EFFECTS OF Fe AND Mn ON THE GROWTH OF A RED TIDE DINOFLAGELLATE SCRIPPSIELLA TROCHOIDEA (STEIN) LOEBLCH Ⅲ     

秦晓明  邹景忠  钱培元 《中国海洋湖沼学报》1997,(2)

ImODUcnONThemacronutrientShitrogen,phosphorus,andsiliconhaveoftenboconsidedtodritthegroWthrateofmarinephytoplankton.RamtstudAsreveatalthattraeernetalAncronutrientSmaybeofsignilicanceintheerelogyofphytoplankton(RueterandUnsworth,l99l,Brandetal.,1983,HatheonandMore,l986).IronisacomPonentofmanyalgaeproteinsparticularlytwortantforbiosynthesisofchiorophyllandeleCtrntIansportrmCtionsofrespthetionandphotosynthesis,andisCrUdalfornitrogenmetaboljsmdriusehemeandiron-stilfUrcomPoundsarethecofact…  相似文献   

木星“大红斑”的旋转浅水实验模拟研究   总被引：1，自引：0，他引：1  

王振坡  王丽艳  刘书声 《天文学报》2001,42(4):397-407

在具有自由表面的旋转轨物面浅水实验系统上进行了可重复的系列模拟实验，在旋转随动坐标系中拍摄的照片和功率谱分析表明，确有大尺度持续存在的涡旋、漂移与演化产生，在一定条件下，呈现出一个自持的、长寿命的、沿与整体旋转方向相反方向漂移的反气旋孤立波涡旋（Rossby孤立波涡旋），这就是木星“大红斑”的实验室模型，实验结果证实，流体动力学不稳定主要来自于剪切和Coriolis力效应，由于远离平衡态的耗散系统的自组织，涌现出大尺度长寿命相干涡旋结构，受多次实验的启发，从流体动力学基本方程出发，在一定的实验条件下提出一个半经验模型，近似求出了Rossby孤立波涡旋解。  相似文献   

The interactions of humic compounds with electrolytes and three clay minerals under simulated estuarine conditions     

M.R. Preston  J.P. Riley 《Estuarine, Coastal and Shelf Science》1982,14(5):567-576

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Distribution of the toxic dinoflagellate Gonyaulax tamarensis in the Southern New England Region     

D.M. Anderson  D.M. Kulis  J.A. Orphanos  A.R. Ceurvels 《Estuarine, Coastal and Shelf Science》1982,14(4):447-458

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Modelling of earth and water pressure development during diaphragm wall construction in soft clay     

R. Schfer  Th. Triantafyllidis 《国际地质力学数值与分析法杂志》2004,28(13):1305-1326

The influence of a diaphragm wall construction on the stress field in a soft clayey soil is investigated by the use of a three‐dimensional FE‐model of seven adjacent wall panels. The installation procedure comprises the excavation and the subsequent pouring of each panel taking into account the increasing stiffness of the placed fresh concrete. The soft clay deposit is described by a visco‐hypoplastic constitutive model considering the rheological properties and the small‐strain stiffness of the soil. The construction process considerably affects the effective earth and pore water pressures adjacent to the wall. Due to concreting, a high excess pore water pressure arises, which dissipates during the following construction steps. The earth pressure finally shows an oscillating, distinct three‐dimensional distribution along the retaining wall which depends on the installation sequence of the panels and the difference between the fresh concrete pressure and the total horizontal earth pressure at rest. In comparison to FE‐calculations adopting the earth pressure at rest as initial condition, greater wall deflections and surface ground settlements during the subsequent pit excavation can be expected, as the average stress level especially in the upper half of the wall is increased by the construction procedure of the retaining structure. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Development of hyperplasticity models for soil mechanics     

S. Likitlersuang  G. T. Houlsby 《国际地质力学数值与分析法杂志》2006,30(3):229-254

Hyperplasticity theory was developed by Collins and Houlsby (Proc. Roy. Soc. Lon. A 1997; 453 :1975–2001) and Houlsby and Puzrin (Int. J. Plasticity 2000; 16 (9):1017–1047). Further research has extended the method to continuous hyperplasticity, in which smooth transitions between elastic and plastic behaviour can be modelled. This paper illustrates a development of a new constitutive model for soils using hyperplasticity theory. The research begins with a simple one‐dimensional elasticity model. This is extended in stages to an elasto‐plastic model with a continuous internal function. The research aims to develop a soil model, which addresses some of the shortcomings of the modified cam‐clay model, specifically the fact that it cannot model small strain stiffness, or the effects of immediate stress history. All expressions used are consistent with critical state soil mechanics terminology. Finally, a numerical implementation of the model using a rate‐dependent algorithm is described. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

黄河沉积物中稀土元素(REE)组成的粒度效应^*     

戴慧敏  鲍庆中  杨作升  王水利  宫传东  张泉  孙中任 《第四纪研究》2007,27(5):718-723

依据Stokes颗粒沉降原理将黄河利津水文站和汊河清八站的表层沉积物分别提取为<2μm,2~4μm,4~8μm,8~16μm,16~32μm和32~63μm的6个粒级,采用ICP-MS法对各个粒级沉积物的15个稀土元素进行测试。结果表明:黄河沉积物两个样品REE含量随粒度增大的变化趋势有细微差别,但总体随粒度大小呈"高—低—高"的不对称马鞍型分布,其中最高REE含量和最低REE含量分别位于<4μm的粘土粒级和4~16μm细粉砂粒级中; 各粒级沉积物经北美页岩标准化后,REE的配分模式一致,呈平缓的右倾型,相对富集轻稀土,明显的Eu正异常和Ce负异常。对各个粒级样品进行X射线衍射分析及体视镜下观测,石英含量随粒级增大而增加, 长石在8~16μm中含量最高,在16~32μm中,碳酸岩含量最高,随着粒级增大,重矿物含量逐渐增加,黄河沉积物REE随粒度的变化特征与粘土矿物对其吸附及流域碎屑沉积物不同粒级的矿物成分密切相关。  相似文献   

Characteristics of runoff and sediment yield for two typical erodible soils in southern China     

《国际泥沙研究》2022,37(5):653-661

Granite red soil (GRS) and Quaternary red clay (QRC) are two typical erodible soils in the red-soil region of southern China. Analytical and comparative studies of the characteristics of runoff and sediment yield for the two soils at various slopes are currently needed. The purpose of the current study was to clarify the characteristics of runoff and sediment yield for GRS and QRC at different slopes and to establish models for estimating sediment yield for the two soils. Forty-eight runoff microplots with four slopes (5°, 15°, 25°, and 35°) and two soils (GRS and QRC) were established and exposed to natural rainfall. Runoff and sediment yield were measured 10 times during the study period. Runoff and sediment yield for the two soils under the various slopes had similar temporal variations, and both increased with prior cumulative erosive rainfall. Runoff for GRS and QRC was moderately temporally variable, with coefficients of variation (CVs) from 46.2% to 60.6%, and sediment yield for QRC was strongly temporally variable, with CVs from 114.8% to 145.8%. Sediment yield for GRS increased with slope, but sediment yield for QRC first increased and then decreased, with a calculated inflection point of 18°, but runoff for both soils decreased with slope. The CVs of both runoff and sediment yield with slope for the two soils ranged from 3.6% to 88.0%, lower than the temporal variabilities, indicating that rainfall may have a larger impact than slope on runoff and sediment yield for QRC and GRS. Under the various slopes, runoff and sediment yield for both soils increased with rainfall and sediment yield increased with runoff, but the proportions of effective rainfall and runoff differed. Pedotransfer-function models based on rainfall, runoff, and slope accurately estimated sediment yield for the two soils, with the model fit coefficient of determination (R²) > 0.81 and the R² for verification >0.79. These results improve the understanding of the laws governing erosion for different soil types in the red-soil region of southern China and are important for managing the erosion of collapsing gullies and sloping farmland in the region.  相似文献   

Pore Characteristics and Factors Controlling Lacustrine Shales from the Upper Cretaceous Qingshankou Formation of the Songliao Basin,Northeast China: A Study Combining SEM,Low-temperature Gas Adsorption and MICP Experiments     

HAN Hui  DAI Jie  GUO Chen  ZHONG Ningning  PANG Peng  DING Zhengang  CHEN Jianping  HUANG Zhenkai  GAO Yuan  LUO Jinyu  LI Qirui  ZHANG Zhaokun 《《地质学报》英文版》2021,95(2):585-601

To investigate pore characteristics and the factors controlling lacustrine shales,geochemical,mineralogical and petrophysical experiments were performed on 23 shale samples from the Qingshankou Formation of the Songliao Basin,China.A comparison of mercury injection capillary pressure (MICP) and low-temperature N2 adsorption pore-size distribution showed that MICP has a higher pore-size distribution (PSD) line in its overlapping pore diameter range,which may be elevated by the higher pressure of MICP.Therefore,in the overlapping range,low-temperature N2 adsorption data were preferred in pore characterization.Negative correlations were observed between pore volumes and TOC content,indicating organic matter pores are not well-developed in the studied samples.This may be related to their low grade of maturity and type I kerogens.There existed negative relationships between pore volumes and S1,which illustrated that liquid hydrocarbons occupied some pore space.Micropore volume had a better correlation with S1 than mesopore and macropore volumes,which suggests that liquid hydrocarbons preferentially occur in micropores.No obvious relationships between pore volumes and quartz or feldspar were observed,while pore volumes increased with the increasing clay mineral content.These relationships indicate that intraparticle pores in clay minerals represent the principal pore type.  相似文献   

黏性土弱透水层压实作用:原理、技术及其水文地质意义     

刘妍君  马腾  杜尧  刘锐 《地学前缘》2021,28(5):59-67

弱透水层与含水层相互作用是国际水文地质学界关注的热点问题,特别是黏性土弱透水层与孔隙含水层的相互作用。近年来,在自然沉积、过量开采地下水、现代化农业机械与建筑业重型机械应用等自然与人为活动影响下,黏土弱透水层会发生有效应力增加、孔隙结构变形和孔隙度减少、渗透性降低、溶解氧和贮水能力减少以及侧向和垂向排水等的压实作用,导致地下水污染、地面沉降等环境问题的发生。本文重点介绍了黏性土弱透水层压实作用的原理,分析了地下水系统中4种不同状态下沉积物压实与孔隙流体压力的关系,基于压实物理模拟和数值模拟两个方面对压实作用的研究方法与技术进行了系统总结,随后探讨了压实作用下黏性土弱透水层对地下水水量与水质的影响,并对此研究的发展趋势及其在地球科学、环境科学等研究领域的潜在应用提出了展望。  相似文献