长江河口南汇嘴潮滩近期演变分析   总被引：6，自引：0，他引：6  

付桂  李九发  应铭  徐海根  虞志英 《海洋通报》2007,26(2):105-112

南汇嘴潮滩位于长江口和杭州湾的交汇地带,受长江口和杭州湾北岸两股潮流的控制,近年来由于低潮滩促淤围垦工程导致其水流和泥沙运移、沉积和地貌发生了显著的变化。根据近期水文泥沙观测资料及1993年、1998年、2003年、2005年的实测地形图资料,分析了南汇嘴潮滩近期演变特征。研究结果表明:1993-1998年为淤涨期;1998-2003年为冲淤调整期;2003-2005年呈现向外淤涨的趋势。而造成这一趋势的原因主要包括潮滩海洋动力作用、长江入海泥沙变化及近岸海岸工程建设等。  相似文献   

Research progress and prospect on development geography     

Deng  Xiangzheng  Jin  Gui  He  Shujin  Wang  Chengxin  Li  Zhaohua  Wang  Zhanqi  Song  Malin  Yang  Qingyuan  Zhang  Anlu  Chen  Jiancheng 《地理学报(英文版)》2021,31(3):437-455

In this paper,we review the research progress in development geography since the 20th century,focusing on its connotation and theory,fields,methods,and development trends.Specifically,we systematically review the research and applications of development geography,comprising fields such as the convergence of underdeveloped countries and re-gions,and the convergence of the process of improving the quality of life in developed coun-tries and regions.Then,based on an analysis of research progress in development geogra-phy in foreign countries,we examine the development conditions and disciplinary advantages of development geography in China.Further,we highlight that future development geography research in China should focus on the latest international academic research and China's national macro-strategic needs.Future research in development geography should be guided by the theory of sustainable development,the core of which is to improve sustainable liveli-hood capacity and regional green development levels in underdeveloped regions.This core includes the construction of industrial policy and development geography theory,as well as an interdisciplinary integrated research system.The focus must be placed on researching the spatial patterns,diffusion characteristics,and the convergence mechanism of regional de-velopment.Such a focus will facilitate exploration of the regulatory policies and scientific paths that serve regional economic construction and industrial development.  相似文献   

Assessing modern arboreal phytolith sensitivity to vegetation variations in temperate forest regions     

Gui‐Zai Gao  Dong‐Mei Jie  De‐Hui Li  Nan‐Nan Li  Li‐Dan Liu  Hong‐Yan Liu  Cheng‐Cheng Leng  Jiang‐Yong Wang  Bao‐Jian Liu  Ping Li 《Boreas: An International Journal of Quaternary Research》2019,48(3):731-745

To assess the reliability of arboreal phytoliths for differentiating vegetation types in temperate forest regions, we systematically analysed arboreal leaf phytoliths from 72 arboreal plants and 49 modern soils from three forest types in northeast China. The arboreal leaf phytolith production and morphotypes were highly variable between species. The arboreal leaf phytolith assemblages could clearly distinguish between broadleaf and coniferous species, but they were much less successful in differentiating broadleaved trees into subtaxa. Coniferous leaf morphotypes were successfully used to differentiate coniferous trees into families and subtaxa, especially in the Pinaceae. Two diagnostic broadleaved and six coniferous phytolith morphotypes were recognized within the modern soil beneath forest ecosystems. These arboreal phytoliths comprised up to 10–15% of the total soil phytoliths, and were dominated by coniferous types. Arboreal phytolith concentrations and phytolith assemblages in the soils fluctuated substantially amongst the three forest types. Soil arboreal phytolith assemblages were successfully used to differentiate samples from Larix mixed forest, broadleaf forest and Pinus koraiensis mixed forest. In addition, the arboreal index quantitatively distinguished the three forest types, with B/BE values <0.4 for Larix mixed forest samples, values from 0.4 to 0.6 for broadleaf forest samples, and values from 0.6 to 0.9 for P. koraiensis mixed forest. Thus, our surface soil arboreal phytolith assemblages and arboreal index are a useful reference for differentiating forest ecotypes, and they also provide reliable analogues for arboreal phytoliths from palaeoecological contexts in temperate forest regions.  相似文献   

Stability of the lundquist field and the physical nature of eruptive prominences with helical structure     

Ao-Ao Xu  Gui Ping Wu 《Solar physics》1995,159(2):265-273

The stability of the Lundquist field is analysed in the light of the energy principle. The results show: (1) form = 0 disturbances, the Lundquist field is stable; (2) form = 1 disturbances, the Lundquist field will turn unstable in certain conditions. Whether the field will remain stable or not depends on parameters such as the helical pinch angle and radius and length of the prominence. Comparison between theory and observations reveals that a kink instability in the Lundquist field may be a critical physical reason for eruptive prominences with helical patterns.  相似文献   

基于GIS的淤泥质潮滩侵蚀堆积空间分析   总被引：13，自引：0，他引：13  

李恒鹏  杨桂山 《地理学报》2001,56(3):278-286

通过野外滩地长期水准详测资料，利用地理信息系统的GRID和TIN模块产生潮滩高程、坡度、二维剖面、侵蚀与堆积分布图，并获取测点所在位置的高程、坡度和侵蚀量，对获取的数据及空间分布图进行分析，结果表明：侵蚀主要发生在-7m以上的岸坡和潮滩，堆积主要出现于广阔的深水岸坡和7部分高滩，侵蚀速率以滩前深槽岸坡最快，年侵蚀率达17.9cm/a，并呈加速趋势，海岸线向陆后退速率为31m/a，侵蚀、堆积的闭合深度约为-9.5m，空间分布表现为自北而南的3个明显分带，即潮滩轻微侵蚀区，滩前深槽岸坡强烈侵蚀区和深水岸坡缓积区，东西向比较，东部，中部侵蚀大于西部。  相似文献   

华南新元古代裂谷盆地演化——Rodinia超大陆解体的前奏   总被引：26，自引：0，他引：26  

王剑  刘宝珺  潘桂棠 《矿物岩石》2001,21(3):135-145

沉积学研究表明，华南新元古代沉积盆地具典型裂谷盆地沉积演化特征。代表裂谷盆地早期形成阶段的成因相组合有：冲洪积相组合、陆相（或海相）火山岩及火山碎屑岩相组合、滨浅海相沉积组合、淹没碳酸盐台地及欠补偿盆地黑色页岩相组合；而代表中、后期形成阶段的成因相组合有：滨岸边缘相至深海相组合，冰期冰积岩相组合、碳酸盐岩及碳硅质细碎岩相组合。华南裂谷盆地岩相古地理演化经历了5个重要的时期，整体上反映了一个由陆变海、由地堑－地垒相间盆地变广海盆地、由浅海变深海、盆地上小变大的演化过程。裂谷盆地的形成经历了裂谷基的形成、地幔柱作用与裂谷体的形成，被动沉降（下坳）与裂谷盖的形成三个阶段。华南裂谷盆地的形成演化与Rodinia超大陆在新元古代时期的裂解作用密切相关，它是超大陆解体过程的一个重要组成部分。  相似文献   

Calcium Isotopic Fractionation during Ion‐Exchange Column Chemistry and Thermal Ionisation Mass Spectrometry (TIMS) Determination          下载免费PDF全文

Hong L. Zhu  Zhao F. Zhang  Gui Q. Wang  Yu F. Liu  Fang Liu  Xin Li  Wei D. Sun 《Geostandards and Geoanalytical Research》2016,40(2):185-194

Significant isotopic fractionation can occur during column chemistry and determination by mass spectrometry. Improper correction may produce uncertainties in the isotopic composition of geological samples. We investigated calcium isotopic fractionation during these two processes and set up a model to check data quality. The δ^44/40Ca_915a value of IAPSO seawater in different Ca cuts (e.g., 0–20, 20–40, 40–60, 60–80 and 80–100%) on column chemistry ranged from ~ 4‰ to 0‰. The more Ca was eluted, the lower the δ^44/40Ca_915a value of the elution was found. The isotopic fractionation of calcium on the column appeared to follow the exponential law. However, TIMS instrumental fractionation during Ca runs did not always follow the exponential law due to mixing effects from sample reservoirs on the filament. Our results show that errors could be caused if the instrumental fractionation deviates from the exponential law, especially when the fractionation degree is large. To improve the measurement uncertainty, a model is proposed to check the behaviour and degree of instrumental fractionation, which will provide a quick and reasonable verdict on the data quality of TIMS runs.  相似文献   

Comparison of ground temperature response of energy pile and borehole heat exchanger during thermal response tests     

Jin Luo  Haifeng Zhao  Shuqiqang Gui  Wei Xiang  Joachim Rohn 《Environmental Earth Sciences》2016,75(22):1463

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Practice and research progress on ecosystem conservation in transboundary areas     

Lina Tang  Liuming Gui  Guofan Shao  Luyan Wang  Longyu Shi 《中国地理科学(英文版)》2016,26(1):109-116

Many ecosystems extend across national or political boundaries. The consistent and effective protection of these ecosystems in transboundary areas(ETAs) is an important global research focus. Previous research on the protection of such areas can be categorized into seven themes: 1) ecological conservation of a single ETA; 2) investigation of the effects of a single conservation measure on a specific ETA; 3) determination of species-level effects due to ETA conservation; 4) comparison of the same protection measures between different ETAs; 5) introduction of a single conservation measure to a specific ETA; 6) understanding the relationship between conservation and sustainable development; and 7) generalization across multiple ETA conservation cases. The protection of ETAs involves various considerations, including funding support, demand and will for collaboration, community and public participation, historical and cultural factors, political backgrounds, uniqueness of biological resources, formulation of laws and regulations, founding of specialized administrative departments, non-governmental organizations, and fairness. Here, we briefly explain the research themes and considerations related to ETA conservation. The most important finding is that most major research themes do not focus on the challenges of ETA conservation. We use two nature reserves located between China and North Korea as examples to identify specific ways to improve ETA conservation on Changbai Mountains. The efficiency of ETA administration still remains low. The study of ETA conservation should focus on concrete regional information and aim to improve existing measures through the accumulation of experience.  相似文献   

An Extension Mechanism to Verify,Constrain and Enhance Geoprocessing Workflows Invocation   总被引：1，自引：0，他引：1       下载免费PDF全文

Kunlun Qi  Zhipeng Gui  Zhenqiang Li  Wei Guo  Huayi Wu  Jianya Gong 《Transactions in GIS》2016,20(2):240-258

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