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1.
This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms.The authors’theoretical explanation and analysis by a mathematical-physical model prove that comparedto montmorillonite,kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity.This project’s studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system;whereas the effect of pH on the kaolin system is the same asthat on the montmonrillonite system.  相似文献   

2.
Study on the coagulation of four species of red tide organisms(Nitzschia pungens,Skeletonema costatum,Prorocentrum minimum and Noctiluca scintillans)with montmorillonite,and the effect ofmontmorillonite pretreatment on the coagulation shows that the capability for montmorillonite to coagu-late with them is in the order:N.pungens>S.costatum>P.minimum>N.scintillans.Thecoagulation is discussed from the aspects of the structure,shape,size,movement,habit,etc.of differ-ent species and the results are explained theoretically.The experimental results also indicate that the treat-ment of montmorillonite with acid can enhance its coagulating capability.This is due to the fact that Al(OH_2)_6~(+3),exchanged from the clay lattice by hydrogen ion H~+,forms hydroxy-aluminum polymers on thesurface of the montmorillonite.The hydroxy-aluminum polymers positively charge and increase the positivecharacteristic of the clay surface,and also serves as a bridge between adjacent surfaces of particles.Thesetwo functions enhance  相似文献   

3.
Various aspects of studies on internal tides are reviewed .Both beam-like structure and modal structure of internal tides may exist in the ocean . Bottom intensifications are caused by many factors .e.g. upstream blocking , which is the result of nonlinear interaction among waves . The energy may decay very fast so that internal tides are mostly locally generated .Internal tides may have considerable residual currents.In a 3-D frame, numerical study revealed that internal waves may interfere with each other to cause strong motions fer from the generation sources.The mechanism that determines how the lee waves break to form various nonlinear waves such as solitary waves, hydraulic jumps and internal surges or bores remains unclear. Analytic study is difficult , so numerical method may be effective . A radiation condition on the open boundary must be employed. A complete 3-D model may gain interesting result.Study on internal tides in China is limited to field observations and data analysis .  相似文献   

4.
A Vector-based Cellular Automata Model for Simulating Urban Land Use Change   总被引：2，自引：0，他引：2  
Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditional raster-based CA model. The cells of vector-based CA model are presented according to the shapes and attributes of geographic entities, and the transition rules of vector-based CA model are improved by taking spatial variables of the study area into consideration. The vector-based CA model is applied to simulate land use changes in downtown of Qidong City, Jiangsu Province, China and its validation is confirmed by the methods of visual assessment and spatial accuracy. The simulation result of vector-based CA model reveals that nearly 75% of newly increased urban cells are located in the northwest and southwest parts of the study area from 2002 to 2007, which is in consistent with real land use map. In addition, the simulation results of the vector-based and raster-based CA models are compared to real land use data and their spatial accuracies are found to be 84.0% and 81.9%, respectively. In conclusion, results from this study indicate that the vector-based CA model is a practical and applicable method for the simulation of urbanization processes.  相似文献   

5.
China is a country in the period of economy takeoff. We cannot use the common method to forecast its fu-ture economy level. This paper establishes an economic level forecast model of the countries whose economy is in the takeoff because of the stimulation of model country. The enlightenment of the model is from physics. If there are two sub-stances, A and B, and a medium between them, according to physics, when substance A is hotter than B, B‘ s tempera-ture will inevitably rise and close to that of A. Thus, this system tends to be a state of balance. Three factors affect heatconduction between substance A and B. They are the difference of temperature between two substances, the conductivityof medium and the characteristics of themselves. The model is testified through two examples. And then we forecast theeconomic development level of China in long term. This paper raises a model to solve the problem of research approaches.However, since there are some limitations on data source, problems will appear. For example, in certain years, our fore-cast results do not suit the real situation. But in the long term, the tendency is accurate. Then this model can be amendedin accordance with different situations.  相似文献   

6.
In the present paper a three-dimensional model has been used to calculate the vertical structure of the current generated by typhoon surge. The aim of this work is to obtain support for the depth-averaged model, which is based upon two basic assumptions. One of them is that the current has a negligible vertical structure and the other is that the velocity veering angle is small. Our results show that, in most of the real storm surge cases, these two assumptions are quite good approximations of the real situation, especially when water is shallow, and the locations are near the shore. These features are usually encountered in the real storm surges with which we are concerned. Therefore, we can expect that the two-dimensional depth-averaged model will give satisfactory results. The experiments carried out by using a straight coastline and uniform depth give vertical structures which are compatible with the conclusions previously reached by other authors.  相似文献   

7.
This article reports main results of investigations on red tide in western waters of Xiamen Bay from Jan. to Dec. 1987, and elaborates on the relationship between the change of phytoplanktonic number and main environmental factors there. The cause and the method for judging and monitoring of red tide are discussed.  相似文献   

8.
The present paper reports on comparative studies of R-phycoerythrin (R-PE) from 30 species of the red seaweeds in Bangiophyceae and in Florideophyceae from Qingdao. The measured absorption spectra show that R-PE from these red seaweeds have two spectral types, namely type I having two absorption peaks and type II having three absorption peaks. 9 specise of a lower red seaweed belonging to Bangiophyceae are all type I R-PE. 3 species of a higher red seaweed belonging to Florideophyceae are also type I R-PE. The remaining 18 species are all type II R-PE. According to the distribution of two types of R-PE in red algae, an evolutionary trend from type I R-PE to type II R-PE can be seen, but this evolutionary process is more complicated and without a definite line of demarcation between the two spectral types of R-PE. The occurrence of two types of R-PE in red algae is of taxonomic significance.  相似文献   

9.
Meeting the challenge of sustainable development requires substantial advances in understanding the interaction of natural and human systems. The dynamics of regional sustainable development could be addressed in the context of complex system thinking. Three features of complex systems are that they are uncertain, non-linear and self-organizing. Modeling regional development requires a consideration of these features. This paper discusses the feasibility of using the artificial neural networt(ANN) to establish an adjustment prediction model for the complex systems of sustainable development (CSSD). Shanghai Municipality was selected as the research area to set up the model, from which reliable prediction data were produced in order to help regional development planning. A new approach, which could help to manage regional sustainable development, is then explored.  相似文献   

10.
Landslide susceptibility mapping is the first step in regional hazard management as it helps to understand the spatial distribution of the probability of slope failure in an area.An attempt is made to map the landslide susceptibility in Tevankarai Ar subwatershed,Kodaikkanal,India using binary logistic regression analysis.Geographic Information System is used to prepare the database of the predictor variables and landslide inventory map,which is used to build the spatial model of landslide susceptibility.The model describes the relationship between the dependent variable(presence and absence of landslide) and the independent variables selected for study(predictor variables) by the best fitting function.A forward stepwise logistic regression model using maximum likelihood estimation is used in the regression analysis.An inventory of 84 landslides and cells within a buffer distance of 10m around the landslide is used as the dependent variable.Relief,slope,aspect,plan curvature,profile curvature,land use,soil,topographic wetness index,proximity to roads and proximity to lineaments are taken as independent variables.The constant and the coefficient of the predictor variable retained by the regression model are used to calculate the probability of slope failure and analyze the effect of each predictor variable on landslide occurrence in thestudy area.The model shows that the most significant parameter contributing to landslides is slope.The other significant parameters are profile curvature,soil,road,wetness index and relief.The predictive logistic regression model is validated using temporal validation data-set of known landslide locations and shows an accuracy of 85.29 %.  相似文献   

11.
Extracting the cell objects of red tide algae is the most important step in the construction of an automatic microscopic image recognition system for harmful algal blooms.This paper describes a set of composite methods for the automatic segmentation of cells of red tide algae from microscopic images.Depending on the existence of setae,we classify the common marine red tide algae into non-setae algae species and Chaetoceros,and design segmentation strategies for these two categories according to their morphological characteristics.In view of the varied forms and fuzzy edges of non-setae algae,we propose a new multi-scale detection algorithm for algal cell regions based on border-correlation,and further combine this with morphological operations and an improved GrabCut algorithm to segment single-cell and multicell objects.In this process,similarity detection is introduced to eliminate the pseudo cellular regions.For Chaetoceros,owing to the weak grayscale information of their setae and the low contrast between the setae and background,we propose a cell extraction method based on a gray surface orientation angle model.This method constructs a gray surface vector model,and executes the gray mapping of the orientation angles.The obtained gray values are then reconstructed and linearly stretched.Finally,appropriate morphological processing is conducted to preserve the orientation information and tiny features of the setae.Experimental results demonstrate that the proposed methods can effectively remove noise and accurately extract both categories of algae cell objects possessing a complete shape,regular contour,and clear edge.Compared with other advanced segmentation techniques,our methods are more robust when considering images with different appearances and achieve more satisfactory segmentation effects.  相似文献   

12.
Algal organic materials (AOMs) are one critical factor affecting the efficiency of modified clays used for the mitigation of harmful algal blooms (HABs). This study was conducted to develop a deeper understanding of the mechanisms and factors affecting the adsorption of AOMs onto modified clays. Sodium alginate (polysaccharide) and kaolinite modified with polyaluminium chloride (PACl) were used as AOMs and modified clay model substances, respectively, and the effects of modifier dosage, contact time, solution pH and ionic strength were investigated through batch adsorption experiments. Kinetics revealed that the alginate adsorption rate was described well by a pseudo-second order model. PACl effectively enhanced the adsorption capacity of kaolinite and increased the adsorption rate, and the optimum additive amount of PACl was 5%. The experimental data fitted both the Freundlich and Langmuir adsorption equations well. The adsorption thermodynamics for alginate onto modified clays suggests that alginate adsorption is a spontaneous process. The adsorption of alginate onto modified clays was highly dependent on pH, with a decrease in adsorption observed with increased pH to 9.48, but the opposite was true above pH 9.48. Finally, adsorption increased with increasing ionic strength.  相似文献   

13.
ＩＮＴＲＯＤＵＣＴＩＯＮＡｑｕｉｃｕｌｔｕｒｅａｒｅａｒｅｄｔｉｄｅｓｉｇｎａｌｓｏｃｅａｎｐｏｌｌｕｔｉｏｎａｎｄｄｉｓａｓｔｅｒ.Ａｌｔｈｏｕｇｈｅｎｖｉｒｏｎｍｅｎｔｓｃｉｅｎｔｉｓｔｓｈａｖｅｃｏｎｄｕｃｔｅｄｍａｎｙｉｎ ｄｅｐｔｈｒｅｓｅａｒｃｈｅｓｏｎｔｈｅｃａｕｓｅａｎｄｆｏｒｍａｔｉｏｎｍｅｃｈａｎｉｓｍｏｆｒｅｄｔｉｄｅ ,ｍａｎｙｏｆｉｔｓａｓｐｅｃｔｓａｒｅｓｔｉｌｌｕｎｋｎｏｗｎｂｅｃａｕｓｅｒｅｄｔｉｄｅｉｓａｃｏｍｐｌｅｘｐｈｅｎｏｍｅｎｏｎａｎｄｔｈｅｅｃｏｌｏｇｉｃ…  相似文献   

14.
A new technique is introduced in this paper regarding red tide recognition with remotely sensed hyper-spectral images based on empirical mode decomposition （EMD）, from an artificial red tide experiment in the East China Sea in 2002. A set of characteristic parameters that describe absorbing crest and reflecting crest of the red tide and its recognition methods are put forward based on general pictre data, with which the spectral information of certain non-dominant alga species of a red tide occurrence is analyzed for establishing the foundation to estimate the species. Comparative experiments have proved that the method is effective. Meanwhile, the transitional area between red-tide zone and non-red-tide zone can be detected with the information of thickness of algae influence, with which a red tide can be forecast.  相似文献   

15.
1 INTRODUCTION In recent decades, red tides that induced by in- creasing eutrophication occur frequently in coastal areas worldwide. This has caused serious problems in marine environment, aquaculture industries and human health (Qi et al., 1993; Horner e…  相似文献   

16.
Harmful algal blooms(HABs),caused by the overgrowth of certain phytoplankton species,have negative effects on marine environments and coastal fisheries.In addition to cell-counting methods using phytoplankton nets,a hydroacoustic technique based on acoustic backscattering has been proposed for the detection of phytoplankton blooms.However,little is known of the acoustic properties of HAB species.In this study,as essential data to support this technique,we measured the acoustic properties of two HAB species,Akashiwo sanguinea and Alexandrium affine,which occur in the South Sea off the coast of Korea.Due to the small size of the target,we used ultrasound for the measurements.Experiments were conducted under laboratory and field conditions.In the laboratory experiment,the acoustic signal received from each species was directly proportional to the cell abundance.We derived a relationship between the cell abundance and acoustic signal received for each species.The measured signals were compared to predictions of a fluid sphere scattering model.When A.sanguinea blooms appeared at an abundance greater than 3 500 cells/mL,the acoustic signals varied with cell abundance,showing a good correlation.These results confirm that acoustic measurements can be used to detect HAB species.  相似文献   

17.
Batch culture experiments were conducted with a red tide dinoflagellateScrippsiella trochoidea (Stein) Loeblch III collected from Jiaozhou Bay, Shangdong, China. Growth rates and oellular Chl—a were measured in media with iron and manganese ion concentrations controlled at different levels using EdTA-trace metal buffer systems. Cell density increased 3.2 times to 6.5 times over the range of lowest (0 mol/L) to highest (10−5 mol/L) iron and manganese ion concentrations. The range of cell density response was much lower than the range of total available iron and manganese, which was >100—fold that of Fe. This nonlinear relationship indicates that the cells adapt to make more efficient use of iron and manganese under limiting conditions. The cellular Chl—a content maximized after 3 days incubation and then decreased gradually under either iron or manganese limitation conditions. It indicated that the algae gained higher photosynthesis ability when transferred to a new environment. Growth responses to iron and manganese limitation can be both modeled according to the equation of Monod. The half—saturation constant for growth,k, is 4.6×10−8 mol/L for Fe and 5.1×10−8 mol/L for Mn. Our results showed that the iron availability in Jiaozhou Bay does not limit the growth ofS. trochoidea. Contribution No. 2831 from the Institute of Oceanology, Chinese Academy of Sciences. Project 9389008 supported by NSFC; Study supported by PDB6.  相似文献   

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