You are here:
ENANTIOMERIC RATIOS AS SOURCE TRACERS OF OC PESTICIDES IN GREAT LAKES AIR
Citation:
Falconer, R L., K. Wiberg, M. A. Tuttle, A. B. Leone, S. J. Amato, AND L. M. Jantunen. ENANTIOMERIC RATIOS AS SOURCE TRACERS OF OC PESTICIDES IN GREAT LAKES AIR. Presented at Society of Environmental Toxicology and Chemistry Conference, Philadelphia, PA, November 14-18, 1999.
Impact/Purpose:
The goal of this task is to contribute to a better understanding of human exposure to pesticides, especially for small children by developing methods to characterize sources and pathways in and around the residential environment. We will support the science behind FQPA and assist the Office of Pesticide Programs (OPP) in the development of guidelines for the assessment of residential exposure to pesticides. Specific research objectives include: (i) to evaluate and develop methods for measuring pesticides in air using passive/diffusive samplers. Assess and refine devices for the collection of surface transferable pesticide residues and to establish transfer efficiencies; (ii) to develop and apply analytical methods for new and emerging pesticides using both gas and liquid chromatographic methods in support of the National Exposure Research Laboratory's (NERL) Human Exposure Measurement Project; and, (iii) to conduct pilot studies investigating chiral chromatographic methods.
Description:
Organochlorine (OC) pesticides were used heavily in the cornbelt regions during the 60's and 70's. Volatilization of these pesticides from agricultural soils may be a significant source of contaminants to the atmosphere which may later be deposited in the Great Lakes. Pesticides are lost from soils by physical processes (volatilization, leaching), chemical breakdown and microbial attack. The latter is the only known mechanism that can result in enantioselective degradation. Enantioselective breakdown in soils may give an "old" source signature which can be used to track releases to the atmosphere and inputs to the Great Lakes. This work was done to determine if enantioselective degradation and subsequent volatilization of non-racemic pesticide residues from soils occurs and can be used to distinguish sources. Laboratory degradation studies were conducted by spiking racemic OC pesticides into pre-screened soils and determining enantiomeric ratios (ERs) over time. Field volatilization studies found that non-racemic pesticide ERs are conserved in the air above the soil upon volatilization. ERs of the OC pesticide Chlordane in home air were found to be very close to racemic while ambient air ERs were nonracemic. Multivariate Analysis was done to classify groups and determine trends and patterns. This work shows the possibilities of using enantiomers of chiral pesticides to follow degradation and exchange processes around and in the Great Lakes.
The research described herein was developed by the author, an employee of the US. Environmental Protection Agency, on her own. time. It was conducted independently of EPA employment and has not been subjected to the Agency's peer and administrative review. Therefore, the conclusions and opinions drawn are solely those of the author and should not be construed to reflect the views of the Agency.