Title: Particle size distribution of PM emitted from cotton harvesting Authors
|Parnell, JR., C - TEXAS A&M UNIVERSITY|
|Shaw, B - TEXAS A&M UNIVERSITY|
|Capareda, S - TEXAS A&M UNIVERSITY|
Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: July 12, 2006
Publication Date: March 15, 2007
Citation: Wanjura, J.D., Parnell, Jr., C.B., Shaw, B.W., Capareda, S.C. 2007. Particle size distribution of PM emitted from cotton harvesting. American Society of Agricultural and Biological Engineers. Paper No. 064168. Interpretive Summary: Cotton producers in some states across the U.S. are facing increased pressure from state air pollution regulatory agencies. Poor air quality in these areas caused regulators to focus on reducing agricultural emissions in an effort to improve regional air quality. Consequently, agricultural operations are now required to obtain operating permits and comply with regulations which require producers to implement management practices to reduce fugitive emissions. Further, proposed regulations by EPA based on the size and physical makeup of the dust emitted from agricultural operations will likely result in increased regulatory pressure without further objective, science based research. Little research has been conducted to quantify the nature and amount of dust emissions from agricultural operations, including cotton harvesting. The objective of this work was to investigate the physical parameters of the dust emitted from cotton harvesting operations. This effort is part of a larger project to quantify an accurate dust emission factor for cotton harvesting. The results of this work report the fractions of the total dust emitted by cotton harvesting that are made up by the currently regulated size indicators, PM10 and PM2.5. Also, the results report estimates for the fraction of organic and soil (crustal) based material which make up the dust emitted from cotton harvesting. The results presented in this manuscript will be critical in the appropriate regulation of cotton harvesting operations in the U.S. Further, these results will help to reduce increased production costs for cotton producers forced to install dust emission abatement systems as a result of regulations based on inaccurate emissions data.
Technical Abstract: Poor air quality in some areas of the U.S. has caused regulators to increase regulatory pressure on sources of air pollution. Historically, cotton producers have not been targeted by regulators to reduce emissions through mandatory implementation of particulate matter (PM) control strategies. However, the use of inaccurate PM emission factors for field operations (including cotton harvesting) has resulted in the identification of agricultural operations as a significant source of PM pollution in California. Little work has been conducted to accurately determine emission factors for PM10 and PM2.5 from cotton harvesting operations. Furthermore, no research has been conducted to characterize the physical parameters of the PM emissions from cotton harvesting in terms of the particle size distribution (PSD), particle density, and PM composition. Therefore, the work presented in this manuscript describes the results of an investigation into the physical parameters of the PM < 100 micrometers (um) contained in seed cotton samples taken from harvesting operations in Texas and New Mexico. It is anticipated that the PM < 100 um contained in harvested seed cotton samples will provide a representative sample from which to make inferences on the physical parameters of the PM emitted from the harvesting operation. PM was air-washed from seed cotton samples taken from two locations in Texas and New Mexico and was analyzed for particle density, PSD, and PM composition. The results of the particle density analysis indicate that PM air washed from the seed cotton samples has a particle density on the order of 2.24 ± 0.175 g/cm3. Significant differences in the particle density of the PM air washed from seed cotton samples were detected by location. PSD analyses indicate that the mean percent mass of the PM<100 um for PM10 and PM2.5 are on the order of 27.5 ± 4.91% and 8.1 ± 2.34%, respectively. No significant differences were observed between the samples by location or harvester type for percent PM10 or PM2.5. A compositional analysis of the PM air washed from the seed cotton samples indicates that soil material and plant material likely account for 78.7 ± 14.6% and 21.3 ± 14.6% of the PM <100 um contained in the seed cotton samples, respectively.