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Weyhenmeyer, Gesa A.
Alternative names
Publications (10 of 144) Show all publications
Engel, F., Farrell, K. J., McCullough, I. M., Scordo, F., Denfeld, B. A., Dugan, H. A., . . . Weyhenmeyer, G. A. (2018). A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters. The Science of Nature: Naturwissenschaften, 105(3), Article ID 25.
Open this publication in new window or tab >>A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters
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2018 (English)In: The Science of Nature: Naturwissenschaften, ISSN 0028-1042, E-ISSN 1432-1904, Vol. 105, no 3, article id 25Article in journal (Refereed) Published
Abstract [en]

The magnitude of lateral dissolved inorganic carbon (DIC) export from terrestrial ecosystems to inland waters strongly influences the estimate of the global terrestrial carbon dioxide (CO2) sink. At present, no reliable number of this export is available, and the few studies estimating the lateral DIC export assume that all lakes on Earth function similarly. However, lakes can function along a continuum from passive carbon transporters (passive open channels) to highly active carbon transformers with efficient in-lake CO2 production and loss. We developed and applied a conceptual model to demonstrate how the assumed function of lakes in carbon cycling can affect calculations of the global lateral DIC export from terrestrial ecosystems to inland waters. Using global data on in-lake CO2 production by mineralization as well as CO2 loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of 0.70(-0.31)(+0.27) 1.52(-0.90)(+1.09) Pg C yr(-1) depending on the assumed function of lakes. Thus, the considered lake function has a large effect on the calculated lateral DIC export from terrestrial ecosystems to inland waters. We conclude that more robust estimates of CO2 sinks and sources will require the classification of lakes into their predominant function. This functional lake classification concept becomes particularly important for the estimation of future CO2 sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.

Keywords
Global carbon cycle, Lake functioning, Hydrologic CO2 transport, Lake carbon cycling, Earth system models, Lake primary production
National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-347136 (URN)10.1007/s00114-018-1547-z (DOI)000431443400005 ()29582138 (PubMedID)
Funder
Swedish Research Council, 2016-04153EU, Horizon 2020, 643052Knut and Alice Wallenberg Foundation
Available from: 2018-03-26 Created: 2018-03-26 Last updated: 2018-07-04Bibliographically approved
Wallin, M., Campeau, A., Audet, J., Bastviken, D., Bishop, K., Kokic, J., . . . Grabs, T. J. (2018). Carbon dioxide and methane emissions of Swedish low-order streams: a national estimate and lessons learnt from more than a decade of observations. Limnology and Oceanography: Letters, 3(3), 156-167
Open this publication in new window or tab >>Carbon dioxide and methane emissions of Swedish low-order streams: a national estimate and lessons learnt from more than a decade of observations
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2018 (English)In: Limnology and Oceanography: Letters, ISSN 2378-2242, Vol. 3, no 3, p. 156-167Article in journal (Refereed) Published
Abstract [en]

Low-order streams are suggested to dominate the atmospheric CO2 source of all inland waters. Yet, many large-scale stream estimates suffer from methods not designed for gas emission determination and rarely include other greenhouse gases such as CH4. Here, we present a compilation of directly measured CO2 and CH4 concentration data from Swedish low-order streams (>1600 observations across>500 streams) covering large climatological and land-use gradients. These data were combined with an empirically derived gas trans- fer model and the characteristics of a ca. 400,000 km stream network covering the entire country. The total stream CO2 and CH4 emission corresponded to 2.7 Tg C yr21 (95% confidence interval: 2.0–3.7) of which the CH4 accounted for 0.7% (0.02 Tg C yr21). The study highlights the importance of low-order streams, as well as the critical need to better represent variability in emissions and stream areal extent to constrain future stream C emission estimates.

National Category
Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-357196 (URN)10.1002/lol2.10061 (DOI)
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-11-08Bibliographically approved
Hastie, A., Lauerwald, R., Weyhenmeyer, G. A., Sobek, S., Verpoorter, C. & Regnier, P. (2018). CO2 evasion from boreal lakes: Revised estimate, drivers of spatial variability, and future projections. Global Change Biology, 24(2), 711-728
Open this publication in new window or tab >>CO2 evasion from boreal lakes: Revised estimate, drivers of spatial variability, and future projections
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2018 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, no 2, p. 711-728Article in journal (Refereed) Published
Abstract [en]

Lakes (including reservoirs) are an important component of the global carbon (C) cycle, as acknowledged by the 5th assessment report of the IPCC. In the context of lakes, the boreal region is disproportionately important contributing to 27% of the worldwide lake area, despite representing just 14% of global land surface area. In this study, we used a statistical approach to derive a prediction equation for the partial pressure of CO2 (pCO2) in lakes as a function of lake area, terrestrial net primary productivity (NPP) and precipitation (r2 = 0.56), and to create the first high resolution, circumboreal map (0.5) of lake pCO2. The map of pCO2 was combined with lake area from the recently published GLOWABO database and three different estimates of the gas transfer velocity k to produce a resulting map of CO2 evasion (FCO2). For the boreal region we estimate an average, lake area weighted,pCO2 of 966 (678- 1325) μatm and a total FCO2 of 189 (74-347) Tg C yr−1, and evaluate the corresponding uncertainties based on Monte Carlo simulation. Our estimate of FCO2 is approximately twofold greater than previous estimates, as a result of methodological and data source differences. We use our results along with published estimates of the other C fluxes through inland waters to derive a C budget for the boreal region, and find that FCO2 from lakes is the most significant flux of the land-ocean aquatic continuum, and of a similar magnitude as emissions from forest fires. Using the model and applying it to spatially resolved projections of terrestrial NPP and precipitation while keeping everything else constant, we predict a 107% increase in boreal lake FCO2 under emission scenario RCP8.5 by 2100. Our projections are largely driven by increases in terrestrial NPP over the same period, showing the very close connection between the terrestrial and aquatic C cycle.

Keywords
Boreal, CO2, Carbon budget, Climate change, Future projections, Lake, Precipitation, Terrestrial NPP
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-335068 (URN)10.1111/gcb.13902 (DOI)000423994700043 ()28892578 (PubMedID)
Funder
EU, Horizon 2020, 643052, 703813Swedish Research Council, 2016-04153Knut and Alice Wallenberg FoundationEU, FP7, Seventh Framework Programme, 336642
Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2018-05-17Bibliographically approved
Nydahl, A., Wallin, M., Tranvik, L., Hiller, C., Attermeyer, K., Garrison, J., . . . Weyhenmeyer, G. A. (2018). Colored organic matter increases CO2 in meso-eutrophic lake water through altered light climate and acidity. Limnology and Oceanography
Open this publication in new window or tab >>Colored organic matter increases CO2 in meso-eutrophic lake water through altered light climate and acidity
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2018 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590Article in journal (Refereed) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-366220 (URN)10.1002/lno.11072 (DOI)
Available from: 2018-11-18 Created: 2018-11-18 Last updated: 2018-11-18
Weyhenmeyer, G. A., Mackay, M., Stockwell, J. D., Thiery, W., Grossart, H.-P., Augusto-Silva, P. B., . . . Woolway, R. I. (2017). Citizen science shows systematic changes in the temperature difference between air and inland waters with global warming. Scientific Reports, 7, Article ID 43890.
Open this publication in new window or tab >>Citizen science shows systematic changes in the temperature difference between air and inland waters with global warming
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 43890Article in journal (Refereed) Published
Abstract [en]

Citizen science projects have a long history in ecological studies. The research usefulness of such projects is dependent on applying simple and standardized methods. Here, we conducted a citizen science project that involved more than 3500 Swedish high school students to examine the temperature difference between surface water and the overlying air (T-w-T-a) as a proxy for sensible heat flux (Q(H)). If Q(H) is directed upward, corresponding to positive T-w-T-a, it can enhance CO2 and CH4 emissions from inland waters, thereby contributing to increased greenhouse gas concentrations in the atmosphere. The students found mostly negative T-w-T-a across small ponds, lakes, streams/rivers and the sea shore (i.e. downward Q(H)), with T-w-T-a becoming increasingly negative with increasing T-a. Further examination of T-w-T-a using high-frequency temperature data from inland waters across the globe confirmed that T-w-T-a is linearly related to T-a. Using the longest available high-frequency temperature time series from Lake Erken, Sweden, we found a rapid increase in the occasions of negative T-w-T-a with increasing annual mean T-a since 1989. From these results, we can expect that ongoing and projected global warming will result in increasingly negative T-w-T-a, thereby reducing CO2 and CH4 transfer velocities from inland waters into the atmosphere.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2017
National Category
Oceanography, Hydrology and Water Resources Climate Research
Identifiers
urn:nbn:se:uu:diva-320259 (URN)10.1038/srep43890 (DOI)000395736900001 ()28262715 (PubMedID)
Funder
EU, Horizon 2020, 643052Swedish Research Council, 2016-04153Knut and Alice Wallenberg FoundationGerman Research Foundation (DFG), GR1540:/21-1
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2018-01-13Bibliographically approved
Hampton, S. E., Galloway, A. W. E., Powers, S. M., Ozersky, T., Woo, K. H., Batt, R. D., . . . Xenopoulos, M. A. (2017). Ecology under lake ice. Ecology Letters, 20(1), 98-111
Open this publication in new window or tab >>Ecology under lake ice
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2017 (English)In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 20, no 1, p. 98-111Article, review/survey (Refereed) Published
Abstract [en]

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer ‘growing seasons’. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass.

Keywords
Aquatic ecosystem, data synthesis, freshwater, lake, limnology, long-term, plankton, seasonal, time series, winter ecology
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-310433 (URN)10.1111/ele.12699 (DOI)000390026200010 ()
Available from: 2016-12-16 Created: 2016-12-16 Last updated: 2017-11-29Bibliographically approved
Woolway, R. I., Carrea, L., Merchant, J., Dokulil, M. T., de Eyto, E., DeGasper, C. L., . . . Weyhenmeyer, G. A. (2017). Lake surface temperature [in €"State of the Climate in 2016"€]. Bulletin of The American Meteorological Society - (BAMS), 98(8), S13-S14
Open this publication in new window or tab >>Lake surface temperature [in €"State of the Climate in 2016"€]
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2017 (English)In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 98, no 8, p. S13-S14Article in journal (Other academic) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-335084 (URN)10.1175/2017BAMSStateoftheClimate (DOI)
Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2017-11-30Bibliographically approved
Weyhenmeyer, G. A. & Conley, D. J. (2017). Large differences between carbon and nutrient loss rates along the land to ocean aquatic continuum-implications for energy:nutrient ratios at downstream sites. Limnology and Oceanography, 62, S183-S193
Open this publication in new window or tab >>Large differences between carbon and nutrient loss rates along the land to ocean aquatic continuum-implications for energy:nutrient ratios at downstream sites
2017 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 62, p. S183-S193Article in journal (Refereed) Published
Abstract [en]

The balance between the availability of energy and nutrients is decisive for the growth and survival of organisms. Here, we evaluated how energy, in this study expressed as total carbon (TC), is lost along the land to ocean aquatic continuum (LOAC) in relation to nutrients, i.e., total phosphorus (TP), total nitrogen (TN), total iron (TFe), and dissolved silica (DSi). For the evaluation, we used data from 4774 lakes, 149 streams, and 52 river mouths from the boreal region. We found that the loss of all chemical variables followed a first order decay function along the LOAC with shortest half-lives for TFe and DSi (410 d and 568 d, respectively). The half-life of TC was more than twice as long as for TFe and DSi, resulting in rapidly increasing TC:TFe and TC:DSi ratios along the LOAC. In contrast, TC:TP and TC:TN ratios decreased along the LOAC. The TC and TFe concentration declines along the LOAC were quantitatively similar to the TC and TFe concentration declines from winter to summer, indicating that similar drivers are responsible for spatial and seasonal TC and TFe losses in inland waters. We conclude that the energy:nutrient ratio rapidly changes along the LOAC with an increasing surplus of energy in relation to TFe and DSi the longer water stays in the landscape. These findings have implications for the growth of aquatic organisms along the LOAC, where organisms are likely to become increasingly iron and silica limited with increasing water retention in the landscape.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-335067 (URN)10.1002/lno.10589 (DOI)000415924700013 ()
Funder
EU, Horizon 2020, 643052Swedish Research Council, 2014-5910Swedish Research Council, 2016-04153Knut and Alice Wallenberg Foundation
Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2018-03-07Bibliographically approved
Nydahl, A., Wallin, M. B. & Weyhenmeyer, G. A. (2017). No long-term trends in pCO2 despite increasing organic carbon concentrations in boreal lakes, streams and rivers. Global Biogeochemical Cycles, 31(6), 985-995
Open this publication in new window or tab >>No long-term trends in pCO2 despite increasing organic carbon concentrations in boreal lakes, streams and rivers
2017 (English)In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 31, no 6, p. 985-995Article in journal (Refereed) Published
Abstract [en]

Concentrations of dissolved organic carbon (DOC) from terrestrial sources have been increasing in freshwaters across large parts of the boreal region. According to results from large-scale field and detailed laboratory studies, such a DOC increase could potentially stimulate carbon dioxide (CO2) production, subsequently increasing the partial pressure of CO2 (pCO2) in freshwaters. However, the response of pCO2 to the presently observed long-term increase in DOC in freshwaters is still unknown. Here we tested whether the commonly found spatial DOC-pCO2 relationship is also valid on a temporal scale. Analyzing time series of water chemical data from 71 lakes, 30 streams, and 4 river mouths distributed across all of Sweden over a 17 year period, we observed significant DOC concentration increases in 39 lakes, 15 streams, and 4 river mouths. Significant pCO2 increases were, however, only observed in six of these 58 waters, indicating that long-term DOC increases in Swedish waters are disconnected from temporal pCO2 trends. We suggest that the uncoupling of trends in DOC concentration and pCO2 are a result of increased surface water runoff. When surface water runoff increases, there is likely less CO2 relative to DOC imported from soils into waters due to a changed balance between surface and groundwater flow. Additionally, increased surface water runoff causes faster water flushing through the landscape giving less time for in situ CO2 production in freshwaters. We conclude that pCO2 is presently not following DOC concentration trends, which has important implications for modeling future CO2 emissions from boreal waters.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2017
National Category
Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-323413 (URN)10.1002/2016GB005539 (DOI)000405103600004 ()
Funder
EU, Horizon 2020, 643052Knut and Alice Wallenberg Foundation, KAW 2013.0091Swedish Research Council, 2016-04153
Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2017-11-30Bibliographically approved
Björnerås, C., Weyhenmeyer, G. A., Evans, C. D., Gessner, M. O., Grossart, H. P., Kangur, K., . . . Kritzberg, E. S. (2017). Widespread Increases in Iron Concentration in European and North American Freshwaters. Global Biogeochemical Cycles, 31(10), 1488-1500
Open this publication in new window or tab >>Widespread Increases in Iron Concentration in European and North American Freshwaters
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2017 (English)In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 31, no 10, p. 1488-1500Article in journal (Refereed) Published
Abstract [en]

Recent reports of increasing iron (Fe) concentrations in freshwaters are of concern, given the fundamental role of Fe in biogeochemical processes. Still, little is known about the frequency and geographical distribution of Fe trends or about the underlying drivers. We analyzed temporal trends of Fe concentrations across 340 water bodies distributed over 10 countries in northern Europe and North America in order to gain a clearer understanding of where, to what extent, and why Fe concentrations are on the rise. We found that Fe concentrations have significantly increased in 28% of sites, and decreased in 4%, with most positive trends located in northern Europe. Regions with rising Fe concentrations tend to coincide with those with organic carbon (OC) increases. Fe and OC increases may not be directly mechanistically linked, but may nevertheless be responding to common regional-scale drivers such as declining sulfur deposition or hydrological changes. A role of hydrological factors was supported by covarying trends in Fe and dissolved silica, as these elements tend to stem from similar soil depths. A positive relationship between Fe increases and conifer cover suggests that changing land use and expanded forestry could have contributed to enhanced Fe export, although increases were also observed in nonforested areas. We conclude that the phenomenon of increasing Fe concentrations is widespread, especially in northern Europe, with potentially significant implications for wider ecosystem biogeochemistry, and for the current browning of freshwaters.

Keywords
browning, climate change, freshwaters, iron, trends
National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-335069 (URN)10.1002/2017GB005749 (DOI)000416625200002 ()
Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2018-03-19Bibliographically approved
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