THE TRIPLE POINT OF WATER

(1) A common error in text-books on physical chemistry is pointed out. It is hoped that the correct value for the triple point temperature, +.0098 degrees C, will be given in new books and in succeeding editions of the books surveyed above. (2) Inconsistencies in the vapor pressure values for ice and for liquid water near 0 degrees C are pointed out. (3) The equilibrium vapor pressures for ice and liquid water under two different sets of equilibrium conditions are compared with the triple point pressure.     

The structure of the first coordination shell in liquid water

X-ray absorption spectroscopy and x-ray Raman scattering were used to probe the molecular arrangement in the first coordination shell of liquid water. The local structure is characterized by comparison with bulk and surface of ordinary hexagonal ice Ih and with calculated spectra. Most molecules in liquid water are in two hydrogen-bonded configurations with one strong donor and one strong acceptor hydrogen bond in contrast to the four hydrogen-bonded tetrahedral structure in ice. Upon heating from 25 degrees C to 90 degrees C, 5 to 10% of the molecules change from tetrahedral environments to two hydrogen-bonded configurations. Our findings are consistent with neutron and x-ray diffraction data, and combining the results sets a strong limit for possible local structure distributions in liquid water. Serious discrepancies with structures based on current molecular dynamics simulations are observed.     

Scheiner's Halo: Evidence for Ice Ic in the Atmosphere

Refraction of sunlight at the angle of minimum deviation between octahedral faces of crystals of ice Ic in the upper atmosphere could produce a halo around the sun or the moon at 27.46 degrees . Crystals of hexagonal ice having low-index faces cannot produce a halo of this radius. It is therefore suggested that Scheiner's halo, which has been reported at least four times since 1629 at 28 degrees from the sun, is due to ice Ic. If this is correct, it is apparently the first evidence that ice Ic occurs naturally and that liquid water can freeze to ice Ic.     

Rutherford backscattering to study the near-surface region of volatile liquids and solids

Here we describe the use of Rutherford backscattering spectrometry (RBS) to measure quantitative in situ elemental profiles with high depth resolution, online and nondestructively, in volatile substances (liquid and frozen acids, ice). Samples for analysis are held in a chamber with controlled temperature and partial pressures designed to match conditions for aerosols in Earth's atmosphere. This technique is demonstrated in studies of water solubility in sulfuric acid, hydrochloric acid (HCl) on ice surfaces, the formation of a HCl-hexahydrate surface layer on evaporating HCl-doped ice, and the diffusion of water through this layer.     

Energetics of hydrogen bond network rearrangements in liquid water

A strong temperature dependence of oxygen K-edge x-ray absorption fine structure features was observed for supercooled and normal liquid water droplets prepared from the breakup of a liquid microjet. Analysis of the data over the temperature range 251 to 288 kelvin (-22 degrees to +15 degrees C) yields a value of 1.5 +/- 0.5 kilocalories per mole for the average thermal energy required to effect an observable rearrangement between the fully coordinated ("ice-like") and distorted ("broken-donor") local hydrogen-bonding configurations responsible for the pre-edge and post-edge features, respectively. This energy equals the latent heat of melting of ice with hexagonal symmetry (ice Ih) and is consistent with the distribution of hydrogen bond strengths obtained for the "overstructured" ST2 model of water.     

Microorganisms in the accreted ice of Lake Vostok, Antarctica

Analysis of a portion of Vostok ice core number 5G, which is thought to contain frozen water derived from Lake Vostok, Antarctica (a body of liquid water located beneath about 4 kilometers of glacial ice), revealed between 2 x 10(2) and 3 x 10(2) bacterial cells per milliliter and low concentrations of potential growth nutrients. Lipopolysaccharide (a Gram-negative bacterial cell biomarker) was also detected at concentrations consistent with the cell enumeration data, which suggests a predominance of Gram-negative bacteria. At least a portion of the microbial assemblage was viable, as determined by the respiration of carbon-14-labeled acetate and glucose substrates during incubations at 3 degrees C and 1 atmosphere. These accreted ice data suggest that Lake Vostok may contain viable microorganisms.     

用于估算冻土中液态水分量的TDR数据校正(英文)

TDR作为1种野外测量土壤水分量简便而准确的方法而被人们熟知和使用。本研究使用TDR在河套灌区对冻土在冻结融解时进行了土壤水分测定。为了用TDR数据计算冻土的液态水分量,文中分析了众多计算模型和经验模型,最终找到了最适合本地区土壤特性的B irchak模型。     

不同冷源对民猪精液冷冻保存效果的影响

用干冰和液氮作为冻源对民猪精液冷冻效果进行研究,包括对精子活率及顶体完整率的影响.结果表明,以干冰为冻源进行民猪精液冷冻,解冻后精子活率为43.5％,顶体完整率为52.2％;以液氮为冻源进行民猪精液冷冻,解冻后精子活率为41.8％,顶体完整率为51.5％,二者差异不显著.     

Geomicrobiology of subglacial ice above Lake Vostok, Antarctica

Data from ice 3590 meters below Vostok Station indicate that the ice was accreted from liquid water associated with Lake Vostok. Microbes were observed at concentrations ranging from 2.8 x 10(3) to 3.6 x 10(4) cells per milliliter; no biological incorporation of selected organic substrates or bicarbonate was detected. Bacterial 16S ribosomal DNA genes revealed low diversity in the gene population. The phylotypes were closely related to extant members of the alpha- and beta-Proteobacteria and the Actinomycetes. Extrapolation of the data from accretion ice to Lake Vostok implies that Lake Vostok may support a microbial population, despite more than 10(6) years of isolation from the atmosphere.     

Microwave spectroscopic imagery of the Earth

The microwave spectrometer on the Nimbus 6 satellite has produced the first microwave spectral images of the earth. It has yielded global maps of (i) atmospheric temperature profiles, (ii) the distributions of water vapor and liquid water over ocean, and (iii) the coverage and type of ice and snow. The method has potential for operational synoptic monitoring.     

Amorphous Solid Water: An X-ray Diffraction Study

Water vapor that condenses on a metal surface at 10 degrees K forms a noncrystalline phase of estimated density 1.2 grams per cubic centimeter. X-ray diffraction data of high precision and resolution have been analyzed to yield oxygen atom pair correlation functions. The positional correlation in amorphous solid water extends over only a few molecular radii, and the radial distribution of nearneighbor oxygen atoms in amorphous solid water is qualitatively different from that found in the low-pressure ice modifications. Amorphous solid water is a useful material for liquid water models because it can be studied under conditions such that the effects of static disorder and thermal excitation can be separated.     

Carbon dioxide clathrate in the martian ice cap

Measurements of the dissociation pressure of carbon dioxide hydrate show that this hydrate (CO(2) . 6H(2)O) is stable relative to solid CO(2) and water ice at temperatures above about 121 degrees K. Since this hydrate forms from finely divided ice and gaseous CO(2) in several hours at 150 degrees K, it is likely to be present in the martian ice cap. The ice cap can consist of water ice, water ice + CO(2) hydrate, or CO(2) hydrate + solid CO(2), but not water ice + solid CO(2).     

黄河凌汛检测系统分析

根据清洁水体、浑浊水体和冰体在不同波段的反射率不同,运用C语言编写黄河凌汛检测系统程序,将清洁水体、浑浊水体和冰体检测出来,运用GIS的地图控件计算出清洁水体、浑浊水体和冰体面积以及它们的中心经纬度,以实现对黄河凌汛的动态检测。     

额尔古纳河河道冰下水位自动监测系统

根据对额尔古纳河流域冰下水位监测的需求,本文利用基于空气、冰与水电阻特性差异的冰水情检测原理,设计了一种全新的适合额尔古纳河河道的冰下水位自动测报系统,整个系统由现场冰下水位数据采集和数据处理中心两部分组成,通过对冰水情信号的采集和传输实现了对河道冰下水位、冰厚值的定点连续自动测报。经过试验证明该系统具有工作状态良好、自动化程度高、信息传送准确和监测连续等优点。试验数据为相关部门提供了第一手的界河冰下水位的数据情况。     

南极普里兹湾关键物理海洋学问题研究进展及未来趋势

南极普里兹湾及其邻近海域关键物理海洋学问题包括水团特性、环流特征和冰架 海洋 海冰相互作用过程等。该海域水团可以分为南极表层水、绕极深层水、南极底层水、南极陆架水和南极冰架水等,受外部条件影响,这些水团时空变化显著。普里兹湾区域的环流以普里兹湾流涡,西向的沿岸流和东向的绕极流,以及两者之间的南极辐散带的环流为主要特征,地形是环流特征的关键影响因素。埃默里冰架 海洋的相互作用过程显著影响普里兹湾海域的水团特性和环流状况。冰泵机制,是埃默里冰架外海水进入冰穴,并引起冰架底部消融和冻结的重要原因。冰架 海洋 海冰相互作用形成的低温高盐水,是普里兹湾形成南极底层水的潜在因素之一。加强现场观测,并建立高分辨率的冰架 海洋 海冰耦合模型系统是研究普里兹湾海域物理海洋学关键过程和变化机制的重要手段,是南极研究的发展趋势。     

Exposed water ice deposits on the surface of comet 9P/Tempel 1

We report the direct detection of solid water ice deposits exposed on the surface of comet 9P/Tempel 1, as observed by the Deep Impact mission. Three anomalously colored areas are shown to include water ice on the basis of their near-infrared spectra, which include diagnostic water ice absorptions at wavelengths of 1.5 and 2.0 micrometers. These absorptions are well modeled as a mixture of nearby non-ice regions and 3 to 6% water ice particles 10 to 50 micrometers in diameter. These particle sizes are larger than those ejected during the impact experiment, which suggests that the surface deposits are loose aggregates. The total area of exposed water ice is substantially less than that required to support the observed ambient outgassing from the comet, which likely has additional source regions below the surface.     

黄河凌汛监测系统开发

本文根据清洁水体、浑浊水体和冰体在不同波段的反射率不同,运用C#语言编写黄河凌汛监测系统程序,将水体、冰体检测出来,同时系统运用GIS的地图控件计算水体、冰体面积变化,以实现对黄河凌汛的动态监测.     

木材皱缩现象中的力学问题探讨

长期以来,木材皱缩现象一直被认为主要是因为木材中液体毛细张力产生的“负压强”压溃细胞壁造成的,该文对此提出了质疑.作者根据YoungLaplace定律设计了一组毛细负压强直接测量试验,发现凹液面上的毛细张力并不能使液体的压强降低.根据水在玻璃表面形成二维冰新结构这一最新发现,对毛细负压强及产生皱缩的主要动力问题提出了一些新的假设.     

Widespread persistent thickening of the East Antarctic ice sheet by freezing from the base

An International Polar Year aerogeophysical investigation of the high interior of East Antarctica reveals widespread freeze-on that drives substantial mass redistribution at the bottom of the ice sheet. Although the surface accumulation of snow remains the primary mechanism for ice sheet growth, beneath Dome A, 24% of the base by area is frozen-on ice. In some places, up to half of the ice thickness has been added from below. These ice packages result from the conductive cooling of water ponded near the Gamburtsev Subglacial Mountain ridges and the supercooling of water forced up steep valley walls. Persistent freeze-on thickens the ice column, alters basal ice rheology and fabric, and upwarps the overlying ice sheet, including the oldest atmospheric climate archive, and drives flow behavior not captured in present models.     

More than 200 meters of lake ice above subglacial Lake Vostok, Antarctica

Isotope studies show that the Vostok ice core consists of ice refrozen from Lake Vostok water, from 3539 meters below the surface of the Antarctic ice sheet to its bottom at about 3750 meters. Additional evidence comes from the total gas content, crystal size, and electrical conductivity of the ice. The Vostok site is a likely place for water freezing at the lake-ice interface, because this interface occurs at a higher level here than anywhere else above the lake. Isotopic data suggest that subglacial Lake Vostok is an open system with an efficient circulation of water that was formed during periods that were slightly warmer than those of the past 420,000 years. Lake ice recovered by deep drilling is of interest for preliminary investigations of lake chemistry and bedrock properties and for the search for indigenous lake microorganisms. This latter aspect is of potential importance for the exploration of icy planets and moons.