title: Effect of dissolved organic matter on Fe(II) oxidation in natural and engineered waters.
abstract: Fe(II) oxidation was investigated in samples from the Sagami River basin (Japan) with particular emphasis on the effect of dissolved organic matter (DOM) in an urban river system. Collected samples consisted of main stream and tributary waters impacted to a moderate and minor extent by anthropogenic activities, respectively, and treated effluents from adjacent municipal wastewater treatment plants (MWWTPs: as representative anthropogenic point source). Nanomolar Fe(II) oxidation was measured in air-saturated waters using luminol chemiluminescence in the dark at 25 °C. Second-order rate constant for Fe(II) oxidation (with respect to Fe(II) and O2 concentrations) showed spatial and temporal variation. Annual average of the rate constant was highest for MWWTP effluents, followed by reservoir and river waters, with tributary waters showing the lowest oxidation rate. Manipulation experiments indicated that, in addition to pH (7.8-8.4), DOM characteristics are important explanatory variable for the Fe(II) oxidation. For example, the addition of MWWTP-derived humic-type DOM to anthropogenically less-influenced tributary water resulted in substantial increase in the oxidation rate. Significant negative correlation observed between the specific UV absorbance (SUVA254) and Fe(II) oxidation rate constant (pH 8.0) suggests a potential effect of humic-type DOM with low SUVA254 (high aliphatic content) on Fe(II) oxidation in natural and engineered waters.
authors.affiliation: Department of Civil Engineering, Tokyo Institute of Technology, 2-12-1-M1-4 Ookayama, Tokyo 152-8552, Japan.
authors.forename: Ying Ping
authors.initials: YP
authors.lastname: Lee
authors.affiliation: Department of Civil Engineering, Tokyo Institute of Technology, 2-12-1-M1-4 Ookayama, Tokyo 152-8552, Japan. Electronic address: fujii.m.ah@m.titech.ac.jp.
authors.forename: Manabu
authors.initials: M
authors.lastname: Fujii
authors.affiliation: Department of Civil Engineering, Tokyo Institute of Technology, 2-12-1-M1-4 Ookayama, Tokyo 152-8552, Japan.
authors.forename: Koumei
authors.initials: K
authors.lastname: Terao
authors.affiliation: Department of Civil Engineering, Tokyo Institute of Technology, 2-12-1-M1-4 Ookayama, Tokyo 152-8552, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Kikuchi
authors.affiliation: Department of Civil Engineering, Tokyo Institute of Technology, 2-12-1-M1-4 Ookayama, Tokyo 152-8552, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Yoshimura
mesh_terms: D005296:Ferrous Compounds; D005618:Fresh Water / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D045483:Rivers / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D005296:Ferrous Compounds; D009930:Organic Chemicals; D014867:Water
keywords: Dissolved organic matter; Fe(II) oxidation; Municipal wastewater treatment plant; Specific UV absorbance (SUVA(254)); Urban river