GAS EMISSIONS, TARS, AND SECONDARY MINERALS AT THE RUTH MULLINS COAL MINE FIRE

The Ruth Mullins coal mine fire, Perry County, Kentucky, has been the subject of several field investigations over the last three years. In November 2009–February 2010 field investigations we measured gas emissions, collected minerals and tars, and characterized the nature of the fire. Vents exhibiting the greatest gas flux (>100,000 mg/s/m²) are those with the largest amount of minerals and tars. Vents with moderate gas flux (10,000-100,000 mg/s/m²) are less likely to contain condensate minerals, but are collocated with tar and vents with the lowest flux (<10,000 mg/s/m²) generally lack both minerals and tars. Aliphatic compounds present in the gasses include C1-C9 compounds; aromatics detected include BTEX. Diffuse-CO₂ emissions are concentrated along the fracture zones overlying abandoned mine works; the area of peak diffuse flux is correlative to the trend of the collapsed portal that forms vent 5. The greatest vent emissions were also recorded at vent 5. The snow-melt zone mapped in January overlies the areas of peak diffuse-CO₂ emissions measured in November; together they delineate the zone of active combustion. Comparison of greenhouse gas emissions from the two sources shows that vent emissions exceed diffuse emissions. The highly fractured, quartz-cemented roof rock funnels the majority of emissions toward the vents. Significant decreases are seen in estimates of yearly greenhouse emissions based on data gathered from November to February, with estimates from November significantly exceeding any previously published estimates. For example, September 2009 estimates from vent 3 alone indicated that 19±7.5 T CO₂/yr were emitted while the November 2009 estimates were 1800±690 T/yr. Barometric pressure was lower in November than September. This implies that there many factors influencing the seasonal variations to fire emissions and that more frequent monitoring will be necessary to derive accurate estimates of coal fires’ contribution to the carbon budget.