| Abstract
| - Compound-specific isotope analysis was used to monitor the δ13C signature of chloroform produced upon the chlorinationof model compounds representing natural organic matter functionalgroups (resorcinol, acetylacetone, acetophenone, phenol, and 2,4,6-trichlorophenol)and a natural water sample. For each model compound, a different apparentkinetic isotope effect was found for chloroform formation. Normalisotope effects were found for resorcinol, acetylacetone, and acetophenone,and ranged from 1.009 ± 0.002 to 1.024 ± 0.004. For thetwo phenols, an inverse effect was found (0.980 ± 0.004). LakeZürich water also had a inverse effect (0.997 ± <0.001)indicating that phenols are likely chloroform precursors in NOM, butthat other functional groups may also participate. The apparent 13C kinetic isotope effect for the addition/elimination reactionof 1,1,1-trichloropropanone mediated by OH− to yieldchloroform is 1.014 ± 0.002. A comparison of this value to thosefound for the chlorination of the model precursors and an evaluationof the differences in chloroform production kinetics for the differentmodel precursors argue against a mechanism in which all NOM precursorsreact via a common intermediate. Compound specific isotope analysismay give additional insights into chloroform formation mechanismsbeyond those allowed by current techniques.
- The apparent kinetic isotope effect and δ13C signature of chloroform, produced upon chlorination of NOM modelcompounds, are used to gain insight into chloroform formation.
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