Trace element fractionation and transport in boreal rivers and soil porewaters of permafrost-dominated basaltic terrain in Central Siberia

The chemical status of similar to 40 major and trace elements (TE) and organic carbon (OC) in pristine boreal rivers draining the basaltic plateau of Central Siberia (Putorana) and interstitial solutions of permafrost soils was investigated. Water samples were filtered ill the field through progressively decreasing pore size (5 mu m -> 0.22 mu m -> 0.025 mu m -> 10 kDa -> 1 kDa) using cascade frontal filtration technique. Most rivers and soil porewaters exhibit 2-5 times higher than the world average concentration of dissolved (i.e., = 30%) of conventionally dissolved (< 0.22 mu M) forms for usually "immobile" elements such as divalent transition metals, Cd. Pb. V, Sri. Y, REEs, Zr, Hf, Th. The Al-normalized accumulation coefficients of TE in vegetation litter compared to basalts achieve 10-100 for B. Mn, Zn, As. Sr, Sri., Sb, and the larch litter degradation is able to provide the major contribution to the annual dissolved flux of most trace elements. It is hypothesized that the decomposition of plant litter in the topsoil horizon leads to Fe(III)-, Al-organic colloids formation and serves as an important source of elements in downward percolating fluids. (c) 2006 Published by Elsevier Inc