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RISS 인기검색어
- 검색키워드
- 저자 : Masahiro Yamaguchi (검색결과 41 건)
- 무료
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Optical Method for Measuring Deposition Amount of Black Carbon Particles on Foliar Surface
Masahiro Yamaguchi,Kenta Takeda,Yoko Otani,Naoto Murao,Hiroyuki Sase,I. Wuled Lenggoro,Kenichi Yazaki,Kyotaro Noguchi,Atsushi Ishida,Takeshi Izuta 한국대기환경학회 2012 Asian Journal of Atmospheric Environment (AJAE) Vol.6 No.4
To perform quick measurements of black carbon (BC)particles deposited on foliar surfaces of forest tree species, we investigated an optical method for measuring the amount of BC extracted from foliar surfaces and collected on quartz fiber filters. The seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to submicron BC particles for one growing season (1June to 7 December 2009). At the end of the growing season, the leaves or needles of the seedlings were harvested and washed with deionized water followed by washing with chloroform to extract the BC particles deposited on the foliar surfaces. The extracted BC particles were collected on a quartz fiber filter. The absorption spectrum of the filters was measured by spectrophotometer with an integrating sphere. To obtain the relationship between the absorbance of the filter and the amount of BC particles on the filter,the amount of BC particles on the filter was determined as that of elemental carbon (EC) measured by a thermal optical method. At wavelengths below 450nm, the absorption spectrum of the filter showed absorption by biological substances, such as epicuticular wax, resulting in the low coefficient of determination (R2) in the relationship between the amount of EC on the filter (MEC, μg C cm-2 filter area) and the absorbance of the filter. The intercept of the regression line between MEC and the absorbance of the filter at 580 nm (A580) was closest to 0. There was a significant linear relationship between the A580 and MEC (R2=0.917, p⁄0.001), suggesting that the amount of BC particles collected on the filter can be predicted from the absorbance. This optical method might serve as a simple, fast and cost-effective technique for measuring the amount of BC on foliar surfaces. To perform quick measurements of black carbon (BC)particles deposited on foliar surfaces of forest tree species, we investigated an optical method for measuring the amount of BC extracted from foliar surfaces and collected on quartz fiber filters. The seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to submicron BC particles for one growing season (1June to 7 December 2009). At the end of the growing season, the leaves or needles of the seedlings were harvested and washed with deionized water followed by washing with chloroform to extract the BC particles deposited on the foliar surfaces. The extracted BC particles were collected on a quartz fiber filter. The absorption spectrum of the filters was measured by spectrophotometer with an integrating sphere. To obtain the relationship between the absorbance of the filter and the amount of BC particles on the filter,the amount of BC particles on the filter was determined as that of elemental carbon (EC) measured by a thermal optical method. At wavelengths below 450nm, the absorption spectrum of the filter showed absorption by biological substances, such as epicuticular wax, resulting in the low coefficient of determination (R2) in the relationship between the amount of EC on the filter (MEC, μg C cm-2 filter area) and the absorbance of the filter. The intercept of the regression line between MEC and the absorbance of the filter at 580 nm (A580) was closest to 0. There was a significant linear relationship between the A580 and MEC (R2=0.917, p⁄0.001), suggesting that the amount of BC particles collected on the filter can be predicted from the absorbance. This optical method might serve as a simple, fast and cost-effective technique for measuring the amount of BC on foliar surfaces.
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Masahiro Yamaguchi,Makoto Watanabe,Hideyuki Matsumura,Yoshihisa Kohno,Takeshi Izuta 한국대기환경학회 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.2
Ozone (O_3) is a main component of photochemical oxidants, and a phytotoxic anthropogenic air pollutant. In North America and Europe, the current concentration of O_3 has been shown to have significant adverse effects on vegetation. In this review, we summarize the experimental studies on the effects of O-3 on the growth and photosynthetic activity of Japanese forest tree species to understand the present knowledge and provide sound basis for future research toward the assessment of O_3 impacts on Japanese forest ecosystem. Since the 1990s, several Japanese researchers have conducted the experimental studies on the effects of ambient levels of O_3on growth and physiological functions such as net photosynthesis of Japanese forest tree species. Although the sensitivity to O_3 of whole-plant growth is quite different among the species, it was suggested that the current ambient levels of O_3 in Japan are high enough to adversely affect growth and photosynthetic activity of Japanese forest tree species classified into high O_3 sensitivity group such as Japanese beech. The N load to soil has been shown to reduce the sensitivity to O_3 of Japanese larch and increase that of Japanese beech. To establish the critical level of O_3 for protecting Japanese forest tree species, therefore, it is necessary to take into account the N deposition from the atmosphere. There is little information on the combined effects of O_3 and other environmental factors such as elevated CO_2and drought on growth and physiological functions of Japanese forest tree species. Therefore, it is necessary to promote the experimental study and accumulate the information on the combined effects of O_3and any other abiotic environmental factors on Japanese forest tree species.
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Masahiro Yamaguchi,Shoma Kamiya,Dai Kokubun,Tomoki Nakayama,Tetsushi Yonekura,Yoshihisa Kohno KOSAE·JSAE·CSES-CSAE 2022 Asian Journal of Atmospheric Environment (AJAE) Vol.16 No.3
Two Japanese rice cultivars with different heat-tolerance, Hinohikari (sensitive) and Nikomaru (tolerant), were grown in pots inside open-top chambers and exposed to ambient CO₂ (400 μmol mol<SUP>-1</SUP>) or elevated CO₂ (550 μmol mol<SUP>-1</SUP>) from the beginning of the tillering stage to maturity. The study was conducted in Nagasaki, in the Kyushu region of Japan, where heat stress on rice has become increasingly evident. Although elevated CO₂ significantly improved the net photosynthesis and whole-plant growth of the cultivars, there were no significant effects on grain yield, which in turn reduced harvest index. In both cultivars, adverse effects occurred with elevated CO₂, such as reductions in spikelet fertility and grain appearance quality, which are typical manifestations of heat stress in rice. During the flowering period, the air temperature was high that spikelet fertility was reduced even under ambient CO₂ conditions for both cultivars. These results suggest that, under high-temperature conditions, elevated CO₂ could induce or exacerbate the manifestations of heat stress in rice. Because transpiration rate in the flag leaf was significantly reduced by the exposure to elevated CO₂, it is possible that elevated CO₂ increased plant temperature via a reduction in transpiration during flowering period, although we did not detect significance of the increase in leaf and panicle temperature. To ensure a more confident conclusion, further studies focusing on the effects of elevated CO₂ on the determinants of spikelet fertility and grain appearance quality with other cultivars in different year are required.
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Optical Method for Measuring Deposition Amount of Black Carbon Particles on Foliar Surface
Yamaguchi, Masahiro,Takeda, Kenta,Otani, Yoko,Murao, Naoto,Sase, Hiroyuki,Lenggoro, I. Wuled,Yazaki, Kenichi,Noguchi, Kyotaro,Ishida, Atsushi,Izuta, Takeshi Korean Society for Atmospheric Environment 2012 Asian Journal of Atmospheric Environment (AJAE) Vol.6 No.4
To perform quick measurements of black carbon (BC) particles deposited on foliar surfaces of forest tree species, we investigated an optical method for measuring the amount of BC extracted from foliar surfaces and collected on quartz fiber filters. The seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to submicron BC particles for one growing season (1 June to 7 December 2009). At the end of the growing season, the leaves or needles of the seedlings were harvested and washed with deionized water followed by washing with chloroform to extract the BC particles deposited on the foliar surfaces. The extracted BC particles were collected on a quartz fiber filter. The absorption spectrum of the filters was measured by spectrophotometer with an integrating sphere. To obtain the relationship between the absorbance of the filter and the amount of BC particles on the filter, the amount of BC particles on the filter was determined as that of elemental carbon (EC) measured by a thermal optical method. At wavelengths below 450 nm, the absorption spectrum of the filter showed absorption by biological substances, such as epicuticular wax, resulting in the low coefficient of determination ($R^2$) in the relationship between the amount of EC on the filter ($M_{EC}$, ${\mu}g\;C\;cm^{-2}$ filter area) and the absorbance of the filter. The intercept of the regression line between $M_{EC}$ and the absorbance of the filter at 580 nm ($A_{580}$) was closest to 0. There was a significant linear relationship between the $A_{580}$ and $M_{EC}$ ($R^2$=0.917, p<0.001), suggesting that the amount of BC particles collected on the filter can be predicted from the absorbance. This optical method might serve as a simple, fast and cost-effective technique for measuring the amount of BC on foliar surfaces.
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Masahiro Yamaguchi,Yoko Otani,Kenta Takeda,I. Wuled Lenggoro,Atsushi Ishida,Kenichi Yazaki,Kyotaro Noguchi,Hiroyuki Sase,Naoto Murao,Satoshi Nakaba,Kenichi Yamane,Katsushi Kuroda,Yuzou Sano,Ryo Funada 한국대기환경학회 2012 Asian Journal of Atmospheric Environment (AJAE) Vol.6 No.4
To clarify the effects of black carbon (BC) particles on growth and gas exchange rates of Asian forest tree species, the seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to BC particles with sub-micron size for two growing seasons from 1 June 2009 to 11 November 2010. The BC particles deposited after the exposure to BC were observed on the foliar surface of the 4 tree species. At the end of the experiment, the amount of BC accumulated on the foliar surface after the exposure to BC aerosols were 0.13, 0.69, 0.32and 0.58 mg C m-2 total leaf area in F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings, respectively. In August 2010, the exposure to BC particles did not significantly affect net photosynthetic rate under any light intensity, stomatal diffusive conductance to water vapour (gs), stomatal limitation of photosynthesis,response of gs to increase in vapour pressure deficit and leaf temperature under light saturated condition in the leaves or needles of the seedlings. These results suggest that the BC particles deposited on the foliar surface did not reduce net photosynthesis by shading, did not increase leaf temperature by absorption of irradiation light, and did not induce plugging of stomata in the leaves or needles of the seedlings. There were no significant effects of BC particles on the increments of plant height and stem base diameter during the experimental period and the whole-plant dry mass at the end of the experiment. These results indicate that the exposure to BC particles with sub-micron size for two growing seasons did not significantly affect the growth and leaf or needle gas exchange rates of F. crenata, C. sieboldii,L. kaempferi and C. japonica seedlings. To clarify the effects of black carbon (BC) particles on growth and gas exchange rates of Asian forest tree species, the seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to BC particles with sub-micron size for two growing seasons from 1 June 2009 to 11 November 2010. The BC particles deposited after the exposure to BC were observed on the foliar surface of the 4 tree species. At the end of the experiment, the amount of BC accumulated on the foliar surface after the exposure to BC aerosols were 0.13, 0.69, 0.32and 0.58 mg C m-2 total leaf area in F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings, respectively. In August 2010, the exposure to BC particles did not significantly affect net photosynthetic rate under any light intensity, stomatal diffusive conductance to water vapour (gs), stomatal limitation of photosynthesis,response of gs to increase in vapour pressure deficit and leaf temperature under light saturated condition in the leaves or needles of the seedlings. These results suggest that the BC particles deposited on the foliar surface did not reduce net photosynthesis by shading, did not increase leaf temperature by absorption of irradiation light, and did not induce plugging of stomata in the leaves or needles of the seedlings. There were no significant effects of BC particles on the increments of plant height and stem base diameter during the experimental period and the whole-plant dry mass at the end of the experiment. These results indicate that the exposure to BC particles with sub-micron size for two growing seasons did not significantly affect the growth and leaf or needle gas exchange rates of F. crenata, C. sieboldii,L. kaempferi and C. japonica seedlings.
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Masahiro Yamaguchi,Nobuyuki Tazoe,Tomoki Nakayama,Tetsushi Yonekura,Takeshi Izuta,Yoshihisa Kohno 한국대기환경학회 2023 Asian Journal of Atmospheric Environment (AJAE) Vol.17 No.1
In the region where heat stress has become evident, the elevation of air temperature could reduce yield of heat stress-susceptible crops, such as rice (Oryza sativa L.), which is a major food staple in Asia. In addition to air temperature, atmospheric CO2 is projected to be elevated in the future. To project rice yield in the future, it is necessary to clarify the responses of rice to concurrent elevations of air temperature and atmospheric CO2. In the present study, two japonica rice cultivars with different heat tolerance, Hinohikari (sensitive) and Nikomaru (tolerant), were grown in pots inside open-top chambers and exposed to elevated air temperature and/or CO2. The degrees of increase in the air temperature and CO2 concentration by the treatments were approximately 1 °C and 120 μmol mol− 1 (ppm). The study was conducted in Nagasaki, Japan, where heat stress on rice has become evident. Elevated air temperature significantly decreased both whole-plant growth and grain yield. Elevated CO2 significantly increased the growth but significantly decreased the yield. The effects of elevated air temperature and elevated CO2 on growth and yield did not significantly differ between two cultivars. In both cultivars, the main cause of yield reduction by both treatments was reduction in spikelet fertility, which is typical heat stress on rice. The elevated CO2- induced reduction in spikelet fertility could be explained partially by high-temperature regime during flowering due to acceleration of heading and by increase in canopy temperature via stomatal closure in flag leaves. Because elevated air temperature and elevated CO2 treatments additively reduced spikelet fertility in both cultivars, concurrent elevations of air temperature and CO2 caused considerable reduction in grain yield.
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Yamaguchi, Masahiro,Otani, Yoko,Takeda, Kenta,Lenggoro, I. Wuled,Ishida, Atsushi,Yazaki, Kenichi,Noguchi, Kyotaro,Sase, Hiroyuki,Murao, Naoto,Nakaba, Satoshi,Yamane, Kenichi,Kuroda, Katsushi,Sano, Yuz Korean Society for Atmospheric Environment 2012 Asian Journal of Atmospheric Environment (AJAE) Vol.6 No.4
To clarify the effects of black carbon (BC) particles on growth and gas exchange rates of Asian forest tree species, the seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to BC particles with sub-micron size for two growing seasons from 1 June 2009 to 11 November 2010. The BC particles deposited after the exposure to BC were observed on the foliar surface of the 4 tree species. At the end of the experiment, the amount of BC accumulated on the foliar surface after the exposure to BC aerosols were 0.13, 0.69, 0.32 and 0.58 mg C $m^{-2}$ total leaf area in F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings, respectively. In August 2010, the exposure to BC particles did not significantly affect net photosynthetic rate under any light intensity, stomatal diffusive conductance to water vapour ($g_s$), stomatal limitation of photosynthesis, response of $g_s$ to increase in vapour pressure deficit and leaf temperature under light saturated condition in the leaves or needles of the seedlings. These results suggest that the BC particles deposited on the foliar surface did not reduce net photosynthesis by shading, did not increase leaf temperature by absorption of irradiation light, and did not induce plugging of stomata in the leaves or needles of the seedlings. There were no significant effects of BC particles on the increments of plant height and stem base diameter during the experimental period and the whole-plant dry mass at the end of the experiment. These results indicate that the exposure to BC particles with sub-micron size for two growing seasons did not significantly affect the growth and leaf or needle gas exchange rates of F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings.
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