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Jingying, X., Buck, M., Eklöf, K., Ahmed Osman, O., Schaefer, J. K., Bishop, K., . . . Bravo, A. G. (2019). Mercury methylating microbial communities of boreal forest soils. Scientific Reports, 9, Article ID 518.
Open this publication in new window or tab >>Mercury methylating microbial communities of boreal forest soils
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 518Article in journal (Refereed) Published
Abstract [en]

The formation of the potent neurotoxic methylmercury (MeHg) is a microbially mediated process that has raised much concern because MeHg poses threats to wildlife and human health. Since boreal forest soils can be a source of MeHg in aquatic networks, it is crucial to understand the biogeochemical processes involved in the formation of this pollutant. High-throughput sequencing of 16S rRNA and the mercury methyltransferase, hgcA, combined with geochemical characterisation of soils, were used to determine the microbial populations contributing to MeHg formation in forest soils across Sweden. The hgcA sequences obtained were distributed among diverse clades, including Proteobacteria, Firmicutes, and Methanomicrobia, with Deltaproteobacteria, particularly Geobacteraceae, dominating the libraries across all soils examined. Our results also suggest that MeHg formation is linked to the composition of also non-mercury methylating bacterial communities, likely providing growth substrate (e.g. acetate) for the hgcA-carrying microorganisms responsible for the actual methylation process. While previous research focused on mercury methylating microbial communities of wetlands, this study provides some first insights into the diversity of mercury methylating microorganisms in boreal forest soils.

National Category
Forest Science
Research subject
Biology with specialization in Limnology
Identifiers
urn:nbn:se:uu:diva-346175 (URN)10.1038/s41598-018-37383-z (DOI)000456553400083 ()
Funder
Swedish Research Council, 2011-7192Swedish Research Council, 2012-3892Swedish Research Council, 2013-6978Swedish Energy Agency, 36155-1
Available from: 2018-03-15 Created: 2018-03-15 Last updated: 2019-02-18Bibliographically approved
Wu, P., Bishop, K., von Brömssen, C., Eklöf, K., Futter, M., Hultberg, H., . . . Åkerblom, S. (2018). Does forest harvest increase the mercury concentrations in fish?: Evidence from Swedish lakes. Science of the Total Environment, 622-623, 1353-1362
Open this publication in new window or tab >>Does forest harvest increase the mercury concentrations in fish?: Evidence from Swedish lakes
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2018 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 622-623, p. 1353-1362Article in journal (Refereed) Published
Abstract [en]

A number of studies have evaluated the effects of forest harvest on mercury (Hg) concentrations and exports in surface waters, but few studies have tested the effect from forest harvest on the change in fish Hg concentrations over the course of several years after harvest. To address this question, mercury (Hg) concentrations in perch (Perca fluviatilis) muscle tissue from five lakes were analyzed for two years before (2010-2011) and three years after (2013-2015) forest harvest conducted in 2012. Fish Hg concentrations in the clear-cut catchments (n = 1373 fish specimens) were related to temporal changes of fish Hg in reference lakes (n = 1099 fish specimen) from 19 lakes in the Swedish National Environmental Monitoring Programme. Small (length < 100 mm) and large perch (length >= 100 mm) were analyzed separately, due to changing feeding habitats of fish over growing size. There was considerable year-to-year and lake-to-lake variation in fish Hg concentrations (-14%-121%) after forest harvest in the clearcut lakes, according to our first statistical model that count for fish Hg changes. While the effect ascribed to forest harvest varied between years, after three years (in 2015), a significant increase of 26% (p < 0.0001) in Hg concentrations of large fish was identified in our second statistical model that pooled all 5 clearcut lakes. The large fish Hg concentrations in the 19 reference lakes also varied, and in 2015 had decreased by 7% (p = 0.03) relative to the concentrations in 2010-2011. The majority of the annual changes in fish Hg concentrations in the clearcut lakes after harvest were in the lower range of earlier predictions for high-latitude lakes extrapolated primarily from the effects of forest harvest operations on Hg concentrations in water. Since the risk of forest harvest impacts on Hg extends to fish and not just surface water concentrations, there is even more reason to consider Hg effects in forestry planning, alongside other ecosystem effects.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Fish hg, Forest harvest, Perch, Forestry practices, Clearcutting
National Category
Fish and Aquacultural Science
Identifiers
urn:nbn:se:uu:diva-350271 (URN)10.1016/j.scitotenv.2017.12.075 (DOI)000426349000132 ()
Funder
Swedish Research Council, 39-2013-6978Mistra - The Swedish Foundation for Strategic Environmental Research
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-05-15Bibliographically approved
Olsson, B. A., Åkerblom, S., Bishop, K., Eklöf, K. & Ring, E. (2017). Does the harvest of logging residues and wood ash application affect the mobilization and bioavailability of trace metals?. Forest Ecology and Management, 383, 61-72
Open this publication in new window or tab >>Does the harvest of logging residues and wood ash application affect the mobilization and bioavailability of trace metals?
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2017 (English)In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 383, p. 61-72Article in journal (Refereed) Published
Abstract [en]

Residue biomass from conventional forestry, such as slash (i.e., tree tops and branches) and stumps, are used at an increasing rate for energy purposes in Sweden. This review examined current knowledge on how extraction of forest biomass for large-scale energy production, including the practice of ash application for nutrient recycling, influences the mobility and stocks of trace metals in the forest environment at different time scales. The study focussed on Swedish energy production systems and contemporary forest management practices, as well as the heavy metals lead (Pb), cadmium (Cd) and mercury (Hg). The historic accumulation of these elements in forest soils has mainly originated from diffuse, long-term atmospheric deposition. There is little conclusive evidence that slash harvest generally increases the risk for mobilization of trace metals from soils during the regeneration phase, compared with stem-only harvesting. However, microbial transformation of mercury into the highly toxic methyl mercury (MeHg) species is facilitated in suboxic soil conditions that may increase during the regeneration,phase. Therefore it has been hypothesized that stump harvest could result in increased mercury methylation and transport to surface waters, owing to stump harvest effects on soil physical conditions and hydrological pathways. The few studies available on the stump harvest effects of Hg showed no consistent difference in runoff from clear felled and stump harvested catchments compared to clear-felled and soil-scarified catchments in terms of concentrations or fluxes of MeHg. Assuming that the highest trace metal concentrations in wood ash recommended by the Swedish Forest Authority are not exceeded, wood ash application does not currently increase metal loads at the national scale, because trace metal export in harvested biomass is much larger than that returned in wood ash. The net load of Pb, Cd, and Cu will not increase at the local scale if ash doses do not greatly exceed the compensation for nutrients exported in harvested biomass. Biomass harvest and ash application have negligible effects on the load of mercury to forest soils. A large number of studies have examined the effects of wood ash on trace metal content in soil, water and biota. Most studies showed no effect of wood ash application. When increased concentrations were found (Cd, Cr, Cu, Zn), this was in soils where concentrations remained well below harmful levels. Relatively fewer reports of increased concentrations are reported for soil water and plants, and no effects were reported for edible berries or fungi.

Keywords
Bioenergy, Cadmium, Mercury, Lead, Stump harvesting
National Category
Forest Science
Identifiers
urn:nbn:se:uu:diva-312027 (URN)10.1016/j.foreco.2016.09.017 (DOI)000389163500007 ()
Funder
Swedish Energy Agency
Available from: 2017-01-05 Created: 2017-01-04 Last updated: 2017-11-29Bibliographically approved
Teutschbein, C., Sponseller, R. A., Grabs, T., Blackburn, M., Boyer, E. W., Hytteborn, J. K. & Bishop, K. (2017). Future Riverine Inorganic Nitrogen Load to the Baltic Sea From Sweden: An Ensemble Approach to Assessing Climate Change Effects. Global Biogeochemical Cycles, 31(11), 1674-1701
Open this publication in new window or tab >>Future Riverine Inorganic Nitrogen Load to the Baltic Sea From Sweden: An Ensemble Approach to Assessing Climate Change Effects
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2017 (English)In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 31, no 11, p. 1674-1701Article in journal (Refereed) Published
Abstract [en]

The dramatic increase of bioreactive nitrogen entering the Earth’s ecosystems continues toattract growing attention. Increasingly large quantities of inorganic nitrogen are flushed from land towater, accelerating freshwater, and marine eutrophication. Multiple, interacting, and potentiallycountervailing drivers control the future hydrologic export of inorganic nitrogen. In this paper, we attempt toresolve these land-water interactions across boreal/hemiboreal Sweden in the face of a changing climatewith help of a versatile modeling framework to maximize the information value of existing measurementtime series. We combined 6,962 spatially distributed water chemistry observations spread over 31 years withdaily streamflow and air temperature records. An ensemble of climate model projections, hydrologicalsimulations, and several parameter parsimonious regression models was employed to project future riverineinorganic nitrogen dynamics across Sweden. The median predicted increase in total inorganic nitrogenexport from Sweden (2061–2090) due to climate change was 14% (interquartile range 0–29%), based on theensemble of 7,500 different predictions for each study site. The overall export as well as the seasonal patternof inorganic nitrogen loads in a future climate are mostly influenced by longer growing seasons and morewinter flow, which offset the expected decline in spring flood. The predicted increase in inorganic nitrogenloading due to climate change means that the political efforts for reducing anthropogenic nitrogen inputsneed to be increased if ambitions for reducing the eutrophication of the Baltic Sea are to be achieved.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2017
Keywords
streamflow, climate change, nitrogen, Baltic Sea, Sweden, eutrophication
National Category
Oceanography, Hydrology and Water Resources Geosciences, Multidisciplinary Climate Research
Research subject
Hydrology
Identifiers
urn:nbn:se:uu:diva-335388 (URN)10.1002/2016GB005598 (DOI)000418082000004 ()08866236 (ISBN)
Available from: 2017-12-05 Created: 2017-12-05 Last updated: 2018-01-29Bibliographically approved
Osterwalder, S., Bishop, K., Alewell, C., Fritsche, J., Laudon, H., Akerblom, S. & Nilsson, M. B. (2017). Mercury evasion from a boreal peatland shortens the timeline for recovery from legacy pollution. Scientific Reports, 7, Article ID 16022.
Open this publication in new window or tab >>Mercury evasion from a boreal peatland shortens the timeline for recovery from legacy pollution
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 16022Article in journal (Refereed) Published
Abstract [en]

Peatlands are a major source of methylmercury that contaminates downstream aquatic food webs. The large store of mercury (Hg) in peatlands could be a source of Hg for over a century even if deposition is dramatically reduced. However, the reliability of Hg mass balances can be questioned due to missing long-term land-atmosphere flux measurements. We used a novel micrometeorological system for continuous measurement of Hg peatland-atmosphere exchange to derive the first annual Hg budget for a peatland. The evasion of Hg (9.4 mu g m(-2) yr(-1)) over the course of a year was seven times greater than stream Hg export, and over two times greater than wet bulk deposition to the boreal peatland. Measurements of dissolved gaseous Hg in the peat pore water also indicate Hg evasion. The net efflux may result from recent declines in atmospheric Hg concentrations that have turned the peatland from a net sink into a source of atmospheric Hg. This net Hg loss suggests that open boreal peatlands and downstream ecosystems can recover more rapidly from past atmospheric Hg deposition than previously assumed. This has important implications for future levels of methylmercury in boreal freshwater fish and the estimation of historical Hg accumulation rates from peat profiles.

National Category
Climate Research
Identifiers
urn:nbn:se:uu:diva-361243 (URN)10.1038/s41598-017-16141-7 (DOI)000416118300046 ()29167528 (PubMedID)
Funder
Swedish Research Council, 2009-15586-68819-37
Available from: 2018-09-26 Created: 2018-09-26 Last updated: 2018-09-26Bibliographically approved
Habiba, G., Abebe, G., Bravo, A. G., Ermias, D., Staffan, Ǻ. & Bishop, K. (2017). Mercury Human Exposure in Populations Living Around Lake Tana (Ethiopia). Biological Trace Element Research, 175(2), 237-243
Open this publication in new window or tab >>Mercury Human Exposure in Populations Living Around Lake Tana (Ethiopia)
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2017 (English)In: Biological Trace Element Research, ISSN 0163-4984, E-ISSN 1559-0720, Vol. 175, no 2, p. 237-243Article in journal (Refereed) Published
Abstract [en]

A survey carried out in Lake Tana in 2015 found that Hg levels in some fish species exceeded internationally accepted safe levels for fish consumption. The current study assesses human exposure to Hg through fish consumption around the Lake Tana. Of particular interest was that a dietary intake of fishes is currently a health risk for Bihar Dar residents and anglers. Hair samples were collected from three different groups: anglers, college students and teachers, and daily laborers. A questionary includes gender, age, weight, activity. Frequency of fish consumption and origin of the eaten fish were completed by each participant. Mercury concentrations in hair were significantly higher (P value <0.05) for anglers (mean ± standard deviation 0.120 ± 0.199 μg/g) than college students (mean ± standard deviation 0.018 ± 0.039 μg/g) or daily workers (mean ± standard deviation 16 ± 9.5 ng/g). Anglers consumed fish more often than daily workers and college group. Moreover, there was also a strong correlation (P value <0.05) between the logarithms of total mercury and age associated with mercury concentration in scalp hair. Mercury concentrations in the hair of men were on average twice the value of the women. Also, users of skin lightening soap on a daily basis had 2.5 times greater mercury in scalp hair than non-users. Despite the different sources of mercury exposure mentioned above, the mercury concentrations of the scalp hair of participants of this study were below levels deemed to pose a threat to health.

Keywords
Bihar Dar, Fish, Hair, Mercury, Occupation, Residents
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-304389 (URN)10.1007/s12011-016-0745-9 (DOI)000392336200001 ()27278962 (PubMedID)
Available from: 2016-10-05 Created: 2016-10-05 Last updated: 2017-11-30Bibliographically approved
Campeau, A., Wallin, M., Giesler, R., Löfgren, S., Mörth, C.-M., Schiff, S., . . . Bishop, K. (2017). Multiple sources and sinks of dissolved inorganic carbon across Swedish streams, refocusing the lens of stable C isotopes. Scientific Reports, 7, Article ID 9158.
Open this publication in new window or tab >>Multiple sources and sinks of dissolved inorganic carbon across Swedish streams, refocusing the lens of stable C isotopes
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 9158Article in journal (Refereed) Published
Abstract [en]

It is well established that stream dissolved inorganic carbon (DIC) fluxes play a central role in the global C cycle, yet the sources of stream DIC remain to a large extent unresolved. Here, we explore large-scale patterns in delta C-13-DIC from streams across Sweden to separate and further quantify the sources and sinks of stream DIC. We found that stream DIC is governed by a variety of sources and sinks including biogenic and geogenic sources, CO2 evasion, as well as in-stream processes. Although soil respiration was the main source of DIC across all streams, a geogenic DIC influence was identified in the northernmost region. All streams were affected by various degrees of atmospheric CO2 evasion, but residual variance in delta C-13-DIC also indicated a significant influence of in-stream metabolism and anaerobic processes. Due to those multiple sources and sinks, we emphasize that simply quantifying aquatic DIC fluxes will not be sufficient to characterise their role in the global C cycle.

National Category
Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-328530 (URN)10.1038/s41598-017-09049-9 (DOI)000408285200002 ()28831088 (PubMedID)
Funder
Swedish Research Council, 2012-3919Swedish Research Council, 2007-3841Swedish Research Council, 2013-5001Swedish Research Council Formas, 214-2008-202Knut and Alice Wallenberg Foundation
Available from: 2017-08-25 Created: 2017-08-25 Last updated: 2018-09-21Bibliographically approved
Audet, J., Wallin, M. B., Kyllmar, K., Andersson, S. & Bishop, K. (2017). Nitrous oxide emissions from streams in a Swedish agricultural catchment. Agriculture, Ecosystems & Environment, 236, 295-303
Open this publication in new window or tab >>Nitrous oxide emissions from streams in a Swedish agricultural catchment
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2017 (English)In: Agriculture, Ecosystems & Environment, ISSN 0167-8809, E-ISSN 1873-2305, Vol. 236, p. 295-303Article in journal (Refereed) Published
Abstract [en]

Excess nitrogen fertiliser in agricultural soils might be leached to streams and converted to the greenhouse gas nitrous oxide (N2O). To assess the importance of N2O emissions from agricultural streams, concentration dynamics and emissions N2O emissions in streams were investigated in a 32 km2 lowland agricultural catchment located in Sweden. Dissolved N2O concentration was measured at nine occasions between December 2014 and August 2015 at nine stream stations. The stream stations represented sub-catchments with different land use characteristics with agricultural land use ranging from 0 to 63% of the area. Stream N2O percentage saturation ranged 40-2701% and showed large spatial and temporal variations. Statistical analysis using mixed models revealed that N2O concentration was significantly linked to nitrate concentration in the stream water, to the percentage arable land in the sub catchments as well as to the stream water discharge. Using two empirical equations to estimate the N2O emissions showed that streams were generally a source of N2O to the atmosphere (mean 108 and 175 mu g N m(-2) h(-1) with first and second equation). The catchment scale estimate of N2O stream emissions was compared to the estimate obtained using IPCC guidelines linking N fertilisation inputs and leaching to N2O emissions. The comparison suggested that N2O stream emission calculated using the IPCC methodology might be underestimated. A coarse estimate suggests that N2O stream emissions represent about 4% of the total N2O emissions from N-fertiliser at the catchment scale. Hence while streams covered only 0.1% of the catchment area they were of disproportionate importance as a source of N2O to the atmosphere.

Keywords
Greenhouse gas, River, Nitrogen pollution
National Category
Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-311867 (URN)10.1016/j.agee.2016.12.012 (DOI)000392886700029 ()
Funder
Swedish Research Council, 2015-1559
Available from: 2017-01-03 Created: 2017-01-03 Last updated: 2017-11-29Bibliographically approved
Mayotte, J.-M., Grabs, T., Sutliff-Johansson, S. & Bishop, K. (2017). The effects of ionic strength and organic matter on virus inactivation at low temperatures: general likelihood uncertainty estimation (GLUE) as an alternative to least-squares parameter optimization for the fitting of virus inactivation models. Hydrogeology Journal, 25(4), 1063-1076
Open this publication in new window or tab >>The effects of ionic strength and organic matter on virus inactivation at low temperatures: general likelihood uncertainty estimation (GLUE) as an alternative to least-squares parameter optimization for the fitting of virus inactivation models
2017 (English)In: Hydrogeology Journal, ISSN 1431-2174, E-ISSN 1435-0157, Vol. 25, no 4, p. 1063-1076Article in journal (Refereed) Published
Abstract [en]

This study examined how the inactivation of bacteriophage MS2 in water was affected by ionic strength (IS) and dissolved organic carbon (DOC) using static batch inactivation experiments at 4 A degrees C conducted over a period of 2 months. Experimental conditions were characteristic of an operational managed aquifer recharge (MAR) scheme in Uppsala, Sweden. Experimental data were fit with constant and time-dependent inactivation models using two methods: (1) traditional linear and nonlinear least-squares techniques; and (2) a Monte-Carlo based parameter estimation technique called generalized likelihood uncertainty estimation (GLUE). The least-squares and GLUE methodologies gave very similar estimates of the model parameters and their uncertainty. This demonstrates that GLUE can be used as a viable alternative to traditional least-squares parameter estimation techniques for fitting of virus inactivation models. Results showed a slight increase in constant inactivation rates following an increase in the DOC concentrations, suggesting that the presence of organic carbon enhanced the inactivation of MS2. The experiment with a high IS and a low DOC was the only experiment which showed that MS2 inactivation may have been time-dependent. However, results from the GLUE methodology indicated that models of constant inactivation were able to describe all of the experiments. This suggested that inactivation time-series longer than 2 months were needed in order to provide concrete conclusions regarding the time-dependency of MS2 inactivation at 4 A degrees C under these experimental conditions.

Keywords
Virus inactivation, Uncertainty, Groundwater management, Bacteriophage MS2, Health
National Category
Oceanography, Hydrology and Water Resources Water Engineering
Identifiers
urn:nbn:se:uu:diva-323761 (URN)10.1007/s10040-017-1559-3 (DOI)000401787800014 ()
Available from: 2017-06-12 Created: 2017-06-12 Last updated: 2018-01-13Bibliographically approved
Xu, X., Meng, B., Zhang, C., Feng, X., Gu, C., Guo, J., . . . Qiu, G. (2017). The local impact of a coal-fired power plant on inorganic mercury and methyl-mercury distribution in rice (Oryza sativa L.). Environmental Pollution, 223, 11-18
Open this publication in new window or tab >>The local impact of a coal-fired power plant on inorganic mercury and methyl-mercury distribution in rice (Oryza sativa L.)
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2017 (English)In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 223, p. 11-18Article in journal (Refereed) Published
Abstract [en]

Emission from coal-fired power plants is one of the major anthropogenic sources of mercury (Hg) in the environment, because emitted Hg can be quickly deposited nearby the source, attention is paid to the effects of coal-burning facilities on levels of toxic methyl-mercury (MeHg) in biota near such sources. Since rice is an agricultural crop that can bio-accumulate MeHg, the potential effects of a large Hg emitting coal-fired power plant in Hunan Province, China on both inorganic Hg (Hg(II)) and MeHg distributions in rice was investigated. Relatively high MeHg (up to 3.8 mu g kg(-1)) and Hg(II) (up to 22 mu g kg(-1)) concentrations were observed in rice samples collected adjacent to the plant, suggesting a potential impact of Hg emission from the coal fired power plant on the accumulation of Hg in rice in the area. Concentrations of MeHg in rice were positively correlated with soil MeHg, soil S, and gaseous elemental Hg (GEM) in ambient air. Soil MeHg was the most important factor controlling MeHg concentrations in rice. The methylation of Hg in soils may be controlled by factors such as the chemical speciation of inorganic Hg, soil S, and ambient GEM.

Keywords
Inorganic mercury, Methyl-mercury, Rice, Soil S, Coal-fired power plant
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-321339 (URN)10.1016/j.envpol.2016.11.042 (DOI)000397359500002 ()28139322 (PubMedID)
Available from: 2017-05-31 Created: 2017-05-31 Last updated: 2017-05-31Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8057-1051

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