| Abstract: | Heavy metal polluted sites are bearing an acute hazardous risk for the groundwater, but also a potential one. While the acute risk can be assessed directly via seepage water measurements, determination of the potential risk is much more complex. It results from the sum of all reactions that are capable to mobilize heavy metals under worst case environ-mental conditions. Using a fourfold sequential extraction (SE4) such a worst case was simulated for four soils highly contaminated with Pb, Zn, and Cu. The resulting potential mobilizable amounts ϕpm have been compared with those derived from 6 single extractions. By means of variance analyses, it is shown that ϕpm of lead can be represented by a single extraction with NH2OH. In contrary, ϕpm of zinc can be represented using the pHstat test or an extraction with aqua regia, while ϕpm of copper can be represented only by aqua regia extraction. The water-soluble amounts deriving from the DEV-S4 test do not correlate with the potential mobilizable amounts of any metal. Therefore, an assessment of contaminated sites should include an aqua regia extraction additionally to the seepage water analysis. |
