Type and evolution of landscapes of Nansha Islands

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Type and evolution of landscapes of Nansha Islands

Landscapes of the Nansha Islands may be divided into five types: tropical marine organism-breeding landscape of reef knoll like Zengmu Shoal, Wan’an Bank and so on; tropical marine organism-breeding landscape of atoll including all emerged reefs and most submerged reefs; tropical evergreen arbor-bush forest and phosphorous lime soil landscape of limesand Islets like Taiping Islet, Nanwei islet and so on; tropical shallow sea marine organism-breeding landscape of southern continental shelf; tropical oceanic and deep-sea marine organism landscape in middle and north parts of the Nansha Islands area. These five landscape types may be also summed up as two categories, one is tropical sea landscape including those in shallow and deep sea, the other is tropical coral reef landscape including those of reef knoll, atoll and limesand islet. This paper outlines the evolutional model of landscapes of the Nansha Islands. The distribution and evolution of landscape types are related with palaeogeography and modern environmental conditions. The former shallow sea of the Nansha islands was coastal zone in the Late Pleistocene epoch. Deep sea is evolved from shallow sea due to long and slow subsidence of crust. Modern coral reefs develop on old reef top of the Late pleistocene epoch or on baserock of continental shelf in the Holocene due to the rise of sea level in postglacial. Limesand islet is in the peak of developmental stage.     

中国南沙群岛的双壳纲贝类

报道了中国南沙群岛的双壳纲贝类141种,分隶于5亚纲8目36科77属.从种类的组成中,帘蛤科有18种,蚶科15种,扇贝科11种,鸟蛤科10种,锉蛤科8种,贻贝科、海菊蛤科和樱蛤科各7种,砗磲科6种,其他各科的种类均在5种以内.按种的性质而论,大多数属于和珊瑚礁有密切联系的热带种或亚热带种,区系性质为印度-西太平洋区的印尼-马来亚区.     

南沙北部灯光罩网与金枪鱼延绳钓联合探捕

2010年7月利用灯光罩网和延绳钓对南沙北部海域进行了初步的渔业资源调查,报道了该海域的鸢乌贼(Symplectoteuthis oualaniensis)和金枪鱼的渔获与分布状况。灯光罩网平均CPUE 63.90 kg/网,主要渔获物为鸢乌贼,占总产量的67.57%,平均胴长122 mm,质量89.6 g;延绳钓平均CPUE为18.19 kg/百钩,其中大目金枪鱼(Thunnus obesus)3.24 kg/百钩、短鳍斜齿鲨(Scoliodon Palasorrah)10.46 kg/百钩,渔获尾数较多的为帆蜥鱼(Alepisaurus ferox)和黑魟(Dasyatis atratus),分别占总数的39.13%和26.09%。提出南沙金枪鱼捕捞采用延绳钓与灯光罩网联合方式的建议。     

DIMETHYLSULFIDE IN THE SOUTH CHINA SEA

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THREE-DIMENSIONAL BAROCLINIC NUMERICAL SIMULATION OF THE SOUTH CHINA SEA CIRCULATION＇S SEASONAL CHARACTERISTICS II. MIDDLE AND DEEP CIRCULATION

A three-dimensional baroclinic shelf sea model‘ s numerical simulation of the South China Sea (SCS) middle and deep layer circulation structure showed that: 1. In the SCS middle and deep layer, a seulhward boundary current exists along the east shore of the Indo-China Peninsula all year long.A cyclonic eddy (gyre) is formed by the current in the above sea areas except in the middle layer in spring, when an anticyclonic eddy exists on the eastern side of the current. In the deep layer, a larges-cale anticyclonic eddy often exists in the sea areas between the Zhongsha Islands and west shore of southern Luzon Island. 2. In the middle layer in snmmer and autumn, and in the deep layer in autumn and winter, there is an anticyclonic eddy (gyre) in the northeastern SCS, while in the middle layer in winter and spring, and in the deep layer in spring and snmmer, there is a cyclonic one. 3. In the middle layer,there is a weak northeastward current in the Nansha Trough in spring and snmmer, while in autumn and winter it evolves inl~ an anticyclonic eddy ( gyre), which then spreads westward l~ the whole western Nansha Islands sea areas.     

A VERTICAL DISTRIBUTION MODEL OF NUTRIENTS AND DISSOLVED OXYGEN IN THE SOUTHERN TAIWAN STRAIT

Sinoe vertical transport of nutrients and dissolved oxygen are quite important in the water col-umn and have drawn serious attention these recent years, a one-dmension numerical model is tried to simulate the vertical distribution of nutrients and dissolved oxygen in June at two research sites in the southemTaiwan Strait. Physical transport parameters are calibrated by temperature simulation, and thenare used to simulate the profiles of NO_3, PO_4 and dissolved oxygen. The simulation was generally success-ful for both stations. The importance of various factors, such as upwelling tidal current andbiogeochemical activities, which influence the vertical distribution of nutrients and dissolved oxygen, is revealed by analysis of the modeling results. Some important rates, fluxes and ratios are also estimated anddiscussed on the basis of simulation.     

On a new species of Paragoneplax Castro (Crustacea: Decapoda: Goneplacidae), P. chenae sp. nov. from the South China Sea

A new species of goneplacid crab, Paragoneplax chenae, is described, based on collections from the Nansha Islands, South China Sea. P. chenae closely resembles its only congener P. serenei (Zarenkov, 1972) in general appearance. They are distinguishable from each other by the male abdominal and gonopodal characters.     

ANALYSIS AND DISTRIBUTION FEATURES OF BENZOTHIOPHENE IN SEDIMENTS OF NANSHA ISLANDS SEA AREA

unomicrroNTherearereportedstudisoninorganicsulfurcomPoundsinrnarinesedtritS(Song,l99(),Stefan,l994),butfeWonorganicsulfurcomPounds.Itwasshownthatthroughoilspthe,mnoffandatmosphdriproasses,manyanthropogedcorganicsulfurcomP0undsrnaybethenspotalintothemarineenvirorstWheretheycanbeeventuallydePositalalongwithnatamlorganicstilfUrcomPoundsinseddritSraateSetal.,l979).ResearchesonorganicstilfurcomPoundsinrnarinesedirnentSareofpotentialenvirornnentalchdricalshoilicanceforhaherunderstandingofthege…     

南沙群岛西南陆架区深水金线鱼的资源现状

根据 2003年南沙群岛西南陆架区春秋两次调查资料,分析南沙群岛西南陆架区深水金线鱼的资源现状。结果表明,深水金线鱼分布广泛,平均渔获率为 9. 9kg·h-1,渔获率有明显的季节变动,秋季高于春季,密集分布于 71~80m水深。其群体组成也有季节差异,春季的平均体长、平均体重大于秋季,优势体长组春季为 131 ~140mm,秋季为 121~130mm,渔获优势年龄组为Ⅰ ~Ⅱ龄鱼。目前其资源密度及资源量分别为 129. 41kg·km-2和9 .484 21t,资源量是原始资源量的 46%,该资源已明显衰退。同时文中还讨论了合理利用该资源的措施。     

Bathymetry and bottom albedo retrieval using Hyperion: a case study of Thitu Island and reef

The Spratly （Nansha） Islands in the South China Sea have considerable economic and important militarily strategic status. Ocean color remote sensing is an effective mean of surveying and research and especially it is useful for areas that are difficult to access, such as Thitu Island and its reef in the Spratly Islands. The Hyper-spectral Optimization Process Exemplar （HOPE） model, developed by Lee et al. （1999） is a rapid and robust bathymetry method that uses hyper-spectral remote sensing. In this study, using Hyperion hyper-spectral sensor data and HOPE, we derive bathymetry and bottom albedo measurements around Thitu Island and its reef. We compare the distribution of bottom depths from C-MAP with that derived from the Hyperion data. The retrieved bathymetry results correlate well with the distribution obtained from the bathymetry contour from 2.0 to 20 m. The average difference between Hyperion and C-MAP for two selected transects was 17.1% （n=59, R=0.848, RMSE=2.342） and 10.9% （n=59, R2=0.834, RMSE=0.463）. The retrieved bottom albedo is homogeneous in the lagoon and significantly non-homogeneous around the lagoon. These results indicate that HOPE could be very useful for bathymetry studies for the islands of the South China Sea.     

3-D BAROCLINIC NUMERICAL SIMULATION OF THE SOUTH CHINA SEA I. UPPER CIRCULATION

A three-dimensional baroclinic shelf sea model was employed to simulate the seasonal characteristics of the South China Sea (SCS) upper circulation. The results showed that: in summer, an anticyclonic eddy, after its formation between the Bashi Channel and Dongsha Islands in the northeastern SCS, moves southwestward until it disperses slowly. There exists a northward western boundary current along the east shore of the Indo-China Peninsula in the western SCS and an anticyclonic gyre in the southern SCS. But at the end of summer and beginning of autumn, a weak local cyclonic eddy forms in the Nansha Trough, then grows slowly and moves westward till it becomes a cyclonic gyre in the southern SCS in autumn. At the beginning of winter, there exists a cyclonic gyre in the northern and southern SCS, and there is a southward western boundary current along the east shore of the Indo-China Peninsula. But at the end of winter, an anticyclonic eddy grows and moves toward the western boundary after forming in the Nansha Trough. The eddy‘s movement induces a new opposite sign eddy on its eastern side, while the strength of the southward western boundary current gets weakened. This phenomenon continues till spring and causes eddies in the southern SCS.     

Diatom assemblages in surface sediments from the South China Sea as environmental indicators

We studied diatom distribution from 62 samples from the uppermost 1 cm of sediment in the South China Sea (SCS), using grabs or box corers in three cruises between 2001–2007. Fifty six genera, 256 species and their varieties were identified. Dominating species included Coscinodiscus africanus, Coscinodiscus nodulifer, Cyclotella stylorum, Hemidiscus cuneiformis, Melosira sulcata, Nitzschia marina, Roperia tesselata, Thalassionema nitzschioides, Thalassiosira excentrica, and Thalassiothrix longissima. Most surface sediments in the SCS were rich in diatoms, except for a few coarse samples. Average diatom abundance in the study area was 104 607 valve/g. In terms of the abundance, ecology, and spatial distribution, seven diatom zones (Zones 1–7) were recognized. Zone 1 (northern continental shelf) is affected by warm currents, SCS northern branch of the Kuroshio, and northern coastal currents; Zone 2 (northwestern continental shelf) is affected by intense coastal currents; Zone 3 (Xisha Islands sea area) is a bathyal environment with transitional water masses; Zone 4 (sea basin) is a bathyal-to-deep sea with stable and uniform central water masses in a semi-enclosed marginal sea; Zone 5 (Nansha Islands marine area) is a pelagic environment with relatively high surface temperature; Zone 6 (northern Sunda Shelf) is a tropical shelf environment; and Zone 7 (northern Kalimantan Island shelf area) is affected by warm waters from the Indian Ocean and coastal waters. The data indicate that these diatom zones are closely related to topography, hydrodynamics, temperature, nutrients and especially the salinity. Better understanding of the relationship between diatom distribution and the oceanographic factors would help in the reconstruction of the SCS in the past.     

The Distribution of Dissolved Aluminum in the Yellow and East China Seas

Water samples containing dissolved aluminum were collected from the Yellow and East China Seas in October-November 2000. The average concentrations of dissolved AI in the Yellow Sea （YS） and East China Sea （ECS） were 0.042 and 0.056 μ molL^-1, respectively. The concentration of dissolved aluminum decreased gradually across the continental shelf. The lower concentrations appeared in the YS cold water center and in the bottom layer at the shelf edge of the ECS, where they were 0.016 and 0.011 μmolL^-1, respectively. The distribution of dissolved Al was controlled by physical mixing processes rather than biological uptake processes. The impact of different water masses along the PN transect was calculated based on the mass balance model. The results show that the impact of the Changjiang River was mainly concentrated on the coastal area and the top thermocline water on the ECS shelf, where the impact percentage decreased from 12.6% to 1.1% in the surface water, while the contribution of the Kuroshio water was dominant on the ECS shelf in this survey, increasing from 77.6% to 97,8% along the PN transect from the Changjiang River Estuary to the Ryukyu Islands. It is concluded that aluminum can serve as a proper tracer for studying the impact of Changjiang terrestrial matter on the ECS shelf water.     

Analysis of the anomalous strength and location of the ITCZ affecting the formation of northern Pacific typhoons

Using the NCEP/NCAR reanalysis dataset from 1959-2004, the location and strength of the ITCZ (Inter-Tropical Con-vergence Zone), as well as their relations with typhoons in the northwestern Pacific were studied. It was found that the pentad loca-tion and strength of the ITCZ had close relations with the typhoon frequency. Higher latitude location or strengthened ITCZ were found to be favorable for the occurrence of typhoons over the Northwestern Pacific. An index was defined for ascertaining the loca-tion of the ITCZ. It was found that the index defined with the maximum value ofpentad and monthly meridional shear of zonal wind speed could better describe the location of ITCZ than another index defined with the maximum value of convergence. Correlation analysis between the index of ITCZ and the maximum cloud cover in the tropics showed that there were close relations between the ITCZ determined by the index and the maximum tropical cloud belt. The strength index of an ITCZ was defined as the zonal wind speed difference at latitudes south and north of the ITCZ. It was found that there are close relations between the ITCZ intensity and typhoon occurrence in the South China Sea [10°N-20°N, 100°E-120°E] and regions east of the Philippines and near the Mariana Islands [5°N-20°N, 127.5°E-150°E].     

南海历史地理争端空间分布与关联性研究

南海占我国海洋国土的2/3,不仅是中国国家安全的天然屏障和重要的出海口与战略通道,而且是我国未来重要的能源接续区与资源基地、地缘政治经济问题的多发区。对南海争端发展态势进行空间分布与关联性GIS分析,是重要的辅助决策支持。结果表明：（1）文献研究和网络爬虫等方法可以快速有效地获取南海争端历史地理数据,GIS技术能够对南海争端历史地理数据进行时空变化的深入分析;（2）就争端事件的时间分布而言,事件数量随时间推进呈现显著增长,个别发生重大南海争端事件的年份出现突增的现象;（3）就争端事件的空间分布而言,与越南及菲律宾相关的南海争端事件尤甚,其他周边国家则相对较少,这主要源于越菲两国的战略利益与南海所在区域交叠,使得越菲不断挑起事端;（4）越南、菲律宾与马来西亚等国的利益诉求区主要位于南沙群岛,各国诉求区分布明确,局部交错。网络GIS技术丰富了历史地理研究的途径,为其提供了新的思路和方法。     

Influence of dissolved oxygen on the protectiveness and morphological characteristics of calcareous deposits with galvanostatic polarization

The influence of dissolved oxygen on calcareous deposits formed under galvanostatic polarization mode was studied.When the dissolved oxygen concentration was less than 7 mg L~(-1),the cathodic protection potential showed a plateau at the initial polarization,and then quickly shifted negatively.While the dissolved oxygen was more than 9 mg L~(-1),the potential shifted negatively in a linear form.After 168 h of polarization,the final protection potential shifted negatively with the decreasing dissolved oxygen concentration.The deposition progress was monitored by electrochemical impedance spectroscopy,and only one single loop was found in Nyquist diagram,indicating deposits of ineffective protectiveness precipitation under the experimental conditions.The protection factor of deposits increased with the decreasing dissolved oxygen concentration which was detected by linear polarization resistance technique.The cathodic electrochemical reaction could change very shortly from oxygen reduction to hydrogen evolution after cathodic protection under very low dissolved oxygen concentration,such as 1 mg L~(-1),resulting in the hydrogen bubbling from the metallic surface and the decrease of deposits protection factor.Observation by scanning electron microscopy and X-ray diffraction analysis demonstrated that the deposits were mainly of calcite under the experimental conditions,and that dissolved oxygen had no effect on the crystalline types of calcium carbonate.     

南沙涉外渔业纠纷突发事件应急组织体系研究

在与外交部建立密切协调沟通机制、以我国外交部的政策方针为引导的基础上,遵循"以人为本、预防为主、综合效益、统一领导"的原则,可设立"南沙涉外渔业纠纷危机应对指挥部",下设"南沙涉外渔业纠纷危机应对事务委员办公室"和"南沙涉外渔业纠纷危机应对专家顾问团"两个职责分明的常规机构,以此构建南沙涉外渔业纠纷应急组织体系,预防并降低南沙海域内突发涉外渔业纠纷可能对南沙捕捞业造成的负面影响。     

南海地区岩石圈有效弹性厚度估计

分析了测高卫星同时应用于重力模型和地形模型时对计算南海地区岩石圈有效弹性厚度的影响,该影响可能会高估有效弹性厚度值。对比多项研究认为,南沙群岛地区岩石圈的有效弹性厚度约为9 km。通过对南海地区岩石圈的有效弹性厚度分布进行计算发现,南海海盆的有效弹性厚度最小约为4 km,南海周边的有效弹性厚度值较高,与海底岩石圈年龄的空间分布有较强的相关性,符合南海海盆扩张的历史。