engleski

Heavy metals in alluvial sediments of the river Drava (Slovenia and Croatia)

Geochemical research of soil, stream and overbank sediments and rocks in Slovenia and Croatia was carried out continually in last two decades. The research target was to obtaining of geochemical data, especially the content of heavy metals in top soil and deeper soil horizons in the valley of the river Drava. The researches have been focused on the overbank sediments (river terraces and flood plains) from Austrian border till the confluence of the rivers Mura and Drava. The targets of collaboration were defining of geochemical background before industrial revolution and evaluation of anthropogenic influence on sediment and soil pollution in the Drava Valley ; determination of spatial distribution of heavy metals in soils on alluvial deposit of the river Drava (river terraces and flood plain) and the distribution of heavy metals in the sediment and soil profiles, and depth of anthropogenic influence. With purpose to define pollution outspread of heavy metals in the sediments and soil profiles we took samples perpendicular to the river Drava flow. The profiles were set equally in both sides of border due to get the better information of spatial distribution of heavy metals in researched area (from Austrian border till the confluence of rivers Mura and Drava.). All together, 172 samples in 19 soil profiles in Slovenia and 161 samples in 27 soil profiles in Croatia were sampled. Analysis for 41 chemical elements (Al, Ca, Fe, K, Mg, Na, P, S, Ti, Ag, As, Au, Ba, Be, Bi, Cd, Ce Co, Cr, Cu, Hf, La, Li, Mn, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Sn, Sr, Ta, Th, U, V, W, Y, Zn and Zr) was performed by inductively coupled plasma mass spectrometry (ICP-MS) after four-acid digestion (fraction <0, 125mm). Hg was determined with cold vapour atomic absorption spectrometry CV-AAS after aqua regia digestion. Preliminary data processing has shown that primary pollution, which is consequence of historical mining and smelting in Carinthia, has a huge influence on chemical composition of alluvial sediments of the river Drava. The sediments of upper stream are less polluted with heavy metals due to stronger river erosion. But, after the river spreading into the Pannonian Basin alluvial plains, the content of heavy metals increase significantly. In Ptuj, Ormoz and Varazdin region, content of Cd, Zn and Pb exceed official critical level for heavy metals in soil. High content of heavy metals are also significant till the confluence of rivers Drava and Danube, what is proven by geochemical sampling in the past.

geochemistry; alluvial sediments; heavy metals; river Drava; Croatia; Slovenia

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