Trace metals in settling particles from the sewage impacted Buenos Aires coastal area in the Río de la Plata estuary, Argentina

Abstract

Sediment traps deployed in Buenos Aires sewage outfall area collected a substantial amount of material (average mass flux 22 ± 12 g cm 2 year−1) with very high metal concentrations, mostly in the range of hazardous exposition for organisms (Zn: 138–671, Cu: 41–273, Cr: 44–255 and Pb: 26–260 μg g−1). The combination of high mass fluxes and concentrations results in huge metal fluxes (0.005–0.7 to 3.6–31 g m−2 day−1 for minor elements and Fe, respectively). Metal concentrations were correlated to the total mass flux and total organic carbon but with different trends for redox-sensitive Fe and Mn (negative) and anthropogenic elements (positive). This reflects the key role of organic discharges promoting anoxia with Fe and Mn evasion, and also contributing toxic metals.