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2919271 
Journal Article 
Occurrence and source characterization of perfluorochemicals in an urban watershed 
Nguyen, VT; Reinhard, M; Karina, GY 
2011 
Yes 
Chemosphere
ISSN: 0045-6535
EISSN: 1879-1298 
82 
1277-1285 
English 
Perfluorochemicals (PFCs) are used in numerous applications, mainly as surfactants, and occur ubiquitously in the environment as complex mixtures. This study was undertaken to characterize the occurrence and sources of commonly detected PFC compounds in surface waters of the Marina catchment, a watershed that drains an urbanized section of Singapore. Of the 19 target PFCs, 13 were detected with perfluorooctanoic acid (PFOA) (5-31 ng L(-1)) and perfluorooctane sulfonate (PFOS) (1-156 ng L(-1)) being the dominant components. Other compounds detected included perfluoroalkyl carboxylates (C7-C12) and perfluoroalkyl sulfonates (C6 and C8). Sulfonamide compounds detected 2-(N-ethylperfluorooctanesulfonamido) acetic acid (N-EtFOSAA), 2-(N-methylperfluorooctanesulfonamido) acetic acid (N-MeFOSAA), perfluorooctanesulfonamido acetic acid (FOSAA) and perfluorooctanesulfonamide (FOSA) were putative transformation products of N-EtFOSE and N-MeFOSE, the N-ethylated and N-methylated ethyl alcohol derivatives, respectively. Surface water concentrations were generally higher during dry weather than during storm water flow: the median concentrations of total PFCs in dry and wet weather were 57 and 138 ng L(-1) compared to 42 and 79 ng L(-1), respectively, at Stamford and Alexandra canal, suggesting the presence of a continuous source(s) which is subject to dilution during storm events. In rain water, median concentrations were 6.4 ng L(-1), suggesting rain contributed from 12-25% to the total PFC load for non-point source sites. The longitudinal concentration profile along one of the canals revealed a point source of sulfonated PFCs (PFOS), believed to originate from aqueous film-forming foam (AFFF). Sources were characterized using principal component analysis (PCA) and by plotting PFHxS/PFOA against PFOS/PFOA. Typical surface waters exhibit PFOS/PFOA and PFHxS/PFOA ratios below 0.9 and 0.5, respectively. PCA plots reveal waters impacted by "non-typical" PFC sources in Alexandra canal. 
PFAS
• NMeFOSAA
     Literature Search
          Pubmed
          WOS
     Screening Results
          Excluded/Not on Topic
• ^Per- and Polyfluoroalkyl Substances (PFAS)
     PFHxS (355-46-4)
          Literature search
               Pubmed
               WOS
     PFOSA (754-91-6)
          Literature Search
               Pubmed
               WOS
     NMeFOSAA (2355-31-9)
          Literature Search
               Pubmed
               WOS
• PFHxS
     Literature Search
          PubMed
          WOS
     Screening Results
          Excluded/Not on Topic
     Title and Abstract Screening
          Excluded
               Not relevant to PECO
• PFOSA
     Literature Search
          Pubmed
          WOS
     Screening Results
          Excluded/Not on Topic