Fine particle emission potential from loam soils in a semiarid region

Fugitive dust emission from agricultural soils is a concern in the U.S. Inland Pacific Northwest because emission of particles with an aerodynamic diameter =10 μ m (PM10) and ≤2.5 μ m (PM2.5) are regulated by the U.S. Environmental Protection Agency (EPA) as air pollutants. The objective of this study was to characterize the PM10 and PM2.5 emission potential of soils in the region. Soil from the upper 3-cm layer of the profi le was collected from fi ve major soil types in southeastern Washington. Soil samples collected from the fi eld were placed inside a wind tunnel to simultaneously measure PM10 and PM2.5 emissions at three wind speeds. Dispersed soil analysis indicated that the sand and silt content, respectively, ranged from 17 to 68% and 23 to 66% while nondispersed soil analysis revealed the PM10 and PM2.5 content averaged 3.7 and 1.2%, respectively, across the fi ve soil types. Emissions of PM10 and PM2.5 were greatest for Warden sandy loam (coarse-silty, mixed, superactive, mesic Xeric Haplocambids) and lowest for Walla Walla silt loam (coarse-silty, mixed, superactive, mesic Typic Haploxerolls). During the 5 min wind tunnel test at the highest wind speed (18 m s -1), loss of sediment, PM10 and PM2.5 for the fi ve soils ranged from 113 to 8039 g m -2, 0.4 to 11.0 g m -2, and 0.1 to 6.0 g m -2, respectively. Although the PM10/sediment loss ratio diff ered among soils, there was no diff erence in the PM2.5/sediment loss ratio across soils. Our results suggest that the emission potential varies for windblown soils found across the Inland Pacific Northwest.