SPATIAL AND TEMPORAL PATTERNS OF ORGANIC CONTAMINANTS IN WET PRECIPITATION IN ATLANTIC CANADA

Wet precipitation samples were collected on a monthly basis from three locations in Atlantic Canada for the period 1980-1989 and analyzed for organochlorine pesticides, total polychlorinated biphenyls (PCBs), chlorinated benzenes, and polynuclear aromatic hydrocarbons (PAHs). The compounds most commonly detected included the pesticide lindane (gamma-HCH) and its decomposition product alpha-HCH, fluoranthene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, and PCBs. Statistical analysis of alpha-HCH and gamma-HCH data indicated a significant decrease in concentration of these compounds after 1983, probably the result of curtailing the agricultural use of lindane in North America and on other continents. Seasonal patterns were observed with maximum concentrations/loadings occurring during the spring and fall. Fluoranthene was the dominant PAH compound and was detected in almost every sample. Fluoranthene and other PAHs were shown to follow seasonal patterns, with increasing concentrations during the colder months of the year (December to April). Spatial influences were also observed, indicating both localized and long-range atmospheric source inputs. Abnormally high annual mean concentrations of PCBs ranging between nondetectable levels and 0.220-mu-g/L were measured during the 1981-1986 period at the Prince Edward Island station. Spatial variations for PCBs in the Atlantic Region were significant and attributed in part to localized source inputs. Seasonal patterns similar to the PAHs were also observed. Concentrations dropped to nondetectable levels after 1984 at all sites with the exception of a few sporadic observations.