合成磷灰石的去氟机理研究          下载免费PDF全文

黄志良  刘羽  王大伟  张术根  陈露军 《岩石矿物学杂志》2001,20(4):568-572

用固相反应法和sol-gel法合成了不同类型的磷灰石（AP），并采用TEM、XRD、IR、BET比表面积法及静、动态吸附等方法研究了不同AP的比表面积、结晶度、晶胞参数、结晶尺寸、晶格缺陷度、Ca/P摩尔比和煅烧温度等与吸氟能力的关系，结果表明：结晶度高、晶粒大的AP有较小的吸氟量，属表面单分子层化学络合吸附机理；酸活化的AP有较大的吸氟量，属溶解-沉淀与沉淀物表面纳米尺寸效应吸附的复合去氟机理；具纳米尺寸的HAP在常温、常压、无二次污染、小于11mg/L的低含氟浓度废水中且不酸化情况下有较大吸氟量，属纳米尺寸效应吸附机理。  相似文献   

高温铀物种形成(Speciation)的热力学数据     

黄克玲  周鲁民  张景廉 《铀矿地质》1993,(6)

本文依据C.M.Criss和J.W.Cobble的“离子熵对应原理”,对1978年D.Langmuir给出的铀物种形成常温热力学数据进行了高温值的处理,得出了一套较全面而系统的高温热力学参数,以供参考使用。  相似文献   

Silicate and carbonate weathering in the drainage basins of the Ganga-Ghaghara-Indus head waters: Contributions to major ion and Sr isotope geochemistry   总被引：1，自引：0，他引：1  

S. Krishnaswami  Sunil K. Singh 《Journal of Earth System Science》1998,107(4):283-291

The role of silicate and carbonate weathering in contributing to the major cation and Sr isotope geochemistry of the headwaters of the Ganga-Ghaghara-Indus system is investigated from the available data. The contributions from silicate weathering are determined from the composition of granites/ gneisses, soil profiles developed from them and from the chemistry of rivers flowing predominantly through silicate terrains. The chemistry of Precambrian carbonate outcrops of the Lesser Himalaya provided the data base to assess the supply from carbonate weathering. Mass balance calculations indicate that on an average ∼ 77% (Na + K) and ∼ 17% (Ca + Mg) in these rivers is of silicate origin. The silicate Sr component in these waters average ∼40% and in most cases it exceeds the carbonate Sr. The observations that (i) the⁸⁷Sr/⁸⁶Sr and Sr/Ca in the granites/gneisses bracket the values measured in the head waters; (ii) there is a strong positive correlation between⁸⁷Sr/⁸⁶Sr of the rivers and the silicate derived cations in them, suggest that silicate weathering is a major source for the highly radiogenic Sr isotope composition of these source waters. The generally low⁸⁷Sr/⁸⁶Sr (< 0.720) and Sr/Ca (∼ 0.2 nM/ μM) in the Precambrian carbonate outcrops rules them out as a major source of Sr and⁸⁷Sr/⁸⁶Sr in the headwaters on a basin-wide scale, however, the high⁸⁷Sr/⁸⁶Sr (∼ 0.85) in a few of these carbonates suggests that they can be important for particular streams. The analysis of⁸⁷Sr/⁸⁶Sr and Ca/Sr data of the source waters show that they diverge from a low⁸⁷Sr/⁸⁶Sr and low Ca/Sr end member. The high Ca/Sr of the Precambrian carbonates precludes them from being this end member, other possible candidates being Tethyan carbonates and Sr rich evaporite phases such as gypsum and celestite. The results of this study should find application in estimating the present-day silicate and carbonate weathering rates in the Himalaya and associated CO₂ consumption rates and their global significance.  相似文献   

Grigg-Skjellerup彗星新生离子激发低频电磁波性质          下载免费PDF全文

曹晋滨 《地球物理学报》1998,41(5):601-608

本文运用磁场的最小方差分析法和磁场-电子密度的相关分析法分析了欧洲空间局Giotto飞船对P／Grigg-Skjellerup（简称G-S）彗星弓激波附近磁场和电子能流的部分观测数据．结果表明彗星附近存在大量的频率靠近新生水族离子回旋频率的波动,它们是由彗星新生水族离子环流激发的低频左旋电磁波．波在近似平行于磁场方向传播,斜传播角小于15°．电子数据和磁场数据相关分析表明即使在离彗星很远的地方仍然存在压缩波．  相似文献   

Time fluctuations of small ion number density in the atmospheric surface layer     

Sven Israelsson 《Pure and Applied Geophysics》1977,115(3):561-574

The standard deviations and time-spectra of small ion number density have been measured at ground level under different atmospheric stability conditions. The auto-correlation correlograms and the time-spectra imply a scale of fluctuations corresponding to 1 to 4 min. No clear relationships between standard deviations of small ion number density and micro-meteorological parameters are observed. Thus the results are not a support for Monin-Obukhov similarity theory. For the highest frequencies the slopes of the spectra seem to follow the –5/3-law fairly well and the frequencies of the peak values of individual spectra lnfS(f) increase when the atmosphere stability increases, which is valid for ordinary micrometeorological parameters.  相似文献   

Spatial and seasonal variation of major ions in Himalayan snow and ice: A source consideration   总被引：2，自引：0，他引：2  

Ya-ping Liu  Zhi-xing Geng  Shu-gui Hou   《Journal of Asian Earth Sciences》2010,37(2):195-205

The spatial and temporal variation of major ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, , , and Cl⁻) in Himalayan snow and ice is investigated by using two snow pits from the East Rongbuk glacier (28°01′N, 86°58′E, 6500 m a.s.l.), one snow pit from the Nangpai Gosum glacier (28°03′N, 86°39′E, 5700 m a.s.l.), one snow pit from the Gyabrag glacier (28°11′N, 86°38′E, 6303 m a.s.l.), and three ice cores from the Sentik (35°59′N, 75°58′E, 4908 m a.s.l.), Dasuopu (28°33′N, 85°44′E, 7000 m a.s.l.), and East Rongbuk (27°59′N, 86°55′E, 6450 m a.s.l.) glaciers, respectively. In general, the major ions show a significant seasonal variation, with high concentrations during the non-monsoon (pre-monsoon and post-monsoon) season and relatively low concentrations during the monsoon season. Monsoon precipitation with high local/regional dust loading related to summer circulation is possibly responsible for the high concentrations occurring sporadically during the monsoon season. The crest of the Himalayas is an effective barrier to the spatial distribution of Na⁺, Cl⁻ and concentrations, but not to the major ions associated with dust influx (e.g. Ca²⁺ and Mg²⁺). Atmospheric backward trajectories from the HYSPLIT_4 model used in identifying chemical species sourcing suggest that the major ions in the Himalayan snow and ice come mainly from the Thar Desert located in the North India, as well as West Asia, or even the distant Sahara Desert in the North Africa during the winter and spring seasons. This is different from the conventionally assumed arid and semi-arid regions of the central Asia. Factors, such as different vapor sources due to atmospheric circulation patterns and geographical features (e.g. altitude, topography), may contribute to the differences in major ionic concentrations between the western and eastern Himalayas.  相似文献   

Real-Time Observation on Water-Soluble Ions of PM_(2.5)in Beijing under the Influences of Different Air Masses in Summer          下载免费PDF全文

CHENG Meng-Tian  SUN Yang  ZHU Xiao-Wan  CHAO Na 《大气和海洋科学快报》2014,(1)

To further understand the variations of water-soluble ions in PM2.5 in Beijing,the authors observed their concentrations continuously and in high temporal resolution by the system for rapid collection of fine particles and ion chromatography(RCFP-IC) during 12–18 July 2010.These results combined with those of earlier backward trajectory research are used analyzed to determine the causes of concentration changes in water-soluble ions under the influences of two kinds of air masses in summer.The results indicate that concentrations of NO3-,SO42-,and NH4+ were influenced strongly by the continental air mass than by the marine air mass.Cl- and Na+ were not changed significantly.Because the sources of K+,Mg2+,and Ca2+ are mainly concentrated on land,their concentration levels were slightly higher under the control of continental air mass than that of the marine air mass.Variations of NO2- during the observation differed from those of other ions;its concentration was significantly higher under the influence of marine air mass.Moreover,the authors obtain the diurnal variations of eight water-soluble inorganic ions including NH4+,K+,Mg2+,Ca2+,Cl-,NO2-,NO3-,and SO42-.Diurnal variations of NH4+,NO3-,and Cl- showed single peak,which appeared before noon,while SO42- showed two peaks that appeared during rush hours.Those of Mg2+,Ca2+,and K+ showed single peak that appeared in the afternoon.That of NO2- showed with a peak appearing at sunrise and a valley appearing at sunset.  相似文献   

Spectrum characteristics of major ion concentrations at Wuhan sectoin of the Changjiang Rriver     

Xing-hui Xia  Jing-sheng Chen  Xu-yi Cai 《中国地理科学(英文版)》2001,11(4):315-320

Spectrum analyses of water quality time series have been carried out for five hydrometric stations including Wuhan hydrometric station of the Changjiang(Yangtze) River, etc. The fluctuations of Ca²⁺, Mg²⁺ and HCO ₃ ⁻ concentrations in river water under different physical geography conditions have about two-year cycle which is corresponding to hydrometeorological quasi-biannual-oscillation (QBO). Na⁺, Cl⁻ SO ₄ ²⁻ have about two-year cycle in the area lightly affected by human activities while two-year cycle doesn’t exist in the area heavily affected by human activities. All the fluctuations of major ions have about three-month cycle. The river diseharge fluctuation accounts for 43.9%, 45.1%, 54.3%, 33.9%, 30.3% and 42.7% of the variance of Ca²⁺, Mg²⁺, HCO ₃ ⁻ , Na⁺, Cl⁻, SO ₄ ²⁻ , respectively, at Wuhan from 1962 to 1985. According to the spectrum characteristic of major ions, the duration of the time series has to be at least 13 years for trend analysis of monthly water quality data. Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 49671017). Biography: XIA Xing-hui(1971-), female, a native of Hunan Province, Ph. D. Her research interest includes environmental chemistry.  相似文献   

Sources of Inaccuracy in Boron Isotope Measurement Using LA-MC-ICP-MS     

Jan Fietzke  Eleni Anagnostou 《Geostandards and Geoanalytical Research》2023,47(3):481-492

Laser ablation multi-collector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) has become a valuable tool for the in situ measurement of the boron isotope composition of geological samples at high (tens to hundreds of μm) spatial resolution. That said, this application suffers from significant analytical challenges. We focus in this study on the underlying processes of two of the main causes for inaccuracies using this technique. We provide empirical evidence that not only Ca ions (Sadekov et al. 2019, Standish et al. 2019, Evans et al. 2021) but also Ar ions, that are reflected within the flight tube of the mass spectrometer, are the source for previously reported issues with spectral baselines. We also address the impact of plasma conditions on the instrumental mass fractionation as a source for matrix- and mass-load-related analytical biases. Comparing experimental data with the results of a dedicated release and diffusion model (RDM) we estimate that a close to complete (~ 97%) release of boron from the sample aerosol is needed to allow for consistently accurate LA boron isotope measurement results without the need for corrections.  相似文献   

Optical Spectroscopy of Comet C/2000 WM1 (LINEAR) at the Guillermo Harro Astrophysical Observatory in Mexico     

Churyumov  Klim I.  Luk'yanyk  Igor V.  Berezhnoi  Alexei A.  Chavushyan  Vahram H.  Sandoval  Lourdes S.  Palma  Alejandro A. 《Earth, Moon, and Planets》2002,90(1-4):361-368

We present a preliminary analysis of medium resolution optical spectra of comet C/2000 WM1 (LINEAR) obtained on 22 November 2001. Theemission lines of the molecules C₂, C₃, CN, NH₂,H₂O⁺ and presumably CO (Asundi and triplet bands) and C₂ ^-were identified in these spectra. By analysing the brightnessdistributions of the C₂, C₃, CN emission lines along theslit of the spectrograph we determined some physical parameters of theseneutrals, such as their lifetimes and expansion velocities inthe coma. The Franck–Condon factors for the CO Asundi bands and C₂ ^- bands were calculated using a Morse potential model.  相似文献