A review of field experiments to determine air-water gas exchange of persistent organic pollutants

Field experiments to determine air-water exchange of gas-phase persistent organic pollutants (POPs) in lakes and oceans are reviewed. Evidence for exchange comes from mass balancing total inputs and outputs of POPs in lakes, and experiments to determine air-water fugacity gradients. Several of these investigations in the Great Lakes demonstrate a net volatilization of polychlorinated biphenyls (PCBs). The annual cycle of hexachlorocyclohexanes (HCHs) in the Great Lakes, predicted from average monthly air concentrations, shows invasion for most of the year, with short periods of evasion during summer. Volatilization of HCHs takes place in some estuarine regions. Gas-phase fluxes of organochlorine pesticides to oceans and large lakes are of equal or greater magnitude than those due to precipitation and dry particle deposition.