The developed diffusion scrubber method is an efficient technique that collects and removes gases making use of the difference in the diffusion coefficients between the gases and air particles. By passing air through a porous Teflon tube, the gases diffuse and permeate the pores on the interior wall of the Teflon tube. The diffused gases can be collected by placing an absorbing solution, such as water, on the exterior wall of the Teflon tube. Particles with a smaller diffusion coefficient pass through the Teflon tube with the air flow. Using pure water as the absorbing solution, various water-soluble gases (HCI, HNO₃, SO₂, NH₃, HCHO etc.) can be collected. The diffusion scrubber is not only a gas collection device but an excellent interface easily connected to analytical instruments. Therefore, by connection to the analytical instrument, such as an IC, HPLC, etc., one is able to perform automated and continuous measurements of trace gases in the air at sub ppbv levels. The diffusion scrubber method can be used not only as an environmental measurement technology, but also as a technology for as air cleaning systems that remove hazardous gases. The air cleaning equipment developed using the diffusion scrubber method having excellent features is expected to be widely utilized as a technology to remove hazardous gases in various industrial and living environments.

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Mercury is easy to spread worldwide via atmospheric long-range transport. In general, mercury is emitted from several sources into the atmosphere as a gaseous elemental mercury (GEM: 95% in atmosphere) and spread worldwide. The other 5% in the atmosphere exists as a form of gaseous oxidized mercury (GOM, Hg(II)) or/and particulate mercury (p-Hg) in the atmosphere. They are removed from the atmosphere as a dry/wet deposition. In order to clarify the fluctuation of the mercury concentration in rain water, we collected rain water in northern Shiga prefecture. We collected it using an automatic rain sampler developed by Nagafuchi and Tanabe which can separate every 5 mm of precipitation during single rain events. We analyzed both the total mercury (T-Hg) and dissolved (D-Hg) concentration level in the rain water. The majority of the mercury in the rain water was Hg(II). The average concentration of Hg(II) was 4.34±1.63 ng/L. The Hg(II) concentration only slightly fluctuated. The fluctuations of the mercury concentration in every 5 mm of precipitation were totally different in each run. In addition, in even single rain events, the mercury concentration showed various trends.

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We have developed a method for the direct estimation of the O₃ induced HOx (OH, HO₂) production rate within the atmosphere. HOx radicals produced from the reactions of O₃ and ambient air constituents within a reaction tube were detected using a PERCA/LIF (PEroxy Radical Chemical Amplification/Laser Induced Fluorescence) method to measure the ROx (OH, HO₂, RO₂) concentration. The measured ROx concentration was found to vary as a function of the added O₃ concentration. We have defined the HOx production rate as the unit concentration of O₃ and unit of time (PHOx) as the slope of the measured ROx concentration at close to 0 ppbv O₃ divided by the reaction time. To assess the ROx loss in our system, we performed a series of fundamental experiments based on the isoprene and ozone reaction. We compared the measured ROx concentration and the ROx concentration calculated using the MCM model (ver. 3.2) to derive the instrument function, K=0.42×[O₃]^0.048. The measured PHOx values are corrected according to K. To avoid variations in the PERCA signal due to natural fluctuations in the NO₂ and O₃ concentrations, a batch sampling method using a Tedlar bag was employed for the ambient PHOx measurements This instrument was successfully applied to measure the ambient PHOx and the ROx concentration within the Kyoto University campus for several days during July 2013. These observations demonstrated that PHOx and the ROx concentration were generally high during the daytime and low at night.

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Fresh leaf/needle, litter, surface soil, and stream bottom sand were monthly collected from Japanese cedar and deciduous broadleaf forests in the so-called “Satoyama” of Namie town in Fukushima Prefecture for one year from June 2012 to July 2013. The concentration of radioactive cesium (¹³⁴Cs and ¹³⁷Cs) was measured by a commercially available NaI(Tl) scintillation detector. The order of the concentration of the radioactive cesium was litter>surface soil>fresh leaf/needle>bottom sand, indicating that radioactive cesium had accumulated in the litter. Snow covering in the winter and snow melt in the spring did not affect the concentration of radioactive cesium in the litter both in the Japanese cedar and deciduous broadleaf forests. There was a high positive correlation between the concentration of radioactive cesium in the bottom sand at the upstream and the following month's concentration of radioactive cesium in bottom sand at the downstream, indicating that radioactive cesium was transported through the suspended sand at approximately 500 m per month in the studied small forest.

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Inhaled submicron aerosols deeply reach into the human respiratory tract. The regional deposition in the bronchi and alveolar widely ranges from 70% for diameters of approximately 10 nm, 10–20% for 100 nm–1 μm, and almost 0% for larger than 10 μm (adult, male, nasal inhalation, and light exercising case). It also varies depending on the hygroscopicity because the respiratory tract below the larynx (bronchi and alveolar) is saturated with water vapor. Combustion-generated soot is generally hydrophobic when emitted (fresh soot), but condensation of the hygroscopic components on soot during long-range transport makes the soot larger and more hygroscopic (aged soot), and thus the regional deposition becomes smaller. Given the typical size and hygroscopicity for fresh soot and aged soot, the regional deposition of fresh soot is approximately twice that of aged soot. The regional deposition ranges for approximately ten-fold from 4.00 to 42.0% for the number equivalent geometric mean dry diameters of 40–280 nm, standard deviations of 1.3–2.0, and hygroscopicity κ of 0–0.7. Accurate assessment of the exposure to hazardous aerosol components requires identification of the host aerosol particles, which carry the hazardous components, and understanding of the host aerosols' size distribution and hygroscopicity, in addition to the bulk mass concentration of the aerosols and the hazardous components.

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To examine the effects of continuous UV-B irradiation on cucumber (Cucumis sativus L.) cotyledons, sections of cucumber cotyledons were observed and the Cs1-MMP expression was analyzed. Cs1-MMP encodes a putative MMP that is expressed during the transition from senescence to PCD in cucumber cotyledons. The observation of sections revealed that the alignment of chloroplasts in palisade cells became irregular by treatment with UV-B for 8 d. The adaxial surface of the cotyledons became smooth due to flattening out of the epidermal cells by treatment with UV-B for 12 d. The longitudinal length of the palisade layers was reduced after 8−16 d of exposure to UV-B. The thickness of the cell walls of the upper palisade cells was reduced after treatment for 16 d. The Cs1-MMP expression was induced by 8−16 d of UV-B exposure. Thus, there is strong temporal correlation between induction of the Cs1-MMP expression and disruption of the epidermal and upper palisade cells in UV-B-irradiated cucumber cotyledons. These results suggest that Cs1-MMP may be responsible for the UV-B-induced disintegration of the cell walls, leading to PCD in the cucumber cotyledons.

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In order to update EAGrid2000-Japan, the grid database of the emission inventory of multiple species in Japan, we newly estimated these emissions for FY2005 and FY2010 with emphasis on the sources with a significant change in the actual emission conditions. The air pollutants we estimated are CO, CO₂, NMVOC, NH₃, NO_x, PM₁₀, PM_2.5 and SO₂. As a fundamental plan, we estimated the total annual emissions by activities for every emission category (for example, the categories of vehicle type, fuel, etc., in road vehicles), and we adopted the method of emission distributions assuming that these relative geographical distributions and seasonal variations are the same as for FY2000. As a result of this estimation, both in FY2005 and FY2010, the sources with the highest contribution of emissions by pollutant type are road vehicles (NO_x, CO, PM₁₀, PM_2.5), large combustion sources mainly in industrial sectors except for power plants and waste incinerators (CO₂, SO₂), stationary evaporative sources (NMVOC) and agriculture (NH₃). The anthropogenic emissions of all species except for CO₂ decreased from FY2000 to FY2005, and future decreased in FY2010 including CO₂. NO_x, CO, PM₁₀ and PM_2.5 have the greatest contribution to decreasing the emissions from road vehicles and NMVOC in road vehicles and stationary evaporative sources, which reflected the effect of emission controls. On the other hand, NH₃ has the greatest contribution to decreasing emissions in agriculture and pit latrines, which reflected a reduction in activities, such as the number of livestocks and the population not connected to sewage lines.

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