| Summary: | Four decades of research have provided a reasonable understanding of the outline of the biogeochemical cycles of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in coastal ocean and surface ocean ecosystems, including atmospheric transport to the sea, air-sea exchange processes, and the role of particulate matter in removing these chemicals from surface waters. It is clear that deep ocean fish are contaminated with POPs. However, despite available sampling and analytical capabilities, deep ocean ecosystems are much less sampled and understood. A multidecade assessment of POPs and PAHs in US coastal waters using bivalve sentinel organisms documents high concentrations near urban areas and also some stations where concentrations have begun to decline. The results are consistent with coastal sediments near urban areas being a leaky sink for POPs and PAHs, and sources from land continuing to contribute these contaminants to the sea. Other studies document coastal and continental margin surface sediments as a sink, albeit a potentially leaky sink, for POPs and PAHs. Floating plastic debris, including small pellets, has reemerged as an oceanic environmental concern. A "Pellet Watch" assessing plastic pellets and associated POPs and PAHs is underway. Enhanced studies of deep-ocean ecosystems are recommended. The findings are also relevant to biogeochemical cycles for emerging organic pollutants.
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