Evapotranspiration and water source of a tropical rainforest in peninsular Malaysia          下载免费PDF全文

Marryanna Lion  Yoshiko Kosugi  Satoru Takanashi  Shoji Noguchi  Masayuki Itoh  Masanori Katsuyama  Naoko Matsuo  Siti‐Aisah Shamsuddin 《水文研究》2017,31(24):4338-4353

To evaluate water use and the supporting water source of a tropical rainforest, a 4‐year assessment of evapotranspiration (ET) was conducted in Pasoh Forest Reserve, a lowland dipterocarp forest in Peninsular Malaysia. The eddy covariance method and isotope signals of rain, plant, soil, and stream waters were used to determine forest water sources under different moisture conditions. Four sampling events were conducted to collect soil and plant twig samples in wet, moderate, dry, and very dry conditions for the identification of isotopic signals. Annual ET from 2012 to 2015 was quite stable with an average of 1,182 ± 26 mm, and a substantial daily ET was observed even during drought periods, although some decline was observed, corresponding with volumetric soil water content. During the wet period, water for ET was supplied from the surface soil layer between 0 and 0.5 m, whereas in the dry period, approximately 50% to 90% was supplied from the deeper soil layer below 0.5‐m depth, originating from water precipitated several months previously at this forest. Isotope signatures demonstrated that the water sources of the plants, soil, and stream were all different. Water in plants was often different from soil water, probably because plant water came from a different source than water that was strongly bound to the soil particles. Plants showed no preference for soil depth with their size, whereas the existence of storage water in the xylem was suggested. The evapotranspiration at this forest is balanced and maintained using most of the available water sources except for a proportion of rapid response run‐off.  相似文献   

Brief sea‐level fall event and centennial to millennial sea‐level variations during Marine Isotope Stage 19 in Osaka Bay,Japan          下载免费PDF全文

Kenta Maegakiuchi  Masayuki Hyodo  Ikuko Kitaba  Kotaro Hirose  Shigehiro Katoh  Hiroshi Sato 《第四纪科学杂志》2016,31(7):809-822

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Noble gases in oxidized residue prepared from the Saratov L4 chondrite and Raman spectroscopic study of residues to characterize phase Q          下载免费PDF全文

Jun‐ichi Matsuda  Kazuhiko Morishita  Masayuki Nara  Sachiko Amari 《Meteoritics & planetary science》2016,51(1):70-79

We analyzed noble gases in an oxidized residue prepared from a HF‐HCl residue of the Saratov L4 chondrite. The Ar, Kr, and Xe concentrations in the oxidized residue are two orders of magnitude lower than those in the HF‐HCl residue, and they are close to concentrations in the bulk. The He and Ne concentrations are similar in the three samples. The Ne isotopic ratios are almost purely cosmogenic, indicating absence of presolar diamonds (the carrier of the HL component). Thus, Saratov contains phase Q without presolar diamond. A study of the Raman spectroscopic parameters for the HF‐HCl residue and the oxidized residue shows large changes due to oxidation. The directions of these changes are the same as observed in Allende, except oxidation increased the I_D/I_G (intensity ratio of the D band to the G band) in Saratov but decreased in Allende. This difference may be attributed to the different crystalline stages of carbon in both meteorites. The shifts in the Raman parameters to a discrete and/or more expanded region suggest that (1) oxidation changes the crystalline condition of graphitic carbon, (2) phase Q is not a dissolved site, and (3) the release of Q‐gas is simply related to the rearrangement of the carbon structure during oxidation.  相似文献   

Development of a numerical model for nitrates in groundwater in the reservoir area of the Komesu subsurface dam, Okinawa, Japan   总被引：1，自引：0，他引：1  

Shuhei Yoshimoto  Takeo Tsuchihara  Satoshi Ishida  Masayuki Imaizumi 《Environmental Earth Sciences》2013,70(5):2061-2077

A numerical model consisting of simplified equations was developed to simulate nitrate concentrations in groundwater in a reservoir area of a subsurface dam in a Quaternary limestone region. The model was composed of a water balance sub-model and a nitrogen balance sub-model; the water balance sub-model was built from tank models which can express the quick dilution near caves and the effect of dam construction; and the nitrogen balance sub-model was made to represent changes in nitrogen forms and movement of nitrogen in the soil and aquifer zones. The model was calibrated and verified by observed data before and after the dam construction and then applied to a predictive simulation under a simple assumption that rainfall descends gradually. The model seemed applicable to long-term prediction of changes in NO₃-N in the reservoir area.  相似文献   

Finite Difference Simulations of Seismic Wave Propagation for the 2007 Mw 6.6 Niigata-ken Chuetsu-Oki Earthquake: Validity of Models and Reliable Input Ground Motion in the Near-Field     

Hideo Aochi  Ariane Ducellier  Fabrice Dupros  Mickael Delatre  Thomas Ulrich  Florent de Martin  Masayuki Yoshimi 《Pure and Applied Geophysics》2013,170(1-2):43-64

Finite difference simulations of seismic wave propagation are performed in the Niigata area, Japan, for the 2007 Mw 6.6 Niigata-ken Chuetsu-Oki earthquake at low frequencies. We test three 3D structural models built independently in various studies. First aftershock simulations are carried out. The model based on 3D tomography yields correct body waves in the near field, but later phases are imperfectly reproduced due to the lack of shallow sediment layers; other models based on various 1D/2D profiles and geological interpretation provide good site responses but generate seismic phases that may be shifted from those actually observed. Next, for the mainshock simulations, we adopt two different finite source models that differ in the near-field ground motion, especially above the fault plane (but under the sea) and then along the coastline. Each model is found to be calibrated differently for the given stations. For engineering purposes, the variations observed in simulated ground motion are significant, but for seismological purposes, additional parameter calibrations would be possible for such a complex 3D case.  相似文献   

Intensity variations of the postnoon auroral bright spots observed at Zhongshan Station, Antarctica on August 8, 1999     

艾勇  邓晓华  刘瑞源  杨惠根 《极地研究(英文版)》2002,13(1)

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅａｆｔｅｒｎｏｏｎｒｅｇｉｏｎ (ａｐｐｒｏｘｉｍａｔｅｌｙ 1 4 0 0ｔｏ 1 60 0ＭＬＴ)ｈａｓａｓｐｅｃｉａｌｓｉｇｎｉｆｉｃａｎｃｅｆｏｒａｖａｒｉｅｔｙｏｆｍａｇｎｅｔｏｓｐｈｅｒｉｃｐｈｅｎｏｍｅｎａ.Ｉｔｓｐｒｏｘｉｍｉｔｙｔｏｍａｇｎｅｔｉｃｎｏｏｎｓｕｇｇｅｓｔｓｔｈａｔｔｈｅａｕｒｏｒａｌｐｈｅｎｏｍｅｎａｏｂｓｅｒｖｅｄｍａｙｂｅｒｅｌａｔｅｄｔｏｄａｙｓｉｄｅｍａｇｎｅｔｏｓｐｈｅｒｉｃｐｒｏｃｅｓｓｅｓ ,ａｎｄｉｎｄｅｅｄａｖａｒｉｅｔｙｏｆｓｔｕ…  相似文献   

Gas stripping by radiation drag from an interstellar cloud     

Jun'ichi Sato  Masayuki Umemura  Keisuke Sawada  Shingo Matsuyama 《Monthly notices of the Royal Astronomical Society》2004,354(1):176-182

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A huge filamentary structure at z= 0.55 and star formation histories of galaxies at z < 1     

Masayuki Tanaka  Takako Hoshi  Tadayuki Kodama  Nobunari Kashikawa 《Monthly notices of the Royal Astronomical Society》2007,379(4):1546-1556

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Galactic winds from primeval galaxies     

Masao Mori  Masayuki Umemura 《Astrophysics and Space Science》2007,311(1-3):111-115

Ultra-high resolution hydrodynamic simulations using 1024³ grid points are performed of early supernova burst in a forming galaxy, with properties similar to those inferred for Lyman α emitters (LAEs) and Lyman Break Galaxies (LBGs). We show that, at the earliest stages of less than 300 Myr, continual supernova explosions produce multitudinous hot bubbles and cooled H(I) shells in-between. The H(I) shells radiate intense Lyman α (Lyα) emission like LAEs. We found that the bubbly structures produced are quite similar to the observed features in the Lyα surface brightness distribution of the extended LAEs. After 1 Gyr, the galaxies are dominated by stellar continuum radiation and then resemble the LBGs. At this point, the abundance of heavy elements appears to be solar. After 13 Gyr, these galaxies resemble present-day ellipticals.  相似文献   

Enhanced Dissolved Organic Matter Recovery from Saltwater Samples with Electrodialysis     

Luke R. Chambers  Ellery D. Ingall  Emily M. Saad  Amelia F. Longo  Masayuki Takeuchi  Yuanzhi Tang  Claudia Benitez-Nelson  Sheean T. Haley  Sonya T. Dyhrman  Jay Brandes  Aron Stubbins 《Aquatic Geochemistry》2016,22(5-6):555-572

Complexities associated with dissolved organic matter (DOM) isolation from seawater have hampered compositional characterization of this key component of global carbon and nutrient cycles. DOM isolation efficiency by electrodialysis (ED) from salt-containing waters was optimized and evaluated on samples including coastal ocean seawater, open ocean seawater, artificial seawater from axenic cultures of marine phytoplankton, and artificial seawater samples containing standard compounds of different molecular sizes and charge. ED was performed with a system optimized for processing 2–10 L sample volumes. Additionally, the combination of ED and solid-phase extraction, using Bond Elut PPL exchange resin, was evaluated. Using only ED, the following DOC recoveries were achieved: coastal seawater, 71.3 ± 6.5 %; open ocean, 50.5 ± 3.1 %; phytoplankton cultures, 70.3 ± 12.5 %; glucose, 90.2 ± 2.1 %; EDTA, 67.5 ± 9.9 %; and vitamin B₁₂, 98.3 ± 1.6 %. With the combination of PPL and ED techniques, an average DOC recovery of 76.7 ± 2.6 % was obtained for coastal seawater, but this recovery was not statistically different from seawater recoveries using only ED. Comparison of C/N ratios and fluorescence excitation emission matrices taken at the beginning and end of the recovery process for coastal samples processed using only ED indicated that the final recovered material was representative of the DOM present in the original samples. Typical recoveries using combined PPL and ED exceed those of previous isolation methods.  相似文献