Collaborative Research: Characterization of Contaminants and Isotopic Tracers Associated with Coal Combustion Products

1235661/1235735 Hsu-Kim/HowerCollaborative Research：Characterization of contaminants and isotopic tracers associated with coal combustion products煤燃烧产物（CCP）是美国最大的工业废物流，每年产生约1.3亿吨。已知这种废物含有有毒元素，如砷、硒和汞。虽然CCP的一部分被回收用于有益的目的，但大多数废物被储存在全国数百个垃圾填埋场和储存池中。CCP不被归类为危险废物，因此，这些垃圾填埋场和储存池通常没有衬里，容易发生泄漏和故障。此外，从储存池排放的废水往往没有受到监测，如果含有从关键氯化石蜡中沥滤出来的有毒元素，则可能造成生态危害。本项目的目标是了解CCP在处置或意外释放到环境中时所造成的危害。该研究将涉及实验室实验，以表征从广泛的燃煤电厂中取样的CCP的地球化学成分，确定在环境相关条件下产生的CCP沥滤液的成分和微量元素形态，并进行实地调查，以表征北卡罗来纳州CCP蓄水池的污水。这项研究将深入评估可以从CCP中浸出的金属和类金属污染物，以及它们的形态和生物利用度如何随着环境条件的变化而变化。这项工作的一个新组成部分是使用CCP中硼、锶和镭的同位素特征作为跟踪CCP释放的污染物的方法。煤基能源目前约占全球总发电量的40%，预计在未来20年（在美国和全球）将大幅增加。尽管每年都会产生大量的CCP废物，但与处置实践相关的风险并不为人所知，特别是鉴于最近的煤灰泄漏，其中PI确定了与CCP废物相关的有毒元素（砷，硒，汞）的释放。 这项研究的成果将是一个层次的煤灰废物的基础上，其潜在的造成损害划定的已知变量，如原始煤炭地质和燃烧操作参数。该研究将尝试建立已知过程变量之间的关系（例如，煤的类型、煤灰成分、燃烧参数）以及CCP中有毒元素的浸出潜力。总的来说，CCP浸出研究和蓄水池分析的结果将用于评估CCP暴露风险潜力的排名方法。联邦和州环境机构未来对CCP处置实践的监管行动将需要这些信息。研究人员将利用杜克的外展计划以及与公共利益相关者的持续合作，向公众和学生更广泛地传播这项工作。

1235661/1235735 Hsu-Kim/HowerCollaborative Research: Characterization of contaminants and isotopic tracers associated with coal combustion productsCoal combustion products (CCPs) represent the largest industrial waste stream in the U.S. with approximately 130 million tons generated every year. This waste is known to contain toxic elements such as arsenic, selenium, and mercury. While a subset of CCPs is recycled for beneficial purposes, the majority of the waste is stored in hundreds of landfills and storage ponds across the nation. CCPs are not classified as hazardous waste, and as a result, these landfills and storage ponds are typically unlined and susceptible to leaks and failures. Moreover, discharge of effluents from storage ponds are often not monitored and may pose an ecological hazard if they contain toxic elements leached from CCPs. The goal of this project is to understand the hazards posed by CCPs during their disposal or accidental release to the environment. The research will involve laboratory experiments to characterize the geochemical composition of CCPs sampled from a wide array of coal-fired power plants, determine the composition and trace element speciation of CCP leachates generated under environmentally-relevant conditions, and perform field investigations to characterize effluent from CCP holding ponds in North Carolina. This research will provide an in-depth evaluation of the metal and metalloid contaminants that can leach from CCPs and how their speciation and bioavailability change as a function of environmental conditions. A novel component of the work is the use of isotopic signatures of boron, strontium, and radium in the CCPs as methods for tracking contaminants released from CCPs. Coal-based energy currently represents approximately 40% of the total worldwide electricity production and is expected to increase significantly in the next 20 years (in the U.S. and globally). Despite the large amount of CCP wastes that are generated annually, the risks associated with disposal practices are not well-known, particularly in light of a recent coal ash spill in which the PIs identified release of toxic elements (arsenic, selenium, mercury) associated with CCP wastes. An outcome of this research will be a hierarchy of coal ash wastes based on their potential to cause harm delineated by known variables such as the original coal geology and combustion operation parameters. The research will attempt to establish relationships between known process variables (e.g., coal type, coal ash composition, combustion parameters) and the leaching potential of toxic elements from CCPs. Collectively the results of CCP leaching studies and holding pond analyses will be used to evaluate methods to rank CCPs for their exposure risk potential. This information will be needed for future regulatory actions on CCP disposal practices from federal and state environmental agencies. The researchers will leverage outreach programs at Duke and on-going collaborations with public interest stakeholders to provide broader dissemination of this work to the public and to students.