Monitoring of Trace Organic Contaminants in Atmospheric Precipitation

Abstract

The design and use of a year-round sampler for trace organic contaminants in wet precipitation are described. The sampler is electronically controlled and features a 0.25-meter-square stainless steel funnel with a 4-L amber glass bottle. The whole assembly is insulated and equipped with heating elements which permit collection of ice/snow samples. The samples are preserved in situ with methylene chloride and extracted again with methylene chloride in the laboratory. A small network of four sampling stations was established in the Great Lakes basin for the purpose of obtaining a refined estimate of atmospheric loading of trace organic pollutants to the Great Lakes. A total of 93 rain/snow samples was collected from the network during 1986. These samples were analyzed for organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. The most significant organochlorine pesticides found were alpha-HCH, gamma-HCH (lindane), and methoxychlor with concentrations in the range of 7–10 ng/L, 4–5 ng/L, and 2–7 ng/L, respectively. Other organochlorinated pesticides were measured occasionally at sub-nanogram levels. Polychlorinated biphenyls were also widely detected with mean concentrations of 7–10 ng/L. Polycyclic aromatic hydrocarbons were detected in about 50% of the samples. Some of the prevalent polycyclic aromatic hydrocarbons were phenanthrene, methylnapthalene, fluoranthene, and pyrene with mean concentrations of 50–200 ng/L. Deposition of agricultural chemicals (HCHs) was higher in Lake Superior and Huron but precipitation at Lake Erie and Lake Ontario contained more varieties of domestic pesticides.