- Copyright ©2003. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.
High concentrations of stray carbon dioxide in buildings are an emerging environmental hazard in some areas of the Appalachian coalfields. In western Pennsylvania, potentially lethal concentrations of CO2 (>25%) and low volumes of O2 (<10%) have caused several private homes to become uninhabitable. The CO2 is primarily anthropogenic, although the specific source is commonly uncertain. Carbon isotope geochemistry provides the most useful technique for identifying the specific gas source.
Carbon dioxide derived from organic substrates by microbial activity is enriched in 12C, whereas CO2 derived from carbonate materials is enriched in 13C. The activity of 14C can support the identification of geologically recent microbial gas generation. Ground-water chemistry can support interpretations of an inorganic CO2 source based on stable-isotope data. Case studies from western Pennsylvania demonstrate the utility of isotopic analyses in identifying specific sources of stray CO2 in buildings.
Christopher D. Laughrey is a senior geologic scientist with the Pennsylvania Geological Survey, where he has worked since 1980. He worked as a geophysical analyst for the Western Geophysical [Company] in Houston, Texas, before taking his present position in Pittsburgh, Pennsylvania. He also teaches sandstone petrology at the University of Pittsburgh. Laughrey's research interests include isotope and organic geochemistry, carbonate and clastic petrology, and borehole geophysics.Fred Baldassare is a hydrogeologist with the Pennsylvania Department of Environmental Protection. He has 15 years experience investigating incidents of subsurface stray gas migration. Fred currently serves as a project manager providing technical reviews of chemical and hydrological data generated at industrial sites with ground-water contamination. He also serves as an advisor on the regulations and technical guidance for Pennsylvania's Land Recycling Program. Fred's current research interests include natural gas isotope geochemistry and contaminant fate and transport.