| 1. |
- Kirpotin, Sergey N., et al.
(författare)
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Russian–EU collaboration via the mega-transect approach for large-scale projects : cases of RF Federal target Programme and SIWA JPI Climate EU Programme
- 2018
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Ingår i: International Journal of Environmental Studies. - : Routledge. - 0020-7233 .- 1029-0400. ; 75:3, s. 385-394
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Tidskriftsartikel (refereegranskat)abstract
- The mega-transect approach is a unique infrastructure which was developed in Tomsk State University for environmental monitoring and landscape-ecological research. The approach can be followed in all seasons, for field sampling, ground-based research on the field stations in combination with remote sensing and ecosystem manipulations. The mega-transect was established as a framework for the concept of Western Siberia as a natural mega-facility, a kind of natural equivalent to CERN’s Large Hadron Collider, to attract leading international research groups. The paper describes cases of Russian Federation Federal target Programme and Siberian Inland Waters Joint Programming Initiative Climate EU Programme as examples of the large-scale international projects which are now resulting.
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| 2. |
- Krickov, Ivan V., et al.
(författare)
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Riverine particulate C and N generated at the permafrost thaw front : case study of western Siberian rivers across a 1700km latitudinal transect
- 2018
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Ingår i: Biogeosciences. - : Nicolaus Copernicus University Press. - 1726-4170 .- 1726-4189. ; 15:22, s. 6867-6884
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Tidskriftsartikel (refereegranskat)abstract
- In contrast to numerous studies on the dynamics of dissolved (< 0.45 mu m) elements in permafrost-affected highlatitude rivers, very little is known of the behavior of river suspended (> 0.45 mu m) matter (RSM) in these regions. In order to test the effect of climate, permafrost and physiogeographical landscape parameters (bogs, forest and lake coverage of the watershed) on RSM and particulate C, N and P concentrations in river water, we sampled 33 small and medium-sized rivers (10-100 000 km(2) watershed) along a 1700 km N-S transect including both permafrost-affected and permafrost-free zones of the Western Siberian Lowland (WSL). The concentrations of C and N in RSM decreased with the increase in river watershed size, illustrating (i) the importance of organic debris in small rivers which drain peatlands and (ii) the role of mineral matter from bank abrasion in larger rivers. The presence of lakes in the watershed increased C and N but decreased P concentrations in the RSM. The C V N ratio in the RSM reflected the source from the deep soil horizon rather than surface soil horizon, similar to that of other Arctic rivers. This suggests the export of peat and mineral particles through suprapermafrost flow occurring at the base of the active layer. There was a maximum of both particulate C and N concentrations and export fluxes at the beginning of permafrost appearance, in the sporadic and discontinuous zone (62-64 degrees N). This presumably reflected the organic matter mobilization from newly thawed organic horizons in soils at the active latitudinal thawing front. The results suggest that a northward shift of permafrost boundaries and an increase in active layer thickness may increase particulate C and N export by WSL rivers to the Arctic Ocean by a factor of 2, while P export may remain unchanged. In contrast, within a long-term climate warming scenario, the disappearance of permafrost in the north, the drainage of lakes and transformation of bogs to forest may decrease C and N concentrations in RSM by 2 to 3 times.
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| 3. |
- Pokrovsky, Oleg S., et al.
(författare)
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Dissolved organic matter controls seasonal and spatial selenium concentration variability in thaw lakes across a permafrost gradient
- 2018
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 52:18, s. 10254-10262
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the sources and processing of selenium, an important toxicant and essential micronutrient, within boreal and sub-arctic environments. Upon climate warming and permafrost thaw, the behavior of Se in northern peatlands becomes an issue of major concern, because a sizable amount of Se can be emitted to the atmosphere from thawing soils and inland water surfaces and exported to downstream waters, thus impacting the Arctic biota. Working toward providing a first-order assessment of spatial and temporal variation of Se concentration in thermokarst waters of the largest frozen peatland in the world, we sampled thaw lakes and rivers across a 750-km latitudinal profile. This profile covered sporadic, discontinuous, and continuous permafrost regions of western Siberia Lowland (WSL), where we measured dissolved (<0.45 mu m) Se concentration during spring (June), summer (August), and autumn (September). We found maximum Se concentration in the discontinuous permafrost zone. Considering all sampled lakes, Se exhibited linear relationship (R-2 = 0.7 to 0.9, p < 0.05, n approximate to 70) with dissolved organic carbon (DOC) concentration during summer and autumn. Across the permafrost gradient, the lakes in discontinuous permafrost regions demonstrated stronger relationship with DOC and UV-absorbance compared to lakes in sporadic/isolated and continuous permafrost zones. Both seasonal and spatial features of Se distribution in thermokarst lakes and ponds suggest that Se is mainly released during thawing of frozen peat. Mobilization and immobilization of Se within peat-lake-river watersheds likely occurs as organic and organo-Fe, Al colloids, probably associated with reduced and elemental Se forms. The increase of active layer thickness may enhance leaching of Se in the form of organic complexes with aromatic carbon from the deep horizons of the peat profile. Further, the northward shift of permafrost boundaries in WSL may sizably increase Se concentration in lakes of continuous permafrost zone.
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| 4. |
- Pokrovsky, Oleg S., et al.
(författare)
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Freeze-thaw cycles of Arctic thaw ponds remove colloidal metals and generate low-molecular-weight organic matter
- 2018
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 137:3, s. 321-336
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Tidskriftsartikel (refereegranskat)abstract
- High-latitude boreal and arctic surface/inland waters contain sizeable reservoirs of dissolved organic matter (DOM) and trace elements (TE), which are subject to seasonal freezing. Specifically, shallow ponds and lakes in the permafrost zone often freeze solid, which can lead to transformations in the colloidal and dissolved fractions of DOM and TE. Here, we present results from experimental freeze-thaw cycles using iron (Fe)- and DOM-rich water from thaw ponds situated in Stordalen and Storflaket palsa mires in northern Sweden. After ten cycles of freezing, 85% of Fe and 25% of dissolved organic carbon (DOC) were removed from solution in circumneutral fen water (pH 6.9) but a much smaller removal of Fe and DOC (< 7%) was found in acidic bog water (pH 3.6). This removal pattern was consistent with initial supersaturation of fen water with respect to Fe hydroxide and a lack of supersaturation with any secondary mineral phase in the bog water. There was a nearly two- to threefold increase in the low-molecular-weight (LMW) fraction of organic carbon (OC) and several TEs caused by the repeated freeze-thaw cycles. Future increases in the freeze-thaw frequency of surface waters with climate warming may remove up to 25% of DOC in circumneutral organic-rich waters. Furthermore, an increase of LMW OC may result in enhanced carbon dioxide losses from aquatic ecosystems since this fraction is potentially more susceptible to biodegradation.
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