Microbial degradation pathways of the herbicide dichlobenil in soils with different history of dichlobenil-exposure

Environ Pollut. 2007 Jul;148(1):343-51. doi: 10.1016/j.envpol.2006.10.028. Epub 2007 Jan 18.

Abstract

This is the first detailed study of metabolite production during degradation of the herbicide 2,6-dichlorobenzonitrile (dichlobenil). Degradation of dichlobenil and three potential metabolites: 2,6-dichlorobenzamide (BAM), 2,6-dichlorobenzoic acid (2,6-DCBA) and ortho-chlorobenzamide (OBAM) was studied in soils either previously exposed or not exposed to dichlobenil using a newly developed HPLC method. Dichlobenil was degraded in all four soils; BAM and 2,6-DCBA were only degraded in soils previously exposed to dichlobenil (100% within 35-56 days and 85-100% in 56 days, respectively), and OBAM in all four soils (25-33% removal in 48 days). BAM produced from dichlobenil was either hydrolyzed to 2,6-DCBA or dechlorinated to OBAM, which was further hydrolyzed to ortho-chlorobenzoic acid. BAM was rapidly mineralized in previously exposed soils only. All potential metabolites and the finding that BAM was a dead-end metabolite of dichlobenil in soils not previously exposed to dichlobenil needs to be included in risk assessments of the use of dichlobenil.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agrochemicals*
  • Biodegradation, Environmental
  • Chromatography, High Pressure Liquid / methods
  • Herbicides / chemistry*
  • Nitriles / chemistry*
  • Soil Microbiology*
  • Soil Pollutants / analysis*
  • Soil Pollutants / chemistry

Substances

  • Agrochemicals
  • Herbicides
  • Nitriles
  • Soil Pollutants
  • dichlobanil