Many modern and legacy pesticides are chiral and consist of one or more pairs of mirror-image enantiomers. The older pesticides were manufactured as racemates (1:1 proportion of enantiomers), but often only one enantiomer is effective and there is a growing trend toward manufacturing pesticides that contain only the active compound. Degradation in soil and water is often enantioselective, with different half-lives for each enantiomer, and leads to residues with enantiomer proportions that are altered from those in the applied product. This provides novel opportunities to use enantiomer proportions to follow environmental transport and fate processes. This lecture presents highlights of our adventures in environmental stereochemistry, employing enantiomer proportions to investigate:
- Fate of the herbicides mecoprop and metolachlor in Ontario streams and lakes.
- Formation of bound residues in soil.
- Exchanges between soil-air and water-air
- Sources and pathways of chiral organochlorines in arctic air.
Examples come from the following publications:
Bidleman, T.F., Jantunen., L.M., Kurt-Karakus, P.B., Wong, F. (2012). Chiral compounds as tracers of atmospheric sources and fate: review and prospects for investigating climate change influences. Atmos. Pollut. Res. 3, 371-382.
Wong, F., Kurt-Karakus, P.B., Bidleman, T.F. (2012). Fate of brominated flame retardants and organochlorine pesticides in urban soil: volatility and degradation. Environ. Sci. Technol. 46, 2668-2674..
Wong, F., Bidleman, T.F. (2011). Aging of organochlorine pesticides and polychlorinated biphenyls in muck soil: volatilization, bioaccessibility and degradation. Environ. Sci. Technol. 45, 958-963.
Kurt-Karakus, P.B., Teixeira, C., Small, J., Muir, D.C.G., Bidleman, T.F. (2011). Current-use pesticides in inland lake waters, precipitation and air from Ontario, Canada. Environ. Toxicol. Chem. 30, 1539-1548.
Kurt-Karakus, P.B., Bidleman, T.F., Muir, D.C.G., Struger, J., Sverko, E., Cagampan, S., Small, J.M., Jantunen, L.M. (2010). Mecoprop, dichlorprop and metolachlor in Ontario streams, 2006-2007 vs. 2003-2004. Environ. Pollut. 158, 1842-1849.
Kurt-Karakus, P.B., Muir, D.C.G., Bidleman, T.F., Small, J., Backus, S., Dove, A. (2010) Metolachlor and atrazine in the Great Lakes. Environ. Sci. Technol. 44, 4678-4684.