Heavy metal concentrations in sediments and in mussels from Argentinean coastal environments, South America

Among environmental contaminants, heavy metals are currently considered to be some of the most toxic ones present worldwide due to their harmful effects on organisms and ability to bioaccumulate in aquatic systems. In this work, the concentration of heavy metals (Cd, Cu, Pb, Zn, Ni and Cr) in Brachidontes rodriguezii and in the fine sediments of several coastal sites at the southwest of Buenos Aires Province, Argentina is analyzed. The Bahia Blanca Estuary and Pehuen-Co beach are located in a highly complex oceanographic and ecological regional system, which creates the basis of one of the most valuable Argentinean habitats for fishing commercial species. An assessment, which involved analyzing distribution pattern of trace metals, comparative studies with sediment and ecological quality guidelines; and a sequential and integrated index analyses approach (containing Metal Pollution Index, Biosediment Accumulation Factor, Geo-accumulation Index (Igeo), Pollution Load Index and the mean Probable Effect Level quotients), was followed to estimate enrichment and risks of heavy metals in the sediments and in the mussels from these study areas. The results showed higher concentrations of some heavy metals (e.g., Cd, Cr and Ni) in mussels collected at Pehuen-Co, while no spatial differences in sediments were observed. According to the international environmental regulations, mean values of trace metals in mussels allowed to place both sites between "unpolluted and moderately polluted" and between the "low and medium category" of pollution. Furthermore, the mean concentrations found were within the detected ranges in other coastal sites worldwide.