Major ion geochemistry of Godavari River at Rajahmundry, India

Detailed time-series studies on the major ion geochemistry of tropical peninsular Indian rivers are lacking. In this backdrop, a small stretch of the Godavari River, globally ranking 32nd in terms of total discharge, is chosen for sampling at its mouth. The objectives are： （1） to understand the natural and anthropogenic sources controlling the major ion chemistry of the Godavari River at Rajahmundry, （2） processes controlling the temporal variations in major ions over a period of two years, （3） comparison of total dissolved solid （TDS） fluxes and weathering rates at Godavari River with other major tropical rivers. A total of 47 surface samples were collected, bimonthly, at five stations in the Godavari at Rajahmundry spaced over a distance of 6 km for a period of two years. Water samples were collected in pre-cleaned PP bottles. Parameters like temperature, pH, conductivity, dissolved oxygen, alkalinity were measured on-site. Samples collected for analysis of major ions were processed within a few hours of collection by filtering through 0.45 mm pore size millipore filters. Filtered water samples for major ions were transported to the laboratory in cleaned 250 mL PP bottles. Sodium and K were measured on a Flame Photometer, Ca and Mg on a Flame Atomic Absorption Spectrophotometer, Cl, NO3, SO4 by Ion Chromatography and SiO2 on a spectrophotometer. Chemical weathering of rocks controls the major ion chemistry of the Godavari River at its mouth as indicated by the alkaline nature of the river and dominant presence of Ca, Mg and HCO3 ions. Ca/Mg and Na/Mg ratios point its source to a mixture of lithological assemblages of basalt, granite-granodiorite,     

洛川黄土地层学

黄土和古土壤的磁化率与所含磁性矿物的浓度和颗粒大小密切相关。磁化率信号的主要载体是非常细的磁铁矿和(或者)磁赤铁矿。洛川黄土序列的磁化率曲线变化与成壤作用和粉尘堆积作用强弱有关,反映了气候的变化。磁化率值为识别黄土和古土壤层提供了一个工具。文中建议了黄土岩石地层单位命名的原则。洛川黄土-古土壤序列的磁化率曲线记录了最近2.5Ma气候变化的历史,与深海沉积的气候记录可以对比。     

中国西南攀西地区下侏罗统益门组蜥脚类足迹:分类学与潜在的造迹者

恐龙足迹和骨骼的记录往往出现在不同的地区。然而,一些地层显示了关系紧密的骨骼和足迹,它们都指向同一个来源。报道了来自四川省攀西地区会理县通安镇通保村下侏罗统益门组中上部的蜥脚类足迹(雷龙足迹Brontopodus),其地理和地层归属均与真蜥脚类的何氏通安龙极为接近。通保足迹与造迹者的关联是可能的,但目前还需要更多的证据。通保的雷龙足迹是攀西地区首次发现侏罗纪的蜥脚类足迹,这也表明,在早侏罗世,原始蜥脚类和基干蜥脚型类共存于中国西南地区。     

Aquatic ecological risk assessment of OCPs in Huaihe River, Jiangsu section

The Huaihe River Basin, located between the Yellow River and the Yangtze River, is one of the most populated areas in the eastern part of China. The Huaihe River is probably the most heavily polluted one among the three largest rivers in China. The Jiangsu section is the downstream reaches of the Huaihe River, where organochlorine pesticides （OCPs） may come from local discharge due to flourishing industry and agriculture, and also from inflows from upstream. OCPs are usually hazardous organic pollutants, and may endanger the aquatic ecosystem of the Huaihe River, Jiangsu section. Surface water of the Huaihe River, Jiangsu section in both high-flow period and low-flow period was sampled and OCPs were determined using GC-ECD. 15 OCPs were detected, including 2,4＇-DDT, 4,4＇-DDT, 4,4＇-DDD, α-HCH, β-HCH, γ-HCH, aldrin, endrin, dieldrin, methoxychlor, heptachlor, hexachlorobenzene（HCB）, α-endosulfan, α-Endosulfan and heptachlorepoxide. The span of total OCPs concentration is between 26.27-124.39 ng/L. Among the 15 OCPs detected, aquatic ecological risk assessment was performed for 12 ones except for α-endosulfan, α-endosulfan and heptachlorepoxide due to lack of the relevant toxicity data of the three compounds. The acute toxicities of 12 OCPs to multi aquatic species were collected from AQUIRE database and other sources. Environmental Concentration Distribution （ECD） and Species Sensitivity Distribution （SSD） were achieved after Kolmogorov-Smirnov test. The risk quotient distributions were acquired using Monte Carlo simulation. The aquatic ecological risks caused by single OCPs were analyzed. It is shown that endrin and 2,4＇-DDT have the highest risk while HCB and HCHs have the lowest risk. Then the joint ecological risk caused by all 12 OCPs was calculated based on the concept of equivalent concentration and it proves to be significantly higher than risk caused by any single OCP. Furthermore, the probability of aquatic ecological risk was calculated according to different ecological risk criteria （ERC）. The comparative analysis shows that ERC is very important to the result of ecological risk assessment.     

宽角反射、折射地震数据与重力数据综合解释龙门山及邻近地区地壳结构

青藏高原东部的隆升机制一直都是地学界的研究热点,研究学者们提出和发展了多种岩石圈变形模型,而存在多种模型的主要原因之一是对青藏高原东部地壳及岩石圈结构认识不足。本文主要针对SinoProbe-02项目横跨龙门山断裂带、全长400多公里的宽角、折射地震数据及重力数据进行联合反演和综合解释。研究结果表明,龙门山及邻近地区地壳结构可明确划分为上地壳、中地壳和下地壳。上地壳上层为沉积层,龙门山断裂带以西大部分区域被三叠纪复理岩覆盖,而在龙日坝断裂与岷江断裂之间出现了密度为2.7g/cm³的高速异常体;向东靠近龙门山地区,沉积层厚度逐渐减薄。中地壳速度变化不均一,而且变形强烈;若尔盖盆地和龙门山断裂带下方出现明显低速带;中地壳在龙门山西侧厚度加厚,在岷江断裂下方和四川盆地靠近龙门山断裂带地区附近厚度达到最大。莫霍面整体深度从东往西增厚,最厚可达56 km。本次研究得到的地壳结构和密度分布分析结果表明现有的地壳厚度和物质组成不足以支撑龙门山及邻近地区目前所达到的隆升高度,因此四川盆地刚性基底西缘因挤压作用产生的弯曲应力也是该地区抬升的重要条件之一。     

南海神狐海域表层沉积物稀土元素地球化学

南海神狐海域表层沉积物稀土元素总量变化较大,分布范围为66.8～218.3μg/g,平均值为128.1μg/g,相对接近于中国黄土(w(∑REE)=170.66μg/g);∑REE受"粒度效应"控制,主要富集于黏土质粉砂中;各类沉积物及与中国黄土、上陆壳和珠江口沉积物的稀土元素标准化曲线的变化趋势基本一致,表明这些沉积物具有相同的物源区,且具有大陆地壳性质。铈的负异常主要受陆源源区气候环境变化控制,而与海水关系不大。∑REE与CaO、CaCO3和Sr元素呈负相关,与Al2O3、K2O、SiO2呈正相关,表明稀土元素与生物作用基本无关,可能主要吸附于黏土矿物表面和赋存于陆源碎屑矿物的晶格中。     

墨西哥湾盆地石油的来源和分类

通过对墨西哥湾岸盆地大量原油样品的抽样调查,其地球化学特征表明,原油的成因类型主要有5组,即①上侏罗统牛津阶海相泥灰岩;②上侏罗统牛津阶海相碳酸盐岩;③上侏罗统提塘阶海相泥灰岩;④白垩系海相碳酸盐岩—蒸发岩;⑤第三系海相三角洲碎屑岩。每一组都与特定的烃源岩有关。烃源岩为多源输入,多相(石油—天然气)变化,已达到成熟,并经历了后期填充蚀变过程。     

黄河三角洲地区末次盛冰期以来浅地层划分与海平面变化的响应

通过对黄河三角洲几个钻孔的分析.将其自上而下划分成3个海相层和3个陆相层,并且划分为1个4级层序(准层序)和4个5级层序。每个层序代表了一次海平面的升降旋回。4级层序的海退沉积与末次冰期的后期对应,海平面下降最大时期是末次冰期最盛期(LGM)的反映。