南沙珊湖礁生态系生物体中δ_(13C)的分布     

陈绍勇  周伟华  吴云华  林昭进 《海洋科学》2001,(6)

1999年4月对南沙群岛海域珊湖礁生态系进行调查,采集了永暑礁和渚碧礁生态系统中不同营养级的生物样品,测定了它们的稳定同位素 13C的丰度δ13C,结果表明,永暑礁中的δ13C 沿着食物链有明显的增加趋势,渚碧礁则不明显.渚碧礁生态系中δ13C 的平均值为 -17.7‰,明显高于永暑礁( -19.5‰),这主要与生物种群的差异,纬度变化及环境因子有关。底栖性鱼类比游泳性鱼类的δ13C 相对高。对于肉食性的珊瑚礁鱼类来说,小型鱼类肌肉中的丰度要高于中型和大型鱼类,这可能是由于代谢反应差异引起的。作为代谢的主要器官肝脏对13C有更高的富集度。温度、生物合成以及初级消费者的食物是以C3 还是C4 植物为主对生物体内的δ13C 起决定作用。  相似文献   

浅海桶形基础平台抗拔力与抗倾稳定分析     

薛万东 《黄渤海海洋》2001,19(3):87-92

平台在海上受风、浪、流、冰等水平载荷作用产生倾斜，而土壤粘接力、摩擦力和土抗力是平台的抗拔和抗倾力，桶基平台应满足抗拔、抗倾稳定的要求，以保证平台的整体稳定性。讨论了桶基平台受水平力作用时，桶形基础的破坏模式及其计算方法，阐述了抗倾稳定计算方法。  相似文献   

Seasonal and annual variations of marine sinking particulate flux during 1993~1996 in the central South China Sea   总被引：1，自引：0，他引：1  

CHEN Ronghu  WIESNER M G  ZHENG Yulong  CHENG Xinrong  JIN Haiyan  ZHAO Qingying  ZHENG Lianfu 《海洋学报(英文版)》2007,26(3):33-43

A total of 67 samples from the upper and lower sediment traps in the central South China Sea were analyzed, which were collected during 1993~1996. It is indicated that the distribution of stable isotope values, surface primary productivity, fluxes of total particulate matter, carbonate, biogenic opal, organic carbon, planktonic foraminiferal species and their total amount exhibit obviously seasonal and annual fluctuations. High values of the fluxes occurred in the prevailing periods of the northeastern and southwestern monsoons, and the low values occurred during the periods between the two monsoons. The fluxes of some planktonic foraminiferal species (Globigerinoides sacculifer, G. ruber, Globigerinita glutinata, Neogloboquadrina dutertrei) and their percentages also exhibit two prominent peaks during the prevailing periods of the northeastern and southwestern monsoons respectively, while those of Globigerina bulloides, Globorotalia menardii and Pulleniatina obliquiloculata only exhibit one peak in the prevailing periods of the northeastern monsoon. In addition, fluxes and percentages of Globigerinoides sacculifer and Globorotalia menardii as well as the fluxes of carbonate and total amount of planktonic foraminifera decrease gradually from 1993 to 1996, and those of Globigerina bulloides, Globigerinita glutinata and biogenic opal increase gradually from 1993 to 1996. The fluxes of carbonate and organic carbon in the upper trap are higher than those in the lower one. The study indicates that the seasonal and annual variations of the sediment fluxes and planktonic foraminiferal species are mainly controlled by the changes of surface primary productivity and hydrological conditions related to the East Asian monsoon. The lower carbonate and organic carbon fluxes in the lower trap are related to the dissolution.  相似文献   

Effects of tributyltin at environmental levels on monooxygenase system of digestive gland in hard clam Meretrix meretrix     

HUANG Zhouying  CHEN Yixin  WANG Chonggang  ZHAO Yang  ZUO Zhenghong 《海洋学报(英文版)》2007,26(2):144-149

The effects on ethoxyresorufin O-deethylase （EROD）, NADPH-cytochrome c reductase and NADH cytochrorne b5 reductase activities of digestive gland in Meretrix meretrix exposed to tributyltin （TBT） at environmental levels （0.1,1.0,10.0 ng/dm as stannum concentration）,in experimental condition, were evaluated. The EROD, NADH cytochrorne b5 reductase activities were significantly inhibited after exposure to 10.0 ng/dm^3 TBT for 8 and 20 d, the NADPH cytochrorne c reductase activities were significantly inhibited after exposure to 0.1,1.0 and 10.0 ng/dm TBT for 8 d and to 1.0 and 10.0 ng/dm for 20 d, as compared with the matched control, while NADH cytochrorne b5 reductases and NADPH cytochrome c reductase activities were induced after exposure to 10.0 ng/dm^3 TBT for 2 d. The EROD activity in the 10 ng/dm^3 group,and the NADH cytochrome b5 reductases activities in 1.0 and 10.0 ng/dm groups, were significantly induced when transferred to clean recovery tanks for 7 d. The three enzymic activities in the clams exposed to TBT were recovered to the level corresponding to that of the control group after transfer to clean recovery tanks for 20 d. NADPH cytochrome c reductase activity in Meretrix meretrix seems to be more sensitive to exposure of TBT than that of the EROD and NADH cytochrome b5 reductases. The results suggest that induction and inhibition by TBT to the monooxygenase system enzymic activity in Meretrix meretrix would simultaneously exist. The enzymic activities were inhibited by exposure for a long time. The results suggest that inhibition of the monooxygenase system should be an indication of the exposure to environmentally relevant concentrations of TBT for a long time.  相似文献   

九龙江河口区表层水铀同位素的粒级分布          下载免费PDF全文

吕娥  张磊  陈敏  邱雨生  邢娜  杨伟锋  李艳平  黄奕普 《海洋学报》2007,29(4):59-68

利用微滤和超滤技术研究了九龙江河口区表层水中铀及其同位素组成的粒级分布和地球化学行为.结果表明,溶解态(<0.4μm)中低分子量组分(<10 000 u)占主要份额,胶体态(10 000 u~0.4μm)238U所占比例不足1%,且随盐度的增加其所占份额逐渐降低.溶解态、低分子量组分和胶体态238U的比活度与盐度之间存在良好的线性正相关关系,证实它们在九龙江河口区呈现保守行为.在颗粒态(>0.4μm)中,各粒级组分238U所占份额主要受控于相应颗粒物的浓度,在盐度小于20的区域,各粒级颗粒组分238U占颗粒态的份额有如下变化次序:10~53μm>2~10μm>0.4~2μm>大于53μm,而在盐度大于30的近外海站位,该次序发生一些变化:0.4~2μm>10~53μm>2~10μm>大于53μm,最小粒级颗粒组分238U的贡献有所增加,反映了自生铀贡献的加强.九龙江河口区表层水中溶解态(包括低分子量组分和胶体态)的234U/238U)_A.R.均大于1,显示出234U过剩的特征,而各粒级颗粒组分中的234U/238U)_A.R.则接近于平衡值(1.0).这一现象与陆地岩石风化过程中水体对铀的淋滤释出量及234U的优先浸出有关.对232Th/238U质量比的研究显示,溶解态及其所包括的低分子量组分和胶体态的232Th/238U质量比均小于1,而颗粒态及其所包括的4个粒级组分中的232Th/238U质量比均大于1,反映了向外海输送过程中铀、钍地球化学行为的差异.  相似文献   

三角褐指藻体分泌物质对汞的络合作用     

吕小乔  孙秉一  史致丽 《中国海洋大学学报(自然科学版)》1990,(4)

本文测定了一次培养实验和连续培养实验中三角褐指藻胞外产物的变化及其与汞的络合性能。28天的培养过程中测得胞外产物与汞的络合容量C_L为2.6×10~(-5)mol/dm~3;表观稳定常数K′为6.1×10~(10)。该结果解释了细胞培养过程中胞外有机物的释放对汞的解毒机理及对介质中汞形态的转化。  相似文献   

晚侏罗世气体水合物中甲烷的释放证据     

周立君  张丽洁 《海洋地质前沿》2001,17(5):15-17

碳酸盐储层的界定性十分模糊,但它是引起气候变化的可能性因素,因而大陆边缘和永久冻土区存在着甲烷水合物这一现象唤起了人们极大的兴趣。CH4（(13C"-60‰）的大规模快速释放可用来解释古新世有孔虫、海洋块体碳酸盐、土壤碳酸盐和齿状磷灰石同位素记录下的(13C负位移、阿普第阶块体碳酸盐的(13C（(13Ccarb）位移以及托阿尔阶块体碳酸盐、海洋和陆源有机物中记录的同位素位移。所有这些同位素位移都伴随着大范围的气候变暖。甲烷释放产生的特殊的(13C特征使我们能够识别整个地质历史中其它的甲烷释放事件。我们在这里给出了晚侏罗世甲…  相似文献   

ODP806井位氧同位素变化记录中轨道倾斜度和轨道偏心度同时出现     

Mull.  RA 陈玲玲 《海洋地质译丛》1997,(2):72-76

  相似文献   

耗氧速率(OUR)测量方法的实验研究   总被引：4，自引：0，他引：4  

李冰  孙英兰  李玉瑛 《中国海洋大学学报(自然科学版)》2006,36(3):456-460

目前多采用分批实验法和呼吸测量仪测量耗氧速率,而耗氧速率的测量对于研究活性污泥数学模型中的动力学参数及废水特性鉴定具有重要意义。本文根据OUR测量方法的基本原理设计了1种简易的OUR测量装置,为检验测量装置的有效性,设计了相关实验进行验证。在内源呼吸实验中,测定了所用活性污泥的内源呼吸速率是5.1mgO2/L·h,污泥的衰减系数是0.0137h-1,比文献值略高。基质降解实验对人工配水(葡萄糖和淀粉)的耗氧速率进行了测定,实验结果显示有3个显著不同的耗氧速率,分别为35mg/L·h,13mg/L·h,6mg/L·h,它们各代表葡萄糖降解、淀粉降解和内源呼吸的速率。内源呼吸速率高于前1个实验是由于基质降解过程中污泥量增加所致。并计算出异养菌产率系数Kd为0.63mgVSS/mgCOD,Kd略低于文献值。实验结果证明,该装置能很好的实现测量目的。  相似文献   

银川盆地中更新世以来的孢粉记录及古气候研究   总被引：8，自引：1，他引：8  

杨振京  刘志明  张俊牌  童国榜  阳小兰 《海洋地质与第四纪地质》2001,21(3):43-49

银川盆地中更新世以来的孢粉记录及据此所重建的古气候参数，揭示了该区中更新世以来的古气候演变特征，其演变经过了温湿→凉湿→温和→冷湿→温干→凉较湿→冷湿→温干→凉润→温较干→温干的变化，并与新疆地区，黄土高原以及深海δ^18O曲线进行了对比，结果表明，各地的古环境变化大致同步，该区由于位置靠西，邻近沙漠，最近地质历史时期的区域性干旱特色明显。  相似文献