In order to prevent water pollution of rivers in general, it is important to control water quality and pollutant loads of small and medium rivers, including tributaries, which contribute essential portion of pollutant loads. For this purpose, runoff characteristics of pollutants from small and medium rivers were studied, and runoff and decay coefficients of pollutants were examined in relation to transport, sedimentation and scouring of pollutants.
In the first half of the paper, the major contoling factors of the runoff coefficient and their constituent elements were discussed, and the methods to describe the relationship between pollutant loads and quality of receiving water were presented putting particular emphasis on non-point sources of pollutants.
In the latter half, the results of case study with several small and medium rivers were shown to analyze the mass balances of pollutants and the relationship between pollutant runoff characteristics and time-varying properties of rivers such as flow, water quality and the amounts of pollutant load. In addition, the variation of runoff and decay coefficients with flow distance were also analyzed.

View full abstract

In the season of blooming, dissolved phosphorus and some environmental factors were measured for seawater in Hiroshima Bay at about one-week interval. The concentrations of dissolved phosphorus with some chemical forms were determined by a combination of photo-oxidation, wet-oxidation and acid-hydrolysis. Their concentrations were discussed in connection with AOU (apparent oxygen utilization). From these analyses, it was demonstrated that OMP (organic monophosphate) was excreted from living phytoplankton. It was also found that concentrations of CF (condensed phosphate) plus OPP (organic polyphosphate) were much lower than those of OP (orthophosphate) and OMP. CP plus OPP may be stable residue of DOP or may be present in bacterial cells.

View full abstract

Chloroform and an unknown substance was produced by the reaction of sodium hypochlorite with humic acid, one of the color ingredients in natural water. It was resulted in the increase of these substances either by the increase of humic acid and sodium hypochlorite concentration or by the elongation of reaction time.
By the application of GC-MS, the unknown substance was identified as chloropicrin.
Chloroform was formed most easily at pH 10, while chloropicrin was formed in the wide range of pH (pH 19). These products were readily volatized or decomposed.
Chloropicrin was presumably formed by oxidation of amino group in humic acid and by addition of chlorine.

View full abstract

The adsorption of phosphate by river sediments taken from a small suburban river was investigated. The experimental results indicated that the phosphate adsorption capacity of sediments significantly correlates with the amounts of contained organic substances and is highly controlled by contained Fe and Al. The phosphate adsorption behavior fits Freundlich equation and the Freundlich constant is almost the same for every sediment samples.

View full abstract

Distribution and behavior of carbohydrate in particulate matter were studied at polluted river water. Particulate matters were collected from June to December, 1979, at Minami-Asakawa River and it's draining sewages.
Particulate carbohydrate carbon (PCC) and water-extractable carbohydrate carbon (PWCC) were determined by anthrone method, and the gas chromatographic technique was applied for analysis of monosaccharide composition.
Concentrations of PCC ranged from 0.053 to 0.10 mgC/l at MA-3 and from 0.14 to 0.24 mgC/l at MA-5 during one day (July 26-27, 1979). From budgets of PCC and PWCC between MA-3 and MA-5, about 70% of them was estimated to be removed by sedimentation and decomposition from river water during going down.
Rhamnose, fucose, arabinose, ribose, xylose, mannose, galactose, and glucose were identified in particulate matter. Glucose was the most abundant monosaccharide and amounted to about 60% of the total particulate carbohydrate. Notable changes in monosaccharide composition, especially decrease in glucose, were observed after aerobic incubation of particulate matter in river water.

View full abstract

The ultraviolet absorption spectra of aqueous solutions of 86 organic compounds were measured, and the relationships among the absorbances at the peak wave length, 220 nm, 254 nm and 275 nm and the concentrations of TOC, TOD and COD_Mn are discussed for characterization of organic pollutants in water.
Several organic compounds did not show any absorbances, and the aliphatic compounds showed less sensitivities than the aromatic compounds. All the compounds used could be classed in the seven groups by the characteristics of the absorbances at 220 nm (A₂₂₀) and at 275 nm (A₂₇₅) near which various organic compounds showed maximum absorbances. The ratios of A₂₇₅/A₂₂₀, A₂₂₀/TOC and A₂₇₅/TOC seemed to be very useful for characterizations and identifications of organic pollutants in water, though the affections of several inorganic ions such as carbonate, nitrite and nitrate need to take notice. However, the absorbances could not be generally used for evaluation of the values of COD_Mn.

View full abstract