| 1. |
- Barros, Nathan, et al.
(author)
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Carbon emission from hydroelectric reservoirs linked to reservoir age and latitude
- 2011
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In: Nature Geoscience. - : Nature Publishing Group. - 1752-0894 .- 1752-0908. ; 4:9, s. 593-596
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Journal article (peer-reviewed)abstract
- Hydroelectric reservoirs cover an area of 3.4 x 10(5) km(2) and comprise about 20% of all reservoirs. In addition, they contain large stores of formerly terrestrial organic carbon. Significant amounts of greenhouse gases are emitted(2), especially in the early years following reservoir creation, but the global extent of these emissions is poorly known. Previous estimates of emissions from all types of reservoir indicate that these human-made systems emit 321 Tg of carbon per year (ref. 4). Here we assess the emissions of carbon dioxide and methane from hydroelectric reservoirs, on the basis of data from 85 globally distributed hydroelectric reservoirs that account for 20% of the global area of these systems. We relate the emissions to reservoir age, location biome, morphometric features and chemical status. We estimate that hydroelectric reservoirs emit about 48 Tg C as CO(2) and 3 Tg C as CH(4), corresponding to 4% of global carbon emissions from inland waters. Our estimates are smaller than previous estimates on the basis of more limited data. Carbon emissions are correlated to reservoir age and latitude, with the highest emission rates from the tropical Amazon region. We conclude that future emissions will be highly dependent on the geographic location of new hydroelectric reservoirs.
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| 2. |
- Prairie, Yves T., et al.
(author)
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Greenhouse Gas Emissions from Freshwater Reservoirs : What Does the Atmosphere See?
- 2018
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In: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 21:5, s. 1058-1071
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Journal article (peer-reviewed)abstract
- Freshwater reservoirs are a known source of greenhouse gas (GHG) to the atmosphere, but their quantitative significance is still only loosely constrained. Although part of this uncertainty can be attributed to the difficulties in measuring highly variable fluxes, it is also the result of a lack of a clear accounting methodology, particularly about what constitutes new emissions and potential new sinks. In this paper, we review the main processes involved in the generation of GHG in reservoir systems and propose a simple approach to quantify the reservoir GHG footprint in terms of the net changes in GHG fluxes to the atmosphere induced by damming, that is, ´€˜what the atmosphere sees’. The approach takes into account the pre-impoundment GHG balance of the landscape, the temporal evolution of reservoir GHG emission profile as well as the natural emissions that are displaced to or away from the reservoir site resulting from hydrological and other changes. It also clarifies the portion of the reservoir carbon burial that can potentially be considered an offset to GHG emissions.
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| 3. |
- Sobek, Sebastian, et al.
(author)
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Patterns and regulation of dissolved organic carbon : An analysis of 7,500 widely distributed lakes
- 2007
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In: Limnology and Oceanography. - 0024-3590 .- 1939-5590. ; 52:3, s. 1208-1219
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Journal article (peer-reviewed)abstract
- Dissolved organic carbon (DOC) is a key parameter in lakes that can affect numerous features, including microbial metabolism, light climate, acidity, and primary production. In an attempt to understand the factors that regulate DOC in lakes, we assembled a large database (7,514 lakes from 6 continents) of DOC concentrations and other parameters that characterize the conditions in the lakes, the catchment, the soil, and the climate. DOC concentrations were in the range 0.1-332 mg L-1, and the median was 5.71 mg L-1. A partial least squares regression explained 48% of the variability in lake DOC and showed that altitude, mean annual runoff, and precipitation were negatively correlated with lake DOC, while conductivity, soil carbon density, and soil C:N ratio were positively related with lake DOC. A multiple linear regression using altitude, mean annual runoff, and soil carbon density as predictors explained 40% of the variability in lake DOC. While lake area and drainage ratio (catchment:lake area) were not correlated to lake DOC in the global data set, these two factors explained significant variation of the residuals of the multiple linear regression model in several regional subsets of data. These results suggest a hierarchical regulation of DOC in lakes, where climatic and topographic characteristics set the possible range of DOC concentrations of a certain region, and catchment and lake properties then regulate the DOC concentration in each individual lake.
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| 4. |
- Stubbins, Aron, et al.
(author)
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Biogeochemical interpretations of colored dissolved organic matter optical signatures (invited)
- 2014
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Conference paper (other academic/artistic)abstract
- The optical properties of colored dissolved organic matter (CDOM) in surface waters are visible from space and observable throughout the water column in real time using in situ sensors. Due to their ease of measurement, CDOM optical properties are used as proxies for the quantity, quality and processing of dissolved organic matter (DOM) in natural waters. This talk will focus upon the use of these optical signatures to provide insight into the cycling of DOM. Examples will include the use of color to estimate quantitative fluxes and the molecular composition of organics in natural waters.
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| 5. |
- Stubbins, Aron, et al.
(author)
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What’s in an EEM? : molecular signatures associated with dissolved organic fluorescence in boreal Canada
- 2014
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In: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 48:18, s. 10598-10606
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Journal article (peer-reviewed)abstract
- Dissolved organic matter (DOM) is a master variable in aquatic systems. Modern fluorescence techniques couple measurements of excitation emission matrix (EEM) spectra and parallel factor analysis (PARAFAC) to determine fluorescent DOM (FDOM) components and DOM quality. However, the molecular signatures associated with PARAFAC components are poorly defined. In the current study we characterized river water samples from boreal Québec, Canada, using EEM/PARAFAC analysis and ultrahigh resolution mass spectrometry (FTICR-MS). Spearman’s correlation of FTICR-MS peak and PARAFAC component relative intensities determined the molecular families associated with 6 PARAFAC components. Molecular families associated with PARAFAC components numbered from 39 to 572 FTICR-MS derived elemental formulas. Detailed molecular properties for each of the classical humic- and protein-like FDOM components are presented. FTICR-MS formulas assigned to PARAFAC components represented 39% of the total number of formulas identified and 59% of total FTICR-MS peak intensities, and included significant numbers compounds that are highly unlikely to fluoresce. Thus, fluorescence measurements offer insight into the biogeochemical cycling of a large proportion of the DOM pool, including a broad suite of unseen molecules that apparently follow the same gradients as FDOM in the environment.
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| 6. |
- Tranvik, Lars, et al.
(author)
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The study of carbon in inland waters-from isolated ecosystems to players in the global carbon cycle
- 2018
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In: Limnology and Oceanography Letters. - : Wiley. - 2378-2242. ; 3:3, s. 41-48
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Journal article (peer-reviewed)abstract
- This essay describes the evolution of our understanding of the carbon cycle of inland waters. Research has evolved from studies of individual lakes with limited attention to the surrounding landscapes, to a focus on how lakes are affected by external factors such as import of organic matter from the watershed, thereafter increasingly addressing how inland waters impact the carbon cycle beyond their own limits, for example by emission of gases to the atmosphere. Major steps are described toward the now widely applied concept of the aquatic “active pipe,” and the development of global quantification of inland water carbon cycling. Despite the great progress in understanding of the carbon cycle during the last decades, we argue that there is still a need for better integration of inland waters with other habitats in studies of carbon biogeochemistry.
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| 7. |
- Weyhenmeyer, Gesa A., et al.
(author)
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Browning of Boreal Freshwaters Coupled to Carbon-Iron Interactions along the Aquatic Continuum
- 2014
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:2, s. e88104-
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Journal article (peer-reviewed)abstract
- The color of freshwaters, often measured as absorbance, influences a number of ecosystem services including biodiversity, fish production, and drinking water quality. Many countries have recently reported on increasing trends of water color in freshwaters, for which drivers are still not fully understood. We show here with more than 58000 water samples from the boreal and hemiboreal region of Sweden and Canada that absorbance of filtered water (a(420)) co-varied with dissolved organic carbon (DOC) concentrations (R-2 = 0.85, P<0.0001), but that a(420) relative to DOC is increased by the presence of iron (Fe). We found that concentrations of Fe significantly declined with increasing water retention in the landscape, resulting in significantly lower Fe concentrations in lakes compared to running waters. The Fe loss along the aquatic continuum corresponded to a proportional loss in a(420), suggesting a tight biogeochemical coupling between colored dissolved organic matter and Fe. Since water is being flushed at increasing rates due to enhanced runoff in the studied regions, diminished loss of Fe along the aquatic continuum may be one reason for observed trends in a(420), and in particular in a(420)/DOC increases. If trends of increased Fe concentrations in freshwaters continue, water color will further increase with various effects on ecosystem services and biogeochemical cycles.
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