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Effect of sorption and desorption resistance on aerobic trichloroethylene biodegradation in soils
Author(s) -
Lee Sangjin,
Moe William M.,
Valsaraj Kalliat T.,
Pardue John H.
Publication year - 2002
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620210811
Subject(s) - microcosm , trichloroethylene , biodegradation , environmental chemistry , chemistry , toluene , sorption , reductive dechlorination , soil water , desorption , soil contamination , adsorption , organic chemistry , environmental science , soil science
Biodegradation of trichloroethylene(TCE) by toluene‐degrading bacteria was measured under aerobic conditions in aqueous and soil‐slurry batch microcosms. For soil‐phase experiments, a freshly contaminated soil and a soil containing only the desorption‐resistant fraction of TCE were tested. In both cases, presence of soil resulted in biodegradation rates substantially lower than those determined in the absence of soil. In aqueous‐phase experiments, an appreciable increase in the rate and extent of TCE biodegradation was observed in microcosms when toluene was added multiple times. The TCE degradation rates were clearly correlated with toluene dioxygenase (TOD) enzyme activity over time, thus providing an indication of the cometabolic pathway employed by the microbial population. In soil‐slurry experiments containing freshly contaminated soil, a TCE degradation rate of approximately 150 μg TCE/kg/h was observed during the first 39‐h period, and then the TCE degradation rate slowed considerably to 0.59 and 0.84 μg TCE/kg/h for microcosms receiving one and two additions of toluene, respectively. The TCE degradation rates in soil‐slurry microcosms containing the desorption‐resistant fraction of TCE‐contaminated soil were approximately 0.27 and 0.32 μg TCE/kg/h in microcosms receiving one and two additions of toluene, respectively. It is clear from these results that mass transfer into the aqueous phase limited bioavailability of TCE in the contaminated soil.