Avaliação da contaminação antrópica por metais no sedimento de fundo da Bacia do Igarapé do Educandos (Manaus/Amazonas)

Abstract

The urban growth rampant that occurred in Manaus until the early 2000s, associeted with the implementation of the Industrial Pole in the 60s, resulted in the degradation of water bodies and the surrounding areas of one of the main hydrographic basins in the city, Educandos Basin. Sediments act as a sink for both nutrients and contaminants and are extremely sensitive to anthropogenic impacts. The determination of the degree of pollution of a metal requires that its concentration is compared with a reference material not polluted. One of the indicators used is the geoaccumulation index. This study aims to determine the concentration of potentially toxic metals in sediments of Educandos Basin using geoaccumulation index. The sediment samples were collected in 9 sampling points, 3 sources of the main stream in February 2016. We determined the concentrations of Al, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Pb, Sn, Sr, Ti, V, Zn by ICP-OES. The Hg concentration was determined by DMA-80. For particle size analysis was used the laser diffraction granulometer. The moisture was determined following ASTM D 2216-98 and organic matter by the method of loss on ignition. Contamination by Hg may be considered moderately strong in the first sampling point and the other as a low to moderately polluted. The concentrations of other metals present values typical of those found in uncontaminated regions used as background. In terms of geoaccumulation index, results indicated metals that do not have enrichment, such as Al, Ti and V and others have clearly anthropogenic origin, such as Cd, Co and Li. Ba, Mg, Mn and Fe have similar performance enhancement. The Cr, Cu, Pb, Ni and Zn, geoaccumulation index had different rates according to the location sampled but have higher concentrations in industrial center region. The exploratory analysis showed that the samples meet in three groups according to their similarity in terms of metal contamination.