Sedimentological evidence of human impact on a nearshore environment: Jurujuba Sound, Rio de Janeiro State, Brazil

The sedimentological and geochemical characteristics of nearshore deposits are examined using cores collected from a semi-enclosed marine embayment. Recent urbanization within the contributing catchment has stimulated the rapid accumulation of heterogeneous sediment rich in the kaolinite/illite clays that are characteristic of regional topsoils. Sediments also contain a high concentration of lead derived from street dust and elevated levels of copper and zinc associated with the uncontrolled discharge of untreated sewage wastes from disposal sources around the bay. Radiocarbon dating of shell fragments at depth in the cores places an earlier phase of accelerated but uncontaminated deposition in the 17th century, possibly as a result of early land clearance by European colonists.