title: Organochlorine pesticides in soils of Mexico and the potential for soil-air exchange.
abstract: The spatial distribution of organochlorine pesticides (OCs) in soils and their potential for soil-air exchange was examined. The most prominent OCs were the DDTs (Geometric Mean, GM=1.6 ng g(-1)), endosulfans (0.16 ng g(-1)), and toxaphenes (0.64 ng g(-1)). DDTs in soils of southern Mexico showed fresher signatures with higher FDDTe=p,p'-DDT/(p,p'-DDT+p,p'-DDE) and more racemic o,p'-DDT, while the signatures in the central and northern part of Mexico were more indicative of aged residues. Soil-air fugacity fractions showed that some soils are net recipients of DDTs from the atmosphere, while other soils are net sources. Toxaphene profiles in soils and air showed depletion of Parlar 39 and 42 which suggests that soil is the source to the atmosphere. Endosulfan was undergoing net deposition at most sites as it is a currently used pesticide. Other OCs showed wide variability in fugacity, suggesting a mix of net deposition and volatilization.
authors.affiliation: Centre for Atmospheric Research Experiments, Science and Technology Branch, Environment Canada, 6248 Eighth Line, Egbert, Ontario L01 1N0, Canada.
authors.forename: Fiona
authors.initials: F
authors.lastname: Wong
authors.forename: Henry A
authors.initials: HA
authors.lastname: Alegria
authors.forename: Terry F
authors.initials: TF
authors.lastname: Bidleman
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D008800:Mexico; D010575:Pesticides / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D014835:Volatilization
chemical_list: D000393:Air Pollutants; D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D012989:Soil Pollutants