Concentrations of 4 insecticides in water and fish from rivers and lakes were reviewed and the bioconcentration potential of the insecticides and their contamination in the field fish were evaluated. For the water survey data in Japan and foreign countries, diazinon and malathion were detected at about the same concentration levels, but fenitrothion and fenthion could not be adequately compared because of few reports in foreign countries. For the fish survey data, the 3 insecticides except malathion were detected in fish from rivers and lakes in Japan and the concentrations of 3 insecticides in fish had a tendency to increase and decrease nearly according to those in water, while malathion was detected in fish from a few lakes in Egypt and India because of its high level contamination in these lakes. The concentrations of 4 insecticides in fish from rivers and lakes were approximately estimated by the laboratory bioconcentration factors of these insecticides in fish.

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The concentrations of heavy metals (V, Mn, Co, Cu, Zn, Cd, Ba, in addition to Pb which was reported elsewhere) in surface soil samples collected from 31 public playgrounds in a ward in Tokyo were determined by ICP mass spectrometry after HNO₃/HF/HClO₄ digestion. Mean concentrations of all metals but Ba exceeded the levels of uncontaminated soils in Japan reported in the previous literature indicating the presence of soil pollution. The exposure to V via direct soil ingestion was estimated to contribute more than that via dietary intake; however, it was not serious enough to warrant immediate attention. For other metals, dietary exposure accounted much more than soil ingestion. There were strong positive correlations between metal concentrations in the soil samples, particularly between V and Mn (r=0.97), V and Co (r=0.95), Pb and Cu (r=0.75), or Pb and Zn (r=0.84). These correlations suggested that the metals, to a certain extent, shared common pollution source.

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The adsorptions of cadmium ions from aqueous solutions on the two kinds of coal based activated carbons (AC's) oxidized (incorporating acidic functional groups by nitric acid treatment) and out-gassed (removing acidic functional groups by heating in reduction condition) were examined. Cadmium adsorption affinity onto the oxidized AC is larger than that to the out-gassed AC, and the equivalent amount of proton for cadmium adsorption was released from oxidized AC. The adsorption kinetic of cadmium onto out-gassed AC could be predicted by Langmuir type kinetic equation, but it was slower than the predicted value in approaching the equilibrium state for the oxidized AC. Based on adsorption kinetics for oxidized AC in acidic solution, the slower kinetics were supposed to be influenced by proton released with adsorption. Since Langmuir type kinetic equation is assumed the collision to the adsorption site, the adsorption process is predominated by collision to the adsorption site in both of the activated carbons.

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In this study, we determined the concentrations of 9 kinds of haloacetic acids and 3 kinds of halosuccinic acids in raw water and drinking water by capillary column GC/MS. Chlorosuccinic acid, bromosuccinic acid and 9 kinds of haloacetic acids were detected at higher concentrations and greater frequencies in drinking water than in raw water. In Tokyo metropolitan area, the concentrations of chlorosuccinic acid and bromosuccinic acid in drinking water were below the limit of determination to 0.60 μg/l in district A; those concentrations were below the limit of determination to 0.45 μg/l and the limit of determination in districts B and C, respectively. The concentration ratios of total halosuccinic acids to the total haloacetic acids were about 5 % in many cases. When the drinking water was boiled for 5 minutes using a kettle, the concentration of chlorosuccinic acid was decreased.

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In the present study, we estimated inflow and effluent load of Polycyclic Aromatic Hydrocarbons (PAHs) in Lake Suwa, Japan. Estimation of PAHs inflow and effluent load were performed by measuring changes in stream flow and concentration of suspended solids (SS) in the lake and river water. Results showed that the concentration of SS increased with stream flow. Annual (March 2004 to February 2005) inflow and effluent load of SS at the lake were calculated as 8.9×10⁶ kg and 7.6×10⁶ kg, respectively. The mass balance between inflow and effluent load indicated that 1.3×10⁶ kg of SS were sedimentated to the lake. The total amount of Σ₉PAHs (Phenanthrene, Pyrene, Chrysene, Benzo[e]pyrene, Benzo[b]fluoranthene, Benzo[k]fluoranthene, Benzo[a]pyrene, Dibenz[a,h]anthracene, Benzo[ghi]perylene) in lake SS varied by 230±120 g/lake (average±SD); the maximum amount exceeded 500 g/lake, which was observed in May and October 2004. Specifically, for Benzo[a]pyrene the total amount in lake SS was 14±7 g/lake. Estimation of total Σ₉PAHs flowing into Lake Suwa and out through Kamaguchi Gate indicated Σ₉PAHs values of 8.6 and 3.5 kg/yr, respectively. The mass balance between Σ₉PAHs inflow and outflow indicated that approximately 5.1 kg/yr of Σ₉PAHs were sedimentated with SS to the lake. The annual flux of PAHs in Lake Suwa calculated in the present study agreed with the deposition flux of PAHs in a previous study estimated from sediment cores (4 kg/yr) (Ikenaka et al.: Environ. Pollut., 138, 530-538 (2005)). Inflow loads of PAHs markedly increased in May 21, October 9, and October 21 when heavy rains occurred, occupying approximately 27 % of the annual inflow. These results indicated that large quantities of PAHs flowed into the lake when river flow increased by heavy rain.

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Photolysis of [¹⁴C]bisphenol A (BPA) was studied in the Japanese environmental water under simulated solar irradiation. Calculated half-lives of BPA under the natural sunlight were approximately 10.8 days in water from the Ushiku Marsh and 12.7 days in water from the Kokai River. Photodegradation rates of BPA in the environmental water were about 5∼6 times faster than that in the pure water. It was assumed that BPA in the environmental water was degraded mostly by indirect photolysis. Major degradation products included 2-(4-hydroxyphenyl)-2-propanol and carbon dioxide. Mineralization of BPA by photolysis in the environmental water was observed. It was considered that dissolved organic matter and nitrate ion had photosensitizing effects for BPA.

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