- Who: Jon Chorover, Ph.D., University of Arizona
- What: Download the Flyer (pdf)
- Where: Building 66 Auditorium, hosted by Peter Nico
- When: 10:30 am to 12:00 noon, February 21, 2014
- Why: About the Distinguished Scientist Seminar Series
Jon Chorover is Professor and Chair in the Department of Soil, Water and Environmental Science at the University of Arizona (UA). He received his M.S. (Forest Science), and Ph.D. (Soil Science) from UC Berkeley, worked as an NSF postdoctoral fellow in Analytical Chemistry at University of Geneva, and was on the faculty of Penn State University before joining the faculty at University of Arizona. His research group explores the biogeochemistry of soil, sediment and water using laboratory and field-based experimental approaches probed with state-of-the-art tools in analytical chemistry. Of particular interest is resolving how mineral-organic interactions influence the weathering of soils, the stabilization of organic carbon, and the speciation, mobility and bioaccessibility of pollutants. He directs a core analytical chemistry facility, the Arizona Laboratory for Emerging Contaminants (http://www.alec.arizona.edu/), and serves as PI of the UA-led, NSF-funded Santa Catalina Mountains – Jemez River Basin Critical Zone Observatory (http://criticalzone.org/catalina-jemez/).
Pulsed water and organic matter inputs to soils and the deeper subsurface critical zone (CZ) affect not only short-term biogeochemical dynamics and fluxes, but also subsurface structure evolution over the longer time scales of pedogenesis and landscape evolution. Plants and microbes colonizing the CZ surface exert modulating control through carbon (e.g., CO2 exchange) and water (e.g., transpiration) partitioning, and mediation of redox reactions. In water-limited systems such as those our team studies in the semi-arid southwestern US, precipitation in excess of evapotranspiration promotes mineral weathering, whereas organic carbon inputs deliver reducing equivalents, protons, and complexing ligands that affect the rates and trajectories of mineral, metal and organic matter transformation. Evolved CZ structures affected by input dynamics of water and reduced carbon include the bonding environment of toxic metal(loid)s, the molecular-to-grain scale composition of mineral-organic complexes, the pore size distributions and preferential flow paths of aggregated porous media, the pedon to catchment-scale depletion and enrichment of lithogenic elements, and the ecosystem-scale pattern of carbon stabilization. Unraveling the coupled processes that influence CZ change over short and long time scales requires close collaboration on measurements and modeling among ecologists, hydrologists, soil scientists, geochemists and geomorphologists.