A Preliminary Particulate Matter Emission Factor from Cotton Harvesting

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 sixrow 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 ± 0.20 and 0.66 ± 0.27 kg/ha, respectively (0.79 ± 0.18 and 0.59 ± 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 ± 0.011 and 0.005 ± 0.043 kg/ha, respectively (0.012 ± 0.01 and 0.004 ± 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 (α = 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 sixrow 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.