Nitrite reduction by biogenic hydroxycarbonate green rusts: evidence for hydroxy-nitrite green rust formation as an intermediate reaction product.
The present study investigates for the first time the reduction of nitrite by biogenic hydroxycarbonate green rusts, bio-GR(CO3), produced from the bioreduction of ferric oxyhydroxycarbonate (Fohc), a poorly crystalline solid phase, and of lepidocrocite, a well-crystallized Fe(III)-oxyhydroxide mineral. Results show a fast Fe(II) production from Fohc, which leads to the precipitation of bio-GR(CO3) particles that were roughly 2-fold smaller (2.3 ± 0.4 μm) than those obtained from the bioreduction of lepidocrocite (5.0 ± 0.4 μm). The study reveals that both bio-GR(CO3) are capable of reducing nitrite ions into gaseous nitrogen species such as NO, N2O, or N2 without ammonium production at neutral initial pH and that nitrite reduction proceeded to a larger extent with smaller particles than with larger ones. On the basis of the identification of intermediates and end-reaction products using X-ray diffraction and X-ray absorption fine structure (XAFS) spectroscopy at the Fe K-edge, our study shows the formation of hydroxy-nitrite green rust, GR(NO2), a new type of green rust 1, and suggests that the reduction of nitrite by biogenic GR(CO3) involves both external and internal reaction sites and that such a mechanism could explain the higher reactivity of green rust with respect to nitrite, compared to other mineral substrates possessing only external reactive sites.
Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Universités-UPMC Univ Paris 06, UMR 7590 CNRS, Muséum National d'Histoire Naturelle, IRD UMR 206 , 4 place Jussieu, F-75005 Paris, France .
Delphine
D
Guerbois
Georges
G
Ona-Nguema
Guillaume
G
Morin
Mustapha
M
Abdelmoula
Anniet M
AM
Laverman
Jean-Marie
JM
Mouchel
Kevin
K
Barthelemy
Fabien
F
Maillot
Jessica
J
Brest
D001673:Biodegradation, Environmental; D002254:Carbonates / Q000378:metabolism*; D005290:Ferric Compounds / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism*; D008903:Minerals / Q000737:chemistry; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D020592:Shewanella / Q000378:metabolism; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
D002254:Carbonates; D005290:Ferric Compounds; D005296:Ferrous Compounds; D008903:Minerals; D009573:Nitrites; C000499:ferric oxide