Promotion of Microbial Oxidation of Structural Fe(II) in Nontronite by Oxalate and NTA.
Environ Sci Technol
; 54(20): 13026-13035, 2020 10 20.
Article
em En
| MEDLINE
| ID: mdl-32845130
ABSTRACT
Iron redox cycling occurs extensively in soils and sediments. Previous research has focused on microbially mediated redox cycling of aqueous Fe. At circumneutral pH, most Fe occurs in solid phase, where Fe and organic ligands interact closely. However, the role of organic ligands in microbial oxidation of solid-phase Fe(II) is not well understood. Here, we incubated reduced nontronite NAu-2 (rNAu-2) with an iron-oxidizing bacterium and in the presence of oxalate and nitrilotriacetic acid. These ligands significantly enhanced the rate and extent of microbial oxidation of structural Fe(II) in rNAu-2. Aqueous and solid-phase analyses, coupled with biogeochemical modeling, revealed a pathway for ligand-enhanced bio-oxidation of solid-phase Fe(II) (1) dissolution of rNAu-2 to form aqueous Fe(II)-ligand complex; (2) bio-oxidation to Fe(III)-ligand complex; (3) rapid reduction of Fe(III)-ligand complex to Fe(II)-ligand complex by structural Fe(II) in rNAu-2. In this process, the Fe(II)-ligand and Fe(III)-ligand complexes effectively serve as electron shuttle to expand the bioavailable pool of solid-phase Fe(II). These results have important implications for a better understanding of the bioavailability and reactivity of solid-phase Fe pool in the environment.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Compostos Férricos
/
Ácido Nitrilotriacético
Idioma:
En
Revista:
Environ Sci Technol
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Estados Unidos