Atmospheric emissions and long-range transport of persistent organic chemicals

Abstract

Persistent organic chemicals include several groups of halogenated compounds, such as polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs), and polyfluorinated carboxylic acids (PFCAs). These chemicals remain for long times (years to decades) in the environment and cycle between different media (air, water, sediment, soil, vegetation, etc.). The environmental distribution of this type of chemicals can conveniently be analyzed by multimedia models. Multimedia models consist of a set of coupled mass balance equations for the environmental media considered; they can be set up at various scales from local to global. Two applications of multimedia models to airborne chemicals are discussed in detail: the day-night cycle of PCBs measured in air near the surface, and the atmospheric long-range transport of volatile precursors of PFCAs, formation of PFCAs by oxidation of these precursors, and subsequent deposition of PFCAs to the surface in remote regions such as the Arctic.