干旱区高盐度潜水蒸发规律初步分析

为分析干旱区高盐度潜水蒸发规律,于2012年4月1日~2014年3月31日在新疆昌吉地下水均衡试验站开展了不同总溶解固体 (0.8 g/L、30 g/L和100 g/L)、不同包气带岩性(细砂和粉质黏土)和不同潜水埋深(0 m、0.5 m、1.0 m、2.0 m和3.0 m)潜水蒸发量的监测工作。结果表明:当潜水埋深大于0.5 m时,包气带岩性对高总溶解固体(Total Dissolved Solids, TDS)潜水蒸发量的影响与淡水基本一致;潜水埋深0.5 m、TDS为30 g/L时,包气带岩性的差异对潜水蒸发量的影响远小于由于潜水的TDS和外界大气蒸发能力对潜水蒸发共同造成的影响;潜水位埋深为0 m、TDS为100 g/L、包气带为粉质黏土时,年内潜水蒸发趋势与大气蒸发能力E_Φ20的趋势相反;潜水埋深0.5~1.0 m时,在非冻结期随着TDS的升高,潜水蒸发量逐渐减小;当潜水埋深为3.0 m时,TDS的变化对潜水蒸发抑制作用存在滞后性。     

The Calcium Isotope Composition of Modern Seawater Determined by Thermal Ionisation Mass Spectrometry

The Ca isotopic composition of modern seawater has been determined using a ⁴³Ca-⁴⁸Ca double spike, which was calibrated using a ⁴²Ca/⁴⁴Ca seawater ratio of 0.30587 ± 0.00026. This ratio was determined from a total evaporation experiment in which the ion beam was measured from the beginning to the end of the emission. With integration of the peak intensities, the fractionation effects can be minimised, since total evaporation of the reservoir cancels out the effect of vapour enrichment in the light isotopes. This experiment avoids the gravimetric uncertainty inherent in the double spike calibration. This calibration allows the precise redetermination of the seawater isotopic composition of Ca. A mean ⁴⁰Ca/⁴⁴Ca ratio for two Atlantic water samples of 45.143 (2s_mean= 0.003) was found. The good reproducibility of the Ca isotope ratios in present seawater and the very strong isotopic homogeneity of Ca in the oceans illustrate the advantage of using seawater as the common standard, with the advantage of decreasing interlaboratory bias.     

Geochemical features and genesis of continental cobalt-rich ferromanganese crusts

Mass cobalt-rich ferromanganese microcrusts and nodules similar in morphology and chemical composition to cobalt-rich ferromanganese deep-ocean crusts were found in Cenozoic volcanic rocks in southern Primorye. Research has shown that ore genesis of this type is genetically related to argillization and destruction of siliceous rocks by CO₂-rich fluids, which is confirmed by experimental data on carbon erosion of iron-containing materials. Two types of this fluid ore genesis are recognized: (1) relatively high-temperature (vapor-condensate), related to late volcanic processes and fracture gas infiltration, and (2) low-temperature (vapor-liquid-condensate), controlled by degassing followed by carbon mobilization (gasification). Primarily colloidal ferromanganese segregations have high contents of Co, Ni, Pb, Cu, and Ce, typical of oceanic ore genesis. Regardless of the concentrations of these metals in the protoliths, their contents in microcrusts are similar (n-10n wt.%). This indicates the same ore genesis mechanism and similar sorption properties of the colloidal ferromanganese material formed. Barium- and cerium-rich ferromanganese microcrusts and nodules are abundant. Condensed drops of iron-containing platinum were found in apobasaltic nickel-rich ferromanganese segregations. There is a cerium paradox expressed as a minimum or a total lack of cerium among rare-earth phosphates associated with ferromanganese microcrusts. Fluid destruction and oxide metallization of ocean-floor basalts are assumed to be the main source of metals for oceanic ferromanganese crusts and nodules.     

直接蒸发单颗粒锆石测定~(207)Pb/~(206)Pb年龄的方法

在双带源热离子发射质谱计上,用Kober,B.(1987)建立的方法直接蒸发锆石测定~(207)Pb/~(206)Pb表面年龄。4件已知年龄的锆石样品测定结果表明,用该方法测定的年龄值与常规锆石U-Pb一致曲线的上交点年龄一致。使用腈基丙烯酸酯粘合剂,使得装样简单、可靠,并可增加铅离子流强度。文中首次报道了湖北广水蔡家河小河岩体、黄土寨岩体中锆石的形成年龄。     

泾河流域温度与器皿蒸发量时空特征及变化趋势

利用泾河流域周边14个气象站点1957～2002年逐日温度、器皿蒸发数据,分析了近45 a来气温、器皿蒸发量的时空变化特征。Mann-Kendall统计检验结果表明：泾河流域气温变化趋势与同期我国气温变化趋势基本一致,年均温存在显著变暖的总趋势,增温率为0.29℃/10 a。流域北部气候变暖趋势高于流域南部,变暖的季节主要是秋冬季节。年器皿蒸发量呈逐渐减少的趋势,倾向率为-39.3 mm/10 a,在空间上变率表现为流域南部、北部减少趋势明显,中部变化趋势不明显。     

An improved methodology to measure evaporation from bare soil based on comparison of surface temperature with a dry soil surface

Accurate estimation of the resistances to water vapor movement is a major difficulty in evaluating evaporation from soil. By including the temperature of a dry soil surface (the temperature of the surface of a dry soil column buried in the field), a method for estimating evaporation from soil is proposed. The necessary input variables for the suggested method are temperature, net radiation, and soil heat flux. There are three advantages of the proposed method over the conventional methods. First, soil surface resistance and aerodynamic resistance are not required. Second, the variables included are fewer. Third, measurement and analysis of the parameters involved are relatively easy. Sensitivity analysis shows that the suggested method is sensitive to temperatures. Test experiments were conducted in a sandy field, where a weighing lysimeter was installed. Evaporation from soil, together with the variables specified above, were measured. For temperatures measured by thermocouples, experimental results showed that the mean absolute error (MAE) for the daily evaporation over 22 days was 0.17 mm day⁻¹. The regression between calculated and measured evaporation was highly significant (r²=0.89). Moreover, the intercept and slope of the regression equation were not significantly different from zero and unity, respectively, at the 0.05 probability level. Furthermore, by using the temperatures measured by infrared thermometers, the MAE between measured evaporation and estimated evaporation was 0.15 mm day⁻¹. The regression between them was highly significant (r²=0.94). In addition, the intercept and slope of the regression equation were not significantly different from zero and unity, respectively, at the 0.05 probability level. These results show that evaporation calculated using the proposed method is in good agreement with lysimeter measured values. By comparing with the temperature difference method, it was shown that the suggested method estimated soil evaporation more accurately than the temperature difference method. Therefore, it is concluded that the proposed method is not only a simple way for application, but also an accurate way to estimate soil evaporation.     

在“三水”转化过程中岩土水势梯度变化及其变化机理研究

通过对岩土水势梯度特征性变及机理研究,进一步加深了对“三水”转变关系的了解,并对降水入渗补给地下水机制和潜水蒸发过程及有关水文地质问题有了新认识。     

1951-2006年三峡库区夏季气候特征

以重庆市的沙坪坝、涪陵、万州、奉节和湖北省的宜昌5个站为代表,从降水、气温、日照、风速和蒸发等5个要素系统地分析了三峡库区1951-2006年夏季的气候变化特征。结果表明：三峡库区夏季降水量总体呈增加趋势,特别是在20世纪70年代末发生了一次明显跃变;最高气温、平均气温、日照时数以及蒸发量等总体呈下降趋势,在20世纪80年代初发生了一次明显跃变;平均最低气温和平均风速的变化趋势不明显,但所有气候要素均表现出明显的年代际变化特征。     

高盐度潜水蒸发试验研究现状及展望

多年来,许多专家学者对干旱区潜水蒸发的机理和规律做了大量研究工作,并取得了明显进展.但这些传统意义上的蒸发研究均未考虑潜水矿化度对潜水蒸发的影响,将在淡水条件下得出的潜水蒸发有关参数直接用于极端干旱区高盐度潜水蒸发的计算必将产生偏差.虽然部分学者注意到矿化度对于潜水蒸发的影响,但开展的研究只限于一般矿化度(小于10 g...     

库车盆地始新世盐湖物源及蒸发浓缩程度研究

古近纪塔里木盆地属于副特提斯海东延部分,而库车次级盆地位于其东北部。它古近纪经历了浅海相—海陆交互相—陆相的沉积演化,并发育了巨厚蒸发岩,是中国油气的重要产区和钾盐重点勘查区,长期以来受到广大地质学家的关注。然而,关于库车盆地始新世盐湖卤水来源及蒸发浓缩成钾的研究尚存在一些争议和不确定性。因此,本文基于岩石学和矿相学观察、X射线衍射和扫描电镜能谱分析以及稳定同位素研究,探讨蒸发岩的沉积环境、补给来源及蒸发浓缩程度。蒸发岩岩相学分析表明:蒸发岩形成于近源泥砾混入的盐湖沉积环境。硬石膏δ~(34)S值指示了具有一定海源补给特征。石盐原生流体包裹体δD和δ18 O值分别为-118.1‰~-95.3‰和2.5‰~5.7‰,蒸发趋势线说明了古卤水蒸发浓缩程度较高。古盐湖演化过程中虽然经历了3次短暂的淡水混入,但随着古盐湖持续的蒸发作用,并没有影响钾镁盐的析出,且在δ18 O值正偏较大时析出相应的钾盐或含钾矿物,推测库车盆地始新统含盐系地层具有良好的成钾潜力。