Potential bioavailability assessment and distribution of heavy metal(oids) in cores from Portman Bay (SE, Spain)

Abstract

A total of 120 sediments from 12 cores of Portman Bay (SE Spain) were studied to assess the degree of contamination and ecological risk related to potentially toxic elements (PTEs) by combining a geochemical and mineralogical characterization with the assessment of the bioavailable forms of trace metals (As, Cd, Cu, Fe, Pb, Zn). 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 bioaccessibility extraction procedure.

The 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. Occasionally, jarosite and carbonates (calcite and dolomite) appear. The total PTEs content is high whereas the sediments generally have a very low soluble PTE content.

The SEM/AVS ratio is less than unity in most 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 (alkaline) while the rest of the elements have greater availability in the stomach (acid).