云龙天池湖泊水深与硅藻生物多样性的关系     

邹亚菲  严瑶  张佼杨  张利周  旺罗 《第四纪研究》2015,35(4)

以云龙天池湖泊为研究对象,通过分析不同深度表层硅藻样品的生物多样性以及100年来硅藻生物多样性的变化特征,探讨硅藻生物多样性与水深变化之间的关系.虽然硅藻组合随水深发生了明显的变化,浅水区底栖硅藻占优势,深水区浮游硅藻占优势,但是不同深度表层样品中硅藻的属种数(简单分异度)基本相同,硅藻种群的生物多样性也没有发生显著的趋势性变化.这主要是由于硅藻各属种在不同深度的权重互补,导致云龙天池硅藻的多样性在湖泊的不同深度变化不大.近百年来的湖泊沉积速率显示,自1960年前后,湖泊水位在波动中逐步升高,但是硅藻种群的生物多样性并没有发生相应的变化.以上研究结果说明,云龙天池硅藻种群的生物多样性,不管是在时间上,还是空间上,与水深变化均无明显相关性.  相似文献   

The use of multivariate statistics to resolve multiple contamination signals in the oxygen isotope analysis of biogenic silica          下载免费PDF全文

KATY E. WILSON  MELANIE J. LENG  ANSON W. MACKAY 《第四纪科学杂志》2014,29(7):641-649

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Study on correlativity among some seismological prediction indexes related to earthquake frequency or energy     

韩渭宾  易桂喜  辛华 《地震学报(英文版)》2001,14(6):620-625

Introduction Study of seismicity indexes and prediction methods is an important aspect of earthquake pre-diction research. In recent years, with more and more seismicity indexes being presented and de-veloped, a question is naturally put forward that which ones among so many seismicity indexes are dependent and which ones are independent when they are used to describe seismicity changes. The author studied the correlativities among several non-linear prediction indexes, such as capacity dimens…  相似文献   

黄土土性参数的统计分析   总被引：16，自引：2，他引：16  

倪万魁  韩启龙 《工程地质学报》2001,9(1):62-67

讨论了土性参数不确定性的主要来源, 并对黄土高原典型地段黄土土性参数进行了详细地统计分析, 结果表明黄土土性参数的均值、标准差和变异系数具有明显的区域性特点, 土性参数的统计必须针对具体的工程进行。黄土的物理力学指标的分布多服从正态分布, 在边坡可靠度计算中各指标均可用正态分布近似。  相似文献   

DIAGNOSTIC ANALYSIS ON THE DYNAMICS AND NUMERICAL SIMULATION OF CLEAR AIR TURBULENCE(CAT)     

Liu Jinliang  Li Jianzhong 《Acta Meteorologica Sinica》1996,10(3):331-345

Clear air turbulence(CAT),a meso-or microscale(subgrid scale)phenomenon occurring insynoptic scale flow field at high altitude,is very difficult to be observed by the conventional obser-vation network.Thus it is necessary to approach an index to predict CAT.But at first,the struc-ture characteristics of CAT should be preanalyzed.In this paper,based on the theoretical and diag-nostic analysis of a case,features for wind profile,energy budget and dynamic mechanism of thiscase were presented.Furthermore,an objective and quantitative index for CAT forecast was giv-en.The verification for its efficiency was done with both real-time observation data and productsfrom a numerical model.The results are very encouraging.  相似文献   

水资源评价指标体系研究   总被引：64，自引：4，他引：64       下载免费PDF全文

左东启  李鸿业 《水科学进展》1996,7(4):367-374

在近20年来不同流域和地区水资源评价工作的基础上,指出若干具有普遍意义、待研究改进的新问题,提出了包括自然、人文、经济、管理等方面的简要评价指标体系,应用两种计算方法,并选取国内7个县市为代表进行了试评价分析.  相似文献   

台湾海峡中北部至南麂列岛海域2005年冬季硅藻群落结构特征   总被引：1，自引：0，他引：1  

谢文玲  陈长平  高亚辉 《台湾海峡》2007,26(3):370-379

分析了2005年冬季台湾海峡中北部至南麂列岛海域浮游硅藻的种类组成、分布特点及与环境因子的关系.共鉴定硅藻58属159种(含变种和变型).调查期间正值冬季,种类组成以广温种(占49.69%)为主,其次是暖水种(占18.24%)和温带种(占14.47%).优势种有14种,占总种类数的7.53%.调查海域冬季硅藻群落分布的特点是:硅藻细胞密集区和高值区基本上集中在海峡中线断面上,底层硅藻丰度较表层高.硅藻丰度介于(0.216~7.544)×103个/dm3,总体上,硅藻丰度较低.应用多元逐步回归方法分析表明:影响调查区冬季硅藻平均细胞数量分布的主要因子是硅酸盐浓度.同时,硅藻平均丰度与水温的线性相关性分析表明,硅藻平均丰度的分布与温度呈显著的正相关关系.  相似文献   

南海晚第四纪的硅藻遗体及其地质意义Ⅶ.方格罗氏藻     

程兆第  刘师成等 《台湾海峡》1995,14(2):110-112

方格罗氏藻[Roperia tesselata(Roper)Grunow]的壳面外形和壳缘构造多样，笔者在南海晚第四纪的三个柱状样沉积物中都采到，统计1303个壳体。分析结果表明：在冰期的沉积物中，壳面呈圆形，壳缘平滑无齿状隆起线的壳体占绝对多数；在间冰期的沉积物中，壳面呈卵形，少数近圆形，壳缘具齿状隆起线的壳体明显增多。因此，该种壳面的两类不同形状和构造的数量差异，可应用于探讨南海晚第四纪古气侯旋回。  相似文献   

One Dimensional Ecosystem Model Simulation of the Effects of Vertical Dilution by the Winter Mixing on the Spring Diatom Bloom     

Naoki Yoshie  Yasuhiro Yamanaka  Michio J. Kishi  Hiroaki Saito 《Journal of Oceanography》2003,59(5):563-571

A one-dimensional ecosystem model has been used to investigate the processes relevant to the spring diatom bloom which play important roles in the biogeochemical cycle in the western subarctic Pacific. The model represents the plankton dynamics and the nutrient cycles in the spring diatom bloom; its results show the importance of dilution by deep mixing in winter. It is supposed that the vertically integrated biomass of phytoplankton decreases in the winter due to the decrease of photosynthesis, because the deep mixing transports phytoplankton to a layer with a low light level. However, the observed integrated diatom biomass increases as the mixed layer deepens. This is because the decrease of concentration due to dilution by mixing causes the diatom grazed pressure to be less significant than diatom photosynthesis. In other words, the effect of dilution on the grazed rate is more significant than the effect on the photosynthesis rate because the grazed rate depends on the concentrations of both diatom and grazer, whereas the photosynthesis rate depends only diatom concentration. The average specific diatom grazed rate, defined as grazed rate divided by diatom biomass, decreases by 35% associated with the deepening, while the average specific photosynthesis rate of diatom decreases by 11%. As a result, the average specific net diatom growth rate during the deep mixing is about 70% of its maximum during the spring diatom bloom. The deep mixing significantly affects the amplitude of the spring diatom bloom not only by the supply of nutrients but also by the dilution which drastically decreases the grazed pressure. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Diatom production in the marine environment: implications for larval fish growth and condition   总被引：5，自引：0，他引：5  

St. John  M. A.; Clemmesen  C.; Lund  T.; Koster  T. 《ICES Journal of Marine Science》2001,58(5):1106-1113

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