Normal Alkane Distributions in Soil Samples along a Lhasa-Bharatpur Transect

We present n-alkane distributions in the soil samples along a transect from Lhasa on the Tibetan Plateau to Bharatpur in Nepal, which covers a large geographical area and a wide range of climatic conditions. These data allow us to assess the significance of n-alkane distributions in different vegetation types and their relationships to temperature and precipitation. In the tropical rainforest and broadleaved forest zones, n-alkanes exhibit a bimodal distribution pattern with dominant homologues around n-C_(31) and n-C_(23). The bimodal distribution of tropical rainforest n-alkanes may be a general pattern because of the presence of many lianas, epiphytic plants, algae and the strong microbial activity and degradation involved in the postdepositional process. In the warm-temperate mixed forest and needle-leaved forest zones, the long-chain alkanes have a pattern of n-C_(31) n-C_(33) n-C_(27). In the alpine shrub and grassland zone, although the most abundant homologue is n-C_(31) , relatively high n-C_(23) concentrations have also been observed in some samples. The statistical results show a good correlation between n-alkane proxies and climatic factors. The average chain length(ACL) values are positively correlated with precipitation and temperature across the transect. The carbon preference index(CPI) values show a negative correlation with temperature and precipitation along a Lhasa–Bharatpur transect. Although there is a positive relationship between ACL and temperature, it is difficult to separate the two climatic variables(temperature and precipitation) because they are well coupled in the monsoon region.     

Strengthened African summer monsoon in the mid-Piacenzian

Using model results from the first phase of the Pliocene Model Intercomparison Project (PlioMIP) and four experiments with CAM4, the intensified African summer monsoon (ASM) in the mid-Piacenzian and corresponding mechanisms are analyzed. The results from PlioMIP show that the ASM intensified and summer precipitation increased in North Africa during the mid-Piacenzian, which can be explained by the increased net energy in the atmospheric column above North Africa. Further experiments with CAM4 indicated that the combined changes in the mid-Piacenzian of atmospheric CO₂ concentration and SST, as well as the vegetation change, could have substantially increased the net energy in the atmospheric column over North Africa and further intensified the ASM. The experiments also demonstrated that topography change had a weak effect. Overall, the combined changes of atmospheric CO₂ concentration and SST were the most important factor that brought about the intensified ASM in the mid-Piacenzian.     

Developed and developing world contributions to climate system change based on carbon dioxide,methane and nitrous oxide emissions

One of the key issues in international climate negotiations is the formulation of targets for emissions reduction for all countries based on the principle of "common but differentiated responsibilities". This formulation depends primarily on the quantitative attribution of the responsibilities of developed and developing countries for historical climate change. Using the Commuity Earth System Model(CESM), we estimate the responsibilities of developed countries and developing countries for climatic change from 1850 to 2005 using their carbon dioxide, methane and nitrous oxide emissions. The results indicate that developed countries contribute approximately 53%–61%, and developing countries approximately 39%–47%, to the increase in global air temperature, upper oceanic warming, sea-ice reduction in the NH, and permafrost degradation. In addition, the spatial heterogeneity of these changes from 1850 to 2005 is primarily attributed to the emissions of greenhouse gases(GHGs)in developed countries. Although uncertainties remain in the climate model and the external forcings used, GHG emissions in developed countries are the major contributor to the observed climate system changes in the 20 th century.     

城市地理空间数据集成应用探讨

城市地理空间数据是表达城市地理要素的数量、质量、分布特征、相互关系、变化规律的位置信息和属性信息。分析城市地理空间数据的组成结构、组织管理、集成利用,并将这些数据有效应用于城市地理信息系统建设之中,将在城市信息化道路上起到举足轻重的作用。该文以开发的"兰州市城关区地理信息集成系统"为例,重点阐述了城市地理空间数据的构成与获取方式,研究了城市地理空间数据与业务部门数据的集成方法,并对城市地理空间数据在晕渲图制作、三维景观生成、数据可视化等主要应用上进行了分析和探讨。     

页岩沉积环境对其油气潜力的影响:以中国和北美对比研究为例

页岩油气是当前全球油气勘探和研究的热点,但其潜力评价一直是难点。该文以中国和北美的四套典型页岩为例,包括北美湖相Green River组、内陆海相Niobrara组、中国环境来评价相龙马溪组和济阳坳陷湖相页岩,发现页岩沉积环境与其油气潜力具有密切关系,因此可通过分析发现这四套页岩的沉积环境都具有页岩沉积环境评价其页岩油气潜力。通过微量元素、生物标志化合物、扫描电镜、X-CT和X射线衍射等方法,发现这四套页岩都具有一定的还原性和较高的生产力,且具有差异性。内陆海相Niobrara组页岩具有弱还原的沉积环境,在四套页岩中有机碳含量较低,呈块状沉积构造,裂缝与微裂缝较少,储集空间相对有限。焦石坝海相龙马溪组页岩为还原的沉积环境,岩石以富含有机质的硅质岩为主,可观察到大量的大孔隙与少量的微裂缝。Green River页岩和济阳坳陷页岩形成于陆相咸化的强还原沉积环境,有机碳含量高,页岩以纹层状结构为主,岩石组成脆性矿物含量高,含有大量的裂缝。可见,具有强还原沉积环境的页岩通常具有较好的勘探前景。     

地下水的生态环境效应及控制指标研究进展

地下水具有重要的生态功能和环境属性。随着不合理的人类活动,改变地下水性状而引发的诸多生态环境问题的出现,国内外有关学者积极进行地下水生态环境效应及控制指标的研究,目前已取得了一些进展,但迄今为止鲜见对其研究成果的综述,及时总结该领域的研究成果可以为进一步深入全面开展研究提供基础。综述了国内外有关地下水引起的七个方面的生态环境效应及三个方面的控制指标的研究现状,最后指出了目前研究中存在的问题并对未来的研究进行了展望,以期为进一步深入全面开展该领域的研究提供基础,更好地促进地下水资源开发利用与生态环境保护协调发展。     

扬子陆块西缘乌拉溪花岗岩体SHRIMP锆石U-Pb定年及地质意义

乌拉溪花岗岩体位于扬子陆块西缘的江浪穹窿北侧,为精确厘定其形成时代并探讨岩石成因、构造意义及与里伍式铜矿的关系,对其进行了SHRIMP锆石U-Pb年代学研究。定年结果表明,乌拉溪花岗岩中发育940.3~199.6Ma的锆石,最年轻一组岩浆锆石206Pb/238U加权平均年龄为166.6±1.1Ma(MSWD=2.6,n=6)。结合前人研究成果,认为乌拉溪花岗岩体形成于~166.6Ma,接近邻近的文家坪花岗岩体结晶年龄(~161.5Ma),可能均是松潘—甘孜造山带伸展构造背景下里伍岩群部分熔融的产物。2个岩体年龄大致代表江浪穹窿的成穹时代,后者可能发生于166.6~161.5Ma。此外,花岗岩体结晶年龄与金属硫化物Re-Os定年结果相近,表明江浪穹窿的Cu、W成矿可能与岩浆热液作用相关。     

川西新场构造须四段储层特征及主控因素

利用岩心观察、岩石薄片分析、阴极发光和扫描电镜等方法对川西新场地区须四段储层的岩石学特征、储集空间类型及物性特征进行分析,讨论沉积环境、成岩作用及构造作用等对储层的影响。研究区储层经历了压实作用、胶结作用、溶蚀作用和交代作用等成岩作用。有利储层主要发育在分选性中等-好、杂基含量低的中细粒砂岩中。主要储集空间以次生孔隙为主,其次为残余粒间孔。高能环境下的分流河道和河口坝是形成有利储层的先决条件,而后期长石及岩屑溶蚀产生的次生孔隙、裂缝的发育是形成有利储层的关键。     

气象数据云数据存储技术及应用

针对气象数据种类多、信息量大、精度高等特点,传统的关系型数据库系统在存储处理、数据读取等方面存在负载饱和、读写性能不理想等问题,利用云数据存储技术,结合气象数据特征,设计了基于云数据存储平台的气象数据存储和处理方法。通过分析气象数据的结构化、半/非结构化特征,采用云关系型数据库存储结构气象数据;采用NoSQL对象库存储半/非结构化气象数据;在数据的存储过程中,应用了气象数据分块压缩技术,进行气象数据存储和传输。结果表明,所讨论的方法具有很好的存储传输效率,能够满足大规模气象数据在业务应用中对存储查询和处理速度的要求。