四种改良剂对铜和镉复合污染土壤的田间原位修复研究

研究了石灰、磷灰石、蒙脱石和凹凸棒石对冶炼厂周边Cu、Cd污染土壤的原位修复效果。以黑麦草(Lolium perenne L.)作为田间修复植物,采用植物重金属吸收性、土壤重金属化学提取性及土壤溶液重金属浓度变化等作指标来评价修复效果,并研究了黑麦草对Cu、Cd的吸收与土壤、土壤溶液中Cu、Cd含量的相关性。结果表明,石灰高添加剂量(石灰占污染土壤耕作层质量的0.4%)处理黑麦草对重金属的富集效果最好,显著降低了重金属毒性,促进了黑麦草的生长及其对重金属的富集;石灰和磷灰石各添加剂量均显著降低了污染土壤交换态Cu含量;石灰、磷灰石和蒙脱石各添加剂量均显著提高了土壤溶液pH并显著降低了其Cu、Cd浓度。黑麦草地上部、根中Cu浓度与土壤交换态Cu及土壤溶液Cu浓度呈显著或极显著正相关关系。

Field in-situ remediation of Cu-Cd polluted soil by four amendments

Effects of four amendments, i.e. lime, apatite, montmorillonite and attapulgite, in in-situ remediation of Cu-Cd contaminated soil nearby a copper smelter were studied. Ryegrass (Lolium perenne L.) was planted in the experiment. Plant absorbability, chemical extractability and concentrations in soil solution of Cu and Cd were cited as indices for evaluation of remediation effect of the amendments. Besides, correlations of contents of exchangeable Cu and Cd in soil and in soil solution with Cu and Cd uptake by ryegrass were also studied. Results show that in treatment of lime at a high dosage (0.4% of the polluted soil of the plow layer), ryegrass showed the best effect in enriching Cu-Cd. Lime significantly lower toxicity of the heavy metals and promoted growth and Cu-Cd bioaccumulation of ryegrass. Amendment of lime and apatite, in all the rate treatments, significantly decreased exchangeability of Cu in the soil; Amendment of lime, apatite and montmorillonite, in all the rate treatments, increased pH of and decreased Cu and Cd concentrations in the soil solution significantly. Cu concentration in the shoots and roots of ryegrass was positively related to soil exchangeable Cu and Cu concentration in soil solution.