Dechlorination of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid in soil

The potential for dechlorinating 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in selected soils with a mixed culture showing stable dechlorinating activity was investigated. Intermediate 2,4,5-T dechlorination products were identified as 2,5-D and 3-CP, while the intermediate 2,4-D dechlorination product was identified as 4-CP. Dechlorination occurred at a faster rate in Shulin clay loam compared to Guishan sandy loam and dechlorination occurred faster for 2,4-D than 2,4,5-T. However, the differences in dechlorination rates of either compound are not significant in either of the two soil types. We found optimal dechlorination conditions for the two compounds to be a temperature of 30°C at pH 8.0 and 100% water content. With the simultaneous presence of 2,4-D and 2,4,5-T, dechlorination rates for both compounds were slower. We also found that the addition of chlorophenolic compounds inhibited dechlorination of both 2,4-D and 2,4,5-T.