Comparative study of microbial dechlorination of chlorinated ethenes in an aquifer and a clayey aquitard

Mio Takeuchi, Yoshishige Kawabe, Eiji Watanabe, Toshio Oiwa, Manabu Takahashi, Kenji Nanba, Yoichi Kamagata, Satoshi Hanada, Yoshihisa Ohko, Takeshi Komai

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


In order to determine whether natural attenuation of chlorinated ethenes by microbial activity occurs in aquitards, sediments at a site contaminated with tetrachloroethene were vertically studied by drilling. The distribution of microbes (Dehalococcoides group and anaerobic hydrogen producers) and the ability of the sediments to sustain microbial dechlorination were determined in an aquitard as well as in an aquifer. Close-spaced sampling revealed the existence of large populations of Dehalococcoides and H2-producing bacteria, especially in the organic-rich clayey aquitard rather than in the aquifer. The vinyl chloride reductase gene was also detected in the clay layer. Furthermore, incubation experiments indicated that the clay sediment could sustain transformations of tetrachloroethene at least to vinyl chloride. In contrast, no significant transformation was observed in the aquifer sand. Our results indicate that dechlorination of tetrachloroethene by bacteria can take place in an organic-rich clayey aquitard, and that organic-rich clay may also be important in the natural attenuation in an adjacent aquifer, possibly supplying a carbon source or an electron donor.

Original languageEnglish
Pages (from-to)14-24
Number of pages11
JournalJournal of Contaminant Hydrology
Issue number1-4
Publication statusPublished - 2011 Jun 1
Externally publishedYes


  • Aquitard
  • Chlorinated ethenes
  • Clay
  • Dehalococcoides
  • Natural attenuation
  • Pore size distribution

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology


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