Heavy metal partition in acid soils contaminated by coal power plant

Abstract

Metal partition coefficient (Kp) may vary by several orders of magnitude because of the different soil characteristics. Therefore, for human health risk assessment it is important to determine the specific soil metal Kp. For the coal-fired Figueira (Figueira county, north of Parana State) power plant surrounding soil, two different extraction methods representing the soil liquid phase were used to determine the Kp of soil samples: an EDTA and a Ca(NO 3)2 extracting solution. In general, KpCa(NO3)2 values showed more variability and were higher than KpEDTA. Kp Ca(NO3)2/KpEDTA ratio for Cd, Ni and Zn was close to one, while Co, Cr, Cu and Pb ratios were higher than two. Subsequent Kp EDTA and KpCa(NO3)2 analyses showed similar soil adsorption for all metals, except Pb. Concerning the Figueira soil case, because of the relatively low KpCa(NO3)2/ KpEDTA ratio (except for Pb), both Kp values could be used for conducting human health risk assessment with mathematical models. ©2007 Sociedade Brasileira de Química.