Field measurements of absolute gravity in East Antarctica     

Koichiro Doi  Hideaki Hayakawa  Takahito Kazama  Toshihiro Higashi  Shingo Osono  Yoichi Fukuda  Jun Nishijima  Yuichi Aoyama  Junichi Ueda 《极地研究(英文版)》2013,(4):339-343

Abstract This paper reports the results of field-based absolute gravity measurements aimed at detecting gravity change and crustal displacement caused by glacial isostatic adjustment. The project was initiated within the framework of the 53rd Japanese Antarctic Research Expedition （JARE53）. Absolute gravity measurements, together with GPS measurements, were planned at several outcrops along the Prince Olav Coast and S6ya Coast of East Antarctica, including at Syowa Station. Since the icebreaker Shirase （AGB 5003） was unable to moor alongside Syowa Station, operations were somewhat restricted during JARE53. However, despite this setback, we were able to complete measurements at two sites： Syowa Station and Langhovde. The absolute gravity value at the Syowa Station IAGBN （A） site, observed using an FG-5 absolute gravimeter （serial number 210; FG-5 #210）, was 982 524 322.7＋0.1 ktGal, and the gravity change rate at the beginning of 2012 was -0.26 gGal.a-1. An absolute gravity value of 982 535 584.2~0.7 ktGal was obtained using a portable A-10 absolute gravimeter （serial number 017; A-10 #017） at the newly located site AGS01 in Langhovde.  相似文献   

Eutrophication-induced changes in Lake Nakaumi,southwest Japan     

Kota Katsuki  Yasushi Miyamoto  Kazuyoshi Yamada  Hiroyuki Takata  Keiko Yamaguchi  Daisuke Nakayama  Hugo Coops  Hidenobu Kunii  Ritsuo Nomura  Boo-Keun Khim 《Journal of Paleolimnology》2008,40(4):1115-1125

Lake Nakaumi, southwest Japan, is an enclosed lagoon characterized by polyhaline and halocline conditions. Since the last century, its ecological state has been altered by eutrophication. We used a paleolimnological approach and studied multiple proxies, including chemical compounds, diatoms, foraminifera and molluscs, to infer the eutrophication history of the ecosystem. Eutrophication in Lake Nakaumi was associated with several factors, including increased nutrient loading, input of herbicides, and dike building since the 1920s. The ecological condition of this lake was divided into several stages that reflect the eutrophication process after the 1940s. A catastrophic “regime shift” from a clear state with aquatic vegetation to a turbid one with phytoplankton occurred in the early 1950s. Environmental degradation in the Honjo area, a part of Lake Nakaumi, was attributed primarily to physical changes caused by the construction of an enclosing dike. Eutrophication occurred almost simultaneously with the physical changes to the Honjo area in the 1970s. Until recently, no regime shift was observed in this area, though the core-top sediments show possible symptoms of incipient change.  相似文献   

Formation age of the lunar crater Giordano Bruno     

Tomokatsu Morota  Junichi Haruyama  Hideaki Miyamoto  Chikatoshi Honda  Makiko Ohtake  Yasuhiro Yokota  Tsuneo Matsunaga  Naru Hirata  Hirohide Demura  Hiroshi Takeda  Yoshiko Ogawa  Jun Kimura 《Meteoritics & planetary science》2009,44(8):1115-1120

Abstract— Using the Terrain Camera onboard the Japanese lunar explorer, SELENE (Kaguya), we obtained new high‐resolution images of the 22‐kilometer‐diameter lunar crater Giordano Bruno. Based on crater size‐frequency measurements of small craters (<200 m in diameter) superposed on its continuous ejecta, the formation age of Giordano Bruno is estimated to be 1 to 10 Ma. This is constructive evidence against the crater's medieval age formation hypothesis.  相似文献   

Late Quaternary faulting along the western margin of the Poronaysk Lowland in central Sakhalin, Russia     

Hiroyuki Tsutsumi  Yasuhiro Suzuki  Andrei I. Kozhurin  Mihail I. Strel'tsov  Takeyuki Ueki  Hideaki Goto  Koji Okumura  Rustam F. Bulgakov  Hiroyuki Kitagawa 《Tectonophysics》2005,407(3-4):257-268

Sakhalin Island straddles an active plate boundary between the Okhotsk and Eurasian plates. South of Sakhalin, this plate boundary is illuminated by a series of M_w 7–8 earthquakes along the eastern margin of the Sea of Japan. Although this plate boundary is considered to extend onshore along the length of Sakhalin, the location and convergence rate of the plate boundary had been poorly constrained. We mapped north-trending active faults along the western margin of the Poronaysk Lowland in central Sakhalin based on aerial photograph interpretation and field observations. The active faults are located east of and parallel to the Tym–Poronaysk fault, a terrane boundary between Upper Cretaceous and Neogene strata; the active faults appear to have reactivated the terrane boundary at depth in Quaternary time. The total length of the active fault zone on land is about 140 km. Tectonic geomorphic features such as east-facing monoclinal and fault scarps, back-tilted fluvial terraces, and numerous secondary faults suggest that the faults are west-dipping reverse faults. Assuming the most widely developed geomorphic surface in the study area formed during the last glacial maximum at about 20 ka based on similarities of geomorphic features with those in Hokkaido Island, we obtain a vertical component of slip rate of 0.9–1.4 mm/year. Using the fault dip of 30–60°W observed at an outcrop and trench walls, a net slip rate of 1.0–2.8 mm/year is obtained. The upper bound of the estimate is close to a convergence rate across the Tym–Poronaysk fault based on GPS measurements. A trenching study across the fault zone dated the most recent faulting event at 3500–4000 years ago. The net slip associated with this event is estimated at about 4.5 m. Since the last faulting event, a minimum of 3.5 m of strain, close to the strain released during the last event, has accumulated along the central portion of the active strand of the Tym–Poronaysk fault.  相似文献   

Water requirements for cultivatingSalicornia bigeloviiTorr. with seawater on sand in a coastal desert environment     

Edward Glenn  Seiichi Miyamoto  David Moore  J.Jed Brown  T.Lewis Thompson  Paul Brown 《Journal of Arid Environments》1997,36(4):711-730

The forage and oilseed halophyte,Salicornia bigeloviiTorr., was grown in gravity-drained lysimeters set in open plots of the same crop over two seasons in a coastal desert environment in Sonora, Mexico. The lysimeters were irrigated daily with seawater (40 g l⁻¹salts) at rates ranging from 46–225% of potential evaporation. Biomass and seed yields increased with increasing irrigation depth over the range of treatments. Biomass yields ranged from 13·6–23·1 t DM ha⁻¹, equivalent to conventional forage crops, on seasonal water application depths of 2·3–3·8 m, but were markedly lower at lower irrigation depths. Increasing the irrigation depth lowered the soil solution salinity, resulting in greater growth and water use, and hence leaching fractions that were nearly even over irrigation treatments, averaging 0·5. Evapo-transpiration rose in direct proportion to the irrigation depth. Potential evaporation was estimated by site pan evaporation and by the Blaney-Criddle and Penman models using climatological data; the methods agreed within 15%. The ratio of evapo-transpiration to potential evaporation increased over the growing season and approached 1·5 by pan on the highest irrigation treatment due to the combined effects of high transpiration and high evaporation from the permanently moist soil surface. The best field predictor of biomass yield was the salinity of the soil moisture in the top 15 cm of soil profile, which constitutes the root zone for this crop. Root zone salinity must be kept at 70–75 g l⁻¹for high yields. Although irrigation and drainage requirements were high compared to conventional crops, seawater irrigation appears to be feasible in medium sand and could augment crop production along coastal deserts. The possibility of using this crop for animal production is discussed.  相似文献   

Ion migration in MgSiO3-perovskite and olivine by molecular dynamics calculations     

Masamichi Miyamoto 《Physics and Chemistry of Minerals》1988,15(6):601-604

We applied molecular dynamics (MD) simulations to finding likely paths of atomic migration of the Mg ion in forsterite (Mg₂SiO₄) and the oxygen ion in MgSiO₃-perovskite to better understand atomic diffusion in minerals. Our simulations show that there exist two routes of Mg migration in the forsterite structure, that is, paths between the M1 and M2 sites and between the M1 and M1 sites. In the MgSiO₃-perovskite structure, some oxygen ions migrate to the next sites all together through the O1 vacant site showing co-operative movements. The O ions are relatively mobile mainly along the b axis in the perovskite structure. Meta-stable sites are often present between a stable site and another stable site on atomic migration. In spite of many assumptions, our MD simulations may show likely paths of atomic migration in crystal.  相似文献   

Experimental calibration of sapphirine–spinel Fe–Mg exchange thermometer: Implication for constraints on P–T condition of Howard Hills, Napier Complex, East Antarctica     

Kei Sato  Tomoharu Miyamoto  Toshisuke Kawasaki 《Gondwana Research》2006,9(4):398-408

The Fe²⁺–Mg distribution coefficients between sapphirine and spinel:were experimentally determined at pressures of 9–13 kbar and temperatures of 950–1150 °C using a natural ultrahigh-temperature (UHT) granulite with paragenesis of these minerals from the Napier Complex in East Antarctica [X_Mg = Mg / (Fe + Mg); X_Fe = Fe / (Fe + Mg)]. A new sapphirine–spinel geothermometer has been obtained as:

We applied the exchange thermometer to UHT or high-grade metamorphic rocks that were reported from various complexes in the world. If the K_D values of 2.63–4.34 obtained from low-Cr mineral pairs such as X_Cr^Spr < 0.016 and X_Cr^Spl < 0.047 were substituted into the equation, their temperature conditions would be estimated as 806–1050 °C at 11 kbar. The X_Cr means Cr / (Al + Cr(+ Fe³⁺)). These temperatures are reasonable retrograde or near peak metamorphic condition.  相似文献   

The First International Workshop on Warning Criteria for Active Slides: technical issues,problems and solutions for managing early warning systems   总被引：1，自引：0，他引：1  

Catherine Cloutier  Federico Agliardi  Giovanni Battista Crosta  Paolo Frattini  Corey Froese  Michel Jaboyedoff  Jacques Locat  Clément Michoud  Hideaki Marui 《Landslides》2015,12(1):205-212

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Protective effect of phospholipid hydroperoxide glutathione peroxidase (PHGPx) against lipid peroxidation in mussels Perna perna exposed to different metals   总被引：2，自引：0，他引：2  

de Almeida EA  Miyamoto S  Bainy AC  de Medeiros MH  Di Mascio P 《Marine pollution bulletin》2004,49(5-6):386-392

Levels of antioxidant defenses and lipid peroxidation were evaluated in mussels exposed to lead (200 mg/l), iron (500 microg/l), cadmium (200 microg/l) and copper (40 microg/l), for 12, 24, 72 and 120 h. Glutathione S-transferase (GST) activity was unchanged with all treatments. Catalase (CAT) increased after 120 h of exposure to all metals. Mussels exposed to Cd for 12 h, and to Cu and Fe for 120 h had increased lipid peroxidation, which might be associated to decreased levels of reduced glutathione (GSH) and glutathione peroxidase (GPx) activity. Pb exposure caused GSH depletion after 12 h and increased GPx activity after 120 h. Negative correlations were observed between the enzyme phospholipid hydroperoxide glutathione peroxidase (PHGPx) and malonaldehyde (MDA) levels after Fe and Cu exposure, indicating a protective role of PHGPx against lipid peroxidation, and suggesting the use of this enzyme as a new potential biomarker of toxicity associated with contaminant exposure in mussels.  相似文献   

Biological productivity of meso-scale eddies caused by frontal disturbances in the Kuroshio   总被引：1，自引：0，他引：1  

Kimura  Shingo; Kasai  Akihide; Nakata  Hideaki; Sugimoto  Takashige; Simpson  John H.; Cheok  Joseph V. S. 《ICES Journal of Marine Science》1997,54(2):179-192

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