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991.
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993.
Abhijit Mukherjee Prosun Bhattacharya Fei Shi Alan E. Fryar Arun B. Mukherjee Zheng M. Xie Gunnar Jacks Jochen Bundschuh 《Applied Geochemistry》2009
Elevated As concentrations in groundwater of the Huhhot basin (HB), Inner Mongolia, China, and the western Bengal basin (WBB), India, have been known for decades. However, few studies have been performed to comprehend the processes controlling overall groundwater chemistry in the HB. In this study, the controls on solute chemistry in the HB have been interpreted and compared with the well-studied WBB, which has a very different climate, physiography, lithology, and aquifer characteristics than the HB. In general, there are marked differences in solute chemistry between HB and WBB groundwaters. Stable isotopic signatures indicate meteoric recharge in the HB in a colder climate, distant from the source of moisture, in comparison to the warm, humid WBB. The major-ion composition of the moderately reducing HB groundwater is dominated by a mixed-ion (Ca–Na–HCO3–Cl) hydrochemical facies with an evolutionary trend along the regional hydraulic gradient. Molar ratios and thermodynamic calculations show that HB groundwater has not been affected by cation exchange, but is dominated by weathering of feldspars (allitization) and equilibrium with gibbsite and anorthite. Mineral weathering and mobilization of As could occur as recharging water flows through fractured, argillaceous, metamorphic or volcanic rocks in the adjoining mountain-front areas, and deposits solutes near the center of the basin. In contrast, WBB groundwater is Ca–HCO3-dominated, indicative of calcite weathering, with some cation exchange and silicate weathering (monosiallitization). 相似文献
994.
GPS网平差观测量选取的理论分析 总被引:1,自引:0,他引:1
由多台GPS接收机在不同时段进行静态观测而组成的观测网形,当采用高精度的科研软件与常用商用软件解算基线时,其基线向量的方差阵不同,前者的方差阵结构是完全的、严密的。同时,在进行GPS网平差时,选取GPS基线的方式及数量的不同,构造的网形也就不同,采用不同的数学模型其得到的平差结果和精度指标也不相同。文章先从理论上进行分析,后用示例进行比较论证。 相似文献
995.
Shi Jian-chun Lin Chi-shengHu Zhong-wei Zhao Hai-binMa Yue-hua 《Chinese Astronomy and Astrophysics》2011,35(3):295
The cometary disconnection event (DE) is the separation of the entire cometary tail or a part of it from the cometary head. It is one of the most spectacular phenomena of comets. The driving mechanism remains unclear, and at present there are many competitive theories to explain the onset of DE. However, the variable solar wind is suspected to play a major role. Comet Lulin exhibited a DE on 4th Feb. 2009. The data around this date are analyzed, and it is found that the comet Lulin had already endured a DE on 3rd Feb. 2009. By comparing the morphologies of the plasma tails in these two DEs, it is concluded that the DE which occurred on 3rd Feb. 2009 is another DE, which is distinct from that of 4th Feb. 2009. In this paper, we describe the results of analysis on the DE dated 3rd Feb. 2009. The measured velocity of disconnection motion is about 68 km/s, and the calculated onset time of this DE is 3.635 ± 0.215 Feb. 2009 in UT decimal date. Combining the orbital characteristics of Comet Lulin before and after the DE occurrence and the solar-wind data measured by the STEREO-A spacecraft, it is concluded that the DE which occurred on 3rd Feb. 2009 was probably caused by the magnetic reconnection due to the interaction between the comet and a coronal mass ejection (CME). 相似文献
996.
Diapycnal Mixing (DM) within the upper 2000m of the global ocean is calculated by a fine-scale parameterization using the multiyear-mean density gridded product that created by employing all the Argo float observations to date through the recently published equation of seawater TEOS-10. The geographic distribution of Argo-derived DM derived in this study is spatial-dependent and varies with latitude and depth. The magnitude and pattern of DM is favorably validated by comparisons with previous studies. Furthermore, the mixing coefficient tensor K is calculated and analyzed. Components of the tensor fitting for the geopotential coordinate models are also presented. It is found that the tensor components in horizontal direction, Kxx and Kyy, have similar magnitude and distribution pattern. In the vertical, Kzz is enhanced over regions with rough topography and strong wind (e.g., Westerly region), suggesting agreement with previous estimates. This work presents a scheme to estimate the DM and mixing coefficient tensor using Argo observations, and offers a useful Argo-based mixing product for the purpose of promoting the study and modeling of ocean circulation and other processes. 相似文献
997.
采用MAP-CGE模型,模拟了我国水泥行业实施低碳水泥标准对不同生产工艺产出、能耗及污染排放的影响,测算了对其边际减排成本和均衡价格的影响,分析了对不同污染物的协同减排效果。模拟结果表明:实施低碳水泥标准有利于水泥生产工艺的升级换代,并有助于水泥行业节能减排;在现有技术水平下,水泥行业在减排1 t CO2的同时将带来约1.17 kg的SO2减排量和4.44 kg的NOx减排量;实施低碳水泥标准对于水泥行业控制NOx排放很有利;但水泥行业也需承担减排成本并导致其均衡价格的小幅上升。 相似文献
998.
Monitoring of subsurface fluid (underground fluid) is an important part of efforts for earthquake prediction in China. The nationwide network, which monitors groundwater level, water temperature, and radon and mercury in groundwater, has been constructed in the last decades. Large amounts of abnormal fluid changes before and after major earthquakes have been recorded, providing precious data for research in earthquake sciences. Many studies have been done in earthquake fluid hydrogeology in order to probe the nature of the earthquake. Much progress in earthquake fluid hydrogeology has been made in the last decades. The paper provides a review of the advances in research on earthquake fluid hydrogeology over the last 40 years in China. It deals with the following five aspects: (1) an introduction to the development history of monitoring networks construction; (2) cases of different subsurface fluid changes recorded before some major earthquakes which occurred in the last decades; (3) characteristics of subsurface fluid changes following major earthquakes; (4) mechanism of subsurface fluid changes before and following earthquakes; (5) application of earthquake fluids in the hydrogeology field. 相似文献
999.
基于加权Voronoi图的北京市湿地功能分区研究 总被引:1,自引:0,他引:1
湿地功能分区是城市湿地生态系统健康恢复、管理改善,以及资源可持续利用的重要前提。本文以北京湿地为例,利用客观赋权的主成分分析法对湿地生态服务功能进行综合评价;并结合空间分析中的Voronoi图空间分区方法,通过利用牛顿-断裂点模型确定属性权重的主要步骤,构建基于加权Voronoi图的城市湿地功能分区模型,开展"自下而上"定量化的北京湿地功能分区研究。结果表明:(1)北京湿地功能综合评价中,密云水库湿地的功能综合值最大,表明该湿地生态服务功能作用最重要。(2)北京湿地功能分区分为三级框架,其中包括4个一级核心湿地功能区、15个二级核心湿地功能区、43个三级核心湿地单元。(3)湿地资源功能价值量与湿地斑块空间关系的相结合,实现了属性和空间双重距离约束的湿地功能分区,促进了湿地生态系统服务价值评估在决策管理中的深入应用,为城市湿地功能区划提供技术支持。 相似文献
1000.
GUO Huihui BAO Zhenmin DU Huixia ZHANG Lingling WANG Shi SUN Luyang MOU Xiaoyu HU Xiaoli 《中国海洋大学学报(英文版)》2013,12(1):97-102
Cytochrome P450 (CYP) superfamily is one of the membership largest and function most diverse protein superfamily recogniozed among living beings. Members of this superfamily were further assigned to different families and subfamilies based on their amino acid similarities. According to their phylogenetic relationships, the CYP genes which likely diverged from common ancestor gene and may share common functions were grouped into one clan. Widely distributing scallops are a group of the most conspicuous bivalve; however the studies on their CYP is acarce. In this study, we searched the genome and expressed sequence tags of Zhikong scallop (Chlamys farreri) for CYP genes. In total, 88 non-redundant CYP were identified, which were homed in 13 CYPs gene families. Phylogenetic analysis divided these genes into 4 CYP clans. As in deuterostomes, Clan 2 was the largest, which contained 33 genes belonging to CYP1, CYP2, CYP17 and CYP356 families. Clan 3 contgained 19 genes belonging to CYP3, CYP5 and CYP30 families. Clan 4 contained 23 genes, all belonging to CYP4 family. The mitochondrial CYP clan contained 9 genes belonging to CYP10 and CYP24 families. In comparison, protostomes (C. farreri, D. pluex, D. melanogaster) contained more CYP genes than deuterostomes (S. purpuratus and vertebrates) in Clan 2 but less genes in Clan 3 and Clan 4. Our findings will aid to deciphering CYP function and evolution in scallops and bivalves. 相似文献