Uptake of Cd, Zn and Pb by two susceptible plants under mono-and multiple-contamination conditions
单一与复合污染条件下两种敏感性植物对Cd、Zn、Pb的吸收效应

To further understand heavy metal behaviors in soil and interaction effect on plant uptake, a pot experiment in an orthogonal experiment design with cadmium (Cd), zinc (Zn) and lead (Pb) under mono- and multiple contamination conditions was carried out based on the experiments of sensitivity to heavy metals. Two susceptible plants, Medicago sativa and Elymus dahurian Turuz were tested. Biomass and absorption to three heavy metals: lead, cadmium and zinc was first tested in mono-contamination conditions, and then multiple-contamination of different ratio. Biomass of two plants was analyzed, and connection between biomass of shoot and heavy metal concentrations was got. Uptake of heavy metal in mono-polluted environment was analyzed, and absorption equation was got. The result showed that, under mono-contamination conditions, cadmium inhibited the growth of Medicago sativa more than zinc and lead, and lead inhibited the growth of Elymus dahurian turuz more than cadmium and zinc. The uptake of Medicago sativa to cadmium was notably higher than Elymus dahurian turuz, with the highest concentration of cadmium in Medicago sativa reaching 789.06 mg/kg. The uptake Elymus dahurian turuz of to lead was notably higher than Medicago sativa, with the highest concentration of lead in Elymus dahurian turuz reaching 1345.5mg/kg. Under the mono-contamination conditions, the uptake of the two plants to heavy metals was connected with the square and quality of heavy metal concentration in the environment. Coefficients in the equations were connected with the sensitivity of plants to heavy metals and environmental conditions. Under the multi-contamination conditions, synergistic effect and antagonistic effect between lead/zinc and lead/cadmium was respectively observed in the terms of uptake in different range of concentration; antagonistic effect between cadmium and zinc was observed in the terms of uptake in all of the range of concentration. The influence of combined effect was connected with the sensitivity of plants to different heavy metals, ratio of heavy metal concentrations and environmental conditions. It was found that the change of absorption of the two plants to heavy metals was different. Exact connection between the change and the sensitivity was not found, however. The result may help in the further research of the soil environment chemical behavior of heavy metals, the synthesis toxicity of heavy metals to plants and the uptake heavy metals by different plants.