Microbial and non-biological decompostion of chlorophenols and phenol in soil
1980
Baker, M.D. | Mayfield, C.I. (Waterloo Univ., Ont. (Canada). Dept. of Biology)
The aerobic and anaerobic degradation of phenol and selected chlorophenols was examined in a clay loam soil containing no added nutrients. A simple, efficient procedure based on the high solubility of these compounds in 95 per cent ethanol was developed for extracting phenol and chlorophenol residues from soil. Analysis of soil extracts with UV spectrophotometry showed that phenol, o-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol and 2,4,6-trichlorophenol were rapidly degraded, while m-chlorophenol, 3,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol were degraded very slowly by microorganisms in aerobically-incubated soil at 23 deg C. Both 3,4,5-trichlorophenol and 2,3,4,5-tetrachlorophenol appeared to be more resistant to degradation by aerobic soil microorgamisms at 23 deg C. None of the compounds examined were degraded by microorganisms in anaerobically-incubated soil at 23 deg C. Direct microscopic observation revealed that phenol and selected chlorophenols stimulated aerobic and to a lesser extent, anaerobic microbial growth in soil, and aerobic soil bacteria were responsible for the degradation of 2,4-dichlorophenol in aerobically-incubated soil at 23 deg C. Phenol, o-chlorophenol, m-chlorophenol, p-chlorophenol and 2,4-dichlorophenol underwent rapid non-biological degradation in sterile silica sand. Non-biological decomposition contributed, perhaps substantially, to the removal of some chlorophenols from sterile aerobically-incubated soil and both sterile and non-sterile anaerobically-incubated soil
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