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1.
Based on the historical evolution of the Hangzhou Bay, by making use of the conclusions made by the previous research workers and the integration of concrete data, five distinct impact indicators of the sediment from the Changjiang Estuary and the East China Sea to the Hangzhou Bay are summarized. Numerical calculation and analysis indicate that the scouring and deposition of seabed in the Hangzhou Bay are subject to the direct impact of the evolution of the Changjiang Estuary, and the growth and decline and the direction of the sandy bar at Nanhuizui give traces to the sediment transport between the Changjiang Estuary and the Hangzhou Bay. The transport of sediment from the Changjiang Estuary to the Hangzhou Bay occurs mainly in winter and spring seasons and the increase of the Changjiang River runoff and the decrease of sediment charge have caused scouring in the northern coast of the Hangzhou Bay and the seabed erosion along the frontal margin of the Changjiang River Delta.  相似文献   

2.
I~IOWIn winter, on the impacts Of the Chriolis force and the current along the shore of the EastChina ho, the residual current from the Changjiang River flows south along the shore and enters the ~ Bay in the north, then it moves out of the bay in the south and flows southin the East China Sea (Su and Wang, 1989; Zhu and Shen, 1997). In recent years, scholars have made further analyse on obSerVed date, and have obtained more profound viewson the residual current and mass transport (Pn …  相似文献   

3.
In this paper,the analysis of the occurrence and the development of typhoon and tropical cyclone is made with the unstable theory of wave. The result indicates that the primary wave is the unstable inertia-gravity wave in the process of the occurrence and the deveJopmant of typhoon and tropical cyclone: The existence of the deep moist layer and the heating by moisture condensation can impel and intensify the unstability of the wave and is favourable for the reduction of the wave energy dispersion, therefore, it is good for the formation and the development of typhoon and tropical cyclone, and also can slow down the wave speed. Besides, the condition that the change of the specific volume of the basic state with pressure is less than that of adiabatic state may also lead to the wave unstability, thus may have certain effect on the occurrence and the development of typhoon and tropical cyclone.  相似文献   

4.
The protection of the biological diversity and the maintenance of the regional ecological integrity for the Huanghe （Yellow River） Estuary and its adjacent areas are practically significant and valuable. However, frequent human activities and natural climate changes have caused vigorous disturbances on the ecosystem in these sea areas. An objective assessment on the benthic habitat quality （BHQ） of the Huanghe Estuary and its adjacent areas is conducted, using AZTI＇s Marine Biotic Index （AMBI） and multivariate AMBI （M-AMBI） based on the data of macrobenthos in May and August 2011. The results show that both the indices do not correlate significantly, and their assessment results are greatly different. All of the samples assessed using the AMBI were ＂high＂ or ＂good＂, because the ecological group I （EGI） and the ecological group II （EGII） were dominant macrobenthic ecological groups in the research area. Owing to a low species＇ richness and a high individual abundance in some samples, the BHQ levels using the M-AMBI were worse than those of the AMBI. Significant correlations are observed between the M-AMBI, water depth, bottom water salinity and dissolved inorganic nitrogen, thus the M-AMBI could sensitively respond to environmental changes and distinguish influences from uninfluenced stations, but the AMBI could not. The consistent results between the AMBI and the M-AMBI mainly appeared in the uninfluenced （undisturbed or slightly disturbed） sta- tions. Therefore, the M-AMBI is more effective than the AMBI in assessing the benthic habitat quality in the Huanghe Estuary and its adjacent areas. Using the M-AMBI to assess the BHQ of the Huanghe Estuary and its adjacent areas, the results show that 3% of the stations are undisturbed and the BHQs are ＂high＂, and 61% of the stations are slightly disturbed and those of the BHQ are ＂good＂, and the rest are meanly disturbed and those of the BHQ are ＂moderate＂.  相似文献   

5.
Based on the analysis of the characteristics of the fossils (mollusks, Radiolaria, planktonic and benthicForaminifera and Ostracoda) found in the four loess profiles located respectively at Heishigou and Beizhuang Villages on Daheishan Island in the Miaodao Islands in the Bohai Straits, and Daweijia and Yujiawaizi Villages in Jinzhou County, Liaodong Peninsula, the distribution and abundance variation of the fossils in vertical profiles are studied, the source of coastal loess is probed and the relationship between loess deposition and paleoclimatic environment as well as sea-level changes is discussed.  相似文献   

6.
The main processes of interaction between the coastal water, shelf water and Kuroshiowater in the Huanghai Sea (HS) and East China Sea (ECS) are analyzed based on the observation and study results in recent years. These processes include the intrusion of the Kuroshio water into the shelf area of the ECS, the entrainment of the shelf water into the Kuroshio, the seasonal process in the southern shelf area of the ECS controlled alternatively by the Taiwan Strait water and the Kuroshio water intruding into the shelf area, the interaction between the Kuroshio branch water, shelf mixed water and modified coastal water in the northeastern ECS, the water-exchange between the HS and ECS and the spread of the Changjiang diluted water.  相似文献   

7.
The offshore waters of the Changjiang Estuary are the transitional areas where river-supplied water and sediment are transported to the sea, and material exchanges occur with the neighbored Hangzhou Bay and the Jiangsu waters. Field observations of currents and sediment properties were conducted to study temporal and spatial distributions of suspended sediments under various dynamical conditions. The high sediment concentrations were found to occur in the western and southern waters of the offshore, and the low concentrations occurred in the eastern and northern waters. This pattern of the suspended sediment concentration (SSC) distribution is obviously influenced by the runoff and tidal current. The significant difference of along-estuary SSC distribution indicates that the SSC is reduced gradually from the west to the east, and that in the spring tide is obviously higher than in the neap tide. The methods of mechanism analysis and equal-area grids were used to calculate the suspended sediment fluxes at the typical cross sections. It was found that 44 percent of total suspended sediments from the Changjiang River were deposited in the submarine delta, and more than 27 percent of sediments were transported southernly into the Hangzhou Bay, and only 9 percent of sediments was supplied and exchanged with the northern Jiangsu waters, and about 20 percent of sediments was delivered offshore to the sea.  相似文献   

8.
A simulation of radiation imagery for ocean color satellite   总被引：2，自引：0，他引：2  
The ocean color satellite is mainly applied to measure the water constituents such as chlorophyll, suspended material and yellow substance. The leaving water radiance is very small part of the total radiance arrival at the sensor about 3%-15%,and depends on the properties of the orbit and sensor. Before the satellite is launched on the orbit, it needs to simulate the radiation imagery in order to evaluate the quality and availability of the satellite data.
If the parameters of satellite orbit, the properties of sensor as well as the characteristics of the atmosphere and water have been known, the radiation scattered by air molecule and aerosol, reflected solar radiation, water leaving and total radiation arriving at the sensor can be simulated by the models of radiation transfer in the atmosphere, air/water and subsurface water. In this paper, the mechanism, models and procedures of the radiation simulation are first discussed and employed to simulate a series of imageries for the Chinese satellites FY-lA, FY-1B, and ROCSAT-1 (Taiwan, China), and American satellite Ses STAR. Their results show that the solar irradiance arrived at water surface and the sun glitter mainly affect the quality and availability of satellite data, which depend on the orbit properties. Finally, some suggestions are proposed to improve the quality and availability of a:ean color satellite data.  相似文献   

9.
The estuary and coast is an area where the land and the sea interact and a place in which human beings frequently move about so that understanding and controlling the change and development modes of the coastal landform plays a vital part in exploiting and protecting coastal resources. A model is the generalization and abstraction of objective things. This paper summarizes four methods for the landform development of the tidal shore and underwater delta, mainly discusses the model‘s structural elements, and presents their specific application on the basis of the authors‘ case study. With the application of the profile model, the dynamic change of coastal landform can be clearly seen by contrasting the different profiles of different years. Through the shrinking, expanding and transformation of the isobath, plane model is used to study the macro-change of the shoal and the coastal landform. Speed model is an efficient means to analyze the trend of erosion and deposition and the local change in a great area of the sea. Statistical survey model is a static analysis, which can be used to establish the relationship between the erosion and deposition of the shoal and the altitude and slope of survey spot.  相似文献   

10.
A recent island survey reveals that the Xuande Atoll and the Yongle Atoll in the Xisha Islands can be classified into one of two systems: the depleted atoll system and growth atoll system; the survey also indicates that the decreased area of several shoals is an unbearable burden for the Xisha Islands, of which the largest island area is 2.13 km2 and the minimum elevation is 1.4 m. According to a survey on the ecological characteristics of Halimeda in the Laolongtou breaker zone of Shidao Island in the Xisha Islands, the green and white living Halimeda are collected,the isotopic ages of 14 C contained in the Halimeda are shown to be 27 years and 55 years, respectively, and carbonate mainly occurs in five types, i.e., luster, segment, sand, sand grain, and marl in the formation. The Halimeda segments mainly provide the carbonate sediments of long-term biogenic deposits in the reef environment and the annual productivity per area is 60–100 g/m2; the characteristics of the microstructure of the Halimeda are analyzed, the aragonite raphide carbonate is deposited and enriched in the cortexes, medullas and cysts, and the Halimeda generally contain major elements such as C, O, Ca, Cl, Mg, K, Na, S and Al, and are rich in trace elements such as tellurium(Te), rhodium(Rh) and strontium. It is believed that the Halimeda grow slowly,including the biotic community of reef corals in the reef areas, thus they possess an environmental remediation capacity, but it takes much time to remedy the environment, and it is necessary to make the law to protect the diversity and vulnerability of the Xisha marine ecology, the ecology of the reef community and the island environment in a scientific way. As indicated in the survey, under the background of global warming and sea-level rise, the discovery of large amounts of Halimeda in the Laolongtou sea area is significant for the natural increase of the depleted atoll system of the Xuande Atoll, while the Halimeda segments represent the primary form of the fossil Halimeda, of which the species can be identified and preserved in great numbers under geological conditions. The Miocene was discovered in large amounts in the Xichen-1 well, therefore the study on the characteristics and mechanism of Halimeda carbonate sediments plays a pivotal role in the formation and construction of organic reefs in the South China Sea as well as oil and gas exploration.  相似文献   

11.
Upwelling occurs on the coast of Java between June and October, forced by local alongshore winds associated with the southeasterly monsoon. This causes variations in phytoplankton community composition in the upwelling zone compared with the surrounding offshore area. Based on pigments analysis with subsequent calculations of group contributions to total chlorophyll a(Chl a) using CHEMTAX, we studied the distribution and composition of phytoplankton assemblages in the subsurface chlorophyll maximum along the south coast of Java and the influence of upwelling. Nineteen phytoplankton pigments were identified using high-performance liquid chromatography, and CHEMTAX analysis associated these to ten major phytoplankton groups. The phytoplankton community in the coastal area influenced by upwelling was characterized by high Chl a and fucoxanthin concentrations, indicating the dominance of diatoms. In contrast, in the offshore area, the Chl a and fucoxanthin concentrations declined to very low levels and the community was dominated by haptophytes represented by 19′-Hexanoyloxyfucoxanthin. Accordingly, microphytoplankton was found to be the major size class in the coastal area influenced by upwelling, while nanophytoplankton was most abundant in the offshore area. Low concentrations of other accessory pigments indicated less contribution from dinoflagellates,prasinophytes, chlorophytes and cryptophytes. Photo-pigment indices revealed that photosynthetic carotenoids(PSCs) were the largest component of the pigment pool, exceeding the proportion of Chl a, with the average PSCTP up to 0.62. These distribution trends can mainly be explained by phytoplankton adaption strategies to upwelling and subsurface conditions by changing species composition and adjusting the pigment pool.  相似文献   

12.
本文依托2008年夏季中国第三次北极科学考察航次,对西北冰洋海盆区和楚科奇海陆架营养盐及光合色素进行了测定和分析。根据海水理化性质将研究海区分为5个区,并使用CHEMTAX软件（Mackery et al.,1996）讨论了西北冰洋不同海区浮游植物群落组成结构及其与环境因子之间的关系。结果显示在楚科奇海陆架区,太平洋入流显著影响浮游植物生物量和群落结构。高营养盐Anadyr水团以及白令陆架水控制海域,表现出高Chl a且浮游植物以硅藻为主,相反,低营养盐如阿拉斯加沿岸流控制海域,Chl a生物量低且以微型,微微型浮游植物为主。在外陆架海区,海冰覆盖情况影响着水团的物理特征及营养盐浓度水平,相应地显著影响浮游植物群落结构。在海冰覆盖区域,硅藻生物量站到总Chl a生物量的75%以上;在靠近门捷列夫深海平原海区,受相对高盐的冰融水影响（MW-HS）,营养盐浓度和Chl a浓度相对海冰覆盖区略高,浮游植物结构中微型、微微型藻类比重增加,硅藻比例则降至33%;南加拿大海盆无冰海区（IfB）,表层水盐度最淡,营养盐浓度最低,相应地显示出低Chl a生物量,表明海冰消退,开阔大洋持续时间延长,将导致低生物量及激发更小型浮游植物的生长,并不有利于有机碳向深海的有效输出。  相似文献   

13.
CHEMTAX analysis of high-performance liquid chromatography(HPLC) pigment was conducted to study phytoplankton community structure in the northern Bering Sea shelf, where a seasonal subsurface cold pool emerges. The results showed that fucoxanthin(Fuco) and chlorophyll a(Chl a) were the most abundant diagnostic pigments, with the integrated water column values ranging from 141 to 2 160 μg/m2 and 477 to 5 535 μg/m2, respectively. Moreover, a diatom bloom was identified at Sta. BB06 with the standing stock of Fuco up to 9 214 μg/m3. The results of CHEMTAX suggested that the phytoplankton community in the northern Bering Sea shelf was dominated by diatoms and chrysophytes with an average relative contribution to Chl a of 80% and 12%, respectively, followed by chlorophytes, dinoflagellates, and cryptophytes. Diatoms were the absolutely dominant algae in the subsurface cold pool with a relative contribution exceeding 90%, while the contribution of chrysophytes was generally higher in oligotrophic upper water. Additionally, the presence of a cold pool would tend to favor accumulation of diatom biomass and a bloom that occurred beneath the halocline would be beneficial to organic matter sinks, which suggests that a large part of the phytoplankton biomass would settle to the seabed and support a rich benthic biomass.  相似文献   

14.
中尺度涡影响下的南海西部活性铝分布   总被引：1，自引：0，他引：1  
To understand the distribution of aluminum(Al) under the influence of mesocale eddies in the western South China Sea(SCS), sea level anomaly, geostrophic current, environmental parameters and reactive Al were investigated in the western SCS in August 2013. The highest reactive Al concentration((180±64) nmol/L) was observed in the surface waters, indicating a substantial atmospheric input. Vertically, the reactive Al decreased from the surface high concentration to the subsurface minima at the depth of chlorophyll a(Chl a) maxima and then increased again with depth at most of the stations. The average concentration of reactive Al in the upper 100 m water column was significantly lower in the cyclonic eddy((137±6) nmol/L) as compared with that in the noneddy waters((180±21) nmol/L). By contrast, the average concentrations of Chl a and silicate in the upper 100 m water column were higher in the cyclonic eddy and lower in the anticyclonic eddy. There was a significant negative correlation between the average concentrations of reactive Al and Chl a in the upper 100 m water column. The vertical distribution of reactive Al and the negative correlation between reactive Al and Chl a both suggest that the reactive Al in the upper water column was significantly influenced by biological removal processes. Our results indicate that mesoscale eddies could regulate the distribution of reactive Al by influencing the primary production and phytoplankton community structure in the western SCS.  相似文献   

15.
The South China Sea(SCS) and the Arabian Sea(AS) are both located roughly in the north tropical zone with a range of similar latitude(0°–24°N). Monsoon winds play similar roles in the upper oceanic circulations of the both seas. But the distinct patterns of chlorophyll a(Chl a) concentration are observed between the SCS and the AS.The Chl a concentration in the SCS is generally lower than that in the AS in summer(June–August); the summer Chl a concentration in the AS shows stronger interannual variation, compared with that in the SCS; Moderate resolution imaging spectroradiometer(MODIS)-derived data present higher atmospheric aerosol deposition and stronger wind speed in the AS. And it has also been found that good correlations exist between the index of the dust precipitation indicated by aerosol optical thickness(AOT) and the Chl a concentration, or between wind and Chl a concentration. These imply that the wind and the dust precipitation bring more nutrients into the AS from the sky, the sub-layer or coast regions, inducing higher Chl a concentration. The results indicate that the wind velocity and the dust precipitation can play important roles in the Chl a concentration for the AS and the SCS in summer. However aerosol impact is weak on the biological productivity in the west SCS and wind-induced upwelling is the main source.  相似文献   

16.
Phytoplankton composition and biomass across the southern Indian Ocean   总被引：2，自引：0，他引：2  
Phytoplankton composition and biomass was investigated across the southern Indian Ocean. Phytoplankton composition was determined from pigment analysis with subsequent calculations of group contributions to total chlorophyll a (Chl a) using CHEMTAX and, in addition, by examination in the microscope. The different plankton communities detected reflected the different water masses along a transect from Cape Town, South Africa, to Broome, Australia. The first station was influenced by the Agulhas Current with a very deep mixed surface layer. Based on pigment analysis this station was dominated by haptophytes, pelagophytes, cyanobacteria, and prasinophytes. Sub-Antarctic waters of the Southern Ocean were encountered at the next station, where new nutrients were intruded to the surface layer and the total Chl a concentration reached high concentrations of 1.7 ??g Chl a L−1 with increased proportions of diatoms and dinoflagellates. The third station was also influenced by Southern Ocean waters, but located in a transition area on the boundary to subtropical water. Prochlorophytes appeared in the samples and Chl a was low, i.e., 0.3 ??g L−1 in the surface with prevalence of haptophytes, pelagophytes, and cyanobacteria. The next two stations were located in the subtropical gyre with little mixing and general oligotrophic conditions where prochlorophytes, haptophytes and pelagophytes dominated. The last two stations were located in tropical waters influenced by down-welling of the Leeuwin Current and particularly prochlorophytes dominated at these two stations, but also pelagophytes, haptophytes and cyanobacteria were abundant. Haptophytes Type 6 (sensuZapata et al., 2004), most likely Emiliania huxleyi, and pelagophytes were the dominating eucaryotes in the southern Indian Ocean. Prochlorophytes dominated in the subtrophic and oligotrophic eastern Indian Ocean where Chl a was low, i.e., 0.043-0.086 ??g total Chl a L−1 in the surface, and up to 0.4 ??g Chl a L−1 at deep Chl a maximum. From the pigment analyses it was found that the dinoflagellates of unknown trophy enumerated in the microscope at the oligotrophic stations were possibly heterotrophic or mixotrophic. Presence of zeaxanthin containing heterotrophic bacteria may have increased the abundance of cyanobacteria determined by CHEMTAX.  相似文献   

17.
The EDdy Dynamics, mixing, Export, and Species composition (EDDIES) project provided a unique opportunity to evaluate the response of the microbial community and further understand the biological and biogeochemical consequences of mesoscale perturbation events in an oligotrophic system. In order to characterize microbial dynamics, we performed measurements of bacterial biomass (BB) and production (BP) and phytoplankton pigment analyses in two upwelling eddies in the Sargasso Sea sampled in 2004 and 2005. We also observed a 3-fold increase in BP at the Bermuda Atlantic Time-series Study (BATS) site during the passage of a cyclonic eddy in 2003. Although the integrated BB and BP over 140 m in 2004 and 2005 eddies remained within the climatological range measured at the BATS site, there was systematic variability in bacterioplankton dynamics across both eddies. Cyclonic eddy C1 demonstrated decreased BP at the feature's center relative to its periphery, and BP was not correlated with total chlorophyll a (TChl a) variability. However, BP correlated with prymnesiophyte pigments throughout the feature. In contrast, mode-water eddy A4 showed an enhancement in BP at the eddy center (EC) relative to its edges and was coincident with elevated TChl a, high primary production measurements, and a high concentration of diatoms. In eddy A4, the tight relationship between enhanced BP, TChl a and specific phytoplankton taxa implies that the phytoplankton community structure was an important factor influencing BP variability. While the heterotrophic bacterial response in C1 and A4 was not enhanced relative to BATS summer climatology, these data and the presence of similar nutrient fields across both eddies suggest that BP and BB were influenced by the eddy perturbations and responded to changes in the phytoplankton community.  相似文献   

18.
An integral concept of ecological research is the constraint of biodiversity along latitudinal and environmental gradients. The Red Sea features a natural example of a latitudinal gradient of salinity, temperature and nutrient richness. Coral reefs along the Red Sea coasts are supported with allochthonous resources such as oceanic and neritic phytoplankton and zooplankton; however, relatively little is known about how the ecohydrography correlates with plankton biodiversity and abundance. In this article we present the biodiversity of phytoplankton and zooplankton in Red Sea coral reefs. Oceanographic data (temperature, salinity), water samples for nutrient analysis, particulate organic matter, phytoplankton and zooplankton, the latter with special reference to Copepoda (Crustacea), were collected at nine coral reefs over ~1500 km distance along the Red Sea coast of Saudi Arabia. The trophic state of ambient waters [as indicated by chlorophyll a (Chl a)] changed from strong oligotrophy in the north to mesotrophy in the south and was associated with increasing biomasses of Bacillariophyceae, picoeukaryotes and Synechococcus as indicated by pigment fingerprinting (CHEMTAX) and flow cytometry. Net‐phytoplankton microscopy revealed a Trichodesmium erythraeum (Cyanobacteria) bloom north of the Farasan Islands. Several potentially harmful algae, including Dinophysis miles and Gonyaulax spinifera (Dinophyceae), were encountered in larger numbers in the vicinity of the aquaculture facilities at Al Lith. Changes in zooplankton abundance were mainly correlated to the phytoplankton biomass following the latitudinal gradient. The largest zooplankton abundance was observed at the Farasan Archipelago, despite high abundances of copepodites, veligers (Gastropoda larvae) and Chaetognatha at Al Lith. Although the community composition changed over latitude, biodiversity indices of phytoplankton and zooplankton did not exhibit a systematic pattern. As this study constitutes the first current account of the plankton biodiversity in Red Sea coral reefs at a large spatial scale, the results will be informative for ecosystem‐based management along the coastline of Saudi Arabia.  相似文献   

19.
东亚边缘海区浮游植物春华的纬向与年际变化   总被引：1，自引：1，他引：0  
Combined studies of latitudinal and interannual variations of annual phytoplankton bloom peak in East Asian marginal seas(17°–58°N, including the northern South China Sea(SCS), Kuroshio waters, the Sea of Japan and the Okhotsk Sea) are rarely. Based on satellite-retrieved ten-year(2003–2012) median timing of the annual Chlorophyll a concentration(Chl a) climax, here we report that this annual spring bloom peak generally delays from the SCS in January to the Okhotsk Sea in June at a rate of(21.20±2.86) km/d(decadal median±SD). Spring bloom is dominant feature of the phytoplankton annual cycle over these regions, except for the SCS which features winter bloom. The fluctuation of the annual peak timing is mainly within ±48 d departured from the decadal median peak date, therefore this period(the decadal median peak date ±48 d) is defined as annual spring bloom period. As sea surface temperature rises, earlier spring bloom peak timing but decreasing averaged Chl a biomass in the spring bloom period due to insufficient light is evident in the Okhotsk Sea from 2003 to 2012. For the rest of three study domains, there are no significant interannual variance trend of the peak timing and the averaged Chl a biomass. Furthermore this change of spring phytoplankton bloom timing and magnitude in the Okhotsk Sea challenges previous prediction that ocean warming would enhance algal productivity at high latitudes.  相似文献   

20.
Phytoplankton is a key component in the functioning of marine ecosystems, phytoplankton community structures are very sensitive to their environment. This study was conducted in the central Bohai Sea in the spring and early summer of 2015. Spatial variations in phytoplankton functional groups were examined through high-performance liquid chromatography pigment–CHEMTAX analysis. Results suggested that the phytoplankton biomass (chlorophyll a [Chl a]) in spring was mainly derived from the diatom community and was 3.5-fold higher than that in the summer. Meanwhile, the phytoplankton in the early summer sustained more diverse marker pigments than that in the spring. Despite the overwhelming predominance of microsized phytoplankton in the spring, some smaller phytoplankton (pico- or nanosized), including flagellates, such as prasinophytes, chlorophytes, and cryptophytes, highly contributed to the total Chl a in the summer. Various physico-chemical variables were recorded, and their correlations with phytoplankton density were established by redundancy analysis. Temperature, water stratification, nutrient availability, and even nutritive proportion influenced the succession of phytoplankton functional groups from diatom dominance in the spring to flagellate (mainly haptophytes and prasinophytes) dominance in the early summer. In conclusion, our work comprehensively evaluated the phytoplankton diversity and dynamics in the central Bohai Sea and suggests the need for long-term monitoring for further investigation.  相似文献   

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