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101.
Hajime Obata Yoshiyuki Nozaki Yoshiyuki Yamamoto 《Geochimica et cosmochimica acta》2004,68(5):1035-1048
To carry out comparative geochemical investigation of refractory and reactive metals in different oceanic settings covering different θ-S characteristics, productivity, dissolved oxygen profiles, water and sediment discharge, etc., we have determined the vertical profiles of dissolved (<0.04 μm) Al, In and Ce, as well as 210Pb and 210Po in the eastern Indian Ocean (from 40°S in the Southern Ocean to 8°N in the Bay of Bengal) and the Southeast Asian Seas. In the Antarctic Circumpolar Region, the concentrations of these refractory metals are very low, presumably due to very low the atmospheric input and intensified scavenging. Resemblance in the vertical profiles of these metals is often seen in some other stations. However, there are also significant differences among their distributions, for example, in the magnitude of surface enrichment caused by the external input from eolian and fluvial-coastal sources. Comparison of Al distributions in surface waters with those of atmospherically derived 210Pb suggests the relative importance of eolian input over fluvial-coastal sources. Fluvial and coastal input appears to be insignificant for dissolved In, but may be important for Ce. The mean residence time of Al in the surface mixed layer was estimated to be ∼2 years which is similar to that of 210Pb.In the intermediate and deep waters, the concentrations of each element vary with depth and location. The range of variation is in the order of Al>Ce>In, depending upon particle reactivity. Although dissolved Al decreases along the water trajectory by particle scavenging, variations of dissolved In and Ce are relatively small which may be due to less scavenging for both elements. Compared with significantly high (>4 pM) dissolved Ce throughout the water column in the Bay of Bengal, dissolved Al concentration remains low, suggesting that it has higher affinity to particles and hence is scavenged by sinking particulate matter. This is consistent with the observation that the dissolved Al in the Antarctic Intermediate Water (AAIW) decreases from 4 to 6 nM in the 30°S Perth Basin to <0.7 nM in the 10°S West Australia Basin along its trajectory. Using the chlorofluorocarbons (CFCs) ventilation age of AAIW (Fine, 1993), the mean residence time of Al in the intermediate and deep waters in the eastern Indian Ocean is estimated to be <17 yr, approximately the same as that of 210Pb (10-15 yr). In the semiclosed basins of Southeast Asia, the distributions of Al, In and Ce are also very unique. In the South China Sea, there is a strong sediment source for dissolved In and Ce during the deepwater passage through the Luzon Strait. 相似文献
102.
Compressional wave velocity of granite and amphibolite up to melting temperatures at 1 GPa 总被引:2,自引:0,他引:2
Compressional wave velocities (VP) at above-solidus temperatures and at 1 GPa were obtained for a granite and amphibolite, which are considered to be major constituents of the continental crust. The temperature variation of velocities showed that the VP values of granite decreased with rising temperature, but substantially increased beyond the melting temperature (850–900 °C). Such an increase may be caused by the α–β transition of quartz. The velocities of amphibolite decreased linearly with increasing temperature and dropped sharply at temperatures above the solidus (700 °C), indicating that partial melting of amphibolite acts to significantly lower the seismic velocities. 相似文献
103.
Hitoshi Koide Yoshiyuki Tazaki Yoshikazu Noguchi Masaki Iijima Kazuitsu Ito Yuji Shindo 《Engineering Geology》1993,34(3-4):175-179
Depleted reservoirs of natural gas and petroleum can provide excellent traps for carbon dioxide. Deep aquifers, which are not used due to high salinity, can host larger amount of the carbon dioxide under their high formation pressure than natural gas and oir reservoirs. Small fraction of aquifers in sedimentary basins in the world are enough to host about 87 gigaton-C of carbon dioxide.
A preliminary technical and economical survey on the carbon dioxide injection system suggests that the energy requirement for carbon dioxide injection into subterranean aquifers is about 269 kWh/ton-C and that the investment and operation costs for system are 79 $/ton-C. By our preliminary cost estimation in Japan, the CO2-emission-free electricity generation may become possible with a cost increase of 35% for natural-gas-fired power station, and of 60% for coal-fired-power station. 相似文献
104.
Yoshiyuki Tatsumi Mitsuhiro Murasaki Edy M. Arsadi Susumu Nonda 《Contributions to Mineralogy and Petrology》1991,107(2):137-149
Major and trace element, and Sr-Nd isotope compositions were determined for Quaternary volcanic rocks from NE Sulawesi (the Sangihe are), Indonesia, in order to examine the origin of across-arc variation in lava and magma source chemistry. The arc is formed in an intraoceanic tectonic setting and is not associated with a backarc basin, thereby minimizing possible contributions from non-arc geochemical reservoirs. The geochemistry of these arc lavas is likely to provide essential information about the chemical characteristics of subduction components. All incompatible elements, except Pb, increase away from the volcancic front. Major element data for Mg-rich lavas together with available experimental data, suggest that primary magmas are produced at higher pressured by smaller degrees of partial melting beneath the backarc-side volcanoes. Rb/K and Ba/Pb are higher, and 87Sr/86Sr and 143Nd/144Nd are lower in backarc-side lavas. These variations may be attributed to generation of hydrous fluids in the downdragged hydrous peridotite layer at the base of the mantle wedge through the following reactions: decompositions of pargasitic amphibole to form phlogopite and breakdown of phlogopite to crystallize K-richterite, beneath the volcanic front and the backarc-side volcanoes, respectively. 相似文献
105.
An absarokite from a phlogopite lherzolite source 总被引:1,自引:0,他引:1
An absarokite (SiO2 47.72 wt %, K2O 3.41 wt %) occurs in the Katamata volcano, SW Japan. The rock carries phenocrysts of olivine, phlogopite, clinopyroxene, and hornblende. Chemical compositions of bulk rock (FeO*/ MgO 0.73) and minerals (Mg-rich olivine and phlogopite, Cr-rich chromite) suggest that the absarokite is not differentiated. Melting experiments at high pressures on the Katamata absarokite have been conducted. The completely anhydrous absarokite melt coexists with olivine, orthopyroxene, and clinopyroxene at 1310° C and 1.0 GPa. The melt with 3.29 wt % of H2O also coexists with the above three phases at 1230° C and 1.4 GPa; phlogopite appears at temperatures more than 80° C below the liquidus. On the other hand, the melt is not saturated with lherzolite minerals in the presence of 5.13 wt % of H2O and crystallizes olivine and phlogopite as liquidus phases; the stability limit of phlogopite is little affected at least by the present variation of H2O content in the absarokite melt. It is suggested that the absarokite magma was segregated from the upper mantle at 1170° C and 1.7 GPa leaving a phlogopite lherzolite as a residual material on the basis of the above experimental results and the petrographical observation that olivine and phlogopite crystallize at an earlier stage of crystallization sequence than clinopyroxene. The contribution of phlogopite at the stage of melting processes is also suggested by the geochemical characteristics that the absarokite is more enriched in Rb, K, and Ba and depleted in Ca and Na than a typical alkali olivine basalt from the same volcanic field. 相似文献
106.
210Pb in the surface water of the North Pacific was extensively determined. The results showed that the highest concentrations of210Pb of 19 ± 3dpm/100kg were found in the northern mid-latitudes around 30°N, but longitudinal variation across the North Pacific was not observed. The mean residence time of210Pb in the surface water up to 100 m in depth is calculated to be 230 days. In the mid-latitudes of the northern hemisphere,210Pb may be transported by the prevailing westerly wind of a higher speed than 15 m/sec, likely the jet stream. 相似文献
107.
Ram C. Sharma Ryutaro Tateishi Keitarou Hara Saeid Gharechelou Kotaro Iizuka 《International Journal of Digital Earth》2016,9(10):1004-1020
An improved methodology for the extraction and mapping of urban built-up areas at a global scale is presented in this study. The Moderate Resolution Imaging Spectroradiometer (MODIS)-based multispectral data were combined with the Visible Infrared Imager Radiometer Suite (VIIRS)-based nighttime light (NTL) data for robust extraction and mapping of urban built-up areas. The MODIS-based newly proposed Urban Built-up Index (UBI) was combined with NTL data, and the resulting Enhanced UBI (EUBI) was used as a single master image for global extraction of urban built-up areas. Due to higher variation of the EUBI with respect to geographical regions, a region-specific threshold approach was used to extract urban built-up areas. This research provided 500-m-resolution global urban built-up map of year 2014. The resulted map was compared with three existing moderate-resolution global maps and one high-resolution map in the United States. The comparative analysis demonstrated finer details of the urban built-up cover estimated by the resultant map. 相似文献
108.
K–Ar geochronology of a Quaternary monogenetic volcano group in Ojika Jima District, Southwest Japan
Masafumi Sudo Kozo Uto Yoshiyuki Tatsumi Kazunori Matsui 《Bulletin of Volcanology》1998,60(3):171-186
An unspiked K–Ar dating method using a mass-fractionation correction procedure was applied to a Quaternary independent group
of monogenetic volcanoes, Ojikajima Volcano Group, located in northwestern Kyushu in Southwest Japan, in order to clarify
in detail secular variations in eruptive volume, locations of eruptive vents, and magma compositions in a single monogenetic
volcano group. The major results were as follows: (a) K–Ar ages of monogenetic volcanoes distribute from 1.08 to 0.30 Ma,
with voluminous peaks at approximately 1.0 and 0.6 Ma. (b) The volcanic activity commenced in the central part of the field,
expanded to the whole field at approximately 0.6 Ma, and then shrank to the central area. (3) Concentrations of incompatible
elements, such as Ba, K, and Nb, increase with decreasing age, whereas P, Y, and Zr concentrations remain constant. These
concentrations suggest gradual decrease in the degree of partial melting from an identical mantle source with residual garnet.
Received: 15 December 1997 / Accepted: 23 May 1998 相似文献
109.
Dia Sotto Alibo Hiroshi Amakawa Yoshiyuki Nozaki 《Journal of Earth System Science》1998,107(4):359-366
Two methods have been developed to measure indium (In) in natural waters by flow injection inductively coupled plasma mass
spectrometry (ICPMS). One is the isotope dilution technique using an113In enriched spike and the other utilizes natural yttrium present in the sample as an internal standard. In the former, optimization
of the113In spike to minimize error is often difficult for samples in which In concentrations are variable, whereas in the latter method,
a separate determination of Y in the sample is necessary and hence more sample is required. Using about 1 liter of a water
sample, 200 fold preconcentration of In was performed by solvent extraction and back extraction technique and then introduced
into the ICPMS to measure the113In/115In or115In/89Y ratios. The detection limits were 0.01–0.02 pmol kg−1 for both methods.
Application of the methods to seawater samples yielded the concentrations of 0.06–0.15 pmol kg−1 for the Pacific and 0.6–1.5 pmol kg−1 for the Atlantic. The large inter-oceanic variation of In best resembles that of Al amongst the 3B group of elements in the
periodic table. River and estuarine samples gave a more variable range of concentrations of 0.01–15 pmol kg−1. Most of the In supplied by rivers is removed by scavenging in the estuarine mixing zone, suggesting that the fluvial input
of In to the ocean is small. 相似文献
110.
A mechanism of interdecadal variability of tropical cyclone activity over the western North Pacific 总被引:7,自引:0,他引:7
Tropical cyclone (TC) activity in the western North Pacific (WNP) has changed interdecadally with an approximately 20-year period between 1951 and 1999. The cause and mechanism of interdecadal variability of TC frequency in the WNP is investigated using NCEP/NCAR reanalysis and the result obtained from a high-resolution coupled general circulation model (CGCM). The interdecadal variability of TC activity in the WNP correlates with long-term variations in sea surface temperatures (SSTs) in the tropical central Pacific and with those of westerly wind anomalies associated with the monsoon trough that appears over the tropical WNP during the typhoon season of July to October. The westerly wind anomalies at near 10°N show positive feedback with the SST anomalies in the central Pacific. Therefore, the interdecadal variability of TC frequency is related to long-term variations in atmosphere–ocean coupling phenomena in the tropical North Pacific. A 50-year long-run simulation using the high-resolution CGCM showed the robustness of interdecadal variability of TC frequency. 相似文献