CARBON SEQUESTRATION IN A COLD DESERT ECOSYSTEM: USE OF GEOCHEMICAL TECHNIQUES TO DETERMINE CALCIUM PROVENANCE AND SOIL CARBONATE FORMATION IN DRYLAND
Dust or loess is a well-known source of Ca, which can lead to the formation of SIC in arid and semi-arid areas. So too is irrigation water when applied in dryland agricultural sites. However, (1) the provenance of Ca is understudied in many native cold desert regions, and (2) the proportion of Ca added to the soil from dust, irrigation water, or the underlying parent material is not clear, which prevents accurate determination of net carbon storage as SIC in these ecosystems.
The goal of this study is to determine the provenance and amount of Ca from natural and anthropogenic sources using isotopic and mass balance techniques, and assess how these sources contribute to the formation of pedogenic carbonate in drylands. Dust samples have been collected seasonally since summer 2021 from installed dust traps in Reynolds Creek Experimental Watershed and agricultural lands at the USDA Northwest Irrigation and Soils Research Lab (NWIS at Kimberly) in southwestern Idaho. Sample processing has begun for analyses, which include organic and inorganic carbon, x-ray fluorescence (XRF) spectroscopy, coupled plasma-optical emission spectrometry (ICP-OES) for major ions, and strontium isotope ratio (87Sr/86Sr) with multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) at the University of Texas at El Paso (UTEP).