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221.
Tetsuji Suzuki Takeshi Ohta Tetsuya Hiyama Yasuhiro Izumi Osmund Mwandemele Morio Iijima 《水文研究》2014,28(17):4780-4794
Land use changes in wetland areas can alter evapotranspiration, a major component of the water balance, which eventually affects the water cycle and ecosystem. This study assessed the effect of introduced rice‐cropping on evapotranspiration in seasonal wetlands of northern Namibia. By using the Bowen ratio–energy balance method, measurements of evapotranspiration were performed over a period of 2.5 years at two wetland sites—a rice field (RF) and a natural vegetation field (NVF)—and at one upland field (UF) devoid of surface water. The mean evapotranspiration rates of RF (1.9 mm daytime?1) and NVF (1.8 mm daytime?1) were greater than that in UF (1.0 mm daytime?1). RF and NVF showed a slight difference in seasonal variations in evapotranspiration rates. During the dry season, RF evapotranspiration was less than the NVF evapotranspiration. The net radiation in RF was less in this period because of the higher albedo of the non‐vegetated surface after rice harvesting. In the early growth period of rice during the wet season, evapotranspiration in RF was higher than that in NVF, which was attributed to a difference in the evaporation efficiency and the transfer coefficient for latent heat that were both affected by leaf area index (LAI). Evapotranspiration sharply negatively responded to an increase in LAI when surface water is present according to sensitivity analysis, probably because a higher LAI over a surface suppresses evaporation. The control of LAI is therefore a key for reducing evaporation and conserving water. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
222.
Graciano P.Yumul Jr. Carla B.Dimalanta Ricky C.Salapare Karlo L.Queano Decibel V.Faustino-Eslava Edanjarlo J.Marquez Noelynna T.Ramos Betchaida D.Payot Juan Miguel R.Guotana Jillian Aira S.Gabo-Ratio Leo T.Armada Jenielyn T.Padrones Keisuke Ishida Shigeyuki Suzuki 《地学前缘(英文版)》2020,11(1):23-36
New radiolarian ages show that the island arc-related Acoje block of the Zambales Ophiolite Complex is possibly of Late Jurassic to Early Cretaceous age.Radiometric dating of its plutonic and volcanichypabyssal rocks yielded middle Eocene ages.On the other hand,the paleontological dating of the sedimentary carapace of the transitional mid-ocean ridge-island arc affiliated Coto block of the ophiolite complex,together with isotopic age datings of its dikes and mafic cumulate rocks,also yielded Eocene ages.This offers the possibility that the Zambales Ophiolite Complex could have:(1)evolved from a Mesozoic arc(Acoje block)that split to form a Cenozoic back-arc basin(Coto block),(2)through faulting,structurally juxtaposed a Mesozoic oceanic crust with a younger Cenozoic lithospheric fragment or(3)through the interplay of slab rollback,slab break-off and,at a later time,collision with a microcontinent fragment,caused the formation of an island arc-related ophiolite block(Acoje)that migrated trench-ward resulting into the generation of a back-arc basin(Coto block)with a limited subduction signature.This Meso-Cenozoic ophiolite complex is compared with the other oceanic lithosphere fragments along the western seaboard of the Philippines in the context of their evolution in terms of their recognized environments of generation. 相似文献
223.
224.
Effects of acidified seawater on calcification,photosynthetic efficiencies and the recovery processes from strong light exposure in the coral Stylophora pistillata 下载免费PDF全文
Takashi Nakamura Akira Iguchi Atsushi Suzuki Kazuhiko Sakai Yukihiro Nojiri 《Marine Ecology》2017,38(3)
The aim of this study was to investigate whether coral photosynthetic efficiencies and recovery processes are affected by CO2‐driven ocean acidification in symbiont photosynthesis and coral calcification. We investigated the effects of five CO2 partial pressure (pCO2) levels in adjusted seawater ranging from 300 μatm (pre‐industrial) to 800 μatm (near‐future) and strong and weak light intensity on maximum photosynthetic efficiency and calcification of a branching coral, Stylophora pistillata, as this species has often been used in rearing experiments to investigate the effects of acidified seawater on calcification and photosynthetic algae of corals. We found that, the photosynthetic efficiencies and recovery patterns under different light conditions did not differ among pCO2 treatments. Furthermore, calcification of S. pistillata was not affected by acidified seawater under weak or strong light conditions. Our results indicate that the photosynthetic efficiency and calcification of S. pistillata are insensitive to changes in ocean acidity. 相似文献
225.
Naoya Suzuki Naoto Ebuchi Chaofang Zhao Isao Watabe Yasuhiro Sugimori 《Journal of Earth System Science》2002,111(3):305-313
Relationship between the non-dimensional roughness length and inverse of wave age has been discussed without consideration
of wave directions, though wind wave field consists of various directional component waves. In this study we observe wave
heights by an array of four wave gauges at the Hiratsuka Tower of (Independent Administrative Institution) National Research
Institute for Earth Science and Disaster Prevention (NIED), Japan, and discuss the effect of wave directionality. As a result,
the data sets were classified into two different groups according to the directional wave spectrum distribution. In case 1
only swell and wind waves exist and in case 2 there exist wave components from several directions. It is shown that the case
of multiple-directional component waves (case 2) may affect the non-dimensional roughness length and friction velocity. 相似文献
226.
Yoshiki Shirahama Yukari Miyashita Masao Kametaka Yuji Suzuki Yosuke Miyairi Yusuke Yokoyama 《Island Arc》2021,30(1):e12376
The NE-trending Hinagu fault zone, length 81 km, is one of the major active faults in Kyushu, Japan. From north to south, it is divided into three segments based on geomorphic features and paleoseismic behavior: the Takano-Shirahata, Hinagu, and Yatsushiro Sea segments. The 2016 Kumamoto earthquake produced a 6-km-long surface rupture with a dextral strike-slip displacement on the northern part of the Takano-Shirahata segment. Surface rupture, a faint east-side-up flexure with a vertical offset of less than 8 cm, was observed near the middle of the Takano-Shirahata segment. To examine past surface-rupturing earthquakes on the Takano-Shirahata segment, including rupture frequency and timing, we conducted a paleoseismic study with boring and trenching at Yamaide. A trench across the surface rupture exposed multiple fault strands associated with multiple surface-rupturing events that deformed several strata of fine-grained sediments. By structural and stratigraphic interpretation, high-density radiocarbon dating and tephra analysis, and Bayesian modeling, we constrained the timing of seven events, Events 1–7, to 0.84–1.25, 1.31–7.06, 9.99–11.0, 10.8–12.1, 12.0–13.0, 14.2–15.1, and before 14.8 kcal BP. Slip during Events 1–6 was obviously larger than the 2016 slip. The estimated average recurrence interval was about 2596–2860 years, but the interval between Events 2 and 3 was much longer than other intervals. Moreover, the vertical throw associated with Event 2 was larger than that of other events. This implies that the Takano-Shirahata segment has a period with rare larger earthquakes and a period with frequent smaller earthquakes. Some events might have produced ruptures on both the Takano-Shirahata and the northern part of the Hinagu segments simultaneously or in a short time. The variety of recurrence intervals suggests that the seismic activity has been affected by one or both activities of the Futagawa fault zone and the Hinagu segment. 相似文献
227.
M. Mikami G.Y. Shi I. Uno S. Yabuki Y. Iwasaka M. Yasui T. Aoki T.Y. Tanaka Y. Kurosaki K. Masuda A. Uchiyama A. Matsuki T. Sakai T. Takemi M. Nakawo N. Seino M. Ishizuka S. Satake K. Fujita Y. Hara K. Kai S. Kanayama M. Hayashi M. Du Y. Kanai Y. Yamada X.Y. Zhang Z. Shen H. Zhou O. Abe T. Nagai Y. Tsutsumi M. Chiba J. Suzuki 《Global and Planetary Change》2006,52(1-4):142
The Aeolian Dust Experiment on Climate Impact (ADEC) was initiated in April 2000 as a joint five-year Japan–China project. The goal was to understand the impact of aeolian dust on climate via radiative forcing (RF). Field experiments and numerical simulations were conducted from the source regions in northwestern China to the downwind region in Japan in order to understand wind erosion processes temporal and spatial distribution of dust during their long-range transportation chemical, physical, and optical properties of dust and the direct effect of radiative forcing due to dust. For this, three intensive observation periods (IOP) were conducted from April 2002 to April 2004.The in situ and network observation results are summarized as follows: (1) In situ observations of the wind erosion process revealed that the vertical profile of moving sand has a clear size dependency with height and saltation flux and that threshold wind velocity is dependent on soil moisture. Results also demonstrated that saltation flux is strongly dependent on the parent soil size distribution of the desert surface. (2) Both lidar observations and model simulations revealed a multiple dust layer in East Asia. A numerical simulation of a chemical transport model, CFORS, illustrated the elevated dust layer from the Taklimakan Desert and the lower dust layer from the Gobi Desert. The global-scale dust model, MASINGAR, also simulated the dust layer in the middle to upper free troposphere in East Asia, which originated from North Africa and the Middle East during a dust storm in March 2003. Raman lidar observations at Tsukuba, Japan, found the ice cloud associated with the dust layer at an altitude of 6 to 9 km. Analysis from lidar and the radio-sonde observation suggested that the Asian dust acted as ice nuclei at the ice-saturated region. These results suggest the importance of dust's climate impact via the indirect effect of radiative forcing due to the activation of dust into ice nuclei. (3) Studies on the aerosol concentration indicated that size distributions of aerosols in downwind regions have bimodal peaks. One peak was in the submicron range and the other in the supermicron range. The main soluble components of the supermicron peak were Na+, Ca2+, NO3−, and Cl−. In the downwind region in Japan, the dust, sea salt, and a mixture of the two were found to be dominant in coarse particles in the mixed boundary layer. (4) Observation of the optical properties of dust by sky-radiometer, particle shoot absorption photometer (PSAP), and Nephelometer indicated that unpolluted dust at source region has a weaker absorption than originally believed.A sensitivity experiment of direct RF by dust indicated that single scattering albedo is the most important of the optical properties of dust and that the sensitivity of instantaneous RF in the shortwave region at the top of the atmosphere to the refractive index strongly depends on surface albedo. A global scale dust model, MASINGAR, was used for evaluation of direct RF due to dust. The results indicated the global mean RF at the top and the bottom of the atmosphere were − 0.46 and − 2.13 W m− 2 with cloud and were almost half of the RF with cloud-free condition. 相似文献
228.
Microbial community respiration and structure of dead zone sediments of Omura Bay, Japan 总被引:1,自引:0,他引:1
Minoru Wada Shotaro Suzuki Tadashi Nara Yu Umezawa Motohiro Shimanaga Kazumi Matsuoka Hideaki Nakata 《Journal of Oceanography》2012,68(6):857-867
Monitoring sediment microbial community metabolism and structure is instrumental to understanding biogeochemical processes in and ecological impacts on bottom environments. The aim of this study was to determine potential community respiration and to reveal community dynamics of the microorganisms in the dead zone sediments of Omura Bay, Japan. The bay is highly enclosed and develops severe hypoxia in the central regions every summer. We collected sediment core samples from the center of the bay during hypoxia, estimated sediment oxygen consumption by using an adapted in vivo electron transport system activity (in vivo ETSA) assay, enumerated abundance of bacteria, and analyzed bacterial community structure by automated ribosomal intergenic spacer analysis. Higher ETSA and bacterial diversity were found in upper sediments (within 3?cm depth) from the center than the fringe of the bay. Sediment bacterial community structure of the bay center was distinct from that of the fringe. From these results, upper sediment in the dead zone of Omura Bay was characterized by (1) greater community respiration and (2) greater diversity of bacterial components compared with the non-hypoxic sediment of the bay fringe. These characteristics have important implications for understanding the interaction between microbial communities and the development of hypoxia in Omura Bay. 相似文献
229.
Wave dissipation by vegetation with layer schematization in SWAN 总被引:1,自引:0,他引:1
Tomohiro Suzuki Marcel ZijlemaBastiaan Burger Martijn C. MeijerSiddharth Narayan 《Coastal Engineering》2012,59(1):64-71
The energy of waves propagating through vegetation is dissipated due to the work done by the waves on the vegetation. Dalrymple et al. (1984) estimated wave dissipation by integrating the force on a cylinder over its vertical extent. This was extended by Mendez and Losada (2004) to include varying depths and the effects of wave damping due to vegetation and wave breaking for narrow-banded random waves. This paper describes the wave dissipation over a vegetation field by the implementation of the Mendez and Losada formulation in a full spectrum model SWAN, with an extension to include a vertical layer schematization for the vegetation. The present model is validated with the original equation and results from Mendez and Losada (2004). The sensitivity of the model to the shape of the frequency spectrum, directional spreading and layer schematization are investigated. The model is then applied to field measurements by using a vegetation factor. This model has the ability to calculate two-dimensional wave dissipation over a vegetation field including some important aspects such as breaking and diffraction as used in SWAN model. 相似文献
230.
Kei Nakayama Yoshiyuki Inoue Naomi Ikeda Naoki Hashizume Hidekazu Murakami Takeshi Ishibashi Hirofumi Ikeda Tomohiko Isobe Shin-Ichi Kitamura Go Suzuki 《Marine pollution bulletin》2014
Uptake and biological effects of synthetic glucocorticoids (GCs) were analyzed using common carp (Cyprinus carpio). Fish were exposed to clobetasol propionate (CP) or clobetasone butyrate (CB) individually or in mixture at 1 μg L−1 for 21 days. Bioconcentration factor (BCF) of CB was calculated as 100, and BCF of CP was less than 16. No effects were found in fish erythrocyte and leukocyte numbers and serum glucose levels after exposure to the selected GCs. On the other hand, serum concentrations of free amino acids significantly increased in GC-exposed groups. Thus, exposures to synthetic GCs at relatively low concentrations seemed to cause enhancement of protein degradation and subsequent increase of serum free amino acids without a corresponding increase in serum glucose levels, an effect which might be related to partial induction of gluconeogenesis by GC. 相似文献