Bioaccumulation of potentially toxic elements in Ammonia tepida (foraminifera) from a polluted coastal area

This work documents the presence of potentially toxic elements (PTEs) in the sediment and in tests of Ammonia tepida, one of the most common benthic foraminifera species in coastal environments worldwide. It aims to analyze if the presence of PTEs in the carbonate test of this species is related to metals concentration in the sediment aiming its application in paleoenvironmental studies. Three chambers of fifty A. tepida specimens from contaminated and uncontaminated sediments from the Sepetiba Bay, one of the most polluted coastal systems from the SE Brazil, were analyzed using an Environmental Scanning Electron Microscope coupled with an X-ray Dispersive Energy Spectrometer. The results reveal the presence of lithogenic elements and PTEs in the tests of A. tepida. Relatively high values of Pb, Hg and Sn were found in specimens recovered from both polluted and unpolluted sediment layers. The bioaccumulation index revealed higher enrichment of Cd and Cr in tests from sediments moderately to heavily polluted by Cd and to a lesser extent by Cr. The results suggest that the incorporation of metals might be controlled and affected by several factors, such as the water residence time, availability of the metals, and biogeochemical processes. As a result, applications of this method utilizing A. tepida for paleoenvironmental studies do not appear to be feasible without further research.