[Effects of several low-molecular-weight organic acids on the release kinetic of DDTs from red soil]

The kinetic release behavior of DDTs from red soil with three kinds of low-molecular-weight (LMW) organic acids solution and water leaching was investigated by kinetic device designed. The results show that the release percentage of DDTs from red soil by LMW organic acid can increase by 15% - 18% more than that by water, especially for the initial 250 mL leaching solution. When using water as leaching solution, the data of release kinetics of DDTs from red soil conformed to the apparently first dynamics equation (R2 > 0.99, p < 0.000 1), it implied that the surface diffuse of soil mineral is primary release mechanism of DDTs from red soil in water leaching system. The kinetic release behavior of DDTs in LMW organic acid leaching system can be described by parabola diffuse equation, double constant equation or Elovich equation. It implied that the LMW organic acids induced the complication of the release mechanisms of DDTs from red soil, this maybe related to the dissolution of soil mineral surface and structure change of inherent organic material that coating onto the soil mineral surface induced by LMW organic acid.