A technique for modeling transport/conversion processes applied to smectite-to-illite conversion in HLW buffers   总被引：3，自引：0，他引：3  

Harald Hökmark  Ola Karnland  Roland Pusch 《Engineering Geology》1997,47(4):10-378

This paper describes an application of a technique developed for modeling chemical processes in buffer materials that are controlled by a reaction rate and by the transport of one component, which is essential for the process in question to occur. The application described here is the illitization of smectite by fixation of potassium ions in cation exchange positions, and with diffusion of dissolved potassium being the transport process. The technique is verified by comparison with analytical solutions. An overview, based on small models, is given which outlines under what constellations of assumptions the time scale for conversion of the buffer is controlled by reaction rate parameters and under which conditions transport controls this time scale. Examples are given of calculations performed for deposition holes, with potassium being supplied from the surroundings to the upper parts of the highly compacted bentonite buffer. It is concluded that restrictions in nearfield transport capacity have a very significant effect on the conversion time scale. Towards the end of the heating period about 98% of the smectite is found to remain, even for reaction rates and buffer transport conditions that would have left only 10% of the smectite unconverted without nearfield transport restrictions. It is also concluded that the modeling technique can be applied to other, similar, transport/conversion processes.  相似文献   

Estimating groundwater recharge in a cold desert environment in northern China using chloride   总被引：4，自引：0，他引：4  

John B. Gates  W. M. Edmunds  Jinzhu Ma  Bridget R. Scanlon 《Hydrogeology Journal》2008,16(5):893-910

Understanding sources and rates of recharge to the Badain Jaran Desert in northern China is important for assessing sustainability of the area’s oasis lake ecosystem and its water resources in general. For this purpose, direct recharge was investigated with the chloride mass balance method for 18 unsaturated zone profiles (6–16 m depth). Spatial variability is low across the area (range in mean Cl in profiles: 62–164 mg/L Cl), largely attributable to the uniformity of sandy unsaturated zone conditions. No strong correlations between environmental factors of profile locations and recharge rates were found, though a weak relationship between recharge and vegetation density was suggested. The study area’s complex dune morphology appears to have no measurable impact on recharge variability. Mean estimated diffuse recharge is 1.4 mm/year (1.0–3.6 mm/year for 95% confidence level), approximately 1.7% of mean annual precipitation. Temporal fluctuations in recharge due to climate variability are apparent and there is good correspondence in temporal trends over a time span of 200–300 years. Water balance considerations indicate that direct recharge is insufficient to support the numerous perennial lakes in the study area, suggesting that diffuse recharge presently plays a minor role in the overall water balance of the desert’s shallow Quaternary aquifer.  相似文献   

碘酸钾的电化学制法的研究   总被引：1，自引：0，他引：1       下载免费PDF全文

林文修  阮丽琴 《盐湖研究》1998,6(4):34-40

研究以碘和氢氧化钾为原料,应用电化学方法制备碘酸钾的最佳条件,并与氯酸钾氧化法对照。实验指出,电比学法优于氯酸钾氧化法。无隔膜的条件下,电解液的最佳配方为：碘200g／L,氢氧化钾85g／L,重铬酸钾2g／L。最佳操作条件为：阳极Pb—PbO2,阴极不锈钢电极,电流密度Dk=25A／dm2,温度50—60℃,电解时间6小时,在该条件下碘酸钾的产率89．7％,电流效率98％,产品纯度99．2％。  相似文献   

Rate of strontium sorption and the effects of variable aqueous concentrations of sodium and potassium on strontium distribution coefficients of a surficial sediment at the Idaho National Engineering Laboratory, Idaho   总被引：1，自引：0，他引：1  

R. L. Bunde  J. J. Rosentreter  M. J. Liszewski 《Environmental Geology》1998,34(2-3):135-142

 The rate of strontium sorption and the effects of variable aqueous concentrations of sodium and potassium on strontium sorption were measured as part of an investigation to determine strontium chemical transport properties of a surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. Batch experimental techniques were used to determine the rate of strontium sorption and strontium distribution coefficients (K_ds) between aqueous and solid phases. Rate experiments indicate that strontium in solution reached an apparent equilibrium with the sediment in 26 h. K_ds were derived using the linear isotherm model at initial sodium concentrations from 100 to 5,000 mg/l and initial potassium concentrations from 2 to 150 mg/l. K_ds ranged from 56±2 to 62±3 ml/g at initial aqueous concentrations of sodium and potassium equal to or less than 300 and 150 mg/l, respectively. K_ds ranged from 4.7±0.2 to 19±1 ml/g with initial aqueous concentrations of sodium between 1,000 and 5,000 mg/l. These data indicate that sodium concentrations greater than 300 mg/l in wastewater increase the availability of strontium for transport beneath waste disposal ponds at the INEL by decreasing strontium sorption on the surficial sediment. Wastewater concentrations of sodium and potassium less than 300 and 150 mg/l, respectively, have little effect on the availability of strontium for transport. Received: 6 February 1997 · Accepted: 31 March 1997  相似文献   

东秦岭—大别山铀钍钾空间分布与铀矿化   总被引：2，自引：0，他引：2  

郑秉钧 《铀矿地质》1990,6(1):26-33

本文在综合分析东秦岭—大别山航空伽玛能谱资料的基础上,结合区域地质特征,探讨本区铀、钍、钾元素的空间分布与铀矿化的关系。  相似文献   

马海盐湖低品位固体钾矿溶解开采方法初步探讨   总被引：2，自引：2，他引：2       下载免费PDF全文

王有德 《盐湖研究》2006,14(1):24-28

马海盐湖经地质勘查提交的KCl品位在8%以下的固体钾矿达486.73×104t,相当于一个中型钾镁盐矿的规模,对于这部分资源目前尚未得到利用。我国从上世纪90年代后期在盐湖矿产的开发中运用溶解采矿的方法,取得了显著的成效。文章主要通过与察尔汗盐湖的对比研究,认为对马海盐湖低品位固体钾矿完全可以进行水溶开采,并就水溶开采的必要性及其可行性进行了论述,对水溶开采的方法进行了初步的探讨。综合分析马海钾矿区的地质条件,包括固体钾矿的分布、厚度、品位以及埋藏深度等,从溶矿的效果和成本对比考虑,提出在矿区低品位固体钾矿厚度较小的东部进行沟渠式溶矿,在低品位固体钾矿厚度较大的西部进行井—渠结合式溶矿,在整个钾矿区根据固体钾矿层埋藏深度选用沟渠溶采和井—渠溶采相结合的溶矿方案,最后指出了溶解开采需要注意的几个方面的问题,这对于马海盐湖低品位固体钾矿进行工业化水溶开采具有重要的参考意义。  相似文献   

Correlations of foliar Δ with K concentration and ash content in sand-fixing plants in the Tengger Desert of China: patterns and implications     

Liangju Zhao  Honglang Xiao  Xiaohong Liu  Ren Juan  Lu Mingfeng  Zhou Maoxian 《Environmental Geology》2007,51(6):1049-1056

In different-aged sand-fixing zones and shifting sand dunes, the seasonal variations of foliar carbon isotope discrimination (Δ), potassium (K) concentration and ash content were investigated in three dominated deserted plants (Artemisia ordosica, Hedysarum scoparium and Caragana korshinskii) during growth season in Shapotou, which is in the southeast margin of the Tengger Desert. The correlations of foliar Δ with foliar K concentration and ash content were examined to evaluate the foliar K and ash content as surrogates of Δ in those deserted plants. Results showed that there were significant effects of plant species, micro-habitation and growth season on foliar Δ, K concentration and ash content. Foliar Δ of C. korshinskii was significantly lower than those of A. ordosica and H. scoparium, and K concentrations in A. ordosica were 2.14 and 2.36 times those of C. korshinskii and H. scoparium. At the same time, micro-habitation and the conditions in growth seasons had significant effects on foliar Δ, K concentration and ash content. Ash content and K concentration were positively correlated to Δ in A. ordosica and H. scoparium, while there was significantly negative relationship between foliar K concentration and Δ in C. korshinskii. Thus, those findings suggest that foliar ash content and K concentration can serve as surrogates of carbon isotope discrimination (Δ) in A. ordosica and H. scoparium, while they do not in C. korshinskii. This result implied that the correlations of foliar Δ with ash content and K concentration were various due to the physiological features of plant species, and species differences should be fully considered when evaluating the surrogates of carbon isotope discrimination in plants.  相似文献   

303 K时KI在CH3OH-H2O混合溶剂中活度系数研究          下载免费PDF全文

王芳  杨美芳 《盐湖研究》2007,15(3):14-18

用电动势法测定了KI在甲醇含量为0%、20%、60%、100%的甲醇-水混合溶剂中的电动势,用幂级数展开方法、扩展的Debye-Hückel方程及Pitzer方程关联不同溶剂组成下电动势的实验值,得到电池的标准电动势E°和KI在混合溶剂中的活度系数。结果表明,在一定的溶剂比例下,KI的平均活度系数先随它的浓度增加而下降,经过一个最低点后上升,或者随浓度增加而单调递减。当KI浓度固定时,它的平均活度系数随溶剂中甲醇的含量增加而下降,表明KI在甲醇中有微弱的缔合。  相似文献   

Treatment of a Trifluraline Effluent by Means of Oxidation‐Coagulation with Fe(VI) and Combined Fenton Processes     

Ayrton F. Martins  Carla da S. Frank  Marcelo L. Wilde 《洁净——土壤、空气、水》2007,35(1):88-99

The amination water (AW) effluent stream from the industrial production of the trifluraline herbicide was submitted to an oxidation‐coagulation treatment with potassium ferrate, combined with advanced oxidation processes. The experimental results obtained by analysis of variance (ANOVA) for the oxidation‐coagulation‐Fenton process, evaluating the variables pH (A), Fe(VI) concentration (B), and H₂O₂ concentration (C), demonstrated that the regression equation resulting from the Response Surface Methodology (RSM) experimental design, for the quadratic model, was η_Abs (%) = 36.9– 21.58A + 8.37A² + 1.36B + 0.92B² + 1.08C + 1.52C² + 1.27AB – 1.34AC + 1.33BC. The maximum absorptiometric color reduction occurred at pH 3, with corresponding maximum amounts of iron and hydrogen peroxide. The absorptiometric color and COD reduction were 96% and 57%, respectively. For the oxidation‐coagulation‐photo‐Fenton process, the analyzed variables were pH (A), Fe(VI) concentration (B), H₂O₂ concentration (C), and temperature (D). The regression equation resulting from the quadratic model was η_Abs (%) = 38.3 – 20.2A + 8.12A² – 0.27B + 3.73B² + 0.3C + 3.6C² + 1.67D + 3.1D² + 1.72AB + 0.51AC – 1.82AD + 0.74BC – 1.11BD + 0.03CD. The ANOVA response showed that the highest absorptiometric color reduction occurred at pH 3, with respective maximum amounts of iron and hydrogen peroxide at 60°C. The maximum efficiencies achieved by the proposed treatment process for the trifluraline effluent stream were 95% and 85%, for absorptiometric color and COD reduction, respectively.  相似文献   

Using remote sensing to regionalize local precipitation recharge rates obtained from the Chloride Method   总被引：4，自引：0，他引：4  

Philip Brunner  Peter Bauer  Martin Eugster  Wolfgang Kinzelbach 《Journal of Hydrology》2004,294(4):241-250

Water supply in semiarid Botswana is, to a large extent, based on groundwater. In the planning of a groundwater abstraction scheme, criteria for the sustainability of the abstraction with respect to both quantity and quality have to be satisfied. The most important parameter in the context of quantitative sustainability is the long-term average groundwater recharge together with its spatial distribution. A method is developed to calculate a recharge map that can be used in a groundwater model. The relative distribution of recharge is obtained from remotely sensed data and then calibrated with local values of recharge derived from the Chloride Method. The method was tested for two sites in Botswana, the Chobe Region and Ngamiland.  相似文献