U.S. Geological Survey , Reston, Virginia, 20192 United States.
U.S. Geological Survey , Menlo Park, California, 94025 United States.
Environ Sci Technol. 2016 Feb 2;50(3):1126-36. doi: 10.1021/acs.est.5b04081. Epub 2016 Jan 15.
At the Ely Copper Mine Superfund site, Cu concentrations exceed background values in both streamwater (160-1200 times) and sediments (15-79 times). Previously, these sediment samples were incubated with laboratory test organisms, and they exhibited variable toxicity for different stream sites. In this study we combined bulk- and microscale techniques to determine Cu speciation and distribution in these contaminated sediments on the basis of evidence from previous work that Cu was the most important stressor in this environment and that variable observed toxicity could have resulted from differences in Cu speciation. Copper speciation results were similar at microscopic and bulk scales. The major Cu species in the more toxic samples were sorbed or coprecipitated with secondary Mn (birnessite) and Fe minerals (jarosite and goethite), which together accounted for nearly 80% of the total Cu. The major Cu species in the less toxic samples were Cu sulfides (chalcopyrite and a covellite-like phase), making up about 80-95% of the total Cu, with minor amounts of Cu associated with jarosite or goethite. These Cu speciation results are consistent with the toxicity results, considering that Cu sorbed or coprecipitated with secondary phases at near-neutral pH is relatively less stable than Cu bound to sulfide at lower pH. The more toxic stream sediment sites were those that contained fewer detrital sulfides and were upstream of the major mine waste pile, suggesting that removal and consolidation of sulfide-bearing waste piles on site may not eliminate all sources of bioaccessible Cu.
在伊利铜矿超级基金场址，溪流水中的铜浓度（160-1200 倍）和沉积物中的铜浓度（15-79 倍）均超过背景值。此前，这些沉积物样本已与实验室测试生物进行了共培养，结果显示，不同溪流点的沉积物样本具有不同的毒性。在本研究中，我们结合了宏观和微观技术，基于先前研究中铜是该环境中最重要的胁迫因素的证据，以及观察到的可变毒性可能是由于铜形态的差异所致，来确定这些受污染沉积物中的铜形态及其分布。微观和宏观尺度上的铜形态结果相似。在毒性较大的样本中，主要的铜形态与次生 Mn（针铁矿）和 Fe 矿物（水铝钾矾和针铁矿）发生吸附或共沉淀，共占总铜的近 80%。在毒性较小的样本中，主要的铜形态为 Cu 硫化物（黄铜矿和类似蓝辉铜矿的相），占总铜的 80-95%，少量 Cu 与水铝钾矾或针铁矿结合。考虑到在近中性 pH 条件下与次生相吸附或共沉淀的 Cu 相对不稳定，与在较低 pH 下与硫化物结合的 Cu 相比，这些铜形态结果与毒性结果一致。毒性较大的溪流沉积物点是那些含较少碎屑硫化物且位于主要矿山废物堆上游的点，这表明在现场去除和整合含硫化物的废物堆可能无法消除所有生物可利用 Cu 的来源。
