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  • 1.
    Bastviken, David
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Sundgren, Ingrid
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Natchimuthu, Sivakiruthika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Reyier, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Gålfalk, Magnus
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Technical Note: Cost-efficient approaches to measure carbon dioxide (CO2) fluxes and concentrations in terrestrial and aquatic environments using mini loggers2015In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 12, no 12, p. 3849-3859Article in journal (Refereed)
    Abstract [en]

    Fluxes of CO2 are important for our understanding of the global carbon cycle and greenhouse gas balances. Several significant CO2 fluxes in nature may still be unknown as illustrated by recent findings of high CO2 emissions from aquatic environments, previously not recognized in global carbon balances. Therefore, it is important to develop convenient and affordable ways to measure CO2 in many types of environments. At present, direct measurements of CO2 fluxes from soil or water, or CO2 concentrations in surface water, are typically labor intensive or require costly equipment. We here present an approach with measurement units based on small inexpensive CO2 loggers, originally made for indoor air quality monitoring, that were tested and adapted for field use. Measurements of soil-atmosphere and lake-atmosphere fluxes, as well as of spatiotemporal dynamics of water CO2 concentrations (expressed as the equivalent partial pressure, pCO(2aq)) in lakes and a stream network are provided as examples. Results from all these examples indicate that this approach can provide a cost- and labor-efficient alternative for direct measurements and monitoring of CO2 flux and pCO(2aq) in terrestrial and aquatic environments.

  • 2.
    Bäckstrand, Kristina
    et al.
    Stockholm University.
    Crill, P. M.
    Stockholm University.
    Jackowicz-Korczyñski, M.
    Lund University.
    Mastepanov, M.
    Lund University.
    Christensen, T. R.
    Lund University.
    Bastviken, David
    Department of Geology and Geochemistry, Stockholm University.
    Annual carbon gas budget for a subarctic peatland, northern Sweden2010In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 7, p. 95-108Article in journal (Other academic)
    Abstract [en]

     Temperatures in the Arctic regions are rising, thawing permafrost and exposing previously stable soil organic carbon (OC) to decomposition. This can result in northern latitude soils, which have accumulated large amounts of OC potentially shifting from atmospheric C sinks to C sources with positive feedback on climate warming. In this paper, we estimate the annual net C gas balance (NCB) of the subarctic mire Stordalen, based on automatic chamber measurements of CO2 and total hydrocarbon (THC; CH4 and NMVOCs) exchange. We studied the dominant vegetation communities with different moisture and permafrost characteristics; a dry Palsa underlain by permafrost, an intermediate thaw site with Sphagnum spp. and a wet site with Eriophorum spp. where the soil thaws completely. Whole year accumulated fluxes of CO2 were estimated to 29.7, −35.3 and −34.9 gC m−2 respectively for the Palsa, Sphagnum and Eriophorum sites (positive flux indicates an addition of C to the atmospheric pool). The corresponding annual THC emissions were 0.5, 6.2 and 31.8 gC m−2 for the same sites. Therefore, the NCB for each of the sites was 30.2, −29.1 and −3.1 gC m−2 respectively for the Palsa, Sphagnum and Eriophorum site. On average, the whole mire was a CO2 sink of 2.6 gC m−2 and a THC source of 6.4 gC m−2 over a year. Consequently, the mire was a net source of C to the atmosphere by 3.9 gC m−2 (based on area weighted estimates for each of the three plant communities). Early and late snow season efflux of CO2 and THC emphasize the importance of winter measurements for complete annual C budgets. Decadal vegetation changes at Stordalen indicate that both the productivity and the THC emissions increased between 1970 and 2000. Considering the GWP100 of CH4, the net radiative forcing on climate increased 21% over the same time. In conclusion, reduced C compounds in these environments have high importance for both the annual C balance and climate.

  • 3.
    Conrad, Ralf
    et al.
    Max Planck Inst Terr Microbiol, Germany.
    Klose, Melanie
    Max Planck Inst Terr Microbiol, Germany.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Univ Fed Rio de Janeiro, Brazil.
    Acetate turnover and methanogenic pathways in Amazonian lake sediments2020In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 17, no 4, p. 1063-1069Article in journal (Refereed)
    Abstract [en]

    Lake sediments in Amazonia are a significant source of CH4, a potential greenhouse gas. Previous studies of sediments using C-13 analysis found that the contribution of hydrogenotrophic versus acetoclastic methanogenesis to CH4 production was relatively high. Here, we determined the methanogenic pathway in the same sediments (n = 6) by applying (14)Cbicarbonate or 2-(14)Cacetate and confirmed the high relative contribution (50 %-80 %) of hydrogenotrophic methanogenesis. The respiratory index (RI) of 2-(14)Cacetate, which is (CO2)-C-14 relative to (CH4)-C-14 +(CO2)-C-14, divided the sediments into two categories, i.e., those with an RI amp;lt; 0.2 consistent with the operation of acetoclastic methanogenesis and those with an RI amp;gt; 0.4 showing that a large percentage of the acetate-methyl was oxidized to CO2 rather than reduced to CH4. Hence, part of the acetate was probably converted to CO2 plus H-2 via syntrophic oxidation, thus enhancing hydrogenotrophic methanogenesis. This happened despite the presence of potentially acetoclastic Methanosaetaceae in all the sediments. Alternatively, acetate may have been oxidized with a constituent of the sediment organic matter (humic acid) serving as oxidant. Indeed, apparent acetate turnover rates were larger than CH4 production rates except in those sediments with a Ramp;lt;0.2. Our study demonstrates that CH4 production in Amazonian lake sediments was not simply caused by a combination of hydrogenotrophic and acetoclastic methanogenesis but probably involved additional acetate turnover.

  • 4.
    de Araujo, Kleiton R.
    et al.
    Univ Fed Para, Brazil.
    Sawakuchi, Henrique
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Univ Sao Paulo, Brazil; Umea Univ, Sweden.
    Bertassoli, Dailson J. Jr.
    Univ Sao Paulo, Brazil.
    Sawakuchi, Andre O.
    Univ Fed Para, Brazil; Univ Sao Paulo, Brazil.
    da Silva, Karina D.
    Univ Fed Para, Brazil; Univ Fed Para, Brazil.
    Vieira, Thiago B.
    Univ Fed Para, Brazil; Univ Fed Para, Brazil.
    Ward, Nicholas D.
    Pacific Northwest Natl Lab, WA 98382 USA; Univ Washington, WA 98195 USA.
    Pereira, Tatiana S.
    Univ Fed Para, Brazil; Univ Fed Para, Brazil.
    Carbon dioxide (CO2) concentrations and emission in the newly constructed Belo Monte hydropower complex in the Xingu River, Amazonia2019In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 16, no 18, p. 3527-3542Article in journal (Refereed)
    Abstract [en]

    The Belo Monte hydropower complex located in the Xingu River is the largest run-of-the-river (ROR) hydroelectric system in the world and has one of the highest energy production capacities among dams. Its construction received significant media attention due to its potential social and environmental impacts. It is composed of two ROR reservoirs: the Xingu Reservoir (XR) in the Xingus main branch and the Intermediate Reservoir (IR), an artificial reservoir fed by waters diverted from the Xingu River with longer water residence time compared to XR. We aimed to evaluate spatiotemporal variations in CO2 partial pressure (pCO(2)) and CO2 fluxes (FCO2) during the first 2 years after the Xingu River impoundment under the hypothesis that each reservoir has contrasting FCO2 and pCO(2) as vegetation clearing reduces flooded area emissions. Time of the year had a significant influence on pCO(2) with the highest average values observed during the high-water season. Spatial heterogeneity throughout the entire study area was observed for pCO(2) during both low-and high-water seasons. FCO2, on the other hand, only showed significant spatial heterogeneity during the high-water period. FCO2 (0.90 +/- 0.47 and 1.08 +/- 0.62 mu mol m(2) d(-1) for XR and IR, respectively) and pCO(2) (1647 +/- 698 and 1676 +/- 323 mu atm for XR and IR, respectively) measured during the high-water season were on the same order of magnitude as previous observations in other Amazonian clearwater rivers unaffected by impoundment during the same season. In contrast, during the low-water season FCO2 (0.69 +/- 0.28 and 7.32 +/- 4.07 mu mol m(2) d(-1) for XR and IR, respectively) and pCO(2) (839 +/- 646 and 1797 +/- 354 mu atm for XR and IR, respectively) in IR were an order of magnitude higher than literature FCO2 observations in clearwater rivers with naturally flowing waters. When CO2 emissions are compared between reservoirs, IR emissions were 90% higher than values from the XR during low-water season, reinforcing the clear influence of reservoir characteristics on CO2 emissions. Based on our observations in the Belo Monte hydropower complex, CO2 emissions from ROR reservoirs to the atmosphere are in the range of natural Amazonian rivers. However, the associated reservoir (IR) may exceed natural river emission rates due to the preimpounding vegetation influence. Since many reservoirs are still planned to be constructed in the Amazon and throughout the world, it is critical to evaluate the implications of reservoir traits on FCO2 over their entire life cycle in order to improve estimates of CO2 emissions per kilowatt for hydropower projects planned for tropical rivers.

  • 5.
    Erkkila, Kukka-Maaria
    et al.
    Univ Helsinki, Finland.
    Ojala, Anne
    Univ Helsinki, Finland.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Biermann, Tobias
    Lund Univ, Sweden.
    Heiskanen, Jouni J.
    Univ Helsinki, Finland.
    Lindroth, Anders
    Lund Univ, Sweden.
    Peltola, Olli
    Univ Helsinki, Finland.
    Rantakari, Miitta
    Univ Helsinki, Finland; Univ Helsinki, Finland.
    Vesala, Timo
    Univ Helsinki, Finland.
    Mammarella, Ivan
    Univ Helsinki, Finland.
    Methane and carbon dioxide fluxes over a lake: comparison between eddy covariance, floating chambers and boundary layer method2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 2, p. 429-445Article in journal (Refereed)
    Abstract [en]

    Freshwaters bring a notable contribution to the global carbon budget by emitting both carbon dioxide (CO2) and methane (CH4) to the atmosphere. Global estimates of freshwater emissions traditionally use a wind-speed-based gas transfer velocity, k CC (introduced by Cole and Caraco, 1998), for calculating diffusive flux with the boundary layer method (BLM). We compared CH4 and CO2 fluxes from BLM with k CC and two other gas transfer velocities (k TE and k HE), which include the effects of water-side cooling to the gas transfer besides shear-induced turbulence, with simultaneous eddy covariance (EC) and floating chamber (FC) fluxes during a 16-day measurement campaign in September 2014 at Lake Kuivajarvi in Finland. The measurements included both lake stratification and water column mixing periods. Results show that BLM fluxes were mainly lower than EC, with the more recent model k TE giving the best fit with EC fluxes, whereas FC measurements resulted in higher fluxes than simultaneous EC measurements. We highly recommend using up-to-date gas transfer models, instead of kCC, for better flux estimates. BLM CO2 flux measurements had clear differences between daytime and night-time fluxes with all gas transfer models during both stratified and mixing periods, whereas EC measurements did not show a diurnal behaviour in CO2 flux. CH4 flux had higher values in daytime than night-time during lake mixing period according to EC measurements, with highest fluxes detected just before sunset. In addition, we found clear differences in daytime and night-time concentration difference between the air and surface water for both CH4 and CO2. This might lead to biased flux estimates, if only daytime values are used in BLM upscaling and flux measurements in general. FC measurements did not detect spatial variation in either CH4 or CO2 flux over Lake Kuivajarvi. EC measurements, on the other hand, did not show any spatial variation in CH4 fluxes but did show a clear difference between CO2 fluxes from shallower and deeper areas. We highlight that while all flux measurement methods have their pros and cons, it is important to carefully think about the chosen method and measurement interval, as well as their effects on the resulting flux.

  • 6.
    Gonsior, M
    et al.
    University of Maryland, MD 20688 USA .
    Schmitt-Kopplin, P
    German Research Centre Environm Heatlh, Germany .
    Bastviken, David
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Depth-dependent molecular composition and photo-reactivity of dissolved organic matter in a boreal lake under winter and summer conditions2013In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 10, no 11, p. 6945-6956Article in journal (Refereed)
    Abstract [en]

    Transformations of dissolved organic matter (DOM) in boreal lakes lead to large greenhouse gas emissions as well as substantial carbon storage in sediments. Using novel molecular characterization approaches and photochemical degradation experiments we studied how seasonal patterns in water column stratification affected the DOM in a Swedish lake under early spring and summer conditions. Dissolved organic carbon (DOC) concentrations were consistently higher above the sediment when compared to surface waters throughout the sampling periods. Photobleaching alone could not explain this difference in DOC because the lake was covered by 40 cm-thick ice during late winter sampling and still showed the same DOC trend. The differences in the molecular diversity between surface DOM in winter and summer were consistent with ongoing photobleaching/ decarboxylation and a possible bacterial consumption of photo-products. Additional photo-degradation experiments using simulated sunlight showed a production of highly oxidized organic molecules and low molecular weight compounds in all late winter samples and also in the deep water sample in summer. In the surface summer DOM sample, few such molecules were produced during the photo-degradation experiments, confirming that DOM was already photobleached prior to the experiments. This study suggests that photobleaching, and therefore also the ice cover during winter, plays a central role in surface DOM transformation, with important differences in the molecular composition of DOM between surface and deep boreal lake waters. The release of DOC from boreal lake sediments also contribute to this pattern. Photochemical degradation of DOM may be more extensive following ice-out and water column turnover when non-light exposed and thereby photosensitive DOM is photo-mineralized. Hence, the yearly DOM photo-mineralization may be greater than inferred from studies of recently light-exposed DOM.

  • 7.
    Gonsior, Michael
    et al.
    University of Maryland, MD 20688 USA.
    Valle, Juliana
    University of Federal Rio de Janeiro, Brazil; Helmholtz Zentrum Munchen, Germany.
    Schmitt-Kopplin, Philippe
    Helmholtz Zentrum Munchen, Germany; Technical University of Munich, Germany.
    Hertkorn, Norbert
    Helmholtz Zentrum Munchen, Germany.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Luek, Jenna
    University of Maryland, MD 20688 USA.
    Harir, Mourad
    Helmholtz Zentrum Munchen, Germany.
    Bastos, Wanderley
    University of Federal Rondonia, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Chemodiversity of dissolved organic matter in the Amazon Basin2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 14, p. 4279-4290Article in journal (Refereed)
    Abstract [en]

    Regions in the Amazon Basin have been associated with specific biogeochemical processes, but a detailed chemical classification of the abundant and ubiquitous dissolved organic matter (DOM), beyond specific indicator compounds and bulk measurements, has not yet been established. We sampled water from different locations in the Negro, Madeira/Jamari and Tapajos River areas to characterize the molecular DOM composition and distribution. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) revealed a large proportion of ubiquitous DOM but also unique area-specific molecular signatures. Unique to the DOM of the Rio Negro area was the large abundance of high molecular weight, diverse hydrogen-deficient and highly oxidized molecular ions deviating from known lignin or tannin compositions, indicating substantial oxidative processing of these ultimately plant-derived polyphenols indicative of these black waters. In contrast, unique signatures in the Madeira/Jamari area were defined by presumably labile sulfur-and nitrogen-containing molecules in this white water river system. Waters from the Tapajos main stem did not show any substantial unique molecular signatures relative to those present in the Rio Madeira and Rio Negro, which implied a lower organic molecular complexity in this clear water tributary, even after mixing with the main stem of the Amazon River. Beside ubiquitous DOM at average H / C and O / C elemental ratios, a distinct and significant unique DOM pool prevailed in the black, white and clear water areas that were also highly correlated with EEM-PARAFAC components and define the frameworks for primary production and other aspects of aquatic life.

  • 8.
    Groeneveld, Marloes
    et al.
    Uppsala University, Sweden.
    Tranvik, Lars
    Uppsala University, Sweden.
    Natchimuthu, Sivakiruthika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Koehler, Birgit
    Uppsala University, Sweden.
    Photochemical mineralisation in a boreal brown water lake: considerable temporal variability and minor contribution to carbon dioxide production2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 13, p. 3931-3943Article in journal (Refereed)
    Abstract [en]

    Sunlight induces photochemical mineralisation of chromophoric dissolved organic matter (CDOM) to dissolved inorganic carbon (DIC) in inland waters, resulting in carbon dioxide (CO2) emissions to the atmosphere. Photochemical rate modelling is used to determine sunlight-induced CO2 emissions on large spatial and temporal scales. A sensitive model parameter is the wavelength-specific photochemical CDOM reactivity, the apparent quantum yield (AQY). However, the temporal variability of AQY spectra within inland waters remains poorly constrained. Here, we studied a boreal brown water lake in Sweden. We measured AQY spectra for photochemical DIC production monthly between June and November 2014 and parameterised a photochemical rate model. The total AQY between 280 and 600 nm increased about 3-fold during the open-water period, likely due to a high rainfall event with consecutive mixing in autumn that increased availability of highly photoreactive CDOM. However, the variability in AQY spectra over time was much smaller than previously reported variability in AQY spectra between lakes. Yet, using either the AQY spectrum from the least or from the most photoreactive water sample resulted in a 5-fold difference in simulated annual DIC photoproduction (2012-2014), with 2.0 +/- 0.1 and 10.3 +/- 0.7 g C m(-2) yr(-1), respectively. This corresponded to 1 and 8% of the mean CO2 emissions measured from this lake. We conclude that (1) it may be recommendable to conduct repeated AQY measurements throughout the season for more accurate simulation of annual photochemical DIC production in lakes and (2), in agreement with previous studies, direct CDOM photomineralisation makes only a minor contribution to mean CO2 emissions from Swedish brown water lakes.

  • 9.
    Gålfalk, Magnus
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlson, Martin
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Centre for Climate Science and Policy Research, CSPR.
    Crill, Patrick
    Stockholm Univ, Sweden.
    Bousquet, Philippe
    LSCE, France.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Technical note: A simple approach for efficient collection of field reference data for calibrating remote sensing mapping of northern wetlands2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 5, p. 1549-1557Article in journal (Refereed)
    Abstract [en]

    The calibration and validation of remote sensing land cover products are highly dependent on accurate field reference data, which are costly and practically challenging to collect. We describe an optical method for collection of field reference data that is a fast, cost-efficient, and robust alternative to field surveys and UAV imaging. A lightweight, waterproof, remote-controlled RGB camera (GoPro HERO4 Silver, GoPro Inc.) was used to take wide-angle images from 3.1 to 4.5 m in altitude using an extendable monopod, as well as representative near-ground (amp;lt; 1 m) images to identify spectral and structural features that correspond to various land covers in present lighting conditions. A semi-automatic classification was made based on six surface types (graminoids, water, shrubs, dry moss, wet moss, and rock). The method enables collection of detailed field reference data, which is critical in many remote sensing applications, such as satellite-based wetland mapping. The method uses common non-expensive equipment, does not require special skills or training, and is facilitated by a step-by-step manual that is included in the Supplement. Over time a global ground cover database can be built that can be used as reference data for studies of non-forested wetlands from satellites such as Sentinel 1 and 2 (10 m pixel size).

  • 10.
    Klaus, Marcus
    et al.
    Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
    Geibrink, Erik
    Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
    Jonsson, Anders
    Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
    Bergstrom, Ann-Kristin
    Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Laudon, Hjalmar
    Department of Forest Ecology and Management, Swedish University of Agricultural Science, Umeå, Sweden.
    Klaminder, Jonatan
    Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
    Karlsson, Jan
    Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
    Greenhouse gas emissions from boreal inland waters unchanged after forest harvesting2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 18, p. 5575-5594Article in journal (Refereed)
    Abstract [en]

    Forestry practices often result in an increased export of carbon and nitrogen to downstream aquatic systems. Although these losses affect the greenhouse gas (GHG) budget of managed forests, it is unknown if they modify GHG emissions of recipient aquatic systems. To assess this question, air-water fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) were quantified for humic lakes and their inlet streams in four boreal catchments using a before-after control-impact experiment. Two catchments were treated with forest clear-cuts followed by site preparation (18 % and 44 % of the catchment area). GHG fluxes and hydrological and physicochemical water characteristics were measured at multiple locations in lakes and streams at high temporal resolution throughout the summer season over a 4-year period. Both lakes and streams evaded all GHGs. The treatment did not significantly change GHG fluxes in streams or lakes within 3 years after the treatment, despite significant increases of CO2 and CH4 concentrations in hillslope groundwater. Our results highlight that GHGs leaching from forest clear-cuts may be buffered in the riparian zone-stream continuum, likely acting as effective biogeochemical processors and wind shelters to prevent additional GHG evasion via downstream inland waters. These findings are representative of low productive forests located in relatively flat landscapes where forestry practices cause only a limited initial impact on catchment hydrology and biogeochemistry.

  • 11.
    Lorke, A.
    et al.
    University of Koblenz Landau, Germany.
    Bodmer, P.
    Leibniz Institute Freshwater Ecol and Inland Fisheries, Germany; Free University of Berlin, Germany.
    Noss, C.
    University of Koblenz Landau, Germany.
    Alshboul, Z.
    University of Koblenz Landau, Germany.
    Koschorreck, M.
    UFZ Helmholtz Centre Environm Research, Germany.
    Somlai-Haase, C.
    University of Koblenz Landau, Germany.
    Bastviken, David
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Flury, S.
    Leibniz Institute Freshwater Ecol and Inland Fisheries, Germany.
    McGinnis, D. F.
    Leibniz Institute Freshwater Ecol and Inland Fisheries, Germany; University of Geneva, Switzerland.
    Maeck, A.
    Senect GmbH and Co KG, Germany.
    Mueller, D.
    Institute Environm Phys IUP, Germany; Centre Trop Marine Ecol ZMT, Germany.
    Premke, K.
    Leibniz Institute Freshwater Ecol and Inland Fisheries, Germany; Leibniz Centre Agriculture Landscape Research, Germany.
    Technical note: drifting versus anchored flux chambers for measuring greenhouse gas emissions from running waters2015In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 12, no 23, p. 7013-7024Article in journal (Refereed)
    Abstract [en]

    Stream networks have recently been discovered to be major but poorly constrained natural greenhouse gas (GHG) sources. A fundamental problem is that several measurement approaches have been used without cross-comparisons. Flux chambers represent a potentially powerful methodological approach if robust and reliable ways to use chambers on running water can be defined. Here we compare the use of anchored and freely drifting chambers on various streams with different flow velocities. The study clearly shows that (1) anchored chambers enhance turbulence under the chambers and thus elevate fluxes, (2) drifting chambers have a very small impact on the water turbulence under the chamber and thus generate more reliable fluxes, (3) the bias of the anchored chambers greatly depends on chamber design and sampling conditions, and (4) there is a promising method to reduce the bias from anchored chambers by using a flexible plastic foil collar to seal the chambers to the water surface, rather than having rigid chamber walls penetrating into the water. Altogether, these results provide novel guidance on how to apply flux chambers in running water, which will have important consequences for measurements to constrain the global GHG balances.

  • 12.
    Luyssaert, S
    et al.
    CEA CNRS UVSQ, France .
    Abril, G
    University of Bordeaux, France .
    Andres, R
    Oak Ridge National Lab, USA .
    Bastviken, David
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Bellassen, V
    CEA CNRS UVSQ, France .
    Bergamaschi, P
    European Commiss, Italy .
    Bousquet, P
    CEA CNRS UVSQ, France .
    Chevallier, F
    CEA CNRS UVSQ, France .
    Ciais, P
    CEA CNRS UVSQ, France .
    Corazza, M
    European Commiss, Italy .
    Dechow, R
    Johann Heinrich von Thunen Institute, Germany .
    -H Erb, K
    Alpen Adria University of Klagenfurt Vienna Graz, Austria .
    Etiope, G
    Ist Nazl Geofis Vulcanol, Italy .
    Fortems-Cheiney, A
    CEA CNRS UVSQ, France .
    Grassi, G
    European Commiss, Italy .
    Hartmann, J
    University of Hamburg, Germany .
    Jung, M
    Max Planck Institute Biogeochem, Germany .
    Lathiere, J
    CEA CNRS UVSQ, France .
    Lohila, A
    Finnish Meteorol Institute, Finland .
    Mayorga, E
    University of Washington, WA 98105 USA .
    Moosdorf, N
    University of Hamburg, Germany .
    S Njakou, D
    University of Antwerp, Belgium .
    Otto, J
    CEA CNRS UVSQ, France .
    Papale, D
    University of Tuscia, Italy .
    Peters, W
    Wageningen University, Netherlands .
    Peylin, P
    CEA CNRS UVSQ, France .
    Raymond, P
    Yale University, USA .
    Roedenbeck, C
    Max Planck Institute Biogeochem, Germany .
    Saarnio, S
    University of Eastern Finland, Finland University of Eastern Finland, Finland .
    Schulze, E-D
    Max Planck Institute Biogeochem, Germany .
    Szopa, S
    CEA CNRS UVSQ, France .
    Thompson, R
    CEA CNRS UVSQ, France .
    Verkerk, P J
    European Forest Institute, Finland .
    Vuichard, N
    CEA CNRS UVSQ, France .
    Wang, R
    Peking University, Peoples R China .
    Wattenbach, M
    Deutsch GeoForschungsZentrum GFZ, Germany .
    Zaehle, S
    Max Planck Institute Biogeochem, Germany .
    The European land and inland water CO2, CO, CH4 and N2O balance between 2001 and 20052012In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 9, no 8, p. 3357-3380Article in journal (Refereed)
    Abstract [en]

    Globally, terrestrial ecosystems have absorbed about 30% of anthropogenic greenhouse gas emissions over the period 2000-2007 and inter-hemispheric gradients indicate that a significant fraction of terrestrial carbon sequestration must be north of the Equator. We present a compilation of the CO2, CO, CH4 and N2O balances of Europe following a dual constraint approach in which (1) a land-based balance derived mainly from ecosystem carbon inventories and (2) a land-based balance derived from flux measurements are compared to (3) the atmospheric data-based balance derived from inversions constrained by measurements of atmospheric GHG (greenhouse gas) concentrations. Good agreement between the GHG balances based on fluxes (1294 +/- 545 Tg C in CO2-eq yr(-1)), inventories (1299 +/- 200 Tg C in CO2-eq yr(-1)) and inversions (1210 +/- 405 Tg C in CO2-eq yr(-1)) increases our confidence that the processes underlying the European GHG budget are well understood and reasonably sampled. However, the uncertainty remains large and largely lacks formal estimates. Given that European net land to atmosphere exchanges are determined by a few dominant fluxes, the uncertainty of these key components needs to be formally estimated before efforts could be made to reduce the overall uncertainty. The net land-to-atmosphere flux is a net source for CO2, CO, CH4 and N2O, because the anthropogenic emissions by far exceed the biogenic sink strength. The dual-constraint approach confirmed that the European biogenic sink removes as much as 205 +/- 72 Tg C yr(-1) from fossil fuel burning from the atmosphere. However, This C is being sequestered in both terrestrial and inland aquatic ecosystems. If the C-cost for ecosystem management is taken into account, the net uptake of ecosystems is estimated to decrease by 45% but still indicates substantial C-sequestration. However, when the balance is extended from CO2 towards the main GHGs, C-uptake by terrestrial and aquatic ecosystems is offset by emissions of non-CO2 GHGs. As such, the European ecosystems are unlikely to contribute to mitigating the effects of climate change.

  • 13.
    Pinho, L.
    et al.
    University of Federal Rio de Janeiro, Brazil; IMEDEA CSIC UIB, Spain; University of Estado Rio De Janeiro, Brazil.
    Duarte, C. M.
    IMEDEA CSIC UIB, Spain; KAUST, Saudi Arabia.
    Marotta, H.
    University of Federal Fluminense, Brazil; University of Federal Fluminense, Brazil.
    Enrich Prast, Alex
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. University of Federal Rio de Janeiro, Brazil.
    Temperature dependence of the relationship between pCO(2) and dissolved organic carbon in lakes2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 3, p. 865-871Article in journal (Refereed)
    Abstract [en]

    The relationship between the partial pressure of carbon dioxide (pCO(2)) and dissolved organic carbon (DOC) concentration in Brazilian lakes, encompassing 225 samples across a wide latitudinal range in the tropics, was tested. Unlike the positive relationship reported for lake waters, which was largely based on temperate lakes, we found no significant relationship for low-latitude lakes (< 33 degrees), despite very broad ranges in both pCO(2) and DOC levels. These results suggest substantial differences in the carbon cycling of low-latitude lakes, which must be considered when upscaling limnetic carbon cycling to global scales.

  • 14.
    Podgrajsek, E.
    et al.
    Uppsala University, Sweden .
    Sahlee, E.
    Uppsala University, Sweden .
    Bastviken, David
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Holst, J.
    Lund University, Sweden .
    Lindroth, A.
    Lund University, Sweden .
    Tranvik, L.
    Uppsala University, Sweden .
    Rutgersson, A.
    Uppsala University, Sweden .
    Comparison of floating chamber and eddy covariance measurements of lake greenhouse gas fluxes2014In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 11, no 15, p. 4225-4233Article in journal (Refereed)
    Abstract [en]

    Fluxes of carbon dioxide (CO2) and methane (CH4) from lakes may have a large impact on the magnitude of the terrestrial carbon sink. Traditionally lake fluxes have been measured using the floating chamber (FC) technique; however, several recent studies use the eddy covariance (EC) method. We present simultaneous flux measurements using both methods at lake Tamnaren in Sweden during field campaigns in 2011 and 2012. Only very few similar studies exist. For CO2 flux, the two methods agree relatively well during some periods, but deviate substantially at other times. The large discrepancies might be caused by heterogeneity of partial pressure of CO2 (pCO(2w)) in the EC flux footprint. The methods agree better for CH4 fluxes. It is, however, clear that short-term discontinuous FC measurements are likely to miss important high flux events.

  • 15.
    Sanders, Luciana M.
    et al.
    Southern Cross Univ, Australia.
    Taffs, Kathryn
    Southern Cross Univ, Australia.
    Stokes, Debra
    Southern Cross Univ, Australia.
    Sanders, Christian J.
    Southern Cross Univ, Australia.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Amora, Leonardo Nogueira
    Univ Fed Fluminense, Brazil.
    Marotta, Humberto
    Univ Fed Fluminense, Brazil.
    Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarem, Brazil2018In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, no 2, p. 447-455Article in journal (Refereed)
    Abstract [en]

    Forests along the Amazon Basin produce significant quantities of organic material, a portion of which is deposited in floodplain lakes. Deforestation in the watershed may then have potentially important effects on the carbon fluxes. In this study, a sediment core was extracted from an Amazon floodplain lake to examine the relationship between carbon burial and changing land cover and land use. Historical records from the 1930s and satellite data from the 1970s were used to calculate deforestation rates between 1930 to 1970 and 1970 to 2010 in four zones with different distances from the margins of the lake and its tributaries (100, 500, 1000 and 6000m buffers). A sediment accumulation rate of similar to 4 mmyr(-1) for the previous similar to 120 years was determined from the Pu240+239 signatures and the excess Pb-210 method. The carbon burial rates ranged between 85 and 298 gCm(-2) yr(-1), with pulses of high carbon burial in the 1950s, originating from the forest vegetation as indicated by delta C-13 and delta N-15 signatures. Our results revealed a potentially important spatial dependence of the organic carbon (OC) burial in Amazon lacustrine sediments in relation to deforestation rates in the catchment. These deforestation rates were more intense in the riparian vegetation (100m buffer) during the period 1930 to 1970 and the larger open water areas (500, 1000 and 6000m buffer) during 1970 to 2010. The continued removal of vegetation from the interior of the forest was not related to the peak of OC burial in the lake, but only the riparian deforestation which peaked during the 1950s. Therefore, this supports the conservation priority of riparian forests as an important management practice for Amazon flooded areas. Our findings suggest the importance of abrupt and temporary events in which some of the biomass released by deforestation, especially restricted to areas along open water edges, might reach the depositional environments in the floodplain of the Amazon Basin.

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