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排序方式: 共有190条查询结果,搜索用时 31 毫秒
1.
The passivation of calcite by acid mine water. Column experiments with ferric sulfate and ferric chloride solutions at pH 2 总被引:2,自引:1,他引:1
Josep M. Soler Marco Boi Jos Luis Mogolln Jordi Cama Carlos Ayora Peter S. Nico Nobumichi Tamura Martin Kunz 《Applied Geochemistry》2008,23(12):3579-3588
Column experiments, simulating the behavior of passive treatment systems for acid mine drainage, have been performed. Acid solutions (HCl or H2SO4, pH 2), with initial concentrations of Fe(III) ranging from 250 to 1500 mg L−1, were injected into column reactors packed with calcite grains at a constant flow rate. The composition of the solutions was monitored during the experiments. At the end of the experiments (passivation of the columns), the composition and structure of the solids were measured. The dissolution of calcite in the columns caused an increase in pH and the release of Ca into the solution, leading to the precipitation of gypsum and Fe–oxyhydroxysulfates (Fe(III)–SO4–H+ solutions) or Fe–oxyhydroxychlorides (Fe(III)–Cl–H+ solutions). The columns worked as an efficient barrier for some time, increasing the pH of the circulating solutions from 2 to 6–7 and removing its metal content. However, after some time (several weeks, depending on the conditions), the columns became chemically inert. The results showed that passivation time increased with decreasing anion and metal content of the solutions. Gypsum was the phase responsible for the passivation of calcite in the experiments with Fe(III)–SO4–H+ solutions. Schwertmannite and goethite appeared as the Fe(III) secondary phases in those experiments. Akaganeite was the phase responsible for the passivation of the system in the experiments with Fe(III)–Cl–H+ solutions. 相似文献
2.
Yoichi?ShimadaEmail author Atsushi?Kubokawa Kay?I.?Ohshima 《Journal of Oceanography》2005,61(5):913-920
Recent observations suggest that the annual mean southward transport of the East Sakhalin Current (ESC) is significantly larger
than the annual mean Sverdrup transport. Motivated by this observational result, transport of a western boundary current has
been investigated using a simple numerical model with a western slope. This transport is defined as the instantaneous barotropic
transport integrated from the western boundary to the offshore point where the barotropic velocity vanishes. The model, forced
by seasonally varying wind stress, exhibits an annual mean of the western boundary current transport that is larger than that
of the Sverdrup transport, as observed. The southward transport from October to March in the model nearly equals the instantaneous
Sverdrup transport, while the southward transport from April to September decreases slowly. Although the Sverdrup transport
in July vanishes, the southward transport in summer nearly maintains the annual mean Sverdrup transport, because the barotropic
Rossby wave cannot intrude on the western slope. This summer transport causes the larger annual mean. Although there are some
uncertainties in the estimation of the Sverdrup transport in the Sea of Okhotsk, the seasonal variation of the southward transport
in the model is qualitatively similar to the observations. 相似文献
3.
State Estimation of the North Pacific Ocean by a Four-Dimensional Variational Data Assimilation Experiment 总被引:1,自引:0,他引:1
Toshiyuki Awaji Shuhei Masuda Yoichi Ishikawa Nozomi Sugiura Takahiro Toyoda Tomohiro Nakamura 《Journal of Oceanography》2003,59(6):931-943
A four-dimensional variational data assimilation system has been applied to an experiment to describe the dynamic state of
the North Pacific Ocean. A synthesis of available observational records and a sophisticated ocean general circulation model
produces a dynamically consistent dataset, which, in contrast to the nudging approach, provides realistic features of the
seasonally-varying ocean circulation with no artificial sources/sinks for temperature and salinity fields. This new dataset
enables us to estimate heat and water mass transports in addition to the qualification of water mass formation and movement
processes. A sensitivity experiment on our assimilation system reveals that the origin of the North Pacific Intermediate Water
can be traced back to the Sea of Okhotsk and the Bering Sea in the subarctic region and to the subtropical Kuroshio region
further south. These results demonstrate that our data assimilation system is a very powerful tool for the identification
and characterization of ocean variabilities and for our understanding of the dynamic state of ocean circulation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Hiroshi Kobayashi Keiichi Tamura Shunsuke Tanimoto 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1135-1141
In order to improve seismic design technology of bridges, it is necessary to evaluate the vibration characteristics of a bridge–soil system that consists of soil, foundation structure, pier and superstructure. However, there have been few experimental studies on seismic behavior of bridge–soil system. In this paper, we conducted the hybrid vibration experiment on seismic behavior of bridge–soil system, and examined the applicability of hybrid vibration experiment to study seismic response of bridge–soil system. Based on the experiment results, seismic response of bridge was quantitatively studied. 相似文献
5.
Jule Xiao Yoshio Inouchi Hisao Kumai Shusaku Yoshikawa Yoichi Kondo Tungsheng Liu Zhisheng An 《Quaternary Research》1997,47(3):277-283
The record of the biogenic silica flux (BSF, g cm−2(103yr)−1) in Lake Biwa reflects changes in diatom productivity in the lake and provides information regarding changes in paleoclimatic conditions. The BSF record of Lake Biwa demonstrates five periods over the past ca. 145,000 yr when the BSF values were significantly greater than 7.5 g cm−2(103yr)−1, and five intervals when they were lower. The data imply that paleoclimatic conditions were warmer and wetter from ca. 123,000 to 115,000, 103,000 to 95,000, 88,000 to 72,000, 57,000 to 32,000 yr B.P., and around ca. 6000 yr B.P. when the BSF values were greater, and relatively dry and cold from ca. 141,000 to 123,000 yr B.P. and during intervals between two of the five warm and wet episodes when the BSF values were lower. Time series of the BSF record can be correlated with the record of biogenic silica content in Lake Baikal and the marine oxygen isotope stages 1 through 6. Furthermore, the BSF values varied with much higher amplitude during the last interglaciation than during the last glaciation, probably implying that the diatom productivity in Lake Biwa was likewise more variable and had a larger range under interglacial conditions than under glacial conditions. 相似文献
6.
Yoichi Fukuda Toshihiro Higashi Shuzo Takemoto Maiko Abe Sjafra Dwipa Dendi Surya Kusuma Achmad Andan Koichiro Doi Yuichi Imanishi Giuseppe Arduino 《Journal of Geodynamics》2004,38(3-5):489
For the purposes of the calibration of the superconducting gravimeter (SG) in Bandung and the establishment of the absolute gravity (AG) points, we carried out AG measurements for the first time in Indonesia in November 2002. The measurements in Bandung were conducted between November 15th and 20th by means of a FG5 (#210), and 14,520 effective drops were obtained. The gravity value newly determined at the AG point in Bandung is 977976701.2 μgal (1 μgal = 10−8 ms−2) and the scale factor for the SG is −52.22 μgal/V. We also established another AG point in Yogyakarta near Merapi volcano and carried out AG measurements in Yogyakarta between November 22nd and 26th. The gravity value determined for this station is 978203093.5 μgal. 相似文献
7.
Takeshi Kuramochi Jusen Asuka Hanna Fekete Kentaro Tamura Niklas Höhne 《Climate Policy》2016,16(8):1029-1047
This article assesses Japan's carbon budgets up to 2100 in the global efforts to achieve the 2?°C target under different effort-sharing approaches based on long-term GHG mitigation scenarios published in 13 studies. The article also presents exemplary emission trajectories for Japan to stay within the calculated budget.The literature data allow for an in-depth analysis of four effort-sharing categories. For a 450?ppm CO2e stabilization level, the remaining carbon budgets for 2014–2100 were negative for the effort-sharing category that emphasizes historical responsibility and capability. For the other three, including the reference ‘Cost-effectiveness’ category, which showed the highest budget range among all categories, the calculated remaining budgets (20th and 80th percentile ranges) would run out in 21–29 years if the current emission levels were to continue. A 550?ppm CO2e stabilization level increases the budgets by 6–17 years-equivalent of the current emissions, depending on the effort-sharing category. Exemplary emissions trajectories staying within the calculated budgets were also analysed for ‘Equality’, ‘Staged’ and ‘Cost-effectiveness’ categories. For a 450?ppm CO2e stabilization level, Japan's GHG emissions would need to phase out sometime between 2045 and 2080, and the emission reductions in 2030 would be at least 16–29% below 1990 levels even for the most lenient ‘Cost-effectiveness’ category, and 29–36% for the ‘Equality’ category. The start year for accelerated emissions reductions and the emissions convergence level in the long term have major impact on the emissions reduction rates that need to be achieved, particularly in the case of smaller budgets.Policy relevanceIn previous climate mitigation target formulation processes for 2020 and 2030 in Japan, neither equity principles nor long-term management of cumulative GHG emissions was at the centre of discussion. This article quantitatively assesses how much more GHGs Japan can emit by 2100 to achieve the 2?°C target in light of different effort-sharing approaches, and how Japan's GHG emissions can be managed up to 2100. The long-term implications of recent energy policy developments following the Fukushima nuclear disaster for the calculated carbon budgets are also discussed. 相似文献
8.
This work presents the results of geochemical (LA-ICP-MS) study of minerals of peridotites from ophiolite complexes of the Polar Urals to clarify the nature of these formations. The distribution of trace and rare earth elements in clinopyroxenes testifies that there were three types of the mantle substratum, which formed in different geodynamic settings. Two types of primary peridotites were formed upon partial melting of the mantle at different-depth levels in the subduction zone. The first type is represented by lherzolites and diopside harzburgites, formed at partial melting under the spinel facies conditions; the second type is represented by diopside harzburgites, formed under polybaric partial melting under the garnet and spinel facies conditions. In the suprasubduction zone, peridotites experienced fluid-induced partial melting that resulted in crystallization of harzburgites. All types of harzburgites were transformed by ascending melts and fluids (refertilization) and high-temperature hydration with the formation of amphibole. These processes are recorded in variations in the REE spectra of minerals. 相似文献
9.
Kosuke Tamura Dustin T. Duncan Jessica Athens Marc Scott Michael RientiJr. Jared Aldstadt Laurie M. Brotman Brian Elbel 《GeoJournal》2018,83(4):775-782
Sedentary behavior and lack of physical activity are key modifiable behavioral risk factors for chronic health problems, such as obesity and diabetes. Little is known about how sedentary behavior and physical activity among adolescents spatially cluster. The objective was to detect spatial clustering of sedentary behavior and physical activity among Boston adolescents. Data were used from the 2008 Boston Youth Survey Geospatial Dataset, a sample of public high school students who responded to a sedentary behavior and physical activity questionnaire. Four binary variables were created: (1) TV watching (>2 h/day), (2) video games (>2 h/day), (3) total screen time (>2 h/day); and (4) 20 min/day of physical activity (≥5 days/week). A spatial scan statistic was utilized to detect clustering of sedentary behavior and physical activity. One statistically significant cluster of TV watching emerged among Boston adolescents in the unadjusted model. Students inside the cluster were more than twice as likely to report >2 h/day of TV watching compared to respondents outside the cluster. No significant clusters of sedentary behavior and physical activity emerged. Findings suggest that TV watching is spatially clustered among Boston adolescents. Such findings may serve to inform public health policy-makers by identifying specific locations in Boston that could provide opportunities for policy intervention. Future research should examine what is linked to the clusters, such as neighborhood environments and network effects. 相似文献
10.
Natural Hazards - Foreigners tend to be vulnerable to disasters due to religious and cultural differences. In Japan, Muslim foreign residents, who are minorities, likely face difficulties in terms... 相似文献