Kvale, Dorian2016-02-122016-02-122013-12https://hdl.handle.net/11299/177034University of Minnesota M.S. thesis. December 2013. Major: Environmental Health. Advisor: Matt Simcik. 1 computer file (PDF); vi, 58 pages.Studies from the turn of the century reported annual net volatilization of toxaphene from Lake Michigan and Lake Superior to the atmosphere. Net volatilization from Lake Superior was predicted to shift to net absorption before the year 2010. To measure current toxaphene concentrations and calculate instantaneous air-water fluxes, this study collected paired air-water samples in 2004 and 2005 on Lake Michigan and in 2006 on Lake Superior. Average(±SD) dissolved water concentrations were 380(±180) ng/m3 for Lake Michigan and 730(±85) ng/m3 for Lake Superior. Average gas-phase concentrations were 9.4(±4.1) pg/m3 over Lake Michigan and 22(±20) pg/m3 over Lake Superior. Instantaneous air-water fluxes averaged 240(±530) ng/m2-season for Lake Michigan and 370(±1000) ng/m2-season for Lake Superior. Mass budgets estimated a net export of 81(±30) kg/yr of toxaphene from Lake Michigan and 365(±64) kg/yr from Lake Superior. Half-lives were approximately 17 years for both lakes. These long residence times have prolonged toxaphene's elevated concentration in the upper Great Lakes, and will sustain it as a concerning contaminant in Lake Superior for well over 50 years.enair-waterfluxgasMichiganSuperiortoxapheneThesis or Dissertation