REFINEMENTS IN SOURCE PROFILES FROM COAL-FIRED UTILITY BOILERS BASED ON TRACE ELEMENT SOLUBILITY PERSPECTIVES

In the spring of 2006, the U.S. EPA conducted a study to update source profiles from coal-fired utility boilers. The host facility was a 125 MW, low sulfur (<0.7%), Eastern bituminous coal-fired utility boiler equipped with a cold-side electrostatic precipitator (ESP). Co-located sets of fine fraction (<2.5 micron mass median aerodynamic diameter) particulate matter samples were acquired on three separate days using a dilution sampler system (DSS) from stack sampling ports located at a ground elevation of approximately 40 meters. The DSS dilutes stack emissions (1:35) with clean ambient air, and provides sufficient residence time at near-ambient temperature and pressure to allow condensation and coagulation of particulate matter. While particulate samples were being collected, total gas phase mercury emissions were quantified using a Tekran series 3300 continuous emission monitoring system. The PM2.5 total metal concentrations were determined using energy dispersive x-ray fluorescence (ED-XRF). The water and dilute acid extractable metal concentrations were subsequently quantified using high resolution inductively coupled plasma mass spectrometry (HR-ICPMS). In combination, these total concentration as well as solubility based trace element and mercury emission profiles will produce new insights from source apportionment and environmental impact perspectives.