Factors Controlling the Fractionation and Seasonal Mobility Variations of Ga and In in Systems Impacted by Acidic Thermal Waters: Effects of Thermodynamics and Bacterial Activity     

Yasumasa Ogawa  Daizo Ishiyama  Naotatsu Shikazono  Koichi Suto  Chihiro Inoue  Noriyoshi Tsuchiya  Bernhardt Saini-Eidukat  Scott A. Wood 《Aquatic Geochemistry》2018,24(1):5-25

This work assessed both the fractionation and the seasonal mobility variations of Ga and In in systems impacted by acidic thermal waters. This was accomplished by performing thermodynamic calculations using the PHREEQC algorithm and by assessing the activity of acidophilic iron-oxidizing bacteria. The pH of the Kusatsu thermal waters in Gunma Prefecture, central Japan, is rapidly increased following the addition of a lime suspension. After an abrupt pH increase, under which conditions free ions of Ga and In and their complexes with Cl^? and SO₄^2? exist only in negligible quantities, the majority of dissolved Ga and In is removed by sorption onto suspended hydrous ferric oxides (HFOs). These HFOs are then transported to an artificial lake without significant sedimentation along the river. Subsequently, the suspended HFOs settle out and are added to sediments without significant fractionation between Ga and In. The Tamagawa thermal waters in Akita Prefecture, northeast Japan, are also treated with lime. However, complete neutralization requires mixing with some tributary streams, leading to a gradual downstream increase in pH. Dissolved Ga is, in general, sorbed by HFOs in upstream areas, leading to wide dispersal of Ga across the entire watershed. In comparison, In is transported to the lake inlet predominantly as a Cl^? complex species without significant removal along the river, with the majority being precipitated in an artificial lake, where Cl^? concentrations are too low to form stable complex species with In, and thus, dissolved In is sorbed by HFOs. As a result, In is effectively concentrated within downstream lakebed sediments, whereas Ga is dispersed along the river. Seasonal variations in Ga mobility within the Tamagawa field between snowmelt and low-flow seasons are primarily controlled by pH, because hydrolysis reactions of these metals, which are related to sorption reactions, tend to occur in the upstream regions in the snowmelt season. However, under warmer conditions, HFO formation preferably occurs due to the activity of acidophilic iron-oxidizing bacteria. Thus, under similar pH variations, dissolved Ga is more effectively removed by HFOs during warmer seasons. On the contrary, because HFOs are abundantly formed in low-flow season, even under colder conditions, before In hydrolysis reaction starts to occur, In mobility is less affected by water temperature and then bacterial activity.  相似文献   

Seismic interaction of underground RC ducts and neighboring bridge piers in liquefiable soil foundation     

Saeed Moshirabadi  Masoud Soltani  Koichi Maekawa 《Acta Geotechnica》2015,10(6):761-780

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An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials     

Asten  Michael W.  Yong  Alan  Foti  Sebastiano  Hayashi  Koichi  Martin  Antony J.  Stephenson  William J.  Cassidy  John F.  Coleman  Jacie  Nigbor  Robert  Castellaro  Silvia  Chimoto  Kosuke  Cornou  Cécile  Cho  Ikuo  Hayashida  Takumi  Hobiger  Manuel  Kuo  Chun-Hsiang  Macau  Albert  Mercerat  E. Diego  Molnar  Sheri  Pananont  Passakorn  Pilz  Marco  Poovarodom  Nakhorn  Sáez  Esteban  Wathelet  Marc  Yamanaka  Hiroaki  Yokoi  Toshiaki  Zhao  Don 《Journal of Seismology》2022,26(4):757-780

Journal of Seismology - Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site...  相似文献   

Simulation of Formation and Spreading of Salinity Minimum Associated with NPIW Using a High-Resolution Model     

Hiroshi Ishizaki  Ichiro Ishikawa 《Journal of Oceanography》2002,58(2):463-485

A series of numerical experiments were conducted with a high-resolution (eddy-permitting) North Pacific model to simulate the formation and spreading of the salinity minimum associated with the North Pacific Intermediate Water (NPIW). It was found that two factors are required to simulate a realistic configuration of the salinity minimum: a realistic wind stress field and small-scale disturbances. The NCEP reanalyzed wind stress data lead to better results than the Hellerman and Rosenstein wind stress data, due to the closer location of the simulated Oyashio and Kuroshio at the western boundary. Small-scale disturbances formed by relaxing computational diffusivity included in the advection scheme promote the large-scale isopycnal mixing between the Oyashio and Kuroshio waters, simulating a realistic configuration of the salinity minimum. A detailed analysis of the Oyashio water transport was carried out on the final three-year data of the experiment with reduced computational diffusivity. Simulated transport of the Kuroshio Extension in the intermediate layer is generally smaller than the observed value, while those of the Oyashio and the flow at the subarctic front are comparable to the observed levels. In the Oyashio-Kuroshio interfrontal zone the zonally integrated southward transport of the Oyashio water (140-155°E) is borne by the eddy activity, though the time-mean flow reveals the existence of a coastal Oyashio intrusion. In the eastern part (155°E-180°) the zonally integrated transport of the Oyashio water indicates a southward peak at the southern edge of the Kuroshio Extension, which corresponds to the branching of the recirculating flow from the Kuroshio Extension.  相似文献   

Dilution of North Pacific Intermediate Water studied with chlorofluorocarbons     

Yutaka W. Watanabe  Koh Harada  Kimitoshi Ishikawa 《Journal of Oceanography》1995,51(2):133-144

Assessment was made of residual ratio of North Pacific Intermediate Water (NPIW) produced in subpolar region of the North Pacific using chlorofluorocarbons, CFC-11 and CFC-12 (CCl₃F and CCl₂F₂), along 175°E. NPIW on density horizons less than 26.80 remained more than 80% north of 30°N. It was suggested that new NPIW laterally spreads over the northern North Pacific without hardly being diluted by the surroundings. For density horizons greater than 26.80 north of 30°N, NPIW remained less than 60%. The difference in the residual ratio between <26.80 and >26.80 north of 30°N suggests that NPIW is produced on density horizons less than 26.80, which contacts the atmosphere in the subpolar region, and that NPIW is diluted by upwelling deep water on density horizons greater than 26.80 in high latitude of the North Pacific. NPIW on a density horizon of 26.80 remained about 50% south of 30°N. The decrease in the horizontal distribution of the residual ratio of NPIW suggests that half the new NPIW produced in the subpolar region is laterally spread over the North Pacific with the southward movement of NPIW.  相似文献   

Bunnoite,a new hydrous manganese aluminosilicate from Kamo Mountain,Kochi prefecture,Japan     

Daisuke Nishio-Hamane  Koichi Momma  Ritsuro Miyawaki  Tetsuo Minakawa 《Mineralogy and Petrology》2016,110(6):917-926

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Evolution of the composition of seawater through geologic time, and its influence on the evolution of life   总被引：2，自引：2，他引：0  

Tsuyoshi Komiya  Takafumi Hirata  Kouki Kitajima  Shinji Yamamoto  Takazo Shibuya  Yusuke Sawaki  Tomoko Ishikawa  Degan Shu  Yong Li  Jian Han 《Gondwana Research》2008,14(1-2):159

The redox state of the surface environment of the early Earth is still controversial, and a detailed and quantitative estimate is still lacking. We carried out in-situ analyses of major, trace, and rare-earth elements of carbonate minerals in rocks with primary sedimentary structures in shallow and deep sea-deposits, in order to eliminate secondary carbonate and contamination of detrital materials, and to estimate the redox condition of seawater through time. Based on the Ce content and anomalies of the carbonate minerals at given parameters of atmospheric CO₂ content (pCO₂) and Ca content of seawater, we calculated the oxygen contents of shallow and deep seawater, respectively. The results show that the oxygen content of the deep sea was low and constant until at least 1.9 Ga. The oxygen content of shallow seawater increased after 2.7 Ga, but fluctuated. It became quite high at 2.5 and 2.3 Ga, but eventually increased after the Phanerozoic. In addition, the calculation of a high pCO₂ condition shows that seawater was more oxic even in the Archean than at present, suggesting a relatively low pCO₂ through geologic time.Our detailed calculations from compositions of carbonate minerals in Three Gorge area, south China show a low oxygen content of seawater after the Snowball Earth until the late Ediacaran, an increase in the late Ediacaran, and a significant decrease around the Precambrian–Cambrian and Nemakit/Daldynian–Tommotian boundaries. These variations were possibly caused by global regression and dissolution of methane hydrates.  相似文献   

Radiative characteristics in a Japanese forested drainage basin during snowmelt     

H. Nakabayashi  N. Ishikawa  Y. Kodama 《水文研究》1999,13(2):157-167

Radiative characteristics in a forested drainage basin during the snowmelt season were examined in order to better understand and predict snowmelt runoff in the basin. A method for estimating net radiation in a forest (R_nf) was presented using the total sky view factor (P) and the sun path sky view factor (Q). Solar radiation, albedo, atmospheric radiation and air temperature observed at an open site were also required. The total and the sun path sky view factors were determined from all‐sky photographs. Q was expressed as a linear function of P for 0·15<P<0·86 regardless of forest type. For P<0·15, Q was set to zero, and for P>0·86, Q was equal to unity. The short‐wave radiation budget at the forest floor (S_nf) increased with P, whereas the long‐wave radiation budget (L_nf) decreased with P. R_nf increased with P for 0·15<P<0·86, and changed little with P for P<0·15 and P>0·86, as the increase in S_nf was offset by the decrease in L_nf . The forest effect on R_nf was diminished under cloudy or high albedo conditions, because S_nf was easily offset by L_nf . This estimation method was extended to the whole basin, and R_nf was obtained over a watershed covered by trees. At the beginning of the snowmelt season when the albedo remained high, the forest effect became null because the decrease in S_nf was balanced by the increase in L_nf . As the albedo gradually lowered with the advance of the snowmelt season, the decrease in S_nf owing to forest covers exceeded the increase in L_nf , and the forest effect to decrease R_nf became evident. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Occurrence conditions of hyperpycnal flows, and their significance for organic-matter sedimentation in a Holocene estuary, Niigata Plain, Central Japan     

Mamiko  Yoshida  Yuka  Yoshiuchi  Koichi  Hoyanagi 《Island Arc》2009,18(2):320-332

River floods influence sedimentary environments and ecosystems from the terrestrial to the deep-marine. This study documents the occurrence conditions of hyperpycnal flows generated by river floods and related organic-matter sedimentation for Holocene sediments of the Niigata Plain, Central Japan, based on detailed sedimentary facies, total sulfur and total organic carbon content, diatom assemblages and organic-matter composition. Holocene sediments of the Niigata Plain consist of sand, mud and gravel that were deposited in estuarine and fluvial systems during a sea-level rise (15 000–6800 years BP) and stillstand (after 6800 years BP) following the Last Glacial Maximum. Hyperpycnites are present in the upper part of the estuarine lagoon sediments. The depositional age is considered to be about 5000 years BP. The hyperpycnites comprise two successions of a top fining-up unit and a basal coarsening-up unit, and include abundant terrigenous organic matter and freshwater diatoms. A large volume of freshwater is inferred to have flowed into the lagoon during deposition of the upper part of the lagoon sediments. In consequence, hyperpycnal flows may have readily formed in the lagoon, because the halocline was weak. The hyperpycnal flows also produced a layer of concentrated terrigenous organic matter in the uppermost part of the hyperpycnites. The abundant organic matter on the estuarine floor is inferred to have produced anoxic bottom conditions owing to oxidative decomposition by benthic bacteria.  相似文献   

Characteristics of Sea Surface Circulation and Eddy Field in the South China Sea Revealed by Satellite Altimetric Data   总被引：4，自引：0，他引：4  

Akihiko Morimoto  Koichi Yoshimoto  Tetsuo Yanagi 《Journal of Oceanography》2000,56(3):331-344

Temporal and spatial variations of sea surface circulation in the South China Sea were revealed with use of altimetric data provided by TOPEX/POSEIDON from December 1992 to October 1997. The estimated distribution of sea surface dynamic heights from altimetric data coincide well with the results of observation by Soong et al. (1995) and Chu et al. (1998). The RMS variability of sea surface dynamic height, which is obtained after tidal correction based on Yanagi et al. (1997), is high in the central part of the South China Sea, the Gulf of Tongking, the Sunda Shelf and the Gulf of Thailand. The high RMS variability in the Gulf of Tongking, the Sunda Shelf and the Gulf of Thailand is due to set up and set down of sea water by the East Asian monsoon, which is northeasterly during winter and southwesterly during summer. Also, the high RMS variability in the central part of the South China Sea is due to the variations of basin-wide circulation. The circulations are dominant in the central part of the South China Sea during summer and winter, an anticyclonic circulation during summer and a cyclonic circulation during winter. It is suggested that these circulations are controlled by the East Asian monsoon. Hence, there is an interannual variability of the basin-wide circulation associated with the variation of the East Asian monsoon.  相似文献