五种钝化剂施用水平对稻田镉污染土壤的修复效果研究

Study on the remediation effect of five passirator application levels on cadmium contaminated soil in paddy fields

筛选高效价廉的土壤重金属钝化剂是农田重金属污染防控的关键。在大田试验条件下,研究了5种钝化剂(石灰+沸石、凹凸棒土、硅-钙钝化剂、硅-钙-铝钝化剂、硅-钙-镁钝化剂)在不同添加量的情况下对稻田土壤镉(Cd)的钝化效果以及对水稻中镉含量的影响。结果表明,5种钝化剂均能提高土壤pH,其中石灰+沸石处理对土壤pH影响最大。硅-钙钝化剂处理的稻田土壤有效态镉含量最低,最大降幅为15.9%。当硅-钙钝化剂、凹土、石灰+沸石3种钝化剂的添加量为4500 kg/hm2时,所有处理糙米样品镉含量均达到GB 2762—2017安全标准,可安全食用。硅-钙钝化剂对该镉污染水田具有较好的钝化效果,能改善土壤理化性质并促进作物生长,可作为镉污染水田的安全利用措施。

Screening of soil passivators with high efficiency and low cost is of great significance in remediation of heavy metal polluted farmland soils.The effects of five typical passivators,i.e.,lime-zeolite mortars,palygorskite,passivator of silicon-calcium,passiv⁃ator of silicon-calcium-aluminium and passivator of silicon-calcium-magnesium at difference additions,on cadmium content in pad⁃dy soil and rice grain were investigated in this field experiment.The results showed that soil pH was increased by several passivators,of which the lime-zeolite treatment had the greatest effect on soil pH.The paddy soil with passivator of silicon-calcium had the lowest available cadmium content,and the maximum reduction rate was 15.9%.The Cd content in brown rice was significantly reduced by passivator of silicon-calcium,attapulgite and lime-zeolite at the dosage of 4500 kg/hm2,reaching the National Standard GB 2762—2017,and the rice was qualified for eating.Considering the beneficial effect of passivator of silicon-calcium on soil physical and chem⁃ical properties and crop growth,passivator of silicon-calcium could be used as an efficient precaution for safe utilization of cadmium contaminated paddy fields.