Biodegradation behavior of perchlorate in soils and sediments

Degradation behavior and the effects of nitrate and sulfate of perchlorate (ClO₄^-) in soils and sediments of natural environments were investigated. The lag time of both ClO₄^- and NO₃^- degradation was site-specific and depended on the environmental conditions such as content of organic substrate, nitrate concentration, initial ClO₄^- concentration and prior ClO₄^- exposure. The lag time of ClO₄^- degradation at an initial concentration of 5 mg·L^-1 ranges from 1.5 to 34 days, depending on environmental conditions mentioned above, and its rate constant ranges from 0.003d^-1 ~ 0.094 d^-1. While the lag time of NO₃^- degradation ranges from 0.5 to 16 days, and its rate constant ranges from 0.017 d^-1 ~ 0.179 d^-1, indicating that NO₃^- degradation rate is relatively higher than that of ClO₄^-. Nitrate does prolong the lag time of v degradation, which may account for the persistence of ClO₄^- in the environment. The results show that microorganism can degrade ClO₄^- in sediments and soils, and the degradation efficiency is influenced by the availability of organic substrate.