Predicting PM_(10) and PM_(2.5) Dust Emissions From Agricultural Wind Erosion

摘要

Many urban areas, particularly in the Western U.S., have experienced concentrations of fugitive dust particulates from up-wind sources, which exceeded federal health standards. In many of these cases, it was evident that a significant amount of this material was generated on agricultural fields during wind erosion, entrained and transported in the regional air mass. Thus both the soil resource and the air quality in downwind urban regions are degraded. The Pacific Northwest Columbia Plateau of eastern Washington, northern Oregon and northern Idaho is a broad, relatively flat loessial plateau of over 136,000 square kilometers which was selected for a regional scale study. This area is characterized by very erosive soils, mostly dryland farming and several urban regions experiencing air quality concerns due to particulates. The loess soils of the study region are highly erodible and contain significant amounts of free dust particulates less than 10 and less than 2.5 microns diameter, which readily become suspended and travel many kilometers downwind during wind erosion events. Soil, vegetation and climatic variables were combined into empirical wind erosion and fugitive dust emission relationships. The emissions model was combined with a comprehensive transport/dispersion model to predict downwind urban concentrations and evaluate the relative effectiveness of selected farm-level controls.