[Influence of the interaction between iron oxide and electron donor substances on 1,1,1-trichloro- 2, 2-bis (p-chlorophenyl) ethane ( DDT) reductive dechlorination in hydragric acrisols].

: The interaction between iron oxide and electron donor substance have significant influences on electron transfer and the growth of iron-reducing bacteria, which may affect the reductive dechlorination of polychlorinated organic compounds in soil. Anaerobic soil incubation experiment was conducted to study the effect and its mechanism of iron oxide (goethite), electron donor substances (butyrate and ethanol), and their interaction on DDT reductive dechlorination in Hydragric Acrisols. Results showed that after 6 weeks of anaerobic incubation, the extractable residues of DDT were between 1.29% and 2.01% of initial DDT amounts in soils, which was attributed to the dechlorinated degradation of DDT and formation of bound residues of DDT and its dechlorinated products. The main product of DDT anaerobic dechlorination was 1,1-dichloro-2,2-bis (p-chloro-phenyl) ethane (DDD). During the prophase of incubation, the application of butyrate or ethanol led to the decreased pH and increased Eh for reaction system, thus inhibited DDT dechlorination. The applications of only goethite or goethite and electron donor substances resulted in the increased soil pH, decreased soil Eh and increased Fe( II ) contents, thus accelerated DDT dechlorination. There was no significant interaction between butyrate and iron oxide on DDT dechlorination, whereas there was antagonistic action between ethanol and iron oxide on DDT dechlorination. The results will be of great significance for developing efficient and in-situ remediation technology of DDT contaminated soil.