Gas Bench Ⅱ-IRMS测定地下水中溴同位素新技术

建立了利用Gas BenchⅡ联用同位素比值质谱仪(Gas BenchⅡ-IRMS)用于测定地下水中溴稳定同位素的方法.基于溴比氯更容易被重铬酸钾氧化的性质,将Br-氧化成Br2,而氯残留在原溶液中,从而把溴与氯分离开;再利用AgNO3将溴以AgBr的形式沉淀下来,然后将AgBr转化成CH3Br进行溴稳定同位素质谱测定.反应中,CH3I用量为20 μL,AgBr用量为0.5 mg.本测试流程需溴4～10 mg,质谱测试时间由1.5h缩短为800 s,测试精度优于±0.1‰(2σ).该方法可以用于地下水中溴同位素测定,在水文地质研究中具有广阔的应用前景.     

固相萃取-气相色谱/质谱法检测卤水中有机物的种类

建立了卤水中有机物的固相萃取-气相色谱/质谱分析方法。首先用石墨化碳黑柱对盐湖卤水的有机物进行富集,采用气相色谱-质谱(GC-MS)以扫描离子和选择离子检测模式进行检测。回收率标记物在0.1～1 mg/L范围里线性关系良好,相关系数R=0.998 7;其回收率处于74.00%～96.00%之间,相对标准偏差(RSD)为10.9%。最后用优化的方法检测了所富集的有机物。     

鄂尔多斯盆地七里村油田延长组长62油层沉积相特征及沉积模式

本文通过钻井、测井资料及露头地质剖面研究,对鄂尔多斯盆地三叠系延长组长62油层沉积相进行了系统分析。研究表明,研究区目的层发育三角洲前缘亚相沉积,其不具备吉尔伯特式三角洲模式的顶积层、前积层、底积层三层结构。沉积结构上,三角洲单体厚度薄、分布广,具有"毯状"沉积结构、水下分流河道砂体优势发育等特征。沉积微相发育是以分流河道砂体为骨架,河口坝一般不发育,分流河道遭受不同程度的席状化改造。一方面,当河道入湖后迅速扩展,形成面状流向湖盆中央推进,后期河道扩展后对前期沉积物进行冲刷及改造;另一方面,湖水波浪改造使河口处形成的河口坝沉积物难以保存。沉积微相组合具有以水下分流河道优势发育,水下分流河道砂体与水下分流间湾微相互层发育等特征。研究区三角洲沉积受构造演化、气候、水平面变化及供给体系等因素控制。长62油层沉积时期地形平缓,沉降速率缓慢,气候温湿,当河道携带细粒沉积物进入湖盆时,河道迅速扩展,水流分散形成面状流并向湖盆中央推进,形成"毯式"结构。总体呈水下分流河道砂体与泥岩互层发育。     

Formation of pockmarks and submarine canyons associated with dissociation of gas hydrates on the Joetsu Knoll,eastern margin of the Sea of Japan

This study, based on 3.5 kHz SBP, 3D seismic data and long piston cores obtained during MD179 cruise, elucidated the timing and causes of pockmark and submarine canyon formation on the Joetsu Knoll in the eastern margin of the Sea of Japan. Gas hydrate mounds and pockmarks aligned parallel to the axis on the top of the Joetsu Knoll are associated with gas chimneys, pull-up structures, faults, and multiple bottom-simulating reflectors (BSRs), suggesting that thermogenic gas migrated upward through gas chimneys and faults from deep hydrocarbon sources and reservoirs. Seismic and core data suggest that submarine canyons on the western slope of the Joetsu Knoll were formed by turbidity currents generated by sand and mud ejection from pockmarks on the knoll. The pockmark and canyon formation probably commenced during the sea-level fall, lasting until transgression stages. Subsequently, hydropressure release during the sea level lowering might have instigated dissociation of the gas hydrate around the base of the gas hydrate, leading to generation and migration of large volumes of methane gas to the seafloor. Accumulation of hydrate caps below mounds eventually caused the collapse of the mounds and the formation of large depressions (pockmarks) along with ejection of sand and mud out of the pockmarks, thereby generating turbidity currents. Prolonged pockmark and submarine canyon activities might have persisted until the transgression stage because of time lags from gas hydrate dissociation around the base of the gas hydrate until upward migration to the seafloor. This study revealed the possibility that submarine canyons were formed by pockmark activities. If that process occurred, it would present important implications for reconstructing the long-term history of shallow gas hydrate activity based on submarine canyon development.     

北京“7.21”暴雨过程中变形场引起的锋生与倾斜涡度发展诊断分析

从变形场驱动锋生及通过锋生引起倾斜涡度发展的角度对变形场在北京“7.21”暴雨发生、发展过程中的可能作用机制进行了初步探讨。诊断结果发现：北京地区降水产生时,变形向量与等位温线走向一致或有较小夹角,北京地区有较强的变形场局地锋生过程。锋生函数分析发现,变形项对引发暴雨的低层锋生有重要贡献。锋生能够引发大气动力、热力结构的调整,伴随大气锋生过程的高空急流加强和转竖使得北京地区处于高空急流入口区右侧的辐散区中,其带动低层空气辐合,有助于暴雨的加强维持。分析还发现,“7.21”暴雨过程中,垂直涡度存在爆发性发展,尤其是锋面降水阶段,而大气斜压度的增长趋势与垂直涡度增长趋势十分一致。分析全型涡度方程中与变形场有关的斜压度个别变化项发现,与变形场相关的垂直涡度驱动项异常正值区与垂直涡度爆发性增长区相对应,表明变形场在北京“7.21”暴雨过程中对垂直涡度发展有重要贡献。基于变形场沿其压缩轴方向气流汇合的特点,进一步分析了加入水汽作用的水汽通量变形场与暴雨发生、发展的关系。分析结果发现,低层水汽通量变形场的正值区与暴雨具有很强的相关,且水汽通量变形场包含两部分,一部分为比湿平流,其对未来暴雨区位置有很好的指示意义;一部分为变形场项,其对水汽通量变形场分布起主要贡献。     

Fossil fuel compounds from fly dust in recent organic matter of southern Poland peats

Several samples of peat from 6 bogs located in southern Poland were investigated for occurrence and distribution types of biomarkers present in their extractable organic matter fraction. It was found that there are inputs from two different sources of organic compounds differing in their characteristics and origin: (1) recent immature peat organic matter deposited in situ which is the source of all polar functionalized compounds, most of n-alkanes, and acyclic isoprenoids, and (2) mature fossil fuels, most probably bituminous coals from the Upper Silesia Coal Basin of vitrinite reflectance equivalent values of 0.9–1.1%. The latter compounds were most probably transported with fly ash to bogs from nearby settlements utilizing such fuel in domestic ovens. This group includes pentacyclic triterpenoids (hopanes and moretanes), minor amounts of n-alkanes, and numerous alkyl naphthalenes and alkyl phenanthrenes. All these compounds show distributions and values of geochemical ratios characteristic for mature organic matter confirming there ex situ origin.     

Relationship between the ionospheric conductance, field aligned current, and magnetopause geometry: Global MHD simulations

The role of the ionospheric conductance in the solar wind-magnetosphere coupling is studied using global MHD simulations. The simulations with varying conductance and a constant solar wind input show that the field-aligned currents, whose magnitude depends on the ionospheric conductance, affect the size of the magnetopause at the flanks by increasing the local magnetic pressure and thus altering the surface equilibrium at the magnetopause. A current system that generates the magnetic stresses required to account for the location and geometrical structure of the magnetosphere observed in the simulations is proposed.     

Comparative Study of LiNbO3 and Servo Controlled Air Gap Fabry-Perot Etalons for Solar Application

In this note, we compare the LiNbO₃ and Piezo-Electrically(PE) servo controlled air gap Fabry-Perot etalons for observing the Sun. An identical test setup was used to evaluate the instrumental parameters of the two etalons. It is found that for the etalons with similar finesse the advantage of using PE Etalons is tunability over entire Free Spectral Range. On the other hand, the LiNbO₃ etalons have advantage of wider acceptance angle. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Method for Determining Sedimentary Micro-Facies Belts Automatically

1IntroductionThe method is to find the boundary of distribu-tion of sedimentary micro-facies and draw the map of sedimentary belts based on known data of sedi-mentary facies from each layer(strata unit or sedi-mentary unit) of each well in a specific area. It is important to understand the distribution of sedimentary micro-facies. Generally determining the distribution of sedimentary facies is a primary and hard job in the stage of oil-field development. At the scale of sedimentary micro-f…     

Sublimation extraction coupled with gas chromatography-mass spectrometry: A new technique for future in situ analyses of purines and pyrimidines on Mars

We have developed a sublimation technique coupled with chemical derivatization and gas chromatography mass spectrometry (GC-MS) to detect nucleobases and other volatile organic compounds derived from bacteria in Mars analog materials. To demonstrate this technique, a sample of serpentine inoculated with Escherichia coli (E. coli) cells was heated to 500 °C for several seconds under Martian ambient pressure. The sublimate was collected on a cold finger, then derivatized and analyzed by GC-MS. We found that adenine, cytosine, thymine and uracil were the most abundant molecules detected in the sublimed E. coli extract by GC-MS. In addition, nucleobases were also detected in sublimed extracts of a deep-sea sediment sample, seawater, and soil collected from the Atacama Desert in Chile after heating the samples under the same conditions. Our results indicate that nucleobases can be easily isolated directly from natural samples using sublimation and then detected by GC-MS after chemical derivatization. The sublimation-based extraction technique is one approach that should be considered for use by future in situ instruments designed to detect organic compounds relevant to life in the Martian regolith.