Sequential chemical extraction of copper from clay: an overview

In general, the total content of heavy metals and trace elements in soils is useful, but the speciation (bioavailability) is also in need for agricultural purpose, for example. The present paper studies the efficiency of some soil remediation treatments on soils polluted, especially with copper, by using sequential chemical extraction (SCE). Usually, SCE is fractioned, according to Tessier, in five fractions: exchangeable, carbonate bound, Fe and Mn oxide bound, organic matter bound and residual. Copper (Cu) is one of the contaminants found in many soils around the world. In small concentration, it is an essential microelement for plants and organisms, but in high concentrations, it is harmful for the entire ecosystem. Because the concentrations of Cu are associated with soil texture and several other parameters, many remediation soil treatments are based on organic mixture, by converting the element into a less exchangeable form, and thus less bioavailable. In this study, the efficiency of organic amendments such as organic matter (OM), zero-valent iron with organic matter (OMZ), dolomite (DL) and organic matter with dolomite (OMDL) are investigated. These treatments were applied on soils affected by Cu pollution. The results indicated that OMDL and OMZ treatments had the best efficiency on Cu pollution, by enhancing the stability of the element, decreasing the level of bioavailability.