More than half of the environmental contamination of soils and groundwater reported by the environmental control authorities both in Japan and U.S.A. are caused by halogenated volatile organic compounds. Remediation of these sites contaminated by halogenated organic volatiles is an urgent task in Japan.
Remedial works which include remediation of the sites and the development of applicable technologies have been carried out under the lead of government authorities from the latter half of the 1980's in U.S.A. and from the beginning of the 1990's in Japan.
In situsoil vapour extraction (SVE) in combination with air stripping tower (for desorption of the contaminated groundwater) and carbon adsorption (for the emitted gas) has been selected as a potentially applicable technology for this type of contaminated ground in Japan. Field remediation by this technology has been carried out in commercial scale at many sites.
Thermal desorption and in situ bioremediation are considered to be applicable and demonstrative field studies are being undertaken.
Catalytic dechlorination and photolytic oxidation are also considered to be potentially applicable technologies for the final stage of a treatment process to achieve remediation goals at sites in which no hazardous material can be passed to the surrounding environment. Demonstrative tests in sites and bench scale tests are underway by several developers applying precious metal catalyst or ultra violet radiation.
This paper reports field experiences on the application of SVE at several sites in Japan. The effective range around a single SVE borehole and the time required to clean up sites, both of which vary with site specific factors, are discussed and brief comments for more effective field works are presented.
This paper also reports present states of the demonstrating technologies on the catalytic dechlorination of halogenated volatile organic compounds and introduces an outline of the catalytic oxidation system of which the authors have participated in R&D works.

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Statistical analysis was carried out on the atmospheric monitoring data and the analytical data of filter paper used in automatic SPM monitor to estimate factors causing high concentration of SPM. Samples were extracted with water from the filter paper, and seven ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^-, NO^-₃and SO^2-₄) were analyzed by ion chromatography.
The weight of NO^-₃occupied 6.1 % of the SPM weight. The components which correlated significantly with the SPM concentration were NO^-₃, NO, NO₂and SO₂. Also, SPM and NO^-₃were selected in the 2nd factor as a result of the principal component analysis. This indicated that the contributions of nitrogen oxide and NO^-₃are great with respect to the fluctuation of SPM concentrations. Through an analysis of variance, fluctuations of SPM concentration can be explained definitely by the NO^-₃, K⁺and NO₂concentration and the effects of the monitoring season. These results may indicate that the nitrogen oxide emitted from motor vehicles contribute mainly to high concentration appearances of SPM in Sendai City.

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A large-volume sample injection to capillary column by multi-dimensional column system has been developed for analysis of a low concentration of airborne pesticides.
Air was pumped through a cartridge column (SEP-PAK PS-2) for several hours at a flow rate of 1.0L/min. The trapped organics were eluted with 5mL of acetone and the eluate was concentrated to 0.5mL. A 112.51μL of sample injection by autosampler to capillary column could be done.
Distortion of peak profiles generated in the precolumn was eliminated by cryo-focussing, and the samples were then successfully introduced to the main-column. As a result, sufficient chromatographic seperation and sensitivity and good linearity between injection volume and MS response of 23 golf course pesticides were obtained with an injection volume of 1 to 100μL.

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Biodegradation of 1, 1, 1-trichloroethane (TCA) which is a common contaminant found in groundwater was investigated in soils to predict the behavior and fate of TCA in the environment. TCA was biotransformed in the soil to dichloroethane (DCA) and chloroethane (CA) . The Biodegradation rate of TCA was related to the organic carbon content in soils. About 16-91% of the initial TCA was transformed to DCA and CA during the experimental period. The measured biodegradation rate constants of TCA were in the range of 0.04d^-1to 0.099d^-1.

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A new gas exposure system that measures the mutagenicity of volatile nitrosamines was evaluated. The examinations used to determine the test conditions in this system, using N-nitrosodiethylamine (NDEA) under S9mix conditions, showed the greatest mutagenicity in theE. coliWP2uvrA/pKM101 strain, next in theS. typhimuriumTA100 strain, and no mutagenicity in theS. typhimuriumTA98 strain. The variation coefficients obtained from this system were shown to be comparatively small (3.9-10.8%) .
The mutagenic activity of the four nitroso compounds were compared in three assays using the WP2uvrA/pKM101 strain with the S9mix. The order of mutagenic activity obtained was as follows: N-nitrosodi-n-butylamine>N-nitrosodi-n-propylamine > N-nitrosodiethylamine>N-nitrosodimethylamine. The mutagenic detectability with increasing molecular weight of the nitrosamines was as follows: gas exposure system>preincubation assay>plate incorporation assay.

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Gas Chromatograph/mass spectrometric survey analyses were performed on the air, seawater, sea sediment and seaweed samples from several urban areas of Japan. More than 400 compounds, including 49 halogenated compounds, were identified. In addition to common contaminants (n-alkane, polycyclic aromatic hydrocarbons, chlordanes, chlorobenzenes, triclosan, trichloroethylene, etc.), some novel contaminants, such as bromodichloroanilines and chlorodibromoanilines, were found in sediment and seaweed samples. The compositions of aromatic hydrocarbons in sediments showed marked regional difference. Alkylbenzenes (C₉-C₁₄) were found in Tokyo Bay, owing to domestic waste water contamination, while no alkylbenzenes but a large number of polycyclic aromatic hydrocarbons found in Dokai Bay. Thus, the composition of aromatic hydrocarbons in sediment may represent the regional characteristics on pollution.

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Chlorine is widely used as a disinfectant in water treatment and in the food industry. Five organophosphorus pesticides (EPN, diazinon, fenitrothion, malathion and parathion) were, therefore, subjected to aqueous chlorination with hypochlorite to evaluate inhibitory effect on cholinesterase (ChE) activity and mutagenic effect of these reaction products. Treatment with hypochlorite of thiophosphorus (P=S) pesticide solutions was shown to produce compounds with a great inhibiting effect on ChE activity, but, further reactions resulted in decrease in the ChE inhibiting activity. Aqueous chlorination with hypochlorite of these P=S compound solutions was also shown to produce compounds with mutagencity onS. typhimuriumTA98 without S9 mix. The production of mutagens is dependent on the parent pesticides, the solution pH values, and the reaction time.

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A new injection and extraction method using membrane chromatographic system for determination of volatile organic compounds in air and aqueous samples was developed. The system was evaluated with volatile chlorinated hydrocarbons, aromatic, sulfur, nitrogen compounds in air and water samples by using hollow fiber silicone rubber membranes of 40-100 μm thickness.
It became possible to inject aqueous sample of 1 to 100μl in flow injection and 0.1 to 5ml in the stopped-flow system with capillary gas chromatography. This method can be applied to determine volatile organic compounds in water samples containing sodium chloride and stearate.
This method has a characteristic, that is, it is possible for GC, GC/MS or HPLC analyses to extract and concentrate organic compounds in environmental samples without using organic solvents.

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A fully-automated HPLC system for simultaneous determination of three pesticides, simazine, thiram and thiobencarb, in tap water was developed.
A test tap water was made up in a solution of 2mM sodium ascorbate and 1mM EDTA in order to prevent the decomposition of thiram and thiobencarb from residual chroline and metal ions. Three ml of the tap water injected by the auto sampler was passed through an enrichment column, where the pesticides were trapped quantitatively. The pesticides were then flushed from the column onto an analytic column, where the separation was achieved, and they were measured by the UV detector. The recoveries of simazine (0.3μg/l), thiram (0.6μg/l) and thiobencarb (1.0μg/l) spiked to 7 tap water samples were 93-100%, 92-98% and 81-88%, respectively. It may be possible that many samples are continuously analyzed within a running time of 30minutes by the proposed system. Therefore, it is suggested that the analytical system is effective for daily assay of simazine, thiram and thiobencarb in tap water as a screening method.

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Acid-neutralizing capacity was measured by the batch technique on fifteen kinds of soil type collected in Sendai City in order to investigate the damage against plants by acid rain. Measurement items are pH, EC and acid-neutralizing capacity of the soils. The acid-neutralizing capacity is defined as H⁺volume being consumed by 100g of soil until pH of soil pore water decreases as low as 4.7. Also the composition of water soluble cations of soil was compared each other by“similarity (of patterns) ”.
The pH (H₂O) of 15 soil types ranged from 4.5 to 7.5. The similarity of cation was close for lower layer of all soil types except for one soil type (article soil) . The ANC of each soil ranged from 0.1 to 33.9 (meq/100g), and the average was 13.2 (meq/100g) . Also, the range of upper layers' ANC was 1.2 to 29.5 (meq/100g) with an average 14.3 (meq/100g) . Soil type that showed the lowest ANC was sand hill immature soil collected at‘Fukanuma (sand beach) ’, and the highest ANC soil type was the ash yellow soil collected at‘Imozawa Kita’.

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Residues of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls have been identified in all parts of the global ecosystem. The environmental persistence, bioaccumulation, and toxic properties of these chemicals has given rise to much concern over the last few decades, and they were the subject of the three hundred and thirty five oral and poster presentations given to“Dioxin '94 The 14th International Symposium on Chlorinated Dioxins, PCBs and Related Compounds”held in Kyoto, Japan November 21-25, 1994. The lectures and posters presented at the National Overviews, Analytical Methods, Environmental Levels and the Polar Environment sections of the Symposium are reviewed. A full list of presentations to all twelve sections is given.

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