Study on Calcium Deposition Shows Increasing Dust Storms in American West

Novus participants Drs. Janice Brahney and Ash Ballantyne of the University of Colorado, Boulder, along with colleagues Drs. C. Sievers and Jason Neff (also of UC-Boulder) recently published a study on calcium deposition across the continental United States.

Their data showed increases in calcium deposition over the last 17 years resulting from increased soil aerosols (dust) across portions of the midwest, the inter-mountain west, and the northwest United States. These increases were linked to a combination of climatic and anthropogenic impacts, specifically increased aridity and wind transport, and increased area and intensity of human impacts. Increases in dust storms could have important biogeochemical and ecological ramifications for both the region where the dust originates and where it is deposited.

Dr. Brahney’s paper was highlighted in an article by the University of Colorado, Boulder, and another article by National Geographic. The citation information and abstract of the paper are below, and the full article can be obtained here.

Article Citation:

Brahney J., A. Ballantyne, C. Sievers, J. Neff (2013) Increasing Ca2+ deposition in the western US: the role of mineral aerosols. Aeolian Research, DOI: http://dx.doi.org/10.1016/j.aeolia.2013.04.003

Article Abstract

Considerable research has focused on the role of industrial emissions in controlling the acidity of precipitation; however, much less research has focused on the role of mineral aerosols emitted from soils. According to data published by the National Atmospheric Deposition Network (NADP), over the past 17 years Ca2+ deposition has increased over large regions of the US. A trend analysis to determine regions of significant change in Ca2+ deposition revealed statistically significant increases in three broad regions within the western half of the country: the inter-mountain west, the midwest, and the northwest. We evaluated potential changes in sources of calcium to the atmosphere including soil erosion, industrial emissions, forest fires, and sea-salt aerosols to determine the cause of rising atmospheric calcium deposition. Based on our evaluation, the most parsimonious explanation for increased Ca2+ deposition is an increase in mineral aerosol emissions from within the western US. This explanation is corroborated by independent evidence showing increases in the frequency of dust storms and low-visibility days across regions of the western US. Furthermore, our analysis indicates that the increase in mineral aerosol emissions is most likely due to (1) increased aridity and wind transport and (2) increased area and intensity of upwind human activities. Changes in atmospheric dust concentrations can have important ecological implications through the contribution of acid neutralizing capacity to both precipitation and regions of deposition. Thus increased dust emissions have the potential to ameliorate the detrimental effects of acid precipitation on terrestrial ecosystems, though dust may exacerbate the impacts of air quality on human health.

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