Ethyl t-butyl ether (ETBE) is a widely used gasoline additive known to be a persistent chemical substance. In this research, the mechanism of the degradation of ETBE by sodium persulfate was investigated. The sodium persulfate treatment of ETBE revealed that 100% ETBE in aqueous phase was degraded within 79 h. The degradation of ETBE followed a pseudo-first-order reaction and its degradation rate constant was 0.054 h^-1. The identification of byproducts in both aqueous and gas phases by GC-FID and GC-TCD revealed that acetaldehyde, ethanol, acetone, t-butyl alcohol (TBA), acetic acid, t-butyl acetate, CO₂ and CH₄ were generated during the reaction. 95% of the carbon in the degraded ETBE was recovered in the form of these byproducts. The degradation of each byproduct was carried out to determine the degradation pathways of ETBE by sodium persulfate. Consequently, the degradation pathways are proposed as follows: the main pathway in the initial stage is (i) ETBE → TBA + ethanol, and the subpathway is (ii) ETBE → t-butyl acetate. Further degradation pathways are proposed as follows: ethanol → acetaldehyde → acetic acid, TBA → acetone → acetic acid, t-butyl acetate → TBA + acetic acid and acetic acid → CO₂.

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To find a means of restoring the population of the clam Meretrix lusoria, we caged M. lusoria and three other clam species at two stations on the Oi tidal flat in Tokyo Bay, where hypoxic water often intrudes. Nine caging experiments, each of which lasted for 1.5 to 5 months, were conducted from July 2006 to October 2007. The survival and growth of the clams in relation to environmental conditions were assessed. M. lusoria showed high mortalities (survival ≈ 40%) at the muddier station in the late summer of 2007, when hypoxic water was consistently present in the shallow subtidal zone. However, its survival rates exceeded 90% in all other cases, and were higher than or comparable to those of the other species throughout the study period. The growth rates of M. lusoria in warm seasons were higher than or comparable to those of the other species, and were less affected by sediment quality than those of Mercenaria mercenaria, the predominant species on the flat. Thus, M. lusoria had a high survival ability, and other factors such as overfishing and life-cycle-related events should be considered for restoration.

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As a ligand exchange kinetic model of an Fe(III)-fulvic acid complex and a siderophore, desferrioxamine B (DFOB) was developed. The model includes two pathways of Fe(III)-DFOB formation, (1) a disjunctive pathway where DFOB binds to unchelated Fe(III) following the dissociation of Fe(III) from Fe(III)-fulvic acid and (2) an adjunctive pathway where Fe(III)-DFOB is formed via the direct association of DFOB with an Fe(III)-fulvic acid complex. Iron binding sites in fulvic acid were classified into two ligand classes on the basis of binding strength. Fitting the kinetic model to experimental observation with a spectrophotometer, the rate constant of ligand exchange for a strong binding site [k₁ (M^-1 · s^-1)] was determined to be k₁ = 4.7 × 10³ / [FA]_T + 5.5 × 10², where [FA]_T (mg · l^-1) denotes the total fulvic acid concentration. The rate constant for a weak binding site [k₂ (M^-1 · s^-1)] was estimated to be greater than 1 × 10⁵. The model calculation provided profiles of ligand exchange rate and the amount of Fe(III) bound to each ligand class (relative ratio to total Fe), which are functions of fulvic acid concentration and both of fulvic acid and iron concentrations, respectively.

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