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101.
The determination of rare earth elements (REEs), Th and U in seaweeds of various species and in ambient surface seawater were performed by inductively coupled plasma mass spectrometry. The seaweeds and the seawater samples were collected at 10 different coastal areas of Niigata Prefecture in Japan twice a year (spring and autumn) in 2004 and 2005. Results showed that concentration of REEs in seaweed species from Niigata Prefecture were about 103 times higher than those in seawater, and the enrichment factors of REEs were larger in heavy REE than light REE. A significant concentration difference of REEs, Th and U was found among species even in the same phylum. Undaria pinnatifida had the highest concentration of U. Considering that U. pinnatifida has low concentrations of REEs among typical brown algae, different REEs and U uptake mechanisms are suggested. The concentration of REEs, Th and U did not vary remarkably between sampling points and/or seasons. 相似文献
102.
103.
A rock magnetic investigation was carried out on a sedimentary core taken from the distal portion of the Bengal Fan in order to reconstruct the South Asian monsoon variability during the past 800 kyr. The 10.2 m long piston core MR0503-PC3, recovered at a water depth of 4400 m, consists of clay to silty clay with minor amounts of nannofossils. An age model for the MR0503-PC3 core is established by correlating a relative paleointensity record of the core [Suganuma Y., Yamazaki, T., Kanamatsu, T., Hokanishi, N., 2008. Relative paleointensity record during the last 800 kyr from the equatorial Indian Ocean: implication for relationship between inclination and intensity variations. Geochemistry, Geophysics, Geosystems. 9, Q02011. doi:10.1029/2007GC001723.] to the global paleointensity stack “Sint-800” [Guyodo, Y., Valet, J.P., 1999. Global changes in intensity of the Earth's magnetic field during the past 800 kyr. Nature. 399, 249–252.]. The age model is consistent with the published ages of tephra layers intercalated in the core, and shows continuous sedimentation during the past 800 kyr.Temporal variations in rock magnetic proxies for the magnetic concentration (ARM, IRM, and HIRM), the grain size (Mrs/Ms), and the composition (S?0.3T and S?0.1T) show that the amount of fine-grained magnetite increased during interglacial stages, and then gradually decreased toward the following glacial maxima. This indicates that the supply of fine-grained magnetite probably originated from areal expansion and/or increased pedogenic activity in the Ganges and Brahmaputra Rivers catchment. Increases during warmer periods suggest intensification of the South Asian summer monsoon during interglacial stages. During marine isotope stages (MIS) 15–11, enhancement of fine-grained magnetite and increased hematite and maghemite contributions are observed. These suggest a significant intensification of the South Asian summer monsoon during this period. Our record and other paleoclimatic reconstructions mainly from the low and mid-latitudes suggest that a major climatic event possibly occurred prior to the mid-Brunhes event (MBE), but the timing is not synchronous. 相似文献
104.
激光雷达在沙尘观测中的应用——2004年春季北京和呼和浩特沙尘天气的解析 总被引:4,自引:0,他引:4
2004年春季(2003年12月至2004年5月)利用激光雷达在北京和呼和浩特对沙尘天气进行了连续观测。利用激光雷达的数据导出了沙尘和大气污染物气溶胶消光系数的关系,对两个地点的沙尘天气特征和大气污染特征进行了探讨。该期间在呼和浩特观测到较大型的沙尘事件(消光系数大于0.3·km-1)有9次,这些起源于蒙古国/内蒙古的沙尘事件晚于呼和浩特6~10 h在北京被观测到。在呼和浩特观测到的沙尘云块的高度普遍较低(由地表至高空1~2 km),而在北京较高一般可达到2~4 km,同一沙尘事件的最高浓度(消光系数)是呼和浩特高于北京。在北京观测到的沙尘天气共有17次,其中包括数次小规模的沙尘事件在呼和浩特未观测到。从北京及呼和浩特的观测结果可以看出,北京地区3~5月沙尘的背景浓度高于呼和浩特,北京地区具有明显的区域规模大气污染特征,而呼和浩特只具有局部规模的大气污染特征。 相似文献
105.
The last great earthquake in northern Chile took place in 1877, and the ensuing tsunami affected not only that region but also Central Chile. For example, the Bay of Concepción, which is located 1,500 km south of the tsunami source, experienced an inundation height of around 3 m. Ports are important in the Chilean economy, due to the fact that a large percentage of Chilean exports (excluding copper) use ports located in Central Chile. With this in mind, the authors investigated the potential effect of an 1877-like tsunami on the main ports of Central Chile. To do this, the dispersive wave model Non-hydrostatic Evolution of Ocean WAVEs was used. In addition, the first tsunami forecast model for Talcahuano, inside the Bay of Concepción, was developed by means of numerical simulation of several events of different moment magnitudes. The results showed that most of the important ports (Valparaiso, San Antonio, San Vicente and Coronel) had inundation heights on the order of just 1 m, while inundation levels in Talcahuano reached up to 3.5 m. The forecast model for Talcahuano uses only earthquake magnitude, focal depth and tide level to determine tsunami inundation heights. In addition, the tsunami arrival time was computed to be 3 h, and the maximum tsunami amplitude takes place at 4 h and 45 min after the earthquake. 相似文献
106.
Eri Hirakawa Akiko Murakami-Kitase Takamoto Okudaira Jun Inoue Hideo Yamazaki Shusaku Yoshikawa 《Environmental Earth Sciences》2011,64(3):833-840
Spheroidal carbonaceous particles (SCPs) are produced by the high-temperature combustion of fossil fuels and emitted in to
the atmosphere. The distribution and concentration of SCPs in sediments have been used as a proxy for the distribution of
pollutants emitted to the atmosphere. However, the effect on the distribution of SCPs due to industrial activity at nearby
industrial cities is yet to be quantified. To clarify the origin of SCPs of ~20 μm in size that are preserved in sediments,
we evaluated the abundance, surface morphology, and chemical composition of SCPs in sediment core samples recovered from industrial
cities in Japan (Tokyo, Osaka, and Nagasaki) and China (Beijing), with the cities being located at least ~500 km away from
each other. Vertical profiles of SCP concentration in sediment cores from the Japanese cities and Beijing are different, reflecting
the contrasting industrial histories of the two countries. The SCPs from different cities show contrasting morphological and
chemical characteristics, suggesting that ~20 μm SCPs in sediments from the industrial cities could represent the local combustion
history in detail, as the influx of local SCPs is dominant at such sites. 相似文献
107.
Akiko Sugimoto Yukio Nobe Takafumi Yamazaki Yasuhide Yamaguchi Kiyoshi Yamagishi Yusaburo Segawa Humihiko Takei 《Physics and Chemistry of Minerals》1997,24(5):333-339
Cr-droped and Cr,Li-doped forsterite crystals were grown and their optical properties were investigated. It was shown that when only Cr is doped, Cr3+ is substituted at the site of low crystal field, and the energy level 2E lie above the 4T2 level, while 4T2 is just above 2E when Cr and Li are codoped. The difference was rationalized by a deformation of the Cr substituted site with the introduction of Li. 相似文献
108.
Hirokazu Maekawa Kazuyoshi Ohtsuka Koshi Yamamoto Nobuo Gouchi Keiko Hattori 《Island Arc》2021,30(1):e12384
Numerous green polished stone axes have been excavated from the Sannai-Maruyama site, one of Japan's largest archeological sites in the Jomon period (5.9–4.2 cal kyr BP). The axes are composed of weakly metamorphosed fine-grained volcaniclastic rock having a peculiar texture that includes numerous acicular actinolites growing in random directions within a quartz and albite matrix. Cobbles of Aotora stone found along the Nukabira River, Biratori town, southern Hokkaido, are the most likely raw material for these stone axes. Aotora stones have alternate bands of a soft dark-green picritic layer and a hard SiO2-rich pale-green layer. The pale-green layer has a texture similar to the stone axes. Basaltic and picritic volcanic rocks of the Sorachi-Yezo Belt occupy the area along the Shidoni River, a tributary of the Nukabira River. Volcaniclastic rocks similar in texture, mineralogy, and bulk rock compositions to the Aotora stone are exposed in the area. These rocks underwent metamorphism under the actinolite-pumpellyite facies conditions. Their protolith is submarine hyaloclastic rocks that are intercalated with laminated picrite detritus. The stone axes, pale-green layers of Aotora stone, and those of the volcaniclastic rocks of the Shidoni River area all have high SiO2 (~ 55 wt%), Cr (~ 840 μg/g), and Ni (~ 370 μg/g). The rare earth element patterns with abundant light rare earth elements and depleted heavy rare earth elements of stone axes were also consistent with the pale-green layers of the outcrop. These pale-green layers, interleaved with dark-green layers of picritic detritus, were the likely source rock of the stone axes. The high SiO2 content in the pale-green layer caused the crystallization of quartz and albite in the matrix, which resulted in high-quality raw material for making stone axes. 相似文献
109.
The construction of 3-D basin velocity structures is ongoing in many regions of Japan. The structure models are constructed
mainly for the prediction of long-period ground motions from future large earthquakes. In this paper, we validate the 3-D
velocity structure model of the Tokachi basin, a deep sedimentary basin located in eastern Hokkaido, Japan, based on 3-D simulation
of long-period (2–20 s) ground motions from three nearby intermediate-depth earthquakes; this model was constructed by the
National Research Institute for Earth Science and Disaster Prevention (NIED). We make comparisons between the observed and
synthetic long-period ground motions for the basin-induced surface waves as well as the direct S-wave. We also try to revise
the 3-D velocity structure in the western part of the Tokachi basin based on 1-D velocity structures estimated using long-period
S-wave modeling and the microtremor survey method. We then perform the 3-D simulation again to validate the revised model.
Based on quantitative comparisons of the long-period ground motions from these simulations with those observed, we conclude
that the NIED and revised velocity structure models are generally good at the central basin sites, but that both models require
modification at the basin edges to explain the details of the observed basin-induced surface waves. 相似文献
110.
Shuangmeng Zhai Weihong Xue Daisuke Yamazaki Shuangming Shan Eiji Ito Naotaka Tomioka Akira Shimojuku Ken-ichi Funakoshi 《Physics and Chemistry of Minerals》2011,38(5):357-361
High pressure in situ synchrotron X-ray diffraction experiment of strontium orthophosphate Sr3(PO4)2 has been carried out to 20.0 GPa at room temperature using multianvil apparatus. Fitting a third-order Birch–Murnaghan equation of state to the P–V data yields a volume of V 0 = 498.0 ± 0.1 Å3, an isothermal bulk modulus of K T = 89.5 ± 1.7 GPa, and first pressure derivative of K T ′ = 6.57 ± 0.34. If K T ′ is fixed at 4, K T is obtained as 104.4 ± 1.2 GPa. Analysis of axial compressible modulus shows that the a-axis (K a = 79.6 ± 3.2 GPa) is more compressible than the c-axis (K c = 116.4 ± 4.3 GPa). Based on the high pressure Raman spectroscopic results, the mode Grüneisen parameters are determined and the average mode Grüneisen parameter of PO4 vibrations of Sr3(PO4)2 is calculated to be 0.30(2). 相似文献