CONTAMINATION OF THE MARINE-ENVIRONMENT FROM LAND-BASED SOURCES

Seven major categories of contaminants from land have perceived and/or real adverse effects on the coastal marine environment. Heavy metals, although perceived by the public to be a major contaminant of the marine environment, pose little threat on a global scale. Although sewage discharges, litter and oil spills constitute significant threats to the marine environment, their sources, fates and environmental effects are understood well enough to develop management strategies. Problems exist regarding those contaminants where management strategies have not been implemented. In the case of anthropogenically mobilized sediments, synthetic organic compounds, and nutrients, there is insufficient scientific information on the interrelationship between sources, transport, fates and effects to allow for development of management strategies for these contaminants, short of total source control. Based on trends in world population growth, and global production and use of pesticides and fertilizers, it is concluded that nutrients, synthetic organic compounds and sewage pose the greatest present and future threat to the marine environment.