Phytoremediation of heavy metal‐contaminated water and sediment by Eleocharis acicularis     

Masayuki Sakakibara  Yuko Ohmori  Nguyen Thi Hoang Ha  Sakae Sano  Koichiro Sera 《洁净——土壤、空气、水》2011,39(8):735-741

Phytoremediation is an environmental remediation technique that takes advantage of plant physiology and metabolism. The unique property of heavy metal hyperaccumulation by the macrophyte Eleocharis acicularis is of great significance in the phytoremediation of water and sediments contaminated by heavy metals at mine sites. In this study, a field cultivation experiment was performed to examine the applicability of E. acicularis to the remediation of water contaminated by heavy metals. The highest concentrations of heavy metals in the shoots of E. acicularis were 20 200 mg Cu/kg, 14 200 mg Zn/kg, 1740 mg As/kg, 894 mg Pb/kg, and 239 mg Cd/kg. The concentrations of Cu, Zn, As, Cd, and Pb in the shoots correlate with their concentrations in the soil in a log‐linear fashion. The bioconcentration factor for these elements decreases log‐linearly with increasing concentration in the soil. The results indicate the ability of E. acicularis to hyperaccumulate Cu, Zn, As, and Cd under natural conditions, making it a good candidate species for the phytoremediation of water contaminated by heavy metals.  相似文献   

Broadband Ground Motion Reconstruction for the Kanto Basin during the 1923 Kanto Earthquake     

Haruko Sekiguchi  Masayuki Yoshimi 《Pure and Applied Geophysics》2011,168(3-4):609-630

Ground motions of the 1923 Kanto Earthquake inside the Kanto Basin are numerically simulated in a wide frequency range (0?C10?Hz) based on new knowledge of the earthquake??s source processes, the sedimentary structure of the basin, and techniques for generating broadband source models of great earthquakes. The Kanto Earthquake remains one of the most important exemplars for ground motion prediction in Japan due to its size, faulting geometry, and location beneath the densely populated Kanto sedimentary basin. We reconstruct a broadband source model of the 1923 Kanto Earthquake from inversion results by introducing small-scale heterogeneities. The corresponding ground motions are simulated using a hybrid technique comprising the following four calculations: (1) low-frequency ground motion of the engineering basement, modeled using a finite difference method; (2) high-frequency ground motion of the engineering basement, modeled using a stochastic Green??s function method; (3) total ground motion of the engineering basement (i.e. 1?+?2); and (4) ground motion at the surface in response to the total basement ground motion. We employ a recently developed three-dimensional (3D) velocity structure model of the Kanto Basin that incorporates prospecting data, microtremor observations and measurements derived from strong ground motion records. Our calculations reveal peak ground velocities (PGV) exceeding 50?cm/s in the area above the fault plane: to the south, where the fault plane is shallowest, PGV reaches 150?C200?cm/s at the engineering basement and 200?C250?cm/s at the surface. Intensity 7, the maximum value in the Japan Meteorological Agency??s intensity scale, is calculated to have occurred widely in Sagami Bay, which corresponds well with observed house-collapse rates due to the 1923 event. The modeling reveals a pronounced forward directivity effect for the area lying above the southern, shallow part of the fault plane. The high PGV and intensity seen above the southeastern corner of the fault plane and further east are largely due to this effect. Waveforms above the fault plane contain both short- and long-period components, but the short-period components are not observed further afield. Away from the fault, long-period waves (>2?s) dominate the ground motion, and in areas where the base of the third layer is relatively deep, the predominant period is >5?s. Levels of long-period ground motion in the southern part of the study area, around Sagami Bay and the southern parts of Boso Peninsula and Tokyo Bay, exceed that recorded at Tomakomai during the 2003 Tokachi-oki earthquake, when large oil storage tanks collapsed in response to sloshing generated by strong long-period motions.  相似文献   

Holocene East Asian monsoon variation inferred from species assemblage and shell chemistry of the ostracodes from Hulun Lake, Inner Mongolia   总被引：3，自引：0，他引：3  

Dayou Zhai  Jule Xiao  Lang Zhou  Ruilin Wen  Zhigang Chang  Xu Wang  Xindi Jin  Qiqing Pang  Shigeru Itoh 《Quaternary Research》2011,75(3):512-522

A sediment core from Hulun Lake, Inner Mongolia was analyzed for species assemblages and shell chemistry of ostracodes to investigate changes in the hydrology and climate of the East Asian summer monsoon margin during the Holocene. Darwinula stevensoni was abundant, Ilyocypris spp. scarce, littoral ostracodes absent and Mg/Ca, Sr/Ca and δ¹⁸O were low 11,100 to 8300 yr ago, indicating high lake levels and cool/fresh waters. Darwinula stevensoni declined largely, Ilyocypris spp. throve, littoral ostracodes were rare and chemical indicators remained in low values 8300 to 6200 yr ago, suggesting that the lake continued high stands but water became warm. The lake then contracted and water became cool/brackish 6200 to 4300 yr ago. Littoral ostracodes flourished 4300 to 3350 yr ago, marking the lowest lake levels of the entire Holocene. The lake level recovered and water salinity decreased 3350 to 1900 yr ago. From 1900 to 500 yr ago, the lake maintained the preceding status albeit lowered stands and increased salinities 1100 to 800 yr ago. During the recent 500 yr, the lake expanded and water salinity decreased. The data imply that the East Asian summer monsoon did not intensify until 8300 yr ago and weakened dramatically 4300 to 3350 yr ago.  相似文献   

Hayabusa‐returned sample curation in the Planetary Material Sample Curation Facility of JAXA     

Toru YADA  Akio FUJIMURA  Masanao ABE  Tomoki NAKAMURA  Takaaki NOGUCHI  Ryuji OKAZAKI  Keisuke NAGAO  Yukihiro ISHIBASHI  Kei SHIRAI  Michael E. ZOLENSKY  Scott SANDFORD  Tatsuaki OKADA  Masayuki UESUGI  Yuzuru KAROUJI  Maho OGAWA  Shogo YAKAME  Munetaka UENO  Toshifumi MUKAI  Makoto YOSHIKAWA  Junichiro KAWAGUCHI 《Meteoritics & planetary science》2014,49(2):135-153

Abstract– The Planetary Material Sample Curation Facility of JAXA (PMSCF/JAXA) was established in Sagamihara, Kanagawa, Japan, to curate planetary material samples returned from space in conditions of minimum terrestrial contaminants. The performances for the curation of Hayabusa‐returned samples had been checked with a series of comprehensive tests and rehearsals. After the Hayabusa spacecraft had accomplished a round‐trip flight to asteroid 25143 Itokawa and returned its reentry capsule to the Earth in June 2010, the reentry capsule was brought back to the PMSCF/JAXA and was put to a series of processes to extract recovered samples from Itokawa. The particles recovered from the sample catcher were analyzed by electron microscope, given their ID, grouped into four categories, and preserved in dimples on quartz slide glasses. Some fraction of them has been distributed for initial analyses at NASA, and will be distributed for international announcement of opportunity (AO), but a certain fraction of them will be preserved in vacuum for future analyses.  相似文献   

Investigation of cutting methods for small samples of Hayabusa and future sample return missions     

Masayuki Uesugi  Ryo Noguchi  Tooru Matsumoto  Junya Matsuno  Takashi Nagano  Akira Tsuchiyama  Shigenori Harada  Kaori Yokoyama  Yoshiaki Yodo  Noboru Takeda  Toru Yada  Shogo Yakame  Yuzuru Karouji  Yukihiro Ishibashi  Masanao Abe  Tatsuaki Okada  Akio Fujimura  Mitsuru Ebihara  Fumio Kitajima  Keisuke Nagao  Tomoki Nakamura  Hiroshi Naraoka  Takaaki Noguchi  Ryuji Okazaki  Hisayoshi Yurimoto 《Meteoritics & planetary science》2014,49(7):1186-1201

We report the investigation of cutting methods for Hayabusa samples. The purpose of our study is to explore the possibility of applying multiple analyses to a single particle effectively. We investigated the cutting performance of a blade dicing saw, laser, focused ion beam (FIB), and physical breaking by microindenter. Cutting performance was examined by estimating the aspect ratio of the cut slit, i.e., depth over width of the slit. We also investigated the possible contamination and sample damage by cutting. The result of the investigation shows that we can cut the samples from <50 μm to 500 μm using those methods with aspect ratios from 10 to 20, although they would introduce some contamination or damage to the samples. Our investigations also provide an important basis for the analysis of samples obtained by future sample return missions.  相似文献   

Three‐dimensional microstructure of samples recovered from asteroid 25143 Itokawa: Comparison with LL5 and LL6 chondrite particles     

Akira Tsuchiyama  Masayuki Uesugi  Kentaro Uesugi  Tsukasa Nakano  Ryo Noguchi  Toru Matsumoto  Junya Matsuno  Takashi Nagano  Yuta Imai  Akira Shimada  Akihisa Takeuchi  Yoshio Suzuki  Tomoki Nakamura  Takaaki Noguchi  Masanao Abe  Toru Yada  Akio Fujimura 《Meteoritics & planetary science》2014,49(2):172-187

In this study, the three‐dimensional (3‐D) microstructure of 48 Itokawa regolith particles was examined by synchrotron microtomography at SPring‐8 during the preliminary examination of Hayabusa samples. Moreover, the 3‐D microstructure of particles collected from two LL6 chondrites (Ensisheim and Kilabo meteorites) and an LL5 chondrite (Tuxtuac meteorite) was investigated by the same method for comparison. The modal abundances of minerals, especially olivine, bulk density, porosity, and grain size are similar in all samples, including voids and cracks. These results show that the Itokawa particles, which are surface materials from the S‐type asteroid Itokawa, are consistent with the LL chondrite materials in terms of not only elemental and isotopic composition of the minerals but also 3‐D microstructure. However, we could not determine whether the Itokawa particles are purely LL5, LL6, or a mixture of the two. No difference between the particles collected from Rooms A and B of the sample chamber, corresponding to the sampling sequence of the spacecraft's second and first touchdowns, respectively, was detected because of the statistically small amount of particles from Room B.  相似文献   

MURS-300 MK II: A remote inspection system for underwater facilities of hydraulic power plants     

Tsusaka  Y. Ishidera  H. Itoh  Y. 《Oceanic Engineering, IEEE Journal of》1986,11(3):358-363

While the civil engineering facilities of hydraulic power plants such as dam, water intake, waterway, etc., are usually submerged, there are few effective methods for their inspection. So we at Mitsui Ocean Development and Engineering Co., Ltd. (MODEC) have developed a new remote-controlled inspection system named "MURS-300 MK II" (MODEC Unmanned Remote-Controlled Submersible for 300-m water depth) in cooperation with Tokyo Electric Power Co., Inc. This MK II system, which consists of a submersible vehicle with a TV camera and a still camera, a handling system, a control van, and a composite cable with optical fibers, was designed, developed, and successfully evaluated at the end of 1984. This new system will find many applications to the inspection of nuclear and thermal power stations, offshore platforms, etc., as well as hydraulic power plants.  相似文献   

The effects of radiative transfer on the reionization of an inhomogeneous universe     

Taishi Nakamoto  Masayuki Umemura  Hajime Susa 《Monthly notices of the Royal Astronomical Society》2001,321(4):593-604

Assuming simple dynamics for the growth of density fluctuations, we implement six-dimensional (6D) radiative transfer calculations to elucidate the effects of photon propagation during the reionization of an inhomogeneous universe. The ionizing sources are postulated to be AGN-like in this paper. The present simulations reveal that radiative transfer effects are still prominent considerably after the percolation epoch, in which patchy ionized regions connect with each other. In other words, owing to the collective opacity, the Universe does not become perfectly transparent against ionizing radiation even though strongly self-shielded regions disappear. It turns out that the inhomogeneity of the medium enhances the opacity effects and delays the end of reionization. Owing to such radiative transfer effects, the reionization in an inhomogeneous universe proceeds fairly slowly, in contrast to the prompt reionization in a homogeneous universe, and as a result the surface of reionization is not so sharply edged, but highly uneven. As a signature of the uneven surface of reionization, the cosmic IR background (CIB) radiation, which is produced by Ly photons resulting from radiative recombination, could exhibit strong anisotropies, reflecting the amplitude of density fluctuations at the reionization era. The predicted CIB intensity lies on a level of possible detection by forthcoming IR space telescope facilities.  相似文献   

The Structure of Young Stellar Jets and Winds Revealed by High Resolution [Fe II] λ1.644μm Line Observations     

Tae-Soo Pyo  Masahiko Hayashi  Naoto Kobayashi  Alan T. Tokunaga  Hiroshi Terada  Miwa Goto  Takuya Yamashita  Yoichi Itoh  Hideki Takami  Naruhisa Takato  Yutaka Hayano  Wolfgang Gaessler  Yukiko Kamata  Yosuke Minowa  Masanori Iye 《Astrophysics and Space Science》2003,287(1-4):21-24

We present high angular resolution spectra taken along the jets from L1551 IRS 5 and DG Tau obtained with the Subaru Telescope. The position-velocity diagrams of the [Fe II] λ 1.644 μmemission line revealed remarkably similar characteristics for the two sources, showing two distinct velocity components separated from each other in both velocity and space with the entire emission range blueshifted with respect to the stellar velocity. The high velocity component (HVC) has a velocity of –200 ––300 km s^-1 with a narrow line width, while the low velocity component (LVC) is around –100 km s^-1 exhibitinig a broad line width. The HVC is located farther away from the origin and is more extended than the LVC. Our results suggest that the HVC is a well-collimated jet originating from the region close to the star, while the LVC is a widely-opened wind accelerated in the region near the inner edge of the accretion disk.  相似文献   

Cosmological radiative transfer codes comparison project – I. The static density field tests     

Ilian T. Iliev  Benedetta Ciardi  Marcelo A. Alvarez  Antonella Maselli  rea Ferrara  Nickolay Y. Gnedin  Garrelt Mellema  Taishi Nakamoto  Michael L. Norman  Alexei O. Razoumov  Erik-Jan Rijkhorst  Jelle Ritzerveld  Paul R. Shapiro  Hajime Susa  Masayuki Umemura  Daniel J. Whalen 《Monthly notices of the Royal Astronomical Society》2006,371(3):1057-1086

Radiative transfer (RT) simulations are now at the forefront of numerical astrophysics. They are becoming crucial for an increasing number of astrophysical and cosmological problems; at the same time their computational cost has come within reach of currently available computational power. Further progress is retarded by the considerable number of different algorithms (including various flavours of ray tracing and moment schemes) developed, which makes the selection of the most suitable technique for a given problem a non-trivial task. Assessing the validity ranges, accuracy and performances of these schemes is the main aim of this paper, for which we have compared 11 independent RT codes on five test problems: (0) basic physics; (1) isothermal H  ii region expansion; (2) H  ii region expansion with evolving temperature; (3) I-front trapping and shadowing by a dense clump and (4) multiple sources in a cosmological density field. The outputs of these tests have been compared and differences analysed. The agreement between the various codes is satisfactory although not perfect. The main source of discrepancy appears to reside in the multifrequency treatment approach, resulting in different thicknesses of the ionized-neutral transition regions and the temperature structure. The present results and tests represent the most complete benchmark available for the development of new codes and improvement of existing ones. To further this aim all test inputs and outputs are made publicly available in digital form.  相似文献