As, Cd, Cu, Mn, Pb, and Zn Contents in Sediments and Mollusks (Hexaplex trunculus and Tapes decussatus) from Coastal Zones of a Mediterranean Lagoon (Mar Menor, SE Spain) Affected by Mining Wastes

Individuals of Hexaplex trunculus, Tapes decussatus, and associated sediments were collected from 16 coastal sampling plots of the Mar Menor lagoon (SE Spain), and the metal and As concentrations were determined. The sediments had maximum values (in milligrams per kilogram dry weight [d.w.]) of 7,132 for Zn; 6,975 for Pb; 5,039 for Mn; 501 for As; 74 for Cu; and 9.1 for Cd. Specimens of H. trunculus could be collected from all the sampling plots, and it was found that concentrations of Zn (between 883 and 3,130 mg kg(-1) d.w.), Pb (between 0.09 and 222 mg kg(-1) d.w.), Mn (between 7.6 and 17.7 mg kg(-1) d.w.), As (between 144 and 418 mg kg(-1) d.w.), and Cd (between undetectable and 8.4 mg kg(-1) d.w.) in soft tissues significantly increased when concentrations in sediments increased. H. trunculus apparently regulated Cu assimilation (concentrations between 17.7 and 47.2 mg kg(-1) d.w.) in its soft tissues. T. decussatus was very scarce or even absent from sites with higher metal and As contents in the sediments. Hence, H. trunculus could be used as a bioindicator of metals and As pollution, but not T. decussatus. Based on our results, a human health risk exists because the species analyzed are collected from the studied zone and so are consumed by the population.