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Impact of climate change on Gironde Estuary  

Science.gov (United States)

Within the THESEUS European project, a simplified mathematical model for storm surge levels in the Bay of Biscay was adjusted on 10 events at Le Verdon using wind and pressure fields from CLM/SGA, so that the water levels at Le Verdon have the same statistic quantiles as observed tide records for the period [1960-2000]. The analysis of future storm surge levels shows a decrease in their quantiles at Le Verdon, whereas there is an increase of the quantiles of total water levels. This increase is smaller than the sea level rise and gets even smaller as one enters farther upstream in the estuary. A numerical model of the Gironde Estuary was then used to evaluate future water levels at 6 locations of the estuary from Le Verdon to Bordeaux and to assess the changes in the quantiles of water levels during the XXIst century using ONERC's pessimistic scenario for sea level rise (60 cm). The model was fed by several data sources : wind fields at Royan and Mérignac interpolated from the grid of the European Climatolologic Model CLM/SGA, a tide signal at Le Verdon, the discharges of Garonne (at La Réole), the Dordogne (at Pessac) and Isle (at Libourne). A series of flood maps for different return periods between 2 and 100 years and for four time periods ([1960-1999], [2010-2039], [2040-2069] and [2070-2099]) have been built for the region of Bordeaux. Quantiles of water levels in the floodplain have also been calculated. The impact of climate change on the evolution of flooded areas in the Gironde Estuary and on quantiles of water levels in the floodplain mainly depends on the sea level rise. Areas which are not currently flooded for low return periods will be inundated in 2100. The influence of river discharges and dike breaching should also be taken into account for more accurate results.

Laborie, Vanessya; Hissel, François; Sergent, Philippe

2014-05-01

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PCB contamination in fish community from the Gironde Estuary (France): blast from the past.  

Science.gov (United States)

The contamination of the Gironde Estuary, southwest of France, by polychlorinated biphenyls (PCBs) was assessed using six fish of high ecological and economic importance as bioindicator species. The concentrations of 21 PCB congeners and total fat contents were determined in the muscle and liver of eels (Anguilla anguilla), seabass (Dicentrarchus labrax), flounders (Platichthys flesus), meagres (Argyrosomus regius), mullets (Liza ramada), and soles (Solea vulgaris). In addition, information regarding the trophic ecology of the studied fish was obtained through the analysis of carbon and nitrogen stable isotopes (i.e., ?(13)C and ?(15)N) in muscle. Results revealed high PCB concentrations in fish compared to monitored European estuaries. The muscle of eels was by far the most contaminated fish flesh (?7PCBs=1000±440 ng g(-1) on a dry weight basis), while the higher PCB concentrations in liver were measured in flounder (?7PCBs=2040±1160 ng g(-1) d.w.). A quantile regression approach allowed to investigate the fate of PCBs in the Gironde estuarine fish assemblage, and revealed a general process of trophic magnification. Finally, most of the analysed fish presented PCB concentrations in muscle meat above the current European maximum limits for sea products, while the derived "Toxic Equivalent Quantity" (TEQ) revealed human health concerns only for high-fat fish consumption. PMID:24238912

Bodin, N; Tapie, N; Le Ménach, K; Chassot, E; Elie, P; Rochard, E; Budzinski, H

2014-03-01

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Numerical-simulation of the turbidity maximum transport in the gironde estuary (france)  

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A coupled two-dimensional vertical width-integrated hydrodynamic and sediment transport numerical model is presented to simulate the ''turbidity maximum'' formation and dynamics in the Gironde estuary. A turbulence closure sub-model is used to parametrize the turbulent mixing process. The numerical results of a five-day simulation are compared with field measurements carried out at several locations. The formation and the displacement of the turbidity maximum during one tidal cycle are correc...

Li, Zh; Nguyen, Kd; Bruncottan, Jc; Martin, Jm

1994-01-01

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Shelf mud fields formation within historical times: examples from offshore the Gironde estuary, France  

Science.gov (United States)

The Gironde shelf mud fields are distinctive morpho-sedimentary units that overlap the sands and gravels covering the North Aquitaine continental shelf (France). The muddy deposits are located offshore of the two main channels of the Gironde mouth, the West-Gironde mud patch (WGMP) and South-Gironde mud patch (SGMP). Fine-grained sediments originate in the Gironde, especially during river floods, and a smaller part of silty and shelly fine sand has its origin in the sandy covering of the inner shelf, during periods of high-energy (i.e. storms). The stratigraphy of these muddy deposits has been revised, using 14C dates and palynological analyses from cores. The results do not agree with previous estimates, of 10,000 or 7000 BP, for the age of the deposits. The deposition of the Aquitaine shelf mud fields is not linked to the postglacial transgression. The substrate has formed between 2000 and 5000 BP. Some shells from the lower part of the muddy sediments have been dated at 1000 or 1100 BP (SGMP) and 500-600 BP (WGMP). Pollen analyses confirm they formed after 2000 BP. The oldest muds were deposited in the Subatlantic period, and evidence of human activities (such as clearance and agriculture) are conspicuous. Some palynological markers provide evidence of Roman colonization at about 2000 BP. Causes of deferred settling of the muds have been sought through variations in the rate of escape of Gironde suspended matter. This depends on the infilling and the morphological changes within the estuary since the post-Holocene stillstand and the increase of sediment supply resulting from soil erosion within the catchment area. The latest link to climatic fluctuations, and intensive human activities that have occurred during the last thousand years, are suspected to have been influential. However, the various events were concomitant and are difficult to separate. Comparison between cores suggests that at first there was a concentration of sedimentation at the site of the SGMP and in the inner zone of the WGMP. However, later, recent fine-grained sedimentation was concentrated on the outer zone of the WGMP, as testified by the preponderance of pollen that records the afforestation of Les Landes (mid-19th century). The sedimentation rates are variable and range between 1 and 4 mm y -1.

Lesueur, P.; Tastet, J. P.; Marambat, L.

1996-12-01

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A preliminary investigation of the fish food web in the Gironde estuary, France, using dietary and stable isotope analyses  

Science.gov (United States)

Carbon and Nitrogen stable isotopes and stomach contents analyses were used to investigate an estuarine fish food web and identify the contribution of these two methods to the knowledge and understanding of the food web's structure and its functioning. The nine most abundant fish species during the warm period in the Gironde estuary (southwest France, Europe) are examined. Observation of the stomach contents reflects a variety of feeding modes between fish species that consume a diverse assortment of prey, with limited dietary overlap. Nevertheless, when regarding the whole fish community, few prey species dominate the stomach contents. Nitrogen isotope ratios indicate a high intraspecific variability inducing an interspecific covering of the signatures. However, a tendency to ? 15N enrichment according to the trophic position of the species studied was observed. Fish assemblages show a trend towards enrichment of their carbon isotopic signatures from the upper estuary (-20.8 ± 1.8‰) towards the lower estuary (-18.3 ± 1.6‰). But whatever the capture zone considered, most of the individual ? 13C values for each fish analysed are comprised between -22 and -16‰. Only few specimens, belonging to migratory amphihaline species, have significantly lighter values. The stomach contents method of analysis has the advantage of giving an initial view of the ichthyological trophic structure of the system by describing the food relations between a fish species and its prey. From these results, hypotheses can be drawn about the network's functioning, suggesting a sharing of resources between species and a "wasp-waist" control of this estuarine food web. The stable isotope analysis method enables us to improve our structural knowledge by positioning the different species in a food web, with their position being determined by the number of energy transfers (analysis of ? 15N). Conversely, in environments as complex and changing as estuaries, it appears difficult to precisely identify and quantify the sources of the organic matter at the base of the fish estuarine food webs using analysis of ? 13C isotopic signatures. Nevertheless, the results obtained by using these two methods in parallel suggest that more detailed functional ecological studies could be carried out in future.

Pasquaud, S.; Elie, P.; Jeantet, C.; Billy, I.; Martinez, P.; Girardin, M.

2008-06-01

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Carbon isotopic ratio of suspended organic matter of the Gironde estuary. Application to particulate Zn and Pb distribution  

International Nuclear Information System (INIS)

In the Gironde estuary, the isotopic ratio of particulate organic carbon (P.O.C.), and the ratio metal/P.O.C. indicate the occurrence of two zones. Up-river, the concentration decreases due to the consumption of the organo-metallic phase and by mixing in the ''mud plug'' with terrestrial particles impoverished in metal and P.O.C. Down-stream, the mixing of metal rich terrestrial P.O.C. with poorer marine particles determines the metal concentrations

1981-10-12

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Effet de la turbidité sur la dégradation des pigments phytoplanctoniques dans l'estuaire de la GirondeEffect of turbidity on phytoplanktonic pigments degradation in the Gironde Estuary  

Science.gov (United States)

In the Gironde Estuary, most part of phytoplanktonic material carried by the rivers is mineralised in the maximum turbidity zone (MTZ). In order to follow the degradation of the phytoplanktonic material into the MTZ, we developed an in vitro approach based on the monitoring of phytoplanktonic pigments. Algal material from two chlorophytes ( Scenedesmus suspicatus Chaudat and Chlamydomonas sp.) was incubated in the dark during 28 days into water samples from the Gironde estuary MTZ, at variable suspended solid concentrations (SPM) as well as in a sterilised turbid sample. First order decay constants of chlorophylls a and b and lutein increased by a factor 3 to 5 between SPM of 0 and 3 g l-1. The production of pheophytin a in the presence of particles and the lack of degradation in the sterilised turbid sample confirmed the effect of attached bacteria on the particles. To cite this article: E. Lemaire et al., C. R. Geoscience 334 (2002) 251-258.

Lemaire, Emmanuelle; Abril, Gwenaël; De Wit, Rutger; Etcheber, Henri

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Behaviour of arsenic on the continental shelf off the Gironde estuary: role of phytoplankton in vertical fluxes during spring bloom conditions  

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The arsenic (As) cycle in the marine environment is known to be sensitive to biological activity. Within the scope of the National Coastal Oceanography Program, we undertook a specific study of the behaviour of this element in a water column on the continental shelf of the Bay of Biscay off the Gironde estuary during two oceanographic cruises conducted in May 1994 and May 1995. Various chemical forms were measured: arsenite (As3), at-senate (As5), monomethylarsenic (MMA), dimethylarsenic (DMA...

Michel, Pierre; Boutier, Bernard; Herbland, Alain; Averty, Bernard; Artigas, Luis Felipe; Auger, Dominique; Chartier, Emmanuelle

1998-01-01

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Tritium Study of the Mixing of Waters in Lakes and Estuaries, with Particular Reference to the Lake of Geneva and the Gironde  

International Nuclear Information System (INIS)

The results presented here relate to a general study of the dynamics of the Lake of Geneva (Léman) and the Gironde. Tritium was used as a tracer in order to differentiate waters with identical physico-chemical characteristics. On the Lake of Geneva campaigns carried out at different hydrological periods on the two main affluents revealed a surface current, a main current at half depth and a turbidity current in a sub- lacustrine canyon. Three layers with their own well-defined dynamic behaviour (0 - 50 m, 50 - 150 m and 150 - 310 m) correspond to these movements. Only the surface layer may become homogeneous in winter. In the Gironde the use of tritium enabled us to determine, in waters having identical or constant salinities, whether the fresh waters were of different fluvial origins. In this way we observed a substantial difference in dynamic behaviour and the absence of any significant exhanges between the edges and the centre of the Gironde. In estuaries this method should permit the study of flood propagation and the formation of high-turbidity zones. (author)

1970-09-01

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Geochemical risk assessment of a case study of climate change adaptation policy: the managed realignment of an island in the Gironde Estuary (SW France)  

Science.gov (United States)

During the last millennium, poldering had consisted to reclaim land from the sea by pumping and creating dike to develop, for example, agricultural lands (e.g. tidal marshes, estuarine island). During 1980's, gain land from the sea stopped in Europe because of the concern of rising sea level and for better controlling flood events. This study aims at evaluating the impact of an accidental realignment due to a dam-break on the "Ile Nouvelle" in the Gironde Estuary (France) during the "Xynthia" storm (27-28 February 2010). After this accident, the General Council of Gironde and the national office for coastal territory preservation ("Conservatoire du Littoral"), which own this island, have adopted a new policy of managed realignment allowing soil submersion by estuarine water during each high tide in order to promote rehabilitation of a wetland ecosystem. This management policy has resulted in the re-inundation of formerly agricultural embanked soils. The regular tidal re-inundation of formerly agricultural embanked soils has induced strong biological and morphological changes (mechanical erosion, siltation). Based on 50 soils samples, spatial distribution of priority metal contaminants (Ni, Cr, Zn, Cu, As, Cd, Pb and Hg) was conducted using GIS (Arcview®). Metal concentrations were compared to local geochemical background measured at the bottom of a sediment core in the Gironde Estuary. Only a moderate Cd enrichment was observed (~2 to 7 times) and attributed to former deliberate submersion of vineyard soils on the island to fight off the damage caused by Phylloxera. Leaching experiments simulating episodic immersion during winter (salinity 0) and summer (salinity 12) were performed for investigating metal reactivity during soil suspension. Part of Cu and As were released from the soils at whatever salinity, whereas Cd release occurred only for salinity 12. Such desorption processes present potential geochemical risk to the Gironde Estuary. In contrast, during winter submersion events the studied soils would act as Cd sinks, adsorption being the dominating process. Coupling Acoustic Doppler Current Profiler (ADCP) and 2 multi-parameters probes (OBS and SMATCH) during 2 spring-tide cycles allowed estimating residual metal fluxes, suggesting that under these conditions the Ile Nouvelle acts as a metal sink receiving ~5 kg of Cd, 440 kg of Cu et 480 kg of As. A bathymetry mapping of the corridor (mechanical erosion of the de-poldering area) was used to estimate the annual sedimentary and metals fluxes exported due to its erosion. Annual fluxes related to corridor erosion, compared to fluxes into the Gironde Estuary are significant for Cu and As. With climate change adaptation policies, managed realignment is becoming more common in the future. Consequently, it will be necessary before this management policy to assess the geochemical risk of the re-inundation of formerly embanked soils.

Ivanovsky, Anastasia; Coynel, Alexandra; Kessaci, Kahina; Kervella, Stéphane; Curti, Cécile; Sottolichio, Aldo; Blanc, Gérard

2014-05-01

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Seaward pinching out and internal stratigraphy of the Gironde incised valley on the shelf (Bay of Biscay)  

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An incised paleovalley offshore the estuary mouth of the Gironde River (Southwest France) was evidenced recently (Comptes Rendus de 1'Academie des Sciences de Paris 326 (1998) 701). Nevertheless its seaward extension to the shelf break was still unknown. New high-resolution geophysical data were acquired on the continental shelf in order to follow the incision until the shelf break. After processing the seismic lines, the shape of the valley was identified and the valley-fill in terms of sequ...

Lericolais, Gilles; Berne, Serge; Fenies, Hugues

2001-01-01

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Collapse of allis shad, Alosa alosa, in the Gironde system (southwest France): environmental change, fishing mortality, or Allee effect?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

At the end of the 20th century the allis shad population in the Gironde was the largest in Europe. During the first decade of the 21st century, catches declined dramatically by two orders of magnitude, and a fishery moratorium was implemented in 2008. This deterioration in the status of the stock was confirmed by three independent assessments (abundance of juveniles and of potential and effective spawners). Three hypotheses on the cause of the collapse were examined: (i) an environmental chan...

Rougier, T.; Lambert, P.; Drouineau, H.; Girardin, M.; Castelnaud, G.; Carry, L.; Aprahamian, M.; Rivot, E.; Rochard, E.

2012-01-01

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Trends in turbidity in the fluvial section of a highly turbid macrotidal estuary, the Gironde in SW France, based on continuous in-situ monitoring  

Science.gov (United States)

The fluvial-estuarine system of the Gironde (SW France) is one of the largest European estuaries, in terms of surface area and of annual mean discharge. The upstream tidal asymmetry and subsequent tidal pumping are the main mechanisms that develop a pronounced Turbidity Maximum Zone (TMZ) characterized by high suspended sediment concentrations (SSC), over 1 g/L in surface waters. Freshwater inflow and tidal cycles are the major factors that affect the size, position and concentration of the TMZ along the estuary axis. In the context of global change, the decrease in freshwater flows (changes in rainfall, upstream land use) and sea level rise may lead to a progressive upstream displacement and an increasing persistence of TMZ, close to the uppermost limit of tidal influence. Understanding and predicting trends of turbidity are then crucial for a better present and future evaluation of the estuarine processes, as well as for a more sustainable management and planning of the landscape. At present, these tasks are difficult due to the limited available data, mainly obtained in the lower reaches. The upper Gironde estuary consists of two tidal rivers (Garonne and Dordogne), where sections are narrow, and where SSC and sediment fluxes are particularly sensitive to changes on river flow. Up to recently, the upper reaches were still poorly documented. Since 2004, as a part of the MAGEST network, a real-time continuous system records turbidity at representative stations of the fluvial (Bordeaux and Portets on the Garonne River; Libourne on the Dordogne River) and central estuary, aims to establish a long-term reference database. In this work, we present 9-years of records of turbidity for analysis and discussion of the trends at the limit of freshwater influence at different time scales. The turbidity sensor (Endress and Hauser, CUS31-W2A) measures values between 0 and 9999 NTU (9999 NTU correspond to about 8 g/L). Continuous measurements reveal the temporal changes in turbidity due to deposition-resuspension processes related the tidal cycles, and to changes in fluvial discharges. In particular, only such a continuous record can capture turbidity signatures of a flood peak that often occur for a few hours. For the Gironde estuary, we show that turbidity maxima during flood events are 4-10 times lower compared to TMZ values during a drought period. There are marked seasonal differences in daily-averaged turbidities, from about 10 to nearly 9999 NTU, in both the Garonne and Dordogne Rivers. We found a pronounced interannual variability in the concentration and persistence of the TMZ according to hydrological conditions. In the Garonne River, the mean concentration and duration of TMZ presence are 2845 NTU - 93 days and 4134 NTU - 250 days during a wet and dry year, respectively. The dependence of turbidity on tidal range varies in function to river flow and the stronger relationships are observed for discharges below 150m3/s. By analyzing the turbidity evolution during the installation and expulsion of TMZ, we show that the relationship between turbidity and discharge follows a hysteresis patterns during these transition periods.

Jalón Rojas, Isabel; Schmidt, Sabine; Sottolichio, Aldo

2014-05-01

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Impacts of anthropogenic pressures on the water quality of the Gironde Estuary (SW France) from the Urban Agglomeration of Bordeaux: spatial characterization and inputs of trace metal elements (Ag, As, Cd, Cu, Pb and Zn)  

Science.gov (United States)

Recent European legislation (2000/60/CE) has listed eight trace metal elements as priority toxic substances for water quality. Urban metal inputs into hydrosystems are of increasing interest to both scientists and managers facing restrictive environmental protection policies, population increase and changing metal applications. The Gironde Estuary (SW France; 625 km2) is known for its metal/metalloid pollution originating from industrial (e.g. Cd, Zn, Cu, As, Ag, Hg) or agricultural sources (e.g. Cu) in the main fluvial tributaries (Garonne and Dordogne Rivers). However, little peer-reviewed scientific work has addressed the impact of urban sources on the Gironde Estuary, especially the Urban Agglomeration of Bordeaux (~1 million inhabitants) located on the downstream branch of the Garonne River. In this study, a snapshot sampling campaign was performed in 2011 for characterizing the spatial distribution of dissolved and particulate metal/metalloid (As, Ag, Cd, Pb, Zn, Cu) concentrations in three suburban watersheds: the Jalle of Blanquefort (330 km2), Eau Bourde (140 km2), and Peugue (112 km2). Furthermore, particulate metal Enrichment Factors (EF) were calculated using local geochemical background measured at the bottom of a sediment core (492 cm). Results indicated that metal concentrations displayed a high spatial variability depending on the suburban watershed and the studied element. Local concentrations anomalies were observed for: (i) As in the Eau Bourde River in dissolved (4.2 ?g/l) and particulate phases (246 mg/kg; EF= 20) and attributed to a nearby industrial incinerator; (ii) Zn in the Peugue River with maximum dissolved and particulate concentrations of 87 ?g/l and 1580 mg/kg (EF=17), respectively, probably due to urban habitation runoff; (iii) Ag in the Jalle of Blanquefort River with high dissolved (74 ng/l) and particulate concentrations (33.7 mg/kg; EF=117) due to industrial activities in the downstream part. Based on hydro-geochemical monitoring of both suburban rivers and local wastewater treatment plants (WWTPs), we present a first estimate of metal/metalloid fluxes and compare them to the respective loads in the Garonne River. Our results suggest that suburban metal inputs may significantly increase metal concentrations and fluxes in the fluvial Gironde Estuary, especially for Ag due to inputs exported by WWTPS and the Jalle of Blanquefort River.

Kessaci, Kahina; Coynel, Alexandra; Blanc, Gérard; Deycard, Victoria N.; Derriennic, Hervé; Schäfer, Jörg

2014-05-01

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Response of biota to sedimentary organic-matter quality of the west gironde mud patch, bay of biscay (france)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Relationships between benthos and sedimentary organic matter quality were analyzed in the West Gironde Mud Patch (WGMP), on the shelf of the Bay of Biscay, off the Gironde estuary, as part of the multidisciplinary national programme Ecomarge, a JGOFS-France contribution. At three stations located on an east-west transect and at different periods from 1985 to 1988, the following parameters of the sediment were analyzed: POC (particulate organic carbon); SIGMA (sum of easily extractable macromo...

Relexans, Jc; Lin, Rg; Castel, J.; Etcheber, H.; Laborde, P.

1992-01-01

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Monitoring water quality in estuarine environments: lessons from the MAGEST monitoring programme in the Gironde fluvial-estuarine system  

Directory of Open Access Journals (Sweden)

Full Text Available The Gironde estuary, one of the largest European ones, presents temporary low dissolved oxygen content in its fluvial section close to the Bordeaux urban area. In a context of population growth and of long-term environmental changes, the development of a high-frequency monitoring programme of the fluvial-estuarine system of the Gironde, called MAGEST (MArel Gironde ESTuary, had appeared essential to address current and future water-quality issues/evaluations. The objectives of the MAGEST survey programme are to establish a reference database to improve the knowledge of the Gironde estuary functioning, encompassing the aspects of hydrology, sediment dynamics and biogeochemistry. Through examples of results from intratidal to seasonal time scales, we demonstrate how such a time-series is of valuable interest to extract the main trends of its functioning and of the water quality in relation to external forcings (climatology, urban wastes, land use, ... and to predict the future evolution of the Gironde estuary with global and environmental changes.

H. Etcheber

2010-12-01

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Long-term records of cadmium and silver contamination in sediments and oysters from the Gironde fluvial-estuarine continuum - Evidence of changing silver sources  

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The Gironde fluvial estuarine system is impacted by historic metal pollution (e.g. Cd, Zn, Hg) and oysters (Crassostrea gigas) from the estuary mouth have shown extremely high Cd concentrations for decades. Based on recent work (Chiffoleau et al., 2005) revealing anomalously high Ag concentrations (up to 65 mg kg(-1); dry weight) in Gironde oysters, we compared long-term (similar to 1955-2001) records of Ag and Cd concentrations in reservoir sediment with the respective concentrations in oyst...

Lanceleur, Laurent; Schaefer, Joerg; Chiffoleau, Jean-francois; Blanc, Gerard; Auger, Dominique; Renault, Sophie; Baudrimont, Magalie; Audry, Stephane

2011-01-01

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Estuaries  

Science.gov (United States)

Estuaries are bodies of water and their surrounding coastal wetlands typically found where rivers meet the sea. Estuaries harbor unique plant and animal communities because their waters are brackish--a mixture of fresh water draining from the land and salty seawater.Estuaries are some of the most productive ecosystems in the world. Many animal species rely on estuaries for food, places to breed, and migration stopovers. Human communities also rely on estuaries for food, recreation, jobs, and coastal protection.Of the 32 largest cities in the world, 22 are located on estuaries (e.g., New Orleans, London, etc). Not surprisingly, human activities have led to the decline in the health of estuaries, making them one of the most threatened ecosystems on the Earth. NOAA's National Estuarine Research Reserve System in partnership with coastal states monitors the health of estuaries and helps communities manage their coastal resources.

Educator, Laura K.; National Science Teachers Association (NSTA); Review, Steve W.

2005-04-01

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VARIABILITES MORPHOLOGIQUE ET DU TAUX D’HORMONE DE CROISSANCE DES CIVELLES D'ANGUILLES EUROPEENNES (Anguilla anguilla DANS L'ESTUAIRE DE LA GIRONDE AU COURS DE LA SAISON 1997-1998 MORPHOLOGICAL AND GROWTH HORMONE VARIABILITIES OF EUROPEAN GLASS-EEL (Anguilla anguilla IN GIRONDE ESTUARY DURING 1997-1998 SEASON  

Directory of Open Access Journals (Sweden)

Full Text Available L’objectif de ce travail est de compléter la caractérisation morphologique des civelles entrant dans l’estuaire de la Gironde par un paramètre physiologique, le taux d’hormone de croissance. Le flux d’arrivée a été suivi lors de la saison 1997 – 1998. 303 civelles au stade Vb ont été capturées et analysées individuellement. La longueur et la masse des individus diminuent en février, le facteur de condition seulement en mars. Le taux moyen d’hormone de croissance passe de 6 ng/hypophyse en moyenne en décembre à 16 ng/hypophyse en février et mars pour atteindre 20 ng/hypophyse en avril et mai. L’hypothèse la plus plausible est que cette augmentation du taux d’hormone traduise une détresse physiologique de plus en plus importante des animaux qui arrivent. The aim of this study is to complete the morphological description of Gironde glass eels according to a physiological parameter, the growth hormone. The incoming flux had been observed during the migration season 1997-1998. 303 glass eels of pigmentation stage Vb were caught and individually analysed. The length and the weight of the glass eels decreased in February, the condition factor only in March. The growth hormone rate increased from an average of 6 ng/pituitary in December to an average of 16 ng/pituitary in February and March and up to an average around 20 ng/pituitary in April and May. The most credible hypothesis is that the first incoming glass eels show a smaller distress level than the last ones.

LAMBERT P.

2008-04-01

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Formation of anoxia and denitrification in the bottom waters of a tropical estuary, southwest coast of India  

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Full Text Available Hydrographic characteristics of the southwest coast of India and its adjoining Cochin backwaters (CBW were studied during the summer monsoon period. Anomalous formation of anoxia and denitrification were observed in the bottom layers of CBW, which have not been previously reported elsewhere in any tropical estuarine systems. The prevalent upwelling in the Arabian Sea (AS brought cool, high saline, oxygen deficient and nutrient-rich waters towards the coastal zone and bottom layers of CBW during the high tide. High freshwater discharge in the surface layers brought high amount of nutrients and makes the CBW system highly productive. Intrusion of AS waters seems to be stronger towards the upstream end (~15 km, than had been previously reported, as a consequence of the lowering of river discharges and deepening of channels in the estuary. Time series measurements in the lower reaches of CBW indicated a low mixing zone with increased stratification, 3 h after the high tide (highest high tide and high variation in vertical mixing during the spring and neap phases. The upwelled waters (O2?40 ?M intruded into the estuary was found to lose more oxygen during the neap phase (suboxic O2?4 ?M than spring phase (hypoxic O2?10 ?M. Increased stratification coupled with low ventilation and presence of high organic matter have resulted in an anoxic condition (O2=0, 2–6 km away from barmouth of the estuary and leads to the formation of hydrogen sulphide. The reduction of nitrate and formation of nitrite within the oxygen deficient waters indicated strong denitrification intensity in the estuary. The expansion of oxygen deficient zone, denitrification and formation of hydrogen sulphide may lead to a destruction of biodiversity and an increase of green house gas emissions from this region.

G. D. Martin

2010-03-01

 
 
 
 
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On the quantity and composition of floating plastic debris entering and leaving the Tamar Estuary, Southwest England.  

Science.gov (United States)

The majority of plastic debris found in the marine environment has land based sources and rivers are considered an important medium for transfer of this debris. Here we report on the quantity and composition of floating plastic debris collected from surface waters of the Tamar Estuary. This represents the first study of riverine transport of floating plastic debris into European waters during different tidal regimes. Plastics were found in a variety of forms and sizes and microplastics (<5 mm) comprised 82% of the debris. The most abundant types of plastic were Polyethylene (40%), Polystyrene (25%) and Polypropylene (19%). There was a significant difference in size frequency distribution between the spring and neap tides with more fragments of larger size observed during spring tides. While it is clear that debris has accumulated on shorelines within the estuary, during our study this river did not identify as a net source or sink. PMID:24613232

Sadri, Saeed S; Thompson, Richard C

2014-04-15

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Toxic Metals Enrichment in the Surficial Sediments of a Eutrophic Tropical Estuary (Cochin Backwaters, Southwest Coast of India)  

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Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surficial sediments of the Cochin backwaters were studied during both monsoon and pre-monsoon periods. Spatial variations were in accordance with textural charaterstics and organic matter content. A principal component analysis distinguished three zones with different metal accumulation capacity: (i) highest levels in north estuary, (ii) moderate levels in central zone, and (iii) lowest levels in sout...

Martin, G. D.; George, Rejomon; Shaiju, P.; Muraleedharan, K. R.; Nair, S. M.; Chandramohanakumar, N.

2012-01-01

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Formation of anoxia and denitrification in the bottom waters of a tropical estuary, southwest coast of India  

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Hydrographic characteristics of the southwest coast of India and its adjoining Cochin backwaters (CBW) were studied during the summer monsoon period. Anomalous formation of anoxia and denitrification were observed in the bottom layers of CBW, which have not been previously reported elsewhere in any tropical estuarine systems. The prevalent upwelling in the Arabian Sea (AS) brought cool, high saline, oxygen deficient and nutrient-rich waters towards the coastal zone and bottom layers of CBW du...

2010-01-01

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Behaviour of REEs in a tropical estuary and adjacent continental shelf of southwest coast of India: evidence from anomalies  

International Nuclear Information System (INIS)

The distribution and accumulation of the rare earth elements (REE) in the sediments of the Cochin Estuary and adjacent continental shelf were investigated. The rare earth elements like La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the heavy metals like Mg, V, Cr, Mn, Fe, Cu, Zn, U, Th were analysed by using standard analytical methods. The Post-Archean Australian Shale composition was used to normalise the rare earth elements. It was found that the sediments were more enriched with the lighter rare earth elements than the heavier ones. The positive correlation between the concentrations of REE, Fe and Mn could explain the precipitation of oxyhydroxides in the study area. The factor analysis and correlation analysis suggest common sources of origin for the REEs. From the Ce-anomalies calculated, it was found that an oxic environment predominates in all stations except the station No. 2. The Eu-anomaly gave an idea that the origin of REEs may be from the feldspar. The parameters like total organic carbon, U/Th ratio, authigenic U, Cu/Zn, V/Cr ratios revealed the oxic environment and thus the depositional behaviour of REEs in the region. (author)

2012-10-01

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Fish composition and assemblage structure in three Eastern English Channel macrotidal estuaries: A comparison with other French estuaries  

Science.gov (United States)

This study has analysed for the first time fish composition and assemblage structures of three small macrotidal estuaries of the Eastern English Channel (EEC) and has explored the influences of 19 biotic and abiotic variables on the fish assemblages. Fish from Canche, Authie and Somme estuaries were collected during spring (June 2006 and May 2007) and autumn (September 2006) along the estuarine gradients using a 1.5 m beam trawl. Using identical sampling protocols, the study also analysed and compared for the first time taxonomic and functional aspects of the fish assemblages in 15 estuaries located along the Atlantic and English Channel coasts. SIMPER analysis showed high similarities in fish assemblages in the three EEC estuaries and during either spring or autumn periods. However, intra-estuary similarities were relatively low, indicating that fish assemblage structures (species richnesses or abundances) were more variable within the estuary (salinity gradient) than between estuaries and/or seasons (spring vs autumn). Although numerous environmental variables were included in the study, only 47% of the variability observed in the fish distribution was explained. Fish spatial variations in the EEC estuaries are mostly driven by abiotic variables as opposed to biological interactions. As indicated by CCA, salinity and muddy sediments were the two most important factors structuring the fish assemblages. The macrobenthos being very abundant in the EEC estuaries (580-1121 ind. m -2), the availability of potential prey is probably not a limiting factor in the utilization of estuaries by fish. Contrary to the majority of French estuaries dominated by estuarine species (ES), the fish assemblages of the EEC estuaries are clearly dominated by marine migrant (MM) species (65% on average) with high abundance of juveniles (mostly young-of-the-year). Cluster and SIMPROF's analyses distinguished the functional structure of the 15 estuarine fish assemblages into different clusters. The three EEC estuaries form a similar group with the largest French estuaries (Seine, Loire and Gironde). The latters were characterized by higher MM/ES ratio compared to the other French estuaries. Freshwater flow and tidal range were the main factors associated with this group of estuaries. The results of the present study do not indicate that anthropogenic impacts (chemical contamination) on estuaries affect their ecological functioning as described by the fish ecological guilds. It is suggested that the guild approach may not be useful to provide valuable information on the ecological status of estuaries.

Selleslagh, Jonathan; Amara, Rachid; Laffargue, Pascal; Lesourd, Sandric; Lepage, Mario; Girardin, Michel

2009-01-01

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Détermination de l'âge et croissance de l'Acipenser sturio L. de la Gironde  

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Full Text Available La détermination de l'âge de 66 Esturgeons (Acipenser sturio L, péchés en 1958 en Gironde, a été réalisée par l'étude de coupes minces effectuées principalement dans le premier rayon de la nageoire pectorale. Les résultats ont été comparés avec ceux obtenus par CLASSEN (1944, D'ANCONA (1923-1926 et PACCAGNELLA (1948 pour les mêmes Acipenser du Guadalquivir, du Tibre et du Pô. Un caractère commun les rapproche, c'est leur croissance lente ; mais l'Esturgeon de la Gironde croît moins rapidement que celui du Guadalquivir qui lui-même a une croissance plus lente que celui du Tibre et du Pô.

MAGNIN É.

2008-10-01

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3D modelling of seasonal evolution of Loire and Gironde plumes on Biscay Bay continental shelf  

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A 3D model of the Atlantic shelf has been developed and applied to study shelf dynamics and evolution of hydrology. The model takes the combined effects of tide, wind, river discharges and surface heat flux into account. Time scales vary from 1 day to several years. Following a brief description of the model and forcing variables, the behaviour of the Loire and Gironde plumes is described, first for winter and spring, then over a period of several years, under realistic forcing. The results s...

Lazure, Pascal; Jegou, Anne-marie

1998-01-01

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Typology Estuaries  

Typology Estuaries Environment Agency copyright and / or database right 2010. All rights reserved. This map includes data supplied under licence from: Crown Copyright and database right 2010. All rights reserved. Ordnance Survey licence number 100026380. Some river features of this map are based on…

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Estuary regime  

International Nuclear Information System (INIS)

The primary aim of this research into estuary regime is to provide engineers with an improved method of predicting the long term evolutionary effects of major engineering changes in estuaries. Of specific interest to the Department of Trade and Industry's renewable energy R and D programme is the long term impact of tidal energy barrages on estuarine morphology. It is considered that the approach being taken is the most appropriate line to follow in terms of developing an applicable estuary regime predictive capability. As a consequence it is considered that any further regime model development should be complimentary to this approach. In addition to model development there is still an enormous amount of basic research required in examining sediment transport processes within the estuarine environment. Recently developed models for predicting the motion of fluidised mud on inter-tidal and sub-tidal banks, an important process within the estuarine sediment regime, requires specific field data calibration and validation. The impacts of wave action on sediment mobility on estuarine banks is a further area requiring field measurements. It is recommended that the opportunity be taken to obtain a set of measurements at a site following construction of major engineering works to provide data for future verification of a regime model. Possibilities exist, for example, on the Tees Estuary for such measurements. (author)

1994-01-01

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THE EFFICIENCY OF SELECTIVE TIDAL STREAM TRANSPORT IN GLASS EEL ENTERING THE GIRONDE (FRANCE) EFFICACITÉ DE LA MIGRATION DES CIVELLES ENTRANT DANS LE BASSIN DE LA GIRONDE EN UTILISANT UN TRANSPORT SÉLECTIF TIDAL  

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Traditional estimation of migration speed is based on telemetry or marking of individual fish. Only a few numbers of fishes (or batches) are followed, often over short periods of time. We propose a method based on capture data from the professional fishery. It is applied to glass eel (Anguilla anguilla) in the Gironde basin (France). Migration speed is estimated using 2 methods: a rough method based on the analysis of seasonal abundance peaks for two métiers and a more precise method of cro...

Beaulaton, L.; Castelnaud, G.

2008-01-01

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THE EFFICIENCY OF SELECTIVE TIDAL STREAM TRANSPORT IN GLASS EEL ENTERING THE GIRONDE (FRANCE EFFICACITÉ DE LA MIGRATION DES CIVELLES ENTRANT DANS LE BASSIN DE LA GIRONDE EN UTILISANT UN TRANSPORT SÉLECTIF TIDAL  

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Full Text Available Traditional estimation of migration speed is based on telemetry or marking of individual fish. Only a few numbers of fishes (or batches are followed, often over short periods of time. We propose a method based on capture data from the professional fishery. It is applied to glass eel (Anguilla anguilla in the Gironde basin (France. Migration speed is estimated using 2 methods: a rough method based on the analysis of seasonal abundance peaks for two métiers and a more precise method of cross-correlation, which compares speeds between several fishing areas. The methods are coherent and lead to mean migration speed ranging from 3 to 4 km/day. We define an index of efficiency of migration using selective tidal stream transport (STST efficiency index as the ratio of the observed migration speed to the potential speed (flood tide current speed and swimming speed. For the glass eel in the Gironde basin this index ranges between 0.15 and 0.19. The glass eel behavior, which can explain this low value, is reviewed. Our STST efficiency index can be successfully applied for many fish or crustaceans using selective tidal stream transport. It can also be used for one species to compare results obtained on different basins. Les méthodes traditionnelles d’estimation de la vitesse de migration reposent sur la télémétrie ou les techniques de marquage. Seulement un nombre restreint de poissons (ou lots de poissons sont ainsi suivis, souvent sur un temps court. Nous proposons une méthode basée sur les données de capture de la pêcherie professionnelle. Elle est appliquée au cas de la migration de la civelle (Anguilla anguilla dans le bassin de la Gironde (France. La vitesse de migration est estimée grâce à deux méthodes : une méthode grossière basée sur l’étude des pics saisonniers d’abondance de deux métiers de pêche ; une méthode plus précise utilisant les corrélations croisées qui permet de comparer des vitesses de migration entre plusieurs zones de pêche du bassin. Les résultats des deux méthodes sont cohérents et conduisent à une vitesse moyenne de migration de l’ordre de 3 à 4 km/jour. Nous calculons un indice d’efficacité de la migration utilisant le transport sélectif tidal (STST efficiency index qui est la vitesse réelle des civelles divisée par une vitesse potentielle (la somme de la vitesse des courants de flot et de la vitesse de nage. Pour le bassin de la Gironde, cet indice est compris entre 0,15 et 0,19. Les comportements de la civelle qui peuvent expliquer ces faibles valeurs, sont passés en revue. Notre indice et nos méthodes peuvent être employés pour de nombreuses espèces de poissons et de crustacés qui utilisent le transport sélectif tidal. Il peut également être utilisé pour une espèce donnée pour comparer les résultats obtenus sur différents bassins.

BEAULATON L.

2008-04-01

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Trophic functioning of coastal ecosystems along an anthropogenic pressure gradient: A French case study with emphasis on a small and low impacted estuary  

Science.gov (United States)

The ecological functioning of various French coastal ecosystems, with special emphasis on the Canche estuary, along an anthropogenic pressure gradient was studied using mass-balanced trophic models in order to test the relevance of functional indices assessing the ecological status of coastal systems. A trophic model of the Canche (eastern English Channel, France) estuarine food web was constructed using an Ecopath approach to determine the structure and functioning of energy flows in the trophic network. The model consisted of 15 compartments, from primary producers (trophic level TL = 1) to the top consumers (fish, TL = 3.8). Input parameters were mainly computed from field studies conducted between 2006 and 2007. Results showed that the majority of flows came from detritus, which is an important energy source in the ecosystem, as indicated by mixed trophic impacts. Keystone index (KSI) revealed that amphipods, copepods, gobies and European eel were identified as key compartments in the Canche estuarine food web, with the first two considered as important vectors for carbon transfer from detritus to top predators. The Canche estuary trophic network has a low recycling level (FCI = 0.8%), a low total system throughput (TST = 1364 gC. m-2. y-1) and a low ascendency (A = 1439 gC. m-2. y-1), but a relatively low connectivity (CI = 0.33), high internal relative ascendency (Ai/Ci = 35.6%) and a high omnivory index (OI = 0.04), indicating that this estuary is immature but relatively organised and complex, with strong production but which little is used as the estuary depends on external exchanges. In addition, the Canche estuary, recognised as a small and low impacted estuarine ecosystem, was compared with six other French coastal systems: the bay of Somme, the Seine estuary, the Mont Saint-Michel bay, the Loire estuary, the Pertuis Charentais and the Gironde estuary, where Ecological Network Analyses (ENA) have been applied using similar methods. Compared with the other six coastal systems, the Canche estuary did not present a similar functioning to close geographically estuaries or estuaries with similar environmental characteristics. The results of the present study showed that among computed ENA indices, the omnivory index (OI) was positively correlated with an anthropogenic pressure index, suggesting that such a functional index can be useful for assessing the ecological quality of estuarine and coastal systems.

Selleslagh, Jonathan; Lobry, Jérémy; Amara, Rachid; Brylinski, Jean-Michel; Boët, Philippe

2012-10-01

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Coagulation in Estuaries.  

Science.gov (United States)

The coagulation rates of kaolinite, illite, and montmorillonite were determined in solutions at various ionic strengths. In addition, the coagulation rates of selected sediments collected from the Pamlico Estuary of North Carolina were determined. Finally...

J. K. Edzwald

1972-01-01

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Phytoplankton spring bloom of the Gironde plume waters in the Bay of Biscay: early phosphorus limitation and food-web consequences  

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Au cours du printemps 1995 (2¿25 mai), une campagne océanographique a été réalisée à bord du NO Poséidon (Allemagne) sur le plateau continental Sud-Gascogne. L'objectif était l'étude de la structure et du fonctionnement du réseau trophique planctonique des eaux issues de l'estuaire de la Gironde. Les concentrations en phosphate dans ces eaux étaient extrêmement faibles (indécelable à moins de 0,1 ?mol·L?1) tandis que celles du nitrate, du silicate et de l'ammoniaque...

1998-01-01

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Levels and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments from Lenga Estuary, central Chile.  

Science.gov (United States)

The Lenga Estuary is a small brackish wetland located southwest of San Vicente Bay, Region VIII, Chile. Surface sediment from nine sites in the estuary were analysed for PAHs and compared to Sediment Quality Guidelines (SQG). Sediment samples were freeze dried and soxhlet extracted for 16 h using DCM. Identification and quantification was carried out by HPLC. Organic carbon was also determined. Results showed total PAH concentrations ranged from 290 to 6118 (2025 ± 1975)ng g(-1) d.w. (2025 ± 1975). Results for organic carbon percentages ranged from 1% to 7%. Statistical analysis showed a significant positive correlation (Pearson test) between organic carbon percentage PAHs. Comparison of contaminant levels and international Sediment Quality Guidelines (SQG) (ERL and ER) suggested that sediment of the Lenga estuary did not show any ecotoxicological risk for benthic organisms where high levels of PAHs were detected. Monitoring of this and other contaminants is recommended in Chile. PMID:21612800

Pozo, Karla; Perra, Guido; Menchi, Valentina; Urrutia, Roberto; Parra, Oscar; Rudolph, Anny; Focardi, Silvano

2011-07-01

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75 FR 34975 - Notice of Estuary Habitat Restoration Council's Intent to Revise its Estuary Habitat Restoration...  

Science.gov (United States)

...0648-XX00 Notice of Estuary Habitat Restoration Council's Intent to Revise its Estuary Habitat Restoration Strategy; Request for Public Comment...behalf of the interagency Estuary Habitat Restoration Council, is providing notice of...

2010-06-21

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Go Southwest, Old Man  

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Go Southwest, Old Man, a sort of personal remake of 'Go West, Young Man', the founding episteme of the American nineteenth century, conciliates these two souls (well, not to be pretentious, let's simply say two sides) that have actually always lived in harmony. This is a book generated by a quarter of a century spent wandering around the canyons and deserts of Arizona, Colorado, Utah and, above all New Mexico, with a view to penetrating the by now universal legend of the West, approaching the...

Materassi, Mario

2009-01-01

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Oxidative stress biomarkers in bivalves transplanted to the Guadalquivir estuary after Aznalcóllar spill.  

Science.gov (United States)

Biological effects of metals were studied in clams (Scrobicularia plana) transplanted to Guadalquivir estuary (Spain) at several times after the spill of toxic metals from Aznalcóllar pyrite mine (southwest Spain) (April 1998) using biochemical biomarkers responsive to reactive oxygen species. Significant As, Cd, Fe, Mn, Ni, and Pb uptake was found in clams living for seven months at the estuary (from July 1999). Increased activity of antioxidant (catalase, glucose-6-phosphate, and 6-phosphogluconate dehydrogenase) and glutathione-related (glutathione reductase and glyoxalase I and II) enzymes was also found after short exposures; the levels of malondialdehyde and metallothionein increased also, particularly with long exposures. Clams living four weeks at the estuary (from March 2000) but not at a reference site also accumulated metals. The higher malondialdehyde and lower reduced-glutathione levels and the more oxidized glutathione status confirmed the oxidative stress of clams living at the estuary, while no marked increase of antioxidant activities was found this time. Lower metal availability along the second transplant could explain the limited responses in this shorter experiment. Although the status of Guadalquivir estuary has recovered since Aznalcóllar spill, continuous monitoring is needed to confirm its progress and to be alert to possible deterioration after heavy rains. PMID:12503751

Romero-Ruiz, Antonio; Amezcua, Oscar; Rodríguez-Ortega, Manuel J; Muñoz, José L; Alhama, José; Rodríguez-Ariza, Antonio; Gómez-Ariza, José L; López-Barea, Juan

2003-01-01

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Great Bay Estuary Restoration Compendium.  

Science.gov (United States)

Single species approaches to natural resource conservation and management are now viewed as antiquated and oversimplified for dealing with complex systems. Scientists and managers who work in estuaries and other marine systems have urged adoption of ecosy...

A. Eberhardt D. Burdick J. Odell P. Ingraham

2006-01-01

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FLORA OF MOLOCHNYI ESTUARY COASTS  

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Full Text Available Present-day characteristic of the coastal flora of Molochnyi eastury is given, that is one of the largest estuaries in Ukraine, the shores and waters of which in 2009 became a part of the Pryazov’ya National Nature Park. The analysis of the main parameters of the flora is made. Rare component of the estuary coastal flora is characterized, further steps to conserve the nature of Pryazov’ya are proposed.

Kolomiychuk V.P.

2013-09-01

 
 
 
 
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¡Salud! Southwest Tour  

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Full Text Available During this summer of 2009, 12 American medical students from the Escuela Latinoamericana de Medicina (ELAM – Latin American School of Medicine in Havana, Cuba will board a Recreational Vehicle (RV to travel across the Southwest region of the United States visiting a number of tribal settlements of American Indian Nations, community colleges and universities. While at the various sites the students will share their personal experiences of what it’s like to study at ELAM while promoting the availability of full scholarships for students, volunteer their services while learning about some of the more significant health concerns affecting American Indian populations and to build personal and professional relationships with health care practitioners and members of Native American communities.

Joanna Mae Mae Souers

2009-06-01

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Geochemical, multi-isotopic and hydrogeological characterization of mineralized groundwaters, Entre-deux-Mers area, Gironde (SW France).  

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Groundwater quality sustainability In the south-west of France, the Eocene aquifer is one of the main resources for irrigation, thermo-mineral water, and mainly for drinking water in the Bordeaux region. This aquifer is characterized by the presence of a large mineralized area, centered on the Entre-deux-Mers region, between the Garonne and the Dordogne rivers, where the groundwaters show strong mineralization and anomalous levels of critical elements, such as sulphates and fluoride, leading ...

Malcuit, Eline; Ne?grel, Philippe; Petelet Giraud, Emmanuelle; Atteia, O.; Franceschi, M.; Dupuy, A.; Larroque, F.; Schmidt, S.; Marchet, Pierre

2010-01-01

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[Rother Estuary Final (2).pdf  

…barrier at Scot's Float across the Eastern Rother, which maintains the non tidal Rother for navigation and water resource purposes. This is also the case for the other rivers that flow into the Rother Estuary which can be an issue for fish passage for migratory fish species. Though Scot's Float has a…

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Thames Estuary 2100 (TE2100)  

The TE2100 Plan sets out the strategic direction for managing flood risk in the Thames estuary to the end of the century and beyond. It sets out how we will continue to protect 1.25 million people and £200 billion worth of property from tidal flood risk.

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Historical morphological change in the Mersey Estuary  

Science.gov (United States)

Several techniques including analysis of bathymetric data, calculation of analytical parameters and computational hydrodynamic simulations are combined in this study to develop a conceptual understanding of processes causing morphological change in the Mersey Estuary between 1871 and 1997. Volumetric analysis demonstrates that morphological change is dominated by a trend of significant accretion between 1906 and 1977, with estuary volume reducing by ?10% (70 Mm3), followed by a relatively small increase in volume between 1977 and 1997. Previous research identified the construction of training walls between 1906 and 1936 to stabilise the position of the low water channel in Liverpool Bay outside the estuary as a probable cause of perturbation. The paper examines the hypothesis that sedimentation in the estuary was controlled by changes to hydrodynamic flow and related sediment transport patterns outside the estuary resulting from training wall construction, and that the estuary has now evolved towards a stable state. The results from computational hydrodynamic models for the years 1906, 1936 and 1977 quantifying potential changes in sediment transport pathways from outside the estuary indicate a significant increase in potential sediment supply to the mouth of the estuary during the period of peak accretion. However, these changes cannot be solely attributed to construction of the training walls, but result from the combined effect of training wall construction and dredging activity in the sea approach channels. Furthermore, it is not simply changes in hydrodynamic flow characteristics that cause sedimentation but also the existence of salinity-induced gravitational circulation within the estuary and wider Liverpool Bay system that acts as an important mechanism for importing sediment into the estuary. Evidence for evolution towards a stable estuary state is provided by derivation of a sediment budget demonstrating a negligible net flux of sediment into the estuary between 1977 and 1997. The establishment of a stable state is attributed to a reduction in the calculated transport of sediment across Liverpool Bay reducing the supply of sediment to the estuary mouth.

Thomas, C. G.; Spearman, J. R.; Turnbull, M. J.

2002-07-01

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Environmental data management in the Sado Estuary  

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Estuaries are perhaps the most threatened environments in the coastal fringe; the coincidence of high natural value and attractiveness for human use has led to conflicts between conservation and development. These conflicts occur in the Sado Estuary since its location is near the industrialised zone of Peninsula of Setúbal and at the same time, a great part of the Estuary is classified as a Natural Reserve due to its high biodiversity. These facts led us to the need of implementing a model o...

Caeiro, Sandra Sofia Ferreira Da Silva

2004-01-01

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Morphodynamic equilibrium of alluvial estuaries  

Science.gov (United States)

The evolution of the longitudinal bed profile of an estuary, with given plan-form configuration, subject to given tidal forcing at the mouth and prescribed values of water and sediment supply from the river is investigated numerically. Our main goal is to ascertain whether, starting from some initial condition, the bed evolution tends to reach a unique equilibrium configuration asymptotically in time. Also, we investigate the morphological response of an alluvial estuary to changes in the tidal range and hydrologic forcing (flow and sediment supply). Finally, the solution helps characterizing the transition between the fluvially dominated region and the tidally dominated region of the estuary. All these issues play an important role also in interpreting how the facies changes along the estuary, thus helping to make correct paleo-environmental and sequence-stratigraphic interpretations of sedimentary successions (Dalrymple and Choi, 2007). Results show that the model is able to describe a wide class of settings ranging from tidally dominated estuaries to fluvially dominated estuaries. In the latter case, the solution is found to compare satisfactory with the analytical asymptotic solution recently derived by Seminara et al. (2012), under the hypothesis of fairly 'small' tidal oscillations. Simulations indicate that the system always moves toward an equilibrium configuration in which the net sediment flux in a tidal cycle is constant throughout the estuary and equal to the constant sediment flux discharged from the river. For constant width, the bed equilibrium profile of the estuarine channel is characterized by two distinct regions: a steeper reach seaward, dominated by the tide, and a less steep upstream reach, dominated by the river and characterized by the undisturbed bed slope. Although the latter reach, at equilibrium, is not directly affected by the tidal wave, however starting from an initial uniform stream with the constant 'fluvial' slope, the final equilibrium state is reached through an erosional wave, which leads to bed degradation of the upstream 'fluvial reach'. For a given river discharge, the length of the tidal reach increases quite rapidly with tidal amplitude, up to some threshold value of the tidal amplitude above which the length of the estuary becomes comparable with the length of the tidal wave. When the channel plan-form is convergent, deposition of sediments of fluvial origin in the funnel-shaped region drastically changes the equilibrium configuration. The effect of an increasing channel convergence is thus to induce bed aggradation close to the inlet. Nevertheless, tidal forcing only slightly changes the non-tidal profile. The effect of increasing tidal oscillations again leads to an increase of the bed slope at the inlet and to a general bed degradation upstream. The effects of varying sediment supply, flow discharge and river width in the upstream reach have also been investigated and play an important role. Further geomorphological implications of these results will be discussed at the meeting. References Dalrymple, R. W., and K. Choi (2007), Morphologic and facies trends through the fluvialmarine transition in tide-dominated depositional systems: A schematic framework for environmental and sequence-stratigraphic interpretation, Earth-Science Reviews, 81(3-4), 135-174, doi:10.1016/j.earscirev.2006.10.002. Seminara, G., M. Bolla Pittaluga, and N. Tambroni (2012), Morphodynamic equilibrium of tidal channels, Environmental Fluid Mechanics: Memorial Volume in Honour of Prof. Gerhard H. Jirka, 153-174

Tambroni, Nicoletta; Bolla Pittaluga, Michele; Canestrelli, Alberto; Lanzoni, Stefano; Seminara, Giovanni

2014-05-01

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ANALYSE DE LA TENDANCE DE L’ABONDANCE DE L’ALOSE ALOSA ALOSA EN GIRONDE À PARTIR DE L’ESTIMATION D’INDICATEURS HALIEUTIQUES SUR LA PÉRIODE 1977-1998. ABUNDANCE TREND ANALYSIS OF THE ALLIS SHAD ALOSA ALOSA IN THE GIRONDE BASIN DURING THE 1977-1998 PERIOD ON THE BASIS OF ESTIMATED FISHING INDICATORS  

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Full Text Available Au cours des deux dernières décennies, la population d’alose vraie Alosa alosa a été considérée par différents auteurs en diminution, même vouée à la disparition, puis en progression, ou se maintenant à un haut niveau d’effectif dans le bassin de la Garonne. L’objectif de ce travail est de produire les indicateurs halieutiques les plus aptes à rendre compte de la tendance de l’abondance de l’alose vraie en Gironde sur la période 1977-1998. Ces indicateurs saisonniers sont d’une part la CPUE et d’autre part la production totale et l’effort total qui doivent permettre d’expliciter et de conforter le diagnostic sur la tendance de l’abondance. L’échantillon non-aléatoire de données de capture et d’effort provenant d’un réseau de pêcheurs coopératifs, a été stratifié selon les métiers de pêche, les zones de pêche et les quinzaines de pêche. L’estimation des captures totales et des efforts totaux fait appel à la théorie classique de l’échantillonnage avec stratification. Afin d’obtenir un indice qui reflète le mieux possible les variations d’abondance inter-annuelles et qui limite l’incidence des variations de capturabilité dans l’espace et dans le temps, nous avons utilisé la théorie du Modèle Linéaire Général pour construire un modèle log-linéaire qui donne le même poids aux zones et aux quinzaines de pêche sur toute la période d’étude. Le modèle explique la CPUE comme l’addition des effets principaux des facteurs zone, année et quinzaine. Une évolution en paliers des indices d’abondance est testée grâce à un modèle à erreur auto-régressive. On constate que les paliers sont très hautement significatifs pour la Gironde et les trois compartiments Estuaire, Garonne, Dordogne. L’analyse des trois indicateurs halieutique et la confrontation de leur évolution nous amènent à conclure que l’abondance d’A. alosa est au minimum stable en Gironde et qu’elle a très certainement augmenté au cours de la période 1977-1998. Le saut des indices d’abondance observé en 1994 peut être rapporté à l’effet de la mise en place des passes et ascenseurs à poissons sur les parties amont de Garonne et Dordogne. Ces résultats encourageants ne doivent pas dissuader les gestionnaires d’adopter une approche prudente de la population d’alose dans le bassin de la Garonne, compte tenu du statut de cette espèce en Europe. The population of the allis shad Alosa alosa has been considered successively in the last twenty years as declining, endangered, increasing, in a satisfactory status. The objective of this study is to estimate the most appropriate fishing indicators which can allow us to state on the abundance trend of Alosa alosa during the 1977-1998 period. These fishing indicators are CPUE, total catch and total fishing effort. The non-random sample of data provided by a group of cooperative fishermen has been stratified with fishing techniques, fishing area, fortnight periods of fishing. The estimate of total catches and total efforts is based on the classical theory of stratified sampling. We used the General Linear Model method to obtain CPUE from a log-linear model, which limits the effects of the variations of capturability in space and time. These CPUE are supposed to be representative of the inter-annual variation of abundance. The model explains the CPUE as the addition of the main effects of the factors zone, year and fortnight. The trend of the abundance indexes is modeled by a step function with an autoregressive error model. The plateaus appear to be very highly significant for the Gironde basin as well as for the sections Estuaire, Garonne, Dordogne. The analysis of the three fishing indicators and the comparison of their evolution lead to the conclusion that the abundance of Alosa alosa is at least stable and has certainly increased in the Gironde basin. The jump of the CPUE observed in 1994 can be related to the construction of fishways in the upper parts of the Garonne and Dordogne rivers. These e

CASTELNAUD G.

2008-05-01

49

AFS Estuaries Section - A Successful Partnership  

Science.gov (United States)

The Estuaries Section of the American Fisheries Society offers travel awards to students in support of their attendance and presentations at the AFS meeting. Since 2007, the Southern Association of Marine Laboratories has partnered with the Estuaries Section to sponsor two stude...

50

An electrochemical study of Ni, Sb, Se, Sn, U and V in the estuary of the Tamar  

Science.gov (United States)

Cathodic stripping voltammetry (CSV) was used to investigate the behaviour of several dissolved trace elements (Ni, Sb, Se, Sn, U and V) in the Tamar estuary (south-west England). An attempt was made to differentiate between the labile and non-labile (organically or colloidally bound) metal fractions in the estuary by utilizing ligand competition between an added electroactive ligand and the natural complexing material. Surface-active organic material was found to interfere with the CSV determinations and prohibited the determination of low concentrations of labile Sn, Sb, V and Se occurring in the Tamar estuary, but the total dissolved concentrations of these elements could be determined after UV photolysis. Both labile and total dissolved concentrations of Ni could be determined and these were used to establish the speciation of this element. It was found that the non-labile and labile Ni fractions were not in equilibrium throughout the estuary and that these two fractions behaved independently, the organically complexed fraction behaving conservatively and the labile fraction non-conservatively. Total dissolved selenium and vanadium were found to behave largely conservatively; variation in the concentration of vanadium at very low salinities (below 0·2) could be due to variations in the freshwater input or to removal processes. Uranium was found to show partial removal at low to intermediate salinities. Antimony was found to be scavenged from solution in the low-salinity region (Shydroxide particles could account for some of the variations seen for uranium and vanadium. The tin concentration in the estuary was considerably enhanced by tin pollution at the mouth of the estuary presumably due to inputs of organotin (as tributyltin). This tin was found to behave conservatively.

van den Berg, C. M. G.; Khan, S. H.; Daly, P. J.; Riley, J. P.; Turner, D. R.

1991-09-01

51

Biomarker pigment signatures in Cochin back water system - A tropical estuary south west coast of India  

Science.gov (United States)

Sedimentary biomarker pigments around Cochin estuary situated in the southwest coast of India were determined by HPLC. Fucoxanthin, an indicator of diatom was observed to be the most abundant carotenoid pigment in the estuary. Dinoflagellate derived carotenoid pigment peridinin was confined in the southern part of estuary and zeaxanthin pigment indicative of cyanobacteria were more found in sites influenced by anthropogenic activities. One compound having close similarity to fucoxanthin was also detected. Alloxanthin (cryptophyceae), chl b (green algae), canthaxanthin, neoxanthin, lutein and peridinin isomer were also detected by spectra and corresponding algal class were identified. The highest concentration of chl a (11.01 ?g g-1) found near to the anthropogenic affected area while the lowest chl a (0.65 ?g g-1) was recorded in industrial area. Degradation products of chl a, such as pheophorbide and pheophytin were observed and principal mode of mechanism of degradation were derived. Higher pheopigments content than chl a, reflects a density trapping of dead cells and early degradation of phytopigments from grazing activities.

Aneeshkumar, N.; Sujatha, C. H.

2012-03-01

52

Nitrogen, Phosphorus, and Suspended Solids Concentrations in Tributaries to the Great Bay Estuary Watershed in 2011.  

Science.gov (United States)

Nitrogen, phosphorus, and sediment loads to the Great Bay Estuary are a growing concern. The Piscataqua Region Estuaries Partnership (PREP) calculates the nitrogen load from tributaries to the Great Bay Estuary for its State of the Estuaries reports. Ther...

M. A. Wood P. Trowbridge

2012-01-01

53

Geochemical behavior of metals and metalloids in an estuary affected by acid mine drainage (AMD).  

Science.gov (United States)

The Tinto and Odiel rivers in southwest Spain drain the world's largest sulfide mineral formation: the Iberian Pyrite Belt which has been worked since 2,500 BC. The Tinto and Odiel estuarine zones include both an extensive area of salt marsh and an intensively industrialized urban area. As a consequence of pyrite oxidation, the Tinto and Odiel rivers are strongly acidic (pH?drainage affected estuary of the Ría de Huelva. During estuarine mixing, ore-derived metal concentrations exhibit excellent correlations with pH as the main controlling parameter. As pH increases, concentrations of dissolved ore-associated elements are attenuated, and this process is enhanced during the summer months. The decrease in Fe and Al concentrations ranged from 80 to 100 % as these elements are converted from dissolved to sediment-associated forms in the estuary. Coprecipitation/adsorption processes also removed between 60 and 90 % of the originally dissolved Co, Cu, Mn, Pb, Zn, and Th; however, Cd and Ni exhibited a greater propensity to remain in solution, with an average removal of approximately 60 %. On the other hand, As and U exhibited a different behavior; it is likely that these elements remain in dissolved forms because of the formation of U carbonates and soluble As species. Concentrations of As remain at elevated levels in the outer estuary (average?=?48 ?g L(-1)) which exceeds concentrations present in the Tinto River. Nevertheless, the estuary has recently witnessed improvements in water quality, as compared to results of several previous studies reported in the 1990s. PMID:24096526

Hierro, A; Olías, M; Ketterer, M E; Vaca, F; Borrego, J; Cánovas, C R; Bolivar, J P

2014-02-01

54

Smoking rates low in southwest  

Directory of Open Access Journals (Sweden)

Full Text Available No abstract available. Article truncated at 150 words. The Gallup survey confirms that smoking rates in the US are declining and that smoking rates are lower in the Southwest than the US as a whole (1. Nationally, the smoking rate fell to 19.7% in 2013 from 21.1% in 2008. Among the Southwest states California ranked second (15.0%, Colorado ninth (17.4%, and Arizona tenth (17.5%. Only New Mexico was above the Nation's average at 20.0%. Utah remains the state with the lowest percentage of smokers, 12.2 percent, and Kentucky the highest, 30.2 percent. Nine of the 10 states with the lowest smoking rates have outright bans on smoking in private worksites, restaurants, and bars, with California allowing for ventilated rooms. Bans are significantly less common in the 10 states with the highest smoking rates. Kentucky, West Virginia, and Mississippi -- the states with the three highest smoking rates -- do not have statewide smoking bans. In addition, these three ...

Robbins RA

2014-04-01

55

Estuaries, sediments and shorebirds 1: determinants of the intertidal sediments of estuaries  

International Nuclear Information System (INIS)

Tidal energy barrages could affect estuarine ecosystems to varying degrees. Of particular concern are the possible effects that such schemes might have on the dozen or so shorebird species that use British estuaries in large numbers on passage, in autumn and spring, and during the winter. The objectives of the research described in this report were to survey the intertidal sediment composition of a sample of contrasting British estuaries; quantify variables measuring the estuary size, shape, shore width and tidal range, together with position and exposure to gales of individual areas within each estuary; to develop equations which relate the sediment composition of an entire estuary, and areas within it, to these variables. (author)

1996-01-01

56

Tidal currents assessment in the Tagus estuary  

Energy Technology Data Exchange (ETDEWEB)

The authors present in this paper the results of an initial assessment of the potential of tidal currents to generate energy in the Tagus estuary. The work is divided into three phases. The first phase comprises the setting up and calibration of a detailed finite element model for the estuary starting in the ocean boundary. The model was calibrated and verified using water levels and current velocities for several measuring stations within the estuary. The measuring campaign took place in 1987 and was performed by Instituto Hidrografico of the Portuguese Navy. The records are of good quality and cover a period of spring and neap tides. The model give clear indication about the flow pattern within the estuary showing the places were high current velocities are likely to occur. Calculation of the tidal power on selected locations was made. The second phase consisted on the study of the requirements of tidal turbines in terms of site conditions: mainly the minimum water depth and current velocity required for installation. In addition a review was made to understand the development of tidal turbine technology. Three types of turbines were selected as having potential for the site, which usually are associated with moderate current velocity. The third and final phase was the study of the estuary 'map-use' through the construction of a GIS system that allows the identification of locations of potential conflict.

Mendonca, A. (CEHIDRO, Instituto Superior Tecnico, Av. Rovisco Pais, Lisboa, (PT)); Trigo Teixeira, A. (Department of Civil Engineering and Architecture, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, Lisboa (PT))

2007-07-01

57

Heat and Drought Kills Trees in Southwest  

Science.gov (United States)

... Southwest was caused by higher atmospheric temperatures combined with drought and lowered pest ... in northern N.M. They measured moisture and temperature of the location and used satellites to ...

58

Academic Library Instruction in the Southwest.  

Science.gov (United States)

The purpose of this directory is to acquaint Southwest academic librarians with current library instruction programs and activities in academic libraries in their region, and to encourage regional cooperation in sharing ideas and materials. Information li...

A. Brooke

1976-01-01

59

Southwest residential experiment station: the second year  

Energy Technology Data Exchange (ETDEWEB)

The Southwest Residential Experiment Station (SW RES) is in its second year of a multiyear program to develop, test, and evaluate utility-interactive residential photovoltaic (PV) systems. Results of all SW RES functions to date are documented.

Schaefer, J.F.; Zwibel, H.S.

1982-01-01

60

Estuary wader capacity following severe weather mortality  

International Nuclear Information System (INIS)

The building of a tidal power barrage across an estuary may lead to substantial changes in its ecology. Many of Britain's estuaries hold internationally important numbers of waders. Careful consideration, therefore, needs to be given to the likely effects of tidal power barrages on wader populations. The opportunity for increased understanding of the mechanisms which govern wader populations was provided by a period of severe winter weather in 1991, which resulted in a substantial mortality of waders in eastern England. Such conditions are known to be stressful to birds and the study objectives were to investigate both the effects of and recovery from severe weather. (author)

1993-01-01

 
 
 
 
61

Relocation of the Yellow River estuary in 1855 AD recorded in the sediment core from the northern Yellow Sea  

Science.gov (United States)

Relocation of the Yellow River estuary has significant impacts on not only terrestrial environment and human activities, but also sedimentary and ecological environments in coastal seas. The responses of regional geochemical characteristics to the relocation event, however, have not been well studied. In the present study, we performed detailed geochemical elemental analyses of a sediment core from the northern Yellow Sea and studied their geochemical responses to the 1855 AD relocation of the Yellow River estuary. The results show that TOC/TN, Co/Al2O3, Cr/Al2O3, Ni/Al2O3 and Se/Al2O3 ratios all decreased abruptly after 1855 AD, and similar decreases are observed in the sediments of the mud area southwest off the Cheju Island. These abrupt changes are very likely caused by the changes in source materials due to the relocation of the Yellow River estuary from the southern Yellow Sea to the Bohai Sea, which the corresponding decreasing trends caused by the changes in main source materials from those transported by the Liaohe River, the Haihe River and the Luanhe River to those by the Yellow River. Because the events have precise ages recorded in historical archives, these obvious changes in elemental geochemistry of sediments can be used to calibrate age models of related coastal sea sediments.

Zhou, Xin; Jia, Nan; Cheng, Wenhan; Wang, Yuhong; Sun, Liguang

2013-12-01

62

Numerical modeling of oil spill in the Patos Lagoon estuary; Modelagem numerica de derrames de oleo no estuario da Lagoa dos Patos  

Energy Technology Data Exchange (ETDEWEB)

Navigation is responsible for the input of 555.000 tons of oil per year in the marine environment. The recovery of the system can take dozens of years, affecting economical, ecological and social areas. The Patos Lagoon estuary presents wide importance and high susceptibility to accidents of oil spill. Therefore, the objective of this study is to analyze the spread of oil spills using the MOHID model, which simulates both the hydrodynamics of the estuary and the oil dispersion considering the different processes involved. Wind and water level data from May 1 to August 18, 1999 were used to simulate a hypothetic accident of involving 2000 m3 of oil MF 380 during the passage of a cold front considering high and low river discharges. Results indicate that the oil dispersion is governed by the estuarine dynamic, which is controlled by the wind action and river discharge. Thus, during southwest wind the oil is retained within the estuary, and in situations of northeast wind the oil tends to leave the estuary and sometimes can reach the inner shallow bays. (author)

Martinho, Vivian; Monteiro, Igor Oliveira; Janeiro, Joao; Fernandes, Elisa Helena Leao [Fundacao Universidade do Rio Grande (FURG), RS (Brazil)

2008-07-01

63

Fisheries oceanography of the southeast bering sea: Relationships of growth, dispersion and mortality of sand lance larvae to environmental conditions in the port moller estuary. Final report  

Energy Technology Data Exchange (ETDEWEB)

The objective of the study was to describe the early life history of Pacific sand lance, Ammodytes hexapterus, in the southeastern Bering Sea so as to assess the potential impact of oil and gas development in the area of forage fishes. A fisheries oceanography program in the Port Moller estuary from April to July, 1990, collected 473 samples of ichthyoplankton. Analysis of these samples showed that three waves of adult Pacific sand lance entered the Port Moller estuary from mid-January to late May, 1990, and laid their eggs on sand banks in the shallow, well-mixed outer portion of the estuary. After an incubation period of 41 to 63 days, newly-hatched larvae moved at an average speed of about .3 km/day towards a fjord-like basin in upper Herendeen Bay about 20 km southwest of the center of hatch. The basin develops a spring-summer zooplankton community with greater biomass than any other part of the estuary. The fate of the stock depends on maintenance of undisturbed spawning beds and a productive larval rearing area.

McGurk, M.D.; Warburton, H.D.

1992-05-01

64

The composition of lignin in estuarine suspended particulates and the distribution of particulate lignin in estuaries as determined by capillary gas chromatography of cupric oxide oxidation products  

Science.gov (United States)

The contribution of lignin to the estuarine suspended particulate fraction is described in terms of its distribution over a spring tide and a neap tide in the Tamar Estuary, Southwest England and the Mersey Estuary, Northwest England. Suspended particulate samples are treated with CuO?NaOH at 170°C to yield simple, lignin-derived phenolic compounds, which are separated, derived and quantified by capillary gas chromatography with flame ionization detection (GC-FID). Estuarine distributions of particulate lignin are described and the sources and compositional changes of the lignin identified. Comparison of the lignin concentrations in the suspended material with those in the underlying sediment reveals that lignin is preferentially enriched in the suspended material.

Reeves, A. D.; Preston, M. R.

1989-12-01

65

[Medway and Swale Estuary Final.pdf  

…number of scheduled millitary defence structures in the estuary. On the northern point of the Isle of Sheppy is the major port of Sheerness, managed by Peel Ports. Two large power stations are present on the Hoo Peninsula, including Grain Power Station as well as a Liquid Natural Gas (LNG) Terminal. There…

66

THE ECOLOGICAL CONDITION OF VERACRUZ, MEXICO ESTUARIES  

Science.gov (United States)

During June and July, 2002, forty-seven stations were sampled within estuaries along the gulf coast of the state of Veracruz, MX, using a probabilistic survey design and a common set of response indicators. The objective of the study was to collect information to assess the condi...

67

TIDAL WETLAND RESTORATION, CAMEL ESTUARY, CORNWALL  

…meanders, which were then filled and the land levelled. Since then it has been increasingly intensively managed for agriculture. Picture 4 - 1947 aerial photograph showing Clapper Marshes with the tidal creek system evident. Photo provided by Cornwall Council. The upper Camel estuary was identified as having…

68

Padilla Bay: The Estuary Guide. Level 2.  

Science.gov (United States)

Estuaries are marine systems that serve as nurseries for animals, links in the migratory pathways, and habitat for a complex community of organisms. This curriculum guide intended for use at the middle school level is designed for use with the on-site program developed by the Padilla Bay National Esturine Research Reserve (Washington). The guide…

Friesem, Judy; Lynn, Valerie, Ed.

69

BCG Approaches for Improved Management of Estuaries  

Science.gov (United States)

Estuaries and other complex aquatic systems are exposed to a variety of stressors that act at several scales, but are managed piecemeal - - often resulting in a ?death by 1000 cuts? caused by cumulative impacts to these valued resources. To address this, managers need tools that...

70

Thames Estuary 2100 Plan strategic environmental assessment  

The TE2100 Plan sets out the strategic direction for managing flood risk in the Thames estuary to the end of the century and beyond. It sets out how we will continue to protect 1.25 million people and £200 billion worth of property from tidal flood risk.

71

Radiological assessment of the Esk Estuary  

International Nuclear Information System (INIS)

An assessment has been carried out of the radiological impact of artificial radionuclides in the Esk estuary in Cumbria, UK. Measurements were made of the distributions of 137Cs, 239+240Pu, and 241Am in water, surface bed sediments and core profiles. The highest measured concentrations in surface sediments were 2.8 Bq g-1 of 137Cs, 3.1 Bq g-1 of 239+240Pu and 4.7 Bq g-1 of 241Am. These values represent significant decreases from similar measurements made in 1970-1980. The measured behaviour of the actinides in low salinity water at the head of the estuary supports previous observations of actinide remobilisation from the bed. A model has been developed which simulates the long-term behaviour of radioactivity in the estuary. The model incorporates representations of tidal mixing, sediment transport, seasonal and long-term sediment accretion. The model also represents long-term build-up in salt marsh regions. The model gives good agreement with measured distributions of 137Cs, but tends to underestimate actinide concentrations by factors of 2-3. Dose calculations show the importance of radionuclide uptake through livestock grazing sea-washed pasture alongside the estuary. 137Cs and 241Am are identified as the most important radionuclides considered in the assessment. (Author)

1993-01-01

72

[Medway and Swale Estuary Final.pdf  

…in the estuary. On the northern point of the Isle of Sheppy is the major port of Sheerness, managed by Peel Ports. Two large power stations are present on the Hoo Peninsula, including Grain Power Station as well as a Liquid Natural Gas (LNG) Terminal. There is also a fishing and shellfish industry in…

73

Predicting Bankfull Discharge in Ungauged Estuaries by Explaining the Physical Relation Between the Morphology and Hydrology of Estuaries  

Science.gov (United States)

River discharge is a very important parameter in morphological and hydrodynamic studies of estuaries. However, it is always difficult to accurately measure river discharge, and in particular the bankfull discharge in estuaries where the tidal discharge dominates over river discharge. Until today, little research has been done in finding a simple and useful approach to estimate the river discharge in the tidal region, and most of the previous studies focused on the river regime. In this study, we found that there appear to be empirical relations that link together the morphology and hydrology of estuaries, which can be used to estimate river discharge with the least amount of data available. The aims of this study are: 1) to discover the physical explanation for the empirical relation that exists between geometrical characteristics of estuaries and the bankfull flood discharge; and 2) to estimate bankfull discharge in estuaries from the relationship. The physical connection between the estuaries and river regime is found by incorporating the estuary shape analysis and tidal dynamic analysis to Lacey's hydraulic geometry theory. Relationship between the estuary depth and the bankfull river discharge has been analyzed in 19 estuaries around the world (with 9 recently surveyed estuaries). In this study, the discharge data (from gauging station located further upstream) were adjusted by a projection approach to improve the discharge measurement. The outcome of the relationship was compared to Lacey's theory of hydraulic geometry. From the analysis, it shows that the depth of an estuary is a function of the bankfull flood discharge to the power of 1/3 which indicates an agreement with Lacey's formula. With the physical explanation, engineers would be able to estimate flood discharge characteristics from estuary shape indicators. This could be very useful to estimate the flood discharge in ungauged estuaries on the basis of readily available data. In order to verify the accuracy of the relation, existing and new measurement data from estuaries worldwide will be collected and compiled to strengthen the reliability of this finding.

Gisen, J.; Savenije, H.

2013-12-01

74

Nutrient budgets for large Chinese estuaries  

Directory of Open Access Journals (Sweden)

Full Text Available Chinese rivers deliver about 5–10% of global freshwater input and 15–20% of the global continental sediment to the world ocean. We report the riverine fluxes and concentrations of major nutrients (nitrogen, phosphorus, and silicon in the rivers of the contiguous landmass of China and Korea in the northeast Asia. The rivers are generally enriched with dissolved inorganic nitrogen (DIN and depleted in dissolved inorganic phosphate (PO43? with very high DIN: PO43? concentration ratios. DIN, phosphorus, and silicon levels and loads in rivers are mainly affected by agriculture activities and urbanization, anthropogenic activities and adsorption on particulates, and rock types, climate and physical denudation intensity, respectively. Nutrient transports by rivers in the summer are 3–4 times higher than those in the winter with the exception of NH4+. The flux of NH4+ is rather constant throughout the year due to the anthropogenic sources such as the sewer discharge. As nutrient composition has changed in the rivers, ecosystems in estuaries and coastal sea have also changed in recent decades. Among the changes, a shift of limiting nutrients from phosphorus to nitrogen for phytoplankton production with urbanization is noticeable and in some areas silicon becomes the limiting nutrient for diatom productivity. A simple steady-state mass-balance box model was employed to assess nutrient budgets in the estuaries. The major Chinese estuaries export <15% of nitrogen, <6% of phosphorus required for phytoplankton production and ~4% of silicon required for diatom growth in the Chinese Seas (Bohai, Yellow Sea, East China Sea, South China Sea. This suggests that land-derived nutrients are largely confined to the immediate estuaries, and ecosystem in the coastal sea beyond the estuaries is mainly supported by other nutrient sources such as regeneration, open ocean and atmospheric deposition.

S. M. Liu

2009-10-01

75

Nitrogen, Phosphorus, and Suspended Solids Concentrations in Tributaries to the Great Bay Estuary Watershed in 2010. Final Report.  

Science.gov (United States)

Nitrogen, phosphorus, and sediment loads to the Great Bay Estuary are a growing concern. The Piscataqua Region Estuaries Partnership (PREP) calculates the nitrogen load from tributaries to the Great Bay Estuary for its State of the Estuaries reports. Ther...

M. A. Wood P. Trowbridge

2011-01-01

76

76 FR 55673 - Vulnerability Assessments in Support of the Climate Ready Estuaries Program: A Novel Approach...  

Science.gov (United States)

...Assessments in Support of the Climate Ready Estuaries Program: A Novel Approach...Assessments in Support of the Climate Ready Estuaries Program: A Novel Approach...Assessments in Support of the Climate Ready Estuaries Program: A Novel...

2011-09-08

77

Seasonal stratification and property distributions in a tropical estuary (Cochin estuary, west coast, India  

Directory of Open Access Journals (Sweden)

Full Text Available The intratidal, spring-neap and seasonal variations in stratification were examined in Cochin estuary. The observations established a strong connection with the distribution of chemical and biological properties. The influence of tides and river discharge forcing in water column stability was quantified using potential energy anomaly (PEA and stratification parameter. Partially mixed (neap and well-mixed (spring conditions during low river discharge (dry period were altered in monsoon by the salt wedge intrusions. The ecological impact of salt wedge propagation on high tides bringing upwelled water to the system was evident from the bottom hypoxic, high chlorophyll a and nutrient-rich conditions. Phosphate and nitrite concentrations were higher at the bottom saline conditions but silicate and nitrate were clearly supplied by river water. However, during ebb tide this front was driven out of the estuary. The periodic advance and retreat of the salt wedge was inevitable in making the system immune from extended hypoxia/anoxia and maintaining the health of Cochin estuary. For the seasonally varying river flow in the estuary, salt intrusion receded with increasing river flow in monsoon and rebounded with decreasing river flow in dry season. During monsoon, the intense flushing and reduction in salinity field expansion seemed to be responsible for the limited chlorophyll a levels along the surface of Cochin estuary.

A. Shivaprasad

2012-07-01

78

Seasonal stratification and property distributions in a tropical estuary (Cochin estuary, west coast, India  

Directory of Open Access Journals (Sweden)

Full Text Available The intratidal, spring–neap and seasonal variations in stratification were examined in the Cochin estuary. The observations established a strong connection with the distribution of chemical and biological properties. The influence of tides and river discharge forcing in water column stability was quantified using potential energy anomaly (PEA and stratification parameter. Partially mixed (neap and well-mixed (spring conditions during low river discharge (dry period were altered in monsoon by the salt wedge intrusions. The ecological impact of salt wedge propagation on high tides bringing upwelled water to the system was evident from the bottom hypoxic, high chlorophyll a and nutrient-rich conditions. Phosphate and nitrite concentrations were higher at the bottom saline conditions but silicate and nitrate were clearly supplied by river water. However, during ebb tide this front was driven out of the estuary. The periodic advance and retreat of the salt wedge was inevitable in making the system immune from extended hypoxia/anoxia and maintaining the health of the Cochin estuary. For the seasonally varying river flow in the estuary, salt intrusion receded with increasing river flow in monsoon and rebounded with decreasing river flow in dry season. During monsoon, the intense flushing and reduction in salinity field expansion seemed to be responsible for the limited chlorophyll a levels along the surface of the Cochin estuary.

A. Shivaprasad

2013-01-01

79

Hydrodynamical and biogeochemical modeling study of Sado estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Sado estuary is located in the surrounding area of an important Portuguese natural park (Arrábida Natural Park) near the city of Setúbal. The low freshwater discharge from Sado River, the mesotidal tide along the estuary and the strong currents observed turn the estuary a well?mixed system, controlling the estuarine residence time, and therefore determining the patterns of conservative and nonconservative tracers. The salt dynamics inside this kind of system is very imp...

Rosa, Mo?nica Sofia Soares

2010-01-01

80

Relation between tidal damping and wave celerity in estuaries:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Observations in estuaries indicate that an amplified tidal wave moves considerably faster than is indicated by the classical equation for wave propagation. Similarly, the celerity of propagation is lower if the tidal wave is damped. This phenomenon is clearly observed in the Schelde estuary (located in the Netherlands and Belgium) and in the Incomati estuary in Mozambique. In the Incomati, the tidal wave is damped throughout, whereas in the Schelde the tidal range increases from the mouth unt...

Savenije, H. H. G.; Veling, E. J. M.

2005-01-01

 
 
 
 
81

Estuaries, sediments and shorebirds 2: shorebird usage of intertidal areas  

International Nuclear Information System (INIS)

The United Kingdom has some of the most promising sites in Western Europe for tidal energy barrage schemes, however their acceptability will partly depend on longer term environmental effects particularly on estuarine ecosystems. Estuaries around the British Isles support internationally important waterfowl populations, which could be affected by possible future barrage schemes. Three linked projects have been funded under the DTI's tidal energy generic environmental programme to develop a predictive methodology for correlating estuary bird populations to sediments. This study summarises bird usage in a sample of 27 estuaries and relates communities of waterfowl on estuaries to a suite of environmental and sediment cover variables. (author)

1996-01-01

82

Marine geology of the St. Lawrence Estuary  

Science.gov (United States)

The St. Lawrence Estuary, Eastern Canada, contains a very thick (>450 m) Quaternary sedimentary sequence. The results from recently conducted geophysical surveys in conjunction with piston coring indicate that these sediments were deposited under very high sedimentation rates, sometimes as high as ~30 m/ka during the last deglaciation. Results also reveal evidence of large submarine landslides during the Holocene, changes in sedimentation rates and the significant role of submarine canyons and channels to transfer sediments from the coast to the deeper marine environment. Finally, this paper highlights the presence of more than 1900 pockmarks on the seafloor of the St. Lawrence Estuary and discusses their possible origins: active hydrocarbon seeps in the Laurentian Channel and biogenic gas seepage on the northwestern shoulder of the Laurentian Channel.

St-Onge, Guillaume; Duchesne, Mathieu J.; Lajeunesse, Patrick

2011-05-01

83

Marine geology of the St. Lawrence Estuary  

International Nuclear Information System (INIS)

The St. Lawrence Estuary, Eastern Canada, contains a very thick (>450 m) Quaternary sedimentary sequence. The results from recently conducted geophysical surveys in conjunction with piston coring indicate that these sediments were deposited under very high sedimentation rates, sometimes as high as ?30 m/ka during the last deglaciation. Results also reveal evidence of large submarine landslides during the Holocene, changes in sedimentation rates and the significant role of submarine canyons and channels to transfer sediments from the coast to the deeper marine environment. Finally, this paper highlights the presence of more than 1900 pockmarks on the seafloor of the St. Lawrence Estuary and discusses their possible origins: active hydrocarbon seeps in the Laurentian Channel and biogenic gas seepage on the northwestern shoulder of the Laurentian Channel.

2011-05-01

84

Marine geology of the St. Lawrence Estuary  

Energy Technology Data Exchange (ETDEWEB)

The St. Lawrence Estuary, Eastern Canada, contains a very thick (>450 m) Quaternary sedimentary sequence. The results from recently conducted geophysical surveys in conjunction with piston coring indicate that these sediments were deposited under very high sedimentation rates, sometimes as high as {approx}30 m/ka during the last deglaciation. Results also reveal evidence of large submarine landslides during the Holocene, changes in sedimentation rates and the significant role of submarine canyons and channels to transfer sediments from the coast to the deeper marine environment. Finally, this paper highlights the presence of more than 1900 pockmarks on the seafloor of the St. Lawrence Estuary and discusses their possible origins: active hydrocarbon seeps in the Laurentian Channel and biogenic gas seepage on the northwestern shoulder of the Laurentian Channel.

St-Onge, Guillaume [Canada Research Chair in Marine Geology, Institut des sciences de la mer de Rimouski (ISMER) and GEOTOP Research Center, 310 allee des Ursulines, Rimouski, Quebec, G5L 3A1 (Canada); Duchesne, Mathieu J [Geological Survey of Canada, Quebec Division, 490 de la Couronne, Quebec City, Quebec, G1K 9A9 (Canada); Lajeunesse, Patrick, E-mail: guillaume_st-onge@uqar.qc.ca [Departement de geographie and Centre d' etudes nordiques, Universite Laval, Quebec City, Quebec, G1V 0A6 (Canada)

2011-05-15

85

Southwest residential experiment station: the first year  

Energy Technology Data Exchange (ETDEWEB)

The Southwest Residential Experiment Station (SW RES) is part of the Department of Energy's National Photovoltaic Program aimed at the residential applications sector. The SW RES is currently erecting 8 of a planned 15 prototype residence-like photovoltaic systems. The first year's history and the current status are presented. Other current and planned hardware systems are discussed.

Schaefer, J.; Zwibel, H.

1981-01-01

86

Southwest Regional Partnership on Carbon Sequestration  

Energy Technology Data Exchange (ETDEWEB)

The Southwest Partnership on Carbon Sequestration completed its Phase I program in December 2005. The main objective of the Southwest Partnership Phase I project was to evaluate and demonstrate the means for achieving an 18% reduction in carbon intensity by 2012. Many other goals were accomplished on the way to this objective, including (1) analysis of CO{sub 2} storage options in the region, including characterization of storage capacities and transportation options, (2) analysis and summary of CO{sub 2} sources, (3) analysis and summary of CO{sub 2} separation and capture technologies employed in the region, (4) evaluation and ranking of the most appropriate sequestration technologies for capture and storage of CO{sub 2} in the Southwest Region, (5) dissemination of existing regulatory/permitting requirements, and (6) assessing and initiating public knowledge and acceptance of possible sequestration approaches. Results of the Southwest Partnership's Phase I evaluation suggested that the most convenient and practical ''first opportunities'' for sequestration would lie along existing CO{sub 2} pipelines in the region. Action plans for six Phase II validation tests in the region were developed, with a portfolio that includes four geologic pilot tests distributed among Utah, New Mexico, and Texas. The Partnership will also conduct a regional terrestrial sequestration pilot program focusing on improved terrestrial MMV methods and reporting approaches specific for the Southwest region. The sixth and final validation test consists of a local-scale terrestrial pilot involving restoration of riparian lands for sequestration purposes. The validation test will use desalinated waters produced from one of the geologic pilot tests. The Southwest Regional Partnership comprises a large, diverse group of expert organizations and individuals specializing in carbon sequestration science and engineering, as well as public policy and outreach. These partners include 21 state government agencies and universities, five major electric utility companies, seven oil, gas and coal companies, three federal agencies, the Navajo Nation, several NGOs, and the Western Governors Association. This group is continuing its work in the Phase II Validation Program, slated to conclude in 2009.

Brian McPherson

2006-03-31

87

Eelgrass Distribution in the Great Bay Estuary 2008. Final Report.  

Science.gov (United States)

Eelgrass in the Great Bay Estuary in 2008 was found only in the Great Bay itself and Portsmouth Harbor. In 2008 there was a continued loss of eelgrass biomass in the Estuary. Virtually all the eelgrass in Little Bay and the Piscataqua River has died. Eelg...

F. Short

2009-01-01

88

Fish assemblage structure in relation to environmental conditions in a tropical estuary / Ensamblaje estructural de peces en relación a las condiciones ambientales en un estuario tropical  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in spanish La estructura de la comunidad de peces del estero de Sabancuy, México, fue analizada durante 2 temporadas climáticas usando datos de abundancia, biomasa y de 14 parámetros ambientales. No se encontraron diferencias estadísticamente significativas entre los datos obtenidos en las 2 estaciones climáti [...] cas. En el estuario se definieron 2 zonas ambientales, una que se extiende desde el sureste hasta el puente de Sabancuy y la otra desde ese sitio hasta la cabeza del estuario. Se registraron un total de 32 especies de peces representando a 21 familias. Las familias más abundantes fueron: Gerridae, Sciaenidae, Sparidae, Lutjanidae y Ciprinodontidae. La diversidad fue alta en el centro de la laguna. La clasificación comunitaria dió como resultado 3 ensamblajes con diferencias notables en la distribución espacial. Una muestra la influencia de la comunicación del estuario con la laguna de Términos, la segunda muestra la cabeza del estuario y la tercera una zona transicional cerca del puente que divide al estuario. La organización ecológica del estuario estuvo dividida en 2 áreas por el puente, con relativa escasez de hábitats y alimento y una consecuente pobreza de especies en los 2 extremos. La concentración de fosfato tiene la mayor influencia en el ensamblaje de la comunidad de peces. Abstract in english Fish community in Sabancuy Estuary, Mexico, was analyzed during 2 a dry and a rainy seasons using 14 environmental parameters and fish species abundance and biomass data. No significant differences in data were observed between seasons. Two environmental zones were defined within the estuary, one ex [...] tending southwest from a bridge and the other northeast from the bridge to the estuary head. A total of 21 fish families and 32 species were recorded. The most abundant families were Gerridae, Sciaenidae, Sparidae, Lutjanidae and Ciprinodontidae. Diversity was high in the central lagoon. Fish community classification resulted in 3 assemblages with notable differences in spatial distribution. One was influenced by estuary communication with Terminos Lagoon, a second was at the estuary head and a third at the transitional zone near the bridge dividing the estuary. Ecological organization of the Estuary was divided into 2 areas by the bridge, with relative habitat and food resource scarcity and consequent species paucity at the 2 extremes. Phosphate concentrations had the most influence on fish community assemblage.

Alicia, González-Solis; Daniel, Torruco.

89

Distribution of U-Th nuclides in the riverine and coastal environments of the tropical southwest coast of India  

International Nuclear Information System (INIS)

A reconnaissance study has been made on the distribution of 238U, 234U, 232Th and 230Th in soils, water, suspended particulate matter (SPM) and bottom sediments in the Kali river basin around Kaiga, its estuarine region and the adjacent Arabian Sea to obtain the baseline data of U-Th series nuclides in view of the commissioning of nuclear power reactors at Kaiga, near Karwar, on the southwest coast of India. Drainage basin soils developed over greywackes (the dominant litho-unit upstream) are lower in 238U/Al and 232Th/Al ratios by factors of 3-5 in comparison with those developed over tonalitic gneisses (the dominant litho-unit downstream). The dominance of the former type of soils is reflected in the composition of river-bottom sediments derived from the upstream drainage basin during the monsoon. The 232Th in bottom sediments tends to increase towards the estuarine and coastal areas, presumably due to deposition of heavy minerals and onshore transport of coastal sediments into the estuary. The dissolved U in the Kali river is low (0.001-0.02 ?g/l) when compared to the major Indian rivers as the Kali river flows through U-poor greywackes. Thus, the input of dissolved U to the Kali estuary is dominated by sea water. Although there is some evidence for the removal of dissolved U at low salinity during estuarine mixing, its behaviour is conservative in the lower estuary (at higher salinities). The removal rate of dissolved U from the Kali river basin is similar to that reported from other tropical river basins. The U flux from all the west-flowing rivers of Peninsular India is estimated at 26.3x106 g/yr to the Arabian Sea which is about 2% of the flux from the Himalayan rivers to the Bay of Bengal

2001-06-01

90

An analytical solution for tidal propagation in the Yangtze Estuary, China :  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An analytical model for tidal dynamics has been applied to the Yangtze Estuary for the first time, to describe the tidal propagation in this large and typically branched estuary with three-order branches and four outlets to the sea. This study shows that the analytical model developed for a single-channel estuary can also accurately describe the tidal dynamics in a branched estuary, particularly in the downstream part. Within the same estuary system, the North Branch and the South Branches ha...

2012-01-01

91

Radiological assessment of the Ribble Estuary - 3. Redistribution of radionuclides  

Energy Technology Data Exchange (ETDEWEB)

The Ribble Estuary in the UK is contaminated by radionuclides derived from BNFL Sellafield and Springfield. Following the temporary shutdown of the Springfields plant, beta dose and gamma air kerma rates were measured at a range of sites in the estuary. Sediment surface samples were analysed for {sup 137}Cs, {sup 234m}Pa, {sup 234}Th and {sup 241}Am activity concentrations by gamma spectrometry, {sup 230}Th and Pu isotopes by alpha spectrometry and sediment grain size (percentage < 63 {mu}m) by wet sieving. Temporal variations in Springfields-derived radionuclides are explained by variations in discharges by radionuclides and the distribution of fine grained sediments in the estuary which is controlled mainly by the spring-neap tidal cycle and river runoff. Radionuclide dynamics, modelling variations in the {sup 234}Th/{sup 137}Cs activity concentration ratio and calculating environmental beta dose rate and {sup 234}Th half-lives allow the estuary to be split into three areas: (a) upper estuary where fine grained sediments tend to be deposited during periods of low and average river flow; (b) middle reaches of the estuary which encompass most of the main channel sites where fine grained sediments are probably deposited and removed on most tides; (c) outer estuary including large areas of salt marshes which tend to accumulate fine grained sediment. This is confirmed by similar results derived from the {sup 234}Th/{sup 239,240}Pu ratio. (author).

Mudge, S.M.; Assinder, D.J.; Bourne, G.S. [University Coll. of North Wales, Bangor (United Kingdom)

1997-07-01

92

Structure and Function of South-east Australian Estuaries  

Science.gov (United States)

An attempt is made to synthesize the geological properties, water quality attributes and aspects of the ecology of south-east Australian estuaries so as to provide a framework for addressing coastal management issues. The approach is based on the underlying causal factors of geology and morphology and more immediate environmental factors (e.g. salinity and sediments) which are associated with ecological distributions, species richness and fisheries catch. This ' broad brush ' approach seeks to maximize reality and generality, albeit at the expense of precision and local variability in individual circumstances. It disregards small-scale ecological patterns as noise. Unlike in the Northern Hemisphere, conditions in temperate Australia are characterized by irregular flood and fire regimes that strongly influence estuary hydrology and nutrient inputs. Three main types of estuary (tide-dominated, wave-dominated and intermittently closed) are recognized based on geological criteria and having particular entrance conditions that control tidal exchange. Four zones (marine flood-tidal delta, central mud basin, fluvial delta and riverine channel/alluvial plain) are also recognized common to each type of estuary. These zones correspond to mappable sedimentary environments in all estuaries and have characteristic water quality, nutrient cycling/primary productivity signatures and ecosystems. The ecology of a zone is modified by (a) estuary type which determines the salinity regime; (b) stage of sediment filling (evolutionary maturity) which controls the spatial distribution/size of the zones; and (c) impacts of various forms of development. By using the zones/habitats as a common currency among all estuaries, it is possible to link ecological aspects such as species richness and commercial fisheries production so as to compare different estuaries or within-estuary zones.

Roy, P. S.; Williams, R. J.; Jones, A. R.; Yassini, I.; Gibbs, P. J.; Coates, B.; West, R. J.; Scanes, P. R.; Hudson, J. P.; Nichol, S.

2001-09-01

93

Waterfowl migration and distribution in North West estuaries. V. 1  

International Nuclear Information System (INIS)

Waterfowl populations may be affected by proposed tidal barrage across the Mersey. This study had three objectives:-(1) to evaluate the patterns of usage of the intertidal flats of the Mersey estuary by waders and wildfowl and to establish which are the preferred areas; (2) to identify the places of origin and movement patterns of the populations of waders and wildfowl that visit the Mersey Estuary; and (3) to evaluate evidence regarding the capacity of British estuaries to absorb waders and wildfowl populations which might be displaced by a Mersey Barrage. The text and tables and results only are presented in Volume 1. (author)

1990-01-01

94

Seasonal Patterns in the Fish and Crustacean Community of a Turbid Temperate Estuary (Zeeschelde Estuary, Belgium)  

Science.gov (United States)

Fish and crustaceans were sampled for 1 year in the upper reaches of a temperate estuary characterized by high turbidity and a tidal range of up to 5 m. Samples were taken in the cooling-water circuit of the Doel Nuclear Power station (Zeeschelde, Belgium). Between July 1994 and June 1995, 55 fish species, two shrimp species and four crab species were recorded. The fish community was composed of 36 marine species, 16 freshwater species and three diadromous species. Shrimps, Gobiidae and Clupeidae dominated the samples both in numbers and biomass. An exceptionally clear seasonal succession was observed in the species composition. It is argued that young fish and crustaceans use the highly turbid Zeeschelde Estuary as a refuge from predators.

Maes, J.; Taillieu, A.; Van Damme, P. A.; Cottenie, K.; Ollevier, F.

1998-08-01

95

Environmental modulation of the plankton community composition and size-structure along the eutrophic intertidal coast of the Río de La Plata estuary, Argentina  

Directory of Open Access Journals (Sweden)

Full Text Available In this study we investigated the spatial distribution of the plankton community, bacterio-, phyto- and zooplankton, in relation with environmental conditions along the intertidal coast of the Río de la Plata estuary, Argentina. Plankton was analyzed in terms of species composition, abundance, biomass (carbon content and size-structure. We aim to evaluate the potential effects of antrophogenic impacts (e.g., nutrient enrichment[mdg1]  and physicochemical [mdg2] gradients alongshore (e.g., salinity, turbidity on the composition and functioning of the plankton. We asked whether the natural structuring of the plankton by salinity and turbidity, as known in estuaries, is modified by eutrophication along the studied shoreline. We found that the density and biomass of bacteria and phytoplankton were strikingly enhanced by high eutrophication levels along the intertidal southwest coast of the Río de la Plata estuary. We also found that the highest zooplankton density in the most polluted area but the biomass showed a different distribution pattern. Nevertheless, when zooplankton was analyzed by means of its size fraction, we accordingly found that the microzooplankton biomass was positively associated with smaller-size phytoplankton groups and the most polluted study sites. Copepods were the major taxonomic groups that best represented the mesozooplankton biomass. We therefore expected that its distribution was modulated by the presence of its food items (i.e., large cells which, in turn, were more abundant in the middle-outer zone. In contrast, we found that the highest biomass of copepods occurred at the innermost site of the estuary and we found no significant association with other planktonic groups. Overall, this study highlights the noteworthy impacts of human activities modifying the functioning of this coastal ecosystem. The differences found in the taxonomic composition and size structure of the planktonic community assemblage between the most polluted and less polluted sites constitutes an excellent baseline for considering plankton as ecological an indicator of water quality.

Maximiliano D. Garcia

2014-02-01

96

Mobility of contaminants in relation to dredging operations in a mesotidal estuary (Tagus Estuary, Portugal)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

During the construction of a New Bridge over the Tagus estuary 2.5 million tons of sediments were dredged, part of this quantity being contaminated material. The extension and intensity of the water turbidity associated with dredging operating varied with the tidal conditions but the resuspended material collected near the bucket dredger did not present a concentration increment in metals and PCB, when compared to the estuarine suspended sediments. The calculated distribution coefficients sug...

Vale, Carlos; Ferreira, Ana; Micaelo, Cristina; Caetano, Miguel; Pereira, Eduarda; Madureira, Maria J.; Ramalhosa, Elsa

1998-01-01

97

Distribution of alkyl lead species in the Mersey Estuary  

Energy Technology Data Exchange (ETDEWEB)

Differential pulse anodic stripping voltametry has been used to study the distribution of dissolved inorganic lead, and di- and tri-alkyl lead species in the Mersey Estuary and the Manchester Ship Canal. At all stations seawards of the point of discharge into the estuary the total concentration of alkyl lead was 5-10 times that of dissolved inorganic lead. In general, di-alkyl lead constituted about one-tenth of the total alkyl lead. The total alkyl lead concentration behaves conservatively in the estuary, in line with the stability and low adsorbability of these compounds. In contrast, inorganic lead shows a strongly non-conservative behavior. Concentrations of total alkyl lead in the Ship Canal are much higher than those in the estuary reaching as high as approx.100 ..mu..gl/sup -1/ near the outfall. 18 references, 10 figures, 1 table.

Riley, J.P.; Towner, J.V.

1984-01-01

98

HIGH CYANOBACTERIAL ABUNDANCE IN GULF OF MEXICO ESTUARIES  

Science.gov (United States)

Aquatic phytoplankton comprise a wide variety of taxa spanning more than 2 orders of magnitude in size, yet studies of estuarine phytoplankton often overlook the picoplankton, particularly chroococcoid cyanobacteria (c.f. Synechocococcus). Three Gulf of Mexico estuaries (Apalachi...

99

Oysters return to the Tagus estuary through an ecological model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aquaculture is an activity that has been increasing along the last years. Until the 1970’s Portugal and more specifically the Tagus estuary, was the major exporter of oysters in Europe. Factors like TBT and

Bento, Va?nia Sofia Oliveira

2008-01-01

100

Assessing the Impact of Human Activities on British Columbia's Estuaries  

Science.gov (United States)

The world’s marine and coastal ecosystems are under threat and single-sector management efforts have failed to address those threats. Scientific consensus suggests that management should evolve to focus on ecosystems and their human, ecological, and physical components. Estuaries are recognized globally as one of the world’s most productive and most threatened ecosystems and many estuarine areas in British Columbia (BC) have been lost or degraded. To help prioritize activities and areas for regional management efforts, spatial information on human activities that adversely affect BC’s estuaries was compiled. Using statistical analyses, estuaries were assigned to groups facing related threats that could benefit from similar management. The results show that estuaries in the most populated marine ecosections have the highest biological importance but also the highest impacts and the lowest levels of protection. This research is timely, as it will inform ongoing marine planning, land acquisition, and stewardship efforts in BC.

Robb, Carolyn K.

2014-01-01

 
 
 
 
101

Habitat Scale Mapping of Fisheries Ecosystem Service Values in Estuaries  

Directory of Open Access Journals (Sweden)

Full Text Available Little is known about the variability of ecosystem service values at spatial scales most relevant to local decision makers. Competing definitions of ecosystem services, the paucity of ecological and economic information, and the lack of standardization in methodology are major obstacles to applying the ecosystem-services approach at the estuary scale. We present a standardized method that combines habitat maps and habitat–faunal associations to estimate ecosystem service values for recreational and commercial fisheries in estuaries. Three case studies in estuaries on the U.S. west coast (Yaquina Bay, Oregon, east coast (Lagoon Pond, Massachusetts, and the Gulf of Mexico (Weeks Bay, Alabama are presented to illustrate our method’s rigor and limitations using available data. The resulting spatially explicit maps of fisheries ecosystem service values show within and between estuary variations in the value of estuarine habitat types that can be used to make better informed resource-management decisions.

Steve J. Jordan

2010-12-01

102

A PROBABILISTIC SURVEY OF SEDIMENT TOXICITY IN WEST COAST ESTUARIES  

Science.gov (United States)

A probabalistic survey of coastal condition assessment was conducted in 1999 by participants in US EPA's Environmental Monitoring and Assessment Program (EMAP). The survey targeted estuaries along the outer coasts of Washington, Oregon and California, including the lower Columbi...

103

Distribution of Th-232 and Th-228 in Santos and Sao Vicente Estuary, Sao Paulo, Brazil  

Energy Technology Data Exchange (ETDEWEB)

In the last decades considerable attention has been given to technologically enhanced natural occurring radioactive material (TENORM). Within this frame, of particular concern is the phosphate fertilizer industry. Santos Basin, located in Southwest Brazil, Sao Paulo State, comprising Santos and Sao Vicente estuarine system, is considered the most important industrial region of the country. Among the industrial activities present, phosphate fertilizer plants are responsible for the production of 69 millions tons of phosphogypsum waste, which is stockpiled in the surrounding environment. This waste concentrates radionuclides of the natural series originally present in the phosphate rock used as raw material. This study aims to evaluate the environmental impact of such activities in the sediments of the estuarine system. {sup 232} Th and {sup 228} Th concentrations in Santos and San Vicente estuary sediments were determined by Neutron activation analysis and Gamma spectrometry, respectively. {sup 232} Th concentration ranged from 6.5 to 198 Bq kg{sup -1} with mean value of 57 {+-} 39 Bq kg{sup -1}, for 42 samples. {sup 228} Th content varied from 12 to 110 Bq kg{sup -1} with a mean value of 74 {+-} 23 Bq kg{sup -1}, for 18 samples. It can be seen that the amount of {sup 232} Th is higher in the rivers close to the phosphogypsum piles, at least five points were identified as being affected by anthropogenic factor. (Author)

Silva, P.S.C.; Mazzilli, B.P.; Favaro, D.I.T. [Instituto de Pesquisas Energeticas e Nucleares, Av. Lineu Prestes, 2242, Caixa Postal 05508-000, Cidade Universitaria, Sao Paulo (Brazil)]. e-mail: Pscsilva@ipen.br

2004-07-01

104

Distribution of Th-232 and Th-228 in Santos and Sao Vicente Estuary, Sao Paulo, Brazil  

International Nuclear Information System (INIS)

In the last decades considerable attention has been given to technologically enhanced natural occurring radioactive material (TENORM). Within this frame, of particular concern is the phosphate fertilizer industry. Santos Basin, located in Southwest Brazil, Sao Paulo State, comprising Santos and Sao Vicente estuarine system, is considered the most important industrial region of the country. Among the industrial activities present, phosphate fertilizer plants are responsible for the production of 69 millions tons of phosphogypsum waste, which is stockpiled in the surrounding environment. This waste concentrates radionuclides of the natural series originally present in the phosphate rock used as raw material. This study aims to evaluate the environmental impact of such activities in the sediments of the estuarine system. 232 Th and 228 Th concentrations in Santos and San Vicente estuary sediments were determined by Neutron activation analysis and Gamma spectrometry, respectively. 232 Th concentration ranged from 6.5 to 198 Bq kg-1 with mean value of 57 ± 39 Bq kg-1, for 42 samples. 228 Th content varied from 12 to 110 Bq kg-1 with a mean value of 74 ± 23 Bq kg-1, for 18 samples. It can be seen that the amount of 232 Th is higher in the rivers close to the phosphogypsum piles, at least five points were identified as being affected by anthropogenic factor. (Author)

2004-07-11

105

Monitoring Radio Frequency Interference in Southwest Virginia  

Science.gov (United States)

The radio signals received from astronomical objects are extremely weak. Because of this, radio sources are easily shrouded by interference from devices such as satellites and cell phone towers. Radio astronomy is very susceptible to this radio frequency interference (RFI). Possibly even worse than complete veiling, weaker interfering signals can contaminate the data collected by radio telescopes, possibly leading astronomers to mistaken interpretations. To help promote student awareness of the connection between radio astronomy and RFI, an inquiry-based science curriculum was developed to allow high school students to determine RFI levels in their communities. The Quiet Skies Project_the result of a collaboration between the National Aeronautics and Space Administration (NASA), the National Science Foundation (NSF), and the National Radio Astronomy Observatory (NRAO)_encourages students to collect and analyze RFI data and develop conclusions as a team. Because the project focuses on electromagnetic radiation, it is appropriate for physics, physical science, chemistry, or general science classes. My class-about 50 students from 15 southwest Virginia high schools-participated in the Quiet Skies Project and were pioneers in the use of the beta version of the Quiet Skies Detector (QSD), which is used to detect RFI. Students have been involved with the project since 2005 and have collected and shared data with NRAO. In analyzing the data they have noted some trends in RFI in Southwest Virginia.

Rapp, Steve

2010-01-01

106

Two-dimensional hydrodynamic model of St. Lucie Estuary  

Energy Technology Data Exchange (ETDEWEB)

A two-dimensional hydrodynamic model of St. Lucie Estuary was developed to assess the impact of drainage canal discharge and storm water runoff. Water surface elevation, two-dimensional velocity field and salinity are collected during 1998--1998 ENSO episode. The data sets cover an eight months period that includes both wet ad dry weather conditions. The model has been applied to St. Lucie Estuary salinity study. It will also provide flow fields to a water quality model.

Hu, G.G.

1999-07-01

107

Nutrient cycling and plant dynamics in estuaries: A brief review  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Eutrophication of European estuaries due to massive nutrient loading from urban areas and diffuse runoff from extensively cultivated land areas is analysed. Consequences for the ecology of estuaries, namely changes in plant species composition, which also affects heterotrophic organisms, are approached based on examples showing that the result is often a fundamental structural change of the ecosystem, from a grazing and/or nutrient controlled stable systems to unstable detritus/mineralisation...

1999-01-01

108

Continuous resistivity profiling data from the Corsica River Estuary, Maryland  

Science.gov (United States)

Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine its importance in nutrient delivery to the Chesapeake Bay. The Corsica River Estuary represents a coastal lowland setting typical of much of the eastern bay. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the lower estuary in April and May 2007. Resource managers are concerned about nutrients that are entering the estuary via SGD that may be contributing to eutrophication, harmful algal blooms, and fish kills. Techniques employed in the study included continuous resistivity profiling (CRP), piezometer sampling of submarine groundwater, and collection of a time series of radon tracer activity in surface water. A CRP system measures electrical resistivity of saturated subestuarine sediments to distinguish those bearing fresh water (high resistivity) from those with saline or brackish pore water (low resistivity). This report describes the collection and processing of CRP data and summarizes the results. Based on a grid of 67.6 kilometers of CRP data, low-salinity (high-resistivity) groundwater extended approximately 50-400 meters offshore from estuary shorelines at depths of 5 to >12 meters below the sediment surface, likely beneath a confining unit. A band of low-resistivity sediment detected along the axis of the estuary indicated the presence of a filled paleochannel containing brackish groundwater. The meandering paleochannel likely incised through the confining unit during periods of lower sea level, allowing the low-salinity groundwater plumes originating from land to mix with brackish subestuarine groundwater along the channel margins and to discharge. A better understanding of the spatial variability and geological controls of submarine groundwater flow beneath the Corsica River Estuary could lead to improved models and mitigation strategies for nutrient over-enrichment in the estuary and in other similar settings.

Cross, V.A.; Bratton, J.F.; Worley, C.R.; Crusius, J.; Kroeger, K.D.

2011-01-01

109

Contamination and restoration of an estuary affected by phosphogypsum releases  

International Nuclear Information System (INIS)

The Huelva Estuary in Huelva, Spain, has been one of the most studied environmental compartments in the past years from the point of view of naturally occurring radioactive material (NORM) releases. It has been historically affected by waste releases, enriched in radionuclides from the U-decay series, from factories located in the area devoted to the production of phosphoric acid and phosphate fertilizers. Nevertheless, changes in national regulations forced a new waste management practice in 1998, prohibiting releases of phosphogypsum into the rivers. The input of natural radionuclides from phosphate factories to rivers was drastically reduced. Because of this there was a unique opportunity for the study of the response of a contaminated environmental compartment, specifically an estuary affected by tidal influences, after the cessation of the contaminant releases to, in this case, the Huelva Estuary (henceforth referred to as the Estuary). To investigate the environmental response to this new discharge regime, the specific activities of radionuclides 226Ra and 210Pb in water and sediment samples collected in four campaigns (from 1999 to 2005) were determined and compared with pre-1998 values. From this study it is possible to infer the most effective mechanisms of decontamination for the Estuary. Decontamination rates of 210Pb and 226Ra in the sediments and water have been calculated using exponential fittings and corresponding half-lives have been deduced from them. The cleaning half-life in the whole area of the Estuary is about 6 and 3.5 years for 226Ra and 210Pb respectively. The observed trend clearly shows that contamination of the Estuary by natural radionuclides is now decreasing and radioactive levels in waters and sediments are approaching the natural background references. This work attempts to evaluate whether it can be expected that the decontamination of the enhanced levels of natural radioactivity in the Estuary can be performed via natural processes.

2009-12-15

110

Contamination and restoration of an estuary affected by phosphogypsum releases  

Energy Technology Data Exchange (ETDEWEB)

The Huelva Estuary in Huelva, Spain, has been one of the most studied environmental compartments in the past years from the point of view of naturally occurring radioactive material (NORM) releases. It has been historically affected by waste releases, enriched in radionuclides from the U-decay series, from factories located in the area devoted to the production of phosphoric acid and phosphate fertilizers. Nevertheless, changes in national regulations forced a new waste management practice in 1998, prohibiting releases of phosphogypsum into the rivers. The input of natural radionuclides from phosphate factories to rivers was drastically reduced. Because of this there was a unique opportunity for the study of the response of a contaminated environmental compartment, specifically an estuary affected by tidal influences, after the cessation of the contaminant releases to, in this case, the Huelva Estuary (henceforth referred to as the Estuary). To investigate the environmental response to this new discharge regime, the specific activities of radionuclides {sup 226}Ra and {sup 210}Pb in water and sediment samples collected in four campaigns (from 1999 to 2005) were determined and compared with pre-1998 values. From this study it is possible to infer the most effective mechanisms of decontamination for the Estuary. Decontamination rates of {sup 210}Pb and {sup 226}Ra in the sediments and water have been calculated using exponential fittings and corresponding half-lives have been deduced from them. The cleaning half-life in the whole area of the Estuary is about 6 and 3.5 years for {sup 226}Ra and {sup 210}Pb respectively. The observed trend clearly shows that contamination of the Estuary by natural radionuclides is now decreasing and radioactive levels in waters and sediments are approaching the natural background references. This work attempts to evaluate whether it can be expected that the decontamination of the enhanced levels of natural radioactivity in the Estuary can be performed via natural processes.

Villa, M., E-mail: mvilla@us.es [Centro de Investigacion, Tecnologia e Innovacion, Universidad de Sevilla CITIUS, Av. Reina Mercedes 4B, E41012-Sevilla (Spain); Mosqueda, F. [Dpto. de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, Campus de El Carmen, 21007-Huelva (Spain); Hurtado, S. [Centro de Investigacion, Tecnologia e Innovacion, Universidad de Sevilla CITIUS, Av. Reina Mercedes 4B, E41012-Sevilla (Spain); Mantero, J.; Manjon, G. [E. T. S. Arquitectura, Universidad de Sevilla, Departamento de Fisica Aplicada II, Av. Reina Mercedes, 2. 41012-Sevilla (Spain); Perianez, R. [E.U.I.T.A., Universidad de Sevilla, Departamento de Fisica Aplicada III, Carretera de Utrera, Km. 1, 41013 Sevilla (Spain); Vaca, F. [Dpto. de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, Campus de El Carmen, 21007-Huelva (Spain); Garcia-Tenorio, R. [E. T. S. Arquitectura, Universidad de Sevilla, Departamento de Fisica Aplicada II, Av. Reina Mercedes, 2. 41012-Sevilla (Spain)

2009-12-15

111

Monitoring Rehabilitation in Temperate North American Estuaries  

Energy Technology Data Exchange (ETDEWEB)

In this chapter, we propose that monitoring rehabilitation in estuarine ecosystems by necessity requires quantifying relationships between dynamic estuarine processes and sensitive indicators of ecosystem function. While we do discuss temperate systems in general, emphasis is placed on anadromous salmon habitats in the Pacific Northwest because anadromous fishes are such a major focus of rehabilitation efforts, and present some of the greater challenges in linking function of one segment of their life history to conditions in a specific habitat. We begin with a basic overview of the ecological and socioeconomic significance of, as well as anthropogenic effects on, estuaries. Next, we briefly summarize the various kinds of estuarine rehabilitation historically practiced in temperate regions, and review estuarine rehabilitation monitoring design and methods, highlighting the unique challenges involved in monitoring estuarine systems. We then close with a summary and conclusions.

Rice, Casimir A.; Hood, W Gregory; Tear, Lucinda M.; Simenstad, Charles; Williams, Gregory D.; Johnson, L. L.; Feist, B. E.; Roni, P.

2005-02-01

112

Radiological assessment of the Ribble Estuary - 3. Redistribution of radionuclides  

International Nuclear Information System (INIS)

The Ribble Estuary in the UK is contaminated by radionuclides derived from BNFL Sellafield and Springfield. Following the temporary shutdown of the Springfields plant, beta dose and gamma air kerma rates were measured at a range of sites in the estuary. Sediment surface samples were analysed for 137Cs, 234mPa, 234Th and 241Am activity concentrations by gamma spectrometry, 230Th and Pu isotopes by alpha spectrometry and sediment grain size (percentage 234Th/137Cs activity concentration ratio and calculating environmental beta dose rate and 234Th half-lives allow the estuary to be split into three areas: (a) upper estuary where fine grained sediments tend to be deposited during periods of low and average river flow; (b) middle reaches of the estuary which encompass most of the main channel sites where fine grained sediments are probably deposited and removed on most tides; (c) outer estuary including large areas of salt marshes which tend to accumulate fine grained sediment. This is confirmed by similar results derived from the 234Th/239,240Pu ratio. (author)

1997-01-01

113

Aging and sediment characteristics of northern Gulf of Mexico estuaries  

Energy Technology Data Exchange (ETDEWEB)

Eight major estuarine systems present along the northern margin of the Gulf of Mexico serve as primary depositional basins for all rivers draining into the gulf from central Louisiana eastward to the Florida peninsula. These estuaries consist of Apalachicola Bay, St. Andrews Bay, Choctawhatchee Bay, Pensacola Bay, Perdido Bay, Mobile Bay, Mississippi sound, and Lake Pontchartrainn. Because each receives sediment from a different river system (or systems), each estuary is characterized by sediments that are both physically and mineralogically distinct. Estuaries in the eastern Gulf, for example, possess a clay mineral suite dominated by kaolinite (derived from deeply weathered piedmont rocks), whereas those from the western Gulf are rich in smectite and mixed layer clays (reflecting a Western Interior or provenance from Paleozoic or older coastal plain sources). Similarly, weathering of rocks in the southern piedmont has provided eastern Gulf estuarine sediments with a suite of largely metamorphic rock-derived heavy minerals, whereas those in the western Gulf contain a mixed suite of both igneous- and metamorphic-derived minerals. Equally distinctive, however, are the textures of the bottom sediments themselves for each estuary when plotted on standard sand-silt-clay ternary diagrams. The relative percentages of these components are uniquely different for most of the estuaries and reflect both natural and anthropogenic conditions that exist in the watershed areas that drain into each estuary.

Isphording, W.C. (Univ. of South Alabama, Mobile (USA)); Imsand, F.D. (Army Corps of Engineers, Mobile, AL (USA)); Flowers, G.C. (Tulane Univ., New Orleans, LA (USA))

1989-09-01

114

Influence of salt marsh on bacterial activity in two estuaries with different hydrodynamic characteristics (Ria de Aveiro and Tagus Estuary).  

Science.gov (United States)

The influence of salt marsh on estuarine bacterioplankton was investigated in two estuaries with different hydrodynamic characteristics (Ria de Aveiro and Tagus Estuary). In the Ria de Aveiro, bacteria in the flood water overlying the marsh were two times more abundant and five to six times more active than in the main channel. In the Tagus Estuary, bacterial abundance was similar in flooding and channel water, but bacterial activity was up to two times higher in the main channel. The two salt marshes have distinct influences on estuarine bacterioplankton abundance and activity. In the Ria de Aveiro, salt marsh enhanced estuarine bacterial communities, increasing their size and stimulating their activity. By contrast, the salt marsh in the Tagus Estuary does not seem to increase the bacterial abundance and production in the channel water. These distinct influences may be explained by the hydrodynamic characteristics of the salt marshes, which were confirmed by the hydrodynamic model implemented for both systems. PMID:17374125

Santos, Luísa; Cunha, Angela; Silva, Helena; Caçador, Isabel; Dias, Joao M; Almeida, Adelaide

2007-06-01

115

Organochlorine pesticides, polychlorinated biphenyls and trace elements in wild European sea bass (Dicentrarchus labrax) off European estuaries  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polychlorinated biphenyls (PCBs) and organochlorine pesticides like dichloro-diphenyl-trichloroethane (DDTs), hexachlorocyclohexanes (HCHs), aldrin, dieldrin and trace elements (Cd, Cu, Se, Pb, Zn and Hg) were analysed in the muscle of European sea bass (Dicentrarchus labrax) sampled in Atlantic coastal regions near several important European river mouths (Gironde, Charente, Loire, Seine and Scheldt). High contamination levels were measured in the muscles of European sea bass sampled in the c...

Schnitzler, Joseph; Thome?, Jean-pierre; Lepage, Mario; Das, Krishna

2011-01-01

116

Frequency of twinning in southwest Nigeria  

Directory of Open Access Journals (Sweden)

Full Text Available Background: In the human species, twin is a type of multiple birth in which the mother gives birth to two offspring from the same pregnancy. The occurrence and frequency of twinning, however, varies across human populations. The maternal age, socio-environmental factors, increase in the use of contraceptives, the race of human population, increase in the spontaneous abortion rate, and seasonal variations are among the factors that could influence twinning rate. Information on twinning rates in southwest Nigeria is limited. Aims : This study presents information on the frequency of twinning, as well as its analysis by maternal age, in four urban settings in southwest Nigeria. This is with the aim of extending current knowledge on the frequency of twinning in southwest Nigeria and contributing to the demographic studies in the country. Materials and Methods: Data on single births and twin births from January 1995 to December 2004 were collected from the Oyo State General Hospital (OSGH, Wesley Guild Hospital (WGH, Obafemi Awolowo University Teaching Hospital (OAUTH, and Ekiti State Specialist Hospital (ESSH in Ogbomoso, Ilesa, Ile-Ife, and Ado-Ekiti respectively. These were analyzed by year and maternal age groups of 15-19, 20-24, 25-29, 30-34, 35-39, 40-44, and 45-49 years according to the standard method. Results: A frequency of twin births of 46.5 per 1000 deliveries and 46.2 per 1000 deliveries was recorded for Ilesa and Ile-Ife respectively. The frequency recorded for Ogbomoso and Ado-Ekiti was 38.5 and 22.1 per 1000 deliveries respectively. The overall average frequency of 40.2 per 1000 deliveries for the four hospitals ranks among the highest recorded rates of twin births in the world. The maternal age group of 25-29 years had the highest occurrence of twin births, while the lowest was recorded in the 45-49 years age group. Conclusion: This analysis reveals high incidence of twinning in the studied areas and supports previous assertion that the southwestern part of Nigeria has the highest twinning rate in the country and in the whole world. It is our opinion that diet, maternal history of twinning, and some socio-environmental factors may have influenced the results.

Akinboro A

2008-01-01

117

Center for Southwest Research and Special Collections  

Science.gov (United States)

Based at the University of New Mexico, the Center for Southwest Research and Special Collections (CSWR) brings together interdisciplinary subjects relating to New Mexico, the southwestern United States, Mexico and Latin America. In the About the CSWR area, visitors can learn more about the collection's strengths, how to use the collection, and fellowship opportunities. Visitors can also look over the New Mexico's Digital Collections, which contain everything from digitized newspapers from the Land of Enchantment to information about New Deal era musicology research. Moving on, the LoboVault contains scholarly publications related to these matters crafted by University of New Mexico affiliates from 2009 to the present day. The site is rounded out by the Rocky Mountain Online Archive, which contains helpful links to related collections from around the region.

118

Southwest Regional Partnership on Carbon Sequestration  

Energy Technology Data Exchange (ETDEWEB)

The Southwest Partnership on Carbon Sequestration completed several more tasks during the period of April 1, 2005-September 30, 2005. The main objective of the Southwest Partnership project is to evaluate and demonstrate the means for achieving an 18% reduction in carbon intensity by 2012. While Phase 2 planning is well under way, the content of this report focuses exclusively on Phase 1 objectives completed during this reporting period. Progress during this period was focused in the three areas: geological carbon storage capacity in New Mexico, terrestrial sequestration capacity for the project area, and the Integrated Assessment Model efforts. The geologic storage capacity of New Mexico was analyzed and Blanco Mesaverde (which extends into Colorado) and Basin Dakota Pools were chosen as top two choices for the further analysis for CO{sub 2} sequestration in the system dynamics model preliminary analysis. Terrestrial sequestration capacity analysis showed that the four states analyzed thus far (Arizona, Colorado, New Mexico and Utah) have relatively limited potential to sequester carbon in terrestrial systems, mainly due to the aridity of these areas, but the large land area offered could make up for the limited capacity per hectare. Best opportunities were thought to be in eastern Colorado/New Mexico. The Integrated Assessment team expanded the initial test case model to include all New Mexico sinks and sources in a new, revised prototype model in 2005. The allocation mechanism, or ''String of Pearls'' concept, utilizes potential pipeline routes as the links between all combinations of the source to various sinks. This technique lays the groundwork for future, additional ''String of Pearls'' analyses throughout the SW Partnership and other regions as well.

Brian McPherson

2006-04-01

119

Salt intrusion in multi-channel estuaries: a case study in the Mekong Delta, Vietnam  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There is a well-tested theory for the computation of salt intrusion in alluvial estuaries that is fully analytical and predictive. The theory uses analytical equations to predict the mixing behaviour of the estuary based on measurable quantities, such as channel topography, river discharge and tidal characteristics. It applies to single-channel topographies and estuaries that demonstrate moderate tidal damping. The Mekong delta is a multi-channel estuary where the tide is damped due to a rela...

Nguyen, A. D.; Savenije, H. H.

2006-01-01

120

Mineral and organic soluble forms of zinc, iron and copper: Distribution in the Seine Estuary.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

One characteristic of the Seine Estuary system is the process of sediment resuspension by the specific hydrodynamics of this environment. It's the main factor of trace metals transport. Autotrophic activities also have an effect on the estuary, by pH variation. The behavior of soluble and organic copper, iron, have been studied in relation to salinity in and out of the estuary. The results are compared with those of other estuaries.

Gandon, R.; Guegueniat, P.; Fischer, J.; Wartel, M.

1985-01-01

 
 
 
 
121

Eco-morphological problems in the Yangtze estuary and the Western Scheldt:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper compares the Yangtze Estuary in China and the Western Scheldt Estuary in The Netherlands by their morphodynamic and ecological systems, their engineering works and estuarine management issues, and the major challenges in studying them. Physically speaking, the two estuaries are very different. The Yangtze Estuary is much larger and much more influenced by the upstream river than the Western Scheldt. Yet, they also have a number of morphological and ecological features in common. Bo...

Vriend, H. J.; Wang, Z. B.; Ysebaert, T. J. W.; Herman, P. M. J.; Ding, P. X.

2011-01-01

122

Contribution of N2O emissions to the atmosphere from Indian monsoonal estuaries  

Directory of Open Access Journals (Sweden)

Full Text Available Estuaries are known to contribute a significant amount of nitrous oxide (N2O to the atmosphere; however, the contribution from the Indian estuaries is unknown. We made an attempt to estimate emissions of N2O from the Indian estuaries by collecting samples from 28 major and minor estuaries along the Indian coast during the wet and dry periods. The N2O was mostly saturated in all measured Indian estuaries during the study period (72–631%, with exceptionally high saturation in the Ponniyaar estuary (5902% during the wet period. The N2O saturation displayed a strong relation with dissolved inorganic nitrogen (DIN; nitrate +nitrite and ammonium, ammonium and dissolved oxygen saturation, suggesting that nitrification is the major source of N2O in the Indian estuaries. The negative relation between salinity and N2O saturation suggests inner estuaries are a strong source compared to outer estuaries. The annual mean N2O saturation (204±137% and fluxes (1.3 µmol N2O m?2 d?1 in the Indian estuaries were significantly less than European estuaries (271% and ~2.7 µmol N2O m?2 d?1, respectively. The estimation of flux of N2O from the European estuaries was also biased due to the inclusion of an exceptionally high supersaturation value from a small UK estuary, Colne (2645%. However, low N2O saturation and fluxes in the Indian estuaries were related to mean low concentration of DIN that led to low nitrification rates compared to world estuaries. Despite India ranking second in artificial fertilizers use, high flushing rates during the wet period reduce residence time leading to less modification within the estuary.

Gijjapu Durga Rao

2013-05-01

123

Dynamics of intertidal flats in the Loire estuary  

Science.gov (United States)

Tidal flats form at the edges of many tidal estuaries, and are found in broad climatic regions. Their evolution plays a fundamental role in maintaining the morphodynamic equilibrium of an estuary. The Loire estuary is one of the largest macrotidal systems of the french atlantic coast. Since 200 years, its geometry has been drastically modified through channeling, deepening, embanking, infilling of secondary channels, etc. These works altered many intertidal areas. In the recent years, efforts for the rectification of the morphology have been made in order to restore the ecology of the estuary. In this context, it is crucial to better understand the dynamics of intertidal flats, still poorly understood in this estuary. The aim of this work is to analyse a series of original observations conducted for the first time in two intertidal flats of the central Lore estuary between 2008 and 2010. The tidal flats are situated in the northern bank, at 12 and 17 km upstream from the mouth respectively. Six Altus altimeters were deployed at two cross shore transects, measuring continuously and at a high-frequency bed altimetry and water level, providing information on tide and waves. At the semi-diurnal tidal scale, the surficial sediment of intertidal flats is permanently mobilized. Altimetry variations are low, and their amplitude varies as a function of tides and river flow. At the scale of several months, the sedimentation is controlled by the position of the turbidity maximum (and therefore by the river flow) and also by the tidal amplitude. During low river flow periods, altimetry variations are only due to tidal cycles. During decaying tides, suspended sediment settle mainly on the lower part of the tidal flats, forming fluid mud layers of several cm thick, which can consolidate rapidly; under rising tides, the increasing of tidal currents promotes erosion. During periods of high river flow, the turbidity maximum shifts to the lower estuary. The higher suspended sediment concentration increases deposition and erosion rates, especially in the lower parts of the flats, where continuous sedimentary accretion is favoured by the proximity of the channel. During this period, reinforcement of current veolocities limits deposition in the central and high portion of the flats, where erosion is enhanced. The first rivers floods remove fluid mud in the upper estuary, previously deposited during the dry season, which is transported seawards. The transported suspended sediment settles massively in the lower parts of the flats and in the channels. The deposited mud is eroded a few days later. These results provide useful information to better understand the dynamics of the Loire estuary, as well as they give in situ data to be compared with numerical modelling.

Kervella, Stephane; Sottolichio, Aldo; Bertier, Christine

2014-05-01

124

Effect of Freshwater Influx on Phytoplankton in the Mandovi Estuary (Goa, India) during Monsoon Season: Chemotaxonomy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Mandovi estuary is a prominent water body that runs along the west coast ofIndia. It forms an estuarine network with the adjacent Zuari estuary, connected via the Cumbharjua canal. The physico-chemical conditions seen in the Mandovi estuary are influenced by two factors:

Parab, Sushma G.; Prabhu Matondkar, S. G.; Gomes, Helga Do R.; Goes, Joaquim I.

2013-01-01

125

Metals in sediments and benthic organisms in the Mersey estuary  

Science.gov (United States)

Concentrations of twelve metals were determined in sediments, seaweed ( Fucus vesiculosus), winkles ( Littorina littorea), polychaetes ( Nereis diversicolor), suspension feeding bivalves ( Mytilus edulis, Cerastoderma edule) and deposit feeding bivalves ( Macoma balthica, Scrobicularia plana) collected from the Mersey estuary between April 1980 and June 1984. Sediments and organisms in the Mersey are moderately contaminated with most of the metals measured, but mercury concentrations are consistently higher than in other United Kingdom estuaries. Comparisons with other sites in the North West of England indicate that mercury residues in organisms, though primarily dependent on sediment concentrations, are also influenced by complexation with particulate organic matter which reduces the availability of mercury. The biological availability of arsenic in Mersey sediments is similarly influenced by complexation with iron oxyhydroxides. Nereis diversicolor and Macoma balthica are the most suitable indicator species in terms of abundance and widespread distribution along the estuary, and, for the majority of metals, tissue concentrations increase upstream, reflecting corresponding gradients in sediment contamination. However mid-estuarine peaks for tin, chromium copper and nickel in Nereis indicate more localised inputs to the estuary. Correlations between lead in sediments and organisms are poor; it is suggested that hydrophilic alkyl lead compounds may be the predominant biologically available forms. Progressive reductions in mercury contamination in sediments and mercury and lead in organisms have occurred in recent years, which coincide with efforts to reduce inputs of these metals to teh Mersey estuary.

Langston, W. J.

1986-08-01

126

An analysis of the trophic network of a macrotidal estuary: the Seine Estuary (Eastern Channel, Normandy, France)  

Science.gov (United States)

A steady state, mass balance, trophic network has been constructed to illustrate the flow of energy in the Seine Estuary by using Network Analysis and Ecopath methods. This ecosystem shows 15 compartments from primary producers to the top consumers (fish and birds). This study has been compared with other ecosystems of comparable nature located in North America (Narragansett, Chesapeake, Delaware Bays), Europe (Ems Estuary, Dublin Bay and Bay of Somme), and South Africa (Swartkops Estuary) in which analysis of trophic network has been applied with similar methods. The Seine Estuary shows values of some global parameters and indices either close to large North American bays and a South African estuary characterised by the complexity of their trophic network, or values near European bays and estuaries, or else remain typical of the Seine estuary. All of this reflects specific functioning of the Seine Estuary which can be explained by the analysis of the dominant food web. In the upstream sector an important pelagic food web was found correlated with highest primary production, especially planktonic, which is rapidly consumed by an abundant zooplankton and suprabenthos (Mysidacae and Decapoda Crustacea). This reveals the dominant consumer role of this sector. The external fluvial inputs (277.80 gC m -2 y -1) are transferred to the downstream sector which produces the major export (548.43 gC m -2 y -1), in parallel with the low consumption and efficiency of dominant benthos component from its bentho-pelagic food web. This reflects the dominant exporter role of this sector. In the Seine Estuary low values of detritivory index D/ H (2.52), recycling index FCI (16.1%) and connectance (0.24) were found associated with high values of P/ B ratio (38.2%), sum of exports (548.43 gC m -2 y -1) and the great difference between ratio of ascendency to capacity development A/ C and internal ratio Ai/ Ci. This shows the lack of a dominant resource as in Delaware Bay, that the state of development is different from a mature ecosystem, and the dependance on external connections similar to the Bay of Somme, another ecosystem of Eastern Channel, France.

Rybarczyk, Hervé; Elka??m, Bernard

2003-12-01

127

Southwest Region Experiment Station - Final Technical Report  

Energy Technology Data Exchange (ETDEWEB)

Southwest Technology Development Institute (SWTDI), an independent, university-based research institute, has been the operator of the Southwest Region Photovoltaic Experiment Station (SWRES) for almost 30 years. The overarching mission of SWTDI is to position PV systems and solar technologies to become cost-effective, major sources of energy for the United States. Embedded in SWTDI's general mission has been the more-focused mission of the SWRES: to provide value added technical support to the DOE Solar Energy Technologies Program (SETP) to effectively and efficiently meet the R&D needs and targets specified in the SETP Multi-Year Technical Plan. : The DOE/SETP goals of growing U.S. PV manufacturing into giga-watt capacities and seeing tera-watt-hours of solar energy production in the U.S. require an infrastructure that is under development. The staff of the SWRES has supported DOE/SETP through a coherent, integrated program to address infrastructural needs inhibiting wide-scale PV deployment in three major technical categories: specialized engineering services, workforce development, and deployment facilitation. The SWRES contract underwent three major revisions during its five year period-of- performance, but all tasks and deliverables fell within the following task areas: Task 1: PV Systems Assistance Center 1. Develop a Comprehensive multi-year plan 2. Provide technical workforce development materials and workshops for PV stakeholder groups including university, professional installers, inspectors, state energy offices, Federal agencies 3. Serve on the NABCEP exam committee 4. Provide on-demand technical PV system design reviews for U.S. PV stakeholders 5. Provide PV system field testing and instrumentation, technical outreach (including extensive support for the DOE Market Transformation program) Task 2: Design-for-Manufacture PV Systems 1. Develop and install 18 kW parking carport (cost share) and PV-thermal carport (Albuquerque) deriving and publishing lessons learned Task 3: PV Codes and Standards 1. Serve as the national lead for development and preparation of all proposals (related to PV) to the National Electrical Code 2. Participate in the Standards Technical Panels for modules (UL1703) and inverters (UL1741) Task 4: Assess Inverter Long Term Reliability 1. Install and monitor identical inverters at SWRES and SERES 2. Operate and monitor all inverters for 5 years, characterizing all failures and performance trends Task 5: Test and Evaluation Support for Solar America Initiative 1. Provide test and evaluation services to the National Laboratories for stage gate and progress measurements of SAI TPP winners

Rosenthal, A

2011-08-19

128

Drought in Central South-West Asia  

Science.gov (United States)

In this investigation on Central Southwest Asia (CSWA) meteorological drought, water budget terms have been identified. Tele-connections with climate patterns indices and their impact on the shifting of the mid-latitude jet stream have been explored. We have evaluated the precipitation simulations of different climate models using results from the Atmospheric Model Inter-comparison Project (AMIP). The seasonal and annual moisture flux convergence of the CSWA region has been examined using reanalysis data sets allowing us to compute water budgets terms in central southwest Asia to understand the regional topographic effects on local precipitation. The study also examines composites of moisture flux convergence (MFC) that characterize the wettest and driest years in this region. Spatially and vertically distributed features of MFC during wet and dry years have been studied to identify the variability of water transport during the 1999-2001 drought periods from the normal years. Teleconnections between precipitation over CSWA and SLP anomalies associated with different climate patterns, North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Pacific Decadal Oscillation (PDO) and El Nino Southern Oscillation (ENSO) have been quantified by using Singular Value Decomposition (SVD). Analysis showed that variation of precipitation over CSWA is associated with variation in SLP over the Atlantic and Pacific Oceans. The highest coupling strength between regional precipitation and different phases of climate patterns has been investigated during the negative phase of the NAO and the positive phase of the PDO. Variability of sea level pressure over the Pacific and Atlantic oceans is directly linked with four features of the average jet stream (November-April) up wind of CSWA. There is its strength over the western part of the domain, enhancement of a convergence region to the west of the domain, shifting towards north/south, and its direction when crossing the domain. This study evaluates simulations of precipitation patterns by using Atmospheric Model Inter-comparison Project (AMIP) results compared with the GPCC (Global Precipitation Climatology Centre) monthly precipitation data. Most of the models over-predict cyclones-induced autumn precipitation over the western part of the domain and monsoonal summer rainfall over the eastern part of the domain. The Max Planks Institute model (MPI) showed best overall results for the region. Horizontal resolution is not the sole arbiter of model performance. No clear linkages between model physics configurations and model performance have been found.

Malik, Khalid Mahmood

129

76 FR 25298 - Southwest Idaho Resource Advisory Committee  

Science.gov (United States)

...of 2000, as amended, (Pub. L 110-343), the Boise, Payette, Salmon-Challis, and Sawtooth National Forests' Southwest...2011. Michael R. Williams, Acting Forest Supervisor, Payette National Forest. [FR Doc. 2011-10821 Filed...

2011-05-04

130

76 FR 18153 - Southwest Idaho Resource Advisory Committee  

Science.gov (United States)

...of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, Salmon-Challis, and Sawtooth National Forests' Southwest...March 24, 2011. Suzanne C. Rainville, Forest Supervisor, Payette National Forest. [FR Doc. 2011-7748 Filed...

2011-04-01

131

Geomorphological variability among microtidal estuaries from the wave-dominated South African coast  

Science.gov (United States)

Over 300 independent river outlets exist around the microtidal, wave-dominated South African coast. Most of these are located in drowned river valley settings and have acquired their present morphology during the Holocene marine transgression. A variety of geomorphological forms are identified in these estuaries that result from variation in antecedent topography, fluvial sediment supply and marine sediment supply. Five distinctive estuary types are identified on the basis of contemporary morphodynamics. These are categorised into three types of normally open estuary (that maintain a semi-permanent connection with the open sea) and two types of normally closed estuary, which are separated from the sea for long periods by a continuous supratidal barrier. The contemporary morphodynamics and sedimentary environments of each estuary type are discussed. Open estuaries include barrier-inlet systems maintained by fluvial discharge (termed river-dominated estuaries) and tidal discharge (termed tide-dominated estuaries). A third category of open estuary lacks a supratidal barrier due to inadequate marine sediment availability. Closed estuaries receive marine influence via barrier overwash and occasional breaching but are typically enclosed behind a continuous supratidal barrier. Two categories of closed estuary are identified: perched and non-perched. Perched estuaries develop behind high berms and maintain a water level above high tide level in the open sea. They are often dominated by fresh to brackish water and breach and drain periodically. Non-perched estuaries are developed behind low-elevation barriers fronted by wide dissipative beach profiles. High overwash frequency introduces marine water into such systems. Breaching of such estuaries does not produce dramatic draining as the water level may only drop according to the stage of the open sea tidal cycle. The variety of estuary types suggests several potential pathways may exist in estuarine development and that the progressive infilling model is an over simplification.

Cooper, J. A. G.

2001-09-01

132

?-particle radioactivity of hot particles from the Esk estuary  

International Nuclear Information System (INIS)

Transuranium radionuclides (Pu, Am and Cm) present in effluents discharged into the north-east Irish Sea by British Nuclear Fuels Limited, Windscale, Cumbria, UK, are found in sediment and biota of the Esk estuary approximately 10 km to the south. The site of the present investigation was at Newbiggin and the materials examined were suspended particulate debris samples at the sea surface, bottom sediments and some forms of biota collected in September 1977. It is shown here that hot particles (defined as small volumes of material emitting ? particles recorded in a dielectric detector as dense clusters of tracks from a common origin) found in the estuary are likely to be original effluent debris derived from the processing of Magnox uranium fuel elements and not formed in situ as a result of natural processes common to the estuary. (author)

1981-04-23

133

Dissolved organic matter status in Damietta estuary of the Nile  

Energy Technology Data Exchange (ETDEWEB)

The seasonal distribution of dissolved organic matter (DOM) in Damietta estuary of the Nile was investigated to show the influence of organic pollution. The DOM values increased generally with depth. The vertical values of DOM varied from 0.23-9.97 mg O/l. The average DOM values gave noticeable local variations in each month and pronounced monthly variations at each station. The maximum monthly average value in August coincided principally with elevation of temperature and the minimum in December is due mainly to the drop in temperature. The direct effect of pollution, in increasing the DOM content in the estuary, decreases relatively towards the sea, as indicated by the minimum regional average DOM value at the mouth of Damietta estuary. An inverse relationship was found generally between the averages of DOM and those of dissolved oxygen.

Saad, M.A.; Abdel-Moati, M.A.

1984-12-01

134

Waterfowl migration and distribution in North West estuaries. V. 2  

International Nuclear Information System (INIS)

Waterfowl populations may be affected by the proposed tidal barrage across the Mersey. A study was performed with three objectives: (1) to evaluate the patterns of usage of the intertidal flats of the Mersey estuary by waders and wildfowl and to establish which are the preferred areas; (2) to identify the places of origin and movement patterns of the populations of waders and wildfowl that visit the Mersey estuary; and (3) to evaluate evidence regarding the capacity of British estuaries to absorb waders and wildfowl populations which might be displaced by a Mersey Barrage. The text and tables of results of this study have already been presented in Volume 1. Volume 2 contains the figures describing the results (U.K)

1990-01-01

135

A lightning climatology of the South-West Indian Ocean  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The World Wide Lightning Location Network (WWLLN) data have been used to perform a lightning climatology in the South-West Indian Ocean (SWIO) region from 2005 to 2011. Maxima of lightning activity were found in the Maritime Continent and southwest of Sri Lanka (>50 fl km?2 yr?1) but also over Madagascar and above the Great Lakes of East Africa (>10–20 fl km?2 yr?1). Lightning flashes within tropical storms and tropical c...

Bovalo, C.; Barthe, C.; Be?gue, N.

2012-01-01

136

Radium isotopes in the Orinoco estuary and Eastern Caribbean Sea  

International Nuclear Information System (INIS)

Radium isotopes provide a means of identifying the source of freshened waters in the ocean and determining the time elapsed since these waters were in the estuary. The authors present evidence that during April, waters from the Amazon mixing zone pass within 50 km of the mouth of the Orinoco River. These Amazon waters are characterized by a lower 228Ra/226Ra activity ratio (AR) than are waters from the Orinoco at similar salinities. During autumn, the increased discharge of the Orinoco displaces the freshened Amazon waters seaward, yet the two can be distinguished clearly. Within the Caribbean Sea, waters of Orinoco origin carry a characteristic radium signature including excess activities of 224Ra. This isotope may be used to estimate the time elapsed since the waters were removed from contact with sediments. Current speeds based on 224Ra dating ranged from 15 to 33 cm/s during April. The radium isotopes also provide an assessment of sediment mixing in the estuary. During low discharge (April), considerable mixing of older sediment by physical or biological processes or dredging maintained high activities of 228Ra in the estuary and produced the highest 228Ra/226Ra AR's yet measured in any estuary. During high discharge (September), a large fraction of the 228Ra was derived from desorption from fresh sediment rather than mixing of older sediments. Activities of 224Ra were high in the estuary during both high and low discharge, indicating that considerable mixing of recently introduced sediment must occur during each period. During April, 224Ra and 228Ra activities in the water were about equal, indicating that most of the sediment being resuspended had been stored in the estuary long enough to reestablish radioactive equilibrium in the 232Th decay series (i.e., 20 years). 19 refs., 11 figs., 3 tabs

1993-02-15

137

Mud transport in the Microtidal San Jacinto Estuary  

Science.gov (United States)

The overall objective of this research is to better understand the sediment transport processes in the microtidal San Jacinto Estuary (near Houston, TX) under variable hydrologic conditions. A numerical modeling approach is selected to answer the main question of; how will changes in freshwater input change the sedimentation pattern of the region? In this computational work, no new numerical method or code is developed, but rather an existing technology (MIKE 3D developed by DHI) is used to build a virtual San Jacinto Estuary laboratory where boundary conditions could be applied and altered to the domain to observe the general functional response of the system. Two synthetic freshwater inflows, simulating dry and wet conditions, were used in the numerical modeling experiments. Simulations showed that change in freshwater inflow has major impact on the salinity magnitude within the estuary. In dry conditions, the 5 ppt isohaline traveled all the way upstream of Morgans Point, almost to the confluence of San Jacinto River with Buffalo Bayou. During the extreme wet weather conditions, the 5 ppt isohaline of the surface water was pushed almost as far as Galveston Island. Overall erosion and deposition pattern showed little change between extreme dry and wet years. In general, part of the shallow areas experienced erosion whereas deeper parts of the estuary were under deposition. High freshwater inflow caused around 30% higher deposition in some parts of the channel compared with the low freshwater. Furthermore, examining the mass balance within the whole San Jacinto Estuary showed that around 28% of the input sediment was flushed out during the wet season. But in dry season, not only no sediment left the domain but also it received around 17% of the total available sediment within the estuary from the shelf.

Salehi, M.

2013-12-01

138

The recreational value of river inflows into South African estuaries  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Estuarine habitats are subject to increasing demand pressures. Some of these are direct, for the appealing space they provide for residences and recreation; and some are indirect, in the form of competitive demand for the inputs required to maintain their ecological functionality, for instance, rive [...] r inflows. As a result of increasing demand for river water the connection of many of South Africa's estuaries with the sea has been undermined and their recreational appeal reduced. This paper reports findings on these negative impacts for selected estuaries. The contingent valuation method was used to estimate the value of recreational benefits that would result at 40 South African estuaries if water-inflow reductions were averted. The studies were undertaken between 2000 and 2007. All the estuaries selected were known to be vulnerable to changes in river inflows. Expert opinions on the consequences of specified hypothetical changes to water inflows into estuaries were used to generate the scenarios valued. User populations were estimated and surveys administered to samples of these populations. From the elicited responses median estuary user willingness to pay bids were predicted using Tobit and OLS models. An internal credibility assessment was conducted over the plausibility of the predictive model, the consistency of the values to those estimated using an alternative valuation method (the contingent travel cost method), and the reliability of the estimates. For the 37 estimates deemed reliable (but not necessarily valid), the average of the predicted median values of river inflow into estuaries was calculated to be 3.4 c/m³ (South African cents, ZAR) and standard deviation 3.84 c/m³. The average of the predicted mean values was calculated to be 7.4 c/m³ and the standard deviation 6.7 c/m³. It was also found that where there had been extensive economic development around the river system, the values of inflows into estuaries tended to be less than the value of water abstracted upstream.

Hosking, Stephen.

139

Impacts of pesticides in a Central California estuary.  

Science.gov (United States)

Recent and past studies have documented the prevalence of pyrethroid and organophosphate pesticides in urban and agricultural watersheds in California. While toxic concentrations of these pesticides have been found in freshwater systems, there has been little research into their impacts in marine receiving waters. Our study investigated pesticide impacts in the Santa Maria River estuary, which provides critical habitat to numerous aquatic, terrestrial, and avian species on the central California coast. Runoff from irrigated agriculture constitutes a significant portion of Santa Maria River flow during most of the year, and a number of studies have documented pesticide occurrence and biological impacts in this watershed. Our study extended into the Santa Maria watershed coastal zone and measured pesticide concentrations throughout the estuary, including the water column and sediments. Biological effects were measured at the organism and community levels. Results of this study suggest the Santa Maria River estuary is impacted by current-use pesticides. The majority of water samples were highly toxic to invertebrates (Ceriodaphnia dubia and Hyalella azteca), and chemistry evidence suggests toxicity was associated with the organophosphate pesticide chlorpyrifos, pyrethroid pesticides, or mixtures of both classes of pesticides. A high percentage of sediment samples were also toxic in this estuary, and sediment toxicity occurred when mixtures of chlorpyrifos and pyrethroid pesticides exceeded established toxicity thresholds. Based on a Relative Benthic Index, Santa Maria estuary stations where benthic macroinvertebrate communities were assessed were degraded. Impacts in the Santa Maria River estuary were likely due to the proximity of this system to Orcutt Creek, the tributary which accounts for most of the flow to the lower Santa Maria River. Water and sediment samples from Orcutt Creek were highly toxic to invertebrates due to mixtures of the same pesticides measured in the estuary. This study suggests that the same pyrethroid and organophosphate pesticides that have been shown to cause water and sediment toxicity in urban and agriculture water bodies throughout California, have the potential to affect estuarine habitats. The results establish baseline data in the Santa Maria River estuary to allow evaluation of ecosystem improvement as management initiatives to reduce pesticide runoff are implemented in this watershed. PMID:24464329

Anderson, Brian; Phillips, Bryn; Hunt, John; Siegler, Katie; Voorhees, Jennifer; Smalling, Kelly; Kuivila, Kathy; Hamilton, Mary; Ranasinghe, J Ananda; Tjeerdema, Ron

2014-03-01

140

Rhenium and Molybdenum in Rivers and Estuaries.  

Science.gov (United States)

Due to their redox-sensitive nature, the geochemical cycles of Re and Mo are linked to the global organic carbon cycle. Reducing sediments constitute a globally important sink and weathering of organic-rich sediments is responsible for a large portion of the Re and - to a lesser extent - Mo flux to the oceans (Colodner et al., 1993; Jaffe et al., 2002). Riverine concentrations of Re and Mo are a function of the river basin lithology, but are also likely to be affected by anthropogenic contributions (Colodner et al., 1995). Current estimates of global natural riverine Re flux are restricted to single analyses of four major rivers, which characterize only 23%\\ of the global freshwater flux (Colodner et al., 1993). Annual variability of Re and Mo concentrations in rivers has not been studied. A single study of Re concentrations along the salinity gradient of the Amazon shelf is suggestive of conservative mixing, but scatter in the data do not allow to exclude the possibility of Re addition in the low-salinity end of the profile (Colodner et al., 1993). Careful evaluation of samples from the Hudson River estuary using a variety of extraction techniques indicates that spike-sample equilibration was not fully achieved using commonly used methods. We have therefore developed a simple, clean and efficient method of extracting Re from filtered water samples. Our method utilizes syringe filtration, prolonged heating to achieve spike-sample equilibration, batch equilibration with TEVA resin, and extraction of Re and Mo using syringe filtration. Rhenium concentrations in the Hudson, Housatonic and Connecticut rivers are 38 pM, 6.6 pM and 14 pM, respectively, much higher than the estimated global average of 2.1 pM (Colodner et al., 1993). Molybdenum concentrations are 4.6 nM, 5.5 nM, 7.8 nM, respectively. These rivers drain basins of Precambrian basement as well as predominantly Paleozoic sediments and have been substantially urbanized. Data for a salinity profile along the Hudson River estuary are suggestive of conservative mixing of Mo. However, data for Re indicate non-conservative mixing with a significant Re source between 5 and 12 psu. This feature could reflect an anthropogenic point source near Croton Point. Alternatively, it could be caused by a process that transfers Re, but not Mo, from the particulate into the operationally defined dissolved phase. Preliminary data for a Mississippi delta salinity profile suggest projected Re and Mo concentrations of about 90 pM and 26 nM for the freshwater end member, respectively. Our results indicate that the surficial Re cycle is more complex then previously thought. It requires further evaluation before a global estimate of natural riverine Re flux can be accurately constrained. A revision of the marine residence time of Re may be required.

Walker, B. D.; Peucker-Ehrenbrink, B.

2004-12-01

 
 
 
 
141

Research, Monitoring, and Evaluation for the Federal Columbia River Estuary Program  

Energy Technology Data Exchange (ETDEWEB)

The purpose ofthis document is to describe research, monitoring, and evaluation (RME) for the Federal Columbia River Estuary Program. The intent of this RME effort is to provide data and information to evaluate progress toward meeting program goals and objectives and support decision-making in the Estuary Program. The goal of the Estuary Program is to understand, conserve, and restore the estuary ecosystem to improve the performance of listed salmonid populations. The Estuary Program has five general objectives, designed to fulfill the program goal, as follows. 1. Understand the primary stressors affecting ecosystem controlling factors, such as ocean conditions and invasive species. 2. Conserve and restore factors controlling ecosystem structures and processes, such as hydrodynamics and water quality. 3. Increase the quantity and quality of ecosystem structures, i.e., habitats, juvenile salmonids use during migration through the estuary. 4. Maintain the food web to benefit salmonid performance. 5. Improve salmonid performance in terms of life history diversity, foraging success, growth, and survival. The goal of estuary RME is to provide pertinent and timely research and monitoring information to planners, implementers, and managers of the Estuary Program. In conclusion, the estuary RME effort is designed to meet the research and monitoring needs of the estuary Program using an adaptive management process. Estuary RME's success and usefulness will depend on the actual conduct of adaptive management, as embodied in the objectives, implrementation, data, reporting, and synthesis, evaluation, and decision-making described herein.

Johnson, Gary E.; Diefenderfer, Heida L.; Ebberts, Blaine D.; Tortorici, Cathy; Yerxa, Tracey; Leary, J.; Skalski, John R.

2008-02-05

142

Marine conservation in a Southwest Portuguese natural park  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Most of the SW Portuguese continental coast is protected by a natural park (Parque Natural do Sudoeste Alentejano e Costa Vicentina – PNSACV). A marine zone 2 km wide has been designated along the coast of this park (ca. 130 km) with oceanic sandy beaches, extensive rocky shores, and small estuaries and coastal lagoons.

2009-01-01

143

Spacecraft computer technology at Southwest Research Institute  

Science.gov (United States)

Southwest Research Institute (SwRI) has developed and delivered spacecraft computers for a number of different near-Earth-orbit spacecraft including shuttle experiments and SDIO free-flyer experiments. We describe the evolution of the basic SwRI spacecraft computer design from those weighing in at 20 to 25 lb and using 20 to 30 W to newer models weighing less than 5 lb and using only about 5 W, yet delivering twice the processing throughput. Because of their reduced size, weight, and power, these newer designs are especially applicable to planetary instrument requirements. The basis of our design evolution has been the availability of more powerful processor chip sets and the development of higher density packaging technology, coupled with more aggressive design strategies in incorporating high-density FPGA technology and use of high-density memory chips. In addition to reductions in size, weight, and power, the newer designs also address the necessity of survival in the harsh radiation environment of space. Spurred by participation in such programs as MSTI, LACE, RME, Delta 181, Delta Star, and RADARSAT, our designs have evolved in response to program demands to be small, low-powered units, radiation tolerant enough to be suitable for both Earth-orbit microsats and for planetary instruments. Present designs already include MIL-STD-1750 and Multi-Chip Module (MCM) technology with near-term plans to include RISC processors and higher-density MCM's. Long term plans include development of whole-core processors on one or two MCM's.

Shirley, D. J.

1993-01-01

144

Sediment transport investigations in Hugli estuary using radiotracer technique  

International Nuclear Information System (INIS)

This paper describes sediment transport investigations carried out at two different locations in Hugli estuary along the shipping channel leading to Haldia Dock Complex of the Kolkata Port Trust, Kolkata. The objectives of these investigations were to evaluate the suitability of the proposed dumping sites for optimizing the dredging operation and implementing the recommendations of the River Regulatory Measures, Kolkata Port Trust, Kolkata

2006-01-23

145

Laboratory Investigations on Estuary Salinity Mixing: Preliminary Analysis  

Directory of Open Access Journals (Sweden)

Full Text Available Estuaries are bodies of water along the coasts that are formed when fresh water from rivers flows into and mixes with salt water from the ocean. The estuaries serve as a habitat to some aquatic lives, including mangroves. Human-induced activities such as dredging of shipping lanes along the bottom estuarine, the disposal of industrial wastes into the water system and shoreline development influence estuarine dynamics which include mixing process. These activities might contribute to salinity changes and further adversely affect the estuarine ecosystem. In order to study at the characteristics of the mixing between salt water (estuary and freshwater (river, a preliminary investigation had been done in the laboratory. Fresh water was released from one end of the flume and overflowing at weir at the other end. Meanwhile, salt water was represented by the red dye tracer released through a weir and intruded upstream as a gravity current. The isohalines are plotted to see the salinity patterns. Besides, to examine the spatial and temporal salinity profiles along the laboratory investigations, the plotted graphs have been made. The results show that the changes in salinity level along the flume due to mixing between fresh water and salt water. This showed typical salt-wedge estuary characteristics.

F. H. Nuryazmeen

2014-05-01

146

Eelgrass Distribution in the Great Bay Estuary for 2009.  

Science.gov (United States)

Eelgrass in the Great Bay Estuary in 2009 was once again present only in Great Bay itself and in Portsmouth Harbor. For the second year in a row, there was no eelgrass in Little Bay or in the Piscataqua River. In 2009, there was a continued loss of eelgra...

F. T. Short

2010-01-01

147

Eelgrass Distribution in the Great Bay Estuary 2004. Final Report.  

Science.gov (United States)

Eelgrass (Zostera marina) is an essential habitat for the Great Bay Estuary (GBE) because it provides food for wintering waterfowl and habitat for juvenile fish and shellfish. Eelgrass is the basis of an estuarine food chain that supports many of the recr...

F. Short

2006-01-01

148

Eelgrass Distribution in the Great Bay Estuary 2003. Final Report.  

Science.gov (United States)

Eelgrass (Zostera marina) is an essential habitat for the Great Bay Estuary (GBE) because it provides food for wintering waterfowl and habitat for juvenile fish. Eelgrass is the basis of an estuarine food chain that supports many of the recreationally, co...

F. Short

2005-01-01

149

Primary Productivity Regime and Nutrient Removal in the Danube Estuary  

Science.gov (United States)

The primary productivity regime, as well as the distribution of dissolved inorganic nutrients and particulate organic matter in the Danube estuary, were investigated during several cruises at different discharge regimes of the Danube River. The shallowness of the upper surface layer due to insignificant tidal mixing and strong stratification of the Danube estuary, as well as the high nutrient concentrations, are favourable for elevated primary production. The incident light levels at the bottom of the upper surface layer of the water column (0·5-3·0 m) were generally higher than 20% of the surface irradiance. Elevated chlorophyll (Chl) aconcentrations with maxima at mid salinities were found during each survey. Within the upper mixed layer estimated primary production of 0·2-4·4 g m -2day -1is very high compared with estuaries of other major world rivers. Mixing diagrams of dissolved inorganic nutrients reveal removal of significant quantities of nutrients during estuarine mixing. These observations were consistent with the distribution of particular organic matter, which was negatively correlated to the nutrient distribution during each survey. C:Chl aratios, as well as the elevated estimated production, indicate that biological transformation processes govern the nutrient distribution in this estuary.

Humborg, C.

1997-11-01

150

ASSESSING THE ECOLOGICAL CONDITION OF VERACRUZ, MX ESTUARIES  

Science.gov (United States)

As part of an international technology transfer activity between EPA's Office of Research and Development and the state of Veracruz's Sub-secretary of the Environment, 50 stations within estuaries along the gulf coast of the state of Veracruz MX, were sampled during June and July...

151

ASSESSING THE ECOLOGICAL CONDITION OF VERACRUZ, MEXICO ESTUARIES  

Science.gov (United States)

Macauley, John, Hector A. Vasquez, George Craven and P. Thomas Heitmuller. In press. Assessing the Ecological Condition of Veracruz, Mexico Estuaries (Abstract). To be presented at the EPA Science Forum: Healthy Communities and Ecosystems, 1-3 June 2004, Washington, DC. 1 p. (ERL...

152

Buffering of the salinity intrusion in estuaries by channel convergence  

Directory of Open Access Journals (Sweden)

Full Text Available A one-dimensional advective-diffusive model is used to investigate the influence of channel convergence on the runoff-dependence of the distance salt intrudes from the ocean into estuaries. We express the runoff dependence of the dispersion coefficient as K~??, and that of the intrusion extent as xs~??, where ? is the normalized fresh-water discharge into the estuary, and show that ?+?=1 for a prismatic channel. For a channel that is narrower at the river end we find that for relatively low runoff, ?+?<1. Using two decades of salinity observations in the Chesapeake Bay, and Delaware Bay and a shorter data-set for the Connecticut River, we show that channel convergence may contribute significantly to buffering the salinity intrusion. We demonstrate that in a well-mixed estuary with significant convergence, the geometry alone can explain the relatively weak response of the salt intrusion to fluctuations in river discharge. In contrast, a less tapered, but more stratified estuary dominated by gravitational circulation will respond more strongly to runoff fluctuations.

P. S. Gay

2009-09-01

153

[Limitation of Leven Estuary Net Fishing Licences Order.pdf  

…Executive Summary The Environment Agency (North West Region) in exercise of its powers proposes to remove the reducing net limitation order and introduce a new order fixing the Net Fishing Licences of the Leven Estuary, Cumbria to two licences with the introduction of a new Net Fishing Licences Order,…

154

LATITUDINAL GRADIENTS IN BENTHIC COMMUNITY COMPOSITION IN WESTERN ATLANTIC ESTUARIES  

Science.gov (United States)

The community structure of benthic macroinvertebrates from estuaries along the Atlantic coast of North America from Cape Cod, MA, to Biscayne Bay, FL, were compared. Benthic data were collected over a 5 year period (1990 to 1995) by the U.S. Environmental Protection Agency's Envi...

155

An assessment of tidal energy potential. The Lima estuary  

Energy Technology Data Exchange (ETDEWEB)

A hydrodynamic model was set up for the Lima estuary (Portugal) and a preliminary assessment of the strength of tidal currents to produce tidal energy was made. To calibrate the model results were compared with measured data, and the model tuned to reproduce water levels and currents in several locations within the estuary. The data was acquired with ADCPs, during a field campaign that was planed to cover a spring-neap tide cycle, in October 2006. The Advanced Circulation Model - ADCIRC was forced with the most important harmonic constituents present in the ocean tide signal. Upstream, in the river boundary, the discharge was taken from hydrographs. The wetting and drying tool was also applied and a detailed bathymetry was considered, since there are areas in the domain where salt marshes occur, drying out at low tide. The tidal currents potential were assessed for a scenario of tidal forcing only, without any river discharge. The lower estuary is occupied by the port infrastructure and navigation channels which conflicts with any kind of equipment installation. Values of the currents and water depths given by the model indicate that some places in the main channel of the middle estuary, might be interesting to install micro turbines in the future, depending on the evolution of the requirements of this technology.

Trigo-Teixeira, A. [Department of Civil Engineering and Architecture, Instituto Superior Tecnico, Lisbon Technical University, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Rebordao, I. [WW Consulting Engineers, Laveiras, Caxias 2760-032 (Portugal)

2009-07-01

156

Isolation and Characterization of Vibrio vulnificus from Two Florida Estuaries  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Vibrio vulnificus was enumerated in seawater and shellfish from two Florida estuaries at selected seasonal intervals. There were significant fluctuations in the presence and numbers of V. vulnificus. Relatively high seawater temperature and salinity favored the presence of V. vulnificus in both seawater and shellfish samples.

Tamplin, M.; Rodrick, G. E.; Blake, N. J.; Cuba, T.

1982-01-01

157

APPENDIX C - ADDITIONAL INFORMATION ON FLUSHING IN ESTUARIES  

Science.gov (United States)

Water residence time is an important determinant of the sensitivity of the response of estuaries and other water bodies to nutrient loading. A variety of terms such as residence time, flushing time, transit time, turnover time, and age are used to describe time scales for transpo...

158

Water Quantity and Quality Research for the Rhine Meuse Estuary.  

Science.gov (United States)

The effects of boundary conditions and changes in the tidal area on Rhine Meuse estuary water quantity and quality were studied. Tests carried out under cyclic and under time series conditions of several weeks show the importance of the interactions of ha...

A. Roelfzema M. Karelese A. J. Struijk M. Adriaanse

1984-01-01

159

Waterquantity and -Quality Research for the Rhine-Meuse Estuary.  

Science.gov (United States)

In commission of the Dutch Government (Ministry of Public Works), the Delft Hydraulics Laboratory carries out a long term research program on the water quantity and water quality of the Rhine-Meuse estuary. The research program has to provide the necessar...

A. Roelfzema M. Karelse A. J. Struijk M. Adriaanse

1984-01-01

160

CHEMICAL CONSTITUENTS OF AVICENNIA ALBA OF KRISHNA ESTUARY  

Directory of Open Access Journals (Sweden)

Full Text Available Phytochemical investigation on the aerial roots of Avicennia alba of Krishna estuary, resulted in the isolation of four triterpenoids, Lupeol (1, taraxerol (2, betulinic acid (3   and botulin (4. These are characterized by physical and spectral data and all are known compounds but we are reporting first time from this plant. Compound (4 was also possess antibacterial activity.

Ramanjaneyulu MVV* and Venkateswara Rao

2013-12-01

 
 
 
 
161

The dynamics of a frictionally-dominated Amazonian estuary  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A hidrodinâmica, morfologia e sedimentologia do estuário do Taperaçu foram investigadas. Este é um entre vários estuários do litoral amazônico que integram a maior extensão contínua de manguezais do mundo, apresentando uma descarga de água doce muito reduzida, atípica para a região. Os resultados re [...] velam grandes bancos arenosos que ocupam em grande parte a porção central do estuário. Areias muito finas e bem selecionadas de origem marinha prevalecem. Fases de enchente mais curtas, com velocidades de corrente substancialmente mais altas, são observadas na porção superior do estuário, como esperado para um estuário raso e dominado por fricção. Por outro lado, uma vazante mais intensa poderia ocorrer como resultado de grandes áreas de manguezais associadas e intenso preenchimento estuarino, sendo que ambas as condições são observadas no Taperaçu. Neste caso, a prevalência da enchente parece estar associada à ausência de uma descarga fluvial efetiva. Além disso, alguns canais de maré conectam o Taperaçu com seu vizinho estuário do Caeté, o que contribuiria para o domínio de enchente. Como um todo, os resultados demonstram uma complexa interação de aspectos de configuração (fricção, drenagem fluvial, conexões com estuários vizinhos, preenchimento e grandes áreas intermareais) na determinação dos padrões hidrodinâmicos, contribuindo para o entendimento dos estuários da região amazônica. Abstract in english The hydrodynamics, morphology and sedimentology of the Taperaçu estuary were investigated. This is one of several estuaries located within the largest mangrove fringe in the world, bordering the Amazon region, subject to a macrotidal regime and regionally atypical negligible fresh water supply. The [...] results reveal widespread sand banks that occupy the central portion of the estuarine cross-section. Well-sorted very fine sandy sediments of marine origin prevail. Shorter flood phases, with substantially higher current velocities, were observed in the upper sector of Taperaçu, as expected for a shallow, friction-dominated estuary. However, ebb domination can be expected for estuaries with large associated mangrove areas and substantial estuarine infilling, both of which situations occur on the Taperaçu. The tidal asymmetry favoring flood currents could be the result of the absence of an effective fluvial discharge. Furthermore, it was observed that the Taperaçu is connected by tidal creeks to the neighboring Caeté estuary, allowing a stronger flux during the flood and intensifying the higher flood currents. As a whole, the results have shown a complex interaction of morphological aspects (friction, fluvial drainage, connections with neighbor estuaries, infilling and large storage area) in determining hydrodynamic patterns, thus improving the understanding of Amazon estuaries.

Asp, Nils Edvin; Schettini, Carlos Augusto França; Siegle, Eduardo; Silva, Marcio Sousa da; Brito, Roney Nonato Reis de.

162

Temporal changes in physical, chemical and biological sediment parameters in a tropical estuary after mangrove deforestation  

Science.gov (United States)

Dated sediment cores taken near the head and mouth of a tropical estuary, Nha-Phu/Binh Cang, in south central Viet Nam were analyzed for changes over time in physical, chemical and biological proxies potentially influenced by removal of the mangrove forest lining the estuary. A time-series of satellite images was obtained, which showed that the depletion of the mangrove forest at the head of the estuary was relatively recent. Most of the area was converted into aquaculture ponds, mainly in the late 1990's. The sediment record showed a clear increase in sedimentation rate at the head of the estuary at the time of mangrove deforestation and a change in diatom assemblages in the core from the mouth of the estuary indicating an increase in the water column turbidity of the entire estuary at the time of the mangrove deforestation. The proportion of fine-grained sediment and the ?13C signal both increased with distance from the head of the estuary while the carbon content decreased. The nitrogen content and the ?15N signal were more or less constant throughout the estuary. The proportion of fine-grained material and the chemical proxies were more or less stable over time in the core from the mouth while they varied synchronously over time in the core from the head of the estuary. The sediment proxies combined show that mangrove deforestation had large effects on the estuary with regard to both the physical and chemical environment with implications for the biological functioning.

Ellegaard, Marianne; Nguyen, Ngoc Tuong Giang; Andersen, Thorbjørn Joest; Michelsen, Anders; Nguyen, Ngoc Lam; Doan, Nhu Hai; Kristensen, Erik; Weckström, Kaarina; Son, Tong Phuoc Hoang; Lund-Hansen, Lars Chresten

2014-04-01

163

Research, Monitoring, and Evaluation for the Federal Columbia River Estuary Program.  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this document is to describe research, monitoring, and evaluation (RME) for the Federal Columbia River Estuary Program, hereafter called 'the Estuary Program'. The intent of this RME effort is to provide data and information to evaluate progress toward meeting program goals and objectives and support decision making in the Estuary Program. The goal of the Estuary Program is to understand, conserve, and restore the estuary ecosystem to improve the performance of listed salmonid populations. The Estuary Program has five general objectives, designed to fulfill the program goal, as follows: (1) Understand the primary stressors affecting ecosystem controlling factors, such as ocean conditions and invasive species. (2) Conserve and restore factors controlling ecosystem structures and processes, such as hydrodynamics and water quality. (3) Increase the quantity and quality of ecosystem structures, i.e., habitats, juvenile salmonids use during migration through the estuary. (4) Maintain the food web to benefit salmonid performance. (5) Improve salmonid performance in terms of life history diversity, foraging success, growth, and survival. The goal of estuary RME is to provide pertinent and timely research and monitoring information to planners, implementers, and managers of the Estuary Program. The goal leads to three primary management questions pertaining to the main focus of the Estuary Program: estuary habitat conservation and restoration. (1) Are the estuary habitat actions achieving the expected biological and environmental performance targets? (2) Are the offsite habitat actions in the estuary improving juvenile salmonid performance and which actions are most effective at addressing the limiting factors preventing achievement of habitat, fish, or wildlife performance objectives? (3) What are the limiting factors or threats in the estuary/ocean preventing the achievement of desired habitat or fish performance objectives? Performance measures for the estuary are monitored indicators that reflect the status of habitat conditions and fish performance, e.g., habitat connectivity, survival, and life history diversity. Performance measures also pertain to implementation and compliance. Such measures are part of the monitoring, research, and action plans in this estuary RME document. Performance targets specific to the estuary were not included in the 2007 draft Biological Opinion.

Johnson, Gary E.; Diefenderfer, Heida L. (Pacific Northwest National Laboratory)

2008-02-20

164

A lightning climatology of the South-West Indian Ocean  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The World Wide Lightning Location Network (WWLLN) data have been used to perform a lightning climatology in the South-West Indian Ocean (SWIO) region from 2005 to 2011. Maxima of lightning activity were found in the Maritime Continent and southwest of Sri Lanka (>50 fl km?2 yr?1) but also over Madagascar and above the Great Lakes of East Africa (>10–20 fl km?2 yr?1). Lightning flashes w...

Bovalo, C.; Barthe, C.; Be?gue, N.

2012-01-01

165

Seasonal Behaviour of a Shallow Estuary of Lower Cauvery Basin, India  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of bifurcation at the estuary mouth was studied on the measurements of salinity, current and tidal depth in a shallow estuary during spring and neap tides of two different seasons. There was a considerable variation of salinity at the observed stations during the seasons. At the shallowest location of the estuary, salinity, as high as 37 ppt, was observed during the period of zero fresh water discharge. The flushing time of the estuary was higher at its western side compared to the eastern one. The diffusion coefficient was reached by using an advection-diffusion equation. The estuary was classified using a circulation/stratification diagram. Well mixed conditions persisted during pre monsoon and post monsoon in the Muthupet estuary.DOI: http://dx.doi.org/10.5755/j01.erem.61.3.2041

Priya K L

2012-10-01

166

76 FR 15307 - Notice of Staff Attendance at Southwest Power Pool Strategic Planning Committee Meeting  

Science.gov (United States)

...Notice of Staff Attendance at Southwest Power Pool Strategic Planning Committee Meeting The Federal Energy Regulatory...meeting of the Southwest Power Pool, Inc. (SPP) Strategic Planning Committee (SPC), as noted below. Their...

2011-03-21

167

Seasonal incidence of Vibrio vulnificus in the Great Bay estuary of New Hampshire and Maine.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Vibrio vulnificus, a normal bacterial inhabitant of estuaries, is of concern because it can be a potent human pathogen, causing septicemia, wound infections, and gastrointestinal disease in susceptible hosts. From May 1989 through December 1990, oysters and/or water were obtained from six areas in the Great Bay estuary of New Hampshire and Maine. Water was also sampled from three freshwater sites that lead into these areas. V. vulnificus was first detected in the estuary in early July and rem...

O Neill, K. R.; Jones, S. H.; Grimes, D. J.

1992-01-01

168

Mutagenicity and genotoxicity of suspended particulate matter in the Seine river estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Highly mutagenic compounds such as some PAHs have been identified in surface waters and sediments of the Seine river estuary. Suspended particulate matter (SPM) represents a dynamic medium that may contribute to the exposure of aquatic organisms to toxic compounds in the water column of the estuary. In order to investigate major sources of mutagenic contaminants along the estuary, water samples were taken at 25 in downstream of the outlet of an industrial wastewater-treatment plant (WWTP). SP...

Hubert, Francoise; Moisan, Karine; Munschy, Catherine; Tronczynski, Jacek

2012-01-01

169

The Ichthyoplankton of Selected Estuaries in Sarawak and Sabah: Composition, Distribution and Habitat Affinities  

Science.gov (United States)

The ichthyoplankton assemblages of 23 estuaries in Sarawak and Sabah were surveyed with particular reference to the culturally and commercially important clupeid Tenualosa toli. The species composition, distribution and density of all fish larvae were recorded, together with the physical characteristics of each estuary. A more detailed study was made of the Lupar and Lassa estuaries, which are the ' core area ' for T. toli. The estuaries fall into two groups. The first consists of the estuaries of the ' core area ' from the Sebako in the west to the Lassa in the east, and the Labuk and Kinabatangan estuaries of eastern Sabah. They are large and deep, have middle-range salinities with no halocline, are highly turbid and have tidal ranges of >3·5 m and strong currents. There is little seasonal change in freshwater input and their waters are not peat-stained. Their total zooplankton biomasses (approximately 0·05 g m -3dry weight, excluding fish larvae) are an order of magnitude greater than biomasses in the second group of estuaries. The second group consists of all estuaries east of the Lassa as far as the Papar in Sabah. They are mostly smaller, shallower and have more variable salinities than the ' core area ' estuaries, with marked haloclines and seasonal changes in freshwater inflow, lower turbidities, weaker currents, tidal ranges of Sabah estuaries (56 taxa, 26 families) is lower than in most other tropical estuaries of the Indo-west Pacific. This is possibly because of their rigorous physical nature, particularly the very high turbidities and current speeds, or in smaller, less physically rigorous estuaries, the low biomass of zooplankton available as food for the larvae.

Blaber, S. J. M.; Farmer, M. J.; Milton, D. A.; Pang, J.; Boon-Teck, O.; Wong, P.

1997-08-01

170

The contribution of scientific research for integrated coastal management: the Mondego estuary as study case  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present paper quantifies and summarizes the research performed in the Mondego estuary (Portugal) over the last decades. Online databases were used to quantitatively assess the international publications, the master dissertations and PhD theses focused in the research about that estuary, from 1989 to 2012. In general, there had been a notable growth trend in publication output. Estuarine, Coastal and Shelf Science was the most active journal publishing on Mondego estuary. Field studies wer...

Costa, Sonia; Azeiteiro, Ulisses; Pardal, Miguel

2013-01-01

171

Retail Demand Response in Southwest Power Pool  

Energy Technology Data Exchange (ETDEWEB)

In 2007, the Southwest Power Pool (SPP) formed the Customer Response Task Force (CRTF) to identify barriers to deploying demand response (DR) resources in wholesale markets and develop policies to overcome these barriers. One of the initiatives of this Task Force was to develop more detailed information on existing retail DR programs and dynamic pricing tariffs, program rules, and utility operating practices. This report describes the results of a comprehensive survey conducted by LBNL in support of the Customer Response Task Force and discusses policy implications for integrating legacy retail DR programs and dynamic pricing tariffs into wholesale markets in the SPP region. LBNL conducted a detailed survey of existing DR programs and dynamic pricing tariffs administered by SPP's member utilities. Survey respondents were asked to provide information on advance notice requirements to customers, operational triggers used to call events (e.g. system emergencies, market conditions, local emergencies), use of these DR resources to meet planning reserves requirements, DR resource availability (e.g. seasonal, annual), participant incentive structures, and monitoring and verification (M&V) protocols. Nearly all of the 30 load-serving entities in SPP responded to the survey. Of this group, fourteen SPP member utilities administer 36 DR programs, five dynamic pricing tariffs, and six voluntary customer response initiatives. These existing DR programs and dynamic pricing tariffs have a peak demand reduction potential of 1,552 MW. Other major findings of this study are: o About 81percent of available DR is from interruptible rate tariffs offered to large commercial and industrial customers, while direct load control (DLC) programs account for ~;;14percent. o Arkansas accounts for ~;;50percent of the DR resources in the SPP footprint; these DR resources are primarily managed by cooperatives. o Publicly-owned cooperatives accounted for 54percent of the existing DR resources among SPP members. For these entities, investment in DR is often driven by the need to reduce summer peak demand that is used to set demand charges for each distribution cooperative. o About 65-70percent of the interruptible/curtailable tariffs and DLC programs are routinely triggered based on market conditions, not just for system emergencies. Approximately, 53percent of the DR resources are available with less than two hours advance notice and 447 MW can be dispatched with less than thirty minutes notice. o Most legacy DR programs offered a reservation payment ($/kW) for participation; incentive payment levels ranged from $0.40 to $8.30/kW-month for interruptible rate tariffs and $0.30 to $4.60/kW-month for DLC programs. A few interruptible programs offered incentive payments which were explicitly linkedto actual load reductions during events; payments ranged from 2 to 40 cents/kWh for load curtailed.

Bharvirkar, Ranjit; Heffner, Grayson; Goldman, Charles

2009-01-30

172

Desorption of Ba and 226Ra from river-borne sediments in the Hudson estuary  

International Nuclear Information System (INIS)

The pronounced desorption of Ba and 226Ra from river-borne sediments in the Hudson estuary can be explained quantitatively by the drastic decrease in the distribution coefficients of both elements from a fresh to a salty water medium. The desorption in estuaries can augment, at least, the total global river fluxes of dissolved Ba and 226Ra by one and nine times, respectively. The desorption flux of 226Ra from estuaries accounts for 17-43% of the total 226Ra flux from coastal sediments. Two mass balance models depicting mixing and adsorption-desorption processes in estuaries are discussed. (Auth.)

1979-01-01

173

TSUNAMI PROPAGATION ALONG TAGUS ESTUARY (LISBON, PORTUGAL PRELIMINARY RESULTS  

Directory of Open Access Journals (Sweden)

Full Text Available In this study we present preliminary results of flood calculation along Tagus Estuary, a catastrophic event that happened several times in the past, as described in historical documents, and that constitutes one of the major risk sources for Lisbon coastal area. To model inundation we used Mader’s SWAN model for the open ocean propagation with a 2 km grid, and Imamura’s TSUN2 with a 50 m grid covering the entire estuary. The seismic source was computed with the homogeneous elastic half space approach. Modelling results agree with historical reports. Synthetic flood areas correspond to the sites where there are morphological and sedimentary evidences of two known major events that stroke Lisbon: 1531-01-26 and 1755-11-01 tsunamis.

M. A. Viana-Baptista

2006-01-01

174

Multibiomarker assessment of three Brazilian estuaries using oysters as bioindicators  

International Nuclear Information System (INIS)

Oysters have been largely employed as bioindicators of environmental quality in biomonitoring studies. Crassostrea rhizophorae was selected to evaluate the health status of three estuarine areas impacted by anthropogenic activities along the Brazilian coast, in three estuarine complexes, ranging in latitude from 7 to 25 deg. S. In each estuary three sites were sampled in Winter and in Summer: a site considered as reference, and two sites next to contamination sources. Condition index was similar at all sites and estuaries, with the highest values found for Itamaraca oysters in Summer. Necrosis, hyperplasia, mucocyte hypertrophy and fusion of ordinary filaments were the main histopathological lesions observed. Muscle cholinesterase activity was overall similar, but with a strong seasonal effect. Inhibition or activation of branchial total ATPase and Na,K-ATPase activities at the contaminated sites was observed. The health status of these estuarine areas is quite similar, and the combined use of biomarkers is recommended

2007-11-01

175

Mercury bioaccumulation in organisms from three Puerto Rican estuaries.  

Science.gov (United States)

We analyzed mercury levels in shrimp (Palaemonetes sp.), Blue Crabs (Callinectes sp.), fish (Tarpon Megalops atlantica and Tilapia Tilapia mossambica), lizards (Ameiva exsul), Cattle Egret (Bubulcus ibis) and Moorhen (Gallinula chloropus) in three estuaries in Puerto Rico in 1988. There were no quantifiable concentrations greater than the method detection limit of mercury in shrimp, crabs and lizards from any site. Mercury levels were also below detection limits in Tilapia, except for specimens collected at Frontera Creek, allegedly contaminated with mercury. However, mercury levels ranged from 92-238 ?g/kg (wet weight) in Tarpon, a predaceous fish that feeds on smaller fish. Few of the birds had detectable levels of mercury. Our results indicate relatively low concentrations of mercury in biota collected in all of the three estuaries at most trophic levels, although 10 of 12 Tarpon fillet samples from Frontera had detectable mercury compared to 3 of 12 fillet samples for the other two lagoons. PMID:24226951

Burger, J; Cooper, K; Saliva, J; Gochfeld, D; Lipsky, D; Gochfeld, M

1992-09-01

176

Radium and radon in Charlotte Harbor Estuary, Florida  

Science.gov (United States)

Radium-226 and 222Rn activities are greater in the estuarine waters of northern Charlotte Harbor and the lower tidal Peace and Myakka Rivers, Florida, than in either the freshwater reaches of the rivers or waters of the lower estuary and the Gulf of Mexico. The activity of 226Ra in the tidal rivers increases with decreasing river inflow, with a maximum value of 548 dpm 1001 -1 measured in the tidal Myakka River. The source of the high activity of 226Ra and 222Rn is predominantly ground water inflow. Because of the large ground water input, the contribution of 226Ra from suspended and bottom sediments is a smaller fraction of the total 226Ra input than in many other estuaries. Although ground water 226Ra activity in the area varies widely, we estimate that artesian ground water inflow to the tidal rivers is similar in magnitude to the flow of the rivers above the tidal reach during the dry season.

Miller, Ronald L.; Kraemer, Thomas F.; McPherson, Benjamin F.

1990-10-01

177

Contrasting phytoplankton distributions controlled by tidal turbulence in an estuary  

Science.gov (United States)

The vertical distribution of three phytoplankton species was monitored over a complete tidal cycle during daylight hours, with specific reference to estuarine hydrodynamics. The data suggest that pelagic diatoms ( Coscinodiscus spp.) and dinoflagellates ( Prorocentrum micans and Peridinium trochoideum) are able to co-exist by utilising contrasting properties of tidal mixing to develop and reside within the partially mixed estuary, Southampton Water, UK. The data imply that the stability within the water column during slack water periods, permits surface aggregation of dinoflagellates which become homogeneously distributed when turbulence intensifies during ebb and flood currents. Diatoms, conversely, rely on the periods of increased turbulent kinetic energy (TKE) to ensure entrainment into the upper water column and to prevent sinking from the photic zone during stable intervals. The unusual tidal regime for this estuary provides a unique environment to investigate the hydrodynamic properties which influence different phytoplankton groups.

Lauria, Mary Lou; Purdie, Duncan A.; Sharples, Jonathan

1999-06-01

178

Effects of prevailing winds on turbidity of a shallow estuary.  

Science.gov (United States)

Estuarine waters are generally more turbid than lakes or marine waters due to greater algal mass and continual re-suspension of sediments. The varying effects of diurnal and seasonal prevailing winds on the turbidity condition of a wind-dominated estuary were investigated by spatial and statistical analyses of wind direction, water level, turbidity, chlorophyll a, and PAR (Photosynthetically Active Radiation) collected in Lake Pontchartrain, Louisiana, USA. The prolonged prevailing winds were responsible for the long-term, large-scale turbidity pattern of the estuary, whereas the short-term changes in wind direction had differential effects on turbidity and water level in varying locations. There were temporal and spatial changes in the relationship between vertical light attenuation coefficient (Kd) and turbidity, which indicate difference in phytoplankton and color also affect Kd. This study demonstrates that the effect of wind on turbidity and water level on different shores can be identified through system-specific analyses of turbidity patterns. PMID:17617683

Cho, Hyun Jung

2007-06-01

179

Nuclear free security in the South-West Pacific  

International Nuclear Information System (INIS)

Security interests in the South-West Pacific and the proposals for a South Pacific Nuclear Free Zone (SPNFZ) are discussed. The Australian proposals seek to ban the use, testing or stationing of nuclear explosive devices in the South Pacific and to provide that no South Pacific country would develop or manufacture, or receive from others, or acquire or test any nuclear explosive device

1985-01-01

180

Gender Marking in a Dialect of Southwest Spanish.  

Science.gov (United States)

Literature regarding Southwest Spanish suggests gender agreement with nouns is being lost. A study of recorded speech from 11 Spanish speakers in San Antonio (Texas) shows gender agreement is neither random nor largely nonstandard, suggesting gender marking is a rule still observed in this dialect. (Author/MSE)

Garcia, MaryEllen

1998-01-01

 
 
 
 
181

Schistidium sordidum new to Turkey and southwest Asia  

Directory of Open Access Journals (Sweden)

Full Text Available Schistidium sordidum I. Hagen (Grimmiaceae is recorded for the first time in Southwest Asia (Turkey. The specimen was collected in the south (A?r? Mountain of I?d?r province, East Anatolia Region of Turkey. The nearest locality to Turkey for this species is Russia. A site description, illustrations, ecology, distribution and diagnostic characters of the species are presented.

Batan Nevzat

2013-01-01

182

Nontuberculous mycobacteria: incidence in Southwest Ireland from 1987 to 2000.  

LENUS (Irish Health Repository)

SETTING: The Southwest of Ireland (Counties Cork and Kerry) 1987-2000, average population 549,500. OBJECTIVE: Nontuberculous mycobacteria (NTM) cause significant morbidity worldwide and the study of epidemiology and characteristics helps in their prevention and treatment. This study was performed to determine the incidence of NTM disease in comparison to Mycobacterium tuberculosis (M. tuberculosis) and Mycobacterium bovis (M. bovis) in Southwest Ireland, over the above time period. DESIGN: A retrospective study was carried out in all human isolates of NTM, M. tuberculosis and M. bovis between 1987 and 2000, in the Southwest Region of Ireland. RESULTS: The mean incidence of NTM (0.4\\/100,000 population) has risen since 1995, principally of pulmonary Mycobacterium avium intracellulare complex (MAC). The annual incidence of M. tuberculosis in humans over 14 years in the same region was 971\\/100,000 population with a significant reduction since 1994 and M. bovis remained constant at 0.5\\/100,000 population. CONCLUSION: The increasing incidence of disease causing NTM noted in Southwest Ireland reflects global data and is surmised to be due to an ageing population, increased incidence related to chronic fibrotic lung disease, and environmental mycobacterial factors.

Kennedy, M P

2012-02-03

183

Sixth annual environmental management and technology conference, Southwest: Technical papers  

International Nuclear Information System (INIS)

This conference was held November 1--3, 1994 in Houston, Texas as part of the Environmental Management and Technology Conference and Exhibition/Southwest. The purpose of the conference was to provide a forum for exchange of information on environmental hazardous waste management. Individual papers are processed separately for inclusion in the appropriate data bases

1994-11-01

184

Environmental restoration of the Guadiaro river estuary, Cadiz (Spain)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

During 1998, the Spanish Ministry of Environmental Protection has developed the restoration of the Guadiaro estuary, near the Strait of Gibraltar, through the Coastal General Directorate. The main environmental problems, amongst others, detected at the area were a high eutrophication level of the estuarine waters and fish mortality mainly due to the low summer river effluent, the urban sewage inputs and no tidal renovation caused by the blockage of the sand bar at the mouth...

La Casa, A?ngel; Gomez-pina, Gregorio; Acha Martin, Antonio; Mun?oz-perez, Juan J.

2000-01-01

185

Estuaries from a meiofaunal perspective: biodiversity patterns of benthic nematodes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Estuarine meiofauna communities have been only recently considered to be good indicators of ecological quality status, in contrast with macrofauna which is widely used in the assessment and monitoring of aquatic systems. Meiofauna features, such as their small size, high abundance, rapid generation times and absence of a planktonic phase, make these assemblages potential target indicators. In estuaries, we must account not only for great natural variability (e.g. salinity, sediment type and d...

Alves, Ana; Ada?o, Helena; Ferrero, T. J.; Costa, M. J.; Marques, J. C.; Patricio, J.

2012-01-01

186

Hydrodynamic modelling for Mondego estuary water quality management  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The south arm of Mondego estuary, located in the central western Atlantic coast of Portugal, is almost silted up in the upstream area. So, tides, wind and the tributary river Pranto discharges mostly drive the water circulation in this system. Annual fresh water inflow, regulated by precipitation and by sluice management practices, has a significant impact on flow velocity, salinity, N:P ratios and light extinction coefficients, which interaction controls biomass growth and loss processes. Eu...

Duarte, Anto?nio A. L. Sampaio; Pinho, Jose? L. S.; Pardal, Miguel A. C.; Neto, Joa?o M.; Vieira, J. M. Pereira; Santos, Fernando S.

2002-01-01

187

Clostridium botulinum type C in the Mersey estuary.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nineteen of 98 samples of mud or sand taken from the Mersey estuary in 1981 contained Clostridium botulinum type C, the organism almost always responsible for botulism in water birds. In the Dungeon and Score Bank areas, where many dead and dying birds were found during the period September-December 1979, almost half the samples contained type C. Most of the positive samples were essentially muddy rather than sandy. The findings do not prove that botulism contributed to the 1979 mortality but...

Smith, G. R.; Oliphant, J. C.; White, W. R.

1982-01-01

188

Effects of wave forcing on a subterranean estuary  

Science.gov (United States)

Wave and tide are important forcing factors that typically coexist in coastal environments. A numerical study was conducted to investigate individual and combined effects of these forces on flow and mixing processes in a nearshore subterranean estuary. A hydrodynamic model based on the shallow water equations was used to simulate dynamic sea level oscillations driven by wave and tide. The oscillating sea levels determined the seaward boundary condition of the coastal aquifer, where variably saturated, variable density flow was modeled. The simulation results showed that waves induced an onshore upward tilt in the phase-averaged sea level (wave setup). The resulting hydraulic gradient generated pore water circulations in the nearshore zone of the coastal aquifer, which led to formation of an upper saline plume (USP) similar to that formed due to tides. However, mixing of recirculating seawater in the USP with underlying fresh groundwater was less intensive under the high-frequency wave oscillations. In the case of combined forcing, wave-induced circulations coupled with the intratidal flows strengthened the averaged, circulating pore water flows in the nearshore zone over the tidal period. The circulating flows increased exchange between the subterranean estuary and ocean, contributing 61% of the total submarine groundwater discharge for the simulated condition in comparison with the 40% and 49% proportions caused by the same but separate tidal and wave forcing, respectively. The combined forces also created a more extensive USP with the freshwater discharge zone shifted farther seaward. The freshwater flow paths in the intertidal subterranean estuary were modified with a significant increase in the associated transit times. The interplay of wave and tide led to increased mixing between discharging fresh groundwater and recirculating seawater. These results further demonstrate the complexity of nearshore groundwater systems and have implications for future investigations on the fate of land-sourced chemicals in the subterranean estuary prior to discharge to the ocean.

Xin, Pei; Robinson, Clare; Li, Ling; Barry, D. A.; Bakhtyar, R.

2010-12-01

189

Trace elements distribution in bottom sediments from Amazon River estuary  

International Nuclear Information System (INIS)

The Amazon River discharges into a dynamic marine environment where there have been many interactive processes affecting dissolved and particulate solids, either those settling on the shelf or reaching the ocean. Trace elemental concentration, especially of the rare earth elements, have been determined by neutron activation analysis in sixty bottom sediment samples of the Amazon River estuary, providing information for the spatial and temporal variation study of those elements. (author). 16 refs, 6 figs, 3 tabs

1994-09-02

190

Summary of implementation and demonstration projects in bays and estuaries  

International Nuclear Information System (INIS)

The projects investigated include demonstration projects as well as unique programmatic initiatives of 15 bays and estuaries and are divided into 11 separate project categories: Boat and Marine Wastes; Contaminated Sediments; Land Use and Development Controls; Local Government and Community Involvement; Nutrient Loading; On-site Disposal Systems; Public Outreach and Education; Shellfish Bed Protection and Restoration; Stormwater Controls; Toxic Waste Reduction; Wetlands/Habitat Protection and Restoration

1992-01-01

191

Effects of Prevailing Winds on Turbidity of a Shallow Estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Estuarine waters are generally more turbid than lakes or marine waters due to greater algal mass and continual re-suspension of sediments. The varying effects of diurnal and seasonal prevailing winds on the turbidity condition of a wind-dominated estuary were investigated by spatial and statistical analyses of wind direction, water level, turbidity, chlorophyll a, and PAR (Photosynthetically Active Radiation) collected in Lake Pontchartrain, Louisiana, USA. The prolonged prevailing winds were...

Hyun Jung Cho

2007-01-01

192

Distribution of endocrine disruptors in the Mondego River estuary, Portugal  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Recent studies in the Mondego River estuary demonstrated signs of pollution in the area, but the nature of the contamination remains unexplored. Because there seems to be any studies in that zone checking for the simultaneous presence of xenoestrogenic endocrine disrupting compounds, either of animal (estradiol and estrone), vegetal (daidzein, genistein and biochanin A), pharmaceutical (17a-ethynylestradiol) or industrial (bisphenol A, 4-octylphenol, 4-nonylphenol) origins, the main...

Ribeiro, Cla?udia; Pardal, Miguel; Martinho, Filipe; Margalho, Rui; Tiritan, Maria; Rocha, Eduardo; Rocha, Maria

2008-01-01

193

Habitat Scale Mapping of Fisheries Ecosystem Service Values in Estuaries  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Little is known about the variability of ecosystem service values at spatial scales most relevant to local decision makers. Competing definitions of ecosystem services, the paucity of ecological and economic information, and the lack of standardization in methodology are major obstacles to applying the ecosystem-services approach at the estuary scale. We present a standardized method that combines habitat maps and habitat–faunal associations to estimate ecosystem service values for recr...

Higgins, Timothy G. O.; Ferraro, Steven P.; Dantin, Darrin D.; Jordan, Steve J.; Chintala, Marnita M.

2010-01-01

194

Spatial modeling on the nutrient retention of an estuary wetland  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There is a great potential to use the estuary wetland as a final filter for nutrient enriched river water, and reduce the possibility of coastal water eutrophication. Based upon field data, spatial models were designed on a stepwise basis to simulate the nutrient reduction function of the wetland in the Liaohe Delta. The model contained two major subsystems: the canal system and the reed field. In the preliminary model, a non-linear regression model was established for the nutrient reduction ...

Li, X.; Xiao, D.; Jongman, R. H. G.; Harms, W. B.; Bregt, A. K.

2003-01-01

195

Possible estuary-associated syndrome: symptoms, vision, and treatment.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The human illness designated as possible estuarine-associated syndrome (PEAS) by the Centers for Disease Control and Prevention (CDC) has been associated with exposure to estuaries inhabited by toxin-forming dinoflagellates, including members of the fish-killing toxic Pfiesteria complex (TPC), Pfiesteria piscicida and Pfiesteria shumwayae. Humans may be exposed through direct contact with estuarine water or by inhalation of aerosolized or volatilized toxin(s). The five cases reported here dem...

Shoemaker, R. C.; Hudnell, H. K.

2001-01-01

196

Local flows in the Quequen Grande River Estuary, Argentina  

International Nuclear Information System (INIS)

Quequen Grande River is one of the most important water courses of Buenos Aires Province due to the economic and strategic significance of its estuary, where the populous Quequen-Necochea area and Quequen Port are located. The minor Las Cascadas falls, at 15 km from the place where the river meets the sea is the point where the maximum tidal propagation is detected marking the head of the estuary. Artificial dredging is needed to insure the adequate navigability conditions in the Quequen harbour, which has induced a highly stratified water column in the last 2 km of the estuary. Thus, an abrupt step is established at the head of the harbour, implying a much reduced water circulation and in some cases nonexistent, producing strong reductive and even anoxic conditions. The foot of the step is a sediment and organic matter trap and becomes an interesting place of study. The goal of this article is to present the information obtained with Doppler sonar at the neighborhood of the step, which allows distinguishing local turbidity currents that may influence the deposition patterns of the sediments.

2009-05-01

197

High-resolution simulations of a macrotidal estuary using SUNTANS  

Science.gov (United States)

The parallel, finite-volume, unstructured-grid SUNTANS model has been employed to study the interaction of the tides with complex bathymetry in the macrotidal Snohomish River estuary. The unstructured grid resolves the large-scale, O(10 km) tidal dynamics of the estuary while employing 8 m grid-resolution at a specific region of interest in the vicinity of a confluence of two channels and extensive intertidal mudflats to understand detailed local intratidal flow processes. After calibrating tidal forcing parameters to enforce a match between free surface and depth-averaged velocities at several locations throughout the domain, we analyze the complex dynamics of the confluence and show that the exposure of the intertidal mudflats during low tide induces a complex flow reversal. When coupled with the longitudinal salinity gradient, this flow reversal results in a highly variable salinity field, which has profound implications for local mixing, stratification and the occurrence of fine-scale flow structures. This complex flow is then used as a testbed from which to describe several challenges associated with high resolution modeling of macrotidal estuaries, including specification of high resolution bathymetry, specification of the bottom stress, computation of the nonhydrostatic pressure, accurate advection of momentum, and the influence of the freshwater inflow. The results indicate that with high resolution comes the added difficulty of requiring more accurate specification of boundary conditions. In particular, the bottom bathymetry plays the most important role in achieving accurate predictions when high resolution is employed.

Wang, B.; Fringer, O. B.; Giddings, S. N.; Fong, D. A.

198

Sediment transport and morphodynamics of the Douro River estuary  

Science.gov (United States)

A combination of dredging data, hydrographic surveys and numerical modelling has been used to assess morphological change and sediment transport in the Douro River estuary. The system is dominated by sand- and gravel-sized sediments and confined by resistant rock types. The evolution of the bed in the last 20 years has been strongly influenced by the opening of a navigation channel. According to the data available to date, the average maintenance dredging volume has been of the order of 0.4 × 106 m3 year-1. Comparisons of hydrographic surveys reveal a rate of volume loss of the same magnitude. Apparently, maintenance dredging mainly involves local material, transported into the channel from shallower areas of the estuary. The results of numerical modelling indicate that the sediment transport capacity due to tidal currents is very limited. River flood events increase the transport capacity by several orders of magnitude, thus playing a critical role in sediment redistribution and supply to the coast. The average sediment transport capacity is estimated to be of the order of 0.1 × 106 m3 year-1 in most of the estuary and 0.5 × 106 m3 year-1 at the inlet, with a large uncertainty. It is concluded that, if morphological stability is set as an environmental objective, the dredged material should not be removed from the system but rather be used to nourish the estuarine beaches and the barrier spit.

Portela, Luís Ivens

2008-04-01

199

Holocene deltaic sequence in the Saloum estuary, Senegal  

Science.gov (United States)

The 2250 km 2 Saloum delta, south of Dakar, Senegal, consists of a Holocene sedimentary sequence deposited during five evolutionary stages: submerged postglacial ria, funnel-like estuary, barred estuary, cuspate delta, and reverse estuary. The passage from one stage to another was marked by the deposition of sedimentary units consisting of shelly sands, silty or sandy clays, and an extensive thick green mud. Muds in the lower strata, dating between 6130 and 3500 yr B.P., were deposited on a subtidal mudflat, while fine sands and silty clays characterize intertidal deposits. A drastic change in sedimentation patterns, resulting in the accumulation of a series of beach barriers, likely was associated with a major climatic change. The regional climate was then very dry, and silt and sand were trapped in the water behind the barriers in two stages, from 1990 to 1510 and 1020 to 600 yr B.P. Each event was accompanied by construction of shell middens that demonstrate the presence of humans who exploited newly available shallows and banks. Relative sea level did not change significantly between 6000 yr B.P. and the present. Morphological and sedimentological changes observed in the late Holocene sequences were apparently induced by a constraining climatic background.

Ausseil-Badie, Josiane; Barusseau, J. Paul; Descamps, Cyr; Salif Diop, E. H.; Giresse, Pierre; Pazdur, Mieczyslaw

1991-09-01

200

[Spatiotemporal changes of fish community in Yangtze estuary intertidal zone].  

Science.gov (United States)

Based on the 36 fish samplings at 4 stations in the intertidal zone of Yangtze estuary from March to November 2006, the spatial and temporal changes of the fish community were analyzed. A total of 55 fish species belonging to 20 families were collected. Cyprinid had the largest species number (18 species), followed by Gobiidae (8 species), and Sciaenidae (4 species). The intertidal fish community was classified into brackish water and freshwater groups. Brackish water group had somewhat lower diversity than freshwater group. In the estuary mouth, the dominant species were of brackish-water fishes, including Acanthogobius ommaturus, Mugil cephalus and Collichthys lucidus, etc.; in the inner estuary, freshwater fishes were dominant, including Hemiculter bleeleri, Pseudobrama simony, and Parabramis pekinensis. The average dissimilarity between the two groups reached 80.75%, and the accumulative contribution of 23 fish species was more than 90%, mainly coming from Hemiculter bleeleri, Acanthogobius ommaturus, Mugil cephalus, Collichthys lucidus, Pseudobrama simony, Parabramis pekinensis, Saurogobio dumerili, and Odontamblyopus rubicundus. The abundance of fish assemblages in spring differed from that in summer and autumn to certain extent, but the abundance in summer and autumn had little differences. For each of the two groups, the abundance was more affected by water temperature than by water salinity; for the whole fish community, opposite situation was observed. PMID:20077714

Zhang, Heng; Zhu, Guo-Ping

2009-10-01

 
 
 
 
201

Numerical Modeling of Groundwater Seepages to River/Estuary Systems  

Science.gov (United States)

An integrated model is developed to simulate seepages from groundwater to river/estuary systems. The model includes a one-dimensional flow module for river/estuary networks and a two-dimensional groundwater flow module for subsurface media. The former was adapted from the one-dimensional module in a watershed model, WASH123D, and the latter was obtained by modifying an existing vertically averaged groundwater flow model, FEWA. The modeling system was applied to St. Lucie Estuary (SLE) to estimate seepages. The seepage measurement data on four seepage-meter transect sites in St. Lucie River were calibrated with results of the computational model. In addition, the computational model results were compared with those of analytical model on seepage meter sites. The model was then applied to predict the groundwater seepage flux into SLE due to interaction between aquifer and river domain during multiple-year period. Seven types of statistics of calibration indicated that the numerical models have improved over the analytical models. Therefore, it should be expected that the forty-year predictions are an improvement over the previous analytical calculations.

Yeh, G.; Lee, J.; Hu, G.; Sun, D.

2009-12-01

202

Analysis of CMIP5 Historical Runs for Southwest US Precipitation  

Science.gov (United States)

Decadal changes in southwest US precipitation may have profound consequences on agriculture and water resource management. Therefore, in order to investigate the potential for future predictability, we examine historical runs from the CMIP5 archive to evaluate model performance against the present climate. We focus on mechanisms linked to decadal variations in southwest US precipitation, and the occurrence of long-term drought. Precipitation in the southwest US is dominated by mesoscale convective activity from the south during the summer monsoon season, and large-scale storms crossing the central US west coast during winter. Precipitation climatology varies between the CMIP5 models in the summer, due to shifts in the location of the monsoon ridge and the timing of the reversal of the low-level winds. Varied results are also seen in 20th Century Reanalysis V2, ECMWF 40 Year Reanalysis, and GPCC gauge precipitation data, due to the difficulty in capturing thunderstorm activity during this season. The CMIP5 models and data sets are more consistent in winter, due to their ability to represent the characteristics of large-scale coastal storms. Higher than average precipitation in the southwest US on decadal timescales is generally associated with low pressure anomalies over the northern Pacific Ocean and southern US, and high pressure anomalies over northern North America. These pressure anomalies are in turn associated with cool north Pacific Ocean SST anomalies, and warmer than usual equatorial Pacific Ocean SSTs. These warm anomalies extend northwards along the west coast of Mexico and the US in winter. This evidence of an atmospheric bridge between SST anomalies in the Pacific Ocean and southwest US precipitation may be useful in predicting decadal drought in the Great Basin region if the SST anomalies are predictable on long timescales.

Langford, S.; Noone, D. C.

2012-12-01

203

Variation in tidal wetland plant diversity and composition within and among coastal estuaries: assessing the relative importance of environmental gradients  

Science.gov (United States)

Question: Does wetland plant composition vary more by estuarine type (differentiated by the degree of riverine versus oceanic influence) or habitat type within estuaries (defined by US National Wetlands Inventory [NWI] marsh classes)? Location: Oregon estuaries: Netarts Bay, Yaq...

204

Spartina maritima influence on the dynamics of the phosphorus sedimentary cycle in a warm temperate estuary (Mondego estuary, Portugal)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract During the last decades the Mondego estuary has been under severe ecological stress mainly caused by eutrophication. In this salt march system, Spartina maritima covers about 10.5 ha of the intertidal areas. The objective of the present study was to evaluate the effect of Spartina maritima marshes on the dynamics of phosphorus (P) binding in the surface sediment. We compare phosphate and oxygen fluxes, P-adsorption capacity, phosphate concentrations and total amount, and the extract...

Lillebø, Ana; Coelho, J.; Flindt, M.; Jensen, H.; Marques, J.; Pedersen, C.; Pardal, M.

2007-01-01

205

Measurement frequency and sampling spatial domains required to characterize turbidity and salinity events in the Guadalquivir estuary (Spain)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Estuaries are complex systems in which long water quality data series are not always available at the proper scale. Data proceeding from several water quality networks, with different measuring frequencies (monthly, weekly and 15 min) and different numbers of sampling points, were compared throughout the main channel of the Guadalquivir estuary. Higher frequency of turbidity sampling in the upper estuary is required. In the lower estuary, sampling points help to find out the...

Contreras, E.; Polo, M. J.

2012-01-01

206

E-estuary: A Decision Support System for Coastal Water and Ecosystem Management in the US (CZ09)  

Science.gov (United States)

Ready access to geographic information is needed to support management decisions for estuaries at local, state, regional, and national scales. The U.S. Environmental Protection Agency (US EPA) is developing e-Estuary, a decision-support system for coastal management. E-Estuary ...

207

E-Estuary: Developing a Decision Support System for Coastal Management in the Conterminous United States (IAHR)  

Science.gov (United States)

Ready access to geographic information is needed to support management decisions for estuaries at local, state, regional, and national scales. The U.S. Environmental Protection Agency (US EPA) is developing e-Estuary, a decision-support system for coastal management. E-Estuary ...

208

Retrospective study of metal contamination time trends in the French part of the Bay of Biscay  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two cores were sampled in the Bay of Biscay: one a few miles off the Gironde estuary (pointe de la Coubre), the other near the Spanish border (Capbreton canyon) to study past variations in sediment contamination. Radiochronology (210Pb, 137Cs) and total metal determinations by ICP-MS allowed the study of time trends for metal concentrations in sediment. Off the Gironde, during the time interval recorded by the core (1958–1999), all metal concentrations remained less than OSPAR background va...

Boutier, Bernard; Quintin, Jean-yves; Rozuel, Emmanuelle; Auger, Dominique; Bretaudeau-sanjuan, Jane

2011-01-01

209

The Application of a Segmented Tidal Mixing Model to the Great Bay Estuary, N.H.  

Science.gov (United States)

The Great Bay Estuarine System has a very complex geometry. Measurements show that in general salt is vertically well-mixed everywhere in the estuary except near the river entrances at the head of the estuary. Dyer and Taylor's (1973) modified version of ...

W. S. Brown E. Arrelano M

1979-01-01

210

Long-term morphological change and its causes in the Mersey Estuary, NW England  

Science.gov (United States)

Changes in the morphology of the Mersey Estuary, and their possible causes, have been investigated using Historical Trend Analysis and Expert Geomorphological Assessment. Historical bathymetric charts were digitised and analysed within a GIS to provide quantitative estimates of changes in areas and sediment volumes above and below selected elevation planes. The results show that the estuary experienced major changes over the last 150 years, notably between the late 19th century and ca. 1950. An analysis of data relating to possible natural and human factors which could have influenced these changes suggests that training wall construction and dredging in the Outer Estuary and Liverpool Bay was the most significant factor contributing to change during this period. These activities modified the hydrodynamic and sediment transport regime in a way which enhanced an existing natural tendency for movement of sediment from Liverpool Bay and the Outer Estuary into the Inner Estuary. Changes in other factors, including sea level, tidal range, wind/wave climate, freshwater flow and embanking/land reclamation, were of relatively minor importance. Between 1950 and 1977 the rate of sediment accumulation in the Inner Estuary declined as the estuary approached a new condition of dynamic equilibrium, and since 1977 there has been a slight net loss of sediment. Under these conditions the changes in natural forcing factors, such as sea level and storminess, are likely to have a relatively greater effect on the estuary than in the past.

Blott, Simon J.; Pye, Kenneth; van der Wal, Daphne; Neal, Adrian

2006-11-01

211

Second international symposium on the biogeochemistry of model estuaries: Estuarine processes in global change  

Energy Technology Data Exchange (ETDEWEB)

This report consists of abstracts of papers presented at the symposium of Biogeochemistry. The main topics discussed at the meeting are; nutrient and mineral cycling, trace element distribution, sources and sinks of estuaries, sedimentation, importance of organic matter, and other biogeochemical processes of estuaries.

1991-12-31

212

Liver oxidative stress of the grey mullet Mugil cephalus presents seasonal variations in Ennore estuary  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The objective of this study was to determine the liver oxidative stress status of grey mullets living in heavy-metal-rich polluted Ennore estuary compared with unpolluted Kovalam estuary. Fish were collected from both estuaries during the monsoon and summer seasons from October 2004 to September 200 [...] 6. Fish liver homogenate (N = 20 per group) was prepared for evaluating oxidative stress parameters. Fish living in the polluted estuary had significantly higher lipid oxidation products, conjugated dienes (0.346 ± 0.017 vs 0.141 ± 0.012 DA233/mg protein), lipid hydroperoxides (0.752 ± 0.032 vs 0.443 ± 0.03 nmol/mg protein), and lipid peroxides (3.447 ± 0.14vs 1.456 ± 0.096 nmol MDA/mg protein) than those of the unpolluted estuary during the summer. In contrast, significantly lower levels of superoxide dismutase (20.39 ± 1.14 vs 53.63 ± 1.48 units/mg protein) and catalase (116 ± 6.87vs 153 ± 8.92 units/mg protein) were detected in the liver of fish from the polluted estuary (Ennore) compared to fish from the unpolluted estuary (Kovalam) during the summer. Variations in most of the oxidative stress parameters were observed between the summer and monsoon seasons, indicating the importance of seasonal variation for estuaries and their inhabitants.

E., Padmini; B., Vijaya Geetha; M., Usha Rani.

213

Liver oxidative stress of the grey mullet Mugil cephalus presents seasonal variations in Ennore estuary  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this study was to determine the liver oxidative stress status of grey mullets living in heavy-metal-rich polluted Ennore estuary compared with unpolluted Kovalam estuary. Fish were collected from both estuaries during the monsoon and summer seasons from October 2004 to September 2006. Fish liver homogenate (N = 20 per group was prepared for evaluating oxidative stress parameters. Fish living in the polluted estuary had significantly higher lipid oxidation products, conjugated dienes (0.346 ± 0.017 vs 0.141 ± 0.012 DA233/mg protein, lipid hydroperoxides (0.752 ± 0.032 vs 0.443 ± 0.03 nmol/mg protein, and lipid peroxides (3.447 ± 0.14vs 1.456 ± 0.096 nmol MDA/mg protein than those of the unpolluted estuary during the summer. In contrast, significantly lower levels of superoxide dismutase (20.39 ± 1.14 vs 53.63 ± 1.48 units/mg protein and catalase (116 ± 6.87vs 153 ± 8.92 units/mg protein were detected in the liver of fish from the polluted estuary (Ennore compared to fish from the unpolluted estuary (Kovalam during the summer. Variations in most of the oxidative stress parameters were observed between the summer and monsoon seasons, indicating the importance of seasonal variation for estuaries and their inhabitants.

E. Padmini

2008-11-01

214

Limitation of Kent Estuary Net Fishing Licences Order, 2003 (2012 Review)  

…existing restrictions on the Net Fishing Licences of the Kent Estuary, Cumbria with the introduction of a new Net Fishing Licences Order, 2013. This paper sets out the case for reducing the number of available lave net licences on the Kent Estuary from 8 to 6 with a recommendation for an early 5 year review…

215

The effect of interacting downstream branches on saltwater intrusion in the Modaomen Estuary, China  

Science.gov (United States)

In recent years, the increased pressure of saltwater intrusion in the Modaomen Estuary, one of the outlets in the Pearl River Delta (PRD), China, has threatened the freshwater supply for the surrounding regions. The estuary has complex geometry and bathymetry and branches into three waterways, Madaomen Waterway, Hongwan Waterway, and Hezhou Waterway, entering into the coastal sea. In this study, a three-dimensional baroclinic model (EFDC) was used to investigate salt transport among these branches and saltwater intrusion in the mainstem of the estuary. The salt transport at selected cross sections was decomposed into three components: advection, steady shear, and tidal oscillatory, following the method of Lerczak et al. (Lerczak, J.A., Geyer, W.R., Chant, R.J., 2006. Mechanisms driving the time-dependent salt flux in a partially stratified estuary. Journal of Physical Oceanography 36, 2296-2311). Results from this study indicate that the Hongwan Waterway serves as a salt source for the mainstem of the estuary, especially during spring tides, while the Hezhou Waterway mainly acts as a salt sink for the mainstem. The down-estuary wind increases the steady shear transport in the Modaomen Waterway and the advection transport in the Hongwan Waterway, which alters the saltwater intrusion in the estuary. Closure of the Hongwan and the Hezhou Waterways could result in a 20% decrease of saltwater intrusion in the estuary. These results provide scientific basis for water resource management in the region.

Gong, Wenping; Wang, Yaping; Jia, Jianjun

2012-02-01

216

Simulating Suspended Silt Concentrations in the Ems Estuary, The Netherlands  

Science.gov (United States)

1 Introduction The Ems Estuary is situated in the North-east Netherlands on the border with Germany. Its area, including the tidal river and excluding the outer delta, is ± 500 km2. The area of the outer delta is ± 100 km2. The length of the estuary from the inlet to the town of Leer in Germany is approximately 75 km. The mean tidal range varies over years (de Jonge, 1992), but is approximately 2.3 m near the island of Borkum (tidal inlet) and approximately 3.2 m near the town of Emden in Germany. The estuary receives water from the rain-fed River Ems (approximately 115 m3/s on average). A second much smaller freshwater input emanates from the small canalized river Westerwoldsche Aa (12.5 m3/s on average). These discharges vary strongly within and between years. The result of the interaction between freshwater discharge and seawater brought in by the tide is a salinity gradient, the length and position of which is strongly dependent on the water discharge by the rivers. The present morphology of the estuary is the result of natural processes such as tidal currents, wind and wave driven currents and river discharge, resulting in sediment trans-port and sedimentation and erosion patterns. These natural processes are affected by human interferences like maintenance dredging of the navigation channels, land reclamation, building of dikes, etc. The greatest changes in the last 50 years in the physical functioning of the Ems estuary have been the increased sea level and tidal range, the increased amplitude and frequency of storm surge, and greatly increased turbidity and sediment concentrations (particularly near the estuarine turbidity maximum). Much of the changes can be traced directly or indirectly to anthropogenic influence. 2 Aim and approach We studied the hydrodynamics and morphodynamics of the Ems estuary. One of the aims was to gain more insight in the behaviour of the suspended silt concentrations in the estuary and the anthropogenic influence thereon. We applied a beta release of the state-of-the-art Delft3D numerical model for this purpose. The model includes a new sediment transport module published by Van Rijn (2007, 2007a). The vertical distribution of the suspended sediment concentration in the transport module depends on the effective settling velocity of the sediment, the bed shear velocity and the turbulence. The silt transport is simulated every time step together with the flow (online), which means that the impact of the calculated concentration is accounted for in the hydrodynamics. Major challenge was to accurately simulate the relatively high suspended silt concentrations observed near the estuarine turbidity maximum. 3 Results The paper will compare observed and predicted water levels, salinity distributions and suspended silt concentrations. Figure 1 shows an example of predicted depth-averaged suspended silt concentrations during spring high tide without waves. Under these conditions the depth-averaged concentrations decrease from about 2 kg/m3 in the Unterems (upstream of Emden) to almost zero seaward of Borkum. PIC Figure 1: Figure 2 Observed and predicted salinities in the upper part of the water column along the estuary The presence of waves will increase the concentrations on the shoals but have a limited effect on the concentrations in the channels. Figure 2 presents observed and predicted salinities along the estuary. The model results encouragingly agree with the observations. PIC 4 References De Jonge, V.N., 1992. Tidal flow and residual flow in the Ems estuary. Estuarine, Coastal and Shelf Science, 34: 1-22. Van Rijn, L.C., 2007. Unified View of Sediment Transport by Currents and Waves. I: Initiation of Motion, Bed Roughness, and Bed-Load Transport. Journal of Hydraulic Engineering, 133(6): 649-667. Van Rijn, L.C., 2007a. Unified View of Sediment Transport by Currents and Waves. II: Suspended Transport. Journal of Hydraulic Engineering, 133(6): 668-689.

Grasmeijer, B. T.

2009-04-01

217

Heavy Metals (Cd, Cu, Cr, Pb and Zn) in Meretrix meretrix Roding, Water and Sediments from Estuaries in Sabah, North Borneo  

Science.gov (United States)

Concentrations of heavy metals (Cd, Cu, Cr, Pb and Zn) in tissues of Meretrix meretrix Roding (M. meretrix R.), water and sediments from two estuaries were determined. One estuary is located in an urban area of Kota Kinabalu (Likas estuary) and the other in a rural district of Kota Belud (Kota Belud estuary), where both are in Sabah, North of…

Abdullah, Mohd. Harun; Sidi, Jovita; Aris, Ahmad Zaharin

2007-01-01

218

Coastal upwelling along the southwest coast of India – ENSO modulation  

Directory of Open Access Journals (Sweden)

Full Text Available An index of El Niño Southern Oscillation (ENSO in the Pacific during pre monsoon is shown to account for a significant part of the variability of coastal Sea Surface Temperature (SST anomalies measured a few months later within the wind driven southwest coast of India coastal upwelling region 7° N–14° N. This teleconnection is thought to result from an atmospheric bridge between the Pacific and north Indian Oceans, leading to warm (cold ENSO events being associated with relaxation (intensification of the Indian trade winds and of the wind-induced coastal upwelling. This ENSO related modulation of the wind-driven coastal upwelling appears to contribute to the connection observed at the basin-scale between ENSO and SST in the Arabian Sea. The ability to use this teleconnection to give warning of large changes in the southwest coast of India coastal upwelling few months in advance is successfully tested using data from 1998 and 1999 ENSO events.

K. Muni Krishna

2008-04-01

219

An examination of Southwest Pacific explosive cyclones, 1989 to 2009  

International Nuclear Information System (INIS)

This study has assembled a climatology of Southwest Pacific explosively developing cyclones, based on the European Centre for Medium-Range Weather Forecasts' ERA-Interim reanalysis data, over the 21-year period from 1989 to 2009. The recently developed 'combined explosive' expression, a refinement of the 'relative explosive' criterion, was used to identify cyclones deemed explosive with respect to both the drop in central pressure and the climatological pressure gradient. Over the period of analysis, 47 explosive cyclones were identified within the Southwest Pacific, equating to an average of 2.2 explosive events per year. Seasonally, explosive cyclones are most frequent during the winter months, while least frequent during the summer. Two case explosive systems are briefly considered, with their corresponding measures of intensity and scale placed into climatological perspective.

2010-08-01

220

Geothermal development in southwest Idaho: the socioeconomic data base  

Energy Technology Data Exchange (ETDEWEB)

This report inventories, analyzes, and appraises the existing socioeconomic data base for the ten counties in southwest Idaho that would be impacted by any significant geothermal development. The inventory describes key sociological demographic, and economic characteristics, and presents spatial boundaries, housing data, and projections of population and economic activity for the counties. The inventory identifies the significant gaps in the existing data base and makes recommendations for future research.

Spencer,S.G.; Russell, B.F. (eds.)

1979-09-01

 
 
 
 
221

Geothermal development in southwest Idaho: the socioeconomic data base  

Energy Technology Data Exchange (ETDEWEB)

This report inventories, analyzes, and appraises the exiting socioeconomic data base for the ten counties in southwest Idaho that would be impacted by any significant geothermal development. The inventory describes key sociological demographic, and economic characteristics, and presents spatial boundaries, housing data, and projections of population and economic activity for the counties. The inventory identifies the significant gaps in the existing data base and makes recommendations for future research.

Spencer, S.G.; Russell, B.F.

1979-09-01

222

The Road to Maternal Death In Rural Southwest Ethiopia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The study explored cultural beliefs and practices contributing to maternal deaths together with maternal deaths reviews as testimonial. Six maternal deaths were retrospectively observed in rural southwest Ethiopia. Four of the 6 deaths occurred due to direct obstetric causes. Substandard primary and referral care, not understanding the severity of the problem, and lack of transport were the major themes identified as contributing factors. The result highlighted the need to improving primary h...

2010-01-01

223

Themes in Southwest Prehistory, edited by George J. Gumerman, 1994  

Directory of Open Access Journals (Sweden)

Full Text Available The 11 chapters by 26 authors in this book result from a School of American Research seminar entitled, "The Organization and Evolution of Prehistoric Southwestern Society, held in September 1989. The goal of the seminar was to have well-known Southwestern scholars consider the entire Southwest as a single but diverse entity, with papers structured according to particular themes, including aggregation, abandonment. warfare, health, and demography.

Todd W. Bostwick

1995-11-01

224

NCLB: Local implementation and impact in southwest Washington state.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The research reported here is from the first two years of an ongoing and largely qualitative study to examine the impact of the No Child Left Behind federal education policy on educational practice and climate in elementary schools in two districts in southwest Washington. Based on systematic drop-in observations in classrooms and interviews with teachers and school and district administrators, data indicated that the policy had partially yielded the intended standards-based reforms but at co...

Linda Mabry; Linda Mabry and Jason Margolis

2006-01-01

225

Factors Associated with Treatment Compliance in Hypertension in Southwest Nigeria  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hypertension is an important condition among adults, affecting nearly one billion people worldwide. Treatment with appropriate medication is a key factor in the control of hypertension and reduction in associated risk of complications. However, compliance with treatment is often sub-optimal, especially in developing countries. The present study investigated the factors associated with self-reported compliance among hypertensive subjects in a poor urban community in southwest Nigeria. This com...

Osamor, Pauline E.; Owumi, Bernard E.

2011-01-01

226

Marine mammal strandings in the New Caledonia region, Southwest Pacific  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Four hundred twenty three marine mammals, in 72 stranding events, were recorded between 1877 and 2005 in New Caledonia, the Loyalty Islands, and Vanuatu in the southwest Pacific. Sixteen species were represented in this count, including: minke whale, Balaenoptera acutorostrata (1 single stranding), sei whale, B. borealis (1 single stranding), blue whale, B. musculus (1 single stranding), humpback whale, Megaptera novaeangliae (2 single strandings), giant sperm whale, Physeter macrocephalus (1...

Borsa, Philippe

2006-01-01

227

Local Impact of State Testing in Southwest Washington  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A decade after implementation of a state testing and accountability mandate, teachers' practices and perspectives regarding their classroom assessments and their state's assessments of student achievement were documented in a study of 31 teachers in southwest Washington state. Against a background of national trends and standards of psychometric quality, the data were analyzed for teachers' beliefs and practices regarding classroom assessment and also regarding state assessment, commonalities...

Linda Mabry; Jayne Poole; Linda Redmond; Angelia Schultz

2003-01-01

228

Influence of habitat structure and mouth dynamics on avifauna of intermittently-open estuaries: A study of four small South African estuaries  

Science.gov (United States)

Habitat composition was a major factor in determining waterbird species composition and abundance, particularly the area of floodplain and vegetated channel in four intermittently open estuaries (IOEs) in the warm-temperate coastal biogeographical region of South Africa. Average bird densities on the four estuaries varied from 0.5 to 4.2 birds per hectare, and community composition differed significantly between estuaries. However, the considerable variation in abundance of macrophytes did not have a detectable effect on waterbirds. Under closed mouth conditions, piscivorous birds dominated the avifauna. Each estuary's avifauna responded differently in terms of changes in feeding guild composition when the mouth opened. Bird abundance changed immediately after breaching, but not consistently. Diversity was significantly higher under open-mouth conditions for three of the four estuaries, and species composition was significantly different from that under closed-mouth conditions at all four estuaries. Changes in mouth dynamics as a result of climate change, water abstraction and artificial breaching could lead to significant changes in estuarine fauna.

Terörde, Anja I.; Turpie, Jane K.

2013-07-01

229

Levels of C{sub 10}-C{sub 13} polychloro-n-alkanes in marine mammals from the Arctic and the St. Lawrence River estuary  

Energy Technology Data Exchange (ETDEWEB)

Marine mammals from various regions of the Arctic and the St. Lawrence River estuary were examined for the first time for levels of C{sub 10}--C{sub 13} polychloro-n-alkanes (sPCAs). Respective mean total sPCA concentrations in the blubber of beluga whales (Delphinapterus leucas) from Saqqaq and Nuussuaq, western Greenland, were 0.23 {+-} 0.02 (n = 2) and 0.164 {+-} 0.06 {micro}g/g (n = 2), similar to that in beluga from the Mackenzie Delta in the western Canadian Arctic 0.21 {+-} 0.08 {micro}g/g (m = 3). sPCAs levels were higher in beluga blubber from the St. Lawrence River (0.37 to 1.4 {micro}g/g). Mean sPCA concentrations in the blubber samples from walruses (Odobenus rosmarus) (Thule, northwest Greenland) and ringed seal (Phoca hispida) (Eureka, southwest Ellesmere Island) were 0.43 {+-} 0.06 (n = 2) and 0.53 {+-} 0.2 {micro}g/g (n = 6), respectively. Relative to commercial sPCA formulations, samples from the Arctic marine mammals showed a predominance of the shorter chain length lower percent chlorinated PCA congeners, the more volatile components of industrial formulations. This observation is consistent with long-range atmospheric transport of sPCAs to this region. The profiles of the belugas from the St. Lawrence River estuary, however, had higher proportions of the less volatile sPCA congeners, implying that contamination to this region is probably from local sources.

Tomy, G.T.; Muir, D.C.G.; Stern, G.A.; Westmore, J.B.

2000-05-01

230

Pennsylvanian foreland deformation of Wichita uplift, southwest Oklahoma  

Energy Technology Data Exchange (ETDEWEB)

Pennsylvanian foreland deformation associated with the Ouachita orogene reactivated a west-northwest-east-southeast Cambrian basement trend, the southern Oklahoma aulacogen, to form the Wichita uplift, southwest Oklahoma. The 30-km-wide subsurface Frontal fault zone separates the uplift from the Anadarko basin to the north. Horizontal shortening across this fault zone is estimated at 7-15 km (20-40%), vertical displacement totals 9-10 km from the uplift to the basin. Folds are mapped on an interformational scale within the Frontal fault zone, and on an intraformational scale (Cambro-Ordovician Arbuckle Group) in the Slick Hills, southwest Oklahoma. Additional shortening occurred along southwest dipping mountain flank thrusts and on bedding plane thrusts, respectively. Hanging wall blocks of major faults contain the shallow dipping limb and anticlinal hinge zone of the interformational scale folds. Oil and gas production is generally restricted to these anticlinal crests within Paleozoic rocks. Deep wells (> 6000 m) that have penetrated footwall imbricates of the mountain flank thrusts have drilled through steep-overturned beds and tight recumbent folds before passing through faults into a normal stratigraphic sequence. Basement thrust loading of the southern margin of the Anadarko basin controlled the trend (west-northwest-east-southeast) of the axis of maximum deposition within the basin during the Pennsylvanian.

McConnell, D.

1986-05-01

231

Occurrence and distribution of dissolved tellurium in Changjiang River estuary  

Science.gov (United States)

With the implementation of the GEOTRACES program, the biogeochemical cycle and distribution of tellurium (Te) in marine environments are becoming increasing environmental concerns. In this study, the concentration of dissolved Te in the Changjiang (Yangtze) River estuary and nearby waters was determined in May 2009 by hydride-generation atomic fluorescence spectrometry to elucidate the abundance, dominant species, distribution, and relationship with environmental factors. Results show that: (1) dissolved Te was low owing to its low abundance in the Earth's crust, high insolubility in water, and strong affinity to particulate matter; (2) Te(IV) and Te(VI) predominated in surface water. Te(VI) was the dominant species in bottom water, and Te(IV) was the minor species; (3) Horizontally, resulting from low phytoplankton metabolism and the weak reduction from Te(VI) to Te(IV) in the shore, Te(IV) was concentrated in the central zone instead of the coastal region. However, Te(VI) was abundant near the mouth of the Changjiang River where the Changjiang water is diluted and in the area to the south where the Taiwan Warm Current invaded. In the adsorption-desorption process, Te(IV) was negatively related to suspended particulate matter (SPM), indicating that it was adsorbed by particulate matter. While for Te(VI), the positive correlation with SPM suggested that it was desorbed from the solid phase. In the estuary, dissolved Te had a negative correlation to salinity. However, it deviated from the dilution line in high-salinity regions due to the invasion of the Taiwan Warm Current and the mineralization of organic matter. The relationship between Te(IV) and SPM nutrients indicated that it was more bioavailable and more related to phosphorus than to nitrogen. Progress in the field is slow and more research is needed to quantify the input of Te to the estuary and evaluate the biochemical role of organisms.

Wu, Xiaodan; Song, Jinming; Li, Xuegang

2014-03-01

232

Be isotopes in rivers/estuaries and their oceanic budgets  

International Nuclear Information System (INIS)

10Be and 9Be have been determined in several North American rivers and in the estuaries of San Francisco Bay and the Pearl River (China). The average fluvial concentration of dissolved 10Be in the rivers is 3220±1960 (1?) atoms/g, almost an order of magnitude higher than the observed estuarine values and slightly higher than the 10Be concentration in the ocean (? 1700 atoms/g). For dissolved 9Be, a similar order-of-magnitude drop in concentration also occurs in going from rivers (750±740 pM) to estuaries (80-140 pM). However, in contrast to the 10Be situation, there appears another order-of-magnitude drop from estuaries to the ocean, which has 9Be concentrations of 5-30 pM. In spite of the wide range of concentrations for both isotopes in river and estuarine waters, 10Be/9Be ratios range mostly from 2 to 12x10-9, with a median value of 7x10-9 (atom/atom), and are much lower than the seawater ratio of ?10-7. In the rivers studied, a given volume of water contains roughly equal amounts of particulate and dissovled 10Be. The 10Be concentration in particulate matter ranges from 2x106 to 1x109 atoms/g-particulate with a median value of about 5x107 atoms/g-particulate. A two-box model calculation shows that coastal regions play an important role in the removal of Be isotopes from the ocean and that eolian dusts may be the chief source of oceanic 9Be. Because of the marginal removal effect, the overall oceanic residence time of Be should be shorter than the residence time of 500-1200 yr estimated for the open ocean. (orig.)

1991-01-01

233

Oil spill response planning on the Columbia river estuary  

International Nuclear Information System (INIS)

The Columbia River Estuary lies along the Washington-Oregon state boundary on the west coast of the United States. The entire area is environmentally very sensitive with numerous large, shallow bays, exposed mud flats, wetland areas, and central channels having maximum currents of three to four knots. These features make the area very difficult to protect from an oil spill. Spill response is further complicated because of the many different state, federal, and local jurisdictions with mandated responsibilities in oil spill response and environmental protection. Under the leadership of the US Coast Guard Marine Safety Office in Portland, Oregon, a steering group was established to guide the development of a response plan for the Columbia River Estuary. A concerted effort was made to include representatives from response organizations, natural resource agencies, and resource users from federal, state, and local governments, and commercial sectors in the planning process. The first draft of an operational response plan was completed the summer of 1992 through a combination of technical workshops, field trips, and small working groups meeting with local communities. The Columbia River Estuary Response Plan prioritizes areas to protect; identifies specific response strategies for protecting these areas; and outlines the Iogistics needed to implement these strategies, including equipment needs, the location of staging areas, and the identification of pre-designed command posts. The local spill response cooperative and oil transportation industry are using the plan to coordinate the purchase of response equipment and the staging of this equipment at numerous locations along the river. The key to success is ensuring that all the groups responding to an event participate in the planning process together. This process has worked well and will serve as a model for response planning for other areas along the Columbia River and coastal areas of Washington and Oregon

1993-04-01

234

Calculation of runoff to an estuary. Ria de Vigo  

Digital Repository Infrastructure Vision for European Research (DRIVER)

[EN] Runoff that reaches an estuary was estimated as a function of daily rainfall in the drainage basin when the daily measurements of river flows are not available. This method is applied to the rivers flowing into the Ría de Vigo and compared with the River Deza that reaches the Ría de Arosa where the daily flow and rainfall are known. The optimum value of the retention coefficient (k = 0.75) is calculated. The distribution of flow calculated from the equation obtained and the...

Ri?os, Aida F.; Nombela, Miguel A?ngel; Pe?rez, Fiz F.; Roso?n, Gabriel; Fraga, Fernando

1992-01-01

235

Carbon biogeochemistry of the Betsiboka Estuary (north-western Madagascar)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Madagascar’s largest estuary (Betsiboka) was sampled along the salinity gradient during the dry season to document the distribution and sources of particulate and dissolved organic carbon (POC, DOC) as well as dissolved inorganic carbon (DIC). The Betsiboka was characterized by a relatively high suspended matter load, and in line with this, low DOC/POC ratios ( 0.4–2.5). The partial pressure of CO2 (pCO2) was generally above atmospheric equilibrium (270–1530 ppm), but rel...

Ralison, Olivier Harifidy; Borges, Alberto; Dehairs, Frank; Bouillon, Steven

2008-01-01

236

Bacterial Communities in Kuantan Estuary of Pahang Malaysia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Physicochemical parameters influence the vertical spatial distribution of microbial communities in any water bodies. Based on this perspective, a study on physicochemical parameters and bacterial community was carried out from five stations on January-June 2009 at the Kuantan estuary of Pahang, Malaysia. The temperature was ranged from 25.01-27.48°C, salinity fluctuation observed 0.03-25.84 ppt, Dissolved Oxygen (DO) 6.10 to 10.73 mg L-1, specific conductivity ranged from 0.10 to ...

2010-01-01

237

Comparison of common persistent organic pollutants (POPs) in flounder (Platichthys flesus) from the Vistula (Poland) and Douro (Portugal) River estuaries.  

Science.gov (United States)

Groups of flounder (Platichthys flesus) females were collected in 2011 from the Vistula River and the Duoro River estuaries and corresponding reference sites in the southern Baltic Sea and Portuguese coast of the Atlantic Ocean to measure and compare the levels and profiles of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). The estuaries' sediments were also investigated. Several differences were found in the POPs between the estuaries and between the two marine regions, which were highlighted by PCA. The Vistula River estuary POPs, significantly higher than in the Douro River estuary, were dominated by DDTs followed by PCBs. PBDEs levels, indifferent between the estuaries, were relatively low. The POP levels in flounder and sediment evaluated against environmental assessment criteria (EACs) indicated that none of the measured contaminants for which EAC had been established exceeded the criterion, except for CB-118 in flounder from the Vistula River estuary. PMID:24492155

Waszak, Ilona; Dabrowska, Henryka; Komar-Szymczak, Katarzyna

2014-04-15

238

Microphytobenthos interannual variations in a north-European estuary (Loire estuary, France) detected by visible-infrared multispectral remote sensing  

Science.gov (United States)

Estuarine intertidal sediments are colonized by photosynthetic microorganisms grouped under the generic term of microphytobenthos (MPB). These microbial assemblages form transient biofilms at the sediment surface and have important ecosystem functions. MPB biofilms are well known to exhibit high microscale patchiness whereas meso- and macroscale spatio-temporal structures are little known. In this work, satellite remote sensing was used to map MPB assemblages at such scales. MPB interannual distribution was investigated in the poly- and mesohaline domain of the north-European estuary (Loire estuary), using a multispectral SPOT image time series (1991-2009). The Normalized Difference Vegetation Index (NDVI) was calculated from two SPOT channels, XS2 and XS3, (red and near-infrared wavelengths, respectively). MPB biofilms were identified by NDVI values between 0 and 0.3. At the scale of the whole intertidal area, the results showed that MPB biofilms in the Loire estuary exhibited perennial structures in both the polyhaline and mesohaline sectors, occupying nearly 90% of the mudflat surfaces. MPB biofilm density was closely associated with intertidal position, with thicker biofilms developing mostly in the upper and middle shore, and formed kilometric longitudinal structures parallel to the shoreline. Mean NDVI values showed a strong positive correlation with mean seasonal air temperature (? = 0.714, p < 0.05 in the polyhaline domain and ? = 0.810, p < 0.05 in the mesohaline domain), with a strong correlation in the upper intertidal mudflat (between +3 and 4 m isobaths). Negative wind effect was mainly detected in the upper intertidal areas, particularly between the +3 and 4 m isobaths (? = -0.810, p < 0.05 in the polyhaline domain and ? = -0.910 in the mesohaline).

Benyoucef, Ismaïl; Blandin, Elodie; Lerouxel, Astrid; Jesus, Bruno; Rosa, Philippe; Méléder, Vona; Launeau, Patrick; Barillé, Laurent

2014-01-01

239

Trace elements and radionuclides in the Connecticut River and Amazon River estuary  

Energy Technology Data Exchange (ETDEWEB)

The Connecticut River, its estuary, and the Amazon River estuary were studied to elucidate some of the processes which control river water chemistry and the flux of elements to the sea. The approach taken was to identify inputs to the Connecticut River and to investigate geochemical processes which modify the dissolved load. The form and quantity of nuclides which are in turn supplied to the estuary are altered by processes unique to that transition zone to the ocean. The Connecticut River estuary was sampled on a seasonal basis to investigate the role of the estuary in controlling the flux of elements to the sea. The knowledge gained from the Connecticut River study was applied to the quantitatively more significant Amazon River estuary. There a variety of samples were analyzed to understand the processes controlling the single greatest flux of elements to the Atlantic Ocean. The results indicate that estimates of the total flux of nuclides to the oceans can best be calculated based on groundwater inputs. Unless significant repositories for nuclides exist in the river-estuarine system, the groundwater flux of dissolved nuclides is that which will eventually be delivered to the ocean despite the reactions which were shown to occur in both rivers and estuaries. 153 references, 63 figures, 28 tables.

Dion, E.P.

1983-01-01

240

Trace elements and radionuclides in the Connecticut River and Amazon River estuary  

International Nuclear Information System (INIS)

The Connecticut River, its estuary, and the Amazon River estuary were studied to elucidate some of the processes which control river water chemistry and the flux of elements to the sea. The approach taken was to identify inputs to the Connecticut River and to investigate geochemical processes which modify the dissolved load. The form and quantity of nuclides which are in turn supplied to the estuary are altered by processes unique to that transition zone to the ocean. The Connecticut River estuary was sampled on a seasonal basis to investigate the role of the estuary in controlling the flux of elements to the sea. The knowledge gained from the Connecticut River study was applied to the quantitatively more significant Amazon River estuary. There a variety of samples were analyzed to understand the processes controlling the single greatest flux of elements to the Atlantic Ocean. The results indicate that estimates of the total flux of nuclides to the oceans can best be calculated based on groundwater inputs. Unless significant repositories for nuclides exist in the river-estuarine system, the groundwater flux of dissolved nuclides is that which will eventually be delivered to the ocean despite the reactions which were shown to occur in both rivers and estuaries. 153 references, 63 figures, 28 tables

1983-01-01

 
 
 
 
241

Dissolved organic matter (DOM) export to a temperate estuary: Seasonal variations and implications of land use  

DEFF Research Database (Denmark)

Inputs of dissolved carbon, nitrogen, and phosphorus were assessed for an estuary and its catchment (Horsens, Denmark). Seasonal patterns in the concentrations of DOM in the freshwater supply to the estuary differed depending on the soil and drainage characteristics of the area. In streams draining more natural areas the patterns observed were largely driven by seasonal temperature fluctuations. The material exported from agricultural areas was more variable and largely controlled by precipitation events. Positive exponential relationships were found between the nitrogen and phosphorus loading, and the percentage of catchment area used for agriculture. Colored DOM (CDOM) loading measurements were found to be a good predictor of dissolved organic carbon (DOC) loading across the different subcatchments, offering a rapid and inexpensive alternative of operationally monitoring DOC export. For all the dissolved nutrient inputs to the estuary, dissolved inorganic nitrogen (DIN) and dissolved organic phosphorus dominated the loadings. Although 81% of the nitrogen annually supplied to the estuary was DIN, 83% of the nitrogen exported from the estuary was dissolved organic nitrogen (DON). Results show that increasing the area of the catchment covered by forest and natural pastures would have a positive effect on the trophic status of the estuary, leading to a considerable decrease in the phosphorus loading and a shift in the nitrogen loading from DIN to DON. Such a change in land use would also increase the export of DOC and CDOM to the estuary having the potential to increase oxygen consumption and reduce the phofic depth.

Stedmon, Colin A.; Markager, Stiig

2006-01-01

242

A numerical study of local variations in tidal regime of Tagus estuary, Portugal.  

Science.gov (United States)

Tidal dynamics of shallow estuaries and lagoons is a complex matter that has attracted the attention of a large number of researchers over the last few decades. The main purpose of the present work is to study the intricate tidal dynamics of the Tagus estuary, which states as the largest estuary of the Iberian Peninsula and one of the most important wetlands in Portugal and Europe. Tagus has large areas of low depth and a remarkable geomorphology, both determining the complex propagation of tidal waves along the estuary of unknown manner. A non-linear two-dimensional vertically integrated hydrodynamic model was considered to be adequate to simulate its hydrodynamics and an application developed from the SIMSYS2D model was applied to study the tidal propagation along the estuary. The implementation and calibration of this model revealed its accuracy to predict tidal properties along the entire system. Several model runs enabled the analysis of the local variations in tidal dynamics, through the interpretation of amplitude and phase patterns of the main tidal constituents, tidal asymmetry, tidal ellipses, form factor and tidal dissipation. Results show that Tagus estuary tidal dynamics is extremely dependent on an estuarine resonance mode for the semi-diurnal constituents that induce important tidal characteristics. Besides, the estuarine coastline features and topography determines the changes in tidal propagation along the estuary, which therefore result essentially from a balance between convergence/divergence and friction and advection effects, besides the resonance effects. PMID:24312474

Dias, João Miguel; Valentim, Juliana Marques; Sousa, Magda Catarina

2013-01-01

243

Understanding the fate of iron in a modern temperate estuary: Leirarvogur, Iceland  

Energy Technology Data Exchange (ETDEWEB)

Highlights: > Fluvial Fe (aq) and Fe (total) concentrations drop upon mixing with seawater in estuaries. > The majority of Fe in estuaries is lost in the bay-head delta. > Our results suggest that the bay-head delta is a key location in Fe-mineral formation. > Isotopic variation in estuarine waters may play a role in the formation of Fe-minerals. - Abstract: Fluvial dissolved Fe concentrations decrease upon mixing with seawater, resulting in the formation of Fe-floccules. However, a clear understanding of the fate of these floccules has yet to be established. Assessing how tidal processes affect the formation of Fe-colloids in the Leirarvogur estuary, SW Iceland, is an important step in understanding the formation and potential deposition of estuarine Fe-rich minerals within this estuarine system. The Leirarvogur estuary drains predominately Fe-rich basalt, increasing the likelihood of detecting changes in Fe-phases. Fluvial waters and local lake waters that drain into the estuary were compared and the effects of seasonal changes were considered, in an attempt to understand how varying end-members and external factors play a role in Fe-rich mineral formation. Aqueous and colloidal Fe concentrations were found to be greater towards the head of the Leirarvogur estuary, suggesting that potential Fe-rich minerals and complexes are forming at sites of fluvial input. Increasing suspended colloidal Fe towards the estuary mouth suggests that Fe-colloids are readily transported seaward.

Byrne, Gemma M., E-mail: gmbyrne@liverpool.ac.uk [Department of Earth and Ocean Sciences, School of Environmental Science, University of Liverpool, Liverpool L69 3GP (United Kingdom); Worden, Richard H.; Hodgson, David M. [Department of Earth and Ocean Sciences, School of Environmental Science, University of Liverpool, Liverpool L69 3GP (United Kingdom); Polya, David A.; Lythgoe, Paul R. [School of Earth, Atmosphere and Environmental Sciences, University of Manchester, Manchester M13 9PL (United Kingdom); Barrie, Craig D.; Boyce, Adrian J. [Scottish Universities Environmental Research Centre, Rankine Avenue, East Kilbride, Glasgow G75 0QF (United Kingdom)

2011-06-15

244

Understanding the fate of iron in a modern temperate estuary: Leirarvogur, Iceland  

International Nuclear Information System (INIS)

Highlights: ? Fluvial Fe (aq) and Fe (total) concentrations drop upon mixing with seawater in estuaries. ? The majority of Fe in estuaries is lost in the bay-head delta. ? Our results suggest that the bay-head delta is a key location in Fe-mineral formation. ? Isotopic variation in estuarine waters may play a role in the formation of Fe-minerals. - Abstract: Fluvial dissolved Fe concentrations decrease upon mixing with seawater, resulting in the formation of Fe-floccules. However, a clear understanding of the fate of these floccules has yet to be established. Assessing how tidal processes affect the formation of Fe-colloids in the Leirarvogur estuary, SW Iceland, is an important step in understanding the formation and potential deposition of estuarine Fe-rich minerals within this estuarine system. The Leirarvogur estuary drains predominately Fe-rich basalt, increasing the likelihood of detecting changes in Fe-phases. Fluvial waters and local lake waters that drain into the estuary were compared and the effects of seasonal changes were considered, in an attempt to understand how varying end-members and external factors play a role in Fe-rich mineral formation. Aqueous and colloidal Fe concentrations were found to be greater towards the head of the Leirarvogur estuary, suggesting that potential Fe-rich minerals and complexes are forming at sites of fluvial input. Increasing suspended colloidal Fe towards the estuary mouth suggests that Fe-colloids are readily transported seaward.

2011-06-01

245

Interaction of lateral baroclinic forcing and turbulence in an estuary  

Science.gov (United States)

Observations of density and velocity in a channel in northern San Francisco Bay show that the onset of vertical density stratification during flood tides is controlled by the balance between the cross-channel baroclinic pressure gradient and vertical mixing due to turbulence. Profiles of velocity, salinity, temperature, and suspended sediment concentration were measured in transects across Suisun Cutoff, in northern San Francisco Bay, on two days over the 12.5-hour tidal cycle. During flood tides an axial density front developed between fresher water flowing from the shallows of Grizzly Bay into the northern side of Suisun Cutoff and saltier water flowing up the channel. North of the front, transverse currents were driven by the lateral salinity gradient, with a top-to-bottom velocity difference greater than 30 cm/s. South of the front, the secondary circulation was weak, and along-channel velocities were greater than to the north. The gradient Richardson number shows that stratification was stable north of the front, while the water column was turbulently mixed south of the front. Time-series measurements of velocity and salinity demonstrate that the front develops during each tidal cycle. In estuaries, longitudinal dynamics predict less stratification during flood than ebb tides. These data show that stratification can develop during flood tides due to a lateral baroclinic pressure gradient in estuaries with complex bathymetry.

Lacy, Jessica R.; Stacey, Mark T.; Burau, Jon R.; Monismith, Stephen G.

2003-03-01

246

Spatial variation of the longitudinal dispersion coefficient in an estuary  

Directory of Open Access Journals (Sweden)

Full Text Available The effective longitudinal dispersion is a primary tool for determining property distributions in estuaries. Most previous studies have examined the longitudinal dispersion coefficient for the average tidal condition. However, information on spatial and temporal variations of this coefficient at low and high tides is scarce. Three years of hydrographic data taken at low and high tide along the main axis of the Sumjin River Estuary (SRE, Korea are used to estimate the spatial and temporal variation of the effective longitudinal dispersion coefficient. The range of the dispersion coefficient is rather broad at high water slack (HWS and narrower at low water slack (LWS because of the different tidal amplitudes. The spatially varying dispersion coefficient has maximal values (>300 m2 s?1 near the mouth at high water and decreases gradually upstream, with fluctuations. The temporally varying dispersion coefficient appears to be positively correlated with river discharges at both low and high tide. The dispersion varies with the square root of river discharges at HWS and LWS. The dispersive salt fluxes increases with increasing river discharges and decreases with decreasing river discharges at HWS and LWS. Estimation of the numerical values of the effective longitudinal dispersion coefficient in the SRE can be useful for better understanding of the distributions of other tracers in the SRE as well as for developing and testing hypotheses about various mixing mechanisms.

D. C. Shaha

2011-12-01

247

Spatial variation of the longitudinal dispersion coefficient in an estuary  

Directory of Open Access Journals (Sweden)

Full Text Available The effective longitudinal dispersion is a primary tool for determining property distributions in estuaries. Most previous studies have examined the longitudinal dispersion coefficient for the average tidal condition. However, information on spatial and temporal variations of this coefficient at low and high tide is scarce. Three years of hydrographic data taken at low and high tide along the main axis of the Sumjin River Estuary (SRE, Korea are used to estimate the spatial and temporal variation of the effective longitudinal dispersion coefficient. The range of the dispersion coefficient is rather broad at high water slack (HWS and narrower at low water slack (LWS because of the different tidal amplitudes. The spatially varying dispersion coefficient has maximal values (>300 m2 s?1 near the mouth at high water and decreases gradually upstream, with fluctuations. The temporally varying dispersion coefficient appears to be positively correlated with river discharges at both low and high tide. The dispersion varies with the square root of river discharges at HWS and LWS. The dispersive salt fluxes increases with increasing river discharges and decreases with decreasing river discharges at HWS and LWS. Estimation of the numerical values of the effective longitudinal dispersion coefficient in the SRE can be useful for better understanding of the distributions of other tracers in the SRE as well as for developing and testing hypotheses about various mixing mechanisms.

D. C. Shaha

2011-08-01

248

Caspian Rapid Sea Level Changing Impact on Estuaries Morphodynamic Deformation  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, the evaluation of sedimentary-morphodynamic deformation of main estuaries of rivers in the southern coasts of the Caspian Sea is main target. With selecting, eight main rivers and by sampling of sediments on them in the beach zones, geometry of surrounded beach structure, morphodynamic condition and sedimentary deposition processes were analyzed. with interpretation satellite and aerial images of study area along the period between 1983 till 2004 that correspond to last progression phase of Caspian sea level arise (+ 2.5m, the effect of rapid sea level changing of the Caspian Sea on beach and mouth of rivers have been measured. The results show that there are different type of the estuaries in the study area and the last sea level arise has caused morphdynamic deformation (trait inclination of rivers, inflation of mouth and it’s widen on the beach zone and the rivers mouth condition. Therefore as conclusion, the rivers of the Caspian Sea southern coasts have different behavior against rapid sea level changing in the coastal zones and they are classified to three statements: erosion, accretion and transition.

Homayoun Khoshravan

2013-07-01

249

Mathematical simulation of sediment and radionuclide transport in estuaries  

International Nuclear Information System (INIS)

The finite element model LFESCOT (Flow, Energy, Salinity, Sediment and Contaminant Transport Model) was synthesized under this study to simulate radionuclide transport in estuaries to obtain accurate radionuclide distributions which are affected by these factors: time variance, three-dimensional flow, temperature, salinity, and sediments. Because sediment transport and radionuclide adsorption/desorption depend strongly on sizes or types of sediments, FLESCOT simulates sediment and a sediment-sorbed radionuclide for the total of three sediment-size fractions (or sediment types) of both cohesive and noncohesive sediments. It also calculates changes of estuarine bed conditions, including bed elevation changes due to sediment erosion/deposition, and three-dimensional distributions of three bed sediment sizes and sediment-sorbed radionuclides within the bed. Although the model was synthesized for radionuclide transport, it is general enough to also handle other contaminants such as heavy metals, pesticides, or toxic chemicals. The model was checked for its capability for flow, water surface elevation change, salinity, sediment and radionuclide transport under various simple conditions first, confirming the general validity of the model's computational schemes. These tests also revealed that FLESCOT can use large aspect ratios of computational cells, which are necessary in handling long estuarine study areas. After these simple tests, FLESCOT was applied to the Hudson River estuary between Chelsea and the mouth of the river to examine how well the model can predict radionuclide transport through simulating tidally influenced three-dimensional flow, salinity, sediment and radionuclide movements with their interactions

1982-01-01

250

A modelling assessment of contaminant distributions in the Severn Estuary.  

Science.gov (United States)

The regulatory requirements imposed by the Habitats Directive (EU 93/43/EEC) require the Environment Agency for England and Wales (EA) to review consented discharges and determine whether they are compliant with Environmental Quality Standards (EQS). Since the EQS are annual averages, model predictions, and sample comparisons, should be made on an annual average basis. Advection and dispersion of metal contaminants in the Severn Estuary were computed using a coupled 1-D and 2-D hydrodynamic-water quality model. The external inputs of dissolved copper, arsenic, mercury and chromium to the model were from 66 industrial discharges and sewage treatment works and 30 rivers. The annual average predicted concentrations were compared with the annual average dissolved metal concentrations from the 2004 and 2005 monitoring programme, and any discrepancy used to identify the role of additional processes, mainly involving the sediments. This ability to separate anthropogenic inputs from internal estuarine processes contributes to a better understanding of the functioning of the estuary and hence an improved management capability. The paper discusses the approach in designing scenarios and characterising uncertainty, when decision-making in the regulatory context. PMID:20079502

Murdoch, N; Jonas, P J C; Falconer, R A; Lin, B

2010-01-01

251

Environmental flow assessments in estuaries related to preference of phytoplankton  

Directory of Open Access Journals (Sweden)

Full Text Available We developed an approach to assess environmental flows in estuaries related to preference of phytoplankton considering the complex relationship between hydrological modification and biomass in ecosystems. As a first step, a relationship was established between biomass requirements for organisms of primary and higher nutritional levels based on the principle of nutritional energy flow of ecosystem. Then, diagnostic pigments were employed to represent phytoplankton community biomass, which indicated competition between two groups of phytoplankton in the biochemistry process. Considering empirical relationships between diagnostic pigments and critical environmental factors, responses of biomass to river discharges were established based on a convection–diffusion model by simulating distributions of critical environmental factors under action of river discharges and tide currents. Consequently, environmental flows could be recommended for different requirements of fish biomass. In the case study in the Yellow River estuary, May and October were identified as critical months for fish reproduction and growth during dry years. Artificial hydrological regulation strategies should carefully consider the temporal variations of natural flow regime, especially for a high-amplitude flood pulse, which may cause negative effects on phytoplankton groups and higher organism biomass.

Z. F. Yang

2014-01-01

252

Radium and radon in Charlotte Harbor Estuary, Florida  

Science.gov (United States)

Radium-226 and 222Rn activities are greater in the estuarine waters of northern Charlotte Harbor and the lower tidal Peace and Myakka Rivers, Florida, than in either the freshwater reaches of the rivers or waters of the lower estuary and the Gulf of Mexico. The activity of 226Ra in the tidal rivers increases with decreasing river inflow, with a maximum value of 548 dpm 1001-1 measured in the tidal Myakka River. The source of the high activity of 226Ra and 222Rn is predominantly ground water inflow. Because of the large ground water input, the contribution of 226Ra from suspended and bottom sediments is a smaller fraction of the total 226Ra input than in many other estuaries. Although ground water 226Ra activity in the area varies widely, we estimate that artesian ground water inflow to the tidal rivers is similar in magnitude to the flow of the rivers above the tidal reach during the dry season. ?? 1990.

Miller, R. L.; Kraemer, T. F.; McPherson, B. F.

1990-01-01

253

A trace element study in the Thames estuary  

International Nuclear Information System (INIS)

The paper reports a study of the trace element concentrations in part of the Thames Estuary, a partially enclosed area of water. The concentration of the trace elements in the 'dissolved fraction' and the 'non-dissolved fraction' of the water and in the sediment is reported and relationships between these elements are sought. This information may be important in predicting transport mechanisms for trace elements and gives an indication of their fate. Neutron activation analysis was selected for this study but preconcentration was required for elements in the dissolved fraction. Chelex-100 resin was used to selectively remove cobalt, zinc, chromium, mercury and scandium from the water matrix. All elements except mercury were reproducible with a coefficient of variation less than 20%. Ultraviolet absorbance (to give an indication of organic content) and salinity were recorded for samples taken at points spanning the Estuary in Sea Reach. All other fractions were subject to instrumental neutron activation analysis and all results were correlated for every pair of elements in each sample component. Six groups of elements were identified with correlations which indicated relationships within each group. The most important group was common to the muddy sediment and the non-dissolved fraction in the water. There were no strong correlations in the dissolved fraction but cobalt, zinc and chromium were linked with UV absorbance and salinity. Iron, cobalt, chromium and hafnium did not align with the main grouping and possible mechanisms for these differences are suggested. (author)

1975-06-30

254

Influence of tides and winds on fishing techniques and strategies in the Mamanguape River Estuary, Paraíba State, NE Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este trabalho foi desenvolvido junto a duas comunidades de pescadores artesanais: Barra de Mamanguape e Tramataia, Nordeste do Brasil. O objetivo foi estudar o conhecimento e a percepção dos pescadores artesanais sobre a classificação das marés e dos ventos bem como as técnicas e estratégias de pesc [...] a. A metodologia empregada envolveu várias técnicas: entrevistas livres, entrevistas semiestruturadas, turnês guiadas e observação direta. Os resultados obtidos junto aos pescadores mostraram a classificação das marés de acordo com as fases lunares em: 'maré de quebramento', 'maré de lançamento', 'maré morta' e 'maré grande', designadas tecnicamente estas últimas como maré de quadratura e maré de sizígia, respectivamente. O vento é também um fator essencial no sucesso da pescaria, eles o classificam de acordo com a direção: Norte, Sul, Leste, Sudeste, Sudoeste, Nordeste, Noroeste. Os dados obtidos nesta pesquisa mostraram que o conhecimento dos pescadores pode ser útil na elaboração de planos de manejo e nos estudos de conservação para este estuário. Abstract in english This work was carried out in two small fishing communities, Barra de Mamanguape and Tramataia, Northeastern Brazil. The aim was to study these traditional fishermen's knowledge and perception about tide and wind classifications, as well as their fishing strategies and techniques. Our research method [...] ology involved various techniques: free interviews and semi-structured ones, guided tours and direct observations. The results obtained show the fishermen's classification of the tides according to the phases of the moon: 'breaking tide', 'flushing tide', 'dead tide' and 'big tide' designated technically these last as neap tide and spring tide, respectively. Wind is also an essential factor for the fishermen to make successful catches, and they classify it according to direction: North, South, East, Southeast, Southwest, Northeast and Northwest. The data show that fishermen's knowledge can also be useful in devising plans for management and conservation studies for this estuary.

Dandara M.M., Bezerra; Douglas M., Nascimento; Emmanoela N., Ferreira; Pollyana D., Rocha; José S., Mourão.

255

A modelling study of residence time in a macro-tidal estuary  

Science.gov (United States)

This paper outlines a numerical modelling study to predict the average residence time of a conservative tracer in a macro-tidal estuary, namely the Mersey Estuary, UK. An integrated hydrodynamic-dispersion model was used to predict the average residence time in the estuary for various tidal level and freshwater discharge conditions. The numerical model was verified against six sets of field measured hydrodynamic data, with the model-predicted water elevations and salinity levels generally agreeing well with the field measurements. The numerical model results show that in the Mersey Estuary both the tidal level and river discharge affect significantly the predicted average residence time. The value of the average residence time is also shown to be closely linked to the intensity of the residual tidal current. This is due to the fact that a large proportion of the Upper and Inner Estuary dries out during low tides, thus a significant amount of the tracer material is transported through the deep channels. An increase in the freshwater discharge causes a considerable increase in the intensity of the residual current along the main channels and thus a reduction in the average residence time. The predicted overall tracer residence time for the whole estuary is relatively short for a relatively large estuary, ranging from less than 1 day to 4 days for various tidal level and freshwater flow combinations. When the tidal range and freshwater discharge are both small, then the local tracer residence time in the upper part of the estuary can be significantly longer than the values predicted for the middle and lower reaches of the estuary.

Yuan, D.; Lin, B.; Falconer, R. A.

2007-02-01

256

Comparing spatial and temporal dynamics of anammox and denitrifying communities at Cape Fear River Estuary and New River Estuary, North Carolina  

Science.gov (United States)

Anaerobic ammonium oxidation (anammox) and denitrification are two main microbial processes capable of removing fixed nitrogen by conversion into a gaseous species. Both microbial processes are known to occur in anoxic estuarine sediments and are capable of remediating excess nitrogen loadings from anthropogenic activities. In order to understand the importance of anammox and denitrification in estuarine ecosystems, we investigated both processes in two different estuaries of North Carolina to compare sedimentary nitrogen removal capacity and to identify key players of N2 production pathways. Both Cape Fear River Estuary (CFRE) and New River Estuary (NRE) are highly enriched with nitrogen from anthropogenic sources in spite of distinct geomorphological and geochemical characteristics. We conducted seasonal samplings to collect sediments across transects at fifteen stations along each estuary. 15N tracer techniques were used to measure spatial and temporal variations of N2 production by denitrification and anammox in estuarine sediments. Molecular analysis of nitrous oxide reductase (nosZ) and hydrazine oxidase (hzo) genes was conducted to examine community structures of denitrifying and anammox bacteria, respectively. Denitrification was found to be the dominant N2 production processes in both estuaries. Anammox contributed up to 19% and 15 % of total N2 productions in the CFEE and the NRE, respectively. Phylogenetic analysis of hzo genes identified that the anammox bacteria at both estuaries are closely associated with five known genera in the order Brocadiales. Anammox communities at the CFRE showed biogeographical distribution along the estuarine gradients while high seasonal variations were observed in the NRE communities. Spatial and temporal variations of denitrifying communities at both estuaries were also found based on nosZ gene analysis. Multivariate analysis was conducted to define key biogeochemical parameters influencing the community dynamics and activities of anammox and denitrifying bacteria in these ecosystems. Thus, this study reveals the importance of community structure to its function, as well as estimates and compares potential N removal capacity in two geologically distinct estuarine ecosystems.

Lisa, J. A.; Hirsch, M. D.; Duernberger, K. A.; Tobias, C. R.; Song, B.

2010-12-01

257

Monitoring requirements for detecting tidal barrage induced changes to estuary bird populations  

Energy Technology Data Exchange (ETDEWEB)

This study was performed to examine the monitoring requirements for detecting tidal barrage induced changes to estuary bird populations, focussing mainly on the Mersey estuary. The degree of variability in populations between years for a number of species within the Mersey, Dee, Alt and Ribble were ascertained. The number of counts needed each winter, before and after barrage construction, were assessed. The percentage charge detectable for species was predicted. One east coast estuary (the Wash) was investigated for comparison of the effects of influences of severe weather. (UK).

Davenport, T.; Jeffers, J.N.R.; North, P.M. [Kent Univ., Canterbury (United Kingdom); Clark, N.A.; Langston, R.H.W.; Prys-Jones, R.P.

1990-12-31

258

Waterfowl migration and distribution in North West estuaries. V. 1. Text and tables  

Energy Technology Data Exchange (ETDEWEB)

Waterfowl populations may be affected by proposed tidal barrage across the Mersey. This study had three objectives:-(1) to evaluate the patterns of usage of the intertidal flats of the Mersey estuary by waders and wildfowl and to establish which are the preferred areas; (2) to identify the places of origin and movement patterns of the populations of waders and wildfowl that visit the Mersey Estuary; and (3) to evaluate evidence regarding the capacity of British estuaries to absorb waders and wildfowl populations which might be displaced by a Mersey Barrage. The text and tables and results only are presented in Volume 1. (author).

Clark, N.A.; Kirby, J.S.; Langston, R.H.W.; Donald, P.; Mawdesley, T.; Evans, J.

1990-12-01

259

Man-made radionuclides and sedimentation in the Hudson River Estuary  

International Nuclear Information System (INIS)

Recently deposited fine-grained sediments in the Hudson River estuary contain radionuclides from global fallout produced by atmospheric bomb tests as well as from low-level releases of a local nuclear reactor. Accumulation rates of these nuclides are dependent on rates of sediment deposition and vary with location in the estuary by more than two orders of magnitude. Within the Hudson estuary, New York harbor is currently the zone of most rapid deposition of sediments containing radionuclides, some of which were released from a nuclear reactor about 60 kilometers upstream of the harbor

1976-10-08

260

Distribution and occurrence of diatom community along three estuaries of Dakshina Kannada, west coast of India.  

Science.gov (United States)

The present paper deals with the collection and identification of Diatoms (Bacillariophyceae) of three estuaries at Dakshina Kannada district, (Karnataka). The studies were carried out for a period of one year extending between November 1994 to December 1995. A total of 33 taxa belonging to 24 genera were recorded from three different estuaries. The highest number of diatom taxa were recorded from H1 & G1 estuaries and the most common diatom genera observed at all the stations were Coscinodiscus sp., and Cheatoceros sp.,. The various ecological parameters analysed are discussed. PMID:13677062

Shashikumar, K C; Madhyastha, M N; Rekha, P D

2002-10-01

 
 
 
 
261

Southwest British Columbia natural gas supply and deliverability: Discussion paper  

International Nuclear Information System (INIS)

A review is presented of energy in British Columbia, the role of natural gas, and options available to enhance gas supply security in the province's most densely populated area, the southwest. British Columbia has abundant natural gas supplies, and production exceeds domestic demand. In 1992, natural gas supplied ca 25% of total provincial end-use energy requirements, but this share is expected to rise to 30% by 2015. Although some say that the province's natural gas production and transmission system should serve only domestic needs, this would have significant negative impacts. Domestic gas supply policy allows gas consumers to contract their own supplies, but contract security is required. Provincial guidelines allow demand-side programs to compete with supply sources to ensure that the resource profile is achieved at least cost. In the southwest, natural gas demand is projected to increase from 189 PJ in 1991 to 262 PJ by 2005. Most gas supplied to this region comes from northeast British Columbia through pipelines that are generally fully contracted. Short-term deliverability can be a problem, especially in peak winter demand periods. The gas industry's contingency plans for shortages are outlined and alternatives to enhance deliverability to the southwest are assessed, including storage, expansion of the pipeline system, supply curtailment, and peaking supply contracts. Aspects of provincial natural gas planning are discussed, including security of supply and deliverability, economic and environmental impacts, consumer costs, safety, and the public interest. A least-cost option for enhancing deliverability (underground storage and an additional liquefied natural gas plant) is estimated to cost consumers $3.69/GJ over 20 years. 9 figs., 1 tab

1994-01-01

262

Rocky desertification in Southwest China: Impacts, causes, and restoration  

Science.gov (United States)

Rocky desertification, which is relatively less well known than desertification, refers to the processes and human activities that transform a karst area covered by vegetation and soil into a rocky landscape. It has occurred in various countries and regions, including the European Mediterranean and Dinaric Karst regions of the Balkan Peninsula, Southwest China on a large scale, and alarmingly, even in tropical rainforests such as Haiti and Barbados, and has had tremendous negative impacts to the environment and social and economic conditions at local and regional scales. The goal of this paper is to provide a thorough review of the impacts, causes, and restoration measures of rocky desertification based on decades of studies in the southwest karst area of China and reviews of studies in Europe and other parts of the world. The low soil formation rate and high permeability of carbonate rocks create a fragile and vulnerable environment that is susceptible to deforestation and soil erosion. Other natural processes related to hydrology and ecology could exacerbate rocky desertification. However, disturbances from a wide variety of human activities are ultimately responsible for rocky desertification wherever it has occurred. This review shows that reforestation can be successful in Southwest China and even in the Dinaric Karst region when the land, people, water, and other resources are managed cohesively. However, new challenges may arise as more frequent droughts and extreme floods induced by global climate change and variability may slow the recovery process or even expand rocky desertification. This review is intended to bring attention to this challenging issue and provide information needed to advance research and engineering practices to combat rocky desertification and to aid in sustainable development.

Jiang, Zhongcheng; Lian, Yanqing; Qin, Xiaoqun

2014-05-01

263

Data report for the Southwest Residential Experiment Station, January 1982  

Energy Technology Data Exchange (ETDEWEB)

Physical performance data obtained from the photovoltaic energy systems under test at the Southwest Residential Experiment Station in Las Cruces, New Mexico are tabulated and graphed for the month of January, 1982. Data drawn from the Residential Data System (RDS) appears in several formats. A one-page summary is provided as well as a more detailed hour-by-hour tabulation for an average day of the month. Energy histograms are provided, based on RDS data and recording kilowatt hour meters. The histograms also present horizontal and plane-of-array insolation data as well as comments that explain data and/or energy production anomalies. (LEW)

Lieberman, M.; Hai, O. Y.; Hocking, G.; Whitaker, C.

1982-02-23

264

Health Care Services Used by Appalachians in Southwest Virginia  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this research was to study the healthcare services used by Appalachians in southwest Virginia. The study finds that emergency room users are likely to be never married and male. On the other hand, those with a diagnosed medical condition are likely to choose a physician as their primary healthcare provider. The results underscore the critical role of insurance in health care. Individuals with no health coverage are more likely to use emergency room services. The study finds no difference in healthcare services in terms of private or public insurance. Both groups are equally likely to use a physician as their primary healthcare provider.

Marion R. Manton

2008-10-01

265

Be isotopes in rivers/estuaries and their oceanic budgets  

Energy Technology Data Exchange (ETDEWEB)

{sup 10}Be and {sup 9}Be have been determined in several North American rivers and in the estuaries of San Francisco Bay and the Pearl River (China). The average fluvial concentration of dissolved {sup 10}Be in the rivers is 3220{+-}1960 (1{sigma}) atoms/g, almost an order of magnitude higher than the observed estuarine values and slightly higher than the {sup 10}Be concentration in the ocean ({approx equal} 1700 atoms/g). For dissolved {sup 9}Be, a similar order-of-magnitude drop in concentration also occurs in going from rivers (750{+-}740 pM) to estuaries (80-140 pM). However, in contrast to the {sup 10}Be situation, there appears another order-of-magnitude drop from estuaries to the ocean, which has {sup 9}Be concentrations of 5-30 pM. In spite of the wide range of concentrations for both isotopes in river and estuarine waters, {sup 10}Be/{sup 9}Be ratios range mostly from 2 to 12x10{sup -9}, with a median value of 7x10{sup -9} (atom/atom), and are much lower than the seawater ratio of {proportional to}10{sup -7}. In the rivers studied, a given volume of water contains roughly equal amounts of particulate and dissovled {sup 10}Be. The {sup 10}Be concentration in particulate matter ranges from 2x10{sup 6} to 1x10{sup 9} atoms/g-particulate with a median value of about 5x10{sup 7} atoms/g-particulate. A two-box model calculation shows that coastal regions play an important role in the removal of Be isotopes from the ocean and that eolian dusts may be the chief source of oceanic {sup 9}Be. Because of the marginal removal effect, the overall oceanic residence time of Be should be shorter than the residence time of 500-1200 yr estimated for the open ocean. (orig.).

Kusakabe, M.; Ku, T.L.; Cusimano, G.L.; Nakaya, S. (Dept. of Geological Sciences, Univ. of Southern California, Los Angeles, CA (USA)); Southon, J.R.; Vogel, J.S.; Nelson, D.E. (Archaeology Dept., Simon Fraser Univ., Burnaby (Canada)); Liu Shao (South China Sea Inst. of Oceanology, Academia Sinica, Guangzhou, GD (China))

1991-03-01

266

Hydrodynamics in Shallow Estuaries with Complex Bathymetry and Large Tidal Ranges.  

Science.gov (United States)

Understanding the dynamics of flows, mixing and turbulence in estuaries with large tidal range and complex bathymetry. This includes making the connections between Lagrangian and Eulerian mean flow quantities as well as the role of fronts in determining o...

S. G. Monismith

2011-01-01

267

Seasonal incidence of Vibrio vulnificus in the Great Bay estuary of New Hampshire and Maine.  

Science.gov (United States)

Vibrio vulnificus, a normal bacterial inhabitant of estuaries, is of concern because it can be a potent human pathogen, causing septicemia, wound infections, and gastrointestinal disease in susceptible hosts. From May 1989 through December 1990, oysters and/or water were obtained from six areas in the Great Bay estuary of New Hampshire and Maine. Water was also sampled from three freshwater sites that lead into these areas. V. vulnificus was first detected in the estuary in early July and remained present through September. V. vulnificus was isolated routinely during this period from oysters and water of the Squamscott, Piscataqua, and Oyster Rivers but was only isolated twice from the oysters or water of the Great Bay itself. This study determined that there was a strong correlation (by analysis of variance) between temperature, salinity, and the presence of V. vulnificus in water and oysters. However, other unidentified factors appear to influence its presence in certain areas of the estuary. PMID:1444362

O'Neill, K R; Jones, S H; Grimes, D J

1992-10-01

268

St. Johns Estuary: Estuarine Benthic Macroinvertebrates Phase 2 Final Report. Special Publication SJ2012-SP4.  

Science.gov (United States)

Benthic macrofaunal communities can be strongly influenced by changes in freshwater inflows in an estuary. Macrofauna are affected by changes in estuarine condition (including nutrient concentrations, sediment supply and salinity) caused by variation in f...

J. B. Pollack P. A. Montagna T. A. Palmer

2011-01-01

269

VISION, STRATEGY AND ACTION PLAN FOR SHELLFISH FARMING DEVELOPMENT IN THE KRKA RIVER ESTUARY  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper are presented the vision, strategic guidelines/measures and the action plan for shellfish farming development in the Krka river estuary. They came as a result from several discussions that were held with shellfish farmers of the estuary area in year 2008 while writing the Integrated Plan for Shellfish Farming for Krka Estuary Area, which was realized in the framework of the Green Business Support Programme (UNDP COST Project — Conservation, and Sustainable Use of Biodiversity in the Dalmatian Coast through Greening Coastal Development. For a short–term, a considerable impetus for the development of shellfish farming in the Krka river estuary could be the construction of common distribution and purification center, building of warehouse for shellfish farming equipment, and providing work space for the preparation of the equipment as well as the space for waste disposal; for a long–term it could be building of shellfish hatchery at the location of Martinska marine station.

Drago Maguš

2009-10-01

270

Climate change drives warming in the Hudson River Estuary, New York (USA).  

Science.gov (United States)

Estuaries may be subject to warming due to global climate change but few studies have considered the drivers or seasonality of warming empirically. We analyzed temperature trends and rates of temperature change over time for the Hudson River estuary using long-term data, mainly from daily measures taken at the Poughkeepsie Water Treatment Facility. This temperature record is among the longest in the world for a river or estuary. The Hudson River has warmed 0.945 °C since 1946. Many of the warmest years in the record occurred in the last 16 years. A seasonal analysis of trends indicated significant warming for the months of April through August. The warming of the Hudson is primarily related to increasing air temperature. Increasing freshwater discharge into the estuary has not mitigated the warming trend. PMID:21720614

Seekell, David A; Pace, Michael L

2011-08-01

271

Environmental fate of fungicides and other current-use pesticides in a central California estuary.  

Science.gov (United States)

The current study documents the fate of current-use pesticides in an agriculturally-dominated central California coastal estuary by focusing on the occurrence in water, sediment and tissue of resident aquatic organisms. Three fungicides (azoxystrobin, boscalid, and pyraclostrobin), one herbicide (propyzamide) and two organophosphate insecticides (chlorpyrifos and diazinon) were detected frequently. Dissolved pesticide concentrations in the estuary corresponded to the timing of application while bed sediment pesticide concentrations correlated with the distance from potential sources. Fungicides and insecticides were detected frequently in fish and invertebrates collected near the mouth of the estuary and the contaminant profiles differed from the sediment and water collected. This is the first study to document the occurrence of many current-use pesticides, including fungicides, in tissue. Limited information is available on the uptake, accumulation and effects of current-use pesticides on non-target organisms. Additional data are needed to understand the impacts of pesticides, especially in small agriculturally-dominated estuaries. PMID:23790458

Smalling, Kelly L; Kuivila, Kathryn M; Orlando, James L; Phillips, Bryn M; Anderson, Brian S; Siegler, Katie; Hunt, John W; Hamilton, Mary

2013-08-15

272

Sediment disturbance off the Tagus Estuary, Western Portugal: chronic contamination, sewage outfall operation and runoff events.  

Science.gov (United States)

Sediment disturbance patterns in the coastal area off the Tagus Estuary (Portugal) have been assessed using a set of combined techniques. The potential sources of disturbance in the area include chronic contamination of the fine sediments originating from the estuary, a local input from a long-sea sewage outfall and occasional high runoff episodes following torrential rain. The Sediment Quality Triad approach, combining environmental chemistry (namely organic contaminants), macrofaunal benthic communities and laboratory sediment toxicity assays, was performed on sediment samples from 20 sites. The samples were collected before the outfall commenced operation and four years after commissioning, in order to evaluate the relative magnitudes of the three potential sources of disturbance. The sediment contamination created by the estuary was identified as the most important cause of reduced sediment quality, as disturbance in all three components of the Sediment Quality Triad were only found in a site located near the estuary. PMID:15245980

Silva, Susana; Ré, Ana; Pestana, Pilar; Rodrigues, Ana; Quintino, Victor

2004-08-01

273

Phytoplankton community structure defined by key environmental variables in Tagus estuary, Portugal.  

Science.gov (United States)

In this work, we analyze environmental (physical and chemical) and biological (phytoplankton) data obtained along Tagus estuary during three surveys, carried out in productive period (May/June/July) at ebb tide. The main objective of this study was to identify the key environmental factors affecting phytoplankton structure in the estuary. BIOENV analysis revealed that, in study period, temperature, salinity, silicate and total phosphorus were the variables that best explained the phytoplankton spatial pattern in the estuary (Spearman correlation, rho=0.803). A generalized linear model (GLM) also identified salinity, silicate and phosphate as having a high explanatory power (63%) of phytoplankton abundance. These selected nutrients appear to be consistent with the requirements of the dominant phytoplankton group, Baccilariophyceae. Apparently, phytoplankton community is adapted to fluctuations in light intensity, as suspended particulate matter did not come out as a key factor in shaping phytoplankton structure along Tagus estuary. PMID:17884159

Brogueira, Maria José; Oliveira, Maria do Rosário; Cabeçadas, Graça

2007-12-01

274

MORE THAN JUST BAIT: BURROWING SHRIMP AS ECOSYSTEM ENGINEERS IN OREGON ESTUARIES - SEPTEMBER 2006  

Science.gov (United States)

Burrowing shrimp may be most widely known as excellent fishing bait, but they also play important roles in estuaries of the Pacific Northwest. These shrimps strongly affect carbon and nutrient cycling, phytoplankton abundance, food web structure and dynamics, sediment stability,...

275

QUANTIFYING SEASONAL SHIFTS IN NITROGEN SOURCES TO OREGON ESTUARIES. PART I: EMPIRICAL 15N MACROALGAE DATA  

Science.gov (United States)

?Green Tides? are typically considered to be a symptom of eutrophication associated with anthropogenic nutrient loading. In many estuaries along the Pacific Northwest (PNW), the seasonal development of macroalgal mats or ?Green Tides? coincides with the initiation of coastal upw...

276

Fin Fish Biodiversity Of A Tropical Sal Estuary, Goa, West Coast Of India  

Directory of Open Access Journals (Sweden)

Full Text Available Sal estuary represents rich biodiversity because of the heavy rains during the south west monsoon and lack of any industrial development along the banks of the river. Attempt was made to survey the fin fish biodiversity along the estuary to fulfill the lack of adequate information regarding estuarine fisheries. Hydrological parameters were analysed during the study period and found to be highly influencing. Fishes were caught near shore by using gill nets and cast nets. About 35 fin fishes were recorded belonging to 28 families. The distribution varies according to the environmental conditions. Some of the important fin fishes found in this estuary are Mugil cephalus, Gerres filamentosus, Sillago sihama, Etroplus suratensis, Arius arius, Lutjanus argentimaculatus, Acanthopagrus berda and Lobotes surinamensis. Some of the fresh water species are also observed in the Sal river. In future, Industrialization along the bank of the estuary may threaten the species diversity and need necessary laws for conservation of biodiversity

Nandadeep U. Fal Dessai

2013-09-01

277

Changes in the diet composition of transitory fishes in coastal systems, estuary and continental shelf  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The feeding habits of five species of teleosts in the southern coast of Brazil were analyzed comparatively between estuary and continental shelf. The displacement between the two sites caused expressive qualitative alterations, the proportion of different items varying from 50% in the diet of Micropogonias furnieri to 89% in Isopisthus parvipinnis. In the group of species, 57% of the items were exclusive to one of the environments and, within the three most common items in the estuary - fish,...

Chaves, Paulo T. C.; Umbria, Simone C.

2003-01-01

278

Salt intrusion in multi-channel estuaries: a case study in the Mekong Delta, Vietnam  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There is a well-tested theory for the computation of salt intrusion in alluvial estuaries that is fully analytical and predictable, in the sense that it has well-tested analytical equations to predict the mixing behaviour of the estuary based on measurable quantities, such as channel topography, river discharge and tidal characteristics. This theory has been described in a range of publications (Savenije, 1986, 1989, 1993) and a recent book (Savenije, 2005). This theory applies to single-chan...

Nguyen, A. D.; Savenije, H. H. G.

2006-01-01

279

Contrasting Patterns of Phytoplankton Community Pigment Composition in Two Salt Marsh Estuaries in Southeastern United States  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Phytoplankton community pigment composition and water quality were measured seasonally along salinity gradients in two minimally urbanized salt marsh estuaries in South Carolina in order to examine their spatial and temporal distributions. The North Inlet estuary has a relatively small watershed with minimal fresh water input, while the Ashepoo, Combahee, and Edisto (ACE) Basin is characterized by a relatively greater influence of riverine drainage. Sampling stations were located in regions o...

Noble, Peter A.; Tymowski, Raphael G.; Fletcher, Madilyn; Morris, James T.; Lewitus, Alan J.

2003-01-01

280

Seasonal variation of heavy metals in Mytilus edulis, Fucus vesiculosus and sediment from the Shannon estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Samples of Mytilus edulis, together with samples of sediment and Fucus vesiculosus, were taken monthly from each of five shores on the south coast of the Shannon Estuary from March 1992 to December 1993 inclusive. Samples were digested individually and the levels of iron, zinc, manganese, cobalt, chromium and copper were determined using atomic absorption spectrophotometry. Levels of metals were lower than previously published values from Irish east coast estuaries, including Dublin, except f...

Breen, John; O Leary, Caitriona

1998-01-01

 
 
 
 
281

Occurrence of Cymbasoma longispinosum Bourne, 1890 (Copepoda: Monstrilloida) in the Curuçá River estuary (Amazon Littoral)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present work was carried out to verify the occurrence and distribution of Cymbasoma longispinosum Bourne, 1890 in a tropical Amazon estuary from North Brazil. Samplings were performed bimonthly from July/2003 to July/2004 at two different transects (Muriá and Curuçá rivers) situated along the Curuçá estuary (Pará, North Brazil). Samples were collected during neap tides via gentle (1 to 1.5 knots) 200 ?m-mesh net tows from a small boat. Additional subsurface water samples were c...

Leite, Nata?lia R.; Pereira, Luci C. C.; Fernando Abrunhosa; Pires, Marcus A. B.; Da Costa, Rauqui?rio M.

2010-01-01

282

An introduction to the San Francisco Estuary tidal wetlands restoration series  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Restoration of tidal wetlands may provide an important tool for improving ecological health and water management for beneficial uses of the San Francisco Estuary (hereafter ?Estuary?). Given the large losses of tidal wetlands from San Francisco Bay and the Sacramento-San Joaquin Delta in the last 150 years, it seems logical to assume that restoring tidal wetlands will have benefits for a variety of aquatic and terrestrial native species that have declined during the same time period...

2003-01-01

283

Data on nutrition of amur sturgeon Acipenser schrenckii and kaluga Acipenser dauricus in the Amur estuary  

Directory of Open Access Journals (Sweden)

Full Text Available Data on nutrition of Amur sturgeon and kaluga in the Amur estuary are presented for the first time. It is found that the main food of Amur sturgeon consists of polychaetes (75.2 % and mol-luscs (more than 90 %, as crustaceans (71.9 % and fishes (66.2 % are dominant in kaluga food composition. Regional peculiarities of both species feeding in different areas of the Amur estuary are described.

Kolobov Vladimir Yurievich

2013-09-01

284

Spatial Distribution of Copepods along the Salinity Gradient of Perai River Estuary, Penang, Malaysia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Investigation on copepod communities in Perai river estuary was conducted from November 2005 to May 2006. Five stations were established for monthly sampling and were located from the river mouth to the upper reaches of the river. Copepod samples were collected from vertical tows using a standard zooplankton net. The Perai river estuary was slightly stratified and salinity decreases significantly from the mouth of the river towards the upper reaches of the river. A total of 28 species of cope...

Johan, I.; Wan Maznah, W. O.; Mashhor, M.; Abu Hena, M. K.; Amin, S. M. N.

2012-01-01

285

Nutrient behavior in 2 contrasting scottish estuaries, the Forth and Tay  

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The distribution and behaviour of nutrients (nitrate, nitrite, ammonia, silicate and phosphate) have been examined over the course of a year in two major Scottish estuaries, the Forth and Tay. Maximum concentrations of nitrate and silicate in both estuaries occur in winter, when mixing is conservative. By contrast maximum phosphate, ammonia and nitrite concentrations (notably in the Forth) are observed in summer, these are related to lower oxygen concentrations both within the water column an...

Balls, Pw

1992-01-01

286

Estuary planning and management in Portugal: sharing local boundaries for water resources management  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Estuaries concentrate complex and often conflicting sets of natural, economic and social resources and activities bringing multiple challenges to institutional frameworks, planning and management approaches as well as governance practices dedicated to their protection, maintenance and resilience. Portugal has recently adopted a new set of estuary plans of regulatory nature, which combine the perspective of water resources management with that of land-use management. This paper explores the co...

Fide?lis, Teresa; Carvalho, Teresa

2013-01-01

287

Use of a Real-Time Remote Monitoring Network (RTRM) to Characterize the Guadalquivir Estuary (Spain)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The temporal variability of hydrological variables in the Guadalquivir estuary was examined during three years through a real-time remote monitoring network (RTRM). The network was developed with the aim of studying the influence of hydrodynamical and hydrological features within the estuary on the functioning of the pelagic ecosystem. Completing this data-gathering network, monthly cruises were performed in order to measure biogeochemical variables that are indicative of the trophic status o...

Gabriel Navarro; Isabel Emma Huertas; Eduardo Costas; Susana Flecha; Manuel Díez-Minguito; Isabel Caballero; Victoria López-Rodas; Laura Prieto; Javier Ruiz

2012-01-01

288

Application of Biotic Indices in Assessing the Ecological Quality Status of Bahrekan Estuary (Persian Gulf )  

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The aim of present study was to examine the macro invertebrates as an assessment tool for characterization of the state of Bahrekan estuary in Persian Gulf, by using different biotic indices. An investigation on benthos was carried out during autumn 2008 to summer 2009 in the Bahrekan estuary (Persian Gulf). In order to identify and assess the benthic community structure, seasonal sampling was done from 21 stations with three replicates using van veen grab (./285 m2). The ecologica...

Shokat, P.; Nabavi, S. M. B.; Savari, A.; Kochanian, P.

2010-01-01

289

Characterization of cytotoxicity and genotoxicity of sediments from a potentially contaminated estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Sado Estuary (W Portugal) is affected by various sources of pollution, associated with the existence of an urban center, heavy-industry, mining activities and agriculture. It also remains a privileged site for fishing activities that are responsible for the supplying of consumable resources either locally or externally. Previous studies revealed sizable amounts of contaminants in the estuary sediments, namely metals, pesticides and polycyclic aromatic hydrocarbons. These compounds can be ...

Pinto, Miguel

2011-01-01

290

Foraminifera, Thecamoebians and Palynomorphs as Hydrodynamic Indicators in Araguari Estuary, Amazonian Coast, Amapá State – Brazil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Araguari estuarine dynamics is singular among traditional models of estuaries under tidal regime due to influence of macrotidal and tidal bore. In order to establish estuarine zones in Araguari according foraminifera, thecamoebians, paliynomorphs and physical-chemistry parameters, sixteen sample stations were established along the estuary. Turbidity and temperature were the environmental parameters which allowed determination of the estuarine gradient. Eighteen species of foraminifera, t...

2010-01-01

291

Dynamics and hydrology of the Tagus estuary : results from in situ observations  

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The present study was carried out with the main objective of describing some aspects of the physical oceanography of the Tagus Estuary, in order to increase the understanding of its dynamics, namely in what concerns the propagation of the tide within the estuary, the thermohaline and circulation patterns and the role of the principal forcing mechanisms of the estuarine dynamics. The study was based on the analysis of a comprehensive observational data set of the Tagus Estuar...

Neves, Filipe Dos Santos

2010-01-01

292

Numerical modeling of cohesive sediment transport and bed morphology in estuaries  

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Two major lines of investigation have been pursued in this thesis: (1) More efficient, robust and realistic numerical techniques are designed for the simulation of complex turbulent fluid flows; (2) A new algorithm and its analysis is performed in the context of multiphasic fluid flow, for a cohesive fine-grained sediment (fluid mud) transport in estuaries. Estuaries exist between marine and freshwater system where waters of different physical, chemical and biological composition meet, combin...

Leupi, Ce?lestin

2005-01-01

293

The ecology and taxonomy of estuarine benthic diatoms and their use as bioindicators in a highly stratified estuary (Ebro Estuary, NE lberian Peninsula): a multidisciplinary approach = L’ecologia i la taxonomia de les diatomees bentòniques estuarianes i el seu ús com a bioindicadors en un estuari altament estratificat (l’estuari de l’Ebre, NE Península Ibèrica): un estudi multidisciplinari.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The general aim of the thesis was to improve knowledge of the ecology and taxonomy of estuarine benthic diatoms in a highly stratified Mediterranean estuary, in order to evaluate their potential use as bioindicators of this ecosystem. To achieve that, diatom community composition was described and the factors affecting its composition and distribution were elucidated. Once the main anthropogenic pressures in the Ebro Estuary had been established, the response of diatoms to these pressures was...

Rovira Torres, Laia

2013-01-01

294

Impact of climate variability on ichthyoplankton communities: An example of a small temperate estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent variations in the precipitation regime across southern Europe have led to changes in river fluxes and salinity gradients affecting biological communities in most rivers and estuaries. A sampling programme was developed in the Mondego estuary, Portugal, from January 2003 to December 2008 at five distinct sampling stations to evaluate spatial, seasonal and inter-annual distributions of fish larvae. Gobiidae was the most abundant family representing 80% of total catch and Pomatoschistus s...

Primo, Ana Li?gia; Azeiteiro, Ulisses Miranda; Marques, So?nia Cotrim; Pardal, Miguel A?ngelo

2011-01-01

295

Morphological controls in sandy estuaries: the influence of tidal flats and bathymetry on sediment transport  

Science.gov (United States)

The morphodynamics of shallow, vertically well-mixed estuaries, characterised by tidal flats and deeper channels, have been investigated. This paper examines what contributes to flood/ebb-dominant sediment transport in localised regions through a 2D model study (using the TELEMAC modelling system). The Dyfi Estuary in Wales, UK has been used as a case study and, together with idealised estuary shapes, shows that shallow water depths lead to flood dominance in the inner estuary whilst tidal flats and deep channels cause ebb dominance in the outer estuary. For medium sands and with an artificially ‘flattened’ bathymetry (i.e. no tidal flats), the net sediment transport switches from ebb-dominant to flood-dominant where the parameter a/ h (local tidal amplitude ÷ local tidally averaged water depth) exceeds 1.2. Sea level rise will reduce this critical value of a/ h and also reduce the ebb-directed sediment transport significantly, leading to a flood-dominated estuarine system. A similar pattern, albeit with greater transport, was simulated with tidal flats included and also with a reduced grain size. This suggests that analogous classifications for flood/ebb asymmetry of the tide in estuaries as a whole may not represent the local sediment transport in sufficient detail. Through the Dyfi simulations, the above criterion involving a/ h is shown to be complicated further by augmented flow past a spit at the estuary mouth which gives rise to a self-maintaining scour hole. Simulations of one year of bed evolution in an idealised flat-bottomed estuary, including tidal flow past a spit, recreate the flood/ebb dominance on either side of the spit and the formation of a scour hole in between. The erosion rate at the centre of the hole is reduced as the hole deepens, suggesting the establishment of a self-maintaining equilibrium state.

Robins, Peter Edward; Davies, Alan G.

2010-06-01

296

A discontinuity in mantle composition beneath the southwest Indian ridge.  

Science.gov (United States)

The composition of mid-ocean-ridge basalt is known to correlate with attributes such as ridge topography and seismic velocity in the underlying mantle, and these correlations have been interpreted to reflect variations in the average extent and mean pressures of melting during mantle upwelling. In this respect, the eastern extremity of the southwest Indian ridge is of special interest, as its mean depth of 4.7 km (ref. 4), high upper-mantle seismic wave velocities and thin oceanic crust of 4-5 km (ref. 6) suggest the presence of unusually cold mantle beneath the region. Here we show that basaltic glasses dredged in this zone, when compared to other sections of the global mid-ocean-ridge system, have higher Na(8.0), Sr and Al2O3 compositions, very low CaO/Al2O3 ratios relative to TiO2 and depleted heavy rare-earth element distributions. This signature cannot simply be ascribed to low-degree melting of a typical mid-ocean-ridge source mantle, as different geochemical indicators of the extent of melting are mutually inconsistent. Instead, we propose that the mantle beneath approximately 1,000 km of the southwest Indian ridge axis has a complex history involving extensive earlier melting events and interaction with partial melts of a more fertile source. PMID:12610622

Meyzen, Christine M; Toplis, Michael J; Humler, Eric; Ludden, John N; Mével, Catherine

2003-02-13

297

Oceanic eddy formation and propagation southwest of Taiwan  

Science.gov (United States)

Oceanic eddies are active and energetic southwest of Taiwan. The formation and propagation of eddies in this area were investigated using 17 year satellite altimeter data. Cyclonic eddies (CEs) and anticyclonic eddies (ACEs) often coexisted, but there were more CEs than ACEs generated during the period from October 1992 to October 2009. ACEs were stronger and, in general, lived longer than CEs. ACEs occurred more often in winter than in other seasons, while CEs were more frequent in summer. Compared with the direct local wind forcing, the Kuroshio path variability appears to be a dominant factor for eddy formation in this area. A conceptual model of an eddy-Kuroshio interaction is proposed. In summer, there exists an outflow northwest of Luzon Island, and the Kuroshio likely leaps across the Luzon Strait. To the north of the outflow and left of the Kuroshio axis, CEs are often formed, which in turn induce ACEs to the west of CEs. In winter, under the influence of northeasterly monsoon, the Kuroshio Current Loop (KCL) appears southwest of Taiwan more frequently than in other seasons, and ACEs are frequently shed from the KCL. Most of the ACEs propagate westward, and, as a result, CEs are often spun up to the east of the ACEs. The surface South China Sea outflow in summer and the KCL in winter are, however, likely related to the monsoons. Therefore, the indirect effects of monsoon winds are also evident in the seasonal variations of eddy occurrence.

Nan, Feng; Xue, Huijie; Xiu, Peng; Chai, Fei; Shi, Maochong; Guo, Peifang

2011-12-01

298

Guidelines for determining inputs of inorganic contaminants into estuaries  

International Nuclear Information System (INIS)

This publication describes sampling and sample preparation procedures suitable to obtain unpolluted samples for the purpose of determining river inputs of inorganic pollutants into estuaries. Emphasis is placed on heavy metal pollutants but procedures are suitable, with appropriate modifications for other inorganic pollutants. For example, the collection of samples for mercury may require modifications of handling procedures. River water samples are collected at the most down-river point where no estuarine influences effect results. Samples are collected using a peristaltic pump and separated into aqueous and particulate phases for pollutant analysis. As is the case of all trace pollutant analyses, meticulous care is required to prevent pollution of the sample and in addition to the precautions described in this method, great personal attention is required to minimize sample handling, pollution by smoke, hands, hair, dust, talc from gloves, etc., and to avoid all contact of the samples and reagents with skin and metallic objects. 1 ref., 3 figs, 1 tab

1987-08-01

299

Numerical Simulation of Contaminant Dispersion in Estuary Flows  

Science.gov (United States)

The paper examines in detail the dispersion of a passive contaminant in steady and oscillatory turbulent shear flow in a two-dimensional channel. The aim of this examination is to understand dispersion in estuaries. A new method of analysing and predicting concentration distributions has been developed from work of Sullivan (J. Fluid Mech. 49, 551-576 (1971)). A random walk technique is used, the contaminant being represented by a large number of marked particles whose paths are tracked as they move through the fluid. The technique seeks to model the physics of dispersion more realistically than the standard diffusion equation, and results from the simulation, with input based on data taken in the Mersey, show it to be a useful and versatile method of studying dispersion in oscillatory flows.

Allen, Catherine M.

1982-05-01

300

Tidal variations of particulate carbohydrates in the Mersey estuary  

Science.gov (United States)

The composition of monosaccharides and their variations in concentration in suspended particles and sediments have been examined for samples from two sites in the River Mersey estuary. Samples were collected over a tidal cycle and the compositional changes as a function of tidal state are reported. Higher concentrations of carbohydrates were found in the lower-salinity region with glucose being the dominant monosaccharide at both sample sites. Carbohydrates contributed between 14 and 17% of the organic carbon present. The detailed monosaccharide speciation indicates that the primary sources of monosaccharides are angiosperm leaves and grasses rather than phytoplankton. Carbohydrate concentrations were somewhat higher in the suspended particles than in the underlying sediments and various hypotheses are advanced to explain this phenomenon.

Preston, Martin R.; Prodduturu, Prabhakar

1992-01-01

 
 
 
 
301

Turbulent nitrate fluxes near a sill in a large estuary  

Science.gov (United States)

Historical nitrate concentration profiles and new turbulent microstructure observations were combined to calculate turbulent nitrate fluxes in the Lower St. Lawrence Estuary (LSLE), Canada. Two stations were compared: the head of the Laurentian Channel (st. 25), where intense mixing occurs on the shallow sill that marks the upstream limit of the LSLE, and another station located about 100 km downstream (st. 23). Nitrate fluxes at the base of the surface layer for both stations were respectively (with the 95% confidence interval): F25 = 64(23,130)mmolm-2 d-1 and F23 = 0.11(0.04,0.23)mmolm-2 d-1. Observations suggest that the interplay between large isopleths heaving near the sill and strong turbulence is the key mechanism to sustain such high turbulent nitrate fluxes at station 25 (about 600 times those at station 23). Calculations also suggest that these localised large fluxes can sustain almost entirely the post-bloom new production over the whole LSLE.

Cyr, Frédéric; Bourgault, Daniel; Galbraith, Peter S.; Gosselin, Michel

2014-05-01

302

Electrochemical behavior of Al—basic sacrificial anode at estuary  

Science.gov (United States)

The Al—basic sacrificial anode is widely used to protect steel construction from corrosion in seawater, but is not suitable for protecting steel in freshwater. In the estuary area, seawater and freshwater mix and different seawater salinity can be formed in different mixing sites between freshwater and seawater. Based on the requirements of the Shengli Petroleum Administrative Bureau of China, the effect of seawater salinity on electrochemical properties of Al—basic anode was studied under laboratory conditions by the method given in National Standard GB 4948-85 (China Starndard Bureau, 1985). No obvious effect was found when seawater salinity was 30 to 10, but obvious effect on anodic open circuit potential, closed circuit potential and current efficiency was found when seawater salinity was 5. These values are lower than those given in the National Standard.

Zhang, Jing-Lei; Hou, Bao-Rong; Li, Hong-Ling; Yang, Fang-Ying; Xie, Xiao-Bo

1996-09-01

303

Observations on the fish populations of an east coast estuary  

Energy Technology Data Exchange (ETDEWEB)

Monthly samples of fish were collected from the cooling-water intake screens at Kingsnorth Power Station on the Medway Estuary. A total of 26,372 fish, comprising 41 species, was recorded between April 1981 and August 1983. The seasonal distribution of both species numbers and abundance of fish was similar to earlier studies, although the community structure has altered in recent years. The regular occurrence and increased population size of Osmerus eperlanus, the smelt, and Clupea harengus, the herring, were the most notable changes. The results are compared with previous studies, and the indirect effects of enhance water quality conditions in the tidal Thames and the subsequent recolonization by fish, which were previously absent for many years, are discussed. 11 references, 44 figures.

Wharfe, J.R.; Wilson, S.R.; Dines, R.A.

1984-04-01

304

Nutrient budgets for large Chinese estuaries and embayment  

Directory of Open Access Journals (Sweden)

Full Text Available Nutrient concentrations among the Chinese rivers and bays vary 10–75 fold depending on nutrient elements. The silicic acid levels in South China rivers are higher than those from North China rivers and the yields of dissolved silicate increased from the north to the south of China, indicating the effect of climate on weathering. The nutrient levels in Chinese rivers are higher than those from the large and less-disturbed world rivers such as Amazon and Zaire, but comparable to the values for European and North American polluted and eutrophic rivers like the Loire and Po. This may be ascribed to both of extensive leaching and influences from agricultural and domestic activities over the drainage basins of Chinese rivers. DIN:PO3?4 ratios in most of Chinese rivers and bays are higher (up to 2800 than the other rivers in the world. The atomic ratios of DIN to PO43? in the major Chinese rivers and embayment decrease in exponential trend with increase in the atomic ratios of PO43? to Si(OH4, indicating that primary production in coastal environments changes with the nutrients transport when the urbanization develops to a certain extent, and the potential limited nutrient elements can be changed from phosphorus to nitrogen limitation, which can modify aquatic food webs and then the ocean ecosystem.

A simple steady-state mass-balance box model was employed. The output shows that the estuaries and embayment behave as a sink or source of nutrients. For the major Chinese estuaries, both residual and mixing flow transport nutrients off the estuaries, and nutrient transport fluxes in summer is 3–4 fold that in winter except comparable for NH4+. These fluxes are 1.0–1.7 fold that estimated by timing riverine nutrient concentrations and freshwater discharge. For the major Chinese embayment, nutrient elements are transported to China Seas except PO43? and Si(OH4 in Sanggou Bay and Jiaozhou Bay. Seasonally, nutrients transport fluxes off the bays in the summer are 2.2–7.0 fold that in the winter. In the embayment, the exchange flow dominated the water budgets, resulting in average system salinity approaching the China seas salinity where river discharge is limited. The major Chinese estuaries and embayment transport 1.0–3.1% of nitrogen, 0.2–0.5% of phosphorus and 3% of silicon necessary for phytoplankton growth for the China Seas. This demonstrates regenerated nutrients in water column and sediments and nutrients transport fluxes between the China Seas and open ocean play an important role for phytoplankton growth. Atmospheric deposition may be another important source of nutrients for the China Seas.

S. M. Liu

2009-01-01

305

Effects of river discharge and high-tide stage on salinity intrusion in the Weeki Wachee, Crystal, and Withlacoochee River estuaries, southwest Florida  

Science.gov (United States)

The Weeki Wachee, Crystal, and Withlacoochee Rivers are coastal streams flowing into the Gulf of Mexico that may be affected by either future surface water or groundwater withdrawals. Reduction of river discharge will affect the upstream extent of saltwater intrusion in the rivers; however, under certain reduced low-flow discharges, the estimated change in upstream extent of saltwater intrusion is on the order of several tenths of a mile and frequently is within the range of predicted error. Data on flow, tides, and salinity describe the physical characteristics of the Weeki Wachee, Crystal, and Withlacoochee River systems. Vertical and longitudinal salinity profiles indicate that salinity of the rivers increases downstream and varies substantially at any given location. The Weeki Wachee River system is the best mixed of the three. The Crystal River system exhibited the next best mixed system, and the Withlacoochee River system exhibited the most variation in its salinity regime. The daily maximum upstream extent of salinity intrusion is described by multiple linear-regression analysis based on daily mean streamflow of each river and high-tide stage of the gulf. The equations are used to show the effects of discharge on the daily maximum upstream extent of salinity intrusion in the rivers. (USGS)

Yobbi, D. K.; Knochenmus, L. A.

1989-01-01

306

Sedimentary mercury dynamics in Great Bay Estuary (NH) (Invited)  

Science.gov (United States)

Due to the significant sedimentation of river-borne particulate matter in estuaries these zones act as repositories for particulate contaminants including Hg. Estuarine sediments have a high degree of variability in geochemical characteristics and infaunal density, and are subject to significant fluctuations in water level and salinity that result in redox transitions in the zone close to the sediment-water interface (SWI). We performed pore-water and sediment chemical and molecular analyses to study Hg cycling at two mudflats in Great Bay Estuary (NH). Both sites had relatively similar total sediment Hg. The site with a higher infaunal density (Portsmouth), however, had a significantly higher sediment Fe(III) concentration, but lower DOC, alkalinity and acid-volatile sulfide (AVS) concentrations than the site with a lower infaunal density (Squamscott). The extent of bioturbation at both sites was characterized by measurement of sediment 7Be concentration with a half-life of 57 d. Squamscott site had significantly higher pore-water Hg and MeHg, and solid-phase MeHg concentrations. At this site, pore-water and solid-phase MeHg showed distinct coincident peaks close to the SWI, whereas at Portsmouth site, no MeHg peaks were observed within the top 10 cm. Molecular analysis showed that the two mudflats had similar concentration and distribution of sulfate- and iron-reducers, but Squamscott had significantly higher mer-A gene (with peak corresponding to peak in inorganic Hg) and methanogen concentrations. Our findings suggest that the presence of high Fe(III) concentrations in the more bioturbated sediments may control the extent of inorganic Hg availability for methylation.

Amirbahman, A.; Brown, L.; Voytek, M. A.; Chen, C.

2009-12-01

307

The Temperature and Salinity Variabilities at Cisadane Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available The study was conducted at Cisadane Estuary at 18 oceanographic station in Transition Monsoon Season I, East Monsoon Season, and Transition Monsoon Season II from 2003 to 2005. The area of the study was located at the longitude of 106.58° - 106.70° E and the latitude of 5.96° - 6.02°S. The measurements of temperature, salinity, tubidity and light transmision used CTD (Conductivity, Temperature and Depth Model SBE-19. The result shows that the temperature and salinity vertical profil variabilities at Cisadane Estuary underwent a change in the influence of Transition Monsoon Season I, East Monsoon Season, and Transition Monsoon Season II, for example it was obtained the leg time of the maximum salinity of Transition Monsoon Season II as the same as that of East Monsoon Season. Based on the horizontal and vertical distribution pattern analysis of the interaction between low salinity fresh water of Cisadane River and high salinity sea water of Java Sea, it was also influenced by the season variability and tide. The surface layer was much more influenced by the low salinity and the heat of sunray (seasonal variability with the weaker intensity to the lower layer. The change of the heat energy by the increase of seasonal temperature occurred in September 2003 to May 2004 ((?E = 600.6 ? 105 Joule, July to November 2005 (?E = 84.9 Joule. The decrease of the heat energy occurred in June to September 2003 ((-267.6 ? 105, May ke October 2004 (?E = 189.3 ? 105 Joule and October 2004 to July 2005 (?E = -215.4 ? 105 Joule.

Hadikusumah

2008-11-01

308

Facilitation of the Estuary/Ocean Subgroup for Research, Monitoring, and Evaluation, FY06 Annual Report  

Energy Technology Data Exchange (ETDEWEB)

This annual report is a deliverable for fiscal year 2006 (FY06) for Project 2002-077-00, Facilitation of the Estuary/Ocean Subgroup (EOS). The EOS is part of the research, monitoring, and evaluation (RME) effort the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) developed in response to the 2000 and 2004 Biological Opinions on operation of the Federal Columbia River Power System. The goal of the EOS project is to facilitate activities of the estuary/ocean RME subgroup as it coordinates implementation of the Estuary RME Plan. In FY06, EOS project accomplishments included: 1) subgroup meetings; 2) participation in the estuary work group of the Pacific Northwest Aquatic Monitoring Partnership; 3) project management via the project tracking system, PISCES; 4) quarterly project status reports; and 5) a major revision to the Estuary RME Plan (new version May 2006) based on comments by EOS members, the Independent Scientific Review Panel, and other reviewers. In the context of uncertainty about the direction of the federal RME due to litigation on the FCRPS Biological Opinion, FY06 activities for the EOS project resulted in expanded substantive coordination with other regional RME forums, project tracking infrastructure, and a new version of the Estuary RME Plan.

Johnson, Gary E.

2006-10-03

309

The carbonate system of the amur estuary and the adjacent marine aquatic areas  

Science.gov (United States)

In July 2007, integrated studies of the Amur Estuary and the adjacent aquatic areas were performed on board R/V Professor Gagarinskii within the project of the Amur River basin exploration. On the basis of the data obtained during the cruise, the carbonate system of the Amur Estuary in the summer period was considered. It was shown that the distribution of the carbonate parameters in the Amur Estuary and the adjacent aquatic areas points to the high intensity of the bio-geochemical processes of production and mineralization of organic matter. It was found that the organic matter destruction is prevailing over the photosynthesis in the riverine part of the estuary. This aquatic area is a source of carbon dioxide for the atmosphere and rates as a heterotrophic basin. On the contrary, the surface waters at the outer boundaries of the estuary (the Gulf of Sakhalin and the Tatar Strait) act as a sink of the atmospheric carbon dioxide, which is caused by the intense photosynthesis in this area. This part of the estuary is treated as an autotrophic basin.

Koltunov, A. M.; Tishchenko, P. Ya.; Zvalinskii, V. I.; Chichkin, R. V.; Lobanov, V. B.; Nekrasov, D. A.

2009-10-01

310

Chiral source apportionment of polychlorinated biphenyls to the Hudson River estuary atmosphere and food web.  

Science.gov (United States)

The New York/New Jersey Harbor Estuary is subject to significant contamination of polychlorinated biphenyls (PCBs) from numerous sources, including the historically contaminated Upper Hudson River, stormwater runoff and sewer overflows, and atmospheric deposition from PCBs originating from the surrounding urban area. However, the relative importance of these sources to the estuary's food web is not fully understood. Sources of PCBs to the estuary were apportioned using chiral signatures of PCBs in air, water, total suspended matter, phytoplankton, and sediment. PCBs 91, 95, 136, and 149 were racemic in the atmosphere of the estuary. However, the other phases contained nonracemic PCB 95 and to a lesser extent PCB 149. Thus, the predominant atmospheric source of these congeners is likely unweathered local pollution and not volatilization from the estuary. The similarity in chiral signatures in the other phases is consistent with dynamic contaminant exchange among them. Chiral signatures in the dissolved phase and total suspended matter were correlated with Upper Hudson discharge, suggesting thatthe delivery of nonracemic contaminated sediment from the Upper Hudson, not the atmosphere, controls phytoplankton uptake of some PCBs. Thus, measures to control PCB contamination in the Upper Hudson should be effective in reducing loadings to the estuary's aquatic ecosystem. PMID:17937297

Asher, Brian J; Wong, Charles S; Rodenburg, Lisa A

2007-09-01

311

Potential Impacts and Management Implications of Climate Change on Tampa Bay Estuary Critical Coastal Habitats  

Science.gov (United States)

The Tampa Bay estuary is a unique and valued ecosystem that currently thrives between subtropical and temperate climates along Florida's west-central coast. The watershed is considered urbanized (42 % lands developed); however, a suite of critical coastal habitats still persists. Current management efforts are focused toward restoring the historic balance of these habitat types to a benchmark 1950s period. We have modeled the anticipated changes to a suite of habitats within the Tampa Bay estuary using the sea level affecting marshes model under various sea level rise (SLR) scenarios. Modeled changes to the distribution and coverage of mangrove habitats within the estuary are expected to dominate the overall proportions of future critical coastal habitats. Modeled losses in salt marsh, salt barren, and coastal freshwater wetlands by 2100 will significantly affect the progress achieved in "Restoring the Balance" of these habitat types over recent periods. Future land management and acquisition priorities within the Tampa Bay estuary should consider the impending effects of both continued urbanization within the watershed and climate change. This requires the recognition that: (1) the Tampa Bay estuary is trending towards a mangrove-dominated system; (2) the current management paradigm of "Restoring the Balance" may no longer provide realistic, attainable goals; (3) restoration that creates habitat mosaics will prove more resilient in the future; and (4) establishing subtidal and upslope "refugia" may be a future strategy in this urbanized estuary to allow sensitive habitat types (e.g., seagrass and salt barren) to persist under anticipated climate change and SLR impacts.

Sherwood, Edward T.; Greening, Holly S.

2014-02-01

312

Pollution in the estuary of the Baracoa river, La Habana, Cuba  

Directory of Open Access Journals (Sweden)

Full Text Available The environmental quality of the Baracoa river estuary was studied from the physic (temperature and salinity, chemic variables (dissolved oxygen, oxygen biochemical demand (DBO, oxygen chemical demand (DQO, nitrogen cycle, inorganic phosphorus and total phosphorus and the microbiological variables (total and thermotolerant coliforms and faecal streptococci. The samplings were made on February 2006, May and October 2007. Spatial distribution of the physical and chemical parameters measured suggests that the estuary is dominated by the marine conditions. The salinity and temperature analyses show that in general the characteristics of the estuary could be influenced by the contribution of the river basin drainage. In general, the concentrations of the measured parameters in the Baracoa river estuary, strongly suggest that this area is under influence of human activities on the river basin, due to the low levels of dissolved oxygen and an oxygen average deficit of -1.6 mg/L. nthropogenic actions in this estuary are mainly related to the emission of domestic and farming rejects without suitable treatment. This is visibly associated with the observed values of the total coliforms concentrations as well as the concentration of faecal streptococci, that surpassed reference values from the Cuban norm for water quality, following on bad or doubtful quality levels pointing out negatively measurements made next to the communication channel the estuary and the El Doctor lagoon.

Regla Duthit Somoza

2011-04-01

313

78 FR 43964 - Intent To Prepare a Supplemental Draft Environmental Impact Statement for the Southwest Light...  

Science.gov (United States)

...Environmental Impact Statement for the Southwest Light Rail Transit Extension Project (Formerly...Impact Statement (SDEIS) for the Southwest Light Rail Transit Extension (SWLRT) Project...2012. The Project is a new 15.8-mile light rail alignment with 17 new light rail...

2013-07-22

314

Granitoids of South Korea and Southwest Japan. Trace element evidence regarding their differentiation  

International Nuclear Information System (INIS)

Although we have already published our trace element data for granitoids of South Korea and Southwest Japan, and we have interpreted REE patterns and Ba, Rb and Sr relationships of the granitoids (Tsusue et al., 1986, 1987a, 1987b, 1988), we intend to review briefly the trace element data of South Korea and Southwest Japan in this report. (J.P.N.)

1994-07-01

315

Haemocytic leukemia in Prince Edward Island (PEI) soft shell clam (Mya arenaria): Spatial distribution in agriculturally impacted estuaries  

International Nuclear Information System (INIS)

Intensive farming of potatoes in Prince Edward Island (PEI) relies on the repeated and widespread application of fertilizers and pesticides. In PEI the main potato farming areas are in close proximity and drain directly to estuaries. Runoff from high agricultural activity watersheds could impact benthic organism health in the depositional zone of downstream estuaries. The estuarine filter feeder Mya arenaria (soft-shell clam) could be particularly vulnerable to both particle-adsorbed and water soluble contaminants. M. arenaria is susceptible to haemocytic leukemia. In May 2009, we established that heavily proliferated leukemia (HPL) prevalence was generally higher in PEI estuaries located downstream of high intensity potato farming (Dunk and Wilmot estuaries) watersheds than in estuaries downstream of lower intensity areas. Using Mab-1E10 based immunocytochemistry we observed that leukemic haemocytes from the Dunk and Wilmot estuaries were 1E10 negative whereas those from the Ox/Sheep estuary (low potato farming intensity) were 1E10 positive. The expression of genes in the p53 tumour suppressor pathway enabled us to differentiate groups of leukemic and normal M. arenaria, validating our diagnoses. In October 2009, we confirmed that HPL prevalence was elevated in the Dunk and Wilmot estuaries compared to reference (Souris River). Moreover, leukemia prevalence declined with distance from the river mouths along transects through the Dunk and Wilmot estuaries. The pesticides ß-endosulfan and ?-endosulfan were detected in surface sediments from the Dunk and Wilmot estuaries, but not in sediments from either the Souris River or several other lower intensity potato farming watersheds. Our study provides evidence of an association between intensity of potato farming and prevalence of clam leukemia at downstream estuaries in PEI. - Highlights: ? We examined leukemia prevalence in PEI clams Mya arenaria. ? Prevalence was generally higher downstream of high intensity potato farming. ? Leukemia prevalence declined with distance from source in two impacted estuaries. ? Proteins, gene expression and immunology confirm diagnosis of disease. ? Intensive potato farming may contribute to prevalence of clam leukemia in PEI.

2012-05-01

316

Diatoms from the Pearl River estuary, China and their suitability as a water salinity indicator for coastal environments.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We collected 77 modern diatom samples from sites across the Pearl River estuary, China to analyze the relationship between diatom assemblages and environmental parameters including water salinity, water depth and sediment particle size. Results showed that marine diatoms were dominant in the high salinity environment around Hong Kong and the outer part of the estuary. Brackish water diatoms were found in high abundance in the central part of the estuary. Both marine and brackish water diatoms...

2010-01-01

317

Dune Mining and the Nhlabane Estuary, South Africa: the Effect of a Dredger Crossing on the Zoobenthic Community  

Energy Technology Data Exchange (ETDEWEB)

The Nhlabane Estuary, located on the north-east coast of South Africa, is situated in a titanium dune mining lease area. During 1993, a mining dredger and concentrator crossed the middle reaches of the estuary. For this purpose, two berm walls were constructed across the estuary. Two impacts stemmed from the crossing. A series of fine sediment intrusions into the estuary from the berm wall area occurred during late 1993 and early 1994 and caused a rapid decline in benthic densities and number of taxa. Recovery of the affected area was slow and characterized by initial proliferation of opportunistic colonizers. The berm walls, which divided the estuary in half, were kept in place for nearly three years and caused changes in water quality and the benthic community of the upper and lower halves of the estuary. Artificial breaching of the estuary in August 1995 and removal of the berm walls in May 1996 initiated recovery of the estuary. The success of a second dredger crossing, scheduled for January 1999, depends on addressing the mistakes made during the first crossing and on the speed with which the carefully planned crossing operation, berm wall removal and estuary rehabilitation proceed.

Vivier, L.; Cyrus, D.P

1999-01-01

318

Dune Mining and the Nhlabane Estuary, South Africa: the Effect of a Dredger Crossing on the Zoobenthic Community  

International Nuclear Information System (INIS)

The Nhlabane Estuary, located on the north-east coast of South Africa, is situated in a titanium dune mining lease area. During 1993, a mining dredger and concentrator crossed the middle reaches of the estuary. For this purpose, two berm walls were constructed across the estuary. Two impacts stemmed from the crossing. A series of fine sediment intrusions into the estuary from the berm wall area occurred during late 1993 and early 1994 and caused a rapid decline in benthic densities and number of taxa. Recovery of the affected area was slow and characterized by initial proliferation of opportunistic colonizers. The berm walls, which divided the estuary in half, were kept in place for nearly three years and caused changes in water quality and the benthic community of the upper and lower halves of the estuary. Artificial breaching of the estuary in August 1995 and removal of the berm walls in May 1996 initiated recovery of the estuary. The success of a second dredger crossing, scheduled for January 1999, depends on addressing the mistakes made during the first crossing and on the speed with which the carefully planned crossing operation, berm wall removal and estuary rehabilitation proceed

1999-01-01

319

Sequence stratigraphic and sedimentologic significance of biogenic structures from a late Paleozoic marginal- to open-marine reservoir, Morrow Sandstone, subsurface of southwest Kansas, USA  

Science.gov (United States)

Integrated ichnologic, sedimentologic, and stratigraphic studies of cores and well logs from Lower Pennsylvanian oil and gas reservoirs (lower Morrow Sandstone, southwest Kansas) allow distinction between fluvio-estuarine and open marine deposits in the Gentzler and Arroyo fields. The fluvio-estuarine facies assemblage is composed of both interfluve and valley-fill deposits, encompassing a variety of depositional environments such as fluvial channel, interfluve paleosol, bay head delta, estuary bay, restricted tidal flat, intertidal channel, and estuary mouth. Deposition in a brackish-water estuarine valley is supported by the presence of a low diversity, opportunistic, impoverished marine ichnofaunal assemblage dominated by infaunal structures, representing an example of a mixed, depauperate Cruziana and Skolithos ichnofacies. Overall distribution of ichnofossils along the estuarine valley was mainly controlled by the salinity gradient, with other parameters, such as oxygenation, substrate and energy, acting at a more local scale. The lower Morrow estuarine system displays the classical tripartite division of wave-dominated estuaries (i.e. seaward-marine sand plug, fine-grained central bay, and sandy landward zone), but tidal action is also recorded. The estuarine valley displays a northwest-southeast trend, draining to the open sea in the southeast. Recognition of valley-fill sandstones in the lower Morrow has implications for reservoir characterization. While the open marine model predicts a "layer-cake" style of facies distribution as a consequence of strandline shoreline progradation, identification of valley-fill sequences points to more compartmentalized reservoirs, due to the heterogeneity created by valley incision and subsequent infill. The open-marine facies assemblage comprises upper, middle, and lower shoreface; offshore transition; offshore; and shelf deposits. In contrast to the estuarine assemblage, open marine ichnofaunas are characterized by a high diversity of biogenic structures representing the activity of a benthic fauna developed under normal salinity conditions. Trace fossil and facies analyses allow environmental subdivision of the shoreface-offshore successions and suggest deposition in a weakly storm-affected nearshore area. An onshore-offshore replacement of the Skolithos ichnofacies by the Cruziana ichnofacies is clearly displayed. The lower Morrow fluvio-estuarine valley was incised during a drop of sea level coincident with the Mississippian-Pennsylvanian transition, but was mostly filled during a subsequent transgression. The transgressive nature of the estuarine infill is further indicated by the upward replacement of depauperate brackish-water trace fossil assemblages by the open-marine Cruziana ichnofacies. Additional stratal surfaces of allostratigraphic significance identified within the estuary include the bayline surface, the tidal ravinement surface, the wave ravinement surface, and a basinwide flooding surface recording inundation of the valley interfluves. A younger sequence boundary within the lower Morrow is also recorded in the Gentzler field at the base of a forced regression shoreface, demarcated by the firmground Glossifungites ichnofacies, indicating a rapid basinward facies migration during a sea-level drop. Trace fossil models derived from the analysis of Mesozoic and Cenozoic reservoirs are generally applicable to the study of these late Paleozoic reservoirs. Pennsylvanian brackish-water facies differ ichnologically from their post-Paleozoic counterparts, however, in that they have: (1) lower trace fossil diversity, (2) lower degree of bioturbation, (3) scarcity of crustacean burrows, (4) absence of firmground suites, and (5) absence of ichnotaxa displaying specific architectures designed to protect the tracemaker from salinity fluctuations. Morrow open-marine ichnofaunas closely resemble their post-Paleozoic equivalents. ?? 2002 Elsevier Science B.V. All rights reserved.

Buatois, L. A.; Mangano, M. G.; Alissa, A.; Carr, T. R.

2002-01-01

320

Continuous Resistivity Profiling Data from the Upper Neuse River Estuary, North Carolina, 2004-2005  

Science.gov (United States)

Introduction: The Neuse River Estuary in North Carolina has suffered impacts of eutrophication in recent years. As part of a larger project to better constrain nutrient budgets in the estuary, field investigations were performed to study occurrence and discharge of fresh and brackish ground water and nutrients beneath the estuary itself (fig. 1). A Continuous Resistivity Profiling (CRP) system (Manheim and others, 2004) was used to map the depth of the freshwater-saltwater interface (FSI) in sub-estuarine groundwater. This study area serves as a typological representation of a submarine groundwater environment characteristic of a shallow estuary in a wide coastal plain that has not experienced glaciation. Similar settings extend from New Jersey to Georgia, and along the Gulf of Mexico in the U.S. This report archives 29 lines of data collected during 2004 and 2005 surveys representing almost 210 km of survey lines. These data are further explained in the Data Processing section of the report and previews available of the processed data are available. Eutrophication background -- The Neuse River Estuary suffers from frequent summer fish kills, especially of menhaden, attributed directly or indirectly to natural and anthropogenic eutrophication. Some evidence indicates that these events have become more frequent in recent years. An increasing excess of nutrients is likely derived from accelerating agricultural and residential development of the watershed over the last few decades. Impacts have included declines in dissolved oxygen in stratified estuary water due to consumption by decaying algal biomass, as well as blooms of the toxic dinoflagellate, Pfiesteria piscicida (Burkholder and others, 2005; but see Drgon and others, 2005). Several groups have attempted to develop well-constrained nutrient budgets for the estuary (e.g., Christian and Thomas 2003), and typically have used estimates of direct groundwater delivery in the range of 5% of the total nutrient load. None of the estimates, however, has incorporated specific field measurements in the estuary to determine the actual contribution from direct groundwater discharge. Particular geological features of the estuary suggest that it may receive substantial direct discharge. Background on submarine groundwater discharge -- Contributions of groundwater to flow in rivers have historically been estimated using hydrograph separation (e.g., Sloto and Crouse 1996), but no similar method exists for estuaries. Most efforts have relied on flow modeling based on extrapolation of onshore data on recharge and groundwater flow velocities into the offshore, often assuming that most discharge occurs within a few meters of the shore. Radioisotopic tracer techniques have recently been developed to permit estimation of direct submarine groundwater discharge (SGD) to estuaries and coastal embayments. These approaches can be useful for calculating SGD for regional budgets, and can also be used to broadly identify discharge hotspots (Burnett and Dulaiova 2003; Crusius and others, 2004, 2005a, 2005b). They do not, however, provide subsurface information on the geological controls on the occurrence of freshened groundwater beneath brackish to saline surface water and the style of discharge (i.e., focused vs. diffuse). Geographic and geologic setting -- The Neuse River Estuary (fig. 1) is a drowned river valley located in the Tidewater Region, or the Outer Atlantic Coastal Plain, of North Carolina. It is a tributary of the large Albemarle-Pamlico estuarine system. The estuary has a distinct 'V' shape, with the upper limb oriented NW-SE and the lower limb oriented SW-NE. The hinge is located where the estuary narrows and crosses the Minnesott sand ridge. This feature is a subaerial barrier island complex correlative with the regional Bogue-Suffolk Scarp that separates two marine terraces of different ages to the east and west. Stratigraphic units of Eocene to Pliocene age underlie

Cross, VeeAnn A.; Bratton, John F.; Bergeron, Emile; Meunier, Jeff K.; Crusius, John; Koopmans, Dirk

2006-01-01

 
 
 
 
321

Gravity and magnetic study of Yucca Wash, southwest Nevada  

Energy Technology Data Exchange (ETDEWEB)

Gravity and ground magnetic data were collected along five traverses across and one traverse along Yucca Wash in the southwest quadrant of the Nevada Test Site. Two additional ground magnetic profiles were collected approximately 100 m to either side of the longitudinal profile. These data do not indicate major vertical offsets greater than 100 m using a density contrast of 0.2 to 0.3 g/cm{sup 3} along the proposed Yucca Wash fault. A broad magnetic high coincides with the location of the hydrologic gradient. Density profiling, a technique used to determine the average density of small topographic features, suggests that the density of near-surface material in the vicinity of Yucca Wash is about 2.0 g/cm{sup 3}.

Langenheim, V.E.; Ponce, D.A.; Oliver, H.W.; Sikora, R.F. [Geological Survey, Menlo Park, CA (United States)

1993-12-31

322

Dung of Mammuthus in the arid Southwest, North America  

Science.gov (United States)

The discovery of a unique organic deposit in a dry cave on the Colorado Plateau, southern Utah, permits the first comparison of the physical characteristics and the diet of the dung of the extinct mammoths from the arid Southwest, North America, with that of mammoths from Siberia and northern China, the only other known locations of such remains. The deposit buried beneath sand and rockfall is composed primarily of mammoth dung, estimated at over 300 m 3. Radiocarbon dates on dung boluses indicate that the mammoths frequented the cave between approximately 14,700 and 11,000 yr B.P. (the range of ages at 2?). The desiccated boluses, measuring approximately 230 × 170 × 85 mm, are nearly identical in size to dung from extant elephants. The largest contents in the dung are stalks measuring 60 × 4.5 mm. Grasses and sedges dominated the diet, although woody species were commonly eaten.

mead, Jim I.; Agenbroad, Larry D.; Davis, Owen K.; Martin, Paul S.

1986-01-01

323

Bathymetry of the southwest flank of Mauna Loa Volcano, Hawaii  

Science.gov (United States)

Much of the seafloor topography in the map area is on the southwest submarine flank of the currently active Mauna Loa Volcano. The benches and blocky hills shown on the map were shaped by giant landslides that resulted from instability of the rapidly growing volcano. These landslides were imagined during a 1986 to 1991 swath sonar program of the United States Hawaiian Exclusive Economic Zone, a cooperative venture by the U.S. Geological Survey and the British Institute of Oceanographic Sciences (Lipman and others, 1988; Moore and others, 1989). Dana Seamount (and probably also the neighboring Day Seamount) are apparently Cretaceous in age, based on paleomagnetic studies, and predate the growth of the Hawaiian Ridge volcanoes (Sager and Pringle, 1990).

Chadwick, William W.; Moore, James G.; Fox, Christopher G.

1994-01-01

324

Exploring new drilling prospects in the southwest Pacific  

Science.gov (United States)

A major International Ocean Discovery Program (IODP) workshop covering scientific ocean drilling in the southwest Pacific Ocean was held in Sydney, Australia, in late 2012. The workshop covered all fields of geoscience, and drilling targets in the area from the Equator to Antarctica. High-quality contributions and a positive and cooperative atmosphere ensured its success. The four science themes of the new IODP science plan were addressed. An additional resource-oriented theme considered possible co-investment opportunities involving IODP vessels. As a result of the workshop, existing proposals were revised and new ones written for the April 2013 deadline. Many of the proposals are broad and multidisciplinary in nature, hence broadening the scientific knowledge that can be produced by using the IODP infrastructure. This report briefly outlines the workshop and the related drilling plans.

Gallagher, S. J.; Exon, N.; Seton, M.; Ikehara, M.; Hollis, C. J.; Arculus, R.; D'Hondt, S.; Foster, C.; Gurnis, M.; Kennett, J. P.; McKay, R.; Malakoff, A.; Mori, J.; Takai, K.; Wallace, L.

2014-04-01

325

PIXE analysis of Salado polychrome ceramics of the American Southwest  

Science.gov (United States)

Prehistoric Salado polychrome ceramics of the American Southwest show temporal variation in pigment use depending on location of manufacture during the Classic Period ( A.D. 1250-1450). Proton-induced X-ray emission (PIXE) analysis was undertaken to characterize chemical differences among Pinto, Gila, and Tonto Polychrome paints found in the Tonto Basin, Arizona. White slip samples on pottery from Roosevelt phase ( A.D. 1250-1320) sites are compared to samples from Gila phase ( A.D. 1320-1450) sites. A significant difference was found between the white slips used on the early (Pinto) versus the late (Gila and Tonto) Salado polychrome decorations, suggesting technological and economic changes in pottery manufacture over time.

Gosser, Dennis C.; Ohnersorgen, Michael A.; Simon, Arleyn W.; Mayer, James W.

1998-03-01

326

Gravity and magnetic study of Yucca Wash, southwest Nevada  

International Nuclear Information System (INIS)

Gravity and ground magnetic data were collected along five traverses across and one traverse along Yucca Wash in the southwest quadrant of the Nevada Test Site. Two additional ground magnetic profiles were collected approximately 100 m to either side of the longitudinal profile. These data do not indicate major vertical offsets greater than 100 m using a density contrast of 0.2 to 0.3 g/cm3 along the proposed Yucca Wash fault. A broad magnetic high coincides with the location of the hydrologic gradient. Density profiling, a technique used to determine the average density of small topographic features, suggests that the density of near-surface material in the vicinity of Yucca Wash is about 2.0 g/cm3

1993-01-01

327

Copper smelters and atmospheric visibility in the southwest, seasonal analysis  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the results of the seasonal analysis from a study which has evaluated the effects of copper smelter emissions on atmospheric visibility in southwestern national parks and wilderness areas. The study also examined these effects on an episodic basis and conducted statistical analyses of aerosol and visibility measurement data before and during the summer 1980 copper strike. Copper smelters have been the major emitters of sulfur oxides (SO/sub x/) in the Southwest. The contribution of the copper smelters to visibility reduction versus all other contributions, natural as well as anthropogenic, is estimated at selected locations. This study was initiated to evaluate the effectiveness of the constant emission control (CEC) strategy in improving visibility at southwestern national parks and wilderness areas. The southwestern states of Arizona, Nevada, New Mexico, and Utah are implementing the CEC strategy to control SO/sub x/ emissions from copper smelters as part of their state implementation plans (SIP).

Nochumson, D.H.; Williams, M.D.

1983-01-01

328

Wolf predation in the Burwash caribou herd, southwest Yukon  

Directory of Open Access Journals (Sweden)

Full Text Available The role of wolf predation as a proximate mortality factor influencing caribou herd growth was assessed in the Burwash herd (400 animals in the southwest Yukon between 1980 - 1982. Ten to 14 wolves in two packs preyed primarily on caribou (Rangifer tarandus caribou and moose (Alces alces with disproportionate consumption of caribou (relative to available biomass in the rut and winter periods. Wolf predation was responsible for 72% of total annual mortality in 1980 - 1981 and 46% in 1981 - 1982. Losses due to human harvest varied between 7 to 13%. Additional limited data on climatic factors and winter forage indicated forage-climate were not major proximate mortality factors in 1980 - 1981, but that early-calving climate may have been a factor in increased calf mortality in 1982.

John B. Theberge

1986-06-01

329

Uncertainty quantification of US Southwest climate from IPCC projections.  

Energy Technology Data Exchange (ETDEWEB)

The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) made extensive use of coordinated simulations by 18 international modeling groups using a variety of coupled general circulation models (GCMs) with different numerics, algorithms, resolutions, physics models, and parameterizations. These simulations span the 20th century and provide forecasts for various carbon emissions scenarios in the 21st century. All the output from this panoply of models is made available to researchers on an archive maintained by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) at LLNL. I have downloaded this data and completed the first steps toward a statistical analysis of these ensembles for the US Southwest. This constitutes the final report for a late start LDRD project. Complete analysis will be the subject of a forthcoming report.

Boslough, Mark Bruce Elrick

2011-01-01

330

Complex seasonal cycle of ecohydrology in the Southwest United States  

Science.gov (United States)

This study investigates the causes for, and distribution of, unimodal versus bimodal seasonal cycle of vegetation greenness in the Southwest United States using extensive site observations, climate data, satellite data, and the Lund-Potsdam-Jena (LPJ) vegetation model. Peak vegetation greenness is achieved in a clockwise manner across the Southwest, beginning in spring in the Sonoran Desert following winter rains, then in Utah-Colorado with snowmelt/summer rains, and finally in New Mexico-eastern Arizona with late summer monsoon rains. At high elevations, spring-summer snowmelt is critical for supplying the necessary soil moisture to trigger vegetation growth. A bimodal seasonal cycle of vegetation greenness is evident in satellite data and LPJ simulations across eastern Arizona and western New Mexico, characterized by peaks during late spring-early summer and late summer-early autumn. This bimodal green-up remains a pressing paradox for which many competing hypotheses exist. The mechanism for this seasonal pattern is demonstrated using LPJ and observational data and is found to deviate from the traditional pulse-reserve paradigm. This paradigm states that rainfall events in arid lands produce nearly immediate pulses of vegetation growth and accumulation of reserves but does not consider cold dormancy, time-lagged vegetation responses, or rainfall seasonality. The following soil moisture based mechanism for bimodal greening is proposed. The initial peak in vegetation greenness during late spring-early summer results from a break in cold dormancy and benefits from the gradual winter-long accumulation of deep soil moisture from weak synoptic rain events and snowmelt in colder regions. Limited precipitation and ongoing transpiration, from the initial vegetation greening, trigger a midsummer drying of the soil and a consequential minimum in vegetation activity. Later, pulses of monsoon rainfall in late summer-early autumn support the secondary greening, although significant runoff of brief, intense rainstorms and substantial soil evaporation limit moisture to the upper soil layers.

Notaro, Michael; Liu, Zhengyu; Gallimore, Robert G.; Williams, John W.; Gutzler, David S.; Collins, Scott

2010-12-01

331

A lightning climatology of the South-West Indian Ocean  

Directory of Open Access Journals (Sweden)

Full Text Available The World Wide Lightning Location Network (WWLLN data have been used to perform a lightning climatology in the South-West Indian Ocean (SWIO region from 2005 to 2011. Maxima of lightning activity were found in the Maritime Continent and southwest of Sri Lanka (>50 fl km?2 yr?1 but also over Madagascar and above the Great Lakes of East Africa (>10–20 fl km?2 yr?1. Lightning flashes within tropical storms and tropical cyclones represent 50 % to 100 % of the total lightning activity in some oceanic areas of the SWIO (between 10° S and 20° S.

The SWIO is characterized by a wet season (November to April and a dry season (May to October. As one could expect, lightning activity is more intense during the wet season as the Inter Tropical Convergence Zone (ITCZ is present over all the basin. Flash density is higher over land in November–December–January with values reaching 3–4 fl km?2 yr?1 over Madagascar. During the dry season, lightning activity is quite rare between 10° S and 25° S. The Mascarene anticyclone has more influence on the SWIO resulting in shallower convection. Lightning activity is concentrated over ocean, east of South Africa and Madagascar.

A statistical analysis has shown that El Niño–Southern Oscillation mainly modulates the lightning activity up to 56.8% in the SWIO. The Indian Ocean Dipole has a significant contribution since ~49% of the variability is explained by this forcing in some regions. The Madden–Julian Oscillation did not show significative impact on the lightning activity in our study.

C. Bovalo

2012-08-01

332

Temporal variation of the water budget in Central Southwest Asia  

Science.gov (United States)

Water budget terms for Central Southwest Asia (CSWA) have been computed using National Centre for Environmental Prediction (NCEP) reanalysis data for 60-years from 1948-2007 and European Centre for Medium-Range Weather Forecasts (ERA-40) reanalysis for the 44-year period from 1958-2001. First, observational rainfall data from the Pakistan Meteorological Department (PMD) and the Iran Meteorological Organization (IMO) were compared with Global Prediction Climate Centre (GPCC) version-4 data. GPCC rainfall data appear close to the observational data of the region. GPCC rainfall data have then been used for comparison with both NCEP and ERA-40 reanalysis data sets and it was found that NCEP is closer to GPCC than ERA-40 for this region. The domain under study is located from 45-75E and 25-40N including parts of Iran, Afghanistan, Pakistan, Iraq and Kazakhstan. For realistic results only land areas has been used in the study. In the ERA-40 reanalysis data, evapotranspiration may have been overestimated in the system noting that evaporation exceeds rainfall. NCEP computes more precipitation than evaporation with moisture flux into the area providing the balance. This suggests that the ERA-40 data set is not suitable for computing water budget terms in this particular region. Moisture flux convergence is computed by using four daily readings (00, 06, 12 and 18z) up to 300 hPa. Finally, Principle Component Analysis (PCA) techniques are used to divide the domain into six areas and we discuss the temporal variation of rainfall for each area. The main contribution of rainfall in most of the areas is due to western disturbance weather systems moving from west to east. Also the area at the extreme southeast is getting rain though southwest monsoon in the month of July August. It is observed that rainfall decreases significantly after 1980 as a result of a dedcrease in moisture flux convergence.

Malik, K.; Taylor, P. A.; Szeto, K.

2009-05-01

333

Nonindigenous Aquatic Species in a United States Estuary: A Case Study of the Biological Invasions of the San Francisco Bay and Delta. Biological Study.  

Science.gov (United States)

The San Francisco Bay/Delta Estuary hosts more nonindigenous species than are known for any other estuary, with 212 established species, 15 species too recently aarrived to determine whether they have become established, and at least 125 cryptogenic speci...

A. N. Cohen J. T. Carlton

1995-01-01

334

Seasonal dynamics and conservative mixing of dissolved organic matter in the temperate eutrophic estuary Horsens Fjord  

DEFF Research Database (Denmark)

This study presents the results of a year-long study investigating the characteristics of dissolved organic matter (DOM) in the Danish estuary, Horsens Fjord. The estuary is shallow with a mean depth of 2.9 m and receives high loadings of inorganic nutrients from its catchment. The behaviour of different DOM parameters i.e. dissolved organic carbon (DOC), nitrogen (DON), and phosphorous (DOP), light absorption and eight fluorescence components, were analysed relative to conservative mixing. Many of the parameters did not behave conservatively. For DON, DOP and absorption, more than 65% of the freshwater concentration was removed initially at salinities below 12. At higher salinities two general patterns were identified. Concentrations of DON, DOP and four humic fluorescent fractions were not, or only weakly, related to salinity, showing that other processes than mixing were involved. Other parameters such as DOC and two terrestrial humic components behaved conservatively. The same was true for DON during winter. These results are consistent with the finding that autochthonous DOM was the dominant source of DOM in this estuary. The molar C:N and C:P ratios for DOM (DOC:DON and DOC:DOP) in freshwater were 11 and 758, respectively. The DOC:DON ratio increased in the estuary during the productive season to average values between 13 and 17, due to accumulation of DOC and removal of DON. The DOC:DOP ratio decreased within the estuary showing that in general DOM was enriched with phosphorous, however, during the spring, when phosphorous was limiting, the DOC:DOP ratio increased due to low DOP concentrations. We hypothesise that in estuaries with high loadings of inorganic nutrients relative to DOM, production and degradation of DOM within the estuary will dominate over allochthonous inputs and control both concentration and characteristics of DOM. A conceptual model for this hypothesis is presented. (C) 2011 Elsevier Ltd. All rights reserved.

Markager, Stiig; Stedmon, Colin

2011-01-01

335

Concerns in assessing radiological releases to a major estuary  

International Nuclear Information System (INIS)

Full text: In the State of Virginia, the James River flows into the Chesapeake Bay and from the mouth of the James River to the fall line the river is under the influence of tidal forces. There are several centers of commerce along the river including an international port of call at the mouth of the James. Associated with the centers of commerce are potential sources of radioactive materials for being released to the river. Two hundred miles inland, the Babcock and Wilcox nuclear fuels processing plants are situated along-side the James River, which has been known to flood its banks quickly in the mountainous regions of Virginia. Storage tanks have been swept downstream from this facility in a previous flood. Fortunately, the tanks were not destroyed. Another source of a possible release is the Suny Nuclear Power Station located on the James River about fifty miles from the Chesapeake Bay. In the cities of Norfolk and Newport News, shipyards are fueling and defueling the Navy's nuclear powered fleet. In addition, many of the Navy's ships are carrying nuclear weapons. These activities may also result in an inadvertent release. In assessing the radiological release from any one of the previously mentioned activities, it is obvious that dilution of the material released into the river is a major factor in dose assessment, as well as the fact that the water is brackish and not suitable as a source of potable water. However, dilution in this case may not be the simple solution. We also have to remember that this estuary is under tidal effects, which means that the materials may not be going out to sea to be further diluted as quickly as we would like to think. It may be possible that the material will be carried up river as far as the fall line and deposited, or deposited along the river's banks. From Virginia's experience with the pesticide, Kepone, materials may be deposited along the estuary and enter the food chain thereby necessitating the limitation of taking shellfish and commercial, recreational fishing. A major problem in assessing the environmental impact is determining what isotopes and in what forms will be taken up in species of commercial interest or those species that would otherwise contribute to man's exposure. Even though water to the lower James River is brackish, there may be uses for the water that have not been considered before, such as use by desalinization plants. Currently, the City of Virginia Beach has difficulty maintaining an adequate supply of water and there has been some discussion of building desalinization plants. If such a plant were in operation, the health physicist would have to consider the consequences of the material being concentrated and the problems associated with disposal of resins or contamination of the equipment. Most ships distill water while at sea and probably the still would not be operating while in port; however, the brackish water is used for fire fighting and many prove to be a source of contamination on the piers, unless an advisory was issued. At the mouth of the James River is located a major beach resort and in the event of a major release its business would suffer if the radiological conditions were not assessed and communicated effectively to the public promptly. I would like to conclude this discussion by stating that citizens in states surrounding the Chesapeake Bay have become very sensitive to the environment of the Bay and that they no longer tolerate rivers being used as sewers. As health physicists we also need to be sensitive to these issues and be mindful that estuaries are more complicated than a direct sewer drain to the ocean for wastes even though the discharges may be accidental. (author)

1989-09-01

336

Fishes and fisheries in tropical estuaries: The last 10 years  

Science.gov (United States)

Since 2002 there has been an increase in knowledge of many aspects of the biology and ecology of tropical estuarine fishes, as well as significant changes to many estuarine fisheries. Analyses of literature databases (2002-2012) show that: of the c. 600 relevant papers, 52% are primarily related to ecology, 11% to conservation, 11% to anthropogenic and pollution effects on fishes, 9% to fisheries, 7% to aquaculture, 4% to study techniques, and 1% each to fish larvae, effects of fishing, taxonomy, climate change, evolution and genetics. In terms of geographic spread 17% are from North America, 15% from south Asia, 14% from the Caribbean, 13% from Australasia, 12% from Africa and 9% each from South America and SE Asia. Research papers came from 50 countries of which the dominant were USA (15%), India (12%), Australia (11%) and Brazil (7%). Increasing numbers of studies in West Africa, SE and South Asia and South America have increased basic knowledge of the ecology of estuarine fish faunas. Increases in understanding relate to: roles of salinity, turbidity and habitat diversity; connectivity between habitats; water flow; ecological drivers of spatial variability; scale dependent variation; thermal tolerances; movement patterns; food webs; larval adaptations; and the viability of areas heavily impacted by human activities. New reviews both challenge and support different aspects of the estuarine dependence paradigm - still perhaps one of the main research issues - and the protective function of estuaries and mangroves for juvenile fishes has received attention in relation to e.g. predation risks and fisheries. There have also been significant advances in the use of guilds and biodiversity models. Fishing pressures have continued unabated in most tropical estuaries and are summarised and management issues discussed. Understanding of the relationships between fisheries production and mangroves has advanced and significant differences have emerged between Indo-West Pacific and Atlantic systems. The effects of fishing itself have also received attention and research is often related to conservation studies. The effects of anthropogenic activities are reviewed and important advances in mitigation are discussed. Restoration of estuarine habitats, such as mangroves, previously taking place mainly in countries such as Australia and USA, is now occurring in more countries. The design of reserves and the use of protected areas as management tools are gaining credence. Finally, the evidence for actual and potential effects of climate change is discussed.

Blaber, S. J. M.

2013-12-01

337

Remote Sensing Technologies for Estuary Research and Management (Invited)  

Science.gov (United States)

Estuarine ecosystems and their biogeochemical processes are extremely vulnerable to climate and environmental changes, and are threatened by sea level rise and upstream activities such as land use/land cover and hydrological changes. Despite the recognized threat to estuaries, most aspects of how change will affect estuaries are not well understood due to the poorly resolved understanding of the complex physical, chemical and biological processes and their interactions in estuarine systems. New and innovative remote sensing technologies such as high spectral resolution optical and thermal imagers and lidar, microwave radiometers and radar imagers enable measurements of key environmental parameters needed to establish baseline conditions and improve modeling efforts. Radar's sensitivity to water provides information about water height and velocity, channel geometry and wetland inundation. Water surface temperature and salinity and can be measured from microwave radiometry, and when combined with radar-derived information can provide information about estuarine hydrodynamics. Optical and thermal hyperspectral imagers provide information about sediment, plant and water chemistry including chlorophyll, dissolved organic matter and mineralogical composition. Lidar can measure bathymetry, microtopography and emergent plant structure. Plant functional types, wetland community distributions, turbidity, suspended and deposited sediments, dissolved organic matter, water column chlorophyll and phytoplankton functional types may be estimated from these measurements. Innovative deployment of advanced remote sensing technologies on airborne and submersible un-piloted platforms provides temporally and spatially continuous measurement in temporally dynamic and spatially complex tidal systems. Through biophysically-based retrievals, these technologies provide direct measurement of physical, biological and biogeochemical conditions that can be used as models to understand estuarine processes and forecast responses to change. We demonstrate that innovative remote sensing technologies, coupled with long term datasets from satellite earth observing missions and in situ sensor networks provide the spatially contiguous measurements needed to make 'supra-regional' (e.g. river to coast) assessments of ecological communities, habitat distribution, ecosystem function, sediment, nutrient and carbon source and transport. We show that this information can be used to improve environmental modeling with increased confidence and support informed environmental management.

Hestir, E. L.; Ustin, S.; Khanna, S.; Botha, E.; Santos, M. J.; Anstee, J.; Greenberg, J. A.

2013-12-01

338

Tide-driven fluid mud transport in the Ems estuary  

Science.gov (United States)

The Ems estuary, located at the border between The Netherlands and Germany, experienced a significant change of the hydrodynamic regime during the past decades, as a result of extensive river engineering. With the net sediment transport now being flood-oriented, suspended sediment concentrations have increased dramatically, inducing siltation and formation of fluid mud layers, which, in turn, influence hydraulic flow properties, such as turbulence and the apparent bed roughness. Here, the process-based understanding of fluid mud is essential to model and predict mud accumulation, not only regarding the anthropogenic impact, but also in view of the expected changes of environmental boundary conditions, i.e., sea level rise. In the recent past, substantial progress has been made concerning the understanding of estuarine circulation and influence of tidal asymmetry on upstream sediment accumulation. While associated sediment transport formulations have been implemented in the framework of numerical modelling systems, in-situ data of fluid mud are scarce. This study presents results on tide-driven fluid mud dynamics, measured during four tidal cycles aside the navigation channel in the Ems estuary. Lutoclines, i.e., strong vertical density gradients, were detected by sediment echo sounder (SES). Acoustic Doppler current profiles (ADCP) of different acoustic frequencies were used to determine hydrodynamic parameters and the vertical distribution of suspended sediment concentrations in the upper part of the water column. These continuous profiling measurements were complemented by CTD, ADV, and OBS casts. SES and ADCP profiles show cycles of fluid mud entrainment during accelerating flow, and subsequent settling, and the reformation of a lutocline during decelerating flow and slack water. Significant differences are revealed between flood and ebb phase. Highest entrainment rates are measured at the beginning of the flood phase, associated with strong current shear and rapid vertical mixing, inducing the highest instantaneous suspended sediment flux measured during the tidal cycle. During decelerating flood currents a lutocline is again established at a certain distance above the consolidated river bed. During slack water after the flood phase the concentration gradient increases and the thickness of the fluid mud layer below is constant, also during a significant part of the ebb phase. As water depth decreases during ebb, entrainment occurs only at the upper part of the fluid mud layer. The suspended sediment flux is low compared to the flood phase. These observations are further elaborated using turbulence parameters obtained from ADV and ADCP, explaining the difference between ebb and flood concerning the vertical location of the maximum concentration gradient. This study is funded through DFG-Research Center / Excellence Cluster "The Ocean in the Earth System". The Senckenberg Institute and the Federal Waterways Engineering and Research Institute are acknowledged for technical support.

Becker, Marius; Maushake, Christian; Winter, Christian

2014-05-01

339

Distribution of Epiphytic Diatoms in a Sub-Tropical Estuary  

Science.gov (United States)

Within estuaries, seagrasses may represent an order of magnitude greater surface area relative to sediments for the colonization and growth of diatoms. Fossil diatom distributions have proven useful in inferring paleoenvironmental conditions. The strength of these inferences is dependent upon defining the environmental relationships of contempory diatom compositions. The present investigation characterized the modern epiphytic diatom flora on the seagrass Thalassia testudinum at seven sites in the sub-tropical Florida Bay estuary and at one Atlantic Ocean site east of the upper Florida Keys. These sites were sampled six times between March 2000 and April 2001. Diatom species composition was related to water quality parameters using multivariate statistics. 338 diatom species were identified. The seven most abundant species from pooled samples were Cocconeis placentula, Brachysira aponina, Nitzschia liebetruthii, Hyalosynedra laevigata, Amphora cf. tenerrima, Mastogloia crucicula, and M. pusilla. These seven species collectively accounted for 51.7 percent of all valves counted and occurred in at least 85 percent of all samples. Analysis of similiarity and NMDS ordination of species relative abundances revealed four distinct diatom communities across the study region. The spatial variability of these communities was correlated with salinity and water-column nutrient availability. Summertime communities were significantly different from winter-spring communities, but these communities showed a gradual temporal progression with much overlap. The temporal variability was correlated with temperature. Indicator species analysis identified many species significantly influencing the four spatial groups. The Atlantic marine site was characterized by many different Mastogloia species and some epipsammic (sand-grain associated) diatoms (i.e., Cymatosira lorenziana, Dimerogramma dubium, and Neofragilaria nicobarica). Mastogloia pusilla, Rhopalodia pacifica, and Cocconeis woodii were strong indicators of the Gulf of Mexico marine site. Reimerothrix floridensis was particularly abundant in the western interior of Florida Bay (i.e., sites 2, 3, and 4) during summer months. The eastern interior of Florida Bay was characterized by high relative abundances of Brachysira aponina and Nitzschia liebetruthii. The optima and tolerance of these indicator species relative to individual water quality parameters were also determined.

Frankovich, T. A.; Gaiser, E. E.; Wachnicka, A.; Zieman, J. C.

2005-05-01

340

Bacterial Communities in Kuantan Estuary of Pahang Malaysia  

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Full Text Available Physicochemical parameters influence the vertical spatial distribution of microbial communities in any water bodies. Based on this perspective, a study on physicochemical parameters and bacterial community was carried out from five stations on January-June 2009 at the Kuantan estuary of Pahang, Malaysia. The temperature was ranged from 25.01-27.48°C, salinity fluctuation observed 0.03-25.84 ppt, Dissolved Oxygen (DO 6.10 to 10.73 mg L-1, specific conductivity ranged from 0.10 to 42.43 mS cm-1, Total Dissolved Solids (TDS ranged from 0.05 to 26.36 g L-1 and pH varied from 5.69 to 8.11 and chlorophyll a ranged 0.01 to 1.14 ?g L-1. The nitrite concentration was higher at St. 5 (0.19 mg L-1 followed by St. 4 (0.16 mg L-1 and it was lowest at St. 1 (0.13 mg L-1. Similarly, high phosphorus content (0.17 mg L-1 was found at St. 4 followed by St. 5 (0.16 mg L-1 while, it was lowest at St. 1 (0.08 mg L-1. Out of 19 isolated bacteria most dominant bacteria were Citrobacter freundii followed by Leuconostoc sp. and Staphylococcus xylosus. High bacterial colony (cfu mL-1 was observed at St. 4 (570 cfu mL-1 in water column followed by St. 5 (490 cfu mL-1. In contrary, it was lowest at St. 2 (213 cfu mL-1. Meanwhile, the highest bacterial colony in sediment was observed at St. 4 (390 cfu mL-1 followed by St. 5 (333 cfu mL-1. It was lowest observed at St. 2 (167 cfu mL-1. Nevertheless, a continuous monitoring of water quality is needed in this estuary especially at St. 4 and 5 which could be alarming in the long run due to deposition of nutrients from the outlets of fishing villages and industry sources.

K.C.A. Jalal

2010-01-01

 
 
 
 
341

Analytical Modeling of Groundwater Seepages to St. Lucie Estuary  

Science.gov (United States)

In this paper, six analytical models describing hydraulic interaction of stream-aquifer systems were applied to St Lucie Estuary (SLE) River Estuaries. These are analytical solutions for: (1) flow from a finite aquifer to a canal, (2) flow from an infinite aquifer to a canal, (3) the linearized Laplace system in a seepage surface, (4) wave propagation in the aquifer, (5) potential flow through stratified unconfined aquifers, and (6) flow through stratified confined aquifers. Input data for analytical solutions were obtained from monitoring wells and river stages at seepage-meter sites. Four transects in the study area are available: Club Med, Harbour Ridge, Lutz/MacMillan, and Pendarvis Cove located in the St. Lucie River. The analytical models were first calibrated with seepage meter measurements and then used to estimate of groundwater discharges into St. Lucie River. From this process, analytical relationships between the seepage rate and river stages and/or groundwater tables were established to predict the seasonal and monthly variation in groundwater seepage into SLE. It was found the seepage rate estimations by analytical models agreed well with measured data for some cases but only fair for some other cases. This is not unexpected because analytical solutions have some inherently simplified assumptions, which may be more valid for some cases than the others. From analytical calculations, it is possible to predict approximate seepage rates in the study domain when the assumptions underlying these analytical models are valid. The finite and infinite aquifer models and the linearized Laplace method are good for sites Pendarvis Cove and Lutz/MacMillian, but fair for the other two sites. The wave propagation model gave very good agreement in phase but only fairly agreement in magnitude for all four sites. The stratified unconfined and confined aquifer models gave similarly good agreements with measurements at three sites but poorly at the Club Med site. None of the analytical models presented here can fit the data at this site. To give better estimates at all sites numerical modeling that couple river hydraulics and groundwater flow involving less simplifications of and assumptions for the system may have to be adapted.

Lee, J.; Yeh, G.; Hu, G.

2008-12-01

342

Open water processes of the San Francisco Estuary: From physical forcing to biological responses  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reviews the current state of knowledge of the open waters of the San Francisco Estuary. This estuary is well known for the extent to which it has been altered through loss of wetlands, changes in hydrography, and the introduction of chemical and biological contaminants. It is also one of the most studied estuaries in the world, with much of the recent research effort aimed at supporting restoration efforts. In this review I emphasize the conceptual foundations for our current understanding of estuarine dynamics, particularly those aspects relevant to restoration. Several themes run throughout this paper. First is the critical role physical dynamics play in setting the stage for chemical and biological responses. Physical forcing by the tides and by variation in freshwater input combine to control the movement of the salinity field, and to establish stratification, mixing, and dilution patterns throughout the estuary. Many aspects of estuarine dynamics respond to interannual variation in freshwater flow; in particular, abundance of several estuarine-dependent species of fish and shrimp varies positively with flow, although the mechanisms behind these relationships are largely unknown. The second theme is the importance of time scales in determining the degree of interaction between dynamic processes. Physical effects tend to dominate when they operate at shorter time scales than biological processes; when the two time scales are similar, important interactions can arise between physical and biological variability. These interactions can be seen, for example, in the response of phytoplankton blooms, with characteristic time scales of days, to stratification events occurring during neap tides. The third theme is the key role of introduced species in all estuarine habitats; particularly noteworthy are introduced waterweeds and fishes in the tidal freshwater reaches of the estuary, and introduced clams there and in brackish water. The final theme is the rather heterogeneous set of results from monitoring and research in the estuary. For example, some topics have been subjects of intense activity both in research and monitoring (e.g., physical dynamics of the upper estuary, phytoplankton blooms, while others have received little attention (e.g., microzooplankton. In addition, both research and monitoring have emphasized some regions of the estuary (e.g., the Sacramento-San Joaquin Delta over others (e.g., San Pablo Bay. In addition, ecological modeling and synthesis has emphasized lower trophic levels over higher. Opportunities for restoration in the open waters of the estuary are somewhat limited by the lack of scientific basis for restoration, and the difficulty in detecting ecosystem responses in the context of high natural variability.

Wim Kimmerer

2004-02-01

343

River discharge, sediment transport and exchange in the Tana Estuary, Kenya  

Science.gov (United States)

This study focuses on sediment transport and exchange dynamics in the 27 km 2 Tana Estuary located at Kipini in the north Kenya coast. The estuary is drained by the Tana River, which contributes more than 50% of the total river discharges into the Kenyan sector of the Indian Ocean. The study involved measurement of river discharges, estuarine flood-ebb tidal discharges, total and particulate organic suspended sediment concentrations (TSSC, POSC) and fluxes, tidal water elevation, current velocities, temperature and salinity. The study was conducted between February 2001 and November 2003. The results of the study showed that the Tana River discharge ranged between 60 and 750 m 3 s -1. The maximum river discharges during the Southeast and Northeast monsoons were 750 and 350 m 3 s -1, respectively. The peak river discharges occurred in May and November. The total daily sediment load of the Tana River varied from 2796 tons day -1 during the dry season to 24,322 tons day -1 during the rainy season. The annual total sediment load is 6.8 × 10 6 tons yr -1, which is, however, smaller than that before the damming of the river in the Upper Tana Basin. Because of river discharge and occurrence of a wide mangrove wetland, the estuary is mainly ebb tide dominant. The peak ebb tide currents (0.87 m s -1) were 30% larger than the peak flood tide currents (0.65 m s -1). During spring tide, the estuary was partially well mixed. However, in neap tide, the estuary was stratified in the middle zone. The turbidity maximum zone with TSSC > 1.5 g l -1 was generated in spring tide by wave stirring of frontwater zone bed sediments and trapping of fine sediments at the toe of the salt wedge. The peak TSSC ranging from 1.5 to 5.0 g l -1 occurred at low tide due to river supply of sediment and resuspension of channel bed sediments by wind waves, particularly at the last stages of ebb tide and early stages of flood tide. Due to the influx of oceanic water into the estuary at flood tide TSSC decreased to <0.2 g l -1 at high tide in the frontwater zone and was larger in the backwater zones of the estuary. The estuary exports sediments at a rate ranging from 0.02 to 0.08 kg m -2 tidal cycle -1. The net export of sediments causes a net denudation of the estuary at a rate ranging from 0.08 to 0.04 mm tidal cycle -1.

Kitheka, J. U.; Obiero, M.; Nthenge, P.

2005-05-01

344

Assessing spatial and seasonal variations of dissolved organic matter by spectroscopic analysis in a stratified estuary: Yura River Estuary, Japan  

Science.gov (United States)

Dissolved organic matter (DOM) discharged from terrestrial areas may play an important role in global carbon dynamics as well as in estuarine and coastal primary and heterotrophic productivity. Dynamics of DOM in estuarine areas may be affected by various biological processes, such as production of autochthonous DOM and degradation of DOM. A spectroscopic method, which is a three-dimensional excitation emission matrix (EEM) fluorescence analysis has been applied to evaluate the qualitative variation of DOM. Parallel factor (PARAFAC) analysis is a newly introduced statistical modeling method to quantitatively decompose EEMs into individual fluorescent component. Combination of EEMs and PARAFAC analysis is a useful tool for assessing the dynamics of DOM. However our knowledge about the dynamics of individual PARAFAC component in esturine environment is still limited. The Yura River estuary is a typical microtidal estuary, which flows into the Sea of Japan. The estuary is characterized by the seasonal salt-wedge intrusion: In summer and autumn, seawater intrudes into the river approximately 20 km upstream from the river mouth due to the generally low water discharge during the season except for storm-induced sudden increase. In contrast, due to the high precipitation and snowmelt, water discharge is higher and the seawater rarely intrudes into the river in winter and early spring. The main objective of this study is to assess the spatial and seasonal variations of individual fluorophore in the stratified estuarine environment by using EEM-PARAFAC method. Six sampling stations were set between the mouth of the Yura River and the location about 16 km upstream. Twenty sampling stations were set at 5, 10, 20 and 30 m depths in the coastal area. Sampling and observations were carried out seasonally from July 2010 to July 2011. Measurement of vertical profiles of salinity, temperature and chlorophyll fluorescence was conducted by a CTD profiler at each station. We collected surface water samples from all 26 stations, and water samples from different depths at 6 stations located in the river and at 4 coastal stations along the extension of the river. Concentrations of DOC were determined with a total organic carbon analyzer. EEM was measured by using a fluorescent spectrometer. After EEM data were standardized by the Raman correction, several peaks are extracted by the PARAFAC analysis. Our study shows a great variability of DOM in terms of quantity and quality. DOC concentration tended to be high when the water discharge was high during the snowmelt season and in the summer when there was a storm-induced increase in water discharge. Two different terrestrial humic-like components (component 1 and 2) were identified by the PARAFAC analysis and the ratio between the fluorescent intensities of two components was greatly varied seasonally. Our study highlights the applicability of EEM-PARAFAC method to investigate DOM dynamics in esturine environments. This study was conducted as a part of the Kibunka Project, FSERC, at Kyoto University.

Fukuzaki, K.; Watanabe, K.; Fukushima, K.; Akiyama, S.; Fuji, T.; Funahashi, T.; Shirasawa, H.; Ueno, M.; Yamashita, Y.; Yoshioka, T.

2011-12-01

345

Tidal Exchange Variation On Pier Bridge Between Busan New-port And Nakdong Estuary, Korea  

Science.gov (United States)

This study analyzes the characteristics of tidal exchange between Nakdong estuary and Busan New-port. Therefore Compact-EM current meter was established on a connecting pier bridge and current velocity was analyzed for flow direction. Observation of tide and C.T.D(Conductivity Temperature Depth) was also analyzed to determine the characteristics of sea water and described the tidal exchange between Nakdong estuary and Busan New-port. For the purpose of indicating characteristics of tidal exchange numerical modelling was used. From the results of measuring the component of current velocity on the connecting pier bridge, it was determined that the dominant outflow direction in ebb tidal current was from the Nakdong estuary to Busan New-port. However, in flood tidal current the dominant direction was from the Busan New-port to the Nakdong estuary. Sum of volume transport of sea water calculations revealed (+)8.076 × 10{6} m{3} on the connecting pier bridge. It showed the volume transport of sea water to be more from Busan New-port to Nakdong estuary than in going the other direction.

Lee, Y.; Ryu, C.; Yoon, H.; Park, S.

2007-12-01

346

Facilitation of the Estuary/Ocean Subgroup for Research, Monitoring, and Evaluation, FY07 Annual Report  

Energy Technology Data Exchange (ETDEWEB)

This annual report is a deliverable for fiscal year 2007 (FY07) for Project 2002-077-00, Facilitation of the Estuary/Ocean Subgroup (EOS). The EOS is part of the research, monitoring, and evaluation (RME) effort the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) developed in response to responsibilities arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The goal of the EOS project is to facilitate activities of the estuary/ocean RME subgroup as it coordinates design and implementation of federal RME in the lower Columbia River and estuary. In FY07, EOS project accomplishments included 1) subgroup meetings; 2) participation in the estuary work group of the Pacific Northwest Aquatic Monitoring Partnership; 3) project management via the project tracking system, PISCES; 4) quarterly project status reports; and 5) a major revision to the Estuary RME Plan (new version September 2007) based on comments by EOS members and invited reviewers.

Johnson, Gary E.; Diefenderfer, Heida L.

2007-10-10

347

Facilitation of the Estuary/Ocean Subgroup for Research, Monitoring and Evaluation - FY07 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

This annual report is a deliverable for fiscal year 2007 (FY07) for Project 2002-077-00, Facilitation of the Estuary/Ocean Subgroup (EOS). The EOS is part of the research, monitoring, and evaluation (RME) effort of the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) developed in response to responsibilities arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The goal of the EOS project is to facilitate activities of the estuary/ocean RME subgroup as it coordinates design and implementation of federal RME in the lower Columbia River and estuary. In FY07, EOS project accomplishments included (1) subgroup meetings; (2) participation in the estuary work group of the Pacific Northwest Aquatic Monitoring Partnership; (3) project management via the project tracking system, PISCES; (4) quarterly project status reports; and (5) a major revision to the Estuary RME Plan (new version September 2007) based on comments by EOS members and invited reviewers.

Johnson, Gary E.; Diefenderfer, Heida L. [Pacific Northwest National Laboratory

2007-10-10

348

Abundance and Diversity of Mould Inhabiting Muara Layang Estuary Sediment, Bangka Belitung Islands  

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Full Text Available Estuary basin is a fertile area which has important role for sustaining many organisms from estuary and sea. Mould and other saprobic microorganisms have important role to decomposing organic material in estuary water. A study on diversity and abundance of mould inhabiting Muara Layang estuary sediment, Bangka Belitung Islands has not conduct before. The objective of this study is to investigate the abundance and diversity of mould inhabiting Muara Layang estuary sediment, Bangka Belitung Islands. The mould isolation was based on sample dilution method with Rose Bengal Cloramphenicol Agar mould isolation media. The abundance of mould was counted by measuring the average Colony Forming Unit (CFU/ml of all mould colonies which grown on isolation media by Total Plate Count (TPC method. The diversity of isolated mould was identified based on phenotypic characters by observing both of macroscopic and microscopic mould morphology. The result showed that the growth average of mould colonies is about (5-27.5 x102 CFU/mL. The result of mould identification showed that eight mould genera, Aspergillus (6 species, Chaetomium, Eupenicillium (3 species, Gliocladium, Paecilomyces, Penicillium (3 species, Scopulariopsis, Trichoderma (3 species, one group identified in class level (Coelomycetes, and three groups of unidentified sterile mould isolates were isolated.

MUHAMMAD ILYAS

2009-04-01

349

Modelling phytoplankton successions and nutrient transfers along the Scheldt estuary (Belgium, The Netherlands)  

Science.gov (United States)

The freshwater (RIVE) and the marine (MIRO) biogeochemical models were coupled to a 1D hydro-sedimentary model to describe contemporary phytoplankton successions and nutrient transfers in the macrotidal Scheldt estuary (BE/NL) affected by anthropogenic nutrient loads. The 1D-RIVE-MIRO model simulations are performed between Ghent and Vlissingen and the longitudinal estuarine profiles are validated with physico-chemical and phytoplankton observations available for the year 2006. Results show the occurrence of two distinct phytoplankton blooms in the upper and lower estuary, suggesting that neither the freshwater nor the marine phytoplankton is crossing the maximum turbidity zone (MTZ) at the saline transition. Sensitivity tests performed to understand how changing conditions (salinity, turbidity and nutrients) along the estuary are controlling this bimodal spatial phytoplankton distribution point salinity and light availability as key drivers while the grazing pressure and nutrient limitations are negligible. In the absence of species-specific salinity control or in low light limitation, freshwater phytoplankton is able to cross the MTZ and grow in the lower estuary where they compete with marine phytoplankton for nutrients. Additional tests with varying salinity-resistant (euryhaline) species in the freshwater assemblage conclude that the presence (or absence) of euryhalines determines the magnitude and the extension of freshwater and marine phytoplankton blooms in the estuary. Annual nutrient budgets estimated from 1D-RIVE-MIRO simulations show that biological activities have a negligible impact on nutrient export but modify the speciation of nutrients exported to the coastal zone towards inorganic forms.

Gypens, N.; Delhez, E.; Passy, P.; Lancelot, C.

2012-04-01

350

Dissolved oxygen dynamics in a eutrophic estuary, Upper Newport Bay, California  

Science.gov (United States)

Eutrophication often causes hypoxia in estuarine and coastal systems, but the mechanisms that control hypoxic events vary among estuaries and are often difficult to discern. We monitored surface and bottom dissolved oxygen (DO) in the Upper Newport Bay (UNB), a tidally mixed estuary in southern California subject to anthropogenic nutrient loading, eutrophication and hypoxia. Our goal was to identify the environmental factors regulating DO dynamics. Six hypoxic events occurred between June and November and were associated with a combination of low solar radiation, increased freshwater discharge following precipitation, and enhanced haline stratification during reduced tidal range periods. At the head of the estuary, high macroalgal biomass and pronounced haline stratification resulted in high DO in the surface layer and low DO in the bottom layer. Oxygen-rich and oxygen-poor waters were transported down-estuary by ebb tides, resulting in DO heterogeneity throughout the UNB. Cross-wavelet analysis illustrated the down-estuary propagation of high/low DO signal correlated with the phases of diurnal photosynthetic and semi-diurnal tidal cycles.

Nezlin, Nikolay P.; Kamer, Krista; Hyde, Jim; Stein, Eric D.

2009-03-01

351

Intra- and inter-seasonal variability of nutrients in a tropical monsoonal estuary (Zuari, India)  

Science.gov (United States)

A study was conducted to understand the intra- and inter-seasonal variability of dissolved oxygen and nutrients in a tropical monsoon estuary (Zuari in Goa, India). We adopted a dual sampling approach with (a) daily or alternate day sampling at a fixed location in the mid-estuarine zone and (b) longitudinal transect sampling from freshwater end to mouth during spring and neap tides of each month for about a year. Multivariate statistical analyses of oxygen and nutrients were carried out to evaluate the hypotheses: (i) biogeochemical processes chiefly regulate their variability and (ii) anthropogenic inputs lead to material accumulation in the estuary. Multivariate statistical analyses helped identify the controlling factors of the oxygen and nutrient variability. Our results significantly revealed (i) physical forcings (freshwater discharge and tidal circulation, these also facilitate sedimentary releases) are more important than biogeochemical processes in determining oxygen and nutrient variability in the water column and (ii) the monsoon driven regular annual flushing makes the system resilient to human interference as the Zuari estuary returns to normalcy by postmonsoon every year. Our study identified the significance of subsurface discharges in transporting mining effluents from the river basin. Results also suggest that extrapolation of controlling factors of biogeochemical variables at a fixed location to the entire estuary is untenable since the relative dominance of forcings vary in time and space in the estuary.

Subha Anand, S.; Sardessai, S.; Muthukumar, C.; Mangalaa, K. R.; Sundar, D.; Parab, S. G.; Dileep Kumar, M.

2014-07-01

352

Mangroves and Associated Flora of Vashista and Vainateyam Estuaries, A.P. India  

Directory of Open Access Journals (Sweden)

Full Text Available Mangroves are highly productive ecosystems occurs intertidal regions only. Mangroves and associated flora occurring in two major estuaries of Godavari river (India were studied using transect with 4x4 m2 quadrats and the quadrat samples were analyzed. Seasonal data were collected on environmental, hydrographical and chemical observations from three different stations of the two estuaries. Low values in Secchi depth, salinity and pH were reported during the monsoon season, while higher values were reported in pre-monsoon and post monsoon seasons. In the present study three mangrove species and nine associated species were reported. Transect studies in these two estuaries showed that mangrove and halophytes occurred up to 40 meters from water front region. In some places mangrove vegetation was in the form of long strips only. In Vainateyam estuary, the species with the highest density was Suaeda monoica whereas the species with lowest density was Avicennia officinalis. In Vashista estuary, maximum density was reported for Suaeda maritima and minimum density for Avicennia officinalis. The maximum height in these two stations varied from 5 to 8 meters only. Percentage frequencies of DBH (Density at Breast Height classes were estimated. In the present study only two diameter classes were reported. This is indicative of the small and bushy mangrove vegetation in the region studied. Human interference, urban settlements and aqua industry play a critical impact on the survival of these tropical ecosystems. If management and conservation programmes are not undertaken, these ecosystems may be depleted.

Pragada PRAYAGA MURTY

2010-12-01

353

Facilitation of the Estuary/Ocean Subgroup for Federal Research, Monitoring, and Evaluation, FY08 Annual Report  

Energy Technology Data Exchange (ETDEWEB)

The Estuary/Ocean Subgroup (EOS) is part of the research, monitoring, and evaluation (RME) effort that the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) developed in response to obligations arising from the Endangered Species Act as applied to operation of the Federal Columbia River Power System (FCRPS). The goal of the EOS project is to facilitate activities of the estuary/ocean RME subgroup as it coordinates design and implementation of federal RME in the lower Columbia River and estuary. In fiscal year 2008 (FY08), EOS project accomplishments included 1) subgroup meetings; 2) participation in the estuary work group of the Pacific Northwest Aquatic Monitoring Partnership; 3) project management via the project tracking system, Pisces; 4) quarterly project status reports; and 5) a major revision to the Estuary RME document and its subsequent regional release (new version January 2008). Many of the estuary RME recommendations in this document were incorporated into the Biological Opinion on hydrosystem operations (May 2008). In summary, the FY08 EOS project resulted in expanded, substantive coordination with other regional RME forums, a new version of the federal Estuary RME program document, and implementation coordination. This annual report is a FY08 deliverable for the project titled Facilitation of the Estuary/Ocean Subgroup.

Johnson, Gary E.; Diefenderfer, Heida L.

2008-09-29

354

Facilitation of the Estuary/Ocean Subgroup for Federal Research, Monitoring and Evaluation FY08 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

The Estuary/Ocean Subgroup (EOS) is part of the research, monitoring, and evaluation (RME) effort that the Action Agencies (Bonneville Power Administration (BPA), U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) developed in response to obligations arising from the Endangered Species Act as applied to operation of the Federal Columbia River Power System (FCRPS). The goal of the EOS project is to facilitate activities of the estuary/ocean RME subgroup as it coordinates design and implementation of federal RME in the lower Columbia River and estuary. In fiscal year 2008 (FY08), EOS project accomplishments included (1) subgroup meetings; (2) participation in the estuary work group of the Pacific Northwest Aquatic Monitoring Partnership; (3) project management via BPA's project tracking system, Pisces; (4) quarterly project status reports; and (5) a major revision to the Estuary RME document and its subsequent regional release (new version January 2008). Many of the estuary RME recommendations in this document were incorporated into the Biological Opinion on FCRPS operations (May 2008). In summary, the FY08 EOS project resulted in expanded, substantive coordination with other regional RME forums, a new version of the federal Estuary RME program document, and implementation coordination. This annual report is a FY08 deliverable for the project titled Facilitation of the Estuary/Ocean Subgroup.

Johnson, GE; Diefenderfer, HL [Pacific Northwest National Laboratory

2008-09-29

355

Response of the Plankton to a Fresh Water Pulse in a Fresh Water Deprived, Permanently Open South African Estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study assessed the influence of a freshwater pulse on selected physico-chemical and biological variables in a permanently open freshwater deprived southern African estuary. In the absence of the freshwater pulse a reverse gradient in salinity was evident with hypersaline (salinity > 40) conditions prevailing in the upper reaches of the estuary. Total chlorophyll-a

Pierre William Froneman; Paul Denzi Vorwerk

2013-01-01

356

Allochthonous Organic Matter Subsidize the High Secondary Production of the Invasive Bivalve Corbicula fluminea in Minho Estuary (N-Portugal)  

Science.gov (United States)

The Asian clam Corbicula fluminea is one of the most invasive species in freshwater ecosystems. In Minho estuary, this species colonize all the middle and upper part of the estuary, dominating the abundance, biomass and secondary production in River Minho tidal freshwater area (T...

357

MAPPING SEAGRASS AND GREEN MACROALGAE DISTRIBUTIONS IN AN OREGON ESTUARY USING COLOR INFRARED AERIAL PHOTOGRAPHY: 1997 & 1998  

Science.gov (United States)

Aerial photograph surveys of Oregon's Yaquina Bay estuary were conducted during the summers of 1997 and 1998. Advantage was taken of daylight low tide conditions when most of the intertidal mudflats in the estuary were exposed. The absence of overlying water permitted the use o...

358

MAPPING SEAGRASS AND GREEN MACROALGAE DISTRIBUTIONS IN AN OREGON ESTUARY USING COLOR-INFRARED AERIAL PHOTOGRAPHY: 1997 & 1998  

Science.gov (United States)

Aerial photograph surveys of Oregon's Yaquina Bay estuary were conducted during the summers of 1997 and 1998. Advantage was taken of daylight low tide conditions when most of the intertidal mudflats in the estuary were exposed. The absence of overlying water permitted the use o...

359

A Proposal for Impact Evaluation of the Diversion of the Acheloos River, on the Acheloos Estuary in Western Greece  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper the study of the hydrodynamic circulation at the Acheloos’ river estuary, in Western Greece, is proposed as a complementary approach for evaluating the environmental impacts, during river’s diversion to the Thessaly plain. Up to date, the environmental studies have been restricted only to the upper part of Acheloos river, including mainly hydrologic factors for addressing to the problem. Based on the assumption that the Acheloos diversion project is expected to modify runoff patterns at the lower part of the delta, reducing the ecological flow into the estuary, a hydrodynamic tool is required to quantify the impacts from this ambitious project. More specifically, the application of a hydrodynamic model is required in order to incorporate all thephysical factors that affect the hydrodynamic processes in the estuary, including effects of fresh water reduction scenarios to the overall hydrodynamic diet of the estuary, before and after the diversion project. This hydrodynamic approach will contribute towards a detailed understanding of the estuary’s ecosystem, quantifying the river’s diversion effects at the lower estuary’s environment.

NIKOLAOS TH. FOURNIOTIS

2012-04-01

360

Measuring hydrodynamics and sediment transport processes in the Dee estuary  

Directory of Open Access Journals (Sweden)

Full Text Available The capability of monitoring and predicting the marine environment leads to a more sustainable development of coastal and offshore regions. Therefore, the continuous measurement of environmental processes become an important source of information. The present paper shows data collected during 6 years, and in particular during 2008, in the Dee Estuary. The data aims to improve the observations of the mobile sediments in coastal areas and its forcing hydrodynamics and turbulence. Data involves the deployment of instrumented rigs measuring sediment in suspension, currents, waves, sea level, sediment size and bedforms as well as cruise work including grab sampling, CTD profiles and side-scan sonar. The data covers flood and ebb tides during spring and neap periods with moderate and mild wave events, thus, having a good coverage of the processes needed to improve knowledge of sediment transport and the parameterizations used in numerical modelling. The data, in raw and treated, is being banked at BODC (British Oceanographic Data Centre, http://www.bodc.ac.uk/ which is the formal British organization for looking after and distributing data concerning the marine environment.

R. Bolaños

2010-03-01

 
 
 
 
361

Measuring hydrodynamics and sediment transport processes in the Dee Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available The capability of monitoring and prediction in the marine environment provides information that may allow sustainable development of coastal and offshore regions. Therefore, the continuous measurement of environmental processes becomes an important source of information. The present paper shows data collected during 6 years, and in particular during 2008, in the Dee Estuary. The aim of the data collection is to improve the observations of the mobile sediments in coastal areas and its forcing hydrodynamics and turbulence. Data includes information from the deployment of instrumented rigs measuring sediment in suspension, currents, waves, sea level, sediment size and bedforms as well as cruise work including grab sampling, CTD profiles and side-scan sonar. The data cover flood and ebb tides during spring and neap periods with moderate and mild wave events, thus, having a good coverage of the processes needed to improve knowledge of sediment transport and the parameterizations used in numerical modelling. The data, in raw and treated, are being banked at BODC (British Oceanographic Data Centre, http://www.bodc.ac.uk/ which is the formal British organization for looking after and distributing data concerning the marine environment.

R. Bolaños

2010-06-01

362

Disposal of radioactive wastes into rivers, lakes and estuaries  

International Nuclear Information System (INIS)

The purpose of this report is to present, in the light of the information and experience accumulated to date, those principles and practices which, if applied to the disposal of radioactive wastes into inland surface and estuarial waters will ensure that man will not experience radiation exposures that are above the limits recommended by the International Commission for Radiation Protection (ICRP); and further, that radiation exposures are kept as far below those limits as is practicable. Disposal into sub-surface waters has not been specifically considered as this topic has been covered in another International Atomic Energy Agency publication. The report discusses the mechanisms and parameters which affect and control the fate of radionuclides introduced into fresh waters; it discusses the concepts of ''critical nuclide'', ''critical pathway'' and ''critical population group'' and demonstrates how the use of these concepts provides a sound, convenient and economical means for setting discharge limits and maintaining a continuing surveillance. It offers practical advice on the use of these concepts; gives some detailed information on uptake and dispersion mechanisms; and offers instruction on how to use this information and these concepts to estimate potential radiation doses and thus establish discharge limits.

1971-04-01

363

Radioactivity and United Kingdom estuaries: an overview identifying research priorities  

International Nuclear Information System (INIS)

The report consists of the results of an evaluation of research priorities for the environmental radioactivity of estuaries, (and near shore waters) of the United Kingdom. The format of this report is:(i) general conclusions for the future requirements for research in the field of environmental radioactivity; (ii) an overview of some specific recommendations for research; and (iii) an appendix in which a comprehensive evaluation of the research priorities for specific areas of research are given. On the basis that man is the prime target for concern and protection, special attention has been given to the environment in the vicinity of the British Nuclear Fuels (BNFL) reprocessing plant at Sellafield, Cumbria, which is the source of major releases of a variety of radionuclides into the natural environment. Subjects covered in the Appendix are: site factors; pathways to man; source term; hot particles; terrestrial inputs; surveys and monitoring; analysis; organics; field versus laboratory data; biology; bioaccumulation factors; some bioaccumulators of radioactivity; bioturbation; bacteria; genetics; natural change; sediment; resuspension; surfaces; Ksub(d) factors; pore liquids; diagenesis and the ageing processes; airborne transport of radionuclides; models; natural radioactivity; public opinion; recreation; the ICRP; the ALARA principle; decommissioning of nuclear power stations; identification of research requirements; environmental radioactivity - the national effort. (U.K.)

1985-01-01

364

Changes in Epipelic Diatom Diversity from the Savannah River Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available Littoral zones can be characterized with temporal exposure of algae to diurnal desiccation at low tides. Combinations of diverse freshwater, marine, and brackish diatoms dominate exposed mud samples. With enlargement of the delta of the Savannah River, Georgia and other anthropogenic influences, changes in the rich epipelic community will not be estimated accurately without baseline data. In the current study, mud samples were taken from the Savannah River estuary along with physicochemical characteristics every two months throughout 2011. Live algal communities were assessed in every sample and live to dead diatom proportions in the communities were calculated. Cleaned diatoms were analyzed following standard protocols. Community indices were compared between sampling events and with literature reports from similar habitats in the Southeastern USA diverse diatom community of 241 species was documented and 39 of those species should be described as new to science. Decrease in species richness and diversity was due to dominance of representatives of the genera Cymatosira and Minidiscus during the summer months.

Joseph N. Dominy Jr.

2013-02-01

365

Prospective ecological risk assessment of sediment resuspension in an estuary.  

Science.gov (United States)

This study assesses potential ecological risk of resuspended sediment in the water column during the construction of a viaduct in the estuary of the Ulla river (Galicia, NW Iberian Peninsula), a shellfish production area. Chemical analyses and toxicity bioassays with elutriates were performed with sediments from the area where the three pillars of the viaduct will be located (CT1, CT2 and CT3) and a reference sediment (A2). Acute toxicity of the elutriate was evaluated in five species of three trophic levels (Isochrysis galbana, Paracentrotus lividus, Mytilus galloprovincialis, Venerupis pullastra and Siriella armata). The sediments of the pillars showed moderate levels of contamination by trace elements (Cu, Cr). Clam and sea urchin embryo-larval toxicity tests showed slightly higher sensitivity than mussel embryo tests, and toxicity was not detected for phytoplankton and mysid bioassays. The predicted no-effect environmental concentration (PNEC) was calculated from the arithmetic mean of the lowest calculated EC(50)s for each sampling site. The predicted environmental concentration (PEC) was estimated from a simple dilution model and the PEC/PNEC ratio was calculated according to different scenarios of resuspension. Negligible ecological risk in the water column is expected during construction of the pillars. PMID:22763505

Rial, Diego; Beiras, Ricardo

2012-08-01

366

Electrochemical determination of dissolved uranium in Krka River estuary.  

Science.gov (United States)

The applicability of the previously developed method for electrochemical determination of dissolved uranium concentration has been tested on natural water samples taken from the Krka river estuary during various seasons and along different depth profiles. The method is based on the following treatment of the sample: destroying the uranyl-carbonato complexes by adjusting the pH to 3, enabling the formation of adsorbable uranyl-hydroxo complexes by adjusting the pH to 6.5-7.0 and measurement by cathodic stripping voltammetry technique. As the signal of the dissolved uranium reduction is sometimes masked by the signal of the matrix of the sample, a resolution enhancement including digestion and/or deconvolution has to be applied. The measured concentration of dissolved uranium varies in the range from 0.4 to 3.3 x 10(-8) mol l-1, corresponding to the data found in the literature. The depth profile of dissolved uranium concentration distributions shows conservative behaviour. The X-ray fluorescence spectroscopy (XRF) confirmed the applicability of the method, yet pointing out to its limitations caused by the matrix of the solution. PMID:11337837

Djogi?, R; Pizeta, I; Branica, M

2001-06-01

367

An overview of tritium behaviour in the Severn Estuary (UK)  

International Nuclear Information System (INIS)

Measurements of tritium (3H) activity in marine species in the Severn Estuary (UK) show concentrations significantly above those predicted by standard models. Concentration factors of 104 between seawater and marine species are observed; standard models assume a concentration factor of 1. In addition, the vast majority of activity is present in the form of organically bound tritium (OBT). The critical group dose from tritium - to consumers of local flounder - is estimated as ?36 ?Sv per annum. The measurements are related to the authorised release of wastes, via the sewer system, from the Amersham plc plant at Cardiff. The radiochemical plant manufactures a wide range of isotopically labelled compounds for use in life science research. The elevated levels of tritium observed in marine species have led to a programme of investigative work by specialist organisations. This paper describes the various definitions, measurements and significance of the term OBT. It also outlines the environmental observations and preliminary conclusions from the investigative programme to date. (author)

2001-12-01

368

Development of indicators of habitat condition for southeastern estuaries  

Energy Technology Data Exchange (ETDEWEB)

EMAP-Estuaries (Environmental Monitoring and Assessment Program) was extended into the southeast during pilot year studies. The efficacy of core indicators as well as some developmental indicators for classification of habitats as degraded or undegraded was evaluated at 24 stations from NC to Indian River Lagoon, FL. Results from continuous DO recordings indicate a pronounced diurnal/tidal component with periods of hypoxia at most sites, but with more extreme values and longer durations at degraded sites. Amphipod toxicity tests showed poor powers of discrimination, but Microtox assays showed some promise. Assays based on the effects of sediments on growth of seed clams (Mercenaria mercenaria) were developed that also yielded encouraging results. The benthic community data was used to develop an index based on community attributes (such as diversity, pollution sensitivity, dominance) that was very effective at discriminating degraded from undegraded sites. Protocols were also developed for in situ deployment of juvenile oysters (Crassostrea virginica) for evaluation of effects on growth, bioaccumulation, and disease. Oysters deployed at degraded sites had significantly lower growth rates, higher concentrations of metals, and higher incidences of disease.

Ringwood, A.H.; Holland, A.F.; Gilbert, G. [Marine Resources Research Inst., Charleston, SC (United States); Hyland, J. [NOAA, Charleston, SC (United States). Carolinian Province Office

1994-12-31

369

Anthropogenic sediment resuspension mechanisms in a shallow microtidal estuary  

Science.gov (United States)

The mechanisms that resuspend bottom sediments in Hillsborough Bay, a shallow, microtidal, subtropical estuary in West-central Florida, were determined by analysing hydrodynamic and suspended-solids concentration data collected during several instrument deployments made in 1990 and 1991. Large vessels in a dredged ship channel can generate forced solitary long waves that cause large water velocities and sediment resuspension at the study sites. An experiment was conducted with a trawler that resuspended bottom sediments, and some of the resuspended sediments remained in suspension for at least 8 h. A secondary impact of vessel-generated long waves and trawling is that sediments that are resuspended and newly deposited are more susceptible to resuspension by tidal currents than undisturbed bottom sediments. Natural sediment resuspension by wind waves and tidal current is less frequent or of smaller magnitude than anthropogenic sediment resuspension. The annual mass of sediment resuspended by vessel-generated long waves is estimated to be one order of magnitude greater than the annual mass of sediment resuspended by wind waves generated by winter storms.

Schoellhamer, D. H.

1996-01-01

370

Proceedings of the Columbia River Estuary Conference on Ecosystem Restoration.  

Energy Technology Data Exchange (ETDEWEB)

The 2008 Columbia River Estuary Conference was held at the Liberty Theater in Astoria, Oregon, on April 19-20. The conference theme was ecosystem restoration. The purpose of the conference was to exchange data and information among researchers, policy-makers, and the public, i.e., interrelate science with management. Conference organizers invited presentations synthesizing material on Restoration Planning and Implementation (Session 1), Research to Reduce Restoration Uncertainties (Session 2), Wetlands and Flood Management (Session 3), Action Effectiveness Monitoring (Session 4), and Management Perspectives (Session 5). A series of three plenary talks opened the conference. Facilitated speaker and audience discussion periods were held at the end of each session. Contributed posters conveyed additional data and information. These proceedings include abstracts and notes documenting questions from the audience and clarifying answers from the presenter for each talk. The proceedings also document key points from the discussion periods at the end of each session. The conference program is outlined in the agenda section. Speaker biographies are presented in Appendix A. Poster titles and authors are listed in Appendix B. A list of conference attendees is contained in Appendix C.

U.S. Bonneville Power Administration

2008-08-01

371

Environmental flow assessments in estuaries related to preference of phytoplankton  

Science.gov (United States)

An approach to assess estuarine environmental flow based on phytoplankton preference, including the complex relationships between hydrological modifications and ecosystem biomass, was developed in this study. We initially established a relationship between biomass requirements for primary and higher nutritional level organisms based on the ecosystem nutritional energy flow principles. Subsequently, diagnostic pigments were employed to represent phytoplankton community biomass, which indicated competition between two groups of phytoplankton in the biochemistry process. Considering empirical relationships between diagnostic pigments and critical environmental factors, biomass responses to river discharge were established by simulating distributions of critical environmental factors under action of river discharges and tide currents. Consequently, environmental flows were recommended for different fish biomass requirements. We used the Yellow River estuary as a case study; and May and June were identified as critical months for maintaining environmental flow. Temporal variation in natural river flow dynamics, which was used as a proxy for environmental flow, should be carefully examined in artificial hydrological regulation strategies, particularly during high-amplitude flood pulses, which might result in negative effects on phytoplankton groups, and subsequently higher aquatic species biomass.

Yang, Z. F.; Sun, T.; Zhao, R.

2014-05-01

372

Possible estuary-associated syndrome: symptoms, vision, and treatment.  

Science.gov (United States)

The human illness designated as possible estuarine-associated syndrome (PEAS) by the Centers for Disease Control and Prevention (CDC) has been associated with exposure to estuaries inhabited by toxin-forming dinoflagellates, including members of the fish-killing toxic Pfiesteria complex (TPC), Pfiesteria piscicida and Pfiesteria shumwayae. Humans may be exposed through direct contact with estuarine water or by inhalation of aerosolized or volatilized toxin(s). The five cases reported here demonstrate the full spectrum of symptoms experienced during acute and chronic stages of this suspected neurotoxin-mediated illness. The nonspecific symptoms most commonly reported are cough, secretory diarrhea, headache, fatigue, memory impairment, rash, difficulty in concentrating, light sensitivity, burning skin upon water contact, muscle ache, and abdominal pain. Less frequently encountered symptoms are upper airway obstruction, shortness of breath, confusion, red or tearing eyes, weakness, and vertigo. Some patients experience as few as four of these symptoms. The discovery that an indicator of visual pattern-detection ability, visual contrast sensitivity (VCS), is sharply reduced in affected individuals has provided an objective indicator that is useful in diagnosing and monitoring PEAS. VCS deficits are present in both acute and chronic PEAS, and VCS recovers during cholestyramine treatment coincident with symptom abatement. Although PEAS cannot yet be definitively associated with TPC exposure, resolution with cholestyramine treatment suggests a neurotoxin-mediated illness. PMID:11401768

Shoemaker, R C; Hudnell, H K

2001-05-01

373

Fundamental Concepts of Recharge in the Desert Southwest  

Science.gov (United States)

Recharge in arid basins does not occur in all years or at all locations. To address the temporal and spatial variability of recharge, one must (1) distinguish between recharge and net infiltration, (2) understand travel time in the unsaturated zone, and (3) comprehend the local- and basin-scale deterministic processes and surficial properties that control net infiltration. Net infiltration is the quantity of water that moves below the zone of surface evapotranspiration whereas recharge is the quantity or process of water entering the saturated zone. Under steady-state conditions, net infiltration becomes recharge unless diverted to an area of spring flow, generally by laterally extensive, low-permeability rock. The rate of net infiltration, thickness of unsaturated zone, and the effective porosity of the flow-pathway control travel time through the unsaturated zone. Net infiltration and recharge vary spatially owing to variations in surface microclimates, root zone and unconsolidated material thickness, faults and fractures, and thickness and hydrologic properties of geologic strata in the unsaturated zone. Although temporal fluctuations in net infiltration diminish with depth, resultant recharge is expected to vary on timescales of days to centuries making decadal-scale climate cycles significant to understanding recharge. Results of model simulations of recharge indicate that net infiltration occurs in less than 5 percent of the area of a typical southwest basin and only when the surface-water supply exceeds the storage capacity of the root zone and evapotranspiration over a fixed period of time. The critical components controlling net infiltration and recharge are precipitation, as rain or snow (and snow accumulation and melt); infiltration and water storage capacity of the overlying soil (within the zone of evapotranspiration); potential and actual evapotranspiration; and bedrock permeability. In the desert Southwest, potential evapotranspiration exceeds precipitation on a yearly basis. However, on shorter time scales and in certain areas of a basin, precipitation and (or) snowmelt exceed the infiltration capacity of the soil and becomes runoff or exceed the storage capacity of the soil and becomes runoff in shallow soils or percolates below the root zone in deeper soils. A method to simulate the spatial and temporal variability of net infiltration was developed using a deterministic water-balance model and extensive GIS coverages. The GIS coverages include a digital elevation model and maps of geology, soils, vegetation, precipitation, and air temperature. Other required surficial properties for the model, such as permeability, porosity, and water-retention functions, have been calculated from associated data sets. The deterministic model identifies the areas and climatic conditions that allow for excess water, quantifies the amount of water available either as runoff or in-place recharge, and allows inter-basin comparison of recharge mechanisms (i.e. mountain front, mountain block, ephemeral stream) and potential recharge for current, wetter, and drier climates. Travel time through the unsaturated zone can be estimated if unsaturated zone thickness and permeability data are available. The model, which uses a monthly time step, is being used to evaluate the role of decadal-scale climate cycles (El Niño/La Niña and the Pacific Decadal Oscillation) and recharge potential at a pixel scale (generally 30 - 90 meters) across the entire desert Southwest.

Flint, A. L.; Flint, L. E.; Blainey, J. B.; Hevesi, J. A.

2001-12-01

374

Ostracoda and foraminifera as short-term tracers of environmental changes in very polluted areas: the Odiel Estuary (SW Spain)  

International Nuclear Information System (INIS)

The analysis of 17 cores collected in the Odiel Estuary (SW Spain) permits delimiting the recent evolution of this zone during the past decades and the influence of natural and anthropogenic factors on the distribution of Ostracoda and Foraminifera. In the upper estuary, the coincidence of acid waters, prolonged subaerial exposure, and coarse sediments may explain the absence or the disappearance of these microorganisms during the industrial period (1966-1985) in the major part of this area. In the lower estuary, sedimentary evolution and industrial wastes are the main factors influencing both the distribution and trends of the populations of these two groups. Finally, the main changes observed in the marine estuary are due to the sedimentary effects of the construction of two banks and the dredging of the main estuarine channel. - In a polluted estuary, the meiofaunal assemblages experience different changes even in adjacent sedimentary environments, closely related to anthropogenic and natural causes

2004-05-01

375

Ostracoda and foraminifera as short-term tracers of environmental changes in very polluted areas: the Odiel Estuary (SW Spain)  

Energy Technology Data Exchange (ETDEWEB)

The analysis of 17 cores collected in the Odiel Estuary (SW Spain) permits delimiting the recent evolution of this zone during the past decades and the influence of natural and anthropogenic factors on the distribution of Ostracoda and Foraminifera. In the upper estuary, the coincidence of acid waters, prolonged subaerial exposure, and coarse sediments may explain the absence or the disappearance of these microorganisms during the industrial period (1966-1985) in the major part of this area. In the lower estuary, sedimentary evolution and industrial wastes are the main factors influencing both the distribution and trends of the populations of these two groups. Finally, the main changes observed in the marine estuary are due to the sedimentary effects of the construction of two banks and the dredging of the main estuarine channel. - In a polluted estuary, the meiofaunal assemblages experience different changes even in adjacent sedimentary environments, closely related to anthropogenic and natural causes.

Ruiz, F.; Gonzalez-Regalado, M.L.; Borrego, J.; Abad, M.; Pendon, J.G

2004-05-01

376

Turnover of Extracellular DNA in Eutrophic and Oligotrophic Freshwater Environments of Southwest Florida.  

Science.gov (United States)

Turnover of extracellular DNA was investigated in oligotrophic springs of the Crystal River and the eutrophic Medard Reservoir of southwest Florida. The Medard Reservoir possessed large populations of bacterioplankton and phytoplankton (6.8 x 10 sup 9 cel...

J. H. Paul W. H. Jeffrey A. W. David M. F. DeFlaun L. H. Cazares

1989-01-01

377

Predicting Streamflow Patterns in Ephemeral Channels in the Southwest to Estimate Groundwater Recharge.  

Science.gov (United States)

Groundwater levels rise following El Nino years. This suggests that floods may contribute more than baseflows to groundwater recharge in the Southwest. Simulation modeling aids in supporting this premise. Documentation of spatial and temporal patterns of ...

A. Stewart J. Constantz R. Niswonger

2010-01-01

378

Resource Assessment for Microalgal/Emergent Aquatic Biomass Systems in the Arid Southwest: Final Report  

Energy Technology Data Exchange (ETDEWEB)

This research project has been designed to facilitate the eventual selection of biomass production systems using aquatic species (microalgal and emergent aquatic plant species (MEAP) which effectively exploit the potentially available resources of the Southwest.

Vigon, B. W.; Arthur, M. F.; Taft, L. G.; Wagner, C. K.; Lipinsky, E. S.; Litchfield, J. H.; McCandlish, C. D.; Clark, R.

1982-12-23

379

Hepatitis B virus genotypes in southwest Iran: Molecular, serological and clinical outcomes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

AIM: To investigate the associations of hepatitis B virus (HBV) genotype with HBeAg and anti-HBe status, alanine aminotransferase (ALT) levels and HBV-DNA detection in different groups of HBV-infected patients in southwest Iran.

Mojiri, Anahita; Behzad-behbahani, Abbas; Saberifirozi, Mehdei; Ardabili, Maryam; Beheshti, Mahmood; Rahsaz, Marjan; Banihashemi, Mehrdad; Azarpira, Negar; Geramizadeh, Bita; Khadang, Baharak; Moaddeb, Afsaneh; Ghaedi, Mojgan; Heidari, Tahereh; Torab, Ardeshir; Salah, Alireza

2008-01-01

380

75 FR 9156 - Notice of Southwest Idaho Resource Advisory Committee Meeting  

Science.gov (United States)

...of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, and Sawtooth National Forests' Southwest Idaho Resource...February 19, 2010. Suzanne C. Rainfille, Forest Supervisor, Payette National Forest. [FR Doc. 2010-3983 Filed...

2010-03-01

 
 
 
 
381

75 FR 16070 - Notice of Southwest Idaho Resource Advisory Committee Meeting  

Science.gov (United States)

...of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, and Sawtooth National Forests' Southwest Idaho Resource...March 22, 2010. Suzanne C. Rainville, Forest Supervisor, Payette National Forest. [FR Doc. 2010-7006 Filed...

2010-03-31

382

75 FR 68321 - Notice of Southwest Idaho Resource Advisory Committee Meeting  

Science.gov (United States)

...of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, and Sawtooth National Forests' Southwest Idaho Resource...October 29, 2010. Suzanne C. Rainville, Forest Supervisor, Payette National Forest. [FR Doc. 2010-27997 Filed...

2010-11-05

383

76 FR 12691 - Notice of Southwest Idaho Resource Advisory Committee Meeting  

Science.gov (United States)

...of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, Salmon-Challis, and Sawtooth National Forests' Southwest...March 2, 2011. Suzanne C. Rainville, Forest Supervisor, Payette National Forest. [FR Doc. 2011-5155 Filed...

2011-03-08

384

76 FR 6117 - Notice of Southwest Idaho Resource Advisory Committee Meeting  

Science.gov (United States)

...of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, Salmon-Challis, and Sawtooth National Forests' Southwest...January 27, 2011. Suzanne C. Rainville, Forest Supervisor, Payette National Forest. [FR Doc. 2011-2431 Filed...

2011-02-03

385

75 FR 24879 - Notice of Southwest Idaho Resource Advisory Committee Meeting  

Science.gov (United States)

...of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, and Sawtooth National Forests' Southwest Idaho Resource...April 27, 2010. Suzanne C. Rainville, Forest Supervisor, Payette National Forest. [FR Doc. 2010-10379 Filed...

2010-05-06

386

Waterfowl migration and distribution in North West estuaries. V. 2. Figures  

Energy Technology Data Exchange (ETDEWEB)

Waterfowl populations may be affected by the proposed tidal barrage across the Mersey. A study was performed with three objectives: (1) to evaluate the patterns of usage of the intertidal flats of the Mersey estuary by waders and wildfowl and to establish which are the preferred areas; (2) to identify the places of origin and movement patterns of the populations of waders and wildfowl that visit the Mersey estuary; and (3) to evaluate evidence regarding the capacity of British estuaries to absorb waders and wildfowl populations which might be displaced by a Mersey Barrage. The text and tables of results of this study have already been presented in Volume 1. Volume 2 contains the figures describing the results (U.K).

Clark, N.A.; Kirby, J.S.; Langston, R.H.W.; Donald, P.; Mawdesley, T.; Evans, J.

1990-12-01

387

Variability in waterfowl distribution within hypertidal estuaries in relation to sediments  

Energy Technology Data Exchange (ETDEWEB)

The Severn and Mersey estuaries are two of Britain`s most important sites for their waterfowl populations. It is therefore critical to fully understand the likely impacts of tidal power barrages on these populations in order to predict the long-term post-barrage populations that the estuaries could support. Previous studies have enabled four years of monitoring to be carried out on both estuaries using identical methodology. These studies have shown that there is a considerable degree of consistency in the waterfowl populations in some areas, although apparently less so in other areas. Studies of sediment mobility have not been carried out in ways which enable direct comparison of changes in sediment with changes in bird populations. This latest study was planned to permit such a comparison and to provide five years of detailed counts on the Severn and four years on the Mersey on the low tide distribution of waterfowl populations. (author)

Clark, N.A.; Evans, J.; Rehfisch, M.M.; Shepherd, M.

1993-11-01

388

Variability in waterfowl distribution within hypertidal estuaries in relation to sediments  

International Nuclear Information System (INIS)

The Severn and Mersey estuaries are two of Britain's most important sites for their waterfowl populations. It is therefore critical to fully understand the likely impacts of tidal power barrages on these populations in order to predict the long-term post-barrage populations that the estuaries could support. Previous studies have enabled four years of monitoring to be carried out on both estuaries using identical methodology. These studies have shown that there is a considerable degree of consistency in the waterfowl populations in some areas, although apparently less so in other areas. Studies of sediment mobility have not been carried out in ways which enable direct comparison of changes in sediment with changes in bird populations. This latest study was planned to permit such a comparison and to provide five years of detailed counts on the Severn and four years on the Mersey on the low tide distribution of waterfowl populations. (author)

1993-01-01

389

Distribution and flux of /sup 226/Ra and /sup 228/Ra in the Amazon River estuary  

Energy Technology Data Exchange (ETDEWEB)

Measurements of /sup 226/Ra and /sup 228/Ra in the Amazon River estuary show that desorption from riverborne suspended particulate matter in the estuary increases the riverine flux of both isotopes to the ocean by a factor of approximately 5 over the flux attributable to radium dissolved in the river water alone. The total Amazon flux supplies approximately 0.20% of the /sup 226/Ra and approximately 2.6% of the /sup 228/Ra standing crops in the near-surface Atlantic (0-200 m). Diffusive flux from estuarine and shelf sediments and desorption from resuspended sediments in the region of the estuary approximately double the estuarine /sup 226/Ra concentration and quadruple the estuarine /sup 228/Ra concentration above that caused by the dissolved and desorbed river components alone.

Key, R.M.; Sarmiento, J.L.; Stallard, R.F.; Moore, W.S.

1985-07-20

390

Phosphorus Distribution in the Sediments of the Hooghly (Ganges) Estuary, India  

Science.gov (United States)

The dissolved reactive phosphorus concentration in the Hooghly Estuary is maintained at a near constant value of 40 ?g l -1. Sediments act as a major sink for the high dissolved phosphate input into the estuary from the Ganges River. The distribution of various forms of P and their association with other sediment components were determined in the Hooghly estuarine sediments. Total P concentration ranges from 250 to 500 ?g g -1 in the surface sediments of the estuary; organic and inorganic P average 35 and 400 ?g g -1 respectively; P bound to Ca is the dominant form of sediment inorganic P (70%) and occluded P constitutes 24%, whereas non-occluded P makes up 6% of inorganic P. Non-occluded and occluded P are strongly correlated with Fe, Al, Mn and the organic matter content in the surficial sediments. There are no significant changes in inorganic and organic P in the top 50-100 cm of the sediment cores.

Vaithiyanathan, P.; Jha, P. K.; Subramanian, V.

1993-12-01

391

Sediment transport due to extreme events: The Hudson River estuary after tropical storms Irene and Lee  

Science.gov (United States)

Storms Irene and Lee in 2011 produced intense precipitation and flooding in the U.S. Northeast, including the Hudson River watershed. Sediment input to the Hudson River was approximately 2.7 megaton, about 5 times the long-term annual average. Rather than the common assumption that sediment is predominantly trapped in the estuary, observations and model results indicate that approximately two thirds of the new sediment remained trapped in the tidal freshwater river more than 1 month after the storms and only about one fifth of the new sediment reached the saline estuary. High sediment concentrations were observed in the estuary, but the model results suggest that this was predominantly due to remobilization of bed sediment. Spatially localized deposits of new and remobilized sediment were consistent with longer term depositional records. The results indicate that tidal rivers can intercept (at least temporarily) delivery of terrigenous sediment to the marine environment during major flow events.

Ralston, David K.; Warner, John C.; Geyer, W. Rockwell; Wall, Gary R.

2013-10-01

392

Factors controlling the concentrations of soluble phosphorus in the Mississippi estuary  

Energy Technology Data Exchange (ETDEWEB)

Sediments from the Mississippi River estuary were suspended in solutions with a range of salinities and various initial concentrations of phosphate. After 42 days the suspensions had nearly uniform values for the ion activity product of calcium times biphosphate, (Ca/sup 2 +/)(HPO/sub 4//sup 2 -/) approx. = 10/sup -9/ M/sup 2/. Similar values were observed for this ion product in the Mississippi River and in the upper estuary, suggesting that the concentration of soluble phosphorus may be controlled by an equilibrium with sedimentary material. The data are consistent with a mechanism where soluble phosphorus is controlled by hydrolysis on the surface of hydroxyapatite particles. Phosphorus levels in the lower estuary are controlled primarily by dilution with low-nutrient waters from the Gulf of Mexico.

1985-07-01

393

Distribution, sources and ecological risk assessment of PAHs in surface sediments from Guan River Estuary, China.  

Science.gov (United States)

The contamination of surface sediments in Guan River Estuary, China, by polycyclic aromatic hydrocarbons (PAHs) has been fully investigated. Total concentrations of 21 PAHs ranged from 90 to 218 ng/g with an average of 132.7 ng/g, which is relatively low in comparison with other estuaries around the world. PAH concentrations appeared to be positively correlated with clay content and negatively correlated with sediment grain size. Source identification implied that the PAHs originated mainly from pyrolytic sources. However, source patterns may be continuously changed to a petrogenic origin due to the heavy ship traffic and continuous discharge of oily sewage in this area. The PAH levels were also compared with international Sediments Quality Guidelines and Sediments Quality Criteria, and the results indicated low negative effects for most individual PAHs. However, toxic effects related to FLO would occur occasionally in most locations in the estuary. PMID:24508044

He, Xinran; Pang, Yong; Song, Xiaojuan; Chen, Binlin; Feng, Zhihua; Ma, Yuqin

2014-03-15

394

Dominance of point source in heavy metal distributions in sediments of a major Sydney estuary (Australia)  

Energy Technology Data Exchange (ETDEWEB)

Size-normalized (<63 {mu}m) distributions of Cu, Zn, and Pb in the surficial sediments of one of Sydneys` four major estuaries - the Georges River/Botany Bay estuary - are not facies or depositionally controlled, but rather their distribution is dominated by source. Point source (waste dumps, sewage overflows, and discharge form a polluted river) are responsible for elevating sediment heavy-metal concentrations up to 50 times above background. Nonpoint sources contribute in raising baseline levels to four times background and comprise mainly stormwater and also marinas, moorings, and wharfs/jetties. Heavy metals disgorged from a point soruce (Cooks River) strongly impact the sediments in the lower estuary, which has implications for the construction of a new runway for Sydney airport. (orig.)

Birch, G. [Environmental Geology Group, Geology and Geophysics Dept., Univ. of Sydney (Australia); Evenden, D. [Environmental Geology Group, Geology and Geophysics Dept., Univ. of Sydney (Australia); Teutsch, M.E. [Environmental Geology Group, Geology and Geophysics Dept., Univ. of Sydney (Australia)

1996-12-01