龙门山地区历史强震数值模拟

考虑区域地质构造差异、主要活动断裂分布特征和地表附加重力影响,建立反映龙门山地区地表起伏和岩石圈分层的三维粘弹性有限元模型。以GPS为约束重建研究区现今构造应力场,依次模拟龙门山地区1900年以来发生的5次M_S 7.0以上地震,从库仑应力和等效应力角度,分析应力场演化对强震的影响以及强震间的相互作用关系。研究结果表明:从库仑应力角度,有3次地震对后续地震有促进作用,其中汶川地震对芦山地震有触发作用;从等效应力角度,有4次地震对后续地震的发生具有加速作用。     

Trend analysis of nutrient loadings in a large prairie catchment

Nutrient loadings in many river catchments continue to increase due to rapid expansion of agriculture, urban and industrial development, and population growth. Nutrient enrichment of water bodies has intensified eutrophication which degrades water quality and ecosystem health. In this study, we carried out a trend analysis of total phosphorus and total nitrogen loads in the South Saskatchewan River (SSR) catchment using a novel approach to analyse nutrient time series. Seasonal analysis of trends at each of the water quality stations was performed to determine the relationships between annual flow regimes and nutrient loads in the catchment, in particular, the influence of the high spring runoff on nutrient export. Decadal analysis was also performed to determine the long-term relationships of nutrients with anthropogenic changes in the catchment. Although it was found that seasonal and historical variability of nutrient load trends is mainly determined by streamflow regime changes, there is evidence that increases in nitrogen concentration can also be attributed to anthropogenic changes.     

Soil quality changes in land degradation as indicated by soil chemical, biochemical and microbiological properties in a karst area of southwest Guizhou, China

Not only the nutritional status and biological activity but also the soil ecological functioning or soil health has been impacted profoundly by land degradation in the karst area of southwest China where the karst ecosystems are generally considered as extremely vulnerable to land degradation under intensified land-use changes. The objectives of this study are to elucidate the changes in overall soil quality by a holistic approach of soil nutritional, biological activity, and soil health indicators in the karst area as impacted by intense cultivation and vegetation degradation. Topsoil samples were collected on selected eco-tesserae in a sequence of land degradation in a karst area of southwest Guizhou in 2004. The soil nutrient pools of organic carbon (C_org), extractable extracellular carbon (C_ext), total soil nitrogen (N_t), alkali-hydrolyzable nitrogen (N_ah), total phosphorus (P_t), available phosphorus (P_a) were analyzed by wet soil chemistry. The soil biological properties were studied by means of measurements of microbial biomass carbon (both by fumigation–extraction, FE-C_mic, and by calculation from substrate-incubation respiration, SIR-C_mic) of respiration [respiration without addition of substrates, basal respiration (BR), and potential respiration (PR) with substrate-incubation] and of soil enzyme activities (invertase, urease, and alkaline phosphatase). Soil health status was assessed by simple indices of C_mic/C_org and BR/C_mic in conjunction with bacterial community structures determined by polymerase chain reaction and denaturing gradient gel electrophoresis. While the nutritional pool parameters, such as C_org and C_ext, described basically the changes in soil life-supporting capacity with cultivation interference and vegetation declined, those parameters of biological activity such as FE-C_mic, SIR, and SIR-C_mic as well as bacterial community structures measured by molecular method evidenced well the changes in soil functioning for ecosystem health with the land degradation.     

多孔黏弹介质平面波理论及波场数值模拟

本文将黏弹固体骨架与各向异性多孔弹性模型相结合,并将地层黏弹性的特性考虑其中,更好地刻画了快P波和横波在地震频带的衰减现象。将多孔黏弹模型模拟结果同传统弹性模型模拟结果对比显示,多孔黏弹模型在模拟真实储层方面更具优势。     

新疆东天山晚古生代地壳增生和成矿作用

地壳增生和成矿作用是矿床学研究的前沿领域; 东天山作为中亚造山带的重要组成部分,在晚古生代地壳演化过程中经历了板块俯冲、碰撞造山大规模走滑剪切和后造山演化阶段,在每个构造演化阶段都伴随有地壳增生和大量有用金属元素的堆积。按照地壳增生和成矿作用关系,研究区晚古生代主要有如下几种矿床类型： 1）晚泥盆世—早石炭世增生前形成的Cu Mo Au Ag矿床; 2）早石炭世增生前形成的Fe Cu Pb Zn矿床; 3）晚石炭世—早二叠世增生后形成的造山型Cu Ni PGE矿床; 4）晚石炭世—早二叠世增生后形成的造山型Au Cu矿床。上述矿床在形成过程中既有地壳的水平增生,也有地壳的垂向增生作用,已经构成了我国重要的内生金属矿床富集区。     

辽河三角洲滨海湿地水域初级生产力研究进展

滨海湿地位于海洋与陆地生态系统的交错过渡带,具有极高的生产力和光合固碳效率,是海岸带蓝色碳汇的重要组成部分。滨海湿地生产力不仅由芦苇、翅碱蓬、红树林等陆上植被提供,水体中浮游植物的光合固碳也是提供初级生产力的重要途径。以往较多的调查和研究集中在陆上植被,而对于滨海湿地水域浮游植物和底栖微藻的报道较少。近年来随着各国政府和学者对二氧化碳排放和气候变化的关注,滨海湿地多圈层生态系统的碳循环和碳汇过程成为研究热点,而湿地水域生产力和光合固碳过程作为多圈层碳循环中重要的一个环节亦应受到足够的重视。以中国北方典型的盐沼湿地区域——辽河三角洲滨海湿地为案例,对湿地水域生产力研究进展进行综述,并对其影响因素进行讨论,以期为国家碳循环与碳中和目标调查提供参考资料。     

退火对B掺杂纳米金刚石薄膜微结构和电化学性能的影响

采用热丝化学气相沉积法制备B掺杂纳米金刚石薄膜,并对薄膜进行真空退火处理,系统研究了不同退火温度对B掺杂纳米金刚石薄膜的微结构和电化学性能的影响.结果表明,当退火温度升高到800 ℃后,薄膜的Raman谱图中由未退火时在1157,1346,1470,1555 cm^-1处的4个峰转变为只有D峰和G峰,说明晶界上的氢大量解吸附量减少;并且D峰和G峰的积分强度比I_D/I_G值变为最小,即sp²相团簇     

Modelling the effect of wave overtopping on nearshore hydrodynamics and morphodynamics around shore-parallel breakwaters

Wave overtopping nearshore coastal structures, such as shore-parallel breakwaters, can significantly alter the current circulation and sediment transport patterns around the structures, which in turn affects the formation of tombolos and salients in the nearshore area. This paper describes the implementation of a wave overtopping module into an existing depth-averaged coastal morphological mode: COAST2D and model applications to investigate the effect of wave overtopping on the hydrodynamics and morphodynamics around a group of shore-parallel breakwaters. The hydrodynamic aspects of the model were validated against a series of laboratory conditions. The model was then applied to a study site at Sea Palling, Norfolk, UK, where 9 shore-parallel segmented breakwaters including 4 surface-piercing and 5 low-crested breakwaters are present, for the storm conditions in Nov 2006. The model results were compared with laboratory data and field measurements, showing a good agreement on both hydrodynamics and morphological changes. Further analysis of wave overtopping effect on the nearshore hydrodynamics and morphodynamics reveals that wave overtopping has significant impacts on the nearshore circulation, sediment transport and the resulting morphological changes within such a complex breakwater scheme under the storm and macro-tide conditions. The results indicate the importance of including the wave overtopping in modelling nearshore morphodynamics with the presence of coastal structures.     

渤海湾表层沉积物元素地球化学分布特征与影响因素

对取自渤海湾的307个表层沉积物进行了元素测试和粒度分析。渤海湾表层沉积物的常微量元素呈现4种组合:富集于粗粒沉积区的SiO_2、Na_2O亲碎屑元素组合;富集于细粒沉积区的以Al_2O_3和重金属元素为代表的亲黏土元素组合;与缺氧环境有关的MnO、V、TOC元素组合和与河流输入有关的陆源CaO、TiO_2元素组合。粒度粗细主导了渤海湾元素含量分布的整体格局;海域河流物源供应不同较大影响了渤海湾南部(富Na_2O、CaO和SiO_2)和北部(富Ba和P_2O_5)在元素含量上的差异;高流速潮流对海底的冲刷再分配导致曹妃甸南侧Sr、Ca元素的条带状富集异常;有机质在细粒沉积区的富集导致缺氧环境的形成和K_2O、Mn、V、自生黄铁矿的海洋自生化学沉积;人类活动导致以Pb为代表的重金属污染在河流入海口、港口及沿岸海域的元素分布异常;曹妃甸沙坝内侧的泻湖(海洋钙质生物沉积)与沙坝外侧水下岸坡(陆源碎屑沉积)的截然不同的物源,导致了独特地貌沉积环境下元素分布的局部差异。     

目标采集技术在西部新区地震勘探中的应用

目标采集技术是根据复杂的地下地质构造提出来的,它是针对诸如小断层、小断块、复杂断裂带、特殊岩性、泥岩裂缝等主要地质构造目标而进行的有针对性的目标观测系统设计及目标采集施工方法设计的技术。针对目标采集的特点,在观测系统设计中提出了以地质模型正演模拟分析为核心的观测系统设计技术;在老资料分析和采集参数论证中提出了细化、量化分析技术。通过目标采集技术在西部探区的应用,有效的解决了西部新区勘探开发中广泛存在的复杂隐蔽油气藏勘探难题。