Phytoremediation of Soil in the Wastewater Irrigation Area of the Western of Shenyang

The phytoremediation of jointly contaminated farmland soil with Cd and PAHs was studied in the long-term and representative wastewater irrigation area in Northeast China. Black nightshades (Solanum nigrum L), proved to be a Cd-hyperaccumulator was taken to remove the Cd contaminant from soil during one growing seasons in field test and thirteen lawn grasses and pasture grasses were taken to remediate the PAHs in pot experiments. Results showed that the residual concentrations Cd and PAHs were 1.94~3.69 mg/kg (dry weight) and 1.69~2.71 mg/kg (dry weight), respectively, still much higher than the Soil Quality Standard after the stop of wastewater irrigation for more than 20 years. The black nightshades could tolerate and grow well in the jointly contaminated farmland, with the distribution sequence of Cd in the order of leaf> stem> fruit> root, and the removal rate in the high-density black nightshade treatment was 1.40 percent in one growing season, higher than that in the moderate-density treatment and low-density treatment. Alfalfa, rye grass, Balin, tall fescue and white clover were more efficient than others of the tested thirteen grasses for the remediation of PAH-contaminated soil.