Gas emissions, minerals, and tars associated with three coal fires, Powder River Basin, USA
Ground-based surveys of three coal fires and airborne surveys of two of the fires were conducted near Sheridan,Wyoming. The fires occur in natural outcrops and in abandoned mines, all containing Paleocene-age subbituminous coals. Diffuse (carbon dioxide (CO2)only)andvent(CO2, carbon monoxide (CO), methane, hydrogen sulfide(H2S), and elemental mercury) emission estimates were made for each of the fires. Additionally, gas samples were collected for volatile organic compound (VOC) analysis and showed a large range in variation between vents. The fires produce locally dangerous levels of CO, CO2,H2S, and benzene, among other gases. At onefire in an abandoned coal mine, trends in gas and tar composition followed a change in topography. Total CO2 fluxes for the fires from airborne, ground-based, and rate of fire advancement estimates ranged from 0.9 to 780 mg/s/m2andare comparable to other coal fires worldwide. Samples of tar and coal-fire minerals collected from the mouth of vents provided insight into the behavior and formation of the coal fires.
Science of the Total Environment, 420 (March 2012), 146-159.