昆仑Ms 8.1地震前青藏块体北、东缘水平运动变形的关联特征   总被引：2，自引：0，他引：2  

王双绪  张希  张晓亮 《中国地震》2005,21(1):41-49

青藏块体东北缘和川滇GPS监测区1991(1993)、1999和2001年高精度GPS观测资料揭示：2001年11月14日昆仑Ms8．1地震前，青藏块体北、东缘构造区域水平运动变形场动态演变具有一定的关联性特征。即：在继承性运动总体背景下，临近大震发生时两区域运动强度同步减弱且变形状态发生变化。结合地质构造分析研究认为，昆仑Ms8．1地震前，青藏块体边界运动变形的关联性变化与大震孕育后期大范围应力应变快速积累所形成的扰动应力场有关；随着块体内部大震的发生、应变能的大量释放和构造应力场的调整，可能会促使块体边界地带具有较高应变积累的相关构造部位(尤其是未被历史强震破裂贯通的地带)的应力应变的进一步积累或破裂释放。  相似文献   

区域生态地球化学评价核心与对策   总被引：30，自引：1，他引：30       下载免费PDF全文

杨忠芳  奚小环  成杭新  周国华  陈德友  张建新  袁晓军  冯海艳  陈家玮  刘爱华  汤奇峰  余涛 《第四纪研究》2005,25(3):275-284

生态地球化学是地学与土壤学、农业、环境学和生态学等多学科交叉融合产生的新学科,是地球化学领域新的发展方向。区域生态地球化学评价是在区域地球化学调查基础上,针对影响流域/区带生态系统安全性的元素异常而开展的一项评价和研究工作。多目标区域地球化学调查获得的海量高精度地球化学数据,可为环境质量评价提供背景值、为土地的质量和生态管护提供地球化学依据;调查还发现了一系列影响流域生态安全性的元素异常,针对异常元素分布特征,区域生态地球化学评价将开展异常元素追踪和成因甄别、生态效应评价和生态系统安全性的预警预测等项评价和研究工作。文章论述了区域地球化学调查成果,介绍了区域地球化学评价的思路,阐述了区域生态地球化学评价的主要问题与对策。  相似文献   

Geochemical Information Indicating the Water Recharge to Lakes and Immovable Megadunes in the Badain Jaran Desert   总被引：1，自引：0，他引：1  

CHEN Jiansheng  ZHAO Xi  SHENG Xuefeng  Wang Jiyang  GU Weizu  and CHEN Liang State Key Laboratory of Hydrology-Water Resources  Hydraulic Engineering  Hohai University  Nanjing  Jiangsu  E-mail: jschen@hhu.edu.cn Institute of Isotope Hydrology Research  Hohai University  Nanjing  Jiangsu Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing 《《地质学报》英文版》2005,79(4):540-546

1 Introduction The Badain Jaran Desert, located in western Inner Mongolia, China, has a unique landscape containing 144 lakes (72 of which are still watery) with a total water area of about 23 km2, and the world’s highest stationary sand dunes with a height between 200 m and 500 m. Much attention has been paid to the water recharge of the desert in the past decade. Investigations on the resources of water system there have been performed continuously since the early 1990s, which lead to th…  相似文献   

Full and ideal mixing behavior between Zr–Wd (K2ZrSi3O9) and Ti–Wd (K2TiSi3O9): evidences from mineral chemistry,X-ray diffraction pattern and Raman spectrum     

Linlin Chang  Xi Liu  Chunming Wu  Xiaoyang Liu  Guowu Li 《Physics and Chemistry of Minerals》2015,42(3):223-234

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Using hysteretic behaviour and hydrograph classification to identify hydrological function across the “hillslope–depression–stream” continuum in a karst catchment     

Runrun Zhang  Xi Chen  Zhicai Zhang  Chris Soulsby 《水文研究》2020,34(16):3464-3480

In cockpit karst landscapes, fluxes from upland areas contribute large volumes of water to low-lying depressions and stream flow. Hydrograph hysteresis and similarity between monitoring sites is important for understanding the space–time variability of hydrologic responses across the “hillslope–depression–stream” continuum. In this study, the hysteretic feature of hydrographs was assessed by characterizing the loop-like relationships between responses at upstream sites relative to subsurface discharge at the outlet of a small karst catchment. A classification of hydrograph responses based on the multi-scale smoothing Kernel -derived distance classifies the hydrograph responses on the basis of similarities between hillslope and depression sites, and those at the catchment outlet. Results demonstrate that the temporal and spatial variability of hydrograph hysteresis and similarity between hillslope flow and outlet stream flow can be explained by the local heterogeneity of depression aquifer. Large depression storage deficits emerging in the highly heterogeneous aquifer produce strong hysteresis and multiple relationships of upstream hydrographs relative to the outlet subsurface discharge. In contrast, when depression storage deficits are filled during consecutive rainfall events, depression hydrographs at the high permeability sites are almost synchronous or exhibit a monotonous function with the hydrographs at the outlet. This reduced hydrograph hysteresis enhances preferential flow paths in fractured rocks and conduits that can accelerate the hillslope flow to the outlet. Therefore, classification of hydrograph similarities between any upstream sites and the catchment outlet can help to identify the dominant hydrological functions in the heterogeneous karst catchment.  相似文献   

Water uptake of riparian plants in the lower Lhasa River Basin,South Tibetan Plateau using stable water isotopes     

Wenbo Rao  Xi Chen  Karina T. Meredith  Hongbing Tan  Man Gao  Jintao Liu 《水文研究》2020,34(16):3492-3505

Riparian plants can adapt their water uptake strategies based on climatic and hydrological conditions within a river basin. The response of cold-alpine riparian trees to changes in water availability is poorly understood. The Lhasa River is a representative cold-alpine river in South Tibet and an under-studied environment. Therefore, a 96 km section of the lower Lhasa River was selected for a study on the water-use patterns of riparian plants. Plant water, soil water, groundwater and river water were measured at three sites for δ¹⁸O and δ²H values during the warm-wet and cold-dry periods in 2018. Soil profiles differed in isotope values between seasons and with the distance along the river. During the cold-dry period, the upper parts of the soil profiles were significantly affected by evaporation. During the warm-wet period, the soil profile was influenced by precipitation infiltration in the upper reaches of the study area and by various water sources in the lower reaches. Calculations using the IsoSource model indicated that the mature salix and birch trees (Salix cheilophila Schneid. and Betula platyphylla Suk.) accessed water from multiple sources during the cold-dry period, whereas they sourced more than 70% of their requirement from the upper 60–80 cm of the soil profile during the warm-wet period. The model indicated that the immature rose willow tree (Tamarix ramosissima Ledeb) accessed 66% of its water from the surface soil during the cold-dry period, but used the deeper layers during the warm-wet period. The plant type was not the dominant factor driving water uptake patterns in mature plants. Our findings can contribute to strategies for the sustainable development of cold-alpine riparian ecosystems. It is recommended that reducing plantation density and collocating plants with different rooting depths would be conducive to optimal plant growth in this environment.  相似文献   

Assessing effects of “source-sink” landscape on non-point source pollution based on cell units of a small agricultural catchment     

WANG Jin-liang  CHEN Cheng-long  NI Jiu-pai  XIE De-ti  GUO Xi  LUO Zhi-jun  ZHAO Yue 《山地科学学报》2019,(9)

Ascertaining the relationship between "source-sink" landscape and non-point source(NPS) pollution is crucial for reducing NPS pollution, however, it is not easy to realize this target on cell unit scale. To reveal the relationships between "sourcesink" landscape and NPS pollution based on cell units of a small catchment in the Three Gorges Reservoir Region(TGRR), the runoff and nutrient yields were simulated first by rainfall events on a cell unit scale based on the Annualized AGricultural Non-Point Source Pollution Model(AnnAGNPS). Landscape structure and pattern were quantified with "sourcesink" landscape indicators based on cell units including landscape area indices and locationweighted landscape indices. The results showed that:the study case of small Wangjiagou catchment highlighted a good prediction capability of runoff and nutrient export by the AnnAGNPS model. Throughout the catchment, the spatial distribution trends of four location-weighted landscape indices were similar to the trends of simulated total nitrogen(TN) and total phosphorus(TP), which highlighted the importance of spatial arrangement of "source" and "sink" landscape types in a catchment when estimating pollutant loads. Results by Pearson correlation analysis indicated that the location-weighted landscape index provided a more comprehensive account of multiple factors, and can better reflect NPS-related nutrient loss than other landscape indices applied in single-factor analysis. This study provides new findings for applying the "source-sink" landscape indices based on cell units in small catchments to explain the effect of "source-sink" landscape on nutrient export based on cell unit, and helps improve the understanding of the correlation between "source-sink" landscape and NPS pollution.  相似文献   

连云港近海紫菜养殖区遥感识别、空间变异和驱动分析     

卢霞  顾杨  王晓静  林雅丽  赵倩  王凯  刘笑楠  费鲜芸 《海洋科学》2018,42(7):87-96

为了科学有效地掌握海域使用信息、管理海域权属,为海域资源调查、管理、规划、保护、合理利用提供服务,为违法、违规、违章用海项目得到有效遏制,减少用海矛盾,有必要开展海域使用动态监测,作者以连云港近海为研究区,利用4个时相Landsat遥感影像(2002、2008、2013、2016年)通过面向对象算法提取弱水背景下的紫菜养殖区信息,揭示空间分异规律,并分析其驱动原因。研究结果表明:4期影像提取连云港近海紫菜养殖区信息的精度分别是87.5%、92%、91.7%和94.6%。紫菜养殖区空间分布的变化规律为紫菜养殖面积不断增加且整体向深海方向推进。赣榆港口航运区和田湾核电站特殊利用区存在少量紫菜养殖区,项目用海不符合连云港市海洋功能区划(2016～2020年)。连云港近海紫菜养殖区空间分异的驱动因子主要是自然条件、养殖技术、海洋经济和社会发展四大因素。  相似文献   

Application of computational fluid dynamics simulation for submarine oil spill     

YANG Zhenglong  YU Jianxing  LI Zhigan  CHEN Haicheng  JIANG Meirong  CHEN Xi 《海洋学报(英文版)》2018,37(11):104-115

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保持局域特征的多源海冰图像融合与分类     

余志强  王廷伟  张晰  张杰  任鹏 《海洋学报(英文版)》2019,38(7):129-136

本文提出一种保持局域特征的多源海冰图像融合方法，并在此基础上进行海冰分类。本文提出的多源海冰图像融合方法包括保持空间局域融合和保持特征局域融合两方面。首先，通过学习得到投影矩阵和相似矩阵。投影矩阵将多源像素进行投影变换，得到保留像素空间局域特性的融合向量。相似矩阵度量像素特征间的相似性，通过拉普拉斯特征分解，得到保留像素特征局域相似性的融合向量。然后，将空间融合向量和特征融合向量进行像素综合，得到融合图像。在此基础上，本文设计一种滑动集成分类方法进行融合图像像素分类。提出的分类方法利用滑动集成的特点，在分类时增强刻画了海冰局域特性。由于本文的保持局域融合框架不仅刻画了海冰在物理空间中的邻接关系，而且考虑不同海冰类型的特征关系，因此其在多源图像（多光谱和合成孔径雷达（SAR）图像）的海冰分类任务中表现优异。实验结果表明本文提出的基于保持局域特征融合的多源海冰图像分类方法有效提升了海冰分类精度。  相似文献