SOIL SURFACE CONDITIONS OF AN ACTIVE COAL MINE FIRE, CENTRALIA PA

After burning for almost 40 years, the underground mine fire in Centralia, Pennsylvania has greatly modified soil conditions and temperatures above the fire. Combustion gases condense rapidly when cooled at the surface introducing heavy metals and nutrients to the soil. Temperatures reach up to 119°C along the advancing front. Relationships between extreme temperatures and ammonia, nitrate, and phosphate concentrations are studied to characterize the processes of nutrient enrichment and nutrient cycling in high temperature soil. A study site is located on the encroaching edge of fire. Twenty-seven borings up to 1 meter deep were collected and samples were measured for moisture content, pH, ammonia, nitrate and phosphate. Temperatures for each sample were measured in-situ. Central Pennsylvania soils are naturally acidic and pH levels range from 3.5 to 6.0 on site. Soil moisture levels fall between 15 and 40 percent by mass, and relationships between temperature and moisture content are questionable. However, the highest concentrations of nitrate, ammonia and phosphate exist where soil temperatures exceed 30°C. It is not surprising that a mine fire causes high temperature soils. We conclude that gas emissions alter the chemical composition of the soil making it nutrient rich. If the fire were to cease, vegetative and microbial communities would likely thrive on the abundance of ammonia, nitrate and phosphate.