Trace elements in oyster farming areas in the Amazon

Abstract

Analyses of contaminants in sediments, such as trace elements, are fundamental to characterize normality or alterations in aquatic environments. These are important data to evaluate areas used for aquaculture, particularly those where there is a closer interaction between sediments and organisms cultured, as in oyster cultivation. The concentrations of trace elements (Al, Cd, Co, Cr, Cu, Fe, Ni, Mg) were assessed in the sediments of six oyster farming areas in the Amazon estuary. Sediment sampling was carried out in the months of November 2013 (dry season) and April 2014 (rainy season) and central areas were prioritized. Levels of trace elements were quantified by induced plasma optical emission spectrometry (ICP-MS). Possible effects on aquatic biota were evaluated by comparing the levels of metals in the sediments with the reference values proposed in the TEL and PEL protocols. The concentrations of trace elements in sediments in all evaluated areas were higher in the rainy season, except for copper. Following the order of concentration, in most of the locations Al> Fe> Mg> Cr> Ni> Co> Cu> Cd. Only Cd levels were higher than the TEL and PEL.