A review of processes involved in the exchange of persistent organic pollutants across the air–sea interface

Atmospheric deposition across the air–sea interface is the main input route for persistent organic pollutants (POPs) to the marine environment and its ecosystems. The main processes contributing to air–sea exchange of POPs are diffusive vapour exchange, precipitation scavenging of vapours and particle-sorbed chemicals, and dry deposition with particles. Additional processes within the atmosphere and surface water affecting this exchange are aerosol–vapour partitioning, and partitioning and sedimentation in the water-column. These processes are discussed and recent findings are summarised. Commonly employed expressions used for describing these processes in models are presented, with a special focus on the influence of temperature and other seasonal parameters. Research gaps are identified which have to be addressed to gain a solid understanding of the environmental transport and distribution of POPs. This is needed to implement and evaluate the effectiveness of recent international agreements to protect the marine environment from the deleterious effects of POPs.