Solvation processes in steam: Ab initio calculations of ion-solvent structures and clustering equilibria     

Kono H. Lemke  Terry M. Seward 《Geochimica et cosmochimica acta》2008,72(14):3293-3310

Reports of the high ion content of steam and low-density supercritical fluids date back to the work of Carlon [Carlon H. R. (1980) Ion content of air humidified by boiling water.J. Appl.Phys.51, 171-173], who invoked ion and neutral-water clustering as mechanism to explain why ions partition into the low-density aqueous phase. Mass spectrometric, vibrational spectroscopic measurements and quantum chemical calculations have refined this concept by proposing strongly bound ion-solvent aggregates and water clusters such as Eigen- and Zundel-type proton clusters H₃O⁺·(H₂O)_m and the more weakly bound water oligomers (H₂O)_m. The extent to which these clusters affect fluid chemistry is determined by their abundance, however, little is known regarding the stability of such moieties in natural low-density high-temperature fluids. Here we report results from quantum chemical calculations using chemical-accuracy multi-level G3 (Curtiss-Pople) and CBS-Q theory (Peterson) to address this question. In particular, we have investigated the cluster structures and clustering equilibria for the ions and H₃S⁺·(H₂O)_m(H₂S)_n, where m ? 6 and n ? 4, at 300-1000 K and 1 bar as well as under vapor-liquid equilibrium conditions between 300 and 646 K. We find that incremental hydration enthalpies and entropies derived from van’t Hoff analyses for the attachment of H₂O and H₂S onto H₃O⁺, and H₃S⁺ are in excellent agreement with experimental values and that the addition of water to all three ions is energetically more favorable than solvation by H₂S. As clusters grow in size, the energetic trends of cluster hydration begin to reflect those for bulk H₂O liquids, i.e. calculated hydration enthalpies and entropies approach values characteristic of the condensation of bulk water (ΔH^o = −44.0 kJ mol⁻¹, ΔS^o = −118.8 J K mol⁻¹). Water and hydrogen sulfide cluster calculations at higher temperatures indicate that a significant fraction of H₃O⁺, and H₃S⁺ ions exists as solvated moieties.  相似文献   

Characteristics of Intraslab Stress Field and Tectonic Implication in the Nankai Trough, Japan     

XU Jiren  ZHAO Zhixin Institute of Geology  Chinese Academy of Geological Science  Beijing  China Kono Yoshiteru Faculty of Science  Kanazawa University  Kanazawa -  Japan 《Continental Dynamics》2000,(1)

1. IntroductionThe Nankai Trough region (Fig. 1.1) of southwest Japan is one of the most tectonically complex subduction zones in the world. The subduction of the Philippine Sea plate (PH) beneath the Eurasian plate (EU) has caused a series of large and great interplate earthquakes. It is generally accepted that great earthquakes have occurred at intervals of 100-150 years along the Nankai subduction zone since the 684 Hakuho earthquake (Fig. 1.2). However, a large earthquake (M>7.5) has…  相似文献   

Performance of HSC columns under severe cyclic loading     

Hakim Bechtoula  Susumu Kono  Fumio Watanabe  Youcef Mehani  Abderrahmane Kibboua  Mounir Naili 《Bulletin of Earthquake Engineering》2015,13(2):503-538

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Formation of the salinity minimum in the Mixed Water Region between the Oyashio and Kuroshio Fronts     

Tokihiro Kono   《Deep Sea Research Part I: Oceanographic Research Papers》1998,45(12):2035-2057

The salinity minimum frequently occurring in the Mixed Water Region between the Oyashio and Kuroshio Fronts seems to originate from the salinity minimum at the density of 26.8σ_θ called the North Pacific Intermediate Water. We examined water exchange of this region with the Oyashio and the Kuroshio Extension using mixing ratio R_K defined as (θ - θ_OY)/(θ_K - θ_OY) × 100, where θ_OY, θ_K, and θ represent potential temperature of the Oyashio and Kuroshio Waters and their mixture on the isopycnal surfaces, respectively. CTD data were obtained by repeated observation from January 1990 to May 1991. R_K increases southward from the Oyashio Front to the Kuroshio Front with the range of −20 to 120%. The gradient of R_K on the isopycnal surfaces is large around the Oyashio Front above the 26.8σ_θ surface, while it is large around the Kuroshio Front below it. This agrees with the average R_K in the Mixed Water Region decreasing greatly with the increase of density at densities less dense than 26.8σ_θ. We calculated thickness and volume transport of the Oyashio between the isopycnal surfaces near the coast of Hokkaido. They increase largely with density at densities less dense than 26.8σ_θ. It is supposed that the salinity minimum in the Mixed Water Region is the upper limit of the water largely influenced by the Oyashio Water. Its density could depend only on the density structure of the Oyashio.  相似文献   

The distribution of total and methylmercury concentrations in soils near the Idrija mercury mine, Slovenia, and the dependence of the mercury concentrations on the chemical composition and organic carbon levels of the soil     

Takashi Tomiyasu  Akito Matsuyama  Ryusuke Imura  Hitoshi Kodamatani  Junko Miyamoto  Yuriko Kono  David Kocman  Jo?e Kotnik  Vesna Fajon  Milena Horvat 《Environmental Earth Sciences》2012,65(4):1309-1322

Although the mining activity of the Idrija mine in Slovenia ceased in 1995, a large amount of mining dregs containing high concentrations of mercury remains in the area. The mining dregs were transported with river flow and deposition along the Idrija River. To estimate the dispersion and change in the chemical form of mercury, a total of 28 soil core samples were taken around the river. The individual core samples were separated into layers for the analysis of their chemical composition, carbon contents, total mercury (T-Hg) and methylmercury (MeHg) concentrations. The chemical composition measured by X-ray fluorescence spectrometry was useful to estimate the dispersion of tailings: the fluvial terrace soil had a chemical composition similar to that of the tailings and could be distinguished clearly from the forest soil. The highest T-Hg concentration, 1,100 mg kg⁻¹, was observed in the fluvial terrace soil near the mine. Although the concentration decreased gradually along with distance from the mine, concentrations higher than 200 mg kg⁻¹ of T-Hg were still observed in the fluvial terrace soil approximately 20 km downstream from the mine. In the vertical distribution of T-Hg in the hillslope soil, a higher value was observed in the upper layers, which suggests the recent atmospheric deposition of mercury. The concentration of MeHg was the lowest at the riverside and higher in the hillslope soil, which was the opposite of the T-Hg distribution. The total organic carbon content tracked similarly with the distribution of MeHg and a linear relation with a significantly high correlation coefficient was obtained. The distinction may be related to the different dispersion process of mercury, and the organic carbon contents may be an important factor for MeHg formation.  相似文献   

Numerical Investigations of Mean Winds Within Canopies of Regularly Arrayed Cubical Buildings Under Neutral Stability Conditions   总被引：2，自引：2，他引：0  

Takaaki Kono  Tetsuro Tamura  Yasunobu Ashie 《Boundary-Layer Meteorology》2010,134(1):131-155

Recently, several attempts have been made to model the wind velocity in an urban canopy in order to accurately predict the mixing and transport of momentum, heat, and pollutants within and above the canopy on an urban scale. For this purpose, unverified assumptions made by Macdonald (Boundary-Layer Meteorol 97:25–45, 2000) to develop a model for the profile of the mean wind velocity within an urban canopy have been used. In the present study, in order to provide foundations for improving the urban canopy models, the properties of the spatially-averaged mean quantities used to make these assumptions have been investigated by performing large-eddy simulations (LES) of the airflow around square and staggered arrays of cubical blocks with the following plan area densities: λ _p = 0.05, 0.11, 0.16, 0.20, 0.25, and 0.33. The LES results confirm that the discrepancy between the spatial average of wind velocity and Macdonald’s five-point average of wind velocity can be large in both types of arrays for large λ _p . It is also confirmed that Prandtl’s mixing length varies significantly with height within the canopy, contrary to Macdonald’s assumption for both types of arrays and for both small and large λ _p . On the other hand, in accordance with Macdonald’s assumption, the sectional drag coefficient is found to be almost constant with height except in the case of staggered arrays with high λ _p .  相似文献   

Modeling of spring bloom in the western subarctic Pacific (off Japan) with observed vertical density structure   总被引：1，自引：0，他引：1  

A. Yoshimori  J. Ishizaka  T. Kono  H. Kasai  H. Saito  M. J. Kishi  S. Taguchi 《Journal of Oceanography》1995,51(4):471-488

Effects of vertical stability on spring blooms of phytoplankton were investigated for the western subarctic Pacific ocean using a one-dimensional (depth) ecosystem model. In the model, vertical stability was expressed by diffusion constants calculated from observed density distribution. Dynamics of phytoplankton in blooms was calculated by the model using the vertical diffusion. Then, the calculated results were compared with the Coastal Zone Color Scanner (CZCS) data. The comparison shows that the shallow surface mixed layer causes early start days of spring blooms at inshore (northern) stations. In addition, spring blooms continue long at inshore (northern) stations since a water column has weak stability. This is because weak stability of a water column causes large nutrient supply from a deep layer and large diffusive transport of phytoplankton biomass from the subsurface maximum.  相似文献   

Wind environment in the Lee of Kauai Island,Hawaii during trade wind conditions: weather setting for the Helios Mishap     

John N. Porter  Duane Stevens  Kevin Roe  Sheldon Kono  David Kress  Eric Lau 《Boundary-Layer Meteorology》2007,123(3):463-480

On 26 June 2003 (approximately 1030 local time) the Helios ultralight aircraft broke apart off the west coast of Kauai Island, Hawaii as it was climbing out of the Kauai wind shadow. Following the aircraft mishap, a study was carried out to understand the conditions on the day of the crash and to better characterize the wind in the lee of Kauai. As part of this effort, both aircraft measurements and numerical modelling studies were carried out. Measurements and models showed the trade wind flow was enhanced around the island creating a region of wind shear surrounding the leeside calm zone. This wind shear region was found to be vertically oriented along the south side but tilted northward with height along the northern side of the calm zone. Several other factors on the day of the crash were investigated including water vapour gradients, diurnal Island heating, and gravity waves but their possible influences on the crash could not be confirmed. While the numerical model captured the general features of the Kauai leeside winds, the orientation of the calm zone was north of the observed one.  相似文献   

Paleointensity determination by a modified thellier method     

Masaru Kono  Naoko Ueno 《Physics of the Earth and Planetary Interiors》1977,13(4):305-314

It has been frequently observed that the ferromagnetic minerals in volcanic rocks may undergo some physical/chemical changes when they are heated in a laboratory. For paleointensity determinations, it is therefore desirable to use the Thellier method, in which internal consistency of the data assures that such undesirable changes did not take place in a particular sample. The most serious drawback of this method is that it requires a considerable number of heatings and coolings and measurements of the remanent magnetization. Following a suggestion of Kono, a modified version of Thellier's technique was developed and applied to a historical lava flow of Hawaii and Oligocene rhyolites and welded tuffs of San Juan volcanic field, Colorado, U.S.A. Samples were heated only once to each temperature and cooled under a magnetic field applied perpendicular to the NRM directions. Results were compared to those obtained by the conventional Thelliers' technique. It was found that the modified method gives results as satisfactory as the original method. With the selection of appropriate samples, the modified method will cut down the time required for the experiment to almost half of what is required in the original method, without losing the merits of Thelliers' technique.  相似文献   

Water mass exchange and diapycnal mixing at Bussol’ Strait revealed by water mass properties     

Kazuya Ono  Kay I. Ohshima  Tokihiro Kono  Motoyo Itoh  Katsuro Katsumata  Yuri N. Volkov  Masaaki Wakatsuchi 《Journal of Oceanography》2007,63(2):281-291

Intensive CTD observations that resolve the mean and tidal components were done with a total of 129 casts in summer of 2001 at Bussol’ Strait. Based on these data and all the available historical data, we have revealed the outflow from Bussol’ Strait to the Pacific and the significant diapycnal mixing in the strait. In the range 27.0−27.3σ _θ , the water property in Bussol’ Strait is almost identical to that of the Kuril Basin Water (KBW). The KBW out of Bussol’ Strait forms a water mass front with the East Kamchatka Current Water (EKCW). This front also corresponds to the front of the Oyashio Current. In the lower part of the intermediate layer (27.3−27.6σ _θ ), part of the water in the strait is characterized by lower temperature, lower salinity, and higher dissolved oxygen than that of KBW and EKCW, which can be explained only by the diapycnal mixing. The strong diapycnal mixing in the strait can also be shown by the density inversion, occurrence frequency of which corresponds well to the amplitude distribution of the diurnal current. In the density range 26.7−26.8σ _θ , the water in Bussol’ Strait has the lowest potential vorticity, suggesting that it is a source region of the low potential vorticity water. Seasonal change of the water can reach up to a density of 26.8σ _θ around Bussol’ Strait. This leads us to propose that the combination of winter convection and local tidal mixing leads to effective ventilation of the intermediate layer.  相似文献