The role of Fe(oxyhydr)oxides in regulating the biogeochemical cycling of the essential micronutrients zinc and copper
EMSL Project ID
51934
Abstract
Elements essential for plant growth and nutritious crops (e.g., Fe, Cu, and Zn) are often strongly associated with Fe (oxyhydr)oxides, particularly in more weathered terrains. For example, Zn deficiency is one of the most widespread micronutrient deficiencies in agricultural lands around the world, causing yield decreases and diminishing the nutritional quality of agricultural plants. Calcareous and laterite soils exhibit particular low Zn bioavailability due to occurrence of iron-coated carbonates and incorporation of Zn in refractory Fe (oxyhydr)oxides. The aim of this proposal is to better understand the role played by Fe(III) (oxyhydr)oxides in regulating the biogeochemical cycling of Zn and Cu, key micronutrients and cofactors in enzymes that catalyze a range of reactions in both flora and fauna including biomineralization processes. We propose to leverage fundamental knowledge on the detailed coordination environment of Zn and Cu in Fe oxides gained from our prior EMSL supported work to focus on the role that Fe vacancies play in the bioavailability of both micronutrients. Further, we plan on exploring how different incorporation pathways might alter the defect/micronutrient relationship and consequently the release of Cu and Zn from nominally stable Fe (oxyhydr)oxides back to solution. In order to reach these objectives we propose a comprehensive approach to unravel key processes in the incorporation and release of Zn and Cu in or from FeHyOx; one that integrates the computational and instrumental capabilities in EMSL with experiments, and strongly constrains spectroscopic interpretation with theory. In particular, the following EMSL resources are requested to track reaction progress via both aqueous solution compositions as well as solid state behavior: Solids (nano-particulate Fe oxides) will be analyzed with 1.) XPS to quantify compositions and chemical states of the near surface, 2.) STEM/EDX/EELS and SEM/EDX to quantify elemental distributions at the atomic to nanoscale and particle-particle growth (DLS for the latter), 3.) powder XRD to determine potential phase evolution, 4.) Raman spectroscopy to characterize the protonation state of the solid. Aqueous solutions will be analyzed with ICP-MS to quantify the extent of Zn, Cu, and Fe release/incorporation. The team will perform all sample preparations and are experts in analyzing XPS, Raman, STEM, SEM/EDX, and ICP data. AIMD simulations will use NWChem (SNK is an expert user) to elucidate details about local coordination environments of Zn and Cu in tandem with EXAFS/PDF measurements at other DOE user facilities, including SSRL.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2021-10-01
End Date
2023-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members