THE SPECIES AND GEOCHEMICAL CHARACTERISTICS OF HEAVY-METALS IN THE SEDIMENTS OF KANGJIAXI RIVER IN THE SHUIKOUSHAN MINE AREA, CHINA

The different geochemical species of heavy metals in sediments in the Kangjiaxi River, Shuikoushan Mine Area, were separated and analysed. T he exchangeable proportions of Pb, Zn and Cu in sediments are very low , never exceeding 1.5%, but the proportion of exchangeable Cd is as hi gh as 10-15%. The CO3 form of Cd, Cu, Pb and Mn in total increases. Th e proportion of this form of Ca in total is very high (11-16%) which i ndicates that in the HCO3- and Ca2+ system in Kangjiaxi river water, u nder the present alkaline conditions (pH 7.6-7.8), the trace metals co -precipitate strongly with CO3. The heavy metals in the forms of Fe-Mn oxides are the main existing forms in the non-residue fractions. Thes e forms of Cd, Zn and Pb occupy a total of 21-52%, 29-54% and 65-79%, respectively and the proportions of this form of Mn reach 65-79%. This shows that the precipitation effect of Fe-Mn oxides in water is very strong and it is also the main characteristic of heavy metals in the s ediments in the subtropical climate. Copyright (C) 1996 Elsevier Scien ce Ltd