三元体系K2B4O7-KBr-H2O在323K的相平衡研究          下载免费PDF全文

赵向阳  桑世华  孙明亮 《盐湖研究》2011,19(1):35-39

采用等温溶解平衡法研究了三元体系K2B4O7-KBr-H2O在323 K的相平衡关系及密度。研究发现,该三元体系为简单共饱和型,无复盐及固溶体形成。根据溶解度数据绘制了相图,相图中有一个共饱点,两条单变曲线,单变量曲线所对应的平衡固相分别为K2B4O7.4H2O和KBr;实验结果表明KBr对K2B4O7有较强的盐析作用。并简要讨论了密度变化规律。  相似文献   

硫酸铵溶液淋滤-电感耦合等离子体质谱测定离子相稀土分量的方法优化   总被引：2，自引：2，他引：0  

张磊  周伟  朱云  屈文俊  樊兴涛  李迎春 《岩矿测试》2018,37(5):518-525

离子吸附型稀土中离子相稀土的准确测定对稀土矿体资源评价具有重要意义。离子相稀土以羟基或水合羟基的形式吸附在黏土矿物上,可与强电解质(Mg~(2+)、NH_4~+等)交换解吸进入溶液。前人以硫酸铵为淋滤液,实现了离子相稀土的解吸、提取,但在溶液浓度、浸取过程等方面选择各异,淋滤浸取率(60%～90%)差异大,未形成高效、统一的浸取方法,不利于离子相稀土元素的精确测定。本文通过对比实验规范了硫酸铵淋滤离子相稀土的各项淋滤参数(固液比、硫酸铵浓度、样品最佳称样量、浸泡时间),减少了淋滤过程中离子相稀土的损失,浸取率达到88%～98%,进而利用ICP-MS测定离子相稀土分量。方法检出限为0. 05～5. 11 ng/g;三类岩性离子吸附型稀土样品的精密度为:火山岩1. 80%～10. 01%,变质岩1. 06%～7. 27%,沉积岩1. 72%～7. 58%。协作实验室的分析结果验证了本方法的可靠性和准确性。本方法操作简便,分析效率高,为建立相关的行业标准乃至国家标准奠定了基础。  相似文献   

Seasonal and interannual variations of nitrate and chloride in stream waters related to spatial and temporal patterns of groundwater concentrations in agricultural catchments     

C. Martin  L. Aquilina  C. Gascuel‐Odoux  J. Molnat  M. Faucheux  L. Ruiz 《水文研究》2004,18(7):1237-1254

Nitrate concentrations in streamwater of agricultural catchments often exhibit interannual variations, which are supposed to result from land‐use changes, as well as seasonal variations mainly explained by the effect of hydrological and biogeochemical cycles. In catchments on impervious bedrock, seasonal variations of nitrate concentrations in streamwater are usually characterized by higher nitrate concentrations in winter than in summer. However, intermediate or inverse cycles with higher concentrations in summer are sometimes observed. An experimental study was carried out to assess the mechanisms that determine the seasonal cycles of streamwater nitrate concentrations in intensive agricultural catchments. Temporal and spatial patterns of groundwater concentrations were investigated in two adjacent catchments located in south‐western Brittany (France), characterized by different seasonal variations of streamwater nitrate concentrations. Wells were drilled across the hillslope at depths ranging from 1·5 to 20 m. Dynamics of the water table were monitored and the groundwater nitrate and chloride concentrations were measured weekly over 2 years. Results highlighted that groundwater was partitioned into downslope domains, where denitrification induced lower nitrate concentrations than into mid‐slope and upslope domains. For one catchment, high subsurface flow with high nitrate concentrations during high water periods and active denitrification during low water periods explained the higher streamwater nitrate concentrations in winter than in summer. For the other catchment, the high contribution of groundwater with high nitrate concentrations smoothed or inverted this trend. Increasing bromide/chloride ratio and nitrate concentrations with depth argued for an effect of past agricultural pressure on this catchment. The relative contribution of flows in time and correlatively the spatial origin of waters, function of the depth and the location on the hillslope, and their chemical characteristics control seasonal cycles of streamwater nitrate concentrations and can influence their interannual trends. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

The diffusive fluxes of inorganic nitrogen across the intertidal sediment-water interface of the Changjiang Estuary in China     

HOU Lijun  LIU Min  XU Shiyuan  LU Jianjian  OU Dongni  YU Jie 《海洋学报(英文版)》2006,25(3):48-57

1IntroductionEstuaries are the main channels linking bothland and coastal seas,through which pass matterleached from land into rivers,together with anthro-pogenic matter discharged directly into the estuaries.During the past few decades,increasing concern…  相似文献   

Leaching of rock-concrete interfaces   总被引：1，自引：1，他引：0  

O. Buzzi  M. Boulon  M. Hervé  K. Su 《Rock Mechanics and Rock Engineering》2008,41(3):445-466

Summary  It has been shown that contacts between host rock and engineered barriers may be critical in the design of deep radioactive waste repositories. Water is expected to reach the interface zone after the resaturation of the geological massive and its presence may lead to concrete leaching. Such a phenomenon could increase the interface transmissivity and compromise the confinement of radioactive waste. This paper intends to investigate the influence of concrete leaching on the hydromechanical behaviour of host rock-concrete interfaces. Some concrete specimens have been subjected to an accelerated leaching process using ammonium nitrate. The hydromechanical response of degraded concrete-rock interfaces has been studied under shearing and compared to that of sound interfaces. Consistent with the results available in the literature on bulk concrete, a loss of mechanical strength has been observed for the degraded interface. Unlike the sound specimens, the degraded interfaces do not dilate when sheared and they tend to be closed, thereby preventing water from flowing. Correspondence: O. Buzzi, Centre for Geotechnical and Materials Modelling, School of Engineering, University of Newcastle, 2308 Callaghan NSW, Australia  相似文献   

A study of bromide in the Mandovi-Zuari river system of Goa     

Francisca P. de Souza  V.N.Kamat Dalal 《Estuarine, Coastal and Shelf Science》1985,21(4):601-606

Bromide was the subject of detailed investigation in the Mandovi-Zuari river system and information was compiled on its spatial and temporal distribution. A simple mixture relation of Carpenter et al. was applied and seawater percentage and bromide concentrations were computed. The variation of bromide with chlorinity was linear indicating the purely conservative character of bromide and its seawater origin. Seawater ranged between 1 and 3% in monsoon, 76 and 91% in post-monsoon and 92 and 97% in pre-monsoon in the Mandovi-Zuari river system. As the bromide concentration varied linearly with chlorinity both longitudinally and depthwise, it followed that bromide exhibited a simple distribution pattern established by conservative mixing.  相似文献   

AMMONIUM UPTAKE AND REGENERATION FLUXES OF THE MICROPLANKTON COMMUNITIES IN JIAOZHOU BAY   总被引：3，自引：0，他引：3  

焦念志  王荣 《中国海洋湖沼学报》1994,12(2):165-174

The results from four cruises(Nov.1991—Jul.1992)to examine fluxes of ammonium uptake andregeneration in the surface layer of Jiaozhou Bay are presented.Seasonal variations of the two fluxeswere in the order:summer>spring>autumn>winter.Diel patterns were characterized by higher uptake inthe daytime and higher regeneration at night.Averaged uptake and regeneration fluxes on an annual scalewere 0.073 and 0.053 μmol·L~(-1)·h~(-1)respectively.Regeneration fluxes were always less than uptakefluxes throughout the year.The longest turnover time was 16.34 d(in winter),and the shortest one was0.68 d(in summer).The major uptake flux was contributed by the smallest fraction-picoplankton.Theextents of light-dependence of ammouium uptake by different size fractions were in the order:netplankton>nanoplankton>picoplankton..  相似文献   

硫酸亚铁铵氧化还原滴定法测定钠硝石中硝酸根的含量     

彭玉玲  唐妙红 《岩矿测试》2007,26(2):165-166

试样用盐酸分解，硫酸亚铁铵将硝酸根还原为氧化氮，用重铬酸钾标准溶液滴定剩余二价铁。由消耗硫酸亚铁铵的量换算成硝酸根含量。对盐酸的用量、样品的煮沸时间进行了试验。对实际钠硝石样品重复测定8次．方法的精密度（RSD）为0．73％～2．00％，加标回收率为99．0％～101．0％。方法适用于钠硝石矿石中1％以上的硝酸根测定。  相似文献   

Kinetic investigation of the OH + CH3Br reaction between 248 and 390 K     

A. Chichinin  S. Teton  G. Le Bras  G. Poulet 《Journal of Atmospheric Chemistry》1994,18(3):239-245

The rate parameters for the reaction of the OH radical with CH₃Br have been measured using the discharge flow-electron paramagnetic resonance method. The result isk ₁=(1.86±0.48)×10^–12 exp[–(1230±150)/T] cm³ molecule^–1 s^–1. This value is compared to earlier data and is found to be in excellent agreement with the most recent results, which greatly increases the accuracy of the ozone depletion potential of CH₃Br which can be derived from these kinetic data.  相似文献   

ON THE ROLE OF SULFATE ION IN THE ATMOSPHERE          下载免费PDF全文

J. Rosinski  C. T. Nagamoto 《Acta Meteorologica Sinica》1994,8(4):498-504

Drop freezing experiments with ammonium sulfate water solutions have shown the existence of the temperature maxima that are a function of the salt concentration.The maxima were:-12℃ for 10^-4 M solution on filter,-9℃ for 10^-4 to 10^-3M solution in contact with particles of continental origin,and-4℃ for 10^-4 M solution in contact with particles of marine origin.It was speculated that the presence of ice-forming nuclei active at high temperature(-4℃） should extend the formation of ice in clouds toward lower latitudes,increase their albedos,and provide additional cooling during daytime for the earth.The microphysics of clouds must be included in studying climate.  相似文献