Organic carbon, major and trace element release from and adsorption onto particulate suspended matter of the Ob River, western Siberia.

Particulate suspended matter (PSM) of rivers is a significant factor for carbon, nutrient, and trace metal transfer from land to ocean. Towards better understanding the role that PSM exerts on major and trace elements in riverine systems, here we report the results of an experimental study which utilizes a two-fold approach to assess interaction between PSM and riverine solutes. First, we measured element leaching (via desorption and dissolution in distilled water, simulating snow melt) from PSM of the largest Siberian river, the Ob River.

Fluvial carbon dioxide emissions peak at the permafrost thawing front in the Western Siberia Lowland.

In order to foresee the impact of permafrost thaw on CO emissions by high-latitude rivers, in-situ measurements across a permafrost and climate/vegetation gradient, coupled with assessment of possible physico-chemical and landscape controlling factors are necessary. Here we chose 34 catchments of variable stream order (1 to 9) and watershed size (1 to >10 km) located across a permafrost and biome gradient in the Western Siberian Lowland (WSL), from the permafrost-free southern taiga to the continuous permafrost zone of tundra. Across the south-north transect, maximal CO emissions (2.

Dissolved organic matter quality in thermokarst lake water and sediments across a permafrost gradient, Western Siberia.

Thermokarst (thaw) lakes of permafrost peatlands are among the most important sentinels of climate change and sizable contributors of greenhouse gas emissions (GHG) in high latitudes. These lakes are humic, often acidic and exhibit fast growing/drainage depending on the local environmental and permafrost thaw. In contrast to good knowledge of the thermokarst lake water hydrochemistry and GHG fluxes, the sediments pore waters remain virtually unknown, despite the fact that these are hot spots of biogeochemical processes including GHG generation.

Size matters: Aerobic methane oxidation in sediments of shallow thermokarst lakes.

Shallow thermokarst lakes are important sources of greenhouse gases (GHGs) such as methane (CH ) and carbon dioxide (CO ) resulting from continuous permafrost thawing due to global warming. Concentrations of GHGs dissolved in water typically increase with decreasing lake size due to coastal abrasion and organic matter delivery. We hypothesized that (i) CH oxidation depends on the natural oxygenation gradient in the lake water and sediments and increases with lake size because of stronger wind-induced water mixing; (ii) CO production increases with decreasing lake size, following the dissolved organic matter gradient; and (iii) both processes are more intensive in the upper than deeper sediments due to the in situ gradients of oxygen (O ) and bioavailable carbon.

Environmental controllers for carbon emission and concentration patterns in Siberian rivers during different seasons.

Despite the importance of small and medium size rivers of Siberian boreal zone in greenhouse gases (GHG) emission, major knowledge gaps exist regarding its temporal variability and controlling mechanisms. Here we sampled 11 pristine rivers of the southern taiga biome (western Siberia Lowland, WSL), ranging in watershed area from 0.8 to 119,000 km, to reveal temporal pattern and examine main environmental controllers of GHG emissions from the river water surfaces.

Organic carbon, and major and trace elements reside in labile low-molecular form in the ground ice of permafrost peatlands: a case study of colloids in peat ice of Western Siberia.

The fate of organic carbon (OC), nutrients and metals accumulated in thawing permafrost ice is at the forefront of environmental studies in the Arctic. In contrast to a fairly good understanding of the chemical nature of dissolved OC (DOC) and metals in surface Arctic waters, the speciation and colloidal status of solutes accommodated in the dispersed ground ice remain virtually unknown. Here we used a size fractionation procedure (centrifugal ultrafiltration) to quantify the proportion of colloidal (3 kDa to 0.

Dispersed ground ice of permafrost peatlands: Potential unaccounted carbon, nutrient and metal sources.

The physical and chemical consequences of massive ground ice (wedges) melt upon permafrost thaw is one of the central issues of environmental research linked to climate warming in the Arctic. Little is known about the chemical properties of dispersed ground ice abundant throughout permafrost peatlands that can easily melt with increasing active layer thickness (ALT). This is especially pertinent in continental lowlands, that account for sizeable areas of the Arctic, and contain high amount of organic carbon in both solid (peat) and liquid (porewater) phases.

Enhanced particulate Hg export at the permafrost boundary, western Siberia.

Arctic permafrost soils contain large amounts of organic carbon and the pollutant mercury (Hg). Arctic warming and associated changes in hydrology, biogeochemistry and ecology risk mobilizing soil Hg to rivers and to the Arctic Ocean, yet little is known about the quantity, timing and mechanisms involved. Here we investigate seasonal particulate Hg (PHg) and organic carbon (POC) export in 32 small and medium rivers across a 1700 km latitudinal permafrost transect of the western Siberian Lowland.

High carbon emissions from thermokarst lakes of Western Siberia.

The Western Siberia Lowland (WSL), the world's largest permafrost peatland, is of importance for understanding the high-latitude carbon (C) cycle and its response to climate change. Warming temperatures increase permafrost thaw and production of greenhouse gases. Also, permafrost thaw leads to the formation of lakes which are hotspots for atmospheric C emissions.