Atmospheric Deposition of POPs: Implications for the Chemical Pollution of Aquatic Environments
Résumé
Persistent Organic Pollutants (POPs) are emitted into the atmosphere in warm or seasonally warm areas of significant urban/industrial activity. These compounds, which persist in the atmosphere, land, and aquatic environments, can be transported long distances toward those areas of the globe that are cold or seasonally cold (e.g., the Arctic). There is little doubt today that atmospheric transport and deposition via dry and wet deposition and air–water transfer are major drivers of POPs loading and inventories in both large lakes and costal/open marine systems. In the last 10 years, field data in large lakes, remote aquatic systems, and in the open seas conclusively show that atmospheric POPs interact dynamically with aquatic biota and the food web.
Global and most regional POPs protocols and programs do not inherently include an atmospheric component as direct source of those toxic chemicals, although water, biota, and sediment monitoring reveal the result. The Stockholm Convention of POPs is an example of a global program to limit or eliminate POPs where possible, but restricts the role of the atmosphere to its implications in the long-range atmospheric transport of POPs. In Europe, the Water Framework Directive and the Marine Strategy Framework Directive do not address the atmospheric role. In contrast, the Great Lakes Integrated Atmospheric Deposition Network is an example of the implementation of a scientifically aggressive, temporally consistent yet policy–policy relevant program to frame the role of the atmosphere of contaminating large lakes with POPs, old and new.
In this chapter, we provide a review of the atmospheric processes leading to accurate estimation of atmospheric deposition fluxes. We have selected three case studies of major water bodies (inland waters and marine) where atmospheric deposition of POPs plays a leading role in the loadings of POP to surface waters and contamination of ecosystems. Compiling evidence of the major role of atmospheric deposition in the bioavailability, exposure, and pollution status by POPs of relevant water bodies should raise awareness that this pathway should be addressed in current and future environmental protocols in its full dimension.