Assessment of heavy metal contamination of seawater and marine limpet, Patella vulgata L., from Northwest Spain.

In the present work, both seawater and limpets (Patella vulgata L.) were collected from different sampling points in the Vigo estuary area (Galicia, NW Spain) and their heavy metal concentrations (Zn, Cd, Pb, Cu) were determined by means of a voltammetric technique. The results showed a direct relationship between the heavy metal levels in seawater and the content in biological samples, especially those obtained from limpet soft tissues, directly related to the increasing importance of anthropogenic environmental contamination. Heavy metal concentrations were usually higher in soft tissues than in shell, with a maximum difference corresponding to Cd and Zn (average of 93.6 and 86 folds, respectively). As expected, heavy metal content was higher in animal samples situated in inner part of the estuary zone, except for cadmium content in soft tissues, where a maximum of 5.62 ppm was quantified in limpet soft tissues collected next to the open sea area. Statistical analysis allowed the establishment of a clear relationship between Zn and Cd content in both shells and soft tissues from limpet, and especially between Zn and Cu in soft tissues (p < 0.001).