With recent emphasis of agricultural wind erosion and associated dust emissions impacting downwind air quality, there is an increased need for a prediction method to estimate dust emissions and ambient particle concentrations on a wind event basis. Most current wind erosion methods predict average annual or seasonal erosion amounts, and only very approximate estimates of suspended dust emissions are available. A project in the Columbia Plateau of eastern Washington State was initiated to develop an empirical method to estimate dust emissions for this region. Field measurements, wind tunnel tests, and laboratory analyses were combined to provide an empirical wind erosion equation and a related vertical flux dust emission model. While based on measured data, the model has not been independently verified. When combined with a transport-dispersion model and calibrated, estimates of downwind particulate concentrations compared reasonably with those measured.

Microbial diversity was characterized in mining-impacted soils collected from two abandoned uranium mine sites, the Edgemont and the North Cave Hills, South Dakota, using a high-density 16S microarray (PhyloChip) and clone libraries. Characterization of the elemental compositions of soils by X-ray fluorescence spectroscopy revealed higher metal contamination including uranium at the Edgemont than at the North Cave Hills mine site. Microarray data demonstrated extensive phylogenetic diversity in soils and confirmed nearly all clone-detected taxonomic levels. Additionally, the microarray exhibited greater diversity than clone libraries at each taxonomic level at both the mine sites. Interestingly, the PhyloChip detected the largest number of taxa in Proteobacteria phylum for both the mine sites. However, clone libraries detected Acidobacteria and Bacteroidetes as the most numerically abundant phyla in the Edgemont and North Cave Hills mine sites, respectively. Several 16S rDNA signatures found in both the microarrays and clone libraries displayed sequence similarities with yet-uncultured bacteria representing a hitherto unidentified diversity. Results from this study demonstrated that highly diverse microbial populations were present in these uranium mine sites. Diversity indices indicated that microbial communities at the North Cave Hills mine site were much more diverse than those at the Edgemont mine site.

In this study, we have introduced a biological dust control technique utilizing a naturally occurring soil microorganism, Sporosarcina pasteurii, which is capable of inducing calcium carbonate precipitation in the environment. To evaluate the dust suppressive potential of this microbial calcite, S. pasteurii was suspended in medium and applied to locally available sand. The treated soil samples were tested via a wind tunnel at intervals and mass losses were measured. In order to identify the optimum conditions of microbial dust suppression, we examined the effects of: a) the concentration of S. pasteurii, b) the temperature and humidity, and c) the soil preparation method (washed or unwashed). Both types of the soil samples treated with S. pasteurii formed a crust-like layer on the surface and showed a significant reduction in mass loss. Our study demonstrated the potential of this microbiallymediated process as an effective, environmentally friendly means of airborne fugitive dust control.

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