EOLIAN DUST DEPOSITION IN A COLD DESERT ECOSYSTEM: COMPARING AEOLIAN DEPOSITION RATES IN AGRICULTURAL WITH NON-AGRICULTURAL AREAS

Dust and eolian deposits are critical to soil formation, climate, biogeochemical cycles, and ocean productivity. During transport, dust can present significant hazards for aviation, driving, and human health. Organisms and metals present in the dust can negatively affect human health and increase the occurrence of certain diseases, posing a threat to air and water quality.

Rising dust fluxes throughout the 20th century, are linked to climate change and altered land use by human activities. Agriculture contributes ~ 10% to 50% of total global dust emissions. The goal of this study is to understand the spatial, temporal, and chemical variability in dust in different land uses (irrigated vs. non-irrigated sites) in a semi-arid region. Dust samples were collected seasonally from April 2022 to April 2023 from 2-meter-high passive dust traps in Reynolds Creek Experimental Watershed (RCEW) and agricultural lands at the USDA Northwest Irrigation and Soils Research Lab (NWIS at Kimberly) in southwestern Idaho. We installed 12 new passive dust collectors at the Kimberly site and 19 previously installed passive dust collectors in RCEW. This study examines 1) the flux of dust from native and agricultural dryland sites in Idaho, 2) the geochemical signature of dust, and 3) possible dust sources in native sagebrush and agricultural sites.

From April 2022-April 2023, the dust deposition rate varied seasonally in both study areas. The highest dust flux was from July-Nov 2022 at both the agricultural site and the native mountainous watershed. While the dust flux rates at both locations slightly follow the same pattern seasonally, they displayed strong variations in the amount of monthly and annual dust flux. Notably, the annual dust flux rate at the irrigated site (50.2 g/m²/year) is 7.6 times higher than the annual dust flux rate at the native site (6.6 g/m²/year). At RCEW, dust samples are highly elevated in Copper and Zinc (~3-4 times higher) as compared to the average composition of the upper continental crust. Elements such as Zinc, Eoropium, Lutetium, and Terbium are highly elevated relative to the average composition of the upper continental crust in the irrigated site.