College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, China; Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark; Sino-Danish Center for Education and Research, Beijing 100190, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, China; Sino-Danish Center for Education and Research, Beijing 100190, China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Environ Pollut. 2020 Feb;257:113565. doi: 10.1016/j.envpol.2019.113565. Epub 2019 Nov 4.
Industrial by-products provide materials for remediation measures. In this study, a silicon-iron amendment was prepared from residue originating from acid-extracted copper (Cu) tailings based on thermal activation at temperatures ranging from 550 °C to 1150 °C for 30 min with the use of additives (CaO, NaCO, NaOH). The remediation performance of the amendment was evaluated through soil incubation and greenhouse pot experiments with vetiver (Vetiveria zizanioides). The results showed that the highest levels of soluble Si (6.11% of the total Si) and Fe (2.3% of the total Fe) in the amendment were achieved with thermal activation at 1150 °C for 30 min using an optimal ratio between residue and additives (residue: CaO: NaCO: NaOH = 1: 0.4: 0.4: 0.2). Heavy metal release indicated that the amendment could be safely used for soil remediation. The incubation experiments showed that the DTPA-extractable Cd, Cr and Pb in contaminated soils decreased with increasing amendment rate, which was not observed for As. The amendment-induced decrease in the Cd, Cr and Pb availability in contaminated soils could be explained by pH-change induced immobilization, Fe-induced chemisorption, Si-induced co-precipitation, and Ca-induced ion exchange. Correlation analysis suggested that there were significant negative correlations between DTPA-extractable Cd, Cr and Pb and the pH, Fe, Si, and Ca in soil pore water and soil. The most suitable amendment rate was determined to be 1% by balancing the efficacy and wise utilization of the amendment. The pot experiment demonstrated that the amendment promoted the vetiver growth and stimulated the accumulation of Cd and Cr in the roots. The amendment was proved to be promising for the phytostabilization of Cd, Cr and Pb in contaminated soils. Further investigations are required to determine whether the amendment is a tool for the long-term remediation of multi-metal-contaminated soils at the field scale.
工业副产品为修复措施提供了材料。在本研究中，基于热激活，从酸浸提铜（Cu）尾矿中得到的残渣制备了硅铁改良剂，热激活温度范围为 550°C 至 1150°C，时间为 30min，并使用添加剂（CaO、NaCO、NaOH）。通过土壤培养和温室盆栽实验，用香根草（Vetiveria zizanioides）评价了改良剂的修复性能。结果表明，在残渣与添加剂最佳比例（残渣：CaO：NaCO：NaOH=1：0.4：0.4：0.2）下，在 1150°C 热激活 30min，改良剂中可溶性 Si（占总 Si 的 6.11%）和 Fe（占总 Fe 的 2.3%）含量最高。重金属释放表明，该改良剂可安全用于土壤修复。培养实验表明，随着改良剂用量的增加，污染土壤中 DTPA 可提取的 Cd、Cr 和 Pb 减少，但 As 没有观察到这种情况。改良剂诱导的污染土壤中 Cd、Cr 和 Pb 生物有效性降低可归因于 pH 变化引起的固定、Fe 诱导的化学吸附、Si 诱导的共沉淀和 Ca 诱导的离子交换。相关分析表明，土壤孔隙水中和土壤中 DTPA 可提取的 Cd、Cr 和 Pb 与 pH、Fe、Si 和 Ca 之间存在显著的负相关关系。通过平衡改良剂的功效和明智利用，确定最合适的改良剂用量为 1%。盆栽实验表明，改良剂促进了香根草的生长，刺激了 Cd 和 Cr 在根系中的积累。结果表明，该改良剂有望用于稳定污染土壤中的 Cd、Cr 和 Pb。需要进一步研究以确定该改良剂是否是在田间尺度上修复多金属污染土壤的长期修复工具。
