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  • 1.
    Denfeld, Blaize A.
    et al.
    Uppsala University, Sweden; Umeå University, Sweden.
    Ricao Canelhas, Monica
    Uppsala University, Sweden.
    Weyhenmeyer, Gesa A.
    Uppsala University, Sweden.
    Bertilsson, Stefan
    Uppsala University, Sweden.
    Eiler, Alexander
    Uppsala University, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Constraints on methane oxidation in ice-covered boreal lakes2016Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, nr 7, s. 1924-1933Artikel i tidskrift (Refereegranskat)
    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.

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  • 2.
    Gudasz, Cristian
    et al.
    Uppsala University, Sweden.
    Sobek, Sebastian
    Uppsala University, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Koehler, Birgit
    Uppsala University, Sweden.
    Tranvik, Lars J.
    Uppsala University, Sweden.
    Temperature sensitivity of organic carbon mineralization in contrasting lake sediments2015Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 120, nr 7, s. 1215-1225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Temperature alone explains a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that (1) temperature sensitivity differs between the fast and slowly decomposition OC and (2) over time, decreasing soil respiration is coupled with increase in temperature sensitivity. In lakes, autochthonous and allochthonous OC sources are generally regarded as fast and slowly decomposing OC, respectively. Lake sediments with different contributions of allochthonous and autochthonous components, however, showed similar temperature sensitivity in short-term incubation experiments. Whether the mineralization of OC in lake sediments dominated by allochthonous or autochthonous OC has different temperature sensitivity in the longer term has not been addressed. We incubated sediments from two boreal lakes that had contrasting OC origin (allochthonous versus autochthonous), and OC characteristics (C/N ratios of 21 and 10) at 1, 3, 5, 8, 13, and 21 degrees C for five months. Compared to soil and litter mineralization, sediment OC mineralization rates were low in spite of low apparent activation energy (E-a). The fraction of the total OC pool that was lost during five months varied between 0.4 and 14.8%. We estimate that the sediment OC pool not becoming long-term preserved was degraded with average apparent turnover times between 3 and 32years. While OC mineralization was strongly dependent on temperature as well as on OC composition and origin, temperature sensitivity was similar across lakes and over time. We suggest that the temperature sensitivity of OC mineralization in lake sediments is similar across systems within the relevant seasonal scales of OC supply and degradation.

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  • 3.
    Guillemette, Francois
    et al.
    Uppsala University, Sweden.
    von Wachenfeldt, Eddie
    Uppsala University, Sweden; Swedish University of Agriculture Science, Sweden.
    Kothawala, Dolly N.
    Uppsala University, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Tranvik, Lars J.
    Uppsala University, Sweden.
    Preferential sequestration of terrestrial organic matter in boreal lake sediments2017Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, nr 4, s. 863-874Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The molecular composition and origin has recently been demonstrated to play a critical role in the persistence of organic matter in lake water, but it is unclear to what degree chemical attributes and sources may also control settling and burial of organic matter in lake sediments. Here we compared the annual contribution of allochthonous and autochthonous sources to the organic matter settling in the water column and present in the sediments of 12 boreal lakes. We used the fluorescence properties and elemental composition of the organic matter to trace its origin and found a consistent pattern of increasing contribution of terrestrial compounds in the sediments as compared to the settling matter, with an annual average allochthony of similar to 87% and similar to 57%, respectively. Seasonal data revealed a predominance of in-lake-produced compounds sinking in the water column in summer. Yet only a slight concurrent decrease in the contribution of terrestrial C to lake sediments was observed during the same period, and sediment allochthony increased again to high levels in autumn. Our results reveal a preferential preservation of allochthonous matter in the sediments and highlight the role of lakes as sequesters of organic carbon primarily originating from the surrounding landscape.

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  • 4.
    Johnson, Matthew S.
    et al.
    NASA, CA 94035 USA.
    Matthews, Elaine
    NASA, CA USA.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Deemer, Bridget
    US Geol Survey, AZ 86001 USA.
    Du, Jinyang
    Univ Montana, MT 59812 USA.
    Genovese, Vanessa
    Calif State Univ Monterey Bay, CA USA.
    Spatiotemporal Methane Emission From Global Reservoirs2021Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 126, nr 8, artikel-id e2021JG006305Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inland aquatic systems, such as reservoirs, contribute substantially to global methane (CH4) emissions; yet are among the most uncertain components of the total CH4 budget. Reservoirs have received recent attention as they may generate high CH4 fluxes. Improved quantification of these CH4 fluxes, particularly their spatiotemporal distribution, is key to realistically incorporating them in CH4 modeling and budget studies. Here we report on a new global, gridded (0.25 degrees lat x 0.25 degrees lon) study of reservoir CH4 emissions, accounting for new knowledge regarding reservoir areal extent and distribution, and spatiotemporal emission patterns influenced by diurnal variability, temperature-dependent seasonality, satellite-derived freeze-thaw dynamics, and eco-climatic zone. The results of this new data set comprise daily CH4 emissions throughout the full annual cycle and show that reservoirs cover 297 x 10(3) km(2) globally and emit 10.1 Tg CH4 yr(-1) (1 sigma uncertainty range of 7.2-12.9 Tg CH4 yr(-1)) from diffusive (1.2 Tg CH4 yr(-1)) and ebullitive (8.9 Tg CH4 yr(-1)) emission pathways. This analysis of reservoir CH4 emission addresses multiple gaps and uncertainties in previous studies and represents an important contribution to studies of the global CH4 budget. The new data sets and methodologies from this study provide a framework to better understand and model the current and future role of reservoirs in the global CH4 budget and to guide efforts to mitigate reservoir-related CH4 emissions.

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  • 5.
    Johnson, Matthew S.
    et al.
    NASA Ames Res Ctr, CA 94035 USA.
    Matthews, Elaine
    NASA Ames Res Ctr, CA USA.
    Du, Jinyang
    Univ Montana, MT 59812 USA.
    Genovese, Vanessa
    Calif State Univ, CA USA.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Methane Emission From Global Lakes: New Spatiotemporal Data and Observation-Driven Modeling of Methane Dynamics Indicates Lower Emissions2022Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 127, nr 7, artikel-id e2022JG006793Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lakes have been highlighted as one of the largest natural sources of the greenhouse gas methane (CH4) to the atmosphere. However, global estimates of lake CH4 fluxes over the last 20 years exhibit widely different results ranging from 6 to 185 Tg CH4 yr(-1), which is to a large extent driven by differences in lake areas and thaw season lengths used. This has generated uncertainty regarding both lake fluxes and the global CH4 budget. This study constrains global lake water CH4 emissions by using new information on lake area and distribution and CH4 fluxes distinguished by major emission pathways; ecoclimatic lake type; satellite-derived ice-free emission period length; and diel- and temperature-related seasonal flux corrections. We produced gridded data sets at 0.25 degrees latitude x 0.25 degrees longitude spatial resolution, representing daily emission estimates over a full annual climatological cycle, appropriate for use in global CH4 budget estimates, climate and Earth System Models, bottom-up biogeochemical models, and top-down inverse model simulations. Global lake CH4 fluxes are 41.6 +/- 18.3 Tg CH4 yr(-1) with approximately 50% of the flux contributed by tropical/subtropical lakes. Strong temperature-dependent flux seasonality and satellite-derived freeze/thaw dynamics limit emissions at high latitudes. The primary emission pathway for global annual lake fluxes is ebullition (23.4 Tg) followed by diffusion (14.1 Tg), ice-out and spring water-column turnover (3.1 Tg), and fall water-column turnover (1.0 Tg). These results represent a major contribution to reconciling differences between bottom-up and top-town estimates of inland aquatic system emissions in the global CH4 budget.

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  • 6.
    Karlson, Martin
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Multi‐Source Mapping of Peatland Types Using Sentinel‐1, Sentinel‐2, and Terrain Derivatives—A Comparison Between Five High‐Latitude Landscapes2023Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 128, nr 4, artikel-id e2022JG007195Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mapping wetland types in northern-latitude regions with Earth Observation (EO) data is important for several practical and scientific applications, but at the same time challenging due to the variability and dynamic nature in wetland features introduced by differences in geophysical conditions. The objective of this study was to better understand the ability of Sentinel-1 radar data, Sentinel-2 optical data and terrain derivatives derived from Copernicus digital elevation model to distinguish three main peatland types, two upland classes, and surface water, in five contrasting landscapes located in the northern parts of Alaska, Canada and Scandinavia. The study also investigated the potential benefits for classification accuracy of using regional classification models constructed from region-specific training data compared to a global classification model based on pooled reference data from all five sites. Overall, the results show high promise for classifying peatland types and the three other land cover classes using the fusion approach that combined all three EO data sources (Sentinel-1, Sentinel-2 and terrain derivatives). Overall accuracy for the individual sites ranged between 79.7% and 90.3%. Class specific accuracies for the peatland types were also high overall but differed between the five sites as well as between the three classes bog, fen and swamp. A key finding is that regional classification models consistently outperformed the global classification model by producing significantly higher classification accuracies for all five sites. This suggests for progress in identifying effective approaches for continental scale peatland mapping to improve scaling of for example, hydrological- and greenhouse gas-related processes in Earth system models.

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  • 7.
    Metson, Genevieve
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. Natl Acad Sci, DC 20418 USA; US EPA, OR 97333 USA; Washington State Univ, WA 98686 USA.
    Lin, Jiajia
    Natl Acad Sci, DC 20418 USA; US EPA, OR 97333 USA; Oak Ridge Inst Sci & Educ, OR USA.
    Harrison, John A.
    Washington State Univ, WA 98686 USA.
    Compton, Jana E.
    US EPA, OR 97333 USA.
    Where Have All the Nutrients Gone? Long-Term Decoupling of Inputs and Outputs in the Willamette River Watershed, Oregon, United States2020Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 125, nr 10, artikel-id e2020JG005792Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Better documentation and understanding of long-term temporal dynamics of nitrogen (N) and phosphorus (P) in watersheds is necessary to support effective water quality management, in part because studies have identified time lags between terrestrial nutrient balances and water quality. We present annual time series data from 1969 to 2012 for terrestrial N and P sources and monthly data from 1972 to 2013 for river N and P for the Willamette River Basin, Oregon, United States. Inputs to the watershed increased by factors of 3 for N and 1.2 for P. Synthetic fertilizer inputs increased in total and relative importance over time, while sewage inputs decreased. For N, increased fertilizer application was not matched by a proportionate increase in crop harvest; N use efficiency decreased from 69% to 38%. P use efficiency increased from 52% to 67%. As nutrient inputs to terrestrial systems increased, river concentrations and loads of total N, total P, and dissolved inorganic P decreased, and annual nutrient loads were strongly related to discharge. The N:P ratio of both sewage and fertilizer doubled over time but there was no similar trend in riverine export; river N:P concentrations declined dramatically during storms. River nutrient export over time was related to hydrology and waste discharge, with relatively little influence of watershed balances, suggesting that accumulation within soils or groundwater over time is mediating watershed export. Simply managing yearly nutrient balances is unlikely to improve water quality; rather, many factors must be considered, including soil and groundwater storage capacity, and gaseous loss pathways.

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  • 8.
    Natchimuthu, Sivakiruthika
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Klemedtsson, Leif
    University of Gothenburg, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Spatiotemporal variability of lake pCO(2) and CO2 fluxes in a hemiboreal catchment2017Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, nr 1, s. 30-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Globally, lakes are frequently supersaturated with carbon dioxide (CO2) and are major emitters of carbon to the atmosphere. Recent studies have generated awareness of the high variability in pCO(2aq) (the partial pressure corresponding to the concentration in water) and CO2 fluxes to the atmosphere and the need for better accounting for this variability. However, studies simultaneously accounting for both spatial and temporal variability of pCO(2aq) and CO2 fluxes in lakes are rare. We measured pCO(2aq) (by both manual sampling and mini loggers) and CO2 fluxes, covering spatial variability in open water areas of three lakes of different character in a Swedish catchment for 2years. Spatial pCO(2aq) variability within lakes was linked to distance from shore, proximity to stream inlets, and deepwater upwelling events. Temporally, pCO(2aq) variability was linked with variability in dissolved organic carbon, total nitrogen, and dissolved oxygen. While previous studies over short time periods (1 to 6h) observed gas transfer velocity (k) to be more variable than pCO(2aq), our work shows that over longer time (days to weeks) pCO(2aq) variability was greater and affected CO2 fluxes much more than k. We demonstrate that 8 measurement days distributed over multiple seasons in combination with sufficient spatial coverage (8 locations during stratification periods and 5 or less in spring and autumn) are a key for representative yearly whole lake flux estimates. This study illustrates the importance of considering spatiotemporal variability in pCO(2aq) and CO2 fluxes to generate representative whole lake estimates.

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  • 9.
    Pajala, Gustav
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sawakuchi, Henrique
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Rudberg, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Schenk, Jonathan
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sieczko, Anna
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Gålfalk, Magnus
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Seekell, David
    Umea Univ, Sweden.
    Sundgren, Ingrid
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Nguyen, Thanh Duc
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Karlsson, Jan
    Umea Univ, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    The Effects of Water Column Dissolved Oxygen Concentrations on Lake Methane Emissions-Results From a Whole-Lake Oxygenation Experiment2023Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 128, nr 11, artikel-id e2022JG007185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lakes contribute 9%-19% of global methane (CH4) emissions to the atmosphere. Dissolved molecular oxygen (DO) in lakes can inhibit the production of CH4 and promote CH4 oxidation. DO is therefore often considered an important regulator of CH4 emissions from lakes. Presence or absence of DO in the water above the sediments can affect CH4 production and emissions by (a) influencing if methane production can be fueled by the most reactive organic matter in the top sediment layer or rely on deeper and less degradable organic matter, and (b) enabling CH4 accumulation in deep waters and potentially large emissions upon water column turnover. However, the relative importance of these two DO effects on CH4 fluxes is still unclear. We assessed CH4 fluxes from two connected lake basins in northern boreal Sweden where one was experimentally oxygenated. Results showed no clear difference in summer CH4 emissions attributable to water column DO concentrations. Large amounts of CH4 accumulated in the anoxic hypolimnion of the reference basin but little of this may have been emitted because of incomplete mixing, and effective methane oxidation of stored CH4 reaching oxic water layers. Accordingly, <= 24% of the stored CH4 was likely emitted in the experimental lake. Overall, our results suggest that hypolimnetic DO and water column CH4 storage might have a smaller impact on CH4 emissions in boreal forest lakes than previous estimates, yet potential fluxes associated with water column turnover events remain a significant uncertainty in lake CH4 emission estimates.

  • 10.
    Rudberg, David
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Duc, N. T.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Schenk, Jonathan
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sieczko, Anna Katarzyna
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Pajala, Gustav
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Sawakuchi, Henrique Oliveira
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Department of Ecology and Environmental Sciences, Umeå Universitet, Umeå, Sweden.
    Verheijen, H. A.
    Department of Ecology and Environmental Sciences, Umeå Universitet, Umeå, Sweden.
    Melack, J. M.
    Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA University of California Santa Barbara, Earth Research Institute, Santa Barbara, CA, USA.
    MacIntyre, S.
    Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA University of California Santa Barbara, Earth Research Institute, Santa Barbara, CA, USA University of California Santa Barbara, Marine Science Institute, Santa Barbara, CA, USA.
    Karlsson, J.
    Department of Ecology and Environmental Sciences, Umeå Universitet, Umeå, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Diel Variability of CO2 Emissions From Northern Lakes2021Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 126, nr 10, artikel-id e2021JG006246Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lakes are generally supersaturated in carbon dioxide (CO2) and emitters of CO2 to the atmosphere. However, estimates of CO2 flux (FCO2) from lakes are seldom based on direct flux measurements and usually do not account for nighttime emissions, yielding risk of biased assessments. Here, we present direct FCO2 measurements from automated floating chambers collected every 2-3 hr and spanning 115 24 hr periods in three boreal lakes during summer stratification and before and after autumn mixing in the most eutrophic lake of these. We observed 40%-67% higher mean FCO2 in daytime during periods of surface water CO2 supersaturation in all lakes. Day-night differences in wind speed were correlated with the day-night FCO2 differences in the two larger lakes, but in the smallest and most wind-sheltered lake peaks of FCO2 coincided with low-winds at night. During stratification in the eutrophic lake, CO2 was near equilibrium and diel variability of FCO2 insignificant, but after autumn mixing FCO2 was high with distinct diel variability making this lake a net CO2 source on an annual basis. We found that extrapolating daytime measurements to 24 hr periods overestimated FCO2 by up to 30%, whereas extrapolating measurements from the stratified period to annual rates in the eutrophic lake underestimated FCO2 by 86%. This shows the importance of accounting for diel and seasonal variability in lake CO2 emission estimates.

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  • 11.
    Sabo, Robert D.
    et al.
    U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, U.S. EPA, Washington, DC, USA.
    Clark, Christopher M.
    U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, U.S. EPA, Washington, DC, USA.
    Gibbs, David A.
    World Resources Institute, Washington, DC, USA.
    Metson, Genevieve
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för klimatpolitisk forskning, CSPR.
    Todd, M. Jason
    U.S. Environmental Protection Agency, Office of Chemical Safety and Pollution, U.S. EPA, Washington, DC, USA.
    LeDuc, Stephen D.
    U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, U.S. EPA, Research Triangle Park, NC, USA.
    Greiner, Diana
    U.S. Environmental Protection Agency, Region 6 Office, U.S. EPA, Dallas, TX, USA.
    Fry, Meridith M.
    U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, U.S. EPA, Washington, DC, USA.
    Polinsky, Robyn
    U.S. Environmental Protection Agency, Region 4 Office, U.S. EPA, Atlanta, GA, USA.
    Yang, Qichun
    Pacific Northwest National Lab, Richland, WA, USA.
    Tian, Hanqin
    Auburn University, Auburn, AL, USA.
    Compton, Jana E.
    U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, U.S. EPA, Corvallis, OR, USA.
    Phosphorus Inventory for the Conterminous United States (2002-2012)2021Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 126, nr 4, artikel-id e2020JG005684Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Published reports suggest efforts designed to prevent the occurrence of harmful algal blooms and hypoxia by reducing non‐point and point source phosphorus (P) pollution are not delivering water quality improvements in many areas. Part of the uncertainty in evaluating watershed responses to management practices is the lack of standardized estimates of phosphorus inputs and outputs. To assess P trends across the conterminous United States, we compiled an inventory using publicly available datasets of agricultural P fluxes, atmospheric P deposition, human P demand and waste, and point source discharges for 2002, 2007 and 2012 at the scale of the 8‐digit Hydrologic Unit Code subbasin (∼1800 km2). Estimates of agricultural legacy P surplus accumulated from 1945‐2001 were also developed. Fertilizer and manure inputs were found to continue exceed crop removal rates by up to 50% in many agricultural regions. This excess in inputs has led to the continued accumulation of legacy P in agricultural lands. Atmospheric P deposition increased throughout the Rockies, potentially contributing to reported increases in surface water P concentrations in undisturbed watersheds. In some urban areas, P fluxes associated with human waste and non‐farm fertilizer use has declined despite population growth, likely due, in part, to various sales bans on P‐containing detergents and fertilizers. Although regions and individual subbasins have different contemporary and legacy P sources, a standardized method of accounting for large and small fluxes and ready to use inventory numbers are essential for coordinated and targeted interventions to reduce P concentrations in the nation's waters.

  • 12.
    Sawakuchi, Henrique
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Umea Univ, Sweden.
    Martin, Gaetan
    Swedish Univ Agr Sci, Sweden.
    Peura, Sari
    Swedish Univ Agr Sci, Sweden.
    Bertilsson, Stefan
    Swedish Univ Agr Sci, Sweden.
    Karlsson, Jan
    Umea Univ, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Phosphorus Regulation of Methane Oxidation in Water From Ice-Covered Lakes2021Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 126, nr 9, artikel-id e2020JG006190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Winter methane (CH4) accumulation in seasonally ice-covered lakes can contribute to large episodic emissions to the atmosphere during spring ice melt. Biological methane oxidation can significantly mitigate such CH4 emissions, but despite favorable CH4 and O-2 concentrations, CH4 oxidation appears constrained in some lakes for unknown reasons. Here we experimentally test the hypothesis that phosphorus (P) availability is limiting CH4 oxidation, resulting in differences in ice-out emissions among lakes. We observed a positive relationship between potential CH4 oxidation and P concentration across 12 studied lakes and found an increase in CH4 oxidation in response to P amendment, without any parallel change in the methanotrophic community composition. Hence, while an increase in sedimentary CH4 production and ebullitive emissions may happen with eutrophication, our study indicates that the increase in P associated with eutrophication may also enhance CH4 oxidation. The increase in CH4 oxidation may hence play an important role in nutrient-rich ice-covered lakes where bubbles trapped under the ice may to a greater extent be oxidized, reducing the ice-out emissions of CH4. This may be an important factor regulating CH4 emissions from high latitude lakes.

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  • 13.
    Schilder, J.
    et al.
    University of Bern, Switzerland; University of Jyvaskyla, Finland.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    van Hardenbroek, M.
    University of Bern, Switzerland; University of Southampton, England.
    Heiri, O.
    University of Bern, Switzerland.
    Spatiotemporal patterns in methane flux and gas transfer velocity at low wind speeds: Implications for upscaling studies on small lakes2016Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, nr 6, s. 1456-1467Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lakes contribute significantly to the global natural emissions of methane (CH4) and carbon dioxide. However, to accurately incorporate them into the continental carbon balance more detailed surveys of lacustrine greenhouse gas emissions are needed, especially in respect to spatiotemporal variability and to how this affects the upscaling of results. We investigated CH4 flux from a small, wind-shielded lake during 10 field trips over a 14month period. We show that floating chambers may be used to calibrate the relationship between gas transfer velocity (k) and wind speed at 10m height (U-10) to the local system, in order to obtain more accurate estimates of diffusive CH4 flux than by applying general models predicting k based on U-10. We confirm earlier studies indicating strong within-lake spatial variation in this relationship and in ebullitive CH4 flux within the lake basin. However, in contrast to the pattern reported in other studies, ebullitive CH4 flux was highest in the central parts of the lake. Our results indicate positive relationships between k and U-10 at very low U-10 (0-3ms(-1)), which disagrees with earlier suggestions that this relationship may be negligible at low U-10 values. We estimate annually averaged open water CH4 emission from Lake Gerzensee to be 3.6-5.8mmolm(-2)d(-1). Our data suggest that estimates of greenhouse gas emissions from aquatic systems to the atmosphere based on the upscaling of short-term and small-scale measurements can be improved if both spatial and temporal variabilities of emissions are taken into account.

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  • 14.
    Sobek, Sebastian
    et al.
    Uppsala University, Sweden.
    Gudasz, Cristian
    Uppsala University, Sweden; Umeå University, Sweden.
    Koehler, Birgit
    Uppsala University, Sweden.
    Tranvik, Lars J.
    Uppsala University, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Morales-Pineda, Maria
    University of Cadiz, Spain.
    Temperature Dependence of Apparent Respiratory Quotients and Oxygen Penetration Depth in Contrasting Lake Sediments2017Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, nr 11, s. 3076-3087Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lake sediments constitute an important compartment in the carbon cycle of lakes, by burying carbon over geological timescales and by production and emission of greenhouse gases. The degradation of organic carbon (OC) in lake sediments is linked to both temperature and oxygen (O-2), but the interactive nature of this regulation has not been studied in lake sediments in a quantitative way. We present the first systematic investigation of the effects of temperature on the apparent respiratory quotient (RQ, i.e., the molar ratio between carbon dioxide (CO2) production and O-2 consumption) in two contrasting lake sediments. Laboratory incubations of sediment cores of a humic lake and an eutrophic lake across a 1-21 degrees C temperature gradient over 157days revealed that both CO2 production and O-2 consumption were positively, exponentially, and similarly dependent on temperature. The apparent RQ differed significantly between the lake sediments (0.630.26 and 0.990.28 in the humic and the eutrophic lake, respectively; meanSD) and was significantly and positively related to temperature. The O-2 penetration depth into the sediment varied by a factor of 2 over the 1-21 degrees C temperature range and was significantly, negatively, and similarly related to temperature in both lake sediments. Accordingly, increasing temperature may influence the overall extent of OC degradation in lake sediments by limiting O-2 supply to aerobic microbial respiration to the topmost sediment layer, resulting in a concomitant shift to less effective anaerobic degradation pathways. This suggests that temperature may represent a key controlling factor of the OC burial efficiency in lake sediments.

  • 15.
    Wallin, Marcus B.
    et al.
    Uppsala University, Sweden; Uppsala University, Sweden.
    Weyhenmeyer, Gesa A.
    Uppsala University, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Chmiel, Hannah E.
    Uppsala University, Sweden.
    Peter, Simone
    Uppsala University, Sweden.
    Sobek, Sebastian
    Uppsala University, Sweden.
    Klemedtsson, Leif
    University of Gothenburg, Sweden.
    Temporal control on concentration, character, and export of dissolved organic carbon in two hemiboreal headwater streams draining contrasting catchments2015Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 120, nr 5, s. 832-846Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although lateral carbon (C) export from terrestrial to aquatic systems is known to be an important component in landscape C balances, most existing global studies are lacking empirical data on the soil C export. In this study, the concentration, character, and export of dissolved organic carbon (DOC) were studied during 2years in two hemiboreal headwater streams draining catchments with different soil characteristics (mineral versus peat soils). The streams exposed surprisingly similar strong air temperature controls on the temporal variability in DOC concentration in spite of draining such different catchments. The temporal variability in DOC character (determined by absorbance metrics, specific ultraviolet absorbance 254 (SUVA(254)) as a proxy for aromaticity and a254/a365 ratio as a proxy for mean molecular weight) was more complex but related to stream discharge. While the two streams showed similar ranges and patterns in SUVA(254), we found a significant difference in median a254/a354, suggesting differences in the DOC character. Both streams responded similarly to hydrological changes with higher a254/a365 at higher discharge, although with rather small differences in a254/a365 between base flow and high flow (less than0.3). The DOC exports (9.6-25.2gCm(-2)yr(-1)) were among the highest reported so far for Scandinavia and displayed large interannual and intraannual variability mainly driven by irregular precipitation/discharge patterns. Our results show that air temperature and discharge affect the temporal variability in DOC quantity and character in different ways. This will have implications for the design of representative sampling programs, which in turn will affect the reliability of future estimates of landscape C budgets.

  • 16.
    Watts, Emily G.
    et al.
    Univ Florida, FL 32611 USA.
    Hylen, Astrid
    Univ Antwerp, Belgium; Univ Gothenburg, Sweden.
    Hall, Per O. J.
    Univ Gothenburg, Sweden.
    Eriksson, Mats
    Linköpings universitet, Institutionen för hälsa, medicin och vård, Avdelningen för diagnostik och specialistmedicin. Linköpings universitet, Medicinska fakulteten.
    Robertson, Elizabeth K.
    Univ Gothenburg, Sweden.
    Kenney, William F.
    Univ Florida, FL USA.
    Bianchi, Thomas S.
    Univ Florida, FL 32611 USA.
    Burial of Organic Carbon in Swedish Fjord Sediments: Highlighting the Importance of Sediment Accumulation Rate in Relation to Fjord Redox Conditions2024Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 129, nr 4, artikel-id e2023JG007978Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fjords are net carbon sinks with high organic carbon (OC) burial rates; however, the key drivers of OC burial in these systems are not well constrained. To study the role of water column redox condition and OC composition on OC preservation in fjord sediments, we determined OC accumulation rates (OCAR), OC source, and OC degradation in three Swedish fjords with variable redox conditions (long-term oxic, seasonally hypoxic, and long-term anoxic). Average OCARs were variable between and within the fjords studied (2-122 g OC m-2 yr-1), but highest rates were at the mouth for each fjord. Based on a delta 13C mixing model, Swedish fjords bury predominantly marine-derived OC (similar to 83% of the total OC burial) likely because of relatively gentle slopes, low riverine discharge, and high marine inflow. Using a multi-biomarker approach (lignin, photosynthetic pigments, and total hydrolyzable amino acids) we found, terrestrially- and marine-derived OC were moderately degraded under the various redox conditions sampled, suggesting water column redox and OC source are not primary drivers of OC burial in these fjords. Rather, high sediment accumulation rates, common to fjords globally, lead to low oxygen exposure times, thus promoting efficient burial of OC regardless of its chemical composition. Fjords are net carbon sinks due in part to very high organic carbon burial rates. Despite being important in the regulation of earth's climate, the drivers of organic carbon burial in fjords are not well constrained. Here, we characterize the organic carbon buried in Swedish fjord sediments under different oxygen regimes (long-term oxic, seasonally hypoxic, and long-term anoxic) using bulk elemental and biomarker analyses. These fjords effectively bury organic carbon regardless of organic carbon source and water column oxygen conditions, likely because of high sediment accumulation rates. Fjords represent distinctive coastal systems with the capacity to retain reactive organic carbon, underscoring the importance of exploring these ecosystems in the context of global change. Swedish fjords bury primarily marine-derived organic carbon under long-term oxic, seasonally hypoxic, and long-term anoxic water columns Organic carbon burial in Swedish fjords is largely controlled by sediment accumulation rate which can limit oxygen exposure time Marine-dominated fjords are uniquely efficient sinks of labile organic carbon

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