Effect of bicarbonate and phosphate on arsenic release from mining-impacted sediments in the Cheyenne River watershed, South Dakota, USA
Effect of bicarbonate and phosphate on arsenic release from mining-impacted sediments in the Cheyenne River watershed, South Dakota, USA
复制标题
DOI：
10.1039/c8em00461g
复制
发表时间：
2019-03-01
影响因子：
5.5
通讯作者：
Cerrato, Jose M.
中科院分区：
文献类型：
--
作者：
DeVore, Cherie L.;Rodriguez-Freire, Lucia;Cerrato, Jose M.
利用水溶液形态化学、光谱学和衍射分析研究了受南达科他州中北部金矿开采遗产影响的河岸沉积物中砷（As）的迁移。金矿开采导致约109公吨的矿山废物排放到Homestake矿附近的怀特伍德溪（WW）和下游241公里处Deal Ranch（DR）的夏延河。从固体样品中测得的酸可提取As的最高浓度在WW为2020 mg kg（-1），在DR为385 mg kg（-1）。使用XRD鉴定了WW和DR之间相似的沉积物矿物学，以铝硅酸盐和含铁矿物为主。在这两个网站的地表水碱度测量范围从1000至2450毫克L-1的碳酸钙（10-20毫米HCO 3-在pH 7）。在氧化条件下进行批实验室实验，以评估NaHCO 3（0.2 mM和20 mM）和NaH 2 PO 3（0.1和10 mM）对As的动员的影响。由于河流的碱性和牧场的营养物动员，这些离子与场地相关。用NaHCO 3处理的As（V）释放的范围为17-240 μ g L-1。然而，最高的释放（6234 μ g L-1）发生与10 mM NaH 2 PO 3，这表明，作为释放是有利的竞争性离子置换与PO 43-相比，HCO 3-。虽然较高的总砷检测WW固体，目前在DR固体中的As（V）是不稳定的反应时，与碳酸氢钠和磷酸二氢钠，这是一个相关的发现，社区生活在河岸附近。这项研究的结果有助于更好地了解受采矿遗产影响的地表水站点中的As流动性。
The mobilization of arsenic (As) from riverbank sediments affected by the gold mining legacy in north-central South Dakota was examined using aqueous speciation chemistry, spectroscopy, and diffraction analyses. Gold mining resulted in the discharge of approximately 109 metric tons of mine waste into Whitewood Creek (WW) near the Homestake Mine and Cheyenne River at Deal Ranch (DR), 241 km downstream. The highest concentrations of acid-extractable As measured from solid samples was 2020 mg kg(-1) at WW and 385 mg kg(-1) at DR. Similar sediment mineralogy between WW and DR was identified using XRD, with the predominance of alumino-silicate and iron-bearing minerals. Alkalinity measured in surface water at both sites ranged from 1000 to 2450 mg L-1 as CaCO3 (10-20 mM HCO3- at pH 7). Batch laboratory experiments were conducted under oxidizing conditions to evaluate the effects of NaHCO3 (0.2 mM and 20 mM) and NaH2PO3 (0.1 and 10 mM) on the mobilization of As. These ions are relevant for the site due to the alkaline nature of the river and nutrient mobilization from the ranch. The range of As(V) release with the NaHCO3 treatment was 17-240 mu g L-1. However, the highest release (6234 mu g L-1) occurred with 10 mM NaH2PO3, suggesting that As release is favored by competitive ion displacement with PO43- compared to HCO3-. Although higher total As was detected in WW solids, the As(V) present in DR solids was labile when reacted with NaHCO3 and NaH2PO3, which is a relevant finding for communities living close to the river bank. The results from this study aid in a better understanding of As mobility in surface water sites affected by the mining legacy.