纳米羟基磷灰石修复硫铁矿区镉锌复合污染土壤的效果研究

选取典型硫铁矿区周边受Cd和Zn复合污染黄壤为研究对象,采用淋溶试验和老化试验,探索添加羟基磷灰石对土壤中重金属生物有效性以及形态分布的影响,羟基磷灰石添加比例(w/w)设置为0%(CK)、1%(P1)、3%(P3)和5%(P5)。结果表明:(1)添加羟基磷灰石能够显著提高淋滤液的pH值,明显降低土壤中Cd和Zn淋失量,P1、P3和P5与CK的Cd累积淋失量(120μg)相比可分别降低74.2%、85.0%、92.0%,与CK的Zn累积淋失量(16.7 mg)相比可分别降低79.4%、92.1%、97.9%;(2)添加羟基磷灰石能够显著提高土壤pH值,P1、P3和P5的pH值分别比CK升高了0.64、0.85、1.20个pH单位;(3)添加羟基磷灰石能够显著降低土壤有效态Cd和Zn(0.025 M HCl提取),相较于CK,P1、P3和P5的有效态Cd含量可分别降低74.2%、96.8%、98.4%,有效态Zn含量可分别降低68.1%、96.6%、99.5%;(4)添加羟基磷灰石能够显著降低土壤可交换态和碳酸盐结合态Cd和Zn含量,增加土壤中残渣态Cd和Zn含量,从而促进Cd和Zn向非活性态转化。本研究证明了羟基磷灰石在西南典型硫铁矿区土壤重金属污染修复中有较大的应用潜力。

Effect Assessment of Nano-hydroxyapatite for Remediation ofCd and Zn Contaminated Soil in Pyrite Areas

Abstract：The column leaching and batch incubation experiments were conducted to investigate the effect of nano-hydroxyapatite addition on the bioaccessibility and speciation of Cd and Zn in yellow soil in pyrite areas.Additive ratios of nano-hydroxyapatite were set as 0% (CK), 1% (weight ratio, P1), 3% (P3) and 5% (P5).It was found that: (1) Nano-hydroxyapatite could increase pH of the leachate and decrease leaching loss of Cd and Zn significantly.Compared with the CK (leaching loss of Cd and Zn were 120 μg and 16.7 mg, respectively), Cd and Zn accumulated leaching in P1, P3 and P5 declined by 74.2%, 85.0%, 92.0% and 79.4%, 92.1%, 97.9% correspondingly; (2) Nano-hydroxyapatite could increase soil pH remarkedly, and the soil pH increased by 0.64, 0.85 and 1.20 of pH units in P1, P3 and P5 treatments after 45 days incubation; (3) In comparison with the CK, nano-hydroxyapatite addition at P1, P3 and P5 reduced available Cd and Zn determined by 0.025 M HCl extraction by 74.2%, 96.8%, 98.4% and 68.1%, 96.6%, 99.5% respectively; (4) Nano-hydroxyapatite significantly decreased the concentrations of exchangeable and carbonate bounded Cd and Zn in sequential extraction, and increased residual fractions, which promoted the transformation of Cd and Zn from the active forms to the inactive ones in the soil.These findings indicated that nano-hydroxyapatite could effectively decrease the heavy metals risk in the soil and had good applications prospect in the remediation of Cd and Zn contaminated soil in typical pyrite regions of Southwest China.