.g. Alphaproteobacteria Loktanella, Erythrobacter and the Gammaproteobacterium Rheiheimera) from dispersal sources, in which atmospheric deposition appeared to play a major role.

  • 122.
    Corcoll, Natalia
    et al.
    Univ Gothenburg, Dept Biol & Environm Sci, Box 461, SE-40530 Gothenburg, Sweden..
    Osterlund, Tobias
    Chalmers, Dept Math Sci, SE-41296 Gothenburg, Sweden..
    Sinclair, Lucas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Eiler, Alexander
    Uppsala universitet, Science for Life Laboratory, SciLifeLab. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Kristiansson, Erik
    Chalmers, Dept Math Sci, SE-41296 Gothenburg, Sweden..
    Backhaus, Thomas
    Univ Gothenburg, Dept Biol & Environm Sci, Box 461, SE-40530 Gothenburg, Sweden..
    Eriksson, K. Martin
    Chalmers, Dept Mech & Maritime Sci, SE-41296 Gothenburg, Sweden..
    Comparison of four DNA extraction methods for comprehensive assessment of 16S rRNA bacterial diversity in marine biofilms using high-throughput sequencing2017Inngår i: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 364, nr 14, artikkel-id fnx139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High-throughput DNA sequencing technologies are increasingly used for the metagenomic characterisation of microbial biodiversity. However, basic issues, such as the choice of an appropriate DNA extraction method, are still not resolved for non-model microbial communities. This study evaluates four commonly used DNA extraction methods for marine periphyton biofilms in terms of DNA yield, efficiency, purity, integrity and resulting 16S rRNA bacterial diversity. Among the tested methods, the Plant DNAzol (R) Reagent (PlantDNAzol) and the FastDNA (R) SPIN Kit for Soil (FastDNA Soil) methods were best suited to extract high quantities of DNA (77-130 mu g g wet wt(-1)). Lower amounts of DNA were obtained (<37 mu g g wet wt(-1)) with the Power Plant (R) Pro DNA Isolation Kit (PowerPlant) and the Power Biofilm (R) DNA Isolation Kit (PowerBiofilm) methods, but integrity and purity of the extracted DNA were higher. Results from 16S rRNA amplicon sequencing demonstrate that the choice of a DNA extraction method significantly influences the bacterial community profiles generated. A higher number of bacterial OTUs were detected when DNA was extracted with the PowerBiofilm and the PlantDNAzol methods. Overall, this study demonstrates the potential bias in metagenomic diversity estimates associated with different DNA extraction methods.

  • 123.
    Corell, Hanna
    et al.
    DHI Sverige AB.
    Nissling, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Modelling of larval dispersal of Baltic flounder (Platichthys solemdali) revealed drifting depth as a major factor determining opportunities for local retention vs large-scale connectivity2019Inngår i: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 218, s. 127-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For flatfishes, transportation of larvae to nursery areas is regarded a key mechanism for recruitment, with adaptations in larval behaviour to reach a suitable habitat. Here we model different possibilities of larval drifting of coastal spawning Baltic flounder Platichthys solemdali (recently identified as a species from European flounder P. flesus) to reveal opportunities for local retention vs large-scale dispersal to ensure settling in coastal nursery areas. Drifting depth, duration of drifting and effects of year and time during season were modelled using 1) a high-resolution local dispersal model, and 2) a large-scale connectivity database. The outcome revealed drifting depth as a major factor affecting larval dispersal. Drift at 10-22 m depth involved retention along the coast with the majority of larvae (>= 94% or 69-93% according to 1 and 2, respectively) with end points <= 20 km from the coast enabling further successful migration to nursery habitats. Contrary, larval drift close to the surface resulted in advection with end points in the open sea (72-76%), i.e. loss of larvae, but with a small fraction (5-12%) displaying cross-basin connectivity. The results suggest, in agreement with depth distribution of spawning, a larval behaviour promoting drift in the lower part of the water mass, favouring retention close to coastal nursery areas. Obtained dispersal patterns may sustain both local recruitment but also connectivity with other areas, potentially explaining the low genetic diversity between areas for P. solemdali. Low inter-annual variability in dispersal patterns when drifting at 10-22 m depth suggests that larval drift is not a major bottleneck explaining recruitment variability in P. solemdali in the area. The study highlights the differences in life-history strategies of the species pair of flounder in the Baltic Sea; P. flesus spawning in the deep basins with extensive larval dispersal, and coastal spawning P. solemdali with, according to the model outcome, mainly local larval dispersal for sustaining a viable population, i.e. request for different management strategies.

    Fulltekst tilgjengelig fra 2021-05-29 17:00
  • 124.
    Creed, Irena F.
    et al.
    Univ Saskatchewan, Sch Environm & Sustainabil, Saskatoon, SK, Canada.
    Bergstrom, Ann-Kristin
    Umea Univ, Dept Ecol & Environm Sci, Umea, Sweden.
    Trick, Charles G.
    Western Univ, Interfac Program Publ Hlth, London, ON, Canada;Western Univ, Dept Biol, London, ON, Canada.
    Grimm, Nancy B.
    Arizona State Univ, Sch Life Sci, Tempe, AZ USA.
    Hessen, Dag O.
    Univ Oslo, Sect Aquat Biol & Toxicol, Oslo, Norway.
    Karlsson, Jan
    Umea Univ, Climate Impacts Res Ctr, Dept Ecol & Environm Sci, Umea, Sweden.
    Kidd, Karen A.
    Univ New Brunswick, Dept Biol, St John, NB, Canada;Univ New Brunswick, Canadian Rivers Inst, St John, NB, Canada.
    Kritzberg, Emma
    Lund Univ, Dept Biol, Lund, Sweden.
    McKnight, Diane M.
    Univ Colorado, INSTAAR, Boulder, CO 80309 USA.
    Freeman, Erika C.
    Western Univ, Dept Geog, London, ON, Canada.
    Senar, Oscar E.
    Western Univ, Dept Geog, London, ON, Canada.
    Andersson, Agneta
    Umea Univ, Dept Ecol & Environm Sci, Umea, Sweden.
    Ask, Jenny
    Umea Univ, Dept Ecol & Environm Sci, Umea, Sweden.
    Berggren, Martin
    Lund Univ, Dept Phys Geog & Ecosyst Sci, Lund, Sweden.
    Cherif, Mehdi
    Umea Univ, Dept Ecol & Environm Sci, Umea, Sweden.
    Giesler, Reiner
    Umea Univ, Climate Impacts Res Ctr, Dept Ecol & Environm Sci, Umea, Sweden.
    Hotchkiss, Erin R.
    Virginia Polytech Inst & State Univ, Dept Biol Sci, Blacksburg, VA 24061 USA.
    Kortelainen, Pirkko
    Finnish Environm Inst, Helsinki, Finland.
    Palta, Monica M.
    Arizona State Univ, Sch Life Sci, Tempe, AZ USA.
    Vrede, Tobias
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes2018Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, nr 8, s. 3692-3714Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.

  • 125. Cremona, Fabien
    et al.
    Laas, Alo
    Arvola, Lauri
    Pierson, Don
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Nõges, Peeter
    Nõges, Tiina
    Numerical Exploration of the Planktonic to Benthic Primary Production Ratios in Lakes of the Baltic Sea Catchment2016Inngår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, nr 8, s. 1386-1400Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Autotrophic structure refers to the partitioning of whole-ecosystem primary production between benthic and planktonic primary producers. Autotrophic structure remains poorly understood especially because of the paucity of estimates regarding benthic primary production. We used a conceptual model for numerically exploring the autotrophic structure of 13 hemiboreal lakes situated in the Baltic Sea catchment. We also used diel variations in primary production profiles to graphically evaluate levels of light and/or nutrient limitation in lakes. The input morphometric data, light extinction coefficients and dissolved carbon parameters were mostly obtained from in situ measurements. Results revealed that cross- and within-lake autotrophic structure varied greatly: one lake was clearly dominated by benthic production, and three lakes by phytoplankton production. In the rest, phytoplankton production was generally dominant but switch to benthic dominance was possible. The modelled primary production profiles varied according to lake water clarity and bathymetry. Our results clearly indicate that the relative contribution of benthic primary production to whole-lake primary production should be taken into account in studies about hemiboreal and boreal lakes.

  • 126.
    Csitári, Bianka
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Macrophyte cover and groundwater as the key drivers of the extremelyhigh organic carbon concentration of soda pans2019Dataset
  • 127. Daneshvar, Atlasi
    et al.
    Aboulfadl, Khadija
    Viglino, Liza
    Broseus, Romain
    Sauve, Sebastien
    Madoux-Humery, Anne-Sophie
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Prevost, Michele
    Evaluating pharmaceuticals and caffeine as indicators of fecal contamination in drinking water sources of the Greater Montreal region2012Inngår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 88, nr 1, s. 131-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We surveyed four different river systems in the Greater Montreal region, upstream and downstream of entry points of contamination, from April 2007 to January 2009. The studied compounds belong to three different groups: PPCPs (caffeine, carbamazepine, naproxen, gemfibrozil, and trimethoprim), hormones (progesterone, estrone, and estradiol), and triazine herbicides and their metabolites (atrazine, deethylatrazine, deisopropylatrazine, simazine, and cyanazine). In the system A. B, and C having low flow rate and high TOC, we observed the highest detection frequencies and mass flows of PPCPs compared to the other compounds, reflecting discharge of urban contaminations through WWTPs and CSOs. However, in River D, having high flow rate and low TOC, comparable frequency of detection of triazine and their by-products and PPCPs, reflecting cumulative loads of these compounds from the Great Lakes as well as persistency against natural attenuation processes. Considering large differences in the removal efficiencies of caffeine and carbamazepine, a high ratio of caffeine/carbamazepine might be an indicative of a greater proportion of raw sewage versus treated wastewater in surface waters. In addition, caffeine appeared to be a promising indicator of recent urban fecal contaminations, as shown by the significant correlation with FC (R-2 = 0.45), while carbamazepine is a good indicator of cumulative persistence compounds.

  • 128. Daneshvar, Atlasi
    et al.
    Svanfelt, Jesper
    Kronberg, Leif
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Neglected sources of pharmaceuticals in river water: footprints of a Reggae festival2012Inngår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 14, nr 2, s. 596-603Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wastewater treatment plants (WWTPs) are commonly considered as the main source of pharmaceuticals in surface waters. Here, however, we show that an open-air festival, attracting approximately 10 000 visitors per year at the shores of River Fyris upstream of Uppsala WWTP, can temporarily result in a higher pharmaceutical input into the river water than the WWTP. Studying the influence of Uppsala Reggae festival on the occurrence of ten commonly used acidic and basic pharmaceuticals upstream, in the effluent, and downstream of the Uppsala WWTP, we found that occasional heavy rainfalls during the festival in 2008 severely increased the mass flows of all pharmaceuticals at the WWTP upstream site. Also, strong increases in ammonium (210-fold), nitrate (21-fold), and total nitrogen (21-fold) mass flows were observed. The pharmaceutical mass flows at the upstream site were up to 3.4 times higher than those observed in the WWTP effluent. In contrast, in 2009, the festival was not accompanied with rainfalls and no major additional input of pharmaceuticals and nitrogen was observed. The findings of this study give new insights into risk assessments and are relevant for monitoring programmes.

  • 129.
    de Melo, Michaela L
    et al.
    Departamento de Hidrobiologia, Universidade Federal de São Carlos, São Carlos, Brazil.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Amaral, João Henrique F
    Coordenação de Dinâmica Ambiental, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil.
    Barbosa, Pedro M
    Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
    Forsberg, Bruce R
    Coordenação de Dinâmica Ambiental, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil.
    Sarmento, Hugo
    Departamento de Hidrobiologia, Universidade Federal de São Carlos, São Carlos, Brazil.
    Flood pulse regulation of bacterioplankton community composition in an Amazonian floodplain lake2019Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 64, nr 1, s. 108-120Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding spatial and temporal dynamics of microbial communities is a central challenge in microbial ecology since microorganisms play a key role in ecosystem functioning and biogeochemical cycles. Amazonian aquatic systems comprise a dynamic mosaic of heterogeneous habits but are understudied and there is limited information about the mechanisms that shape bacterial community composition (BCC). There is a consensus that environmental selection (species sorting) and dispersal processes (source?sink dynamics) act in concert to shape the composition of these communities, but the relative importance of each mechanism may vary dramatically through time and between systems. Applying 16S rRNA gene amplicon high-throughput sequencing, we studied factors and processes that modulate BCC in an Amazonian floodplain lake and used source-tracking models to trace the main dispersal sources of microorganisms in the whole floodplain system during a full hydrological cycle. Our source-tracking models indicated that dispersal processes were predominant, explaining most of the BCC variability throughout the study period. We observed more sources contributing to the sink community during the falling water than rising water period, when contributions from the Solim?es River dominated. There was a clear seasonal pattern in BCC, closely related to environmental variables, suggesting that the successful establishment of dispersing bacteria also depends on environmental filtering that is linked to water flow. In summary, source?sink dynamics and species sorting were strongly affected by water exchange and connectivity with the main river that varied throughout the flood pulse cycle. Our results demonstrated the influence of lateral transport and temporal dynamics on BCC in Amazonian floodplain lakes that could ultimately impact regional carbon budgets and biogeochemical cycles.

  • 130.
    de Wit, Heleen A.
    et al.
    Norwegian Inst Water Res NIVA, Gaustadalleen 21, N-0349 Oslo, Norway..
    Valinia, Salar
    Norwegian Inst Water Res NIVA, Gaustadalleen 21, N-0349 Oslo, Norway..
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Futter, Martyn N.
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Lennart Hjalms Vag 9, S-75007 Uppsala, Sweden..
    Kortelainen, Pirkko
    Finnish Environm Inst, POB 140, Helsinki 00251, Finland..
    Austnes, Kari
    Norwegian Inst Water Res NIVA, Gaustadalleen 21, N-0349 Oslo, Norway..
    Hessen, Dag O.
    Univ Oslo, Sect Aquat Biol & Toxicol, Dept Biosci, N-0316 Oslo, Norway..
    Räike, Antti
    Finnish Environm Inst, POB 140, Helsinki 00251, Finland..
    Laudon, Hjalmar
    Swedish Univ Agr Sci, Dept Forest Ecol & Management, S-90183 Umea, Sweden..
    Vuorenmaa, Jussi
    Finnish Environm Inst, POB 140, Helsinki 00251, Finland..
    Current Browning of Surface Waters Will Be Further Promoted by Wetter Climate2016Inngår i: ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS, ISSN 2328-8930, Vol. 3, nr 12, s. 430-435Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Browning of surface waters because of increasing terrestrial dissolved organic carbon (OC) concentrations is a concern for drinking water providers and can impact land carbon storage. We show that positive trends in OC in 474 streams, lakes, and rivers in boreal and subarctic ecosystems in Norway, Sweden, and Finland between 1990 and 2013 are surprisingly constant across climatic gradients and catchment sizes (median, +1.4% year(-1); interquartile range, +0.8-2.0% year(-1)), implying that water bodies across the entire landscape are browning. The largest trends (median, +1.7% year(-1)) were found in regions impacted by strong reductions in sulfur deposition, while subarctic regions showed the least browning (median, +0.8% year(-1)). In dry regions, precipitation was a strong and positive driver of OC concentrations, declining in strength moving toward high rainfall sites. We estimate that a 10% increase in precipitation will increase mobilization of OC from soils to freshwaters by at least 30%, demonstrating the importance of climate wetting for the carbon cycle. We conclude that upon future increases in precipitation, current browning trends will continue across the entire aquatic continuum, requiring expensive adaptations in drinking water plants, increasing land to sea export of carbon, and impacting aquatic productivity and greenhouse gas emissions.

  • 131. DeAngelis, Donald L.
    et al.
    Wolkowicz, Gail S. K.
    Lou, Yuan
    Jiang, Yuexin
    Novak, Mark
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Araujo, Marcio S.
    Jo, YoungSeung
    Cleary, Erin A.
    The Effect of Travel Loss on Evolutionarily Stable Distributions of Populations in Space2011Inngår i: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 178, nr 1, s. 15-29Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A key assumption of the ideal free distribution (IFD) is that there are no costs in moving between habitat patches. However, because many populations exhibit more or less continuous population movement between patches and traveling cost is a frequent factor, it is important to determine the effects of costs on expected population movement patterns and spatial distributions. We consider a food chain (tritrophic or bitrophic) in which one species moves between patches, with energy cost or mortality risk in movement. In the two-patch case, assuming forced movement in one direction, an evolutionarily stable strategy requires bidirectional movement, even if costs during movement are high. In the N-patch case, assuming that at least one patch is linked bidirectionally to all other patches, optimal movement rates can lead to source-sink dynamics where patches with negative growth rates are maintained by other patches with positive growth rates. As well, dispersal between patches is not balanced (even in the two-patch case), leading to a deviation from the IFD. Our results indicate that cost-associated forced movement can have important consequences for spatial metapopulation dynamics. Relevance to marine reserve design and the study of stream communities subject to drift is discussed.

  • 132. Del Sontro, Tonya
    et al.
    McGinnis, Daniel F.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Ostrovsky, Ilia
    Wehrli, Bernhard
    Extreme methane emissions from a Swiss hydropower reservoir: contribution from bubbling sediments2010Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, nr 7, s. 2419-2425Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Methane emission pathways and their importance were quantified during a yearlong survey of a temperate hydropower reservoir. Measurements using gas traps indicated very high ebullition rates, but due to the stochastic nature of ebullition a mass balance approach was crucial to deduce system-wide methane sources and losses. Methane diffusion from the sediment was generally low and seasonally stable and did not account for the high concentration of dissolved methane measured in the reservoir discharge. A strong positive correlation between water temperature and the observed dissolved methane concentration enabled us to quantify the dissolved methane addition from bubble dissolution using a system-wide mass balance. Finally, knowing the contribution due to bubble dissolution, we used a bubble model to estimate bubble emission directly to the atmosphere. Our results indicated that the total methane emission from Lake Wohlen was on average >150 mg CH4 m−2 d−1, which is the highest ever documented for a midlatitude reservoir. The substantial temperature-dependent methane emissions discovered in this 90-year-old reservoir indicate that temperate water bodies can be an important but overlooked methane source.

  • 133.
    Denfeld, Blaize A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Graduate School of Geography, Clark University.
    Frey, Karen E.
    Sobczak, William V.
    Holmes, Robert M.
    Mann, Paul J.
    Summer CO2 evasion from streams and rivers in the Kolyma River basin, north-east Siberia2013Inngår i: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 32, s. 19704-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Inland water systems are generally supersaturated in carbon dioxide (CO2) and are increasingly recognized as playing an important role in the global carbon cycle. The Arctic may be particularly important in this respect, given the abundance of inland waters and carbon contained in Arctic soils; however, a lack of trace gas measurements from small streams in the Arctic currently limits this understanding.We investigated the spatial variability of CO2 evasion during the summer low-flow period from streams and rivers in the northern portion of the Kolyma River basin in north-eastern Siberia. To this end, partial pressure of carbon dioxide (pCO2) and gas exchange velocities (k) were measured at a diverse set of streams and rivers to calculate CO2 evasion fluxes. We combined these CO2 evasion estimates with satellite remote sensing and geographic information system techniques to calculate total areal CO2 emissions. Our results show that small streams are substantial sources of atmospheric CO2 owing to high pCO2 and k, despite being a small portion of total inland water surface area. In contrast, large rivers were generally near equilibrium with atmospheric CO2. Extrapolating our findings across the Panteleikha-Ambolikha sub-watersheds demonstrated that small streams play a major role in CO2 evasion, accounting for 86% of the total summer CO2emissions from inland waters within these two sub-watersheds. Further expansion of these regional CO2emission estimates across time and space will be critical to accurately quantify and understand the role of Arctic streams and rivers in the global carbon budget.

  • 134.
    Denfeld, Blaize A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Wallin, Marcus B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Sahlée, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Kokic, Jovana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Chmiel, Hannah E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Temporal and spatial carbon dioxide concentration patterns in a small boreal lake in relation to ice cover dynamics2015Inngår i: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 20, nr 6, s. 679-692Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Global carbon dioxide (CO2) emission estimates from inland waters commonly neglect the ice-cover season. To account for CO2 accumulation below ice and consequent emissions into the atmosphere at ice-melt we combined automatically-monitored and manually- sampled spatially-distributed CO2 concentration measurements from a small boreal ice-covered lake in Sweden. In early winter, CO2 accumulated continuously below ice, whereas, in late winter, CO2 concentrations remained rather constant. At ice-melt, two CO2 concentration peaks were recorded, the first one reflecting lateral CO2 transport within the upper water column, and the second one reflecting vertical CO2 transport from bottom waters. We estimated that 66%–85% of the total CO2 accumulated in the water below ice left the lake at ice-melt, while the remainder was stored in bottom waters. Our results imply that CO2 accumulation under ice and emissions at ice-melt are more dynamic than previously reported, and thus need to be more accurately integrated into annual CO2 emission estimates from inland waters.

  • 135.
    Denfeld, Blaize Amber
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Greenhouse Gas Dynamics in Ice-covered Lakes Across Spatial and Temporal Scales2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Lakes play a major role in the global carbon (C) cycle, despite making up a small area of earth’s surface. Lakes receive, transport and process sizable amounts of C, emitting a substantial amount of the greenhouse gases, carbon dioxide (CO2) and methane (CH4), into the atmosphere. Ice-covered lakes are particularly sensitive to climate change, as future reductions to the duration of lake ice cover will have profound effects on the biogeochemical cycling of C in lakes. It is still largely unknown how reduced ice cover duration will affect CO2 and CH4 emissions from ice-covered lakes. Thus, the primary aim of this thesis was to fill this knowledge gap by monitoring the spatial and temporal dynamics of CO2 and CH4 in ice-covered lakes. The results of this thesis demonstrate that below ice CO2 and CH4 were spatially and temporally variable. Nutrients were strongly linked to below ice CO2 and CH4 oxidation variations across lakes. In addition, below ice CO2 was generally highest in small shallow lakes, and in bottom waters. Whilst below ice CH4 was elevated in surface waters near where bubbles from anoxic lake sediment were trapped. During the ice-cover period, CO2 accumulation below ice was not linear, and at ice-melt incomplete mixing of lake waters resulted in a continued CO2 storage in bottom waters. Further, CO2 transported from the catchment and bottom waters contributed to high CO2 emissions. The collective findings of this thesis indicate that CO2 and CH4 emissions from ice-covered lakes will likely increase in the future. The strong relationship between nutrients and C processes below ice, imply that future changes to nutrient fluxes within lakes will influence the biogeochemical cycling of C in lakes. Since catchment and lake sediment C fluxes play a considerable role in below ice CO2 and CH4 dynamics, changes to hydrology and thermal stability of lakes will undoubtedly alter CO2 and CH4 emissions. Nevertheless, ice-covered lakes constitute a significant component of the global C cycle, and as such, should be carefully monitored and accounted for when addressing the impacts of global climate change.  

    Delarbeid
    1. Regional Variability and Drivers of Below Ice CO2 in Boreal and Subarctic Lakes
    Åpne denne publikasjonen i ny fane eller vindu >>Regional Variability and Drivers of Below Ice CO2 in Boreal and Subarctic Lakes
    Vise andre…
    2016 (engelsk)Inngår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, nr 3, s. 461-476Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Northern lakes are ice-covered for considerable portions of the year, where carbon dioxide (CO2) can accumulate below ice, subsequently leading to high CO2 emissions at ice-melt. Current knowledge on the regional control and variability of below ice partial pressure of carbon dioxide (pCO(2)) is lacking, creating a gap in our understanding of how ice cover dynamics affect the CO2 accumulation below ice and therefore CO2 emissions from inland waters during the ice-melt period. To narrow this gap, we identified the drivers of below ice pCO(2) variation across 506 Swedish and Finnish lakes using water chemistry, lake morphometry, catchment characteristics, lake position, and climate variables. We found that lake depth and trophic status were the most important variables explaining variations in below ice pCO(2) across the 506 lakes(.) Together, lake morphometry and water chemistry explained 53% of the site-to-site variation in below ice pCO(2). Regional climate (including ice cover duration) and latitude only explained 7% of the variation in below ice pCO(2). Thus, our results suggest that on a regional scale a shortening of the ice cover period on lakes may not directly affect the accumulation of CO2 below ice but rather indirectly through increased mobility of nutrients and carbon loading to lakes. Thus, given that climate-induced changes are most evident in northern ecosystems, adequately predicting the consequences of a changing climate on future CO2 emission estimates from northern lakes involves monitoring changes not only to ice cover but also to changes in the trophic status of lakes.

    Emneord
    CO2; winter limnology; ice cover; carbon; nutrients; lake depth
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-275017 (URN)10.1007/s10021-015-9944-z (DOI)000373018200007 ()
    Forskningsfinansiär
    Swedish Research CouncilSwedish Research Council FormasEU, European Research Council
    Tilgjengelig fra: 2016-01-27 Laget: 2016-01-27 Sist oppdatert: 2018-05-21bibliografisk kontrollert
    2. Temporal and spatial carbon dioxide concentration patterns in a small boreal lake in relation to ice cover dynamics
    Åpne denne publikasjonen i ny fane eller vindu >>Temporal and spatial carbon dioxide concentration patterns in a small boreal lake in relation to ice cover dynamics
    Vise andre…
    2015 (engelsk)Inngår i: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 20, nr 6, s. 679-692Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Global carbon dioxide (CO2) emission estimates from inland waters commonly neglect the ice-cover season. To account for CO2 accumulation below ice and consequent emissions into the atmosphere at ice-melt we combined automatically-monitored and manually- sampled spatially-distributed CO2 concentration measurements from a small boreal ice-covered lake in Sweden. In early winter, CO2 accumulated continuously below ice, whereas, in late winter, CO2 concentrations remained rather constant. At ice-melt, two CO2 concentration peaks were recorded, the first one reflecting lateral CO2 transport within the upper water column, and the second one reflecting vertical CO2 transport from bottom waters. We estimated that 66%–85% of the total CO2 accumulated in the water below ice left the lake at ice-melt, while the remainder was stored in bottom waters. Our results imply that CO2 accumulation under ice and emissions at ice-melt are more dynamic than previously reported, and thus need to be more accurately integrated into annual CO2 emission estimates from inland waters.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-267129 (URN)000366959400002 ()
    Forskningsfinansiär
    Swedish Research CouncilSwedish Research Council FormasEU, European Research Council
    Tilgjengelig fra: 2015-11-18 Laget: 2015-11-18 Sist oppdatert: 2018-05-21bibliografisk kontrollert
    3. Methane oxidation at the water-ice interface of an ice-covered lake
    Åpne denne publikasjonen i ny fane eller vindu >>Methane oxidation at the water-ice interface of an ice-covered lake
    Vise andre…
    2016 (engelsk)Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 61, nr S1, s. S78-S90Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Lakes are important components of the global methane (CH4) cycle. In seasonally ice-covered lakes, CH4 transported by ebullition (bubbling) from anoxic sediments gets trapped at the water-ice interface. If not oxidized by methane-oxidizing bacteria (MOB), this can potentially lead to high episodic CH4 emissions at ice-melt. To understand the fate of CH4 trapped below ice, we measured depth-distributions of CH4 concentrations in the water column near bubbles trapped below ice in Lake Erken. We also performed a 21 d incubation experiment at low temperature (2.3 ± 0.2°C) to investigate the potential for CH4 oxidation. During most sampling occasions, we found steep CH4 concentration gradients just below the ice with a 13-fold decrease from the surface to a depth of 20 cm. In vitro incubations revealed that CH4oxidation can occur at low temperatures typical for the water-ice interface. CH4 oxidation was observed as a significant decrease in CH4 concentration, a significant increase in stable isotope 13C signature, and an increase in MOB during the incubation. Thus, CH4 accumulating in the top 20 cm of the water column, fed by diffusion from CH4 in trapped bubbles, may fuel significant CH4 oxidation. Since northern latitude lakes can be ice-covered for many months of the year and significant amounts of CH4 accumulate below the ice, the extent of CH4oxidation under these low temperature-conditions is important for understanding the potential CH4 emissions to the atmosphere during ice-melt.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-274392 (URN)10.1002/lno.10288 (DOI)000388560900007 ()
    Forskningsfinansiär
    Swedish Research CouncilSwedish Research Council Formas
    Tilgjengelig fra: 2016-01-21 Laget: 2016-01-21 Sist oppdatert: 2018-01-10bibliografisk kontrollert
    4. Constraints on methane oxidation in ice-covered boreal lakes
    Åpne denne publikasjonen i ny fane eller vindu >>Constraints on methane oxidation in ice-covered boreal lakes
    Vise andre…
    2016 (engelsk)Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, nr 7, s. 1924-1933Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Boreal lakes can be ice covered for a substantial portion of the year at which time methane (CH4) can accumulate below ice. The amount of CH4 emitted at ice melt is partially determined by the interplay between CH4 production and CH4 oxidation, performed by methane-oxidizing bacteria (MOB). Yet the balance between oxidation and emission and the potential for CH4 oxidation in various lakes during winter is largely unknown. To address this, we performed incubations at 2 degrees C to screen for wintertime CH4 oxidation potential in seven lakes. Results showed that CH4 oxidation was restricted to three lakes, where the phosphate concentrations were highest. Molecular analyses revealed that MOB were initially detected in all lakes, although an increase in type I MOB only occurred in the three lake water incubations where oxidation could be observed. Accordingly, the increase in CO2 was on average 5 times higher in these three lake water incubations. For one lake where no oxidation was measured, we tested if temperature and CH4 availability could trigger CH4 oxidation. However, regardless of incubation temperatures and CH4 concentrations, ranging from 2 to 20 degrees C and 1-500M, respectively, no oxidation was observed. Our study indicates that some lakes with active wintertime CH4 oxidation may have low emissions during ice melt, while other and particularly nutrient poor lakes may accumulate large amounts of CH4 below ice that, in the absence of CH4 oxidation, will be emitted following ice melt. This variability in CH4 oxidation rates between lakes needs to be accounted for in large-scale CH4 emission estimates.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-274393 (URN)10.1002/2016JG003382 (DOI)000382581900015 ()
    Forskningsfinansiär
    Swedish Research CouncilSwedish Research Council FormasCarl Tryggers foundation
    Merknad

    De två första författarna delar förstaförfattarskapet.

    Tilgjengelig fra: 2016-01-21 Laget: 2016-01-21 Sist oppdatert: 2017-11-30bibliografisk kontrollert
  • 136.
    Denfeld, Blaize
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Kortelainen, Pirkko
    Finnish Environment Institute.
    Rantakari, Miitta
    Department of Environmental Sciences, University of Helsinki.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Weyhenmeyer, Gesa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Regional Variability and Drivers of Below Ice CO2 in Boreal and Subarctic Lakes2016Inngår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, nr 3, s. 461-476Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Northern lakes are ice-covered for considerable portions of the year, where carbon dioxide (CO2) can accumulate below ice, subsequently leading to high CO2 emissions at ice-melt. Current knowledge on the regional control and variability of below ice partial pressure of carbon dioxide (pCO(2)) is lacking, creating a gap in our understanding of how ice cover dynamics affect the CO2 accumulation below ice and therefore CO2 emissions from inland waters during the ice-melt period. To narrow this gap, we identified the drivers of below ice pCO(2) variation across 506 Swedish and Finnish lakes using water chemistry, lake morphometry, catchment characteristics, lake position, and climate variables. We found that lake depth and trophic status were the most important variables explaining variations in below ice pCO(2) across the 506 lakes(.) Together, lake morphometry and water chemistry explained 53% of the site-to-site variation in below ice pCO(2). Regional climate (including ice cover duration) and latitude only explained 7% of the variation in below ice pCO(2). Thus, our results suggest that on a regional scale a shortening of the ice cover period on lakes may not directly affect the accumulation of CO2 below ice but rather indirectly through increased mobility of nutrients and carbon loading to lakes. Thus, given that climate-induced changes are most evident in northern ecosystems, adequately predicting the consequences of a changing climate on future CO2 emission estimates from northern lakes involves monitoring changes not only to ice cover but also to changes in the trophic status of lakes.

  • 137.
    Denfeld, Blaize
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Umea Univ, Dept Ecol & Environm Sci, Umea, Sweden.
    Ricão Canelhas, Monica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Weyhenmeyer, Gesa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Eiler, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bastviken, David
    Linköping University, Department of Thematic Studies – Environmental Change .
    Constraints on methane oxidation in ice-covered boreal lakes2016Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, nr 7, s. 1924-1933Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Boreal lakes can be ice covered for a substantial portion of the year at which time methane (CH4) can accumulate below ice. The amount of CH4 emitted at ice melt is partially determined by the interplay between CH4 production and CH4 oxidation, performed by methane-oxidizing bacteria (MOB). Yet the balance between oxidation and emission and the potential for CH4 oxidation in various lakes during winter is largely unknown. To address this, we performed incubations at 2 degrees C to screen for wintertime CH4 oxidation potential in seven lakes. Results showed that CH4 oxidation was restricted to three lakes, where the phosphate concentrations were highest. Molecular analyses revealed that MOB were initially detected in all lakes, although an increase in type I MOB only occurred in the three lake water incubations where oxidation could be observed. Accordingly, the increase in CO2 was on average 5 times higher in these three lake water incubations. For one lake where no oxidation was measured, we tested if temperature and CH4 availability could trigger CH4 oxidation. However, regardless of incubation temperatures and CH4 concentrations, ranging from 2 to 20 degrees C and 1-500M, respectively, no oxidation was observed. Our study indicates that some lakes with active wintertime CH4 oxidation may have low emissions during ice melt, while other and particularly nutrient poor lakes may accumulate large amounts of CH4 below ice that, in the absence of CH4 oxidation, will be emitted following ice melt. This variability in CH4 oxidation rates between lakes needs to be accounted for in large-scale CH4 emission estimates.

  • 138.
    Dinasquet, Julie
    et al.
    Linnaeus Univ, Dept Nat Sci, Kalmar, Sweden.;Univ Copenhagen, Marine Biol Sect, Helsingor, Denmark.;Scripps Inst Oceanog, Div Marine Biol Res, La Jolla, CA 92093 USA..
    Richert, Inga
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. UFZ Helmholtz Ctr Environm Res, Microbial Ecosyst Serv Grp, Dept Environm Microbiol, Leipzig, Germany..
    Logares, Ramiro
    CSIC, Inst Marine Sci, Barcelona, Spain..
    Yager, Patricia
    Univ Georgia, Dept Marine Sci, Athens, GA 30602 USA..
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Riemann, Lasse
    Univ Copenhagen, Marine Biol Sect, Helsingor, Denmark..
    Mixing of water masses caused by a drifting iceberg affects bacterial activity, community composition and substrate utilization capability in the Southern Ocean2017Inngår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 19, nr 6, s. 2453-2467Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The number of icebergs produced from ice-shelf disintegration has increased over the past decade in Antarctica. These drifting icebergs mix the water column, influence stratification and nutrient condition, and can affect local productivity and food web composition. Data on whether icebergs affect bacterioplankton function and composition are scarce, however. We assessed the influence of iceberg drift on bacterial community composition and on their ability to exploit carbon substrates during summer in the coastal Southern Ocean. An elevated bacterial production and a different community composition were observed in iceberg-influenced waters relative to the undisturbed water column nearby. These major differences were confirmed in short-term incubations with bromodeoxyuridine followed by CARD-FISH. Furthermore, one-week bottle incubations amended with inorganic nutrients and carbon substrates (a mix of substrates, glutamine, Nacetylglucosamine, or pyruvate) revealed contrasting capacity of bacterioplankton to utilize specific carbon substrates in the iceberg-influenced waters compared with the undisturbed site. Our study demonstrates that the hydrographical perturbations introduced by a drifting iceberg can affect activity, composition, and substrate utilization capability of marine bacterioplankton. Consequently, in a context of global warming, increased frequency of drifting icebergs in polar regions holds the potential to affect carbon and nutrient biogeochemistry at local and possibly regional scales.

  • 139. Dominik, Janusz
    et al.
    Tagliapietra, Davide
    Garcia Bravo, Andrea G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Sigovini, Marco
    Spangenberg, Jorge E.
    Amouroux, David
    Zonta, Roberto
    Mercury in the food chain of the Lagoon of Venice, Italy2014Inngår i: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 88, nr 1-2, s. 194-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sediments and biota samples were collected in a restricted area of the Lagoon of Venice and analysed for total mercury, monomethyl mercury (MMHg), and nitrogen and carbon isotopes. Results were used to examine mercury biomagnification in a complex food chain. Sedimentary organic matter (SOM) proved to be a major source of nutrients and mercury to primary consumers. Contrary to inorganic mercury, MMHg was strongly biomagnified along the food chain, although the lognormal relationship between MMHg and δ15N was less constrained than generally reported from lakes or coastal marine ecosystems. The relationship improved when log MMHg concentrations were plotted against trophic positions derived from baseline δ15N estimate for primary consumers. From the regression slope a mean MMHg trophic magnification factor of 10 was obtained. Filter-feeding benthic bivalves accumulated more MMHg than other primary consumers and were probably important in MMHg transfer from sediments to higher levels of the food chain.

  • 140. Downing, J. A.
    et al.
    Cole, J. J.
    Duarte, C. M.
    Middelburg, J. J.
    Melack, J. M.
    Prairie, Y. T.
    Kortelainen, P.
    Striegl, R. G.
    McDowell, W. H.
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Global abundance and size distribution of streams and rivers2012Inngår i: Inland Waters, ISSN 2044-2041 (print), 2044-205X (online), Vol. 2, nr 4, s. 229-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To better integrate lotic ecosystems into global cycles and budgets, we provide approximations of the size-distribution and areal extent of streams and rivers. One approach we used was to employ stream network theory combined with data on stream width. We also used detailed stream networks on 2 continents to estimate the fraction of continental area occupied by streams worldwide and corrected remote sensing stream inventories for unresolved small streams. Our estimates of global fluvial area are 485 000 to 662 000 km2 and are +30–300% of published appraisals. Moderately sized rivers (orders 5–9) seem to comprise the greatest global area, with less area covered by low and high order streams, while global stream length, and therefore the riparian interface, is dominated by 1st order streams. Rivers and streams are likely to cover 0.30–0.56% of the land surface and make contributions to global processes and greenhouse gas emissions that may be +20–200% greater than those implied by previous estimates.

  • 141. Edberg, F.
    et al.
    Andersson, A. F.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Holmström, S. J. M.
    Microbial community analyzis and connection to Iron chemistry in a former uranium mine - Lake Tranebarssjon2010Inngår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 74, nr 12, s. A259-A259Artikkel i tidsskrift (Annet vitenskapelig)
  • 142.
    Eiler, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Drakare, S.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Pernthaler, J.
    Peura, S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Rofner, Carina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Simek, K.
    Yang, Yang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik.
    Znachor, P.
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Unveiling Distribution Patterns of Freshwater Phytoplankton by a Next Generation Sequencing Based Approach2013Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 1, s. e53516-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The recognition and discrimination of phytoplankton species is one of the foundations of freshwater biodiversity research and environmental monitoring. This step is frequently a bottleneck in the analytical chain from sampling to data analysis and subsequent environmental status evaluation. Here we present phytoplankton diversity data from 49 lakes including three seasonal surveys assessed by next generation sequencing (NGS) of 16S ribosomal RNA chloroplast and cyanobacterial gene amplicons and also compare part of these datasets with identification based on morphology. Direct comparison of NGS to microscopic data from three time-series showed that NGS was able to capture the seasonality in phytoplankton succession as observed by microscopy. Still, the PCR-based approach was only semi-quantitative, and detailed NGS and microscopy taxa lists had only low taxonomic correspondence. This is probably due to, both, methodological constraints and current discrepancies in taxonomic frameworks. Discrepancies included Euglenophyta and Heterokonta that were scarce in the NGS but frequently detected by microscopy and Cyanobacteria that were in general more abundant and classified with high resolution by NGS. A deep-branching taxonomically unclassified cluster was frequently detected by NGS but could not be linked to any group identified by microscopy. NGS derived phytoplankton composition differed significantly among lakes with different trophic status, showing that our approach can resolve phytoplankton communities at a level relevant for ecosystem management. The high reproducibility and potential for standardization and parallelization makes our NGS approach an excellent candidate for simultaneous monitoring of prokaryotic and eukaryotic phytoplankton in inland waters.

  • 143.
    Eiler, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hayakawa, Darin H
    Rappé, Michael S
    Non-random assembly of bacterioplankton communities in the subtropical North Pacific Ocean2011Inngår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 2Artikkel i tidsskrift (Fagfellevurdert)
  • 144.
    Eiler, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Heinrich, Friederike
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Coherent dynamics and association networks among lake bacterioplankton taxa2012Inngår i: The ISME Journal: multidisciplinary journal of microbial ecology, ISSN 1751-7362, Vol. 6, nr 2, s. 330-342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bacteria have important roles in freshwater food webs and in the cycling of elements in the ecosystem. Yet specific ecological features of individual phylogenetic groups and interactions among these are largely unknown. We used 454 pyrosequencing of 16S rRNA genes to study associations of different bacterioplankton groups to environmental characteristics and their co-occurrence patterns over an annual cycle in a dimictic lake. Clear seasonal succession of the bacterioplankton community was observed. After binning of sequences into previously described and highly resolved phylogenetic groups (tribes), their temporal dynamics revealed extensive synchrony and associations with seasonal events such as ice coverage, ice-off, mixing and phytoplankton blooms. Coupling between closely and distantly related tribes was resolved by time-dependent rank correlations, suggesting ecological coherence that was often dependent on taxonomic relatedness. Association networks with the abundant freshwater Actinobacteria and Proteobacteria in focus revealed complex interdependencies within bacterioplankton communities and contrasting linkages to environmental conditions. Accordingly, unique ecological features can be inferred for each tribe and reveal the natural history of abundant cultured and uncultured freshwater bacteria.

  • 145.
    Eiler, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Mondav, Rhiannon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Sinclair, Lucas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Fernandez-Vidal, Leyden
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Scofield, Douglas G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Schwientek, Patrick
    Martinez-Garcia, Manuel
    Torrents, David
    McMahon, Katherine D.
    Andersson, Siv G. E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär evolution. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Stepanauskas, Ramunas
    Woyke, Tanja
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Tuning fresh: radiation through rewiring of central metabolism in streamlined bacteria2016Inngår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 10, nr 8, s. 1902-1914Artikkel i tidsskrift (Fagfellevurdert)
  • 146.
    Eiler, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Zaremba-Niedzwiedzka, Katarzyna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär evolution.
    Martinez Garcia, Manuel
    McMahon, Katherine
    Stepanauskas, Ramunas
    Andersson, Siv G.E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär evolution.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Productivity and salinity structuring of the microplankton revealed by comparative freshwater metagenomics2014Inngår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 16, nr 9, s. 2682-2698Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Little is known about the diversity and structuring of freshwater microbial communities beyond the patterns revealed by tracing their distribution in the landscape with common taxonomic markers such as the ribosomal RNA. To address this gap in knowledge, metagenomes from temperate lakes were compared to selected marine metagenomes. Taxonomic analyses of rRNA genes in these freshwater metagenomes confirm the previously reported dominance of a limited subset of uncultured lineages of freshwater bacteria, whereas Archaea were rare. Diversification into marine and freshwater microbial lineages was also reflected in phylogenies of functional genes and there were also significant differences in functional beta-diversity. The pathways and functions that accounted for these differences are involved in osmoregulation, active transport, carbohydrate and amino acid metabolism. Moreover, predicted genes orthologous to active transporters and recalcitrant organic matter degradation were more common in microbial genomes from oligotrophic versus eutrophic lakes. This comparative metagenomic analysis allowed us to formulate a general hypothesis that oceanic- compared to freshwater-dwelling microorganisms, invest more in metabolism of amino acids and that strategies of carbohydrate metabolism differ significantly between marine and freshwater microbial communities.

  • 147.
    Einarsdóttir, Karólina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Wallin, Marcus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    High terrestrial carbon load via groundwater to a boreal lake dominated by surface water inflow2017Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, nr 1, s. 15-29Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The input of dissolved organic and inorganic carbon (DOC and DIC) via direct groundwater seepage to boreal lakes is often assumed to be small in noncarbonaceous areas. However, measurements are rare. We estimated the terrestrial load of DOC, DIC, and methane (CH4) to a small boreal lake for the open water period, on the basis of measured concentrations of carbon species in near-shore groundwater wells and inlet streams, and measured area-specific discharge. The subcatchment directly draining into the lake via groundwater seepage contributed 18% to the total water input during the open water season. Compared to stream and lake water, near-shore groundwater concentrations of DOC were slightly elevated, and groundwater DIC and CH4concentrations were highly elevated. Consequently, direct groundwater seepage contributed 27% to the total DOC load, 64% to the total DIC load, and 96% to the total CH4 load from the catchment to the lake. Groundwater DIC import corresponded only to 5–8% of lake carbon dioxide (CO2) emission. In incubation experiments, we observed higher photochemical DOC loss rates in stream and groundwater samples (18–55% DOC loss upon 72 h UV-A exposure) than in lake water (15% DOC loss) and detected significant DOC flocculation in groundwater samples in both light and dark incubations (2–24% DOC loss). We conclude that even in regions where lake hydrology is dominated by surface water inflow via inlet streams, direct groundwater seepage can represent an important carbon source to boreal lakes, and groundwater DOC may be susceptible to in-lake removal via degradation and flocculation.

  • 148.
    Ekebom, Nicklas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Mälardalens Högskola UKK.
    Loss of parental care in a sympatric three-spine stickleback system of southern Sweden2018Dataset
  • 149.
    Eklöf, Karin
    et al.
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, SE-75007 Uppsala, Sweden.
    Bishop, Kevin
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, SE-75007 Uppsala, Swede.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Björn, Erik
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden.
    Buck, Moritz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Umea Univ, Dept Chem, SE-90187 Umea, Sweden.; National Bioinformatics Infrastructure Sweden, Uppsala SE-75236, Sweden.
    Skyllberg, Ulf
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
    Osman, Omneya
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Kronberg, Rose Marie
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
    Bravo, Andrea Garcia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Formation of mercury methylation hotspots as a consequence of forestry operations2018Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 613-614, s. 1069-1078Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Earlier studies have shown that boreal forest logging can increase the concentration and export of methylmercury (MeHg) in stream runoff. Here we test whether forestry operations create soil environments of high MeHg net formation associated with distinct microbial communities. Furthermore, we test the hypothesis that Hg methylation hotspots are more prone to form after stump harvest than stem-only harvest, because of more severe soil compaction and soil disturbance. Concentrations of MeHg, percent MeHg of total Hg (THg), and bacterial community composition were determined at 200 soil sampling positions distributed across eight catchments. Each catchment was either stem-only harvested (n = 3), stem- and stump-harvested (n = 2) or left undisturbed (n = 3). In support of our hypothesis, higher MeHg to THg ratios was observed in one of the stump-harvested catchments. While the effects of natural variation could not be ruled out, we noted that most of the highest % MeHg was observed in water-filled cavities created by stump removal or driving damage. This catchment also featured the highest bacterial diversity and highest relative abundance of bacterial families known to include Hg methylators. We propose that water-logged and disturbed soil environments associated with stump harvest can favor methylating microorganisms, which also enhance MeHg formation.

  • 150.
    Eklöf, Karin
    et al.
    SLU Department of Aquatic Sciences and Assessment.
    Kraus, Andrea
    SLU Department of Aquatic Sciences and Assessment.
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Meili, Markus
    Stockholm University.
    Bishop, Kevin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Forestry Influence by Stump Harvest and Site Preparation on Methylmercury, Total Mercury and Other Stream Water Chemistry Parameters Across a Boreal Landscape2012Inngår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 15, nr 8, s. 1308-1320Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Forestry has been reported to cause elevated mercury (Hg) concentrations in runoff water. However, the degree to which forestry operations influence Hg in runoff varies among sites. A synoptic study, covering 54 catchments distributed all over Sweden, subjected to either stump harvest (SH), site preparation (SP) or no treatment (Ref), was undertaken to reveal the degree of forestry impact and causes of eventual variation. All streams were sampled twice, in autumn 2009 and summer 2010. There were no significant differences in total mercury (THg) and methylmercury (MeHg) concentrations between the three treatments in either 2009 or 2010. However, when pooling the treated catchments (that is, SH and SP) and taking catchment properties such as latitude into account, the treatment had a significant influence on the THg and MeHg concentrations. Although the treatment effect on THg and MeHg did not differ between SH and SP, the study did reveal significant forestry effects on potassium (K) and total nitrogen (TN) that were greater in the SH catchments and lower in the SP catchments. Partial least square (PLS) regressions indicated that organic matter was the most important variable influencing both the THg and MeHg concentrations. There were no significant differences between the treatment groups when comparing the ratios of THg/total organic carbon (TOC) and MeHg/TOC, suggesting that the high concentrations of THg and MeHg observed at some of the treated catchments are associated with increased concentrations of TOC rather than new methylation or increased mobilization caused by factors other than TOC.

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