Based on vertical distribution of the pesticides in a reservoir, a correct monitoring method of pesticide residues originated from paddy field application were investigated in this study. The spatial distribution of pesticides in thermally stratified water clearly shows that concentrations of the pesticide residues were same levels as in the inlet part of the reservoir. Therefore, the dominant residues of pesticides were present in the middle water layer. The results of the study indicate that spatial monitoring as well as periodical moni toring is essential for the accurate evaluation of the pesticide residues in the lake and reservoir water.

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For antimony, which is a highly toxic element and often detected in the environ ment, the valency differential determination as well as the determination of total con centration in living organism samples were performed. About the valency differential determination, the sample solution prepared from antimony trioxide and antimony pentaoxide was measured. As a result, the valency fractional determination was successfully conducted with high recoveries of more than85% and high reproducibilities of less than 10.5 %. In the previous studies, hydrophilic antimony compounds, such as antimony potassium tartarate has been used; those com pounds are easy to analyze, however the industrial production of them is considerably small, so that the amount of those compounds discharged into the environment should be small. Consequently, it was found that the antimony compounds, such as antimony trioxide and antimony pentaoxide, for which the chemical forms are quite common in the production and utilization, could be easily determined. About the determination of total antimony concentration in living organism sam ples, the addition of tartaric acid solution after the acid-digestion process resulted in the favorable determination with high recoveries of more than 96%. By use of this method, the total antimony concentrations in several freshwater organisms in which it was exposed to the antimony, could be measured.

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In the case that some polluted soils including hazardous substances are taken directly, the risk evaluated by content may be overestimated. Therefore, a general idea of bioavailability is necessary. Bioavailability refers to how much hazardous contents are eluted and absorbed when they are exposed to the gastrointestinal tract. The in vitro screening test based on this idea was examined, and heavy metals elution from road sediments in stomach and small intestine were investigated. As a result, the liquid tosolid ratio of 100:1 was selected, pH conditions of stomach and stomach + small in testine solution range of pH 2 .0 and pH 7.0, respectively. Organic acids and enzymes were added to the extraction. These results confirmed that the hazardous heavy metals in road sediments leached in the model stomach solution, but they were decreased in the model stomach + small intestine solution.

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Plastic resin pellets (several mm in diameter and a raw material for the plastic industry) are widely distributed in the ocean. They are ingested by birds and their adverse effects are a concern. Our previous study has revealed polypropylene (PP) pellets are enriched with PCB and DDE through adsorption from ambient seawater and nonylphenol (NP) as additives. In the present study, polyethylene (PE) and PP pellets collected from 18 beaches in Japan and Malaysia were analyzed for PCBs, DDE, polycyclic aromatic hydrocarbons (PAHs), NP and octylphenol (OP). Concentrations of PCBs (1.2-890 ng/g), DDE (0.088-1600 ng/g), PAHs (0.047-8.8 p g/g), NP (0.018-17μg/g), and OP (0-41 ng/g) varied among the sampling sites. PCB, DDE, and PAHs concentrations in pellets were higher in Japanese coasts than in Malaysia. The spatial differences in pollutant concentrations in the pellets were consistent with those observed in biomonitor (i. e. mussels), indicating pollutants concentrations in pellets reflect marine pollution. This suggests potential of the marine plastic resin pellets as monitoring media for marine pollution by organic micropollutants. Field adsorption experiment using virgin pellets showed greater adsorption of PCB, DDE, and PAHs by PE than by PP, being consistent with higher concentrations of the compounds in PE pellets found in the marine environment. The adsorption experiment and the field observations suggest that additive-derived NP and OP mainly contribute to those in the marine plastic pellets, with minor contribution from adsorption.

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Currently, the impact of suspended particulate matter (SPM) on humans has been concerned, but it still has many uncertainties. In vitro cytotoxicity tests using cultured cells have recently been receiving much attention, but there is few research about the evaluation of atmospheric environment. In this article, we investigated the feasibility of a new bioassay using air-liquid interface culture (ALIC) of human alveolar cells, A549, in the toxicity evaluation of SPM. In this bioassay, it was possible to mimic the in vivolike direct exposure of SPM. Carbon absorbing l-nitropyrene (l-NP), involved in the diesel exhaust gases, was loaded directly to the layer of A549 cells in ALIC culture. Dose-response relationships between the loaded amount of carbons or absorbed l-NP and cell survivability were successfully obtained. In addition, net intake in humans was evaluated by the measurement of the leaking kinetics of l-NP into the culture medium in the basolateral side. Although this assay still needs improvement, it is promising as a bioassay suitable for evaluating the toxicity of SPM samples, because not only it exactly mimics the in vivo situation but also it gives basic information about the permeation and intake of chemicals eluted from SPM deposited on the alveolar epithelia.

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Road runoff is an important route of PAHs contamination to the aquatic environment. This study focused on exhausts of diesel and gasoline engine vehicles, tires and road materials as possible sources of PAHs in road dusts. Cluster analysis was applied to characterize 16 USEPA-PAH profile data of the possible source samples, which consisted of 22 data analyzed in this study and 64 data reported in literature. They were categorized into 6 groups (S1-S6). The eight tire samples were categorized into a single group (S1), which did not include any other source samples. The group S1 was characterized by the significantly high percentages of pyrene and benzo (ghi) perylene (43.5% and 18.9%). The road materials samples were categorized into S2 and S3 groups. The average percentage of each PAH component was less than 20% in the S2 group, while the group S3 had high total percentages (more than 75%) of the three dominant components, phenanthrene, pyrene, and fluoranthene. The S2 and S3 groups mostly consisted of road materials and particulate diesel exhausts. The gasoline exhausts and the several diesel exhausts were classified into 3 groups (S4-S6), which were commonly characterized by the high percentage of naphthalene. Multiple regression analysis was performed to estimate the contributions of categorized PAH profiles (S1-S6) in road dust samples at two streets in Tokyo. The contributions of group Sl and group S2 to two road dust samples at Kan-nana Avenue were found to be greater than 50% and 20%, respectively, while that of group S1 to two road dust samples for Sakurada Avenue were more than 75%. Consequently, tires were considered as an important PAHs contributor in the Kan-nana Avenue as well as road material and diesel exhausts. On the other hand, only road material and diesel exhausts were recognized as the major source of PAHs in Sakurada Avenue.

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By the umu-test with genetically engineered bacterium, we can detect genotoxic potential of environmental sample, as an enzymatic activity corresponding to umuC gene induction. Currently, when bacterial assays are applied to environmental samples, mainly because of the their low sensitivities, it is necessary to concentrate the aqueous samples by about thousand times using various solid-phase extractions. In this study, firstly we modified the umu-test method by concentrating the inoculum of the test bacteria to increase its sensitivity. Secondly, for the purpose to avoid the false results affected by formation of precipitation, selectivity or recovery during the extraction, this modified umu-test method followed by simple evaporation under reduced pressure us-ing a rotary evaporator as sample preparation was adapted to environmental samples. Concerning the interference by the formation of turbid materials in the concentrated samples, it was effective to carry out the correction by absorbency. This modified method successfully detected the genotoxocity of various wastewater samples before and after its treatment process. In summery, the umu-test based on the protocol modified in this study is useful in practical management of the toxicity in treatment processes of wastewater from the standpoint of cost, sensitivity, time and simplicity of operation.

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