Near-Field Dust Exposure from Cotton Field Tilling and Harvesting
- April L. Hiscox *a,
- David R. Millera,
- Britt A. Holménb,
- Wenli Yangc and
- Junming Wangd
- a Natural Resources Management and Engineering, The Univ. of Connecticut, 1376 Storrs Rd. U-4087, Storrs, CT 06269
b School of Engineering, The Univ. of Vermont, Votey Bldg. Rm. 213B, Burlington, VT 05405
c Crocker Nuclear Lab., One Shields Ave., Univ. of California, Davis, CA 95616
d Plant and Environmental Sciences, New Mexico State Univ., Dep. 3Q, Las Cruces, NM 88003
The frequency and intensities of dust exposures in and near farm fields, which potentially contribute to high intensity human exposure events, are undocumented due to the transient nature of local dust plumes and the difficulties of making accurate concentration measurements. The objective of this study is to measure near-field spatial concentrations of the dust plumes emitted during tilling and harvesting of an irrigated cotton field outside of Las Cruces, NM (soil class: fine-loamy, mixed, superactive, thermic Typic Calciargid). A comparison of remote lidar measurements of plumes emitted from cotton field operations with in situ samplers shows a strong agreement between the two techniques: r 2 = 0.79 for total suspended particulates (TSP) and r 2 = 0.61 for particulate matter with diameter less than or equal to 10 μm (PM10). Plume movement was dependent on the short-term wind field and atmospheric stability. Horizontal spread rate of the plumes, determined from lidar measured Gaussian dispersion parameters, was less than expected by a factor of 7. Thus, in-plume downwind concentrations were higher than expected. Vertical dispersion was dependent on the rise of “cells” of warm air convecting off the soil surface. On a windy day, discing the field showed TSP and PM10 concentrations at the source itself of up to 176 μg m−3 and 120 μg m−3, respectively. These resulted in in-plume peak TSP concentrations of about 1.22 μg m−3 at 10 m downwind and 0.33 μg m−3 at 100 m downwind. The measured concentrations highlight a potential exposure risk to people in and around farming operations.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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