Distribution and bioavailability of Cr in central Euboea, Greece

Plants and soils from central Euboea, were analyzed for Cr-(total), Cr(VI), Ni, Mn, Fe and Zn. The range of metal concentrations in soils is typical to those developed on Fe-Ni laterites and ultramafic rocks. Their bioavailability was expressed in terms of concentrations extractable with EDTA and 1 M HNO3, with EDTA having a limited effect on metal recovery. Cr(VI) concentrations in soils evaluated by alkaline digestion solution were lower than phytotoxic levels. Chromium and Ni - and occasionally Zn - in the majority of plants were near or above toxicity levels. Cr(VI) concentrations in plants were extremely low compared to total chromium concentrations. Cr-(total) in ground waters ranged from < 1 mu g.L-1 to 130 mu g.L-1, with almost all chromium present as Cr(VI). With the exception of Cr-(total) and in some cases Zn, all elements were below regulatory limits for drinking water. On the basis of Ca, Mg, Cr-(total) and Si ground waters were classified into three groups: Group(I) with Cr concentrations less than 1 mu g.L-1 from a karstic aquifer; Group(II) with average concentrations of 24 mu g.L-1 of Cr and relatively high Si associated with ophiolites; and Group(III) with Cr concentrations of up to 130 mu g.L-1, likely due to anthropogenic activity. Group(III) is comparable to ground waters from Assopos basin, characterized by high Cr(VI) concentrations, probably due to industrial actrivities.