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The deposition of aeolian (windblown) dust is a global phenomenon with significant implications for terrestrial ecosystems. In particular, the geochemical flux of dust can be an important factor for biogeochemical cycling in soils and, in some settings, may influence ecosystem productivity and chemical weathering. To quantify the role of exogenous dust in soils, the flux and composition of dust must be compared with local soil forming factors. In general, the magnitude, particle size, and geochemical composition of dust vary regionally and are primarily dependent on the distance from dust source area. Each winter/spring the San Juan Mountains (SJM) receive a substantial flux of exogenous dust, which most likely...
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Snow cover duration in a seasonally snow covered mountain range (San Juan Mountains, USA) was found to be shortened by 18 to 35 days during ablation through surface shortwave radiative forcing by deposition of disturbed desert dust. Frequency of dust deposition and radiative forcing doubled when the Colorado Plateau, the dust source region, experienced intense drought (8 events and 39?59 Watts per square meter in 2006) versus a year with near normal precipitation (4 events and 17?34 Watts per square meter in 2005). It is likely that the current duration of snow cover and surface radiation budget represent a dramatic change from those before the widespread soil disturbance of the western US in the late 1800s that...
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Mineral aerosols from dust are an important influence on climate and on marine and terrestrial biogeochemical cycles. These aerosols are generated from wind erosion of surface soils. The amount of dust emission can therefore be affected by human activities that alter surface sediments. However, changes in regional- and global-scale dust fluxes following the rapid expansion of human populations and settlements over the past two centuries are not well understood. Here we determine the accumulation rates and geochemical properties of alpine lake sediments from the western interior United States for the past 5,000 years. We find that dust load levels increased by 500% above the late Holocene average following the increased...
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Dust deposition in the Rocky Mountains may be an important biogeochemical flux from upwind ecosystems. Seasonal (winter/spring) dust mass fluxes to the San Juan Mountains during the period from 2004 to 2008 ranged from 5 to 10 g m?2, with individual deposition events reaching as high as 2 g m?2. Dust deposited in the San Juan Mountains was primarily composed of silt- and clay-sized particles, indicating a regional source area. The concentrations of most major and minor elements in this dust were similar to or less than average upper continental crustal concentrations, whereas trace element concentrations were often enriched. In particular, dust collected from the San Juan Mountain snowpack was characterized by enrichments...
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