| 1. |
- Vorobyev, Sergey N., et al.
(författare)
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Biogeochemistry of dissolved carbon, major, and trace elements during spring flood periods on the Ob River
- 2019
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Ingår i: Hydrological Processes. - : John Wiley & Sons. - 0885-6087 .- 1099-1085. ; 33:11, s. 1579-1594
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Tidskriftsartikel (refereegranskat)abstract
- Detailed knowledge of the flood period of Arctic rivers remains one of the few factors impeding rigorous prediction of the effect of climate change on carbon and related element fluxes from the land to the Arctic Ocean. In order to test the temporal and spatial variability of element concentration in the Ob River (western Siberia) water during flood period and to quantify the contribution of spring flood period to the annual element export, we sampled the main channel year round in 2014-2017 for dissolved C, major, and trace element concentrations. We revealed high stability (approximately <= 10% relative variation) of dissolved C, major, and trace element concentrations in the Ob River during spring flood period over a 1-km section of the river channel and over 3 days continuous monitoring (3-hr frequency). We identified two groups of elements with contrasting relationship to discharge: (a) DIC and soluble elements (Cl, SO4, Li, B, Na, Mg, Ca, P, V, Cr, Mn, As, Rb, Sr, Mo, Ba, W, and U) negatively correlated (p < 0.05) with discharge and exhibited minimal concentrations during spring flood and autumn high flow and (b) DOC and particle-reactive elements (Al, Fe, Ti, Y, Zr, Nb, Cs, REEs, Hf, Tl, Pb, and Th), some nutrients (K), and metalloids (Ge, Sb, and Te), positively correlated (p < 0.05) with discharge and showed the highest concentrations during spring flood. We attribute the decreased concentration of soluble elements with discharge to dilution by groundwater feeding and increased concentration of DOC and particle-reactive metals with discharge to leaching from surface soil, plant litter, and suspended particles. Overall, the present study provides first-order assessment of fluxes of major and trace elements in the middle course of the Ob River, reveals their high temporal and spatial stability, and characterizes the mechanism of river water chemical composition acquisition.
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| 2. |
- Vorobyev, Sergey N., et al.
(författare)
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Permafrost Boundary Shift in Western Siberia May Not Modify Dissolved Nutrient Concentrations in Rivers
- 2017
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 9:12
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Tidskriftsartikel (refereegranskat)abstract
- Identifying the landscape and climate factors that control nutrient export by rivers in high latitude regions is one of the main challenges for understanding the Arctic Ocean response to ongoing climate change. This is especially true for Western Siberian rivers, which are responsible for a significant part of freshwater and solutes delivery to the Arctic Ocean and are draining vast permafrost-affected areas most vulnerable to thaw. Forty-nine small- and medium-sized rivers (10-100,000 km(2)) were sampled along a 1700 km long N-S transect including both permafrost-affected and permafrost-free zones of the Western Siberian Lowland (WSL) in June and August 2015. The N, P, dissolved organic and inorganic carbon (DOC and DIC, respectively), particular organic carbon (POC), Si, Ca, K, Fe, and Mn were analyzed to assess the role of environmental parameters, such as temperature, runoff, latitude, permafrost, bogs, lake, and forest coverage on nutrient concentration. The size of the watershed had no influence on nutrient concentrations in the rivers. Bogs and lakes retained nutrients whereas forests supplied P, Si, K, Ca, DIC, and Mn to rivers. The river water temperature was negatively correlated with Si and positively correlated with Fe in permafrost-free rivers. In permafrost-bearing rivers, the decrease in T northward was coupled with significant increases in PO4, P-tot, NH4, pH, DIC, Si, Ca, and Mn. North of the permafrost boundary (61 degrees N), there was no difference in nutrient concentrations among permafrost zones (isolated, sporadic, discontinuous, and continuous). The climate warming in Western Siberia may lead to a permafrost boundary shift northward. Using a substituting space for time scenario, this may decrease or maintain the current levels of N, P, Si, K, Ca, DIC, and DOC concentrations in rivers of continuous permafrost zones compared to the present state. As a result, the export flux of nutrients by the small- and medium-sized rivers of the Western Siberian subarctic to the Arctic Ocean coastal zone may remain constant, or even decrease.
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| 3. |
- Lim, Artem G., et al.
(författare)
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Carbon emission and export from the Ket River, western Siberia
- 2022
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Ingår i: Biogeosciences. - : Copernicus Publications. - 1726-4170 .- 1726-4189. ; 19:24, s. 5859-5877
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Tidskriftsartikel (refereegranskat)abstract
- Despite recent progress in the understanding of the carbon (C) cycle of Siberian permafrost-affected rivers, spatial and seasonal dynamics of C export and emission from medium-sized rivers (50 000-300 000 km2 watershed area) remain poorly known. Here we studied one of the largest tributaries of the Ob River, the Ket River (watershed Combining double low line 94 000 km2), which drains through pristine taiga forest of the boreal zone in the West Siberian Lowland (WSL). We combined continuous and discrete measurements of carbon dioxide (CO2) concentration using submersible CO2 sensor and floating chamber flux (FCO2), with methane (CH4), dissolved organic and inorganic C (DOC and DIC, respectively), particulate organic C and total bacterial concentrations over an 800 km transect of the Ket River main stem and its 26 tributaries during spring flood (May 2019) and 12 tributaries during summer baseflow (end of August-beginning of September 2019). The partial pressure of CO2 (pCO2) was lower and less variable in the main stem (2000 to 2500 μatm) compared to that in the tributaries (2000 to 5000 μatm). In the tributaries, the pCO2 was 40 % higher during baseflow compared to spring flood, whereas in the main stem, it did not vary significantly across the seasons. The methane concentration in the main stem and tributaries was a factor of 300 to 1900 (flood period) and 100 to 150 times lower than that of CO2 and ranged from 0.05 to 2.0 μmol L-1. The FCO2 ranged from 0.4 to 2.4 g C m-2 d-1 in the main channel and from 0.5 to 5.0 g C m-2 d-1 in the tributaries, being highest during August in the tributaries and weakly dependent on the season in the main channel. During summer baseflow, the DOC aromaticity, bacterial number, and needleleaf forest coverage of the watershed positively affected CO2 concentrations and fluxes. We hypothesize that relatively low spatial and seasonal variability in FCO2 of the Ket River is due to a flat homogeneous landscape (bogs and taiga forest) that results in long water residence times and stable input of allochthonous dissolved organic matter (DOM), which dominate the FCO2. The open water period (May to October) C emission from the fluvial network (main stem and tributaries) of the Ket River was estimated to 127 ± 11 Gg C yr-1, which is lower than the downstream dissolved and particulate C export during the same period. The estimated fluvial C emissions are highly conservative and contain uncertainties linked to ignoring hotspots and hot moments of emissions, notably in the floodplain zone. This stresses the need to improve the temporal resolution of FCO2 and water coverage across seasons and emphasizes the important role of WSL rivers in the release of CO2 into the atmosphere.
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| 4. |
- Karlsson, Jan, 1974-, et al.
(författare)
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Carbon emission from Western Siberian inland waters
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- High-latitude regions play a key role in the carbon (C) cycle and climate system. An important question is the degree of mobilization and atmospheric release of vast soil C stocks, partly stored in permafrost, with amplified warming of these regions. A fraction of this C is exported to inland waters and emitted to the atmosphere, yet these losses are poorly constrained and seldom accounted for in assessments of high-latitude C balances. This is particularly relevant for Western Siberia, with its extensive peatland C stocks, which can be strongly sensitive to the ongoing changes in climate. Here we quantify C emission from inland waters, including the Ob’ River (Arctic’s largest watershed), across all permafrost zones of Western Siberia. We show that the inland water C emission is high (0.08–0.10 Pg C yr−1) and of major significance in the regional C cycle, largely exceeding (7–9 times) C export to the Arctic Ocean and reaching nearly half (35–50%) of the region’s land C uptake. This important role of C emission from inland waters highlights the need for coupled land–water studies to understand the contemporary C cycle and its response to warming.
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| 5. |
- Krickov, Ivan V., et al.
(författare)
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Sizable carbon emission from the floodplain of Ob River
- 2021
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Ingår i: Ecological Indicators. - : Elsevier. - 1470-160X .- 1872-7034. ; 131
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Tidskriftsartikel (refereegranskat)abstract
- The Ob River floodplain is the second largest floodplain in the world. Despite its vast area, estimates of carbon (C) emissions from the Ob River floodplain are largely absent. Here we present seasonal C emission and water area extent from the main channel and the floodplain along a ~4 km reach in the boreal zone of the Ob River. We found strong seasonality in water area extent of the Ob main channel (~1.8 km2) and floodplain (~3 km2) with water covering 34% of land during flood and subsequently declining to ~16% and ~14% during summer and autumn baseflow, respectively. The C emissions also varied seasonally over the open water period, ranging from −0.1 to 0.6 g C m−2 d−1 for the Ob main channel and from 0 to 9 g C m−2 d−1 for the floodplain. The dissolved organic carbon positively affected CO2 concentrations and fluxes in the floodplain during all seasons, whereas pH and oxygen concentration negatively impacted CO2 concentrations and fluxes. Some nutrients (ammonia and phosphate) positively correlated with CO2 and CH4 concentrations in summer. The total C emission from the study reach (1.8 km2 main channel, 3 km2 floodplain) during moderate flooding was 236 ± 51 tons C yr−1 (>99% CO2, <1% CH4) with the floodplain accounting for ~65%. The contribution of the floodplain to the net river C evasion may be even greater during years of high flooding and in northern regions of the Ob River basin, where floodplain soils are more C-rich and are underlain by permafrost, and in years with more extensive flooding.
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| 6. |
- Vorobyev, Sergey N., et al.
(författare)
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Floodplain carbon dioxide emissions strongly exceed those of the main river stem : a case study of the Ob river, western Siberia
- 2024
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Ingår i: Journal of Hydrology. - : Elsevier. - 0022-1694 .- 1879-2707. ; 638
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Tidskriftsartikel (refereegranskat)abstract
- The importance of floodplains in carbon (C) evasion from the lotic systems is especially important in continental plains of low runoff such as the organic-rich Western Siberian Lowland (WSL). To quantify the relative importance of the floodplain compared to main stem CO2 emissions, we monitored a large region of the Ob River's middle course (permafrost-free zone) over 3 months from spring to summer. We calculated seasonal water coverage using remote sensing, GIS and hydrologically-based approaches and measured CO2 emissions using floating chambers. There was a strongly pronounced seasonality in the water area's extent of the floodplain with water covering > 40 % of land during the ∼ 30 days of the most intensive spring flood (May – June) and subsequently declining to ≤ 10 % during summer (July-August). Maximal CO2 emissions were recorded in most shallow water bodies of the floodplain, notably in temporary flooded fens and birch forests. The CO2 emissions during the study period ranged from 0.2 ± 0.2 to 0.9 ± 0.2 g Cm−2 d−1 for the floodplain and 0.03 ± 0.34 g C m−2 d−1 for the Ob's main channel.CO2 emissions from the floodplain were ∼ 163 ± 20 t C per km for the river's main stem during the 95 day study period. The partial contributions of temporary flooded zones, main stem, and permanent lakes / secondary channels to total emissions (1820 km² area) were 70, 16, and 14 %, respectively. Over spring and summer seasons, contributions from flooded zones ranged from 43 to 99 % of total CO2 emissions from water surfaces of the Ob River's middle course. Extrapolation of obtained results to the entire territory of the Ob River floodplain indicates that not accounting for the floodplain emissions may sizably—up to an order of magnitude—underestimate the CO2 emissions from riverine systems in Western Siberia during open water period. Future work on the Ob River floodplain in the permafrost-bearing zone should be prioritized and would allow adequate upscaling of C emission from this environmentally important territory.
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| 7. |
- Vorobyev, Sergey N., et al.
(författare)
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Fluvial carbon dioxide emission from the Lena River basin during the spring flood
- 2021
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Ingår i: Biogeosciences. - : Nicolaus Copernicus University Press. - 1726-4170 .- 1726-4189. ; 18:17, s. 4919-4936
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Tidskriftsartikel (refereegranskat)abstract
- Greenhouse gas (GHG) emission from inland waters of permafrost-affected regions is one of the key factors of circumpolar aquatic ecosystem response to climate warming and permafrost thaw. Riverine systems of central and eastern Siberia contribute a significant part of the water and carbon (C) export to the Arctic Ocean, yet their C exchange with the atmosphere remains poorly known due to lack of in situ GHG concentration and emission estimates. Here we present the results of continuous in situ pCO2 measurements over a 2600 km transect of the Lena River main stem and lower reaches of 20 major tributaries (together representing a watershed area of 1 661 000 km2, 66 % of the Lena's basin), conducted at the peak of the spring flood. The pCO2 in the Lena (range 400-1400 μatm) and tributaries (range 400-1600 μatm) remained generally stable (within ca. 20 %) over the night-day period and across the river channels. The pCO2 in tributaries increased northward with mean annual temperature decrease and permafrost increase; this change was positively correlated with C stock in soil, the proportion of deciduous needleleaf forest, and the riparian vegetation. Based on gas transfer coefficients obtained from rivers of the Siberian permafrost zone (kCombining double low line4.46 md-1), we calculated CO2 emission for the main stem and tributaries. Typical fluxes ranged from 1 to 2 gCm-2d-1 (>99 % CO2, <1 % CH4), which is comparable with CO2 emission measured in the Kolyma, Yukon, and Mackenzie rivers and permafrost-affected rivers in western Siberia. The areal C emissions from lotic waters of the Lena watershed were quantified by taking into account the total area of permanent and seasonal water of the Lena basin (28 000 km2 ). Assuming 6 months of the year to be an open water period with no emission under ice, the annual C emission from the whole Lena basin is estimated as 8.3±2.5 TgCyr-1, which is comparable to the DOC and dissolved inorganic carbon (DIC) lateral export to the Arctic Ocean.
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