共查询到19条相似文献，搜索用时 859 毫秒
1.
KANG Yanyu LIANG Junrong GAO Yahui LIN Rongcheng GAO Hu XING Xiaoli MA Jie LUO Qiaoqi 《海洋学报(英文版)》2007,26(5):107-115
The growth and interspecies competition of two red tide algal species Thalassiosira pseudonana Hasle et Heimdal and Gymnodinium sp.were studied under different concentration ratios of nitrogen to phosphorus,and the algal batch culture experiments were conducted.The physiological and biochemical indexes were measured periodically,including the maximum comparing growth rate,relative growth rate,average double time and chlorophyll a concentration.The results showed that when the concentration ratio of nitrogen to phosphorus was 16:1,the maximum comparing growth rate,relative growth rate and chlorophyll a concentration of Thalassiosira pseudonana all reached the highest,and average double time was the shortest.This implied that the optimal concentration ratio of nitrogen to phosphorus of Thalassiosira pseudonana is 16:1.When the concentration ratio of nitrogen to phosphorus was 6:1,the maximum comparing growth rate,relative growth rate and the chlorophyll a concentration of Gymnodinium sp.reached the highest,and average double time was the shortest,so the optimal concentration ratio of nitrogen to phosphorus of Gymnodinium sp.is 6:1.From the growth curves as indicated both in the cell density and the chlorophyll a concentration,it is suggested that the influence of concentration ratio of nitrogen to phosphorus on the chlorophyll a concentration and the cell density are almost the same.Different concentration ratios of nitrogen to phosphorus had weak influence on community succession and the competition between the two algae.Gymnodinium sp.may use the phosphorus in vivo for growth,so it is important to pay attention to the concealment of phosphorus,in order to avoid the outbreak of red tide.On the basis of the importance of nitrogen and phosphorus and the ratio of their concentration,the possible outbreak mechanism of red tide of the two algae was also discussed. 相似文献
2.
In recent years, the red tide erupted frequently, and caused a great economic loss. At present, most literatures emphasize the academic research on the growth mechanism of red tide alga. In order to find out the characters of red tide in detail and improve the precision of forecast, this paper gives some new approaches to dealing with the red tide. By the extreme values, we deal with the red tide frequency analysis and get the estimation of T-times red tide level U （T） , which is the level once the consistence of red tide alga exceeds on the average in a period of T times. 相似文献
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Observations of fluid mud were made in the lower North Passage of the Yangtze Estuary in February 2000, on 10 -11 August 2000, on 30 - 31 August 2000 (after two strong typhoons), on 21 - 24 August 2000 (neap tide) and on 3 -6 September 2000 (mean tide) respectively. In situ data show that the fluid mud in this area consists of fine cohesive sediment (median size 7.23 μm). The formation and movement of fluid mud varied during the neap-spring and flood-ebb tidal cycle. Observations suggest that fluid mud phenomena in this area may be categorised in a three-fold manner as slack water, storm and saltwedge features. The thickness of the fluid mud layer of slack water during the neap tide ranged from 0.2 to 0.96 m, whereas during the mean tide, the thickness ranged from 0.17 to 0.73 m, and the thickness of the fluid mud layer was larger during slack water than at the flood peak. Shoals cover an area of 800 km^2 with a water depth smaller than 5 m. Erosion of these extensive intertidal mudflats due to storm action provides an abundant sediment source. This is particularly significant in this estuary when the tidal level is lower than 5 m. The lower North Passage is a typical zone of saltwater wedging, so the saltwedge fluid mud has the most extensive spatial range in the estuary. 相似文献
4.
From November 24 to 26, 2014, a red tide event occurred in the offshore water off the Hailing Island located at the western Guangdong coast. The red tide appeared as pink strips distributed within 3 km in the offshore water and extended for about 10 km along the shoreline. During the flood tide, the pink seawater rushed to the beach with breaking waves, forming foam strips on the beach. Guangdong Province Key Laboratory for Coastal Ocean Variation and Disaster Prediction Technologies, Guangdong Ocean University, emergently responded to the event and organized three-dimensional observations from the air, onboard and on beach. The preliminary analyses of the cruise data and water samples indicate that the event was induced by nontoxic Noctiluca scintillans, of which the concentration reaches as high as 4 200 cells/L near the surface and 2 600 cells/L at the bottom. 相似文献
5.
The 25-h measurements of current speed, flow direction, water depth, suspended sediment concentration and salinity were carried out at six anchored stations in the study area during spring and neap tides in winter of 1987 and summer of 1989. Caculations and analyses of the data obtained show that large amounts of suspended sediments are moved back and forth under the action of tidal current, and the net transport of sediment is small, with its predominance upstream in winter and downstream in summer. These calculations and analyses also suggest that the advective transport of sediment is dominant, while the vertical gravitational circulation of the suspended sediment comes next. Meantime, it is indicated that tidal currents play a major role in the suspended sediment transport, and residual flows have effect on the net transport of the suspended sediment, which is more remarkable during neap tide than during spring tide. 相似文献
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The Changjiang (Yangtze) Estuary is located in the East China Sea shelf with shallow water. Affected by the tide mixing and the runoff of the Changjiang River and the Qiantang River, the turbidity is very high. Generally, the water-leaving radiance is high in the turbid water because of the large particle scattering. Based on the in-situ data and ocean color remote sensing data of SeaWiFS, it was found that there was a black water region with the normalized water-leaving radiances less than 0.5 mW/(cm2·μm2·... 相似文献
7.
Sediment transport capacity is a fundamental parameter in sediment transport theory and its accurate calculation is important from both theoretical and engineering viewpoints. The capacity of sediment transport has been studied extensively by many researchers in the last decades. Nevertheless, the underlying mechanism behind sediment transport capacity in estuaries remains poorly understood. The current study aims to explore the impact of the river–tide interaction on sediment transport and establish a formula of sediment transport capacity under the river–tide interaction. The impact of the river–tide interaction on the hydrodynamics and sediment dynamics in the Changjiang Estuary was analyzed, a practical method for describing the variation in tide-runoff ratio was established,and a formula of sediment transport capacity considering the impact of river–tide interaction was proposed by introducing the tide-runoff ratio. The new method bridged the gap between two well-known sediment transport capacity methods by considering the variation in the index a for the gravitational term and overcomes the drawback of distinguishing flood/dry season or spring/ebb tide in the calculation of estuarine sediment transport. A large amount of flow and sediment data obtained from the Changjiang Estuary were collected to verify the proposed formula. The effect of salt-fresh water mixture and the morphological evolution on sediment transport capacity of the Changjiang Estuary were discussed. 相似文献
8.
The tidal current is generally predominant in China's offshore areas. The vertical structure of the observedtidal current is quite complicated with the presence of seasonal thermocline. The observed tidal current may be divided into two parts, an averaged barotropic tide current and a variation tide current. A method for studying the vertical structure of tidal current is developed from the constitution and distribution of energy, and the vertical structure of the observed tide current in the North Huanghai Sea is studied on the basis of the method. The result shows that the reason why the energy of the tidal current is concentrated on the neighbourhood of the thermocline mainly lies in the internal tides i under certain conditions, the fact that the direction of the internal tide current above the thermocline is opposite to the one below the thermocline will be able to cause the rotary directions of the observed tidal current above and below the thermocline to be in opposite. The interaction between th 相似文献
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In the paper, the sea is divided into two layers with density jumping, assuming that the physical parameters in each layer are independent of depth. Two-layer flow field with tide and wind currents is calculated with extended ADI method, after the calculation for flow field is stable , coupled with temperature diffusion equations and thermohaline depth prediction equation, a four-day time prediction of the surface, bottom temperature and thermohaline depth of the Huanghai and the Bohai Seas. At the same time, three dimensional temperature field of sea water is predicted through vertical temperature distribution function. The result indicates that the prediction quality of the whole model and the fitting degree between the predicted result and the measured values are satisfactory. 相似文献
11.
赤潮形成与富营养化及生化防治机理——污水深度处理与脱氮除磷 总被引：2，自引：0，他引：2
讨论了藻类形成的生化机理 ,富营养化水体中大量氮、磷的存在是藻类暴发性增殖、形成赤潮的主要原因。减少水体富营养化是防止赤潮的重要途径。污水深度处理及脱氮除磷 ,是根治海洋赤潮的根本方法。对赤潮成因及根本防治提出新见解。 相似文献
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甲藻赤潮与水体中营养盐的关系初探 总被引：8，自引：0，他引：8
作者在国家海洋局第三海洋研究所的陆基水池中，应用围隔实验技术，排除了水动力、盐度等环境因子的变动性的干扰，人工诱发甲藻赤潮．在这个围隔实验的两个围隔体中，分别发生了一种裸甲藻（Gymnodinium
sp.）和海洋原甲藻（Prorocentum micans）的赤潮．在赤潮发生和发展过程中所监测到的营养盐数据表明有些甲藻增殖不一定需要水体中高营养盐；营养盐供给的多寡会导致甲藻赤潮优势种的差异和赤潮规模． 相似文献
15.
Young Baek Son Joji Ishizaka Jong-Chul Jeong Hyun-Choel Kim Taehee Lee 《Ocean Science Journal》2011,46(4):239-263
To distinguish true red tide water (particularly Cochlodinium polykrikoides blooms) from non-red tide water (false satellite high chlorophyll water) in the South Sea of Korea, we developed a systematic
classification method using spectral information from MODIS level products and applied it to five different harmful algal
bloom events. Red tide and nonred tide waters were classified based on four different criteria. The first step revealed that
the radiance peaks of potential red tide water occurred at 555 and 678 nm. The second step separated optically different waters
that were influenced by relatively low and high contributions of colored dissolved organic matter (CDOM) (including detritus)
to chlorophyll. The third and fourth steps discriminated red tide water from non-red tide water based on the blue-to-green
ratio in areas with lower and higher contributions of CDOM to chlorophyll, respectively. After applying the red tide classification
(using the four criteria), the spectral response of the red tide water, which is influenced by pigment concentration, showed
different slopes for the blue and green bands (lower slope at blue bands and higher slope at green bands). The opposite result
was found for non-red tide water, due to decreasing phytoplankton absorption and increasing detritus/CDOM absorption at blue
bands. The results were well matched with the discoloration of water (blue to dark red/brown) and delineated the areal coverage
of C. polykrikoides blooms, revealing the nature of spatial and temporal variations in red tides. This simple spectral classification method
led to increase user accuracy for C. polykrikoides and non-red tide blooms (>46% and >97%) and provided a more reliable and robust identification of red tides over a wide range
of oceanic environments than was possible using chlorophyll a concentration, chlorophyll anomaly, fluorescence analysis, or proposed red tide detection algorithms. 相似文献
16.
赤潮是最严重的海洋灾害之一,它不仅破坏海洋渔业生产、恶化海洋环境、影响滨海旅游业,而且还会影响人类健康。东海是我国赤潮灾害的“高发区”,赤潮发生次数和面积均明显高于其它海区。遥感是赤潮监测的最有效的手段之一,从光谱曲线可以看出,赤潮水体和非赤潮水体光谱曲线有明显的区别,前者呈现出2个吸收峰和2个反射峰,而后者不具备该特征。基于光谱差异,本文提出了1种新的赤潮提取算法:Rrs555/Rrs488>1.5且Rrs678-Rrs667>0。该算法能有效地确定卫星数据中赤潮的位置,与公报的赤潮位置吻合得较好。因此,该算法适用于卫星数据的东海赤潮信息提取。 相似文献
17.
伴随广西北部湾经济区的建立与开发,北部湾海域污染加剧,赤潮灾害愈发严重。文章综述1984—2015年广西北部湾海域赤潮演变趋势,结果表明:①赤潮发生频率和发生面积逐年增加;②赤潮种类呈现增多趋势。通过分析赤潮演变趋势,提出防控的思路:①加强广西北部湾入海流域及沿海地区污染防治和近岸海域环境保护;②利用生物技术进行赤潮生物防控;③加强科技支撑和提升赤潮科学研究能力。 相似文献
18.
Zhang Shuijin 《海洋学报(英文版)》1994,13(4):589-600
ＡｎａｌｙｓｉｓｏｆｔｈｅｄｅｖｅｌｏｐｍｅｎｔａｎｄｃａｕｓｅｓｏｆｆｏｒｍａｔｉｏｎｏｆＥｕｃａｍｐｉａｚｏｏｄｉａｃｕｓｒｅｄｔｉｄｅｉｎＸｉａｍｅｎＨａｒｂｏｒ￥ＺｈａｎｇＳｈｕｉｊｉｎ（ＲｅｃｅｉｖｅｄＪｕｎｅ２０，１９９４；ａｃｃｅｐｔｅ... 相似文献
19.
隍城岛海域塔玛亚历山大藻赤潮发展过程及其成因 总被引：1，自引：0，他引：1
2006年9月,南隍城岛附近海域首次发生由塔玛亚历山大藻(Alexandrium tamarense)引发的大规模赤潮,面积约2.37 km~2,最大细胞丰度2.334×10~8cell/L,大量衰亡赤潮生物的分解消耗水体的溶解氧,引起中下层水体严重缺氧,导致当地网箱养殖的鱼类全部死亡,藻体分泌的麻痹性贝毒(PSP),导致岸边的皱纹盘鲍近一半死亡.通过对这次赤潮的研究认为:其成因主要是由船舶压舱水排海带来赤潮生物物种,大量陆源有机物、营养盐类的排入和大规模贝类筏式养殖的自身污染为赤潮生物的暴发性繁殖提供了丰富的物质基础,适宜的水文气象条件为赤潮的发生提供了良好的繁殖环境. 相似文献