In situ strength measurements on natural upper-mantle minerals   总被引：1，自引：0，他引：1  

Junji Yamamoto  Jun-ichi Ando  Hiroyuki Kagi  Toru Inoue  Akihiro Yamada  Daisuke Yamazaki  Tetsuo Irifune 《Physics and Chemistry of Minerals》2008,35(5):249-257

Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700°C, we examined rheological properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential stress of 4–6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600°C. Neither orthopyroxene nor spinel shows complete stress relaxation, but both retain some stress even at 700°C. The strength of the minerals decreases in the order of chromian-spinel ≈ orthopyroxene > olivine for these conditions. This order of strength is consistent with the residual pressure of fluid inclusions in mantle xenoliths.  相似文献   

Evapotranspiration from citrus trees growing in sandy soilunder drip irrigation with saline water     

杨胜利  Tomohisa Yano 《中国科学D辑(英文版)》2002,45(Z1)

An experiment on evapotranspiration from citrus trees under irrigation with saline waterwas carried out for 4 months. Two lysimeters planted with a citrus tree in the green house wereused. One lysimeter was irrigated with saline water (NaCl and CaCl2 of 2000 mg/L equivalence,EC = 3.8 dS/m, SAR = 5.9) and the other was irrigated with freshwater using drip irrigation. Theapplied irrigation water was 1.2 times that of the evapotranspiration on the previous day.Evapotranspiration was calculated as the change in lysimeter weight recorded every 30 minutes.The lysimeters were filled with soil with 95.8% sand. The results of the experiment were as follows.(i) The evapotranspiration from citrus tree was reduced after irrigation with saline water. Theevapotranspiration returns to normal after leaching. However it takes months to exhaust the saltfrom the tree. ( ii ) To estimate the impact of irrigation with saline water on the evapotranspirationfrom citrus trees, the reduction coefficient due to salt stress (Ks) was used in this experiment.Evapotranspiration under irrigation with saline water (ETs) can be calculated from evapotranspira-tion under irrigation with freshwater (ET) by the equation ETs = Ks× ET. Ks can be expressed as afunction of ECsw. (iii) The critical soil-water electrical conductivity (ECsw) is 9.5 dS/m, beyondwhich adverse effects on evapotranspiration begin to appear. If ECsw can be controlled at below9.5 dS/m, saline water can be safely used for irrigation.  相似文献   

Interpretation of charging on fracture or frictional slip surface of rocks     

Akihiro Takeuchi  Hiroyuki Nagahama 《Physics of the Earth and Planetary Interiors》2002,130(3-4):285-291

Fracturing and frictional sliding of quartz and granite under dry condition generates fractoluminescence, charged particle emission and electromagnetic radiation. Various kinds of experiments indicate that surface charge density on fracture or frictional slip surface of quartz and granite is 10⁻⁴ to 10⁻² C/m² which is larger than bound charges induced by the disappearance of piezoelectricity due to the release of stress. Hole and electron trapping centers, which is found in semiconductor devices with the Si–SiO₂ system, are causes of surface charging on fracture or frictional slip surface of quartz crystal. The quantity of the surface charge is enough to cause corona discharge that can generate earthquake lights. The mechanism considering the hole and electron trapping centers has a probability to explain why non-piezoelectric minerals or rocks generate electromagnetic phenomena. It can be one of origins of seismo-electromagnetic phenomena (SEP).  相似文献   

Temperature and pH Dependence of Some Metals Leaching from Fly Ash of Municipal Solid Waste     

Lallan Prasad Gupta    Hodaka Kawahata    Mio Takeuchi  Hidekazu Ohta  Yoshiro Ono 《Resource Geology》2005,55(4):357-372

Abstract. Municipal solid waste combustion leads to concentration of various metals in the solid residue (fly ash) remaining after combustion. These metals pose serious environmental hazard and require proper handling and monitoring in order to control their harmful effects. Leachability of some metals from fly ash was examined in fly ash and Milli-Q water mixture (liquid-to-solid ratio, 100) under various temperature and pH conditions in the laboratory. The leaching experiments conducted for 24 hours showed that pH was generally more important than temperature in controlling the amount of metals leached out of the fly ash. However, at a given pH, rise in temperature led to different degree of (usually one to two fold) enhanced or reduced leaching of metals. Owing to amphoteric nature of oxides of Al, Cr, Pb and Zn, these metals often yielded typical pattern of increase and decrease in their concentrations with change in pH. The extent of leaching of Cr and Pb in our experiments suggests that decrease of pH to acidic range in the case of Pb and to neutral to acidic range for Cr over a long period of storage of fly ash at solid waste dumping site may facilitate leaching of these metals from fly ash, leading to contamination of groundwater to the level that exceeds beyond the level permitted by the environmental laws.  相似文献   

Chemistry of Supraglacial Ponds in the Debris-Covered Area of Lirung Glacier in Central Nepal Himalayas     

Maya P. Bhatt  Nozomu Takeuchi  Miguel F. Acevedo 《Aquatic Geochemistry》2016,22(1):35-64

  相似文献   

Authigenic rhodochrosite from a gas hydrate-bearing structure in Lake Baikal     

Krylov  Alexey A.  Hachikubo  Akihiro  Minami  Hirotsugu  Pogodaeva  Tatyana V.  Zemskaya  Tamara I.  Krzhizhanovskaya  Mariya G.  Poort  Jeffrey  Khlystov  Oleg M. 《International Journal of Earth Sciences》2018,107(6):2011-2022

International Journal of Earth Sciences - Early diagenetic carbonates are rare in Lake Baikal. Siderite (Fe carbonate) concretions in the sediments were discovered only recently. Here, we discuss...  相似文献   

Tide-related Changes in mRNA Abundance of Aromatases and Estrogen Receptors in the Ovary and Brain of the Threespot Wrasse <Emphasis Type="Italic">Halichoeres trimaculatus</Emphasis>     

Dae-Ju Oh  Sung-Pyo Hur  Selma Bouchekioua  Yuki Takeuchi  Shingo Udagawa  Neelakanteswar Aluru  Yong-Ju Park  Ji-Gweon Park  Se-Jae Kim  Thomas W. Moon  Mathilakath M. Vijayan  Akihiro Takemura 《Ocean Science Journal》2018,53(2):239-249

  相似文献   

Molecular and isotopic characteristics of gas hydrate-bound hydrocarbons in southern and central Lake Baikal   总被引：4，自引：4，他引：0  

Akihiro Hachikubo  Oleg Khlystov  Alexey Krylov  Hirotoshi Sakagami  Hirotsugu Minami  Yutaka Nunokawa  Satoshi Yamashita  Nobuo Takahashi  Hitoshi Shoji  Shin’ya Nishio  Masato Kida  Takao Ebinuma  Gennadiy Kalmychkov  Jeffrey Poort 《Geo-Marine Letters》2010,30(3-4):321-329

We investigated the molecular composition (methane, ethane, and propane) and stable isotope composition (methane and ethane) of hydrate-bound gas in sediments of Lake Baikal. Hydrate-bearing sediment cores were retrieved from eight gas seep sites, located in the southern and central Baikal basins. Empirical classification of the methane stable isotopes (δ¹³C and δD) for all the seep sites indicated the dominant microbial origin of methane via methyl-type fermentation; however, a mixture of thermogenic and microbial gases resulted in relatively high methane δ¹³C signatures at two sites where ethane δ¹³C indicated a typical thermogenic origin. At one of the sites in the southern Baikal basin, we found gas hydrates of enclathrated microbial ethane in which ¹³C and deuterium were both highly depleted (mean δ¹³C and δD of –61.6‰ V-PDB and –285.4‰ V-SMOW, respectively). To the best of our knowledge, this is the first report of C₂ δ¹³C–δD classification for hydrate-bound gas in either freshwater or marine environments.  相似文献   

Molecular ecological study of <Emphasis Type="Italic">Siganus spinus</Emphasis> and <Emphasis Type="Italic">S. guttatus</Emphasis> from Okinawan waters based on mitochondrial DNA control region sequences     

Kensuke Iwamoto  Akihiro Takemura  Tetsuo Yoshino  Hideyuki Imai 《Journal of Oceanography》2009,65(1):103-112

The mitochondrial DNA (mtDNA) control region was sequenced to examine the genetic variability and gene flow of juvenile Siganus spinus and S. guttatus. In total, 461 nucleotide sequences were obtained from 69 specimens of juvenile S. spinus from Okinawa Island and Ishigaki Island, in which 17 variable sites and 22 haplotypes were identified. Haplotype diversity (h) was high (0.9244 in Okinawa and 0.8984 in Ishigaki), whereas nucleotide diversity (π) was low (0.0063 in Okinawa and 0.0059 in Ishigaki). The two populations were not genetically distinct. Siganus guttatus, which do not form large schools at recruitment, in contrast S. spinus, were also analyzed by studying 152 individuals collected off Okinawa Island, Miyako Island, and Ishigaki Island. Of 476 nucleotide sequences, 50 were variable, and 42 haplotypes were identified. Genetic variability values were high (h = 0.8766 and π = 0.0151 in Okinawa; h = 0.9640 and π = 0.0192 in Miyako; h = 0.9161 and π = 0.0199 in Ishigaki). The Okinawa population was genetically isolated from the Miyako and Ishigaki populations. As a result, genetic diversity was high for each of these siganid populations despite their being target species for fisheries; however, the degree of inter-population gene flow was higher for S. spinus than S. guttatus, suggesting that these species exhibit different dispersal strategies.  相似文献   

新生代深海冷水碳酸盐泥丘成因及IODP 307航次初步研究结果   总被引：1，自引：1，他引：0  

李祥辉  陈云华  徐宝亮  Akihiro Kano 《地球科学进展》2007,22(7):666-672

记述了新生代深海冷水碳酸盐泥丘近期的9个重要研究事件;总结了冷水泥丘具有全球海洋(大陆斜坡为主)分布、形态各异、冷水枝状珊瑚构筑泥丘的特点;介绍了冷水泥丘形成的(地质流体渗流和微生物作用)内因及(海底牵引底流作用)外因两种主要观点.对2005年IODP 307航次实施的北大西洋Porcupine Seabight冷水泥丘大洋钻探工作初步成果进行了编译,公布了中国科学家在碳氧同位素方面的初步实验结果.实验结果显示上新世中期以来的2 Ma里冷水碳酸盐泥丘启动和发育过程中存在2次碳氧同位素偏移事件(Ⅰ和Ⅱ),碳氧同位素偏移事件Ⅰ与泥丘的启动相呼应,暗示北大西洋古海洋气候发生巨大变化,可能与北极冰盖极盛有关.  相似文献