RAPID, Collaborative: Using geochemical signatures to evaluate the impact of a recent coal ash spill on trace elements in water and sediments of the Dan River

2014年2月2日，美国第三大煤灰泄漏事故发生在北卡罗来纳州伊甸，杜克能源公司占地27英亩的丹河蒸汽厂污水池下的排水管坍塌，将煤灰和数百万加仑的污水排入丹河。丹河发源于弗吉尼亚州，流入北卡罗来纳州，然后向北流经州界八次，又回到弗吉尼亚州。它最终流入罗阿诺克河，然后流入克尔湖，然后流入加斯顿湖，最后流入北卡罗来纳州的阿尔伯马尔湾。这片水域是一个高度利用的娱乐系统，也是从弗吉尼亚州丹维尔到弗吉尼亚海滩等城市的饮用水来源。煤灰的有毒成分包括各种污染物，从砷（as）、铅（Pb）、汞（Hg）到硒（Se）等金属，以及一系列有机化合物。虽然蓄水水中的元素浓度可以超过饮用水标准和水生生物水质标准，但在新的生物地球化学环境中，人们对淡水河灰分中微量元素的命运知之甚少。溶解和物种形成的变化会增加金属毒性，从而在未来几年威胁野生生物和水的可用性。要回答其中的一些问题，有必要采用多学科方法。拟议的工作应该为环境机构和水资源管理者提供一个更清晰的画面，范围，运输时间尺度，以及煤炭燃烧残留物衍生污染物在该河流系统中的去除过程。该项目将为煤燃烧残渣污染物在更长时间和空间尺度上的演变提供独特的见解，这些污染物的水平可能被认为低于直接的修复目标，但对整体生物地球化学功能和水生生态系统的健康仍然很重要。开发和应用新型和独立的煤燃烧残留物地球化学示踪剂将有助于消除与污染物浓度数据相关的一些模糊性，并确定煤燃烧残留物输入的程度，即使没有污染物的作用水平。虽然州/联邦机构和其他组织最初的重点是确定煤燃烧残渣池流出物和河流中的污染物水平，但有几种技术可以使科学家在时间和长度尺度上追踪系统的响应，这些响应与煤燃烧残渣向克尔水库的运输相一致。本研究将为丹河泄漏后水体和沉积物中主要、次要和微量元素的浓度以及稳定同位素S-34（硫-34）的追踪提供工具。由于锗（Ge）在煤中富集，应该作为一种保守的示踪剂，我们预计Ge是异常的，Ge/Si（硅）比是煤燃烧残渣输入的唯一指纹。人们认为As/Ge；（铬）Cr/Ge和其他微量元素/Ge比值应该是识别煤燃烧残渣相关元素异常的有力工具。溶解硫酸盐中S-34的稳定同位素分析将作为煤燃烧残渣输入的第二个约束，可以与Ge/Si和微量元素/Ge比进行比较。这项RAPID基金将为漏油事件发生后立即开始的采样和分析项目提供资金。预计河流水文过程和生物地球化学过程都能显著地改变和减弱污染事件的直接影响。为了评估运输和生物地球化学去除对所关注的污染物的影响，建立和继续定期取样方案至关重要。

1440099/1440067Derry/SchreiberOn February 2, 2014, the third-largest coal ash spill in the Nation occurred at Eden, North Carolina where a drainage pipe under a 27-acre Duke Energy Dan River Steam Plant waste pond collapsed, discharging coal ash and millions of gallons of contaminated water into the Dan River. The Dan River originates in Virginia and flows into North Carolina and then flows north back into Virginia crossing the state lines eight times. It eventually flows into the Roanoke River, and into Lake Kerr then Lake Gaston and eventually into the Albemarle Sound, NC. The waters serve as a highly used recreation system and as a source of drinking water for cities from Danville, VA to as far away as Virginia Beach. The toxic constituents of coal ash include various contaminants from metals such as arsenic (As), lead (Pb), mercury (Hg) to selenium (Se) along with a suite of organic compounds. While the element concentrations in impoundment water can exceed drinking water criteria and aquatic life water quality criteria, less is known about the fate of trace elements bound to ash in the new biogeochemical environment of the Dan River. Dissolution and changes in speciation can increase metal toxicity thus threaten wild life and water usability for years to come. To answer some of these questions a multidisciplinary approach is necessary. The proposed work should provide a clearer picture to environmental agencies and water managers of the extent, transport time scales, and removal processes of coal combustion residue-derived pollutants in this river system.This project will provide unique insight into the evolution of coal combustion residue-derived contaminants in the basin over longer time and spatial scales, and at levels that may be considered below immediate remediation targets but are still important for the overall biogeochemical function and health of the aquatic ecosystem. The development and application of novel and independent geochemical tracers for coal combustion residue input will help remove some of the ambiguity associated with data on contaminant concentrations, and identify the extent of coal combustion residue inputs even in the absence of action levels of contaminants. While the initial focus by the state/federal agencies and other organizations has been on identifying the levels of contaminants in the coal combustion residue pond outflow and the river, there are several techniques which allow scientists to trace the response of the system in time and length scales consistent with the transport of coal combustion residue to the Kerr Reservoir. This proposed research will provide tools to track the concentrations of major, minor and trace elements as well as the stable isotope S-34 (sulfur-34) in water and sediments in the Dan River in the post-spill period. Because germanium (Ge) is enriched in coals and should act as a conservative tracer, we expect Ge to be anomalous and Ge/Si (silicon) ratios to be a unique fingerprint for coal combustion residue input. It is thought that the As/Ge; (chromium) Cr/Ge and other trace element/Ge ratios should be a powerful tools for identifying coal combustion residue-related anomalies in those elements. The stable isotopic analysis of S-34 in dissolved sulfate will act as a second constraint on the coal combustion residue input that can be compared to the Ge/Si and trace element/Ge ratios. This RAPID funding is to provide funds to continue a sampling and analysis program begun in the immediate aftermath of the spill. Both river hydrologic process and biogeochemical processes are expected to significantly modify and attenuate the immediate impacts of the contamination event. It is vital to establish and continue a regular sampling program in order to assess the impact of transport and biogeochemical removal on contaminants of concern.