Environmental Effects of Pollutants from Coal Combustion: 1. The Four Corners Power Plant, Farmington, NM

摘要

Cloud condensation nuclei (CCN: particles active at less than 1% supersaturation) were found to be formed in the plume of the Four Corners power plant and CCN concentrations were often found to increase with increasing distance of up to 80 km from the power plant. Condensation nuclei (CN: particles active at 300% supersaturation) were also formed. The greatest concentrations of CN were found at distances of less than 40 km downwind, although the total CN population was greater at the greater distances, thus indicating an increase in mean particle size with increasing time of reaction, i.e., increasing distance. This is corroborated by the size distribution measurements showing a gradually increasing modal radius and increasing concentrations of the accumulation mode with increasing distances. Most particles are sulfates; most larger particles are fly ash. Fly ash particles are found to adsorb sulfate, thus becoming activated as CCN. The relationship between concentration of surface-deposited sulfate and inverse particle diameter suggests that sulfur is adsorbed and oxidized on refractory fly ash in the high temperature zone of the boiler. Little or no accumulation of sulfur and/or chlorine could be detected after the fly ash became airborne.