October 1, 2017.
The Landscape Evolution Observatory (LEO) at Biosphere 2 near Tucson, AZ is a unique and singular experimental setup in which scientists are able to tackle large-scale earth science questions involving soil formation, nutrient cycling, and chemical weathering in a way that is unavailable in true Earth systems. Three identical zero-order 330 m^2 drainage basins are each filled with 330 m^3 of ground basaltic tephra with a loamy sand texture sourced from northern Arizona for its capacity for carbon sequestration. To obtain information on accumulation of carbon/nitrogen on LEO slopes as a result of biological and abiotic processes, six soil cores distributed across three locations in the LEO hillslopes were collected and six depths including 5, 20, 35, 50, and 85 cm were analyzed in a Shimadzu total carbon and nitrogen analyzer. Seepage samples from biweekly rains on LEO from the same time period were collected from a subset of the 1500 total available samplers and analyzed for pH, conductivity, carbon, nitrogen, cation, and anion concentrations. A cross section of the LEO hillslopes provides data which can be combined with similar data along the flow path; this allows for the analysis of the effects of hydrologic weathering on total soil nitrogen and carbon. Nitrogen is usually found in higher concentrations closer to the top of the slopes, perhaps due to microbial activity or chemical weathering of the basalt.
NASA Jet Propulsion Laboratory (JPL)
The 2017 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (www.chevron.com), the National Marine Sanctuary Foundation (www.marinesanctuary.org), the California State University Office of the Chancellor, and California Polytechnic State University, in partnership with NASA Jet Propulsion Laboratory.