Distribuição de mercúrio total em sedimentos da plataforma continental Amazônica: Brasil

Abstract

This study was developed at the Amazon Continental Shelf aims to determine the levels of total mercury in the sediment bottom, and them to contribute as environmental matrix for the general plan of coastal monitoring in the North Region of the Brazil. Twenty sampling sites between May and June from 1999 to 2002, 2005 and 2007 were analyzed. The results indicate there is not evidence of anthropic activities associated to the contamination by mercury in the region. The levels of total mercury founded range between 0.047 and 0.166 mg kg-1 with average of 0.085±0,026 mg kg-1. The results are inside of the background interval determined to not contaminated or not polluted Amazon Rivers, which the interval ranges from 0.05 to 0.28 mg kg-1. The mercury concentrations in the sediment bottom, especially in the mud sediment, had shown a narrow dependence with both the clay levels (fine material) and organic matter, corroborating important geochemical mechanisms in Hg dynamics. The largest adsorption of the mercury can be associated to the increase of the oxides and hydroxides compounds of iron, aluminum, manganese and others primary and secondary minerals from the rocks of the Amazon drainage basin.