Coal is currently used as a major source of energy worldwide, generating about 40% of global electricity. In 2012, approximately 110 million tons of coal fly ash, the ash that is generated after coal combustion, was produced in the United States. Coal fly ash contains several metal(loid)s of physiological concern, such as lead, arsenic, and mercury. Fly ash particles may be released to the environment due to accidental release or uncovered storage, making them susceptible to surface water or aeolian transport, or leaching during precipitation events. This project aims to examine the interaction between coal fly ash before and after exposure to environmental media and simulated physiological fluids (gastric and alveolar) in order to estimate the potential bioaccessibility of metal(loid)s in fly ash. Previous characterization of fly ash obtained from a local coal-fired power plant identified the presence of toxic metal(loid)s such as arsenic (8.1 + 0.5 mg kg-1), lead (17 + 1 mg kg-1), molybdenum (5.1 + 0.4 mg kg-1), mercury (2 + 1 mg kg-1), manganese (370 + 80 mg kg-1), and selenium (2.0 + 0.5 mg kg-1). Based on these results, gastric and alveolar physiological based extraction tests (PBETs) were performed on unreacted fly ash and solid phase residuals of fly ash that had been reacted with either 18MΩ water or simulated rainwater. After agitation at 37° C for times of one week for alveolar or one hour for gastric extractions, filtered supernatants were analyzed by inductively coupled mass spectrometry (ICP-MS) to determine the metal(loid) liberation under physiological conditions. Future work includes characterization of mineralogical transformations during room temperature reactions with the 18MW or simulated rain water and further PBETs after fly ash reaction with natural aquatic media.

Physiological extractions of metal(loid)s from coal fly ash in interior Alaska

253rd National Meeting (2017)

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