短波红外光谱技术在西藏尼木地区岗讲斑岩铜-钼矿床中的应用

为进一步探明岗讲斑岩铜-钼矿床蚀变和矿化结构,有效指导下一步勘查工作,利用短波红外光谱技术对矿床内典型剖面上的4个钻孔进行了系统的测试分析.共检测到绢云母类、高岭石类、绿泥石类、硫酸盐类和碳酸盐类等蚀变矿物,其中尤以绢云母类矿物最为发育.对绢云母进行短波红外光谱测试分析显示:在靠近矿体的位置,有较大的伊利石结晶度(≥1.5)和较小的绢云母Al-OH吸收位置(≤2 205 nm);而在远离矿体的位置伊利石结晶度和绢云母Al-OH吸收位置分别为0.8~1.2和2 207~2 209 nm.同时,铁氧化物强度值与氧化矿体的出现具有同步性.表明短波红外光谱的这些特征参数有助于进一步理解岗讲斑岩铜-钼矿床蚀变和矿化结构,有效识别成矿流体性质,有潜力成为该矿区及其他类似矿区有效的找矿指标.     

Experimental measurements of water content in crude oil emulsions by terahertz time-domain spectroscopy

We measured the water content （0.01% 0.25% w/w） in crude oil emulsions using terahertz time-domain spectroscopy （THz-TDS）. To improve the precision and range of the measurements, we used 1 and 10 mm thick quartz cells. The experiments were performed at 20 ℃ and the THz wave was transmitted vertically to the samples and detected on the other side. The experimental results suggest linear relation for the THz absorption coefficient and the water content of the crude oil emulsions in the observed range. The linear dependence facilitates high-precision measurements of the water content of crude oil. This suggests the potential of THz-TDS in determining the water concentration in crude oil and borehole fluid identification.     

Electrical conductivity,thermopower and <Superscript>57</Superscript>Fe Mössbauer spectroscopy of aegirine (NaFeSi<Subscript>2</Subscript>O<Subscript>6</Subscript>)

DC and AC electrical conductivities were measured on samples of two different crystals of the mineral aegirine (NaFeSi₂O₆) parallel () and perpendicular () to the [001] direction of the clinopyroxene structure between 200 and 600 K. Impedance spectroscopy was applied (20 Hz–1 MHz) and the bulk DC conductivity _DC was determined by extrapolating AC data to zero frequency. In both directions, the log _DC – 1/T curves bend slightly. In the high- and low-temperature limits, differential activation energies were derived for measurements [001] of E_A 0.45 and 0.35 eV, respectively, and the numbers [001] are very similar. The value of _DC [001] with _DC(300 K) 2.0 × 10^{–6 –1}cm^–1 is by a factor of 2–10 above that measured [001], depending on temperature, which means anisotropic charge transport. Below 350 K, the AC conductivity () (/2=frequency) is enhanced relative to _DC for both directions with an increasing difference for rising frequencies on lowering the temperature. An approximate power law for () is noted at higher frequencies and low temperatures with () ^s, which is frequently observed on amorphous and disordered semiconductors. Scaling of () data is possible with reference to _DC, which results in a quasi-universal curve for different temperatures. An attempt was made to discuss DC and AC results in the light of theoretical models of hopping charge transport and of a possible Fe²⁺ Fe³⁺ electron hopping mechanism. The thermopower (Seebeck effect) in the temperature range 360 K < T <770 K is negative in both directions. There is a linear – 1/T relationship above 400 K with activation energy E 0.030 eV [001] and 0.070 eV [001]. ⁵⁷Fe Mössbauer spectroscopy was applied to detect Fe²⁺ in addition to the dominating concentration of Fe³⁺.     

Mechanism of Hg(II) immobilization in sediments by sulfate-cement amendment

Reactive amendments such as Portland and super-sulfate cements offer a promising technology for immobilizing metalloid contaminants such as mercury (Hg) in soils and sediments through sequestration in less bioavailable solid forms. Tidal marsh sediments were reacted with dissolved Hg(II) in synthetic seawater and fresh water solutions, treated with Portland cement and FeSO₄ amendment, and aged for up to 90 days. Reacted solids were analyzed with bulk sequential extraction methods and characterized by powder X-ray diffraction (XRD), electron microscopy, and synchrotron X-ray absorption spectroscopy at the Hg L_III- and S K-edge. In amended sediments, XRD, SEM and sulfur K-edge XANES indicated formation of gypsum in seawater experiments or ettringite-type (Ca₆Al₂(SO₄)₃(OH)₁₂^.26H₂O) phases in fresh water experiments, depending on the final solution pH (seawater ∼8.5; freshwater ∼10.5). Analysis of Hg EXAFS spectra showed Cl and Hg ligands in the first- and second-coordination shells at distances characteristic of a polynuclear chloromercury(II) salt, perhaps as a nanoparticulate phase, in both seawater and fresh water experiments. In addition to the chloromercury species, a smaller fraction (∼20–25%) of Hg was bonded to O atoms in fresh water sample spectra, suggesting the presence of a minor sorbed Hg fraction. In the absence of amendment treatment, Hg sorption and resistance to extraction can be accounted for by relatively strong binding by reduced S species present in the marsh sediment detected by S XANES. Thermodynamic calculations predict stable aqueous Hg–Cl species at seawater final pH, but higher final pH in fresh water favors aqueous Hg-hydroxide species. The difference in Hg coordination between aqueous and solid phases suggests that the initial Hg–Cl coordination was stabilized in the cement hydration products and did not re-equilibrate with the bulk solution with aging. Collectively, results suggest physical encapsulation of Hg as a polynuclear chloromercury(II) salt as the primary immobilization mechanism.     

MIPAS-Transall Observations of the Variability of CLONO2 during the Arctic Winter of 1994/95

In the winter of 1994/95 the German Transall research aircraft performed 5 campaigns in the European Arctic with 22 flights altogether. An extensive dataset of HNO3, ClONO2 and O3 column amounts was obtained by MIPAS-FT (Michelson Interferometer for Passive Atmospheric Sounding - Flugzeug Transall) onboard the aircraft. In this paper we present the variability of the ClONO2 reservoir gas in the course of the winter. We include groundbased FTIR measurements of HF, HCl and ClONO2 to discuss the airborne observations with regard to the partitioning of inorganic chlorine.From mid-December until the end of January, MIPAS measured a stable ClONO2 collar with constantly low column amounts inside the polar vortex and maxima at the edge. This observation reflected widespread conversion of ClONO2 to reactive chlorine inside the vortex for at least six weeks. In good accordance, the ground stations measured low in-vortex HCl and ClONO2 column amounts and conversion of HCl into ClONO2 in the region of the ClONO2 maxima. In the first week of February the ClONO2 amounts started to increase in the edge region as well as inside the vortex. Between March 21 and 27, just one week after the last cold period, MIPAS observed exclusively high ClONO2 column amounts inside the vortex, indicating fast deactivation of active chlorine. In the same period the ground stations measured an excess of ClONO2 over HCl. Further, the high ClONO2 implies that the polar vortex was renoxified in March. Lower ClONO2 values, observed inside the vortex on the flights of April 5 and 8, and an increased HCl/ClONO2 ratio, measured from ground, marked the starting redistribution within the chlorine reservoir species to the photochemically more stable HCl.In February, March and April, MIPAS observed mixing of ClONO2-rich air masses with midlatitude air at the vortex edge. A very clear event happened on March 27. On this flight a distinct ClONO2 minimum was measured at the vortex edge, which was closely correlated with a filament of midlatitude air observed by OLEX (Ozone Lidar EXperiment) onboard the Transall.     

南海乐东海域黄色物质浓度反演及其时空变化分析

为掌握南海乐东海域黄色物质浓度的时间及空间动态,对该海域黄色物质浓度反演方法及表达方式进行研究。利用在乐东海域遥感地质调查获取的黄色物质吸收系数数据对Carder和Tassan两种模型进行回归分析,得到黄色物质浓度反演模型。其中,利用Carder模型进行回归分析得到的回归模型决定系数R~2为0.62;利用Tassan模型进行回归分析得到的回归模型决定系数R~2为0.78。应用精度较高的Tassan回归模型反演黄色物质浓度并进行年度、季度变化分析,结果表明:1由近岸到深海,黄色物质浓度呈现逐渐下降的趋势,且分布一定程度上受洋流和人类活动的影响;2黄色物质浓度有逐年上升的趋势,在不同季节里,冬季黄色物质浓度最高。     

Temperature-dependence of ultraviolet absorption cross-sections of alternative chlorofluoroethanes: 2. The 2-chloro-1,1,1,2-tetrafluoro ethane -HCFC-124

The temperature-dependent ultraviolet absorption cross-sections of CF₃-CHFCI (HCFC-124) have been measured between 170 and 230 nm for temperatures ranging from 295 to 210 K, with uncertainties between 2 and 4%. These results are compared with other available sets of determinations. Temperature effects are discussed and the photodissociation coefficients, presented with their temperature dependence, are calculated. Implication of the temperature dependences on the stratospheric chemistry is also discussed. Parametrical formulae are proposed to compute absorption crosssection values for wavelengths and temperatures useful in modelling calculations.     

UV-Vis spectrophotometric and XAFS studies of ferric chloride complexes in hyper-saline LiCl solutions at 25-90 °C

The speciation and thermodynamic properties of ferric chloride complexes in hydrothermal solutions and hypersaline brines are still poorly understood, despite the importance of this element as a micronutrient and ore-component. Available experimental data are limited to room temperature and relatively low chloride concentrations. This paper reports results of UV-Vis spectrophotometric and synchrotron XAFS experiments of ferric chloride complexes in chloride concentrations up to 15 m and at temperatures of 25-90 °C. Qualitative interpretation of the UV-Vis spectra shows that FeCl²⁺, FeCl₂⁺, FeCl_3(aq) and FeCl₄⁻ were present in the experimental solutions. As chloride concentrations increase, higher ligand number complexes become important with FeCl₄⁻ predominating in solutions containing more than 10 m at 25 °C. The predominance fields of FeCl_3(aq) and FeCl₄⁻ expand to lower Cl concentrations with increasing T. Both XANES and UV-Vis spectra reveal a major change in the geometry of the complex between FeCl₂⁺ and FeCl_3(aq). EXAFS data confirm that the number of chloride ligands increases with increasing chloride concentration and show that Fe³⁺, FeCl²⁺ and FeCl₂⁺ share an octahedral geometry. FeCl_3(aq) could be either tetrahedral or trigonal dipyramidal, while FeCl₄⁻ is expected to be tetrahedral. EXAFS data support a tetrahedral geometry for FeCl₄⁻, especially at 90 °C, but do not allow to distinguish between a tetrahedral or trigonal dipyramidal geometry for FeCl_3(aq) because of similar Fe-Cl distances. At room temperature, EXAFS data suggest that FeCl_3(aq) may be a mixture of octahedral and tetrahedral or trigonal dipyramidal forms.The room temperature formation constants for three ferric chloride complexes (FeCl₂⁺, FeCl_3(aq) and FeCl₄⁻) determined from the UV data are generally in good agreement with previous studies. Calculations based on the properties extrapolated to 300 °C show that hematite solubility is much higher than previously estimated, and that the high orders complexes FeCl_3(aq) and FeCl₄⁻ are important at high temperatures even in solutions with low chloride concentrations. The accuracy of these properties is limited by a poor understanding of activity-composition relationships in concentrated electrolytes, and by limitations in the available experimental techniques and extrapolation algorithms; however, the inclusion of higher order complexes in numerical models of ore transport and deposition allows for a more accurate qualitative prediction of Fe behaviour in hydrothermal and hypersaline systems.     

莱州湾荧光溶解有机物的时空分布

利用三维荧光光谱-平行因子分析法(EEMs-PARAFAC)技术结合多元统计方法研究了莱州湾海域春季(2020年5月)和秋季(2020年10月)荧光溶解有机物(FDOM)的来源及时空分布特征。结果显示莱州湾海域FDOM由2类共4个荧光组分组成:C1、C4为类蛋白质组分,分别为色氨酸和酪氨酸; C2、C3为类腐殖质组分。并对各组分的来源及分布特征分析:春季FDOM分布主要受到陆源输入的影响,其中表层C1、C2、C3也受微生物活动影响。秋季表层C1、C2、C3分布受到陆源输入和浮游植物生产共同影响,秋季表层C4主要受生物现场生产影响,秋季底层C1、C2、C3主要受陆源输入影响,C4受陆源输入和浮游植物生产共同影响。各荧光组分在表层的季节性差异主要是由于春季部分FDOM经陆源输入后受偏南风作用,在莱州湾西部及南部海域扩散。FDOM在底层的季节性差异主要由于受到沉积物再悬浮的影响。HIX高值分布表明莱州湾西部和南部FDOM受陆源输入影响显著,BIX高值分布表明莱州湾远海FDOM受生物活动影响程度较高。总体上,陆源输入影响莱州湾FDOM分布的主要因素。     

Study of inorganic ligand-chromium(III)-surface ternary complexes by ESR spectroscopy

Cr(III) sorbed at the solid/water interface of latex and hectorite was studied by ESR spectroscopy in the presence of different inorganic ligands. The ESR spectra of the surface obtained in the presence of selenite, phosphate and fluoride can be explained in terms of ternary surface complex formation. This is contrasted by the behaviour of sulfate and selenate ions which were found to have no effect on the ligand field of Cr(III), either in the adsorbed state or in solution.