STUDY OF THE DISTRIBUTION OF METHYLMERCURY AND TOTAL MERCURY IN GRAIN-SIZE FRACTIONS OF FREEZE-DRIED ESTUARINE SEDIMENT SAMPLES

A study of the total mercury and methylmercury distribution in esturin e sediments is presented. Core sediments obtained in a polluted area w ere freeze-dried and sieved to obtain four fractions. Fraction 1, havi ng grain size <0.30 mm; Fraction 2, having grain size <0.30 mm; Fracti on 3, with grain size <1 mm and Fraction 4, having particle size >1 mm . In all these fractions total mercury (Cold Vapor AAS) and methylmerc ury (Gas Chromatography with ECD detection) have been analyzed. As exp ected high concentrations of total mercury and small concentrations of methylmercury were obtained in Fractions 1 and 2 but were not detecte d in Fractions 3 and 4, although the study of the data obtained sugges ts that significant amounts of geochemical mercury remain in these fra ctions. Attempts have been made to correlate data for both species whe n freeze dried sediments and the raw wet samples were analyzed.