MP18 Environmental Fate of Mercury
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(OWN-1117-662595) Spatial Distribution of Mercury in an East Texas Coal Seam.

Paul, J¹, Ownby, D¹, ¹ Stephen F. Austin State University, Nacogdoches, TX, USA

ABSTRACT- With new mercury release regulations a possibility, it is imperative for power companies to manage Hg content in incoming coal. Therefore, understanding Hg distribution throughout a coal seam is important for coal burning electrical utilities in order to evaluate Hg emission reduction programs. One potential option would be to selectively mine low Hg coal from within a seam. This research measured Hg concentrations in three detailed (0.1 ft sections) and 28 regular cores (sectioned on visual mineral/maceral content changes) from an East Texas coal seam. Prior to analysis of lignite coal for Hg, ASTM Method 6414-01 was optimized for our Perkin Elmer AAnalyst FIAS system using NIST SRM 2682b (subbituminous), EPRI ES-5 (lignite), and CANSPEX 2003-1 (lignite) standard materials. Perkin Elmer's recommended conditions for flow injection systems (1.1% SnCl₂ in 3% HCl) were used for analysis; resulting in improved sensitivity. An additional modification of digestion acid concentrations was evaluated by altering ASTM's recommended 6 mL HCl: 2 mL HNO₃ stepwise to 1.5 ml HCl: 5 mL HNO₃ to optimize sensitivity. Upon altering ASTM 6414-01, average recoveries of 97%, 108%, 100% were achieved for the standard materials listed above. Upon analysis of the lignite seam, there was no correlation of Hg concentration with depth. In detailed cores, differences of over 100 ug Hg/kg were commonly observed in adjacent sections. A 3-D geospatial model of Hg distribution within the coal seam further illustrates heterogeneity found throughout the mining area. The effect of ash content, total organic carbon, and pyritic sulfur on Hg concentrations will also be discussed.

Key words: coal, mercury, GIS