Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/11/2007
Publication Date: 6/20/2007
Citation: Wanjura, J.D., Shaw, B.W., Parnell, C.B., Capareda, S.C., Faulkner, W.B. 2007. A preliminary particulate matter emission factor from cotton harvesting. In: Proceedings of the National Cotton Council Beltwide Cotton Conferences, January 9-12, 2007, New Orleans, Louisiana. 2007 CDROM. p. 1511-1541. Interpretive Summary: Cotton producers in some states across the cotton belt are faced with increasing regulatory pressure from state air pollution control agencies. The lack of accurate particulate matter (PM) emission factors has resulted in the identification of agricultural operations as a significant source of PM10 in California. Moreover, recent modifications to the National Ambient Air Quality Standard for PM2.5 will likely result in further regulatory pressure on cotton producers due to the lack of emission factors. Agricultural producers are required to comply with permitting rules which document the amount of PM emissions from their operation. Producers in California are also required to submit a plan identifying the conservation management practices they will employ to help reduce the fugitive PM emissions from their operation. Air pollution regulators in California allow cotton producers to claim the use of six-row harvesting equipment rather than two-row equipment as a conservation management practice. The objective of this manuscript is to report the first year findings of a two-year study to develop a science-based PM emission factor for modern picker type cotton harvesting machines. The results of this study indicate that the overall emission factor of cotton harvesting operations is lower than the current emission factor used by air pollution regulators in California. The PM10 and PM2.5 emission factors developed for the six-row harvester from the work of this study are on the order of 0.66 kg/ha and 5 g/ha, respectively. Differences in the level of PM emissions between two-row and six-row harvesting equipment were observed. The PM10 and PM2.5 emission factors developed for the two-row harvester are on the order of 0.89 kg/ha and 14 g/ha,respectively. A novel source sampling system was designed and successfully implemented on the six-row harvester to directly measure the PM emission concentration from the harvester. The emission factor results from the source sampling system exhibit a high level of measurement precision. The PM10 and PM2.5 emission factors developed from the four tests using the source sampling system are 45 and 0.15 g/ha, respectively. Further development and testing with the source sampling system is planned for 2007.
Technical Abstract: Particulate matter (PM) sampling of cotton harvesting operations at three locations in Texas was conducted during the summer of 2006. PM emissions generated by a two-row (John Deere Model 9910) and six-row (John Deere Model 9996) cotton picker were measured at each sampling location. The PM emissions from the two-row and six-row machines were measured using a protocol employing collocated low volume total suspended particulate (TSP) and PM10 samplers upwind and downwind of the operation. The concentrations measured by the collocated samplers were used in the Industrial Source Complex Short Term version 3 (ISCST3) dispersion model to back calculate the emission fluxes from the source (harvesting operation). The resulting TSP emission fluxes were converted to PM10 and PM2.5 emission factors using the results of particle size distribution (PSD) analyses. The mean PM10 emission factors for the two-row and six-row harvesters resulting from this protocol are 0.89 plus or minus 0.20 and 0.66 plus or minus 0.27 kg/ha, respectively (0.79 plus or minus 0.18 and 0.59 plus or minus 0.24 lb/ac, respectively). Similarly, the mean PM2.5 emission factors for the two-row and six-row harvesters resulting from this protocol are 0.014 plus or minus 0.011 and 0.005 plus or minus 0.043 kg/ha, respectively (0.012 plus or minus 0.01 and 0.004 plus or minus 0.04 lb/ac, respectively). Large uncertainty in the emission factors developed using the upwind/downwind sampler protocol was observed. Thus, the differences in the PM10 and PM2.5 emission factors for the two-row and six-row harvesters are not statistically significant (alpha = 0.05). However, the PM emission factors from the six-row harvester trend lower than the emission factors from the two-row machine. In addition, a novel source sampling system was developed to measure the PM emission concentration from the six-row harvester. The resulting emission concentrations were converted to emission factors and compared to the emission factors resulting from the collocated sampler/ISCST3 protocol. Emission factor data for the six-row harvester from the source sampling system was collected at the first two sampling locations. The PM10 and PM2.5 emission factors resulting from the source sampling system on the six-row harvester are 45 and 0.15 g/ha, respectively. An analysis of the emission factor data from the source sampling system indicates that it is more appropriate to report PM emission factors on a mass of PM per unit area basis than on a mass of PM per bale harvested basis.