Author
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Van Pelt, Robert - Scott |
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Zobeck, Teddy |
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Submitted to: Environmental Monitoring and Assessment
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/7/2007 Publication Date: 7/1/2007 Citation: Van Pelt, R.S., Zobeck, T.M. 2007. Chemical constituents of fugitive dust. Environmental Monitoring and Assessment. 130(1-3):3-16. Interpretive Summary: Fugitive dust from wind erosion and agricultural operations has recently come under increasing scrutiny. In some areas of the country, fugitive dust emissions from agricultural operations have become a regulatory issue. Very little is known about the contribution of agriculturally-based fugitive dust to the over-all transport and deposition of plant nutrients and trace elements into adjacent watersheds and population centers. We sampled source soils with known erosion and deposition histories, dust from the air cleaners of agricultural tractors, airborne sediments above an actively eroding field, and the sediments from 50 ' 75 years of accumulation in area attics to determine present and historical loads, the chemical constituents of fugitive dust produced by wind erosion of fallow fields and by tillage and harvesting operations, and transformations and additions to the dust as it is transported into a semi-urban setting. We found that fugitive dust of agricultural origin contributes very little to the total chemical deposition in an area when compared to other anthropogenic sources such as industry and vehicle traffic. Technical Abstract: Wind erosion selectively winnows the fine, most chemically concentrated portions of surface soils and results in the inter-regional transport of fugitive dust containing plant nutrients, trace elements and other soil-borne contaminants. We sampled and analyzed surface soils, sediments in transport over eroding fields, and attic dust from a small area of the Southern High Plains of Texas to characterize the physical nature and chemical constituents of these materials and to investigate techniques that would allow relatively rapid, low cost techniques for estimating the chemical constituents of fugitive dust from an eroding field. From chemical analyses of actively eroding sediments, it would appear that Ca is the only chemical species that is enriched more than others during the process of fugitive dust production. We found surface soil sieved to produce a sub-sample with particle diameters in the range of 53 ' 74 microns to be a reasonably good surrogate for fugitive dust very near the source field, that sieved sub-samples with particle diameters < 10 microns have a crustal enrichment factor of approximately 6, and that this factor, multiplied by the chemical contents of source soils, may be a reasonable estimator of fugitive PM10 chemistry from the soils of interest. We also found that dust from tractor air cleaners provided a good surrogate for dust entrained by tillage and harvesting operations if the chemical species resulting from engine wear and exhaust were removed from the data set or scaled back to the average of enrichment factors noted for chemical species with no known anthropogenic sources. Chemical analyses of dust samples collected from attics approximately 4 km from the nearest source fields indicated that anthropogenic sources of several environmentally important nutrient and trace element species are much larger contributors, by up to nearly two orders of magnitude, to atmospheric loading and subsequent deposition than fugitive dust from eroding soils. |
