Heavy metal content in seaweeds

Cadmium, copper, chromium, lead, nickel, and zinc were measured in water, sediments, and some common macroalgal species (Ulva fasciata, Ulva reticulata, Sargassum species, Padina boryana, Turbinaria ornata, Colpomenia sinuosa) of four sites, namely La Cuvette, Pointe d''Esny, Poste La Fayette and Pointe aux Sables. Heavy metal concentrations were determined by flame atomic absorption spectrophotometry. A correlation study (spearman) between the different elements in seawater, sediments, and seaweeds was also done. Metals were thus found to most accumulate in sediments, and seaweeds. The most abundant heavy metal in sediment was observed to be chromium whereas zinc was most prevalent in seaweeds. The highest average concentration read for chromium in sediment was 43.513 ± 3.315 mg/Kg at Pointe d''Esny whereas the highest mean reading for zinc in seaweeds was 192.52 ± 11.30 mg/Kg at Pointe aux Sables. Levels of cadmium, copper, nickel, and chromium in seawater in this study exceeded permissible limits at most of the sites, showing that heavy metal contamination is quite and significant in the coastal waters of Mauritius.