Using the Chemical Signature of Dust to Understand Soil Development and Carbon Storage in Soils

Idaho’s tradition for famous potatoes is rooted in dust: long-term addition of dust creates rich, fertile soils. While fine air-borne silt provides nutrients and water-holding capacity important for crops, dust is also an important but understudied aspect of soil development. On a global scale, soils provide an important storage location for carbon, and constitute a reservoir for atmospheric carbon dioxide. Plants, microbes, and microorganisms are responsible for organic carbon formation, but inorganic carbon requires the presence of mobile Ca ⁺ ions to mix with water and CO ₂ from the atmosphere to produce calcium carbonate CaCO ₃ . Natural traps provide a unique opportunity to analyze the geochemistry of pure dust in the absence of pedogenesis, or soil-formation. We collected dust from crevices in rhyolite, basalt and granite outcrops, and compared major element oxides and trace element geochemistry using Inductively Coupled Plasma Mass Spectrometry (ICPMS). This study (1) explores the chemical composition of pure dust as a primary soil forming material, (2) compares dust heterogeneity among different lithologies and throughout the watershed, and (3) constrains the origin of dust.