Poly and perfluorinated carboxylates in North American precipitation.
Although perfluorocarboxylates (PFCAs) have been detected in a number of environmental matrices, there are very few reports on concentrations in precipitation. In this study PFCAs, fluorotelomercarboxylates (FTCAs), and fluorotelomer-unsaturated carboxylates (FTUCAs), were determined in wet only precipitation samples from nine sites in North America. The analytical method involved derivatization of the carboxylates and measurement of the 2,4-difluoroanilide by GC-MS. Samples from three remote sites in Canada had low concentrations of perfluorooctanoate (PFOA) (<0.1-6.1 ng/L). Significantly higher concentrations of PFOA were found at 4 northeastern United States and 2 southern urban Canadian sites, with Delaware having the highest levels (85 ng/L PFOA, with a range of 0.6-89 ng/L) and a maximum flux of 13 000 ng/m2. 8:2- and 10:2 FTCAs and FTUCAs were detected at all 4 U.S. sites and 2 urban Canadian sites (<0.07-8.6 ng/L), most frequently at the Delaware site. Longer chained PFCAs (deca-, undeca-, and dodeca-perfluorocarboxylates) were detected (<0.07-5.2 ng/L) at 2 urban Ontario sites but not determined in other samples. Air mass back trajectory results for 3 U.S. sites indicate highly populated urban areas in the New York to Washington corridor as the main sources of PFOA, although low PFOA levels associated with air masses coming off the Atlantic Ocean imply multiple sources.