DISTRIBUIÇÃO DE METAIS PESADOS (COBRE, ZINCO E CHUMBO) EM ÁREAS RURAIS DO GRANDE RIO DE JANEIRO

Resumo

As part of a research program in environmental geochemistry, three rural areas close to Rio de Janeiro were sampled for traces of lead, copper and zinc. By atomic absorption analysis, seventeen samples of granitic rocks gave averages of 17,17 and 51 ppm for Pb, Cu and Zn, respectively; 28 samples of residual soil gave 28, 11 and 28 ppm; thirty samples of fluvial sediments 25, 14 and 31 ppm; and 26 samples of lagoonal sediments 32, 26 and 48 ppm. These values are within the expected range for areas with little or no contamination, and can be used for comparison with neighboring areas which have undergone heavy metal pollution. Comparisons between rocks soils and fluvial sediments show increases in Pb and decreases in Cu and Zn related to their relative solubilities during intense chemical weathering. The moderate increase in all three metals in lagoonal sediments is related to their affinity for clays, and possibly for organic material.