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1.
The report considers the distribution of the salinity, the particulate matter, and the dissolved and particulate forms of iron in the Amur Liman and Sakhalin Gulf under different volumes of the riverine runoff during the summer periods. It was shown that the influence of the runoff variations is pronounced in the composition of the surface layer of the estuarine and coastal waters but smoothed within the bounds of the Sakhalin Gulf. The dissolved iron is additionally exposed to the smoothing effect of the coagulation processes under the mixing of the riverine and marine waters. The calculation of the iron utilization by the plankton points to the key role of the production processes in the Sakhalin Gulf for the further migration of iron over the Sea of Okhotsk.  相似文献   

2.
The variability of the phosphates, silicates, alkalinity, oxygen, CO2 pressure, salinity, and temperature in the surface mixed layer (SML), as well as the variations of its thickness along the drift passage of the North Pole 35 station, are considered. The station drifted over the Nansen Basin mainly eastwards from ??105 to ??30° E. The surveys were performed from October of 2007 till June of 2008 at three-day intervals. The SML parameters are mainly determined by the advection and mixing with the underlying waters. The analysis of the hydrochemical variability shows that the surface waters at the eastern and western areas of the drift are of different origins. The waters of the eastern area were subjected to the impact of riverine runoff. These waters were spread westwards. The fraction of riverine waters in the eastern area amounts to 3%. In the western area of the drift, presumably transformed Atlantic waters were observed, which spread eastwards from the Fram Strait. The drift path of the station crosses the boundary of the water masses near 85° N and 45° E.  相似文献   

3.
The paper considers tidal effects on the formation of the hydrological and hydrochemical characteristics of the mouth of the Northern Dvina River in the presence of ice cover were considered. The results of natural surveys at the river delta and near-mouth area in March 2014 were analyzed. No surveys as such were performed in winter formerly. It was found that short-term variations of flow rates during the winter low-water time might be traced at 85–95 km from the seaward border of the delta. The tidal effects upon the short-term variability of hydrochemical parameters appeared at 70 km from the delta seaward border. The tidal variations of all the considered parameters were most intense in the mixing zone of riverine and marine waters at the delta.  相似文献   

4.
Pore Water Nutrient Regeneration in Shallow Coastal Bohai Sea, China   总被引：1，自引：0，他引：1  
The regeneration of pore water nutrients was studied and the contribution of benthic nutrient fluxes to the overlying water was evaluated on the basis of field specific observations conducted in September–October 1998 and April–May 1999 in the Bohai Sea. Nutrient concentrations in sediment pore waters were examined by incubating sediment core samples with overlying seawater in air and/or nitrogen conditions. Nutrient diffusion fluxes calculated by diagenetic equations were within a factor of 2 during incubations. The factors affecting nutrient diffusion across sediment/water interface include bioturbation, nitrification, denitrification, adsorption, and dissolution. The regeneration of nutrients from sediments will increase nutrient loads of the Bohai Sea and affect nutrient atomic ratios in this region. Among nutrient sources from riverine input, atmospheric deposition and sediment regeneration, ammonium and phosphate mainly came from atmospheric deposition (>50%); nitrate was mainly transported by riverine input into the Sea, silicate from sediment regeneration accounts up to 60%. This demonstrates that nutrient regeneration in sediments contributes more silicate than riverine input and atmospheric deposition together, but benthic flux contributes very much less phosphate and nitrate relative to riverine input and atmospheric deposition. The benthic fluxes of nutrients may lead to a decrease of the amount of nitrate, an increase of phosphate, ammonia and silicate in the water column. The release of silicate from sediments may compensate the decrease of silicate due to the reduction of riverine discharge. Nutrient regeneration in sediment may have an important influence on the eutrophic character of coastal waters in this region. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

5.
Four cruises were conducted during 2002--2003 in the Changjiang Estuary and adjacent coastal areas. The data presented show a clear coast to open sea gradient in nutrients related to the river inputs. Maximum values of chlorophyll a were typically observed at intermediate salinities at surface water and coincided with non-conservative decreases in nutrients along the salinity gradient, indicating that removal of nutrients was related to phytoplankton uptake. The seasonal variations of nutrient concentrations were just opposite to those of chlorophyll a, indicating that the seasonal variations of nutrients were mainly controlled by phytoplankton uptake, whereas riverine inputs merely weakened or balanced its extent. During the estuarine mixing, phosphate demonstrated some remobilization during all the four cruises; whereas both conservative and non-conservative behaviors for dissolved inorganic nitrogen and silicate were observed in the study area, indicating that both biotic and abiotic events may affect their behaviors during the estuarine mixing. Under the influence of freshwater inputs with high value of ratio of nitrogen to phosphorus, the estuarine and coastal waters impacted by the Changjiang plume were high （ 〉 30） in ratio of nitrogen to phosphorus, but rates of primary production were apparently not constrained by any kind of nutrient elements. However, the low （ 〈 1 ） ratio of silicate to nitrogen in most of the study area might be linked with the rapidly increasing frequency of harmful algal bloom （HAB） incidents in recent years in the coastal waters impacted by the Changjiang plume.  相似文献   

6.
The publication presents the results of the studies on the carbonate system of the waters of the East Siberian Sea performed aboard R/V Ivan Kireev in September 2003–2004. It is shown that the aquatic area considered may be subdivided into two biohydrochemical provinces. The western part of the sea is a CO2 supplier to the atmosphere, while its eastern part is a sink for CO2. This is caused by the fact that the western part of the East Siberian Sea was affected by the waters of the southeastern part of the Laptev Sea, which were desalinated by riverine runoff, turbid, and enriched in the bioactive organic matter supplied into the water due to the coastal (and bottom) erosion. In the eastern part, cold waters of Pacific origin prevailed (saline, transparent, and productive), which caused a pronounced decrease in the partial pressure of CO2(pCO2) in the surface layer. In the frontal zone delimiting the desalinated shelf waters and those of the Pacific origin, the direction of the CO2 flux between the atmosphere and the sea changed (from evasion to invasion). The interannual variability of the carbonate system parameters in the coastal-shelf zone of the East Siberian Sea was determined by the intensity of the propagation of the waters of different origins over the sea aquatic area caused by the atmospheric circulation, as well as by the riverine runoff intensity and the dynamics of erosion processes.  相似文献   

7.
The grain-size and mineral composition of the suspended particulate matter (SPM) of the Severnaya Dvina River mouth is studied, as well as the content of several lithogenic elements in the SPM during the spring flood in May 2004. The data published on the composition of the riverine SPM in the White Sea basin are very poor. The spring flood period when more than half of the annual runoff is supplied from the river to the sea in a short time is understood more poorly. The report considers the comparison results for the grain-size compositions of the SPM and the bottom sediments. The data of laser and hydraulic techniques of the grain-size analysis are compared. The short-period variations of the SPM concentration and composition representing two diurnal peaks of the tide level are studied. It is found that the SPM is mainly transferred during the spring flood as mineral aggregates up to 40 μm diameter. The sandysilty fraction of the riverine SPM settles in the delta branches and channels, and the bulk of the fine pelitic matter is supplied to the sea. The mineral and chemical composition of the Severnaya Dvina River SPM is determined by the supply of substances from the drainage basin. This substance is subjected to intense mechanic separation during the transfer to the sea. The key regularities of the formation of the mineral composition of the SPM during the flood time are revealed. The effect of the grain-size composition of the SPM on the distribution of the minerals and elements studied in the dynamic system of the river mouth are characterized.  相似文献   

8.
根据2013年8月(夏季)和2014年5月(春季)在曹妃甸邻近海域的调查资料,研究了浮游动物群落的种类组成、丰度、生物量、优势种和多样性的时空变化特征,分析了其与环境因子的关系,并结合2004年调查资料对比分析了浮游动物丰度和优势种的变化特征及围填海的影响。结果表明,研究海域浮游动物共鉴定得到31种(类),以桡足类和浮游幼体为主,优势种主要包括双刺纺锤水蚤(Acartia bifilosa)、小拟哲水蚤(Paracalanus parvus)、拟长腹剑水蚤(Oithona similis)和桡足类幼体(Copepodid larva)等。春季的浮游动物丰度和生物量均高于夏季,多样性和均匀度指数均低于夏季。浮游动物丰度的空间分布主要受温度、叶绿素a(Chl-a)等环境因子影响,春季基本为近岸高、远岸低的空间分布规律,夏季则相反,基本为近岸低、远岸高的空间分布规律。与2004年相比,本次调查春季和夏季的浮游动物丰度明显下降,可能与浮游植物丰度及DIP浓度降低有关。春季,西侧、东侧海域的浮游动物丰度分别明显降低、升高,与围填海后营养盐重新分布促进了东侧海域浮游植物增殖有关。夏季则主要受河流输入影响,浮游动物丰度的变化不具有空间差异。  相似文献   

9.
The Po River runoff strongly affects the oceanographic and ecological characteristics of the Northern Adriatic Sea. Catalysed reported deposition ‐ fluorescence in situ hybridization (CARD‐FISH) analysis was employed to assess how the composition of the coastal bacterioplankton community is influenced by the river runoff in two different seasons (spring and autumn). Samples were collected from the water column along a coastal–offshore transect in the Northern Adriatic Sea at different depths. Four clone libraries were then constructed from coastal (0 m) and offshore waters (?65 m). Higher abundances of bacteria were recorded in coastal waters as compared with the offshore samples. This result was mainly due to the trophic state of the water column, and it was related to salinity. Particularly, Actinobacteria and Gammaproteobacteria were affected by the riverine inputs, whereas Bacteroidetes and Alphaproteobacteria showed only minor responses. This was particularly clear in the autumn sample, in which a clear difference between the coastal and the offshore samples was found due to a strong influence of the less saline river water with high nutrient concentrations. Analysis of 205 partial length 16S rRNA gene sequences indicated a high diversity with the dominance of Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria mainly affiliated to coastal and marine bacterioplankton clades. Actinobacteria were also detected and, together with Gammaproteobacteria, strongly follow the freshwater intrusion. Overall, our results indicate that the seasonal difference in the Po River discharge greatly affects the bacterioplankton community. In spring we observed a smooth transition from coastal to open‐sea conditions owing to the more superficial freshwater plume. In autumn the deeper freshwater intrusion in the coastal site and thermal stratification offshore resulted in a marked difference between the coastal and offshore microbial communities.  相似文献   

10.
河口只是河流与海洋之间的一小部分水域,但对人类社会的发展和生物的进化起着重要的作用。它不仅是生物种群繁殖、育幼和栖息的场所,而且是溯河和降海鱼类洄游的必经之路,因此,河口对生物种群的繁衍延续和资源补充,以及保持生态平衡具有十分重要的意义。 然而,河口又是生态环境十分脆弱和敏感的水域,同时也是受人类干扰最为严重的区域。因此,河口的生态环境问题愈来愈引起人们的关注,其中包括长江三峡水库的兴建对长江口及其附近海域生态、环境的影响,特别是对位于河口两侧的我国著名两大渔场——舟山渔场和吕四渔场的影响问题。影响渔业资源的因子是多方面而且错综复杂的。本文主要通过长江径流的变化与环境因子变量的相关分析,并根据三峡水库不同蓄水方案,对河口近海渔业的影响问题进行初步探讨。  相似文献   

11.
A procedure for separating the colloid component of natural waters is proposed. It was shown that this component is the main form of matter transfer in Ob River runoff, because the mass of colloid substance is two orders of magnitude higher than that of particulate matter in the outer part of the estuary. Simulation and field experiments revealed the influence of nature and concentration of organic matter on their ability to stabilize or flocculate clay particles with an increase in salinity, thus affecting the range of transfer of riverine runoff matter. It was shown that the interaction of humic acids and clay particles, as well as the increase in hydrophobic properties of a flocculant, improve flocculation efficiency. Criteria are proposed to recognize in the estuarine region areas of pronounced contribution of flocculation processes to sedimentation of fine particles. It is shown that the newly formed organic matter produced by biota under saline stress might be flocculants of fine particulate matter.  相似文献   

12.
Coastal ecosystem processes are largely influenced by the interaction of different factors operating at various temporal and spatial scales, specifically those responsible for primary production patterns that modulate zooplankton and subsequent trophic levels. Hydrological processes, such as tidal cycles and coastal currents, nutrients availability, phytoplankton groups (studied through algal pigment signatures analysed by HPLC), and zooplankton abundance and distribution were investigated at the Sofala Bank (Mozambique), with special emphasis on their horizontal distribution and vertical dynamics (48 h). Horizontal distribution has shown inshore–offshore gradients in all analysed parameters, as well as inshore waters intrusion probably related to Zambezi River delta runoff. Tidal currents were responsible for major hydrological vertical variations and for horizontal and vertical advection of phytoplankton biomass in the surface and deepest layers, respectively. Nutrient concentrations were typical from oligotrophic regions, and nutrient ratios were strongly influenced by depleted nitrate + nitrite concentrations, indicating low estuarine discharges typical from the dry season. The very low N:P ratio obtained suggests strong nitrogen limitation to phytoplankton communities, supporting the low phytoplankton abundance observed. Both phytoplankton pigments and zooplankton were found mainly near the bottom (40 m depth), despite the latter displayed vertical migrations triggered by light variations. Phytoplankton community was dominated by microflagellates, specifically prymnesiophyceans, and behaved as a whole, except Cyanobacteria that displayed vertical distribution movements different from other phytoplankton groups, being mainly concentrated at mid-water column depths (10–20 m). This investigation enhances physico-chemical phenomena and their importance determining the planktonic communities vertical dynamics at Sofala Bank, a tropical coastal ecosystem of the Western Indian Ocean where planktonic dynamics are still poorly described and understood.  相似文献   

13.
Characteristics of different types of river drainage were obtained during studies of a polygon in the near-mouth part of the Volga River in 2000–2003: “fast” (flowing through deep channels) and “slow” (that which passes through the littoral parts of the delta (1–2 m)). The low current velocities (lower than in the channel waters by a factor of ten), the abundance of water vegetation, and the strong heating of the waters lead to the high intensity of the biochemical processes. Therefore, the chemical composition of the waters is subjected to significant transformation with intensity so high that it allows comparing these regions with some sort of “bioreactor.” These changes influence the dissolved oxygen and various forms of carbon content.  相似文献   

14.
We conducted studies of nutrients and water mass movements in a semi-enclosed bay in northern China to understand nutrient dynamics under varying tidal regimes. Four cruises were conducted under varying tidal regimes in Jiaozhou Bay, two at neap tide and one at spring tide in August and one at spring tide in October 2001. In addition to transect surveys, drift experiments and an anchor station were employed to show current and tidal effects. Samples for nutrient evaluation were taken from the five major tributary rivers in March (dry season) and August (flood season) of 2002 to estimate nutrient transport by rivers, and wastewater samples were collected to evaluate nutrients in wastewater discharge. Benthic nutrient fluxes were determined by (1) incubation of sediments with overlying seawater on board the boat and (2) calculated by Fick’s First Law from nutrient pore water profiles. Nutrient concentrations were high in the north, especially the northeast and northwest sectors, reflecting human activities. Jiaozhou Bay was characterized by high nitrogen, but low phosphorus and silica concentrations compared to Chinese coastal seas. Based on nutrient atomic ratios, the limiting elements for phytoplankton growth in Jiaozhou Bay were silica and phosphorus. The fluxes of nutrients between sediment and overlying water varied depending on the specific nutrient, the site and redox conditions. Benthic nutrient fluxes based on sediment incubations were all lower than the estimated diffusive fluxes, implying that the nutrients released from sediment pore waters were probably utilized by benthic microalgal and bottom-water primary production. A preliminary estimate of nutrient budgets demonstrated that riverine and wastewater inputs were greater than atmospheric deposition into Jiaozhou Bay, except that nitrate from wastewater inputs was less than atmospheric deposition. Concentrations of nitrogen and phosphorus increased while silica decreased in the last four decades, similar to other eutrophicated estuaries. The resulting shift in nutrient composition in Jiaozhou Bay affects phytoplankton composition, trophic interactions, and sustainability of living resources.  相似文献   

15.
Floating objects facilitate the dispersal of marine and terrestrial species but also represent a major environmental hazard in the case of anthropogenic plastic litter. They can be found throughout the world's oceans but information on their abundance and the spatio-temporal dynamics is scarce for many regions of the world. This information, however, is essential to evaluate the ecological role of floating objects. Herein, we report the results from a ship-based visual survey on the abundance and composition of flotsam in the German Bight (North Sea) during the years 2006 to 2008. The aim of this study was to identify potential sources of floating objects and to relate spatio-temporal density variations to environmental conditions. Three major flotsam categories were identified: buoyant seaweed (mainly fucoid brown algae), natural wood and anthropogenic debris. Densities of these floating objects in the German Bight were similar to those reported from other coastal regions of the world. Temporal variations in flotsam densities are probably the result of seasonal growth cycles of seaweeds and fluctuating river runoff (wood). Higher abundances were often found in areas where coastal fronts and eddies develop during calm weather conditions. Accordingly, flotsam densities were often higher in the inner German Bight than in areas farther offshore. Import of floating objects and retention times in the German Bight are influenced by wind force and direction. Our results indicate that a substantial amount of floating objects is of coastal origin or introduced into the German Bight from western source areas such as the British Channel. Rapid transport of floating objects through the German Bight is driven by strong westerly winds and likely facilitates dispersal of associated organisms and gene flow among distant populations.  相似文献   

16.
Dynamics of Turbidity in the Tweed Estuary   总被引：1，自引：0，他引：1  
Results are presented of turbidity measurements made in the Tweed Estuary during 14–29 September 1993. The observations covered a spring-neap period of very strong and relatively weak tides, which included strong wave activity at the mouth of the estuary, the aftermath of a strong freshwater inflow event and a minor inflow event which coincided with neap tides. Turbidity levels between the mouth and the limit of saline intrusion during this period were observed to lie in the range 2–30 ppm. Temperature–salinity relationships, based on rapid sampling throughout the estuary, often indicated conservative mixing between riverine and coastal waters. Turbidity–salinity relationships throughout the estuary were approximately linear for most of the lower salinity range (<30) although the relationships varied throughout a tidal cycle. At the highest salinities, in the lower 2·5 km of estuary, significantly enhanced turbidities occurred during strong, onshore swell-wave conditions. Near-mouth turbidities were very low (<5 ppm) at high-water (HW) when the swell-wave height was small (<0·3 m). There was no correlation between near-mouth turbidity at HW and tidal range, whereas the correlation between near-mouth turbidity and swell-wave height explained over 90% of the variance in near-mouth turbidity. The temporal trends in freshwater turbidity and freshwater inflow during the fieldwork period were fairly similar. A statistically significant relationship existed between these variables when freshwater turbidity was correlated against inflow 30 h earlier. A ‘ model ’ of turbidity, based on 5 days of inflows and used to hindcast turbidity from 14 days of inflows between 16–29 September, explained over 80% of the variance in freshwater turbidity. Therefore, inflow exerted a significant control on the fluvial turbidity. It appears that very fine-grained particles were responsible for the observed turbidity in the central and upper reaches of the Tweed. During the flood, in the presence of strong wave activity in the coastal zone, larger sediment was rapidly winnowed in the lower reaches, close to the mouth, whereas fine silt particles remained in suspension and reached the limit of saline intrusion.  相似文献   

17.
长江河口生态系统鱼类浮游生物生态学研究进展   总被引：12，自引：0，他引：12  
鱼类浮游生物群落结构的时空分布和动态变化与其所处水域的环境因子有密切的关系，它的变动受环境因子的变化和时空异质性的制约，而其鱼类浮游生物群落结构的变动最具代表性。研究证明，鱼类浮游生物群落结构对鱼类资源的补充，延续和维持生态平衡具有重要的意义，但尚无系统报道。本文就长江口鱼类浮游生物群落的研究做了阐述。三峡工程建设之后，通过改变长江径流来改变长江口水域的温度、盐度及其他非生物因子，同时由于非生物因子的变化，也引起生物因子的改变，从而使鱼类浮游生物优势种的组成和群落结构的生态性质发生了一定的变化，可以影响到长江口鱼类资源的补充，进一步改变长江口水域生态系统的平衡。  相似文献   

18.
用等离子体原子发射光谱法（ICP-AES）分析了珠江马口站和三水站1997-1998年度3个典型水文时段径流悬移质中部分金属元素的含量，同时用元素分析仪测定了其中的有机碳、氮的含量，结果表明，在不同性质的水文动力条件下，流域侵蚀产出的河流悬移质的化学组成发生了变化，这主要缘于有机质在悬移质中所占质量分数的差别。汛期增强的水文动力主要表现为对流域土壤矿物的优先侵蚀，虽然有机质的总侵蚀量也同时增加，但在悬移质中的质量分数却相对减少，而在枯水期较弱的水文动力条件下，河流悬移质中有机质的质量分数增加，悬移质中的有机质对液相中的部分重金属元素产生较矿物更大的吸附作用。  相似文献   

19.
为研究黄河入海径流变化条件下河口附近海域盐度扩散特征,以更好地保护河口海域生物资源多样性,本文以黄河下游利津水文站的长序列实测径流数据资料为基础,利用近海水动力模型FVCOM,分析径流变化对黄河口海域盐度的影响规律。结果表明：黄河口与莱州湾之间存在顺时针的环流系统,在余流作用以及涨落潮方向的影响下,黄河冲淡水长期向莱州湾扩散;丰水期黄河冲淡水几乎影响了整个莱州湾,27盐度锋可以到达莱州湾中部,27等盐线的表层包络面积为2 665.61 km2,占莱州湾的1/4左右,枯水期低盐度水只有向南扩散的趋势,27以下的低盐度水集中分布在黄河口门附近,27等盐线的表层包络面积只有199.65 km2;5月份,随着入海径流量增加,27等盐线扩散的范围、距离、方向都会发生明显变化。在对近海生物资源有迫切保护需求的情景下,适当减少其他用水户供水量以增加入海生态径流量,可以有效改善黄河口海域附近的盐度情况,为生物资源的生长繁殖创造良好条件。  相似文献   

20.
It is believed that the ecological balance and productivity of marine coastal environments are directly related to nutrient supplies from various sources including riverine-estuarine-coastal exchange, upwelling, precipitation, nitrogen fixation, and nutrient regeneration. In south Texas coastal waters, where phytoplankton productivity is comparable to other high productive coastal areas, many nutrient sources are suspected, but are not equally important in supplying sufficient nutrients to drive coastal production dynamics. Nitrogen regeneration from the benthos is implicated from a 2.5-y study of the nutrient cycling processes important in contributing to production levels in these waters. Sediments of the south Texas coastal habitat appear to exhibit a sensitive coupling with overlying waters, where a strong negative correlation exists between the random periodicity of external supplies of ‘new’ nitrogen to the coastal system and the rate at which nitrogen is recycled by sediments. This pattern buffers these waters against extended periods of low input of nutrients from external sources. The development of a conceptual scheme for nutrient cycling in this coastal habitat has provided a more holistic framework from which we can derive an objective assessment of the importance of mechanisms in the system. All data collected so far suggest that the primary production of organic matter and passage through the benthic habitat of these coastal waters is an important pattern responsible for the continued maintenance of productivity in the south Texas coastal ecosystem.  相似文献   

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