WIT Press

Elemental Composition Of PM10 And PM2.5 In Ambient Air Downwind Of Agricultural Operations In California’s San Joaquin Valley


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O. F. Carvacho, L. L. Ashbaugh & R. G. Flocchini


Fugitive dust emissions from soil are thought to constitute a large fraction of the PM10 and PM2.5 inventory in California's San Joaquin Valley (SJV) and other western air basins, especially during dry periods. The major sources of these emissions are paved and unpaved roads, construction sites, windblown dust, and agricultural activities. Furthermore, PM10 and PM2.5 are considered to be among the most harmful of all air pollutants. When inhaled these particles evade natural defenses of the respiratory system and lodge deep in the lungs causing serious health problems. Some heavy metals in small particles have the tendency to donate electrons and to form basic oxides. Biologically, many metals are essential to living systems and are involved in a variety of cellular, physiological, and structural functions. But at high doses, many metals become toxic. The route of exposure may affect the dose and the site where the metal concentrates, and thus the observed toxic effect. In California’s San Joaquin Valley, agricultural operations are highly complex and potentially significant sources of PM10 and PM2.5, especially during late summer and fall. A series of experiments was conducted to measure PM10 and PM2.5 emissions with traditional array sampling from agricultural operations in San Joaquin Valley. The elemental analysis of PM10 and PM2.5 collected in the field samples was conducted using Proton Induced X-Ray Emissions (PIXE), Proton Elastic Scattering Analysis (PESA) and X-Ray Fluorescence (XRF) analytical techniques available in our laboratory. The composition of PM10 dust collected downwind of agricultural operations is different from the composition of the PM2.5 dust collected at the same time. The smaller particles are enriched in sulphur and in heavy metals. Keywords: PM10, PM2.5, fugitive dust, agriculture, particle speciation, elemental composition.


PM10, PM2.5, fugitive dust, agriculture, particle speciation, elemental composition.