title: A North American and global survey of perfluoroalkyl substances in surface soils: Distribution patterns and mode of occurrence.
abstract: The distribution of 32 per/polyfluoroalkyl substances (PFASs) in surface soils was determined at 62 locations representing all continents (North America n = 33, Europe n = 10, Asia n = 6, Africa n = 5, Australia n = 4, South America n = 3 and Antarctica n = 1) using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) systems. Quantifiable levels of perfluoroalkyl carboxylates (PFCAs: PFHxA-PFTeDA) were observed in all samples with total concentrations ranging from 29 to 14,300 pg/g (dry weight), while perfluoroalkane sulfonates (PFSAs: PFHxS, PFOS and PFDS) were detected in all samples but one, ranging from <LOQ-3270 pg/g, confirming the global distribution of PFASs in terrestrial settings. The geometric mean PFCA and PFSA concentrations were observed to be higher in the northern hemisphere (930 and 170 pg/g) compared to the southern hemisphere (190 and 33 pg/g). Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were the most commonly detected analytes at concentrations up to 2670 and 3100 pg/g, respectively. The sum of PFCA homologues of PFOA commonly were roughly twice the concentration of PFOA. The PFCA and PFSA congener profiles were similar amongst most locations, with a few principal-component statistical anomalies suggesting impact from nearby urban and point sources. The ratio of even to odd PFCAs was consistent with the atmospheric oxidation of fluorotelomer-based precursors previously observed in laboratory and environmental studies. Given the soils were collected from locations absent of direct human activity, these results suggest that the atmospheric long-range transport (LRT) of neutral PFASs followed by oxidation and deposition are a significant source of PFCAs and PFSAs to soils.
authors.affiliation: Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
authors.forename: Keegan
authors.initials: K
authors.lastname: Rankin
authors.affiliation: Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Mabury
authors.affiliation: Senior Environmental Employment Program, United States Environmental Protection Agency, 960 College Station Road, Athens, 30605, Georgia.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Jenkins
authors.affiliation: Ecosystems Research Division, National Exposure Research Laboratory, Office of Research and Development, United States Environmental Protection Agency, 960 College Station Road, Athens, 30605, Georgia. Electronic address: washington.john@epa.gov.
authors.forename: John W
authors.initials: JW
authors.lastname: Washington
mesh_terms: D000349:Africa; D017738:Alkanesulfonic Acids / Q000032:analysis*; D000864:Antarctic Regions; D001208:Asia; D001315:Australia; D002210:Caprylates / Q000032:analysis*; D002264:Carboxylic Acids / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D005060:Europe; D005466:Fluorocarbons / Q000032:analysis*; D006801:Humans; D009656:North America; D012987:Soil / Q000737:chemistry* / Q000592:standards; D012989:Soil Pollutants / Q000032:analysis*; D013020:South America; D011795:Surveys and Questionnaires; D053719:Tandem Mass Spectrometry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D017738:Alkanesulfonic Acids; D002210:Caprylates; D002264:Carboxylic Acids; D005466:Fluorocarbons; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; C023036:perfluorooctanoic acid; C076994:perfluorooctane sulfonic acid
keywords: Background soils; PFASs; PFOA; PFOS; Reconnaissance survey