北部湾表层黏土矿物分布特征及物源研究

利用X射线衍射(XRD)对北部湾表层沉积物中黏土矿物组成和结晶学特征进行了详细研究,揭示了源区和洋流对该区沉积物搬运和分布的控制机制。结果表明,北部湾表层沉积物中黏土矿物组成以伊利石、蒙脱石和高岭石为主,含有少量的绿泥石。在空间分布上,蒙脱石含量表现为中部高近岸低;伊利石含量表现为西南高东北低,绿泥石组分含量与之类似;高岭石含量表现为东北高,西南低。伊利石结晶度指数和化学指数平均分别为0.25°(Δ2θ)和0.5,表明伊利石结晶程度极好,为富Al伊利石,来源于化学风化作用占主导的源区。黏土矿物物源分析表明,红河是北部湾伊利石、绿泥石和蒙脱石的主要物源,其中蒙脱石因受沉积分异作用影响而在研究区中部富集;高岭石受到了红河、珠江以及广西和海南岛沿岸河流物质输入的共同影响。本研究结果对理解北部湾沉积物"源-汇"过程和古环境有重要参考意义。     

Distribution of meiofaunal abundance in relation to environmental factors in Beibu Gulf, South China Sea

This study aims to explore the distribution of meiofaunal abundance in relation to environmental factors in the Beibu Gulf,a natural semi-enclosed part of the South China Sea,surrounded by China and Vietnam.Meiofauna and ten benthic environmental factors were determined at 27 sampling stations in the Beibu Gulf in four surveys during 2006-2007.The results show a clear geographical trend in meiofaunal abundance,water depth,salinity and clay content.The meiofaunal abundance and the clay content decreased,whereas the water depth and the salinity increased from the north to the south of the Gulf.The percentage of meiofaunal abundance in the 0-2 cm layer increased,whereas in the 2-5 cm and 5-10 cm layers it decreased from the north to the south of the Gulf.Correlation analysis show significant negative correlations between meiofaunal abundance and water depth,benthic temperature,salinity and pH,but significant positive correlations between meiofaunal abundance and dissolved oxygen,chlorophyll a and clay content.     

南海北部湾东部海域表层沉积物地球化学特征

通过对南海北部湾东部海域61 个站位表层沉积物粒度和地球化学组成的相关分析和因子分析,探讨了其空间分布特征、元素相关性以及元素组合特征, 揭示了元素在区域上的分布规律和主控因素。结果表明: 绝大多数常微量元素具有相似的平面分布特征, 而MnO、Zr、CaO 和Sr 空间变异系数较大,在部分区域出现了异常高值, 表明其沉积环境受到正常陆源沉积以外其他因素的影响。元素和Al₂O₃的比值分布特征表明, 广西和海南岛近岸沉积物主要由陆源碎屑沉积组成, 在潮汐和近岸径流作用下,由近岸向远海输送; 而研究区西部海域沉积物主要为来自红河的物质。元素相关分析和因子分析结果表明, 研究区表层沉积物中绝大多数常微量元素主要受沉积物粒度的控制; CaO 和Sr 含量主要受生物活动活跃程度控制; Zr 含量分布主要受控于源区母岩矿物组成以及自源区的搬运距离; 而MnO 含量则受陆源、海底热液以及自生作用等多种来源共同影响。     

南海北部三种金线鱼属鱼类BHC,DDT残留研究

为探讨六六六(BHC)、滴滴涕(DDT)对远岸海域渔业资源和水产品质量的影响,用气相色谱法测定了南海北部陆架海域3种金线鱼属(Nemipterus)鱼类肌肉内和其中深水金线鱼(N.bathybius)5种组织内的BHC、DDT含量.结果显示,研究海域鱼肉中BHC和DDT含量分别为0.04~0.89(平均0.26)μg/kg(湿重)、0.71~8.0(平均3.1)μg/kg(湿重),均低于亚太地区部分近岸海洋鱼类的残留水平,并低于国内外水产品安全限量,呈广东海域高于台湾浅滩的区域分布,但在不同鱼种之间、离岸远近的鱼类之间BHC、DDT含量差异不明显(p>0.10).深水金线鱼体内农药含量在肝组织中较高,在肌肉内居中,在鳃丝中较低,BHC含量由高到底的顺序为:肝脏、腹肌、背肌、肠、皮、鳃丝,DDT含量由高到底的顺序为:肝脏、腹肌、背肌、皮≈肠、鳃丝,不同组织中pp-DDT,op-DDT含量与脂肪含量较显著地正相关(p<0.05).     

南海北部陆坡峡谷区海底沉积物工程地质特征及区域稳定性评价

The upper part of the continental slope in the northern South China Sea is prone to submarine landslide disasters,especially in submarine canyons. This work studies borehole sediments, discusses geotechnical properties of sediments, and evaluates sediment stability in the study area. The results show that sediment shear strength increases with increasing depth, with good linear correlation. Variations in shear strength of sediments with burial depth have a significantly greater rate of change in the canyon head and middle part than those in the canyon bottom. For sediments at the same burial depth, shear strength gradually increased and then decreased from the head to the bottom of the canyon, and has no obvious correlation with the slope angle of the sampling site. Under static conditions, the critical equilibrium slope angle of the sediments in the middle part of the canyon is 10° to 12°, and the critical slope angle in the head and the bottom of the canyon is 7°. The results indicate that potential landslide hazard areas are mainly distributed in distinct spots or narrow strips on the canyon walls where there are high slope angles.     

南海中西部渔场上升流时空变化特征分析

南海中西部海域是我国外海渔业开发的潜在渔场之一,摸清该海域的物理环境特征可为我国开发中西部渔场提供参考。本文以遥感风场和海温数据为基础,分析了2003~2012年西南季风期起止时间的年变化、上升流中心位置时空变动以及风场对上升流中心位置变动的影响。结果表明:在南海中西部海域,西南季风期通常从5月份开始,到9月份结束,西南季风持续天数平均值为129.4 d,其中,风向角呈51°~60°的天数最多,占总季风天数的21.98%,西南季风期持续时间有增加的现象。上升流中心位置变动范围为11°~15°N,109°~112°E。西南季风期平均风速减小时,年平均上升流中心在经向上向近岸移动,在纬向上向高纬度移动;平均风速增加时,年平均上升流中心在经向上向离岸方向移动,在纬向上向低纬度移动;当西南季风期平均风向角减小时,年平均上升流中心向低纬度移动,平均风向角增大时,年平均上升流中心向高纬度移动。此外,发现厄尔尼诺年此上升流面积显著大于非厄尔尼诺年,而最低温度比2003~2012年平均最低温度低1.3℃。     

南海北部深海小型底栖动物丰度和生物量

2010年9月在南海北部5个深海站位和1个浅海站位进行了小型底栖动物和环境因子采样,对小型底栖动物的丰度和生物量进行了定量研究。本次调查中,共鉴定出10个小型底栖动物类群,分别是线虫、桡足类、多毛类、介形类、甲壳类幼体、异足类、寡毛类、涡虫、无板类和等足类。从丰度来看,线虫是绝对的优势类群,占总丰度百分比为94.72%;桡足类次之,占2.70%;多毛类再次,占1.62%;其他类群之和仅占0.96%。从生物量来看,线虫的生物量最大,占总生物量的53.83%;其次是多毛类,占32.17%;居生物量第三位的是桡足类,占7.14%;其他类群之和占6.85%。小型底栖动物的丰度和干重生物量分别为566.12±635.61个·(10cm2)-1和398.43±431.98μg·(10cm 2)-1,线虫的丰度和干重生物量分别为536.21±593.48个·(10cm 2)-1和214.48±237.39μg·(10cm 2)-1。研究站位线虫、桡足类、多毛类和小型底栖动物丰度,小型底栖动物生物量与环境因子的相关分析表明,影响线虫丰度、小型底栖动物丰度、小型底栖生物生物量的主要环境因子包括底层水pH值、沉积物粉砂黏土含量和有机质含量。单因素方差分析(One-way ANVOA)结果表明,线虫丰度、桡足类丰度、小型底栖动物丰度和生物量在不同站位均有显著差异。与渤海、北黄海、南黄海、长江口、芽庄湾(越南)、大亚湾、北部湾、南海近海等海域相比,本研究海域的小型底栖动物丰度和生物量偏低。     

Distribution and dispersal pattern of clay minerals in surface sediments, eastern Beibu Gulf, South China Sea

Clay minerology of sediments are useful in determining distribution,sources and dispersal routes of fine-grained sediments.In the present paper,clay minerals of surface sediments throughout the eastern part of Beibu Gulf has been investigated to reveal sources and transport of detrital finegrained sediments.Four distinct clay mineral suites were observed from cluster analysis of clay mineral compositions of the samples.From the distribution pattern of clay minerals,we conclude that kaolinte in the eastern gulf is mainly derived from South China Landmass;Smectite could not be transported mainly by surface current from north-western Hainan Island,and maybe minor portion of it from Red River;Illite is mainly transported by the currents from South China Sea.Chlorite has two sources,namely South China Sea and South China Landmass.The Zhujiang River derived sediments could not be one of the sources for the clay mineral here,because of very different composition and ratios.The distribution pattern of clay minerals in the eastern Beibu Gulf is mainly controlled by fine-grained sediment source and local currents.The Silt/Clay,Smectite/Kaolinte,and Smetite/(Chlorite+Illite) ratios could be used as indicators of fine-grained sediment dispersal in the gulf.     

南海北部浮游植物生物量的研究特点及影响因素

介绍了浮游植物生物量变化的研究方法。综述了南海北部浮游植物生物量在营养盐、光照、季风等理化因子影响下出现的变化特点。该海域生态环境复杂,由富营养的珠江口、沿岸带、北部湾和广阔的陆架及贫营养的开阔海区等不同生态区组成,因此浮游植物群落和生物量有其自身复杂的空间和时间变化特点。     

南海北部深水区表层沉积物工程性质的统计特征分析

针对从中国南海北部海域某深水区采集的表层沉积物柱状样,进行了沉积物微观结构的扫描电镜测试、矿物成分的X射线衍射试验以及物理和力学性质的统计学分析。结果表明,该深水区海底表层沉积物通常为有机质软黏土,具有高含水率、低密度、高孔隙比、高液限、高可塑性、低强度等典型特征。统计分析和假设检验表明,沉积物的物理和力学指标均呈现变异性,且后者普遍高于前者。相对密度、含水率、液塑限和塑性指数服从正态分布;容重、碳酸盐含量、不排水抗剪强度、灵敏度接近假设检验结果,近似服从正态分布。研究结果可为深水海底工程结构设计的海床土性参数取值提供参考。