As part of research on the method of collecting soil samples for mutagenicity measurement, a map of the former Sagamihara City was divided into a square mesh by drawing lines along every latitudinal minute and longitudinal minute. 40 surface soil samples were collected at the intersection points on the map, and the mutagenicity of the samples was examined by the Ames preincubation method using Salmonella typhimurium TA98 and TA100 strains. It was found that the average mutagenicity was 47 rev/g of soil when TA98 was used without S9mix, 87 rev/g of soil when TA98 was used with S9mix, 11 rev/g of soil when TA100 was used without S9mix, and 152 rev/g of soil when TA100 was used with S9mix, all of which were lower than the values reported in past documents, and were approximately the same as values obtained in the countryside. To provide an overview, the geographical distribution of specific mutagenic activity was examined. As a result, mutagenic substances easily detectable with TA98 strain (inducing frame shift type mutations) were found mostly in the center of the former Sagamihara City, whereas mutagenic substances easily detectable with TA100 strain (inducing base pair substitution type mutations) were found to have spread over the whole of Sagamihara City. In order to look for hot spots, and in order to understand the distribution of mutagenicity, a sampling plan using non-arbitrary selection of sites as in the present study was effective.

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We measured the concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in sediments of the Furuayase River, located in the southeast part of Saitama Prefecture, Japan. Surface and core sediment samples were collected at 27 sites at 50 m intervals upstream and downstream of the Matsueshinbashi Bridge. Dioxin concentrations in toxic equivalents (TEQ) in surface sediment at 9 sites located within the area 300 m upstream and 200 m downstream of the bridge exceeded the Japanese environmental standard for sediment. Dioxin concentrations in sliced core samples collected from lower sediment layers were generally higher than concentrations in samples collected from upper layers. The homologue profiles in the samples collected at upstream sites differed from those in the samples collected at downstream sites, suggesting that the bridge piers at the saddle of the riverbed affected the flow and diffusion of surface sediment in the river. Extremely high concentrations of 1,3,7,8-/1,3,7,9-TeCDF were detected in some samples, mainly those collected upstream of the bridge. These congeners were found in the lower layers of sediment, and the contamination in the lower layers sediment may have resulted from the long-term influence of drainage from upstream drainage ditches.

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Dioxin concentrations in water sampled from a drainage ditch flowing into the Furuayase River (southeast Saitama Prefecture, Japan) were monitored during a 3-h rainfall event. The dioxin concentrations in toxic equivalent (TEQ) ranged between 3.5 and 17 pg-TEQ/L. The concentrations in all 12 samples exceeded the Japanese environmental standard (ES) for water (1 pg-TEQ/L), and the concentrations in 5 samples exceeded even the Japanese wastewater standard (10 pg- TEQ/L). Excellent correlation between TEQ and SS in the water samples was observed. The amount of precipitation during the observation period was 8.7 mm. Discharges of suspended solids (SS) and dioxins from the ditch to the river during the event were estimated at 570 kg and 68 μg-TEQ, respectively. The average concentration of dioxins in SS was 120 pg-TEQ/g, which is lower than the Japanese ES for sediment. Because the dioxin concentrations and SS in the ditch water varied with rainfall conditions, it was difficult to determine whether the presence of dioxins in the SS was the sole reason that dioxin concentrations of the riverbed exceeded the ES for sediment. The ratio of 1,3,7,8-/1,3,7,9-TeCDF to TeCDFs in the ditch water was extremely high. This typical pattern in the ratio was similar to the reported value of sediment in the Furuayase River, indicating that the discharge from the ditch into the river still continued.

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Highly adsorptive clay mineral-TiO₂ composites were prepared by a simple sol-gel method in order to remove trichloroethylene and the intermediate products of its degradation by photocatalytic degradation and adsorption. The composite powder was obtained by the following procedure: particles of the natural clay mineral, allophone or kaolinite, were dispersed into a titanium alkoxide sol, separated from the sol after the sol-gel reaction proceeded to some extent, and then heated. Trichloroethylene was transformed into the intermediate product, phosgene, on the TiO₂ during the UV irradiation. Using the composites, emission of phosgene was significantly inhibited although the degradation rate of trichloroethylene was slower than that using TiO₂. The composites supported on porous filters enabled the removal of trichloroethylene in a relatively short time due to a better contact between the composites and reactants.

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Triclosan, triclocarban, and other antimicrobial and antifungal agents have recently become a significant concern for public due to their potentially high ecological risk for aquatic organisms. In the present study, laboratory riverwater biodegradation, sunlight photodegradation and sorption experiments using river sediments were conducted for four selected antimicrobials and antifungal agents of concern, triclosan, triclocarban, and their alternatives, phenoxyethanol, and 4-isopropyl-3-methylphenol, to estimate their fate and transport in the aquatic environment. As results, we found relatively fast removal of triclosan by sunlight while the other three compounds were found to be recalcitrant against sunlight emission. As for the degradation in the river water, relatively fast degradation of phenoxyethanol and moderate degradation of triclocarban was observed while triclosan and 4-isopropyl-3-methylphenol are somewhat resistant against microbes. The sorption coefficients of triclosan and triclocarban were relatively high and comparable to a four-ring polycyclic hydrocarbon, pyrene, and they are possible to accumulate in the sediment while phenoxyethanol and 4-isopropyl-3-methylphenol remain in the aqueous phase. These results overall suggests the relatively high accumulation of triclosan and triclocarban in the sediment due to their high hydrophobicity and their effects on benthic organisms could be the significant concern as well as those on aquatic organisms. In contrast, phenoxyethanol and 4-isopropyl-3-methylphenol tend to remain in the aqueous phase, which agrees to the relatively high detected concentrations of these compounds in the urban streams with unsewered watershed area.

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As one of the offensive odorous compounds in drinking water, there is trichloramine except musty and earthy odor. The N-chloroaldimines which are chlorination byproducts of amino acids are offensive odorous compounds, too. It was found that the contributions of trichloramine and N-chloroaldimines in chlorinated raw water samples were approximately 20 % and 10-20 % of odor intensity (TON), respectively.

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