Related Experiment Video
Updated: Feb 25, 2026

Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Published on: July 24, 2016
Iron Redox Transformations in the Presence of Natural Organic Matter: Effect of Calcium
Chao Jiang1, Shikha Garg1, T David Waite1
1School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia.
Abstract:
The effects of calcium on iron redox transformations in acidic nonirradiated and irradiated Suwannee River Fulvic Acid (SRFA) solutions are investigated in this study. Our results reveal that, even though calcium is redox-inert, it affects the redox transformations of iron with increased Fe(III) reduction rates under irradiated conditions and decreased Fe(II) oxidation rates in the dark in the presence compared to the absence of calcium. While the exact mechanism via which the Fe(III) reduction rate under irradiated conditions is impacted by calcium addition is not clear, the formation of more photolabile weakly complexed Fe(III)SRFA is most consistent with our experimental results. An observed decline in the Fe(II) oxidation rate in nonirradiated and previously irradiated SRFA solutions with the addition of calcium can be rationalized by formation of more weakly bound Fe(II) and Fe(III). The higher Fe(III) reduction rates and lower Fe(II) oxidation rates in the presence compared to the absence of calcium will help to maintain higher concentrations of Fe(II) thereby increasing the bioavailability of iron in calcium-containing waters. On the basis of our experimental results, we have developed a mathematical model that well describes the iron redox transformations mediated by SRFA in calcium-containing waters under irradiated and nonirradiated conditions.
More Related Videos
Related Concept Videos
Redox Reactions
Redox Reactions
Oxidation Numbers
Oxidation and Reduction of Organic Molecules
The removal of an electron from a molecule, results in a...
Redox Equilibria: Overview
Redox Titration: Other Oxidizing and Reducing Agents

