Exchange Dynamics of Typical Emerging and Legacy Persistent Organic Pollutants at the Air‐Water Interface Over a Strongly Human‐Influenced Large River Estuary

Abstract

AbstractTo explore the riverine or atmospheric influence on the source‐sink fates of typical persistent organic pollutants (POPs): polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in the large river estuary, atmospheric and seawater samples were collected simultaneously over a whole year at a remote small island in the Yangtze River Estuary (YRE), the East China Sea. A comparable net input of BDE‐209 from the atmosphere to the sea for both air‐water gas exchange and dry/wet deposition was observed. The gas deposition of BDE‐209 had a strong dependence on the gaseous concentration, which was in turn governed by atmospheric transport. For Br<10‐BDEs, which have been prohibited in recent years, the gas exchange almost reached equilibrium at the air‐water interface during the whole observation period. However, a strong net gas volatilization was observed for legacy ΣICESPCBs especially in the flood season, and the volatilization was significantly associated with ambient parameter‐wind speed. These remarkably different exchange dynamics of PBDEs and PCBs at the air‐water interface over the YRE could be attributed to their primary emission intensity and inconsistent environmental transport pathways. The reversal of the source‐sink fates of BDE‐209 and legacy PCBs suggest that the strongly human‐influenced large river estuary water could act as a source‐sink buffer for POPs during the switch from approved to prohibited usage.