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3856871 
Journal Article 
Aerobic biotransformation of polyfluoroalkyl phosphate esters (PAPs) in soil 
Liu, C; Liu, J 
2016 
Yes 
Environmental Pollution
ISSN: 0269-7491
EISSN: 1873-6424 
212 
230-237 
English 
Microbial transformation of polyfluoroalkyl phosphate esters (PAPs) into perfluorocarboxylic acids (PFCAs) has recently been confirmed to occur in activated sludge and soil. However, there lacks quantitative information about the half-lives of the PAPs and their significance as the precursors to PFCAs. In the present study, the biotransformation of 6:2 and 8:2 diPAP in aerobic soil was investigated in semi-dynamics reactors using improved sample preparation methods. To develop an efficient extraction method for PAPs, six different extraction solvents were compared, and the phenomenon of solvent-enhanced hydrolysis was investigated. It was found that adding acetic acid could enhance the recoveries of the diPAPs and inhibit undesirable hydrolysis during solvent extraction of soil. However 6:2 and 8:2 monoPAPs, which are the first breakdown products from diPAPs, were found to be unstable in the six solvents tested and quickly hydrolyzed to form fluorotelomer alcohols. Therefore reliable measurement of the monoPAPs from a live soil was not achievable. The apparent DT50 values of 6:2 diPAP and 8:2 diPAP biotransformation were estimated to be 12 and > 1000 days, respectively, using a double first-order in parallel model. At the end of incubation of day 112, the major degradation products of 6:2 diPAP were 5:3 fluorotelomer carboxylic acid (5:3 acid, 9.3% by mole), perfluoropentanoic acid (PFPeA, 6.4%) and perfluorohexanoic acid (PFHxA, 6.0%). The primary product of 8:2 diPAP was perfluorooctanoic acid (PFOA, 2.1%). The approximately linear relationship between the half-lives of eleven polyfluoroalkyl and perfluoroalkyl substances (PFASs, including 6:2 and 8:2 diPAPs) that biotransform in aerobic soils and their molecular weights suggested that the molecular weight is a good indicator of the general stability of low-molecular-weight PFAS-based compounds in aerobic soils. 
PFAS
• 5:3 acid
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• 6:2/8:2 diPAP
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• 6:2 diPAP
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• 8:2 diPAP
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• FtOH 6:2
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• FtOH 8:2
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• ^Per- and Polyfluoroalkyl Substances (PFAS)
     PFOA (335-67-1) and PFOS (1763-23-1)
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     PFHxA (307-24-4)
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     PFPeA (2706-90-3)
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     FtOH 8:2 (678-39-7)
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     FtOH 6:2 (647-42-7)
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     6:2 diPAP (57677-95-9)
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     8:2 diPAP (678-41-1)
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               Pubmed
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     6:2/8:2 diPAP (943913-15-3)
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     5:3 acid (914637-49-3)
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• PFHxA
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     Title and Abstract Screening
          Excluded
               Not relevant to PECO
     Literature Search
          Pubmed
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• PFOA (335-67-1) and PFOS (1763-23-1)
     Literature Search – Adverse outcome pathway (2015-present)
          Pubmed
          WOS
     Screening Results
          Excluded/Not on Topic
     Literature Search Update (2013-2019)
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• PFPeA
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          Pubmed
          WOS
     Screening Results
          Excluded/Not on Topic