Impact of snow deposition on major and trace element concentrations and fluxes in surface waters of Western Siberian Lowland

Towards a better understanding of chemical composition of snow and its impact on surface water hydrochemistry in poorly studied Western Siberia Lowland (WSL), dissolved (melted snow) and particulate (> 0.45 μm) fractions of snow were sampled in February 2014 across a 1700-km latitudinal gradient (c.a. 56.5 to 68° N) in essentially pristine regions. Concentration of dissolved Fe, Co, Cu, As, La, increased by a factor of 2 to 5 north of 63° N. The pH, Ca, Mg, Sr, Mo and U dissolved concentration in snow water increased with the increase in concentration of particulate fraction (PF), which was also correlated with the increase in calcite and dolomite proportion in the mineral fraction, suggesting an enrichment of meltwater by these elements during dissolution of carbonate minerals. The concentrations of Al, Fe, Pb, La and other insoluble elements in Comparison of major and trace elements in dissolved fraction of snow with lakes and rivers of western Siberia across the full latitude profile revealed significant atmospheric input of a number of trace elements. The snow water concentration of DIC, Cl, SO 4 , Mg, Ca, Cr, Co, Ni, Cu, Mo, Cd, Sb, Cs, W, Pb and U exceeded or were comparable with spring-time concentration in thermokarst lakes of the region. The spring-time river fluxes (May–June, representing the snow melt period) of DIC, Cl, SO 4 , Na, Mg, Ca, Rb, Cs, metals (Cr, Co, Ni, Cu, Zn, Cd, Pb), metalloids (As, Sb), Mo and U in the discontinuous to continuous permafrost zone (64–68° N) can be fully explained by melting of accumulated snow. Therefore, the present study demonstrates significant and previously underestimated atmospheric input of many major and trace elements to their riverine fluxes during spring flood. The impact of snow deposition strongly increased northward, in discontinuous and continuous permafrost zones of frozen peat bogs, which is consistent with the decrease of the impact of rock lithology on river chemical composition in the permafrost zone of WSL, relative to the permafrost-free regions.