Soil-air exchange model of persistent pesticides in the United States cotton belt.
Measurements of organochlorine pesticides (lindane, cis-chlordane [CC], trans-chlordane [TC], trans-nonachlor [TN]), dieldrin, p,p'-dichlorodiphenyldichloroethylene [DDE], and toxaphene) in Alabama, USA, air and soil were used to assess the soil-air equilibrium status and to identify compounds with significant contributions to observed air burdens. Of the compounds tested, p,p'-DDE and toxaphene showed a significant potential for outgasing, followed by dieldrin and trans-nonachlor, which showed moderate outgasing potentials. Lindane, cis-chlordane, and trans-chlordane were near soil-air equilibrium. A fugacity-based, multilayered soil-air exchange model was used to predict temporal trends of chemical in air and soil resulting from reemission of soil residues to a presumed clean atmosphere (maximum emission scenario). Results showed that p,p'-DDE and toxaphene accounted for up to 50% of the observed air burden and that approximately 200 to 600 kg of p,p'-DDE and 3,000 to 11,000 kg to toxaphene are released to the atmosphere each year by soils in Alabama (area = 1.23 x 10(11) m2). High annual net fluxes were also predicted for dieldrin and trans-nonachlor (300-1,100 kg and 150-500 kg, respectively), but these only account for up to approximately 20% of their observed air burdens.
Harner
T
T
Meteorological Service of Canada, 4905 Dufferin Street, Downsview, Ontario M3H 5T4, Canada. tom.harner@ec.gc.ca
Bidleman
T F
TF
Jantunen
L M
LM
Mackay
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D
D000383:Agriculture; D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D005740:Gases / Q000032:analysis; D003368:Gossypium; D006843:Hydrocarbons, Chlorinated; D007306:Insecticides / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D014835:Volatilization
D000393:Air Pollutants; D005740:Gases; D006843:Hydrocarbons, Chlorinated; D007306:Insecticides; D012989:Soil Pollutants