Both soil and underground water of the southwestern Bangladesh has already been threatened with arsenic contamination affecting health of millions of people. An estimated 44% of total area of Bangladesh (34 districts) and 53 million rural people are at risk of arsenic poisoning. In the southwestern and some parts of eastern Bangladesh, arsenic content in soil and underground water has identified higher contamination. The experts at Bangladesh Council for Scientific and Industrial Research (BCSIR) found the highest contamination, 14mg/l of shallow tube well water in Pabna, a northern district and 220mg/kg of soil in Sylhet area of Bangladesh. The World Health Organization (WHO) standard for arsenic in drinking water is 0.01mg/l . However, the maximum permissible limit of arsenic in drinking water of Bangladesh is 0.05mg/l. Worsening contamination of groundwater aquifer and sufferings of the millions of people demand extensive research in this field.
This study is a preliminary evaluation of our ongoing research on current state of the subsurface contamination of arsenic in Bangladesh. Last decade water resources management has been analyzed to cope with the problem in the source level. Possible geo-hydrological and geo-chemical occurrences of arsenic in subsurface are discussed. The concentration of arsenic and the stratigraphic occurrence are presented. It is observed that arsenic concentration in tubewell water of 31 districts of Bangladesh contain above the maximum permissible limit. And the concentration of arsenic in tubewell water decreases with the depth of subsurface.

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Decalin solution containing 1000ppm PCBs was treated with the sodium dispersion (SD) process under conditions at less than 100°C. PCBs in the reaction mixtures were not detected (below 20ppb) by GC analysis.
The SD process gave rate of 100% dechlorination. The decomposition products identified by GC-MS were biphenyl, phenylcyclohexadiene, and phenylcyclohexene. The latter two would be the reduction products of biphenyl formed as a result of hydrogen abstraction of decalin by biphenyl sodium which were formed during the reaction of PCBs with sodium. GPC analysis showed that oligomers of biphenyl generated in the SD process were negligibly small. About 100% of PCBs decomposed by the SD process were recovered as biphenyl, phenylcyclohexadiene, and phenylcyclohexene.

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Analytical methods for haloacetonitriles and chloral hydrate in tap water by extraction and detection by GC-ECD, GC/MS and GC-NPD methods were studied.
Good results were obtained by using GC/NPD method for the analysis of haloacetonitriles and by using GC/MS method for the analysis of chloral hydrate.
The result indicated that dichloroacetonitrile and chloral hydrate were volatilized like trihalomethane by heating.

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Fifteen kinds of volatile organic compounds (VOCs) in the air were measured at five houses in Kitakyushu City in summer (June-August) 1996 and in winter (January-February) 1997. Samples for VOCs were collected hourly by using two automatic sequential tube samplers, each of which equipped with 24 sample tubes packed with Carbopack B and Carbosieve S II, at outdoor and indoor in in-dividual houses. Air was sucked through each tube by a pump at a flow-rate of 100 ml min^-1 for an hour. Then, the tubes were capped with Swagelock compression fittings. The VOCs were analyzed by the system composed of automated thermal desorption device, and a gas chromatograph/mass selective detector. Most of the VOCs in indoor air showed higher concentration than those in outdoor air. Among the VOCs measured, the hourly change of chloroform and 1, 1, 1-trichloroethane concentration in indoor air was relatively large. On the other hand, the hourly change of p-dichlorobenzene and α-pinene concentrations in indoor air were very small. The results suggested that major emission sources of chloroform and 1, 1, 1-trichloroethane were outside of the houses. However, major emission sources of p-dichlorobenzene and α-pinene were inside of the houses. The concentrations of bromoform, 1, 2-dichloroethane and 1, 2-di-chloroethane were relatively low compared with other VOCs. The highest carcinogenic risk estimated in indoor air was 1.7 × 10^-5 for p-dichlorobenzene, and that in outdoor air was 4.9 × 10^-6 for benzene. Loss of life expectancy estimated with the 10 VOCs carcinogenic risk was 170 minutes for indoor air, 70 minutes for outdoor air.

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A highly sensitive and automatic analytical method for polycyclic aromatic hydrocarbons (PAHs) in indoor airborne Particulates was developed and applied to a preliminary survey of indoor PAH pollution. The PAH analysis consists of ultrasonic extraction of PAH from airborne particulates with dichloromethane, evaporation of the solvent and dissolution of the residue in acetonitrile, and separation analysis by a newly developed high performance liquid chromatographic (HPLC) method. The HPLC system consists of pre-column, main column, 2 spectrofluorometers, data processor and system controller. Twenty PAHs had been analyzed reliably by the present method. Recovery of PAHs from airborne particulates ranged from 91.4±1.7% (dibenzo [a, h] pyrene) to 106±2.4% (pyrene) . Quantification limit ranged from 2.4 (chrysene, dibenz [a, h] anthracene) to 89 (dibenzo [a, i] pyrene) pg. The method was applied to a preliminary indoor survey for one week in the late summer season at 6 homes in Shizuoka. Seventeen PAHs were found in airborne particulate samples which were collected by a mini-pump system at a flow rate of 1.0 l/min for 24 hours. Indoor PAH levels varied largely according to the life style, living conditions, and sampling date.

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Thirty-one n-alkanes (C₁₀-C₄₀), two branched alkanes (pristane and phytane), eight alkyl dibenzothiophenes and 22 polycyclic aromatic hydrocarbons (PAHs) were identified from nine oil samples collected from the coasts of the Niigata Prefecture during May to August 1997. Compositions and relative ratios of these compounds to C₃₀ in the oil samples were compared with those in the heavy oil (N-1) from a Russian-registered tanker, Nakhodka which has broken and sunk on January 2, 1997, in the Sea of Japan.
Low molecular weight compounds, such as n-alkanes with C₁₀-C₂₂, alkyl dibenzothiophenes and PAHs decreased by weathering in the environment. Volatilization rather than elution and/or bio-degradation seems to be a major factor for the disappearance of the compounds. Six among nine oil samples from the coasts did not seem to be originated from Nakhodka based on the comparison of the compositions and the relative ratios of the target compounds in the oil samples with those of the oil from the tanker.

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An ultrasonic extraction was developed for gas chromatography-mass spectrometric (GC/MS) determination of polycyclic aromatic hydrocarbones (PAHs) and n-alkanes in airborne particulates. PAHs and n-alkanes investigated were benz [a] anthracene, benzo [b] fluoranthene, benzo [k] fluoranthene, benzo [e] pyrene, benzo [a] pyrene, indino [1, 2, 3-cd] pyrene, dibenz [a, h] anthracene, benzo [ghi] perylene and n-alkanes with carbon numbers 23 to 32. The target compounds collected on a quartz-fiber filter were extracted ultrasonically and the extract was reduced to a small volume and added with hexane for GC/MS. Twelve different solvents were evaluated for the ultrasonic extraction; ethanol-cyclohexane (1: 3) was chosen as the best solvent.
This method was applied to determining the target compounds except for benz [a] anthracene at four sites in Niigata Prefecture. Their concentrations at an urban site were higher than those at two suburban sites and an industrial site. While compositions of the PAHs showed no statistically significant difference in the four sites, the composition of hexacosane at the urban site was higher than those at the other sites.

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Twenty seven volatile organic compounds in indoor air in a newly constructed residential multi-family building before occupied were measured by Air Toxics sorbent tubes - thermal desorption - GC/MS system. All the volatile organic compounds were detected except for chloroform.
Detection limit of chloroform was 0.3μg/m³. Concentration of volatile organic compounds ranged from 1.2μg/m³ for 1, 1, 1-trichloroethane to 1200μg/m³ for toluene.
We also investigated the usefulness of diffusive sampling tube packed with Carbopack B for the determination of volatile organic compounds in indoor air.
Diffusive uptake rates were calculated to be 0.36±0.06ml/min for hexane, 0.267±0.04ml/min for ethylbenzene, 0.177±0.03ml/min for nonane, 0.137±0.02ml/min for dichloromethane and 0.24±0.05ml /min for methyl iso-butyl ketone. Relative standard deviations of diffusive uptake rates for heptane, benzene and trichloroethylene were under 24%.
These results suggested that Carbopack B diffusive sampler was useful for the determination of volatile organic compounds in indoor air samples.

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