ARSENIC TRANSPORT IN A WATERSHED RECEIVING GOLD MINE EFFLUENT NEAR YELLOWKNIFE, NORTHWEST-TERRITORIES, CANADA
ARSENIC TRANSPORT IN A WATERSHED RECEIVING GOLD MINE EFFLUENT NEAR YELLOWKNIFE, NORTHWEST-TERRITORIES, CANADA
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DOI：
10.1016/0048-9697(94)90503-7
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发表时间：
1994-10-28
影响因子：
9.8
通讯作者：
REIMER, KJ
中科院分区：
文献类型：
--
作者：
BRIGHT, DA;COEDY, B;REIMER, KJ
从一系列小湖泊中收集的沉积物和水样中存在异常高浓度的砷，这为研究淡水中无机砷的环境分配和形态提供了一个独特的机会。砷在水、表层沉积物（0-5厘米深）和排放下游相关孔隙水中的分布与预期不同，这是由于保守稀释和/或沉积物从点源吸附所致。无机砷在水柱，沉积物颗粒和孔隙水表现出的最大浓度相似的4-6公里下游的金矿输入。亚砷酸盐（As（III））是整个流域的沉积物孔隙水中的主要砷，而砷酸盐（As（V））包括绝大多数溶解的砷在水柱样品。在矿井废水中未检测到亚砷酸盐，但发现其在水柱中的浓度随着离排放管下游距离的增加而增加。有两种可能的机制，在这个系统中的历史砷输入的下游再分配：（1）通过沉积物/颗粒运输的整体运动;（2）从沉积物中的再溶解在早期成岩作用，然后向上扩散和运输到下游地区。沉积物中的其他物质的分布是'示踪剂'的金矿废水（如锑，铜，金，镍，锌，硫酸盐和氯离子）进行了检查，以区分这些机制。总的来说，这些数据表明，砷在研究区的表层沉积物中的分布部分控制的大规模移动的沉积物，其次是埋藏与污染较少的沉积物在上游的流域。颗粒浓度的砷的贡献显着的总砷浓度在水柱下游的金矿排放（高达70%的总砷浓度）。在沉积物孔隙水（高达68.9亩M）和上覆水柱（高达7.3亩M的溶解形式）的地区进一步删除输入的砷的浓度极高，但是，是由于从沉积物通过氧化还原相关的溶解再活化。沉积物成岩过程中溶解砷的释放可能会增强，通过adhergenically增强硫酸盐沉积，也与金矿开采活动。
The presence of abnormally high concentrations of arsenic in sediment and water samples collected from a chain of small lakes afforded a unique opportunity to investigate the environmental partitioning and speciation of inorganic arsenic in fresh water. The distribution of arsenic in water, surface sediment (0-5 cm depth) and associated pore water downstream of the discharge differed from that expected due to conservative dilution and/or sediment adsorption from a point-source. Inorganic arsenic in the water column, sediment particulates and pore water exhibited a maximum concentration similar to 4-6 km downstream of the gold-mine input. Arsenite (As(III)) was the predominant arsenical in the sediment pore water throughout the watershed, whereas arsenate (As(V)) comprised the vast majority of dissolved arsenic in water column samples. Arsenite was not detected in the mine effluent, but was found in increasing concentrations in the water column with increasing downstream distance from the discharge pipe. There are two possible mechanisms for the downstream redistribution of historical arsenic inputs in this system: (1) bulk movement via sediment/particulate transport; and (2) redissolution from sediments during early diagenesis, followed by upward diffusion and transport to downstream areas. Sediment distributions of other substances which are 'tracers' of the gold-mine effluent (e.g. antimony, copper, gold, nickel, zinc, sulphate and chloride ion) were examined in order to distinguish between these mechanisms. Collectively, the data indicate that the arsenic distribution in surficial sediments of the study area is controlled partially by the bulk movement of sediments, followed by burial with less contaminated sediments in the upper reaches of the watershed. Particulate concentrations of arsenic contributed significantly to the total arsenic concentrations in the water column downstream of the gold-mine discharge (up to 70% of total As concentration). The extremely high concentrations of arsenicals in sediment pore water (up to 68.9 mu M) and the overlying water column (up to 7.3 mu M in dissolved form) in areas further removed from the input, however, are attributable to remobilization from sediments through redox-related dissolution. This release of dissolved arsenic during sediment diagenesis may be enhanced by anthropogenically-enhanced sulfate deposition, also associated with gold-mining activity.