S1 SUPPORTING INFORMATION Air-Water Exchange of Anthropogenic and Natural Organohalogens on International Polar Year (IPY) Expeditions in the Canadian Arctic Fiona Wong †,‡ , Liisa M. Jantunen † , Monika Pućko §,║ , Tim Papakyriakou ║ , Ralf M. Staebler ┴ , Gary A. Stern §,║ , Terry F. Bidleman †, * † Centre for Atmospheric Research Experiments, Environment Canada, 6248 Eighth Line, Egbert, ON, L0L 1N0, Canada ‡ Department of Chemistry, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada § Freshwater Institute, Department of Fisheries and Oceans, University of Manitoba, 501 University Crescent, Winnipeg, MB, R3T 2N6, Canada ║ Centre for Earth Observation Science, University of Manitoba, 474 Wallace Building, 125 Dysard Road, Winnipeg, R3T 2N2, Canada ┴ Science and Technology Branch, Environment Canada, 4905 Dufferin St, Toronto, ON, M3H 5T4, Canada * Corresponding Author. Tel: 1-705-458-3322; Fax: 1-705-458-3301 List of SI: Page SI-1 Sample collection, extraction and analysis, quality control S2 SI-2 Air-water gas exchange S6 SI-3 Whitman two-film model S8 Table SI-1 Details of low volume air (LV Air) sampling at ~1 m and 15 m above water or ice surface during Legs 1b, 8 and 9 S9 Table SI-2 Concentrations (pg m -3 ) of α-HCH, γ-HCH, HCB, DBA and TBA in low volume air samples (LV Air) collected on Legs 1b, 8 and 9 S10 Table SI-3 Concentrations (pg m -3 ) of α-HCH, γ-HCH in high volume air samples (HV Air) collected on Legs 1a, 1b, 8 and 9. S11 Table SI-4 Concentrations (pg L -1 ) of α-HCH, γ-HCH , DBA and TBA in low volume water samples (LV Water) collected on Legs 1a, 1b, 8 and 9 S12 Table SI-5 Concentrations (pg L -1 ) of α-HCH, γ-HCH and HCB in high volume water samples (HV Water) collected on Legs 1a, 1b, 8 and 9 S13 Table SI-6 Fluxes of chemicals in the southern Beaufort Sea during open water condition (i.e. Leg 9) S14