Source Sampling of Particulate Matter Emissions from Cotton Harvesting: System Field Testing and Emission Factor Development

Abstract

Emission factors are used in the air pollution regulatory process to quantify the mass of pollutants emitted from a source. Accurate emission factors must be used in the air pollution regulatory process to ensure fair and appropriate regulation for all sources. Agricultural sources, including cotton production operations, are not exempt from air quality regulation. Particulate matter (PM) emissions from agricultural operations are difficult to quantify due to the physical characteristics of emission source, particle size distribution of the PM emitted, and natural dispersion of emissions into the environment. These factors have introduced substantial amounts of uncertainty into previous emission factor estimates from cotton harvesting operations. This article documents a new protocol for measuring PM emissions onboard a cotton harvester using a novel source sampling system and reports total suspended particulate (TSP), PM10, and PM2.5 emission factors developed using the new protocol. The average systematic uncertainty of the measured emission rates is 2.78%. Significant correlations were observed between test plot yield and TSP, PM10, and PM2.5 emission rates, indicating that it is appropriate to report emission factors on a mass of PM emitted per mass of cotton harvested basis. The area-based TSP, PM10, and PM2.5 emission factors developed in this work are 1.64, 0.55, and 1.58E-03 kg ha-1, respectively (1.46, 0.49, and 1.41E-03 lb ac-1, respectively). In terms of PM emitted per harvested cotton mass, the TSP, PM10, and PM2.5 emission factors are 0.22, 0.07, and 2.15E-4 kg bale-1, respectively (0.48, 0.15, and 4.74E-4 lb bale-1, respectively).