Environ. Sci. Technol. 1997, 31, 1940-1945
Enantiomers of r-Hexachlorocyclohexane as Tracers of Air-Water Gas Exchange in Lake Ontario JEFFREY J. RIDAL* St. Lawrence River Institute of Environmental Sciences, 1111 Montreal Rd, Suite 144, Cornwall, Ontario, Canada K6H 1E1 TERRY F. BIDLEMAN Atmospheric Environment Service, 4905 Dufferin Street, Downsview, Ontario, Canada M3H 5T4 BRYAN R. KERMAN Lake Meteorology Laboratory, Atmospheric Environment Service, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, Ontario, Canada L7R 4A6 MICHAEL E. FOX AND WILLIAM M. J. STRACHAN National Water Research Institute, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, Ontario, Canada L7R 4A6
The technique of chiral phase capillary gas chromatography was applied to investigate the degradation and transport of the persistent chiral pesticide R-hexachlorocyclohexane (R-HCH) in the Lake Ontario environment. Chiral analysis gave the enantiomeric ratios (ERs) of R-HCH in samples taken May-October 1993 from the lake and its atmosphere. ERs of (+)R-HCH/(-)R-HCH for Lake Ontario surface and deep water samples were similar and averaged 0.85 ( 0.02 as compared with a value of 1.00 for the R-HCH standard. Higher ERs were observed in water samples from the Niagara River (0.91 ( 0.02) and from precipitation (1.00 ( 0.01). Air samples of R-HCH measured at 10 m above the lake show a seasonal variability with values near 1.00 in spring and fall and minimum values in individual samples near 0.90 in summer. A simple air-water gas transfer model demonstrates that enantiomeric ratios
