氧化钙改性坡缕石对水稻土中Cd污染的钝化效果研究

在钝化实验和盆栽实验中利用土壤理化性质、Cd形态分布、有效态Cd、以及玉米幼苗生长等因素来分析5种比例氧化钙改性坡缕石（1∶1、2∶1、3∶1、4∶1和5∶1，质量比）的施加对水稻土中Cd污染的钝化效果。结果表明:氧化钙改性坡缕石可以显著提高土壤pH、阳离子交换量和电导率。与对照相比，5种氧化钙改性坡缕石使DTPA提取态、TCLP提取态、酸溶态Cd含量分别降低了3.44% ~ 23.3%、4.12% ~ 30.7%、2.30% ~ 21.8%。添加氧化钙改性坡缕石对玉米的生长起到了明显的促进作用，玉米的茎长、根长、鲜重和干重分别升高了2.04% ~ 17.7%、4.66% ~ 25.1%、7.62% ~ 39.4%和0.70% ~ 26.1%；玉米地上部分和地下部分Cd的含量分别降低了5.17% ~ 27.3%和4.62% ~ 22.7%。可见，氧化钙改性坡缕石钝化材料对Cd的钝化效果优于未改性坡缕石材料，其中以坡缕石与氧化钙的添加量为3∶1时效果最佳。

Passivation Effects of Palygorskite Modified by CaO on Cd Contamination in Paddy Soil

In the passivation experiment and pot experiment, the passivation effect of calcium oxide modified palygorskite (1∶1, 2∶1, 3∶1, 4∶1 and 5∶1, mass ratio) on Cd pollution in paddy soil was analyzed by using soil physical and chemical properties, Cd form distribution, available Cd and corn seedling growth. The results showed that calcium oxide modified palygorskite significantly improved soil pH, cation exchange capacity and electrical conductivity. Compared with the control, the contents of Cd in DTPA extracted, TCLP extracted and acid soluble fractions decreased by 3.44%-23.3%, 4.12%-30.7% and 2.30%-21.8%, respectively. The stem length, root length, fresh weight and dry weight of corn increased by 2.04%-17.7%, 4.66%-25.1%, 7.62%-39.4% and 0.70%-26.1%, respectively; The contents of Cd in the aboveground and underground parts of corn decreased by 5.17%-27.3% and 4.62%-22.7%, respectively. It can be seen that the passivation effect of calcium oxide modified palygorskite on Cd was better than that of unmodified palygorskite, and the addition of palygorskite and calcium oxide at ratio og 3∶1 showed the most significant effect.