Estimation of groundwater residence time using the 36Cl bomb pulse   总被引：1，自引：0，他引：1  

Tosaki Y  Tase N  Sasa K  Takahashi T  Nagashima Y 《Ground water》2011,49(6):891-902

We propose a methodology for estimating the residence time of groundwater based on bomb-produced (36)Cl. Water samples were collected from 28 springs and 2 flowing wells located around Mt. Fuji, Central Japan. (36)Cl/Cl ratios in the water samples, determined by accelerator mass spectrometry (AMS), were between 43 × 10(-15) and 412 × 10(-15). A reference time series of the above-background (i.e., bomb-derived) (36)Cl concentration was constructed by linearly scaling the background-corrected Dye-3 data according to the estimated total bomb-produced (36)Cl fallout in the Mt. Fuji area. Assuming piston flow transport, estimates of residence time were obtained by comparing the measured bomb-derived (36)Cl concentrations in spring water with the reference curve. The distribution of (36)Cl-based residence times is basically consistent with that of tritium-based estimates calculated from data presented in previous studies, although the estimated residence times differ between the two tracers. This discrepancy may reflect chlorine recycling via vegetation or the relatively small change in fallout rate, approximately since 1975, which would give rise to large uncertainties in (36)Cl-based estimates of recharge for the period, approximately since 1975. Given the estimated ages for groundwater from flowing wells, dating based on a (36)Cl bomb pulse may be more reliable and sensitive for groundwater recharged before 1975, back as far as the mid-1950s.  相似文献   

Erratum to K. Sakata, N. Kitadai and T. Yokoyama (2010) “Effects of pH and temperature on dimerization rate of glycine: Evaluation of favorable environmental conditions for chemical evolution of life” Geochimica et Cosmochimica Acta 74, 6841-6851     

Kasumi Sakata  Norio Kitadai 《Geochimica et cosmochimica acta》2011,75(21):6720-6722

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Diversity analysis of protistan microplankton in Sagami Bay by 18S rRNA gene clone analysis using newly designed PCR primers     

Sau Pin Kok  Tomohiko Kikuchi  Tatsuki Toda  Norio Kurosawa 《Journal of Oceanography》2012,68(5):599-613

The diversity of protistan microplankton in Sagami Bay was revealed by 18S rRNA gene clone analysis using newly designed PCR primers. PCR amplification consisted of a first reaction targeting the V3–V5 region of the 18S rRNA gene, followed by a nested reaction targeting the V3–V4 region. In total, 629 clones consisting of 108 phylotypes were affiliated with a variety of protistan groups including dinoflagellates, diatoms, prymnesiomonada, chlorophyta, ciliophora, cercozoa, and heterokonta. The dinoflagellate group was detected most frequently and shared approximately 74?% of the total clones. Within this group, approximately half of the clones belonged to the parasitic dinoflagellate Syndiniales group I, which was first reported from Sagami Bay. The genera Woloszynskia, Gonyaulax, Neoceratium, and Karlodinium have not been reported from this bay until now. The second most frequent group was diatoms, which shared approximately 22?% of the total clones. Within this group, highly diverse Thalassiosira phylotypes were detected, and they shared approximately 70?% of the diatom clones. Therefore, highly diverse protists including some candidate groups were successfully detected, indicating that the designed primers and PCR protocol will be useful for molecular diversity analyses of protistan microplankton communities in aquatic environments.  相似文献   

What constitutes successful participatory disaster risk management? Insights from post-earthquake reconstruction work in rural Gujarat,India     

Subhajyoti Samaddar  Norio Okada  Junho Choi  Hirokazu Tatano 《Natural Hazards》2017,85(1):111-138

Although for decades, public participation in disaster risk management has been strongly advocated for, in reality, it remains elusive. Planners and practitioners are still struggling to find ways to meaningfully involve the local community in disaster management programs; so far, apparently successful projects and initiatives have seldom been scaled up or replicated. The reason for this is that no comprehensive framework for participatory disaster risk management exists, and no systematic evaluation has been made to assess the necessary elements and appropriate paths for meaningful public participation in disaster management. This study attempts to examine the process and identify outcome-based factors that account for successful participatory disaster risk management. To accomplish this, we have evaluated reconstruction projects in earthquake-affected rural Gujarat, India, where the government envisioned a people-centric reconstruction project, but provided no public participation framework or guidelines. As a result, several reconstruction models pursuing different levels and types of public participation ultimately emerged. We selected three dominant reconstruction approaches and examined the extent to which various processes and outcome-based factors were successful in promoting ideal levels of public participation during these reconstruction projects. This study is considered an example of pioneering research in defining factors that account for successful participatory disaster risk management.  相似文献   

Recognition of shear heating on a long‐lived major fault using Raman carbonaceous material thermometry: implications for strength and displacement history of the MTL,SW Japan          下载免费PDF全文

Hiroshi Mori  Simon Wallis  Koichiro Fujimoto  Norio Shigematsu 《Island Arc》2015,24(4):425-446

The extent to which movement on major faults causes long term shear heating is a contentious issue and an important aspect in the debate about the strength of major faults in the crust. Comparing the results of experimental work on the kinetics of crystallization of carbonaceous material with results of thermal modeling show that the Raman carbonaceous material (CM) geothermometer is well suited to studying shear heating on geological time scales in suitable lithologies exposed around exhumed major fault zones. The Median Tectonic Line (MTL), SW Japan, is the largest on‐land fault in Japan with a length of > 800 km. Application of Raman CM thermometry to pelitic schist adjacent to the fault reveals the presence of a rise in peak temperature of around 60 °C over a distance of around 150 m perpendicular to the MTL fault plane. The spatial association of this thermal anomaly with the fault implies it is due to shear heating. Thermal modeling shows the recorded thermal anomaly and steep temperature gradient is compatible with very high rates of displacement over time scales of a few thousand years. However, the implied displacement rates lie outside those generally observed. An alternative explanation is that an originally broader thermal anomaly that developed during strike slip faulting was shortened due to the effects of normal faulting. Constraints on displacement rate, width of the original anomaly, duration of heating and peak temperature imply a coefficient of friction, μ, greater than 0.4.  相似文献   

Diverse mineralogical and oxygen isotopic signatures recorded in CV3 carbonaceous chondrites     

Hatsumi Ishida  Tomoki Nakamura  Hitoshi Miura  Yuki Kakazu 《Polar Science》2012,6(3-4):252-262

We describe the petrography and mineralogy of six CV3 carbonaceous chondrites. LAP02206, LAP02228, LAP04843, and GRA06101 are classified as oxidized Allende-like chondrites (CV3_oxA). RBT04143 and QUE97186 are classified as members of the reduced subtype (CV3_red). Chondrules in the CV3_oxA chondrites show extensive Fe–Mg zoning. Fe-rich olivine in the rims of the CV3_oxA chondrules are ¹⁶O-poor relative to Mg-rich olivine in the cores, suggesting that in addition to Fe and Mg, oxygen was exchanged between chondrules and matrix during weak thermal metamorphism. The CV3_red chondrites appear to have formed through various processes. QUE97186 shows chondrule flattening with a preferred orientation, which is interpreted to have resulted from shock impact at a pressure of ～20 GPa. The post-shock residual heat (～1000 °C) is likely to be responsible for the restricted Fe/Mg ratios of matrix olivine. Based on the degree of Fe–Mg homogenization of matrix olivines, we estimate the spatial scale of the shock-heated region to be ～1 m. RBT04143 is a breccia containing many clasts of two types of lithologies: reduced-type material and very weakly altered material.  相似文献   

Geochemical characteristics of pelagic chert sequences across the Permian-Triassic boundary in southwest Japan   总被引：1，自引：0，他引：1  

Hroaki  Ishiga  Kotaro  Ishida  Kaori  Dozen Makoto  Musashino 《Island Arc》1996,5(2):180-180

Abstract Geochemical characteristics, mainly of major and trace elements and REE (rare earth elements) of bedded chert and shale/mudstone sequences, across the Permian/Triassic boundary in southwest Japan are examined. The boundary is characterized by the disappearance of bedded cherts, and the interval between the Upper Permian cherts and Lower Triassic (probably Smithian) cherts comprises siliceous shales and organic black mudstones. Bedded cherts are characterized by a gradual depletion of chemical elements from Middle to Upper Permian. However, overlying siliceous shales exhibit a clear enrichment in some elements, especially alkaline metals (such as K, Rb and Cs) and Ti, Th, Y, P₂O₅, and REE in comparison with elements of the PAAS (post Archean Australian shales). This indicates that average components of the upper continental crust were transported in the boundary interval, possibly caused by volcanic activity. Ce-negative shifting in NASC (North American Shales Composite)-normalized REE patterns is characteristic of this interval, and could be related to the deposition of siliceous rocks in Ce-depleted seawater. This was probably caused by an invasion of water mass with a Ce-negative anomaly into the previously existing water mass of the Paleo-Tethys. Weak negative Eu-anomalies in this interval are suggestive of plagioclase fractionation caused by acid volcanisms and the LREE/HREE ratios in the interval show a slightly light-REE enrichment. Organic black mudstones are characteristically intercalated in the interval. These rocks are usually regarded as a product of oceanic deterioration, but in pelagic conditions, organic materials were formed by high primary production that resulted from the active upwelling of ocean floor water currents with rich nutrients. This may have been caused by the inferred mixing of water masses of the Paleo-Tethys and of the Panthalassa in Early Triassic time which was regarded as an event synchronous with an increase in volcanic activity on highly matured island arcs and/or continents.  相似文献   

Radiolarian-bearing conglomerate from the Hayang Group, the Kyongsang Supergroup, southeastern Korea   总被引：1，自引：0，他引：1  

T. Mitsugi  K. Ishida  B. -G. Woo  K. -H. Chang  S. -O. Park  H. Hirano 《Journal of Asian Earth Sciences》2001,19(6):87

The non-marine Cretaceous Kyongsang Supergroup, which is divided into the Sindong, the Hayang and the Yuchon groups, is widely distributed in southeastern Korea. Radiolarian-bearing pebbles are collected from the conglomerates of the Kumidong and the Kisadong formations of the Hayang Group. The age of radiolarian fossils range from Late Permian to Middle Jurassic. In Korea, Permian to Middle Jurassic marine chert beds are not exposed. The directions of paleocurrents of the Kumidong and the Kisadong formations are mainly from the northeast to southwest. During Cretaceous time, the Mino-Tamba Belt, within which Permian to Middle Jurassic chert beds are exposed, is suggested to have been located northeast of the Kyongsang Basin. The radiolarian faunas of the Hayang Group are similar to those of the Mino-Tamba Belt and other associated Mesozoic accretionary belts in Japan (e.g. the Ashio Belt). The provenance of the radiolarian-bearing pebbles collected from the Kumidong and the Kisadong formations is interpreted to be the Mino-Tamba Belt and other associated Mesozoic accretionary belts in Japan.  相似文献   

Groundwater contamination in Japan     

Norio Tase 《Environmental Geology》1992,20(1):15-20

Problems on groundwater contamination in Japan are briefly summarized in this paper. Although normal physical conditions in Japan restrict the possibilities of groundwater contamination, human activities are threatening groundwater resources. A survey by the Environment Agency of Japan showed nationwide spreading of organic substances, such as trichloroethylene as well as nitrogen compounds. Synthetic detergents have also been detected even in rural areas and in deep confined aquifers, although their concentrations are not as high. Public awareness of agrichemical or pesticides abuse, especially from golf courses, is apparent. Other problems such as nitrate-nitrogen, leachate from landfills, and the leaking of underground storage tanks are also discussed.  相似文献   

Mineralogy and geothermometry of high-temperature rhyolites from the central and western Snake River Plain     

Norio Honjo  Bill Bonnichsen  William P Leeman  John C Stormer Jr 《Bulletin of Volcanology》1992,54(3):220-237

Voluminous mid-Miocene rhyolitic ash-flow tuffs and lava flows are exposed along the northern and southern margins of the central and western Snake River Plain. These rhyolites are essentially anhydrous with the general mineral assemblage of plagioclase ±sanidine ± quartz + augite + pigeonite ± hypersthene ± fayalitic olivine + Fe-Ti oxides + apatite + zircon which provides an opportunity to compare feldspar, pyroxene, and Fe-Ti oxide equilibration temperatures for the same rocks. Estimated pyroxene equilibration temperatures (based on the geothermometers of Lindsley and coworkers) range from 850 to 1000°C, and these are well correlated with whole-rock compositions. With the exception of one sample, agreement between the two-pyroxene thermometers tested is well within 50°C. Fe-Ti oxide geothermometers applied to fresh magnetite and ilmenite generally yield temperatures about 50 to 100°C lower than the pyroxene temperatures, and erratic results are obtained if these minerals exhibit effects of subsolidus oxidation and exsolution. Results of feldspar thermometry are more complicated, and reflect uncertainties in the thermometer calibrations as well as in the degree of attainment of equilibrium between plagioclase and sanidine. In general, temperatures obtained using the Ghiorso (1984) and Green and Usdansky (1986) feldspar thermometers agree with the pyroxene temperatures within the respective uncertainties. However, uncertainties in the feldspar temperatures are the larger of the two (and exceed ±60°C for many samples). The feldspar thermometer of Fuhrman and Lindsley (1988) produces systematically lower temperatures for many of the samples studied. The estimated pyroxene temperatures are considered most representative of actual magmatic temperatures for these rhyolites. This range of temperatures is significantly higher than those for rhyolites from many other suites, and is consistent with the hypothesis that the Snake River Plain rhyolitic magmas formed by partial fusion of relatively dry (e.g. granulitic) crustal lithologies.  相似文献