酸性农田土壤镉污染修复钝化材料筛选研究

Screening of Passivating Materials for Remediation of Cadmium Pollution in Acid Farmland Soil

【目的】研究0.3 mg kg^(−1)、1.0 mg kg^(−1)、1.5 mg kg^(−1)三种不同镉污染水平的酸性农田土壤单一或复配添加海泡石(H)、膨润土(P)、钙镁磷肥(G)、磷矿粉(L)四种钝化剂钝化镉污染的效果。【方法】采用室内培养模拟实验,添加单一纯化剂处理于开始培养后10 d、20 d、30 d,复配添加钝化剂处理于开始培养后30 d,取样测定土壤pH、有效态镉含量评价添加钝化剂对土壤镉钝化效果。【结果】三种镉污染土壤pH值添加H和G钝化剂后升高(P<0.05)而添加P和L钝化剂变化不明显;与CK相比,0.3 mg kg^(−1)镉含量土壤单一添加4种钝化剂后有效镉含量降低但差异不显著(P>0.05);1.0 mg kg^(−1)镉含量土壤,单一添加H、G钝化剂有效镉含量明显下降而单一添加P、L钝化剂有效镉含量变化不显著(P>0.05);复配添加2%H、1%G钝化剂,土壤有效态镉降低52.73%,效果最好;1.5 mg kg^(−1)镉污染土壤,单一添加H、G钝化剂有效镉含量显著下降,单一添加P、L钝化剂的有效镉含量下降不显著(P>0.05),而复配添加1.5%H和1%G钝化剂处理土壤有效态镉降低了56.45%,效果良好。【结论】建议对0.3 mg kg^(−1)镉含量土壤不进行钝化修复,对1.0 mg kg^(−1)和1.5 mg kg^(−1)镉含量土壤分别推荐使用复配添加2%H、1%G和1.5%H、1%G钝化剂进行修复。

[Objective]The effects of sepiolite(H),bentonite(P),calcium magnesium phosphate fertilizer(G)and phosphate rock powder(L)on cadmium(Cd)pollution in acidic farmland soils with 0.3 mg kg^(−1),1.0 mg kg^(−1) and 1.5 mg kg^(−1) Cd levels were studied.[Methods]The experiment was simulated by indoor culture.Samples were taken at 10 d,20 d and 30 d after culture with the single purified agent,and samples were taken at 30 d after culture with the compound passivating agent.Then,soil pH and available cadmium content were measured to evaluate the effect of passivating agent.[Result]The pH values in the three Cd contaminated soils increased with H and G passivators(P<0.05),while the pH values did not change significantly with P and L passivators.Compared with CK,the effective Cd content in 0.3 mg kg^(−1) Cd contaminated soil with four passivators was decreased,but the difference was not significant(P>0.05).In soil with 1.0 mg kg^(−1) Cd addition,the effective Cd contents of H and G passivating agents decreased significantly,but the effective Cd contents of P and L passivating agents did not change significantly(P>0.05).In addition,2%H+1%G passivators reduced soil available Cd by 52.73%,with the best effect.In 1.5 mg kg^(−1) Cd contaminated soil,the effective Cd contents were significantly decreased by H and G passivator alone,while the effective Cd contents were not significantly decreased by P and L passivator alone(P>0.05).However,the effective Cd content in soil treated by 1.5%H+1%G passivators combined was reduced by 56.45%,showing a good effect.[Conclusion]it is recommended that the 2%H+1%G and 1.5 H+1%G passivating agents were used to passivate 1.0 mg kg^(−1) and 1.5 mg kg^(−1) Cd contaminated soils.