Progress 02/02/01 to 02/02/04
Outputs
Chlordane has been banned since 1988, but soil-bound residues continue to be observed. Chlordane has been found in both indoor and outdoor ambient air. We are conducting studies to help explain the continued presence of chlordane in ambient air. Chlordane was originally applied as a mixture of over 140 different related compounds. The primary active ingredients of this mixture were cis-chlordane, trans-chlordane, and trans-nonachlor and together they comprised about 25% of the total. Two of the three primary active ingredients are chiral, present as racemates in the technical mixture. Therefore, analysis of the relative concentrations of both chiral and achiral components of the technical mixture in environmental samples can differentiate enantioselective processes (such as microbial degradation) from physical-chemical processes (such as volatilization). We have examined the compositional and chiral profiles of chlordane in Connecticut ambient air at four locations (2
urban, 1 suburban, 1 rural) within Connecticut and compared these data to those reported for ambient air in other parts of the country. We are also conducting studies at a weathered contaminated site from a chlordane application over 40 years ago. Air samples were collected using high volume samplers to draw air through glass fiber filters (to remove particulate matter) and polyurethane foam plugs to collect the vapor phase chlordane compounds. The samples were collected at three different heights above the contaminated plot, and at the four other locations. Samples for each height and location were collected every two weeks. Vapor phase samples were extracted using Soxhlet extraction cleaned up with florisil column chromatography and analyzed using chiral gas chromatography /electron impact ion trap mass spectrometry. The results of these analyses show that the ambient air concentrations and profiles in Connecticut are similar to ambient concentrations and profiles in other parts of
the country. These air concentrations are consistent with a source related to the volatilization of chlordane from locations where it was used as a termiticide around homes. Air collected above the contaminated plot shows that the concentration decreases with height and that the concentrations from above the plot are higher than concentrations observed at the other locations. Furthermore, the results also show that the enantiomeric fractions (EFs) of chiral chlordane components changed with height. Samples taken at lower heights had EFs more similar to soil EFs than samples taken at the same location but a greater height. Together these results indicate that chlordane from this 40-year-old application continues to volatilize from this site. The data were used to develop a model of the volatilization from the experimental plot. This model led to the conclusion that volatilization occurs from the top-most cm of soil. The chlordane in this surface layer is lost at a rate exceeding the
rate at which the surface layer is replenished from the soil reservoir, though cultivation processes can quickly replenish the surface layer by mixing the surface with the reservoir.
Impacts
This research has shown that chlordane present in Connecticut air is likely the result of volatilization of chlordane from locations where it was used as a termiticide. Once volatilized the chlordane can be transported, thus the chlordane in Connecticut air is a sum of both chlordane volatilized within the state as well as chlordane transported into the state with air from other regions. This volatilization tends to occur from the topmost centimeter of contaminated soil, and can be affected by cultivation practices. This knowledge can lead to improved management of the residues of this pollutant. The long-term impact of identifying chlordane-contaminated sites is to avoid planting edible plants in these areas and to avoid human exposure to contaminated soil. Overall, there will be less human exposure to pesticides, thereby reducing health risks.
Publications
- Eitzer, B.D., Iannucci-Berger, W., Mattina, M.J.I. 2003. Volatilization of Weathered Chiral and Achiral Residues from Soil. Environ. Sci. Technol. 37:4887-4893.
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Progress 01/01/02 to 12/31/02
Outputs
The pesticide chlordane was widely used in the United States for both agricultural and residential applications from the time of its introduction in the 1940s through its banning by the Environmental Protection Agency in 1988. It has been shown to be both toxic and persistent in the environment. It has been suggested that persistent pesticide residues become tightly bound to soil over time and become hard to extract from soil. Despite these suggestions banned persistent pesticides, including chlordane, are still being found in ambient air samples. We are conducting studies to help elucidate the environmental fate of these compounds, which will in turn help to explain their continued presence in ambient air. Our studies have focused on chlordane, originally applied as a mixture of over 140 different related compounds known as technical chlordane. We have examined the compositional and chiral profiles of chlordane in Connecticut ambient air at several locations and
compared these data to those reported for ambient air in other parts of the country. We are also conducting studies at a weathered contaminated site from a single chlordane application over 40 years ago. Samples of ambient air are collected using high volume samplers to draw air through glass fiber filters and polyurethane foam plugs. The samples were collected at three different heights above the contaminated plot, and at four other locations (2 urban, 1 suburban, 1 rural). Samples for each height and location were collected every two weeks. Vapor phase samples were extracted using Soxhlet extraction cleaned up with florisil column chromatography and analyzed using chiral gas chromatography /electron impact ion trap mass spectrometry. The results of these analyses to date show that the ambient air concentrations in Connecticut are similar to ambient concentrations in other parts of the country. Air collected above the contaminated plot shows that the concentration decreases with
height and that the concentrations from above the plot are higher than concentrations observed at the other locations. Furthermore, the results also show that the enantiomeric fractions (EFs) of chiral chlordane components changed with height. Samples taken at lower heights had EFs more similar to soil EFs than samples taken at the same location but a greater height. Together these results indicate that chlordane from this 40-year-old application continues to volatilize from this site. Use of wind speed data, time profiles for ambient air concentrations and comparison with ambient background samples allow us to conclude that volatilization from weathered residues is occurring, is a phenomenon which is dependant on both temperature and soil cultivation, and occurs from the topmost centimeter of soil.
Impacts
Knowledge of the volatilization rate of chlordane from soils and concentrations in ambient air allows us to better understand the environmental fate of chlordane. This in turn can lead to improved management of chlordane residues and allow us to lower the risk to the public from this toxic and persistent pollutant.
Publications
- Mattina, M.J.I., White, J., Eitzer, B., and Iannucci-Berger, W. 2002. Cycling of weathered chlordane residues in the environment: Compositional and chiral profiles in contiguous soil, vegetation, and air compartments. Environ. Toxicol. Chem. 21:281-288.
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Progress 01/01/01 to 12/31/01
Outputs
The pesticide chlordane was widely used in the United States for both agricultural and residential applications from the time of its introduction in the 1940s through its banning by the Environmental Protection Agency in 1988. It has been shown to be both toxic and persistent in the environment. As applied, chlordane was not a single compound, but a mixture of over 140 different related compounds known as technical chlordane. It has been suggested that these persistent residues become tightly bound to soil over time and become hard to extract from soil. We have inititiated studies which show that although weathered residues may be tightly bound at least a portion of those residues can still volatilize from the soil. We have been studying the compositional and chiral profiles of chlordane in Connecticut soils and the ambient air overlaying those soils. Our studies are currently focused on a site contaminated by a single chlordane application over 40 years ago. Samples
of ambient air are collected using high volume samplers and polyurethane foam plugs at three different heights above the contaminated plot; along with background ambient air samples from alternate sites, and, soil samples from the plot and background sites. Air samples for each height and location are collected every two weeks. Samples are extracted using Soxhlet extraction, cleaned up with florisil column chromatography, and analyzed using chiral gas chromatography /electron impact ion trap mass spectrometry. To date, the results of these analyses show that the ambient air concentration above the plot decreases with height and that air samples taken from above the plot have higher concentrations than background sites. The results also show that the enantiomeric fractions (EFs ) of the chiral chlordane components changed with height. The closer the sample was to the soil the greater the agreement in EFs between the soil and the air. Together these results indicate that chlordane is
volatilizing from this site. Use of wind speed data and comparison with ambient background samples produce an estimated volatilization rate of 1.4% of the chlordane present in the top 10 cm of soil and a 49 year half-life based on volatilization.
Impacts
Knowledge of the volatilization rate of chlordane from soils and concentrations in ambient air allows us to better understand the environmental fate of chlordane. This in turn can lead to improved management of chlordane residues and allow us to lower the risk to the public from this toxic and persistent pollutant.
Publications
- "Compositional and Chiral Profiles of Weathered Chlordane Residues in Soil", Brian D. Eitzer, Mary Jane Incorvia Mattina, William Ianucci-Berger. Environmnental Toxicology and Chemistry, 2001, 20, 2198-2204.
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