Influence of Certain Organic Substances on Growth and Colony Formation of Asterionella glacialis Castracane (Bacillariophyceae)     

Tzu-Chiu  Teng 《Marine Ecology》1984,5(4):317-327

Abstract. Organic substances are suspected to influence the unpredictable, episodic blooms which characterize the planktonic pennate diatom Asterionella glacialis in certain coastal waters. Experiments to test its general responsiveness to organic enrichments in terms of growth rate and colony formation were carried out. An axenic clone was grown at 10° C, 0.039 l min^-1,12:12 LD cycle in G uillard's f/2 medium enriched with eight different organic substances. Growth rates in organically-enriched media during exponential phase usually exceeded those in f/2 medium alone. Cell yields after 12 days in media enriched with glycyl-glycin and trypticase + yeast extract were significantly greater than in the other treatments. Longer chain lengths accompanied organic enrichment, notably with trypticase + yeast extract and 100ppm soil extract. These results suggest that Asterionella glacialis is positively responsive to elevated levels of certain organic substances. A potential effect of organic substance - trace metal - silica interactions on colony-size is suggested.  相似文献   

Wave Breaker Indices in Finite Water Depth   总被引：2，自引：0，他引：2  

Li Yucheng  Dong Guohai Teng Bin Professor  Civil Engineering Department  Dalian University of Technology  Dalian Ph. D. Student  Dalian University of Technology  Dalian Research Assistant  Doctor of Engineering  Dalian University of Technology  Dalian 《中国海洋工程》1991,(1)

Based on the analysis and comparison of wave breaker indices defined by geometric, kinetic as well as dynamic stabilities and verified by observation, the value a, which is equal to H / Lthkd by Miche's result and may be modified by Goda's results, is" suggested as the wave breaking criteria. The applicable values of a for pure waves or wave-current co-existing field are given in this paper. They are smaller than Miche's result (0.142), and they have been verified by model tests.  相似文献   

A new model (DRARCH) for assessing groundwater vulnerability to arsenic contamination at basin scale: a case study in Taiyuan basin,northern China   总被引：7，自引：0，他引：7  

Qinghai Guo  Yanxin Wang  Xubo Gao  Teng Ma 《Environmental Geology》2007,52(5):923-932

A modified DRASTIC model for groundwater vulnerability assessment (abbreviated as DRARCH model by combining the first letters of its six assessment indices) was proposed. It is essentially the specific application of DRASTIC model rather than a new model. Both natural hydrogeological conditions that prevent groundwater from contamination and important intrinsic hydrogeochemical properties of sediments in vadose zone that are related to the retardation of contaminants were considered as vulnerability indices. The DRARCH model consists of six indices: (1) Depth to the water table, (2) net Recharge, (3) Aquifer thickness, (4) Ratio of cumulative thickness of clay layers to total thickness of vadose zone, (5) Contaminant adsorption coefficient of sediment in vadose zone, and (6) Hydraulic conductivity of aquifer. The rating values and the weights of these vulnerability indices were obtained by contaminant transport simulation and factor analysis method respectively. Furthermore, the DRARCH model was applied to evaluate the groundwater vulnerability to arsenic contamination in Taiyuan basin, northern China, where groundwaters with high arsenic concentration occur in some localities. GIS-based mapping of groundwater vulnerability using this model indicates that the distribution of very high and high-vulnerability areas corresponds well to that of high-arsenic groundwaters. The DRARCH model is therefore reliable and useful for guiding groundwater environment management.  相似文献   

Common reflection surface stack using dip decomposition for rugged surface topography   总被引：1，自引：0，他引：1  

孙小东李振春  滕厚华 《应用地球物理》2007,4(1):45-50

We present an extension of the Common Reflection Surface （CRS） stack that provides support for an arbitrary top surface topography. CRS stacking can be applied to the original prestack data without the need for any elevation statics. The CRS-stacked zero- offset section can be corrected （redatumed） to a given planar level by kinematic wave field attributes. The seismic processing results indicate that the CRS stacked section for rugged surface topography is better than the conventional stacked section for S/N ratio and better continuity of reflection events. Considering the multiple paths of zero-offset rays, the method deals with reflection information coming from different dips and performs the stack using the method of dip decomposition, which improves the kinematic and dynamic character of CRS stacked sections.  相似文献   

浙江省降水云系红外云图特征及其与降水量的关系   总被引：2，自引：0，他引：2  

滕卫平  杜惠良胡波 俞善贤 《气象科技》2006,34(5):527-531

用2000~2003年GMS红外云图资料,统计分析了影响浙江省降水系统的红外云图特征及其与地面1 h降水量的关系。结果表明:降水云团的云顶亮温、1 h云顶亮温差、云顶亮温梯度和云团移动速度与地面降水强度的对应关系是非线性的,并且随季节的变化它们的关系又有明显变化;随着云顶亮温的降低,1 h降水量降水强度逐渐增大,出现强降水的机率也明显增多;浙江省内易出现2.0 mm/h(中雨)7、.0 mm/h(大雨)、15.0 mm/h(暴雨)强降水的云顶亮温指标分别为-30℃、-36℃、-41℃。  相似文献   

两类江淮大水的大气环流特征   总被引：5，自引：1，他引：5  

于淑秋  林学椿 《气象学报》2006,64(5):605-613

文中研究了江淮流域特大洪涝的环流特征。江淮流域洪涝年全国降水有两类分布型:即江淮流域大水年中国降水偏多型和江淮流域大水其南北降水偏少型。研究了这两类降水分布型的环流特征,结果指出:北半球500 hPa位势高度场有着显著的差异。东亚大西洋相关链的建立(南海高压、梅雨槽和鄂霍茨克海高压)是江淮流域多雨的重要条件,而欧洲阻塞高压的建立在全国降水分布型中起着重要的作用。进而研究了东亚大西洋相关链与北太平洋海温的关系。  相似文献   

中国气温的年代际振荡及其未来趋势   总被引：9，自引：13，他引：9       下载免费PDF全文

于淑秋林学椿  徐祥德 《气象科技》2003,31(3):136-139146

文章用1851～2000年中国年气温资料，讨论了它的变化及其未来趋势。指出：①我国气温有3次全国性的跃变，分别在1920、1955和1978年，每个阶段平均持续期为30年，这和北半球气温跃变点是基本一致的；②我国气温从1978年开始进入了一个稳定增温的气候阶段，直到目前全国年平均气温比上一气候阶段增加了0．3l℃，增暖地区主要在黄河以北的北方地区，冬季增暖比夏季明显，1998年是我国近百年来最暖的一年；③最近一次增温开始于1978年，至2000年持续了23年，估计这个增温阶段至少还能持续10年，但未来10年主要的增温地区有可能南移，长江流域将比现在暖，夏季气温37℃以上的日数要比现阶段增多。  相似文献   

浙江古田山自然保护区常绿阔叶林群落特征   总被引：1，自引：0，他引：1  

胡正华  于明坚  方腾  丁炳扬  钱海源 《南京气象学院学报》2003,26(1):63-69

在对古田山自然保护区森林植被广泛调查的基础上，详细分析了常绿阔叶林群落特征，从该区森林植被的外貌特征、群落结构和种类组成上看，均具有我国典型亚热带常绿阔叶林的基本性质。  相似文献   

Controls by saturation state on etch pit formation during calcite dissolution   总被引：1，自引：0，他引：1  

H.Henry Teng 《Geochimica et cosmochimica acta》2004,68(2):253-262

Dissolution experiments were conducted on {101?4} cleavage faces of calcite at various under-saturations to determine how the saturation state controls etch pit formation. Experimental observations were made by using in situ fluid cell Atomic Force Microscopy. Three dissolution modes were observed. When the saturation index Ω > 0.541, no etch pit formation was seen and dissolution primarily occurred at existing steps. When Ω decreased to Ω_c = 0.541-0.410, the first visible pits appeared and continuous reduction in saturation state slowly increased the pit density on terraces while dissolution simultaneously proceeded at step edges. Finally, when the saturation state fell below Ω_max = ∼0.007, a precipitous increase in pit density took place that sharply contrasted to the ordered fashion of pit formation observed at saturation conditions above this level. These observations are interpreted to be two-dimensional and unassisted pit formation at Ω < ∼0.007, defect- and step-assisted dissolution in between Ω = 0.541 and 0.007, and existing step-induced dissolution for Ω > 0.541.The values of Ω_c are in good agreement with the dislocation theory's predicted critical under-saturations for pit formation at line dislocations. The occurrence of Ω_max is not directly predicted but is a logical consequence of dissolution thermodynamics. These findings suggest that (1) dissolution near and far from equilibrium (i.e., Ω > Ω_c, Ω < Ω_max) is not controlled by dislocations, therefore (2) dislocation density should significantly impact dissolution rate only in the saturation range of Ω_max < Ω < Ω_c; (3) dissolution kinetics and chemical affinity of dissolution reactions should have a non-linear relationship: at sufficiently close to equilibrium, when dislocations cannot open up to form etch pits, the dissolution kinetics will be limited by the number of existing steps; at far from equilibrium, when pits are able to form in defect-free regions, the dissolution rate will be capped by the maximum number of achievable steps.These findings may provide explanations for several well-observed geochemical relationships, including the weak dependence of dissolution rate upon dislocation density in distilled water and the ‘plateau’ behavior of dissolution kinetics both near and far from equilibrium. The explosive occurrence of unassisted pit nucleation at Ω ∼ Ω_max is not predicted by the current dissolution rate equations. This suggests that an accurate ‘general’ rate law describing universal dissolution processes has yet to be developed.  相似文献   

Near real-time magnitude determination for large crustal earthquakes     

Yih-Min Wu  Ta-liang Teng   《Tectonophysics》2004,390(1-4):205-216

We introduce an empirical method of near real-time, near-field magnitude determination for large (M>6.5) crustal earthquakes. Time integration over the strong shaking duration on the absolute values of the acceleration records is carried out for nearby stations surrounding many large earthquake sources in Taiwan. The integrated quantity, here denoted as total effective shaking, is used in a regression process to derive an empirical relationship for a quick Mw determination useful for a reliable real-time operation in earthquake rapid reporting and earthquake early warning systems (EWSs).  相似文献