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FORT HALL SOURCE APPORTIONMENT STUDY (FINAL REPORT)
Citation:
Willis, R. D. AND W. D. Ellenson. FORT HALL SOURCE APPORTIONMENT STUDY (FINAL REPORT). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-99/103 (NTIS PB2001-100329), 1999.
Description:
Air quality monitoring on the Fort Hall Indian Reservation has revealed numerous exceedances of the National Ambient Air Quality Standard (NAAQS) for 24-h averaged PM10 mass. Wind-directional analysis coupled with PM10 measurements have identified the FMC elemental phosphorus plant as the major source of PM10. This study attempts to identify specific sources or operations within the FMC complex that contribute to the PM10 violations. Data used to identify FMC emission sources were collected at two downwind and one background monitoring sites and include 24-h PM10 concentrations, met data (wind speed and wind direction), 24-h PM2.5 and coarse (PM10 minus PM2.5) mass and elemental concentrations, organic and elemental carbon data on selected ambient samples, continuous PM10 and PM2.5 measurements, and electron microscopy characterization of individual source and ambient particles. A limited source sampling effort was conducted, which yielded qualitative source profiles of selected FMC sources or processes. Ambient data show that PM10 is dominated by the fine fraction (PM2.5) but that both fine and coarse-fraction aerosols are generally required to produce an exceedance. PM10 mass during exceedance events is split approximately evenly (with significant mass unaccounted for) between fine-fraction phosphate, believed to be emitted predominantly from the ground and elevated CO flares, and coarse-fraction Ca and Si-rich dust believed to come from numerous sources at FMC. Short but intense "miniflush" events appear to be less important than steady-state CO flaring as it relates to 24-h averaged PM10. Ambient and source concentrations of thallium and rubidium are used to estimate upper limits on contributions from the calciners (<9% of the total fine mass) and furnace tapping (<9% of fine mass), respectively. In addition to extremely high P concentrations, unusually high concentrations of anthropogenic elements Se, Cd, V, Cr, Ni, Hg, and Tl were measured at the downwind monitoring sites when winds are from FMC. Efforts to provide more definitive source apportionment results are limited, especially for the coarse fraction, by the lack of quantitative and representative source profiles.
The U.S. Environmental Protection Agency through its Office of Research and Development managed and partially funded the research described here under Contract 68-D5-0049 to ManTech Environmental Technology, Inc. Principal funding was provided by Region 10 of the U.S. Environmental Protection Agency through Work Assignments III-072 and IV-107. This document has been submitted for Agency peer and administrative review and approved for publication as an EPA document. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.