WorldWideScience
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Changes in the distribution of copepods in the Gironde estuary: A warming and marinisation consequence?  

Science.gov (United States)

The Gironde is the largest estuary of South-West Europe and is one of the best monitored estuarine systems in the world. This macrotidal estuary is characterized by a low biodiversity in both oligo- and mesohaline zones. Its zooplankton community is constituted by only five major species, three calanoid copepods (including one invasive species) and two mysids. Retrospective analyses have already documented a warming associated to a phenomenon of marinisation. Here, we investigate the influence of both marinisation and warming on the spatial distribution and the abundance of copepods (i.e. Eurytemora affinis, Acartia bifilosa and neritic species) in the Gironde estuary. We modelled the environmental envelope of the copepods as a function of salinity and temperature to demonstrate that the alteration of their longitudinal distribution in the estuary between 1975 and 2003 was the result of both changing temperature and salinity. Although the upstream movement of neritic species was mostly related to salinity, we show that the augmentation of both temperature and salinity was at the origin of the upstream progression of both A. bifilosa and E. affinis. These results suggest that the distribution of copepods can be affected by both anthropogenic forcing and climatic change, which modulate the physic-chemistry of the Gironde estuary.

Chaalali, Aurélie; Chevillot, Xavier; Beaugrand, Grégory; David, Valérie; Luczak, Christophe; Boët, Philippe; Sottolichio, Aldo; Sautour, Benoît

2013-12-01

2

Silver behaviour along the salinity gradient of the Gironde Estuary.  

Science.gov (United States)

Dissolved and particulate Ag concentrations (Ag(D) and Ag(P), respectively) were measured in surface water and suspended particulate matter (SPM) along the salinity gradient of the Gironde Estuary, South West France, during three cruises (2008-2009) covering contrasting hydrological conditions, i.e. two cruises during intermediate and one during high freshwater discharge (~740 and ~2,300 m(3)/s). Silver distribution reflected non-conservative behaviour with 60-70 % of Ag(P) in freshwater particles being desorbed by chlorocomplexation. The amount of Ag(P) desorbed was similar to the so-called reactive, potentially bioavailable Ag(P) fraction (60 ± 4 %) extracted from river SPM by 1 M HCl. Both Ag(P) (0.22 ± 0.05 mg/kg) and Ag(P)/Th(P) (0.025-0.028) in the residual fraction of fluvial and estuarine SPM were similar to those in SPM from the estuary mouth and in coastal sediments from the shelf off the Gironde Estuary, indicating that chlorocomplexation desorbs the reactive Ag(P). The data show that desorption of reactive Ag(P) mainly occurs inside the estuary during low and intermediate discharge, whereas expulsion of partially Ag(P)-depleted SPM (Ag(P)/Th(P) ~0.040) during the flood implies ongoing desorption in the coastal ocean, e.g. in the nearby oyster production areas (Marennes-Oléron Bay). The highest Ag(D) levels (6-8 ng/L) occurred in the mid-salinity range (15-20) of the Gironde Estuary and were decoupled from freshwater discharge. In the maximum turbidity zone, Ag(D) were at minimum, showing that high SPM concentrations (a) induce Ag(D) adsorption in estuarine freshwater and (b) counterbalance Ag(P) desorption in the low salinity range (1-3). Accordingly, Ag behaviour in turbid estuaries appears to be controlled by the balance between salinity and SPM levels. The first estimates of daily Ag(D) net fluxes for the Gironde Estuary (Boyle's method) showed relatively stable theoretical Ag(D) at zero salinity (Ag (D) (0) = 25-30 ng/L) for the contrasting hydrological situations. Accordingly, Ag(D) net fluxes were very similar for the situations with intermediate discharge (1.7 and 1.6 g/day) and clearly higher during the flood (5.0 g/day) despite incomplete desorption. Applying Ag (D) (0) to the annual freshwater inputs provided an annual net Ag(D) flux (0.64-0.89 t/year in 2008 and 0.56-0.77 t/year in 2009) that was 12-50 times greater than the Ag(D) gross flux. This estimate was consistent with net Ag(D) flux estimates obtained from gross Ag(P) flux considering 60 % desorption in the estuarine salinity gradient. PMID:22782792

Lanceleur, Laurent; Schäfer, Jörg; Blanc, Gérard; Coynel, Alexandra; Bossy, Cécile; Baudrimont, Magalie; Glé, Corine; Larrose, Aurélie; Renault, Sophie; Strady, Emilie

2013-03-01

3

Origin and composition of particulate organic matter in a macrotidal turbid estuary: The Gironde Estuary, France  

Science.gov (United States)

At the interface between continent and ocean, estuaries receive particles, and especially particulate organic matter (POM) originating from these two reservoirs, but also produce POM, through autochthonous primary production. The origin and composition of surface POM in the Gironde Estuary (SW France) and the environmental forcing of its variability was investigated using the data set produced by the French Coastal Monitoring Network SOMLIT (Service d'Observation en Milieu LITtoral; monthly like sampling during years 2007-2009). This estuary is considered as a model of macrotidal turbid estuaries. Using elemental and isotopic composition of the POM, we estimated that, at the inner estuary space scale and inter-annual time scale, surface particulate organic carbon (POC) was composed of terrestrial POM originated from the turbidity maximum (96.4%; refractory POC) and flood events (1.6%; labile and refractory POC), and of riverine (0.1%), estuarine (0.8%) and marine (1.1%) phytoplankton, i.e. that POC was 98% and 2% of terrestrial and phytoplankton origin, respectively. However, there was a clear spatial gradient: the phytoplankton contribution increases from ca. 1% in the upper and middle estuary to 8.5% in the lower estuary, where light condition is more favourable to plankton growth. The low contribution of phytoplankton to the POC is a characteristic of the Gironde estuary and contrast with other large temperate estuaries. Statistical analysis indicates that salinity, river flow and SPM concentration, and thus associated hydro-dynamic and sedimentary processes, were the only environmental forcings to the composition of surface POC in this system, at intra- and inter-annual time scale. In contrast, temperature and nutrient concentrations, and thus associated processes, do not force this composition of POC. By combining POC fluxes entering the inner estuary (literature data), POC loss as dissolved organic carbon and CO2 and as sediment trapping within the inner estuary (literature data), and our estimate of the composition of POC flux at the mouth of the estuary (96% and 4% of terrestrial and phytoplankton origin), a first-order net export of POC originating from the Gironde to the continental shelf was estimated: it amounts 48,150 tC yr-1, and is composed of 46,200 tC yr-1 of terrestrial material and of 1950 tC yr-1 of estuarine phytoplankton. POC exported by the Gironde Estuary is thus poorly bioavailable for shelf pelagic and benthic food webs.

Savoye, Nicolas; David, Valérie; Morisseau, François; Etcheber, Henri; Abril, Gwenaël; Billy, Isabelle; Charlier, Karine; Oggian, Georges; Derriennic, Hervé; Sautour, Benoît

2012-08-01

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Spatial distribution and dynamics of microphytobenthos biomass in the Gironde estuary (France)  

OpenAIRE

The spatial variation of microphytobenthos was investigated with reference to both the estuarine gradient and the intertidal levels of the Gironde estuary, France. Four transects, each with three stations, were surveyed in two different seasons (April and October) during two consecutive years. In addition, the seasonality of microphytobenthic pigment concentration and its relationship to environmental factors were examined by means of weekly sampling at an intertidal mudflat located in the ol...

Santos, Pjp; Castel, J.; Souzasantos, Lp

1997-01-01

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Mechanisms of suspension and dispersion of the thin sediments in the Gironde estuary  

International Nuclear Information System (INIS)

The Gironde estuary, as the great majority of estuaries, is characterized by the existence of a zone of turbidity maximum. This study, based on a radioisotope tracer experience and hydrological in situ measurements, has permitted the study of the transportation and sedimentation processes of the suspended sediments. Among the conclusions, it was found that: - the turbidity maximum has not a constant volume during a semi-diurnal tidal cycle, but pulsates with the increase and decrease of tidal currents; - the increase in concentration of suspended sediments is directly proportional to the near bottom velocity, and a function of the degree of compaction of the bottom sediment. A general model for the circulation and dispersion of the suspended sediments is presented, which illustrates the large scale lateral transport of suspended sediments in the lower estuary

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Dynamics of coarse particulate matter in the turbidity maximum zone of the Gironde Estuary  

Science.gov (United States)

There is a lack of studies devoted to coarse particulate matter (CPM) in estuaries, although this fraction can disturb activities that filter large volumes of water, such as industrial or fishery activities. In the macrotidal and highly-turbid Gironde Estuary, a monthly sampling of CPM was performed in 2011 and 2013 at two stations in the Turbidity Maximum Zone (TMZ) to understand its seasonal, tidal and hydrological dynamics. Regardless of the season and station, low quantities of CPM (few g m-3) were observed in comparison with suspended particulate matter (several 103 g m-3). The highest concentrations were consistently recorded in bottom waters and at the upstream station. Whereas there is no clear link between the CPM present in the column water and spring or neap tides, an increase in the CPM size has been identified at the two stations after a flood event, fact potentially critical regarding filtering functioning of estuarine activities.

Fuentes-Cid, Ana; Etcheber, Henri; Schmidt, Sabine; Abril, Gwenaël; De-Oliveira, Eric; Lepage, Mario; Sottolichio, Aldo

2014-01-01

7

Long-term changes of the zooplankton variability in a turbid environment: The Gironde estuary (France)  

Science.gov (United States)

Zooplanktonic variability at the maximum turbidity zone was investigated for the Gironde estuary for 18 years. This ecosystem is characterized by a high concentration of suspended matter and five dominant zooplankton species: the copepods Eurytemora affinis, Acartia bifilosa, A. tonsa and the mysids Neomysis integer and Mesopodopsis slabberi. Four major sources of variation in density were analyzed: (a) spatial variation (vertical and longitudinal variability) and (b) temporal variation (seasonal and annual variability) in the oligo-mesohaline area of the estuary. Temporal variability was related to environmental parameters: temperature, salinity, suspended matter concentration and active chlorophyll in the water column. Seasonal and annual variability were identified as significant sources of variation which explains the fluctuations of all zooplankton densities. No long-term trend was observed for zooplankton densities except for A. tonsa, a species recently introduced into the oligo-mesohaline area of the estuary. Temperature and salinity were important factors explaining the interannual variability of E. affinis as well as of both mysids. Suspended matter concentration controlled the long-term trends of E. affinis and A. tonsa. Annual variability of A. bifilosa and both mysid species was also explained by the proportion of active chlorophyll. Seasonal variability, calculated as the between-month variation, represented the dominant type of variability for all species. Seasonal variations of copepods were essentially explained by salinity. N. integer was significantly correlated with temperature and copepod densities, whereas M. slabberi was correlated with temperature and salinity. Zooplankton also showed significant spatial variation. Mysids demonstrated significant differences between surface and bottom densities whereas vertical variability of copepod densities did not represent a significant source of variation. In terms of longitudinal variability, density of E. affinis was similar along the salinity gradient, whereas Acartia spp. and mysids occurred at significantly greater densities at the downstream station. The high turbidity, which characterizes the Gironde estuary, seems to be a determining factor that acts directly on copepod temporal variability and indirectly on mysid long-term fluctuations by limiting the nutritional quality of the environment.

David, Valérie; Sautour, Benoît; Chardy, Pierre; Leconte, Michel

2005-08-01

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Numerical modelling of sand-mud mixtures settling and transport processes : application to morphodynamic of the Gironde estuary (France)  

OpenAIRE

This study attempts to model sediment transport rates and the resulting bed evolution in a complex estuarine environment: the Gironde estuary, characterized by a high hetereogeneity in the sediment bed composition, with the presence of both cohesive and non-cohesive sediments and sand/mud mixtures. Our main objective is to extend an existing 2D morphodynamic model developped by Huybrechts et al (2012b) for non-cohesive sediments, to account for the presence of mud and to draw some preliminary...

Do, Lan Anh

2012-01-01

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A 9-year continuous monitoring of salinity in the Gironde estuary (S-W France) reveals marked inter-annual variability in marine intrusion  

Science.gov (United States)

Estuaries form a transition zone in which rivers and oceans meet, including both fresh and salt waters. Thus conditions in estuary are more variable than those in either rivers or marine environments. In particular salinity presents a large temporal and lateral variations, depending of the degree of water mixing. The limit of salinity intrusion along an estuary is determined by the balance between the landward transport of salt by tidal processes and its seaward return by freshwater discharges. The major factor that affects the limit of saline intrusion along an estuary is freshwater inflow. In a context of global change, salinity intrusion in estuaries is expected to increase due to the cumulative effect of decrease in freshwater flows (changes in rain rate, decrease of riverine discharge due to upstream land use) and to sea level rives. At present, it is still difficult to establish changes in marine intrusion in estuaries due to the limited available data set. With its 625 km2, the Gironde estuary (S-W France) is one of the largest European estuaries. Since 2004, a real-time continuous system (MAGEST network) records four selected parameters (salinity, turbidity, dissolved oxygen) to establish a reference database of water-quality of this fluvio-estuarine system to address current and future water-quality issues. Here we present in details the 9-year time series of salinity in the Gironde estuary, recorded at four stations representative of the central and up estuary. Not surprisingly there are large difference among the four instrumented stations depending on their localization. But the time-series had allowed to highlight marked inter-annual variability in relation with the local hydrology. This example clearly illustrates the interest of long-term time series to detect potential changes in salinity, related to global changes, from inter-annual variability.

Schmidt, Sabine; Sottolichio, Aldo

2013-04-01

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Numerical modeling techniques for the study of horizontal ciruclation in estuaries - Apllication to the Gironde  

OpenAIRE

Recent advances in fast computers have helped in developing numerical models for the study of estuarine and coastal dynamics. So far, different workers have made definitions of an estuary mainly based on salinity considerations. For example, following PRITCHARD (1965), an estuary may be defined as "a semi enclosed body of water having a free connection with the open sea within which sea water is mesurably diluted with fresh water derived from land drainage". In the case of european estuaries,...

Unnikrishnan, A. S.

1985-01-01

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Successful colonization of the calanoid copepod Acartia tonsa in the oligo-mesohaline area of the Gironde estuary (SW France) Natural or anthropogenic forcing?  

Science.gov (United States)

The copepod Acartia tonsa appeared in Europe in the first half of the 20th century and colonized progressively European seas and estuaries, possibly transferred from North Atlantic Coast of America. It had been reported in the polyhaline area of the Gironde estuary for a long time but was first recorded in the oligo-mesohaline area in 1983. Its abundance has been increasing significantly. High abundances of A. tonsa were reported since 1999, supplanting the abundances of its autochthonous congeneric species, Acartia bifilosa. This colonization was characterized by analyzing the mean seasonal variability: (1) for three 5-year periods corresponding to three different steps of A. tonsa appearance (1978-1982, A. tonsa was absent; 1988-1992, low abundances of the species; and 1999-2003, high abundances of A. tonsa) in the oligo-mesohaline area and (2) for three stations distributed along the salinity gradient during the recent period. The aim of this work was to define if this colonization was due to natural or anthropogenic forcing and to evaluate its possible impact on autochthonous zooplanktonic community. Both natural and anthropogenic forcings seem to explain the colonization of Acartia tonsa in the oligo-mesohaline area of the Gironde estuary. First records (1983-1988) could be due to marine water inputs caused by high values of the North Atlantic Oscillation index. The global warming which caused the increase of the summer warm period, the marinisation of the system and the local decrease of the turbidity should have been the key factors favoring the establishment of the species. Anthropogenic forcings as the establishment of the nuclear power plant which locally causes warmer conditions are also important factors explaining the differences of seasonal cycle observed between oligo-mesohaline area and other stations: the seasonal pattern of A. tonsa in the oligo-mesohaline area was indeed characterized by an autumnal peak of abundances which has been observed in other stations and in many North European estuaries, and by a second spring peak that had only been observed in Southern estuaries. The introduction of Acartia tonsa in the Gironde estuary significantly changed the seasonal pattern of autochthonous copepods, by limiting their seasonal abundances without affecting their long-term population stability. Finally, the successful colonization of A. tonsa had led to the spread of the seasonal zooplanktonic production which could have had an impact on fish and shrimp productions.

David, Valérie; Sautour, Benoît; Chardy, Pierre

2007-02-01

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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

13

Reconnaissance par stratigraphie sismique haute résolution de la paléovallée de la Gironde sur le plateau continental  

Science.gov (United States)

Before new high resolution geophysical results were acquired during the PLABAS seaward cruise of the estuary mouth of the Gironde River (southwest of France), the offshore extension of the palaeovalley was unknown. One seismic section shows the offshore palaeovalley incision. From this processed seismic line, it is possible to interpret the infilling of the valley in terms of stratigraphic sequences. The seismic sequences are limited by unconformities already described in the inner estuary by Allen and Posamentier (1993, 1994). They form a 5 th -order stratigraphic unit (20 000 years).

Lericolais, Gilles; Fémes, Hugues; Tastet, Jean-Pierre; Berné, Serge

1998-05-01

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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

15

Seasonal succession of estuarine fish, shrimps, macrozoobenthos and plankton: Physico-chemical and trophic influence. The Gironde estuary as a case study  

Science.gov (United States)

Characterization of the structure and seasonal variability of biotic communities is essential for a better understanding of estuarine ecosystem functioning and in order to manage these highly fluctuating and naturally stressed systems. Numerous studies have investigated the role of environmental factors in controlling temporal variations in biotic communities. However, most have concluded that the explanatory power of physico-chemical variables was significant but not sufficient to explain ecological dynamics. The present study aimed to propose the importance of trophic interactions as an additional structuring factor of species seasonal variability by examining simultaneous dynamics of all estuarine biotic communities, using the oligo-mesohaline area of the Gironde estuary (SW France) as a case study. Data on the main biological groups (fish, shrimps, macrozoobenthos and plankton) sampled during a five-year period (2004-2008) at monthly intervals using a well standardized protocol, as well as data on environmental variables, were compiled here for the first time. According to species composition, the Gironde estuary is used as a nursery, feeding, resident and migratory habitat. For almost all species, strong seasonal fluctuations occurred with a succession of species, indicating an optimization of the use of the available resources over a typical year by estuarine biological communities. Multivariate analyses discriminated four seasonal groups of species with two distinctive ecological seasons. A clear shift in July indicated a biomass transfer from a "planktonic phase" to a "bentho-demersal phase", corresponding to spring and summer-autumn periods, respectively. With regard to the temporal fluctuations of dominant species of all biological groups, this study highlighted the possible influence of trophic relationships, predation in particular, on seasonal variations in species abundance, in addition to the physico-chemical influence. This study enabled us to collate important seasonal data and to discuss their integration into seasonal models of estuarine functioning and/or specific prey-predator models. In a global change context, prey abundance variations could generate changes in the temporal dynamics of their predators (and conversely), and potentially in the functioning of the whole estuarine system.

Selleslagh, Jonathan; Lobry, Jérémy; N'Zigou, Aimé Roger; Bachelet, Guy; Blanchet, Hugues; Chaalali, Aurélie; Sautour, Benoît; Boët, Philippe

2012-10-01

16

Geochemical survey and metal bioaccumulation of three bivalve species (Crassostrea gigas, Cerastoderma edule and Ruditapes philippinarum) in the Nord Medoc salt marshes (Gironde estuary, France)  

International Nuclear Information System (INIS)

A 15-month experiment combining a geochemical survey of Cd, Cu, Zn and Hg with a bioaccumulation study for three filter-feeding bivalve species (oysters, Crassostrea gigas; cockles, Cerastoderma edule; and clams, Ruditapes philippinarum) was conducted in a breeding basin of the Nord Medoc salt marshes connected to the Gironde estuary, which is affected by historic polymetallic pollution. Regular manual surface measurements of temperature, salinity, pH and dissolved O2 concentration and hourly multiprobe in situ measurements throughout several periods for 6-8 weeks were performed. The geochemical behavior of metals in water, suspended particulate matter and sediment and their ecotoxicological impact on the three bivalve species were evaluated by in situ exposure of juvenile oysters (water column) and adult cockles and clams (sediment surface). The physico-chemical parameters reflected seasonal variations and basin management. A distinct daily periodicity (except salinity) indicated intense photosynthesis and respiration. In summer, low dissolved O2 saturations (?40-50%) occurred in the early morning at 30 cm above the sediment, whereas in depressions, the water column near the sediment surface was suboxic. Cadmium, Zn and Cu concentrations in suspended particulate matter exceeded typical estuarine values and were much higher than the homogeneously distributed concentrations in different depth ranges of the basin sediment. Particles collected in basin sediment. Particles collected in sediment traps showed intermediate metal concentrations close to sediment values. These results suggest trace metal recycling due to reductive dissolution under suboxic conditions at the sediment surface resulting in trace metal release to the water column and adsorption onto suspended particles. Dissolved Cd, Zn and Hg concentrations (e.g. 13-136 ng l-1; 0.3-25.1 ?g l-1 and 0.5-2.0 ng l-1, respectively) in the basin corresponded to the concentration range typically observed in the Gironde estuary, except for some maximum values attributed to metal recycling. In contrast, dissolved Cu concentrations (1.08-6.08 ?g l-1) were mostly higher than typical estuarine values, probably due to recycled Cu complexation by dissolved organic matter. Growth, bioaccumulation rates and kinetics in the whole soft body of the bivalves were analyzed every 40 days. Although Cd bioaccumulation of oysters was lower in the basin than in the estuary during the same period (27,000 ng g-1, dry weight and 40,000 ng g-1, respectively) these values are largely above the new human consumption safety level (5000 ng g-1, dw; European Community, 2002). For cockles and clams, Cd bioaccumulation was lower, reaching 1400 ng g-1 and 950 ng g-1, respectively. Similar results were obtained for Zn and Cu suggesting physiological differences between the species and/or differences in the exposure of the organisms due to physico-chemical conditions and metal distribution between dissolved and particulate phases. In contrast, Hg bioaccumulation was highest for cockles reaching bioconcentration factors of ?200,000, which even exceeded that of Cd in oysters (50,000) for the same exposition period. Nevertheless, Hg concentrations remained relatively low in the three bivalve species

17

Fitting a predator prey model to zooplankton time-series data in the Gironde estuary (France): Ecological significance of the parameters  

Science.gov (United States)

The relationships between the seasonal fluctuations of the copepod Eurytemora affinis and the mysid Neomysis integer were studied from observed data and experimental results, using a predator-prey model in the oligo-mesohaline area of the Gironde estuary. Mean seasonal fluctuations of abundances were derived from long term data series collected from 1978 to 2003 for both species. In situ predator-prey experiments over a seasonal cycle were used to estimate the seasonal variation of the consumption rate of N. integer on E. affinis and to verify the order of magnitude of the biological parameters given by the model. Predator-prey experiments revealed a high seasonal variation in maximum consumption rates with a mean of 56 ± 9 ind. pred -1 d -1. Maximum consumption rates were always higher for adults than for juveniles of Neomysis integer. Recorded selectivities were higher on nauplii than on copepodids + adults of Eurytemora affinis, both for the juveniles and the adults of N. integer. Neomysis integer mainly fed on meroplanktonic larvae, when they were available in higher abundances, than E. affinis in their environment. Spring increases of abundance for Eurytemora affinis copepodids + adults seemed to be mainly controlled by temperature whereas its decreasing abundance in summer was more related to Neomysis integer predation, suggesting that summer fluctuations of E. affinis abundance are probably controlled by mysid predation at summer times. Using a Lotka-Volterra predator-prey model, the seasonal peak of abundance of the mysid N. integer was well reproduced considering a predation on copepodids + adults of E. affinis, and suggested a dependence between mysid and copepod seasonal variations. However, the seasonal peak amplitude could not be explained solely by a predation on copepodids + adults or on nauplii of the copepod. Thus, N. integer is probably dependent on the seasonal fluctuations of the copepod's abundance, complementing its diet with macrophytal detritus during periods of scarce food.

David, Valérie; Chardy, Pierre; Sautour, Benoît

2006-05-01

18

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

19

The particulate 7Be/210Pbxs and 234Th/210Pbxs activity ratios as tracers for tidal-to-seasonal particle dynamics in the Gironde estuary (France): implications for the budget of particle-associated contaminants.  

Science.gov (United States)

The short-lived natural radionuclides (7)Be (T(1/2)=53 days), (234)Th(xs) (T(1/2)=24.1 days) and (210)Pb(xs) (T(1/2)=22.3 years), i.e. (234)Th and (210)Pb in excesses of that supported within particles by the decay of their parent isotopes, were analysed in suspended particulate matter (SPM) to study the particle dynamics in the Gironde fluvial estuarine system (France), strongly impacted by heavy metal pollution. From surveys of this land-ocean interface in 2006 and 2007, we established a times series of these radioisotopes and of their activity ratios ((7)Be/(210)Pb(xs) and (234)Th/(210)Pb(xs) ARs) in particles sampled under different hydrological conditions. The particulate (7)Be/(210)Pb(xs) AR varies along the fluvial estuarine system mainly due to variations in (7)Be activities, controlled by riverine, oceanic and atmospheric inputs and by resuspension of old (7)Be-deficient sediments. These processes vary with river discharge, tidal cycle and season. Therefore, seasonal particle transport processes can be described using variations of the SPM (7)Be/(210)Pb(xs) ARs. During high river discharge, the SPM (7)Be/(210)Pb(x) ARs decrease from river to the ocean. The turbidity maximum zone (TMZ) is dispersed and the particles, and the associated contaminants, are rapidly transported from river to coastal waters, without significant retention within the TMZ. During low river discharge, the TMZ intrudes into the fluvial estuary, and the lowest (7)Be/(210)Pb(x) ARs are observed there due to resuspension of (7)Be-deficient sediments. Away from the TMZ, from the middle to lower estuary, SPM (7)Be/(210)Pb(x) ARs increase, indicating that the particles have been recently tagged with (7)Be. We explain this trend as being caused by marine input of dissolved radionuclides, as traced by SPM (234)Th/(210)Pb(xs) ARs, followed by scavenging in the estuary. This result indicates that particle transport models based on (7)Be and trace-metal budgets must consider oceanic dissolved inputs as an additional source of (7)Be and, possibly, of contaminants to estuaries. PMID:20659759

Saari, Hanna-Kaïsa; Schmidt, Sabine; Castaing, Patrice; Blanc, Gérard; Sautour, Benoît; Masson, Olivier; Cochran, J Kirk

2010-09-15

20

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

OpenAIRE

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

21

Fine-scale responses of phytoplankton to freshwater influx in a tropical monsoonal estuary following the onset of southwest monsoon  

Science.gov (United States)

In May of 2007, a study was initiated by the National Institute of Oceanography (NIO), Goa, India, to investigate the influence of monsoonal rainfall on hydrographic conditions in the Mandovi River of India. The study was undertaken at a location ˜2 km upstream of the mouth of this estuary. During the premonsoon (PreM) in May, when circulation in the estuary was dominated by tidal activity, phytoplankton communities in the high saline (35-37 psu) waters at the study site were largely made up of the coastal neritic species Fragilaria oceanica, Ditylum brightwellii and Trichodesmium erythraeum. During the later part of the intermonsoon (InterM) phase, an abrupt decline in salinity led to a surge in phytoplankton biomass (Chlorophyll a ˜14 mg m - 3), of a population that was dominated by Thalassiosira eccentricus. As the southwest monsoon (SWM) progressed and the estuary freshened salinity and Chlorophyll a (Chl a) concentrations decreased during the MoN, Skeletonema costatum established itself as the dominant form. Despite the low biomass (Chl a <2 mg m - 3), the phytoplankton community of the MoN was the most diverse of the entire study. During the postmonsoon (PostM), the increase in salinity was marked by a surge in dinoflagellate populations comprising of Ceratium furca, Akashiwo sanguinea, and Pyrophacus horologium.

Pednekar, Suraksha M.; Matondkar, S. G. Prabhu; Gomes, Helga Do R.; Goes, Joaquim I.; Parab, Sushma; Kerkar, Vijaya

2011-06-01

22

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

Directory of Open Access Journals (Sweden)

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

23

Modeling ecosystem processes with variable freshwater inflow to the Caloosahatchee River Estuary, southwest Florida. I. Model development  

Science.gov (United States)

Variations in freshwater inflow have ecological consequences for estuaries ranging among eutrophication, flushing and transport, and high and low salinity impacts on biota. Predicting the potential effects of the magnitude and composition of inflow on estuaries over a range of spatial and temporal scales requires reliable mathematical models. The goal of this study was to develop and test a model of ecosystem processes with variable freshwater inflow to the sub-tropical Caloosahatchee River Estuary (CRE) in southwest Florida from 2002 to 2009. The modeling framework combined empirically derived inputs of freshwater and materials from the watershed, daily predictions of salinity, a box model for physical transport, and simulation models of biogeochemical and seagrass dynamics. The CRE was split into 3 segments to estimate advective and dispersive transport of water column constituents. Each segment contained a sub-model to simulate changes in the concentrations of organic nitrogen and phosphorus (ON and OP), ammonium (NH4+), nitrate-nitrite (NOx-), ortho-phosphate (PO4-3), phytoplankton chlorophyll a (CHL), and sediment microalgae (SM). The seaward segment also had sub-models for seagrasses (Halodule wrightii and Thalassia testudinum). The model provided realistic predictions of ON in the upper estuary during wet conditions since organic nitrogen is associated with freshwater inflow and low salinity. Although simulated CHL concentrations were variable, the model proved to be a reliable predictor in time and space. While predicted NOx- concentrations were proportional to freshwater inflow, NH4+ was less predictable due to the complexity of internal cycling during times of reduced freshwater inflow. Overall, the model provided a representation of seagrass biomass changes despite the absence of epiphytes, nutrient effects, or sophisticated translocation in the formulation. The model is being used to investigate the relative importance of colored dissolved organic matter (CDOM) vs. CHL in submarine light availability throughout the CRE, assess if reductions in nutrient loads are more feasible by controlling freshwater quantity or N and P concentrations, and explore the role of inflow and flushing on the fates of externally and internally derived dissolved and particulate constituents.

Buzzelli, Christopher; Doering, Peter H.; Wan, Yongshan; Sun, Detong; Fugate, David

2014-12-01

24

Artificial radionuclides in French estuaries  

International Nuclear Information System (INIS)

Measurements were made of 238Pu, sup(239-240)Pu, 241Am, 137Cs, 144Ce, 106Ru, 125Sb and 131I in the principal rivers and estuaries of France (Seine, Loire, Gironde, Rhone). The mean specific activities due to sup(239-240)Pu in river water suspensions (5 to 10 fCi/g) are very little affected by releases from nuclear power stations. The unexpectedly high 238Pu/sup(239-240)Pu activity ratios (0.15 to 0.25) found in media subject only to atmospheric fall-out results from fractionation in the catchment areas. The high artificial radionuclide activities measured in the Seine estuary are attributed to releases from Windscale and, above all, from La Hague. The 137Cs found in Gironde river water remains associated with particles in the estuary. It decreases downstream by ion exchange in the estuary of the Loire, whereas in the Seine estuary the values recorded are higher than upstream owing to the effects of marine contamination. Particulate sup(239-240)Pu increases in all cases between the river and the estuary, a result which is in line with its frequent deficit in solution. However, the transfer of dissolved fluvial sup(239-240)Pu (0.05 to 0.2 fCi/ltr) cannot account for the excess in the particulate phase, the origin of which is ascribed to dissolved marine plutonium. (author)

25

Modeling ecosystem processes with variable freshwater inflow to the Caloosahatchee River Estuary, southwest Florida. II. Nutrient loading, submarine light, and seagrasses  

Science.gov (United States)

Short- and long-term changes in estuarine biogeochemical and biological attributes are consequences of variations in both the magnitude and composition of freshwater inputs. A common conceptualization of estuaries depicts nutrient loading from coastal watersheds as the stressor that promotes algal biomass, decreases submarine light penetration, and degrades seagrass habitats. Freshwater inflow depresses salinity while simultaneously introducing colored dissolved organic matter (color or CDOM) which greatly reduces estuarine light penetration. This is especially true for sub-tropical estuaries. This study applied a model of the Caloosahatchee River Estuary (CRE) in southwest Florida to explore the relationships between freshwater inflow, nutrient loading, submarine light, and seagrass survival. In two independent model series, the loading of dissolved inorganic nitrogen and phosphorus (DIN and DIP) was reduced by 10%, 20%, 30%, and 50% relative to the base model case from 2002 to 2009 (2922 days). While external nutrient loads were reduced by lowering inflow (Q0) in the first series (Q0 series), reductions were accomplished by decreasing the incoming concentrations of DIN and DIP in the second series (NP Series). The model also was used to explore the partitioning of submarine light extinction due to chlorophyll a, CDOM, and turbidity. Results suggested that attempting to control nutrient loading by decreasing freshwater inflow could have minor effects on water column concentrations but greatly influence submarine light and seagrass biomass. This is because of the relative importance of Q0 to salinity and submarine light. In general, light penetration and seagrass biomass decreased with increased inflow and CDOM. Increased chlorophyll a did account for more submarine light extinction in the lower estuary. The model output was used to help identify desirable levels of inflow, nutrient loading, water quality, salinity, and submarine light for seagrass in the lower CRE. These findings provide information essential to the development of a resource-based approach to improve the management of both freshwater inflow and estuarine biotic resources.

Buzzelli, Christopher; Doering, Peter; Wan, Yongshan; Sun, Detong

2014-12-01

26

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

27

Lames Retouchées Magdaléniennes du Morin (Gironde  

Directory of Open Access Journals (Sweden)

Full Text Available Des lames retouchées, souvent appointées ou tronquées, ont été signalées dans le Magdalénien supérieur par divers auteurs. R. de Saint-Périer notamment en figure plusieurs exemplaires provenant du Magdalénien de la Salle Saint-Martin et surtout du Magdalénien de la Grande Salle d'Isturitz, Basses-Pyrénées, Jude signale dans la couche III de la grotte de Rochereil, Dordogne, avec des lames tronquées, des lames appointées et arquées. M. et Saint-Just Péquart figurent du Magdalénien supérieur de la grotte du Mas-d'Azil, Ariège, des «lames lancéolées» et diverses lames, certaines appointées ou tronquées.Nous étudions ici la morphologie et les traces d'utilisation d'une série de lames retouchées recueillies dans le Magdalénien supérieur VI du gisement du Morin (Gironde par R. Deffarge: elles proviennent du niveau inférieur B I et des niveaux supérieurs A IV et A III.

Denise de SONNEVILLE-BORDES

2009-10-01

28

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

OpenAIRE

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...

Martin, G. D.; Muraleedharan, K. R.; Vijay, J. G.; Rejomon, G.; Madhu, N. V.; Shivaprasad, A.; Haridevi, C. K.; Nair, M.; Balachandran, K. K.; Revichandran, C.; Jayalakshmy, K. V.; Chandramohanakumar, N.

2010-01-01

29

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)

30

Climatic facilitation of the colonization of an estuary by acartia tonsa  

OpenAIRE

Global change has become a major driving force of both terrestrial and marine systems. Located at the interface between these two realms, estuarine ecosystems are probably the place where both direct and indirect effects of human activities conspire together to affect biodiversity from phytoplankton to top predators. Among European estuarine systems, the Gironde is the largest estuary of Western Europe and many studies have provided evidence that it has been affected by a variety of anthropog...

Chaalali, A.; Beaugrand, G.; Raybaud, V.; Goberville, E.; David, V.; Boe?t, P.; Sautour, B.

2013-01-01

31

The contribution of 14C dating to a better understanding of the POM behaviour in estuaries  

International Nuclear Information System (INIS)

The discordance between radiocarbon dates and dates obtained with 210Pb and historical data in cores recovered from tidal flats of the Gironde estuary, is explained. According to the results, it appears that the deposited Particulate Organic Matter (POM), taken in account by 14C dating, is mainly pedologic in origin and relatively old, while other dating technics provide information on the sedimentation pattern itself. 23 refs.; 5 figs.; 3 tabs

32

Behavior of natural radionuclides in surficial sediments from an estuary impacted by acid mine discharge and industrial effluents in Southwest Spain.  

Science.gov (United States)

The environmental degradation resulting from the acid mine drainage (AMD) and discharge from effluents of phosphogypsum (PG) piles in the watershed of Tinto and Odiel Rivers estuary over long periods of time has resulted in significant impact on the ecosystem of this estuary, resulting that the sediments are highly polluted by heavy metals and radionuclides from the discharge AMD and leachates from the PG. During resuspension of benthic sediments some of the radionuclides are desorbed making them bioavailable. In the present study, we investigate the spatial distribution of radionuclides U, Th and Ra and assess the factors and processes that caused the spatial distribution of these nuclides in this estuarine system. This study has global significance for other polluted environmental systems that are impacted by AMD and PG. PMID:22327046

Hierro, A; Bolivar, J P; Vaca, F; Borrego, J

2012-08-01

33

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

Science.gov (United States)

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 (~1955-2001) records of Ag and Cd concentrations in reservoir sediment with the respective concentrations in oysters collected between 1979 and 2010 to identify the origin and historical trend of the recently discovered Ag anomaly. Sediment cores from two reservoirs upstream and downstream from the main metal pollution source provided information on (i) geochemical background (upstream; Ag: ~0.3 mg kg(-1); Cd: ~0.8 mg kg(-1)) and (ii) historical trends in Ag and Cd pollution. The results showed parallel concentration-depth profiles of Ag and Cd supporting a common source and transport. Decreasing concentrations since 1986 (Cd: from 300 to 11 mg kg(-1); Ag: from 6.7 to 0.43 mg kg(-1)) reflected the termination of Zn ore treatment in the Decazeville basin followed by remediation actions. Accordingly, Cd concentrations in oysters decreased after 1988 (from 109 to 26 mg kg(-1), dry weight (dw)), while Ag bioaccumulation increased from 38 up to 116 mg kg(-1), dw after 1993. Based on the Cd/Ag ratio (Cd/Ag~2) in oysters sampled before the termination of zinc ore treatment (1981-1985) and assuming that nearly all Cd in oysters originated from the metal point source, we estimated the respective contribution of Ag from this source to Ag concentrations in oysters. The evolution over the past 30 years clearly suggested that the recent, unexplained Ag concentrations in oysters are due to increasing contributions (>70% after 1999) by other sources, such as photography, electronics and emerging Ag applications/materials. PMID:21868056

Lanceleur, Laurent; Schäfer, Jörg; Chiffoleau, Jean-François; Blanc, Gérard; Auger, Dominique; Renault, Sophie; Baudrimont, Magalie; Audry, Stéphane

2011-11-01

34

Climatic facilitation of the colonization of an estuary by Acartia tonsa.  

Science.gov (United States)

Global change has become a major driving force of both terrestrial and marine systems. Located at the interface between these two realms, estuarine ecosystems are probably the place where both direct and indirect effects of human activities conspire together to affect biodiversity from phytoplankton to top predators. Among European estuarine systems, the Gironde is the largest estuary of Western Europe and many studies have provided evidence that it has been affected by a variety of anthropogenic stressors such as thermal and chemical pollution, physical alterations and exploitation, especially for maritime traffic. In such a context, species introduction is also a current major issue with the establishment of strong competitive species that could lead to ecosystem reorganization with potential decrease or even disappearance of native species. In the Gironde estuary, this hypothesis was proposed for the invasive shrimp species Palaemon macrodactylus as a decrease in the native species abundance was observed at the same time. Although species introduction often takes place via ballast water, the influence of climate-driven changes on the establishment of new species remains a key issue. The calanoid copepod Acartia tonsa, observed in the Gironde estuary for the first time in 1983, have since colonized most part of the estuary, reaching a level of abundance comparable to the dominant native species Eurytemora affinis. In this study, using both the concept of the ecological niche sensu Hutchinson (fundamental and realized niches) and statistical models, we reveal that the dynamics of the colonization of A. tonsa was facilitated by environmental conditions that have become closer to its environmental optimum with respect to temperature and salinity. PMID:24098656

Chaalali, Aurélie; Beaugrand, Grégory; Raybaud, Virginie; Goberville, Eric; David, Valérie; Boët, Philippe; Sautour, Benoit

2013-01-01

35

Climatic Facilitation of the Colonization of an Estuary by Acartia tonsa  

Science.gov (United States)

Global change has become a major driving force of both terrestrial and marine systems. Located at the interface between these two realms, estuarine ecosystems are probably the place where both direct and indirect effects of human activities conspire together to affect biodiversity from phytoplankton to top predators. Among European estuarine systems, the Gironde is the largest estuary of Western Europe and many studies have provided evidence that it has been affected by a variety of anthropogenic stressors such as thermal and chemical pollution, physical alterations and exploitation, especially for maritime traffic. In such a context, species introduction is also a current major issue with the establishment of strong competitive species that could lead to ecosystem reorganization with potential decrease or even disappearance of native species. In the Gironde estuary, this hypothesis was proposed for the invasive shrimp species Palaemon macrodactylus as a decrease in the native species abundance was observed at the same time. Although species introduction often takes place via ballast water, the influence of climate-driven changes on the establishment of new species remains a key issue. The calanoid copepod Acartia tonsa, observed in the Gironde estuary for the first time in 1983, have since colonized most part of the estuary, reaching a level of abundance comparable to the dominant native species Eurytemora affinis. In this study, using both the concept of the ecological niche sensu Hutchinson (fundamental and realized niches) and statistical models, we reveal that the dynamics of the colonization of A. tonsa was facilitated by environmental conditions that have become closer to its environmental optimum with respect to temperature and salinity. PMID:24098656

Chaalali, Aurélie; Beaugrand, Grégory; Raybaud, Virginie; Goberville, Eric; David, Valérie; Boët, Philippe; Sautour, Benoit

2013-01-01

36

The role of phosphorus on planktonic production of the Gironde plume waters in the Bay of Biscay  

OpenAIRE

More and more studies emphasize the status of phosphorus (P) as the principal limiting nutrient of phytoplankton growth, especially in coastal waters under the influence of freshwater discharges. The purpose of the present paper is to investigate the role of P on planktonic production in the waters influenced by the Gironde discharges; the Gironde being one of the two largest rivers on the French Atlantic coast. The survey is based on several cruises made in 1998 and 1999. Two different patte...

Labry, Claire; Herbland, Alain; Delmas, Daniel

2002-01-01

37

Southwest Economy  

Science.gov (United States)

The Dallas Federal Reserve Bank publishes Southwest Economy bimonthly; it covers "agriculture, banking, energy, high technology, manufacturing and international trade" in the Texas- New Mexico- Louisiana region.

38

Initiation of winter phytoplankton blooms within the Gironde plume waters in the Bay of Biscay  

OpenAIRE

Thermostratification and seasonal Light increase are generally considered the first causes of phytoplankton spring blooms in temperate waters. The objective of this study is to confirm the existence of winter phytoplankton blooms, responsible for the early exhaustion of phosphate, within the Gironde plume waters (southeast Bay of Biscay), and to understand what may initiate them so early. Two cruises, BIOMET 2 and BIOMET 3, were carried out respectively in early (8 to 21 January) and late win...

Labry, Claire; Herbland, Alain; Delmas, Daniel; Laborde, P.; Lazure, Pascal; Froidefond, J.; Jegou, Anne-marie; Sautour, B.

2001-01-01

39

Activité et production des navires français ? Façade "Manche est" et Façade "Loire-Gironde"  

OpenAIRE

This report is a result of a contract between Ifremer and the French Ministry of Industry. The aim was to provide map the fisheries activity and landings for french fishing vessels, located in the Eastern Channel and the Bay of Biscay during the year 2005. Two areas have been selected: - the "Eastern Channel" area, including 7 administrative departments : Nord, Pas-de-Calais, Somme, Seine-Maritime, Eure, Calvados and Manche. - the "Loire-Gironde" area, including 4 administrative depart...

Delpech, Jean-paul; Mehault, Sonia; Rostiaux, Emilie; Leaute, Jean-pierre; Leblond, Emilie; Demaneche, Sebastien; Coppin, Franck; Mahe, Kelig; Vaz, Sandrine

2007-01-01

40

Geochemical behaviour of plutonium isotopes in natural media (lakes, rivers, estuaries)  

International Nuclear Information System (INIS)

Artificial radionuclide activities (238Pu, 239+240Pu) were measured in natural environments. Their distribution and geochemical behaviour are evaluated and compared them to these of the 137Cs. In a volcanic crater lake, influenced only by atmospheric fallout (Lac Pavin, France), sediments are enriched in 239+240Pu, whereas 137Cs stays in the dissolved phase. Diffusion processes and migration of radionuclides is shown to occur in sediments. Remobilization of 239+240Pu is probable at the sediment/water interface. In the Garonne-Dordogne, Seine and Loire rivers, the 239+240Pu activity levels in suspended matter are little influenced by the waste discharges of nuclear power plants. The element is essentially transported in the particulate fraction, more than is 137Cs. In all the esturies studied (Gironde, Seine, Loire) 239+240Pu concentrations in suspended matter increase between the river and the estuary. Simultaneously a removal of plutonium from the dissolved phase is observed. High plutonium concentrations are measured in the Seine estuary; they are attributed to a ''marine'' contamination: the French nuclear reprocessing plant of La Hague discharges low level radioactive liquid wastes, a part may reach the Seine estuary. There are no decrease in particulate 137Cs concentrations between the river and the estuary of the Gironde, such as it occurs in the Loire. In this last case, the phenomenon is explained by the presence of ''young caesium'' originating in the power plant effluents and which is more exchangeable than 137Cs of atmospheric origin. In the Seine estuary, the influence of marine contamination causes an increase of particulate and dissolved 137Cs concentrations

41

La contamination par le cadmium en Gironde et son extension sur le plateau continental  

OpenAIRE

La répartition du cadmium dans l'eau, le sédiment et la matière en suspension de la Gironde, du proche plateau cohtinental et de la baie de Marennes-Oléron a été étudiée lors de trois campagnes réalisées en conditions de débits moyens ou d'étiage de la Garonne et de la Dordogne. Des apports anormaux de cadmium particulaire par la Garonne ont été mis en évidence. Après désorption ou solubilisation, ils sont expulsés sous forme dissoute, formant un panache très net mais peu ?...

Boutier, Bernard; Chiffoleau, Jean-francois

1986-01-01

42

THE EFFICIENCY OF SELECTIVE TIDAL STREAM TRANSPORT IN GLASS EEL ENTERING THE GIRONDE (FRANCE  

Directory of Open Access Journals (Sweden)

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.

BEAULATON L.

2005-10-01

43

Concentrations of suspended particulate organic carbon in the tidal Yorkshire Ouse River and Humber Estuary.  

Science.gov (United States)

Data are presented for particulate organic carbon (POC) and particulate nitrogen (PN) concentrations in the Humber Estuary and tidal River Ouse Estuary. The POC data were derived from approximately monthly surveys and are consistent with data reported for suspended particulate matter (SPM) in the non-tidal River Ouse (the freshwater river) and with SPM, or bed sediments, in estuarine ecosystems such as the Mississippi, Delaware, San Francisco Bay, Tolo Harbour, the Vellar Estuary and Cochin Backwater, as well as the Loire, Gironde, Ems and Tamar Estuaries. Relative to the dry weight of SPM, the Humber-averaged organic carbon and nitrogen percentages during the year February 1995-March 1996 were 2.6 +/- 0.6% (mean and S.D.) and 0.21 +/- 0.04%, respectively. The ratio of Humber-averaged POC to Humber-averaged PN was 13 +/- 3. Higher POC levels were observed near the Humber's mouth and in the adjacent coastal zone during 'bloom' conditions, and in the upper estuarine reaches during large, winter and springtime freshwater inflows. At these times of high runoff, the POC content of SPM increased progressively up-estuary from the coastal zone to the tidal River Ouse. When inflows became very low, during late spring to early autumn of 1995, both the freshwater-saltwater interface (FSI) and the strengthening turbidity maximum (TM) moved further up-estuary and the POC content of SPM in the upper reaches of the Ouse became lower compared with that immediately down-estuary. This led to a poorly defined POC maximum near the confluence of the Humber, Ouse and Trent, before POC eventually decreased again towards the coastal zone. The lower POC contents in the upper estuarine reaches of the tidal Ouse may have been partly due to POC respiration by heterotrophic bacteria attached to SPM within the TM, consistent with the severe oxygen depletion observed there during high turbidity, summertime spring tides. PMID:10847164

Uncles, R J; Frickers, P E; Easton, A E; Griffiths, M L; Harris, C; Howland, R J; King, R S; Morris, A W; Plummer, D H; Tappin, A D

2000-05-01

44

Local heritage to singularize a wine terroir: the example of pays Foyen (Gironde, France  

Directory of Open Access Journals (Sweden)

Full Text Available Le vin, enjeu culturel et économique, se trouve aujourd’hui au cœur de dynamiques locales œuvrant à produire de la différence : souvent sous l’impulsion de néoruraux, des éléments naturels et d’histoire locale sont sélectionnés et mobilisés pour recomposer un patrimoine fondateur d’identité, fabriquer une authenticité, et donc légitimer des pratiques. Cet article propose d’observer le phénomène de patrimonialisation afin de comprendre comment les frontières se sont progressivement resserrées autour d’un vin régional devenu un vin local, à travers l’exemple d’un espace viti-vinicole, le Pays Foyen (Gironde, France. Après avoir éclairé les tensions théoriques entre global et local, nous nous intéressons particulièrement au processus de territorialisation et de construction identitaire lié à la mise en valeur du « local » dans le produit.Wine, as a cultural and economic product, is today at the heart of local dynamics working towards producing singularity: often under the impulse of neorurals, elements from the local environment and history are selected and used to recompose a heritage which creates an identity, to make up authenticity, therefore to legitimize specific practices. This paper aims at highlighting the current phenomenon of patrimonialization in order to understand how a regional wine turned into a local wine through the observation of a wine terroir, the Pays Foyen (Gironde, France. After theoretic considerations on global/local tensions, we’ll concentrate on spatial definitions and identity construction linked to the promotion of “locality” in the product.

Chantal Crenn

2007-04-01

45

Cartographie synthétique et analyse des peuplements benthiques sur deux secteurs du littoral français "Manche-Est" et "Loire-Gironde"  

OpenAIRE

Ce document présente une étude synthétique des peuplements benthiques marins sur deux façades du littoral métropolitain français : la Manche-Est et la zone Loire-Gironde. Cette synthèse originale résulte d’un inventaire des documents cartographiques existants dans la littérature et publiés pour l’essentiel durant les années 1970. Ce document reprend les descriptions et analyses faites par les différents auteurs, en les transcrivant selon les normes actuelles notamment vis-à-v...

Blanchard, Michel; Heim, Marie; Rozec, Xavier; Caisey, Xavier

2008-01-01

46

Radiotracer studies of the dispersion of solid pollutants in marine and estuarial environments. Measurements of diffusion coefficients and phenomenon of dispersion by currents  

International Nuclear Information System (INIS)

The transfer in suspension of solid particles which may be pollutant vectors is deduced from studies in a natural environment of the circulation, dispersion and decantation of suspensions created by artificial discharge or by erosion of the bed. In the Gironde estuary, where the tide comes in 90 km, radiotracer experiments describe and quantify the transfers of sediments eroded from the bottom of the principal channel to the secondary channel and their return upstream. A mechanism whereby silts move upstream produces progressive dilution of 90% of the eroded material, while a rapid transfer system causing 10% to move upstream produces far less thorough dilution. Both in the Gironde estuary and in the Baie de la Seine, hydrodynamic dispersion is a phenomenon of negligible importance during the first hours after discharge of erosion. The suspensions are diluted by decantation and the artificial discharges circulate in high concentrations around the discharge point. The measured dispersion coefficients are generally less than 0.5 m2/s. (author)

47

Exploitation of trophic resources by fish under stressful estuarine conditions  

OpenAIRE

Despite the high complexity and variability of estuaries, these ecosystems are very productive and play an important role in fish feeding. This paper constitutes a preliminary investigation to test how fish optimize the use of the available trophic resources, by studying trophic preference variability and feeding strategies of some pelagic and demersal fish in the Gironde estuary (southwest France). Fish and their prey were collected approximately every two months from July 2003 to June 2004 ...

Pasquaud, S.; David, V.; Lobry, J.; Girardin, M.; Sautour, B.; Elie, P.

2010-01-01

48

Volunteer Estuary Monitoring  

Science.gov (United States)

This online method manual from EPA describes how to conduct estuary monitoring programs, with step-by-step guides for chemical, physical and biological sampling and data interpretation. Also describes how to plan and maintain a volunteer force, with tips on liability and financial issues, volunteer recruiting training and retention. Addresses quality assurance so that results have weight. Provides an overview of estuarine science, threats to estuaries and some solutions.

49

Evaluation and reduction of ecological impacts related to household consumption: methodological conception and application to the Pays Cœur Entre-deux-Mers, Gironde, France  

OpenAIRE

The aim of this thesis is to strengthen the conceptual and methodological foundations of ecoresponsible consumption. These notions are then applied to the peri-urban area of the “Pays Cœur Entre-deux-Mers” (Gironde, France) in order to provide the main societal actors with some elements to help them towards a better understanding of ways to promote and evaluate ecoresponsible consumption. This is an exploratory process based on the ecology of the family; it involves a multi-disciplinary ...

Sennes, V.

2008-01-01

50

Estuarine Science: All About Estuaries  

Science.gov (United States)

Estuaries are partially enclosed bodies of water along coastlines where fresh water and salt water meet and mix. They act as a transition zone between oceans and continents. This site examines various aspects of estuaries, focusing on the geological features that make an estuary, as well as the water circulation patterns by which they are classified. It also has a section that allows the user to access additional text and graphics on many of the estuaries of the world.

51

Descriptive epidemiology of CNS tumors in France: results from the Gironde Registry for the period 2000–2007  

Science.gov (United States)

An increase in the incidence of CNS tumors has been observed in many countries in the last decades. The reality of this trend has been much debated, as it has happened during a period when computer-assisted tomography and MRI have dramatically improved the detection of these tumors. The Gironde CNS Tumor Registry provides here the first data on CNS tumor incidence and trends in France for all histological types, including benign and malignant tumors, for the period 2000–2007. Incidence rates were calculated globally and for each histological subtype. For trends, a piecewise log-linear model was used. The overall annual incidence rate was found to be 17.6/100 000. Of this rate, 7.9/100 000 were neuroepithelial tumors and 6.0/100 000 were meningiomas. An overall increase in CNS tumor incidence was observed from 2000 to 2007, with an annual percent change (APC) of +2.33%, which was explained mainly by an increase in the incidence of meningiomas over the 8-year period (APC = +5.4%), and also more recently by an increase in neuroepithelial tumors (APC = +7.45% from 2003). The overall increase was more pronounced in women and in the elderly, with an APC peaking at +24.65% in subjects 85 and over. The increase in the incidence rates we observed may have several explanations: not only improvements in registration, diagnosis, and clinical practice, but also changes in potential risk factors. PMID:21980160

Baldi, I.; Gruber, A.; Alioum, A.; Berteaud, E.; Lebailly, P.; Huchet, A.; Tourdias, T.; Kantor, G.; Maire, J.P.; Vital, A.; Loiseau, H.; Champeaux, K; Dhauteribes, M; Eimer, S; Gimbert, E; Liguoro, D; Monteil, P; Penchet, G; San-Galli, F; Vignes, JR

2011-01-01

52

¡Salud! Southwest Tour  

OpenAIRE

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 ...

Joanna Mae Mae Souers

2009-01-01

53

The American Southwest  

Science.gov (United States)

The American Southwest is a personally maintained Web site that, though primarily a travel guide, is also a unique collection of photographs and descriptions of physical geology of seven states. Dozens of photographs and even several panoramic views are available from California, Arizona, Colorado, Nevada, New Mexico, Texas, and Utah, as well as a special section on slot canyons. If only for the freely viewed photos, this site is a fabulous resource.

54

Modélisation du transport de sédiments mixtes sable-vase et application à la morphodynamique de l'estuaire de la Gironde (France)  

OpenAIRE

Cette étude tente de modéliser les taux de transport de sédiments et l'évolution du lit dans un milieu estuarien complexe : l'estuaire de la Gironde, caractérisé par une grande hétérogénéité dans la composition des sédiments de lit, avec la présence de sédiments cohésifs et non-cohésifs ainsi que des mélanges sablo-vaseux. Notre objectif principal est d'étendre un modèle morphodynamique 2D développé par Huybrechts et al. (2012b) pour les sédiments non-cohésifs, afin de ...

Do, Lan Anh

2012-01-01

55

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

OpenAIRE

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...

Herbland, Alain; Delmas, Daniel; Laborde, Pierre; Sautour, Benoit; Artigas, Felipe

1998-01-01

56

Seasonal Abundance of Micro Algae in Pandi Backwaters of Godavari Estuary, Andhra Pradesh, India  

OpenAIRE

Gautami branch of Godavari River is a typical positive estuary and is in tidal communication with the open sea upto a point near Kapileswarapuram. This branch flows southwest and opens into Bay of Bengal at two places, namely Bhiravapalem and Kothapalem. The Gautami branch of Godavari is also connected to Pandi backwaters by a channel known as Pedderu, which starts at Kothapalem, Balusutippa area and enters Pandi back water system. Two stations were selected for collection of data. Hydrograph...

Narasimha Rao, Geddada Mohan; Pragada, Prayaga Murty

2010-01-01

57

Go Southwest, Old Man  

OpenAIRE

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

58

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

59

Southwest Asia assessment.  

Science.gov (United States)

Southwest Asia, which support 1/3 of the world's population, is acutely aware of the consequences of rapid and excessive population growth. No other region has consciously devoted so much of its resources to stemming excessive population growth. India, with a population of 684 million, formulated a policy of population limitation in the 1950s. The 1980 government rededicated itself to voluntary family planning and rebuilt the broad coalition of an excellent infrastructure of government institutions, voluntary organizations, and international agencies. Government support for family planning clinics began in Bangladesh in the 1960s. A strong institutional structure has been established under the supervision of the National Population Council. Innovative approaches to family planning service delivery have been initiated by an admirable array of institutions. Pakistan's Population Welfare Plan provides substantial funds and an administrative structure to make maternal/child helath care and family planning services available in rural areas. Another welfare program encourages smaller families through projects to enhance the status of women by improving literacy, establishing rural industries, and advocating late marriage. Nepal has had to struggle with a poor administrative structure, grossly insufficient medical services, and an inadequate database for policy formulation. Family planning services are now a component of the overall health program. The family planning services of the pioneer Afghan Family Guidance Association, established in 1968, have been incorported into the national maternal/child health program. The present government of Iran views foreign assistance as an unacceptable form of persuasion and has phased out all international funded family planning programs. Sri Lanka is the only country in the region to have made the demographic transition to fertility decline. An impressive health infrastructure delivers family planning services at every level using medical and paramedical professionals, a large scale retail sale of contraceptive, wide media coverage, and cash incentives for sterilization. Throughtout Southwest Asia the major problem encountered by policymakers has been the strong political sensitivity of population programs. Southwest Asis has produced several innovative ideas in the field of population programs. International assistance has played an important role in the development of the region's national family planning programs. PMID:12339632

Devendra, T

1984-06-01

60

¡Salud! Southwest Tour  

Directory of Open Access Journals (Sweden)

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

61

Southwest Journal of Cultures  

Science.gov (United States)

Sponsored by Northeastern State University in Oklahoma, the Southwest Journal of Cultures is an online scholarly book review venue that is intended to bring academics and others book reviews from the field of culture studies. The Journal was first published in September 2008, and its editors have managed to cover a broad range of topics in a short time. Visitors can scroll through the most recent reviews, some of which include critical appraisals of works like "Chinese Street Opera in Singapore" and "Spare Time in Texas: Recreation and History in the Lone Star State". Visitors are welcome to leave their own comments on each review, and they can also look through the online archive. Those interested in starting their own like-minded project would do well to spend sometime navigating this well-thought out site.

62

Estimation of turbidity along the Guadalquivir estuary using Landsat TM and ETM+ images  

Science.gov (United States)

Estuarine water in Mediterranean basins has high concentrations of suspended sediment. In order to study the temporal and spatial distribution of turbidity, a monitoring network with sufficient temporal and spatial resolution is needed to monitor water quality, and this is not always available. Thus, over the last few years, satellite images have been used as an alternative way to estimate water quality parameters, such as turbidity. The Guadalquivir River estuary in south-west Spain extends for 105 km and is one of the world's most turbid estuaries. The sediments present are of a very fine texture due to the great length of the river but, mainly, to the extreme trapping efficiency of the dense reservoir system upstream. This work shows the relationship between turbidity patterns along the Guadalquivir river estuary and the data from Landsat ETM+ images from August 2008 to 2010, and the suitability of the algorithms previously used in this estuary environment, with the ultimate goal of obtaining turbidity maps. The results of this study show that the use of previously developed algorithms underestimate turbidity values measured by the monitoring network used, which proves that one single algorithm for the entire period of study does not provide a reliable reproduction of the real situation. The wide variability in turbidity data along the estuary has enabled us to develop specific expressions for each day, which allow us to obtain turbidity maps.

Carpintero, M.; Contreras, E.; Millares, A.; Polo, M. J.

2013-10-01

63

FLORA OF MOLOCHNYI ESTUARY COASTS  

Directory of Open Access Journals (Sweden)

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

64

FLORA OF MOLOCHNYI ESTUARY COASTS  

OpenAIRE

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.; Podorozhnyi S.N.

2013-01-01

65

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

OpenAIRE

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

66

Estuaries: Where Rivers Meet the Sea  

Science.gov (United States)

Take your students on an EstuaryLive telecast! EstuaryLive brings free, live internet field trips in four different estuaries around the country, right to your classroom. These online field trips are the next best thing to an actual trip to an estuary, providing students with an exciting and new way to learn about unique estuarine ecosystems. The site also includes archived webcasts and teacher resources including classroom activities and a glossary.

67

Réduction des pertes dans les réseaux d’alimentation en eau potable du département de la Gironde : valorisation de la sectorisation dans la lutte contre les fuites : rapport final  

OpenAIRE

This is the final report of a study on the quantification and reduction of water losses in water distribution networks, conducted by Cemagref in the framework of a three-year agreement (2009-2011) with the Department Council of Gironde. Three local authorities, fitted out with control zones: District Metered Areas, DMAs, were chosen to be partner of the study: - Lacanau municipality ; - SIEPA (Intercommunal Union for Water and Sewer Management) of Northern Libournais ; - La Réole local utili...

Renaud, E.; Khedhaouiria, D.; Clauzier, M.

2011-01-01

68

Arsenic speciation in river and estuarine waters from southwest Spain.  

Science.gov (United States)

An arsenic speciation survey was carried out in water samples from the Tinto and Odiel Rivers (southwest of Spain), as well as their common estuary. Both rivers are affected by acid mine drainage (AMD) and represent an input of heavy metals into the estuary, which also suffers from industrial water discharges. Samples were taken in December 2000 and July 2001. The arsenic species considered were arsenite (As(III)), arsenate (As(V)), monomethylarsonic (MMA) and dimethylarsinic (DMA) ions using coupled high-performance liquid chromatography-hydride generation-inductively coupled plasma-mass spectrometry (HPLC-HG-ICP-MS) for their determination. Parameters such as pH, salinity, redox potential and dissolved O2 were also measured. The results revealed that the acid mine drainage originating mainly during winter along the upper part of the Tinto River course causes high inorganic concentrations of dissolved arsenic, up to 600 microg l(-1) of As(III) and 200 microg l(-1) of As(V). In summer, As(III) levels decreased due to the diminution of the input from acid mine drainage and also because of oxidation, with a corresponding increase of As(V) level. Furthermore, the extreme acidic conditions of this river (pH 2.3-2-6) do not allow biological activity sufficient to produce significant concentrations of methylated arsenic species. The arsenic concentrations in the nearby Odiel River were always 5-10 times lower than in the Tinto River, with arsenic levels usually below 100 microg l(-1), dominated by As(V), indicating that it is less affected by acid mine drainage. The highest inorganic arsenic species concentrations were found where the river crosses a mining site, which corresponds to the highest As(III) values. Significant biological activity in this river produced methylated species that were detected along the water-course, with the highest concentrations at the lower course of the river, accounting for up to 53-61% of the total dissolved arsenic. At the common estuary formed by both rivers, only arsenate was detected in most samples at lower concentrations than in the riverine water samples. The tidal cycle showed a similar pattern of dilution of the arsenate when seawater comes into the estuary. Methylated species were not found either in summer or winter, at least at the 0.1 microg l(-1) level, possibly because of the high turbidity of the waters, producing an inhibition of the phytoplankton activity. In addition to the riverine inputs into the common estuary, industrial activity also represents an important source of arsenic as the discharge from a Cu smelter produced the highest arsenate level of all samples in estuary and also the only sample with significant arsenite concentration. Furthermore, the underlying iron-oxide-rich sediments represent an importance source of arsenic into the water column. In three nearby estuaries not affected by industrial activity or acid mine drainage, arsenic levels remained below detection limits. PMID:15919540

Sánchez-Rodas, Daniel; Luis Gómez-Ariza, José; Giráldez, Inmaculada; Velasco, Alfredo; Morales, Emilio

2005-06-01

69

Phosphorous speciation in surface sediments of the Cochin estuary.  

Science.gov (United States)

Sequential chemical extraction using chelating agents were used to study the P dynamics and its bioavailability along the surface sediments of the Cochin estuary (southwest coast of India). Sediments were analyzed for major P species (iron bound P, calcium bound P, acid soluble organic P, alkali soluble organic P and residual organic P), Fe, Ca, total carbon, organic carbon, total nitrogen and total sulfur contents. An abrupt increase in the concentration of dissolved inorganic P with increasing salinity was observed in the study region. Iron-bound P exhibited a distinct seasonal pattern with maximum values in the monsoon season when fresh water condition was prevailed in the estuary. As salinity increased, the percentage of iron-bound P decreased, while that of calcium-bound P and total sedimentary sulfur increased. C/P and N/P ratios were low which indicate that large amounts of organic matter enriched with P tend to accumulate in surface sediments. The high organic P contribution in the sedimentary P pool may indicate high organic matter load with incomplete mineralization, as well as comparatively greater percentage of humic substance and resistant organic compounds. Principal component analysis is employed to find the possible processes influencing the speciation of P in the study region and indicate the following processes: (1) the spatial and seasonal variations of calcium bound P and acid soluble organic P was mainly controlled by sediment texture and organic carbon content, (2) sediment redox conditions control the distribution of iron bound P and (3) the terrigenous input of organic P is a significant processes controlling total P content in surface sediments. The bioavailable P was very high in the surface sediments which on an average accounts for 59 % in the pre-monsoon, 65 % in the monsoon and 53 % in the post-monsoon seasons. The surface sediments act as a potential internal source of P in the Cochin estuary. PMID:22843296

Gireeshkumar, T R; Deepulal, P M; Chandramohanakumar, N

2013-03-01

70

Oil spill trajectory analysis for the Calcasieu Estuary  

International Nuclear Information System (INIS)

A three-dimensional hydrodynamic model (H3D) was used to determine how oil spills might travel and spread within the Calcasieu River Estuary which has heavy oil traffic. The Calcasieu River is located in the southwest corner of the State of Louisiana and houses valuable wetlands that provide both commercial and recreational fishing and wildlife value to the area. These wetlands also filter water and protect Louisiana's coast areas from hurricane storm surges. An oil spill would damage areas of marshes that would have devastating effects on the entire ecological system within the estuary. A Trajectory Analysis Planner (TAP) H3D computer model is under development by the Hazardous Materials Response Division of the National Oceanic and Atmospheric Administration (NOAA). TAP is a statistical planning tool that randomly samples historical hydrodynamic, hydrology and climatological data, to build up a database with biological and cleanup resource information. TAP can be used to predict which sites within the estuarine system will be most susceptible to oil spills of varying magnitudes, materials and locations. TAP can also estimate the time available for mitigation and remedial actions before the spill can impact the site. Hydrodynamics in the Calcasieu estuary is a combination of processes such as saltwater intrusion and response to water level fluctuations at an open boundary, as well as lake dynamics. H3D provides the three components of velocity, plus scalar quantitiesonents of velocity, plus scalar quantities such as water levels, temperature and salinity distribution on a Cartesian three-dimensional grid. TAP was tested for spills of kerosene, non-weathering oil, crude oil, and gasoline and was able to perform reliable spill trajectory analysis. 12 refs., 9 figs

71

Environmental data management in the Sado Estuary  

OpenAIRE

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

72

Bilan des connaissances relatives à la faune et à la flore, aux paysages, à l'occupation du sol - Inventaires des contraintes d'environnement - Biologie de l'estuaire de la Gironde - Synthèse des prospective  

OpenAIRE

Sur les quelques 150 publications recensées sur la biologie de l'estuaire, seulement 18 ont été publiées avant 1975. Or c'est à partir de 1975 que le CNEXO et EDF ont commencé à promouvoir et soutenir les études d'écologie en Gironde dans la perspective de la construction de la centrale du Blayais. Ceci montre le désintérêt de la communauté scientifique pour l'écologie estuarienne dans les années 60-70 alors que l'écologie terrestre et limnique était en plein essor.

,

1993-01-01

73

Carbon dioxide emissions from Indian monsoonal estuaries  

Science.gov (United States)

The oceans act as a net sink for atmospheric CO2, however, the role of coastal bodies on global CO2 fluxes remains unclear due to lack of data. The estimated absorption of CO2 from the continental shelves, with limited data, is 0.22 to 1.0 PgC/y, and of CO2 emission by estuaries to the atmosphere is 0.27 PgC/y. The estimates from the estuaries suffer from large uncertainties due to large variability and lack of systematic data collection. It is especially true for Southeast Asian estuaries as the biogeochemical cycling of material are different due to high atmospheric temperature, seasonality driven by monsoons, seasonal discharge etc. In order to quantify CO2 emissions from the Indian estuaries, samples were collected at 27 estuaries all along the Indian coast during discharge wet and dry periods. The emissions of CO2 to the atmosphere from Indian estuaries were 4-5 times higher during wet than dry period. The pCO2 ranged between ~300 and 18492 microatm which were within the range of world estuaries. The mean pCO2 and particulate organic carbon (POC) showed positive relation with rate of discharge suggesting availability of high quantities of organic matter that led to enhanced microbial decomposition. The annual CO2 fluxes from the Indian estuaries, together with dry period data available in the literature, amounts to 1.92 TgC which is >10 times less than that from the European estuaries. The low CO2 fluxes from the Indian estuaries are attributed to low flushing rates and less human settlements along the banks of the Indian estuaries.

Sarma Vedula, VSS

2012-07-01

74

Tidal Asymmetry in Amazon Estuary  

Science.gov (United States)

Estuaries and coastal areas are the last reservoir of fine sediments yield in the continental basins. One of the most interesting questions for each particular system is where the fine sediments are trapped in larger quantities. In the early 90's, a thorough measurement project was held over the Amazon Continental Shelf and coastal zone. One of the results of this project was the register of a huge amount of sediments in suspension over the Shelf, where the turbidity maximum would be located. In order to promote the formation of a turbidity maximum zone, conditions for trapping and deposition are necessary as well as a source of energy to keep sediments in suspension, in general in a feed back way. Several mechanisms can be pointed as responsible for trapping sediments in estuaries and coastal areas. Sediments are carried by currents and the question could be established as which are the main features in the hydrodynamics which contributes to the formation of the turbidity maximum? Flocculation induced by the changes in the flow structure, mainly the reduction in turbulence, can be regarded as one of the mechanisms which contribute to the formation of the turbidity maximum In fact, in-situ measurements showed floc sizes as big as 600µm over the Amazon Shelf. Other feature which strongly affects hydrodynamics and hence trapping sediments is the creation of recirculation zones, related to the estuarine morphology, this aspect, especially important in open areas, is also important in the Amazon Shelf. The role of the shear stress asymmetry and the transport capacity asymmetry both related to the salt stratification structure are also shown as important mechanisms for sediment trapping in this environment. Focusing the understanding of the dynamics of fine sediments in Amazon estuary, the tide asymmetry in the Amazon estuary is analyzed. Changes in the vertical tide asymmetry are observed along the estuary. A positive vertical tide asymmetry is observed in the estuarine region with river influence, which is not indicative of positive velocity asymmetry, as is currently considered for tidal bays, without significant river discharge. Over the Shelf, where salinity intrusion and fluid mud bottom layers occur, negative tidal asymmetry is observed. Causes for the changes of the asymmetry and their consequences for the sediment transport are addressed in this work.

Vinzon, S. B.; Gallo, M. N.; Fernandes, R. D.

2007-05-01

75

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...

76

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

77

Seasonal differences in the physiology of Carcinus maenas (Crustacea: Decapoda) from estuaries with varying levels of anthropogenic contamination  

Science.gov (United States)

This study reports the seasonal variability in aspects of the physiology of the shore crab Carcinus maenas from three estuaries in South-west England, each with varying anthropogenic inputs: Avon Estuary ('relatively low' impact), Yealm Estuary ('intermediate' impact) and Plym Estuary ('relatively high' impact). Crabs collected over 12 months from the Avon had a significantly 'lower' physiological condition in winter and spring compared to summer and autumn; in particular, haemocyte phagocytic capability (a general indicator of immune function) was significantly higher in winter and spring compared to summer and autumn, and total haemolymph antioxidant status (an indicator of oxidative stress) was significantly lower in winter compared to the remainder of the year. Potentially, shore crabs may be more susceptible to the effects of contaminant exposure, such as increased immunotoxicity (thus, reduction of immune function) and/or oxyradicals (or reactive oxygen species) exposure) especially in seasons of increased susceptibility i.e. summer/autumn (lower phagocytic capability) and winter (lowest antioxidant function). As the Avon was taken to represent the 'reference' site, this pattern is considered to reflect the 'normal' seasonal variability in shore crab physiology. Shore crab physiological condition from the 'relatively high' impact estuary (Plym) revealed increased cellular viability and antioxidant status in autumn and winter compared with that of the 'standard' pattern (Avon) However, crabs from the intermediate impact estuary (Yealm) only demonstrated significant physiological differences in summer as shown by a lower cellular viability. All crabs had been exposed to PAHs (confirmed by the presence of PAH metabolites in their urine) which may account for the observed differences in shore crab physiology. In conclusion, to aid understanding of the potential contaminant impacts on biota it is imperative that the 'normal' seasonal variability of physiological condition be established. Biological effects-based monitoring studies should therefore be employed seasonally to potentially highlight 'windows of sensitivity' to contaminant impact.

Dissanayake, Awantha; Galloway, Tamara S.; Jones, Malcolm B.

2011-07-01

78

Four Corners, Southwest United States  

Science.gov (United States)

This MODIS true-color image is centered on the Four Corners region in the Southwest United States. Recognizable features include the forest-covered Rocky Mountains, which still have snow-covered peaks, running through Colorado and into New Mexico. To the west of Colorado is Utah, where the Great Salt Lake can be seen at the upper left. The Colorado Plateau, with its salmon-colored rocks, extends south from Utah into Arizona. The Grand Canyon of the Colorado River cuts westward through the mountains in northern Arizona. Credit: Jacques Descloitres, MODIS Land Rapid Response Team

2002-01-01

79

75 FR 61790 - Capital Southwest Corporation; Notice of Application  

Science.gov (United States)

...5. Capital Southwest further states that the Plan will not unduly complicate Capital Southwest's structure because equity-based compensation...commonly known to investors. Capital Southwest notes that the...

2010-10-06

80

Application of cluster analysis to the geochemistry zonation of the estuary waters in the Tinto and Odiel rivers (Huelva, Spain).  

Science.gov (United States)

The combination of acid water from mines, industrial effluents and sea water plays a determining role in the evolutionary process of the chemical makeup of the water in the estuary of the Tinto and Odiel rivers. This estuary is in the southwest of the Iberian Peninsula and is one of the estuarine systems on the northwest coast of the Gulf of Cádiz. From the statistical treatment of data obtained by analyzing samples of water from this system, which is affected by industrial and mining pollution processes, we can see how the sampling points studied form two large groups depending on whether they receive tidal or fluvial influences. Fluvial input contributes acid water with high concentrations of heavy metal, whereas industrial effluents are responsible for the presence of phosphates, silica and other nutrients. The estuarine system of the Tinto and Odiel Rivers can be divided into three areas--the Tinto estuary, the Odiel estuary and the area of confluence--based on the physical--chemical characteristics of the water. PMID:12901168

Grande, José Antonio; Borrego, José; de la Torre, Maria Luisa; Sáinz, A

2003-06-01

81

75 FR 63469 - Notice of Staff Attendance at Southwest Power Pool Regional State Committee Meeting and Southwest...  

Science.gov (United States)

...Attendance at Southwest Power Pool Regional State Committee Meeting and Southwest Power Pool Board of Directors Meeting...meetings of the Southwest Power Pool, Inc. (SPP) Regional State Committee, and SPP Board...

2010-10-15

82

75 FR 19964 - Notice of Staff Attendance at Southwest Power Pool Regional State Committee Meeting and Southwest...  

Science.gov (United States)

...Attendance at Southwest Power Pool Regional State Committee Meeting and Southwest Power Pool Board of Directors Meeting...meetings of the Southwest Power Pool, Inc. (SPP) Regional State Committee, and SPP Board...

2010-04-16

83

75 FR 41857 - Notice of Staff Attendance at Southwest Power Pool Regional State Committee Meeting and Southwest...  

Science.gov (United States)

...Attendance at Southwest Power Pool Regional State Committee Meeting and Southwest Power Pool Board of Directors Meeting...meetings of the Southwest Power Pool, Inc. (SPP) Regional State Committee, and SPP Board...

2010-07-19

84

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

85

Mercury sources and transformations in a man-perturbed tidal estuary; the Sinnamary Estuary, French Guiana  

OpenAIRE

The distribution, partition and speciation of mercury (Hg) were studied along the redox gradient of an anthropogenically perturbed tropical estuary, the Sinnamary Estuary in French Guiana. This system is a partially mixed estuary characterized by an anoxic freshwater end-member, while the marine end member consists of the Amazon Plume. The set up of an artificial oxygenation system in the anoxic freshwater end-member generates sharp gradients of major chemical species (iron, sulfides, etc.) c...

Muresan, B.; Cossa, Daniel; Coquery, M.; Richard, S.

2008-01-01

86

Erosion - Deposition in Hooghly Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available An attempt has been made to give an overall idea of erosion-deposition at theBalari-Haldia-Gangra reach of the Hooghly estuary in India. The sediment transport relationships developed by van Rijn and AcKers- White have been tried. Calculation of bed-load transport has beenmade based on'bed material sizes, flow conditions, depth and width of the channels, during 1993-97 Comparison of the results indicates the discrepancies between calculated and observed quantum of deposition/erosion to the extent of 0.6 to 0 :8 times in case ofvan Rijn ' sequation and 0.8 to 1.8 times incase of Ackers-White's model. Results sugges  that the Haldia-Balari channel is deteriorating due toaccumulation of sediment.

T. Sanyal

2013-04-01

87

CNP Project: Southwest American Indian Collaborative Network  

Science.gov (United States)

The Inter Tribal Council of Arizona1 established the Southwest American Indian Collaborative Network (SAICN) to eliminate cancer health disparities among American Indians. Core partners in the project represent both local and regional programs and activities.

88

A trophic model for the Danshuei River Estuary, a hypoxic estuary in northern Taiwan.  

Science.gov (United States)

The estuary of the Danshuei River, a hypoxic subtropical estuary, receives a high rate of untreated sewage effluent. The Ecopath with Ecosim software system was used to construct a mass-balanced trophic model for the estuary, and network analysis was used to characterize the structure and matter flow in the food web. The estuary model was comprised of 16 compartments, and the trophic levels varied from 1.0 for primary producers and detritus to 3.0 for carnivorous and piscivorous fishes. The large organic nutrient loading from the upper reaches has resulted in detritivory being more important than herbivory in the food web. The food-chain length of the estuary was relatively short when compared with other tropical/subtropical coastal systems. The shortness of food-chain length in the estuary could be attributed to the low biomass of the top predators. Consequently, the trophic efficiencies declined sharply for higher trophic levels due to low fractions of flows to the top predators and then high fractions to detritus. The low biomass of the top predators in the estuary was likely subject to over-exploitation and/or hypoxic water. Summation of individual rate measurements for primary production and respiration yielded an estimate of -1791 g WW m(-2) year(-1), or -95 g C m(-2) year(-1), suggesting a heterotrophic ecosystem, which implies that more organic matter was consumed than was produced in the estuary. PMID:17826803

Lin, Hsing-Juh; Shao, Kwang-Tsao; Jan, Rong-Quen; Hsieh, Hwey-Lian; Chen, Chang-Po; Hsieh, Li-Yung; Hsiao, Yi-Ting

2007-11-01

89

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  

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.

LAMBERT P.

2003-07-01

90

Environmental flow assessments for transformed estuaries  

Science.gov (United States)

Here, we propose an approach to environmental flow assessment that considers spatial pattern variations in potential habitats affected by river discharges and tidal currents in estuaries. The approach comprises four steps: identifying and simulating the distributions of critical environmental factors for habitats of typical species in an estuary; mapping of suitable habitats based on spatial distributions of the Habitat Suitability Index (HSI) and adopting the habitat aggregation index to understand fragmentation of potential suitable habitats; defining variations in water requirements for a certain species using trade-off analysis for different protection objectives; and recommending environmental flows in the estuary considering the compatibility and conflict of freshwater requirements for different species. This approach was tested using a case study in the Yellow River Estuary. Recommended environmental flows were determined by incorporating the requirements of four types of species into the assessments. Greater variability in freshwater inflows could be incorporated into the recommended environmental flows considering the adaptation of potential suitable habitats with variations in the flow regime. Environmental flow allocations should be conducted in conjunction with land use conflict management in estuaries. Based on the results presented here, the proposed approach offers flexible assessment of environmental flow for aquatic ecosystems that may be subject to future change.

Sun, Tao; Zhang, Heyue; Yang, Zhifeng; Yang, Wei

2015-01-01

91

Factors controlling the temporal and spatial variations in Synechococcus abundance in a monsoonal estuary.  

Science.gov (United States)

Temporal and spatial variations in Synechococcus abundance were investigated over an annual cycle (February'10-January'11) along a salinity gradient (0-35) in the tropical Zuari estuary, influenced by south-west monsoons. Synechococcus exhibited salinity preferences with phycoerythrin-rich cells at salinities >2 (Synechococcus-PEI), >20 (Synechococcus-PEII) and stratification during monsoon caused Synechococcus group segregation in the surface and near-bottom waters. During monsoon-break and non-monsoon period stabilized waters, increased salinity, temperature, solar radiation and low rainfall favored high Synechococcus abundance whereas unstable waters, increased turbidity and low solar radiation during active monsoon lowered abundance. SYN-PC positively co-related with nitrate and phosphate and SYN-PEI with phosphate. Synechococcus contribution to phytoplankton carbon biomass ranged from 9 to 29%. In monsoonal estuaries, rainfall intensity regulates freshwater runoff which modulates the estuarine environment, creating temporal-spatial niche segregation of Synechococcus groups thereby serving as indicator organisms of the estuarine hydrodynamics. PMID:24094891

K M, Rajaneesh; Mitbavkar, Smita

2013-12-01

92

Modeling tidal distortion in the Ogeechee Estuary  

Science.gov (United States)

A 3D numerical model is used to simulate the distortion of tidal hydrodynamics in the Ogeechee Estuary, GA. The Ogeechee, like many estuaries found in the Southeastern US, consists of shallow channel networks and extensive intertidal storage in the form of wetlands. Such features are known to induce non-linear overtide generation and significant tidal distortion, otherwise known as tidal stage asymmetry. Simulations are run with varying parameters to assess their effects on modeling tidal distortion for the Ogeechee Estuary: bottom friction coefficients, enhanced wetland friction coefficients, and tidal flat elevations. To succinctly quantify the degree of distortion across the domain, the statistical parameters of skewness and asymmetry are calculated for time series of water surface heights and channel volume fluxes. The intertidal storage causes the peak flood flux to occur later and the peak ebb flux to occur earlier, thereby resulting in positive asymmetry for the volume flux for the full estuary. However, ebb dominance is a localized feature and varies throughout the estuary. Increasing the intertidal storage by lowering wetland elevation enhances the effects on high tide and volume flux magnitudes, decreasing the ebb-dominance and volume flux asymmetry typically associated with intertidal storage thereby indicating the importance of the wetland elevation over the total storage volume. Increased channel bottom friction reduces ebb-dominance by extending the duration of the falling tide. More interestingly, increased wetland friction reduces the influence of wetland intertidal storage on tidal distortion. The model suggests an increase in wetland friction does little to dampen wave propagation at high tide but rather impedes the lateral flooding of wetlands, reducing ebb dominance. Tidal flat elevation has the largest impact on distortion for the Ogeechee Estuary whereas enhanced wetland and bottom frictional influences on distortion are small, albeit not insignificant.

Bruder, Brittany; Bomminayuni, Sandeep; Haas, Kevin; Stoesser, Thorsten

2014-10-01

93

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)

94

SOUTHWEST REGIONAL PARTNERSHIP ON CARBON SEQUESTRATION  

Energy Technology Data Exchange (ETDEWEB)

The Southwest Partnership Region includes six whole states, including Arizona, Colorado, Kansas, New Mexico, Oklahoma, and Utah, roughly one-third of Texas, and significant portions of adjacent states. The 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. The main objective of the Southwest Partnership project is to achieve an 18% reduction in carbon intensity by 2012. The Partnership made great progress in this first year. Action plans for possible Phase II carbon sequestration pilot tests in the region are almost finished, including both technical and non-technical aspects necessary for developing and carrying out these pilot tests. All partners in the Partnership are taking an active role in evaluating and ranking optimum sites and technologies for capture and storage of CO{sub 2} in the Southwest Region. We are identifying potential gaps in all aspects of potential sequestration deployment issues.

Brian McPherson; Rick Allis; Barry Biediger; Joel Brown; Jim Cappa; George Guthrie; Richard Hughes; Eugene Kim; Robert Lee; Dennis Leppin; Charles Mankin; Orman Paananen; Rajesh Pawar; Tarla Peterson; Steve Rauzi; Jerry Stuth; Genevieve Young

2004-11-01

95

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

96

77 FR 5493 - Southwest Fisheries Science Center; Public Meeting  

Science.gov (United States)

...COAST methods review will be held at the Southwest Fisheries Science Center; Southwest Fisheries Science Center, 3333 North Torrey Pines Court, La Jolla, CA 92037-1023; (858) 546-7000. FOR FURTHER INFORMATION CONTACT: Mr. Dale Sweetnam,...

2012-02-03

97

A sensitivity analysis of low salinity habitats simulated by a hydrodynamic model in the Manatee River estuary in Florida, USA  

Science.gov (United States)

This paper presents a sensitivity study of simulated availability of low salinity habitats by a hydrodynamic model for the Manatee River estuary located in the southwest portion of the Florida peninsula. The purpose of the modeling study was to establish a regulatory minimum freshwater flow rate required to prevent the estuarine ecosystem from significant harm. The model used in the study was a multi-block model that dynamically couples a three-dimensional (3D) hydrodynamic model with a laterally averaged (2DV) hydrodynamic model. The model was calibrated and verified against measured real-time data of surface elevation and salinity at five stations during March 2005-July 2006. The calibrated model was then used to conduct a series of scenario runs to investigate effects of the flow reduction on salinity distributions in the Manatee River estuary. Based on simulated salinity distribution in the estuary, water volumes, bottom areas and shoreline lengths for salinity less than certain predefined values were calculated and analyzed to help establish the minimum freshwater flow rate for the estuarine system. The sensitivity analysis conducted during the modeling study for the Manatee River estuary examined effects of the bottom roughness, ambient vertical eddy viscosity/diffusivity, horizontal eddy viscosity/diffusivity, and ungauged flow on the model results and identified the relative importance of these model parameters (input data) to the outcome of the availability of low salinity habitats. It is found that the ambient vertical eddy viscosity/diffusivity is the most influential factor controlling the model outcome, while the horizontal eddy viscosity/diffusivity is the least influential one.

Chen, XinJian

2012-06-01

98

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)

99

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

100

Monsoon-induced changes in the size-fractionated phytoplankton biomass and production rate in the estuarine and coastal waters of southwest coast of India.  

Science.gov (United States)

Changes in the autotrophic pico- (0.2-2 microm), nano- (2-20 microm), and microplankton (>20 microm) biomass (chlorophyll a) and primary production were measured in the estuarine and coastal waters off Cochin, southwest coast of India during the onset and establishment of a monsoon. During this period, the estuary was dominated by nutrient-rich freshwater, whereas the coastal waters were characterized with higher salinity values (>30 psu) and less nutrients. The average surface chlorophyll a concentrations and primary production rates were higher in the estuary (average 13.7 mg m(-3) and 432 mgC m(-3) day(-1)) as compared to the coastal waters (5.3 mg m(-3) and 224 mgC m(-3) day(-1)). The nanoplankton community formed the major fraction of chlorophyll a and primary production, both in the estuary (average 85 +/- SD 8.3% and 81.2 +/- SD 3.2%) and the coastal waters (average 73.2 +/- SD 17.2% and 81.9 +/- 15.7%). Nanoplankton had the maximum photosynthetic efficiency in the coastal waters (average 4.8 +/- SD 3.9 mgC mgChl a m(-3) h(-1)), whereas in the estuary, the microplankton had higher photosynthetic efficiency (average 7.4 +/- 7 mgC mgChl a m(-3) h(-1)). The heavy cloud cover and increased water column turbidity not only limit the growth of large-sized phytoplankton in the Cochin estuary and coastal waters but also support the proliferation of nanoplankton community during the monsoon season, even though large variation in nanoplankton chlorophyll a and production exists between these two areas. PMID:19484365

Madhu, N V; Jyothibabu, R; Balachandran, K K

2010-07-01

101

75 FR 17382 - Small Takes of Marine Mammals Incidental to Specified Activities; Russian River Estuary Water...  

Science.gov (United States)

...Specified Activities; Russian River Estuary Water Level Management Activities, California...Authorization (IHA) to the Sonoma County Water Agency (herein after ``Agency...incidental to Russian River Estuary (Estuary) water level management and monitoring...

2010-04-06

102

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

Science.gov (United States)

...Climate Ready Estuaries Program: A Novel Approach Using Expert Judgment, Volume I: Results...Climate Ready Estuaries Program: A Novel Approach Using Expert Judgment, Volume I: Results...Climate Ready Estuaries Program: A Novel Approach Using Expert Judgment, Volume II:...

2011-09-08

103

Second International Symposium on the Biogeochemistry of Model Estuaries: Estuarine processes in global change. Final report  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes estuary events discussed at the symposium on biogeochemistry. Topics include; sedimentation, salinity, inputs and outputs of the estuary, effects of global change, and the need for effective sampling and modeling of estuaries.

Windom, H.L.

1991-12-31

104

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

105

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

Science.gov (United States)

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.

Shivaprasad, A.; Vinita, J.; Revichandran, C.; Reny, P. D.; Deepak, M. P.; Muraleedharan, K. R.; Naveen Kumar, K. R.

2013-01-01

106

Along-estuary dissolved oxygen variability in the Coos Bay estuary, Oregon, USA  

Science.gov (United States)

Hypoxia and anoxia are direct threats to the ecosystem and economic health of coastal communities. In estuaries, oceanic and terrestrial systems merge, making their relative influences on water properties such as dissolved oxygen (DO) difficult to tease apart. Recent studies show evidence for low DO conditions occurring on the Oregon shelf during the dry season on temporal and spatial scales unprecedented in the historic record. There is evidence now, too, showing that estuarine hypoxia, historically observed as a product mainly of terrestrial influences, is occurring due to the shifting properties of oceanic inputs. We report here on data collected in the Coos Bay estuary located on the southern Oregon coast, to quantify past and present DO levels to determine if hypoxia is occurring. We use monthly along-estuary sections of temperature, salinity, dissolved oxygen, turbidity, and fluorescence to examine the seasonal cycle of water properties. This data will be put into temporal context through analysis of historic data collected by state, federal, and private organizations. The goal is to link patterns in DO variation to the temporal and spatial circulation of water within the estuary. We show a significant along-estuary gradient in DO and discuss the variability of this gradient in time, over both seasonal and interannual scales.

O'Neill, M.; Sutherland, D.

2013-12-01

107

Small estuary, big port - progress in the management of the Stour-Orwell Estuary system  

Science.gov (United States)

Management of port development is increasingly challenging because of the competitive requirement for deeper channels and because of the need to preserve important coastal wetlands which function as both habitat and flood defence. This paper describes the management of the Stour/Orwell Estuary system, Eastern England, an estuary system which has experienced considerable development and morphological change. The estuary is internationally important for its wetland bird populations and the intertidal areas of the estuary system are protected under European legislation. It is also the location of the Port of Felixstowe. In 1998/2000 the approach channel to the Port of Felixstowe was deepened from -12.5 mCD to -14.5 mCD. This paper describes the effects of the approach channel deepening, the approach taken to identifying the potential impact to intertidal habitat resulting from the deepening, the sediment recycling implemented as mitigation to prevent increased loss of habitat and the subsequent response of the estuary system to this intervention.

Spearman, Jeremy; Baugh, John; Feates, Nigel; Dearnaley, Mike; Eccles, Dan

2014-10-01

108

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

109

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

110

Salt intrusion, tides and mixing in multi-channel estuaries:  

OpenAIRE

Multi-channel estuaries, such as the Mekong Delta in Vietnam and the Scheldt in the Netherlands, have characteristics of both the river and the sea, forming a unique environment influenced by tidal movements of the sea and freshwater flow of the river. This study addresses a number of knowledge gaps in multi-channel estuaries by developing a predictive analytical approach for salinity intrusion and discharge estimate in multi-channel estuaries. The new approach agrees well with 1-D hydrodynam...

Nguyen, A. D.

2008-01-01

111

Cyanobacteria and macroalgae in ecosystem of the Neva estuary  

OpenAIRE

The Baltic Sea and Neva estuary are plagued by coastal eutrophication. In order to estimate the scale of the problem, quantitative estimates of phytoplankton and macroalgal mats were determined in the Neva estuary. Long-term monitoring (1982–2009) of phytoplankton showed changes in its species composition and abundance. Summer phytoplankton biomass increased significantly in the 1990s, with concomitant changes in species composition, despite a decline of nutrients in the Neva estuary. The c...

Nikulina V. N.; Gubelit Y. I.

2011-01-01

112

Antibiotic Resistance of Escherichia coli Serotypes from Cochin Estuary  

OpenAIRE

This study aimed at detecting the prevalence of antibiotic-resistant serotypes of Escherichia coli in Cochin estuary, India. E. coli strains were isolated during the period January 2010–December 2011 from five different stations set at Cochin estuary. Water samples from five different stations in Cochin estuary were collected on a monthly basis for a period of two years. Isolates were serotyped, antibiogram-phenotyped for twelve antimicrobial agents, and genotyped by polymerase chain reacti...

Sukumaran, Divya P.; Srinivasan Durairaj; Mohamed Hatha Abdulla

2012-01-01

113

Analytical solution for salt intrusion in the Yangtze Estuary, China  

Science.gov (United States)

The Yangtze Estuary is one of the largest estuaries in the world, with three-order bifurcations and four outlets into the sea. In recent years salt intrusion has been given more attention due to the increase in its level and frequency. In this paper, for the first time, an analytical model is applied to the Yangtze Estuary to analyze the salt intrusion. This model has been tested in 18 estuaries in the world. Originally it was derived for single channel estuaries, which makes the application to the Yangtze Estuary challenging. The results show that this model can describe the salt intrusion from the sea in the Yangtze Estuary very well, with a good fit between computed salinity and measurements. The good results for the Combined South Branch and Combined South Channel indicate that the multi-channel estuary system functions as an entity. Additionally, this model can be used to estimate the river discharge distribution over the separate channels. Further work is needed based on more detailed salinity measurements and accurate bathymetry, particularly for the North Branch of the estuary system.

Zhang, Erfeng; Savenije, Hubert H. G.; Wu, Hui; Kong, Yazhen; Zhu, Jianrong

2011-03-01

114

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

115

Eutrophication in a western Australian estuary  

OpenAIRE

Two large, shallow (2m) coastal lagoons of south western Australia have become eutrophic during the last 20 years. Abundant benthic green algae (principally Cladophora aff. albida and Chaetomorpha spp.) accumulate on the shores of one and there are dense phytoplankton blooms of the blue-green Nodularia spumigena in the other. The eutrophy is caused by a great increase in the amount of nutrients, especially phosphorus (phosphatic fertilizers). Tidal range is small and exchage between estuary a...

Hodgkin, E. P.; Birch, P. B.

1982-01-01

116

Columbia River Estuary Ecosystem Classification Cultural Features  

Science.gov (United States)

Estuarine ecosystems are controlled by a variety of processes that operate at multiple spatial and temporal scales. Understanding the hierarchical nature of these processes will aid in prioritization of restoration efforts. This hierarchical Columbia River Estuary Ecosystem Classification (henceforth "Classification") of the Columbia River estuary is a spatial database of the tidally-influenced reaches of the lower Columbia River, the tidally affected parts of its tributaries, and the landforms that make up their floodplains for the 230 kilometers between the Pacific Ocean and Bonneville Dam. This work is a collaborative effort between University of Washington School of Aquatic and Fishery Sciences (henceforth "UW"), U.S. Geological Survey (henceforth "USGS"), and the Lower Columbia Estuary Partnership (henceforth "EP"). Consideration of geomorphologic processes will improve the understanding of controlling physical factors that drive ecosystem evolution along the tidal Columbia River. The mapping extent is the interpreted Holocene geologic floodplain of the tidal Columbia River and its tributaries to the estimated head of tide. Cultural features within the Holocene floodplain were mapped by visual interpretation of Light Detection and Ranging (LiDAR) topography supplemented with aerial photographs and U.S. Geological Survey topographic maps. Mapped cultural features are classified as to their purpose when constructed. Because features were drawn based on LiDAR topography, only features with a significant topographic expression are mapped.

Cannon, Charles M.; Ramirez, Mary F.; Burke, Jennifer L.; Simenstad, Charles A.; O'Connor, Jim E.; Marcoe, Keith

2012-01-01

117

Nutrient budgets for large Chinese estuaries  

Science.gov (United States)

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 regeneration, open ocean and atmospheric deposition.

Liu, S. M.; Hong, G.-H.; Zhang, J.; Ye, X. W.; Jiang, X. L.

2009-10-01

118

A 3-D crustal velocity structure across the Variscides of southwest Ireland  

Science.gov (United States)

In the VARNET-96 experiment three seismic refraction profiles were acquired to examine the crustal structure in the south-west of Ireland. The shotpoint geometry allowed for both in-line and off-line fan shot recordings on the three profiles. Results of 3-D inversion modelling illustrate that there is pervasive lateral heterogeneity of the sedimentary and crustal velocity structure south of the Shannon Estuary. Palaeozoic strata at the south coast are about 5-6 km thick associated with the sedimentary infill of the Munster and South Munster Basins. To the north, shallow upper crust in the vicinity of the Killarney-Mallow Fault Zone is followed by a 3-4 km thick sedimentary succession in the Dingle-Shannon Basin. A zone of high-velocity upper crust (6.4-6.6 km/s) beneath the South Munster Basin correlates with a gravity high between the Kenmare-Killarney and the Leinster Granite gravity lows. Other high-velocity zones beneath Dingle Bay and the Kenmare River region may be associated with the deep traces of the Killarney-Mallow Fault Zone and the Cork-Kenmare Line. The 3-D velocity model was taken as a basis for the computation of PmP reflected arrivals from the crust-mantle boundary. The Moho depth varies from 28-29 km at the south coast to 32-33 km beneath the Dingle-Shannon Basin. Pervasive Variscan deformation appears to be confined to the sedimentary and upper crustal structure thus supporting a thin-skinned tectonic model for Variscan deformation. Deep-crustal variations only occur where they can be correlated with major tectonic features such as the Caledonian Iapetus Suture near the Shannon Estuary. The shallowing of the Moho towards the coast may result from Mesozoic crustal extension in the adjacent offshore sedimentary basins.

Landes, M.; Readman, P. W.; O'Reilly, B. M.; Shannon, P. M.

2003-04-01

119

Freshwater, tidal and wave influences on a small estuary  

Science.gov (United States)

Observations are presented of water levels, currents, salinity, turbidity, sediment grain sizes and sediment transport in the Devonshire Avon Estuary, UK, in order to improve knowledge of freshwater, wave and tidal influences on small, strongly tidal ría estuaries. A large reduction in tidal range occurred progressing from the coastal zone to the upper estuary that was mainly a consequence of rising bed and river water levels. The spring-neap cycle also had an influence on the reduction in tidal range along the length of the estuary. Surface gravity waves were completely dissipated propagating into the estuarine channel from the coastal zone, and despite strong wave-induced resuspension, suspended sediment was not transported into the lower estuary in observable amounts during the ensuing flood tide, indicating that the wave-suspended material was too coarse to remain in suspension once transported away from the surf zone. Turbidity in the lower estuary was relatively low during low runoff summer conditions and had largest values over low water, when turbid waters from farther up-estuary had been transported there. Strong resuspension events occurred at peak currents in the upper estuary during summer, reflecting the presence of finer-grained sediment sources. Turbidity was similar but greater in the lower estuary during high runoff winter conditions and strong resuspension occurred at peak currents, indicating an easily erodible, nearby sediment source, due to down-estuary movement and relocation of finer sediment over the winter. A large shoal in the lower estuary exhibited a consistent pattern of accretion/erosion during the high runoff months of late autumn and winter to spring that also was qualitatively consistent with sediment transport modelling and implied: (a), erosion from the up-estuary limit of the shoal with (b), down-estuary bed-load and suspended-load transport that accreted the centre and down-estuary limit of the shoal until (c), a diminished supply led to erosion via continued down-estuary transport from the shoal centre.

Uncles, R. J.; Stephens, J. A.; Harris, C.

2014-10-01

120

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

Science.gov (United States)

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 methodology 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. PMID:22801380

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

2012-09-01

121

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

Energy Technology Data Exchange (ETDEWEB)

A reconnaissance study has been made on the distribution of {sup 238}U, {sup 234}U, {sup 232}Th and {sup 230}Th 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 {sup 238}U/Al and {sup 232}Th/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 {sup 232}Th 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 {mu}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 26.3x10{sup 6} g/yr to the Arabian Sea which is about 2% of the flux from the Himalayan rivers to the Bay of Bengal.

Balakrishna, K.; Shankar, R. E-mail: rshankar_1@yahoo.com; Sarin, M.M.; Manjunatha, B.R

2001-06-01

122

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

Science.gov (United States)

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 microg/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 26.3 x 10(6) g/yr to the Arabian Sea which is about 2% of the flux from the Himalayan rivers to the Bay of Bengal. PMID:11499608

Balakrishna, K; Shankar, R; Sarin, M M; Manjunatha, B R

2001-01-01

123

[Distribution and source of particulate organic carbon and particulate nitrogen in the Yangtze River Estuary in summer 2012].  

Science.gov (United States)

Based on the data from the cruise carried out in August 2012 in the Yangtze River Estuary and its adjacent waters, spatial distributions of particulate organic carbon (POC), particulate nitrogen (PN) and their relationships with environmental factors were studied, and the source of POC and the contribution of phytoplankton to POC were analyzed combined with n (C)/n (N) ratio and chlorophyll a (Chl a) in the Yangtze River Estuary in summer 2012. The results showed that the concentrations of POC in the Yangtze River Estuary ranged from 0.68 mg x L(-1) to 34.80 mg x L(-1) in summer and the average content was 3.74 mg x L(-1), and PN contents varied between 0.03 mg x L(-1) and 9.13 mg x L(-1) with an average value of 0.57 mg x L(-1). Both of them presented that the concentrations in bottom layers were higher than those in the surface. POC and PN as well as total suspended matter (TSM) showed a extremel similar horizontal distribution trend that the highest values appeared in the near of the mouth and southwest of the survey waters, and decreased rapidly as toward the open seas, both of them showed higher contents in coastal zones and lower in outer sea. There was a fairly good positive linear relationship between POC and PN, which indicated that they had the same source. POC and PN expressed significantly positive correlations with TSM and chemical oxygen demand (COD), but showed relatively weak correlations with salinit and chlorophyll a, which demonstrated that terrestrial inputs had a strong influence on the distribution of POC and PN, and phytoplankton production was not the major source of organic matters in the Yangtze River Estuary. Both the n (C)/n (N) ratio and POC/Chl a analysis showed that the main source of POC was terrestrial inputs, and organic debris was the main existence form of POC. Quantitative analysis showed the biomass of phytoplankton only made an average of 2.54% contribution to POC in the Yangtze Rive Estuary in summer and non-living POC occupied the overwhelming advantage. PMID:25244833

Xing, Jian-Wei; Xian, Wei-Wei; Sheng, Xiu-Zhen

2014-07-01

124

Macroalgae, pore water sulfides and eelgrass in Yaquina estuary, Oregon  

Science.gov (United States)

The hypothesis that relatively high nutrients in estuaries of the Pacific Northwest (PNW) can lead to eutrophication and degradation of critical eelgrass habitat was examined. Yaquina estuary was surveyed for cover and above-ground biomass of benthic macroalgae (Ulva spp.) and n...

125

WATER QUALITY MODELING IN THE RIO CHONE ESTUARY  

Science.gov (United States)

Water quality in the Rio Chone Estuary, a seasonally inverse, tropical estuary, in Ecuador was characterized by modeling the distribution of biochemical oxygen demand (BOD) and dissolved inorganic nitrogen (DIN) within the water column. These two variables are modeled using modif...

126

Nutrients, hypoxia and Mass Fishkill events in Tapi Estuary, India  

Science.gov (United States)

From 1983 to 2011, dissolved oxygen (DO) conditions in the Tapi Estuary changed from normoxic to hypoxic due to increased and untreated discharge of sewage. Both tidal and day-night variations of DO were best explained by hydrographic factors, sewage pollution and phytoplankton dynamics in upper, middle, lower estuary and the coastal water. Hypoxia/anoxia was associated with low-flow periods due to riverine restrictions and changing in climatic condition. The upper Tapi Estuary becomes anoxic during summer irrespective of tide while the middle estuary was anoxic (stratification, sewage discharge and flushing accounted for differences in DO. Because of high nutrient concentrations (maximum NO3--N 103.1, NO2--N 26.0, NH4+-N 104.0 and PO43--P 99.0 ?mol l-1), the lower estuary remains DO deficient between 2.0 and 5.0 mg O2 l-1, most of the time. The environmental condition of Tapi Estuary has impacted the coastal water of the Arabian Sea in recent years with fish kills attributed to its hypoxic/anoxic condition. Enhanced concentrations of nutrients and organic matter from indiscriminate discharge of sewage into the Tapi Estuary and restricted flushing as a result of construction of a series of dams in the catchment area of the estuary are the primary factors that have lead to the development of hypoxia.

Ram, Anirudh; Jaiswar, Jiyalal Ram M.; Rokade, M. A.; Bharti, S.; Vishwasrao, C.; Majithiya, D.

2014-07-01

127

Three dimensional water quality modeling of a shallow subtropical estuary.  

Science.gov (United States)

Knowledge of estuarine hydrodynamics and water quality comes mostly from studies of large estuarine systems. The processes affecting algae, nutrients, and dissolved oxygen (DO) in small and shallow subtropical estuaries are relatively less studied. This paper documents the development, calibration, and verification of a three dimensional (3D) water quality model for the St. Lucie Estuary (SLE), a small and shallow estuary located on the east coast of south Florida. The water quality model is calibrated and verified using two years of measured data. Statistical analyses indicate that the model is capable of reproducing key water quality characteristics of the estuary within an acceptable range of accuracy. The calibrated model is further applied to study hydrodynamic and eutrophication processes in the estuary. Modeling results reveal that high algae concentrations in the estuary are likely caused by excessive nutrient and algae supplies in freshwater inflows. While algal blooms may lead to reduced DO concentrations near the bottom of the waterbody, this study indicates that stratification and circulation induced by freshwater inflows may also contribute significantly to bottom water hypoxia in the estuary. It is also found that high freshwater inflows from one of the tributaries can change the circulation pattern and nutrient loading, thereby impacting water quality conditions of the entire estuary. Restoration plans for the SLE ecosystem need to consider both a reduction of nutrient loading and regulation of the freshwater discharge pattern. PMID:23122270

Wan, Yongshan; Ji, Zhen-Gang; Shen, Jian; Hu, Guangdou; Sun, Detong

2012-12-01

128

Metal behaviour in an estuary polluted by acid mine drainage: the role of particulate matter  

International Nuclear Information System (INIS)

Particle sorption/de-sorption did not play a major role in metal dynamics in the water column of an estuary in Spain. - The concentrations of dissolved and suspended particulate Cd, Cu and Zn have been determined in water samples obtained during two axial transects of the Rio Tinto-Huelva Ria system in south-west Spain, which is severely impacted by acid mine drainage. Although the metal concentrations in both phases were elevated, dissolved metals were dominant and, in the upper estuary, constituted >99% of total metal in the water column. Dissolved metals behaved non-conservatively on each transect, with maximum concentrations in the low salinity region. There was no evidence of metal adsorption within the turbidity maximum zone, despite the high specific surface areas of resuspending particles. Measurements of electrophoretic mobility showed that the suspended particulate matter (SPM) had a positive surface charge in the salinity range 0-4, where the waters had a pH<3. Desorption experiments were carried out in which SPM from the turbidity maximum zone was resuspended in coastal seawater. The desorption of the metals was monitored for 24 h, using anodic stripping voltammetry (ASV) to detect the variation in total dissolved Cd, Cu and Zn and the species of Cu and Zn. Total dissolved Cd concentrations doubled during the incubation period, whereas the concentration of total dissolved Cu declined and that of Zn remained rather constant. The ASV-labile fraction of dissoconstant. The ASV-labile fraction of dissolved Cu and Zn showed an initial sharp release followed by a slower uptake. However, desorption was shown to be a minor source of dissolved metals and made little contribution to the non-conservative behaviour in the low salinity zone. The results are used to predict the effects of acid mine drainage on estuarine ecology

129

The behavior of trace metals in the Geum Estuary, Korea  

Energy Technology Data Exchange (ETDEWEB)

The distributions of trace metals in the Geum Estuary of western Korea were studied with regard to changes in other estuarine chemical parameters. Dissolved oxygen, pH, and alkalinity increased with increasing salinity. Dissolved aluminum concentrations increased at low salinities and were perhaps influenced by the solubility of particulate aluminosilicate phases. Iron, manganese, cobalt, and zinc are removed from solution in the low salinity end of the estuary. Cobalt and nickel have mid-estuary concentration maxima that may be due to an anthropogenic source. Cadmium, copper, lead, and zinc concentrations also increased in the estuary, possibly as th result of remobilization in the sediments. Cadmium increases are also linked to remineralization from tidal flat sediments in the outer estuary. The source of an increase in dissolved lead at low salinity is unclear, but may be due to release from particles.

Byrd, J.T.; Smith, R.G.; Windom, H.L. (Skidaway Inst. of Oceanography, Savannah, GA (United States)); Lee, Kwang, W. (Hanyang Univ. Ansan, Kyunggi (Korea)); Lee, Dong, S. (Korea Ocean Research and Development Inst., Ansan, Kyunggi (Korea))

1991-05-01

130

Polycyclic aromatic hydrocarbons in coastal sediments of southwest Taiwan: an appraisal of diagnostic ratios in source recognition.  

Science.gov (United States)

Fifty-seven surface sediment samples were collected from the coast of southwest Taiwan and analyzed for polycyclic aromatic hydrocarbons (PAHs). Concentrations of total PAHs (28 PAH compounds) ranged from 15 to 907 ng g(-1) dry weight. Diagnostic ratios showed that PAHs in the sediments of the Gaoping estuary were predominantly of petroleum origin, whereas sediments from the Kaohsiung coast contained principally combustion-derived PAHs. Principal component analysis indicated that emissions from automobiles and coal burning were the main sources of combustion-derived PAHs. The relatively high ratios of perylene/penta-aromatic PAH isomers in sediments from the Tainan coast and some off-shore stations on the Kaohsiung coast suggest a significant diagenetic PAH contribution. The study shows that certain diagnostic ratios are useful and sensitive in delineating the distribution of PAHs from specific sources in southwest Taiwan. The phenanthrene/anthracene ratio is a better indicator than the methylphenanthrenes/phenanthrene ratio for tracing petrogenic PAHs, and the benzo(a)anthracene/chrysene and indeno(1,2,3-c,d)pyrene/benzo(g,h,i)perylene ratios are more specific than the benzo(a)pyrene/benzo(e)pyrene and benzo(b)fluoranthcene/benzo(k)fluoranthcene ratios in distinguishing PAHs from various pyrogenic sources. PMID:19181350

Jiang, Jheng-Jie; Lee, Chon-Lin; Fang, Meng-Der; Liu, James T

2009-05-01

131

Mercury sources and transformations in a man-perturbed tidal estuary: The Sinnamary Estuary, French Guiana  

Science.gov (United States)

The distribution, partition and speciation of mercury (Hg) were studied along the redox gradient of an anthropogenically perturbed tropical estuary, the Sinnamary Estuary in French Guiana. This system is a partially mixed estuary characterized by an anoxic freshwater end-member, while the marine end-member consists of the Amazon Plume. The set up of an artificial oxygenation system in the anoxic freshwater end-member generates sharp gradients of major chemical species (iron, sulfides, etc.) coupled with intense organic matter (OM) turnover. The coexistence of oxygenated waters and dissolved sulfides in an organic rich environment depicts the Upper Sinnamary Estuary (USE: part of Sinnamary Estuary under the tidal influence but upstream of the salt intrusion) as a potential site for Hg methylation. The concentrations of all mercury compounds (HgT) in the unfiltered samples (HgT UNF), in the dissolved (HgT D) and particulate (HgT P) phases of the USE average 11 ± 3, 6 ± 2 and 5 ± 3 (i.e. 600 ± 200 pmol g -1) pmol L -1, respectively. Average concentrations of monomethylmercury (MMHg) in the unfiltered (MMHg UNF), dissolved (MMHg D) and particulate (MMHg P) phases were 3.7 ± 1.0, 2.0 ± 0.9 and 1.8 ± 1.2 (i.e. 220 ± 130 pmol g -1) pmol L -1, respectively. Water oxygenation and sulfides concentrations emerged to play a critical role in controlling MMHg levels. Additionally, iron cycling, acid-base mechanisms, and redox-dependent processes were involved in the MMHg partitioning between phases. Overall, the USE constitutes a biogeochemical reactor that gathers partitioning and methylation processes. The permanent MMHg inputs from the anoxic freshwater end-member combined with the intense endogenous Hg methylation ensures high-MMHg levels in both dissolved and particulate phases. To illustrate, the USE exports 60 ± 20% more MMHg UNF than it imports: 5.5 ± 0.7 vs. 3.5 ± 1.2 kg year -1.

Muresan, B.; Cossa, D.; Coquery, M.; Richard, S.

2008-11-01

132

Carbon and nitrogen isotopic composition of suspended particulate organic matter in Zuari Estuary, west coast of India  

Science.gov (United States)

The spatio-temporal variations of the ?13C and ?15N of suspended particulate organic matter (SPOM), along with ancillary chemical and hydrographic parameters, have been examined monthly for one year (October 2010 to September 2011) at a total of seven stations to refine the understanding of SPOM sources and biogeochemical pathways in the tropical Zuari Estuary, west coast of India. The dynamic nature of C and N cycling in estuaries is reflected in the isotopic variation of SPOM as a function of space and time. The results exhibit marked seasonality, with the autochthonous component and the terrestrial component being the major SPOM sources during periods of low and high river discharges, respectively. Spatially, enrichments of ?13C and ?15N from the head (?13C = - 29.6‰, ?15N = 1.78‰, C/N = 7.09) to the mouth (?13C = - 20.9‰, ?15N = 5.77‰, C/N = 6.12) of the estuary indicate downstream reduction of terrigenous influence. The mean C:N ratios varied between 4 and 9 over the study period with low values during the monsoon, in spite of large terrestrial input, which can be attributed to microbial modification of terrestrial SPOM. A significant positive correlation of ?13C with salinity suggests the reliability of ?13C as a biogeochemical tracer for organic matter provenance. Carbon:chlorophyll plots reveal suppressed autochthonous production during the southwest monsoon which may be attributed to the rapid flushing time, light-limitation due to cloud cover and high water-column turbidity.

Bardhan, Pratirupa; Karapurkar, S. G.; Shenoy, D. M.; Kurian, S.; Sarkar, A.; Maya, M. V.; Naik, H.; Varik, S.; Naqvi, S. W. A.

2015-01-01

133

Southwest coast of Greenland and Davis Strait  

Science.gov (United States)

This true-color image was taken by MODIS as it passed over the southwest coast of Greenland (right) and the Davis Strait (center and left). The Davis Strait connects Baffin Bay to the north and the Labrador Sea to the south, and separates Greenland from Baffin Island, Canada. The Davis Strait is part of the Northwest Passage, a navigable seaway connecting the Atlantic Ocean and the Pacific Ocean. The image shows the prevailing currents in the area, with the warm water of a branch of the North Atlantic Drift flowing northward along the Greenland coast, and the cold, iceberg-filled Labrador Current flowing southward along the Baffin Island coast.

2002-01-01

134

76 FR 8730 - Desert Southwest Customer Service Region-Rate Order No. WAPA-151  

Science.gov (United States)

...Desert Southwest Customer Service Region, Western Area...the Desert Southwest Customer Service Regional Office, 615...FURTHER INFORMATION CONTACT: Mr. Jack Murray...Manager, Desert Southwest Customer Service Region, Western...

2011-02-15

135

40 CFR 81.118 - Southwest Missouri Intrastate Air Quality Control Region.  

Science.gov (United States)

...Southwest Missouri Intrastate Air Quality Control Region. 81.118 Section...PURPOSES Designation of Air Quality Control Regions § 81.118 Southwest Missouri Intrastate Air Quality Control Region. The Southwest...

2010-07-01

136

40 CFR 81.259 - Southwest Iowa Intrastate Air Quality Control Region.  

Science.gov (United States)

...Southwest Iowa Intrastate Air Quality Control Region. 81.259 Section...PURPOSES Designation of Air Quality Control Regions § 81.259 Southwest Iowa Intrastate Air Quality Control Region. The Southwest...

2010-07-01

137

Phosphorus dynamics in some coastal plain estuaries  

Energy Technology Data Exchange (ETDEWEB)

Phosphorus availability in estuaries may have a seasonal cycle with a maximum usually occurring in the summer when orthophosphate is released into oxygen depleted deep water and transported to the euphotic zone by turbulent mixing. Superimposed on the annual fluctuation of total phosphorus is the rapid turnover of orthophosphate and phosphorus monoesters in the euphotic zone. The concentrations of these materials in surface waters are similar and phosphate uptake kinetics from each type by natural phytoplankton assemblages are similar which suggests that phosphorus monoesters may be significant in phytoplankton phosphorus nutrition.

Taft, J. L.; Taylor, W. R.

1975-01-01

138

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

OpenAIRE

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 Isl...

MUHAMMAD ILYAS; SEKAR LARASHATI

2009-01-01

139

Earthquake-triggered landslides in southwest China  

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Full Text Available Southwest China is located in the southeastern margin of the Tibetan Plateau and it is a region of high seismic activity. Historically, strong earthquakes that occurred here usually generated lots of landslides and brought destructive damages. This paper introduces several earthquake-triggered landslide events in this region and describes their characteristics. Also, the historical data of earthquakes with a magnitude of 7.0 or greater, having occurred in this region, is collected and the relationship between the affected area of landslides and earthquake magnitude is analysed. Based on the study, it can be concluded that strong earthquakes, steep topography as well as fragile geological environment, are the main reasons responsible for serious landslides in southwest China. At the same time, it is found that the relationship between the area affected by landslides and the earthquake magnitude in this region are consistent with what has been obtained worldwide. Moreover, in this paper, it is seen that the size of the areas affected by landslides change enormously even under the same earthquake magnitude in the study region. While at the same tectonic place or fault belt, areas affected by landslides presented similar outline and size. This means that local geological conditions and historical earthquake background have an important influence on landslides distribution, and they should be considered when assessing earthquake-triggered landslide hazards at Grade 1 according to ISSMGE.

X. L. Chen

2012-02-01

140

Distribution and assessment of sediment toxicity in Tamaki Estuary, Auckland, New Zealand  

Science.gov (United States)

Heavy metal levels in surface sediments from Tamaki Estuary demonstrate significant up estuary increases in Cu, Pb, Zn, Cd and mud concentrations. Increased metal levels towards the head of the estuary are linked to local catchment sources reflecting the historical development, industrialisation and urbanisation of catchment areas surrounding the upper estuary. The relatively narrow constriction in the middle estuary (Panmure area), makes it susceptible to accumulation of upper estuary pollutants, since the constriction reduces circulation and extends the time required for fine waterborne sediments in the upper estuary to exchange with fresh coastal water. As a result fine fraction sediments trapped in the upper estuary facilitate capture and retention of pollutants at the head of the estuary. The increase in sandy mud poor sediments towards the mouth of the estuary is associated with generally low metal concentrations. The estuary’s geomorphic shape with a mid estuary constriction, sediment texture and mineralogy and catchment history are significant factors in understanding the overall spatial distribution of contaminants in the estuary. Bulk concentration values for Cu, Pb, Zn, and Cd in all the studied surface samples occur below ANZECC ISQG-H toxicity values. Cd and Cu concentrations are also below the ISQG-L toxicity levels for these elements. However, Pb and Zn concentrations do exceed the ISQG-L values in some of the surface bulk samples in the upper estuary proximal to long established sources of catchment pollution.

Abrahim, G. M. S.; Parker, R. J.; Nichol, S. L.

2007-07-01

141

Cyanobacteria and macroalgae in ecosystem of the Neva estuary  

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Full Text Available The Baltic Sea and Neva estuary are plagued by coastal eutrophication. In order to estimate the scale of the problem, quantitative estimates of phytoplankton and macroalgal mats were determined in the Neva estuary. Long-term monitoring (1982–2009 of phytoplankton showed changes in its species composition and abundance. Summer phytoplankton biomass increased significantly in the 1990s, with concomitant changes in species composition, despite a decline of nutrients in the Neva estuary. The cyanobacteria Planktothrix agardhii became a dominant species. The summer biomass of phytoplankton reached a maximum of 5.2 ± 0.4 mg·L-1 in 2002–2004. Monitoring of macroalgal community in the coastal area of the Neva estuary from 2002 to 2009 showed the dominance of the filamentous green alga Cladophora glomerata in the phytobenthos. Average biomass of macroalgae in inner and outer estuary differed significantly at 132 ± 29 and 310 ± 67 g DW·m-2, respectively. This study showed, that fluctuations in macroalgal biomass reflected human influence on estuary, although it was less sensitive to human impact than the phytoplankton community. Thus qualitative and quantitative characteristics of phytoplankton and macroalgal blooms can indicate anthropogenic influence on the ecosystem, and help to better manage the Neva estuary.

Nikulina V. N.

2011-07-01

142

Denitrification in the river estuaries of the northern Baltic Sea.  

Science.gov (United States)

Estuaries have been suggested to have an important role in reducing the nitrogen load transported to the sea. We measured denitrification rates in six estuaries of the northern Baltic Sea. Four of them were river mouths in the Bothnian Bay (northern Gulf of Bothnia), and two were estuary bays, one in the Archipelago Sea (southern Gulf of Bothnia) and the other in the Gulf of Finland. Denitrification rates in the four river mouths varied between 330 and 905 micromol N m(-2) d(-1). The estuary bays at the Archipelago Sea and the Gulf of Bothnia had denitrification rates from 90 micromol N m(-2) d(-1) to 910 micromol N m(-2) d(-1) and from 230 micromol N m(-2) d(-1) to 320 micromol N m(-2) d(-1), respectively. Denitrification removed 3.6-9.0% of the total nitrogen loading in the river mouths and in the estuary bay in the Gulf of Finland, where the residence times were short. In the estuary bay with a long residence time, in the Archipelago Sea, up to 4.5% of nitrate loading and 19% of nitrogen loading were removed before entering the sea. According to our results, the sediments of the fast-flowing rivers and the estuary areas with short residence times have a limited capacity to reduce the nitrogen load to the Baltic Sea. PMID:17520925

Silvennoinen, Hanna; Hietanen, Susanna; Liikanen, Anu; Stange, C Florian; Russow, Rolf; Kuparinen, Jorma; Martikainen, Pertti J

2007-04-01

143

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

144

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

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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 anthropogenic impacts (e.g., nutrient enrichment and physicochemical 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, known to be true of 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

2014-09-01

145

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)

146

The branching channel network in the Yangtze Estuary:  

OpenAIRE

The channels in the Yangtze Estuary have an ordered-branching structure: The estuary is first divided by the Chongming Island into the North Branch and the South Branch. Then the South Branch is divided into the North Channel and South Channel by the Islands Changxing and Hengsha. The South Channel is again divided into the North and South Passage by the Jiuduansha Shoal. This three-level bifurcation and four-outlet configuration appears to be a natural character of the estuary, also in the p...

Wang, Z. B.; Ding, P. X.

2012-01-01

147

Forest bound estuaries are higher methane emitters than paddy fields: A case of Godavari estuary, East Coast of India  

Science.gov (United States)

In the Godavari estuary, ambient methane concentrations were monitored for a period of 5 years and the data reveals that the estuary sampling stations have shown a high average maximum value of methane 14.8 ppmv while nearby paddy field sampling stations the methane concentration were 3-4 fold lower than the estuary. The acidic nature of the estuary soils (pH 5.8-6.2) along with redox potential -120mV favours high methane emissions. The samples collected from the edge of the estuary have shown 0.12-0.15% of Fe wherein ambient methane concentrations were 4.8-5.6 ppmv. It was observed that the anoxic condition with high available iron in the soil improves anaerobic decomposition of organic matter to produce methane. The litter production from nearby mangrove vegetation in the estuary is approximately 22,000 tons/annum is a causative factor for higher methane emissions. Remote sensing data was used and developed thematic maps for spatial and temporal distribution of methane using geographical information system. The seasonal trend showed high ambient concentration of methane in winter season, which is mainly due to high moisture content, (OH?) radical and lower temperature. The results suggest that high organic matter (2.5-4.2%) along with soil conditions in the estuary are influencing for higher methane emissions, while in paddy fields the available organic matter for methanogenesis is limited.

Krupadam, Reddithota J.; Ahuja, Rashmi; Wate, Satish R.; Anjaneyulu, Yerramilli

148

Frequency of twinning in southwest Nigeria  

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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

149

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

150

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

OpenAIRE

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

151

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

OpenAIRE

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...

Shivaprasad, A.; Vinita, J.; Revichandran, C.; Reny, P. D.; Deepak, M. P.; Muraleedharan, K. R.; Naveen Kumar, K. R.

2012-01-01

152

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

OpenAIRE

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 monso...

Shivaprasad, A.; Vinita, J.; Revichandran, C.; Reny, P. D.; Deepak, M. P.; Muraleedharan, K. R.; Naveen Kumar, K. R.

2013-01-01

153

Circulation and suspended particulate matter transport in a tidally dominated estuary: caravelas estuary, Bahia, Brazil  

OpenAIRE

The circulation and transport of suspended particulate matter in the Caravelas Estuary are assessed. Nearly-synoptic hourly hydrographic, current (ADCP velocity and volume transport) and suspended particulate matter data were collected during a full semidiurnal spring tide, on the two transects Boca do Tomba and Barra Velha and on longitudinal sections at low and high tide. On the first transect the peak ebb currents (-1.5 ms-1) were almost twice as strong as those of the wider and shallow Ba...

Carlos Augusto França Schettini; Luiz Bruner de Miranda

2010-01-01

154

Seasonal Abundance of Micro Algae in Pandi Backwaters of Godavari Estuary, Andhra Pradesh, India  

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Full Text Available Gautami branch of Godavari River is a typical positive estuary and is in tidal communication with the open sea upto a point near Kapileswarapuram. This branch flows southwest and opens into Bay of Bengal at two places, namely Bhiravapalem and Kothapalem. The Gautami branch of Godavari is also connected to Pandi backwaters by a channel known as Pedderu, which starts at Kothapalem, Balusutippa area and enters Pandi back water system. Two stations were selected for collection of data. Hydrographical data were collected for one year from July 2006 to 2007 and the data on distribution of phytoplankton was studied in three seasons during 2006-2007. Hydrographical features of the two stations showed that lower values were recorded during October to February months, while higher values were reported from the month of March to September. A total 57 species of phytoplankton were identified from the two study sites of the Pandi backwaters Composition of phytoplankton varied seasonally in relation to salinity fluctuations and showed that two peak periods, one in June-July and another in between December and March. Present study indicates that diatoms are the dominant group followed by the Chlorophyceae and others. This study will aid the baseline data for aqua-culturists in nearby regions.

Prayaga Murty PRAGADA

2010-09-01

155

Circulation and dispersion in a cancellate coast: The rivers, bays and estuaries of central Maine  

Science.gov (United States)

The glacially carved central coast of Maine is incised by river systems with interconnecting channels, offshore-trending submarine ridges, and narrow passages between nearshore islands and headlands. The tidal range exceeds 3 m, leading to complex and vigorous circulation patterns with strong flows in narrow channels, near river mouths, and between islands. The spongiform coastal morphology allows enhanced exchange between offshore waters, estuaries and internecine bays, resulting in rapid dispersal of nutrients, larvae and contaminants throughout the region. A fine-grid numerical circulation model has been used to examine the influences of the tides, river flows and winds on the dispersion of lobster larvae and pollutants in the nearshore and riverine environment. This paper describes the model application, presents a few salient features of the circulation patterns, and examines some implications for the coastal environment. For example, under realistic tides and variable southwest summer winds, about 80% of neutral near-surface particles introduced near the offshore islands (a proxy for stage IV lobster larvae from offshore sources) remain within a few km of the islands over a two-week period. On the other hand, a persistent, periodic sea breeze can remove more than two-thirds of the particles from the domain over the same period. Tidal mixing disperses pollutants entering the upper Kennebec River to the offshore and through internecine passages in about one week.

Brooks, David A.

2009-07-01

156

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

157

Application of analytical solutions for salt intrusion and tidal dynamics in the Yangtze estuary, China  

Science.gov (United States)

There is a set of analytical equations for the computation of salt intrusion and tidal wave propagation, which have been used in many estuaries successfully, especially in the single-channel estuaries. They were also well tested in a multi-channel estuary - Mekong estuary. The Yangtze estuary is one of the largest estuaries in the world, also with multiple channels. It has a complex topography, and two branches with very different characteristics (North branch and South branch). Due to little fresh water the North branch is a typical marine channel, whereas the South branch is a riverine channel because of large river discharge which is still about 10 000m3/s even in the driest months. This is a big difference from other estuaries researched using this theory. This study applies the analytical equations to the Yangtze estuary, which were calibrated and validated on observations. Keywords: analytical solutions; salt intrusion; tidal wave propagation; the Yangtze estuary

Zhang, Erfeng; Savenije, Hubert; Wu, Hui; Chen, Shenliang

2010-05-01

158

Tidal Intrusion Front Observations In A Well-Mixed Estuary - New River Estuary, NC  

Science.gov (United States)

Ebb and flood convergence fronts showing persistent stratification were measured in the New River Estuary (NRE) during the May 2012 ONR-sponsored RIVET Experiment. Owing to its shallow bathymetry, weak freshwater input compared to the tidal forcing, and short tidal excursion relative to the total length, the New River Estuary is considered a well-mixed system. These conditions typically inhibit the formation of tidal intrusion fronts, which are much more common in partially-mixed and salt wedge estuaries. However, surface features on aerial imagery suggest the occurrence of tidal intrusion fronts in at least one of several potential locations. During the flood phases of RIVET, an obliquely oriented front was consistently observed near the exit of the primary inlet into the backbay. This front was characterized by strong density gradients, a 100m wide stratification zone, and subsurface flow enhancement, counter to the friction dominated velocity profiles observed elsewhere in the system but consistent with the dynamics of tidal intrusion fronts. Cross- and along-front density and velocity structures were measured at this front as well as surface flow with drifters. Temporal evolution is discussed, as well as hydraulic force balances to confirm that this is a tidal intrusion front. Frontogenetic and stabilization mechanisms for tidal intrusion fronts in a well-mixed system are proposed, including the importance of provenance of the water masses and bathymetric controls. An idealized hydrodynamic model domain is employed to explore linkages to traditional tidal intrusion front systems.

Weltmer, M.; MacMahan, J. H.; Reniers, A. J.; Thornton, E. B.

2012-12-01

159

Scientific Drilling in the Southwest Pacific Ocean  

Science.gov (United States)

Recent geophysical surveys and geological studies in the southwest Pacific Ocean have improved scientists' understanding of geological evolution and helped to crystallize new research goals. In the current phase of the Integrated Ocean Drilling Program (IODP), there have been five regional expeditions: Canterbury Basin Sea Level (Expedition 317), Wilkes Land Glacial History off Antarctica (Expedition 318), Great Barrier Reef Environmental Changes (Expedition 325), South Pacific Gyre Subseafloor Life (Expedition 329), and Louisville Seamount Trail (Expedition 330). Of six current IODP proposals, four are ready to drill. To review the latest research in the region, briefly outline possible future IODP expeditions, and set up working groups to develop compelling new drilling proposals in the global science context, a workshop was organized at the University of Sydney with a diverse group of 80 scientists. As the JOIDES Resolution may be in the region fairly soon, the workshop participants agreed on the urgent need to build strong science proposals.

Exon, Neville; Gallagher, Stephen; Seton, Maria

2013-03-01

160

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.

161

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

162

Buffering of the salinity intrusion in estuaries by channel convergence  

Science.gov (United States)

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~?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, ?+?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.

Gay, P. S.; O'Donnell, J.

2009-09-01

163

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

164

MODIS water quality algorithms for northwest Florida estuaries  

Science.gov (United States)

Synoptic and frequent monitoring of water quality parameters from satellite is useful for determining the health of aquatic ecosystems and development of effective management strategies. Northwest Florida estuaries are classified as optically-complex, or waters influenced by chlo...

165

Plutonium in Atlantic coastal estuaries in the southeastern United States  

International Nuclear Information System (INIS)

A survey was made to begin to provide baseline information on the Pu distribution of representative estuarine and coastal areas of the southeastern United States. Sediments and marsh grass (Spartina) were collected and analyzed from three locations within a tidal marsh. In three estuaries (Savannah, Neuse, and Newport), the suspended particulate matter (1 ?m and greater) was filtered from waters with different salinities, and the plutonium content of the particulates determined. The Savannah River estuary, in addition to fallout Pu, has received up to 0.3 Ci of Pu from the Savannah River Plant (SRP) of the U. S. Energy Research and Development Administration. The SRP plutonium has a variable isotopic composition that can influence Pu isotopic ratios in the estuarine system. The other estuaries do not have nuclear installations upstream. Data are included on the content of 238Pu, 239Pu, and 240Pu in sediments and marsh grass of the Savannah River estuary

166

Annual cycle of hypoxia off the Changjiang (Yangtze River) Estuary.  

Science.gov (United States)

The annual cycle of hypoxia off the Changjiang Estuary, China, was assessed from data acquired during nine cruises in 2006-2007. Hypoxia began to develop in late spring and early summer, reached its maximum in August, weakened in the autumn and finally disappeared in the winter. Hypoxia first developed south-east of the Changjiang Estuary in June, appeared in the east and north-east in July, and spread both south and north of the Changjiang Estuary in August. By September, it had started to recede in the north-east, and had dissipated in the southern part of the studied area by winter. The geographical displacement of the hypoxic zone was controlled by both seasonal changes in regional water column stratification and variations of the northward extension of the Taiwan Warm Current toward the Changjiang Estuary. PMID:22240466

Wang, Baodong; Wei, Qinsheng; Chen, Jianfang; Xie, Linping

2012-06-01

167

Turbidity and sediment transport in a muddy sub-estuary  

Science.gov (United States)

Sub-estuaries, i.e. tidal creeks and also larger estuaries that branch off the stem of their main estuary, are commonplace in many estuarine systems. Their physical behaviour is affected not only by tributary inflows, winds and tides, but also by the properties and behaviour of their main estuary. Measurements extending over more than an annual cycle are presented for the Tavy Estuary, a sub-estuary of the Tamar Estuary, UK. Generally, waves are small in the Tavy because of the short wind fetch. A several-hour period of up-estuary winds, blowing at speeds of between 7 and 10 m s -1, generates waves with significant wave heights of 0.25 m and a wave periodicity of 1.7 s that are capable of eroding the bed over the shallow, ca. 1.5 m-deep mudflats. Waves also influence sedimentation within and near salt marsh areas. An estuarine turbidity maximum (ETM) occurs in the Tavy's main channel, close to the limit of salt intrusion at HW. Suspended particulate matter (SPM) concentrations typically are less than 40 mg l -1 at HW, although concentrations can exceed 80 mg l -1 when tides and winds are strong. Flood-tide SPM inputs to the Tavy from the Tamar are greater during high runoff events in the River Tamar and also at spring tides, when the Tamar has a high-concentration ETM. Higher SPM concentrations are experienced on the mudflats following initial inundation. Without wave resuspension, this is followed by a rapid decrease in SPM for most of the tide, indicating that the mudflats are depositional at those times. SPM concentrations on the mudflats again increase sharply prior to uncovering. Peak ebb tidal speeds at 0.15 m above the mudflat bed can exceed 0.26 m s -1 at spring tides and 0.4 m s -1 following high runoff events, which are sufficient to cause resuspension. Time-series measurements of sediment bed levels show strong seasonal variability. Higher and lower freshwater flows are associated with estimated, monthly-mean sediment transport that is directed out of, or into, the upper sub-estuary, respectively. Seasonal sediment transfers between the estuary and its sub-estuary are discussed.

Uncles, R. J.; Stephens, J. A.

2010-04-01

168

Spatial variation of the longitudinal dispersion coefficient in an estuary  

OpenAIRE

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 var...

Shaha, D. C.; -k Cho, Y.; -t Kwak, M.; Kundu, S. R.; Jung, K. T.

2011-01-01

169

Initial growth of phytoplankton in turbid estuaries: a simple model  

OpenAIRE

An idealised model is presented and analysed to gain more fundamental understanding about the dynamics of phytoplankton blooms in well-mixed, suspended sediment dominated estuaries. The model describes the behaviour of subtidal currents, suspended sediments, nutrients and phytoplankton in a channel geometry. The initial growth of phytoplankton and its spatial distribution is calculated by solving an eigenvalue problem. The growth rates depend on the position in the estuary due to along-estuar...

Swart, H. E.; Schuttelaars, H.; Talke, S. A.

2009-01-01

170

Distribution and Transport of Chemical Constituents in the Clyde Estuary  

Science.gov (United States)

Five transects of the Clyde Estuary were carried out between August 1989 and March 1991, always during the last 2 h of the flood tide. The following water-column properties were examined: dissolved, leachable particulate and detrital particulate trace elements (Fe, Mn, Zn, Pb, Cd, Co, Cu, Ni), pH, alkalinity, salinity, temperature, dissolved oxygen, dissolved and particulate organic carbon, suspended particulate matter and dissolved nutrients (PO 4, NH 3 + NH 4, NO 3, NO 2, Si). The distribution patterns for both dissolved metals and nutrients reflected their quasi-conservative behaviour in the lower estuary, but were more difficult to interpret in the upper estuary due to the multiplicity of inputs. The suspended particulate material (SPM) collected in the lower estuary at 3 m was depleted in leachable Fe, Zn, Cd, Co, Cu, Ni, and enriched in leachable Mn and Pb relative to the upper estuary. For Mn, the degree of enrichment increased towards the mouth of the estuary, and also with decreasing 'effective freshwater input', indicating that the oxidation of Mn(II) proceeds outside the estuary (Firth of Clyde) and to an extent dependent on the residence time of water in that coastal sea area. The quasi-conservative behaviour of most dissolved and particulate constituents within the estuary results from a combination of short residence time (3-7 days) and low SPM (2-10 mg l -1). This behaviour makes it possible to estimate their net seaward fluxes before these become modified by the processes of coagulation (Fe), sorption (Zn, Pb, Co) and oxidative precipitation (Mn) operating in the Firth of Clyde. The seaward fluxes of NH 4 + NH 3, NO 2, PO 4, dissolved Mn, particulate Fe, Zn and Cu are approximately constant throughout the year. Other dissolved and particulate metal fluxes are best represented by an increasing function of freshwater discharge, although the large residual variability attests to the greater complexity of input functions for trace metals.

Muller, F. L. L.; Tranter, M.; Balls, P. W.

1994-08-01

171

Intertidal morphology change following Spartina anglica introduction, Tamar Estuary, Tasmania  

Science.gov (United States)

The surface morphology and sediment characteristics of introduced Spartina anglica marshes of the Tamar Estuary were analysed using a combination of spatial mapping, land-based topographical surveys, sediment coring and identification of the pre-introduction surface. Such a morphological investigation of estuarine change following Spartina introduction has not been attempted elsewhere before. A difference was found between marshes in upper and lower estuary. Surface topography of Type-1 marshes of the upper estuary was found to be independent of the pre-Spartina surface morphology, with deeper vertical development and exhibiting a flat to slightly concave upper marsh, a convex ridge in the outer mid marsh, and a relatively steeply graded convex lower marsh. Type-2 marshes of the lower estuary were thinner in vertical development, and with surface topography dictated by the underlying pre-Spartina surface. The difference was found to be due to variations in environmental conditions in sediment supply and wave/current exposure between the two regions rather being an indication of relative maturity. The seaward edge of marshes was found to be 0.5 m lower at the seaward end of the Tamar relative to the landward, reflecting tidal amplification up this confined estuary. While Spartina marshes are accretionary, surveys demonstrated retreat of the seaward margins throughout the estuary over the past 17 years, and the development of erosional scarps in Type-1 marshes. Spatial mapping identified 374 ha of S. anglica infestation within the Tamar Estuary, with Type-1 marshes occupying 240 ha and Type-2 marshes occupying 134 ha. Topographic profiles and stratigraphic data were used to estimate total sediment volumes trapped by Spartina in the Tamar Estuary, finding approximately 1,193,441 m3 of material to have been trapped beneath Spartina since its introduction in 1947, of which between 14 and 28% has been Spartina-derived organic matter.

Sheehan, Matthew R.; Ellison, Joanna C.

2014-08-01

172

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

173

Options for Marine Leisure Development in Waterford Estuary  

OpenAIRE

During 2000-2001 the Marine Institute, the national agency charged with responsibility for co-ordinating marine research in Ireland, participated in an Interreg IIc Project - MAYA - Marinas and Yachting in the North West Metropolitan Area. A key objective of this European project was to develop a spatial vision for marina developments in a city, estuary and sensitive coastal environments. As part of this project, the Institute commissioned a study of Waterford Estuary, which would: (1)a...

Institute, Marine

2001-01-01

174

Nutrient flux and budget in the Ebro estuary  

OpenAIRE

The Ebro river flows to the Mediterranean coast of Spain. During its final stretch, the Ebro behaves in a similar way to a highly stratified estuary. This paper describes the transport of nutrients to the Ebro estuary, evaluates the general movement of nutrients in the estuarine region, using a mass balance approach, and estimates the amounts of nutrients discharged to the coastal environment. Given the strong saline stratification, this study only includes the surface layer that contains the...

Falco Giaccaglia, Silvia Laura; Niencheski, L. F.; Rodilla Alama?, Miguel; Romero Gil, Inmaculada; Gonza?lez Del Rio Rams, Julio; Sierra, J. P.; Mo?sso, C.

2010-01-01

175

Silicate Abundance and its Significance in the Hooghly-Matla Estuary, India (Invited)  

Science.gov (United States)

Sea water contains in suspension a wide spectrum of siliceous materials. The surface water abounds with organisms such as diatoms and radiolarians having skeletons composed of non-crystalline form of hydrated silica. A very high level of silicate (130-140 ?M) noticed in the Bay of Bengal nearer the confluence of the rivers, where nutrient levels are appreciably higher during southwest monsoon period (March-October) in contrast to other seasons (CSMCRI, 2007). The relatively high (>5 µg) silicate values at the Ganges head (Bay of Bengal) is attributable to river runoff during the same period (CSMCRI, 2007). In general, the concentration of inorganic phosphate, nitrate and silicate increased in the direction of Antarctic Sea, particularly around 40° S latitude, in the proximity of sub-tropical convergence. In comparison to Atlantic and Pacific oceans, the concentration of nutrients in the Indian Ocean is almost twice (Venkataramana, 2007). The mean value of 102.9±43.2 ?M for silicate in Hooghly estuary is found lower than worldwide average river water concentration of 147.8±93.6 ?M (Gems, 2002). Seasonal variation of river runoff of silicate shows maximum value of 12.6×109 mol during monsoon; thereafter, its value decreased to 2.54 and 1.33×109 mol during post-monsoon and pre-monsoon, respectively. The net residual flows of 4.91, 1.47 and 0.5×109 mol and the exchange flux of 6.95, 0.94 and 0.51×109 mol is found at the estuary during monsoon, post-monsoon and pre-monsoon, respectively. The annual flux of silicate out of the estuary is estimated to be 15.28×109 mol (428×103 t), about 93% of the total fluvial flux. The non-conservative flux of silicate removed from the water column is found to be 1.12 × 109 mol (31.0×103 t), which is about 5% in the global scale (0.6×106 t year-1) (Tregguer et al.,1995). Nitrate, Phosphate and Silicate, have been studied in the Hooghly-Matla estuarine complex and compared with selected previous studies. It is observed that both nitrate and phosphate concentrations remained almost stable varied (between 19.28 and 19.4?M for DIN and between 1.61and 1.99?M for DRP) during the period between 1975 and 2001, but silicate shows a distinct increasing trend from 35.6 to 102.9?M (Nandy et al., 1983; NIO, 1986; Ghosh et al., 1992). These also conforms our study, with the concentration of silicate from 19.97 µ M to 72.73 µ M during pre-monsoon and 48.26 µ M to 103.19 µ M during the monsoon in the Hooghly-Matla estuarine complex. High concentrations of biogenic silica in tidal marshes are necessary for maximum benthic diatom production which in turn helps high secondary production of commercial fish and crustaceans (Courtney, 2007). The Gross Primary Productivity is found to be increased in three stations of these estuaries (27.32±5.06 mg/m3/ hr in 1990, 33.58±14 mg/m3/ hr in 2000 and 44.36±5.91 mg/m3/ hr in 2007) (Biswas et. al., 2009), with the increasing trend of silicate within this estuarine complex. The increasing trend of total catches in the Eastern and Western Indian Ocean (FAO, 1998), of which the Bay of Bengal is an important part (Islam, 2003), justify the interrelation. Thus, these findings are ascertaining the interrelation between the increasing trend of silicate concentration with the enhanced primary productivity, which in turn increase the fish yield in the Hooghly-Matla estuarine complex on the Bay of Bengal.

Ghosh, T.; Akhand, A.

2010-12-01

176

7 CFR 1126.2 - Southwest marketing area.  

Science.gov (United States)

...2010-01-01 2009-01-01 true Southwest marketing area. 1126.2 Section 1126.2 Agriculture...Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Milk), DEPARTMENT...

2010-01-01

177

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

178

A review of sediment contamination by trace metals in the Humber catchment and estuary, and the implications for future estuary water quality  

Science.gov (United States)

This paper reviews what is presently known about sediment contamination in the macro-tidal Humber estuary on the east coast of the UK, with particular reference to the trace elements arsenic, copper, lead and zinc. The Humber is a post-industrial estuary, with an industrial and mining legacy of contaminated sediments throughout the river catchment. Surface and near-surface sediments in the estuary also show significant contamination of trace metals over background values. Inputs of dissolved and particulate trace elements to the estuary from the rivers are reviewed, and atmospheric deposition to the catchment and estuary calculated as a potential additional source of contamination. The necessity of maintaining the sediment balance within the estuary means that contaminated sediments dredged from the estuary harbours are deposited to other sites within the estuary, rather than being removed. Trace metal concentrations in recent dredged sediments, and sediments from the period of peak contamination in the 1970s, are compared with background values. Current inputs to the estuary from point sources, and trends over the last decade are considered. Our calculation of the current depositional fluxes of trace metals to the estuary intertidal sediments, and comparison with the inputs, reveals that the estuary sediments are today capable of storing 55-97% of the input load of As, 15-27% of the Cu, 17-50% of the Pb and 11-12% of the Zn annually. Sediment quality in the estuary is currently far from its 'background' state with respect to trace metals. This has implications for the future water and sediment quality of the Humber under the terms of the EU Water Framework Directive. One management option being considered to improve sea defences in the estuary, managed realignment, may also act to dilute contaminated sediments in the estuary, and thereby to improve future water quality. We look at the effect on sediment contaminant storage of three possible future managed realignment scenarios.

Cave, R. R.; Andrews, J. E.; Jickells, T.; Coombes, E. G.

2005-02-01

179

Hydrodynamic controls on oxygen dynamics in a riverine salt wedge estuary, the Yarra River estuary, Australia  

Science.gov (United States)

Oxygen depletion in coastal and estuarine waters has been increasing rapidly around the globe over the past several decades, leading to decline in water quality and ecological health. In this study we apply a numerical model to understand how salt wedge dynamics, changes in river flow and temperature together control oxygen depletion in a micro-tidal riverine estuary, the Yarra River estuary, Australia. Coupled physical-biogeochemical models have been previously applied to study how hydrodynamics impact upon seasonal hypoxia; however, their application to relatively shallow, narrow riverine estuaries with highly transient patterns of river inputs and sporadic periods of oxygen depletion has remained challenging, largely due to difficulty in accurately simulating salt wedge dynamics in morphologically complex areas. In this study we overcome this issue through application of a flexible mesh 3-D hydrodynamic-biogeochemical model in order to predict the extent of salt wedge intrusion and consequent patterns of oxygen depletion. The extent of the salt wedge responded quickly to the sporadic riverine flows, with the strength of stratification and vertical density gradients heavily influenced by morphological features corresponding to shallow points in regions of tight curvature ("horseshoe" bends). The spatiotemporal patterns of stratification led to the emergence of two "hot spots" of anoxia, the first downstream of a shallow region of tight curvature and the second downstream of a sill. Whilst these areas corresponded to regions of intense stratification, it was found that antecedent conditions related to the placement of the salt wedge played a major role in the recovery of anoxic regions following episodic high flow events. Furthermore, whilst a threshold salt wedge intrusion was a requirement for oxygen depletion, analysis of the results allowed us to quantify the effect of temperature in determining the overall severity and extent of hypoxia and anoxia. Climate warming scenarios highlighted that oxygen depletion is likely to be exacerbated through changes in flow regimes and warming temperatures; however, the increasing risk of hypoxia and anoxia can be mitigated through management of minimum flow allocations and targeted reductions in organic matter loading. A simple statistical model (R2 > 0.65) is suggested to relate riverine flow and temperature to the extent of estuary-wide anoxia.

Bruce, L. C.; Cook, P. L. M.; Teakle, I.; Hipsey, M. R.

2014-04-01

180

Building Regional Threat-Based Networks for Estuaries in the Western United States  

OpenAIRE

Estuaries are ecologically and economically valuable and have been highly degraded from both land and sea. Estuarine habitats in the coastal zone are under pressure from a range of human activities. In the United States and elsewhere, very few conservation plans focused on estuaries are regional in scope; fewer still address threats to estuary long term viability.We have compiled basic information about the spatial extent of threats to identify commonalities. To do this we classify estuaries ...

Merrifield, Matthew S.; Hines, Ellen; Liu, Xiaohang; Beck, Michael W.

2011-01-01

181

The unexpected occurrence of late Sardina pilchardus (Walbaum, 1792) (Osteichthyes: Clupeidae) larvae in a temperate estuary  

OpenAIRE

The presence of sardine larval stages inside estuaries has generally been regarded as accidental and restricted to the lower part of estuaries. Sampling done with a zooplankton net in the Guadiana estuary corroborated this hypothesis. Late sardine larvae (32.8 ± 2.0 mm) were, however, unexpectedly collected with an otter trawl, 14 km upstream from the mouth of the estuary. Thus, this work intends to: (1) discriminate and compare the abiotic characteristics of the sites where maximum...

Morais, P.; Faria, Ana Margarida Da Silva; Chi?charo, Alexandra; Chi?charo, Lui?s

2009-01-01

182

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

183

A Simple Model of Nitrogen Concentration, Throughput, and Denitrification in Estuaries  

Science.gov (United States)

The Estuary Nitrogen Model (ENM) is a mass balance model that includes calculation of nitrogen losses within bays and estuaries using system flushing time. The model has been used to demonstrate the dependence of throughput and denitrification of nitrogen in bays and estuaries on...

184

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

OpenAIRE

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:

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

2013-01-01

185

MORFODINAMIKA PANTAI DAN SEBARAN VEGETASI BERDASARKAN SEDIMEN BACKSHORE PANTAI ESTUARI JENEBERANG MAKASSAR  

OpenAIRE

ROHAYA LANGKOKE. Morfodinamika Pantai Dan Prospek Sebaran Vegetasi Berdasarkan Sedimen Backshore Estuari Jeneberang (dibimbing oleh Muslimin Mustafa, D.A. Suriamiahardja, dan Agnes Rampisela). Tujuan Penelitian adalah untuk 1) menentukan zona pemanfaatan lahan Pantai Estuari Jeneberang berdasarkan sedimen backshore, 2) menjelaskan proses-proses morfodinamika garis tepi dan hamparan Estuari Jeneberang, 3) menjelaskan proses perubahan tinggi rendahnya permukaan air laut, dan menginterpretas...

Langkoke, Rohaya

2012-01-01

186

Numerical study on salinity stratification in the Pamlico River Estuary  

Science.gov (United States)

The variations of current circulation, salt intrusion, and vertical stratification under different river flow and wind conditions in the Pamlico River Estuary (PRE) were investigated in this paper using a three-dimensional numerical model. The model was calibrated and verified against water level variation, temperature, and salinity variations during 2003 and 2001, respectively. Eight sensitivity tests were conducted with different river flow and wind conditions specified in the model. Model results show that salinity intruded further upstream under scenarios with low flow, downriver local wind, and remote-wind-caused water level set-up conditions. In contrast, the responses of salinity stratification to different environmental forcing functions were different in different portions of the estuary. Salinity stratification was enhanced under high flow condition at the lower part of the estuary, under upriver wind near the river mouth, under downriver wind at the upstream to middle portion of the estuary, and under remote-wind-caused water level set-up condition at the majority of the estuary except near the river mouth. Model results also show that across-channel wind tended to reduce salt intrusion and salinity stratification in the PRE through increased vertical mixing.

Xu, Hongzhou; Lin, Jing; Wang, Dongxiao

2008-10-01

187

Analytical description of tidal dynamics in convergent estuaries  

Science.gov (United States)

Analytical solutions of the one-dimensional hydrodynamic equations for tidal wave propagation are now available and, in this paper, presented in explicit equations. For given topography, friction, and tidal amplitude at the downstream boundary, the velocity amplitude, the wave celerity, the tidal damping, and the phase lag can be computed. The solution is based on the full nonlinearized St. Venant equations applied to an exponentially converging channel, which may have a bottom slope. Two families of solutions exist. The first family consists of mixed tidal waves, which have a phase lag between zero and ?/2, which occur in alluvial coastal plain estuaries with almost no bottom slope; the second family consists of "apparent standing" waves, which develop in short estuaries with a steep topography. Asymptotic solutions are presented for progressive waves, frictionless waves, waves in channels with constant cross section, and waves in ideal estuaries where there is no damping or amplification. The analytical method is accurate in the downstream, marine part of estuaries and particularly useful in combination with ecological or salt intrusion models. The solutions are compared with observations in the Schelde, Elbe, and Mekong estuaries.

Savenije, Hubert H. G.; Toffolon, Marco; Haas, Jennifer; Veling, Ed J. M.

2008-10-01

188

Attenuation of rare earth elements in a boreal estuary  

Science.gov (United States)

This study focuses on attenuation of rare earth elements (REE) when a boreal creek, acidified and loaded with REE and other metals as a result of wetland drainage, empties into a brackish-water estuary (salinity acidic creek were extensively removed in the inner/central estuary where the acidic water was neutralised, whereas Mn was relatively persistent in solution and thus redistributed to particles and deposited further down the estuary. The REE removal was caused by several contemporary mechanisms: co-precipitation with oxyhydroxides (mainly Al but also Fe), complexation with flocculating humic substances and sorption to suspended particles. Down estuary the dissolved REE pool, remaining after removal, was fractionated: the Humic Model after revision and updating, predicted that the dissolved (humic substances. Acid sulphate soils, the source of the REE and other metals in the creek water, are widespread on coastal plains worldwide and therefore the REE attenuation patterns and mechanisms identified in the studied estuary are relevant for recognition of similar geochemical processes and conditions in a variety of coastal locations.

Åström, Mats E.; Österholm, Peter; Gustafsson, Jon Petter; Nystrand, Miriam; Peltola, Pasi; Nordmyr, Linda; Boman, Anton

2012-11-01

189

Lateral saltwater intrusion in the Changjiang Estuary  

Science.gov (United States)

A common view of saltwater intrusion is the movements of saline water in longitudinal direction. However, suggested by the fields data measured from December 2011 to January 2012 in the Changjiang Estuary, we found that the saline water in the middle reaches of North Channel (NC), where a side-outlet (SNC) is developing, was derived mainly from this lateral outlet rather than its longitudinal main channel during the spring tide. In addition, the peak salinities in the upper and lower reaches of NC were out of phase (~3 days) in the spring-neap tidal cycle, which leads us to speculate whether this salinity phase shift was the result from the lateral saltwater intrusion. To investigate the mechanisms behind these findings, a 3D numerical ocean model is employed after being validated with field data. The model reproduced the lateral saltwater intrusion in middle NC using the wind fields derived from the atmosphere model WRF. The decomposing analysis shows that the vertical shear transport is the major dynamics causing the landward salt transport in lower NC, and the Lagrange and tidal pumping transports are responsible for the salt transport flows from SNC to NC, i.e., the lateral saltwater intrusion. The various mechanisms result in the mentioned salinity phase shift in the different reaches of NC.

Li, L.; Zhu, J. R.; WU, H.

2012-12-01

190

UNAVCO-PBO Southwest Region Network Operations  

Science.gov (United States)

The UNAVCO Southwest region of the Plate Boundary Observatory manages 470 continuously operating GPS stations located principally along the transform system of the San Andreas Fault, Eastern California Shear Zone and the northern Baja peninsula. In the past year, network uptime averaged 98% with greater than 99% data acquisition. Communications range from CDMA modem (314), radio (100), Vsat (30), DSL/T1/other (25) to manual download (1). Thirty-four stations have WXT520 metpacks. Sixty-four stations stream 1 Hz data over the VRS3Net typically with <0.5 second latency. Over 650 maintenance activities were performed during 341 onsite visits out of approximately 346 engineer field days. Within the past year there have been 7 incidences of minor (attempted theft) to moderate vandalism (solar panel stolen) with one total loss of receiver and communications gear. Security was enhanced at these sites through fencing and more secure station configurations. UNAVCO is working with NOAA to stream real-time GPS and met data from PBO stations with WXT520 meteorological sensors and high rate data communications. These streams support watershed and flood analyses for regional early-warning systems related to NOAA's work with California Department of Water Resources. Network-wide NOAA receives a total of 54 streams including stations in Cascadia. In 2008 PBO became the steward of 209 existing network stations ("Nucleus stations") of which 140 are in the SW region that included SCIGN, BARD, BARGEN stations. Due to the mix of incompatible equipment used between PBO and existing network stations a project was undertaken to standardize existing network GPS stations to PBO specifications by upgrading antenna cabling, power systems and enclosures. In 2012 the Nucleus upgrade project was completed.

Walls, C. P.; Mann, D.; Basset, A.; Sklar, J.; Jarvis, C.; Pitcher, T.; Lawrence, S.; Greathouse, M.; Feaux, K.

2012-12-01

191

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

192

The buffering capacity of a small estuary on nutrient fluxes originating from its catchment (Leyre estuary, SW France)  

Science.gov (United States)

This work studied the impact of a small estuary (a 4 km-long estuary, at the interface between the Leyre River and the Arcachon lagoon, SW France) with a short flushing time on continental nutrient loads to a coastal lagoon. While large estuaries are known to modify the nutrient load of rivers to the coast, the impact on continental fluxes of a short salinity gradient from small coastal rivers is rarely studied. A survey of nutrient and dissolved organic matter concentration, particulate phosphorus speciation and particulate organic matter (POM) concentration and characteristics (C:N ratio and particulate organic carbon ?13C) showed that the estuarine behaviour varied throughout the year. The autochthonous primary production was a sink of dissolved N, P and Si in spring. During this period, the continental load of dissolved nitrogen was reduced by about 1/3 and phosphorus was totally consumed by estuarine processes. Nutrient recycling occurred in summer with ammonium production although this source was low in comparison with continental fluxes of nitrogen. The phosphorus concentration was dominated by the iron oxides-bound fraction. Contrary to large estuaries, the desorption of particulate phosphorus was not a source of dissolved phosphorus. Our results showed that estuarine processes impacted the net nutrient fluxes during productive periods, although estuarine residence time was very short. Passive transport with conservative mixing of nutrient was observed in autumn and winter. The non-conservative behaviour of small estuaries must be taken into account for nutrient mass balance calculation in lagoon.

Canton, Mathieu; Anschutz, Pierre; Poirier, Dominique; Chassagne, Romain; Deborde, Jonathan; Savoye, Nicolas

2012-03-01

193

Delaware Estuary situation reports. Emergency response: How do emergency management officials address disasters in the Delaware Estuary  

International Nuclear Information System (INIS)

From hurricanes and other natural threats to oil spills and other manmade emergencies, the Delaware Estuary has experienced a variety of disasters over the years. The toll that these events take on the estuary and those who live on its shores depends largely upon the degree of emergency preparedness, speed of response, and effectiveness of recovery operations. In Emergency Response: How Do Emergency Management Officials Address Disasters in the Delaware Estuary, the latest addition to its Delaware Estuary Situation Report series, the University of Delaware Sea Grant College Program defines emergency management; examines the roles that the Coast Guard, Army Corps of Engineers, and Environmental Protection Agency play in an emergency; and reviews how each of these federal agencies operated during an actual disaster--the 1985 Grand Eagle oil spill. The report was written by Dr. Richard T. Sylves, a professor of political science at the University of Delaware. Sylves has been studying emergency management for the past 15 years, with special emphasis on oil spill preparedness and response in the Mid-Atlantic Region. The Delaware Estuary Situation Report is 12 pages long and contains maps and photographs, as well as a detailed account of response and recovery operations undertaken during the Grand Eagle oil spill. A comparison of the 1985 Grand Eagle spill and the 1989 Presidente Rivera spill also is included

194

The geomorphology of UK estuaries: The role of geological controls, antecedent conditions and human activities  

Science.gov (United States)

This paper provides an overview of the geomorphological characteristics of UK estuaries and the factors which control them. Many of the features included in previous classifications of UK estuaries are not true estuaries since they do not possess significant river influence. The features considered in this paper to be 'true' estuaries are divided into 'restricted entrance' and 'unrestricted entrance' types on the grounds that the size and geometry of the estuary mouth exerts a critical influence on water levels, tidal currents, wave action, sediment transport and morphological evolution. An estuary which has a wide mouth, narrows and becomes shallower towards the head is likely to be flood dominated, especially if it has a large tidal range, whereas an estuary which has a narrow mouth and widens and/or becomes deeper towards the head is more likely to display ebb dominance, especially if it has a relatively small tidal range. Wide-mouthed estuaries are influenced to a greater degree by wave processes than estuaries with a narrow mouth. Previous authors have hypothesised that estuaries may maintain a state of dynamic equilibrium through alternating periods of flood and ebb dominance, but it is concluded that there is presently no substantive evidence to support this hypothesis. UK estuaries have been affected to varying degrees by embanking, land claim, dredging, sea wall breaching and managed realignment. Some estuaries have adjusted quickly to such perturbations, but others continue to show progressive change, either sedimentary infilling or erosion and sediment loss. The quantification of estuary morphometry, identification of change over time, and testing of hypotheses regarding the morphodynamics and stability of estuaries requires adequate bathymetric/topographic, hydrodynamic and sediment data. At present, such data are available for relatively few UK estuaries.

Pye, Kenneth; Blott, Simon J.

2014-10-01

195

Tritium in the Savannah River Estuary and adjacent marine waters  

International Nuclear Information System (INIS)

The tritium distribution in the Savannah River estuary and adjacent marine waters was measured to provide information on the dilution, mixing, and movement of Savannah River water in this region. The Savannah River marine region was chosen because the average tritium concentration in this river is 5 pCi/ml, whereas other rivers in the southeastern United States average less than 0.5 pCi/ml. The increased tritium concentration in the Savannah River is due to releases from the Savannah River Plant of the Department of Energy. Tritium measurements have proved particularly effective in estimating the flushing time of the Savannah River estuary (2.4 days) and in delineating the relative contribution to the water masses in Ossabaw and Port Royal Sounds from the River and from sea water. Ossabaw and Port Royal Sounds are located approximately 20 km south and north of the Savannah River estuary, respectively

196

Tritium in the Savannah River estuary and adjacent marine waters  

International Nuclear Information System (INIS)

The tritium distribution in the Savannah River estuary and adjacent marine waters was measured to provide information on the dilution, mixing and movement of Savannah River water in this region. The Savannah River marine region was chosen because the average tritium concentration in this river is approximately 5 pCi/ml, whereas other rivers in the southeastern United States of America average less than 0.5 pCi/ml. The increased tritium concentration in the Savannah River is due to releases from the Savannah River Plant of the Department of Energy. Tritium measurements have proved particularly effective in estimating the flushing time of the Savannah River estuary (2.4 days) and in delineating the relative contribution to the water masses in Ossabaw and Port Royal Sounds from the river and from sea-water. Ossabaw and Port Royal Sounds are located approximately 20 km south and north of the Savannah River estuary respectively. (author)

197

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)

198

Preliminary Holocene History of the Southwest Greenland Ice Sheet  

Science.gov (United States)

Radiocarbon dates indicate that the southwest Greenland Ice Sheet (GIS) margin neared its present extent between ~10 and 7 ka before retreating further inland. To better constrain the precise timing of when the southwest GIS margin reached its present extent, we will present new cosmogenic radionuclide dates from boulders distal to Little Ice Age moraines at 61 and 67 degrees North. Comparison of these dates and the existing radiocarbon record with southwest GIS margin climate model simulations from 9 ka to 2100 C.E. will place the paleo-forcing of GIS retreat in context with present and future climate change. Model results indicate that surface air temperature (SAT) and radiative forcing are already driving ice-melt anomalies at ~6 ka levels, and ~9 ka levels could be reached by 2050 to 2100 C.E. Thus summer SAT and radiative forcing over southwest Greenland may have already risen to levels that can force ice-melt anomalies equivalent to mid-Holocene levels when the southwest GIS was smaller than present.

Carlson, A. E.; Winsor, K.; Legrande, A. N.; Anslow, F. S.; Harvey, J. F.; Ullman, D. J.; Murray, D. S.

2010-12-01

199

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.

Stephen, Hosking.

200

Mercury uptake in aquatic species from the Richibucto Estuary  

Energy Technology Data Exchange (ETDEWEB)

A study on mercury uptake in estuarian biota was carried out at three different sites within the Richibucto River watershed, as part of the Richibucto Environment and Resource Enhancement Project (REREP). Initially, four aquatic species were analyzed: sand shrimp, mummichog, Atlantic tomcod, and American eel. Results revealed spatial variations within the estuary and in comparison with other estuaries within the province. An increase in mercury concentration at trophic levels was also observed. The second part of this study will examine the effects of peat spill in Mill Creek, on the bioaccumulation of mercury in aquatic species, as well as in water and sediments.

Surette, C.; Mallet, V. [Moncton Univ., NB (Canada). Faculte des Sciences; Brun, G. [Environment Canada, Environmental Science Centre, Moncton, NB (Canada)

1998-11-01

201

Biogeochemistry of the Kem' River estuary, White Sea (Russia)  

OpenAIRE

The biogeochemistry of the river-sea interface was studied in the Kem' River (the largest river flowing to the White Sea from Karelian coast) estuary and adjacent area of the White Sea onboard the RV 'Ekolog' in summer 2001, 2002 and 2003. The study area can be divided into 3 zones: I - the estuary itself, with water depth from 1 to 5m and low salinity in the surface layer (salinity is lower than 0.2psu in the Kem' River and varies from 15 to 20psu in outer part of this zone); II - the interm...

Shevchenko, V. R.; Dolotov, Y. S.; Filatov, N. N.; Alexeeva, T. N.; Filippov, A. S.; -m No?thig, E.; Novigatsky, A. N.; Pautova, L. A.; Platonov, A. V.; Politova, N. V.; Rat Kova, T. N.; Stein, R.

2005-01-01

202

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

203

The role of wind on the detachment of low salinity water in the Changjiang Estuary in summer  

Science.gov (United States)

Two detachment processes of low salinity water (LSW) in the Changjiang Estuary in July 2006, and the role of wind on detaching the LSW in particular, are explored with a three-dimensional numerical model. The real-case simulation and the sensitivity experiments results show that wind plays a crucial role in the detachment events and is highlighted in three aspects. First, wind is the most important dynamic factor in the two detachment processes of the LSW. Wind mixing, wind-driven northward current and wind-induced upwelling are three driving forces on detaching the LSW, which increase the salinity in the upper layer in the detachment region along the 30 m isobath and separate the offshore LSW from the nearshore main body of LSW. The diagnostic analysis further indicates that the increase of salinity in the detachment region is mainly due to northward current which transports high salinity water from the south. Second, a critical wind speed, namely a southeasterly wind above 8.0 m/s, is found to be related to the timing of the detachment events. A sensitivity experiment further confirms this critical wind speed and no detachment occurs when the wind speed is below 8.0 m/s. Third, the southwesterly wind plays a key role in the magnitude of the spatial size of the detached LSW. Before the detachment occurs, a persistent southwesterly wind induces northeastward expansion of the LSW and consequently forms larger LSW offshore after detachment, which is verified by another sensitivity experiment with modified wind direction.

Xuan, Ji-Liang; Huang, Daji; Zhou, Feng; Zhu, Xiao-Hua; Fan, Xiaopeng

2012-10-01

204

Sediment dynamics of the Mzymta river estuary  

Science.gov (United States)

The Mzymta River dates on the southern slope of the Caucasus Mountains at height 2980 m above sea level. It runs into Black Sea (at Adler, Russia) as uniform channel with width about 170 m, forming a shallow and vast alluvial cone. Length of the Mzymta River is 89 km, the basin area is 885 km2. River alimentation is mixed; water regime is characterized by presence of a spring-and-summer high water and rain high waters. The river sediment runoff is closely connected with features of a water regime of the Mzymta River. The maximum sediment discharge is observed in May and July and occurs due to the high water flow during the flood and high turbidity of waters in this period. The average annual discharge of sediments increases downstream from 4,8 to 11 kg/s. In some years the sediment runoff in a river mouth can reach 730•103 t/year (average turbidity to 420 g/m3) or, on the contrary, decrease to 38•103 t/year (38 g/m3). The greatest value of water turbidity in the Mzymta River was observed in August, 1977 and amount to 11000 g/m3. Average- and small-sand, and clay particles prevail in granulometric composition of the suspended sediments. The river bed is composed by larger material: sand, gravel, pebble and boulder. The river mouth forms a broad alluvial cone blocked by sand alongshore barrier beach. The coast of Black Sea around estuary of the Mzymta River is the accumulative coast generated on steep slope. Beach deposits can leave on the depth excluding return receipt. Several active submarine canyons are situated near Mzymta estuary. Long evolution of these forms carries pulsation character and position of canyons essentially does not vary. According to the aerial mappings for various years, the sizes of pulsations reach 100-120 m. Beach between the Mzymta and Psou rivers are form by Mzymta solid runoff. It confirmed by petrographic structure of the beach deposits. Progressive reduction of the average size of beach deposits and increase of sand part are observed because of reduction of sediment transport and change of its structure. Regulated of the Mzymta River flow has led to reduction of a drain of deposits of the river. Now the drain of deposits of the river makes about 70 % from the natural. At reduction of sediment transport of the river Mzymta and deficiency beach deposits the excess line of underwater slope on depth is forward to approach on coast. The canyon "Novy" especially quickly runs into a land. So in its limits 10-metre isobatic curve has promoted towards coast to 90 m during last 100years and 5-metre isobatic curve - to 120 m. At list 2 million ?3 of sediments has been withdrawn from around the Mzymta mouth beach during last 10 years. As a result of fulfilled research a detailed characteristic of modern sediment dynamics and determining factors was done. Climatic variations and man impact are basic factors that determine a formation of Mzymta seaside and proceeding of dynamical processes at present.

Krylenko, Marina; Isupova, Maria

2010-05-01

205

Historic developments in macrozoobenthos of the Rhine Meuse estuary: From a tidal inlet to a freshwater lake  

Science.gov (United States)

Water works during the 1960s and 1970s changed the northern part of the Rhine-Meuse estuary in the south-west of the Netherlands into a freshwater lake, from west to east divided into three basins called the Haringvliet, the Hollands Diep and the Biesbosch. Concurrently water quality parameters (e.g. nutrients and pollutants) changed drastically during the last 50 years. This study combines macrozoobenthic monitoring data from the region from 1960 to 2001 with trends in abiotic parameters to evaluate historic developments of the communities, including densities, species numbers and diversity, and assess future developments as a first step to a rehabilitation of the estuary as planned for January 01, 2008. During the 1960s, the macrozoobenthic densities of Oligochaeta and/or Polychaeta dominated communities increased with a gradual decrease of saltwater intrusion and salinity variability. The first years after the basins became stagnant, the species numbers per sample and the Shannon diversity were high due to the coexistence of salt and freshwater species. An increase in nutrient and pollutant loads led to a decrease in the macrozoobenthos densities. As water and sediment quality gradually improved, nowadays the former estuary contains high diversity and high density macrozoobenthic communities, whereas Oligochaeta and/or Polychaeta were dominant in the 1960s, and Bivalvia and Gastropoda were more abundant during the 1970s. Macrozoobenthic communities moved from the east to west with a time-lag, which may primarily be attributed to changing salinities, salinity variances and oxygen levels. Therefore, the current communities of the Haringvliet show similarities with the communities that occurred already during the 1960s in the Biesbosch. This study shows the value of macrozoobenthos monitoring data over longer periods. The possible impact of a new saltwater inlet in the west of the Haringvliet, allowing in the near future saltwater to enter 11.5 km eastward, yet alternated by frequent flushing with freshwater to ascertain that the salt intrusion does not reach further, on the development of the macrozoobentic communities is discussed.

Wijnhoven, S.; Sistermans, W.; Hummel, H.

2008-01-01

206

Metal speciation and toxicity of Tamar Estuary water to larvae of the Pacific oyster, Crassostrea gigas.  

Science.gov (United States)

As part of the PREDICT Tamar Workshop, the toxicity of estuarine waters in the Tamar Estuary (southwest England) was assessed by integration of metal speciation determination with bioassays. High temporal resolution metal speciation analysis was undertaken in situ by deployment of a Voltammetric In situ Profiling (VIP) system. The VIP detects Cd (cadmium), Pb (lead) and Cu (copper) species smaller than 4 nm in size and this fraction is termed 'dynamic' and considered biologically available. Cadmium was mainly present in the dynamic form and constituted between 56% and 100% of the total dissolved concentration, which was determined subsequently in the laboratory in filtered discrete samples. In contrast, the dynamic Pb and Cu fractions were less important, with a much larger proportion of these metals associated with organic ligands and/or colloids (45-90% Pb and 46-85% Cu), which probably reduced the toxicological impact of these elements in this system. Static toxicity tests, based on the response of Crassostrea gigas larva exposed to discrete water samples showed a high level of toxicity (up to 100% abnormal development) at two stations in the Tamar, particularly during periods of the tidal cycle when the influence of more pristine coastal water was at its lowest. Competitive ligand-exchange Cu titrations showed that natural organic ligands reduced the free cupric ion concentration to levels that were unlikely to have been the sole cause of the observed toxicity. Nonetheless, it is probable that the combined effect of the metals determined in this work contributed significantly to the bioassay response. PMID:21704365

Money, Cathryn; Braungardt, Charlotte B; Jha, Awadhesh N; Worsfold, Paul J; Achterberg, Eric P

2011-07-01

207

A lightning climatology of the South-West Indian Ocean  

OpenAIRE

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

208

77 FR 24199 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

Science.gov (United States)

...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2012-04-23

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76 FR 22699 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2011-04-22

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76 FR 4652 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2011-01-26

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78 FR 64495 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2013-10-29

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76 FR 64940 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2011-10-19

213

77 FR 42718 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2012-07-20

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77 FR 64505 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2012-10-22

215

77 FR 3765 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2012-01-25

216

76 FR 42123 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2011-07-18

217

78 FR 6320 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2013-01-30

218

78 FR 25078 - Notice of Staff Attendance at Southwest Power Pool Regional Entity Trustee, Regional State...  

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...Attendance at Southwest Power Pool Regional Entity Trustee, Regional State Committee and Board of Directors...meetings of the Southwest Power Pool, Inc. (SPP) Regional Entity Trustee (RE), Regional State Committee (RSC) and...

2013-04-29

219

Revised predictive equations for salt intrusion modelling in estuaries  

Science.gov (United States)

For one-dimensional salt intrusion models to be predictive, we need predictive equations to link model parameters to observable hydraulic and geometric variables. The one-dimensional model of Savenije (1993b) made use of predictive equation for the Van der Burgh coefficient K and the dispersion at the seaward boundary D0. Here we have improved these equations by using an expanded database, including new previously un-surveyed estuaries. Furthermore, we derived a revised predictive equation for the dispersion at tidal average (TA) condition and with the boundary situated at the well identifiable inflection point where the estuary changes from wave-dominated to tide-dominated geometry. We used 89 salinity profiles in 30 estuaries (including 7 recently studied estuaries in Malaysia), and empirically derived a range of equations using various combinations of dimensionless parameters. We split our data in two separated datasets: (1) with more reliable data for calibration, and (2) with less reliable data for validation. The dimensionless parameters that gave the best performance depended on the geometry, tidal strength, friction and the Richardson Number. The limitation of the equations is that the friction is generally unknown. In order to overcome this problem, a coupling has been made with the analytical hydraulic model of Cai et al. (2012), which makes use of observed tidal damping and by which the friction can be determined.

Gisen, J. I. A.; Savenije, H. H. G.; Nijzink, R. C.

2015-01-01

220

Revised predictive equations for salt intrusion modelling in estuaries  

Directory of Open Access Journals (Sweden)

Full Text Available For one-dimensional salt intrusion models to be predictive, we need predictive equations to link model parameters to observable hydraulic and geometric variables. The one-dimensional model of Savenije (1993b made use of predictive equation for the Van der Burgh coefficient K and the dispersion at the seaward boundary D0. Here we have improved these equations by using an expanded database, including new previously un-surveyed estuaries. Furthermore, we derived a revised predictive equation for the dispersion at tidal average (TA condition and with the boundary situated at the well identifiable inflection point where the estuary changes from wave-dominated to tide-dominated geometry. We used 89 salinity profiles in 30 estuaries (including 7 recently studied estuaries in Malaysia, and empirically derived a range of equations using various combinations of dimensionless parameters. We split our data in two separated datasets: (1 with more reliable data for calibration, and (2 with less reliable data for validation. The dimensionless parameters that gave the best performance depended on the geometry, tidal strength, friction and the Richardson Number. The limitation of the equations is that the friction is generally unknown. In order to overcome this problem, a coupling has been made with the analytical hydraulic model of Cai et al. (2012, which makes use of observed tidal damping and by which the friction can be determined.

J. I. A. Gisen

2015-01-01

221

Cladocerans (Branchiopoda) of a tropical estuary in Brazil.  

Science.gov (United States)

The study was conducted in the Capibaribe river estuary in Recife (Brazil) to assess the role played by cladocerans in a eutrophic environment. Samplings were carried out monthly at 4 fixed stations along the estuary from July 1987 to June 1988. Collections were made with a plankton net of 65 micrometers mesh size. Six cladocerans species were registered: Penilia avirostris, Diaphanosoma spinulosum, Chlydorus barroisi, Ceriodaphnia rigaudi, Ilyocryptus spinifer, and Moina micrura. The most frequent species was Moina micrura with 49%. The only true marine species was Penilia avirostris, which was registered at station 1 (close to the river mouth), during high and low tide and in the dry season. The Cladocera average density decreased from 329 ind.m'3 (August 1987, high tide) to 2 ind.m(-3) (March 1988, high tide) due to the high load of organic and chemical pollution received by the estuary. At all stations, D. spinulosum, M. micrura, and C. barroisi occurred with a wide distribution, mainly during the rainy season. C. rigaudi and I. spinifer were rare, occurring only during the rainy season. Cladocerans played an important role in the food webs of the plankton community of the Capibaribe tropical estuary and the dominance of a few small species indicated a hypereutrophic environment. A high level of disturbance was indicated by the decline in diversity of specialized species and the increase in abundance of opportunistic species like M. micrura. PMID:16025910

Paranaguá, M N; Neumann-Leitão, S; Nogueira-Paranhos, J D; Silva, T A; Matsumura-Tundisi, T

2005-02-01

222

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

223

Estuaries May Face Increased Parasitism as Sea Levels Rise  

Science.gov (United States)

Invertebrates in estuaries could be at a greater risk of parasitism as climate change causes sea levels to rise. A new paper published 8 December in Proceedings of the National Academy of Sciences of the United States of America (doi:10.1073/pnas.1416747111) describes how rapid sea level rise in the Holocene affected the population of parasitic flatworms called trematodes.

Wendel, JoAnna

2014-12-01

224

Environmental flow assessments in estuaries related to preference of phytoplankton  

OpenAIRE

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 phytopl...

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

2014-01-01

225

BENTHIC NUTRIENT FLUX IN A SMALL ESTUARY IN NORTHWESTERNFLORIDA (USA)  

Science.gov (United States)

Benthic Nutrient Flux in a Small Estuary in Northwestern Florida(USA).Gulf and Caribbean Research 18, 15-25, 2006. Benthic nutrient fluxes of ammonium (NH4+), nitrite/nitrate (NO2-+NO3-), phosphate (PO4-), and dissolved silica (DSi) were measured in Escambia Bay, an estuar...

226

COASTAL BEND BAYS & ESTUARIES PROGRAM IMPLEMENTATION REVIEW 2004  

Science.gov (United States)

The Coastal Bend Bays & Estuaries Program, Inc. (CBBEP) is a nonprofit 501(c)(3)organization. The CBBEP project area encompasses 12 counties coincident with the Coastal Bend Council of Governments and extends from the Land-Cut in the Laguna Madre, through the Corpus Christi Bay s...

227

Estuarine habitat utilization by birds in Yaquina Estuary, Oregon  

Science.gov (United States)

A wide variety of bird species are highly dependent on intertidal wetland habitats. Because of this dependency, birds are viewed as important indicators of wetland structure and function. Wetlands in Yaquina Bay along with the tidal wetlands in other Pacific coastal estuaries r...

228

Residence time of the Danshuei River estuary, Taiwan  

Science.gov (United States)

The residence time of an estuary is defined in this study as the average time the initially existing water parcels reside in the system before they are flushed out. The residence time of the Danshuei River is calculated through a series of numerical experiments using a laterally integrated two-dimensional hydrodynamic eutrophication model (HEM-2D). The results show that the residence time is on the order of 1-2 days under the mean river flow to zero river flow condition, which is very short compared with most time scales of biogeochemical processes. A procedure is developed to quantify individual contribution to flushing by each of the three major physical transport mechanisms: tide, river discharge, and the density induced circulation. The results indicated that, in general conditions, tidal flushing exerts the greatest influence to the flushing of the Danshuei River estuary, while the density induced circulation hardly contributes any. Tidal transport contributes more than 50% of the flushing when river discharge is below its long-term mean. The suitability of applying the tidal prism method, the modified tidal prism methods, and the fraction of freshwater method in this estuary is also investigated. The relatively short residence time is likely to be one of the limiting factors that result in low phytoplankton biomass in spite of extremely high nutrient concentrations, and causes a significant fraction of pollutants to exert their effects in the coastal waters outside the estuary.

Wang, Chi-Fang; Hsu, Ming-Hsi; Kuo, Albert Y.

2004-07-01

229

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

230

Nutrient transport through estuaries: The importance of the estuarine geography  

Science.gov (United States)

We consider here first the nature of nutrient transport through estuaries and in particular the capacity of estuaries to modify that flux. We then focus particularly on the Wash system in the UK as an example of a particular type of "small estuary", and also consider some tropical estuarine systems in Malaysia. We present nutrient budgets for the Wash system now and create estimates of these budgets 3000 years ago. These show that currently the system is a small sink for fluvial nitrate (?30% removal) largely due to denitrification and dissolved inorganic phosphorus (?24%) by burial. 3000 years ago, prior to large scale human intervention to reclaim wetlands for agriculture, the Wash system was much bigger and operated as a sink for all terrestrial nitrogen (albeit with much lower inputs) and also a sink for nitrate from the North Sea, predominantly via organic nitrogen burial. A similar change with time is evident in the phosphorus flux. We suggest that this change in function of this estuarine system has been replicated in many other estuarine systems. Given the key role of benthic processes of burial and denitrification we go on to suggest that the classification of estuaries in terms of area and river flow may offer a route to a typology of estuarine nutrient retention efficiency.

Jickells, T. D.; Andrews, J. E.; Parkes, D. J.; Suratman, S.; Aziz, A. A.; Hee, Y. Y.

2014-10-01

231

Water and suspended sediment dynamics in Selangor River estuary  

International Nuclear Information System (INIS)

Observations of salinity, temperature, suspended sediment concentration (SSC) and tidal current velocity were made in the lower and along the longitudinal axis of Sungai Selangor estuary over neap-spring cycles. The variations of these parameters at the measurement stations and along the channel are presented to illustrate the water and sediment dynamics in the estuary. The results shows that the Sungai Selangor estuary changes from a partially-mixed type during neaps to a well-mixed one during springs, promoted by stronger tidal energy during the higher tidal ranges. The strong neap density stratification is also promoted by the high river discharges during the measurement period. Maximum concentration of suspended sediment (> 2000 mg/l) occurs during maximum current velocities both during flood and ebb. The maximum salinity was achieved during high water slack but the salt water was totally flushed out of estuary during low water springs. The longitudinal axis measurement indicates that a partially-developed zone of turbidity maximum with a sediment concentration over 1000 mg/l was observed at the limit of salt water intrusion in salinity range less than 1 ppt. Tidal pumping as oppose to the estuarine circulation is the more dominant factor in the maximum formation as the salt water is totally excluded at low water. (Author)

232

The tidal asymmetries and residual flows in Ems Estuary  

Science.gov (United States)

A 3D unstructured-grid numerical model of the Ems Estuary is presented. The simulated hydrodynamics are compared against tidal gauge data and observations from research cruises. A comparison with an idealized test reveals the capability of the model to reproduce the secondary circulation patterns known from theoretical results. The simulations prove to be accurate and realistic, confirming and extending findings from earlier observations and modeling studies. The basic characteristics of dominant physical processes in the estuary such as tidal amplification, tidal damping, overtide generation, baroclinicity and internal mixing asymmetry are quantified. The model demonstrates an overall dominance of the flood currents in most of the studied area. However, the hypsometric control in the vicinity of Dollart Bay reverses this asymmetry, with the ebb currents stronger than the flood ones. Small-scale bathymetric characteristics and baroclinicity result in a very complex interplay between dominant physical mechanisms in different parts of the tidal channels and over the tidal flats. Residual flow reveals a clear overturning circulation in some parts of the estuary which is related to a mixing asymmetry between flood and ebb currents. We demonstrate that while areas close to the tidal river exhibit overall similarity with density controlled estuarine conditions, in large areas of the outer estuary barotropic forcing and complex bathymetry together with the density distribution affect substantially the horizontal circulation.

Pein, Johannes Ulrich; Stanev, Emil Vassilev; Zhang, Yinglong Joseph

2014-12-01

233

Importance of geometric characteristics for salinity distribution in convergent estuaries  

Science.gov (United States)

SummaryWe investigate changes in geometric characteristics and related processes of the longitudinal salinity distribution in an alluvial estuarine system. We focus on tide-dominated estuaries, which are usually characterized by a convergent shape, and analyze effects of intra-tidal and sub-tidal variations of the geometric characteristics on the salinity distribution. A theoretical salt intrusion model is applied to the Red River estuarine system (RRES), where the channel shape and size greatly vary as a function of tidal amplitudes. The model was originally derived for single-channel estuaries by considering the cross-sectional profile only at tidally averaged condition. This assumption makes the application of the model to the RRES a challenging task. In this paper, we split the estuary branch into multi-connected segments to describe the longitudinal variation of geometric characteristics. In addition, by prescribing geometric parameters to exponentially vary under different tidal conditions, we were able to estimate spatial and temporal changes in the salinity distribution. A series of field surveys for salinity in the dry season of 2006, 2008, and 2009 were used to examine and validate the method. We found that the modified model described salt intrusion with a good fit between the computed and measured salinity. This finding provides a key for the further investigation of salt intrusion for estuaries having complex geometry.

Nguyen, Duc H.; Umeyama, Motohiko; Shintani, Tetsuya

2012-07-01

234

Water and suspended sediment dynamics in the Sungai Selangor estuary  

International Nuclear Information System (INIS)

Observations of salinity, temperature, suspended sediment concentration (SSC) and tidal current velocity were made in the lower and along the longitudinal axis sungai Selangor estuary over near-spring cycles. The variations of these parameters at the measurement stations and along the channel are presented to illustrate the water and sediment dynamics in the estuary. The results shows that the Sungai Selangor estuary changes from a partially-mixed type during neaps to a well-mixed one during springs. promoted by stronger tidal energy during the higher tidal ranges. The strong neap density stratification is also promoted by the high river discharges during the measurement period maximum concentration of suspended sediment 2000 mg,'/) occurs during maximum current velocities both during flood and ebb. The maximum salinity was achieved during high water slack but the salt water was totally flushed out of estuary during low water springs. The longitudinal axis measurement indicates that a partially-developed zone of turbidity maximum with a sediment concentration over 1000 mg/l was observed at the limit of salt water intrusion in salinity range less than 1 ppt. Tidal pumping as oppose to the estuarine circulation is the more dominant factor in the maximum formation as the salt water is totally excluded at low water. (author)

235

PEAK STREAMFLOW - VIRGINIA PORTION OF THE ALBEMARLE-PAMLICO ESTUARY  

Science.gov (United States)

Peak discharge data from the U.S. Geological Survey (http://waterdata.usgs.gov/nwis-w/VA) for gaging stations within the Virginia portion of the Albemarle-Pamlico Estuary watershed. Record dates vary by gaging station. Data for each station are located in a text file named by sta...

236

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

237

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...

238

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.

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

2012-09-01

239

The dynamics of a frictionally-dominated Amazonian estuary  

Directory of Open Access Journals (Sweden)

Full Text Available 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.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 revelam 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.

Nils Edvin Asp

2012-09-01

240

Biogeochemistry of the Kem' River estuary, White Sea (Russia  

Directory of Open Access Journals (Sweden)

Full Text Available The biogeochemistry of the river-sea interface was studied in the Kem' River (the largest river flowing to the White Sea from Karelian coast estuary and adjacent area of the White Sea onboard the RV 'Ekolog' in summer 2001, 2002 and 2003. The study area can be divided into 3 zones: I - the estuary itself, with water depth from 1 to 5m and low salinity in the surface layer (salinity is lower than 0.2psu in the Kem' River and varies from 15 to 20psu in outer part of this zone; II - the intermediate zone with depths from 5 to 10m and salinity at the surface from 16 to 22psu; III - the marine zone with depths from 10 to 29 m and salinity 21-24.5psu. Highest concentrations of the suspended particulate matter (SPM were registered in the Kem' mouth (5-7mg/l. They sharply decreased to values org to nitrogen (N ratio (Corg/N in both suspended matter and bottom sediments decreases from the river to the marine part of the mixing zone (from 8.5 to 6.1 in the suspended matter and from 14.6 to 7.5 in the bottom sediments, demonstrating that content of terrestrial-derived organic matter decreases and content of marine organic matter increases from the river mouth to the sea. The Kem' estuary exhibits a similar character of biogeochemial processes as in the large Arctic estuaries, but the scale of these processes (amount of river input of SPM, POC, area of estuaries is different.

V. R. Shevchenko

2005-01-01

241

Salinity and turbidity distributions in the Brisbane River estuary, Australia  

Science.gov (United States)

The Brisbane River estuary (BRE) in Australia not only plays a vital role in ecosystem health, but is also of importance for people who live nearby. Comprehensive investigations, both in the short- and long-term, into the salinity and turbidity distributions in the BRE were conducted. Firstly, the analysis of numerical results revealed that the longitudinal salinity varied at approximately 0.45 and 0.61 psu/h during neap and spring tides, respectively. The turbidity stayed at a higher level and was less impacted by tide in the upper estuary, however, the water cleared up while the tide changed from flood to ebb in the mid and lower estuary. The second investigation into the seasonal variations of salinity and turbidity in the BRE was conducted, using ten-year field measurement data. A fourth-order polynomial equation was proposed, describing the longitudinal variation in salinity dilution changes as the upstream distance in the BRE during the wet and dry seasons. From the observation, the mid and upper estuaries were vertically well-mixed during both seasons, but the lower BRE was stratified, particularly during the wet season. The estuary turbidity maximum (ETM) zone was about 10 km longer during the wet season than the dry season. Particular emphasis was given to the third investigation into the use of satellite remote sensing techniques for estimation of the turbidity level in the BRE. A linear relationship between satellite observed water reflectance and surface turbidity level in the BRE was validated with an R2 of 0.75. The application of satellite-observed water reflectance therefore provided a practical solution for estimating surface turbidity levels of estuarine rivers not only under normal weather conditions, but also during flood events. The results acquired from this study are valuable for further hydrological research in the BRE and particularly prominent for immediate assessment of flood impacts.

Yu, Yingying; Zhang, Hong; Lemckert, Charles

2014-11-01

242

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

243

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

244

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

245

Historical Research in the Southwest: Ignored and Undervalued. Commentary.  

Science.gov (United States)

Comments on the article, "The Unexplored: Art Education Historians' Failure to Consider the Southwest" (Peter Smith). Discusses art education sources on historical research that were omitted from the article. Addresses the difficulties in the value placed on historical research in the southwestern United States. (CMK)

Stokrocki, Mary

2000-01-01

246

Effects of Short Time Variation in the River Discharge on the Salt Wedge Intrusion in the Yura Estuary, a Micro Tidal Estuary, Japan  

OpenAIRE

A numerical model was developed to investigate salinity distribution in the Yura Estuary, a micro tidal estuary in Japan. The model results show that the salinity distribution as represented by salt wedge intrusion agreed well with field observations. In addition to the seasonal variation, the salt wedge responds over short time scales acc...

Yoh Yamashita; Masahiro Ueno; Akihide Kasai; Tatsuhiro Funahashi

2013-01-01

247

Estuary Data Mapper: A Stand-Alone Tool for Geospatial Data Access, Visualization and Download for Estuaries and Coastal Watersheds of the United States. (UNH)  

Science.gov (United States)

The US EPA Estuary Data Mapper (EDM; http://badger.epa.gov/rsig/edm/index.html) has been designed as a free stand-alone tool for geospatial data discovery, visualization, and data download for estuaries and their associated watersheds in the conterminous United States. EDM requi...

248

Estuary Data Mapper: A Stand-Alone Tool for Geospatial Data Access, Visualization and Download for Estuaries and Coastal Watersheds of the United States  

Science.gov (United States)

The US EPA Estuary Data Mapper (EDM; http://badger.epa.gov/rsig/edm/index.html) has been designed as a free stand-alone tool for geospatial data discovery, visualization, and data download for estuaries and their associated watersheds in the conterminous United States. EDM requi...

249

Response of the turbidity maximum zone to fluctuations in sediment discharge from river to estuary in the Changjiang Estuary (China)  

Science.gov (United States)

In the Changjiang Estuary, interactions between the sea and the river result in the development of a turbidity maximum zone (TMZ). Riverine sediments are an important source for TMZ formation. Since the 1960s, sediment discharge from the river basin to the estuary has decreased due to dam construction, water and soil conservation, and water diversion projects. Thirty-two Landsat images of the estuary, covering the period from 1979 to 2008, were collected to identify the TMZ response to sediment decline. A threshold value of suspended sediment concentration (SSC) of 0.7 kg/m3, corresponding to a spectrum reflectance of 5% of Landsat MSS band 7 and 7% of Landsat TM/ETM band 4, was used to identify the Changjiang Estuary TMZ. The TMZ area was then extracted from each image to investigate its temporal and spatial variations during the past 30 years. The images were grouped into five time series; the average TMZ area of each series was estimated. The results show that the TMZ area declined 23% from series (a) to series (e), responding to a 77% reduction in riverine sediment discharge. In addition, the TMZ had strong seasonal and tidal variations; it was generally larger during flood seasons than during dry seasons and during spring tides compared to neap tides. The spring/neap tidal cycle played a more important role in TMZ change than did the seasonal cycle. Due to the continued reduction of sediment discharge to the estuary resulting from dams already constructed and to those that will be constructed upstream in the Changjiang River, it is predicted that the TMZ area will continue decreasing and that the re-suspension of local sediments will play a more important role in the formation of the TMZ.

Jiang, Xuezhong; Lu, Bing; He, Yuhong

2013-10-01

250

Analytical and numerical analysis of tides and salinities in estuaries; part I: tidal wave propagation in convergent estuaries  

Science.gov (United States)

Analytical solutions of the momentum and energy equations for tidal flow are studied. Analytical solutions are well known for prismatic channels but are less well known for converging channels. As most estuaries have a planform with converging channels, the attention in this paper is fully focused on converging tidal channels. It will be shown that the tidal range along converging channels can be described by relatively simple expressions solving the energy and momentum equations (new approaches). The semi-analytical solution of the energy equation includes quadratic (nonlinear) bottom friction. The analytical solution of the continuity and momentum equations is only possible for linearized bottom friction. The linearized analytical solution is presented for sinusoidal tidal waves with and without reflection in strongly convergent (funnel type) channels. Using these approaches, simple and powerful tools (spreadsheet models) for tidal analysis of amplified and damped tidal wave propagation in converging estuaries have been developed. The analytical solutions are compared with the results of numerical solutions and with measured data of the Western Scheldt Estuary in the Netherlands, the Hooghly Estuary in India and the Delaware Estuary in the USA. The analytical solutions show surprisingly good agreement with measured tidal ranges in these large-scale tidal systems. Convergence is found to be dominant in long and deep-converging channels resulting in an amplified tidal range, whereas bottom friction is generally dominant in shallow converging channels resulting in a damped tidal range. Reflection in closed-end channels is important in the most landward 1/3 length of the total channel length. In strongly convergent channels with a single forward propagating tidal wave, there is a phase lead of the horizontal and vertical tide close to 90o, mimicking a standing wave system (apparent standing wave).

van Rijn, Leo C.

2011-11-01

251

Circulation and suspended particulate matter transport in a tidally dominated estuary: caravelas estuary, Bahia, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A circulação e o transporte de material particulado em suspensão no Estuário de Caravelas são pesquisados. Dados quase-sinóticos hidrográficos, de correntes (velocidade e transporte de volume com ADCP) e de material particulado em suspensão, foram medidos em intervalos horários durante um ciclo semi [...] diurno de maré de sizígia, em duas seções transversais na Boca do Tomba e na Barra Velha e também em seções longitudinais na baixa-mar e na preamar. Na primeira transversal as correntes máximas de vazante (-1,50 m s-1) foram quase duas vezes mais intensas do que na seção transversal mais larga e rasa Barra Velha, (-0,80 m s-1) e as maiores velocidades das correntes de enchente foram de 0,75 m s-1 e 0,60 m s-1, respectivamente. Devido à grande intensidade das correntes de maré, nas duas seções transversais a salinidade apresentou-se fracamente estratificada, sendo classificadas com o Diagrama Estratificação-circulação do Tipo 2a (parcialmente misturada e fraca estratificação vertical) e do Tipo 1a (bem misturada). Os transportes de volume foram muito próximos, variando de -3.500 m³ s-1 a 3.100 m³ s-1, na vazante e na enchente, respectivamente, com um transporte de volume residual igual a -630 m³ s-1. A concentração do material particulado em suspensão (MPS) esteve fortemente relacionado à variação da maré, decrescendo estuário acima de 50 mg.L-1, na boca do estuário, para 10 mg.L-1 para distâncias de 9 km e 16 km nos experimentos na baixa-mar e preamar, respectivamente. O transporte residual de MPS foi estuário abaixo com uma taxa estimada em -18 ton por ciclo de maré. Abstract in english The circulation and transport of suspended particulate matter in the Caravelas Estuary are assessed. Nearly-synoptic hourly hydrographic, current (ADCP velocity and volume transport) and suspended particulate matter data were collected during a full semidiurnal spring tide, on the two transects Boca [...] do Tomba and Barra Velha and on longitudinal sections at low and high tide. On the first transect the peak ebb currents (-1.5 ms-1) were almost twice as strong as those of the wider and shallow Barra Velha inlet (-0.80 ms-1) and the peak flood currents were 0.75 and 0.60 ms-1, respectively. Due to the strong tidal currents both inlets had weak vertical salinity stratification and were classified with the Stratification-circulation Diagram as Type 2a (partially mixed-weakly stratified) and Type 1a (well mixed). Volume transports were very close, ranging from -3,500 to 3,100 m³s-1 at the ebb and flood, respectively, with a residual -630 m³s-1. The concentration of the suspended particulate matter was closely related to the tidal variation and decreased landwards from 50 mg.L-1 at the estuary mouth, to 10 mg.L-1 at distances of 9 and 16 km for the low and high tide experiments, respectively. The total residual SPM transport was out of the estuary at rates of -18 tons per tidal cycle.

Carlos Augusto França, Schettini; Luiz Bruner de, Miranda.

2010-03-01

252

Circulation and suspended particulate matter transport in a tidally dominated estuary: caravelas estuary, Bahia, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available The circulation and transport of suspended particulate matter in the Caravelas Estuary are assessed. Nearly-synoptic hourly hydrographic, current (ADCP velocity and volume transport and suspended particulate matter data were collected during a full semidiurnal spring tide, on the two transects Boca do Tomba and Barra Velha and on longitudinal sections at low and high tide. On the first transect the peak ebb currents (-1.5 ms-1 were almost twice as strong as those of the wider and shallow Barra Velha inlet (-0.80 ms-1 and the peak flood currents were 0.75 and 0.60 ms-1, respectively. Due to the strong tidal currents both inlets had weak vertical salinity stratification and were classified with the Stratification-circulation Diagram as Type 2a (partially mixed-weakly stratified and Type 1a (well mixed. Volume transports were very close, ranging from -3,500 to 3,100 m³s-1 at the ebb and flood, respectively, with a residual -630 m³s-1. The concentration of the suspended particulate matter was closely related to the tidal variation and decreased landwards from 50 mg.L-1 at the estuary mouth, to 10 mg.L-1 at distances of 9 and 16 km for the low and high tide experiments, respectively. The total residual SPM transport was out of the estuary at rates of -18 tons per tidal cycle.A circulação e o transporte de material particulado em suspensão no Estuário de Caravelas são pesquisados. Dados quase-sinóticos hidrográficos, de correntes (velocidade e transporte de volume com ADCP e de material particulado em suspensão, foram medidos em intervalos horários durante um ciclo semidiurno de maré de sizígia, em duas seções transversais na Boca do Tomba e na Barra Velha e também em seções longitudinais na baixa-mar e na preamar. Na primeira transversal as correntes máximas de vazante (-1,50 m s-1 foram quase duas vezes mais intensas do que na seção transversal mais larga e rasa Barra Velha, (-0,80 m s-1 e as maiores velocidades das correntes de enchente foram de 0,75 m s-1 e 0,60 m s-1, respectivamente. Devido à grande intensidade das correntes de maré, nas duas seções transversais a salinidade apresentou-se fracamente estratificada, sendo classificadas com o Diagrama Estratificação-circulação do Tipo 2a (parcialmente misturada e fraca estratificação vertical e do Tipo 1a (bem misturada. Os transportes de volume foram muito próximos, variando de -3.500 m³ s-1 a 3.100 m³ s-1, na vazante e na enchente, respectivamente, com um transporte de volume residual igual a -630 m³ s-1. A concentração do material particulado em suspensão (MPS esteve fortemente relacionado à variação da maré, decrescendo estuário acima de 50 mg.L-1, na boca do estuário, para 10 mg.L-1 para distâncias de 9 km e 16 km nos experimentos na baixa-mar e preamar, respectivamente. O transporte residual de MPS foi estuário abaixo com uma taxa estimada em -18 ton por ciclo de maré.

Carlos Augusto França Schettini

2010-03-01

253

Heavy Metallic Element Distribution in Cisadane River Estuary's Water and Sediment  

Directory of Open Access Journals (Sweden)

Full Text Available Observation of heavy metallic elements in Cisadane River Estuary has been done in July and November 2005. The results show that heavy metallic elements content in seawater is lower and still below the treshold value stated by government for fisheries. There was an indication of heavy metallic elements on sediment. Distribution of Pb on July and of Cu on November 2005 were found higher near the coast and decrease towards the sea, and commonly were found in front of estuary such as Cisadane, Muara Saban and Tanjung Pasir. High Pb and Zn distributions on November 2005 were found only in front of Cisadane estuary. Cd distribution of Cisadane estuary was constant at all station but did not show any correlation with the distance of station and estuary. The Cd content on July and November 2005 is lower than 0,001 ppm. Generally, heavy metallic elements content have a uniform distribution at all stations inspite of its distance to estuary.

M. Taufik Kaisupy

2006-04-01

254

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

255

Identifying conservation priority estuaries in British Columbia with a graph-based measure of landscape connectivity  

OpenAIRE

Predicting and ranking ecologically important estuaries supports estuary conservation efforts in British Columbia. Connectivity, an indicator of ecological importance, is not a component of rankings created to date by conservationists. I used graph theory to describe estuarine connectivity for three migratory birds: Dusky Canada Geese, Western Sandpipers, and White-winged Scoters and ranked estuaries based on their maintenance of connectivity. I developed seven metrics that quantified the imp...

Harrold, Lydia Rebecca

2006-01-01

256

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

OpenAIRE

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

257

Abundance and Size of Gulf Shrimp in Louisiana's Coastal Estuaries following the Deepwater Horizon Oil Spill  

OpenAIRE

The Deepwater Horizon oil spill impacted Louisiana's coastal estuaries physically, chemically, and biologically. To better understand the ecological consequences of this oil spill on Louisiana estuaries, we compared the abundance and size of two Gulf shrimp species (Farfantepeneus aztecus and Litopeneus setiferus) in heavily affected and relatively unaffected estuaries, before and after the oil spill. Two datasets were used to conduct this study: data on shrimp abundance and size before the s...

Ham, Joris L.; Mutsert, Kim

2014-01-01

258

Tidal exchange of larvae of Sesarma catenata (Decapoda, Brachyura) in the Swartkops estuary, South Africa  

OpenAIRE

ENGLISH ABSTRACT: The tidal exchange of larvae of the salt-marsh grapsid crab Sesarma catenata was studied in the Swartkops estuary, a tidally driven, shallow estuary in Algoa Bay, South Africa. Plankton samples were collected bimonthly during spring and neap tides from October to March at the tidal inlet. Samples were collected hourly for 25 h in February, and for 13 h in all other months. Hourly estimates of water flux through the tidal inlet of the estuary were calculat...

Pereyra Lago, R.

2012-01-01

259

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

OpenAIRE

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 under...

Wim Kimmerer

2004-01-01

260

Hydrodynamics and suspended sediment transport in the Camboriú estuary - Brazil: pre jetty conditions  

OpenAIRE

Estuarine hydrodynamics is a key factor in the definition of the filtering capacity of an estuary and results from the interaction of the processes that control the inlet morphodynamics and those that are acting in the mixing of the water in the estuary. The hydrodynamics and suspended sediment transport in the Camboriú estuary were assessed by two field campaigns conducted in 1998 that covered both neap and spring tide conditions. The period measured represents the estuarine hydrodynamics a...

Eduardo Siegle; Schettini, Carlos A. F.; Klein, Antonio H. F.; Toldo Jr, Eli?rio E.

2009-01-01

261

Cytotoxic and genotoxic potential of sediments from the Portuguese Mira-River Estuary  

OpenAIRE

The Mira-River Estuary (SW Portugal) although being a protected natural area has been affected by urban pollution from the village of Vila Nova de Milfontes (VNMF) and by contaminants from farming and aquaculture activities. The present study is part of a broader project comprising the evaluation of environmental and human health risks from potentially contaminated estuaries and aims to assess the cytotoxic and genotoxic potential of sediments from the Mira-River Estuary. Sediments were c...

Pinto, Miguel; Louro, Henriqueta; Costa, Pedro Manuel; Costa, Maria Helena; Caeiro, Sandra; Lavinha, Joa?o; Silva, Maria Joa?o

2013-01-01

262

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.)

263

Using a Multi-Component Indicator Toward Reducing Phytoplankton Bloom Occurrences in the Swan River Estuary  

Science.gov (United States)

The Swan River estuary is an icon of the city of Perth, Western Australia, running through the city centre and dividing the northern from the southern part of the city. However, frequent phytoplankton blooms have been observed in the estuary as a result of eutrophication. The Index of Sustainable Functionality (ISF), a composite index able to indicate for sustainable health of the estuary, was applied, taking into account the hydrology and highly seasonal nature of the estuary to inform the management of the estuary, towards the aim of reducing bloom occurrences. The study period was from the beginning of intensive monitoring in 1995 to mid-2009. The results emphasize the importance of physical controls on the ecology of the estuary. No significant trend in the estuary's low functionality was found, indicating that despite extensive restoration efforts, the frequency of algal bloom occurrences has remained relatively stationary and other mitigating factors have maintained an annual average ISF value at around 70 % functionality. We identified that the low flow season consistently performs the worst, with (high) temperature found as the most dominant variable for phytoplankton growth and bloom. Thus in managing the estuary, vigilance is required during periods of high temperature and low flow. Focusing on the risk of phytoplankton bloom, a nutrient reduction program that is in place is a long term solution due to high concentrations in the estuary. Other management measures need to be considered and adopted to effectively reduce the occurrences of future phytoplankton blooms.

Kristiana, Ria; Antenucci, Jason P.; Imberger, Jorg

2012-08-01

264

Distribution and sources of particulate organic matter in the Indian monsoonal estuaries during monsoon  

Science.gov (United States)

distribution and sources of particulate organic carbon (POC) and nitrogen (PN) in 27 Indian estuaries were examined during the monsoon using the content and isotopic composition of carbon and nitrogen. Higher phytoplankton biomass was noticed in estuaries with deeper photic zone than other estuaries receiving higher suspended matter. The ?13CPOC and ?15NPN data suggest that relatively higher ?13CPOC (-27.9 to -22.6‰) and lower ?15NPN (0.7 to 5.8‰) were noticed in the estuaries located in the northern India, north of 16°N, and lower ?13CPOC (-31.4 to -28.2‰) and higher ?15NPN (5 to 10.3‰) in the estuaries located in the southern India. This is associated with higher Chl a in the northern than southern estuaries suggesting that in situ production contributed significantly to the POC pool in the former, whereas terrestrial sources are important in the latter estuaries. The spatial distribution pattern of ?15NPN is consistent with fertilizer consumption in the Indian subcontinent, which is twice as much in the northern India as in the south whereas ?13CPOC suggests that in situ production is a dominant source in the southern and terrestrial sources are important in the northern estuaries. Based on the Stable Isotope Analysis in R model, 40-90% (70-90%) of organic matter is contributed by C3 plants (freshwater algae) in the estuaries located in the northern (southern) India.

Sarma, V. V. S. S.; Krishna, M. S.; Prasad, V. R.; Kumar, B. S. K.; Naidu, S. A.; Rao, G. D.; Viswanadham, R.; Sridevi, T.; Kumar, P. P.; Reddy, N. P. C.

2014-11-01

265

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

OpenAIRE

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...

Priya K L; Jegathambal, P.; James, E. J.

2012-01-01

266

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

267

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

268

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

269

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

270

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

271

Effects of Prevailing Winds on Turbidity of a Shallow Estuary  

OpenAIRE

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

272

Suspended matter and heavy metal content of the Elbe Estuary  

International Nuclear Information System (INIS)

(1) In the River Elbe estuary there is a turbidity zone which is closely bound to the region of brackish waters. Its suspended matter content changes strongly with the tidal rhythm. Suspended matter and river bed sediments influence each other by exchanging their particles. Owing to that mechanism, the heavy metal ions bound or taken up by the suspended matter (sorption) enter the sediments. To obtain an estimation of the estuary's ability to cope with ( self purify ) a strong burden of industrial wastes, it is neccessary to take into consideration the absorbing capacity of both the mean suspension load and the sediments. (2) The concentration of nearly all heavy metal ions investigated in the suspension load decreases remarkably at the very beginning of the turbid zone already, in the Hamburg region. It indicates that the binding process are going on very rapidly and that the metal ion absorbing capacity of the Elbe estuary still requires only the first few miles of this self purification system. The results gained indicate that the suspended matter in Hamburg waters could bind or take up more heavy metal ions than are discharged into this area. (3) The concentration of most ions bound to the suspension material correlates very well with the grain size distribution of the (anorganic) particles. The concentration values decrease along the estuary and lead to a continuous transition to the values of the open sea. Cu, Ni and Cd appear to be captured preferably by organiappear to be captured preferably by organic suspended matter. This behaviour, however, is solely restricted to the turbid zone. In the open sea, after oxidation of the binding organic material, Cu and Ni correspond to the anorganic grain size distribution. (orig./HP)

273

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

274

Estuaries from a meiofaunal perspective: biodiversity patterns of benthic nematodes  

OpenAIRE

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

275

Residence time of water in the Mondego estuary (Portugal)  

Science.gov (United States)

The residence time of water is widely used as an indicator of how long a substance will remain in an estuary, a harbour, or a lagoon, and it is used to enable comparisons among different water bodies. In this work, the residence time in the Mondego Estuary, Portugal, is calculated by using two methodologies: the first one is based on field data and a freshwater fraction model, and the second one is based on a Lagrangian transport model. The Lagrangian model is coupled to a two-dimensional hydrodynamic numerical model that solves the depth-averaged advection and diffusion equations. Boundary conditions are provided by the Portuguese Coastal Operational Model, downscaled by using four nested domains with increasing resolution from the large to the local scale. The spatial variation of the residence time is characterized by subdividing the Mondego Estuary into boxes. The observed average salinity for each box is applied to the freshwater fraction model. With the Lagrangian model, boxes are filled with tracers and the path of the particles passing through them is quantified. The overall results of the two methodologies are similar, with a value of the residence time varying over the year between 1 and 12 days computed with the Lagrangian transport model and 2 and 9 days with the freshwater fraction model. Several scenarios were built by applying the Lagrangian transport model to investigate the history of water renewal and the influence of freshwater inflows and geomorphologic factors on the residence time. The overall results indicate that freshwater inflow is the main factor influencing the residence time. The analysis of the history of the water renewal was carried out by calculating the water exchange among boxes inside the estuary, pointing to the river flow as the main factor contributing to the water renewal of boxes.

Ascione Kenov, Isabella; Garcia, Ana Carla; Neves, Ramiro

2012-06-01

276

Tritium in the Savannah River estuary and adjacent marine waters  

International Nuclear Information System (INIS)

The purpose of this paper is to report the results of a study on the tritium distribution in the Savannah River estuary, inland marine waters, and coastal waters. Tritium is released to surface streams from the Savannah River Plant reactor area fuel and target storage basins, and indirectly by discharge to seepage basins with a fraction ultimately discharged to streams by groundwater transport. Previously tritium has been used to determine the travel time and dispersion coefficients for the Savannah River

277

Shellfish culture in estuary zones and the sanitary restrictions  

OpenAIRE

The nutritional requirements of shellfish are satisfied by the phytoplankton and the nutrients of the estuary waters. Bivalves (mussels, oysters, clams, cockles, scallops and razors) can be there produced. The shellfish are cultured on the sea bottom or suspended. For shellfish culture no food is required and the investment cost is low. If the quality of the water is high then they can be considered as bio or organic products. The disadvantages concern their sanitary status (contamination by ...

Angelidis, Panagiotis

2007-01-01

278

Light-induced bird strikes on vessels in Southwest Greenland  

DEFF Research Database (Denmark)

Light-induced bird strikes are known to occur when vessels navigate during darkness in icy waters using powerful searchlight. In Southwest Greenland, which is important internationally for wintering seabirds, we collected reports of incidents of bird strikes over 2–3 winters (2006–2009) from navy vessels, cargo vessels and trawlers (total n = 19). Forty-one incidents were reported: mainly close to land (<4 km, 78%), but one as far offshore as 205 km. Up to 88 birds were reported killed in a single incident. All occurred between 5 p.m. and 6 a.m. and significantly more birds were involved when visibility was poor (snow) rather than moderate or good. Among five seabird species reported, the common eider (Somateria mollissima) accounted for 95% of the bird casualties. Based on spatial analyses of data on vessel traffic intensity and common eider density we are able to predict areas with high risk of bird strikes in Southwest Greenland.

Merkel, Flemming Ravn; Johansen, Kasper Lambert

2011-01-01

279

Circulation dynamics and salt balance in a lagoonal estuary  

Science.gov (United States)

Albemarle-Pamlico Sound (APS) is a shallow lagoonal estuary connected to the Atlantic Ocean through narrow inlets. The circulation dynamics and salt balance in this estuary are investigated using a numerical model. Although the vertical stratification is weak, the mean flow features a two-layer gravitational circulation with speeds reaching several centimeters per second. Analysis of the momentum budget shows a primary balance among the barotropic pressure gradient as a result of sea level slope, the baroclinic pressure gradient due to horizontal salinity gradients, and stress divergence. The salt budget for APS is determined by the balance between river flow and salt exchange through the inlets. At the inlets, the salt flux resulting from estuarine shear flow is much weaker than that due to tidal pumping and subtidal barotropic transport. Tidal pumping produces a net influx of salt into APS: Strong flood currents push oceanic water into the estuary through a propagating density front, whereas ebb currents advect lighter estuarine water over denser bottom water. The salt flux due to the subtidal barotropic transport across the inlets shows large temporal fluctuations associated with wind events. This transport can be either a source or sink of salt to APS and correlates well with the sea level difference across each inlet. Higher-sea level on the shelf leads to an intrusion of oceanic water into APS whereas higher-sea level inside APS leads to a withdrawal of estuarine water to the shelf.

Jia, Peng; Li, Ming

2012-01-01

280

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.

281

Counting on ?-diversity to safeguard the resilience of estuaries.  

Science.gov (United States)

Coastal ecosystems are often stressed by non-point source and cumulative effects that can lead to local-scale community homogenisation and a concomitant loss of large-scale ecological connectivity. Here we investigate the use of ?-diversity as a measure of both community heterogeneity and ecological connectivity. To understand the consequences of different environmental scenarios on heterogeneity and connectivity, it is necessary to understand the scale at which different environmental factors affect ?-diversity. We sampled macrofauna from intertidal sites in nine estuaries from New Zealand's North Island that represented different degrees of stress derived from land-use. We used multiple regression models to identify relationships between ?-diversity and local sediment variables, factors related to the estuarine and catchment hydrodynamics and morphology and land-based stressors. At local scales, we found higher ?-diversity at sites with a relatively high total richness. At larger scales, ?-diversity was positively related to ?-diversity, suggesting that a large regional species pool was linked with large-scale heterogeneity in these systems. Local environmental heterogeneity influenced ?-diversity at both local and regional scales, although variables at the estuarine and catchment scales were both needed to explain large scale connectivity. The estuaries expected a priori to be the most stressed exhibited higher variance in community dissimilarity between sites and connectivity to the estuary species pool. This suggests that connectivity and heterogeneity metrics could be used to generate early warning signals of cumulative stress. PMID:23755252

de Juan, Silvia; Thrush, Simon F; Hewitt, Judi E

2013-01-01

282

Hydromorphological mechanisms leading to hypoxia off the Changjiang estuary.  

Science.gov (United States)

Based on the seasonal surveying data and long-term data, the annual changes in the geographical locations, occurrence frequency, affected areas and the minimum oxygen level as well as the formation mechanism of the summer hypoxia off the Changjiang estuary are summarized and discussed in this paper. The historical data indicates that there were episodes of hypoxia in the past 50 years but not every year, and the event of summer hypoxia could be traced back to as early as late 1950s off the Changjiang estuary. The minimum oxygen levels in the hypoxia zone did not show any decline in the past 50 years, but all the events with large size of affected area (>5000km(2)) were observed after the late 1990s, suggesting an enlarging trend. The author argues that the development of summer hypoxia off the Changjiang estuary was related not only to stratification and input of suspended particulate matter, but also to the inflow of Taiwan warm current water as well as the bottom topography. PMID:19070359

Wang, Baodong

2009-02-01

283

Use of Rare-Earth Elements as Tracers in Estuaries  

International Nuclear Information System (INIS)

For large hydrology systems, such as estuaries, the method of stable-isotope tracing with post-sampling activation analysis shows much promise. The method retains the inherent sensitivity of radiation measurement without the concomitant chemical problems of dyes and radiation problems of radioisotope tracers. The rare-earth elements possess favourable nuclear, chemical, physical, and low natural abundance properties which make them suitable as a tracer for flow and dispersion studies in estuaries. Post-sample treatment of irradiation in a 10-kW nuclear reactor, radiochemical group separation, and gamma-ray spectroscopy yields detection limits of 1 ng for europium and 20 ng for lanthanum. Its use has been tested in the San Francisco Bay in which the background concentration of lanthanum is 180 ng/I and of europium 12 ng/l. The method can be used for tracing hydraulic flow or for persistence studies of suspended solids or settleable solid components in the estuary. The method competes favourably in cost, especially as the scale of the system increases. As many as six rare-earth elements can be measured simultaneously. They can be used in conjunction with radioactive rare-earth elements to extend tracing time or dilution range when the total amount of radiotracer is limited. (author)

284

NCLB: Local implementation and impact in southwest Washington state.  

OpenAIRE

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

285

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

286

Electromagnetic Borehole Flowmeter Testing at the Southwest Plume Test Pad  

Energy Technology Data Exchange (ETDEWEB)

Multiple-well aquifer tests were recently conducted at the Southwest Plume Test Pad near the Burial Ground Complex (BGC) in accordance with the BGC Field Investigation Plan (WSRC, 1999). The pumping tests were performed in the Upper Three Runs and Gordon aquifers in February and March of 1999. The tests provide reliable estimates of horizontal conductivity averaged over aquifer thickness, and a relatively large horizontal zone of influence.

Flach, G.P.

2001-01-29

287

Water, climate change, and sustainability in the southwest  

OpenAIRE

The current Southwest drought is exceptional for its high temperatures and arguably the most severe in history. Coincidentally, there has been an increase in forest and woodland mortality due to fires and pathogenic outbreaks. Although the high temperatures and aridity are consistent with projected impacts of greenhouse warming, it is unclear whether the drought can be attributed to increased greenhouse gasses or is a product of natural climatic variability. Climate models indicate that the 2...

Macdonald, Glen M.

2010-01-01

288

Epidemiological evaluation of onchocerciasis along Ogun River System, southwest Nigeria  

OpenAIRE

Background & objective: Epidemiological studies were carried out to assess the prevalence and communitymicrofilarial load (CMFL) of onchocerciasis after repeated annual treatment with ivermectin along Ogun riverSystem, southwest Nigeria.Method: Skin snips were taken from consented participants in 11 selected communities along the River system.The microfilarial load of the community was estimated.Results: The prevalence and CMFL varied significantly in the communities (p <0.05). The prevalenc...

S O Sam-wobo, M. A. Adeleke

2012-01-01

289

Marine mammal strandings in the New Caledonia region, Southwest Pacific  

OpenAIRE

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

290

Evaluation of agricultural extension and delivery services in southwest Nigeria  

OpenAIRE

The study on evaluation of agricultural extension and delivery services was carried out in Southwest, Nigeria. The study affirms that participation of people in the achievement of rural development programs in Nigeria, agricultural and non-agricultural, is faced with great challenges. The importance of extension for rural development has been valued quite differently over the course of Nigeria’s rural development efforts. Increasingly, technical change has been recognized as a major pre-req...

Ogunsumi L.O.; Abegunde B.O.

2011-01-01

291

The chimpanzees of Oluwa Forest Reserve, southwest Nigeria  

OpenAIRE

The lack of accurate information on the population of chimpanzees (Pan troglodytes) is a cause for concern on their conservation and management in Southwest Nigeria. We conducted surveys on the chimpanzees of Oluwa Forest Reserve, Ondo State between the month of September 2011 and February 2012. We used the combination of recce survey and GIS mapping to determine Chimpanzees’ locations in the reserve. Chimpanzee distribution was confined to the central portion of the OA2 axis of the res...

Ogunjemite, B. G.; Olaniyi, O. E.

2012-01-01

292

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

293

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

294

Exploring new drilling prospects in the southwest Pacific  

OpenAIRE

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 the...

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

2014-01-01

295

Premarital sexual activities in an urban society of Southwest- Nigeria  

OpenAIRE

Premarital sex is associated with the phenomenon of teenage and unintended pregnancies, abortion, the spread of STIs and HIV. The major objective of this study was the investigation of premarital sexual activities in an urban society of South-west Nigeria. The aim is to quantify premarital sexual behaviour in the study population. Interview method was used to collect information from a sample of 2,500 women within the age bracket of 15-49 years. Percentage distribution and logistic regression...

Isreal Sunday Akinde; Olubunmi Akinsanya Alo

2010-01-01

296

High Cretaceous biostratigraphy at Tercis, south-west France  

OpenAIRE

The limestones in Tercis Quarry, Dax (Landes), south-west France expose high Upper Campanian and low Lower Maastrichtian in which ammonites occur and inoceramids and Echinocorys are common. The vertical ranges of these groups, combined with some evidence from other echinoids and the nannoplankton, provide correlations with the Biscay region, eastern England, north Germany and Poland. The appearance at Tercis of the much quoted Maastrichtian indices Hoploscaphites constrictus and Pachydiscus n...

Hancock, Jm; Peake, Nb; Burnett, J.; Dhondt, Av; Kennedy, Wj; Stokes, Rb

1993-01-01

297

Wolf predation in the Burwash caribou herd, southwest Yukon  

OpenAIRE

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 -...

Gauthier, David A.; Theberge, John B.

1986-01-01

298

Turtle riders: remoras on marine turtles in Southwest Atlantic  

OpenAIRE

An overview is presented for a poorly documented relationship between reef vertebrates in Southwest Atlantic: remoras (Echeneidae) associated with marine turtles. Two remora species (Echeneis naucrates and Remora remora) and four turtle species (Caretta caretta, Chelonia mydas, Eretmochelys imbricata, and Dermochelys coriacea) are here recorded in symbiotic associations in the SW Atlantic. Echeneis naucrates was recorded both on the coast and on oceanic islands, whereas R. remora was recorded...

Ivan Sazima; Alice Grossman

2006-01-01

299

The Southwest Pacific Ocean circulation and climate experiment (SPICE)  

Science.gov (United States)

Southwest Pacific Ocean Circulation and Climate Experiment (SPICE) is an international research program under the auspices of CLIVAR. The key objectives are to understand the Southwest Pacific Ocean circulation and the South Pacific Convergence Zone (SPCZ) dynamics, as well as their influence on regional and basin-scale climate patterns. South Pacific thermocline waters are transported in the westward flowing South Equatorial Current (SEC) toward Australia and Papua-New Guinea. On its way, the SEC encounters the numerous islands and straits of the Southwest Pacific and forms boundary currents and jets that eventually redistribute water to the equator and high latitudes. The transit in the Coral, Solomon, and Tasman Seas is of great importance to the climate system because changes in either the temperature or the amount of water arriving at the equator have the capability to modulate the El Niño-Southern Oscillation, while the southward transports influence the climate and biodiversity in the Tasman Sea. After 7 years of substantial in situ oceanic observational and modeling efforts, our understanding of the region has much improved. We have a refined description of the SPCZ behavior, boundary currents, pathways, and water mass transformation, including the previously undocumented Solomon Sea. The transports are large and vary substantially in a counter-intuitive way, with asymmetries and gating effects that depend on time scales. This paper provides a review of recent advancements and discusses our current knowledge gaps and important emerging research directions.

Ganachaud, A.; Cravatte, S.; Melet, A.; Schiller, A.; Holbrook, N. J.; Sloyan, B. M.; Widlansky, M. J.; Bowen, M.; Verron, J.; Wiles, P.; Ridgway, K.; Sutton, P.; Sprintall, J.; Steinberg, C.; Brassington, G.; Cai, W.; Davis, R.; Gasparin, F.; Gourdeau, L.; Hasegawa, T.; Kessler, W.; Maes, C.; Takahashi, K.; Richards, K. J.; Send, U.

2014-11-01

300

The hydrodynamic response of the York River estuary to Tropical Cyclone Isabel, 2003  

Science.gov (United States)

Hurricane Isabel made landfall along the North Carolina coast on September 18, 2003 (UTC 17:00) and the storm surge exceeded 2.0 m in many areas of the Chesapeake Bay and in the York River estuary. River flooding occurred subsequently, and the peak river discharge reached 317 and 104 m 3 s -1 in the Pamunkey and Mattaponi rivers, respectively. The York River estuary experienced both storm surge and river flooding during the event and the estuary dynamics changed dramatically. This study investigates the hydrodynamics of the York River estuary in response to the storm surge and high river inflows. A three-dimensional model was used to investigate the changes of estuarine stratification, longitudinal circulation, salt flux mechanisms, and the recovery time required for the estuary to return to its naturally evolved condition without the storm. Results show that the salt flux was mainly caused by advection, which was induced by the barotropic gradient during the storm event. The net salt flux increased by a factor of 30 during the rise of the storm surge. However, the large amount of salt transported into the estuary was quickly transported out of the estuary as the barotropic gradient reversed during the descent of the storm surge. Subsequent high freshwater inflow influenced the estuarine circulation substantially. The estuary changed from a partially mixed estuary to a very stratified estuary for a prolonged period. The model results show that it will take about 4 months for the estuary to recover to its naturally evolved salinity distribution after the impacts of the storm surge and freshwater pulse.

Gong, Wenping; Shen, Jian; Reay, William G.

2007-07-01

301

Comment on “A note on salt intrusion in funnel-shaped estuaries: Application to the Incomati estuary, Mozambique” by Brockway et al. (2006)  

Science.gov (United States)

A comment is provided on the paper by Brockway et al. (2006. A note on salt intrusion in funnel-shaped estuaries: application to the Incomati estuary, Mozambique. Estuarine, Coastal and Shelf Science 66, 1-5) on a simple method to determine the salt intrusion in the Incomati estuary. Although this method is able to describe the salt intrusion in the Incomati reasonably well with only limited information, it is demonstrated that with the same data, but a more up-to-date methodology, a better and generally applicable equation could have been obtained.

Savenije, Hubert H. G.

2006-07-01

302

Histochemistry and histology in planktonic ecophysiological processes determination in a temperate estuary (Mondego River estuary, Portugal)  

Science.gov (United States)

Zooplankton communities in temperate climates exhibit well documented seasonal variability. The reasons proposed to explain this kind of behaviour range from the effect of physical-chemical conditions (salinity, nutrients, temperature) growth rates, mortality, migration rates, food availability and predation. It is noticeable that the majority of the factors mentioned are external to the organisms, being environmental factors responsible for time dependent changes in zooplankton abundance. A question may arise from this conclusion, namely, "Could zooplankton blooms, in temperate climates, be mainly modelled by the internal physiological predispositions of the individual organisms?" Or, in a more "functional" formulation, "Could gonads be the baseline regulators of zooplankton abundance?". This study answers this pertinent question, assuming as a basic assumption that the reproductive potential of these organisms is constant, being controlled by extrinsic factors. For this purpose, histological and histochemical techniques were applied to the mysid Mesopodopsis slabberi, a key species in the Mondego River estuary, in order to establish a scale of gonadic development that would allow comparisons between high and low density periods. Histology reveals itself as the ideal base to establish a tool for the evaluation of the gonadic masses by allowing to calculate oocyte dimensions (trough biometry) and determine its maturity status through calculation of the N/C ratio and histochemical analysis (PAS and Tetrazonium reaction for proteins). Upon creation, validation and application of the formerly described tool, the most prominent result emerging from this study is the confirmation of the initial assumption: seasonal variability in zooplankton densities reflects advantageous or disadvantageous external factors acting over a latent reproductive potential. Moreover, this work confirms histology and histochemistry as valuable approaches to the determination of planktonic ecophysiological processes.

Pastorinho, M. R.; Antunes, C. P.; Marques, J. C.; Pereira, M. L.; Azeiteiro, U. M. M.; Morgado, F. M.

2003-05-01

303

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

Science.gov (United States)

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 relatively strong river discharge (in the order of 2000 m3/s), even during the dry season. As a result the Mekong is a strongly riverine estuary. This paper aims to test if the theory can be applied to such a riverine multi-channel estuary, and to see if possible adjustments or generalisations need to be made. The paper presents salt intrusion measurements that were done by moving boat in 2005, to which the salt intrusion model was calibrated. The theory has been expanded to cater for tidal damping. Subsequently the model has been validated with observations made at fixed locations over the years 1998 and 1999. Finally it has been tested whether the Mekong calibration fits the overall predictive equations derived in other estuaries. The test has been successful and led to a slight adjustment of the predictive equation to cater for estuaries that experience a sloping bottom.

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

2006-10-01

304

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

305

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 relatively strong river discharge (in the order of 2000 m3/s, even during the dry season. As a result the Mekong is a strongly riverine estuary. This paper aims to test if the theory can be applied to such a riverine multi-channel estuary, and to see if possible adjustments or generalisations need to be made. The paper presents salt intrusion measurements that were done by moving boat in 2005, to which the salt intrusion model was calibrated. The theory has been expanded to cater for tidal damping. Subsequently the model has been validated with observations made at fixed locations over the years 1998 and 1999. Finally it has been tested whether the Mekong calibration fits the overall predictive equations derived in other estuaries. The test has been successful and led to a slight adjustment of the predictive equation to cater for estuaries that experience a sloping bottom.

A. D. Nguyen

2006-01-01

306

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

307

Particle size analysis of ninety-nine samples from the Clyde Estuary : laboratory report  

OpenAIRE

This is a factual laboratory report presenting the results of the particle size analysis carried out on ninety-nine samples from the Estuary in February 2005. The work forms part of an overall study into the Estuary with Glasgow City Council.

Freeborough, K.; Wagner, D.

2005-01-01

308

Concentration and Distribution of Hydrophobic Organic Contaminants and Metals in the Estuaries of Ukraine  

Science.gov (United States)

In this baseline study of Ukrainian estuaries, sediments and organisms from the Dnieper and Boh estuaries and Danube Delta on the mainland, Sevastopol and Balaklava Bays on the Crimean Peninsula, and coastal Black Sea along the Crimean Peninsula were collected in 2006. Contamina...

309

Environmental monitoring and assessment program (EMAP) laboratory methods manual estuaries. Volume 1. Biological and physical analyses  

Energy Technology Data Exchange (ETDEWEB)

This document is intended to document analytical methods for use by laboratories conducting analyses for the Environmental Monitoring and Assessment Program-Estuaries. This document is volume I of a two-part series. The second volume of the EMAP-Estuaries Laboratory Methods Manual presents methods for the chemical analyses of sediments and tissue.

Strobel, C.J.; Klemm, D.J.; Lobring, L.B.; Eichelberger, J.W.; Alford-Stevens, A.

1995-08-01

310

Transport of fallout and reactor radionuclides in the drainage basin of the Hudson River estuary  

International Nuclear Information System (INIS)

The transport and fate of Strontium 90, Cesium 137 and Plutonium 239, 240 in the Hudson River Estuary is discussed. Rates of radionuclide deposition and accumulation over time and space are calculated for the Hudson River watershed, estuary, and continental shelf offshore. 37 references, 7 figures, 15 tables

311

EFFECTS OF EROSION AND MACROALGAE ON INTERTIDAL EELGRASS (ZOSTERA MARINA) IN A NORTHEASTERN PACIFIC ESTUARY (USA)  

Science.gov (United States)

Eelgrass (Zostera marina) in open-coast northeastern Pacific estuaries is primarily intertidal, yet little research has been done on the natural factors controlling its upper intertidal growth limits. This two-year study in the Yaquina Estuary (Newport, Oregon, USA) evaluated the...

312

ANALYSIS OF VEGETATION DISTRIBUTION AND ITS RELATION TO TIDAL OSCILLATION IN RIVERINE ESTUARIES  

Science.gov (United States)

Boundary between land and water usually forms ecotone in natural condition. Riparian vegetation pattern in lateral direction is one of the examples of such ecotone. Lateral riparian vegetation pattern is strongly dependent on the elevation relative to water level. Water level fluctuation in rivers is one of the most important factors controlling the ecotone along river banks. We have surveyed vegetation cover, morphology and water level fluctuation driven by tide in six riverine estuaries and analyzed the relation between vegetation pattern and ground level to understand the influence of tidal oscillation on the land cover of the banks along riverine estuaries. Common reed was dominant in all estuaries. Although specific height of where common reed distributes was different among estuaries, distribution of reed can be expressed generally by mean inundation depth within tidal zone. Mean inundation depth seems to control vegetation within tidal zone in riverine estuaries.

Onuma, Katsuhiro; Endou, Maremi; Amano, Kunihiko; Kishida, Hiroyuki

313

SALT WATER INTRUSION AND ITS RELATIONSHIP WITH ESTUARINE ECOLOGY IN THE CHIKUGOGAWA ESTUARY  

Science.gov (United States)

The spatiotemporal distribution of seawater intrusion in the Chikugogawa estuary was analyzed, and its relationship with the temporal variation of phytoplankton and engraulid fish, Coilia nasus, was discussed. The Chikugogawa estuary is vertically well mixed for most of the year, and a salt wedge is observed only when the tidal range decreases to 2 m or less. We found that the ratio of chlorophyll-a to pheophytin-a during the semilunar cycle varied according to the change in the mixing conditions in the estuary. Further, the number of sampled estuarine fish was related to the salinity and tidal range within the estuary; the fish was caught when the salinity was low and the tidal range was large. It is necessary to regulate the fresh water discharge in the estuary in order to maintain a low-salinity region that is suitable for the migration of fish and their spawning areas to the downstream of the river mouth barrage.

Yokoyama, Katsuhide; Ohmura, Taku; Suzuki, Tomoyuki; Takashima, Soutaro

314

Ambiguities in the classification of Cochin Estuary, West Coast of India  

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Full Text Available Cochin Estuary is a unique complex system along Indian coastline with a widespread area at the upstream. The fluctuations in salinity are of extreme kind ranging from entirely riverine to entirely saline. The high runoff months are characterized by monsoonal spells causing intense flushing. During the peak dry period, the runoff is less but steady providing a stable environment. River runoff is controlled by short term variations rather than long term variations. Using large comprehensive data sets, an attempt is made to evaluate several classification schemes for the estuary. The existing methods proved to be insufficient to represent the real salient features of this typical estuary. Arguments are also presented to illustrate the confusion in the names by which the estuary is commonly known. Therefore, a new nomenclature is proposed as "Cochin Monsoonal Estuarine Bay" embodying the physiographic, hydrographic and biological features of the estuary.

A. Shivaprasad

2013-03-01

315

What does impacted look like? High diversity and abundance of epibiota in modified estuaries.  

Science.gov (United States)

Ecosystems modified by human activities are generally predicted to be biologically impoverished. However, much pollution impact theory stems from laboratory or small-scale field studies, and few studies replicate at the level of estuary. Furthermore, assessments are often based on sediment contamination and infauna, and impacts to epibiota (sessile invertebrates and algae) are seldom considered. We surveyed epibiota in six estuaries in south-east Australia. Half the estuaries were relatively pristine, and half were subject to internationally high levels of contamination, urbanisation, and industrialisation. Contrary to predictions, epibiota in modified estuaries had greater coverage and were similarly diverse as those in unmodified estuaries. Change in epibiota community structure was linearly correlated with sediment-bound copper, and the tubeworm Hydroides elegans showed a strong positive correlation with sediment metals. Stressors such as metal contamination can reduce biodiversity and productivity, but others such as nutrient enrichment and resource provision may obscure signals of impact. PMID:25282127

Clark, Graeme F; Kelaher, Brendan P; Dafforn, Katherine A; Coleman, Melinda A; Knott, Nathan A; Marzinelli, Ezequiel M; Johnston, Emma L

2015-01-01

316

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

317

Salt intrusion during the dry season in the Huangmaohai Estuary, Pearl River Delta, China  

Science.gov (United States)

The Huangmaohai Estuary is the most western estuary in the Pearl River Delta, China. The tide in the estuary is a mixed semi-diurnal tide. The water level fluctuation is dominated by periods of semi-diurnal tide and alternated by periods of diurnal tide. The tidal range is generally larger during diurnal tide than during semi-diurnal tide, thus the diurnal tide and the semi-diurnal tide are referred to as spring tide and neap tide, respectively, in a traditional sense. The estuary is classified as well-mixed to partially mixed in dry seasons. The salinity distribution is abnormal, since the estuary becomes more stratified during the diurnal tide and more mixed during the semi-diurnal tide. Correspondingly, salt intrusion is strong during the diurnal tide and weak during the semi-diurnal tide. Model diagnostic analyses indicate that the geometry of the estuary largely controls the variation of tidal current during the spring-neap tidal cycle, and the water exchange among the Pearl River Network plays an important role in modulating salt intrusion in the estuary. The change of the diurnal tide and the semi-diurnal tide during a spring-neap tidal cycle results in a strong tidal current during semi-diurnal tide and a weak current during the diurnal tide, which contributes to the change in mixing and salt flux in the estuary. The variation of freshwater discharged into the estuary over a spring-neap tidal cycle is controlled by the river flow distribution in the Pearl River Network and demonstrates a pattern with more freshwater inflow in the estuary during the semi-diurnal tide than that during the diurnal tide. This pattern coincides with the change in tidal mixing resulting in variations of stratification, estuarine circulation, and salt transport during the spring-neap tidal cycle. The combination of tidal action and buoyancy forcing determines the salt intrusion pattern.

Gong, Wenping; Shen, Jian; Jia, Liangwen

2013-02-01

318

Nutrient land sea fluxes in oligothrophic and pristine estuaries of the Gulf of Bothnia, Baltic Sea  

Science.gov (United States)

Estuaries are often seen as important filters between land and the sea for inorganic and organic nutrients. This paper aims at estimating the estuarine fluxes of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and dissolved silicate for the major oligothrophic and pristine rivers running into the Bothnian Bay (BB) and the Bothnian Sea (BS), the northern subarctic subbasins of the Baltic Sea. Long-term data sets for these rivers and their estuaries as well as for the BB and BS were analyzed to assess whether these estuaries are sinks for inorganic nutrients. Most studied estuaries can be characterized as salt wedge estuaries with little exchange between the fresh seaward-flowing river water and the inward-flowing seawater. Estimates of water transit times ranged between 1 and 14 days. In most estuaries of the BB, N-depleted river water meets P-depleted seawater during the growth period. These findings were corroborated by mixing diagrams showing that the inner areas of the estuaries were N-depleted in summer. In the BS, on the other hand, both rivers and seawater were mostly N-depleted during summer. Thus, for most estuaries of this region of the Baltic Sea, primary productivity is presumably lower than or equal to that of offshore. The low productivity is also reflected in the sediments. The coastal sediments did not differ from the offshore stations in accumulation rates as well as the content of organic matter and nutrients, indicating that estuarine nutrient burial is not always higher as normally observed in other temperate systems. Finally, the estuaries of the pristine rivers in the northernmost part of the BB import DIN during summer, whereas the estuaries of the rivers in the BS import DIP during winter, from the sea.

Humborg, Christoph; Danielsson, Åsa; Sjöberg, Björn; Green, Mattias

2003-03-01

319

Lattice Boltzmann Hydrodynamic and Transport Modeling of Everglades Mangrove Estuaries  

Science.gov (United States)

Lattice Boltzmann methods are being developed and applied to simulate groundwater and surface water flows, and heat, solute, and particle transport. Their ability to solve Navier-Stokes, St. Venant, or Darcy equations with closely coupled solute transport and density-dependent flow effects in geometrically complex domains is attractive for inverse modeling of tracer release data and forward modeling of carbon transport in mangrove estuaries under various future conditions. Key physical processes to be simulated include tidal cycles, storm surge, sea level change, variable upstream stage, subsurface groundwater inputs, and precipitation/recharge and their effects on estuary salinity and carbon transport in the estuaries and groundwater beneath the mangroves. Carbon sources and storage in the aquifer and exchanges at the mangrove-estuary interface and carbon transformations in the water column also need to be simulated. Everglades tidal mangrove estuaries are characterized by relatively high velocity (approaching 1 m s-1) tidal flows. The channels are generally less than 2 m in depth. Tidal fluctuations approach 2 m leading to significant areas of periodic inundation and emergence of oyster beds, shell beaches, mangrove root masses, and sandy beaches. Initial models are two-dimensional, although a three-dimensional model explicitly incorporating bathymetry, density-dependent flow, and wind-driven circulation could be developed. Preliminary work highlights some of the abilities of early models. A satellite image of a 64-km2 area surrounding a CO2 flux tower is used to provide the model geometry. Model resolution is 15 m per grid node. A sinusoidal tidal stage variation and constant, high salinity are applied to the Gulf side of the model while a constant stage (corresponding to mean tide), zero salinity boundary is applied on the inland side. The Navier-Stokes equations coupled with the advection-diffusion equation are solved in the open channels. The mangrove areas are simulated as a porous medium, where transport is controlled by the advection-dispersion equation. As expected, incoming tides carry salinity up the channels and outgoing tides tend to flush the salinity from the channels. Salinity also invades the groundwater beneath the mangroves, which then contributes salinity back to the channel during outgoing tides. Although some large-scale aspects of the tidal flows are captured in these preliminary simulations, the current simulations are at Reynolds numbers smaller than those that characterize the real flows. More realistic simulations would require much higher resolution and have to be implemented on large-scale parallel computing platforms possibly using sub-grid turbulence models. Tracer data from experimental releases of SF6 will be used to estimate the parameters controlling transport in the estuary via inverse modeling with the parameter estimation code PEST. SF6 undergoes volatilization from the water column and is therefore a reasonable surrogate for air-sea CO2 gas exchange in the modeling framework. The parameters estimated from the tracer test inversion will be used in predictive modeling of the effects of sea level variations on salinity and carbon transport.

Sukop, M. C.; Engel, V.

2010-12-01

320

Effects of Short Time Variation in the River Discharge on the Salt Wedge Intrusion in the Yura Estuary, a Micro Tidal Estuary, Japan  

Directory of Open Access Journals (Sweden)

Full Text Available A numerical model was developed to investigate salinity distribution in the Yura Estuary, a micro tidal estuary in Japan. The model results show that the salinity distribution as represented by salt wedge intrusion agreed well with field observations. In addition to the seasonal variation, the salt wedge responds over short time scales according to the flood events. The retreat of the salt wedge is dependent on the scale of the river discharge; the salt wedge moved back and disappeared from the estuary when over250 m3·s-1 of fresh water was discharged from the estuary and it takes ~11 days for salt wedge to recover from the fresh water discharge event. The Yura Estuary has on average three floods during summer, this coincides with when phytoplankton is most productive in the river and indicates that the short temporal variations in the river discharge has important effects not only on the hydrodynamics, but also on the ecosystem in the estuary.

Yoh Yamashita

2013-03-01

321

Identifying resuspended sediment in an estuary using the 228Th/232Th activity ratio: the fate of lagoon sediment in the Bega River estuary, Australia  

International Nuclear Information System (INIS)

Thorium-series nuclides (228Th and 232Th) have been used to identify resuspended sediment in the Bega River estuary, south-eastern Australia. A non-conservative increase in concentration of suspended sediment of water in the vicinity of mid-estuary back-flow lagoons was associated with a decrease in the 228Th/232Th activity ratio (AR) of the suspended sediment. The lagoon sediment is characterized by a low estuarine 228Th/232Th signature, distinguishing it from freshwater suspended sediment recently delivered to the estuary, and identifying it as the likely source of the additional suspended sediment. Sediment-core 210TPb profiles show that the lagoons are accumulating sediment, presumably during high river-flow events. However this study indicates that during intervening periods of low flow, 40% of sediment deposited in the lagoons is subsequently resuspended and exported to the lower estuary, and possibly to the ocean. The utility of the 228Th/232Th AR to quantify sediment resuspension in estuaries is likely to be estuary-dependent, and is controlled by the extent of scavenging of dissolved 228Th by suspended particles. Copyright (2000) CSIRO Publishing

322

[Zooplankton in north branch waters of Changiiang Estuary].  

Science.gov (United States)

Based on the investigation data during the high-water (July, 2003) and low-water (January, 2004) periods, a causal analysis was made on the variation of zooplankton distribution in the north branch waters of the Changjiang Estuary. The results showed that in high-water period, the average of zooplankton biomass was 234.38 mg x m(-3), being 141.35 mg x m(-3) in flood tide and 327.40 mg x m(-3) in ebb tide, while in low-water period, it was 188.81 mg x m(-3), being 184.69 mg x m(-3) in flood tide and 192.93 mg x m(-3) in ebb tide. The biomass increased from the east to the west in flood tide, but a contrary trend was observed in ebb tide. The species number did not change obviously both in flood tide and in ebb tide. The value of diversity index (H') was higher in flood tide than in ebb tide. In high-water period, the biomass near the north shore was higher than that near the south shore, but it was contrary in the ebb tide. The difference between the waters of two shores was not obvious in low-water period as in high-water period, though the trend of biomass variation was similar. The variation of zooplankton distribution in the north branch waters of the Changjiang Estuary had a close relation with the seasonal changes of zooplankton biomass outside the Changjiang Estuary and the tide, but not significantly related with the Changjiang runoff water. Coriolis force accounted for the difference of zooplankton biomass in the waters of two shores via tide movement. PMID:16252880

Xu, Zhaoli

2005-07-01

323

Physical oceanography of the Río de la Plata Estuary, Argentina  

Science.gov (United States)

The Río de la Plata drains the second largest basin of South America. It flows into the Atlantic Ocean generating an estuarine system of about 35, 000 km 2, with only 5-15 m water depth. On the basis of temperature and salinity data from the last 29 years, property seasonality at the estuary were studied. Surface salinity distribution is controlled by the balance between onshore and offshore winds, the river discharge and the Coriolis force. As a result of the combined effects of these forces, two periods were observed for the salinity distribution. Fall-winter is characterized by a balance between onshore and offshore winds and a maximum in the continental drainage, generating a main NNE drift of the estuarine waters along the Uruguayan coast. During spring-summer, onshore winds become dominant and a minimum in the runoff is observed, resulting in Ekman surface drift advecting freshwater southwards along the Argentine coast. Consequently, shelf waters penetrate the estuary up to Punta del Este (Uruguay). Bottom salinity distribution does not exhibit seasonality, because the shelf water intrusion is controlled by bathymetry. The temperature field, driven by the atmospheric cycle, presents a warm and a cold season. Homogeneity in the vertical as well as horizontal scales characterizes these periods. High-resolution CTD data were arranged into salinity sections to describe the river-ocean interaction. A salt wedge is a quasi-permanent feature for the central and southern sectors of the estuary, defining an area of strong vertical stratification. However, the salinity stratification is destroyed by moderate to strong onshore winds.

Guerrero, Raúl A.; Acha, Eduardo M.; Framin˜an, Mariana B.; Lasta, Carlos A.

1997-06-01

324

Occurrence of Anaerobic Ammonium Oxidation in the Yangtze Estuary  

Science.gov (United States)

Over the past several decades, a large quantity of reactive nitrogen has been transported into the Yangtze estuarine and coastal water, due to intense human activities in the Yangtze River Basin. At present, it annually receives a high load of anthropogenic inorganic nitrogen (about 1.1 × 1011 mol N) from increased agricultural activities, fish farming, and domestic and industrial wastewater discharge in the Yangtze River Basin, consequently leading to severe eutrophication and frequent occurrences of harmful algal blooms in the estuary and adjacent coastal areas. Hence, the microbial nitrogen transformations are of major concern in the Yangtze Estuary. Anaerobic ammonium oxidation (anammox) has been reported to play a significant role in the removal of reactive nitrogen in aquatic ecosystems. In this study, the occurrences of anammox bacteria and associated activity in the Yangtze Estuary were evidenced with molecular and isotope-tracing techniques. It is observed that the anammox bacteria at the study area mainly consisted of Candidatus Scalindua, Brocadia, Kuenenia. Salinity was found to be a key environmental factor controlling distribution and diversity of the anammox bacterial community at the estuarine ecosystem. Also, temperature and organic carbon had significant influences on anammox bacterial biodiversity. Q-PCR assays of anammox bacteria indicated that their abundance had a range of 2.63 ×106 - 9.48 ×107 copies g-1 dry sediment, with high spatiotemporal heterogeneity. The potential anammox activities measured in the present work varied between 0.94 - 6.61nmol N g-1 dry sediment h-1, which were related to temperature, nitrite and anammox bacterial abundance. On the basis of the 15N tracing experiments, the anammox process was estimated to contribute 6.6 - 12.9 % to the total nitrogen loss whereas the remainder was attributed to denitrification.

Hou, L.

2013-12-01

325

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

326

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 deussed, 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

327

Stable density fronts and dinoflagellate patches in a tidal estuary  

Science.gov (United States)

Possible physical mechanisms contributing to the formation and maintenance of two distinct dinoflagellate patches in the upper region of a tidal estuary in Maine were investigated. Observations and measurements of these patches at the surface and at depth suggest a consistent and causal relationship between them and the dynamic physical frontal features revealed in these studies. The involvement of a normally toxigenic species, Gonyaulax tamarensis, in these patches suggests that comparatively smallscale physical features may be involved in localized 'blooms' of this species in coastal estuarine waters.

Incze, Lewis S.; Yentsch, Clarice M.

1981-11-01

328

Shellfish culture in estuary zones and the sanitary restrictions  

Directory of Open Access Journals (Sweden)

Full Text Available The nutritional requirements of shellfish are satisfied by the phytoplankton and the nutrients of the estuary waters. Bivalves (mussels, oysters, clams, cockles, scallops and razors can be there produced. The shellfish are cultured on the sea bottom or suspended. For shellfish culture no food is required and the investment cost is low. If the quality of the water is high then they can be considered as bio or organic products. The disadvantages concern their sanitary status (contamination by heavy metals, radio nucleotides, phytotoxines, viruses, bacteria and parasites. No medications or vaccines are applied.

ANGELIDIS Panagiotis

2007-10-01

329

Geochemical methods applied to uranium exploration in southwest Baffin Island  

International Nuclear Information System (INIS)

A geochemical orientation survey was undertaken in an area in southwest Baffin Island. A methodology was established for a future reconnaissance geochemical program using lake samples. Mineralogical and chemical studies of known radioactive occurrences, combined with detailed sampling of secondary environment media in the vicinity of the showings, indicate that uranium is the most significant pathfinder, despite considerable enrichment of other metals in the uraniferous rocks. Significant geochemical patterns produced by uranium in lake waters and uranium in lake sediments have been obtained, but their relative usefulness depends on the distribution of carbonate bedrock. The base metal potential of the area was examined in some detail and found to be significant. (author)

330

33 CFR 165.812 - Security Zones; Lower Mississippi River, Southwest Pass Sea Buoy to Mile Marker 96.0, New Orleans...  

Science.gov (United States)

...false Security Zones; Lower Mississippi River, Southwest Pass Sea Buoy to...812 Security Zones; Lower Mississippi River, Southwest Pass Sea Buoy to...Location. Within the Lower Mississippi River and Southwest Pass, moving...

2010-07-01

331

Molybdenum isotopes in two Indian estuaries: Mixing characteristics and input to oceans  

Science.gov (United States)

The distributions of dissolved and particulate Mo and their isotope composition (?98Mo) have been measured in the Narmada and the Tapi estuaries draining into the Arabian Sea. During monsoon, the ?98Mo of dissolved Mo in the Narmada estuary ranges from 0.49‰ to 2.19‰ in the salinity range 0-17.2 practical salinity unit (psu) quite similar to that in the Tapi estuary, 0.99-2.36‰, in the salinity range 0-20.3 psu. Mo concentration in suspended sediments of the Narmada estuary collected during monsoon average 512 ± 44 ng/g (range 459-602 ng/g) similar to that measured in one sample from the Tapi estuary 560 ng/g Mo. ?98Mo of particulate Mo in the Narmada ranges from -0.21‰ to 0.48‰ with an average -0.03 ± 0.2‰. Dissolved Mo in the Narmada and the Tapi rivers display isotopically heavier M? compared to that in basalts, the major lithology of their drainage. This could result from a variety of processes, preferential weathering of Mo rich sulphide minerals dispersed in the basalts, preferential removal of isotopically lighter Mo during transport or contribution from marine cyclic salts supplied via rain or chemical weathering of organic rich shales in the basins. The distribution of ?98Mo in the Narmada and the Tapi estuaries with salinity does not follow the theoretical mixing line between river and seawater endmembers suggesting its non-conservative behavior. Particulate Mo and ?98Mo show concomitant increase with salinity in the Narmada estuary indicating loss of dissolved Mo by adsorption onto Fe-Mn oxyhydroxide. Balancing the Mo budget along the course of these estuaries using inverse model suggests that in the Narmada estuary there could be loss up to 8% of the dissolved Mo and that in the Tapi supply from anthropogenic sources could be up to 27%. The results obtained in this study bring out the processes modifying riverine input of Mo and its ?98Mo in the estuaries, oxic sink in the Narmada and anthropogenic input in the Tapi. Repetitive adsorption and desorption of Mo in the Narmada estuary can modify the supply of dissolved Mo and its ?98Mo relative to riverine supply by up to 40%, this can significantly impact the Mo isotope budget of the oceans. In contrast, in the Tapi estuary there is enhancement in the dissolved supply of Mo relative to that from river due to anthropogenic input of Mo. The investigations in these two estuaries underscore the importance of solute particle interactions and anthropogenic input in determining the Mo flux and its ?98Mo to the open Arabian Sea.

Rahaman, Waliur; Goswami, Vineet; Singh, Sunil K.; Rai, Vinai K.

2014-09-01

332

Quantification of Surface Water and Groundwater Nitrate Fluxes to two Small Estuaries in Atlantic Canada  

Science.gov (United States)

In parts of Atlantic Canada there is currently concern that nutrient loadings from catchments are adversely affecting water quality and ecosystems in estuaries. This is especially the case in Prince Edward Island (PEI), a province in which intensive potato production has contributed to elevated nitrate concentrations in groundwater and streams, and where eutrophic or anoxic conditions occur regularly in many estuaries. Previous nutrient loading studies conducted in PEI have focused only on the contributions from surface water, although it is known that elevated nitrate concentrations exist in groundwater and that the regional fractured sandstone aquifer has relatively high hydraulic conductivity. In this research the nitrogen loadings delivered by surface water and groundwater to two small estuaries located in PEI were quantified over a two-year period. Surface waters were monitored directly, while groundwater discharge to the estuaries was estimated using a combination of airborne thermal infrared imaging, direct discharge measurements at selected shoreline spring locations, and numerical modeling of groundwater flow in the two catchments. Relatively widely spaced shoreline springs have been identified as the dominant mode of groundwater discharge, accounting for about 70% of the total groundwater flux, and this is likely a result of the fractured nature of the contributing aquifer. Focused spring discharge was sampled on six occasions and a two component mixing model based on salinity and nitrate concentrations measured in springs, streams and estuaries was applied to calculate the nitrate concentration in groundwater discharge. The nitrate loadings to both estuaries are highly correlated with freshwater discharge, and the annual nitrate fluxes are dominated by streams (approximately 80% of the total). However, groundwater contributes between 15% and 18% of the annual nitrate load which is significant when compared to other components of estuary nutrient mass balances. The total annual groundwater nitrate load to McIntyre Creek estuary (3200 kg NO3-N/yr) is more than half of the nitrate load for Trout River estuary (5900 kg NO3-N/yr), although the extent of the estuary and its catchment are about ten times smaller than the respective areas of the Trout River estuary. This is a result of the much larger extent of developed land (mostly agricultural) in the McIntyre Creek catchment. The generally poor conditions in these estuaries, including annual anoxic events, are probably driven to a large extent by the high nitrogen loads from streams and groundwater. This study demonstrates that nitrogen loads from direct groundwater discharge to estuaries should not be ignored in these and other areas with similar land use and hydrogeological conditions.

Danielescu, S.; Macquarrie, K. T.

2009-05-01

333

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.

2012-09-01

334

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 methodology 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.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 pesca. 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.

Dandara M.M. Bezerra

2012-09-01

335

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

336

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

337

Pollutant Flux Estimation in an Estuary Comparison between Model and Field Measurements  

Directory of Open Access Journals (Sweden)

Full Text Available This study proposes a framework for estimating pollutant flux in an estuary. An efficient method is applied to estimate the flux of pollutants in an estuary. A gauging station network in the Danshui River estuary is established to measure the data of water quality and discharge based on the efficient method. A boat mounted with an acoustic Doppler profiler (ADP traverses the river along a preselected path that is normal to the streamflow to measure the velocities, water depths and water quality for calculating pollutant flux. To know the characteristics of the estuary and to provide the basis for the pollutant flux estimation model, data of complete tidal cycles is collected. The discharge estimation model applies the maximum velocity and water level to estimate mean velocity and cross-sectional area, respectively. Thus, the pollutant flux of the estuary can be easily computed as the product of the mean velocity, cross-sectional area and pollutant concentration. The good agreement between the observed and estimated pollutant flux of the Danshui River estuary shows that the pollutant measured by the conventional and the efficient methods are not fundamentally different. The proposed method is cost-effective and reliable. It can be used to estimate pollutant flux in an estuary accurately and efficiently.

Yen-Chang Chen

2014-08-01

338

Genetic diversity of Broussonetia papyrifera populations in southwest China.  

Science.gov (United States)

Broussonetia papyrifera is an important native tree species with high economic value in southwest China. Its resources are drastically reduced because of over-harvesting and habitat fragmentation. In this study, 17 natural populations of B. papyrifera were analyzed using inter-simple sequence repeat (ISSR) markers to assess the genetic diversity and population structure. In total, 100 bands were obtained from 16 ISSR primers. The B. papyrifera populations showed relatively high genetic diversity at the species level [percentage of polymorphic bands (PPB): 96%; Nei's genetic diversity (HE): 0.3074; Shannon's information index (I): 0.4617], while the genetic diversity at the population level was relatively low (PPB: 53.2%; HE: 0.1826; I: 0.2735). Relatively high level of genetic differentiation among populations (41%) was disclosed by analysis of molecular variance, which agrees with the Nei's genetic diversity statistics (40.59%) and Shannon's information measure (40.76%). Gene flow among populations (NM) was only 0.7318. A significant correlation was observed between genetic and geographic distance among the studied populations (r=0.2948). We conjectured that the genetic diversity of B. papyrifera resulted from human disturbance, habitat fragmentation, small effective population size, and geographic barrier. Given the high genetic differentiation among populations, some utilization and conservation strategies were proposed. This study provides a reference for the sustainable use of the species in southwest China. PMID:25222255

Liao, S X; Deng, Z H; Cui, K; Cui, Y Z; Zhang, C H

2014-01-01

339

76 FR 21889 - Nebraska Public Power District; Southwest Power Pool Regional Entity; Notice of Extension of Time  

Science.gov (United States)

...Power District; Southwest Power Pool Regional Entity; Notice of Extension of...notes that the Southwest Power Pool Regional Entity filed a petition (SPP RE...due to the NPPD Petition. MRO states that the NPPD Petition and...

2011-04-19

340

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

341

Spatial variation of the longitudinal dispersion coefficient in an estuary  

Science.gov (United States)

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.

Shaha, D. C.; Cho, Y.-K.; Kwak, M.-T.; Kundu, S. R.; Jung, K. T.

2011-12-01

342

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

343

Effects of Prevailing Winds on Turbidity of a Shallow Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

Hyun Jung Cho

2007-06-01

344

The "Southwest Effect" Revisited: An Empirical Analysis of the Effects of Southwest Airlines and JetBlue Airways on Incumbent Airlines from 1993 to 2009  

OpenAIRE

The expansion of Southwest Airlines and JetBlue Airways has sparked new empirical interest in the effects of low-cost carriers (LCC) on existing airfares. Namely, empirical studies have attempted to capture the threat, or potential competition, of an entrant. This paper examines incumbent airline prices as a result of potential and actual competition from both Southwest Airlines and JetBlue Airways from 1993 to 2009 by analyzing mean airfares as well as price dispersion on incumbent routes. I...

Wu, Steven M.

2012-01-01

345

[Spatial distribution of seawater dimethylsulfide in winter of Jiulong Jiang Estuary].  

Science.gov (United States)

Cruise investigation of dimethylsulfide (DMS) emission in estuarine areas, heavily disturbed by human activities, was carried out in the winter of 2001 in Jiulong Jiang Estuary. The concentrations of chlorophyll, salinity and nutrients showed evidently spatial distribution in Jiulong Jiang Estuary, so did DMS concentrations in surface water. The average of seawater DMS was 101.0 and 242.1 ng x L(-1) in river mouth area and gulf area, respectively. DMS concentrations decreased first with the increase of seawater salinity and then increased. The highest DMS concentration occurred at river plume front of maximum turbidity zone of the estuary. PMID:15623021

Ma, Qi-ju; Hu, Min; Liu, Ling-li; Zhu, Tong; Dai, Min-han

2004-09-01

346

Digestive tube contents of blood cockle (Anadara granosa in a tropical mangrove estuary in Malaysia  

Directory of Open Access Journals (Sweden)

Full Text Available This study was carried out to clarify the feeding biology of the blood cockle (Anadara granosa. We collected blood cockles from 8 stations in the Matang mangrove estuary of Malaysia in July and August 2010. The digestive tube contents of the specimens were stained with Congo red and observed under a light microscope. The results showed blood cockles take in particles containing cellulose as well as phytoplankton such as diatoms. As blood cockles in estuaries are known to exhibit cellulolytic enzyme activity in their digestive gland, the present results indicate blood cockles in estuaries feed on litter supplied from mangrove forests and terrestrial plants.

Tatsuya Yurimoto

2014-08-01

347

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

348

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.

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

2013-01-01

349

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

350

Environmental Conditions in northern Gulf of Mexico Estuaries: before and after the BP Oil Spill  

Science.gov (United States)

This presentation provides a summary of ecological condition and sediment chemistry data for northern Gulf of Mexico estuaries that were exposed to oil and oil-related contaminants from the BP Oil Spill. ...

351

10,000 years of sea-level change in the Thames Estuary  

OpenAIRE

“Is the sea level rising in the Thames Estuary, and if so, by how much?” asks Dr Chris Vane who leads a number of projects investigating topics such as sea level change, biogeochemistry and sediment quality (pollution).

Vane, Chris

2014-01-01

352

76 FR 8345 - Endangered and Threatened Species; Recovery Plan Module for Columbia River Estuary Salmon and...  

Science.gov (United States)

...potential for high-quality habitat. Urban and...remaining high-quality off-channel habitat...potential for high-quality habitat. Other threats...1\\ CRE = Columbia River estuary. [[Page...threats, such as water withdrawal,...

2011-02-14

353

A note on the comparative turbidity of some estuaries of the Americas  

Science.gov (United States)

Field data from 27 estuaries of the Americas are used to show that, in broad terms, there is a large difference in turbidity between the analyzed east and west-coast estuaries and that tidal range and tidal length have an important influence on that turbidity. Generic, numerical sediment-transport modeling is used to illustrate this influence, which exists over a range of space scales from, e.g., the Rogue River Estuary (few km, few mg l-1) to the Bay of Fundy (hundreds of km, few g l-1). The difference in Pacific and Atlantic seaboard estuarine turbidity for the analyzed estuaries is ultimately related to the broad-scale geomorphology of the two continents.

Uncles, R.J.; Smith, R.E.

2005-01-01

354

Development and validation of a MODIS colored dissolved organic matter (CDOM) algorithm in northwest Florida estuaries  

Science.gov (United States)

Satellite remote sensing provides synoptic and frequent monitoring of water quality parameters that aids in determining the health of aquatic ecosystems and the development of effective management strategies. Northwest Florida estuaries are classified as optically-complex, or wat...

355

An analysis of MODIS algorithms for surface salinity and dissolved organic carbon in northwest Florida estuaries  

Science.gov (United States)

Synoptic and frequent monitoring of water quality parameters from satellite is useful for determining the health of aquatic ecosystems and development of effective management strategies. Northwest Florida estuaries are classified as optically-complex, or waters influenced by chlo...

356

A one-dimensional model for salinity intrusion in alluvial estuaries  

Science.gov (United States)

A salinity intrusion model for well-mixed alluvial estuaries is developed. The parameters are schematized in such a way that the amount of field work in gathering data on estuary geometry and tide is considerably reduced. The determining factor in the geometry is found to be the variation of width in the estuary. This relationship appears to obey an exponential law. The depth is found to remain fairly constant and does not necessarily have to be measured. A stationary and a non-stationary model are developed. The stationary model may be applied, using a pocket calculator. In many cases however, where the stationary model may not be used the non-stationary model may be applied. Application of the model is demonstrated on several alluvial estuaries.

Savenije, H. H. G.

1986-06-01

357

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

358

Distribution of intertidal eelgrass (Zostera marina L.) with bathymetry in three Pacific Northwest estuaries  

Science.gov (United States)

Distributions of native intertidal eelgrass (Zostera marina L.) and non-vegetated substrates in three coastal estuaries of the Pacific Northwest (PNW) were determined using color infrared (CIR) aerial orthophotography during daylight low tides. Comparison of the digital classif...

359

Historical perspective of lubricant deposit evaluations at Southwest Research Institute  

Energy Technology Data Exchange (ETDEWEB)

This paper presents numerous bench tests investigated at Southwest Research Institute which were intended to evaluate the performance of automotive engine and gear oils, and aircraft turbine lubricants. In most cases the tests were designed to simulate certain aspects of the environment seen by the lubricant while performing its function, and lubricant degradation with subsequent deposit formation are the parameters measured. Although in many instances good correlation with specific engine tests were achieved, the final measure of acceptability of a finished lubricant for military applications remains the full engine tests for engine oils; automotive gear tests for gear oils, and full-scale turbine engine tests for the aircraft lubricants. The tests discussed here are excellent screening devices for new experimental lubricant formulations.

Bowden, J.N.; Lestz, S.J.

1980-11-01

360

Reservoir characterization of the Smackover Formation in southwest Alabama  

Energy Technology Data Exchange (ETDEWEB)

The Upper Jurassic Smackover Formation is found in an arcuate belt in the subsurface from south Texas to panhandle Florida. The Smackover is the most prolific hydrocarbon-producing formation in Alabama and is an important hydrocarbon reservoir from Florida to Texas. In this report Smackover hydrocarbon reservoirs in southwest Alabama are described. Also, the nine enhanced- and improved-recovery projects that have been undertaken in the Smackover of Alabama are evaluated. The report concludes with recommendations about potential future enhanced- and improved-recovery projects in Smackover reservoirs in Alabama and an estimate of the potential volume of liquid hydrocarbons recoverable by enhanced- and improved-recovery methods from the Smackover of Alabama.

Kopaska-Merkel, D.C.; Hall, D.R.; Mann, S.D.; Tew, B.H.

1993-02-01

361

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

362

Gravity and magnetic data of Midway Valley, southwest Nevada  

International Nuclear Information System (INIS)

Detailed gravity and ground magnetic data collected along five traverses across Midway Valley on the eastern flank of Yucca Mountain in southwest Nevada are described. These data were collected as part of an effort to evaluate faulting in the vicinity of proposed surface facilities for a potential nuclear waste repository at Yucca Mountain. Geophysical data show that Midway Valley is bounded by large gravity and magnetic anomalies associated with the Bow Ridge and Paintbrush Canyon faults, on the west side of Exile Hill and on the west flank of Fran Ridge, respectively. In addition, Midway Valley itself is characterized by a number of small-amplitude anomalies that probably reflect small-scale faulting beneath Midway Valley

363

Radioactivity of Phosphogypsum in South-West of Spain  

International Nuclear Information System (INIS)

Phosphogypsum is the by-product of producing phosphoric acid by reacting phosphate rock with sulphuric acid. In the south-west of Spain, and near the town of Huelva, there is a big industrial complex with some factories devoted to the production of phosphoric acid, which produce annually 3 x 106 metric tonnes of phosphogypsum. Of this amount 80% is stored in nearby sites named 'gyp-stacks'. The phosphate rock treated in these factories for the production of phosphoric acid has 238U activities between 1000 and 1600 Bq.kg-1, being their daughters in approximately secular equilibrium. A fraction of these radionuclides, and in different proportion, goes with the phosphogypsum. The radionuclide activity concentrations in various phosphogypsum samples collected at different places in the gyp-stacks are given, and an average dose rate in air due to gamma rays at a point 1 m above these areas is also determined. (author)

364

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

365

Decay of eddies at the South-West Indian Ridge  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english The South-West Indian Ridge in the Indian sector of the Southern Ocean is a region recognised for the creation of particularly intense eddy disturbances in the mean flow of the Antarctic Circumpolar Current. Eddies formed at this ridge have been extensively studied over the past decade using hydrogr [...] aphic, satellite, drifter and float data and it is hypothesised that they could provide a vehicle for localised meridional heat and salt exchange. The effectiveness of this process is dependent on the rate of decay of the eddies. However, in order to investigate eddy decay, logistically difficult hydrographic monitoring is required. This study presents the decay of cold eddies at the South-West Indian Ridge, using outputs from a high-resolution ocean model. The model's representation of the dynamic nature of this region is fully characteristic of observations. On average, 3-4 intense and well-defined cold eddies are generated per year; these eddies have mean longevities of 5.0±2.2 months with average advection speeds of 5±2 km/day. Most simulated eddies reach their peak intensity within 1.5-2.5 months after genesis and have depths of 2000 m - 3000 m. Thereafter they dissipate within approximately 3 months. The decay of eddies is generally characterised by a decrease in their sea surface height signature, a weakening in their rotation rates and a modification in their temperature-salinity characteristics. Subantarctic top predators are suspected to forage preferentially along the edges of eddies. The process of eddy dissipation may thus influence their feeding behaviour.

Jonathan V., Durgadoo; Isabelle J., Ansorge; Beverly A., de Cuevas; Johann R.E., Lutjeharms; Andrew C., Coward.

366

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

367

The Charente estuary : zooplankton community structure and trophic ecology, ecosystem approach to metal contamination  

OpenAIRE

Estuaries are highly dynamic systems where complex biogeochemical greatly affect the fate of organic and non-organic matter. The physical mixing of freshwater and saltwater leads to high variability in the main drivers controlling organisms distribution and trace metals partitioning between the particulate and dissolved phases: eg. salinity gradient, suspended particulate matter concentration (SPM). This work aims thus at studying the Charente estuary, which is the main river discharging into...

Mode?ran, Julien

2010-01-01

368

Cladocerans (Branchiopoda) of a tropical estuary in Brazil Cladoceras (Branchiopoda) de um estuário tropical no Brasil  

OpenAIRE

The study was conducted in the Capibaribe river estuary in Recife (Brazil) to assess the role played by cladocerans in a eutrophic environment. Samplings were carried out monthly at 4 fixed stations along the estuary from July 1987 to June 1988. Collections were made with a plankton net of 65 micrometers mesh size. Six cladocerans species were registered: Penilia avirostris, Diaphanosoma spinulosum, Chydorus barroisi, Ceriodaphnia rigaudi, Ilyocryptus spinifer, and Moina micrura. The most fre...

Paranagua?, M. N.; Neumann-leita?o, S.; Nogueira-paranhos, J. D.; Silva, T. A.; Matsumura-tundisi, T.

2005-01-01

369

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

OpenAIRE

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. Amp Nbsp D.; Amp Nbsp Savenije, H. Amp Nbsp H.

2006-01-01

370

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

OpenAIRE

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

371

An idealized model and systematic process study of oxygen depletion in highly turbid estuaries  

OpenAIRE

The sensitivity of oxygen depletion in turbid estuaries to parameters like freshwater discharge, depth, and sediment availability is investigated using an idealized model. The model describes tidally averaged circulation and suspended sediment concentration (SSC), which are input into an advection?diffusion sink module of dissolved oxygen (DO). Based on the analysis of field data collected in the Ems estuary, the modeled oxygen depletion rates are proportional to SSC. The model is calibrate...

Talke, S. A.; Swart, H. E.; Jonge, V. N.

2009-01-01

372

Schooling behavior of Mugil curema (Perciformes: Mugilidae) in an estuary in southeastern Brazil  

OpenAIRE

Schools of mullets, Mugilidae, are abundant in estuaries and shallow marine waters. We report on the schooling behavior of juvenile white mullet, Mugil curema, in the estuary of the Canto da Paciência stream, in Ubatuba, southeastern Brazil. Schools of small fish (15 to 35 mm TL) were composed of a larger number of individuals (up to a hundred individuals), and were found feeding mainly in shallow nearshore waters, whereas schools of larger fish (40 to 100 mm TL) were observed only in deeper...

Carolina Delgado de Carvalho; Carolina Marocco Corneta; Virginia Sanches Uieda

2007-01-01

373

Numerical Model of Pollution Dispersion in the Gour Soozan Estuary – Bandar Abbas, Iran  

OpenAIRE

Pollution and the dispersion of pollutants are important issues in the environment of rivers and estuaries, being regarded as the major problems in utilizing the surface water globally. Environmentally speaking, the Gour Soozan Estuary suffers from a lot of problems. Arriving at a model for the dispersion of pollution and pollutant particles will therefore provide useful information for future studies in the field of environment and developmental activities in Bandar Abbas. Taking the availab...

Arefe Emami; Mojtaba Tajziyehchi

2012-01-01

374

Numerical Model of Pollution Dispersion in the Gour Soozan Estuary – Bandar Abbas, Iran  

OpenAIRE

Pollution and the dispersion of pollutants are important issues in the environment of rivers and estuaries, being regarded as the major problems in utilizing the surface water globally. Environmentally speaking, the Gour Soozan Estuary suffers from a lot of problems. Arriving at a model for the dispersion of pollution and pollutant particles will therefore provide useful information for future studies in the field of environment and developmental activities in Bandar Abbas. Taking the availab...

Arefe Emami; Mojtaba Tajziyehchi

2013-01-01

375

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

376

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

OpenAIRE

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...

Narasimha Rao, Geddada Mohan; Prayaga Murty, Pragada

2010-01-01

377

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

OpenAIRE

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

378

Seasonal and axial variations of net water circulation and turnover in the estuary of Bilbao  

Science.gov (United States)

A two-layer box model based on salinity and freshwater inflow data was developed and used to estimate net water circulation, contributions of gravitational circulation exchange and tide-driven exchange, and turnover times for the estuary of Bilbao, a small estuary of the Basque coast (Bay of Biscay). Average monthly estimations for the 2001-2010 period were made and related to river discharge and saltwater inflow. Seasonal variations of surface-layer outflows were strongly related to the river discharge regime, even in the lower estuary (inner Abra harbour). Bottom-layer salt-water inflow from the outer Abra was the main driver of bottom landward flow, vertical advection and surface-layer outflow in the inner Abra, but not in the channelized zone that extends from the inner limit of the Abra harbour to the tidal limit. Gravitational circulation exchange dominated in the entire estuary over the annual cycle. Tide-driven exchange proportionately increased in summer and showed the highest contribution (42%) in the lower estuary in August. Flushing and residence times increased in summer in relation with the decrease of freshwater discharge, although in the innermost zone of the estuary they were also high in winter due to the retention of freshwater at the inner estuary under extremely high discharge conditions. Flushing and residence time maxima of 21.5 and 28.6 days respectively were obtained for the entire studied zone in August. It is of note that turnover times differed largely between the upper (flushing time of 0.4-2.4 days) and bottom (flushing time of 2-10 days) layers in the channelized zone. Results supported intuitive conclusions drawn in previous studies about the spatio-temporal dynamics of dissolved oxygen, chlorophyll and zooplankton populations in the estuary of Bilbao, in relation to the effect of water circulation and turnover.

Uriarte, Ibon; Villate, Fernando; Iriarte, Arantza; Duque, Johanna; Ameztoy, Iban

2014-10-01

379

Spatial distribution of subtidal Nematoda communities along the salinity gradient in southern European estuaries  

Science.gov (United States)

This study investigated the spatial distribution of subtidal nematode communities along the salinity gradients of two Portuguese estuaries exposed to different degrees of anthropogenic stress: the Mira and the Mondego. The nematode communities were mainly composed of Sabatieria, Metachromadora, Daptonema, Anoplostoma, Sphaerolaimus and Terschellingia species, closely resembling the communities of Northern European estuaries. In both estuaries, nematode density and community composition followed the salinity gradient, naturally establishing three distinct estuarine sections: (i) freshwater and oligohaline - characterised by the presence of freshwater nematodes, low nematode density and diversity; (ii) mesohaline - dominated by Terschellingia, Sabatieria and Daptonema, with low total density and diversity; and (iii) polyhaline and euhaline - where nematodes reached the highest density and diversity, and Paracomesoma, Synonchiella, and Odontophora were dominant. Despite the similarities in community composition and total nematode density, the proportion of different nematode feeding types were remarkably different in the two estuaries. In Mira, selective deposit feeders were dominant in the oligohaline section, while non-selective deposit feeders were dominant in the other sections. On the contrary, in the Mondego estuary, epigrowth-feeders and omnivores/predators were dominant in the freshwater sections and in the euhaline sector of the southern arm. Differences observed along each estuarine gradient were much stronger than overall differences between the two estuaries. In the Mondego estuary, the influence of anthropogenic stressors seemed not to be relevant in determining the nematodes' spatial distribution patterns, therefore suggesting that mesoscale variability responded essentially to natural stressors, characteristic of estuarine gradients. Nevertheless, the proportion of the different feeding types was different between the two estuaries, indicating that the response of nematode feeding guilds is able to reflect anthropogenic-induced stress and can be useful in assessing biological quality in transitional waters ecosystems.

Adão, Helena; Alves, Ana Sofia; Patrício, Joana; Neto, João Magalhães; Costa, Maria José; Marques, João Carlos

2009-03-01

380

Plutonium in Atlantic coastal estuaries in the southeastern United States of America  

International Nuclear Information System (INIS)

A survey was made to begin to provide baseline information on the plutonium distribution of representative estuarine and coastal areas of the southeastern United States of America. Sediments and marsh grass (Spartina) were collected and analysed from three locations within a tidal marsh. In the three estuaries (Savannah, Neuse and Newport) the suspended particulate matter (1?m and greater) was filtered from waters with different salinities and the plutonium content of the particulates determined. The Savannah river estuary, in addition to fall-out plutonium, has received up to 0.3Ci of plutonium from the Savannah River Plant (SRP) of the US Energy Research and Development Administration. The SRP plutonium has a variable isotopic composition that can influence plutonium isotopic ratios in the estuarine system. The other estuaries do not have nuclear installations upstream. Plutonium contents in surface marsh sediment from the Savannah River estuary are lower than those found in nearby bay sediments. In fact, total plutonium concentrations of sediments showed increases from the upper to lower portions of the estuary; however, higher contributions of 238Pu in the upper portions indicate that releases from the Savannah River Plant do contribute plutonium to the Savannah river estuary. Plutonium concentrations in Spartina were less than 10fCi/g dry weight but are higher than plutonium contents of terrestrial plants (238Pu to the total plutonium activities in the sediment and the Spartina. Plutonium concentrations were about three times higher in the Newport river estuary than in the Neuse and Savannah river estuaries. (author)

381

Functional diversity in European estuaries: Relating the composition of fish assemblages to the abiotic environment  

OpenAIRE

Based on a large standardised data set, the present study proposed a meta-analysis to describe general patterns in the functional diversity of estuarine fish assemblage in terms of both number of species and density along the European Atlantic coast. Fish species collected from 31 European estuaries from Portugal to Scotland were allocated to functional groups according to their ecological utilization of estuaries. A clustering analysis was performed to compare the overall functional structur...

Nicolas, D.; Lobry, J.; Le Pape, O.; Boe?t, P.

2010-01-01

382

Variability of Internally Generated Turbulence in an Estuary, from 100 Days of Continuous Observations  

OpenAIRE

We present detailed observations of internally generated turbulence in a sheared, stratified natural flow, as well as an analysis of the external factors leading to its generation and temporal variability. Multi-month time series of vertical profiles of velocity, acoustic backscatter (0.5 Hz), and turbulence parameters were collected with two moored acoustic Doppler current profilers (ADCPs) in the Hudson River estuary, and estuary-long transects of water density were collected 30 times. ADCP...

Orton, P. M.; Visbeck, Martin

2009-01-01

383

HIDRODYNAMIC CHARACTERIZATION OF THE CUBATÃO RIVER ESTUARY, JOINVILLE CARACTERIZAÇÃO HIDRODINÂMICA DO ESTUÁRIO DO RIO CUBATÃO, JOINVILLE.  

OpenAIRE

This paper presents a preliminary approach on the hydrodynamics of the Cubatão River estuary based on hydrographic data from a thirteen-hour campaign (a complete tidal cycle) under spring tide condition. Current speed and direction, salinity, temperature and turbidity were recorded at 1.5 m bellow the water surface near the estuary mouth, with a moored acoustic currentmeter. Vertical profiles of salinity and temperature were done close to the mooring every hour with a CTD to give the vertica...

Schettini, C. A.; Carvalho, J. L.

2000-01-01

384

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

OpenAIRE

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 we...

Fal Dessai, Nandadeep U.

2013-01-01

385

Cytotoxic and genotoxic assessment of potentially contaminated sediments from the Sado Estuary  

OpenAIRE

Previous studies have shown that the river Sado Estuary (W Portugal) is highly susceptible to contamination due to anthropogenic activity. In fact, sizable concentrations of metals, pesticides and polycyclic aromatic hydrocarbons have been measured in sediments from various points of the estuary. Those compounds may be absorbed by aquatic species, making it a public health issue when entering the human food chain. The purpose of this study was to assess the cytotoxic and genotoxic...

Pinto, Miguel; Louro, Henriqueta; Costa, Pedro; Costa, Maria Helena; Caeiro, Sandra; Silva, Maria Joa?o

2011-01-01

386

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

387

Water-quality data, Columbia River estuary, 2004-05  

Science.gov (United States)

This report describes the water-quality data collected by the USGS from 2004 through 05 as part of the Ecosystem Monitoring Project and attempts to quantify the spatial distribution and temporal variation of water-quality conditions, including contaminant concentrations, in water and suspended sediment in the Columbia River Estuary, and evaluate these water-quality conditions against aquatic-life standards and guidelines. The analytes to be measured in this study were selected because they are either known to be present in Columbia River salmonids at levels of concern; known to be present in salmonids, but not known if present at levels of concern; present in water at concentrations known to affect endocrine function in adult salmonids; or not previously measured in water, but if present, are of potential concern to salmonid populations.

Morace, Jennifer L.

2006-01-01

388

Map similarity measurement and its application to the Sado estuary  

Directory of Open Access Journals (Sweden)

Full Text Available In the past thirty years GIS technology has progressed from computer mapping to spatial database management, and more recently, to quantitative map analysis and modeling. However, most applications still rely on visual analysis for determining similarity within and among maps. The aim of this study is to compare maps of homogenous areas computed from estuarine sediment characterization indicators, using different approaches. These maps were defined using three different interpolation methods. Different Kappa statistics, visual map overlays or components of agreement and disagreement due to chance, quantity and location were used for single cell and/or neighborhood (hard and soft map comparison. Although the three methods were computed with different statistical techniques, their results are similar, supporting the choice of any of the methods as equivalent and thus of equal value to be used as management units of the estuary. Hence the significance of choosing one of the methods is reduced.

Sandra Caeiro

2003-06-01

389

Geostatistic: a tool for the modeling in estuaries  

International Nuclear Information System (INIS)

We apply geostatistical methods in the modeling of physical, chemical, and biological variables measured in the Cienaga Grande of Santa Marta estuary, located on the Caribbean coast of Colombia. The information taken in March of 1997 was analyzed in this ecosystem. This data set indicates that the variables introduce strong structures of space dependence and thus the application of Kriging and the subsequent preparation of maps of distribution are recommended in order to give explanation for this type of information. Though the sampling was carried out in the region during the dry season, distribution maps indicate in general that the magnitudes of the variables are more similar to those found traditionally in rainy season, possibly because of consequence of the phenomenon El Nino

390

Chapman Conference on Sediment Transport Processes in Estuaries  

Science.gov (United States)

During the week of June 13-17, 1988, 72 sediment transport researchers “aggregated” at the Universidad Nacional del Sur in Bahfa Blanca, Argentina, to participate in an AGU Chapman Conference on Sediment Transport Processes in Estuaries. The main goals of the meeting were to discuss recent advances in estuarine science, to appraise promising future research directions, and to develop contacts and establish working relationships between Latin American and non-Latin- American estuarine researchers. The meeting drew participants from Argentina, Brazil, Chile, Uruguay, Venezuela, the U.S., Canada, Britain, France, the Federal Republic of Germany, The Netherlands, and South Africa. Meeting cosponsors were UNESCO, Secretaria de Ciencía y Técnica, Consejo Nacional de Investigaciones Cientificas y Técnicas, Comision de Investigaciones Cientificas de la Provincia de Buenos Aires, Universidad del Sur, Municipalidad de Bahia Blanca, Asociaciôn Argentina de Geofisicos y Geodestas (AGU sister organization), and the Instituto Argentino de Oceanografia (IADO).

Perillo, Gerardo M. E.; Lavelle, J. William

391

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 Rivers, 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

392

Emissions of biogenic sulfur gases from a danish estuary  

Science.gov (United States)

The diurnal variations in sulfur emission were studied at seven sites in a Danish estuary, Norsminde Fjord. The sites comprised grass vegetation, intertidal mud flats, accretions of green algae, an exposed shore and a river outlet. Direct measurements of emission rates from soil and water were done by a dynamic flux chamber technique in connection with gas Chromatographie detection and separation of the cryogenically trapped sulfur gases. Sulfur gas concentrations in air and sea water were measured together with emission rates at 0.5-1 h intervals over 25-40 h periods. DMS was the most important sulfur gas released from grass and algae, while mostly H 2S was released from intertidal mud flats. OCS, CH 3SH and CS 2 were released from most sites at lower rates. Emission of DMS followed the daylight variations, often with a delay towards maximum emission rates in the evening. H 2S was mostly emitted at night or in short outbursts during low tides. Total sulfur emission rates were 1-10?mol Sm -2 d -1. Extreme rates of 335?mol DMSm -2 d -1 were measured over decomposing green algae ( Ulva lactuca). H 2S emission fractions were < 10 -6 to 2.10 -4. H 2S was detected, along with DMS, CH 3SH, OCS and CS 2, in the oxic seawater of the estuary at diurnal mean concentrations of 0.1-6.5nmol S/ol -1. This may indicate a more widespread occurrence of H 2S in shallow, near-shore waters at nanomolar levels.

Barker Jørgensen, Bo; Okholm-Hansen, Bolette

393

Optical changes in a eutrophic estuary during reduced nutrient loadings  

DEFF Research Database (Denmark)

Loss of water clarity is one of the consequences of coastal eutrophication. Efforts have therefore been made to reduce external nutrient loadings of coastal waters. This paper documents improvements to water clarity between 1985 and 2008–2009 at four stations in the microtidal estuary Roskilde Fjord and find significant relationships to freshwater nutrient loadings. The paper then investigates to which extent changes in phytoplankton biomass (chlorophyll a (Chl a)), non-algal particulate organic matter (POM*), and residual attenuation in the water (K b), respectively, can account for this optical improvement. Vertical light attenuation (K d) declined, on average, by 34 %, accompanying a 71 % reduction of Chl a and an 80 % reduction of POM*. Residual attenuation declined by 26 % over the period in accordance with a measured 34 % decline of dissolved organic nitrogen. Analysis of simultaneous changes in light attenuation and Secchi depth also suggested a reduction of the scatter-to-absorption ratio over time. Considering the stronger reductions of particle concentrations than dissolved organic matter, the contribution of residual attenuation to vertical attenuation increased from 54 to 74 % in 1985 to 78 to 85 % in 2008–2009. Overall, efforts to reduce nutrient loading and improve water clarity appeared to have had a larger impact on POM* than on Chl a and colored dissolved organic matter concentrations in the estuary, which can account for the decrease in the scatter-to-absorption ratio. These optical changes lead to larger improvements of Secchi depth than of vertical light attenuation. The consequence of this is an overestimation (0.45–1.48 m) of the predicted increase of potential seagrass depth limits when based on Secchi depth rather than K d

Pedersen, Troels MØller; Sand-Jensen, Kaj

2014-01-01

394

Creation of residual flows in a partially stratified estuary  

Science.gov (United States)

The creation of residual flows in estuaries is examined using acoustic Doppler current profiler data sets from northern San Francisco Bay. The data sets are analyzed using principal component analysis to examine the temporal variability of the flows which create the residual circulation. It is seen that in this periodically and partially stratified estuary the residual flows are created through a series of pulses with strong variability at the 24-hour timescale, through the interaction of shear, stratification and mixing. This interaction is captured through the use of a dimensionless number, the horizontal Richardson number (Rix), which is developed to examine the local balance between the stratifying and destratifying forces at the tidal timescale. It is seen that Rix is a valuable parameter in predicting the onset of the residual-creating events, with a threshold value of ??? 3 on ebb tides. This critical value is argued to be a threshold, above which the stratification and shear flow create a feedback effect, each further intensifying the other. This feedback results in a highly variable exchange flow which creates the estuarine residual in intermittent pulses rather than as a steady flow. Although typically attributed to baroclinic forcing, an argument is made that these pulses of residual-creating exchange flow could be created by barotropic forcing in the presence of variable stratification which is asymmetric between flood and ebb tides. This result poses a great challenge for turbulence modeling, as the timing and magnitude of stratification and shear must be correctly simulated on the tidal timescale in order to reproduce the effects seen in the data sets presented. Copyright 2001 by the American Geophysical Union.

Stacey, M.T.; Burau, J.R.; Monismith, S.G.

2001-01-01

395

Morphology and modern sedimentary deposits of the macrotidal Marapanim Estuary (Amazon, Brazil)  

Science.gov (United States)

The northern Brazilian coast, east of the Amazon River is characterized by several macrotidal estuarine systems that harbor large mangrove areas with approximately 7600 km 2. The Marapanim Estuary is influenced by macrotidal regime with moderate waves influence. Morphologic units were investigated by using remote sensing images (i.e., Landsat-7 ETM+, RADARSAT- 1 Wide and SRTM) integrated with bathymetric data. The modern sedimentary deposits were analyzed from 67 cores collected by Vibracore and Rammkersonde systems. Analysis of morphology and surface sedimentary deposits of the Marapanim River reveal they are strongly influenced by the interaction of tidal, wave and fluvial currents. Based on these processes it was possible to recognize three distinct longitudinal facies zonation that revels the geological filling of a macrotidal estuary. The estuary mouth contain fine to medium marine sands strongly influenced by waves and tides, responsible for macrotidal sandy beaches and estuarine channel development, which are characterized by wave-ripple bedding and longitudinal cross-bedding sands. The estuary funnel is mainly influenced by tides that form wide tidal mudflats, colonized by mangroves, along the estuarine margin, with parallel laminations, lenticular bedding, root fragments and organic matter lenses. The upstream estuary contains coarse sand to gravel of fluvial origin. Massive mud with organic matter lenses, marks and roots fragments occur in the floodplain accumulates during seasonal flooding providing a slowly aggrading in the alluvial plain. This morphologic and depositional pattern show easily a tripartite zonation of a macrotidal estuary, that are in the final stage of filling.

Araújo da Silva, Cléa; Souza-Filho, Pedro Walfir M.; Rodrigues, Suzan W. P.

2009-03-01

396

Movements and residency of juvenile white steenbras Lithognathus lithognathus in a range of contrasting estuaries  

Science.gov (United States)

Acoustic telemetry was used to assess estuarine area use and movements of an overexploited, endemic fishery species in three South African estuaries; two permanently open systems with contrasting salinity gradients and an intermittently open system. Forty juvenile white steenbras Lithognathus lithognathus (215-379 mm FL) were surgically equipped with acoustic transmitters and tracked for up to 355 days. Tagged fish exhibited high levels of site fidelity and long-term residency within each estuary. Most of their time was spent in the lower reaches of all three estuaries and hypersalinity restricted movements into the upper reaches of the freshwater-deprived estuary. All tagged fish exhibited a distinct diel movement pattern. Most individuals (91%) in the two permanently open estuaries also exhibited a tidal-associated pattern, which comprised mainly small-scale (tens to hundreds of metres) transverse movements between deep channels and shallow banks. Observed behaviour was consistent across a range of estuary sizes, types and physico-chemical conditions. This study has identified critical habitats for juvenile white steenbras across a range of estuarine environments. Estuarine management initiatives need to consider these critical habitats, in order to enhance abundance of juveniles and ultimately recruitment to the marine (adult) population.

Bennett, Rhett H.; Cowley, Paul D.; Childs, Amber-Robyn; Næsje, Tor F.

2015-01-01

397

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

398

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

399

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

400

Tide, buoyancy, and wind-driven circulation of the Charlotte Harbor estuary: A model study  

Science.gov (United States)

The circulation of the Charlotte Harbor (CH) estuary is explored with a primitive equation model that encompasses the estuary and the adjacent West Florida Shelf. Tidal forcing is from the shelf through the inlets. We use the M2, S2, K1, and O1 constituents that account for 95% of the shelf tidal variance. River inflows are by the Peace, Myakka, and Caloosahatchee Rivers at their spring 1998 mean values. Wind effects are considered for upwelling or downwelling favorable winds that are either held constant or allowed to oscillate with varying periodicities. These factors are sequentially added to look at their individual and collective influences on the estuary's circulation and salinity fields. Tidal currents are asymmetric and slightly ebb dominant during spring tides. River inflows, combined with tidal mixing, result in a net estuarine circulation by gravitational convection, and the Coriolis acceleration causes the outflowing currents to be stronger and with lower salinity on the western side of the CH portion of the estuary. By virtue of shallow connecting passages the CH portion acts nearly independently from the San Carlos Bay portion of the combined CH estuary system. The addition of wind affects both the instantaneous and net circulation and salinity distributions by increasing mixing and by imposing a force that may add either constructively or destructively to the gravitational convection. The net up-estuary salt flux is also affected by tides and winds through their contributions to the Reynolds' flux, which exceeds the salt flux by gravitational convection alone.

Zheng, Lianyuan; Weisberg, Robert H.

2004-06-01

401

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

Directory of Open Access Journals (Sweden)

Full Text Available 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: the fresh water runoff during the monsoon season (June-September and the tidal influx of coastal seawater during the summer (October to May season. However, the effects of monsoon related changes on the phytoplankton of the Mandovi estuary are not yet fully understood. An attempt to understand the same has been made here by applying the process of daily sampling at a fixed station throughout the monsoon season. It was noticed that the onset of the monsoon is responsible for an increase in nitrate levels upto 26 ?M from a (chl a as high as 14 ?g·L-1 during the same period. The phytoplankton population was observed through both chemotaxonomy and microscopy and was found to be composed mainly of diatoms. CHEMTAX analysis further uncovers the presence of several other groups of phytoplankton, the presence of which is yet to be reported in many other tropical estuaries. It includes chrysophytes, cyanobacteria, prasinophytes, prymnesiophytes and chlorophytes. The appearance of phytoplankton groups at various stages of the monsoon was recorded, and this data is discussed in relation to environmental changes in the Mandovi estuary during the monsoon season.

Joaquim I. Goes

2013-03-01

402

Developing a coupled analytical model for analyzing salt intrusion in alluvial estuaries  

Science.gov (United States)

A predictive assessment technique to estimate the salt intrusion length and longitudinal salinity distribution in estuaries is important for policy makers and managers to maintain a healthy estuarine environment. In this study, the salt intrusion model of Savenije (2005, 2012) is applied and coupled to an explicit solution for tidal dynamics developed by Cai and Savenije (2013). The objective of the coupling is to reduce the number of calibration parameters, which subsequently strengthens the reliability of the salt intrusion model. Moreover, the fully analytical treatment allows assessing the effect of model forcing (i.e., tide and river discharge) and geometry adjustments (e.g., by dredging) on system performance. The coupled model has been applied to a wide range of estuaries, and the result shows that the correspondence between analytical estimations and observations is very good. As a result, the coupled model is a useful tool for decision makers to obtain first order estimates of salt intrusion in estuaries based on a minimum of information required. References Savenije, H.H.G. (2005), Salinity and Tides in Alluvial Estuaries, Elsevier. Savenije, H.H.G. (2012), Salinity and Tides in Alluvial Estuaries, completely revised 2nd edition, www.salinityandtides.com. Cai, H., and H. H. G. Savenije (2013), Asymptotic behavior of tidal damping in alluvial estuaries, Journal of Geophysical Research, submitted.

Savenije, H.; CAI, H.; Gisen, J.

2013-12-01

403

Southwest Center for Environmental Excellence and Opportunity Year End Report (Final Deliverable)  

Energy Technology Data Exchange (ETDEWEB)

The Southwest Center for Environmental Excellence and Opportunity (Southwest CEEO) has been in existence since October 1996 at Albuquerque Technical Vocational Institute's (TVI) South Valley Campus. The Special Project was comprised of three objectives: (1) Increasing the number of Hispanics in careers related to the environment by improving education and job training opportunities; (2) Strengthening the infrastructure of Hispanic businesses and building their capacity to participate in environmental clean-up activities and potential technology commercialization; and (3) Increasing the Hispanic community's understanding of and participation in environmental protection through improved access to information and outreach activities, paying attention to cultural and linguistic issues. The Southwest CEEO has been successful in each of the above objective areas and continues to provide valuable services to TVI and the community. The Southwest CEEO has developed a scholarship/mentorship program involving business and industry, community organizations, and TVI faculty that will be replicated by other student mentorship programs. The Southwest CEEO has awarded approximately $50,000 over the two-year program funded by the U.S. Department of Energy Oakland Operations Office. The Southwest CEEO has also developed a K-12 partnership with Albuquerque Public Schools (APS) to enhance environmental education for students and professional development for teachers. Incorporated into these student activities are experimental learning opportunities and curriculum development and/or enhancement. The Southwest CEEO has worked closely with the TVI Small Business Development Center (SBDC) to support Hispanic businesses in technology partnership activities. The Southwest CEEO in partnership the TVI SBDC has provided a large business forum and business workshops. In addition, the Southwest CEEO has developed a Technology Transfer Model that will be expanded in the future to a technology transfer guide to be used by New Mexico SBDC's. The Southwest CEEO has been active in the Albuquerque South Valley Community and Bernalillo County to promote more Hispanic community participation in environmental issues and education opportunities. The Southwest CEEO has hosted community environmental forums, workshops, and conferences. The Southwest CEEO is also participating on the Bernalillo County Environmental Health Department Technology Deployment Initiative Advisory committee, Hispanic Statement of Cooperation Group, and the Groundwater Protection and Action Plan (GPAP) Committee.

None

1998-11-09

404

ESTIMATING THE STOCK OF GLASS EELS IN AN ESTUARY BY MARK-RECAPTURE EXPERIMENTS USING VITAL DYES  

OpenAIRE

Glass eels (Anguilla anguilla) arriving after the fishing season in the Vilaine estuary (France) were caught by boat and at a trapping ladder located at a blocking dam upstream in the estuary. They were marked with Bismarck brown, rhodamine B or neutral red, and released into the estuary. The effect of marking on behaviour, mortality and recapture differed according to the dye and concentration used. The glass eels also differed in response to marking according to their origin. Estuarine glas...

Briand, C.; Fatin, D.; Feunteun, E.; Fontenelle, G.

2005-01-01

405

Comparison of empirical models with intensively observed data for prediction of salt intrusion in the Sumjin River estuary, Korea  

OpenAIRE

Performance of empirical models has been compared with extensively observed data to determine the most suitable model for prediction of salt intrusion in the Sumjin River estuary, Korea. Intensive measurements of salt intrusion were taken at high and low waters during both spring and neap tide in each season from August 2004 to April 2007. The stratification parameter varied with the distance along the estuary, tidal period and freshwater discharge, indicating that the Sumjin River estuary ex...

Shaha, D. C.; -k Cho, Y.

2009-01-01

406

Acute toxicity bioassay with the amphipod, Grandidierella bonnieroides S. after exposure to sediments from an urban estuary (Macaé River Estuary, RJ, Brazil).  

Science.gov (United States)

Acute toxicity to Grandidierella bonnieroides and physicochemical analysis were used for quality assessment of the sediment of the Macaé River urban estuary, located in the Brazilian coast where rapid socioeconomic growth has been induced by offshore oil and gas exploration at the Campos Basin. Sediment samples were collected during four events in four sampling sites of the estuary and also in a control site. Organism mortality after exposure to the estuarine sediments was, on average, 30 % a value higher than in the control site where it was 10 %. This result together with the physicochemical analysis suggests an initial toxicity condition of the sediments from this aquatic coastal environment. PMID:23124519

Molisani, Mauricio Mussi; Costa, Rafael Nogueira; Cunha, Priscila; de Rezende, Carlos Eduardo; Ferreira, Maria Inês Paes; de Assis Esteves, Francisco

2013-01-01

407

The "Southwest Effect" Revisited: An Empirical Analysis of the Effects of Southwest Airlines and JetBlue Airways on Incumbent Airlines from 1993 to 2009  

Directory of Open Access Journals (Sweden)

Full Text Available The expansion of Southwest Airlines and JetBlue Airways has sparked new empirical interest in the effects of low-cost carriers (LCC on existing airfares. Namely, empirical studies have attempted to capture the threat, or potential competition, of an entrant. This paper examines incumbent airline prices as a result of potential and actual competition from both Southwest Airlines and JetBlue Airways from 1993 to 2009 by analyzing mean airfares as well as price dispersion on incumbent routes. I incorporate a panel OLS with fixed effects model as well as GLS model with random effects. Consistent with re-cent literature, this paper finds that legacy incumbents cut fares significantly when threatened by Southwest Airlines. However, low-cost incumbents do not exhibit the same magnitude of pre-emptive price cutting. When threatened by JetBlue, neither legacy nor low-cost carriers cut fares significantly, suggest-ing that incumbents react differently when threatened by Southwest versus JetBlue. The evidence of increased price dispersion is mixed with price dis-persion decreasing on legacy carrier routes as a result of Southwest threat and entry but increasing on legacy carrier routes as a result of JetBlue threat and entry.

Steven M. Wu

2012-09-01

408

Total mercury in the fish Trichiurus lepturus from a tropical estuary in relation to length, weight, and season  

OpenAIRE

The Goiana River Estuary (7º30'S 34º47'W) is a typical estuary of the semi-arid tropical regions. This estuary shelters a rich fauna of fish, crustaceans and mollusks which play an important role in the life of traditional populations. It is also the main recipient of the effluents from the sugarcane agro-industry and sewage from settlements and villages. Trichiurus lepturus (n = 104), from the Goiana Estuary were examined for total mercury contents during ten months (2005 to 2007) spaning ...

Barbosa, Scheyla C. T.; Costa, Monica F.; Mário Barletta; David Valença Dantas; Kehrig, Helena A.; Olaf Malm

2011-01-01

409

The Ostracoda (Crustacea) of the Tina Menor estuary (Cantabria, southern Bay of Biscay): Distribution and ecology  

Science.gov (United States)

Recent ostracods from the Tina Menor estuary (northern Spain, southern Bay of Biscay) have been analysed. Twenty-five species have been identified for the first time, 20 with living individuals during the sampling period. The most abundant species are Leptocythere castanea, Leptocythere porcellanea, Loxoconcha elliptica, Cytherois fischeri, and Hemicytherura hoskini, Leptocythere psammophila and Semicytherura aff. angulata. These species are grouped into four assemblages defining different environments: muddy inner estuary with euryhaline species (L. elliptica); middle estuary with silty sand flats and low marsh environments (L. castanea, L. porcellanea and C. fischeri); sandy outer estuary with marine characteristics (H. hoskini, S. aff. angulata, Leptocythere baltica and L. psammophila); and littoral to inner shelf environment (Caudites calceolatus, H. hoskini and Callistocythere murrayi). In the middle estuary, L. castanea also delimits sandy-silty low marshes, and L. porcellanea and C. fischeri the vegetated ecosystems. Multivariate analyses with the samples and species (cluster Q-type and detrended and canonical correspondence analysis) confirm that ostracod distribution in the Tina Menor estuary is controlled by sediment grain size and by the distance to the mouth of the estuary (associated to salinity). The geographical height in relation with mean tide levels (and therefore with emersion periods) also plays an important role in distribution. The results of this study confirm ostracod validity as tide-level markers due to the presence of C. fischeri below the MHWNT (mean high water neap tide), whereas L. castanea and L. porcellanea are present between the MHWNT and MHW (mean high water) levels. Ostracods can also indicate environmental changes due to human-influenced processes. Abundant individuals of L. elliptica in some areas of the middle estuary evidence discharges of lower-salinity water from a nearby fish farm. Ostracods from the marine shelf reach the inner estuary, but continental species are not provided by the rivers. The low river influence may be due to Nansa River flow regulation upstream, which hampers the transport of fluvial sediments, resulting in an increase in sand in the mudflat and low marshes, the latter fact confirmed by the numbers of L. castanea and L. porcellanea, much higher than in other estuaries in the southern Bay of Biscay.

Martínez-García, Blanca; Pascual, Ana; Rodríguez-Lázaro, Julio; Martín-Rubio, Maite; Rofes, Juan

2013-10-01

410

Tidal wetland conservation and restoration for flood mitigation in estuaries and deltas: examples and global potential  

Science.gov (United States)

Low-lying and densely populated deltas and estuaries are world widely exposed to flood risks caused by storm surges. On the one hand, global change is increasing these flood risks through accelerating sea level rise and increasing storm intensity, but on the other hand, local-scale human impacts on deltas and estuaries are in many cases even more increasing the vulnerability to floods. Here we address the degradation and reclamation of tidal wetlands (i.e. salt marshes in the temperate zone and mangroves in the tropical zone) as a major source for increasing vulnerability to flooding of estuaries and deltas. Firstly, we present examples of flood mitigation by tidal wetland conservation and restoration, and secondly we explore the potentials and limitations for global application of this approach of ecosystem-based flood defense (see Temmerman et al. 2013). First, we use the Scheldt estuary (SW Netherlands and Belgium) as an example where historic wetland reclamation has importantly contributed to increasing flood risks, and where tidal marsh restoration on the previously reclaimed land is nowadays brought into large-scale practice as an essential part of the flood defense system. Based on data and hydrodynamic modelling, we show that large-scale historic marsh reclamation has largely reduced the water storage capacity of the estuary and has reduced the friction to propagating flood waves, resulting in an important landward increase of tidal and storm surge levels. Hydrodynamic model scenarios demonstrate how tidal and storm surge propagation through the estuary are affected by tidal marsh properties, including the surface area, elevation, vegetation and position of marshes along the estuary. We show that nowadays tidal wetland creation on previously reclaimed land is applied as an essential part of the flood defense system along the Scheldt estuary. Secondly, a global analysis is presented of the potential application of tidal wetlands in flood mitigation in estuaries and deltas worldwide. We discuss the societal benefits and drawbacks of wetland creation for flood defense, and provide an estimation of where on Earth this approach could be feasible. This shows that many of the largest urban populations that are at risk from coastal flooding, are located in large deltas and estuaries, such as in Southeast Asia, North America and Europe. We argue that many of these vulnerable areas are potentially well suited to include wetland conservation and restoration as an essential part of adaptation and mitigation strategies against storm surge flood risks. References: Temmerman S., Meire P., Bouma T.J., Herman P.M.J., Ysebaert T., De Vriend H.J. (2013) Ecosystem-based coastal defense in the face of global change. Nature, 504, P. 79-83, doi:10.1038/nature12859.

Temmerman, Stijn; Smolders, Sven; Stark, Jeroen; meire, patrick

2014-05-01

411

76 FR 28767 - Desert Southwest Customer Service Region-Rate Order No. WAPA-152  

Science.gov (United States)

...Intertie) and Ancillary Services Rates for Western Area...existing NITS and Ancillary Services formula rates expire...FURTHER INFORMATION CONTACT: Mr. Darrick Moe...Manager, Desert Southwest Customer Service Region, Western...

2011-05-18

412

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

Science.gov (United States)

...the Southwest Power Pool, Inc. (SPP) Strategic Planning Committee (SPC), as noted below. Their attendance is part of the Commission's ongoing outreach efforts. SPP SPC March 28, 2011 (10 a.m.-4 p.m.), DFW Hyatt Regency,...

2011-03-21

413

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

414

Three new species of Lathrobium Gravenhorst (Coleoptera, Staphylinidae, Paederinae) from Sichuan, Southwest China  

OpenAIRE

Three new species of the genus Lathrobium Gravenhorst, 1802 from Sichuan Province, Southwest China are described and illustrated: L. acutissimum sp. n., L. hailuogouense sp. n. and L. labahense sp. n. A checklist of Chinese Lathrobium is provided.

Zhong Peng; Li-Zhen Li; Mei-Jun Zhao

2012-01-01

415

Three new species of Lathrobium Gravenhorst (Coleoptera, Staphylinidae, Paederinae) from Sichuan, Southwest China  

OpenAIRE

Three new species of the genus Lathrobium Gravenhorst, 1802 from Sichuan Province, Southwest China are described and illustrated: Lathrobium acutissimum sp. n., Lathrobium hailuogouense sp. n. and Lathrobium labahense sp. n. A checklist of Chinese Lathrobium is provided.

Peng, Zhong; Li, Li-zhen; Zhao, Mei-jun

2012-01-01

416

DETERMINANTS OF INCOME DIVERSIFICATION AMONGST RURAL FARM HOUSEHOLDS IN SOUTHWEST NIGERIA  

OpenAIRE

This study aims to analyze the determinants of household income diversification and the share of income sources to total household income among the rural farm households in southwest Nigeria. The study drew a sample of 411 rural farm households through a multi-stage sampling technique from three states in southwest Nigeria and the data obtained were analyzed using the Herfindal index and Tobit regressions. Results indicate that the level of income diversification among rural farm households...

Idowu, Adewunmi O.; Aihonsu, John O. Y.; Olubanjo, Olugbenga O.; Shittu, Adebayo M.

2011-01-01

417

Exploring the Etiologic Factors and Dynamics of Prescription Drug Abuse in Southwest Virginia  

OpenAIRE

Background: Prescription drug abuse in Southwest Virginia is a serious problem affecting indi-viduals, families, and communities. The aim of this study was to characterize and understand the extent of the prescription drug abuse problem in Southwest, Virginia as well as the dynamics that surround that abuse. More specifically, the study focused on learning the extent of the problem along with which prescription drugs are typically used prior to entering treatment, reasons for prescription dru...

Redican, Kerry J.; Marek, Lydia I.; Jp, Donna Brock; Mccance-katz, Elinore F.

2012-01-01

418

Transformation of social networks in the late pre-Hispanic US Southwest  

OpenAIRE

The late pre-Hispanic period in the US Southwest (A.D. 1200–1450) was characterized by large-scale demographic changes, including long-distance migration and population aggregation. To reconstruct how these processes reshaped social networks, we compiled a comprehensive artifact database from major sites dating to this interval in the western Southwest. We combine social network analysis with geographic information systems approaches to reconstruct network dynamics over 250 y. We show how s...

Mills, Barbara J.; Clark, Jeffery J.; Peeples, Matthew A.; Haas, W. R.; Roberts, John M.; Hill, J. Brett; Huntley, Deborah L.; Borck, Lewis; Breiger, Ronald L.; Clauset, Aaron; Shackley, M. Steven

2013-01-01

419

Investigating turkey (Meleagris gallopavo) domestication in the Southwest United States through ancient DNA analysis  

OpenAIRE

As one of the New World’s few animal domesticates, the turkey (Meleagris gallopavo) represented an important resource for the Ancestral Puebloans of the Southwest United States. Despite the rich database of Southwest archaeology, several questions concerning the domestication and use of turkeys remain unanswered, including the geographic origin of turkey domestication, the pre-contact flock management and breeding practices, and the changing roles of wild and domestic turkeys through time. ...

Speller, Camilla Filomena

2009-01-01

420

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

421

Changes in a temperate estuary during the filling of the biggest European dam.  

Science.gov (United States)

This study aimed to determine whether and how the disruption of river flow, during the filling of the Alqueva dam, influenced the variability of abiotic and biotic factors in the Guadiana estuary, particularly the abundance and distribution of anchovy eggs. River inflow was found to be the most important factor in determining abiotic and biotic variability in the Guadiana estuary. Seasonal patterns were obscured by long periods of low inflow (mid April to early December 2002), which caused marked changes in the estuary. The estuarine turbidity maximum zone was displaced towards the upper estuary, to at least 38 km from the river mouth, 8 to 16 km upstream from previous records. The dynamics of nutrient stoichiometry was also affected. In the upper and middle estuary, P was more potential limiting than N and potential Si limitation was only frequent on the coast, with direct and/or indirect influence in changing phytoplankton dynamics and composition. Previously, the upper estuary alternated between potential P limitation during winter, Si limitation during spring and mid summer and N limitation during mid summer and autumn. The flooding of vast areas in the catchment of the dam probably caused the increase of DSi concentrations, as well as maximal N and P loadings. The abundance of larval stages of anchovy decreased, putatively because estuarine productivity has also decreased. In April 2002 there was an uncontrolled discharge from the Alqueva dam, which reduced the abundance of anchovy eggs by 99.99%. It is suggested that dam managers should mimic, as much as possible, the natural river flow, in order to minimize the impact on downstream ecosystems. Management efforts should not be restricted to the areas upstream of the dam, but should also encompass the estuary and adjacent coastal area. PMID:19155053

Morais, Pedro; Chícharo, Maria Alexandra; Chícharo, Luís

2009-03-15

422

Response of sediment dynamics in the York River Estuary, USA to tropical cyclone Isabel of 2003  

Science.gov (United States)

Tropical Cyclone Isabel of 2003 generated large storm surge, strong waves, and subsequent river flooding in the York River Estuary, USA during its passage across the Chesapeake Bay region. A 3D model was used to investigate the changes of sediment concentration, sediment flux, and the recovery time of the York River Estuary to its naturally evolved condition without the storm. The results showed that two sediment concentration peaks appeared during the storm event. The first one was induced by the large upstream flow and waves during the storm surge rising period, and the later one was caused by the strong downstream flow during the descent of the storm surge. The advection, which was induced by the barotropic gradient, dominated the sediment flux during the storm event. The sediment fluxes increased by a factor of 100 during the rise and descent of the storm surge. A large amount of sediment that was transported into the estuary and eroded from the seabed during the rising of the storm surge was quickly transported out of the estuary during the descent of the storm surge. Waves played a key role in stirring the seabed and increasing the sediment concentration during the storm. Subsequent high freshwater inflow changed the sediment loading and hydrodynamics in the estuary, and thus, influenced the estuarine turbidity maximum (ETM) dynamics profoundly. The ETM moved downstream with the river flooding initially and returned upstream with the waning of river flooding and the re-establishment of gravitational circulation. The effect of river flooding on sediment concentration varied spatially and depended on the changes of ETM locations and vertical mixing. The model results suggest that a large amount of sediment was transported out of the estuary during the storm event and the subsequent river flooding had a larger impact on recovery time of the estuary.

Gong, Wenping; Shen, Jian

2009-08-01

423