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- Semiletov, Igor, et al.
(författare)
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Acidification of East Siberian Arctic Shelf waters through addition of freshwater and terrestrial carbon
- 2016
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 9, s. 361-365
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification affects marine ecosystems and carbon cycling, and is considered a direct effect of anthropogenic carbon dioxide uptake from the atmosphere. Accumulation of atmospheric CO2 in ocean surface waters is predicted to make the ocean twice as acidic by the end of this century. The Arctic Ocean is particularly sensitive to ocean acidification because more CO2 can dissolve in cold water. Here we present observations of the chemical and physical characteristics of East Siberian Arctic Shelf waters from 1999, 2000–2005, 2008 and 2011, and find extreme aragonite undersaturation that reflects acidity levels in excess of those projected in this region for 2100. Dissolved inorganic carbon isotopic data and Markov chain Monte Carlo simulations of water sources using salinity and delO-18 data suggest that the persistent acidification is driven by the degradation of terrestrial organic matter and discharge of Arctic river water with elevated CO2 concentrations, rather than by uptake of atmospheric CO2. We suggest that East Siberian Arctic Shelf waters may become more acidic if thawing permafrost leads to enhanced terrestrial organic carbon inputs and if freshwater additions continue to increase, which may affect their efficiency as a source of CO2.
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| 2. |
- Shakhova, Natalia, et al.
(författare)
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Ebullition and storm-induced methane release from the East Siberian Arctic Shelf
- 2014
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Ingår i: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 7:1, s. 64-70
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Tidskriftsartikel (refereegranskat)abstract
- Vast quantities of carbon are stored in shallow Arctic reservoirs, such as submarine and terrestrial permafrost. Submarine permafrost on the East Siberian Arctic Shelf started warming in the early Holocene, several thousand years ago. However, the present state of the permafrost in this region is uncertain. Here, we present data on the temperature of submarine permafrost on the East Siberian Arctic Shelf using measurements collected from a sediment core, together with sonar-derived observations of bubble flux and measurements of seawater methane levels taken from the same region. The temperature of the sediment core ranged from -1.8 to 0 degrees C. Although the surface layer exhibited the lowest temperatures, it was entirely unfrozen, owing to significant concentrations of salt. On the basis of the sonar data, we estimate that bubbles escaping the partially thawed permafrost inject 100-630 mg methane m(-2) d(-1) into the overlying water column. We further show that water-column methane levels had dropped significantly following the passage of two storms. We suggest that significant quantities of methane are escaping the East Siberian Shelf as a result of the degradation of submarine permafrost over thousands of years. We suggest that bubbles and storms facilitate the flux of this methane to the overlying ocean and atmosphere, respectively.
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