Avaliação ambiental de sedimentos de fundo da sub-bacia do Igarapé Educandos (Manaus-AM) usando uma técnica de extração sequencial

Abstract

Fractionation of the metals Fe, Mn, Zn, Cu and Ni in sediments was performed for samples collected from ten locations from igarapé Educandos sub-basin, in Manaus AM, north Brazil. From air dried sediment particles was made a sequential extraction procedure proposed by the European Community Bureau of Reference (BCR). In general, the speciation study revealed that Mn, Zn, Cu and Ni have high mobility due to their high contents in the exchangeable/acid soluble fraction, while Fe is less mobile. Principal component analysis (PCA) clearly separated the metals in groups, due to different distributions of the metals in the various fractions, in sediments from different locations. The enrichment factor (EF) obtained for each metal showed the intense anthropogenic influence in the region. Based on the risk assessment code (RAC), Mn, Zn and Ni posed a very high risk to the ecosystem (RAC > 50%), Cu pose a high risk (RAC > 31%) and Fe a low risk (RAC < 10%).