Wang Suiling, Mulligan Catherine N
Department of Building, Civil and Environmental Engineering, Concordia University, 1455 de Maisonneuve Boulevard W., EV6.187, Montreal, Quebec, Canada.
Chemosphere. 2009 Jan;74(2):274-9. doi: 10.1016/j.chemosphere.2008.09.040. Epub 2008 Oct 31.
Arsenic and heavy metal mobilization from mine tailings is an issue of concern as it might pose potential groundwater or ecological risks. Increasing attention recently has been focused on the effects of natural organic matter on the mobility behavior of the toxicants in the environment. Column experiments were carried out in this research study to evaluate the feasibility of using humic acid (HA) to mobilize arsenic and heavy metals (i.e., Cu, Pb and Zn) from an oxidized Pb-Zn mine tailings sample collected from Bathurst, New Brunswick, Canada. Capillary electrophoresis analyses indicated that arsenate [As(V)] was the only extractable arsenic species in the mine tailings and the addition of HA at pH 11 did not incur the oxidation-reduction or methylation reactions of arsenic. A 0.1% HA solution with an initial pH adjusted to 11 was selected as the flushing solution, while distilled water (initial pH adjusted to 11) was used as the control to account for the mobilization of arsenic and the heavy metals by physical mixing and the effect of pH. It was found that the HA could significantly enhance the mobilization of arsenic and heavy metals simultaneously from the mine tailings. After a 70-pore-volume-flushing, the mobilization of arsenic, copper, lead and zinc reached 97, 35, 838 and 224 mg kg(-1), respectively. The mobilization of arsenic and the heavy metals was found to be positively correlated with the mobilization of Fe in the presence of the HA. Moreover, the mobilization of arsenic was also correlated well with that of the heavy metals. The mobilization of co-existing metals to some extent might enhance arsenic mobilization in the presence of the HA by helping incorporate it into soluble aqueous organic complexes through metal-bridging mechanisms. Use of HA in arsenic and heavy metal remediation may be developed as an environmentally benign and possible effective remedial option to reduce and avoid further contamination.
尾矿中砷和重金属的迁移是一个备受关注的问题，因为它可能带来潜在的地下水或生态风险。最近，人们越来越关注天然有机物对环境中毒性物质迁移行为的影响。本研究开展了柱实验，以评估使用腐殖酸（HA）从加拿大新不伦瑞克省巴瑟斯特采集的氧化铅锌尾矿样品中迁移砷和重金属（即铜、铅和锌）的可行性。毛细管电泳分析表明，砷酸盐[As(V)]是尾矿中唯一可提取的砷物种，在pH为11时添加HA不会引发砷的氧化还原或甲基化反应。选择初始pH值调至11的0.1% HA溶液作为冲洗液，而蒸馏水（初始pH值调至11）用作对照，以说明通过物理混合对砷和重金属的迁移作用以及pH值的影响。结果发现，HA能显著同时增强尾矿中砷和重金属的迁移。经过70个孔隙体积的冲洗后，砷、铜、铅和锌的迁移量分别达到97、35、838和224 mg kg(-1)。发现在有HA存在的情况下，砷和重金属的迁移与铁的迁移呈正相关。此外，砷的迁移也与重金属的迁移密切相关。在有HA存在的情况下，共存金属的迁移在一定程度上可能通过金属桥接机制帮助将砷纳入可溶性水有机络合物来增强砷的迁移。在砷和重金属修复中使用HA可开发成为一种环境友好且可能有效的修复选择，以减少和避免进一步污染。
