Perfluorinated acid isomer profiling in water and quantitative assessment of manufacturing source.
ABSTRACT A method for isomer profiling of perfluorinated compounds (PFCs) in water was developed and applied to quantitatively assess the contributions from electrochemical (ECF) and telomer manufacturing processes around source regions of North America, Asia, and Europe. With the exception of 3 sites in Japan, over 80% of total perfluorooctanoate (PFOA, C(7)F(15)COO(-)) was from ECF, with the balance attributable to strictly linear (presumably telomer) manufacturing source(s). Comparing PFOA isomer profiles in samples from China, with PFOA obtained from a local Chinese manufacturer, indicated <3% difference in overall branched isomer content; thus, exclusive contribution from local ECF production cannot be ruled out. In Tokyo Bay, ECF, linear-telomer, and isopropyl-telomer sources contributed to 33%, 53%, and 14% of total PFOA, respectively. Perfluorooctane sulfonate (PFOS, C(8)F(17)SO(3)(-)) isomer profiles were enriched in branched content (i.e., >50% branched) in the Mississippi River but in all other locations were similar or only slightly enriched in branched content relative to historical ECF PFOS. Isomer profiles of other PFCs are also reported. Overall, these data suggest that, with the exception of Tokyo Bay, ECF manufacturing has contributed to the bulk of contamination around these source regions, but other sources are significant, and remote sites should be monitored.
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ABSTRACT: Perfluorooctane sulfonate (PFOS) recently has received much attention due to its global distribution, environmental persistence and bioaccumulation. The methods for PFOS decomposition are very limited due to its inertness. In this report we first found the photodecomposition of PFOS under UV was greatly accelerated by addition of ferric ions. In the presence of ferric ion (100μM), PFOS (20μM) decreased to below the detection limit within 48h, with the rate constant of 1.67d(-1), which was 50 times higher than that by direct photolysis (0.033d(-1)). Besides fluoride and sulfate ions, C2-C8 perfluorocarboxylic acids (PFCAs) were identified as the main intermediates. It was found that addition of PFOS into the FeCl3 aqueous solution led to reduction of UV absorption, and the presence of ferric ion reduced the response of PFOS as analyzed by UPLC-MS/MS, which indicated that PFOS formed a complex with ferric ion. The ESR detection indicated that the electronic state of Fe(3+)-PFOS complex changed during reaction. And the role of oxygen and hydroxyl radical on the defluorination of PFOS was investigated. Accordingly the mechanism for PFOS photodecomposition in the presence of ferric ion was proposed.Journal of hazardous materials 02/2014; 271C:9-15. · 4.33 Impact Factor
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ABSTRACT: A total of 100 serum samples from 50 new couples (none of the females in this study has ever been pregnant) in Tianjin, North China, were analyzed for eleven perfluoroalkyl acids (PFAAs) with isomer-specific method. Among all samples, total perfluorooctanesulfonate (∑PFOS, mean 11.3ng/mL) was predominant followed by total perfluorooctanoate (∑PFOA, 2.95ng/mL), perfluorodecanoate (PFDA, 1.17ng/mL), perfluorononanoate (PFNA, 0.93ng/mL) and perfluorohexanesulfonate (PFHxS, 0.67ng/mL). The mean concentrations of ∑PFOS and PFHxS in males (14.2 and 0.89ng/mL) were significantly higher (p=0.001) than in females (8.36 and 0.45ng/mL). No statistical difference between genders was observed for the other PFAAs. This suggests that menstruation is one important elimination pathway for ∑PFOS and PFHxS in females. Linear PFOA was the dominant isomer with mean proportion of 99.7%, suggesting that telomeric PFOA (and its precursors), which contains almost pure linear isomer, might be the dominant exposure source of PFOA in Tianjin. On average, the proportion of linear PFOS (n-PFOS) was 59.2% of ∑PFOS, which was lower than that in technical PFOS products (ca. 70% linear). Except perfluoroisopropyl PFOS, all the other monomethyl branched PFOS isomers were enriched in human serum compared to the commercial products, suggesting the monomethyl branched PFOS precursors were preferentially biotransformed in humans.Environment international 04/2014; 68C:185-191. · 6.25 Impact Factor
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ABSTRACT: Per- and poly-fluoroalkyl substances (PFASs) have been widely detected in the hydrosphere. The knowledge on the distribution and composition patterns of PFAS analogues with different chain length significantly contribute to their source analysis. In the present study, a regional scale investigation of PFASs in surface river waters and adjacent ground waters was carried out in two cities of China with potential contamination, Tianjin and Weifang. A total of 31 water samples were collected, and 20 PFASs therein were measured by a high-performance liquid chromatograph-tandem mass spectrometer (HPLC-MS/MS). The possible sources of PFASs in the aquatic environment were assessed primarily by concentration patterns as well as hierarchical cluster analysis. In all 4 rivers investigated in the two cities, perfluoroalkyl carboxylic acids (PFCAs) were the dominant compounds contributing over 70% of the PFASs detected. Perfluorooctanoic acid (PFOA) was the dominant PFCA with a concentration range of 8.58-20.3ng/L in Tianjin and 6.37-25.9ng/L in Weifang, respectively. On the average, the highest concentration was observed in samples from Dagu Drainage Canal (Dagu) in Tianjin and those short-chain PFASs (C4-C6) was detected with a comparable level of the longer-chain PFASs (>C6). Specifically, perfluorobutanoic acid (PFBA) was dominant in the short-chain analogues. This indicates that a remarkably increasing input of short-chain PFASs might be related to wastewater treatment plant effluent or industrial discharges, which could be possibly due to the switch of manufacturing to short-chain products. In Weifang, precipitation and subsequent surface runoff as non-point sources could be significant inputs of PFASs into surface water while groundwater was possibly subjected to severe point sources with ∑PFASs concentration up to ~100ng/L. The inconsistent distribution patterns in groundwater suggest complicated pathways of contamination.Ecotoxicology and Environmental Safety 08/2014; 108C:318-328. · 2.48 Impact Factor