大亚湾海域多环芳烃和有机氯农药的高分辨率沉积记录   总被引：6，自引：0，他引：6  

池继松  颜文  张干  郭玲利  刘国卿  刘向  邹世春 《热带海洋学报》2005,24(6):44-52

以GC／ECD和GC／MS内标法分析测定了大亚湾沉积物柱样（DYW03—8）中多环芳烃（PAHs）和有机氯农药（0CPs）的含量，结合^210Pb定年，重建了该海域近50年来PAHs和OCPs的污染历史，并对其可能的来源和输入途径进行了探讨。结果表明，近50年来该海域沉积物中PAHs和OCPs的含量总体上均呈上升趋势，且一般都在上世纪90年代以后这种上升变得更加明显；PAHs主要来源于化石燃料的不完全燃烧，即热成因，并可能主要通过大气颗粒物沉降以及工业和生活污水的直接排放等途径进入水体沉积物中；HCHs和DDTs的组成特征及其变化趋势揭示，该区可能曾大量使用过林丹（γ-HCHs）作为杀虫剂，近15年来随着该地区各种经济开发活动的加强，残留在土壤中的这些农药组分更多地随地表径流进入到水体沉积物中。同时，DDTs类农药也可能仍存在新的输入源，但这种输入的强度在近几年似乎有所减弱。  相似文献   

论糜棱岩的分类   总被引：4，自引：0，他引：4  

甘盛飞  邱玉民 《现代地质》1994,8(1):73-78

糜棱岩是在构造应力作用下发生明显塑性变形、具有明显的运动指向标志、集中呈带状产出的构造岩。根据实用性和目的性建立庆棱岩的描述性和成因两个分类系列。在描述性分类中,将糜棱岩分为细粒糜棱岩、中粒糜棱岩和粗粒糜棱岩３个类型。各类型再进一步分为均匀、均匀碎斑和非均匀碎斑３个亚类。在成因分类中,将糜棱岩分为低温脆一韧性糜棱岩、中温韧性糜棱岩和高温超韧性糜棱岩３个类型,再分为低温石英脆一韧性糜棱岩、中温石英韧性糜棱岩、中温石英一斜长有韧性糜棱岩及高温斜长石一钾长石超韧性糜棱岩、高温钾长石一辉石超韧性糜棱岩、高温辉石－橄榄石超韧性糜棱岩６个亚类。  相似文献   

Perspective of urban land use in Beijing   总被引：1，自引：0，他引：1  

Guo-hui Gan Dr. 《GeoJournal》1990,20(4):359-364

This paper illustrates the features of urban land use in Beijing and approaches the factors particularly influencing the urban internal structure model. The brief review of the development process proves that the historical background and human decisions determined the basic framework of the structure. The spatial structure of land use shows that Beijing still keeps the characteristics of an industrialized city due to the importance of industry. Another particular feature was the absence of a central business district in Beijing, although in socialist system urban spatial structure also displays zonal, sectoral and star forms. The particular form in Beijing is the separated integrated district as the basic subdistrict. Finally the urban problems are discussed and suggestions made.  相似文献   

1605年琼山大地震强余震震级参数的研究   总被引：3，自引：0，他引：3  

符干  沈繁銮 《华南地震》2006,26(1):37-46

根据文献[1～18]提供的史料,研究了1605年琼山大地震的前震及强余震的时间、震感范围、烈度和震级等参数问题。最后讨论了琼山大地震的强余震震级参数估算中存在的误差问题。  相似文献   

三万年来南沙海区古环境重建:生物标志物定量与单体碳同位素研究   总被引：6，自引：3，他引：6  

胡建芳  彭平安  贾国东  房殿勇  张干  傅家谟  汪品先 《沉积学报》2003,21(2):211-218

17962钻孔沉积物提供了南沙海区3万年来古气候、古环境变化的高分辨沉积记录。通过对314个柱状样沉积物进行有机分析，提取了相关的古环境信息，揭示出南沙海区末次冰期的古海洋环境及古气候是不稳定的，水生生物来源的生物标志物沉积通量在冰期出现了较大的波动，H3时出现了海洋生产力增大事件；陆源指标如高碳类脂物的沉积通量，既反映了陆源物对南沙海区海洋沉积的贡献，又揭示了造成末次冰期南沙海区陆源物质增高的古气候事件。高碳正烷烃、长链脂肪醇、长链脂肪酸的单体化合物碳同位素δ^13C值:—34．2‰-—28．6‰、—35．8‰-—26．6‰、—31．8‰-—27．1‰都显示其陆源C3植物输入的特征，末次冰期的普遍的干旱化在这一地区并不存在。这些化合物的堆积速率在H3都出现了极大值，反映出在南海海平面降低，巽它陆架出露背景下这一时期丰富的季风降雨导致河流洪水泛滥，从而引起南沙海区输入的陆源营养元素增多，海洋表层生产力增高。  相似文献   

Active tectonic blocks and strong earthquakes in the continent of China   总被引：4，自引：0，他引：4  

Peizhen Zhang  Qidong Deng  Guomin Zhang  Jin Ma  Weijun Gan  Wei Min  Fengying Mao  Qi Wang 《中国科学D辑(英文版)》2003,46(2):13-24

The primary pattern of the late Cenozoic to the present tectonic deformation of China is characterized by relative movements and interactions of tectonic blocks. Active tectonic blocks are geological units that have been separated from each other by active tectonic zones. Boundaries between blocks are the highest gradient of differential movement. Most of tectonic activity occurs on boundaries of the blocks. Earthquakes are results of abrupt releases of accumulated strain energy that reaches the threshold of strength of the earth’s crust. Boundaries of tectonic blocks are the locations of most discontinuous deformation and highest gradient of stress accumulation, thus are the most likely places for strain energy accumulation and releases, and in turn, devastating earthquakes. Almost all earthquakes of magnitude greater than 8 and 80%–90% of earthquakes of magnitude over 7 occur along boundaries of active tectonic blocks. This fact indicates that differential movements and interactions of active tectonic blocks are the primary mechanism for the occurrences of devastating earthquakes.  相似文献   

Movement of Ordos block and alternation of activity along its boundaries     

Junxi Fan  Jin Ma  Weijun Gan 《中国科学D辑(英文版)》2003,46(2):168-180

The GPS data in and around the Ordos block area indicate that the left-lateral slip rate along the northern or southern margin of the Ordos block is about twice or three times as fast as the right-lateral slip rate along the eastern or western margin of the block. However, many researchers stressed the dextral-slip of the eastern or western boundaries of the Ordos block, and suggested that the block as a whole rotated counterclockwise based on the available geological data. Focusing on the inconsistency, we reexamine the late Cenozoic deformation pattern in the Ordos region based on seismicity data and geodesy data (GPS and leveling) around it. The results indicate that the rigid block-like motion appears to be the basic characteristic of the kinematics of the Ordos region, and this motion is absorbed by the displacement of the faults around the block. When the faults along the northern and southern boundaries of the Ordos block are active, its eastern boundary is inactive. However, if the faults along the eastern boundary are active, the northern and southern are inactive. In recent years, the northern and southern boundaries of the Ordos block are in active. But in the long term, the Ordos block is moving southeastward relative to the Alxa and Yinshan blocks because of the strong pushing of the Tibetan Plateau on its southwestern side, and this deformation is accommodated by the counterclockwise rotation of the block itself.  相似文献   

对银川地磁台磁通门磁力仪观测数据的初步分析     

李万胜  陈春梅  金延龙  韩德胜 《地震地磁观测与研究》2003,24(1):39-45

选取2001年1月－6月中美合作项目（SMALL）中磁通门磁力仪的数据和同期磁变仪的数据进行对比分析。结果表明，两种仪器记录的日变形态、日变幅、极值及极值时间具有较好的一致性，说明该项目中磁通门磁力仪的资料真实可靠。给出的典型地磁脉动事件表明，该仪器可提供精确定时的高质量地磁资料。  相似文献   

Removal of Cu（ Ⅱ） from Wastewater Using Acidified Sewage Sludge Ash     

GanYiqun WangYanxin ZhangCongjun 《中国地质大学学报(英文版)》2004,15(3):290-294

Sewage sludge ash (SSA), the waste generated in sewage sludge incineration, was obtained from Wuhan Sewage Treatment Plant and used as a low-cost sorbent for removing Cu (Ⅱ) from wastewaters. The sorbent was first modified with 5 % sulfuric acid to increase its sorption capacity. The specific surface area, porosity, cation-exchange capacity (CEC) and pHzzc of the sorbent were measured. Batch experiments were made to study the effect of contact time, solution pH value and temperature on sorption. Both Langmuir and Freundlich models well described the Cu (Ⅱ) sorption process,with correlation coefficient (R2 ) values of 0. 993 4 and 0.9899 respectively. And the sorption process follows the Lagergren first order kinetic model. The equilibrium sorption capacity of acidified SSA to Cu(Ⅱ) is estimated to be 7.78 mg/g under optimal conditions.  相似文献   

An Invariable Point in the Energy Spectra of Non-Thermal Electrons of Solar Flares     

W.Q. Gan 《Astrophysics and Space Science》1998,260(4):515-519

The power-law energy spectra of non-thermal electrons for each 1.024 second have been drawn together during the flare. For some flares, it is discovered that the energy spectra taken at different times present a roughly fixed crossing point, at which point the flux of non-thermal electrons keeps the same during the flare. The possible significance of this phenomenon is discussed. We conjecture that there may be a flux saturation at the low-energy cutoff in the process of electron acceleration.  相似文献