Atmospheric POPs Threat the Marine Environments

Abstract

Atmospheric input of POPs (e.g., organochlorine pesticides [OCPs], halogenated aromatic hydrocarbons -polychlorinated biphenyls (PCBs), chlorinated or brominated dibenzofuran and dibenzo-p-dioxins [PCDDs/DFs, PBDDs/DFs]) and polycyclic aromatic hydrocarbons [PAHs]) mainly comes from anthropic activities, including as primary emission sources those from agricultural production and industrial processes. Although the commercial use and application of some POPs have been totally prohibited or severely restricted (Stockholm Convention), they continue to be found in the air and other environmental compartments around the world. Global atmospheric long range transport has been widely demonstrated for these compounds and represents a dominant process by which POPs reach the oceans. This is far more relevant for POPs, such as OCPs and PCBs than for PAHs, as the first ones are only generated in the continental sector. On the contrary, PAHs can be generated in the marine environment, as in oil spills from ships. In addition to the atmospheric transport, atmosphere-sea interactions and the inter-compartmental transfer play an essential role in terms of deposition and subsequent entry of POPs into marine ecosystems. The transfer of POPs from the atmosphere to the ocean can take place by dry deposition, wet deposition and by diffusive gaseous flows. Fundamentally, in open marine systems, atmospheric deposition determines that the oceans could act as reservoirs for POPs. Also, aquatic planktonic species are believed to be impacted by atmospheric deposition, supporting the accumulation of POPs through the food chain. Once in the ocean, the fate of POPs will ultimately depend on several events such as movement flows, chemical transformations, physical and biological processes. In this context, highlighting the important links between the atmospheric and oceanic systems, the objective of the present chapter is to consider the implication of atmospheric transport in the circulation of POPs and to present the relevance of atmospheric deposition to the oceans as a key process that affects the marine environments.