罗斗沙岛动态变化的遥感监测     

李晓敏  张杰  马毅  李团结 《海洋学研究》2013,31(2):52-58

罗斗沙岛是我国首批公布的可以开发利用的无居民海岛之一,属于泥沙岛,岛体极不稳定,动态变化比较大。本文利用1973—2011年间12个时相的遥感影像,分析了罗斗沙岛近40 a来的动态变化情况。研究结果表明:近40 a来,罗斗沙岛的位置、形状和大小均发生了较大的变化。罗斗沙岛的动态变化可分为3个阶段:第一阶段(1987年以前),罗斗沙岛为一个完整的岛体;第二阶段(1987—2001年),罗斗沙岛被分为东北和西南两部分;第三阶段(2001年至今),罗斗沙岛的西南部分消失,仅剩下东北部分。本文的监测结果可为编制罗斗沙岛的海岛保护与利用规划、制定海岛开发利用的具体方案、提出海岛的生态保护措施等提供数据支撑,进而为罗斗沙岛的生态保护和相关部门对其进行海岛管理提供服务资料。  相似文献   

近50年海南岛红树林群落的变化及其与环境关系分析——以东寨港、三亚河和青梅港红树林自然保护区为例   总被引：2，自引：0，他引：2  

王丽荣  李贞  蒲杨婕  廖文波  张乔民  余克服 《热带地理》2010,30(2)

选取海南岛东寨港、三亚河和青梅港红树林自然保护区为研究对象,在1959年和2008年的数据基础上,分析了近50年海南岛红树林种类、群落和面积的变化与环境之间的关系。在50年内,三地的红树植物相对灭绝种类比例小,只有三亚河种类变化较大,从26种减少为20种(另有2个引入种),东寨港和青梅港则分别仅减少1种。从群落类型面积变化分析可知,50年来三地主要群落的损失率均在41﹪以上,所毁灭的群落以近岸的内缘种为优势的群落为主,主要是海莲,尖瓣海莲,木榄群落和角果木群落等,并存在单优种群落向多种混合的多优种群落的演替,种群濒危,矮化和面积碎化现象突出。50年来三地红树林总面积也大为减小,东寨港和青梅港减少53﹪左右,而三亚河则减少92﹪。近50年来红树林的变化与环境关系表明,自然环境要素梯度变化形成了红树林群落空间分布和群落垂直分层的分异性。而社会(生产)环境要素的发展过程不但改变了红树林群落空间分布格局,还影响群落种群和外貌的趋同性。  相似文献   

近50年涠洲岛5次珊瑚冷白化的海洋站SST指标变化趋势分析   总被引：1，自引：0，他引：1  

周雄  李鸣  郑兆勇  黄红海  时小军 《热带地理》2010,30(6)

根据涠洲岛海洋站实测海表温度(SST)历史资料和涠洲岛珊瑚礁普查历史资料,采用对比分析与相关分析方法,分析1960―2009年冬季珊瑚冷白化4种SST指标的变化特征。结果显示:(1)涠洲岛珊瑚冷白化的该站SST值为极端低海温(SSTMIN)≤13.2℃或最冷周海温(SSTMCW)≤14.0℃;(2)4种珊瑚冷白化SST指标呈准同步变化,无上升趋势,且其变化趋势与全球变暖无明显对应关系。  相似文献   

Source side seismic tomography(3STomo):A novelmethod to image the subsurface structure beneath seismically active region          下载免费PDF全文

Ting Yang  Shenyi Gu  Khanh Le Phon 《地震科学（英文版）》2010,23(6):637-643

We propose a novel seismic tomography method,Source Side Seismic Tomography(3STomo),which is designed particularly to image the subsurface structure beneath seismically active regions.Unlike the teleseismic tomography,in which the data are relative traveltime residuals between closely spaced stations for each teleseismic event,3STomo uses relative traveltime shifts between earthquakes within the study region for each distant station.Given the relatively evener distribution of global seismic stations,this method has unique advantages for imaging the structure beneath regions that have numerous earthquakes but lack of dense seismic stations,for example,some subduction zones and spreading ridges in the ocean.In addition,3STomo has potentially better vertical resolution at shallow depths than the traditional teleseismic tomography.The effect of the inaccurate source parameters on its resolution can be minimized by using depth phases and the technique of joint source and structure inversion.Numerical experiments and application to Luzon Island,Philippines show that 3STomo can be a valuable tool to investigate the subsurface structure beneath some areas where the traditional method cannot be applied to,or at least it can be used as a complementary component of conventional teleseismic tomography to obtain better back-azimuth coverage and achieve higher resolution at shallow depths in the inversion.  相似文献   

An indigenous soil classification system for Bellona Island – a raised atoll in Solomon Islands     

Henrik Breuning-Madsen  Thilde Bech Bruun  Bo Elberling 《Singapore journal of tropical geography》2010,31(1):85-99

One of the challenges of evaluating existing traditional farming systems is to combine local knowledge and modern scientific methods and terminology. This requires an evaluation of indigenous soil classification in modern terms. This paper focuses on an indigenous soil classification system developed by local farmers on the island of Bellona, Solomon Islands. The definitions of the different soil types are described and the principles of the classification system and the applicability of ethnopedology in soil surveys are discussed. Based on interviews with about 20 per cent of the farmers on the island as well as standard soil chemical and physical determinations on main soil types, an evaluation of the soil types for cultivation of various crops is carried out. The soils on Bellona are developed on oolitic or clayey phosphate-rich deposits forming the basis for the agriculture production on the island. The Bellonese soil classification system is mainly based on the physical properties of the humus-containing top layer. Subsoil layers are only used for classification if they are very close to the surface and may be mixed with the topsoil. Results show a general agreement among farmers, who perceive the same four out of seven soil types as highly useful for cultivation and rank these soil types similarly according to their suitability for different crops such as yam, watermelon, cassava and sweet potato. It is concluded that the indigenous soil classification is in line with the soil production potential and useful for land evaluation on Bellona.  相似文献   

中国热带琼雷生态经济区的建设构想   总被引：1，自引：0，他引：1  

张义丰  贾大猛  谭杰  宋思雨  孙瑞峰  刘春腊 《地理科学进展》2010,29(1)

生态经济区克服了传统经济区生态环境约束下的经济增长瓶颈,是区域经济发展的重要内容和方向。目前黄河三角洲高效生态经济区和鄱阳湖生态经济区的建设都已引起国家的高度关注。琼雷生态经济区是在充分考虑了湛江市(雷州半岛)和海南省(海南岛)地区热带资源禀赋、生态环境脆弱性及经济空间紧密性的基础上提出来的战略构想。琼雷地区生态本底较好;热带作物资源、海洋资源及港口资源十分丰富,热带特色显著;经济结构以一、三产业为主,生态恢复与维护成本较小;存在地缘一致性和经济紧密性,有一定区域联系基础。但同时本区域存在生态环境的脆弱性,影响区域生态安全的因素较多,因此必须坚持生态主导下的经济发展原则。为此,建立中国热带琼雷生态经济区是必要的和及时的。本文从宏观的角度,详细分析了琼雷生态经济区的功能定位和建设的主要内容,以期在中国的典型热带区域打造生态经济区发展平台,构筑中国热带生态经济发展高地。  相似文献   

海南岛古元宙变质基底性质和地壳增生的Nd、Pb同位素制约   总被引：15，自引：0，他引：15  

许德如  范蔚茗  梁新权  唐红峰 《高校地质学报》2001,7(2):146-157

基于海南地壳各类型岩石的63个样品Nd和Pb同位素分析数据,研究了海南地块元古宙地壳变质基底的时代、特征和演化。研究结果表明,海南岛元古宙变质基底成熟度低,基底变质岩系的母岩物质来源于长期亏损的地幔源区,主要形成时代为古元古宙晚期－新元古宙;不同时代花岗岩具有较高的εNd(t)值和较低的Nd模式年龄,主要形成于幔源物质参与下的或含地幔成分较多的初生地壳再循环。地壳增生具幕式增生的特点,并在2．0Ga、1.7Ga、1.2Ga出现高峰;Pb同位素组成既不同于扬子地块又不同于华夏地块,介于两地块之间,和Nd同位素特征具有一致或耦合关系。结合海南岛地质特征,初步认为不能单纯地将海南岛基底理解为华南地块统一南延部分或是华夏古陆的部分,可能为不同的构造块体。  相似文献   

Observation of baroclinic eddies southeast of Okinawa Island     

XiaoHua Zhu  Jae-Hun Park  DaJi Huang 《中国科学D辑(英文版)》2008,51(12):1802-1812

In the region southeast of Okinawa, during May to July 2001, a cyclonic and an anticyclonic eddy were observed from combined measurements of hydrocasts, an upward-looking moored acoustic Doppler current profiler (MADCP), pressure-recording inverted echo sounders (PIESs), satellite altimetry, and a coastal tide gauge. The hydrographic data showed that the lowest/highest temperature (T) and salinity (S) anomalies from a 13-year mean for the same season were respectively -3.0/ 2.5℃ and -0.20/ 0.15 psu at 380/500 dbar for the cyclonic/anticyclonic eddies. From the PIES data, using a gravest empirical mode method, we estimated time-varying surface dynamic height (D) anomaly referred to 2000 dbar changing from -20 to 30 cm, and time-varying T and S anomalies at 500 dbar ranging through about ±2 ℃ and ±0.2 psu, respectively. The passage of the eddies caused variations of both satellite-measured sea surface height anomaly (SSHA) and tide-gauge-measured sea level anomaly to change from about –20 to 30 cm, consistent with the D anomaly from the PIESs. Bottom pressure sensors measured no variation related to these eddy activities, which indicated that the two eddies were dominated by baro-clinicity. Time series of SSHA map confirmed that the two eddies, originating from the North Pacific Subtropical Countercurrent region near 20°―30°N and 150°―160°E, traveled about 3000 km for about 18 months with mean westward propagation speed of about 6 cm/s, before arriving at the region southeast of Okinawa Island.  相似文献   

不同交通干道周边景观格局的分析与比较—以厦门岛为例   总被引：1，自引：0，他引：1  

黄宁  吝涛  陈晓津 《云南地理环境研究》2009,21(5):42-46,51

以厦门岛主要交通干道厦禾路、嘉禾路和鹰厦铁路厦门段为研究对象,利用GoogleEarth软件上获得的厦门岛2006年卫星遥感图像,在ArcGIS9.0与Fragstats3.3软件支持下,通过计算斑块面积比例、平均斑块面积、Shannon多样性、景观优势度、景观破碎度等景观指数,分析与比较各条交通干道周边地区的景观格局特征,得出：厦禾路周边人工景观面积比例较高,景观较为单一,且破碎度高;嘉禾路周边人工景观面积比例比厦禾路低,景观较为多样化,破碎度相对较低;而鹰厦铁路厦门段相对于两条道路,其周边人工景观面积比例较小,景观更为多样化,破碎度相对更低,并指出,造成不同干道周边地区城市化景观格局差异的主要两方面原因是干道建设时间的不同与干道性质的不同。  相似文献   

抚远三角洲国际区域合作模式的构建     

赵玲  王荣成 《世界地理研究》2009,18(3):26-35

本文从抚远三角洲（大黑瞎子岛）的归属问题入手,剖析了抚远三角洲的区域特点与未来发展前景,对目前中俄两国的国际合作机制和国际区域合作的支撑条件进行梳理。在不破坏大黑瞎子岛生态环境原则的基础上,以岛为依托,构建了东北亚综合贸易体、打造东北亚自由贸易区、建立跨国城市联合体、建设抚远为哈巴罗夫斯克卫星城以及开发抚远三角洲为国际生态文化旅游特区五种国际合作模式。  相似文献