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Fact Sheet 2015–3037

Trace Elements in Coal Ash

By Amrika Deonarine, Allan Kolker, and Michael Doughten

Thumbnail of and link to report PDF (1.61 MB)Abstract

Coal ash is a residual waste product primarily produced by coal combustion for electric power generation. Coal ash includes fly ash, bottom ash, and flue-gas desulfurization products (at powerplants equipped with flue-gas desulfurization systems). Fly ash, the most common form of coal ash, is used in a range of products, especially construction materials. A new Environmental Protection Agency ruling upholds designation of coal ash as a non-hazardous waste under Subtitle D of the Resource Conservation and Recovery Act, allowing for the continued beneficial use of coal ash and also designating procedures and requirements for its storage.

In this fact sheet, the form, distribution, and behavior of trace elements of environmental interest in samples of coal fly ash were investigated in response to concerns about element mobility in the event of an ash spill. The study includes laboratory-based leaching experiments to examine the behavior of trace elements, such as arsenic (As) and chromium (Cr), in response to key environmental factors including redox conditions (degree of oxygenation), which are known to vary with depth within coal ash impoundments and in natural ecosystems. The experiments show that As dissolves from samples of coal fly ash into simulated freshwater under both oxic (highly oxygenated) and anoxic (poorly oxygenated) conditions, whereas dissolved Cr concentrations are very redox dependent. This U.S. Geological Survey research helps define the distribution of elements such as As in coal ash and shows that element mobility can vary considerably under different conditions expected in the environment.

First posted May 13, 2015

For additional information, contact:
Director, Eastern Energy Resources Science Center
U.S. Geological Survey
956 National Center
12201 Sunrise Valley Drive
Reston, VA 20192
Telephone: 703-648-6401

Or visit the USGS Eastern Energy Resources Science Center Web site at

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Suggested citation:

Deonarine, Amrika, Kolker, Allan, and Doughten, Michael, 2015, Trace elements in coal ash: U.S. Geological Survey Fact Sheet 2015–3037, 6 p.,

ISSN 2327-6916 (print)

ISSN 2327-6932 (online)

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