TRACING THE EVIDENCE OF POLLUTION IN SEDIMENTS DUE TO COAL COMBUSTION

Fly ash is one of the key pathways for toxic metals from coal combustion power plants to be introduced into the environment. The presence of fly ash in the nearby soil layer indicates the escape of these contaminants from power plants. Discovering direct evidence of contamination from fly ash in the soil and sediments is not easy as fly ash particles are altered due to weathering and biological interference, after deposition.

Soil samples were collected from a wetland in the proximity of a coal combustion power plant located in Chesterfield County, VA. X-ray Fluorescent (XRF) analysis of the bulk soil samples shows high concentrations of iron (13.45 – 9.07%), aluminum (10.33 – 8.09%), and sulfur (0.74 – 0.046%). Most of the samples contained high concentrations of lead (510 - 130 ppm) and chromium (178 – 164 ppm).

The samples were analyzed further with a high sensitivity SEM-EDS to search for further physical evidence and to identify preserved micron-sized fly ash in the soil samples. The following concentrations were found: silicon (14.4- 0.7%), aluminum (19.9-17.59%), iron (14.57-4.9%) and titanium (4.9-0.64%). The micron-sized fly ash particles were probably transported to the nearby wetlands due to washing out from the fly ash dump adjacent to the power plant.