Collaborative Research: Tracing Coal Ash Solids in the Environment - Implications for long-term contamination of the aquatic ecosystem

Coal combustion residuals (known as coal ash) is the largest industrial solid waste generated in the U.S., with production rates of over 100 million tons per year. While some fraction of the generated coal ash is recycled, mostly for the cement industry, over half is stored in coal ash impoundments and landfills. Since coal ash contains high concentrations of heavy metals that are easily transported into water, the disposal of coal ash in leaky impoundments can damage the environment and water resources. Hurricane storms and large floods have been shown to cause spills of coal ash into Sutton Lake in eastern North Carolina and contamination of the lake ecological system. This NSF project seeks to detect coal ash contamination in sediments within different lakes throughout North Carolina and to evaluate the possible environmental impacts of coal ash in these lakes. The project will develop novel methods to detect coal ash in the environment. Understanding the potential occurrence of coal ash outside the major disposal sites and the ecological impact in the lakes is important for the communities living near coal ash ponds and the impacted lakes. The use of scientific methods to detect coal ash in the environment is important for an unbiased and scientific-base evaluation of the risks of coal ash to residents living in rural areas of North Carolina.

The proposed study aims to collect sediments and pore water samples from lakes near major coal ash disposal sites in North Carolina in order to detect the presence of coal ash and its impact on the ecosystem. The study is based on developing novel geochemical and physical methods for tracing coal ash and its contaminants in the environment through integration of independent proxies for the presence of coal ash in the bottom sediments including trace metals distribution, strontium isotope ratios (87Sr/86Sr), lead stable isotopes (206Pb/208Pb, 207Pb/206Pb), radionuclides (228Ra, 226Ra, 210Pb, 137Cs), magnetic susceptibility, and magnetic granulometry. This reconnaissance study will investigate the spatial and temporal distribution of coal ash and contaminants likely introduced during extreme hydrologic events into lakes near coal ash storage impoundments in North Carolina. The study will also evaluate the mobilization of contaminants from coal ash solids into the ecosystem through leaching experiments and measurement of pore water from the lake bottom sediments. The objectives of the study are (1) to develop methods for identification of coal ash in sediments and associated contaminants in pore water extracted from lake bottom sediments; (2) to evaluate the magnitude of unmonitored coal ash spills in the impacted lakes; (3) to determine the residence time of sediments in lakes impacted by coal ash spills; and (4) to evaluate the long-term ecological effects that could result from unmonitored coal ash spills into lakes in North Carolina. The environmental legacy of coal ash is one of the emerging topics in the southeastern U.S. Leaking of coal ash ponds and spills have shown to have environmental effects on the quality of groundwater and surface water near coal ash disposal sites. The expected decommissioning of the operating coal-fired power plants during the next decade requires permanent solutions for the large volumes of coal ash commonly stored in coal ash impoundments near lakes and streams. The evidence of a coal ash spills to Sutton Lake has further raised public concerns about the environmental and human health safety. This NSF project will establish scientific-based criteria for environmental risks assessment associated with coal ash storage and management. Graduate and undergraduate students from Duke University, and undergraduate students from Appalachian State and Montclair State University will take active roles in the project. The results of the project will be used to construct a module on coal ash pollution to 'Water on the Move', a K-12 outreach program in the Department of Geological and Environmental Sciences at Appalachian State. In addition to publication in scientific journals and presentation in professional conferences, the results of this project will be disseminated to the general public and communities living near coal ash impoundments and impacted lakes through press releases following scientific publication, communications with environmental NGOs working with the local communities, townhall meetings with communities at larger risks with direct dialogue with residents, a designated website and social media, communication and presentation of the results in federal (U.S. EPA, Congress) and state (NC House of Representatives) agencies.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.