The kinetics of the oxidation of ferrous iron in synthetic and natural waters

Iron colloids reduce the bioavailability of phosphorus to the green alga Raphidocelis subcapitata

“…The near absence of truly 236 dissolved Fe(II), i.e. Fe(II) in the < 10 kDa fraction, indicates that the oxidation process was 237 completed after 24 hours as expected from earlier studies (Davison and Seed, 1983). 83-87% ferrihydrite, 7-9% lepidocrocite, 2-8% Fe-SRNOM complex, and < 3% of 253 goethite and Fe-oxalate complex.…”

Potential for Microscale Bacterial Fe Redox Cycling at the Aerobic-Anaerobic Interface

“…The dominant role of microbial catalysis in Fe(II) oxidation in acidic environments (e.g., acid mine drainage and acid hot springs) is well-established (Brock and Gustafson 1972;Singer and Stumm 1972;Johnson et al 1993). In contrast, Fe(II) is subject to rapid chemical oxidation by dissolved O 2 at circumneutral pH (Davison and Seed 1983;Millero, Sotolongo, and Izaguirre 1987), and the Fe(III) produced eventually hydrolyzes and precipitates through overall reactions such as [2]…”

“…In view of the speed of this spontaneous abiotic reaction (the half-life of dissolved Fe 2+ in air-saturated water is on the order of a few minutes), bacterial Fe(II) oxidation with O 2 as an electron acceptor at circumneutral pH, though energetically more favorable than Fe(II) oxidation at low pH, has been considered doubtful from a geochemical perspective (e.g., Davison and Seed 1983). Nevertheless, bacteria have been associated with circumneutral Fe(II) oxidation and Fe(III) oxyhydroxide deposition for a over a century (Ghiorse 1984;Ehrlich 1995).…”

Flow and nutrient dynamics in a subterranean estuary (Waquoit Bay, MA, USA): Field data and reactive transport modeling

“…The formation of iron oxide at the freshwater-seawater interface is driven by the oxidation of Fe 2+ as it is transported through oxic surface beach sediments . Other studies (Davison and Seed, 1983;Spiteri et al, 2006) suggest that the pH increase from freshwater to seawater can also play an important role in the precipitation of iron oxides in coastal sediments.…”