基于20a卫星高度计数据的黑潮变异特征     

赵新华  杨俊钢  崔伟 《海洋科学》2016,40(1):132-137

黑潮作为一支典型的西边界流,其路径变化特征及其相关的物理现象对于渔业和航海有着不可忽视的影响。本文基于改进的特征线方法,利用1992~2012年的高度计绝对动力地形数据提取了整个黑潮流区逐月的黑潮主轴和边界位置,并对沿轴速度、主流宽度、表层水体输运以及路径标准差等黑潮特征量进行了分析研究。结果表明,黑潮整体的沿轴速度在夏秋季较大,最大值可达0.95 m/s,而在冬季的速度较小;黑潮主流宽度在10、11月份达到最大值;黑潮表层水体输运在夏季最大,春秋两季次之,冬季最小。沿黑潮流路分区域对黑潮特征进行分析,结果表明,越往黑潮下游,其沿轴速度、主流宽度和表层水体输运越大,同时沿轴速度和表层水体输运量最大值出现的时间也越晚,黑潮主轴位置相对于其多年平均的偏离程度越大,且随时间波动也越强烈。  相似文献   

Early Mesozoic Southward Subduction of the Eastern Mongol–Okhotsk Oceanic Plate: Evidence from Zircon U–Pb–Hf Isotopes and Whole‐rock Geochemistry of Triassic Granitic Rocks in the Mohe Area,NE China          下载免费PDF全文

Liang Li  Fengyue Sun  Bile Li  Qinglin Xu  Yajing Zhang  Ye Qian 《Resource Geology》2016,66(4):386-403

In this paper, we present new U–Pb zircon ages, Hf isotope data and major and trace elements for Early Mesozoic granitic rocks in Mohe area in the Erguna Massif of northeast China to elucidate the southward subduction of the eastern Mongol–Okhotsk Oceanic plate in Early Mesozoic. Zircons from two representative intrusions, syenogranites and monzogranites, in the Mohe area are euhedral–subhedral in shape, display oscillatory growth zoning in cathodoluminescence (CL) images, and have Th/U ratios of 0.10–0.72, and in combination these features indicating that the zircons are of igneous origin. U–Pb zircon dating results demonstrate that the syenogranites formed at 245.1 ± 1.4 Ma and monzogranites formed at 212.2 ± 1.7 Ma. These granitic rocks are characterized by high SiO₂, Al₂O₃ and (Na₂O + K₂O), low TFeO, MgO, TiO₂ and P₂O₅ concentrations, belonging to the high‐K calc‐alkaline series. They are enriched in LREE and large ion lithophile elements (e.g., Rb, K, and Sr), depleted in HREE and high field strength elements (e.g., Nb, Ta, Th, and Ti), as well as very weak negative Eu anomalies (Eu/Eu* = 0.48 ~ 1.01). Their zircon εHf(t) values range from −7.9 to −2.0 and range from 0.20 to 0.49, in response to their two‐stage Hf model ages (T_DM2) range from 1.40 Ga to 1.77 Ga range from 0.94 Ga to 1.24 Ga, respectively, indicating that primary magmas of syenogranites were derived from partial melting of newly accreted juvenile crustal material that formed from the enriched mantle during the Mesoproterozoic, monzogranites are generated by partial melting of newly accreted juvenile crustal material that formed from the depleted mantle during the Meso‐ to Neoproterozoic. We conclude, therefore, that the early Mesozoic granitic rocks of the Mohe area are associated with the continuous southward subduction of the Mongol–Okhotsk oceanic plate rather than the Paleo‐Asian and circum‐Pacific tectonic regimes.  相似文献   

Distinct groundwater recharge sources and geochemical evolution of two adjacent sub-basins in the lower Shule River Basin,northwest China   总被引：2，自引：1，他引：1  

Liheng Wang  Yanhui Dong  Yueqing Xie  Fan Song  Yaqiang Wei  Jiangyi Zhang 《Hydrogeology Journal》2016,24(8):1967-1979

Based on analysis of groundwater hydrogeochemical and isotopic data, this study aims to identify the recharge sources and understand geochemical evolution of groundwater along the downstream section of the Shule River, northwest China, including two sub-basins. Groundwater samples from the Tashi sub-basin show markedly depleted stable isotopes compared to those in the Guazhou sub-basin. This difference suggests that groundwater in the Tashi sub-basin mainly originates from meltwater in the Qilian Mountains, while the groundwater in the Guazhou sub-basin may be recharged by seepage of the Shule River water. During the groundwater flow process in the Tashi sub-basin, minerals within the aquifer material (e.g., halite, calcite, dolomite, gypsum) dissolve in groundwater. Mineral dissolution leads to strongly linear relationships between Na⁺ and Cl^? and between Mg²⁺+ Ca²⁺ and SO₄ ^2??+?HCO₃ ^?, with stoichiometry ratios of approximately 1:1 in both cases. The ion-exchange reaction plays a dominant role in hydrogeochemical evolution of groundwater in the Guazhou sub-basin and causes a good linear relationship between (Mg²⁺+ Ca²⁺)–(SO₄ ^2??+?HCO₃ ^?) and (Na⁺+ K⁺)–Cl^? with a slope of ?0.89 and also results in positive chloroalkaline indices CAI 1 and CAI 2. The scientific results have implications for groundwater management in the downstream section of Shule River. As an important irrigation district in Hexi Corridor, groundwater in the Guazhou sub-basin should be used sustainably and rationally because its recharge source is not as abundant as expected. It is recommended that the surface water should be used efficiently and routinely, while groundwater exploitation should be limited as much as possible.  相似文献   

Variations of Hydrodynamics and Submarine Groundwater Discharge in the Yellow River Estuary Under the Influence of the Water-Sediment Regulation Scheme   总被引：1，自引：0，他引：1  

Dong Xia  Zhigang Yu  Bochao Xu  Maosheng Gao  Tiezhu Mi  Xueyan Jiang  Peng Yao 《Estuaries and Coasts》2016,39(2):333-343

The “Water-Sediment Regulation Scheme” (WSRS) is critically important to the hydrologic evaluation of the Yellow River estuary since a huge pulse of water and sediment are delivered into the sea during a short period. We used the natural geochemical tracers radium (²²³Ra, ²²⁴Ra, ²²⁶Ra) and radon (²²²Rn) isotopes as well as other hydrological parameters to investigate the mixing variations and submarine groundwater discharge (SGD) in the Yellow River estuary under the influence of the 2013 WSRS. Dramatically elevated radium and radon isotopic activities were observed during this WSRS compared with activities measured during a non-WSRS period. Radium “water ages” indicated that the offshore transport rate nearly tripled when the river discharge increased from 400 to 3400 m³/s. We calculated the SGD flux in the Yellow River estuary based on a radium mass balance model as well as radium and radon time-series models. The SGD flux was estimated at 0.02~0.20 m/day during a non-WSRS period and 0.67~1.22 m/day during the 2013 WSRS period. The results also indicate that large river discharge tends to lead more intense SGD along the river channel direction with a large amount of fresh SGD.  相似文献   

Quantities and Fluxes of Dissolved and Particulate Black Carbon in the Changjiang and Huanghe Rivers,China     

Caili Xu  Yuejun Xue  Yuanzhi Qi  Xuchen Wang 《Estuaries and Coasts》2016,39(6):1617-1625

Recent studies have suggested that large rivers play important roles in mobilizing and transporting black carbon (BC) from land to the ocean. However, the influence of the Changjiang and Huanghe, the two largest rivers in China, on the fate of BC has not been determined. In this paper, we present measurements of BC in both the dissolved and particulate phases in the Changjiang and Huanghe Rivers and in the coastal waters of the East China Sea (ECS). Our results show that dissolved black carbon (DBC) accounted for 3.0 ± 0.4 % and 4.8 ± 3.6 % of the total DOC pool in the Changjiang and Huanghe Rivers and 3.4 ± 0.6 % of the DOC pool in the coast of the ECS. In addition, particulate black carbon (PBC) accounted for 13 ± 0.9 % and 22 ± 11 % of the POC pool in the Changjiang and Huanghe Rivers, respectively. We calculate that the Changjiang and Huanghe transported 4.7 × 10¹⁰ gC and 1.7 × 10⁹ gC of DBC, and 2.0 × 10¹¹ gC and 1.2 × 10¹⁰ gC of PBC to the ECS and Bohai Sea in 2015. The large amounts of BC transported by the two rivers represent a major sink of anthropogenically derived organic carbon and could have a significant impact on the ecosystem and carbon cycling in China’s marginal seas.  相似文献   

Two-dimensional landslide dynamic simulation based on a velocity-weakening friction law   总被引：3，自引：3，他引：0  

Wei Liu  Siming He  Xinpo Li  Qiang Xu 《Landslides》2016,13(5):957-965

Surprisingly, hypermobility (high velocity and long run-out) is a remarkable feature of large landslides and is still poorly understood. In this paper, a velocity-weakening friction law is incorporated into a depth-averaged landslide model for explaining the higher mobility mechanism of landslides. In order to improve the precision of the calculation, a coupled numerical method based on the finite volume method is proposed to solve the model equations. Finally, several numerical tests are performed to verify the stability of the algorithm and reliability of the model. The comparison between numerical results and experimental data indicates that the presented model can predict the movement of landslide accurately. Considering the effect of velocity-weakening friction law, the presented model can better reflect the hypermobility of landslide than the conventional Mohr–Coulomb friction model. This work shows that the application of a universal velocity-weakening friction law is effective in describing the hypermobility of landslide and predicting the extent of landslides.  相似文献   

Comprehensive analyses of the initiation and landslide-generated wave processes of the 24 June 2015 Hongyanzi landslide at the Three Gorges Reservoir,China   总被引：1，自引：1，他引：0  

Jia-wen Zhou  Fu-gang Xu  Xing-guo Yang  Yu-chuan Yang  Peng-yuan Lu 《Landslides》2016,13(3):589-601

Reservoir landslides pose a great threat to shipping safety, human lives and properties, and the operation of the hydropower station. In this paper, the 24 June 2015 Hongyanzi landslide at the Three Gorges Reservoir is considered as an example to study the initiation mechanism and landslide-generated wave process of a reservoir landslide. The finite difference method and limit equilibrium analysis are used to analyze the deformation and failure characteristics of the Hongyanzi slope. Simulation results show that a large deformation (about 358 mm) happens in the shallow deposits under intermittent rainfall condition, and the slope is in a limit state. At the same time, continuous rapid drawdown of the water level (about ?0.55 m/day during 8–24 June 2015) reduced the support and accelerated the drainage of the water for the bank slope. A coupling effect of intermittent rainfall and rapid drawdown of the water level was the triggering factor of the 24 June Hongyanzi landslide. Landslide-generated wave process was simulated using a fluid–solid coupling method by integrating the general moving object collision model. Simulation results show that the landslide-generated wave is dominated by the impulse wave, which is generated by sliding masses entering the river with high speed. The maximum wave height is about 5.90 m, and the wave would decay gradually as it spreads because of friction and energy dissipation. To prevent reservoir landslides, the speed for the rising or drawdown of the water level should be controlled, and most importantly, rapid drawdown should be avoided.  相似文献   

Molybdenum Mass Fractions and Isotopic Compositions of International Geological Reference Materials          下载免费PDF全文

Pei‐Pei Zhao  Jie Li  Le Zhang  Zhi‐Bing Wang  De‐Xin Kong  Jin‐Long Ma  Gang‐Jian Wei  Ji‐Feng Xu 《Geostandards and Geoanalytical Research》2016,40(2):217-226

The double‐spike method with multi‐collector inductively coupled plasma‐mass spectrometry was used to measure the Mo mass fractions and isotopic compositions of a set of geological reference materials including the mineral molybdenite, seawater, coral, as well as igneous and sedimentary rocks. The long‐term reproducibility of the Mo isotopic measurements, based on two‐year analyses of NIST SRM 3134 reference solutions and seawater samples, was ≤ 0.07‰ (two standard deviations, 2s, n = 167) for δ^98/95Mo. Accuracy was evaluated by analyses of Atlantic seawater, which yielded a mean δ^98/95Mo of 2.03 ± 0.06‰ (2s, n = 30, relative to NIST SRM 3134 = 0‰) and mass fraction of 0.0104 ± 0.0006 μg g^?1 (2s, n = 30), which is indistinguishable from seawater samples taken world‐wide and measured in other laboratories. The comprehensive data set presented in this study serves as a reference for quality assurance and interlaboratory comparison of high‐precision Mo mass fractions and isotopic compositions.  相似文献   

The August 27, 2014, rock avalanche and related impulse water waves in Fuquan,Guizhou, China   总被引：1，自引：1，他引：0  

Aiguo Xing  Qiang Xu  Yaoqiang Zhu  Jiliang Zhu  Yao Jiang 《Landslides》2016,13(2):411-422

At about 8:30 p.m. on 27 August 2014, a catastrophic rock avalanche suddenly occurred in Fuquan, Yunnan, southwestern China. This landslide and related impulse water waves destroyed two villages and killed 23 persons. The impulse waves occurred after initiation of the landslide, caused by the main part of the slide mass rapidly plunging into a water-filled quarry below the source area. The wave, comprising muddy water and rock debris, impacted the opposite slope of the quarry on the western side of the runout path and washed away three homes in Xinwan village. Part of the displaced material traveled a horizontal distance of about 40 m from its source and destroyed the village of Xiaoba. To provide information for potential landslide hazard zonation in this area, a combined landslide–wave simulation was undertaken. A dynamic landslide analysis (DAN-W) model is used to simulate the landslide propagation before entering the quarry, while Fluent (Ansys Inc., USA) is used to simulate the impulse wave generation and propagation. Output data from the DAN-W simulation are used as input parameters for wave modeling, and there is good agreement between the observed and simulated results of the landslide propagation. Notably, the locations affected by recordable waves according to the simulation correspond to those recorded by field investigation.  相似文献   

经略21世纪海上丝路:重要航线、节点及港口特征   总被引：1，自引：0，他引：1       下载免费PDF全文

郑崇伟  孙威  黎鑫  何方  陈璇 《海洋开发与管理》2016,33(1):4-13

为了更好地认识21世纪海上丝绸之路(简称"海上丝路"),文章对"海上丝路"涉及的重要航线、节点及港口的地理位置、气候状况、水文特征、商业价值、人文背景等进行梳理。重要航线、节点及港口的使用与管理作为"海上丝路"建设的基础要素,是与造船能力并列的核心资源,三者之间环环相扣,构成"海上丝路"健康运营的完整体系。与沿"海上丝路"国家稳步推进航线、节点及港口的管理、开发与维护,打造坚实的战略支撑点、现代之"海上驿站",是成功实现我国资源多样化、产业走出去、贸易全球化的最佳路径之一,以此为契机,融入现有国际海洋法公约并在践行过程中制定利我的海上政策体制,助力"海之梦"、"中国梦"。  相似文献