Remediation of Contaminated Soil with Polychlorinated Organic Pollutants by Ryegrass

Polychlorinated Organic Pollutants (PCOPs) have characteristics of persistence, bioaccumulation, semi-volatility and high toxicity which threaten environment and human's health. In recent years, focus has been on phytoremediation to remove PCOPs in soil. This paper designed soil culture experiment to study the remediation effect of contaminated soil with PCOPs (pp'-DDT,ν-BHC,HCB) by ryegrass and dynamic changes of soil property in rhizosphere. The results showed that after 90 days the content of PCOPs in soil decreased 19.01%～41.75%. The decrease rate of PCOPs was quicker and the capability of absorbing PCOPs by ryegrass was higher at early and middle stages of ryegrass growth (0～60 d) than later stage(60～90 d). With the increase of PCOPs concentration, degradation rate of PCOPs and absorption capability of ryegrass increased. In other words, ryegrass has higher capability of remedying contaminated soil with PCOPs of high concentration than low concentration. For the removal of PCOPs in soil, the function of absorption by ryegrass was very little, and only account for 1.20% ～ 4.72% . The key reason for PCOPs removal from soil was microdegradation. Planting ryegrass can change rhizosphere environment. pH, content of organic matter and catalase activity changed accordingly with ryegrass growth, which has benefit the PCOPs removal from the soil.