Trace elements and δ13C and δ15N isotopes in sediments, phytoplankton and oysters as indicators of anthropogenic activities in estuaries in the Brazilian Amazon

Abstract This study investigated two estuaries on the northern coast of Brazil submitted to different anthropic activities. The main objective was to assess the use of oysters (Crassostrea gasar and Paxyodon ponderosus) and phytoplankton as bioindicators of environmental contamination. Water, sediments, phytoplankton and oysters were chemically analyzed by ICP-OES and ICP-MS. The source for metal bioaccumulation in oysters and phytoplankton was assessed using BSAF (Biota Sediment Accumulation Factor) and the isotropic relations of stable carbon ( δ 13 C and δ 15 N). The oyster-sediment BSAF showed bioaccumulation of Mn, Cu, Zn, Se, Sr, As, Cd and Ba, which was supported by the correlations of Fe, Mn, Cu, Zn, Se, Sr, Al, Ba and Pb with the isotopes ( δ 15 N and δ 13 C), which confirmed bioaccumulation as well as biodilution and biomagnification in oysters and phytoplankton. That reflects the efficiency of organisms in bioconcentrating metals and their capacity as bioindicators of contamination.