In the CO₂ reforming reaction using CH₄, carbon precipitation on metal catalysis takes place making the catalysis inactive and useless. In this study, we have suggested two reaction pathways of carbon deposition process on Pd8 (111) cluster in CO₂-CH₄ reforming reaction, which are i.e. Path 1 and Path 2, shown below;
Path 1
       CO+^* → CO-^*
       CO-^*+CO → C-^*+CO₂
Path 2
       CO+^*+^* →  C-^*+O-^*
       O-^*+CO → CO₂+^*
   where ^* is a adsorption site on a catalysis.
The results obtained in the analysis of these two reaction pathways using ab initio molecular orbital method are as follows: (1) energy profile diagrams of those reaction pathways to elucidate the preferred pathway of carbon deposition and (2) electron transfer and population analysis from and to the Pd cluster. Through this analysis, Path 2 appears the preferred reaction path in the present carbon precipitation reaction scheme.

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The environmental impacts of organotin compounds (OTs) and their residues and breakdown products have been of concern since their ecological effects were discovered. Tributyltin (TBT) and triphenyltin (TPT) concentrations in Japanese coastal waters have drastically decreased since 1990, and have remained low in recent years, because domestic use of TBT and TPT has been restricted. OTs, including TBT; TPT; and the breakdown products dibutyltin, monobutyltin; diphenyltin, and monophenyltin, were measured in surface water, bottom water, pore water, and sediments collected from Hiroshima Bay, Japan. TBT concentrations in surface water were lower than those reported in previous Japanese studies. However TBT concentrations in sediments were similar to those reported in previous Japanese studies. This implies that deposited OTs in sediment persist in the environment. OT concentrations in water samples decreased in the order pore water > bottom water > surface water, suggesting secondary contamination caused by OTs in sediments.

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In this study, the levels of Diuron, Irgarol 1051, and the latter's degradation product M1 were investigated in the sediment from Hiroshima Bay. Concentrations of Diuron, Irgarol 1051 and M1 in sediment samples were in the range of ND-73 ng/g, ND-28 ng/g, ND-9 ng/g, respectively.
Over the study period, the detection rate percentage and the average concentration level of Irgarol for each year was 33.3 % and 2.5 ng/g in 2002, 71.4 % and 2.8 ng/g in 2003, 70.0 % and 4.0 ng/g in 2004 and 81.8 % and 6.0 ng/g in 2005.
The figures for M1 were 66.6 % and 3.3 ng/g in 2002, 85.7 % and 3.6 ng/g in 2003, 70.0 % and 2.7 ng/g in 2004 and 100 % and 4.8 ng/g in 2005. Diuron's figures were 83.3 % and 12 ng/g in 2002, 50.0 % and 10.8 ng/g in 2003, 83.3 % and 14.8 ng/g in 2004 and 72.7 % and 19.6 ng/g in 2005.
The detection rates percentages didn't show an upward tendency in any of the investigated materials. But the average concentration levels of the investigated materials did show an upward tendency. Especially, Diuron which had the highest average concentration levels of the three materials. So, it was shown that Diuron's concentration levels in the sediment accumulated significantly over the study period.
The concentration levels were higher at the ports and dock while at the environmental standard points they were lower. It was determined that the sources of the chemicals were the ports and dock.

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Concentrations of particulate polycyclic aromatic hydrocarbons(PAHs) in ambient air were investigated every month during the period Apr. 2004 to Mar. 2006 at two sampling sites in Ehime Prefecture; Site-N in Niihama city industrial area and Site-U in Uwajima city nonindustrial area. The sampling was carried out by high volume air sampler on quarts filters, extracted with dichloromethane and analyzed by HPLC with programmable fluorescence detection. Heavy metals and water soluble ios in particulate samples and benzene in air samples were also analyzed in this study. Annual average of total PAHs concentrations ranged from 4.5 to 4.7 ng/m³ at Site-N, higher than in Site-U (2.0∼3.4 ng/m³). Estimated risks of each PAHs based on unit risk were in the order of 10^-7∼10^-5, but overall risk was higher than objective criteria suggested by Central Environmental Council, Japan. B[a]P contributed above 50 % followed by DB[a,h]A. To have a complete knowledge on PAHs in atmosphere, their levels in the gaseous phase should also be monitored. Major source of PAHs would be vehicles especially diesel cars because of their diagnostic ratios of B[ghi]P/IP, IP/(IP+B[ghi]P) and (B[b]F+B[k]F)/B[ghi]P ranged within values reported for diesel exhausts so far. This view can be substantiated by the observed high correlation of PAHs with benzene and carbon oxide. Indexes of sources were selected by hierarchical cluster analysis on datasets of PAHs, metals and ions at Site-U which has no significant sources from industries. Then temporal variations of them and back trajectories at points in time were analyzed. It appears that high concentrations of anthropogenic metals and NH₄SO₄ are observed when the air mass was originated and passed through low-altitudes on industrial regions of China. Although PAHs showed significant correlation with these metals, they would be increased mainly by the effect of atmospheric stability.

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Dichloromethane, acetone, and methanol solutions containing semivolatile polycyclic aromatic hydrocarbons with 2 to 6 rings were concentrated using rotary and centrifugal evaporators, and spraying nitrogen, and their recovery rates were compared. With concentration using a rotary evaporator, the recovery rate of low-molecular-weight PAHs was found to be low, but by adjusting the pressure in accordance with the volatilization pressure of the solvent, an almost uniform recovery rate was achieved. When a centrifugal evaporator was used, the recovery rate was approximately 60 %. However, since high-molecular-weight PAHs tended to attach to the internal wall of the vessels used, washing was carried out by applying ultrasonic waves, which improved the recovery rate. With concentration based on nitrogen spraying, an almost uniform recovery rate was achieved.

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Exhaust gases from vehicles under the various conditions were sampled, and the timeseries variations in the concentrations of volatile organic compounds (VOCs) in Tedlar bags and canisters were measured during 3 hours. Two gasoline vehicles and one diesel vehicle were tested by using a chassis dynamometer. Concentrations of 1,3-butadiene and styrene, of the eight VOCs that were monitored, often decreased rapidly after sampling. Under the most drastic condition, concentrations of 1,3-butadiene and styrene 3 hours after sampling were <10% of the initial concentrations. A second-order kinetics of 1,3-butadiene with nitrogen dioxide (NO₂) fitted the decay of 1,3-butadiene in the exhaust samples under the various conditions. An adsorption method was evaluated in which samples were directly sampled and concentrated by an adsorption tube and analyzed immediately without using a bag or canister. Emission factors for VOCs other than 1,3-butadiene and styrene obtained by the adsorption method well agreed with the values obtained by using bags where samples were analyzed just after sampling. However, emission factors for 1,3-butadiene and styrene obtained by using bags were often <50 % of those determined by the adsorption method. It is suggested that the adsorption method can eliminate the underestimation of the labile compounds including 1,3-butadiene and styrene. Reported emission factors for labile compounds obtained by using bags or canisters could be underestimated, and care is needed when using such data.

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An analytical system composed of a purge and trap injection system coupled to Hall detector (HECD) specific for analysis of total volatile halogenated hydrocarbons (TVOX) in chlorinated water was optimized. Samples were purged with purified dry air and trapped into the mixture of Tenax GC and Carboxen 1000, and then the TVOX were discharged by heating the trap tube at 250°C into the detector. The detector with nickel catalyst was held at 850°C for catalytic reduction of TVOX with hydrogen gas to form halogen halides. The generated hydrogen halides were quantitatively determined by electrolytic conductivity detector. Purge & trap-HECD conditions were optimized for TVOX analysis, and the limits of detection and quantitative analysis were evaluated. The proposed method allows to analyze water samples whose TVOX concentrations range is from μg/L to mg/L. This method was also applied to the continuous monitoring of TVOX levels in model chlorinated water and drinking water, in order to find out their formation potentials or daily, weekly and seasonal variations.

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A sensitive and selective method was developed for the determination of acrolein in ambient air by using liquid chromatography/tandem-mass spectrometry (LC/MS/MS). Air was sampled by passing through an O-(4-cyano-2-ethoxbenzyl) hydroxylamine (CNET) cartridge for 2∼24 hrs at a constant flow rate (200 mL/min). The acrolein-CNET derivative eluted from the cartridge with acetonitrile was separated by a reversed phase liquid chromatography and determined by LC/MS/MS in turbo spray ionization (ESI) positive mode. The collection efficiency of acrolein on a CNET cartridge was more than 99 %. The method detection limit was 0.4 ng/m³ in case of sampling volume of 0.3 m³ and relative standard deviation of repeated analysis was 5.0 %. Recoveries of acrolein on CNET cartridges under the condition of the relative humidity of 30∼87 % at the temperature of 25∼35 °C were 82∼92 %. In a refrigerator, acrolein-CNET derivative was stable for about 5 days on the cartridge, and that in the solution eluted with acetonitrile was stable for one month.
This method was applied to the determination of ambient acrolein concentration for every 2∼3 hrs during one day. The concentrations of acrolein observed were in the range of 69∼288 ng/m³.

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The concentrations of persistent organic pollutants (POPs) in paddy soil samples collected in 1982 and 1984 (1980s) and in 2000 and 2002 (2000s) from the Yoneshiro River basin, Japan, were measured to elucidate the temporal trend and mass balance of POPs in paddy soils. Aldrin, dieldrin, endrin, chlordanes and heptachlors were rarely detected in almost all the samples collected in the 1980s and 2000s, whereas DDTs, HCHs, HCB and PCBs were detected in relatively many samples. The concentrations of these compounds were lower than the PCDD/DF concentrations reported in our previous study regardless of sampling year. The concentrations of p,p'-DDD, α-HCH, β-HCH,δ-HCH and lower-chlorinated PCBs (M₁CB, D₂CB, T₃CB and T₄CB) decreased significantly (paired t-test, p<0.05) from the 1980s to 2000s, whereas those of the other compounds such as higher-chlorinated PCBs did not decrease. The half-lives of the compounds were calculated as follows: p,p'-DDD, 5.2 years; α-HCH, 5.6 years; β-HCH, 5.0 years; δ-HCH, 4.0 years; M₁CB, 4.5 years; D₂CB, 5.8 years; T₃CB, 5.5 years; and T₄CB, 8.5 years. The half-lives of these compounds correlated with their water solubility. We estimated the total input and remaining amounts of DDTs and HCHs in the paddy fields to determine their long-term fate in the basin within the period of 1962∼2002. Result of the estimation, revealed that approximately 97 % of the DDTs and HCHs applied to the basin were disappeared from the paddy soil by the 1980s.

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