title: Long-term atmospheric deposition of current-use and banned pesticides in Atlantic Canada; 1980-2000.
abstract: The occurrence of current-use and banned pesticides is reported in wet-precipitation collected from four sites across Atlantic Canada during the period 1980-2000. The most frequently detected compounds were alpha-HCH, gamma-HCH (lindane), chlorothalonil, pentachlorophenol, atrazine, and endosulfan. Median site concentrations varied between not-detected and 10.2 ng l(-1). Deposition of HCHs (hexachlorocyclohexane), chlorothalonil, and endosulfan at Kejimkujik (Keji) and Jackson, Nova Scotia, were generally similar. Significant spatial differences (p<0.05), however, were found for the HCH isomers and endosulfan at Keji and Gros Morne (Newfoundland and Labrador), areas geographically separated by the northern Gulf of St. Lawrence. Long-term deposition of alpha-HCH decreased (p<0.05) at both Keji (1980-2000) and Gros Morne (1994-2000), with half-lives of 5.9 and 4.5 y, respectively. A decreasing trend was also found for pentachlorophenol with a half-life of 4.9 y at Jackson. Significant negative trends (p<0.05) were observed for alpha-/gamma-HCH ratios during the study at Keji and Jackson, possibly reflecting changes in production and use patterns of technical HCH and lindane on a continental and perhaps hemispheric scale. Seasonal trends for alpha-HCH and gamma-HCH were found to vary over the 20-y study period at Keji, however, spatial trends were generally similar between sites. Seasonal trends were observed with peak deposition generally occurring during the growing period (spring-summer) for the HCHs, chlorothalonil, endosulfan, and atrazine. Bimodal seasonal trends were also observed for these compounds with the exception of endosulfan.
authors.affiliation: Environment Canada, Science and Technology Branch, PO Box 23005, Moncton, New Brunswick, Canada E1A 6S8. guy.brun@ec.gc.ca <guy.brun@ec.gc.ca>
authors.forename: Guy L
authors.initials: GL
authors.lastname: Brun
authors.forename: Ronald M
authors.initials: RM
authors.lastname: MacDonald
authors.forename: Jessica
authors.initials: J
authors.lastname: Verge
authors.forename: Jamie
authors.initials: J
authors.lastname: Aubé
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D001272:Atmosphere; D002170:Canada; D004784:Environmental Monitoring; D005843:Geography; D010575:Pesticides / Q000032:analysis* / Q000737:chemistry; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D010575:Pesticides