"Atmospheric deposition and air-sea exchange of persistent chemicals in Bothnian Bay are investigated with goals of understanding current atmospheric loadings and how future loadings will respond to changes in ice cover and air concentrations. Substances examined are organochlorine pesticides (OCPs), current-use pesticides (CUPs) and brominated flame retardants (BFRs), substances which have been shown to undergo long-range transport and deposition in the Arctic and other remote locations. The CUP endosulfan and the BFRs polybrominated diphenyl ethers (PBDEs) are listed among the eight “hazardous substances of specific concern to the Baltic Sea” by the Helsinki Commission (HELCOM). PBDEs were recently added to the Stockholm Convention, and endosulfan and trifluralin are candidate substances. Concentrations of target chemicals are measured in air, Bay water, Bay snowpack, and rain. Seasonal and annual atmospheric loadings to the Bay are estimated from: a) air-water gas exchange, b) winter deposition in the snowpack, and c) rain deposition. Chemical “markers” (enantiomers of chiral compounds, natural bromoanisoles) are employed to trace air-water gas exchange, with emphasis on the effects of ice cover loss and the spring phytoplankton bloom. Enantiomer proportions are also used to follow microbially mediated diagenesis of chiral chemicals in water and soils. The project brings benefits to Sweden and the European community by making the first atmospheric deposition estimates for these substances in the northern Baltic, providing the first data on two HELCOM hazardous substances in Bay air and water, complimenting air measurements made at European Monitoring and Evaluation Program (EMEP) stations in southern Sweden and arctic Finland, and linking with the EU project ARCRISK at Svalbard by providing measurements for a common suite of chemicals at a continental subarctic site. The applicant brings to Umeå University more than 30 years’ experience in atmospheric transport a"