15 research outputs found
Improving the disaster reduction awareness and actions of local residents: From the perspective of experiential learning
Get PDF高知県立大学博士（看護学）令和6年度（2024年度）doctoral thesi
Succession of litter-decomposing microbial organisms in deciduous birch and oak forests, northern Japan
Get PDFBiological litter decomposition and the litter-associated microbial organisms were monitored for three years to characterize litter decomposition in early and late successional stages. Two forests were used for the investigation: pioneer a forest dominated by birch (Betula platyphylla var. japonica) and a climax forest by oak (Quercus mongolica var. grosseserrata) in the cool-temperate region of northern Japan. Three types of litter were used: birch, oak and mixed litter. The litter decomposition was effective during the first year but 50% of the original litter remained even after three years. Carbon-to-nitrogen ratios in the litter decreased largely in the first year and became stable thereafter. The litter decomposition rates were not different among the litter types and between the forests. The temporal changes in phospholipid fatty acids (PLFAs) showed that fungal biomass reached its peak in the first year and the bacterial biomass increased steadily until the end of the experiment. The concentrations of fungal PLFAs in the litter did not differ between the litter types but were lower in the oak forest. The litter decomposition was performed mostly by fungi, in particular in the early stages, while bacterial decomposition depended on the litter types and/or the forest types. Gram-negative bacteria reached their peak of PLFAs in the second year while gram-positive bacteria PLFAs increased gradually during the three years. Therefore, the succession of microorganisms in the litter occurred from fungi to bacteria and from gram-negative bacteria to gram-positive bacteria in the two forests. Unlike in the case of coniferous or monotonic forests, the effects of forests and litter types on litter decomposition for the first year were weak. The forest types on litter decomposition appeared only for the long-term litter decomposition. The successional changes of microorganisms occurred from fungi to bacteria for long-term litter decomposition processes with increasing N concentration in the litter
Changes in Litter Decomposition Across Succession in a Post-mined Peatland, Northern Japan
Get PDFLitter decomposition along successional sere after peat mining was monitored for 3 years on post-mined peatland in Sarobetsu Mire, northern Japan. The litter of two dominant species (Rhynchospora alba and Moliniopsis japonica) was examined in 3 different successional habitats. We used the litterbag method to measure litter decomposition. We also measured changes in litter decomposition properties (carbon, nitrogen, and phospholipid fatty acids) with the environments (solar radiation and peat moisture). Bareground without litter showed the highest fluctuation of solar radiation and temperature, but the litter decomposition was slowest. Therefore, photodegradation and physical abrasion had affected weakly on litter decomposition. The concentrations of carbon, nitrogen, and phosphorus were not different between the two litter species showing that the litter decomposition pathways of these two species were specific in each habitat because of stable isotopes. Phospholipid fatty acids indicated that fungi contributed more to litter decomposition than bacteria in vegetated habitats with time. These results suggested that biodegradation, particularly by fungi, was the determinant in litter decomposition. The fungal activity was determined by vegetation cover suggesting that restoration to the original vegetation was desirable soon after peat mining to return the in-situ litter decomposition
Changes in microbial community composition in the leaf litter of successional communities after volcanic eruptions of Mount Usu, northern Japan
Get PDFChanges in the fungal and bacterial biomass and community structure in litter after the volcanic eruptions of Mount Usu, northern Japan were investigated using a chronosequence approach, which is widely used for analyzing vegetation succession. The vegetation changed from bare ground (10 years after the eruptions) with little plant cover and poor soil to monotonic grassland dominated by Polygonum sachalinense with undeveloped soil (33 years) and then to deciduous broad-leaved forest dominated by Populus maximowiczii with diverse species composition and well-developed soil (100 years). At three chronosequential sites, we evaluated the compositions of phospholipid fatty acids (PLFAs), carbon (C) and nitrogen (N) contents and the isotope ratios of C (delta C-13) and N (delta N-15) in the litter of two dominant species, Polygonum sachalinense and Populus maximowiczii. The C/N ratio, d13C and d15N in the litter of these two species were higher in the forest than that in the bare ground and grassland. The PLFAs gradually increased from the bare ground to the forest, showing that microbial biomass increased with the development of the soil and/or vegetation. The fungi-to-bacteria ratio of PLFA was constant at 5.3 +/- 1.4 in all three sites, suggesting that fungi were predominant. A canonical correspondence analysis suggested that the PLFA composition was related to the successional ages and the developing soil properties (P < 0.05, ANOSIM). The chrono-sequential analysis effectively detected the successional changes in both microbial and plant communities
The involvement of public health nurses improving awareness and behavior of local residents for disaster prevention and mitigation
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Differences in C, N, delta C-13, and delta N-15 among plant functional types after a wildfire in a black spruce forest, interior Alaska
Get PDFWe measured differences in %C, %N, delta(13C,) and delta N-15 of plant functional types (PFTs) between burned and unburned ground surfaces soon after a wildfire on a north-facing slope in interior Alaska. The C and N were measured for 16 species and Sphagnum litter. delta C-13 differed among the PFTs and was low for trees and shrubs, suggesting that woody stems slowed C dynamics or showed low water use efficiency. delta N-15 concentrations suggested that the herbaceous plants depended less on the mycorrhizal associations that became weak on the burned surfaces. The shrub leaves showed the lowest delta N-15 of PFTs and showed higher delta N-15 on the burned surface, showing that N transfer from the soils to the leaves in the shrubs was slowed by the wildfire. Mosses showed the highest C/N ratio. Sphagnum litter decomposed faster on the burned surface, and %N and delta N-15 in the litter increased from the second to third year on both burned and unburned surfaces, while %C changed little. In conclusion, the responses to the wildfire differed among the PFTs as characterized by their C and N dynamics
Oxygen isotope exchange kinetics between CAI melt and carbon monoxide gas : Implication for CAI formation in the earliest Solar System
No full textCoarse-grained igneous calcium-aluminum-rich inclusions (CAIs) are suggested to have experienced gas-melt isotope exchange of oxygen during the melting events of their precursors. Therefore, their oxygen isotope variation would preserve information about the high-temperature processes in the earliest Solar System. We experimentally determined oxygen isotope exchange kinetics between CAI analog melt and carbon monoxide (CO) gas at 1420 degrees C and 1460 degrees C under CO gas partial pressures of 0.1, 0.5, and 1 Pa to understand the role of CO gas on the oxygen isotope exchange. We observed oxygen isotope zoning profiles inside the reacted samples that formed through the oxygen isotope exchange reaction at the melt surface and oxygen diffusion in the melt. The zoning profiles were fitted using a three-dimensional spherical diffusion model with time-dependent surface concentration. The oxygen isotope exchange efficiency for colliding CO molecules is estimated to be similar to 3.3 x 10(-4), which is much smaller than that for H2O (0.28). The oxygen diffusion coefficient obtained in this study is similar to that obtained in the oxygen isotope exchange experiments between the CAI melt and H2O, suggesting that the diffusion species in the melt is O2-, despite the surrounding atmospheres. A comparison of the isotope exchange reaction kinetics between (1) CAI melt and CO gas, (2) CAI melt and H2O gas, and (3) CO and H2O gases shows that the reaction rate decreases in the order of (3), (2), and (1). The rapid isotope exchange of the reaction (1) indicates that the oxygen isotopic compositions of H2O and CO should have been equilibrated during the melting and crystallization processes of igneous CAIs. Both H2O and CO change the oxygen isotope compositions of molten CAI in the same direction, although reaction (2) controls the isotope exchange timescale between the CAI melt and surrounding gas. Our dataset demonstrates that type B CAIs having melilite with homogeneous oxygen isotope composition should have been heated for 2-3 days at P-H2 > 100 Pa above the melilite liquidus (similar to 1400 degrees C) in the solar protoplanetary disk. (C) 2022 Elsevier Ltd. All rights reserved
ULTRAHIGH-RESOLUTION SPECTROSCOPY OF DIBENZOFURAN TRANSITION
No full textAuthor Institution: Molecular Photoscience Research Center, Kobe University, Kobe; 657-8501, Japan; Graduate School of Science, Kyoto University, Kyoto; 606-8502, JapanDibenzofuran is one of the prototypical molecule of toxic dioxins and it is great important to investigate the excited-state dynamics. We have observed low-resolution spectra for the vibronic structure of the transition of jet-cooled dibenzofuran. Several vibronic bands are stronger than the 0 band. These bands are found to be the -type transition which are enhanced by intensity borrowing through the vibronic coupling with the state. } {\bf 110}, 10000 (2006).} Rotationally resolved ultrahigh-resolution spectra of jet-cooled dibenzofuran for the 0 and 0+443 cm band have been observed. Several thousand lines were assigned and these molecular constants were determined. }, {\bf 238}, 49 (2006).} We have extended the high-resolution spectroscopic measurement for several vibronic bands up to 1335 cm. We analyzed observed rotational lines and determined the molecular constants for each vibronic bands. The Zeeman broadenings of the rotational lines were also observed, and the , -dependence were studied. As a result, the observed Zeeman effects could be explained to be originating from the magnetic moment of the state induced by mixing with state by - coupling
EXCITED-STATE DYNAMICS IN THE S STATE OF DIBENZOFURAN
No full textAuthor Institution: Molecular Photoscience Research Center, Kobe University, Kobe; 657-8501, Japan; Graduate School of Science, Kyoto University, Kyoto; 606-8502, JapanDibenzofuran is a prototypical molecule of toxic dioxins and it is of great importance to investigate the excited-state dynamics. We have analyzed the vibronic structure of the S S transition of jet-cooled dibenzofuran. Several vibronic bands are stronger than the 0 band. These bands are found to be the A-type transition } and the intensity arises from vibronic coupling with the S state. We have observed rotationally resolved ultrahigh-resolution spectra of prominent vibronic bands and the changes with the magnetic field. We analyzed each rotational line and determined the rotational constants. It has been shown that the intramolecular vibrational redistribution (IVR) takes place remarkably in the high vibrational levels, but intersystem crossing (ISC) is not efficient in the isolated dibenzofuran molecule
