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1.
Dynamic response analysis of a floating mooring system   总被引：1，自引：0，他引：1  
An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For this new system, most of collision energy is absorbed through the displacement of floating platforms. In order to illustrate the validity of the system, a series of model tests were conducted at a scale of 1:40. The coupled motion characteristics of the floating mooring platforms were discussed under regular and irregular waves, and the influences of wave direction and other characteristics on dynamic response of the system were analyzed. The results show that the mooring system is safest at 0° of wave incident angle, whereas the most dangerous mooring state occurs at 90° of wave incident angle. Motion responses increase with the increase of wave height, but are not linearly related to changes in wave height.  相似文献   

2.
The cytotoxicity of abamectin to the Gill Cell Line of Flounder (FG cell line) was examined in this study. It was found that the exposure of FG cells to abamectin caused the decreases of both cell growth rate and antioxidant enzyme activities,and the increase of intracellular O2- content. It was proposed that the reduction of antioxidant enzyme activities in FG cells caused the accu- mulation of O2- content in FG cells, leading to the change of cell morphology and even the death of cells. The results showed that FG cell line is suitable for the evaluation of the acute toxicity of abamectin.  相似文献   

3.
Coccolithophorid is unicellular marine microalgae with a global distribution in temperate and sub-temperate oceanic regions and has the ability to produce ‘the coccoliths'. It is considered to be the second most productive calcifying organism on earth and becoming an important factor in the global carbonate cycle. Emiliania huxleyi is one of the only two bloom-forming coccolithophores and becomes a species crucial to the study of global biogeochemical cycles and climate modeling. Coccolithoviruse is a recently discovered group of viruses infecting the marine coccolithophorid E. huxleyi. They are a major cause of coccolithophore bloom termination, and DMSP concentration is increasing in the process of viral lysis. Phylogenetic evidences support that some genes are functional both in E. huxleyi and its virus(Eh V). Horizontal gene transfer(HGT) of multiple functionally coupled enzymes occurs in E. huxleyi and its DNA virus Eh V has been confirmed, which contributes to the diversification and adaptation of plankton in the oceans and also critically regulates virus-host infection by allowing viruses to control host metabolic pathways for their replication. Therefore, it is of particular interest to understand this host-virus interaction. On this issue, we have made a minireview of coccolithoviruses focusing on the basic characteristics, phylogenesis, horizontal gene transfer and the interaction between the host and its viruses, as well as its important role in global biogeochemical cycling.  相似文献   

4.
The aim of the present study was to investigate the long-term effects of 17β-estradiol(E2) exposure on gonadal development in the tiger puffer( Takifugu rubripe s), which has a genetic sex determination system of male homogametic XY-XX. Tiger puffer larvae were exposed to 1, 10 and 100 μg/L E2 from 15 to 100 days post-hatch(dph) and then maintained in clean seawater until 400 dph. Changes in sex ratio, gonadal structure and gonadosomatic index(GSI) were monitored at 100, 160, 270 and 400 dph. Sex-associated single nucleotide polymorphism(SNP) markers were used to analyze the genetic sex of samples, except those at 100 dph. Exposure had a positive effect on the conversion of genetically male gonads into phenotypically female gonads at 100 dph. However, gonads from 60% of genetic XY males in the 1-μg/L E2 group and 100% in the 10-μg/L E2 group developed intersexual gonads at 160 dph; gonads of all genetic XY males in the two treatment groups reverted to testis by 270 dph. While 38%, 57% and 44% of gonads of XY fish in the 100-μg/L E2 group reverted to intersexual gonads at 160, 270 and 400 dph, respectively, none reverted to testis after E2 treatment. In addition, E2 exposure inhibited gonadal growth of both genetic sexes, as indicated by the clear dose-dependent decrease in GSI at 270 and 400 dph. The results showed that exposure to E2 during the early life stages of tiger puffer disrupted gonadal development, but that fish recovered after migration to clean seawater. The study suggests the potential use of tiger puffer as a valuable indicator species to evaluate the effects of environmental estrogens on marine fish, thereby protecting valuable fishery resources.  相似文献   

5.
Present-day conditions of the Lake Kenon ecosystem are determined by a combination of natural and anthropogenic factors.We have estimated the effects of a complex of factors on the condition of the abiotic environment and on specific biological components in the lake ecosystem.Change in biogenic load has caused an increase in the role of phytoplankton in the general balance of organic matter during the high-water period.Charophytes are the main dominants of bottom vegetation.Anthropogenic load has caused a decrease in both fish species and fish capacity.The lake application as a water reservoir-cooler has influenced the average annual water mineralization(from 420 mg/L to 530.0 mg/L with a maximum 654 mg/L in 1993) and fluctuations in its hydrochemical composition.The present composition of the lake is sulfate-hydrocarbonate-chloride calcium-sodic-magnesium in character.SO 4 – content is twice as much as the maximum permissible concentration in fishery waters.Water drainage from an ash disposal area to the lake has caused an increase in chemical-element concentrations including the heavy metals.Hg concentration in Perca fluviatilis muscles is 0.5 μg/g dry wt.Thus,understanding directions in the ecosystem of the water reservoir-cooler under changing hydrological conditions will let us forecast the consequences of new combined heat and power plant operation.  相似文献   

6.
Based on the logical causal relationship and taking Liaoning Province, China, which is the Chinese traditional industrial base and is in the stage of accelerated urbanisation, as a case study, this study builds the ′Urbanisation-Energy Consumption-CO2 Emissions System Dynamics(UEC-SD)′ model using a system dynamics method. The UEC-SD model is applied to analyse the effect of the urbanisation process on the regional energy structure and CO2 emissions, followed by simulation of future production and living energy consumption structure as well as the evolutionary trend of CO2 emissions of three urbanisation scenarios(low speed, intermediate speed and high speed) under the assumed boundary conditions in urban and rural areas of Liaoning Province, China. The results show that the urbanisation process can alter production and the living energy consumption structure and thereby change regional CO2 emissions. An increase in the urbanisation rate in case area will lead to regional CO2 emissions rising in the short term, but when the urbanisation rate approaches 80%, CO2 emissions will reach a peak value and then decrease. Comparison of different urbanisation rates showed that production and living energy consumption exhibit different directions of change and rules in urban and rural areas. The effect of urbanisation on CO2 emissions and energy structure is not direct, and urbanisation can increase the differences in energy and CO2 emissions between urban and rural areas caused by the industrial structure, technical level and other factors.  相似文献   

7.
Guppies( Poecilia reticulata) are considered a candidate model species for the identification and testing of endocrine-disrupting chemicals. Male guppies may be used to address the challenge of making potential linkages between alterations of biomarkers, both at the cellular and organ level, and adverse outcomes. In the present study, a predictive relationship between sex characteristics and reproductive output was observed in male guppies that underwent a long-term toxicity test with 0.5 μg/L 17 β-estradiol administered during the juvenile period. Radioimmunoassay and western blot analyses demonstrated that 17 β-estradiol exposure caused a significant increase in testicular 17 β-estradiol levels as well as the induction of exposure biomarkers, namely hepatic vitellogenin. Exposure to 17 β-estradiol also caused a significant decrease in testosterone levels, which consequently reduced the gonadosomatic index, sperm counts, and the coloration index. These changes of male sexual characteristics further translated into adverse influences on reproduction, as measured by a decrease in offspring production and survival rate. Our results suggest that the above-mentioned sexual characteristics of male guppies may be considered potential in vivo biomarkers of estrogen effects on reproduction.  相似文献   

8.
The effects of recombinant eel growth hormone (reGH).methyltestosterone (MT)and L-thyroxine (T4)on the growth of red sea bream. Pagrosomus major.were investigated.Administration of reGH to fry by immersion at 2 mg 1 for 2 hevery 5 dsys resulted in significant increase in both weight and length.but the condition factor (CF) diminished relative to that of similarly treated controls over the 37day treatment period.Immersion in 0.1 mg:1 T4 also resulted in significant increase in both weight and length and higher survival rate of test fry compared to the controls. Immersion in MT had less effect on growth and high-dose resulted in high mortality.In the second study.injection of 2 μg reGH(gwk)caused a significant increase in the specific growth rate (SGR) of test red sea bream fingerlings relative to that of the controls during the 4-week treatment period and maintained the increasing trend over the post-treatment period (weeks 4-6).Injection of MT at a dosage of 1μg (gwk) resulted in a significant in-creas  相似文献   

9.
Prorocentrum minimum is a bloom-forming, planktonic mixotrophic dinoflagellate, and can cause stress in shrimp ponds. In this study, healthy Exopalaemon carinicauda were exposed to 5 × 104 cells mL-1 P. minimum for 72 hours to investigate the adverse effect of P. minimum on shrimps. Elevated superoxide dismutase(SOD) activity and malondialdehyde(MDA) content, reduced total antioxidant capacity(T-AOC) and catalase(CAT) activity, and regulatory glutathione peroxidase(GPX) activity were found in the hemolymph of E. carinicauda after exposure to P. minimum. In this study, P. minimum exposure induced oxidative stress and caused significant oxidative damage to E. carinicauda. P. minimum exposure increased the expression of HSP70 gene in the hemocyte, gills and hepatopancreas. Compared with the enhanced level of caspase-3 gene mR NA in the hemocyte and gills, the up-regulation of caspase-3 gene in the hepatopancreas was only observed from 3 to 6 h, and then the mRNA level of glutathione-S-transferase(GST) gene increased. These results indicated that GST might be involved in the shrimp hepatopancreas' defense against P. minimum exposure. The present study demonstrates that exposure to P. minimum could induce oxidative stress and apoptosis in E. carinicauda. The SOD activity, HSP70 and GST(in the hepatopancreas) were evoked to protect cells from oxidative stress and apoptosis. This study will provide new insights into the toxic mechanism of P. minimum on shrimps.  相似文献   

10.
Large areas of hypoxic water have recently been reported in the East China Sea. It is hypothesized that hypoxia may be partially responsible for the decline of some fish stocks. We evaluated the effect of hypoxia on large yellow croaker (Pseudosciaena crocea). The fish were exposed to three concentrations of dissolved oxygen (DO; 1.5 mg/L and 2.0 mg/L, and 6.5 mg/L control). We collected blood after 6, 12, 24, 48, and 96 h exposure. There was a significant increase in red blood count, hematocrit, hemoglobin concentration, and mean corpuscular hemoglobin in the group exposed to 1.5 mg/L DO after 6 h or 12 h, and a delayed increase (only elevated after 48 h and 96 h) in these indices in the group exposed to 2.0 mg/L DO. Plasma glucose concentrations increased significantly in both hypoxic groups after 24 h. Furthermore, plasma lactate and lactate dehydrogenase activity increased significantly after the first 6 h exposure in both hypoxic groups. Our results suggest that large yellow croakers could not maintain the aerobic pathway and instead use anaerobic metabolism for survival when DO levels fall below 2.0 mg/L. We conclude that the occurrence of hypoxia (<2 mg/L DO) in the East China Sea could cause metabolic stress for large yellow croakers and may be partially responsible for the population decline of this species.  相似文献   

11.
Freeze-thaw cycles are closely related to the slope instability in high-altitude mountain regions. In this study, cohesive coarse-grained soils were collected from a high-altitude slope in the Qinghai–Tibet Plateau to study the effect of cyclic freeze-thaw on their uniaxial mechanical properties. The soil specimens were remolded with three dry densities and three moisture contents. Then, after performing a series of freeze-thaw tests in a closed system without water supply, the soil specimens were subjected to a uniaxial compression test. The results showed that the stress-strain curves of the tested soils mainly performed as strain-softening. The softening feature intensified with the increasing dry density but weakened with an increase in freeze-thaw cycles and moisture content. The uniaxial compressive strength, resilient modulus, residual strength and softening modulus decreased considerably with the increase of freeze-thaw cycles. After more than nine freeze-thaw cycles, these four parameters tended to be stable. These parameters increased with the increase of dry density and decreased with the increasing moisture content, except for the residual strength which did not exhibit any clear variation with an increase in moisture content. The residual strength, however, generally increased with an increase in dry density. The soil structural damage caused by frozen water expansion during the freeze-thaw is the major cause for the changes in mechanical behaviors of cohesive coarse-grained soils. With results in this study, the deterioration effect of freeze-thaw cycles on the mechanical properties of soils should be considered during the slope stability analysis in high-altitude mountain regions.  相似文献   

12.
Human settlements are the place where human beings live,among which the rural settlements can be regarded as a reflection of human-land relationship in mountain areas because their vertical distribution is greatly influenced by the specific geographical environment and ecological conditions of mountains.Based on field investigation,this paper uses physical,geographical,and ecological theories to make a comprehensive study of rural settlements and mountain disasters in the upper Min River,which is an ecologically fragile area with high-frequency disasters（collapse,landslide,debris flow,etc.） and a minority inhabit district.By applying these modern scientific theories,this paper attempts to shed some light on the relationship between rural settlements and mountain disasters.Consequently,an in-depth understanding of this relationship was achieved as follows：（1） Rural settlements and mountain disasters are mainly distributed in the intercepted flows of water and soil; and both quantity and quality of arable lands in mountains are important indicators of these flows.（2） The Small Watershed Management Project is a complex system of rural settlements and mountain disasters that interacts with and constrains the ecological system.By this project,the human survival will be better guaranteed.Being fundamental for the ecological reconstruction,the coupling mechanism of rural settlements and mountain disasters is not only an engine to promote harmonious development between human and nature,but also a bridge to link them.  相似文献   

13.
Based on the ArcGIS geographic information system and the ORACLE database management system,this paper reports our studies on the technology of Marine Engineering Geological Exploration Information System(MEGEIS). By analyzing system structure,designing function modules and discussing data management,this paper systematically proposes a framework of technol-ogy to integrate,manage,and analyze the seabed information comprehensively. Then,the technology is applied to the design and development of the Bohai Sea Oilfield Paradigm Area Information System. The system can not only meet the practical demands of marine resources exploration and exploitation in the Bohai Sea oilfield,but also serve as a preparatory work in theory and technology for the realization of the 'Digital Seabed'.  相似文献   

14.
The Radial Sand Ridges(RSRs) area in the southern Yellow Sea are subject to tropical and extratropical cyclone activities frequently, in which the special geometry feature and moving stationary tidal system result in complex storm-induced hydrodynamic processes, especially the tide-surge interactions. We studied a rare weather event influenced simultaneously by an extratropical cyclone EX1410 and Typhoon Vongfong as an example to investigate the characteristics of storm surges, wave-surge, and tide-surge interaction in the RSRs area, and applied a high-resolution integrally-coupled ADCIRC+SWAN model, in which the meteorological forcing inputs are simulated by the WRF-ARW model. The model is validated by records from 4 tide gauges and 2 wave buoys along the Yellow Sea coast. Results show that the tide-surge interactions are of considerable regional heterogeneousness. The surge curves at Lüsi(in south RSRs) and Jianggang(in middle RSRs) have abrupt falls near the time of low tide, where the peak occurrence time of interaction residuals tend to shift towards the mid-ebb period. Significant increase of bed shear stress in shallow waters was proved the dominant factor to affect the tide-surge interaction in broad tidal flats of the RSRs area. Differently, the interaction pattern in the Xiyang Trough(in north RSRs), showed a unique rising in mid-flood period due to the phase advances of real surge waves in relatively deep waters. Therefore, we suggested to the local flood risk management that the tide-surge interaction tends to alleviate the flooding risk in the RSRs area around the time of high tide, but aggravate the risk on the rising tide in the Xiyang Trough and on the falling tide in large-scale tidal flats of the southern RSRs area.  相似文献   

15.
Organic pollution is a serious environmental problem in coastal areas and it is important to establish quantitative methods for monitoring this pollution.This study screened a series of sensitive biomarkers to construct an integrated biomarker response(IBR)index using Mytilus edulis.Mussels were exposed to the polycyclic aromatic hydrocarbon anthracene under controlled laboratory conditions and the activities of components of the glutathione antioxidant system,and the concentrations of oxidative-damage markers,were measured in the gills and digestive glands.Anthracene exposure resulted in increased levels of malondialdehyde(MDA)and superoxide radicals(O~ˉ_2?),indicating that oxidative damage had occurred.Correspondingly,anthracene exposure induced increased activities of glutathione S-transferase(GST),glutathione peroxidase(GPx)and reduced glutathione(GSH)in digestive glands,and GPx and glutathione reductase(GR)in gills,consistent with stimulation of the antioxidant system.A fi eld experiment was set up,in which mussels from a relatively clean area were transplanted to a contaminated site.One month later,the activities of GST,GPx and GR had increased in several tissues,particularly in the digestive glands.Based on the laboratory experiment,an IBR,which showed a positive relationship with anthracene exposure,was constructed.The IBR is suggested to be a potentially useful tool for assessing anthracene pollution.  相似文献   

16.
In this study, two common pollutants （benzo[a]pyrene and methamidophos） in marine environment were tested by comet assay for their inducement of in vivo genotoxic effect to the blood cells of black porgy （ Acanthopagrus schlegeli）. The fish was exposed to 2 μg/L of benzo[a]pyrene （BaP） and methamidophos, and their mixture. The assay was performed on whole blood at 2 h, 5 h, 24 h and 96 h exposure intervals. A significant increase in DNA damage was observed in each treatment with the pollutants. Additive effect of BaP and methamidophos was also found in the experiment. However, the decrease ratios of DNA damage for 5 h and 96 h exposure interals compared with 2 h and 24 h exposure ones, respectively, were noticed. This phenomenon may be explained by the function of repairing process via enzyme cytochrome P450 in the animal. Evidence of the genotoxicity of organophosphorus pesticides （OPs） and polynuclear aromatic hydrocarbons （PAHs） on marine fish are discussed in this paper.  相似文献   

17.
Desertification is an environmental issue in the world. The salt-alkalization desertification land area formed by both primary and secondary salt-alkalization has extended in a large scale, which has become a significant eco-environmental problem. Based on the characteristics of eco-environment and the situation of desertification in western Songnen plain, this paper reports the analyzes of its formation in background and cause. An early warning system on the salt-alkalization desertification is established and the GIS technology is used to abstract the information of desertification evaluation index. Supported by the integrated technology of the GIS and ANN, the orientation and quantitative result of desertification are gained, which is helpful to the eco-environment protection and resource development in western Songnen Plain.  相似文献   

18.
The effects of changing salinity and nitrogen limitation on dimethylsulfoniopropionate(DMSP) and dimethylsulfide(DMS) concentrations were investigated in batch cultures of coastal diatom Skeletonema costatum,an ecologically important species.Changes in salinity from 20-32 caused no measurable variation in cell growth or culture yield,but increased intracellular DMSP per cell by 30%.Nitrogen limitation caused up to a two-fold increase in total DMSP per cell and up to a three-fold increase in DMS per cell.These changes in DMSP and DMS per cell in the Skeletonema costatum cultures with nitrogen limitation and changing salinity were primarily attributed to the physiological functions of DMSP as an osmolyte and an antioxidant.The data obtained in this study indicated that nitrogen limitation and salinity may play an important role in climate feedback mechanisms involving biologically derived DMS.  相似文献   

19.
Urbanization strategic environmental assessment （SEA） is an effective instrument to enhance the harmonious development of urban complex system, integrating of environment and development in decision-making. Urbanization strategic environmental assessment integration technology system （SEA-ITS） is composed of ＂3S＂ （RS, GIS and GPS）, environmental expert system and environmental model system, coupling with appropriate SEA working process closely. In this paper, the structure and components of SEA-ITS are analyzed based on Chinese characteristics, meanwhile methods to fulfill the following system functions are discussed： urbanization SEA inquiring, analysis, discrimination, assessment, prediction, decision-making and output. Moreover, methods and technologies employed in different urbanization SEA hierarchies are summarized. As a case study, urbanization SEA-ITS is applied in Changchun City to solving complex real problems. Methods such as system dynamics and grey cluster are adopted to achieve the environmental impact assessment on the eco-industrial system planning. It is revealed that the system designed is capable of reflecting the dynamic behavior of eco-industrial system under different scenarios, meanwhile accomplishing strategy optimization and supplying scientific reference. The 4th strategy, namely concerning on economy increase and its interaction with science, technology and environment progress, would have the best efficiency. Further, more attention should be paid to the secondary development of integration techniques and function modification system of urbanization SEA-ITS.  相似文献   

20.
China′s economy and transport infrastructure have both experienced rapid development since 1978, and especially since 1990. Today, China is the second-largest economic entity in terms of GDP and has the largest high-speed rail(HSR) network and the second-largest expressway network in the world. This paper explores the relationship between accessibility and economic growth in China from 1990 to 2010. In the study, the basic research units include 333 prefecture-level cities and four municipalities. We explore a bivariate analysis framework of accessibility and economic growth, and their increase rates, to examine this relationship using long-term panel data. The results indicate that, first, accessibility and economic growth show a significant positive relationship using both cross-section and panel data, while the increase rate in accessibility and GDP indicate no significant relationship using cross-section data and a poor significant relationship using panel data. Second, the distributions of local advantage are uneven. Cities with low local advantage with respect to accessibility and GDP are mainly located in China′s eastern coastal region or the provincial capitals, while those with low local advantage in terms of their increase rates are located in the western region. Third, as China′s economic growth and transport networks have evolved, the distribution of local advantage shows little change in terms of accessibility and GDP, but a greater change in terms of their increase rates, which is largely influenced by the distribution of expressway and HSR networks.  相似文献   

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