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1.
《国际泥沙研究》2021,36(6):736-746
In order to optimize ship navigation in the macrotidal Gironde Estuary, a recent project funded by the port of Bordeaux aims at better understand and forecast hydrodynamic and fine sediment transport within the estuary. In the framework of this project, a two-dimensional hydro-sedimentary model is built. The model includes hydrodynamic forcings, mixed-sediment transport, and consolidation processes. The harmonic analysis of the astronomical tides reveals a strong distortion of the tidal wave inducing the growth of overtide constituents and the non-significant effect of tide-surge interactions in annual-scale prediction. Depending on hydrological conditions, river discharge can considerably alter the model accuracy due to the migration of the turbidity maximum zone modifying the bottom roughness. Comparison with measurements shows the ability of the model to reproduce suspended-sediment concentrations in the central Estuary. Sensitivity of the model to sediment features has also been discussed in regard of suspended-sediment concentrations and fluid mud deposits. The model will be further coupled with ship squat predictions and a morphodynamic model. 相似文献
2.
Alain C.M. Bourg 《Continental Shelf Research》1987,7(11-12)
A brief, critical review of empirical and conceptual metal adsorption models is presented. This covers models conditional to seawater chemistry, as well as models applicable to estuaries or other systems of variable solution chemistry. The conceptual surface complexation approach is used to show why desorption of trace metals does not necessarily occur readily in estuaries, and why in some cases adsorption can even take place. The relevance and weaknesses of this model for the understanding of the mobility and fate of heavy metals in turbid environments, as related to particle dynamics, is discussed using the macrotidal Gironde Estuary, France, as the example. 相似文献
3.
Emilie Strady Stéphane Kervella Gérard BlancSerge Robert Jean Yves StanisièreAlexandra Coynel Jörg Schäfer 《Continental Shelf Research》2011,31(9):997-1007
Sediments quality assessment is of priority concern to provide a comprehensible overview of ecological and chemical state of an ecosystem. The Marennes-Oléron Bay, hosting the largest oyster production in France, is influenced by the historic polymetallic pollution of the Gironde Estuary. Despite, management efforts and decreasing emissions in the Gironde watershed, Cd levels in oysters from the bay are close to consumption limit (5 μg g−1 dw, EC no. 466/2001). In this context, the aim of the study was to assess the priority metal (Ni, Cu, Zn, As, Ag, Cd, Hg, Pb and Th) concentrations in sediment within the Bay, by investigating spatial and temporal distribution variations and the role of hydrodynamic forcing. For that we selected three sites (east, west and south) characterizing different environments of the Bay and we observed metal concentrations, grain size distribution, bed elevation and wave activities during a year survey. The sampling strategy pointed out both spatial and temporal metal concentrations variability in sediment. In general, metal enrichments were close to geochemical background. The eastern part of the Bay, largely influenced by the Charente river particulate deposition, presented constant concentrations over the survey. In contrast, in the western part, bed elevation was strongly influenced by hydrodynamic forcing especially wave activities, and metal distribution showed constant metal concentrations except very located Cd minor enrichment related to the Gironde influence via the Antioche Strait (north). The southern part was disconnected from the rest of the Bay and showed minor to very located moderately severe Cd enrichment, related to the Gironde water discharges via the Maumusson Strait (south). Thus, the multi-disciplinary approach was relevant to characterize the interactions between hydrodynamic forcing on the environment and sediments and their metal quality state which (i) were close to geochemical background over a year for Ni, Cu, Zn, As, Ag, Hg and Pb (i) which presented enrichment of Cd in the western and southern part. 相似文献
4.
Dauvin JC 《Marine pollution bulletin》2008,57(1-5):22-40
Located to the far West of Western Europe, France has a western maritime coastal zone of more than 3800 km, which is widely influenced by the North-eastern Atlantic. The English Channel, an epi-continental shallow sea with very strong tides, runs along 650 km of the French coast and 1100 km of the English coast. It is also a bio-geographical crossroad encompassing a much wider range of ecological conditions than other European seas. France's Atlantic coast north of the Gironde estuary is a succession of rocky and sandy shorelines, including a sizeable intertidal zone, a wide continental shelf, and two major estuaries (Loire and Gironde). South of the Gironde, the 260 km of coastline is low, sandy and straight, with a narrowing continental shelf further on South due to the presence of the Cape Breton canyon in the bathyal and abyssal zones. Interface between the continental and oceanic systems, these bordering seas--North Sea, English Channel and Atlantic Ocean--have been the subject of many recent research programmes (the European Mast-FLUXMANCHE and INTERREG programmes; the national coastal environment programme and the LITEAU programme in France), designed to improve comprehension of the functions, production, and dynamics of these seas as well as their future evolution. Given the many conflicting practices in these littoral zones, integrated coastal zone management appears to be essential in order to cope with both natural phenomena, such as the infilling of estuarine zones, cliff erosion, and rising sea levels, and chronic anthropogenic pressures, such as new harbour installations (container dikes, marinas), sea aggregate extraction for human constructions, and offshore wind mill farms. This article provides as complete an overview as possible of the research projects on these bordering seas, both those that have recently been accomplished and those that are currently in progress, in order to highlight the main characteristics of these ecosystems and to underline the future challenges for European marine research in terms of the integrated coastal zone management of these highly significant coastal zones. 相似文献
5.
Polycyclic aromatic hydrocarbons in the sediments of the Yalujiang Estuary,North China 总被引：22，自引：0，他引：22
Selected polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Yalujiang Estuary, North China, have been investigated by gas chromatography-mass spectrometry (GC-MS) for flood season (August, 1994) and dry season (May, 1996), respectively. PAHs concentrations from sediments range from 68 to 1500 ngg(-1) depending upon the sample locations. The most contaminated sediment samples are found in the turbidity maximum area for both dry and flood seasons. The source of PAHs is most likely pyrolytic, with minor contributions from petrogenic and diagenetic PAHs for some samples. Perylene is mainly derived from biogenic inputs, and occurs at almost stations. In the Yalujiang Estuary, both biogenic and anthropogenic hydrocarbons are primarily derived form riverine discharges and are accumulated in the mixing zone. The overall levels of PAHs in this study are low compared to other regions and reveal moderate PAHs pollution in the Yalujiang Estuary. 相似文献
6.
Spatial variability of metals in the inter-tidal sediments of the Medway Estuary,Kent, UK 总被引：7，自引：0，他引：7
Spencer KL 《Marine pollution bulletin》2002,44(9):933-944
Concentrations of major and trace metals were determined in eight sediment cores collected from the inter-tidal zone of the Medway Estuary, Kent, UK. Metal associations and potential sources have been investigated using principal component analysis. These data provide the first detailed geochemical survey of recent sediments in the Medway Estuary. Metal concentrations in surface sediments lie in the mid to lower range for UK estuarine sediments indicating that the Medway receives low but appreciable contaminant inputs. Vertical metal distributions reveal variable redox zonation across the estuary and historically elevated anthropogenic inputs. Peak concentrations of Cu, Pb and Zn can be traced laterally across the estuary and their positions indicate periods of past erosion and/or non-deposition. However, low rates of sediment accumulation do not allow these sub surface maxima to be used as accurate geochemical marker horizons. The salt marshes and inter-tidal mud flats in the Medway Estuary are experiencing erosion, however the erosion of historically contaminated sediments is unlikely to re-release significant amounts of heavy metals to the estuarine system. 相似文献
7.
Grain size characteristics of surface sediment and its response to the dynamic sedimentary environment in Qiantang Estuary,China 总被引：2，自引：0，他引：2
The composition and grain size characteristics of sediment in estuarine and coastal environments provide important information on the material source, hydrodynamic environment, environmental events,etc. However, few studies have focused on the sediment characteristics of the entire Qiantang Estuary,particularly, on the correlation between hydrodynamics and sediment properties. Through systematic sampling of the surface sediment in a large area of the Qiantang Estuary, the spatial distribution ch... 相似文献
8.
9.
Nutrient Dynamics and Productivity in Three European Estuaries 总被引：3，自引：0，他引：3
The Scheldt, Gironde and Sado estuaries exhibit quite different characteristics regarding the annual river discharges, nutrient loads and oxygen conditions. Distribution patterns of nutrients, dissolved oxygen, suspended matter and chlorophyll a as well as the nutrient ratios and half saturation constants, allow the identification and comparison of specific processes. The Scheldt emerges as the most eutrophic estuary being, in general, not nutrient limited and functions as a source of phosphorus and nitrogen. Intense biogeochemical processes take place in this system. The Sado is shown to be a moderately productive system, the upper part being enriched in nutrients and chlorophyll a and showing a tendency for oxygen depletion in summer. Different factors seem to control phytoplankton production along the salinity gradient: light regime landwards and nitrogen seawards. By contrast, the Gironde does not show clearly the presence of sinks or sources regarding nutrients and exhibits a reduced productivity essentially controlled by turbidity. The high amounts of particles seem also to be responsible for localized processes such as phosphate sorption/desorption and silicate regeneration. 相似文献
10.
Wim van Leussen 《Ocean Dynamics》2011,61(2-3):387-401
Field measurements have been carried out to obtain more quantitative knowledge on the longitudinal distribution of the fine-grained sediment dynamics in the Ems Estuary. Both the short-term (time scale < tidal period) and the long-term (tidally averaged) fine-grained sediment transports have been investigated. It is shown that the short-term erosion/sedimentation cycles are most characteristic and are the building blocks for the ultimate long-term transports. Herein, the macroflocs play a key role. The macroflocs had sizes in the range of 200 to 700?μm, sometimes more than 1?mm, and survived high current velocities. The settling velocities were in the range of 0.5 to 8?mm/s. Turbulence intensities and suspended sediment concentration are of utmost importance for the settling properties of the sediment, but the “flocculation ability??of the suspended sediment is shown to be of equal importance. The suspended sediment concentration is only important at low levels of turbulence. At high levels of turbulence, the limiting properties of turbulence dominate. It is demonstrated that the surface properties of the suspended sediment particles are of prime importance for the flocculation ability of the water/sediment mixture, as do the sizes of the resuspended microflocs. Special attention is given to the longitudinal distribution of the sizes and settling properties of the macroflocs as well as of the sediment transports. The flocculation ability was shown to vary almost one order of magnitude along the estuary. These higher flocculation abilities in the direction of higher salinities are responsible for the increase of the sizes of the macroflocs in the seaward direction. Therefore, notwithstanding the low suspended sediment concentrations at the seaward boundary of the Ems Estuary, large macroflocs and corresponding high settling velocities were observed in this area. It explains that, in the Ems Estuary, no distinct effect was determined of the suspended sediment concentration on the settling properties of the suspended macroflocs. 相似文献
11.
The concentration of selected trace metals (Cu, Pb and Zn) in salt-marsh sediments from within the Erme Estuary have been measured in order to assess possible historical sources of pollution. The Erme Estuary, south Devon, UK is an Area of Outstanding Natural Beauty and has remained largely unaffected by industrialisation, although a number of small silver–lead mines were in operation in the 1800s. Five cores reveal comparable geochemical profiles. An increase of lead at 40 cm depth is observed, reaching maximum values of 427 ppm. Less distinct trends are revealed by zinc and copper, probably reflecting the lack of widespread mining for ores of these elements within the catchment and possible post-depositional mobility rendering the metal concentrations non-contemporaneous with the chemostratigraphy of lead. The geochemical analysis of the salt-marsh sediments provides a fairly robust chemostratigraphic scheme and the likely sources of mine waste can be pinpointed within the catchment. Based upon reference to the historical mining record of these mines chemostratigraphic dating of the sediments can be achieved in order to provide an estimate of salt-marsh accretion rates and sea-level rise. 相似文献
12.
The ecosystem model of the Bristol Channel and Severn Estuary (GEMBASE) was fitted to 3 years of survey data, and has subsequently been validated against a further 5 years of monitoring data. A control chart technique clearly demonstrates that the model is, on the whole, an adequate representation of the estuarine carbon cycle, although the precision of model estimates reduces with increasing trophic level. An ecosystem model of the Ems Estuary has been adapted to simulate the Severn Estuary, and the impact of introducing a notional tidal power scheme assessed. The results were compared to those obtained using GEMBASE in the Severn. The broad predictions from both models are in agreement, although some detail is at variance, which implies that the fundamental ecological assumptions of the models are compatible. 相似文献
13.
Estuaries are sinks for organic matter and nutrients entering both from their catchments and also from the adjacent lands and urban areas and in turn they are sources of such materials to the adjacent coast. The present paper quantifies the relative amounts of natural and anthropogenic organic matter and nutrients entering the Humber Estuary, Eastern England, including the allochthonous and autochthonous materials, those from urban and industrial sewage and from the catchment drainage of arable land. These data thus give a budget for the estuary which in turn answers questions fundamental to the management of the estuary. The estimations within the study have been carried out against a background of designating estuaries under the European Union Urban Waste-water Treatment Directive and the EU Nitrates Directive. The assessment has particularly addressed the question, related to the former Directive, of whether the Humber Estuary is eutrophic or likely to become eutrophic unless management measures are taken. Thus the paper indicates the nature and value of control measures such as treatment plant upgrading and the designation of Nitrate Vulnerable Zones. The paper includes the recent national and European discussions on the designation of areas under these Directives. Finally, the study has allowed a quantification of the present organic inputs to the estuary in comparison to those entering prior to large scale land-claim which had removed natural organic-producing wetlands. 相似文献
14.
Residue levels of HCHs,DDTs and PCBs in shellfish from coastal areas of east Xiamen Island and Minjiang Estuary,China 总被引：8，自引：0，他引：8
Shellfish samples were collected from the coastal cultivating areas of east Xiamen Island and Minjing Estuary, China and analyzed for hexachlorocyclohexanes (HCHs), DDTs and polychlorinated biphenyls (PCBs) by GC. Concentration ranges of HCHs, DDTs and PCBs in the coastal area of east Xiamen Island were 0.18–345, 75.2–2143 and ND-23 ng g−1 dry wt., respectively; those for Minjiang Estuary were ND-5.07, 21.5–2396 and ND-6.78 ng g−1 dry wt., respectively. The results showed that the organochlorines were evidently accumulated in marine bivalve molluscs, particularly in oyster. The concentrations of organocholorine pollutants in shellfish samples varied with the sampling locations, the season of collection and organism species, but were generally higher than those in the sediments. The concentrations of DDTs in the shellfish were high as compared with HCHs and PCBs, so that DDTs can be considered as the typical organochlorines in the survey areas. The residue levels and compositions of HCHs, DDTs and PCBs are discussed. 相似文献
15.
Macroinvertebrates and fish collected periodically from April 1973 to January 1976, from the Lower Medway Estuary, Kent, were analysed for a range of heavy metals, organochlorine pesticides and polychlorinated biphenyls. The heavy metal studies have been previously documented. Results of the chlorinated hydrocarbon analysis of mussels, shore crabs, periwinkles, ragworms, shrimps and selected fish tissues are presented and their significance discussed. 相似文献
16.
The use of a mathematical model, describing the transformations of organic and mineral compounds of C, Si, N, and P for the generalization of hydrological, hydrochemical, and hydrobiological data on nine regions in the White Sea is demonstrated. The regions examined include the head of Kandalaksha Gulf, Dvina Gulf, Mezen Gulf, Onega Bay, the Solovetskie Islands’ area, the central, deep-water part (or Basin), Gorlo, Voronka, and the Chupa Estuary. The results of modeling the transformations of biogenic substances in the water areas of the Chupa Estuary, and other gulfs and bays in the White Sea are compared and analyzed. Calculated variations in the concentrations of biogenic substances and detritus, microorganism biomasses, characteristics of their activity (specific growth rates and biomass turnover times) within a year are presented and discussed. The estimated characteristics are shown to agree with observational data. Particular attention is paid to estimating the organic matter production rates by phytoplankton and calculating balances of biogenic compounds in the Chupa Estuary. 相似文献
17.
Processes of interaction between river flow, tides, and storm surges in the Thames Estuary are discussed. The main regularities in water dynamics during tides and surges are revealed. Specific changed in characteristics of tides and surges along the estuary are established. Mention is made of the significant longterm increase in the ranges of tides and surges during the XX century. The history of floods caused by storm surges in the Thames Estuary and in the area of London is described. Hydraulic engineering measures for flood control in the area of London are discussed. 相似文献
18.
High-resolution hydrodynamic models are a common tool to simulate water dynamics in estuaries. Results from these models are, however, difficult to interpret without the aid of additional parameters to integrate the information. In this paper a methodology to understand the transport patterns in the Tagus Estuary is proposed. It is based on the computation of two renewal time scales: residence time and integrated water fraction. This last parameter is used to build a dependency matrix that gives the integrated influence of each region of the estuary at a selected point. The parameters are computed using a Lagrangian transport model coupled to the hydrodynamic model. Results show that Tagus Estuary has two different types of regions: the central part of the estuary, with low renewal efficiency, and three regions with higher renewal efficiency. Renewal mechanisms are, however, different for each region as shown by the dependency matrix. Comparison of renewal time scales with results from a water-quality model revealed that residence time is not a limiting parameter for primary production in the Tagus Estuary.Responsible Editor: Hans Burchard 相似文献
19.
《水文科学杂志》2013,58(4):702-712
Abstract The “sudestadas” are short-term hydro-meteorological phenomena that produce a “hydraulic plug”, preventing the normal drainage of the water courses in the Río de la Plata Estuary. The purpose of this study was to analyse the influence of the sudestadas on the water quality of the Lower River Luján, which discharges into the Río de la Plata Estuary (59°37′W; 34°43′S). Samplings were conducted from November 1998 to July 2001 at six sites on the lower stretch of river. Physical and chemical variables were measured and a nonparametric test was applied to each variable, grouping samples affected and non-affected by sudestadas, which further diminish the water quality of the river. The frequency and intensity of sudestadas are predicted to increase as a consequence of the Earth's warming; thus, this research suggests that the environmental risk produced by the effects of global change, will be greater. 相似文献
20.
Sequential extraction of Hg was performed in a core collected from intertidal area in Ulhas Estuary in order to characterize the downward distribution and diagenetic behavior of Hg in a polluted estuary. Concentration of total Hg ranged between 0.46 and 6.40 μg g−1 with significant decrease in surficial sediment as a result of closing of two Hg-cell based chlor-alkali plants. Results of sequential extraction showed that >65% Hg was strongly bound to organo-sulphur and inorganic sulphide species that are not bioavailable. Flux of only 18.8% of Hg was found compared to its value deposited on sediment–water interface. Hence, it is concluded that there is no significant diagenetic remobilization of Hg in Ulhas Estuary. This core also has been analyzed for 210Pb geochronology. The estimated sedimentation rate is 0.31 cm y−1 in the present sampling region. 相似文献