School of Water Resource and Environment, Research Center of Environmental Sciences and Engineering, China University of Geosciences (Beijing), 29 Xueyuan Road, Haidian District, 100083, Beijing, China.
School of Water Resource and Environment, Research Center of Environmental Sciences and Engineering, China University of Geosciences (Beijing), 29 Xueyuan Road, Haidian District, 100083, Beijing, China.
J Environ Manage. 2020 Jul 1;265:110511. doi: 10.1016/j.jenvman.2020.110511. Epub 2020 Apr 6.
Nonferrous metal mining activities produce enormous amounts of tailings that contain high concentrations of toxic chemicals threatening human health and the environment. This risk could be alleviated using remediation agents such as biochar, as proposed by others. However, contradictory evidence indicates that biochar can increase or sometimes decrease bioavailable concentrations depending on the selection of metal(loid)s in mine tailings. Here three biochars derived from different raw stocks were used to treat mine tailings samples. Chemical analyses indicated that all biochars favored the stabilization of Cd, Cr, Cu, Pb, and Zn, as well as the mobilization of As and Sb. The barley root elongation bioassay showed that the tailings toxicity was only partially diminished (up to 55.8%) or even elevated (up to 20.7%) by biochar treatment. Similar results were also observed from microbial enzyme assays (increased up to 28.3% or decreased up to 24.0%). Further analyses showed that these toxic effects correlated well with the relative toxicity index (R = 0.66 to 0.88). Toxicity testing coupled with the use of a toxicity prediction model presented here suggested that the release of As and Sb from tailings compromised the favorable effects of biochar treatment on toxic cationic metals. Such information is of paramount importance when taking countermeasures for improving bioremediation technologies.
有色金属矿业活动产生大量尾矿，其中含有高浓度的有毒化学物质，威胁着人类健康和环境。其他人提出，可以使用修复剂如生物炭来减轻这种风险。然而，矛盾的证据表明，生物炭可以根据尾矿中金属（类）的选择增加或有时降低生物利用浓度。在这里，使用了三种源自不同原料的生物炭来处理尾矿样品。化学分析表明，所有生物炭都有利于稳定 Cd、Cr、Cu、Pb 和 Zn，以及促进 As 和 Sb 的迁移。大麦根伸长生物测定表明，生物炭处理仅部分降低（最多 55.8%）或甚至增加（最多 20.7%）了尾矿的毒性。微生物酶测定也观察到了类似的结果（增加最多 28.3%或减少最多 24.0%）。进一步的分析表明，这些毒性效应与相对毒性指数（R=0.66 至 0.88）密切相关。毒性测试结合使用这里提出的毒性预测模型表明，尾矿中 As 和 Sb 的释放削弱了生物炭处理对毒性阳离子金属的有利影响。在采取对策改善生物修复技术时，这种信息至关重要。
