调理剂-植物栽培协同降低矿区农田土壤中重金属有效态含量

定量评估重金属有效态含量是明确农田土壤修复过程中重金属生态环境风险的重要步骤。针对硫化物矿区重金属污染土壤开展添加蚕沙-铁粉及蚕沙-伊蒙土-铁粉调理剂条件下油葵、孔雀草、香茅草和桑树4种经济作物的盆栽试验，并测定经济作物与调理剂共同作用下土壤中pH、有机质及镉砷铅锌铜有效态的含量。结果显示作物栽培与调理剂共同作用下，土壤pH值在两季中均有增加，土壤有机质在第一季中增加。第一季种植4种经济作物添加蚕沙-铁粉可显著降低土壤中多种重金属有效态含量，各重金属的最高钝化效率分别为Cd 30.3%、As 49.5%、Pb33.6%、Zn 52.1%、Cu 45.7%，优于蚕沙-伊蒙土-铁粉的调理效果。第二季种植时调理剂的钝化效率普遍降低。两季综合来看，蚕沙-铁粉联合香茅草时有效态镉、砷、铅、锌、铜的降低幅度最大。因此，添加蚕沙-铁粉调理剂的四种作物单季种植时能同时降低镉、砷、铅、锌、铜有效态的含量，香茅草两季种植时能同时降低以上5种重金属有效态含量，具有潜在应用价值。

Reducing the available contents of various heavy metals by synergetic method of amendments and plantation of crops

The quantitative assessment of available contents of various heavy metals is important to identify the ecological risk of heavy metals in remediation process. In this study, pot experiments with four economic crops (sunflower, malachite grass, citronella, and mulberry), respectively, were carried out in heavy metal contaminated soil from sulfide minerals mine in the presence of silkworm-iron powder or silkworm- (illite-smectite interstratified clay minerals)-iron powder. The pH, organic contents, and the available contents of Cd, As, Pb, Zn, and Cu in soil were analyzed under the combination of the selected crops and conditioners. Experimental results showed that pH in soil increased with the treatments of two amendments in two seasons, while organic contents only increased in the first season. The available contents of various heavy metals in soil were significantly reduced when the four crops were planted in the first season with the treatment of silkworm-iron powder, with passivation efficiencies of 30.3% (Cd), 49.5% (As ), 33.6% (Pb ), 52.1% (Zn), and 45.7% (Cu), respectively, which were better than the treatment of illite-smectite interstratified clay minerals. In general, the passivation efficiencies declined in the second season. The largest decrease of available Cd, As, Pb, Zn, and Cu occurred when the combination of silkworm- iron powder and citronella was applied. The available Cd, As, Pb, Zn, and Cu were all reduced under the synergetic treatment of silkworm-iron power with each of the four selected crops in the first season, and with citronella in two seasons, indicating high potential in application.