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291.
Nagayoshi Katsuta Masao Takano Naomi Sano Yukinori Tani Shinya Ochiai Sayuri Naito Takuma Murakami Masakazu Niwa Shin‐ichi Kawakami 《Sedimentology》2019,66(6):2490-2510
Micro‐X‐ray fluorescence scanning spectroscopy of marine and lake sedimentary sequences can provide detailed palaeoenvironmental records through element intensity proxy data. However, problems with the effects of interstitial pore water on the micro‐X‐ray fluorescence intensities have been pointed out. This is because the X‐ray fluorescence intensities are measured directly at the surfaces of split wet sediment core samples. This study developed a new method for correcting X‐ray fluorescence data to compensate for the effects of pore water using a scanning X‐ray analytical microscope. This involved simultaneous use of micro‐X‐ray fluorescence scanning spectroscopy and an X‐ray transmission detector. To evaluate the interstitial pore water content from the X‐ray transmission intensities, a fine‐grained sediment core retrieved from Lake Baikal (VER99‐G12) was used to prepare resin‐embedded samples with smooth surfaces and uniform thickness. Simple linear regression between the linear absorption coefficients of the samples and their porosity, based on the Lambert–Beer law, enabled calculation of the interstitial pore spaces and their resin content with high reproducibility. The X‐ray fluorescence intensities of resin‐embedded samples were reduced compared with those of dry sediment samples because of: (i) the X‐ray fluorescence absorption of resin within sediment; and (ii) the sediment dilution effects by resin. An improved micro‐X‐ray fluorescence correction equation based on X‐ray fluorescence emission theory considers the instrument's sensitivity to each element, which provides a reasonable explanation of these two effects. The resin‐corrected X‐ray fluorescence intensity was then successfully converted to elemental concentrations using simple linear regression between the data from micro‐X‐ray fluorescence scanning spectroscopy and from the conventional analyzer. In particular, the calculated concentration of SiO2 over the depth of the core, reflecting diatom/biogenic silica concentration, was significantly changed by the calibrations, from a progressively decreasing trend to an increasing trend towards the top of the core. 相似文献
292.
Yuki Chan Amy Li Singaram Gopalakrishnan Paul K.S. Shin Rudolf S.S. Wu Stephen B. Pointing Jill M.Y. Chiu 《Marine pollution bulletin》2014
Hypoxia alters the oxidation–reduction balance and the biogeochemical processes in sediments, but little is known about its impacts on the microbial community that is responsible for such processes. In this study, we investigated the effects of hypoxia and the ubiquitously dispersed flame-retardant BDE47 on the bacterial communities in marine surface sediments during a 28-days microcosm experiment. Both hypoxia and BDE47 alone significantly altered the bacterial community and reduced the species and genetic diversity. UniFrac analysis revealed that BDE47 selected certain bacterial species and resulted in major community shifts, whereas hypoxia changed the relative abundances of taxa, suggesting slower but nonetheless significant community shifts. These two stressors targeted mostly different taxa, but they both favored Bacteroidetes and suppressed Gammaproteobacteria. Importantly, the impacts of BDE47 on bacterial communities were different under hypoxic and normoxic conditions, highlighting the need to consider risk assessments for BDE47 in a broader context of interaction with hypoxia. 相似文献
293.
Shiang‐Jung Wang Jenn‐Shin Hwang Kuo‐Chun Chang Chia‐Yi Shiau Wang‐Chuen Lin Mu‐Sen Tsai Jia‐Xiang Hong Yin‐Han Yang 《地震工程与结构动力学》2014,43(10):1443-1461
The rolling motion of mutually orthogonal rollers respectively sandwiched between two bearing plates in which one or both have V‐shaped sloping surfaces makes the sloped rolling‐type isolation device have an excellent in‐plane seismic isolation performance. In this study, the sloped rolling type isolation device in which a single roller moves between two V‐shaped sloping surfaces along each principle horizontal direction is refined by incorporating multi‐roller, built‐in damping, and pounding prevention mechanisms. The associated dynamic behavior is further clarified, and a simplified twin‐flag hysteretic model, which can be easily applied in most commercial computational tools is then proposed. Seismic simulation tests on the refined isolation devices (i.e. the sloped multi‐roller isolation devices) with different design parameters such as sloping angles of bearing plates and built‐in damping capabilities, together with a raised floor system by employing the sloped multi‐roller isolation devices, were conducted. Not only is the efficiency of the sloped multi‐roller isolation devices in seismically protecting the important objects, but also the practicability and accuracy of the proposed simplified numerical model in predicting the seismic responses of the sloped multi‐roller isolation devices is experimentally verified. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
294.
Hongjoon Shin Younghun Jung Changsam Jeong Jun-Haeng Heo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(1):105-114
An important problem in frequency analysis is the selection of an appropriate probability distribution for a given sample
data. This selection is generally based on goodness-of-fit tests. The goodness-of-fit method is an effective means of examining
how well a sample data agrees with an assumed probability distribution as its population. However, the goodness of fit test
based on empirical distribution functions gives equal weight to differences between empirical and theoretical distribution
functions corresponding to all observations. To overcome this drawback, the modified Anderson–Darling test was suggested by
Ahmad et al. (1988b). In this study, the critical values of the modified Anderson–Darling test statistics are revised using simulation experiments
with extensions of the shape parameters for the GEV and GLO distributions, and a power study is performed to test the performance
of the modified Anderson–Darling test. The results of the power study show that the modified Anderson–Darling test is more
powerful than traditional tests such as the χ2, Kolmogorov–Smirnov, and Cramer von Mises tests. In addition, to compare the results of these goodness-of-fit tests, the
modified Anderson–Darling test is applied to the annual maximum rainfall data in Korea. 相似文献
295.
Taesam Lee Juyoung Shin Taewoong Park Dongryul Lee 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(1):251-263
Hydrologic responses to variations in storm direction provide useful information for the analysis and prediction of floods and the development of watershed management strategies. However, the prediction of hydrologic responses to changes in storm direction is a difficult task that requires meteorological simulations and extensive computation. It is also difficult to identify the center of rotation of a storm affecting a basin of interest. Therefore, we propose a simple approach of rotating the basin position relative to the storm within the rainfall–runoff simulation model instead of changing the pathway of the storm, which we term the basin rotation method (BRM). The proposed BRM was tested on four major typhoon events in South Korea. The results illustrated that the original basin orientation (i.e., before it was rotated) exhibits earlier and higher peak discharge and earlier recession compared to the basin after rotation. We conclude that the proposed method (BRM) is a viable alternative for use in assessing the directional influence of moving storms on floods caused by historical rather than hypothetical storm events. 相似文献
296.
297.
Research and development of the New Generation Sea Surface Temperature for Open Ccean (NGSST-O) product and its demonstration operation 总被引:1,自引:0,他引:1
Futoki Sakaida Hiroshi Kawamura Shin Takahashi Teruhisa Shimada Yoshimi Kawai Kohtaro Hosoda Lei Guan 《Journal of Oceanography》2009,65(6):859-870
Real-time generation and distribution of the New Generation Sea Surface Temperature for Open Ocean (NGSST-O) product began
in September 2003 as a demonstration operation of the Global Ocean Data Assimilation Experiment (GODAE) High-Resolution Sea
Surface Temperature Pilot Project. Satellite sea surface temperature (SST) observations from infrared radiometers (AVHRR,
MODIS) and a microwave radiometer (AMSR-E) are objectively merged to generate the NGSST-O product, which is a quality-controlled,
cloud-free, high-spatial-resolution (0.05° gridded), wide-coverage (13–63° N, 116–166° E), daily SST digital map. The NGSST-O
demonstration operation system has been developed in cooperation with the Japanese Space Agency (JAXA) and has produced six
years of continuous data without gaps. Comparison to in situ SSTs measured by drifting buoys indicates that the root mean-square error of NGSST-O has been kept at approximately 0.9°C. 相似文献
298.
Many metallic ore deposits of the Late Cretaceous to Early Tertiary periods are distributed in the Gyeongsang Basin. Previous and newly analyzed sulfur isotope data of 309 sulfide samples from 56 ore deposits were reviewed to discuss the genetic characteristics in relation to granitoid rocks. The metallogenic provinces of the Gyeongsang Basin are divided into the Au–Ag(–Cu–Pb–Zn) province in the western basin where the sedimentary rocks of the Shindong and Hayang groups are distributed, Pb–Zn(–Au–Ag–Cu), Cu–Pb–Zn(–Au–Ag), and Fe–W(–Mo) province in the central basin where the volcanic rocks of the Yucheon Group are dominant, and Cu(–Mo–W–Fe) province in the southeastern basin where both sedimentary rocks of the Hayang Group and Tertiary volcanic rocks are present. Average sulfur isotope compositions of the ore deposits show high tendencies ranging from 2.2 to 11.7‰ (average 5.4‰) in the Pb–Zn(–Au–Ag–Cu) province, ?0.7 to 11.5‰ (average 4.6‰) in the Cu–Pb–Zn(–Au–Ag) province, and 3.7 to 11.4‰ (average 7.5‰) in the Fe–W(–Mo) province in relation to magnetite‐series granitoids, whereas they are low in the Au–Ag(–Cu–Pb–Zn) province in relation to ilmenite‐series granitoids, ranging from ?2.9 to 5.7‰ (average 1.7‰). In the Cu(–Mo–W–Fe) province δ34S values are intermediate ranging from 0.3 to 7.7‰ (average 3.6‰) and locally high δ34S values are likely attributable to sulfur derived from the Tertiary volcanic rocks during hydrothermal alteration through faults commonly developed in this region. Magma originated by the partial melting of the 34S‐enriched oceanic plate intruded into the volcanic rocks and formed magnetite‐series granitoids in the central basin, which contributed to high δ34S values of the metallic deposits. Conversely, ilmenite‐series granitoids were formed by assimilation of sedimentary rocks rich in organic sulfur that influenced the low δ34S values of the deposits in the western and southeastern provinces. 相似文献
299.
The Middle Miocene Tsushima granite pluton is composed of leucocratic granites, gray granites and numerous mafic microgranular enclaves (MME). The granites have a metaluminous to slightly peraluminous composition and belong to the calc‐alkaline series, as do many other coeval granites of southwestern Japan, all of which formed in relation to the opening of the Sea of Japan. The Tsushima granites are unique in that they occur in the back‐arc area of the innermost Inner Zone of Southwest Japan, contain numerous miarolitic cavities, and show shallow crystallization (2–6 km deep), based on hornblende geobarometry. The leucocratic granite has higher initial 87Sr/86Sr ratios (0.7065–0.7085) and lower εNd(t) (?7.70 to ?4.35) than the MME of basaltic–dacitic composition (0.7044–0.7061 and ?0.53 to ?5.24), whereas most gray granites have intermediate chemical and Sr–Nd isotopic compositions (0.7061–0.7072 and ?3.75 to ?6.17). Field, petrological, and geochemical data demonstrate that the Tsushima granites formed by the mingling and mixing of mafic and felsic magmas. The Sr–Nd–Pb isotope data strongly suggest that the mafic magma was derived from two mantle components with depleted mantle material and enriched mantle I (EMI) compositions, whereas the felsic magma formed by mixing of upper mantle magma of EMI composition with metabasic rocks in the overlying lower crust. Element data points deviating from the simple mixing line of the two magmas may indicate fractional crystallization of the felsic magma or chemical modification by hydrothermal fluid. The miarolitic cavities and enrichment of alkali elements in the MME suggest rapid cooling of the mingled magma accompanied by elemental transport by hydrothermal fluid. The inferred genesis of this magma–fluid system is as follows: (i) the mafic and felsic magmas were generated in the mantle and lower crust, respectively, by a large heat supply and pressure decrease under back‐arc conditions induced by mantle upwelling and crustal thinning; (ii) they mingled and crystallized rapidly at shallow depths in the upper crust without interaction during the ascent of the magmas from the middle to the upper crust, which (iii) led to fluid generation in the shallow crust. The upper mantle in southwest Japan thus has an EMI‐like composition, which plays an important role in the genesis of igneous rocks there. 相似文献
300.
Two leading but independent modes of Northern Pacific atmospheric circulation: the North Pacific Oscillation (NPO) and the Pacific Meridional Mode (PMM), are known external triggers of the El Niño-Southern Oscillation (ENSO) by the sequential migration of sea surface temperature (SST) anomalies into the tropics possibly by means of wind-evaporation-SST (WES) feedbacks. Because of the similar roles of NPO and PMM, most previous studies have explored them with no separation. Here, we investigate their independent and combined effects in triggering ENSO, and find that when the NPO and PMM occur simultaneously during spring, ENSO or ENSO-like SST anomalies are generated during the following winter; whereas when either the NPO or PMM occur alone, ENSO events rarely occur. Furthermore, the relationship between NPO and PMM shows noticeable interdecadal variability, which is related to decadal changes in the mean upper-level jet stream over the North Pacific. Changes in the upper-level jet stream modify the location of the center of the Aleutian Low, which plays a role in bridging the NPO and PMM processes, especially when it migrates to the southwest. The period when NPO and PMM are well correlated coincides somewhat with the active ENSO period, and vice versa, indicating that a more efficient trigger due to combined NPO-PMM processes results in a higher variation of ENSO. Finally, analysis of the coupled model control simulations strongly supports our observational analysis results. 相似文献