Contamination of coastal versus open ocean surface waters: A brief meta-analysis

The relative contamination of coastal and open ocean surface waters by several classes of marine pollutants is compared by re-analysis of data published by GESAMP (1990) on the state of the oceans. This re-evaluation, together with analysis of recent IAEA data, suggests that marine pollutants can be divided into three broad categories: 1. those that are more concentrated in the open ocean environment than in coastal waters, including PCBs and (arguably) radioactive wastes; 2. those that are equally concentrated in open ocean and coastal waters, including DDT and its metabolites; and 3. those that are somewhat more concentrated in coastal waters than the open ocean, including chlorinated hydrocarbons and the heavy metals. The data do not support the conclusion drawn by GESAMP that although coastal waters are contaminated, “the open sea is still relatively clean”. Instead the data support the general conclusion that, with respect to the contaminants examined here, open ocean waters are approximately as contaminated as coastal waters.