Sediments from cores from Portman Bay (SE Spain) were studied to assess the degree of contamination and ecological risk related to trace metals by combining a geochemical and mineralogical characterisation with the assessment of the bioavailable forms of trace metals. With this purpose, sediment contamination was assessed by total and water soluble content, and potential bioavailability by the simultaneously extracted metals and acid volatile sulphides (SEM-AVS) approach, and by an oral bioaccesibility extraction procedure.
Sediments are essentially sandy (>80%), the most important minerals are iron phases such as siderite, iron oxides and hydroxides and pyrite; clay minerals such as clinochlore, greenalite and biotite; and quartz. Ocasionally, jarosite and carbonates (calcite and dolomite) appear. The total heavy metal(oid) content is high while collected materials generally have a very low soluble trace metal content.
The SEM/AVS ratio is less than unity in almost samples, indicating that there is enough sulphur so that if there was a release of metals, they could precipitate as sulphides. After the bioaccessibility extraction, the results showed that zinc and cadmium are more bioaccessible in the intestinal environment (basic) while the rest of the elements have greater availability in the stomach (acid).