Regional sources control dust in the mountain critical zone of the Great Basin and Rocky Mountains, USA

Abstract

Mountain environments are profoundly impacted by the deposition of mineral dust, yet the degree to which this material is far-traveled or intra-regional is typically unclear. This distinction is fundamental to model future changes in mountain geoecosystems resulting from climatic or anthropogenic forcing in dust source regions. We address this question with a network of 17 passive dust samplers installed in primarily mountain locations in Utah, Nevada, and Idaho between October, 2020 and October 2021. For each collector, the dust deposition rate was calculated, and the physical and chemical properties of the dust were constrained. Results were combined with backward trajectory modeling to identify the geologic characteristics of the area over which air passed most frequently in route to each collector (the ‘hot spot’). Dust properties differ significantly between collectors, hot spots for many collectors are spatially discrete, and the dominant geologies in the hot spots corresponding to each collector vary considerably. These results support the hypothesis that the majority of the dust deposited in the areas we studied is sourced from arid lowlands in the surrounding region.