Extraction of soil metals by delute hydrochloric acid; an alternative to sequential extration for estimation of available metal contents in urban soils?

Abstract

Although the total contents of toxic metals in soils are generally used for estimation of the degree of pollution of a given site, on1y a fraction of the metal content is likely to have a significant role in environmental processes. Also, in many cases of moderate pollution a decrease in metal availabi1ity in soil may be feasib1e using relatively cheap techniques, whi1e a decrease in the total contents requires much more difficult treatments and their application is often questionable. Therefore, obtaining a good estimate of metal availability is of the utmost importance in soils with re1atively high total contents. Extraction with EDTA is usually considered an estimate of metal avai1abi1ity in soi1s (Quevauviller et al., 1997). The technique proposed by the European IRMM for sequentia1 extraction of meta1s in soi1s distinguishes 3 fractions (Rauret et al., 1999), whi1e those metal forms not inc1uded in them are considered of no environmenta1 significance. Sutherland (2002) proposed a simp1er extraction with 0.05 M HCl as a good ana1ytica1 assessment of metal pollution.