Altitudinal transect of atmospheric and aqueous fluorinated organic compounds in Western Canada.

Neutral perfluorinated alkyl substances (PFASs), which are thought to be volatile precursors of environmentally ubiquitous perfluorocarboxylates (PFCAs) and perfluorooctanesulfonate (PFOS), were quantified in XAD-2 resin based passive air samplers deployed along an altitudinal transect from 800 to 2740 m above sea level (asl) in Western Canada (based at N51degrees 20' W117degrees 00') over the spring and summer seasons of 2004. The amounts of fluorotelomer alcohols (FTOHs) and perfluorinated sulfonamido alcohols (FOSEs) sequestered in the samplers increased with altitude, being lowest at an elevation of 1300 m asl and highest at either the 2340 or the 2740 m asl sites. A variety of potential reasons for these gradients are discussed, including changes in sampler uptake kinetics and phase capacity caused by changes in atmospheric pressure,temperature, and wind speed. Vapor phase concentrations were estimated to range from 3.7 to 19 pg m(-3) for perfluorinated sulfonamides (FOSAs) and from below detection limits (25 pg m(-3)) to 88 pg m(-3) for FOSEs. Over a similar altitudinal range (800-2350 m asl), 9 L lake water samples were collected in stainless steel cans, extracted with solid phase extraction columns, and analyzed for PFCAs and PFOS. Aqueous concentrations in lake water, ranging from 0.07 to 1.0 ng L(-1) for single PFCAs and from 0.04 to 0.1 ng L(-1) for PFOS, were more constant with altitude and were not correlated with the amount of the precursor compounds in the atmosphere. The relative abundance of FTOHs in air and PFCAs in water supports atmospheric FTOH degradation as the source of PFCAs in the mountain lakes.