File Entry: Especiación de metales en sedimentos del río Cuchivero, Venezuela

The total concentration and the chemical forms of heavy metals were determined in
superficial sediments of the Cuchivero river, Venezuela, using sequential extraction and
atomic absorption spectrophotometry with flame. Pollution indices were used to study the
distribution, pollution and environmental risk in the sediments. Total values ranged from,
394-457 mgkg-1 Fe, 46,87-74,82 Mn, 6,45-11,92 Zn, 1,70-5,75 Ni, 0,39-3,7 Cu, 1,25-3,63
Cr, 0,37-1,82 Co, 0,10-0,30 Cd y <Ld-0,20 mgkg-1 Pb. The metals were found to be
strongly associated with the residual fraction minerals (70 to 90%), carbonates and iron
oxihidroxides. Manganese and cadmium were associated mostly exchangeable fraction
(60-70%). The indices indicate that the source of metals is mainly bedrock; no metal
enrichment and contamination exist. The risk of environmental disruption is low for Fe
and Co, high for Zn and Ni, medium for Cu and Cr, and very high for Mn, Cd and Pb