Heavy metals in the lagos lagoon sediments

Concentrations of cadmium, cobalt, copper, chromium, iron, manganese, nickel, lead and zinc were determined in surface sediments of the Lagos Lagoon, Nigeria. The results revealed largely anthropogenic heavy metal enrichment and implicated urban and industrial wastes and runoff water transporting metals from land-derived wastes, as the sources of the enrichment. Higher levels (F < 0.05) of cadmium, iron, manganese, nickel and zinc occurred in sediment samples collected near industrialized-urban areas than in those from unindustrialized-rural areas only in the wet season. While iron constituted about 1% of dry sediment by weight, the other metals were present in trace amounts.