[Effects of dissolved organic matter in landfill leachate on soil Cd- and Pb bioavailability]

A pot experiment was conducted to study the effects of dissolved organic matter (DOM) in landfill leachate on ryegrass growth and its uptake of soil Cd and Pb. Fresh sample and Shuige leachate were collected from the municipal waste landfills established 0 and 12 years, respectively. The results showed that after the landfill leachate added, the average concentration of DOM remained in soil was 1.39 (fresh sample) and 1.47 (Shuige) times higher than the control (CK). The bioavailability of Cd and Pb in the soils treated with the two leachates was fluctuated in early period, and then raised. Compared with CK, the bioavailability of soil Cd was increased by 4.81% (fresh sample) and 48.97% (Shuige), and that of soil Pb was enhanced by 7.22% (fresh sample) and 18.99% (Shuige). The total concentrations of plant Cd and Pb in the treatments of fresh sample and Shuige were 19.59% and 104.4%, and 36.03% and 44. 66% higher than CK, respectively, while the total biomass of ryegrass was decreased by 14.03% to approximately 52.24%, in compared with CK. It could be inferred that the dissolved organic matter (DOM) in landfill leachate, especially in that from the landfills established for a longer time, could enhance the bioavailability of soil heavy metals and their accumulation in plant, and thus, suppress the growth of plants.