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- Algesten, Grete, et al.
(author)
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Role of lakes for organic carbon cycling in the boreal zone
- 2004
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In: Global Change Biology. - Oxford : Blackwell Scientific. - 1354-1013 .- 1365-2486. ; 10:1, s. 141-147
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Journal article (peer-reviewed)abstract
- We calculated the carbon loss (mineralization plus sedimentation) and net CO2 escape to the atmosphere for 79 536 lakes and total running water in 21 major Scandinavian catchments (size range 437–48 263 km2). Between 30% and 80% of the total organic carbon that entered the freshwater ecosystems was lost in lakes. Mineralization in lakes and subsequent CO2 emission to the atmosphere was by far the most important carbon loss process. The withdrawal capacity of lakes on the catchment scale was closely correlated to the mean residence time of surface water in the catchment, and to some extent to the annual mean temperature represented by latitude. This result implies that variation of the hydrology can be a more important determinant of CO2 emission from lakes than temperature fluctuations. Mineralization of terrestrially derived organic carbon in lakes is an important regulator of organic carbon export to the sea and may affect the net exchange of CO2 between the atmosphere and the boreal landscape.
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| 2. |
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| 3. |
- Algesten, Grete, 1974-, et al.
(author)
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Seasonal variation of CO2 saturation in the Gulf of Bothnia : Indications of marine net heterotrophy
- 2004
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In: Global Biogeochemical Cycles. - Washington, D.C : American Geophysical Union (AGU). - 0886-6236 .- 1944-9224. ; 18, s. 4021-4028
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Journal article (peer-reviewed)abstract
- Seasonal variation of pCO2 and primary and bacterioplankton production were measured in the Gulf of Bothnia during an annual cycle. Surface water was supersaturated with CO2 on an annual basis, indicating net heterotrophy and a source of CO2 to the atmosphere. However, the Gulf of Bothnia oscillated between being a sink and a source of CO2 over the studied period, largely decided by temporal variation in bacterial respiration (BR) and primary production (PP) in the water column above the pycnocline. The calculated annual respiration-production balance (BR-PP) was very similar to the estimated CO2 emission from the Gulf of Bothnia, which indicates that these processes were major determinants of the exchange of CO2 between water and atmosphere. The southern basin (the Bothnian Sea) had a lower net release of CO2 to the atmosphere than the northern Bothnian Bay (7.1 and 9.7 mmol C m−2 d−1, respectively), due to higher primary production, which to a larger extent balanced respiration in this basin.
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| 4. |
- Bergström, Ann-Kristin, et al.
(author)
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Emission of CO2 from hydroelectric reservoirs in northern Sweden
- 2004
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In: Archiv für Hydrobiologie. - : Schweizerbart. - 0003-9136. ; 159, s. 25-42
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Journal article (peer-reviewed)abstract
- Carbon dioxide in Swedish hydroelectric reservoirs and natural lakes was studied to assess whether the emission of CO2 from inland waters has increased due to construction of reservoirs, and to gauge how the CO2-emission from reservoirs relates to CO2-emission from combustion plants used for electricity production. We found that emission of CO2 from Swedish reservoirs was low and, at corresponding dissolved organic carbon concentration, similar to the CO2-emission from natural oligotrophic lakes. The total annual CO2-emission due to regulation for the seven rivers included in this study (which collectively represents 87% of the total hydroelectricity production in Sweden) was 50,000 tonnes of CO2. This emission represents 1.5 % of the yearly CO2-emission from Swedish electricity combustion plants. Thus, the CO2-emission from Swedish hydropower is much lower per unit of electricity produced than the emission from Swedish combustion plants. Emission of CO2 from Swedish reservoirs was lower than from most reservoirs in other boreal regions of the world. This difference is probably due to that a majority of the Swedish reservoirs are constructed by damming of natural lakes in alpine and upland boreal forest areas, which results in flooding of comparatively small areas with thin layers of soil organic carbon.
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| 5. |
- Sobek, Sebastian, et al.
(author)
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The catchment and climate regulation of pCO2 in boreal lakes
- 2003
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In: Global Change Biology. - : Wiley. - 1354-1013. ; 9:4, s. 630-641
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Journal article (peer-reviewed)abstract
- The regulation of surface water pCO2 was studied in a set of 33 unproductive boreal lakes of different humic content, situated along a latitudinal gradient (57°N to 64°N) in Sweden. The lakes were sampled four times during one year, and analyzed on a wide variety of water chemistry parameters. With only one exception, all lakes were supersaturated with CO2 with respect to the atmosphere at all sampling occasions. pCO2 was closely related to the DOC concentration in lakes, which in turn was mainly regulated by catchment characteristics. This pattern was similar along the latitudinal gradient and at different seasons of the year, indicating that it is valid for a variety of climatic conditions within the boreal forest zone. We suggest that landscape characteristics determine the accumulation and subsequent supply of allochthonous organic matter from boreal catchments to lakes, which in turn results in boreal lakes becoming net sources of atmospheric CO2.
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