土壤调理剂对酸性土壤中铅赋存形态及其钝化效果的影响

Effects of soil amendment agents on lead speciation and passivation in weak acid soils

    摘要
  • 摘要: 为明确不同土壤调理剂对酸性土壤中铅（Pb）赋存形态及其钝化效果的影响，本研究以受Pb污染弱酸性耕地土壤为材料，采用盆栽实验，添加石灰粉、白云石粉、牡蛎壳粉、泥炭土、硅钙镁钾肥等5种调理剂，监测了试验后60 d土壤中5种赋存形态Pb含量与土壤pH的变化，分析其钝化土壤中Pb污染的效果。结果显示，土壤中5种赋存形态Pb以可还原态、残渣态Pb为主，其后依次为弱酸提取态、可氧化态和水溶态Pb。添加石灰粉、白云石粉、牡蛎壳粉、泥炭土、硅钙镁钾肥试验后60 d，与CK相比，土壤pH分别提高了1.81、1.49、1.17、0.48和0.60个单位（P<0.05）；水溶态分布系数分别显著降低了92.5%、92.5%、90.0%、57.5%和37.5%，弱酸提取态Pb分布系数分别降低了87.2%、73.7%、77.3%、26.7%和44.9%，可氧化态Pb分布系数分别提高了7.63%、7.90%、17.2%、40.1%和31.9%；而可还原态和残渣态Pb分布系数除了泥炭土与CK差异不显著外，其它处理均有不同程度的提高。土壤pH与其钝化效果具有抛物线型变化关系，相关系数（r）为0.9735（P<0.01）。 5种调理剂具有降低土壤中有效态Pb，并提高潜在有效态和不可利用态Pb的作用；钝化土壤中Pb污染的效果分别为87.2%、73.6%、77.3%、26.7%和44.9%。应用这5种调理剂及适宜施用量，钝化修复酸性土壤中Pb污染是一种有效可行的安全利用技术措施，值得在进一步大田试验验证后进行示范推广。

     

    Abstract: To investigate the influence of different soil amendments on the fractionation and passivation of lead (Pb) in acidic soils, a pot experiment was conducted using Pb-contaminated weak acid soil. Five amendments, namely lime powder, dolomite powder, oyster shell powder, peat soil, and silicate-calcium-magnesium-potassium fertilizer, were applied to the soil. The changes in the content of five Pb fractions (water-soluble, weakly acid-extractable, reducible, oxidizable, and residual) and soil pH were monitored 60 d after the application of amendments, and their passivation effects on Pb pollution were analysed. The dominant Pb fractions in the soil are reducible and residual Pb, followed by weak acid-extractable, oxidizable, and water-soluble Pb. At 60 d after the experiment, the application of lime powder, dolomite powder, oyster shell powder, peat soil, and silicate-calcium-magnesium-potassium fertilizer increases the soil pH by 1.81, 1.49, 1.17, 0.48, and 0.60 units, respectively (P<0.05). The distribution coefficient of water-soluble Pb is decreased by 92.5%、92.5%、90.0%、57.5% and 37.5%, while weak acid-extractable Pb is decreased by 87.2%、73.7%、77.3%、26.7% and 44.9%, respectively. Oxidizable Pb is increased by 7.63%、7.90%、17.2%、40.1% and 31.9%, respectively (P<0.05). Except for peat soil treatment, reducible Pb and residual Pb are all significantly increased in all treatments compared with the control. A parabolic relationship is found between soil pH and the passivation effect, with a correlation coefficient (r) of 0.9735 (P<0.01). The amendments effectively reduce the bioavailable Pb fractions and increase the potentially available and unavailable Pb fractions in the soil. The passivation effect on Pb pollution is 87.2%, 73.6%, 77.3%, 26.7%, and 44.9% for lime powder, dolomite powder, oyster shell powder, peat soil, and silicate-calcium-magnesium-potassium fertilizer, respectively. The application of these five amendments at suitable application rates is an effective and feasible approach to the safe utilization and remediation of Pb-contaminated acid soils. It is worthy of demonstration and extension after further validation through additional field trials

     

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