School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, People's Republic of China.
Department of Applied Chemistry, Szent István University, Villányiút 35-43, Budapest, 1118, Hungary.
Environ Sci Pollut Res Int. 2020 Jan;27(3):2433-2443. doi: 10.1007/s11356-018-2780-x. Epub 2018 Aug 18.
Toxic metal(loid)s released from tailing residues of mining operations have become a global issue with regard to environmental impacts. Biochar derived from the agriculture waste is considered as a cost-effective and stable material, which could be applied for remediation of sites contaminated with toxic metal(loid)s. In the present study, tailings were amended for 90 days with increasing concentrations of Arundo donax L. stem-derived biochar (ASBC; at 0, 1, 3, and 5%). The 7-day wheat seed germination toxicity test was then used to assess the bioavailability of toxicants in aqueous leachates of the biochar-amended tailing samples. Concentrations of As, Cd, Cu, Pb, and Sb in leachates and the Community Bureau of Reference chemical fractions were determined using ICP-OES. The results indicated that tailing leachates were phytotoxic, an effect that was partially decreased due to increasing concentrations of ASBC, with maximum effects (∼47% of tailing phytotoxicity) occurring at 3% ASBC. Results of further fractionation analyses indicated that increasing concentrations of ASBC amendment decreased the mobile fractions of Cd, Cu, and Pb in tailing samples, but increased the mobilities of As and Sb. A novel approach using the relative toxicity index (= sum of toxicities of individual potentially toxic elements) indicated that the toxicity of the tailings decreased when As was not present, since As decreased the biochar-reduced toxicity. Our results suggest that the ability of using biochar to decrease toxicity in tailings (by sequestration of cationic metals such as Cd, Cu, and Pb) is limited by its inability to immobilize oxyanionic metalloids such as As and Sb.
采矿作业尾矿渣中释放的有毒金属（类）已成为一个全球性的环境问题。农业废弃物衍生的生物炭被认为是一种具有成本效益和稳定的材料，可用于修复受有毒金属（类）污染的场地。在本研究中，尾矿用 Arundo donax L. 茎衍生生物炭（ASBC；0、1、3 和 5%）进行了 90 天的改良。然后使用 7 天小麦种子发芽毒性试验来评估生物炭改良尾矿样品水提物中有毒物质的生物可利用性。采用 ICP-OES 测定浸出液和社区参考局化学形态中 As、Cd、Cu、Pb 和 Sb 的浓度。结果表明，尾矿浸出液具有植物毒性，这种效应部分由于 ASBC 浓度的增加而降低，当 ASBC 浓度为 3%时，最大效应（约为尾矿植物毒性的 47%）。进一步的分级分析结果表明，ASBC 施用量的增加降低了尾矿中 Cd、Cu 和 Pb 的可移动分数，但增加了 As 和 Sb 的迁移率。一种使用相对毒性指数（=单个潜在有毒元素毒性之和）的新方法表明，当不存在 As 时，尾矿的毒性降低，因为 As 降低了生物炭降低的毒性。我们的结果表明，生物炭通过螯合 Cd、Cu 和 Pb 等阳离子金属来降低尾矿毒性的能力受到其不能固定 As 和 Sb 等含氧类金属的限制。
