Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, United States.
Department of Geological and Environmental Sciences, Appalachian State University, Boone, North Carolina 28608, United States.
Environ Sci Technol. 2021 Aug 3;55(15):10387-10397. doi: 10.1021/acs.est.1c01215. Epub 2021 Jul 20.
Coal combustion residuals (CCRs), in particular, coal fly ash, are one of the major industrial solid wastes in the U.S., and due to their high concentrations of toxic elements, they could pose environmental and human health risks. Yet detecting coal fly ash in the environment is challenging given its small particle size. Here, we explore the utility and sensitivity of using geochemical indicators (trace elements, Ra nuclides, and Pb stable isotopes), combined with physical observation by optical point counting, for detecting the presence of trace levels of coal fly ash particles in surface soils near two coal-fired power plants in North Carolina and Tennessee. Through experimental work, mixing models, and field data, we show that trace elements can serve as a first-order detection tool for fly ash presence in surface soils; however, the accuracy and sensitivity of detection is limited for cases with low fly ash proportion (i.e., <10%) in the soil, which requires the integration of more robust Ra and Pb isotopic tracers. This study revealed the presence of fly ash particles in surface soils from both the recreational and residential areas, which suggests the fugitive emission of fly ash from the nearby coal-fired power plants.
煤炭燃烧残余物（CCRs），特别是粉煤灰，是美国主要的工业固体废物之一，由于其含有高浓度的有毒元素，可能对环境和人类健康构成风险。然而，由于其粒径小，在环境中检测粉煤灰具有挑战性。在这里，我们探索了使用地球化学指标（微量元素、Ra 核素和 Pb 稳定同位素）以及光学点计数的物理观察，用于检测北卡罗来纳州和田纳西州两个燃煤电厂附近地表土壤中痕量粉煤灰颗粒存在的效用和灵敏度。通过实验工作、混合模型和野外数据，我们表明微量元素可以作为表面土壤中粉煤灰存在的初步检测工具；然而，对于土壤中粉煤灰比例较低（即 <10%）的情况，检测的准确性和灵敏度有限，这需要更强大的 Ra 和 Pb 同位素示踪剂的整合。这项研究揭示了来自娱乐和居民区的地表土壤中存在粉煤灰颗粒，这表明附近燃煤电厂的粉煤灰有逸散排放。
