Submitted to: International Conference on Aeolian Research
Publication Type: Abstract only
Publication Acceptance Date: 7/9/2010
Publication Date: 7/9/2010
Citation: Feng, G., Sharratt, B.S. 2010. Fine-Dust Entrainment Potential from Loessial Soils in the U.S. Pacific Northwest. International Conference on Aeolian Research. Interpretive Summary:
Technical Abstract: Particles with a mean aerodynamic diameter of <10 µm (PM10) and 2.5 µm (PM2.5) are stringently regulated by the U.S. Environmental Protection Agency as air pollutants. To estimate the impact of wind erosion on air quality and to aid in developing prediction capabilities of atmospheric PM2.5 concentration in the Columbia Plateau of the U.S. Pacific Northwest, knowledge must be acquired of the potential release of PM10 and PM2.5 from soils. The objective of this study was to characterize the PM2.5 and PM10 emission potential of loessial soils in the region. Soil samples from the upper 3 cm of the profile were collected from five major soil types across the Columbia Plateau. Dispersed and nondispersed particle and aggregate size fractions of the samples were respectively measured using a laser diffraction instrument and sonic sieve. Soils were dried and placed inside a wind tunnel to assess PM2.5 and PM10 emissions at three wind speeds. PM2.5 and PM10 concentration and wind speed profiles above the eroding soil surface were respectively measured using nephelometers and pitot tubes. The five soil types were characterized by sand content that ranged from 72% to 86%, clay content that varied from 10% to 18% and a similar aggregate size distribution. PM2.5 and PM10 comprised 2.1 and 6.4% of the eroded sediment across soil types. The soil with the greatest fraction of sand was the most erodible while the soil with the smallest fraction of sand was the least erodible. Total sediment, PM10, and PM2.5 loss ranged from 113 to 8039 g m-2, 0.4 to 11 g m-2, and 0.08 to 5.99 g m-2 at the highest wind speed (18 m/s). The PM2.5/PM10 emission ratio ranged from 0.17 to 0.56 across soil types. These emission ratios have application in modeling PM2.5 concentrations in the Columbia Plateau.