降水性层状云微物理结构个例分析   总被引：13，自引：3，他引：13  

李淑日  王广河  刘卫国 《气象》2001,27(11):17-21

对2000年4月14日河南省一次降水性层状云系进行了飞机探测。利用探测所取得的微物理资料，配合同期的天气、卫星、雷达等资料对云的微物理特征进行了分析，讨论了云中液态水含量、云粒子平均直径和粒子谱等的水平和垂直微物理结构特征。  相似文献   

Spatial variability of soil moisture content and its relation to environmental indices in a semi-arid gully catchment of the Loess Plateau, China   总被引：16，自引：0，他引：16  

Yang Qiu  Bojie Fu  Jun Wang  Liding Chen 《Journal of Arid Environments》2001,49(4):723

The degree of spatial variability of soil moisture and the ability of environmental attributes to predict that variability were studied at the Da Nangou catchment (3·5 km²) in the semi-arid loess area of China. Soil moisture measurements were performed biweekly at five depths in the soil profile (0–5 cm, 10–15 cm, 20–25 cm, 40–45 cm and 70–75 cm) from May to October 1998 and from May to September 1999 using Delta-T theta probe. Results indicated that with increasing soil depth, the mean soil moisture content increases significantly for five layers and the coefficients of variation (CV) also increases with depth from 10–15 cm. It was observed that heavier rains and higher mean moisture contents are often associated with lower spatial variability (CV). Environmental attributes such as land use and topography play controlling roles in the spatial distribution of soil moisture content. However, the relative roles of these environmental indices vary with soil depth. The dominant controls on spatial variability of the time-averaged soil moisture changes from land use, aspect, relative elevation and hillslope position in the surface soil (0–5 cm) to relative elevation, hillslope position and aspect in the subsurface soil (10–15 cm, 20–25 cm), and to land use, relative elevation and slope gradient at larger depths (40–45 cm, 70–75 cm). The dynamic behavior of influences of different environmental indices on the layer-averaged soil moisture depends on several factors. In general, the correlation of soil moisture with slope gradient shows a more significant increase following a greater amount of antecedent precipitation (except for the extremely heavy storms), and declines afterwards. The relation of soil moisture with relative elevation and hillslope position exhibits an opposite trend. It was observed that the influence of land use corresponds to the difference in vegetative characteristics, with a stronger influence in June and August with a greater difference in vegetation. A significant influence of cos(aspect) was found during early spring and autumn with a rapid transient in solar irradiation. Finally, it was found that the sample size is adequate to estimate the catchment mean soil moisture at all five depths and on all 10 observations in 1999 (81 sites), while it is only enough for the upper soil layers (0–5 cm and 10–15 cm) in 1998 (26 sites).  相似文献   

Modeling Atmospheric Chemistry: Interactions between Gas-Phase Species and Liquid Cloud/Aerosol Particles     

Rolf Sander 《Surveys in Geophysics》1999,20(1):1-31

For detailed modeling of atmospheric chemistry it is necessary to consider aqueous-phase reactions in cloud droplets and deliquesced aerosol particles. Often, the gas-phase concentration is in equilibrium with the aqueous phase. Then Henrys law can be used to describe the distribution between the phases provided that the Henrys law coefficient is known. In some cases, thermodynamic equilibrium will not be reached and it is necessary to use kinetic expressions of the rates involved. These rates depend on diffusion constants, accommodation coefficients, Henrys law coefficients, particle size distributions, and several other parameters. This review describes how these processes can be treated in computer modeling and how the necessary data can be obtained. Even though it is written primarily for use in modeling atmospheric chemistry, some parts will also be useful for waste water and pesticide control and in other areas where the distribution of chemicals between the aqueous and the gas phase is important.  相似文献   

The Speciation of (CH3)2Sn2+ in Electrolyte Solution Containing the Major Components of Natural Waters     

Claudia Foti  Antonio Gianguzza  Frank J. Millero  Silvio Sammartano 《Aquatic Geochemistry》1999,5(4):381-398

Hydrolysis constants of dimethyltin(IV) cation, in different salt solutions (CaCl₂: 0.15 I 0.90; MgCl₂: 0.30 I 0.60; NaCl-–NaClO₄, NaCl-–NaNO₃ mixtures: I = 3; NaCl-–Na₂SO₄ mixtures: I = 1 mol dm^-3) were determined by potentiometric ([H⁺]-glass electrode) measurements. These data, together with previous data (De Stefano et al., 1996b) were interpreted in terms of DHT (Debye–Hückel type) and Pitzer equations. The mixed electrolyte solution results also allowed us to obtain and parameters for the Pitzer equation. Calorimetric measurements were made at different ionic strengths in order to find the temperature dependence of hydrolysis constants and of the relative interaction parameters. The body of results allows us to determine the speciation of natural waters in a wide range of ionic strengths and temperatures.  相似文献   

Analysis of State and Provincial Atlas Reviews*   总被引：1，自引：0，他引：1  

Diana Hocking  C. Peter Keller 《The Professional geographer》1993,45(1):73-83

Ninety-eight reviews of state and provincial atlases are examined in order to address several questions. Reviews are subjected to content analysis to identify the judgement criteria that experts use in evaluating a provincial or state atlas, and the aspects of each criterion that reviewers praise or condemn. An attempt is made to search for expert consensus and to identify a provincial or state atlas review recipe. The research reported here is part of a larger study undertaken to assist those in the process of planning a new provincial or state atlas initiative. This paper also assists individuals who are searching for rules and guidelines when undertaking an atlas review.  相似文献   

太湖全新世沉积物的古盐度指标及其环境意义   总被引：5，自引：0，他引：5  

王子玉  程安进 《地层学杂志》1994,18(3):196-202

沉积物中的Ｃａ／（Ｆｅ＋Ｃａ）比值和硼含量随水体含盐度的高低而相应增减，它们都是较好的古盐度指标。本文对太湖全新世的沉积物进行了古盐度指标的分析。并与现代湖泊和海洋沉积物作了对比，结果反映东太湖为陆相沉积环境，而西太湖则主要为海相沉积环境。此结论与古生物化石的结论一致，从而证明了太湖地区于全新世期间经历了大规模的海侵，并形成海湾－湖环境。同时也证明了这些古盐度指标是行之有效的。  相似文献   

累托石中晶层含量及规则度测定   总被引：1，自引：0，他引：1       下载免费PDF全文

张荣英 《岩石矿物学杂志》1993,12(3):261-268

本文用直接付里叶交换法测定我国产出的10个累托石样品结构中两类晶层(A云母层、B蒙皂石层)含量(A%、B%)及规则度(Re%)。测定结果表明天然累托石中,A/B不等于1,1.27>A/B>1.01。A%为50.5%—55.8%,B%为44.2%—49.5%;A、B层也不是严格规则交替堆垛,规则度Re%为72%—98.6%。  相似文献   

野外非饱和土壤中溶质运移的试验研究   总被引：9，自引：3，他引：9       下载免费PDF全文

杨金忠  贾锥钊 《水科学进展》1993,4(4):245-252

通过在野外3×6m2面积上均匀入渗条件下非饱和土壤溶质运移试验,同时对8个点定时取样,得到170cm深度内土壤溶液浓度和含水量剖面分布.据此研究了小区域范围内土壤水分和溶质的运移特征,讨论了土壤水分和盐分分布的空间变异性和统计特征.研究结果表明,在本试验条件下,土壤溶液浓度剖面的空间变异性远大于土壤水分剖面.单一测点的取样结果不能代表区域的溶质运移特征.区域上溶质浓度的平均结果能反映溶质运移的基本规律.由于土壤结构等因素的影响,不动水体含量占土壤含水量的24%～39%.  相似文献   

Isotope geochemistry of the Tieluping silver-lead deposit, Henan, China: A case study of orogenic silver-dominated deposits and related tectonic setting   总被引：22，自引：0，他引：22  

Yan-jing Chen  Franco Pirajno  Ying-hui Sui 《Mineralium Deposita》2004,39(5-6):560-575

The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade metamorphic basement of the Xionger Terrane in the Qinling orogenic belt, is part of an important, recently discovered Mesozoic orogenic-type Ag-Pb belt. Ore formation includes three stages: an early barren quartz-pyrite stage (E), an intermediate polymetallic sulfide ore stage (M), and a late barren carbonate stage (L). Carbon, sulfur and lead isotope systematics indicate that the E-stage fluids are deeply sourced; the L-stage fluids are shallow-sourced meteoric water; whereas the M-stage fluids are a mix of deep-sourced and shallow-sourced fluids. Sulfur and lead isotope data show that the ore-forming fluids must have originated from a source with elevated radiogenic lead and low ³⁴S values, that differs significantly from exposed geologic units in the Xionger Terrane, the lower crust and the mantle. This supports the view that the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources, although little is known about their isotopic compositions. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the North China Craton and South China Block (Early-Mid Triassic Indosinian Orogeny), crustal slabs containing the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups, locally rich in organic matter (carbonaceous shale), were thrust northwards beneath the Xionger Terrane along the Machaoying fault. Metamorphic devolatilisation of this underthrust slab probably provided the ore-forming fluids to develop the Ag-Pb ore belt, which includes the Tieluping silver deposit. Fluids and magmas were emplaced during extensional stages related to the Jurassic-Cretaceous Yanshanian Orogeny.Editorial Handling: B. Lehmann  相似文献   

Space group and hydrogen sites of δ-AlOOH and implications for a hypothetical high-pressure form of Mg(OH)<Subscript>2</Subscript>     

Y. ?KudohEmail author  T. ?Kuribayashi  A. ?Suzuki  E. ?Ohtani  T. ?Kamada 《Physics and Chemistry of Minerals》2004,31(6):360-364

The space group and hydrogen positions of -(Al_0.84Mg_0.07Si_0.09)OOH are investigated using a single crystal synthesized using a multi-anvil apparatus under conditions of 1000 °C and 21 GPa. The space group determined by single-crystal X-ray diffraction is to Pnn2, with unit-cell parameters of a=4.6975(8) Å, b= 4.2060(6) Å, c=2.8327(4) Å, and V=55.97(1) ų. Partial occupancy of the Al site by Mg and Si suggests the possibility of a limited solid solution between -AlOOH, stishovite, and a hypothetical CaCl₂-type Mg(OH)₂ that is 16% denser than brucite. Difference-Fourier maps reveal two small but significant Fourier peaks attributable to hydrogen atoms. Atomic distances and angles around the first peak indicate a hydrogen bond with O···O distances of 2.511 Å, while those around the second peak are suggestive of a bifurcated hydrogen bond with O···O distances of 2.743 and 2.743 Å.  相似文献