Geochemical processes influencing arsenic mobility at Bullendale historic gold mine, Otago, New Zealand
Geochemical processes influencing arsenic mobility at Bullendale historic gold mine, Otago, New Zealand
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影响新西兰奥塔哥布伦代尔历史金矿砷迁移率的地球化学过程
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
D. Craw
中科院分区：
文献类型：
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作者：
L. Haffert;D. Craw
摘要历史悠久的布伦代尔金矿于1864年至1907年在新西兰南岛处理了来自中生代矿床的富含毒砂的矿石。矿场关闭后并无进行场地修复，而处理废物的砷浓度高达40重量%。最初，所有这些砷都以毒砂的形式存在，随着时间的推移，它已被次生砷相取代。废物演化导致砷相在具有不同量的吸附砷的水铁矿、无定形铁砷酸盐和结晶钾铁矾、臭葱石和锌铁矾之间的矿物学分级。二次砷相的稳定性在低pH（pH 3，<0.1 mg/L）下是有利的，并且目前，与砷酸铁溶解相关的反应确保了c的主要pH窗口。2.5到3.5。然而，通过洪水增加pH值可能会使次生砷矿物不稳定，导致砷溶解度大幅增加（>100 mg/L）。除了电池现场，上游的一个支洞是一个持续的来源溶解砷的环境。由于集水区的pH值偏碱性，砷保持移动的状态，并溶解了C。0.03在下游2公里以上的Skippers Creek中可检测到mg/L。即使这种异常已经被稀释，砷通量的河流仍然主要是由支洞输入控制。
Abstract The historic Bullendale gold mine processed arsenopyrite-rich ore from mesothermal deposits in the South Island of New Zealand from 1864 to 1907. No site rehabilitation was undertaken upon mine closure and processing waste contains arsenic concentration of up to 40 wt%. Originally, all of this arsenic was present as arsenopyrite and with time it has been replaced by secondary arsenic phases. Waste evolution has resulted in a mineralogical gradation of arsenic phases between the ferrihydrite with varying amounts of adsorbed arsenic, amorphous iron arsenates and crystalline kankite, scorodite and zykaite. The stability of the secondary arsenic phases is favoured at low pH (pH 3, <0.1 mg/L) and, at present, reactions associated with iron arsenate dissolution ensure a prevailing pH window of c. 2.5 to 3.5. However, an increase in pH through flooding could destabilise the secondary arsenic minerals resulting in a substantial increase of arsenic solubility (>100 mg/L). In addition to the battery site, an upstream adit is a continuous source of dissolved arsenic to the environment. Due to the alkaline pH conditions in catchment water, arsenic remains mobile and dissolved As of c. 0.03 mg/L is detectable in Skippers Creek more than 2km downstream. Even when this anomaly has been diluted, the arsenic flux of the river is still predominantly controlled by the adit input.