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1

PBDE and PCB contamination of eels from the Gironde estuary: from glass eels to silver eels.  

Science.gov (United States)

Since the 1980s, the eel population has been decreasing dangerously. Persistent Organic Pollutants (POPs) such as Polychlorinated Biphenyls (PCBs) are one of the suspected causes of this decline. A preliminary study of PCB contamination carried out on different fish from the Gironde estuary (southwest of France, Europe) has shown a relatively high level of contamination of eel muscles. In order to characterize the contamination level of PCBs and PBDEs (PolyBrominated Diphenyl-Ethers) in eels from this estuary more than 240 eels were collected during the years 2004-2005 in the Gironde estuarine system, from glass eels to silver eels. Individual European eels were grouped according to length and localization sites. The results have shown a low contamination level of glass eels: respectively 28±11 ng g(-1)dw for PCBs and 5±3 ng g(-1)dw for PBDEs. The contamination level in eels (expressed in ng g(-1)dw) increases from glass eels to silver eels up to 3399 ng g(-1)dw of PCBs for the most contaminated silver eel. Such levels of PCBs similar to those observed in Northern Europe, could raise sanitary problems connected with the World Health Organization (WHO) recommendations. These results are worrying for the local people who regularly eat eels caught in the Gironde estuary. PMID:21256534

Tapie, Nathalie; Le Menach, Karyn; Pasquaud, Stéphanie; Elie, Pierre; Devier, Marie Hélène; Budzinski, Hélène

2011-03-01

2

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

Science.gov (United States)

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

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

2014-03-01

3

Spawning sounds in meagre Argyrosomus regius recorded in the Gironde estuary, France  

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During their spawning period (June to mid-July) in the Gironde estuary, meagre Argyrosomus regius produce two distinct sounds: regular long grunts, the most common calls, and sometimes also short grunts. It is suggested that long grunts serve the formation of spawning aggregations and short grunts announce the beginning of courtship behaviour. The meagre's long grunts include long series of 30-112 closely spaced pulses placed into call units. Each pulse produces multiple and rapidly decaying ...

Lagardere, Jean-paul; Mariani, A.

2006-01-01

4

A comparative study of mercury contamination in the Tagus estuary (Portugal) and major French estuaries (Gironde, Loire, Rhône)  

Science.gov (United States)

Concentrations of mercury were determined for the waters, suspended matter and sediments of the Tagus and of major French estuaries. The Tagus estuary is one of the most contaminated by mercury derived from the outfalls of a chloralkali plant and from other industrial sources. In deposited sediments the median level, 1·0 ?g Hg g -1, is twenty times higher than the natural background and Hg contents depend on the sediment grain-size, age and the distance from waste-outfalls. Suspended matter is more regularly and highly contaminated (median value: 4·5 ?g Hg g -1). In the French estuaries Hg levels in the suspended material decrease with salinity due to dilution and/or remobilization processes. In June 1982, in the Loire estuary, high values of Hg are observed in the middle estuary and attributed to urban and industrial sources. In the Tagus estuary, the general distribution of total dissolved Hg confirms the contamination: it increases seaward from 10 ng 1 -1 in the river to 80 ng 1 -1 in the estuary outlet. The dissolved Hg is almost totally organic in the river, inorganic in the middle estuary due to inorganic Hg effluents and again organic in the lower estuary. This variation is related to the dissolved organic carbon values. The dissolved Hg levels in the Loire Estuary (5-300 ng 1 -1) are much higher than in the Gironde estuary (3-6 ng 1 -1) and of the same order as those observed in the Tagus estuary.

Figueres, G.; Martin, J. M.; Meybeck, M.; Seyler, P.

1985-02-01

5

Mobility of trace metals associated with urban particles exposed to natural waters of various salinities from the Gironde Estuary, France  

Energy Technology Data Exchange (ETDEWEB)

Background, aim and scope: Urban systems are hot spots of environmental pollution caused by manifold anthropogenic activities generating traffic-related, industrial and domestic emissions. Besides air, soil and groundwater pollution, pollution of surface water systems is of major concern because they are often (ab)used to export waste of various consistence out of urban areas and become contaminated on varying scales. The Gironde Estuary (southwest France) is affected by various anthropogenic contaminations derived from historic polymetallic pollution mainly due to former mining and ore-treatment and, additionally, from agriculture and urban areas. Although detailed knowledge is available on the impact of mining and anthropogenic activities on the water quality of the Gironde Estuary, almost nothing is known on the urban impact, even though the Garonne Branch which is one tributary of the Gironde system crosses the large urban agglomeration of Bordeaux. The present work links urban geochemistry and estuary research and aims at evaluating the mobility of potentially toxic trace elements (Cd, Cu, Zn, V, Co, Mo, Pb) associated with urban particles under estuarine conditions owing to the particles' role as potential vectors transporting urban pollutants into the estuary. For this, environmentally available fractions of trace elements in representative urban particles (urban dust, road sediment, riverbank sediment, construction materials) from the city of Bordeaux were extracted by natural estuarine waters of varying salinities and compared to commonly applied HNO{sub 3} extractions. Materials and methods: For the assessment of the urban particles' contribution to the pollution of the Gironde/Garonne system, various particle types were sampled in Bordeaux: road sediments, urban bulk deposition, construction materials (concrete, asphalt, tile and gravel) and flood sediments. Potentially environmental available fractions of Cd, Cu, Zn, V, Co, Mo and Pb were extracted by means of concentrated HNO{sub 3}, estuarine freshwaters and waters of two different salinities (S=15 and S=31). Analysis of trace elements was carried out by means of quadrupole inductively coupled plasma-mass spectrometry. Furthermore, single particles from road sediments were characterised with scanning electron microscopy (SEM). Results: SEM analysis clearly showed that some particles contained fairly high concentrations of potentially toxic trace elements. Extractions of materials investigated by varying acidities and salinities documented that the potentially bioavailable fractions extracted by concentrated HNO{sub 3} may cover wide concentration ranges. Natural estuarine waters of various salinities (S=0.5; S=15; S=31) extracted high proportions of Co, Ni, Cu, Zn and Cd from urban particles, especially for high-salinity water (S=31). Extractions with freshwater revealed the lowest concentrations of desorbed trace elements. Particulate Mo, Pb and V showed similar or lower mobility in saline water compared with freshwater, depending on the sample type. Discussion: Trace element mobility in estuarine waters varied according to the type of urban particles and depended on salinity for Co, Ni, Cu, Zn and Cd. This is of high importance for towns located directly at the coast or for cities like Bordeaux, where water courses crossing the agglomerations are connected to saline water masses. Since trace elements desorbed from particles in saline waters may become highly bioavailable, they bear a potential risk for organisms. Comprehensive studies on the behaviour of urban particles in estuarine waters and the related potential environmental impact are still missing. Conclusions: Saline waters mobilise relatively high amounts of Co, Ni, Cu, Zn and Cd from urban particles suggesting considerable metal fluxes from riverine urban systems into coastal waters. Although estimates of trace metal inputs by urban bulk deposition (urban dust) and other types of urban particles are preliminary for Bordeaux and may bear important uncertainties due to several assumptions

Schaefer, Joerg; Blanc, Gerard [Bordeaux Univ., Talence (France). UMR 5805 EPOC; Norra, Stefan [Karlsruhe Univ. (Germany). Inst. of Mineralogy and Geochemistry; Klein, Daniel [Bordeaux Univ., Talence (France). UMR 5805 EPOC; Karlsruhe Univ. (Germany). Inst. of Mineralogy and Geochemistry

2009-08-15

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Time concepts in hydrodynamic systems with an application to 7Be in the Gironde estuary  

International Nuclear Information System (INIS)

The main definitions involving time concepts in dynamic systems are reviewed and extended. It is shown that a better understanding of aquatic systems can be achieved taking into consideration their mean age. The relationships between residence time and mean age and the behaviour of chemical components in dynamic systems is studied; the importance of radionuclides whose decay is perfectly known is demonstrated. Finally, an application to the Gironde estuary (France) is attempted using a cosmic ray-produced radionuclide, 7Be, whose half-life is especially relevant to macrotidal estuarine dynamics. (Auth.)

7

Comparison of vertical mobile hydroacoustic survey strategies for monitoring fish distributions in the Gironde estuary (France)  

Science.gov (United States)

Today, hydroacoustic technologies are able to monitor fish populations and assess fish biomass by providing data of a high spatio-temporal resolution, and without damaging the environment. Such techniques are widely used in lakes and marine environments, but they remain much less tested in shallow waters - especially in estuarine habitats. Our study was carried out using a strictly methodological approach. This was necessary in order to take into account the highly changeable nature of the ecosystem in question. Hydroacoustic surveys were conducted in the mesohaline part of the Gironde estuary using SIMRAD EK60 split-beam echosounders, operating simultaneously at two frequencies (70 kHz and 120 kHz). Different mobile hydroacoustic surveys were tested in different seasons, with vertical acquisition, in order to compare variability of results due to the sampling strategy, and to validate the relevance of our design by repeating the surveys. The results obtained on survey design choices gave similar outcomes when sampling was carried out with or against the current and between two mobile designs. The comparison between flood and ebb tides gave different results from one day to another but we observed the same evolution for each flood tide or for each ebb tide on several successive days. This acoustic study in the Gironde estuary was used to validate a reliable sampling mobile design. It is the first step in the process of gaining a better understanding of estuarine ecosystems, an understanding that will be enhanced by combining our data with data from a variety of other sources.

Samedy, V.; Josse, E.; Guillard, J.; Pierre, M.; Girardin, M.; Boët, P.

2013-12-01

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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  

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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

9

Cadmium contamination of three bivalve species (oysters, cockles and clams) in Nord Médoc salt marshes (Gironde estuary, France): Geochemical survey and metal bioaccumulation kinetics  

Science.gov (United States)

A historical Cd pollution of the Lot-Garonne River system (France) bas led to the contamination of sediment and water of the Gironde Estuary. In spite of the decrease of fluvial Cd inputs since the early 90ies, Cd concentrations in the Gironde oysters remain higher than European norms (5 ?g.g^{-1} dry mass) and the “zone D” classification of the estuary prohibits bivalve production and harvesting for human consumption. A geochemical survey in salt marshes used for aquaculture (crustaceans) has been conducted in order to assess the heavy métal contamination level in these systems periodically alimented by the Gironde water, accompanied by caging experiments on three bivalve species of economical interest: oysters (Crassostrea gigas), cockles (Cerastoderma edule) and clams (Ruditapes philippinarum) to study heavy metal accumulation in these organisms. Distribution of heavy metals in this system is controlled by biogeochemical processes and is independent of routine water management. Contamination levels in the studied species indicate the high accumulation of Cd by oysters. On the other hand, Cd concentrations in benthic species, such as cockles and clams, are clearly lower than European safety limits for human consumption.

Baudrimont, M.; Schäfer, J.; Marie, V.; Maury-Brachet, R.; Bossy, C.; Durrieu, G.; Palvadeau, A.; Maneux, E.; Boudou, A.; Blanc, G.

2003-05-01

10

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

International Nuclear Information System (INIS)

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

11

Modeling of Sediment Transport and Turbidity Maximum in the Gironde Estuaries (france) by a Two-Phase Non-Hydrostatic Model  

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Nowadays, there exist two approaches for modeling sediment transport in estuaries: classical (single-phase) and two-phase ones. Almost all existing sediment transport models are based on the single-phase approach, in which a hypothesis on "passive scalar" is adopted. Solid particles are considered as a simple tracer that moves at the same velocity as fluid particles. A numerical study for sediment transport and turbidity maximum in the Gironde Estuary was done by Li et al. (1994) using single-phase approach The second, two-phase approach is first used in particle-gas domain, in particular, for fluidized bed problems. In this approach, all interactions such as fluid-particles, particle-particle and particles-walls are taken into computation. Since the consolidation of solid particles could be taken into computation in the two-phase models, no fictive definition for the bed is necessary as the case of mono-phase models. Fluid-bed interaction, which is in fact the exchange on the water-sediment interface near the bottom, as well as falling velocity of the solid particles are evaluated naturally in solving two-phase Navier-Stokes equations. Therefore, the two-phase approach is a promising one for modeling sediment transport (Barbry 2000, Chauchat 2007 and Nguyen et al 2009). Recently, Lévy et al. (2011) has presented a two-phase model, based on the hydrostatic hypothesis for simulating suspended-sediment transport and the Turbidity Maximum (TM) in the Gironde Estuary. The authors show that one of the benefits of a two-phase model resides in the treatment of the estuary bed. In proximity of the bed, the fluid-mud layer moves not only in vertical but also in horizontal, under the influence of tidal currents and river flows and serves as a solid-particle reservoir for the TM. However the calculated TM has not been enough developed on the vertical. This is due to the fact that, by the hydrostatic hypothesis, the vertical component of the fluid phase has been only determined by the mass conservation, thus not by the momentum equation. The purpose of this article is to present a two-phase, non-hydrostatic model, and to show the perspectives in developing and improving this model for sediment transport modeling. The Eulerian approach is used. The model is based on solving Navier-Stokes' equations for the solid and fluid phases by using a finite-volume method, coupled with a projection technique. The attention is paid to ensure that all numerical schemes used in the model must be strictly conservative. The model is used to simulate the fine-grained sediment transport in the Gironde estuary (France). The estuary with three branches (Garonne, Dordogne and Gironde) has been discretised by a computing of dx=300 m and of 41 points over the vertical. A coupling technique for three branches has been proposed and realized on a PALM Plate-form. The numerical results obtained from modeling of sediment transport and turbidity maximum in the Gironde estuary (France) using two-phase approach are presented. A comparison of the results obtained by both single- and two-phase approaches has been done to illustrate the advantages of two-phase approach over single-phase one.

Nguyen, K.; Ray, R. K.; Pham-Van-Bang, D.

2012-12-01

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Increase of marine juvenile fish abundances in the middle Gironde estuary related to warmer and more saline waters, due to global changes  

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Estuaries have an essential ecological function for several marine fish species, that use these systems as nurseries. Previous studies in the Gironde estuary have reported an increase in water temperature and an extended seawater intrusion associated to global changes. In this study, we evaluated whether these changes impact the nursery function in the middle part of the system, based on the analyses of long-term data series (1991-2009) collected in that area. Trend analysis, correlations and generalized additive models (GAM) were computed in order to study the influence of water temperature and salinity changes on marine juveniles occurrence/densities. Results showed that densities of all the studied species (i.e. Engraulis encrasicolus, Sprattus sprattus, Dicentrarchus labrax, Solea solea, Argyrosomus regius, Merlangius merlangus) significantly increased over the period considered. Changes in water temperature and seawater intrusion contributed to explain the variability in presence/absence and in densities of the majority of these species. However, the deviance explained by GAM and the relevance of these two explanatory variables differed considerably according to species. For most species, it was suggested that the interaction of these two factors, and their effects on other variables, may explain the increase in abundance in the middle part of the Gironde. The effects of global changes in this estuarine system may favour its nursery function for marine juveniles, but some evidence of effects at a wider scale (community and ecosystem levels) may alter the structure and functioning of this system.

Pasquaud, Stéphanie; Béguer, Mélanie; Larsen, Maja Hjort; Chaalali, Aurélie; Cabral, Henrique; Lobry, Jérémy

2012-06-01

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Double radio-tracer tagging of mud in the Gironde: an experimental study of the behaviour of a metallic pollutant in an estuary  

International Nuclear Information System (INIS)

In order to understand the behaviour of metals accidentally introduced into an estuarine system, an experiment using radioactive tracers was conducted in the Gironde estuary. Based on the preliminary laboratory studies on the reactivity of radioisotopes 65Zn and 175+181Hf with different physicochemical agents, they were proved to be suitable for the experiment designed. A quantity of sediment contaminated by these two isotopes was introduced in the upstream part of the Gironde. During transport downstream, it was observed that the Zn/Hf couple on the sediment decreased from an initial ratio of 0.7 to 0.07-0.05 in the fluid mud lenses and in the bottom sediment of the lower estuary at the end of the experiment (3 months). It was lower than 0.2 in the suspended sediments. This is considered to indicate that a part of the zinc is dissociated from the hafnium and released from its particulate support; this signifies a solubilization of the zinc. These experimental data give a new insight into the problem concerning the decrease of stable zinc associated with suspended sediment at the fresh water/salt water interface

14

Geochemical signals and source contributions to heavy metal (Cd, Zn, Pb, Cu) fluxes into the Gironde Estuary via its major tributaries.  

Science.gov (United States)

Daily measurements of water discharges and suspended particulate matter (SPM) concentrations and monthly sampling for trace element analyses (Cd, Zn, Pb and Cu) were conducted from 1999 to 2002 on the Garonne, Dordogne and Isle Rivers, the three main tributaries of the Gironde Estuary, France. Dissolved and particulate Cd, Zn, Pb and Cu concentrations in the Isle River were generally higher than those in the Garonne River, despite the known historical polymetallic pollution affecting the Lot-Garonne River system. Even if the relatively high dissolved metal concentrations in the Isle River may be of importance for the local ecosystem, metal inputs into the estuarine and coastal zones are mainly controlled by fluvial transport via the Garonne River. Characteristic element concentration ratios (e.g., Zn/Pb) in SPM and stream sediments from the Dordogne and Isle Rivers suggest two different metal source areas with distinct geochemical signals. Low Zn/Pb ratios (Massif Central, featuring various ore deposits and mining areas. High Zn/Pb ratios were assigned to downstream sources (e.g., vineyards), partly explaining high Zn and Cu concentrations and high Cu/Pb ratios (>0.8) in SPM. Although SPM derived from the upstream parts of the studied watersheds may greatly contribute to the observed fluvial metal transport (up to approximately 80% for Pb), the results suggest that intensive agriculture also considerably influences gross metal (e.g., Zn, Cu) fluxes into the Gironde Estuary. Relative contributions of upstream and downstream source zones may vary from one year to another reflecting hydrological variations and/or reservoir management. Monitoring fluxes and identifying distinct geochemical signals from source areas in heterogeneous watersheds may greatly improve understanding of contaminant transport to the coast. PMID:16879859

Masson, Matthieu; Blanc, Gérard; Schäfer, Jörg

2006-10-15

15

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

16

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

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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

17

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 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

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

Selenium in sediments and biota from estuaries of southwest England.  

Science.gov (United States)

Selenium concentrations have been measured in sediment, fucoid macroalgae and macroinvertebrates from four estuaries of SW England (Yealm, Plym, Looe, Fal). Sediment concentrations ranged from about 0.4 ?g g(-1) in the Yealm to 1.49 ?g g(-1) at one site in the Plym. Concentrations in Fucus vesiculosus (0.05-0.31 ?g g(-1)) and F. ceranoides (0.05-0.51 ?g g(-1)) were significantly lower than corresponding concentrations in sediment but there was no correlation between algal and sediment concentrations. Selenium concentrations in Littorina littorea (~4 ?g g(-1)), Hediste diversicolor (2.82-12.68 ?g g(-1)), Arenicola marina (~17 ?g g(-1)) and Scrobicularia plana (1.18-6.85 ?g g(-1)) were considerably higher than concentrations in macroalga or sediment, suggesting that Se is effectively accumulated from the diet. Although Se concentrations in some invertebrates exceed toxicity thresholds for the diet of predacious birds and fish, no specific evidence for Se toxicity exists in these estuaries. PMID:23773950

Turner, Andrew

2013-08-15

20

Biomonitoring of thallium availability in two estuaries of southwest England.  

Science.gov (United States)

Thallium is a highly toxic metal whose biogeochemical behaviour in the marine environment is poorly understood. We measured Tl in sediments, macroalgae (Fucus vesiculosus and Fucus ceranoides) and deposit-feeding invertebrates (Hediste diversicolor, Arenicola marina and Scrobicularia plana) from two estuaries of south west England (Plym and Fal) draining mineralised catchments. In the Plym, and for a given sample type, concentrations of Tl were rather invariant between sample locations and averaged about 500 ?g kg(-1) for sediment, 30 ?g kg(-1) for macroalgae and 10 ?g kg(-1) for the invertebrates. In the Fal, respective concentrations were of a similar order of magnitude but exhibited greater variation between sample locations. Normalisation of Tl concentrations to K, the biogeochemical analogue of Tl(+), revealed bioenrichment of about 20 for all organisms in the Plym and bioenrichment ranging from about 3 (H. diversicolor) to 170 (F. ceranoides) in the Fal. Despite the low bioaccumulation of Tl relative to other metals measured concurrently, it is recommended that Tl be more closely monitored and better studied in the estuarine environment. PMID:23465575

Turner, Andrew; Turner, Deborah; Braungardt, Charlotte

2013-04-15

 
 
 
 
21

Small-scale variability of zooplankton pyruvate kinase activity in the Gironde Estuary plume (Atlantic French Coast): A case study under unusually low freshwater discharge  

Science.gov (United States)

Pyruvate kinase (PK) activity measurements are used to assess the role of carbohydrates in global feeding of mesozooplankton communities inhabiting an estuary plume. As a consequence of a remarkably low freshwater discharge rate, the sea surface layers of the area under estuarine influence showed a very moderate salinity fall and a nearly total depletion in nitrates, whereas higher levels of these nutrients were found in deeper, more saline, layers. Small-scale PK activity variations in mesozooplankton appear to be closely correlated to nitrate integration values within the water column. The results were analysed in comparison with literature reports. The study produced a coherent overall interpretation, which strongly supports the reliability of this new biochemical tool in detecting assimilation of trace carbohydrates in the diet of mesozooplankton.

Bergeron, Jean-Pierre

2006-09-01

22

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

Directory of Open Access Journals (Sweden)

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

H. Etcheber

2010-12-01

23

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

Science.gov (United States)

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

Etcheber, H.; Schmidt, S.; Sottolichio, A.; Maneux, E.; Chabaux, G.; Escalier, J.-M.; Wennekes, H.; Derriennic, H.; Schmeltz, M.; Quéméner, L.; Repecaud, M.; Woerther, P.; Castaing, P.

2010-12-01

24

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

Directory of Open Access Journals (Sweden)

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

H. Etcheber

2011-03-01

25

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

Science.gov (United States)

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

Etcheber, H.; Schmidt, S.; Sottolichio, A.; Maneux, E.; Chabaux, G.; Escalier, J.-M.; Wennekes, H.; Derriennic, H.; Schmeltz, M.; Quéméner, L.; Repecaud, M.; Woerther, P.; Castaing, P.

2011-03-01

26

Traceurs organiques dans les dépôts de la vasière Ouest-Gironde (Golfe de Gascogne)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Mud fields located In the inner part of shelves in front of large estuaries are preferential environments for the investigation of the mechanisms and evolution in time of the supply of such sedimentary bodies. The study of different constituents of the particulate organic matter trapped in the sediments of the West Gironde mud patch contributes to the knowledge of the input origins. This study was carried out with different techniques, including pyrolysis-gas chromatography-mass spectrometry ...

Gadel, F.; Jouanneau, Jm; Weber, O.; Serve, L.; Comellas, L.

1997-01-01

27

Water and sediment quality of Ashtamudi estuary, a Ramsar site, southwest coast of India--a statistical appraisal.  

Science.gov (United States)

Ashtamudi estuary, situated on the southwest coast of India, is enormously affected by anthropogenic interventions. Physicochemical quality of water and sedimentological features of the estuary are evaluated during monsoon and nonmonsoon seasons to elucidate its quality variations and to link the same with existing environmental scenario. The whole data has been factorized using principal component analysis for extracting the total variability and linear relationships existing among a set of different physicochemical parameters of the backwater system. In PCA, high loadings were obtained for conductivity, salinity, fluoride, calcium, magnesium, sulfate, boron, and pH. The results were revealed that all the physicochemical processes depend upon seasonal fluctuation of freshwater input and seawater intrusion. Wide spatial concentration fluctuations of organic carbon and iron in bottom sediment have been noticed and both constituents reveal good correlation with sediment texture. The results showed high deterioration of the physicochemical quality of water during nonmonsoon season with respect to monsoon season. PMID:19444633

Babu, K Narendra; Omana, P K; Mohan, Mahesh

2010-06-01

28

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  

International Nuclear Information System (INIS)

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 7Be/210Pbx ARs are observed there due to resuspension of 7Be-deficient sediments. Away from the TMZ, from the middle to lower estuary, SPM 7Be/210Pbx ARs increase, indicating that the particles have been recently tagged with 7Be. We explain this trend as being caused by marine input of dissolved radionuclides, as traced by SPM 234Th/210Pbxs ARs, followed by scavenging in the estuary. This result indicates that particle transport models based on 7Be and trace-metal budgets must consider oceanic dissolved inputs as an additional source of 7Be and, possibly, of contaminants to estuaries.

29

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 (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

30

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

31

Relationship between ore deposits in river catchments and geochemistry of suspended particulate matter from six rivers in southwest France.  

Science.gov (United States)

Here we present original data on the geochemical composition of fluvial particulate matter transported by the rivers of the Adour/Garonne basin, which drains one-fifth of the French land surface. Suspended particulate matter from the six main rivers in the basin, sampled at 'normal' flow and during a flood, is compared in terms of: grain size; particulate organic carbon; Fe; Mn; and trace element concentrations (e.g. Zn, Cd, Pb, Cu, Mo, Sn, Ni, Co, Cr, V, As, Hg, U, Th, W, Au, Ag, Ta). Three of the six studied rivers (Garonne, Dordogne and Isle Rivers) are the main tributaries of the Gironde estuary (southwest France), known for Cd pollution. The Adour and Gaves Rivers enter the Adour Estuary and the Charente River reaches the ocean by the Charente Estuary. Our data show, that Cd (and Zn) are not the only trace elements of eco-toxicological relevance transported into the Gulf of Biscay by these six rivers. Potentially toxic elements (e.g. As, Sn, U, Cu, Ag) show elevated concentrations in river particulates entering the estuaries, compared to world average concentrations [Martin and Whitfield, 1983, The significance of the river input of chemical elements to the oceans. In: C.S. Wong, E. Boyle, K.W. Bruland, J.D. Burton, E.D. Goldberg (editors), Trace Metals in Sea Water, Plenum, New York: pp. 265-296]. Comparing SPM sampled during 'normal' discharge and flood, the basin shows a distinct trace element composition of SPM mostly related to ore deposits in the upper basins (Massif Central and Pyreneans). This geochemical signal is partly masked during floods due to changes in grain size, but also due to increased erosion of the lower parts of the basins. This study proves pumping/centrifugation to be the most appropriate sampling/separation technique (recovery, representativity, contamination) by comparing different methods of SPM recovery. PMID:12449332

Schäfer, Jörg; Blanc, Gérard

2002-10-21

32

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

International Nuclear Information System (INIS)

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. - Highlights: ? Tinto–Odiel rivers estuary affected by AMD and leaching from phosphogypsum. ? Study about distribution processes that govern Ra, U and Th-isotopes in sediments. ? The acidity gradients of mixed waters (pH) regulate the U and Th distribution. ? Significant pollution by U has been found for pH = 3.5–4.5.

33

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

34

Estuary Live!  

Science.gov (United States)

Classrooms and individuals can log on to participate in a real-time field trip to a National Estuary Research Reserve. Ask questions, view live video and still images, and learn about estuaries from experts. Topics range from geology to water quality, estuary plants and animals, and cultural heritage. Includes: references and lesson plans, classroom activities and teachers' guides. Archives of previous years are available, featuring sessions from East, West and Gulf Coast estuaries.

35

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

36

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

37

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

38

Estuary Live!!!  

Science.gov (United States)

Intended for elementary, middle, and high school students, this electronic estuary excursion, Estuary Live!!!, will take place May 8-12, 2000. Free to participants (but please sign up in advance), the field trip will explore the Rachel Carson Site of the North Carolina National Estuarine Research Reserve, covering four islands and salt marshes off the North Carolina coast. The site features useful educational materials, including a photo-illustrated field guide (of the "ecology, habitats and specific plants and animals found in North Carolina's estuaries"); lesson plans (covering highschool biology, estuary habitats, species interactions, and adaptations and communities); and a series of related links. The interactive field trip will require a java-enabled browser, RealVideo (to see a moving image and hear sound), and/or Chatvideo, to see a moving image, ask questions of the naturalist leading the trip, and receive responses via a chat window. Note that ChatVideo requires Netscape 4.0 or better and will not work with AOL or Internet Explorer, and pages "look best" on a screen with resolution of 800x600. The Estuary Live!!! Website is provided by the North Carolina National Estuarine Research Reserve Program, and The Center for Science, Mathematics and Technology Education at East Carolina University.

39

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

40

Gammaridean amphipods in the Columbia River Estuary  

Energy Technology Data Exchange (ETDEWEB)

The distribution, abundance, and habitat preference of the amphipods Corophium salmonis, C. spinicorne, and Anisogammarus confervicolus were studied in the Columbia River estuary as part of baseline research during 1974 to 1976. A figure is presented showing densities of two species at selected stations in the Columbia River. Studies were also conducted on changes in faunal composition and substrate texture existing across an intertidal mudflat on the southwest shore of Youngs Bay. (HLW)

Holton, R.L.; Higley, D.L.

1976-01-01

 
 
 
 
41

Évaluation et réduction des impacts écologiques liés à la consommation des ménages : conception méthodologique et application au Pays Cœur Entre-deux-Mers, Gironde, France  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Le travail de recherche conduit dans le cadre de cette thèse a pour objectif de renforcer les fondements conceptuels et méthodologiques d'une promotion de la consommation écoresponsable. Il s'appuie sur une confrontation au territoire périurbain du Pays Cœur Entre-deux-Mers (Gironde, France). Il s'agit d'une démarche exploratoire qui repose sur l'écologie familiale, approche pluridisciplinaire étudiant les interactions entre les ménages et les écosystèmes, à travers les activités...

Sennes, V.

2008-01-01

42

Welcome to Estuaries  

Science.gov (United States)

This resource features three sections devoted to learning about estuaries: an online tutorial, an educational roadmap to resources, and formal lesson plans. The tutorial shows how estuaries are classified by their geology and water circulation patterns, the various ecosystem services estuaries perform, how organisms have adapted to the unique environmental conditions found in estuaries, the many disturbances that estuaries face from nature and human activities, and finally, the essential work that the National Estuarine Research Reserve System and its many partners conduct to monitor, preserve, and restore estuarine ecosystems throughout the United States. The roadmap to resources provides a set of links to specific data related to the information presented in the tutorial. Lesson plans on estuaries are also provided.

43

Nutrients in an Estuary  

Science.gov (United States)

In this activity, learners model estuaries, artificially enriching both fresh and salt water samples with different amounts of nutrients and observing the growth of algae over several weeks. Learners relate their results to the phenomenon of algae blooms in estuaries. Learners then analyze data for different sites at the Guana Tolomato Matanzas National Estuarine Research Reserve (GTMNERR) in Florida to discover the relationships between nitrogen, chlorophyll, and dissolved oxygen. Finally, learners study how nutrients cycle through an estuary and suggest recommendations for reducing nutrient inputs to estuary waters.

Terc; National Oceanic and Atmospheric Administration (NOAA)

2012-06-26

44

Estuary Classification Revisited  

CERN Document Server

The governing equations of a tidally averaged, width averaged, rectangular estuary has been investigated. It's theoretically shown that the dynamics of an estuary is entirely controlled by three parameters: (i) the Estuarine Froude number, (ii) the Tidal Froude number and (iii) the Estuarine Aspect ratio. The momentum, salinity and integral salt balance equations can be completely expressed in terms of these control variables. The estuary classification problem has also been reinvestigated. It's found that these three control variables can completely specify the estuary type. Comparison with real estuary data shows very good match. Additionally, we show that the well accepted leading order estuarine integral salt balance equation is inconsitent with the leading order salinity equation in an order of magnitude sense.

Guha, Anirban

2012-01-01

45

Biogeochemistry of Estuaries  

Science.gov (United States)

Whether you are interested in material flux from the continents to the oceans or whether the oysters set down in front of you at a waterfront restaurant may have come from polluted waters, we know estuaries are important places. However, anyone attempting to summarize and synthesize the long and rich literature of estuarine research is presented with a daunting task. This is because beyond the concept of an estuary being the transition zone where ``fresh water meets seawater,'' the exact definition of an estuary is not uniformly agreed upon by scientists in this field. Also, estuaries-regardless of how they are defined-tend to be highly heterogeneous, in both space and time. Against this backdrop, Thomas Bianchi's Biogeochemistry of Estuaries successfully tackles its subject matter and is an exciting addition to the field of estuarine research.

Burdige, David J.

2007-12-01

46

Freshwater runoff and salinity distribution in the Loxahatchee River estuary, southeastern Florida, 1980-82  

Science.gov (United States)

Freshwater mixed with seawater over a distance of 5 to 10 river miles in the Loxahatchee River estuary during a recent study. Large freshwater inflows vertically stratified the estuary and shifted the mixing zone seaward. In the northwest fork of the estuary, the saltwater-freshwater interface moved daily about 0.5 to 1.5 river miles as a result of tides, and annually about 3 to 5 miles as a result of seasonal changes in freshwater inflow. In the southwest fork, saltwater movement upstream was blocked by a gate and dam structure in Canal-18, 4.7 miles upstream from the Atlantic Ocean. Although Canal-18 discharged about one-third of the total freshwater tributary inflow to the estuary, the effects of canal discharge on salinity were limited to relatively brief periods. Much of the time, no freshwater was discharged. (USGS)

Russell, G. M.; McPherson, B. F.

1984-01-01

47

Go Southwest, Old Man  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

48

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

49

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.

50

DELAWARE ESTUARY A MANAGEMENT PLAN FOR THE DELAWARE ESTUARY  

Science.gov (United States)

Wise conservation and management of the Delaware Estuary is arguably the most important cooperative environmental initiative ever jointly undertaken by the States of New Jersey, Pennsylvania, and Delaware. While much has been accomplished over the past few decades to improve wate...

51

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

52

Southwest Airlines: lessons in loyalty.  

Science.gov (United States)

Southwest Airlines continues to garner accolades in the areas of customer service, workforce management, and profitability. Since both the health care and airlines industries deal with a service rather than a product, the customer experience depends on the people who deliver that experience. Employees' commitment or "loyalty" to their customers, their employer, and their work translates into millions of dollars of revenue. What employee wants to work for "the worst employer in town?" Nine loyalty lessons from Southwest can be carried over to the health care setting for the benefit of employees and patients. PMID:19330974

D'Aurizio, Patricia

2008-01-01

53

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 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

54

Simulated Sampling of Estuary Plankton  

Science.gov (United States)

To find out about the microscopic life in the valuable estuary environment, it is usually necessary to be near the water. This dry lab offers an alternative, using authentic data and a simulation of plankton sampling. From the types of organisms found in the sample, middle school students can infer relationships in the biological and physical…

Fortner, Rosanne W.; Jenkins, Deborah Bainer

2009-01-01

55

The Need for Definitions in Understanding Estuaries  

Science.gov (United States)

This paper considers what the definition/classification of estuaries has taught us and why there is a need for classification systems. It further considers why we need to define an estuary and its constituent parts, including the fundamental difficulty and dilemma of trying to define parts of a continuum, as a means to both understanding and managing that estuary. The review considers where an estuary starts and ends and the relative merits of defining estuaries in terms of their biology, physics, chemistry, geographic nature and socio-economic units. It briefly discusses the need for legal and planning definitions and the linkages between science and management. Following this, we present a generic framework for the definition, classification, monitoring, assessment, reporting and management of estuaries. In particular, it is argued that scientists should engage in the debate on the definition of estuaries for legal and socio-economic purposes. It is concluded here that as existing definitions will never be suitable for all needs, a different approach is required. The proposed ' Expert Judgement Checklist Approach ' could provide guidance for those needing to define/delimit an estuary while still acknowledging the inherent variability of such systems. The proposed system mostly relates to the European, temperate estuary, but there are lessons here for estuaries worldwide.

Elliott, M.; McLusky, D. S.

2002-12-01

56

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

Science.gov (United States)

...Estuary Habitat Restoration Strategy comments from [insert name...information. A copy of the strategy and other documents related...has four purposes: (1) promotion of estuary habitat restoration...development of a national strategy for creating and...

2010-06-21

57

Environmental data management in the Sado Estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

58

Morphodynamic equilibrium of alluvial estuaries  

Science.gov (United States)

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

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

2014-05-01

59

Sea level variability in South African estuaries  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Sea level variability in the coastal ocean affects water levels in adjacent estuaries over a wide range of periods and to varying distances landward. An assessment is given here of the responses of a number of South African estuaries, focusing on tidal and subtidal periods where the dominant effects [...] are found and the necessary data are available. Shorter period inputs tend to be limited to mouth regions and require more detailed, higher frequency data. Subtidal fluctuations, in particular those caused by coastal trapped waves, play an important part in the dynamics of estuaries in the Western Cape and Eastern Cape. In many cases their influence dominates tidal oscillations farther upstream, and it is apparent that such fluctuations must be considered in any assessment of estuarine characteristics, and indeed their upstream extent. Nonetheless, it should be emphasised that each estuary has unique properties, and must be assessed individually. Sea level variability changes dramatically north of the Kei Estuary, and particularly off the coast of KwaZulu-Natal. Unfortunately, few measurements were available from these estuaries, but the mouth conditions of the estuaries and the build-up of river flow appear to be important factors in resulting estuary water levels. These results show that using only tidal variations in the sea can result in very misleading conclusions about concurrent water levels in estuaries.

Eckart H., Schumann.

60

Southwest Educational Development Laboratory: SCIMAST  

Science.gov (United States)

The Southwest Educational Development Laboratory (SEDL) serves the Southwest including Arkansas, Louisiana, New Mexico, Oklahoma, and Texas. Although most of SEDL's SCIMAST Access Centers are specifically targeted for these specific states, the SCIMAST website offers an array of broadly applicable resources on science and mathematics education. One feature of the site is the Classroom Compass, "a thematic publication designed to link issues in mathematics and science education to instructional ideas and resources." Each issue explores a theme in depth, illustrating instruction around that theme and providing informational resources and materials for further investigation. Topics include constructivism, cooperative learning, Rhythm of Mathematics, science as inquiry, and using community resources. Visitors can also search the extensive resource database for mathematics and science instructional materials and resources.

 
 
 
 
61

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

62

NEW HAMPSHIRE ESTUARIES PROJECT MANAGEMENT PLAN, 2000  

Science.gov (United States)

The Comprehensive Conservation and Management Plan of the New Hampshire Estuaries Project presents a broad framework and specific list of actions to protect and enhance the environmental quality of the estuaries of the State of New Hampshire. It is intended to be a guide for all ...

63

NEW HAMPSHIRE ESTUARIES PROJECT MANAGEMENT PLAN  

Science.gov (United States)

This Comprehensive Conservation and Management Plan of the New Hampshire Estuaries Project presents a broad framework and specific list of actions to protect and enhance the environmental quality of the estuaries of the State of New Hampshire. It is intended to be a guide for all...

64

Southwest Florida Water Management District  

Science.gov (United States)

The mission of the Southwest Florida Water Management District is to manage the water and water-related resources within its boundaries. Central to the mission is maintaining the balance between the water needs of current and future users while protecting and maintaining the natural systems that provide the District with its existing and future water supply. The website includes an Information and Education page, which offers activities, newsletters, virtual field trips, and other resources for K-12 students and teachers. Also provided on the site are various datasets, brochures, publications, reports, textual references and links.

65

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

66

Numerical modelling of morphodynamics—Vilaine Estuary  

Science.gov (United States)

The main objective of this paper is to develop a method to simulate long-term morphodynamics of estuaries dominated by fine sediments, which are subject to both tidal flow and meteorologically induced variations in freshwater run-off and wave conditions. The method is tested on the Vilaine Estuary located in South Brittany, France. The estuary is subject to a meso-macrotidal regime. The semi-diurnal tidal range varies from around 2.5 to 5 m at neap and spring, respectively. The freshwater input is controlled by a dam located approximately 8 km from the mouth of the estuary. Sediments are characterised as mostly fines, but more sandy areas are also found. The morphology of the estuary is highly influenced by the dam. It is very dynamic and changes in a complicated manner with the run-off from the dam, the tide and the wave forcing at the mouth of the estuary. Extensive hydrodynamic and sediment field data have been collected in the past and provide a solid scientific basis for studying the estuary. Based on a conceptual understanding of the morphodynamics, a numerical morphological model with coupled hydrodynamic, surface wave and sediment transport models is formulated. The numerical models are calibrated to reproduce sediment concentrations, tidal flat altimetry and overall sediment fluxes. Scaling factors are applied to a reference year to form quasi-realistic hydrodynamic forcing and river run-off, which allow for the simulations to be extended to other years. The simulation results are compared with observed bathymetric changes in the estuary during the period 1998-2005. The models and scaling factors are applied to predict the morphological development over a time scale of up to 10 years. The influence of the initial conditions and the sequence of external hydrodynamic forcing, with respect to the morphodynamic response of the estuary, are discussed.

Vested, Hans Jacob; Tessier, Caroline; Christensen, Bo Brahtz; Goubert, Evelyne

2013-04-01

67

US Environmental Protection Agency: National Estuary Program  

Science.gov (United States)

Established in 1987 by amendments to the Clean Water Act and administered by the Environmental Protection Agency's Office of Wetlands, Oceans, and Watersheds (OWOW), the National Estuary Program (NEP) identifies, restores and protects estuaries along the coasts of the United States. Unlike the traditional regulatory approaches to environmental protection, the NEP targets a wide range of issues and engages local communities in the process. At the site users can find descriptions of the NEP, specific NEP projects, estuaries involved in the NEP (including location, size, presence of threatened and endangered species, major habitat types, etc.), a current awareness section, links to related sites, and the full text of NEP's newsletter, Coastlines.

68

Suspended sediment delivery dynamics during storm-events to the Avon estuary, southwest UK  

Science.gov (United States)

Knowledge of fine sediment delivery (both timing and loading) is fundamental to the assessment of non-point source pollution in estuarine environments. Turbidity and flow were monitored continuously on the main-stream channel of the River Avon (watershed area 340 km2), in southern Devon, UK, upstream of the freshwater/saline interface. The relationship between suspended sediment concentration and turbidity was derived by analysis of a wide range of samples for suspended sediment by filtration. A log-linear model showed a high positive correlation between suspended sediment concentration (SSC) and turbidity (R2 = 0.97). Twenty-three floods were studied, and hydrological and sedimentary response was highly variable. Maximum suspended sediment concentrations (SSC) was between 4 mg L-1 and 872 mg L-1 and sediment load varied from 3 to 209 t per hydrological event. Most sediment load was concentrated in December when competent floods occur frequently. Hydrological response was also variable in terms of lag, hydrograph form and maximum discharge. Analysis of the key storm parameters showed that the hydrological response of the catchment is affected by the total amount of precipitation and antecedent rain history.

Zoozi, S.; Blake, W.; Masselink, G.; Telfer, M.

2011-12-01

69

Origin and biochemical cycling of particulate nitrogen in the Mandovi estuary  

Science.gov (United States)

Mandovi estuary is a tropical estuary strongly influenced by the southwest monsoon. In order to understand, sources and fate of particulate organic nitrogen, suspended particulate matter (SPM) collected from various locations, was analyzed for particulate organic carbon (POC) and particulate organic nitrogen (PON), ? 13C POC, total hydrolysable amino acid enantiomers ( L- and D- amino acids) concentration and composition. ? 13C POC values were depleted (-32 to -25‰) during the monsoon and enriched (-29.6 to -21‰) in the pre-monsoon season implying that OM was derived from terrestrial and marine sources during the former and latter season, respectively. The biological indicators such as C/N ratio, D-amino acids, THAA yields and degradation indices (DI) indicate that the particulate organic matter (POM) was relatively more degraded during the monsoon season. Conversely, during the pre-monsoon, the biological indicators indicated the presence of relatively fresh and labile POM derived from autochthonous sources. Amino acids such as alanine, aspartic acid, leucine, serine, arginine, and threonine in monsoon and glutamic acid, glycine, valine, lysine, and isoleucine in pre-monsoon were relatively abundant. Presence of bacterial biomarker, D-amino acids in the SPM of the estuary during both the seasons signifies important contribution of bacteria to the estuarine detrital ON pool. Based on D-amino acid yields, bacterial OM accounted for 16-34% (23.0 ± 6.7%) of POC and 29-75% (47.9 ± 18.7%) of PON in monsoon, and 30-78% (50.0 ± 15%) of POC and 34-79% (51.2 ± 13.3%) of the PON in pre-monsoon in the estuary. Substantial contribution of bacterial-N to PON indicates nitrogen (N) enrichment on terrestrial POM during the monsoon season. Transport of terrestrial POM enriched with bacterial OM to the coastal waters is expected to influence coastal productivity and ecosystem functioning during the monsoon season.

Fernandes, Loreta

2011-09-01

70

Assessing the susceptibility of two UK estuaries to nutrient enrichment  

Science.gov (United States)

The susceptibility of two UK estuaries, the Severn and Solva Estuaries to the risks and impacts of nutrient enrichment was investigated in this study by examining nutrients, dissolved oxygen (DO) and turbidity concentrations in the estuaries and applying a risk assessment model based on the UK's Comprehensive Studies Task Team (CSTT) modelling approach. Both estuaries were found to be nutrient enriched. However, there was no evidence of oxygen depletion in the Severn and algal blooms were not observed due to high turbidity, strong tidal currents and tidally induced vertical mixing conditions in the estuary. Although algal blooms were observed in the Solva Estuary, the estuary was well-oxygenated due to the relatively high water exchange rate and consistent rapid flushing in the estuary. The conditions in the Solva Estuary were predicted to be favourable for phytoplankton productivity and the wider potential implications for future water quality protection strategies in the Solva were discussed.

Kadiri, Margaret; Bockelmann-Evans, Bettina; Rauen, William B.

2014-10-01

71

Redissolution of 226Ra from sediments in a Spanish estuary affected by the phosphate industry: model comparisons in the framework of the IAEA EMRAS project  

International Nuclear Information System (INIS)

The Huelva estuary (south-west Spain), a fully mixed tidal estuary, consists of two rivers: Odiel and Tinto. A phosphate fertilizer processing complex has been releasing NORM radionuclides directly into the Odiel river over several decades. As a consequence, high levels of 226Ra, U and Th isotopes and other radionuclides have been measured in water, suspended matter and bed sediments of the estuary. Nevertheless, direct releases stopped in 1998 due to new regulations from the EU and, since then, a self cleaning process has been observed. It consists of a continuous decrease in activity concentrations in water and bed sediments. The study by means of numerical models of the 226Ra self cleaning process observed in the estuary has been proposed as an EMRAS project task. A model has been proposed by each institute participating in the exercise. Models have different configurations and temporal and spatial resolutions. Some processes, for instance tides or uptake/release of radionuclides between water and sediments, are described in different ways. However, all are started from the same initial conditions, provided by the University of Seville model. The endpoint of the simulations is to give the temporal evolution of the total 226Ra inventory in the bed sediments of the estuary and to estimate from it the sediment halving time. A brief description of the main features of each model is provided and the results are compared and analysed. (author)

72

PECONIC ESTUARY PROGRAM TIDAL CREEK STUDY  

Science.gov (United States)

EEA evaluated ten tidal creeks throughout the Peconic Estuary representing a wide range of watershed variables. Primary focus was directed towards the collection and analysis of the macrobenthic invertebrate communities of these ten tidal creeks. Analysis of the macrobenthic comm...

73

Mixing in the Amazon estuary  

Science.gov (United States)

The research area of this work is located at the estuary of the Amazon River (Brazil), near the river mouth. The results of air movement analysis on the surface atmospheric circulation over the Mouth of the Amazonas River, salinity and temperature measures as well as measurements of currents, carried out along a longitudinal section in the navigation canal region of the Northern Bar of the Amazon River (Barra Norte do Rio Amazonas) in June 2006, during the river flood season in the quadrature tide. The dynamics effects affect hydrodynamic,meteorological and hydrographical parameters at the river mouth. The conclusion drawn include that: a) the saline wedge-type stratification can be detected approximately 100km away from the mouth of the Amazon River during the end of the rainy season in the quadrature tide; b) probably, at the Amazon estuary the quadrature entrainment processes are dominant and they are the ones responsible for increased salinity detected in the surface layer, whereas turbulence scattering mixing is not so important. c) The large flow of fresh water from the Amazon River at the end of the rainy season implies the displacement of the saline front position over the internal Amazon continental platform, and d) The tidal wave shows a positive asymmetry in the canal, with floods lasting less than in the ebb tide. This asymmetry decreases towards the ocean, eventually becoming reversed in the presence of a saline wedge. The speeds, however, have a negative asymmetry, with more intense ebb tides, due to the river flow and is more evident by the existence of quadrature tides.

Bezerra, M. O.

2010-05-01

74

Heat and Drought Kills Trees in Southwest  

Science.gov (United States)

... br/>Press Release 05-182Heat and Drought Kills Trees in Southwest Study sheds light on how quickly ... of Arizona. "Beetles don't get trees unless the trees are really water-stressed" and unable to make ...

75

Trophic characteristics of a mangrove fish community in Southwest Thailand: Important mangrove contribution and intraspecies feeding variability  

Science.gov (United States)

Mangrove production has been found to make a major contribution to the nutrition of a fish community in the Sikao Creek mangrove estuary, Southwest Thailand. Gut content analysis and carbon and nitrogen stable isotope analysis were used to assess fish feeding behavior and trophic reliance on different primary producers (mangrove leaves, phytoplankton, microphytobenthos) focusing on 19 dominant fish species, and 4 potential fish food items. Cluster analysis identified 5 trophic groups and the IsoSource model indicated the importance of primary food sources in trophically supporting different fish species. Most analyzed fish species had carbon isotopic signatures that were more depleted than those reported in previous studies, and the IsoSource model indicated that mangrove leaves were an important primary food source. This may be a specific characteristic of our study site, which is not well connected to other productive coastal habitats that provide alternative primary food sources. Thus we suggest that food chains in trophically isolated mangrove estuaries of southwest Thailand are more dependent on mangrove tree production. We also assessed the relationship of individuality in fish feeding habits and variability of ?13C values and showed that several mangrove fish species have significant intraspecies variability in feeding habits, possibly due to high intraspecific competition.

Zagars, Matiss; Ikejima, Kou; Kasai, Akihide; Arai, Nobuaki; Tongnunui, Prasert

2013-03-01

76

Rapid barium removal in the Delaware estuary  

Science.gov (United States)

Six profiles of dissolved barium covering the entire salinity range of the Delaware River and Bay estuary from March through September 1996 were collected and analyzed. The profiles are similar to one another in both shape and magnitude except for one attribute. A sudden (?24 days), nearly complete (>90%) removal of dissolved Ba in midestuary occurs in mid-May followed by an 80% recovery in early June. This removal appears to be temporally and spatially coupled to the end of the spring bloom. Based on such episodic behavior, and on recent work with flocculation of diatom exudates, we conclude that the Ba depletion is caused by barite precipitation in the estuary during the late stages of the bloom. This would imply that lower estuary and inner coastal margin sediments associated with eutrophic estuaries receive a seasonal pulse of barite. The suddenness of this event also implies that sedimentary barite is strongly influenced by high productivity events. Comparison of the riverine Ba concentration with the effective riverine end member after desorptive barium release yields an estimated 30-40 nM Ba available from the suspended sediments as they enter the estuary. This estimate is supported by excess barium in unfiltered samples over filtered samples taken from the river and also by calculations done elsewhere.

Stecher, Hilmar A.; Kogut, Megan B.

1999-04-01

77

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

78

PCBs in phytoplankton in the Odra Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available Eleven PCB congeners were determined in phytoplankton samples collected from the Odra Estuary at 9 stations in 2001-2002. The PCB concentrations were related to the temperature, turbidity, salinity, oxygen and redox potential of the water as well as to the pigment content in the samples. The results indicate that phytoplankton and the detritus derived from it play a crucial role in the distribution of PCBs, their transfer from the water column to sediments and from the Estuary to the sea. The species composition of the phytoplankton occurring in this area could also be very important as regards the sorption of PCBs.

Joanna Konat-Stepowicz

2003-09-01

79

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)

80

The spatial and temporal characteristics of harmful algal blooms in the southwest Bohai sea  

Science.gov (United States)

Harmful algal blooms (HABs) are harmful to coastal ecosystems, fisheries, the aquaculture industry, and even human health, thus they have received great attention worldwide. In this study, geostatistical tools in Geographic information system (GIS) were used to analyze HAB data collected over the last 11 years in the southwest Bohai Sea with the goal of detecting spatial and temporal characteristics of HAB events in this area. The seasonality, trend of HAB occurrences and the spatial pattern of HAB events were examined by time-series analysis and nearest neighbor analysis, respectively. The frequency of HAB occurrences was mapped using kernel density estimation, and the harm caused by HAB events was assessed and then categorized using a characteristic-based empirical model. The occurrences of HABs not only exhibited significant seasonality and a "single peak" trend in time but also were clustered in space. HABs had both a high frequency of occurrence and a high harm in the north Bohai Bay and the Yellow River estuary. In addition, HABs posed a high harm in the nearshore area near the city of Huanghua in Bohai Bay and the offshore area in the middle Bohai Bay; thus, HAB monitoring and/or management should be concentrated in these locales. Compared to previous descriptions, this research utilized a visualizable approach to more fully identify the scope, distribution, and characteristics of HAB occurrences in the southwest Bohai Sea, thus providing useful information to support the implementation of a monitoring and management program for HABs.

Wu, Zaixing; Yu, Zhiming; Song, Xiuxian; Yuan, Yongquan; Cao, Xihua; Liang, Yubo

2013-05-01

 
 
 
 
81

Monsoonal impact on planktonic standing stock and abundance in a tropical estuary (Cochin backwaters - India)  

Science.gov (United States)

Environmental studies in the Cochin backwaters (CBW), a tropical estuary along the southwest coast of India showed that seasonal fluctuations in salinity created by the monsoonal rainfall and associated run off is a major factor controlling the distribution and abundance of micro- and mesozooplankton. During premonsoon season, the CBW was characterized by warm waters (av. 32.6 ± 0.6 °C) with relatively high salinity (>23; except in the lower estuary). On the other hand, fresh water was found to dominate the entire area during monsoon and postmonsoon seasons. The enormous input of nutrients (nitrate, phosphate and silicate) into the estuary from various sources (industries, agriculture and domestic) was responsible for the high phytoplankton biomass (av. 10.4 ± 10.1 mg m -3) irrespective of seasons. The phytoplankton community was, in general, dominated by diatoms (av. 88 ± 12%), and proliferation of multiple species of diatoms ( Skeletonema costatum, Thalassiosira subtilis and Nitzschia closterium - 1600 × 10 3 cells L -1) at different locations were observed especially during high saline condition. In case of zooplankton (micro- and meso), high standing stocks (micro av. 81.4 ± 48.1 mg C m -3; meso av. 88 ± 125 mg C m -3, respectively) were recorded during the premonsoon season. Copepods (e.g. Calanoids) formed the abundant group (av. 75 ± 18%) in the mesozooplankton community irrespective of seasons. The ratio of carbon content between phytoplankton and zooplankton ( P: Z) was quite high (>100) during monsoon and postmonsoon seasons, but became low during premonsoon season (<5). Hence, it is suggested that during the periods of fresh water dominance, the trophic food web of Cochin estuarine system is characterized by substantial amount of unconsumed carbon at primary level owing to the reduction in phytoplankton grazers (zooplankton).

Madhu, N. V.; Jyothibabu, R.; Balachandran, K. K.; Honey, U. K.; Martin, G. D.; Vijay, J. G.; Shiyas, C. A.; Gupta, G. V. M.; Achuthankutty, C. T.

2007-06-01

82

The relationship between sediment and plutonium budgets in a small macrotidal estuary: Esk Estuary, Cumbria, UK  

International Nuclear Information System (INIS)

During a spring tide, measurements were made of sediment and 239,240Pu discharges through a cross-section of the Esk estuary. These indicated that over the full tidal cycle, the inner estuary had a net gain of ca. 18 t of sediment and ca. 85 MBq of particulate phase 239,240Pu, and a probable net loss of ca. 1 to 2 MBq of solution phase 239,240Pu. Each of these was the net result of large gross discharges of sediment and plutonium into and out of the estuary for which the sea was the main source, with eroded estuarine sediment providing an additional minor source of sediment, of particulate phase plutonium and, via desorption, of solution phase plutonium. A net input with each tide, of sediment and its associated radionuclides, is considered to be typical for the Esk estuary under the normal conditions of low river flows. (author)

83

Hydrologic Literacy in the Southwest  

Science.gov (United States)

Improving hydrologic literacy at all levels has been the keystone to the education mission at NSF's SAHRA Science and Technology Center since its inception in 2000. Water issues and water education are particularly relevant in the semi-arid southwest, which has experienced a series of droughts and tremendous growth throughout this period. One of our strategies has been to focus our efforts on the high school and undergraduate level, for which there are far fewer water education materials available. Early on, we worked with local water educators and employed an Understanding by Design methodology to develop a series of Enduring Understandings in the critical areas of water quality, aquatic life, watersheds and urban hydrology. These basic concepts have helped guide our development of content and training opportunities. A prime example of this process is our Watershed Visualization project, which includes a series of animated videos focused on understanding the geographic and hydrologic setting of the Verde Watershed in central Arizona. This series also addresses the interaction of climate and groundwater recharge in this rapidly changing area. This past year, we developed a new program called Arizona Rivers, which emphasizes local and student- based monitoring and research of the interactions between riparian hydrology and ecology. One key feature of this program is an extended summer field trip/research experience for high school students called the Riparian Research Experience. A goal of this program is to raise the level of critical analysis and environmental stewardship among high school students and their teachers. A more comprehensive effort of raising the hydrologic literacy of non-science university freshman has been taking place at the University of Arizona for the past five years through the general education course titled Arizona Water Issues or HWR203. This course focuses equally on fundamental hydrologic understandings, beginning with the water cycle as well as the host of political and social issues that arise as this scarce resource is stretched among many stakeholders claiming ever larger water needs. This course covers a range of topics from water law to water resource management using decision support modeling tools. All of these projects can be found on our web site referenced below.

Washburne, J.; Madden, J.

2008-12-01

84

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

85

Ranking sediment samples from three Spanish estuaries in relation to its toxicity for two benthic species: the microalga Cylindrotheca closterium and the copepod Tisbe battagliai.  

Science.gov (United States)

The present study assesses the sediment toxicity levels of three Spanish estuaries, as well as the suitability of two microorganisms, the benthic microalga Cylindrotheca closterium and the harpacticoid copepod Tisbe battagliai, as test organisms in whole-sediment toxicity assays. The sensitivity of both species to potentially polluted sediments was compared. Three sites at the southwest of the Iberian Peninsula were chosen: the Ría of Huelva, the Guadalquivir Estuary, and the Bay of Algeciras. Inhibition data were based on growth for C. closterium and fecundity for T. battagliai. No toxicity was recorded for the microalga in the Guadalquivir Estuary and the Bay of Algeciras. However, for T. battagliai, inhibition of fecundity was approximately 50% in those zones, indicating higher sensitivity. Samples from stations in the Ría of Huelva were the most toxic of all those assayed; inhibition values higher than 90% were obtained for both organisms. The highest values for total metal concentrations such as arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), tin (Sn), and zinc (Zn) were found in the Ría of Huelva, which can be classified as severely impacted. The Guadalquivir Estuary and the Bay of Algeciras can be considered moderately impacted. In general, both methodologies are suitable for application in ecotoxicological studies. PMID:20821459

Araújo, Cristiano V M; Diz, Fernando R; Tornero, Victoria; Lubián, Luís M; Blasco, Julián; Moreno-Garrido, Ignacio

2010-02-01

86

Fundamentals of conservation in the Southwest  

Energy Technology Data Exchange (ETDEWEB)

The author discusses mineral and organic wealth in the Southwest as an economic resource. Their value is affected more or less by that idea or method of development broadly called conservation. With the exception of coal, the mineral wealth of the southwest, from the standpoint of an economic foundation for society, is exhaustible. The coal available in the area will probably always be handicapped by long hauls and the absence of water. The organic resources, mainly farms, ranges, forests, waters, and water powers, are in a rundown condition. The author concludes that the deterioration of the fundamental resources - land and water - is in the nature of permanent destruction; the process is also seen to be cumulative and gaining in momentum every year. To explore the deterioration, the author discusses the climate and the delicate balance of the fragile ecosystem of the southwest. He concludes the analysis with a discussion of the moral issues involved, specifically the morality of conservation. (SAC)

Leopold, A.

87

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

88

Listening to Estuary English in Singapore  

Science.gov (United States)

In Singapore, many people are not familiar with Estuary English (EE), the variety of English becoming popular in much of southern England. In the current study, when students listened to interviews with EE speakers and were asked to transcribe orthographically what they heard, most of them had severe problems. Features of pronunciation that…

Deterding, David

2005-01-01

89

Restoration of the Golden Horn Estuary (Halic).  

Science.gov (United States)

Restoration of the iconic Golden Horn Estuary in Istanbul, Turkey was a substantial political, logistical, ecological, and social challenge. Forty years of uncontrolled industrial and urban growth resulted in thick layers of anoxic sediment, toxic bacteria, strong hydrogen sulfide odor, and ecologically unlivable conditions. The major components of restoration, spanning two decades, have included (1) demolition and relocation of industries and homes along the shore, (2) creation of wastewater infrastructure, (3) removal of anoxic sludge from the estuary, (4) removal of a floating bridge that impeded circulation, and (5) creation of cultural and social facilities. Although Turkey is not known as an environmental leader in pollution control, the sum of these efforts was largely successful in revitalizing the area through dramatic water quality improvement. Consequently, the estuary is once again inhabitable for aquatic life as well as amenable to local resource users and foreign visitors, and Istanbul has regained a lost sense of cultural identity. This paper focuses on literature review and personal interviews to discuss the causes of degradation, solutions employed to rehabilitate the estuary, and subsequent physicochemical, ecological, and social changes. PMID:19781731

Coleman, Heather M; Kanat, Gurdal; Aydinol Turkdogan, F Ilter

2009-12-01

90

78 FR 32473 - Southwest Research Institute: Modification of Scope of Recognition  

Science.gov (United States)

...OSHA-2006-0041] Southwest Research Institute: Modification of Scope of...Laboratory (NRTL), Southwest Research Institute, based on that NRTL's voluntary...Determination Regarding Southwest Research Institute Southwest Research...

2013-05-30

91

7 CFR 1126.2 - Southwest marketing area.  

Science.gov (United States)

...AGRICULTURE MILK IN THE SOUTHWEST MARKETING AREA Order Regulating Handling...Definitions § 1126.2 Southwest marketing area. The marketing area means all territory...and all territory occupied by government (municipal, State or...

2010-01-01

92

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

93

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

94

Current Characterization at the Amazon estuary  

Science.gov (United States)

At the estuary there are several mechanisms that cause turbulence: influence of solid contours (estuary bottom and shores), speed vertical shearing (fluid inside), wind shearing stress (free surface) and surface and internal gravity waves. Turbulence intensity controls vertical distribution of estuary water mass property concentration. As flow into the estuary takes place during the transition or turbulent regimen, produced by small space and time scale movements, entrainment, turbulent scattering and advection are the processes responsible for fresh water mixing up with the sea and for local salinity variation, as well as for concentration of natural properties and man-made ones. According to this focus, we shall describe general circulation, conveyance and mixing characteristics of the Amazon low estuary waters. Amazon estuary shows unusual characteristics: it is of vast length and enormous outflow. It is extremely wide - 150 Km - and its discharge into the Atlantic amounts to 180,000 m3s-1 (Otman, 1968, Figueiredo et al, 1991), which means 18% of all water discharged by rivers into oceans; this is the largest punctual source of fresh water for oceans (Milliman and Meade, 1983). Maximum outflow is 2.5 x 105 m3s-1, and it happens at the end of May. Minimum outflow is 1.2 x 105 m3 s-1, and it takes place in November. At Amazon River, the Mixing Zone occurs where the Coastal Zone usually is. The reason for that is the extension of fresh water plume moves Northeast for over 1000 Km (Gibbs, 1970; Muller-Karger et al 1988). This is the most extensive estuarine plume ever found in the ocean. During low fluvial discharge (June-November) plume reaches 300 Km; however, on high discharge (November-May) plume reaches 500 Km. Plume already is 3 to 10 m thick and 80 to 300 Km wide (Lentz and Limeburner, 1995). From June to January plume moves towards Africa, from whence 70% of it goes east carried by North Brazil Current retroflection and 30% goes towards the Caribbean. From February to May, the plume goes northwest towards the Caribbean. As to classification according to salinity stratification, at the quadrature the Amazon estuary is considered as "Saline Wedge" type (highly stratified estuary), salinity at 120 Km way from river moth standing out, whereas at sysygy it can be classified as well mixed (Limeburner et al. 1991e 1992; Patchineelam, 2004). Fresh water is everywhere in the river area, salty or mixed water is located in the ocean. In this estuary 90 Km away from the mouth surface water salinity is less than 0.05 and bottom salinity at 14 m deep is about 19 at high water on quadrature at the end of the rainy season. This behavior produces marked difference in the vertical salinity profile, showing the current is moving in the opposite direction (river fresh water and salty water brought by the tide). In this scenario, speed shearing at the interface produces interfacial friction stress that, from the entrainment process carries portions of water from the sea to the upper part. Usually, therefore, in "saline wedge" (highly stratified estuary) type estuaries, when river discharge is more intensive than the tide wave, entrainment is the predominant mechanism; and the greater tide amplitude is, the greater will its influence be to produce turbulent scattering and mixing be. Probably, at Amazon estuary quadrature entrainment processes are predominant and are the ones responsible for increased salinity in surface layer, whereas turbulence scattering mixing is secondary to it. "Saline wedge" (highly stratified estuary) type estuaries are typical of large fluvial discharge and microtide regions. But although the Amazon estuary is a macrotide region, this stratification is due to the river's exceptional discharge. Due to the remarkable river plume discharge on the platform, the tide - a dominant in macrotide region estuarine circulation - now has a secondary role, albeit not a negligible one, with quadrature amplitudes varying from 2 m to 90 Km from the mouth. It is important to point out that tide-ind

Bezerra, M. O.

2009-04-01

95

Epipelic diatoms in the estuaries of South Africa  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Epipelic diatom flora was sampled around the South African coast between the Olifants Estuary, on the cool Atlantic Ocean northwest coast, and the St. Lucia Estuary, on the Indian Ocean northeast coast. Altogether, 333 taxa were identified with 14 being ubiquitous, as they were found in the cool tem [...] perate, warm temperate, and subtropical areas, as well as in St. Lucia Estuary situated close to Mocambique. There was little difference between the epipelic diatom species present in intertidal and subtidal areas and, because many of the species have a high tolerance to salinity, with some being found in conditions ranging from freshwater to a salinity of more than 150 psu, it was concluded that many of the species sampled do not appear to be reliable indicators for assessing salinity in South African estuaries. Although there was a wide spread of diatoms across all of the estuaries around the coast, the greatest species similarity occurred between the Olifants, Great Berg and Breede estuaries, suggesting that the Breede Estuary, normally considered to fall within the warm temperate region, may be more similar to the cool temperate type estuaries. Data also showed that there was very little similarity between the diatom flora in the rivers flowing into estuaries and the diatom flora in the estuaries.

GC, Bate; PA, Smailes; JB, Adams.

2013-01-01

96

Epipelic diatoms in the estuaries of South Africa  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Epipelic diatom flora was sampled around the South African coast between the Olifants Estuary, on the cool Atlantic Ocean northwest coast, and the St. Lucia Estuary, on the Indian Ocean northeast coast. Altogether, 333 taxa were identified with 14 being ubiquitous, as they were found in the cool tem [...] perate, warm temperate, and subtropical areas, as well as in St. Lucia Estuary situated close to Mocambique. There was little difference between the epipelic diatom species present in intertidal and subtidal areas and, because many of the species have a high tolerance to salinity, with some being found in conditions ranging from freshwater to a salinity of more than 150 psu, it was concluded that many of the species sampled do not appear to be reliable indicators for assessing salinity in South African estuaries. Although there was a wide spread of diatoms across all of the estuaries around the coast, the greatest species similarity occurred between the Olifants, Great Berg and Breede estuaries, suggesting that the Breede Estuary, normally considered to fall within the warm temperate region, may be more similar to the cool temperate type estuaries. Data also showed that there was very little similarity between the diatom flora in the rivers flowing into estuaries and the diatom flora in the estuaries.

GC, Bate; PA, Smailes; JB, Adams.

97

Geomorphologic and physical characteristics of a human impacted estuary: Quequén Grande River Estuary, Argentina  

Science.gov (United States)

Even though the Quequén Grande River Estuary has economic and strategic importance from an oceanographic point of view, it has been ignored until recently. Nevertheless, many anthropogenic modifications (i.e., dredging, jetty and harbour construction, etc.) have taken place in the last 100 years which, most of them, have resulted in significative economic expenses to the harbour and city authorities due to the lack of adequate prior studies. The purpose of this article is to provide a review of the present status of the geomorphology and main physical characteristics of the estuary and describe the effects of these man-made modifications upon the estuary. Data were gathered in several field cruises from 1994 to 2000 plus from continuous recording devices installed at or near the estuary directed to define the present geomorphologic and oceanographic conditions of the estuary and to establish a monitoring program. The ultimate goal is to provide some practical solutions in diminishing the maintenance of the harbour and to provide pollution-control devices. The estuary is classified as a microtidal, primary, coastal-plain system. It can be considered as a partly-mixed system 2 km from the mouth up to its head (15 km inland). Artificial dredging to accommodate the Quequén harbour in the last 2 km of the estuary has induced a highly stratified water column where the upper 2-3 m concentrates low salinity water and the lower layer is filled by water of the same or slightly higher salinity than the inner shelf waters. Due to the presence of a step at the head of the harbour, water circulation is very reduced and in some cases nonexistent, producing strong reductive and even anoxic conditions. The foot of the step is a sediment and organic matter trap that must be dredged periodically to insure adequate navigability.

Perillo, Gerardo M. E.; Pérez, Daniel E.; Piccolo, M. Cintia; Palma, Elbio D.; Cuadrado, Diana G.

2005-01-01

98

Sedimentary Rocks and Methane - Southwest Arabia Terra  

Science.gov (United States)

We propose to land the Mars Science Laboratory in southwest Arabia Terra to study two key aspects of martian history the extensive record of sedimentary rocks and the continuing release of methane. The results of this exploration will directly address the MSL Scientific Objectives regarding biological potential, geology and geochemistry, and past habitability.

Allen, Carlton C.; Oehler, Dorothy Z.; Venechuk, Elizabeth M.

2006-01-01

99

Southwest Energy Innovation Forum: Summary Report  

Science.gov (United States)

The Ewing Marion Kauffman Foundation, Arizona State University (ASU), and U.S. Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E) co-convened a conference on Energy Innovation in the Southwest region of the United States that included participation by entrepreneurs, state government officials, representatives of academia,…

Ewing Marion Kauffman Foundation, 2010

2010-01-01

100

Mexican-Americans in the Southwest.  

Science.gov (United States)

With findings as presented in this 1969 book, a 2-year field study conducted by a 3-member team analyzed the economic, cultural, political, and educational conditions of Mexican Americans in the Southwest (California, Arizona, New Mexico, Colorado, and Texas) with some reference to braceros and the situation in Mexico. An overview of 8 geographic…

Galarza, Ernesto; And Others

 
 
 
 
101

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 (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

102

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

103

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

104

LIMNETIC LARVAL FISH OF THE MAUMEE AND SANDUSKY RIVER ESTUARIES  

Science.gov (United States)

A total of 17 taxa were collected in the Maumee River estuary during sampling periods in 1975, 1976, and 1977. A total of 11 taxa were collected from the Sandusky River estuary in 1976. Gizzard shad/alewife, Dorosoma cepedianum/Alosa pseudoharengus, white bass/white perch, Morone...

105

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

Scientific Electronic Library Online (English)

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

Alicia, González-Solis; Daniel, Torruco.

106

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

107

In situ evaluation of sediment toxicity in Guadalete Estuary (SW Spain) after exposure of caged Arenicola marina.  

Science.gov (United States)

A 7 day in situ assay to assess sediment toxicity was carried out per replicate in two sites from Guadalete Estuary (Guad1 and Guad2) (South-West, Spain) using the polychaete Arenicola marina (n = 20) in benthic cages. After the exposure period, a battery of biomarkers were determined to asses the sediment toxicity. Five of them were exposure biomarkers [ethoxyresorufin O-deethylase (EROD), dibenzylfluorescein (DBF) dependant CytP450, gluthation reductase (GR), and gluthation-S-transferase (GST) activities] and one of them was an effect biomarker [lipid peroxidation (LPO)]. Toxicity due to metals bound to the sediment was found in Guad2. Metals provoke the inhibition of EROD, DBF, and GR and the induction of GST, which is showed to carry out antioxidative stress defense. Toxicity caused by metals and also PAH was detected in Guad1. The presence of these chemicals leads to GST induction in and presumably in consequence, to LPO inhibition. GST activity resulted to be the main protection mechanism against oxidative stress in Arenicola marina. We suggest further research in Guadalete Estuary focusing on the detection and toxicity assessment of pharmaceutical and personal care products. PMID:18561300

Ramos-Gómez, Julia; Martín-Díaz, M Laura; Rodríguez, Araceli; Riba, Inmaculada; DelValls, T Angel

2008-10-01

108

Mercury distribution in Douro estuary (Portugal)  

International Nuclear Information System (INIS)

Determinations of dissolved reactive and total dissolved mercury, particulate and sedimentary mercury, dissolved organic carbon (DOC), particulate organic carbon (POC) and suspended particulate matter (SPM) have been made in the estuary of river Douro, in northern Portugal. The estuary was stratified by salinity along most of its length, it had low concentrations of SPM, typically -3, and concentrations of DOC in the range -3. The surface waters had a maximum dissolved concentration of reactive mercury of about 10 ng dm-3, whereas for the more saline bottom waters it was about 65 ng dm-3. The surface waters had maximum concentrations of total suspended particulate mercury of ?7 ?g g-1 and the bottom waters were always -1. Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 ?g g-1. The transport of mercury in surface waters was mainly associated with organic-rich particulate matter, while in bottom waters the dissolved phase transport of mercury is more important. Lower particulate organic matter, formation of chlorocomplexes in more saline waters and eventually the presence of colloids appear to explain the difference of mercury partitioning in Douro estuarine waters

109

Temporal Variability of Nutrient Budgets in a Tropical River Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available Water, salt, dissolved inorganic nitrogen (DIN, and dissolved inorganic phosphorus (DIP budgets in the Bangpakong Estuary were conducted by repeated observations and multiple box modeling. Water samples for inorganic nutrient analyses were collected monthly from June 2000 to May 2001. Flushing time at the estuary depicts high variations ranging from 1.4 (October 2000 to 80 days (February 2001 with an annual mean of 15.2 days. Seasonal variation in salinity gradients and estuarine Richardson numbers show the Bangpakong Estuary was partially stratified during the wet season and a well-mixed estuary in the dry season. Riverine nutrient inputs and distributions of nutrient concentrations within the river estuary varied in space and time. Temporal variations in fluxes were strong within inter-seasonal scales owing to water fluxes and system concentrations. The increase of DIN and DIP fluxes in the estuary may be the results of degradation of particulate organic matter. The Bangpakong Estuary appears to be a heterotrophic system where respiration exceeds photosynthesis (p-r < 0 and a denitrifying system. Seasonal variations in biogeochemical rates were attributable to differences in magnitude of freshwater inputs.

Thanomsak Boonphakdee

2008-01-01

110

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

111

76 FR 19355 - Notice of Staff Attendance at Southwest Power Pool Markets Operations Policy Committee Meeting  

Science.gov (United States)

...ER11-2861, Southwest Power Pool, Inc. Docket No. ER11-2881, Southwest Power Pool, Inc. Docket No. ER11-2916, Southwest Power Pool, Inc. These meetings...Clarey, Office of Energy Market Regulation, Federal Energy...

2011-04-07

112

Earthquake-triggered landslides in southwest China  

Directory of Open Access Journals (Sweden)

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

113

Sediment Transport Processes In River Dominated Sub-Tropical Estuaries  

Science.gov (United States)

The objective of this study is to present a comparative assessment of the largest three river dominated estuaries in the southern coast of the state of Santa Catarina, Brazil (Tubarão, Araranguá and Mampituba estuaries). The study was focused on mechanisms of transport of suspended sediments influenced by its morphologic and hydrodynamics characteristics. As shown in D'Aquino et al (2011), these estuaries share common attributes (climate and tides) and follow the basic conceptual model of fine sediment transport (presented by Toldo & Schettini (2006). However, each one has its own particularities regarding the geographical setting, land use, hypsometry, outfall, etc. The methodology used to the field measurements was the same for all estuaries, aiming at measuring the currents, water level, salinity, temperature and turbidity near the outfall for at least two complete tidal cycles (~25 hours). All the campaigns were carried on under syzygya tide conditions. During the sample collecting period, a longitudinal profile was conducted in each estuary, through acquisitions of salinity and temperature of the water column in every kilometer. In the Tubarão and Araranguá rivers estuaries, the concentration of suspended particulate matter (SPM) is mostly influenced by the periods of incoming tide, flood currents. In the Mampituba river estuary, the flocculation process was observed during the encounter of fresh and salt water in every tide entrance. It was possible to observe that the Araranguá river estuary, in what concerns the bottom SPM, responds to the variation of salinity and currents along the bottom. The Tubarão estuary presents a relation between the salinity and the bottom currents. In the Mampituba estuary no relevant correlation was found between the SPM, the salinity, and the bottom currents. Those aspects demonstrate that even sharing some characteristics there are significant differences among these estuaries. In addition, as a result of the comparative study, an analytical model was proposed that correlates the fluvial discharge, salt wedge, and SPM. This model might represent a tool to encourage discussions and help the scientific exploration of the estuaries in the south of Santa Catarina.

DAquino, Carla; Schettini, Carlos

2014-05-01

114

The conservation behavior of dissolved uranium in estuary  

International Nuclear Information System (INIS)

To understand the application of radioactive element Uranium, it's significant to determine the relationship between the concentration of uranium and salinity because uranium behaves conservatively in most estuary system. Whereas, in some estuaries, uranium is not conservative which means excess input and remove of uranium occurs during the mixing process of river and sea water. In the present paper, uranium activity data from China and other foreign countries are summarized. According to the relationship between uranium activity and salinity in estuaries, four types of relationships are observed. (authors)

115

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

116

Klein River Estuary (South Africa): 2D numerical modelling of estuary breaching  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english 2D numerical modelling of the breaching process of the Klein River Estuary in South Africa was carried out. The model was calibrated on field data and performs reasonably well, and is able to simulate the ebb and flood channels that form upstream of the mouth. The focus of the simulations was to det [...] ermine the effectiveness of flushing of sediments during breaching, by investigating the breaching process at different water levels in the estuary, as well as at two different areas along the berm. Breaching at higher water levels increases the effectiveness of flushing as the discharge through the mouth increases significantly at higher water levels. Flushing towards the middle or south-east side of the berm is much more effective than towards the north-west side.

JS, Beck; GR, Basson.

117

Southwest Region: A Report Identifying and Addressing the Educational Needs  

Science.gov (United States)

The Educational Technical Assistance Act of 2002, authorized the Southwest Regional Advisory Committee (RAC), whose members represent the states of Arkansas, Louisiana, New Mexico, Oklahoma, and Texas, to identify and prioritize the region's educational needs and recommend how those needs can be met. The Southwest RAC conducted three public…

US Department of Education, 2011

2011-01-01

118

The public's attitudes towards nuclear power in the southwest  

International Nuclear Information System (INIS)

The paper is concerned with the public's attitude towards nuclear power in all its aspects, in South-West England. The southwest sites; are people pro or anti; knowledge, perceived risks/benefits, beliefs and actions; the risk/ benefit ratio; and beliefs about nuclear power, are all briefly discussed. (U.K.)

119

75 FR 61790 - Capital Southwest Corporation; Notice of Application  

Science.gov (United States)

...regulated as a business development company (``BDC'') under the Act.\\1\\ Capital Southwest...Capital Southwest elected to be regulated as a BDC. Section 2(a)(48) of the Act defines a BDC to be any closed-end investment company...

2010-10-06

120

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

 
 
 
 
121

Frequency of twinning in southwest Nigeria  

Directory of Open Access Journals (Sweden)

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

Akinboro A

2008-01-01

122

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

Directory of Open Access Journals (Sweden)

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.

Geddada Mohan NARASIMHA RAO

2010-09-01

123

NEKTON-HABITAT ASSOCIATIONS IN A PACIFIC NORTHWEST (USA) ESTUARY  

Science.gov (United States)

Nekton-habitat associations were determined in Yaquina Bay, Oregon, United States, using a stratified-by-habitat, random, estuary-wide sampling design. Three habitats (intertidal eelgrass [Zostera marina], mud shrimp [Upogebia pugettensis], and ghost shrimp [Neotrypaea californie...

124

SAN JUAN BAY ESTUARY PROGRAM IMPLEMENTATION REVIEW ATTACHMENTS  

Science.gov (United States)

A compilation of attachments referenced in the San Juan Bay Estuary Program Implementation Review (2004). Materials include, entity reports, water and sediment quality action plans, progress reports, correspondence with local municipalities and Puerto Rican governmental agencies,...

125

Biological effects of anthropogenic contaminants in the San Francisco Estuary  

Science.gov (United States)

Concentrations of many anthropogenic contaminants in the San Francisco Estuary exist at levels that have been associated with biological effects elsewhere, so there is a potential for them to cause biological effects in the Estuary. The purpose of this paper is to summarize information about biological effects on the Estuary's plankton, benthos, fish, birds, and mammals, gathered since the early 1990s, focusing on key accomplishments. These studies have been conducted at all levels of biological organization (sub-cellular through communities), but have included only a small fraction of the organisms and contaminants of concern in the region. The studies summarized provide a body of evidence that some contaminants are causing biological impacts in some biological resources in the Estuary. However, no general patterns of effects were apparent in space and time, and no single contaminant was consistently related to effects among the biota considered. These conclusions reflect the difficulty in demonstrating biological effects due specifically to contamination because there is a wide range of sensitivity to contaminants among the Estuary's many organisms. Additionally, the spatial and temporal distribution of contamination in the Estuary is highly variable, and levels of contamination covary with other environmental factors, such as freshwater inflow or sediment-type. Federal and State regulatory agencies desire to develop biological criteria to protect the Estuary's biological resources. Future studies of biological effects in San Francisco Estuary should focus on the development of meaningful indicators of biological effects, and on key organism and contaminants of concern in long-term, multifaceted studies that include laboratory and field experiments to determine cause and effect to adequately inform management and regulatory decisions. ?? 2006 Elsevier Inc. All rights reserved.

Thompson, B.; Adelsbach, T.; Brown, C.; Hunt, J.; Kuwabara, J.; Neale, J.; Ohlendorf, H.; Schwarzbach, S.; Spies, R.; Taberski, K.

2007-01-01

126

Contamination and restoration of an estuary affected by phosphogypsum releases  

International Nuclear Information System (INIS)

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

127

Modeling flocculation in a hypertidal estuary  

Science.gov (United States)

When fine particles are involved, cohesive properties of sediment can result in flocculation and significantly complicate sediment process studies. We combine data from field observations and state-of-the-art modeling to investigate and predict flocculation processes within a hypertidal estuary. The study site is the Welsh Channel located at the entrance of the Dee Estuary in Liverpool Bay. Field data consist of measurements from a fixed site deployment during 12-22 February 2008. Grain size, suspended sediment volume concentration, and current velocity were obtained hourly from moored instruments at 1.5 m above bed. Near-bottom water samples taken every hour from a research vessel are used to convert volume concentrations to mass concentrations for the moored measurements. We use the hydrodynamic model Proudman Oceanographic Laboratory Coastal Ocean Modelling System (POLCOMS) coupled with the turbulence model General Ocean Turbulence Model (GOTM) and a sediment module to obtain three-dimensional distributions of suspended particulate matter (SPM). Flocculation is identified by changes in grain size. Small flocs were found during flood and ebb periods—and correlate with strong currents—due to breakup, while coarse flocs were present during slack waters because of aggregation. A fractal number of 2.4 is found for the study site. Turbulent stresses and particle settling velocities are estimated and are found to be related via an exponential function. The result is a simple semiempirical formulation for the fall velocity of the particles solely depending on turbulent stresses. The formula is implemented in the full three-dimensional model to represent changes in particle size due to flocculation processes. Predictions from the model are in agreement with observations for both settling velocity and SPM. The SPM fortnight variability was reproduced by the model and the concentration peaks are almost in phase with those from field data.

Ramírez-Mendoza, Rafael; Souza, Alejandro J.; Amoudry, Laurent O.

2014-01-01

128

Impressions from South-West Uganda  

Directory of Open Access Journals (Sweden)

Full Text Available Certain features of the prevailing agricultural and livestock management practices in four districts of the South-West Uganda are briefly described. This area is characterized by rather high elevation, good rainfall, fertile soil and hills with steep slopes and mountains in some parts. In three ofthe four districts land is becoming scarce though agricultural production is high but traditional. Cash and food crop production are prevalent ; the staple food being plantain banana and milk production is noticeable. The economy shows evident difficulties mainly due to the so called mismanaged Amin's regime and the ensuing Liberation War. Comments are made on the Queen Elisabeth National Park and some prices are given.

Hardouin, J.

1987-01-01

129

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.

130

Winds and the orientation of a coastal plane estuary plume  

Science.gov (United States)

Based on a calibrated coastal plane estuary plume model, ideal model hindcasts of estuary plumes are used to describe the evolution of the plume pattern in response to river discharge and local wind forcing by selecting a typical partially mixed estuary (the Cape Fear River Estuary or CFRE). With the help of an existing calibrated plume model, as described by Xia et al. (2007), simulations were conducted using different parameters to evaluate the plume behavior type and its change associated with the variation of wind forcing and river discharge. The simulations indicate that relatively moderate winds can mechanically reverse the flow direction of the plume. Downwelling favorably wind will pin the plume to the coasts while the upwelling plume could induce plume from the left side to right side in the application to CFRE. It was found that six major types of plumes may occur in the estuary and in the corresponding coastal ocean. To better understand these plumes in the CFRE and other similar river estuary systems, we also investigated how the plumes transition from one type to another. Results showed that wind direction, wind speed, and sometimes river discharge contribute to plume transitions.

Xia, Meng; Xie, Lian; Pietrafesa, Leonard J.

2010-10-01

131

PCBs in the fish assemblage of a southern European estuary  

Science.gov (United States)

The Mondego estuary fish assemblage was studied for the accumulation of PCBs. Three sampling stations were visited along an estuarine salinity gradient, and, in total, 15 species were collected. Analysis of PCBs revealed no significant differences among the sampling stations, although differences were observed among the fish assemblages. Fish assemblages could be divided into three groups. The first group comprised those with higher concentration (more than 10 ng g- 1, dw), included the species Gobius niger, Sardina pilchardus, Anguilla anguilla, Pomatoschistus microps, Chelidonichthys lucerna and Liza ramada; the second group with medium concentration (5-10 ng g- 1, dw), included the species Pomatoschistus minutus, Dicentrarchus labrax, Atherina presbyter, Chelon labrosus, Diplodus vulgaris, Platichthys flesus and Cilata mustela; and a third group with low concentration (less than 5 ng g- 1, dw), included the species Solea solea and Callionymus lyra. A positive correlation was found between lipid content and PCB concentrations. To evaluate the influence of the residence time of species on the accumulation of PCBs, species were divided into two groups: species that spend more than 3 years in the estuary, and species that spend less than 3 years in the estuary. Species that spend more than 3 years in the estuary presented higher concentrations than species that spend less than 3 years in the estuary. CBs 138 and 153 had higher concentration, and tended to increase with time spent in the estuary.

Baptista, Joana; Pato, Pedro; Pereira, Eduarda; Duarte, Armando C.; Pardal, Miguel A.

2013-02-01

132

Methane and nitrous oxide emissions from a subtropical estuary (the Brisbane River estuary, Australia).  

Science.gov (United States)

Methane (CH4) and nitrous oxide (N2O) are two key greenhouse gases. Their global atmospheric budgeting is, however, flout with challenges partly due to lack of adequate field studies determining the source strengths. Knowledge and data limitations exist for subtropical and tropical regions especially in the southern latitudes. Surface water methane and nitrous oxide concentrations were measured in a subtropical estuarine system in the southern latitudes in an extensive field study from 2010 to 2012 and water-air fluxes estimated using models considering the effects of both wind and flow induced turbulence. The estuary was found to be a strong net source of both CH4 and N2O all-year-round. Dissolved N2O concentrations ranged between 9.1 ± 0.4 to 45.3 ± 1.3 nM or 135 to 435% of atmospheric saturation level, while CH4 concentrations varied between 31.1 ± 3.7 to 578.4 ± 58.8 nM or 1210 to 26,430% of atmospheric saturation level. These results compare well with measurements from tropical estuarine systems. There was strong spatial variability with both CH4 and N2O concentrations increasing upstream the estuary. Strong temporal variability was also observed but there were no clear seasonal patterns. The degree of N2O saturation significantly increased with NOx concentrations (r(2)=0.55). The estimated water-air fluxes varied between 0.1 and 3.4 mg N2O m(-2)d(-1) and 0.3 to 27.9 mg CH4 m(-2)d(-1). Total emissions (CO2-e) were N2O (64%) dominated, highlighting the need for reduced nitrogen inputs into the estuary. Choice of the model(s) for estimation of the gas transfer velocity had a big bearing on the estimated total emissions. PMID:24333994

Musenze, Ronald S; Werner, Ursula; Grinham, Alistair; Udy, James; Yuan, Zhiguo

2014-02-15

133

The status of fish conservation in South African estuaries.  

Science.gov (United States)

Estuary-dependent fish species are defined as those taxa whose populations would be adversely affected by the loss of estuarine habitats. Of the 155 species regularly recorded in South African estuaries, only 32 (21%) are completely dependent on these systems, but this figure increases to 103 species (66%) if partially dependent taxa are included in the analysis. The conservation of fishes in estuaries on the subcontinent is threatened by a number of factors, including habitat degradation, disruption of essential ecological processes, hydrological manipulations, environmental pollution, overexploitation due to fishing activities and, more recently, climate change and the effects of introduced aquatic animals. Although major threats to fishes are usually linked to environmental degradation, there is increasing evidence that the stocks of certain fish species are overexploited or collapsed. Fish conservation and fisheries management does not depend on the implementation of a single action, but rather the co-ordination of a detailed plan, often in a multidisciplinary context. Some examples of innovative means of contributing to estuarine fish conservation in a South African context include the determination and implementation of the ecological freshwater requirements for estuaries, the zoning of estuaries for different uses and the recognition that the maintenance of ecological processes are vital to aquatic ecosystem health. Apart from the designation of protected areas, the main direct means of conserving fish species and stocks include habitat conservation, controls over fishing methods, effort, efficiency and seasonality, pollution control and the prevention of artificial manipulation of estuary mouths. Since becoming a democracy in 1994, environmental legislation, policy and institutional arrangements in South Africa have undergone some major changes, which, if fully implemented, will be very positive for fish conservation in estuaries on the subcontinent. PMID:20557655

Whitfield, A K; Cowley, P D

2010-06-01

134

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

135

33 CFR 165.1190 - Security Zone; San Francisco Bay, Oakland Estuary, Alameda, CA.  

Science.gov (United States)

...Security Zone; San Francisco Bay, Oakland Estuary, Alameda, CA. 165.1190 Section 165.1190 Navigation and Navigable...Security Zone; San Francisco Bay, Oakland Estuary, Alameda, CA. (a) Location. The following area is a security zone:...

2010-07-01

136

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

137

76 FR 25298 - Southwest Idaho Resource Advisory Committee  

Science.gov (United States)

...Community Self-Determination Act of 2000, as amended, (Pub. L 110-343), the Boise, Payette, Salmon-Challis, and Sawtooth National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting. The meeting is open to...

2011-05-04

138

76 FR 18153 - Southwest Idaho Resource Advisory Committee  

Science.gov (United States)

...Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, Salmon-Challis, and Sawtooth National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting. The meeting is open to...

2011-04-01

139

Researchers Simulate Long-gone Societies of the American Southwest  

Science.gov (United States)

... Overviews Priority Areas Speeches & Lectures Multimedia Gallery News Archive News by Research ... people?also known as Anasazi?abruptly abandoned the Four Corners region of the U.S. Southwest in the ...

140

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

 
 
 
 
141

77 FR 5493 - Southwest Fisheries Science Center; Public Meeting  

Science.gov (United States)

...NOAA/NMFS Southwest Fisheries Science Center, Advanced...have broad appeal to fisheries managers and researchers as a tool for ecosystem-based management as well as evaluating...Office of Sustainable Fisheries, National Marine...

2012-02-03

142

What Price Energy? Hazards of Uranium Mining in the Southwest.  

Science.gov (United States)

This article describes the hazards, sickness, death and destruction caused by uranium mining/nuclear energy development in the Southwest focusing on the experiences of several Indian uranium mines. (RTS)

Barry, Tom

1979-01-01

143

Communicating Reengineering at Naval Facilities Engineering Command, Southwest Division  

Science.gov (United States)

This research evaluates how effectively the reengineering process concept has been communicated within the Southwest Division in San Diego, California. It clearly defines reengineering, why reengineering has been embraced by Southwest Division, and what senior leadership's communication objectives and strategies have been since its inception. The research analyzes senior leadership's communication of organizational reengineering and some of the obstacles they have encountered. The research provides action recommendations, where warranted, for greater success in communicating the reengineering process transformation.

Welch, David T.

2002-09-01

144

Sediment balance of intertidal mudflats in a macrotidal estuary  

Science.gov (United States)

Intertidal area contributes widely to fine-grained sediment balance in estuarine environments. Their sedimentary dynamics is controlled by several forcing parameters including tidal range, river flow and swell, affected by human activities such as dredging, construction or vessels traffic leading to modify sediment transport pattern. Although the estuarine hydrodynamics is well documented, the link between forcing parameters and these sedimentary processes is weakly understood. One of the main reasons is the difficulty to integrate spatial (from the fluvial to the estuary mouth) and temporal (from swell in seconds to pluriannual river flow variability) patterns. This study achieved on intertidal mudflats distributed along the macrotidal Seine estuary (France) aims (i) to quantify the impact of forcing parameters on each intertidal area respect to its longitudinal position in the estuarine system and (ii) to assess the fine-grained sediment budget at estuarine scale. The Seine estuary is a macrotidal estuary developed over 160 km up the upstream limit of tidal wave penetration. With an average river flow of 450m3.s-1, 80% of the Suspended Particles Matter (SPM) annual flux is discharged during the flood period. In the downstream part, the Seine estuary Turbidity Maximum (TM) is the SPM stock located near the mouth. During their transfer toward the sea, the fine particles can be trapped in (i) the intertidal mudflats; preferential areas characterized by low hydrodynamics and generally sheltered of the tidal dominant flow, the main tidal current the Seine River and (ii) the TM. The Seine estuary is an anthropic estuary in order to secure navigation: one consequence of these developments is the tidal bore disappearance. Along the macrotidal Seine estuary hydrodynamics features and sedimentary fluxes were followed during at least 1 year using respectively Acoustic Doppler Velocimeter, Optical BackScatter and altimeter. Results in the fluvial estuary enhance the role of hydrological cycle that lead to (i) an increased mean water level and (ii) provide SPM from the continental area. This feature leads to significant accretion over intertidal area. In the middle and marine estuary the TM is the main SPM supplier. In these parts of the estuary deposition over these intertidal area is driven by (i) tidal cycle in particular fortnightly cycle link to maximum TM resuspension during (strongest) spring tide and (ii) TM location controlled by river inflow that varies following an annual and inter-annual variability. Outside sedimentation period, the erosion is driven by the combination of (i) progressive erosion driven by fortnightly cycle and (ii) sudden erosion controlled either by wave or boat generated waves respectively at the mouth and in the middle/upper estuary. This last is reinforced by the rheological characteristics of deposit that correspond to fluid/low consolidated mud. During most of the year, the Seine estuary mudflats record an erosion pattern. Significant and intensive sedimentation only occurs few days per year. This pattern is linked to highly variable hydrodynamics conditions (bottom shear stress ranging from 0.5 to 5 N.m-2) that control the sediment supply availability. In this infilling macrotidal anthropized system mudflats are close to equilibrium with an annual rate ranging between +/- 5cm.yrs-1: they act as temporal storage area of fined-grained sediments.

lafite, R.; Deloffre, J.; Lemoine, M.

2012-12-01

145

Southwest conference on optics. SPIE Volume 540  

International Nuclear Information System (INIS)

In 1985 the Los Alamos Conference on Optics, which has been held previously in Los Alamos and Santa Fe, New Mexico, expanded its coverage and moved to Albuquerque as the Southwest Conference on Optics. This was made possible by a broad increase in the Conference sponsorship, which this year included research and educational institutions throughout New Mexico, Colorado, Arizona, Utah, Texas, and old Mexico, as well as SPIE, OSA, and LIA. In that portion of the Conference represented by the present volume, about 115 papers were presented, of which the majority were contributed papers given in poster sessions. The texts of most of these papers, both invited and contributed, are included here. The organization of this volume generally follows that of the Conference, with the papers arranged by the various sessions: General Invited Papers; Optical Components, Materials, and Design; Lasers and Laser Systems; Spectroscopy and Spectroscopic Applications; Applications of Optics; and the Symposium on Optics Along the Rio Grande Research Corridor. There was some rearrangement to provide for a more logical sequence, and the postdeadline papers have been placed in their proper sessions

146

Proliferation of dinoflagellates in Kochi estuary, Kerala.  

Science.gov (United States)

Phytoplankton community structure and dynamics of Kochi estuary (bar mouth) have been studied seasonally. Three seasonal samplings namely pre-monsoon, monsoon and post-monsoon were made, and a wide variation was observed in phytoplankton community with respect to nutrients and other physicochemical parameters. Contrary to other seasons, dinoflagellate cell density increased during pre-monsoon season though species diversity was less pronounced (D > 0.15). Peridinium oceanicum was the dominant dinoflagellate during pre-monsoon season. Significant fluctuation in three principal nutrients namely total nitrogen, total phosphorous and silicate were observed during pre-monsoon (TP 40 micromol l(-1) and SiO4 3.20 micromol l(-1), TN 27 micromol l(-1)). Salinity values were also found to be high during pre-monsoon ( > 25 psu). Study suggests that variation in salinity and nutrient concentration during transition of seasons could result in succession of species, thereby causing change in phytoplankton community structure. High salinity and nitrogen values along with low values of silicate and phosphorous resulted in proliferation of dinoflagellates during pre-monsoon season. PMID:25204062

Kumar, M Ratheesh; Vishnu, S Raj; Sudhanandh, V S; Faisal, A K; Shibu, R; Vimexen, V; Ajmal, K; Aneesh, K S; Antony, Sibin; Krishnan, Anoop K

2014-09-01

147

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

148

?-particle radioactivity of hot particles from the Esk estuary  

International Nuclear Information System (INIS)

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

149

Thermal discharge effects on dissolved oxygen in an urban estuary  

International Nuclear Information System (INIS)

As part of the permitting process for power generation plant repowering, the impact of once-through cooling to estuary dissolved oxygen concentration was examined. This included field investigation of temperature and dissolved oxygen concentration with depth at various places in the estuary under different plant operating conditions, statistical analysis of the resulting data, calibration of a water quality model to the data set, and use of the model to predict the impact of the repowered facility under drought conditions. It was concluded that the once-through cooling operation had a positive impact on estuary dissolved oxygen by its destratification of the water column and its introduction of dissolve oxygen into the effluent by turbulent mixing

150

Mud transport in the Microtidal San Jacinto Estuary  

Science.gov (United States)

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

Salehi, M.

2013-12-01

151

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 ICP-MS and modeling were applied on the waters, and a variety of chemical reagents were used to extract metals from the settling material. Aluminium, Fe and REE transported by the 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 REE and the colloidal (0.45 ?m-1 kDa) pool depleted in the middle and heavy REE. This fractionation was controlled by the removal process, such that those REE with highest affinity for the settling particles became most depleted in the remaining dissolved pool. Modeling, based on Visual MINTEQ version 3.0 and the Stockholm Humic Model after revision and updating, predicted that the dissolved (REE pool in the estuary is bound almost entirely to 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

152

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

153

Human Impact on Estuaries: A Terrible Spill in Grand Bay  

Science.gov (United States)

In this activity, learners make a model of a pollution spill that occurred at Bangs Lake in Mississippi and measure water quality parameters in their model. Learners then study the actual spill, analyzing various forms of data to determine the date of the spill and identify how the spill changed water quality parameters in the estuary during and after the spill. Learners speculate on how various life forms in the estuary were affected. Finally, learners produce a timeline of the spill event, with recommendations to the state Department of Environmental Quality about how to prevent large-scale pollution spills like this in the future.

Terc; National Oceanic and Atmospheric Administration (NOAA)

2012-07-24

154

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.

155

Physical biological coupling in the Pearl River Estuary  

Science.gov (United States)

The Pearl River Estuary is a subtropical estuary and the second largest in China based on discharge volume from the Pearl River. Processes in the estuary vary spatially and temporally (wet vs dry season). In the dry season at the head of the estuary, hypoxic and nearly anoxic conditions occur and NH 4 reaches >600 ?M, NO 3 is ˜300 ?M and nitrite is ˜60 ?M indicating that nitrification and denitrification may be important dry season processes in the region extending 40 km upstream of the Humen outlet. There are very few biological studies conducted in this upper section of the estuary in either the dry or wet seasons and hence there is a need for further research in this region of the river. In the wet season, the salinity wedge extends to the Hongqimen outlet and oxygen is low (35-80% saturation). Nitrate is ˜100 ?M, silicate ˜140 ?M; and phosphate is relatively low at ˜0.5 ?M, yielding an N:P ratio up to ˜200:1 in summer. Nutrients decrease in the lower estuary and primary productivity may become potentially P-limited. Eutrophication is not as severe as one would expect from the nutrient inputs from the Pearl River and from Hong Kong's sewage discharge. This estuary shows a remarkable capacity to cope with excessive nutrients. Physical processes such as river discharge, tidal flushing, turbulent dispersion, wind-induced mixing, and estuarine circulation play an important role in controlling the production and accumulation of algal blooms and the potential occurrence of hypoxia. Superimposed on the physical processes of the estuary are the chemical and biological processes involved in the production of the bloom. For example, the 100N:1P ratio indicates that P potentially limits the amount of algal biomass (and potential biological oxygen demand) in summer. While extended periods of hypoxia are rare in Hong Kong waters, episodic events have been reported to occur during late summer due to factors such as low wind, high rainfall and river discharge which result in strong density stratification that significantly dampens vertical mixing processes. Nutrient loads are likely to change over the next several decades and monitoring programs are essential to detect the response of the ecosystem due to the future changes in nutrient loading and the ratio of nutrients.

Harrison, Paul J.; Yin, Kedong; Lee, J. H. W.; Gan, Jianping; Liu, Hongbin

2008-07-01

156

Rhenium and Molybdenum in Rivers and Estuaries.  

Science.gov (United States)

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

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

2004-12-01

157

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-02-05

158

Consequences of land use and climate changes on sediment deposition in estuaries during the last centuries  

Science.gov (United States)

Estuaries are the downstream end-member of fluvial systems. They are experiencing high sedimentation rates, thus providing good opportunities for high resolution studies of Holocene environmental changes at the land/ocean interface. From a thorough literature survey, it appears that a rapid siltation and/or an increase in sedimentation rate were recorded in many estuarine environments, concomitantly to major migrations of human population throughout the world, both in time and space. It has been clearly related to an increase in sediment supply to estuaries in Minor Asia (Bronze Age, e.g. Spezzaferri et al, 2000) and in North America and Southwest Pacific (18th and 19th centuries, e.g. Goff, 1997), in response to deforestation on catchment areas. However, this relationship is less obvious in Europe (Sorrel et al., 2009), because deforestation occurred concomitantly to climate changes of the last millennium (climate instability at the end of Medieval Warm Period, Little Ice Age) that can also explain an increase in soil erosion. Indeed, these hypotheses have been proposed to explain a similar change in Marennes-Oléron Bay (Atlantic coast of France), which consists in the sudden deposition of a few meters-thick mud drape on basal mixed mud and sand bodies (Billeaud et al., 2005). The methods used to investigate this estuarine bay so far (very high resolution seismic stratigraphy, grain size analysis and radiocarbon dating) provided relevant information about recent environmental changes, but new data are now needed for further investigation. In the present study, we provide a multi-proxy analysis of the Marennes-Oléron Bay mud drape. A new 8 m-long core (M7UC01) was sampled on an intertidal flat, its location being determined on the basis of seismic stratigraphy. Core processing included visual description, physical measurements, grain size analysis every 2.5 to 5 cm, AMS radiocarbon dating, XRF core scanning, clay mineralogy and Rock Eval analysis. Fossil molluscs and foraminifers were also recovered to provide paleoenvironmental reconstructions. Clay mineralogy of the mud drape is similar to that of the turbid plume of the Charente River, which is an important source of terrestrial sediment in the bay, and to surrounding marsh soils. Examination of sediment smear slides shows that the sediment contains abundant plant debris. The very low values of Hydrogen Index determined by Rock-Eval analysis (mean HI: 150 ± 25 mg HC.g-1 TOC) are typical of organic matter derived from land higher plants. These three results strongly suggest that the Marennes-Oléron Bay mud drape is composed of soil relicts derived from the watershed. The mud drape started to deposit at 1400 AD, which coincides with the start of the Spörer minimum. Fossil mollusc and foraminifer assemblages provide evidences of another environmental change dated to 1670 AD, which corresponds to the Maunder minimum. These data suggest a strong impact of Little Ice Age climate changes, superimposed to land reclamation and deforestation, on the increase of sediment supply in the study area. These results, compared with the detailed literature survey performed meanwhile, would provide new insights into the impact of simultaneous land use and climate changes on the sediment deposition in estuaries during the last centuries. References: Billeaud I. et al., 2005. Geo-Marine Letters 25, 1-10. Goff J.R., 1997. Marine Geology 138, 105-117. Sorrel P. et al., 2009. Quaternary Science Reviews 28, 499-516. Spezzaferri S. et al., 2000. Mediterranean Marine Science 1(1), 19-43.

Poirier, Clément; Chaumillon, Eric; Arnaud, Fabien; Goubert, Evelyne; Sauriau, Pierre-Guy; Caurant, Florence

2010-05-01

159

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)

160

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

 
 
 
 
161

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

2014-10-01

162

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

163

CHEMICAL CONSTITUENTS OF AVICENNIA ALBA OF KRISHNA ESTUARY  

Directory of Open Access Journals (Sweden)

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

Ramanjaneyulu MVV* and Venkateswara Rao

2013-12-01

164

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...

165

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)

166

SAN JUAN BAY ESTUARY, COMPREHENSIVE CONSERVATION AND MANAGEMENT PLAN  

Science.gov (United States)

This Comprehensive Conservation and Management Plan (CCMP) contains information about the overall health of the San Juan Bay Estuary (SJBE) as well as proposed solutions to identified problems. These solutions, or Action Plans, are the result of a more than 4-year process of cons...

167

The chemical control of soluble phosphorus in the Amazon estuary  

Science.gov (United States)

The role of sediments in controlling concentrations of soluble phosphorous in the Amazon estuary is examined. The efflux of phosphorous through the estuary is calculated using data collected on field excursions in December 1982 and May 1983, and laboratory mixing experiments. It is observed that soluble phosphorus was released from bottom sediments at a rate of 0.2 micro-M/day, when in seawater and deionizd water mixtures. The relation between release rates and salinity and sediment concentrations is studied. A one-dimensional dispersion model was developed to estimate phosphate inputs to the estuary. The model predicted total fluxes of soluble inorganic phosphorous of 15 x 10 to the 6th mole/day for December 1982 and 27 x 10 to the 6th mole/day for May 1983; the predictions correlate with field observations. It is noted that phosphorous removal is between 0 and 4 ppt at a rate of 0.044 + or - 0.01 micron-M/ppt per day and the annual mean input of phophorous from Amazon to outer-estuary is 23 x 10 to the 6th moles/day.

Fox, L. E.; Wofsy, S. C.; Sager, S. L.

1986-01-01

168

Burrowing shrimp as foundation species in NE Pacific estuaries  

Science.gov (United States)

My talk will be about the my research to characterize the role that burrowing shrimp play as foundation/engineering species in Pacific NW estuaries. My research has focused on measuring the abundance & distribution of two species (ghost shrimp & mud shrimp) at ecosystem scales, ...

169

76 FR 76712 - Notice of Staff Attendance at Southwest Power Pool Markets and Operations Policy Committee Meeting  

Science.gov (United States)

...ER12-444, Southwest Power Pool, Inc. Docket No. ER12-455, Southwest Power Pool, Inc. Docket No. ER12-457, Southwest Power Pool, Inc. Docket No...Clarey, Office of Energy Market Regulation, Federal Energy...

2011-12-08

170

76 FR 2369 - Notice of Staff Attendance at Southwest Power Pool Markets and Operation Policy Committee and...  

Science.gov (United States)

...ER11-2525, Southwest Power Pool, Inc. Docket No. ER11-2528, Southwest Power Pool, Inc. Docket No. ER11-2619, Southwest Power Pool, Inc. These meetings...Clarey, Office of Energy Market Regulation, Federal Energy...

2011-01-13

171

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

172

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.

173

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

Science.gov (United States)

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

2011-03-21

174

76 FR 24048 - Notice of Public Meeting, Southwest Colorado Resource Advisory Council Meeting  

Science.gov (United States)

...INFORMATION: The Southwest Colorado RAC advises the Secretary of...variety of public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include field manager and working group reports, recreation,...

2011-04-29

175

75 FR 23288 - Notice of Public Meeting, Southwest Colorado Resource Advisory Council Meeting  

Science.gov (United States)

...INFORMATION: The Southwest Colorado RAC advises the Secretary of...variety of public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include field manager and working group reports, recreation,...

2010-05-03

176

75 FR 6060 - Notice of Public Meeting, Southwest Colorado Resource Advisory Council Meeting  

Science.gov (United States)

...INFORMATION: The Southwest Colorado RAC advises the Secretary of...variety of public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include field manager and working group reports, recreation,...

2010-02-05

177

76 FR 81962 - Notice of Public Meeting, Southwest Colorado Resource Advisory Council  

Science.gov (United States)

...INFORMATION: The Southwest Colorado RAC advises the Secretary of...variety of public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include field manager and working group reports, recreation,...

2011-12-29

178

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...

179

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...

180

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.

 
 
 
 
181

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-02-20

182

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

LENUS (Irish Health Repository)

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

Kennedy, M P

2012-02-03

183

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

184

Collection Development "Southwest Gardening": The Desert Shall Bloom  

Science.gov (United States)

Gardening in the American Southwest (SW) is an extreme sport. Not only are gardeners challenged by geographic extremes from tropical deserts to subalpine locales, they must also deal with a wide range of climates. Winter in the mountains and higher regions means heavy snows, frozen soils, and temperatures that can dip below zero. In contrast,…

Charles, John; Mosley, Shelley; Van Winkle, Sandra

2008-01-01

185

A law & economics approach to the study of integrated management regimes of estuaries  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper it is proposed to analyse legal regimes for integrated management of estuaries with the help of institutional legal theory and the Schlager & Ostrom framework for types of ownership. Estuaries are highly valued and valuable and therefore need protection. The problem is that they qualify as multiple-use and multiple-user common pool resources. To be able to analyze the legal regimes governing the estuaries, you must be able to take the position of governmental actors and NGO's in...

Griendt, Wim

2004-01-01

186

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper are presented the vision, strategic guidelines/measures and the action plan for shellfish farming development in the Krka river estuary. They came as a result from several discussions that were held with shellfish farmers of the estuary area in year 2008 while writing the Integrated Plan for Shellfish Farming for Krka Estuary Area, which was realized in the framework of the Green Business Support Programme (UNDP COST Project — Conservation, and Sustainable Use of Biodiversity ...

Drago Maguš

2009-01-01

187

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

188

Thermal impact assessment of multi power plant operations on estuaries  

International Nuclear Information System (INIS)

The assessment of the thermal impact of multi power plant operations on large estuaries requires careful consideration of the problems associated with: re-entrainment, re-circulation, thermal interaction, delay in the attainment of thermal equilibrium state, and uncertainty in specifying open boundaries and open boundary conditions of the regions, which are critically important in the analysis of the thermal conditions in receiving water bodies with tidal dominated, periodically reversing flow conditions. The results of an extensive study in the Hudson River at Indian Point, 42 miles upstream of the ocean end at the Battery, concluded that the tidal-transient, multi-dimensional discrete-element (UTA) thermal transport models (ESTONE, FLOTWO, TMPTWO computer codes) and the near-field far-field zone-matching methodology can be employed with a high degree of reliability in the assessment of the thermal impact of multi power plant operations on tidal dominated estuaries

189

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

190

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

191

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

192

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

193

Wave-current interactions in a tide dominated estuary  

Science.gov (United States)

There is a need to understand the interactions of waves and currents in the nearshore and estuarine areas. By using observational data and an advanced model an assessment of the wave-current interactions was performed in a hypertidal estuary. The circulation model includes both barotropic and baroclinic processes arising from tides, rivers and atmospheric forcing. It is coupled to a spectral wave model and a turbulence model. Waves within the estuary are strongly modulated by the tide. Significant wave height and period are mainly controlled by time-varying water depth, but wave periods are also affected by a Doppler shift produced by the current. The major-axis depth-averaged current component is tidally dominated and wave-induced processes do not have a significant effect on it. However, the inclusion of wave effects, in particular 3D radiation stress, improves the depth-averaged minor-axis (transverse) current component. The residual currents show a clear two-layer system, indicating that the baroclinic river influence is the dominant process. The wave effects are second order, but their consideration improves the long-term modelled residual circulation profile, specially the along estuary component. The main improvement appears when a 3-dimensional radiation stress coupling is considered. The 3D version of radiation stress produced better results than the 2D version. Within the estuary, wave setup has little effect on the storm surge, while 2-way wave-current interaction improved the wave simulation. Using a 3D Doppler shift further improved the model compared with using a 2D version.

Bolaños, Rodolfo; Brown, Jennifer M.; Souza, Alejandro J.

2014-09-01

194

Morphodynamics of the Cávado estuary inlet (NW Portugal)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Cávado estuary inlet is situated in the coastal zone of Esposende (NW Portugal) where sandy beaches have migrated inland and thinned, and cliffs have retreated rapidly over the last years. The coastal zone of Esposende extends over 15 km from the Neiva River until Apúlia. The coastal segment of Esposende can be considered of mixed energy and wave-dominated type, according to DAVIS and HAYES (1984). The local tide is mesotidal and semidiurnal, with a maximum equinoctial spring t...

Loureiro, Eduardo; Granja, Helena Maria; Pinho, Jose? L. S.

2005-01-01

195

Caspian Rapid Sea Level Changing Impact on Estuaries Morphodynamic Deformation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, the evaluation of sedimentary-morphodynamic deformation of main estuaries of rivers in the southern coasts of the Caspian Sea is main target. With selecting, eight main rivers and by sampling of sediments on them in the beach zones, geometry of surrounded beach structure, morphodynamic condition and sedimentary deposition processes were analyzed. with interpretation satellite and aerial images of study area along the period between 1983 till 2004 that correspond to last progres...

Homayoun Khoshravan; Masoumeh Banihashemi

2013-01-01

196

Future variability of solute transport in a macrotidal estuary  

Science.gov (United States)

The physical controls on salt distribution and river-sourced conservative solutes, including the potential implications of climate change, are investigated referring to model simulations of a macrotidal estuary. In the UK, such estuaries typically react rapidly to rainfall events and, as such, are often in a state of non-equilibrium in terms of solute transport; hence are particularly sensitive to climate extremes. Sea levels are projected to rise over the 21st century, extending the salinity maximum upstream in estuaries, which will also affect downstream solute transport, promoting estuarine trapping and reducing offshore dispersal of material. Predicted 'drier summers' and 'wetter winters' in the UK will influence solute transport further still; we found that projected river flow climate changes were more influential than sea-level rise, especially for low flow conditions. Our simulations show that projected climate change for the UK is likely to increase variability in estuarine solute transport and, specifically, increase the likelihood of estuarine trapping during summer, mainly due to drier weather conditions. Future changes in solute transport were less certain during winter, since increased river flow will to some extent counter-act the effects of sea-level rise. Our results have important implications for non-conservative nutrient transport, water quality, coastal management and ecosystem resilience.

Robins, Peter E.; Lewis, Matt J.; Simpson, John H.; Howlett, Eleanor R.; Malham, Shelagh K.

2014-12-01

197

Predicting habitat associations of five intertidal crab species among estuaries  

Science.gov (United States)

Intertidal crab assemblages that are active on the sediment surface of tropical estuaries during tidal exposure play an important role in many fundamental ecosystem processes. Consequently, they are critical contributors to a wide range of estuarine goods and services. However, a lack of understanding of their spatial organization within a large landscape context prevents the inclusion of intertidal crabs into generally applicable ecological models and management applications. We investigated spatial distribution patterns of intertidal crabs within and among eight dry tropical estuaries spread across a 160 km stretch of coast in North East Queensland, Australia. Habitat associations were modelled for five species based on photographic sampling in 40-80 sites per estuarine up- and downstream component: Uca seismella occurred in sites with little structure, bordered by low intertidal vegetation; Macrophthalmus japonicus occupied flat muddy sites with no structure or vegetation; Metopograpsus frontalis and Metopograpsus latifrons occupied sites covered with structure in more than 10% and 25% respectively. Finally, both Metopograpsus spp. and Metopograpsus thukuhar occupied rock walls. Habitat associations were predictable among estuaries with moderate to high sensitivity and low percentages of false positives indicating that simple, physical factors were adequate to explain the spatial distribution pattern of intertidal crabs. Results provide a necessary first step in developing generally applicable understanding of the fundamental mechanisms driving spatial niche organization of intertidal crabs within a landscape context.

Vermeiren, Peter; Sheaves, Marcus

2014-08-01

198

Air-Sea Gas Transfer Velocity in a Shallow Estuary  

Science.gov (United States)

The air-sea transfer velocity of was investigated in a shallow estuary in March to July 2012, using eddy-covariance measurements of fluxes and measured air-sea partial-pressure differences. A data evaluation method that eliminates data by nine rejection criteria in order to heighten parametrization certainty is proposed. We tested the data evaluation method by comparing two datasets: one derived using quality criteria related solely to the eddy-covariance method, and the other derived using quality criteria based on both eddy-covariance and cospectral peak methods. The best parametrization of transfer velocity normalized to a Schmidt number of 600 was determined to be: where is the wind speed in m at 10 m; is based on fluxes calculated by the eddy-covariance method and including the cospectral peak method criteria. At low wind speeds, the transfer velocity in the shallow water estuary was lower than in other coastal waters, possibly a symptom of low tidal amplitude leading to low intensity water turbulence. High transfer velocities were recorded above wind speeds of 5 m , believed to be caused by early-breaking waves and the large fetch (6.5 km) of the estuary. These findings indicate that turbulence in both air and water influences the transfer velocity.

Mørk, Eva Thorborg; Sørensen, Lise Lotte; Jensen, Bjarne; Sejr, Mikael K.

2014-04-01

199

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.

200

Local flows in the Quequén Grande River Estuary, Argentina  

Science.gov (United States)

Quequén 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 Quequén-Necochea area and Quequén 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 Quequén 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.

Pereyra, M. G.; Thomas, L. P.; Marino, B. M.

2009-05-01

 
 
 
 
201

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2007-01-01

202

Coastal upwelling along the southwest coast of India – ENSO modulation  

Directory of Open Access Journals (Sweden)

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

K. Muni Krishna

2008-06-01

203

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

204

Monsoons and habitat influence trophic pathways and the importance of terrestrial-marine linkages for estuary sharks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Tropical estuaries often receive enhanced fluxes of terrestrial derived organic matter and phytoplankton during the wet season, and such monsoonal events may significantly influence the trophic dynamics of these systems. This study examined spatio-temporal terrestrial-marine linkages in a tropical estuary, the Pearl River Estuary (PRE), southern China, by investigating trophic pathways leading to estuary sharks. We investigated spatial (inshore vs. offshore) and seasonal (wet vs. dry season) ...

Yeung, Jwy; Lam, Vyy; Williams, Ga; Wai, Tc; Leung, Kmy; Dudgeon, D.

2012-01-01

205

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

206

NCLB: Local implementation and impact in southwest Washington state.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Linda Mabry; Linda Mabry and Jason Margolis

2006-01-01

207

Fluid inclusions in quartz crystals from South-West Africa.  

Science.gov (United States)

Quartz crystals from calcite veins of unknown age in Precambrian metasedimentary rocks at Geiaus No. 6 and Aukam farms in South-West Africa contain both primary and secondary inclusions filled with one substance or a combination of substances. These substances include organic liquid, moderately saline aqueous liquid, dark-colored solid, and a vapor. Analysis of these materials by microscopy and by gas chromatography and mass spectrometry shows the presence of constituents of both low and high molecular weights.

Kvenvolden, K. A.; Roedder, E.

1971-01-01

208

Premarital sexual activities in an urban society of Southwest- Nigeria  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

209

Marine mammal strandings in the New Caledonia region, Southwest Pacific  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Borsa, Philippe

2006-01-01

210

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

211

RELATIONSHIPS BETWEEN SEAGRASSES, BENTHIC MACROALGAE AND NUTRIENTS IN A PACIFIC NORTHWEST ESTUARY  

Science.gov (United States)

Pacific Northwest estuaries are characterized by large tidal ranges (2-3 m) that routinely expose submerged aquatic vegetation (SAV) such as seagrass and benthic macroalgae. The dominant native seagrass in PNW estuaries is the eelgrass Zostera marina. However, in recent decades...

212

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

213

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

214

Water pollution in estuaries and coastal zones. (Latest citations from the NTIS bibliographic database). Published Search  

Energy Technology Data Exchange (ETDEWEB)

The bibliography contains citations concerning the studies of water pollution in estuaries and coastal zones. Citations examine the development, management, and protection of estuary and coastal resources. Topics include pollution sources, environmental monitoring, water chemistry, eutrophication, models, land use, government policy, and laws and regulations. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1996-02-01

215

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

Scientific Electronic Library Online (English)

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

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

2008-11-01

216

78 FR 68995 - Safety Zone: Vessel Removal From the Oakland Estuary, Alameda, CA  

Science.gov (United States)

...Removal From the Oakland Estuary, Alameda, CA AGENCY: Coast Guard, DHS. ACTION: Temporary...north of the Park Street Bridge in Alameda, CA in support of the Oakland Estuary Closure...north of the Park Street Bridge in Alameda, CA. Crane operations to remove sunken...

2013-11-18

217

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

218

Simulating Suspended Silt Concentrations in the Ems Estuary, The Netherlands  

Science.gov (United States)

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

Grasmeijer, B. T.

2009-04-01

219

[Water and environment in the Southwest of Madagascar].  

Science.gov (United States)

The dry and arid southwest region of Madagascar is not a desert but resembles the Sahel region of West Africa. The chronic water deficit is aggravated by the heat and constant winds that accelerate evapotranspiration on the permeable soils. The dryness occurs because the southwest region lies outside the main pluviogenic systems. Erosion occurs at all seasons. In the winter the sun and winds are the main causes, while the rare storms are more conducive to run-off and to erosion than to absorption. The acute water shortage in the southwest has prompted hydrogeologic research and well-drilling, but the high salt content of the water and other impurities will be a limiting factor for development of the area. The population of the southwest is extremely mobile. Human settlements are concentrated in the valleys and depressions and along major roads. Customary rights to land under the control of the traditional chiefs regulate tenure in most areas. But especially in the river bottoms, the coming of cash crops cultivated with modern equipment has resulted in significant erosion which has aggravated ecological problems. Accelerating soil degradation has led peasants to extend their lands under cultivation to the detriment of forest cover. Cattle herding remains the principal economic activity in the southwest. Herding has progressed from nomadism to pastoralism, but it remains a sign of power and wealth. Transhumance is the strategy of herders faced with shortages of water and pasturage, demographic pressure, and environmental degradation. Raising of sheep and goats constitutes a supplemental food source, medium of exchange, and form of savings. But angora goats graze on everything in their path, devastating their surrounds. Fear of cattle thefts militates against efforts to improve the quality of the stock. The various problems together have prompted a wasteful exploitation of the forest resources. Development strategies for the area explored by the government have all been forced to consider the high cost of potable water. A water project forms part of the Environmental Plan of Action launched by Madagascar with the assistance of international organizations. PMID:12286688

Razanamparany, L

1993-04-01

220

Optical properties of a tropical estuary during wet and dry conditions in the Nha Phu estuary, Khanh Hoa Province, south-east Vietnam  

DEFF Research Database (Denmark)

There has been a strong research focus on optical properties in temperate estuaries but very much less in tropical estuaries. These properties comprise light and beam attenuation dominated by suspended particulate matter, Chl a, and CDOM. Spatially and temporally distributed data on optical properties in a tropical wet and dry estuary are compared and discussed in relation to those of temperate estuaries. Sampling in the Nha Phu estuary, Vietnam, consisted of five stations on a transect from head to mouth that was sampled four times during dry conditions and three times during wet conditions between May 2006 and April 2008. Methods comprised CTD, optical measurements, and water sampling for suspended matter, Chl a, and CDOM. Results showed high light attenuation—K d(PAR)—in wet conditions and low in dry. K d(PAR) was highest at the estuary head and lower in the outer part. Spatial and temporal variations in K d(PAR) were in general dominated by variations in suspended particulate matter concentrations in both wet and dry conditions. Chl a concentrations were low and showed no strong variations between wet and dry conditions. CDOM absorption coefficients were higher in wet conditions with high values at the head and lower in the central part of the estuary. The depth of the photic zone was reduced by up to 50% during wet conditions. A residence time in the estuary of 5–6 days was derived from the rate of change of K d(PAR) after a period of heavy rain and discharge of freshwater into the estuary. This complied with a residence time of four and a half days derived from a basic physical relation. Optical properties were in general comparable to temperate estuaries in dry conditions although Chl a concentrations were lower in Nha Phu. A second distinctive point, as compared to temperate estuaries, was the episodic character with days of strong rainfall followed by longer periods of dry weather. All sampling, both wet and dry, was carried out in the dry season which implies a less definitive perception of wet and dry seasons.

Nielsen, Morten Holtegaard

2010-01-01

 
 
 
 
221

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

222

A framework for investigating general patterns of benthic ?-diversity along estuaries  

Science.gov (United States)

The description of major patterns in beta (?) diversity is important in order to understand changes in community composition and/or richness at different spatial and temporal scales, and can interrogate processes driving species distribution and community dynamics. Human impacts have pushed many estuarine systems far from their historical baseline of rich, diverse, and productive ecosystems. Despite the ecological and social importance of estuaries, there has not yet been an attempt to investigate patterns of ?-diversity and its partitioning along estuarine systems of different continents. We aimed to evaluate if benthic assemblages would show higher turnover than nestedness in tropical than in temperate systems, if well-known impacted estuaries would show greater nestedness than less polluted systems, and to propose a conceptual framework for studying benthic macrofauna beta diversity along estuaries. We analyzed subtidal benthic macrofaunal data from estuaries in Brazil, USA and France. We estimated alpha (?), beta (?) and gamma (?) diversity for each sampling time in each system, investigated patterns of ? -diversity as multivariate dispersion and the partitioning (nestedness and replacement) of ?-diversity along each estuary. There was a decrease in the ?-diversity along marine to freshwater conditions at most of the estuaries and sampling dates. Beta diversity as multivariate dispersion showed high variability. Most of the estuaries showed a greater proportion of the ?-diversity driven by replacement than nestedness. We suggest a conceptual framework for estuaries where relatively pristine estuaries would have their ?-diversity mostly driven by replacement while impacted estuaries subjected to several anthropogenic stressors would show total nestedness or total replacement, depending on the stress.

Barros, Francisco; Blanchet, Hugues; Hammerstrom, Kamille; Sauriau, Pierre-Guy; Oliver, John

2014-08-01

223

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2000-05-01

224

Occurrence and distribution of dissolved tellurium in Changjiang River estuary  

Science.gov (United States)

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

Wu, Xiaodan; Song, Jinming; Li, Xuegang

2014-03-01

225

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

226

The Salt Fluxes in a Tidally-Energetic Estuary  

Science.gov (United States)

Time series measurements of velocity and salinity have been used to examine the salt flux components in the tidally-energetic regime of the Conwy Estuary in North Wales. The instantaneous volume transport, up to 400 m 3 s -1, was deduced from a current meter located in mid-channel using a frictional model with a correction for the observed mean velocity shear. Transport estimates obtained in this way have been compared with independent measurements of integrated cross-section transport using a boat-mounted ADCP. The two determinations of the flow are found to be in satisfactory agreement confirming the validity of the frictional model. Estimates of the covariance of the tidally varying transport Q tand salinity S tindicate that a consistently upstream transport of salt occurred over the 9 day period of the observations. This upstream tidal pumping flux (?60 kg s -1) was greater than the downstream transport (?27 kg s -1) estimated from the freshwater river discharge Q f(?3 m 3 s -1). The difference in the salt fluxes implies a net upstream movement of salt and was consistent in sign with the observed general increase in mean salinity which occurred in the upper estuary prior to a rapid salinity decrease due to a large increase in freshwater discharge at the end of the measurement period. The observations have been interpreted to illustrate the problems involved in trying to determine the net flux of a dissolved constituent from such as estuary. Using estimates of the net inflow from river gauging to determine the volume discharge Q0 , estimates of the net flux are realistic but, in the absence of river gauging, large errors are likely to arise from the uncertainties in Q0, which is the small difference between large flood and ebb transports.

Simpson, J. H.; Vennell, R.; Souza, A. J.

2001-01-01

227

Application of microwave radiometers for wetlands and estuaries monitoring  

International Nuclear Information System (INIS)

This paper presents the examples of experimental data obtained with airborne microwave radiometers used for monitoring of wetlands and estuaries located in coastal environments. The international team of researchers has successfully worked in Russia, Ukraine and USA. The data presented relate to a period of time between 1990 and 1995. They have been collected in Odessa Region, Black Sea coast, Ukraine, in Regions of Pittsville and Winfield, Maryland, USA, and in Region of St. Marks, Florida, USA. The parameters discussed are a soil moisture, depth to a shallow water table, vegetation index, salinity of water surface

228

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

229

The risk of harmful algal blooms (HABs) in the oyster-growing estuaries of New South Wales, Australia.  

Science.gov (United States)

The spatial and temporal variability of potentially harmful phytoplankton was examined in the oyster-growing estuaries of New South Wales. Forty-five taxa from 31 estuaries were identified from 2005 to 2009. Harmful species richness was latitudinally graded for rivers, with increasing number of taxa southward. There were significant differences (within an estuary) in harmful species abundance and richness for 11 of 21 estuaries tested. Where differences were observed, these were predominately due to species belonging to the Pseudo-nitzschia delicatissima group, Dinophysis acuminata, Dictyocha octonaria and Prorocentrum cordatum with a consistent upstream versus downstream pattern emerging. Temporal (seasonal or interannual) patterns in harmful phytoplankton within and among estuaries were highly variable. Examination of harmful phytoplankton in relation to recognised estuary disturbance measures revealed species abundance correlated to estuary modification levels and flushing time, with modified, slow flushing estuaries having higher abundance. Harmful species richness correlated with bioregion, estuary modification levels and estuary class, with southern, unmodified lakes demonstrating greater species density. Predicting how these risk taxa and risk zones may change with further estuary disturbance and projected climate warming will require more focused, smaller scale studies aimed at a deeper understanding of species-specific ecology and bloom mechanisms. Coupled with this consideration, there is an imperative for further taxonomic, ecological and toxicological investigations into poorly understood taxa (e.g. Pseudo-nitzschia). PMID:23111868

Ajani, Penelope; Brett, Steve; Krogh, Martin; Scanes, Peter; Webster, Grant; Armand, Leanne

2013-06-01

230

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 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

231

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

232

Southwest British Columbia natural gas supply and deliverability: Discussion paper  

International Nuclear Information System (INIS)

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

233

Spice: Southwest Pacific Ocean Circulation and Climate Experiment  

Science.gov (United States)

South Pacific oceanic waters are carried from the subtropical gyre centre in the westward flowing South Equatorial Current (SEC), towards the southwest Pacific-a major circulation pathway that redistributes water from the subtropics to the equator and Southern Ocean. The transit in the Coral Sea is potentially of great importance to tropical climate prediction because changes in either the temperature or the amount of water arriving at the equator have the capability to modulate ENSO and produce basin-scale climate feedbacks. The south branch is associated with comparable impacts in the Tasman Sea area. The Southwest Pacific is a region of complex circulation, with the SEC splitting in strong zonal jets upon encountering island archipelagos. Those jets partition on the Australian eastern boundary to feed the East Australian Current for the southern branch and the North Queensland Current and eventually the Equatorial Undercurrent for the northern branch. On average, the oceanic circulation is driven by the Trade Winds, and subject to substantial variability, related with the South Pacific Convergence Zone (SPCZ) position and intensity. The circulation, and its influence on remote and regional climate, is poorly understood due to the lack of appropriate measurements. Ocean and atmosphere scientists from Australia, France, New Zealand, the United States and Pacific Island countries initiated an international research project under the auspices of CLIVAR to comprehend the southwest Pacific Ocean circulation and its direct and indirect influence on the climate and environment. SPICE is a regionally-coordinated experiment to measure, study and monitor the ocean circulation and the SPCZ, to validate and improve numerical models, and to integrate with assimilating systems. This ongoing project reflects a strong sense that substantial progress can be made through collaboration among South Pacific national research groups, coordinated with broader South Pacific projects.

Ganachaud, A. S.; Melet, A.; Maes, C.

2010-12-01

234

Data report for the Southwest Residential Experiment Station, January 1982  

Energy Technology Data Exchange (ETDEWEB)

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

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

1982-02-23

235

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.

236

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

237

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

238

Modeling residual circulation and stratification in Oujiang River estuary  

Science.gov (United States)

A 3D, time-dependent, baroclinic, hydrodynamic and salinity model was implemented and applied to the Oujiang River estuarine system in the East China Sea. The model was driven by the forcing of tidal elevations along the open boundaries and freshwater inflows from the Oujiang River. The bottom friction coefficient and vertical eddy viscosity were adjusted to complete model calibration and verification in simulations. It is demonstrated that the model is capable of reproducing observed temporal variability in the water surface elevation and longitudinal velocity, presenting skill coefficient higher than 0.82. This model was then used to investigate the influence of freshwater discharge on residual current and salinity intrusion under different freshwater inflow conditions in the Oujiang River estuary. The model results reveal that the river channel presents a two-layer structure with flood currents near the bottom and ebb currents at the top layer in the region of seawater influenced on north shore under high river flow condition. The river discharge is a major factor affecting the salinity stratification in the estuarine system. The water exchange is mainly driven by the tidal forcing at the estuary mouth, except under high river flow conditions when the freshwater extends its influence from the river's head to its mouth.

Lin, Wei-bo; Wang, Yi-gang; Ruan, Xiao-hong; Xu, Qun

2012-06-01

239

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

240

Environmental flow assessments in estuaries related to preference of phytoplankton  

Directory of Open Access Journals (Sweden)

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

Z. F. Yang

2014-01-01

 
 
 
 
241

A trace element study in the Thames estuary  

International Nuclear Information System (INIS)

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

242

Caspian Rapid Sea Level Changing Impact on Estuaries Morphodynamic Deformation  

Directory of Open Access Journals (Sweden)

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

Homayoun Khoshravan

2013-07-01

243

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

244

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 available field data into account and using Delf3D numerical models, the present study has firstly contended with the hydrodynamic modeling of the estuary; and regarding the obtained hydrodynamic conditions, it has then conducted a two-dimensional modeling of pollution dispersion in the region. The results show that the dispersion of pollution in the cross-sectional area of the estuary has had a rising trend whose concentration gradient does not decline over time. With water flows advancing from the mouth of the estuary toward its end, the dispersion and transfer of pollutant particles will decrease due to the reduction in the range of tidal fluctuations. With releasing pollutant particles in the estuary momentarily, they will gradually leave the estuary through an oscillatory motion over time, being transported to the west of the Persian Gulf and endangering the environment in the west coasts of Bandar Abbas.

Arefe Emami

2013-01-01

245

Ecological condition of US Mid-Atlantic estuaries, 1997-1998.  

Science.gov (United States)

The Mid-Atlantic Integrated Assessment (MAIA-Estuaries) evaluated ecological conditions in US Mid-Atlantic estuaries during the summers of 1997 and 1998. Over 800 probability-based stations were monitored in four main estuarine systems--Chesapeake Bay, the Delaware Estuary, Maryland and Virginian coastal bays, and the Albemarle-Pamlico Estuarine System. Twelve smaller estuaries within the four main systems were also assessed to establish variance at the local scale. A subset of the MAIA-Estuaries data is used here to estimate the extent of eutrophication, sediment contamination, and benthic degradation in mid-Atlantic estuaries. An Environmental Report Card and Index of Environmental Integrity summarize conditions in individual estuaries, the four estuarine systems, and the entire MAIA region. Roughly 20-50% of the region showed signs of eutrophication (high nutrients, excessive production of organic matter, poor water clarity, or depleted dissolved oxygen), 30% had contaminated sediments, and 37% had degraded benthic communities. Compared with the Environmental Monitoring and Assessment Program (EMAP)-Virginian Province study in 1990-1993, larger fractions of Chesapeake Bay (17%) and Delaware River (32%) had increased metals or organics in sediments. PMID:14550336

Kiddon, John A; Paul, John F; Buffum, Harry W; Strobel, Charles S; Hale, Stephen S; Cobb, Donald; Brown, Barbara S

2003-10-01

246

Testing a 1-D Analytical Salt Intrusion Model and the Predictive Equation in Malaysian Estuaries  

Science.gov (United States)

Little is known about the salt intrusion behaviour in Malaysian estuaries. Study on this topic sometimes requires large amounts of data especially if a 2-D or 3-D numerical models are used for analysis. In poor data environments, 1-D analytical models are more appropriate. For this reason, a fully analytical 1-D salt intrusion model, based on the theory of Savenije in 2005, was tested in three Malaysian estuaries (Bernam, Selangor and Muar) because it is simple and requires minimal data. In order to achieve that, site surveys were conducted in these estuaries during the dry season (June-August) at spring tide by moving boat technique. Data of cross-sections, water levels and salinity were collected, and then analysed with the salt intrusion model. This paper demonstrates a good fit between the simulated and observed salinity distribution for all three estuaries. Additionally, the calibrated Van der Burgh's coefficient K, Dispersion coefficient D0, and salt intrusion length L, for the estuaries also displayed a reasonable correlations with those calculated from the predictive equations. This indicates that not only is the salt intrusion model valid for the case studies in Malaysia but also the predictive model. Furthermore, the results from this study describe the current state of the estuaries with which the Malaysian water authority in Malaysia can make decisions on limiting water abstraction or dredging. Keywords: salt intrusion, Malaysian estuaries, discharge, predictive model, dispersion

Gisen, Jacqueline Isabella; Savenije, Hubert H. G.

2013-04-01

247

Interaction between suspended sediment and tidal amplification in the Guadalquivir Estuary  

Science.gov (United States)

Water level records at two stations in the Guadalquivir Estuary (Spain), one near the estuary mouth (Bonanza) and one about 77 km upstream (Sevilla), have been analysed to study the amplification of the tide in the estuary. The tidal amplification factor shows interesting temporal variation, including a spring-neap variation, some extreme low values, and especially the anomalous behaviour that the amplification factor is larger during a number of periods. These variations are explained by data analysis combined with numerical and analytical modelling. The spring-neap variation is due to the quadratic relation between the bottom friction and the tidal flow velocity. The river flood events are the direct causes of the extreme low values of the amplification factor, and they trigger the non-linear interaction between the tidal flow and suspended sediment transport. The fluvial sediment input during a river flood causes high sediment concentration in the estuary, up to more than 10 g/l. This causes a reduction of the effective hydraulic drag, resulting in stronger tidal amplification in the estuary for a period after a river flood. After such an event the tidal amplification in the estuary does not always fall back to the same level as before the event, indicating that river flood events have significant influence on the long-term development of this estuary.

Wang, Zheng Bing; Winterwerp, Johan C.; He, Qing

2014-10-01

248

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

DEFF Research Database (Denmark)

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

Stedmon, Colin A.; Markager, Stiig

2006-01-01

249

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

Science.gov (United States)

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

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

2010-12-01

250

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

International Nuclear Information System (INIS)

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

251

Impact of solid discharges from coal usage in the Southwest.  

Science.gov (United States)

The Southwestern region of the United States is extremely wealthy in low sulfur coal resources which must be eventually utilized in response to national energy balance priorities. Fly ash and scrubber sludge can be safely disposed of using properly managed techniques to ensure that any potential impact from elements such as boron, molybdenum, or selenium is rendered insignificant. Alternative methods of solids utilization are presently being developed. Fly ash is presently being marketed commercially as an additive for concrete manufacture. Successful experiments have been completed to demonstrate the manufacture of commercial-grade wallboard from scrubber sludge. Also, greenhouse studies and field experiments have been conducted to demonstrate increased yields of selected crops grown on typical soils amended with fly ash in amounts ranging from 2% to 8%, by weight. These studies also indicate that barium and strontium may be good monitoring indices for determining atmospheric deposition of fly ash, due to their concentration ratios in soil and vegetation samples. Further studies are being conducted to confirm encouraging irrigation and crop-yield data obtained with fly ash amended soils. Finally, the composition of many fly ashes and soils are similar in the Southwest, and there are no anticipated solid discharges from coal usage which cannot be rendered insignificant with proper management of existing and emerging methods of treatment. Compared with the water availability impact of coal usage in the Southwest, the impact of solid waste discharges are insignificant. PMID:738243

Jones, D G; Straughan, I R

1978-12-01

252

The Southwest Residential Experiment Station - The first year  

Science.gov (United States)

A history and status report on the Southwest Residential Experiment Station (SW RES) aimed at instituting residential applications of prototype residence-like photovoltaic systems is given. The three-acre SW RES site has an average annual insolation of 2375 kwhr/sq m, one of the highest in the United States. The eight prototypes under construction are aimed at suitability for the meteorological, cultural, and economic climates of the southwest, design compatibility with residence design with maintenance for one year after turnkey, and a minimum 100 W preproduction module. Useful information resulting from the program includes the redirection of a 4 kW array reducing costs by a factor of 20, awareness of the interference of Spring winds in handling modules larger than 1 ft x 4 ft, and the fact that white aggregate roofing gravel, south of an optimally tilted array, enhances array performance. In addition, each prototype is instrumented for performance monitoring and is equipped with a residential load simulator capable of dissipating from 0 to 26 kW in 100 watt increments.

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

253

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

International Nuclear Information System (INIS)

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

254

78 FR 64264 - Receipt of Noise Compatibility Program and Request for Review; Southwest Florida International...  

Science.gov (United States)

...International Airport were in compliance with applicable requirements...for Southwest Florida International Airport which will...found by FAA to be in compliance with the requirements...to reduce existing non-compatible uses and...for Southwest Florida International Airport,...

2013-10-28

255

Formative Assessment Policies, Programs, and Practices in the Southwest Region. Issues & Answers. REL 2008-No. 041  

Science.gov (United States)

This study examines evidence about state- and district-level formative/diagnostic policies, programs, and practices of states in the Regional Educational Laboratory Southwest (REL Southwest). Using case study methodology and data collected through document analyses and interviews with state- and district-level representatives, researchers compared…

Gallagher, Carole; Worth, Peter

2008-01-01

256

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

Energy Technology Data Exchange (ETDEWEB)

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

Tsusue, Akio; Mizuta, Toshio [Kumamoto Univ. (Japan). Faculty of Science; Tamai, Tadaharu

1994-07-01

257

75 FR 65401 - Public Notice for Waiver of Aeronautical Land-Use Assurance; Oakland/Southwest Airport; New...  

Science.gov (United States)

...TRANSPORTATION Public Notice for Waiver of Aeronautical Land-Use Assurance; Oakland/Southwest...portion of the Oakland/Southwest Airport from aeronautical use to non-aeronautical use and to authorize the sale of the...

2010-10-22

258

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. ...

259

Simulation of water quality and plankton dynamics in the Danshuei River estuary, Taiwan.  

Science.gov (United States)

An ecosystem model was developed to simulate the water quality and plankton dynamics in the Danshuei River estuary, Taiwan. The model simulates the hydrodynamics with a laterally integrated 2-dimensional intratidal numerical model, which supplies the physical transport processes for simulation of water quality and plankton state variables. The application of the model to the Danshuei River estuary indicates that the point source loadings are mainly responsible for the degraded water quality and very high nutrient concentrations in the estuary. The impacts of wastewater discharges are tightly controlled by the transport processes. Frequent occurrence of high river flow and flood events rapidly cleanses the estuary by flushing out both pollutants and plankton populations. The plankton is allowed to grow to significant populations if low river flow lasts for a period much longer than the biological time scale. PMID:17558774

Wang, Chi-Fang; Hsu, Ming-Hsi; Liu, Wen-Cheng; Hwang, Jiang-Shiou; Wu, Jiunn-Tzong; Kuo, Albert Y

2007-06-01

260

Pollution History of the Savannah Estuary. National Status and Trends Program for Marine Environmental Quality.  

Science.gov (United States)

Dated cores collected from different sites in the Savannah Estuary were analyzed for 16 metals, 22 polycyclic aromatic hydrocarbons (PAH), 20 polychlorinated biphenyls (PCB) congeners, 16 pesticides and 3 butylins. Time stratigraphy of the cores were dete...

C. Alexander, J. Ertel, R. Lee, B. Loganathan, J. Martin, R. Smith, S. Wakeham, H. Windom

1997-01-01

 
 
 
 
261

Sediment-water distribution of perfluorooctane sulfonate (PFOS) in Yangtze River Estuary  

International Nuclear Information System (INIS)

Analysis of Perfluorooctane sulfonate (PFOS) distribution in water and sediment in Yangtze River Estuary showed that the estuary was a sink for PFOS. Salinity was an important parameter in controlling the sediment-water interactions and the fate or transport of PFOS in the aquatic environment. As the salinity (S per mille ) increased from 0.18 to 3.31, the distribution coefficient (Kd) between sediment and water linearly increased from 0.76 to 4.70 L g-1. The study suggests that PFOS may be carried with the river water and transported for long distances before it reaches to the sea and largely scavenged to the sediment in the estuaries due to the dramatic change in salinity. - PFOS may be largely scavenged to the sediment in estuaries due to the dramatic change in salinity during its transport from lands to oceans.

262

Sediment-water distribution of perfluorooctane sulfonate (PFOS) in Yangtze River Estuary  

Energy Technology Data Exchange (ETDEWEB)

Analysis of Perfluorooctane sulfonate (PFOS) distribution in water and sediment in Yangtze River Estuary showed that the estuary was a sink for PFOS. Salinity was an important parameter in controlling the sediment-water interactions and the fate or transport of PFOS in the aquatic environment. As the salinity (S per mille ) increased from 0.18 to 3.31, the distribution coefficient (K{sub d}) between sediment and water linearly increased from 0.76 to 4.70 L g{sup -1}. The study suggests that PFOS may be carried with the river water and transported for long distances before it reaches to the sea and largely scavenged to the sediment in the estuaries due to the dramatic change in salinity. - PFOS may be largely scavenged to the sediment in estuaries due to the dramatic change in salinity during its transport from lands to oceans.

Pan Gang, E-mail: gpan@rcees.ac.c [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); You Chun [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China)

2010-05-15

263

From headwaters to coast: influence of human activities on water quality of the Potomac River Estuary  

Science.gov (United States)

The natural aging process of Chesapeake Bay and its tributary estuaries has been accelerated by human activities around the shoreline and within the watershed, increasing sediment and nutrient loads delivered to the bay. Riverine nutrients cause algal growth in the bay leading to reductions in light penetration with consequent declines in sea grass growth, smothering of bottom-dwelling organisms, and decreases in bottom-water dissolved oxygen as algal blooms decay. Historically, bay waters were filtered by oysters, but declines in oyster populations from overfishing and disease have led to higher concentrations of fine-sediment particles and phytoplankton in the water column. Assessments of water and biological resource quality in Chesapeake Bay and tributaries, such as the Potomac River, show a continual degraded state. In this paper, we pay tribute to Owen Bricker’s comprehensive, holistic scientific perspective using an approach that examines the connection between watershed and estuary. We evaluated nitrogen inputs from Potomac River headwaters, nutrient-related conditions within the estuary, and considered the use of shellfish aquaculture as an in-the-water nutrient management measure. Data from headwaters, nontidal, and estuarine portions of the Potomac River watershed and estuary were analyzed to examine the contribution from different parts of the watershed to total nitrogen loads to the estuary. An eutrophication model was applied to these data to evaluate eutrophication status and changes since the early 1990s and for comparison to regional and national conditions. A farm-scale aquaculture model was applied and results scaled to the estuary to determine the potential for shellfish (oyster) aquaculture to mediate eutrophication impacts. Results showed that (1) the contribution to nitrogen loads from headwater streams is small (about 2 %) of total inputs to the Potomac River Estuary; (2) eutrophic conditions in the Potomac River Estuary have improved in the upper estuary since the early 1990s, but have worsened in the lower estuary. The overall system-wide eutrophication impact is high, despite a decrease in nitrogen loads from the upper basin and declining surface water nitrate nitrogen concentrations over that period; (3) eutrophic conditions in the Potomac River Estuary are representative of Chesapeake Bay region and other US estuaries; moderate to high levels of nutrient-related degradation occur in about 65 % of US estuaries, particularly river-dominated low-flow systems such as the Potomac River Estuary; and (4) shellfish (oyster) aquaculture could remove eutrophication impacts directly from the estuary through harvest but should be considered a complement—not a substitute—for land-based measures. The total nitrogen load could be removed if 40 % of the Potomac River Estuary bottom was in shellfish cultivation; a combination of aquaculture and restoration of oyster reefs may provide larger benefits.

Bricker, Suzanne B.; Rice, Karen C.; Bricker, Owen P., III

2014-01-01

264

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

265

Heavy metals in surface sediments from nine estuaries along the coast of Bohai Bay, Northern China.  

Science.gov (United States)

Concentrations of heavy metals in river water and sediment were investigated in nine estuaries along the coast of Bohai Bay, Northern China. Multivariate statistical techniques such as principal component analysis and cluster analysis, in combination with metal concentration analysis and correlation analysis, were used to identify the possible sources of the metals and the pollution pattern in nine estuaries along the coast of Bohai Bay. The environmental risks of metals, evaluated by sediment quality guidelines and background values, revealed Hg contamination in the estuaries. However, levels of Cd in estuarine sediments were low, and they were less than those levels in river sediments, partly due to the high mobility and dilution of river or seawater. Cd did not contribute to sediment deposits in estuaries. High organic matter from effluents from large municipal sewage treatment plants was predominantly responsible for restricting Hg mobility from the river to Bohai Bay. PMID:24650542

Wu, Guanghong; Shang, Jingmin; Pan, Ling; Wang, Zhongliang

2014-05-15

266

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

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

Drago Maguš

2009-10-01

267

Plutonium, radiocesium and radiocobalt in sediments of the Hudson River estuary  

International Nuclear Information System (INIS)

Anthropogenic radionuclides have reached the Hudson estuary as global fallout from nuclear weapons testing and through local releases from commercial nuclear reactors. Significant activities of 238Pu and 239,240Pu (fallout-derived), 134Cs and 60Co (reactor-released), and 137Cs (derived from both sources), have accumulated in the sediments throughout the estuary, with the primary zone of accumulation near the downstream end of the system in New York harbor. The estuary appears to have trapped nearly all of the 239,240Pu delivered as fallout, and consequently, ocean dumping of dredged harbor sediment is currently the primary means for the net transport of these nuclides to coastal waters. In contrast, only 10-30% of the 137Cs, 134Cs and 60Co delivered to the estuary have been retained on the fine particles which accumulate at a rapid rate in the harbor. (orig./HAE)

268

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

269

Sea fishes spawning pelagic eggs in the St Lucia estuary  

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Full Text Available During September 1993, after the St Lucia estuary had beendosed to the sea for about nine months, two samples of liveplankton were collected at the mouth inside the closedestuary. Fish eggs from these samples were hatched andidentified by the characteristics of the eggs and early larvae.Pomadasys commersonnii and Crenidens crenidens werereared to confirm identification. Eggs of nine species werefound and all but one were identified to at least genus level.The unidentified egg was probably that of a dupeiform, andthe most common egg was the spotted grunter Pomadasyscommersonnii. Subsequent sampling in the Charters Creekarea in 1994 confirmed that five of the species also spawn inthe main lake, while a further species was added to the list ofmarine fishes that will spawn in St Lucia given favourableconditions.

A.D. Connell

2011-08-01

270

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

271

Turbulent nitrate fluxes near a sill in a large estuary  

Science.gov (United States)

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

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

2014-05-01

272

Primary fish survey in the Huanghe River estuary  

Science.gov (United States)

The survey in the Huanghe River estuary indicated that the 85 fish species found there comprised three faunal elements: warm-water species (29.4%), warm-temperate species (55.3%) and cold-temperate species (15.3%). The seasonal changes of fish species, density and biomass are obvious. The total biomass is highest (7 699t) in August and lowest (489 t) in January. Setipinna taty has mean density of 9 278 indiv/km2, and is the most important species constituting 25.5% of the total weight of fish caught. Trichiurus haumela was a dominant species in the 1950s, but no one was caught in this survey. There were obvious changes of the dominant fish species during the recent three decades. The demersal fish biomass has dropped greatly to only 1/10 in over 50 years since 1930.

Yang, Jiming; Wang, Cunxin

1993-12-01

273

Nutrient budgets for large Chinese estuaries and embayment  

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

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

S. M. Liu

2009-01-01

274

76 FR 1501 - Preparation of Environmental Impact Statement for Transit Improvements in the US 90A/Southwest...  

Science.gov (United States)

...for Transit Improvements in the US 90A/Southwest Rail Corridor...Department of Transportation (DOT). ACTION: Notice of Intent...proposed transit improvements in the US 90A/Southwest Rail corridor...area (Harris County). The US 90A/Southwest Rail...

2011-01-10

275

Spatial distribution and general population characteristics of mysid shrimps in the Westerschelde estuary (SW Netherlands)  

Science.gov (United States)

The distribution and general population characteristics of five mysid shrimps were investigated in the period 2003-2005 in the Westerschelde estuary, a tidal temperate estuary situated along the Dutch-Belgian border. Multivariate analyses revealed that salinity predominantly governs the spatial distribution of Neomysis integer, Gastrosaccus spinifer, Schistomysis kervillei and Schistomysis spiritus while temperature, and to a lesser extent turbidity, control the distribution of Mesopodopsis slabberi. N. integer is a resident species in the mesohaline zone of the estuary, i.e. all life stages of the species are present in the estuary throughout the year. For the first time since decades N. integer inhabits the oligohaline zone of the estuary supposedly as a consequence of improved oxygen conditions in the upstream reaches. M. slabberi, the most abundant mysid in the Westerschelde, dominates the hyperbenthos of the mesohaline zone of the estuary. The polyhaline zone of the estuary is, most abundantly inhabited by M. slabberi, G. spinifer, S. kervillei and to a lesser extent by S. spiritus. The abundance of the latter four species is low in winter, probably due to a migration towards coastal waters to avoid colder temperatures in the estuary combined with an increased mortality after breeding. The sex ratio of all the mysid populations corresponds to the expected 1:1 female:male ratio and no salinity governed segregation is found between the different life stages of each mysid population. A seasonal variation exists in brood size in the N. integer population regardless of the body size, with a larger number of broods during winter and spring compared to the summer. In the other mysid populations the brood sizes vary only with the length of the ovigerous females. Our recent observations underline some general characteristics of mysid populations in the Westerschelde and provide novel insights in their life stage and sex specific population segregation, their brood sizes and the expanding upstream distribution of N. integer.

Rappé, Karen; Fockedey, Nancy; Van Colen, Carl; Cattrijsse, Andre; Mees, Jan; Vincx, Magda

2011-01-01

276

Heavy metal anomalies in the Tinto and Odiel River and estuary system, Spain  

Science.gov (United States)

The Tinto and Odiel rivers drain 100 km from the Rio Tinto sulphide mining district, and join at a 20-km long estuary entering the Atlantic Ocean. A reconnaissance study of heavy metal anomalies in channel sand and overbank mud of the river and estuary by semi-quantitative emission dc-arc spectrographic analysis shows the following upstream to downstream ranges in ppm (??g g-1): As 3,000 to heavy metals in the overbank clay throughout the river and estuary systems indicates the importance of suspended sediment transport for dispersing heavy metals from natural erosion and anthropogenic mining activities of the sulfide deposit. The organic-poor (0.21-0.37% TOC) river bed sand has been analyzed to represent bedload transport of naturally-occurring sulfide minerals. The sand has high concentrations of metals upstream but these decrease an order of magnitude in the lower estuary. Although heavy metal contamination of estuary mouth beach sand has been diluted to background levels estuary mud exhibits increased contamination apparently related to finer grain size, higher organic carbon content, precipitation of river-borne dissolved solids, and input of anthropogenic heavy metals from industrial sources. The contaminated estuary mud disperses to the inner shelf mud belt and offshore suspended sediment, which exhibit metal anomalies from natural erosion and mining of upstream Rio Tinto sulphide lode sources (Pb, Cu, Zn) and industrial activities within the estuary (Fe, Cr, Ti). Because heavy metal contamination of Tinto-Odiel river sediment reaches or exceeds the highest levels encountered in other river sediments of Spain and Europe, a detailed analysis of metals in water and suspended sediment throughout the system, and epidemiological analysis of heavy metal effects in humans is appropriate. ?? 1993 Estuarine Research Federation.

Nelson, C.H.; Lamothe, P.J.

1993-01-01

277

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

Science.gov (United States)

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

Robins, Peter Edward; Davies, Alan G.

2010-06-01

278

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

279

Estimating minimum environmental flow requirements for well-mixed estuaries in Spain  

Science.gov (United States)

Following the principles of the European Water Framework Directive, the current Spanish water management legislation requires the definition of the environmental flow regimes for all water bodies, including estuaries. The scientific community has tried to answer the question of how much freshwater an estuary needs since the mid-1970s, resulting in the development of several methodologies and approaches in different parts of the world. However the ability to reproduce most of these approaches is difficult due to the scarcity of required data and also to the differences between the studied estuaries. In this paper, we present a methodology to calculate environmental flow regimes in well-mixed estuaries based on the numerical modelling of salinity and which takes into account the seasonal climatic and hydrologic pattern of the catchment. The approach follows three sequential steps: 1) Definition of reference conditions based on the unaltered salinity patterns and zoning of the estuary, 2) definition of salinity thresholds and 3) calculation of the minimum flows required to satisfy these thresholds. The application of the methodology to five estuaries on the northern coast of Spain has highlighted the importance of considering the hydrological variability and the division of the estuary into homogeneous zones. Moreover, the studies carried out demonstrate the ineffectiveness of river specific methodologies when used to define environmental flow regimes in several estuaries and periods, and the need to apply specific methodologies. The methodology is based on the principles defined by other already tested approaches, but its greatest advantage lies in the ability to be applied to large scales, when physical and biological data is scarce.

Peñas, Francisco J.; Juanes, José A.; Galván, Cristina; Medina, Raúl; Castanedo, Sonia; Álvarez, César; Bárcena, Javier F.

2013-12-01

280

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

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Full Text Available 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-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 2000m$^{3}$/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 was expanded to cater for tidal damping. Subsequently the model was validated with observations made at fixed locations over the years 1998 and 1999. Finally it was tested whether the Mekong calibration fits the overall predictive equations derived in other estuaries. The test was successful and led to a slight adjustment of the predictive equation to cater for estuaries that experience a sloping bottom.

A. D. Nguyen

2006-04-01

 
 
 
 
281

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)

282

Assessing the dynamics of chromophoric dissolved organic matter in a subtropical estuary using parallel factor analysis  

DEFF Research Database (Denmark)

The spatial and temporal dynamics of chromophoric dissolved organic matter (CDOM) were studied using excitation emission matrix fluorescence spectroscopy (EEMs) and parallel factor analysis (PARAFAC) during five cruises in the subtropical Jiulong Estuary from August 2008 to June 2009. Two humic-like (C1 and C3), one tryptophan-like (C4) and one possible protein-like (C2) component was identified by PARAFAC and their behavior in the river–estuary–coastal interface was evaluated. The spatial distributions of the maximum fluorescence (Fmax) for the fluorescent components showed a remarkable loss in the upper estuary. The following significant addition of all components in the low salinity turbidity maximum zone suggested the inputs from riverine source, sediment resuspension and the surrounding mangrove ecosystem. C1, C2 and C3 showed conservative behavior in the middle and lower estuary indicated by the linear relationship between their fluorescence intensities and salinity in the five cruises. However, the tryptophan-like C4 received widespread additions (likely from autochthonous production) in the estuary. Although the humic-like C1 and C3 showed no significant variation in the estuary–coastal interface, C2 and C4 decreased more rapidly beyond this interface, indicating the significant influence of coastal current to this estuarine environment. The seasonal variation of tryptophan-like C4 was characterized by higher Fmax values in the upper to middle estuary in the dry season, which is in contrast to that of the humic-like C3. Correlation analysis with DOC showed that the fluorescence intensity of C1 (or C2 and C3) was suitable for tracing DOC dynamics in this estuary. These results indicated different mixing behavior and temporal variability for different fluorescent components in this dynamic estuarine environment.

Guo, Weidong; Yang, Liyang

2011-01-01

283

Bacterial and Phytoplankton Dynamics along a Trophic Gradient in a Shallow Temperate Estuary  

Science.gov (United States)

Heterotrophic bacterial and phytoplankton biomass, production, specific growth rates and growth efficiencies were studied from June to October in 1996 and from February to May in 1997 along the longitudinal axis of the Urdaibai Estuary, a shallow temperate tidal estuary. Both phytoplankton and bacterial biomass showed a distinct lower to upper estuary increasing gradient. Longitudinal variations of phytoplankton biomass were controlled mainly by inorganic nutrient availability and tidal flushing. Longitudinal variations of bacterial biomass were further influenced by allochthonous inputs of organic carbon from a wastewater treatment plant located at the upper estuary. On a temporal scale, the dilution and washout effect of river discharge was a major controlling factor of both bacterial and phytoplankton biomass in the upper estuary. In this zone there were no indications that bacteria were resource limited, and temperature was the variable that explained most of the variability in bacterial specific growth rates. In the lower estuary, however, data suggested bacteria were nitrogen limited. Likewise, phytoplankton growth rates also showed a positive correlation with inorganic nutrients in this area. Free-living bacteria were generally more abundant than attached ones all along the estuary. However, following the longitudinal gradient of turbidity, the proportion of attached bacteria increased from the lower to the upper estuary. Rates of thymidine incorporation per cell were generally higher for particle-attached bacteria than for free-living bacteria. On average, bacteria contributed only 23% of the phytoplankton plus bacterial carbon biomass. Bacterial contribution to total (bacterial plus phytoplankton) net production of organic carbon was on average 17% for surface samples and 39% for bottom samples. Average phytoplankton growth efficiency in the euphotic zone was estimated to be higher (85%) than bacterial growth efficiency (46%).

Revilla, M.; Iriarte, A.; Madariaga, I.; Orive, E.

2000-03-01

284

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

285

The Temperature and Salinity Variabilities at Cisadane Estuary  

Directory of Open Access Journals (Sweden)

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

Hadikusumah

2008-11-01

286

Rare earth element analysis indicates micropollutants in an urban estuary  

Science.gov (United States)

Rare earth element analysis of Bayou Bienvenue waters shows anomalously high gadolinium, Gd, concentrations relative to its nearest neighbors in the REE series, europium and terbium. The anomalously high Gd concentrations indicate anthropogenic input from waste-water treatment plants in the area as anthropogenic Gd input can be traced back to its use as a contrast agent in magnetic resonance imaging in hospitals. Others have shown that anomalously high levels of Gd in natural waters are likely to be associated with other micropollutants that also occur in hospital effluent and that are not removed in the wastewater treatment process, including pharmaceuticals in the form of steroids, antihistamines, and antibiotics. Estuaries serve as many important ecological roles and have been shown to act as a filter for pollutants. To better understand the transport, biogeochemical cycling, and ultimate fate of trace elements in estuaries, I collected surface water samples from Bayou Bienvenue, a wetland triangle that covers an area of 427 acres directly adjacent to New Orleans, Louisiana. Water samples from Bayou Bienvenue were collected along the salinity gradient and subsequently filtered through progressively smaller pore-size filters. The resulting fractions were analyzed for trace element concentions, including the REEs, by magnetic sector ICP-MS. The attached figure shows the Gd anomaly present in the particulate (>0.45?m) fraction. Upper continental crust (UCC)-normalized plots of colloidal REEs (0.02?m - 0.45?m) fraction is lacking this anomaly indicating anthropogenic Gd is found chiefly in the particulate fraction in Bayou Bienvenue. No clear relationship between Gd concentration and salinity was apparent.

Mohajerin, T. J.; Johannesson, K. H.; Kolker, A.; Burdige, D. J.; Chevis, D.

2011-12-01

287

Phytoplankton abundance and pigment biomarkers in the oligotrophic, eastern Adriatic estuary.  

Science.gov (United States)

Phytoplankton distribution and environmental characteristics were determined in a shallow, highly stratified and oligotrophic estuary (Zrmanja, eastern Adriatic). Samples were collected in two contrasting seasons; winter (February 2000), when river discharge was high, and in summer (July 2003), a period of drought. Phytoplankton distribution was closely related to salinity gradients, nutrient levels, and water residence time. Microscopic analysis revealed that phytoplankton was composed mainly of marine diatoms, dinoflagellates, cryptophytes, green flagellates, and coccolithophorids. The dominant biomarker pigments were fucoxanthin, alloxanthin and 19'-hexanoyloxyfucoxanthin, while lower, but indicative contributions of peridinin and chlorophyll b were also noted. Maximum abundance and biomass were found in the middle estuary in winter and in the upper estuary in summer. The estuary is mostly P-limited. Development of chain-forming marine diatoms was evident in winter. Due to the reduced nutrient input in summer, the biomass accumulated in the upper estuary (1,000 ng chlorophyll a l(-1)) was composed mostly of nanoplanktonic unicellular diatoms, nanoplanktonic marine dinoflagellates, cryptophytes, and chlorophytes. The concentrations of about 200 ng l(-1) hex-fuco, suggested that the contribution of prymnesiophytes to total biomass was comparable to that of diatoms and dinoflagellates. In the middle estuary and coastal sea, PO(4) and TIN were 3.5 times lower, resulting in a fivefold decrease in biomass (<100 ng chlorophyll a l(-1)). The oligotrophic Zrmanja and other karstic rivers discharging in the eastern Adriatic Sea, provide insufficient source of nutrients and low productivity of the eastern Adriatic Sea. PMID:17879135

Vilici?, D; Terzi?, S; Ahel, M; Buri?, Z; Jasprica, N; Cari?, M; Caput Mihali?, K; Oluji?, G

2008-07-01

288

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

289

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

290

Anguilla rostrata glass eel migration and recruitment in the estuary and Gulf of St Lawrence.  

Science.gov (United States)

This study describes catches of Anguilla rostrata glass eels and associated oceanographic conditions in the St Lawrence Estuary and Gulf. Ichthyoplankton survey data suggest that they enter the Gulf primarily in May, migrate at the surface at night, and disperse broadly once they have passed Cabot Strait. They arrive in estuaries beginning at about mid-June and through the month of July. Migration extends west up to Québec City, in the freshwater zone of the St Lawrence Estuary, 1000 km west of Cabot Strait. Anguilla rostrata glass eels travel between Cabot Strait and receiving estuaries at a straight-line ground speed of c. 10-15 km day(-1). Catches of fish per unit effort in estuaries in the St Lawrence system are much lower than those reported for the Atlantic coast of Canada. Low abundance of A. rostrata glass eels in the St Lawrence system may be due to cold surface temperatures during the migration period which decrease swimming capacity, long distances from the spawning ground to Cabot Strait and from Cabot Strait to the destination waters (especially the St Lawrence River), complex circulation patterns, and hypoxic conditions in bottom waters of the Laurentian Channel and the St Lawrence Estuary. PMID:20735683

Dutil, J-D; Dumont, P; Cairns, D K; Galbraith, P S; Verreault, G; Castonguay, M; Proulx, S

2009-06-01

291

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

292

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

293

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

Science.gov (United States)

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

Sherwood, Edward T.; Greening, Holly S.

2014-02-01

294

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.

David A. Gauthier

1986-06-01

295

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

296

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

297

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

298

Data report for the Southwest Residential Experiment Station, February 1982  

Science.gov (United States)

Tabulated are physical performance data obtained from the photovoltaic energy systems under test at the Southwest Residential Experiment Station (SW RES) in Las Cruces, New Mexico for the month of February 1982. A one-page data summary is included as well as a more detailed hourly tabulation for an average day of the month. Energy histograms are provided for each prototype system. The histograms also present horizontal and plane-of-array insolation data as well as comments that explain data and/or energy production anomalies. Eight prototype residential PV systems are under test, each consisting of a roof-mounted PV array sized to meet at least 50% of the annual electric demand of an energy-conserving house, and an enclosed structure to house the remainder of the PV system equipment, test instrumentation, and work space. All systems are grid-connected.

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

1982-04-01

299

Bioclimatic factors affecting daily Cupressaceae flowering in southwest Spain  

Science.gov (United States)

Daily variations in Cupressaceae pollen counts were analysed, together with climatic variables in the southwest of Spain, in order to understand the bioclimatic variables affecting Cupressaceae flowering in a Mediterranean climate. The study was carried out using the Spanish Aerobiology Network recommendations, using a Burkard Hirst-type spore trap. Regression analyses were applied to the pollen counts of the winter months of 13 consecutive years. The regression analysis applied to each year indicated that temperature is the most important variable to include in the model. Temperature affected the pollen counts differently according to the yearly climatic trend. During the coldest years, pollen counts depended on the minimum temperature, while in the warmest ones they were affected by higher temperatures. However, during the driest years, pollen counts depended more on the humidity level, while in the wettest years they depended more on the hours of sunshine.

Galán, C.; Fuillerat, M. Jose; Comtois, Paul; Dominguez-Vilches, Eugenio

300

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.

 
 
 
 
301

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

302

Modeling local paleoclimates and validation in the southwest United States  

International Nuclear Information System (INIS)

In order to evaluate the spatial and seasonal variations of paleoclimate in the southwest US, a local climate model (LCM) is developed that computes modern and 18,000 yr B.P. (18 ka) monthly temperature and precipitation from a set of independent variables. Independent variables include: terrain elevation, insolation, CO2 concentration, January and July winds, and January and July sea-surface temperatures. Solutions are the product of a canonical regression function which is calibrated using climate data from 641 stations from AZ, CA, CO, NM, NV, UT in the National Weather Service Cooperative observer network. Validation of the LCH, using climate data at 98 climate stations from the period 1980--1984, indicates no significant departures of LCM solutions from climate data. LCM solutions of modern and 18 ka climate are computed at a 15 km spacing over a rectangular domain extending 810 km east, 360 km west, 225 km north and 330 km south of the approximate location of Yucca Mt., KV. Solutions indicate mean annual temperature was 5 degrees C cooler at 18 ka and mean annual precipitation increased 68%. The annual cycle of temperature and precipitation at 18 ka was amplified with summers about 1 degrees C cooler and 71% drier, and winters about 11 degrees C colder and 35% wetter than the modern. Model results compare quite reasonably with proxy paleoclimate estimates from glacial deposits, pluvial lake deposits, pollen records, ostracodes records and packrat maddcords, ostracodes records and packrat madden records from the southwest US However, bias (+5 degrees C to +10 degrees C) is indicated for LCM solutions of summer temperatures at 18 ka

303

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

304

Eutrophication Links between the Watershed and Estuary in the Neuse River Basin, NC  

Science.gov (United States)

The Neuse River drains into the Neuse River Estuary and Pamlico Sound, which is part of the second largest estuarine ecosystem in the United States and a key nursery for Mid and Southeast Atlantic fisheries. RiverNet, ModMon, and now FerryMon have monitored nutrient fluxes in the watershed and ecosystem responses in the estuary. Poor water quality in the 1980's led to a phosphorus ban in the basin that decreased P inputs to the watershed and improved water quality in the freshwater portions of the basin. High temporal resolution nutrient monitoring in the river indicates that significant flux variations are associated with point sources, and that N fluxes have been underestimated by previous monitoring efforts. N loss in the watershed is associated with hydric soils that are primarily located in the lower coastal plain. The 17O composition of nitrate suggests that Amospherically Deposited Nitrogen (A.D.N.) is event driven and is controlled by land use in the sub-basin. New regulations imposed by the State of NC are decreasing N fluxes in the watershed, but these fluxes are highly variable and controlled to some extent by extreme rainfall events that result from direct hurricane strikes and droughts. The greater decrease in P flux to the estuary compared to N flux (which has decreased slightly or remained the same) has reduced P-limited primary production in the freshwater upper portion of the estuary. This limits the N assimilation in this region, and allows more efficient N transport to N-sensitive coastal waters in the lower portion of the estuary. Chl a and phytoplankton pigment monitoring in the estuary indicate that site of the maximum primary productivity has moved form the upper estuary in the 1970's and 1980's to the lower estuary today. This displacement of the eutrophication gradient may explain the reduction of Cyanobacteria algae blooms in the upper estuary, and the increase in harmful algae blooms, hypoxia, and declines in fisheries habitats in the lower estuary. These findings underscore the need for basin scale nutrient reduction strategies that consider the entire freshwater-marine continuum, and the need for long term monitoring that take in account climatic and hydrological variability (i.e. hurricanes and droughts).

Showers, W. J.; Paerl, H. W.

2005-05-01

305

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

306

Pollutant fate and spatio-temporal variability in the choptank river estuary: factors influencing water quality.  

Science.gov (United States)

Restoration of the Chesapeake Bay, the largest estuary in the United States, is a national priority. Documentation of progress of this restoration effort is needed. A study was conducted to examine water quality in the Choptank River estuary, a tributary of the Chesapeake Bay that since 1998 has been classified as impaired waters under the Federal Clean Water Act. Multiple water quality parameters (salinity, temperature, dissolved oxygen, chlorophyll a) and analyte concentrations (nutrients, herbicide and herbicide degradation products, arsenic, and copper) were measured at seven sampling stations in the Choptank River estuary. Samples were collected under base flow conditions in the basin on thirteen dates between March 2005 and April 2008. As commonly observed, results indicate that agriculture is a primary source of nitrate in the estuary and that both agriculture and wastewater treatment plants are important sources of phosphorus. Concentrations of copper in the lower estuary consistently exceeded both chronic and acute water quality criteria, possibly due to use of copper in antifouling boat paint. Concentrations of copper in the upstream watersheds were low, indicating that agriculture is not a significant source of copper loading to the estuary. Concentrations of herbicides (atrazine, simazine, and metolachlor) peaked during early-summer, indicating a rapid surface-transport delivery pathway from agricultural areas, while their degradation products (CIAT, CEAT, MESA, and MOA) appeared to be delivered via groundwater transport. Some in-river processing of CEAT occurred, whereas MESA was conservative. Observed concentrations of herbicide residues did not approach established levels of concern for aquatic organisms. Results of this study highlight the importance of continued implementation of best management practices to improve water quality in the estuary. This work provides a baseline against which to compare future changes in water quality and may be used to design future monitoring programs needed to assess restoration strategy efficacy. PMID:20171715

Whitall, David; Hively, W Dean; Leight, Andrew K; Hapeman, Cathleen J; McConnell, Laura L; Fisher, Thomas; Rice, Clifford P; Codling, Eton; McCarty, Gregory W; Sadeghi, Ali M; Gustafson, Anne; Bialek, Krystyna

2010-04-01

307

Modeling tidal circulation and stratification in Skagit River estuary using an unstructured grid ocean model  

Science.gov (United States)

Tidal circulation and river plume dynamics in shallow-water estuarine systems with large intertidal zones are complex. Strong asymmetries in tidal currents and stratification often occur in the intertidal zones and subtidal channels over a tidal cycle. The Skagit River is the largest estuary with respect to the discharge of a significant amount of freshwater and sediment into Puget Sound, Washington. It consists of a large intertidal zone with multiple tidal channels near the mouth of the estuary. To simulate the tidal circulation and salinity stratification accurately in the intertidal region, an unstructured grid numerical model with wetting-drying capability and the capability to accurately represent the bathymetry of tidal flats and the geometry of shallow distributary channels is necessary. In this paper, a modeling study for the Skagit River estuary using a three-dimensional unstructured grid, finite-volume coastal ocean model (FVCOM) supported by high-resolution LIDAR data is presented. The hydrodynamic model was validated with observed water surface elevation, velocity, and salinity data over spring and neap tidal cycles under low-river-flow and high-river-flow conditions. Wetting and drying processes in the intertidal zone and strong stratification in the estuary were simulated successfully by the model. Model results indicate that the Skagit River estuary is a highly stratified estuary, but destratification can occur during flood tide. Tides and baroclinic motion are the dominant forcing in the Skagit River estuary, but strong wind events can affect the currents in the intertidal zone significantly. Preliminary analysis also indicated that the salinity intrusion length scale is proportional to the river flow to the -¼ power.

Yang, Zhaoqing; Khangaonkar, Tarang

308

Tidal sediment transport versus freshwater flood events in the Konkouré Estuary, Republic of Guinea  

Science.gov (United States)

In comparison to their temperate counterparts, sediment processes in tropical estuaries are poorly known and especially in African ones. The hydrodynamics of such environments is controlled by a combination of multiple processes including morphology, salinity, mangrove vegetation, tidal processes, river discharge, settling and erosion of mud and by physico-chemical processes as well as sediment dynamics. The aim of this study is to understand the sediment processes in this transitional stage of the estuary when the balance between river discharges and marine processes is reversing. Studying the hydrodynamics and sediment dynamics of the Konkouré Estuary has recently been made possible thanks to new data on bathymetry, sedimentary cover, salinity, water elevations, and current velocities. The Lower Konkouré is a shallow, funnel shaped, mesotidal mangrove-fringed, tide-dominated estuary, well mixed during low river discharge and stratified during high river discharge. The Konkouré Estuary is turbid despite the small amount of terrestrial input and its residual velocity at the mouth during low river discharges, landwards for two of the three branches, suggests a landward migration by tidal pumping of the suspended particulate matter. A Turbidity Maximum Zone (TMZ) is identified for typical states of the estuary with regard to fluvial and tidal components. Suspended sediment transport during a transitional stage between the rainy and dry seasons is known thanks to current velocity and Suspended Sediment Concentration (SSC) measurements taken in November 2003. The Richardson layered number calculation assesses that turbulence is the major mixing process in the water column, at least during the flood and ebb stages, whereas stratification occurs during the slack water periods. Tidal currents generate bottom erosion, and turbulence mixes the suspended sediment throughout the water column. As a result, a net sediment input is calculated from the western Konkouré outlet for two consecutive tidal cycles. Despite the net water export, almost 300 tons per tide reach the estuary through this outlet, for a moderate river flow.

Capo, Sylvain; Brenon, Isabelle; Sottolichio, Aldo; Castaing, Patrice; Le Goulven, Patrick

2009-09-01

309

Present nitrogen and carbon dynamics in the Scheldt estuary using a novel 1-D model  

Directory of Open Access Journals (Sweden)

Full Text Available A 1-D, pelagic, reactive-transport model of a completely mixed, turbid, heterotrophic estuary – the Scheldt estuary – is presented. The model resolves major carbon and nitrogen species and oxygen, as well as pH. The model features two organic matter degradation pathways, oxic mineralisation and denitrification, and includes primary production as well as nitrification. Apart from advective-dispersive transport along the length axis, the model also describes O2, CO2, and N2 air-water exchange. The aim of this study is to present a model which is as simple as possible but still fits the data well enough to determine the fate and turnover of nutrients entering the estuary and their spatial patterns in the years 2000 to 2004. Nitrification is identified as one of the most important processes in the estuary, consuming a comparable amount of oxygen as oxic mineralisation (1.7 Gmol O2 y?1 vs. 2.7 Gmol O2 y?1. About 10% of the 2.5 Gmol of nitrogen entering the estuary per year is lost within the estuary due to denitrification. Nitrogen and carbon budgets are compared to budgets from the seventies and eighties, showing that nitrification activity has peaked in the eighties, while denitrification steadily declined. Our model estimates an average CO2 emission of 3.3 Gmol y?1 in the years 2001 to 2004, which is a comparatively low estimate in the context of previous estimates of CO2 export from the Scheldt estuary.

A. F. Hofmann

2008-07-01

310

Polychaete Richness and Abundance Enhanced in Anthropogenically Modified Estuaries Despite High Concentrations of Toxic Contaminants  

Science.gov (United States)

Ecological communities are increasingly exposed to multiple chemical and physical stressors, but distinguishing anthropogenic impacts from other environmental drivers remains challenging. Rarely are multiple stressors investigated in replicated studies over large spatial scales (>1000 kms) or supported with manipulations that are necessary to interpret ecological patterns. We measured the composition of sediment infaunal communities in relation to anthropogenic and natural stressors at multiple sites within seven estuaries. We observed increases in the richness and abundance of polychaete worms in heavily modified estuaries with severe metal contamination, but no changes in the diversity or abundance of other taxa. Estuaries in which toxic contaminants were elevated also showed evidence of organic enrichment. We hypothesised that the observed response of polychaetes was not a ‘positive’ response to toxic contamination or a reduction in biotic competition, but due to high levels of nutrients in heavily modified estuaries driving productivity in the water column and enriching the sediment over large spatial scales. We deployed defaunated field-collected sediments from the surveyed estuaries in a small scale experiment, but observed no effects of sediment characteristics (toxic or enriching). Furthermore, invertebrate recruitment instead reflected the low diversity and abundance observed during field surveys of this relatively ‘pristine’ estuary. This suggests that differences observed in the survey are not a direct consequence of sediment characteristics (even severe metal contamination) but are related to parameters that covary with estuary modification such as enhanced productivity from nutrient inputs and the diversity of the local species pool. This has implications for the interpretation of diversity measures in large-scale monitoring studies in which the observed patterns may be strongly influenced by many factors that covary with anthropogenic modification. PMID:24098816

Dafforn, Katherine A.; Kelaher, Brendan P.; Simpson, Stuart L.; Coleman, Melinda A.; Hutchings, Pat A.; Clark, Graeme F.; Knott, Nathan A.; Doblin, Martina A.; Johnston, Emma L.

2013-01-01

311

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

312

Long-term trends in Pamlico River Estuary nutrients, chlorophyll, dissolved oxygen, and watershed nutrient production  

Science.gov (United States)

Trends in Pamlico River estuary ammonia nitrogen (NH4), nitrate nitrogen (NO3), phosphate phosphorus (PO4), chlorophyll a (chl a) and dissolved oxygen (DO) during the past 20-24 years were analyzed, and estimates of annual N and P production in the watershed over the past century were computed. The goal of the study was to determine whether or not the estuary is becoming more eutrophic. NO3 has decreased in the upper and middle regions of the estuary by 3-6% yr-1 since 1970, and NH4 has decreased throughout the estuary at an annual rate of 5.5-7.7% yr-1. Since 1967 PO4 has increased by 2% yr-1 in the lower two thirds of the estuary due to discharges from a phosphate mining facility. Thus the inorganic N:P ratio has decreased, which suggests that N is now potentially more limiting than in the past. In the upper estuary, chl a increased at a rate of 6.6% yr-1 since 1970, and bottom water DO decreased very slightly; neither showed trends in the middle and lower estuary regions. The weight of the evidence is that the Pamlico has not become more eutrophic during the past two decades. This finding is corroborated by the lack of a trend since 1970 in calculated N and P production from point and nonpoint sources in the watershed. Watershed nutrient production is estimated to have increased severalfold between 1880 and 1970, but appears to have stabilized after 1970, due primarily to decreased application of fertilizer on croplands.

Stanley, Donald W.

1993-08-01

313

The effects of hydrological dynamics on benthic diatom community structure in a highly stratified estuary: The case of the Ebro Estuary (Catalonia, Spain)  

Science.gov (United States)

This study of the distribution of benthic diatom assemblages and their relationship with environmental factors in a highly stratified Mediterranean estuary, i.e. the Ebro Estuary, shows the importance of hydrological dynamics to explain the features of the diatom community in such an estuary, where river flow magnitude and fluctuations imply strong physicochemical variability especially in sites close to the sea. Eight sites along the estuary were sampled during 2007-2008 both at superficial and deep water layers, in order to gather both horizontal and vertical estuarine physicochemical and hydrological gradients. Canonical Variates Analysis and Hierarchical Cluster Analysis segregated diatom community in two assemblages depending on the dynamics of the salt-wedge. The diatom assemblages of riverine conditions (i.e. without salt-wedge influence) where characterised by high abundances of Cocconeis placentula var. euglypta and Amphora pediculus, meanwhile high abundances of Nizschia frustulum and Nitzschia inconspicua were characteristic of estuarine conditions (i.e. under salt-wedge influence). Redundancy Analysis showed that both diatom assemblages responded seasonally to Ebro River flows, especially in estuarine conditions, where fluctuating conditions affected diatom assemblages both at spatial and temporal scale.

Rovira, L.; Trobajo, R.; Leira, M.; Ibáñez, C.

2012-04-01

314

Bacterial Communities in Kuantan Estuary of Pahang Malaysia  

Directory of Open Access Journals (Sweden)

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

K.C.A. Jalal

2010-01-01

315

Fishes and fisheries in tropical estuaries: The last 10 years  

Science.gov (United States)

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

Blaber, S. J. M.

2013-12-01

316

Investigation of transport processes in a large urban estuary  

Science.gov (United States)

The Hudson River drains an area of 35 000 km^2 and terminates in a complex of waterways surrounding New York City. These waterways support the largest metropolitan area and third busiest seaport in the U.S., absorbing a large flux of industrial contaminants and wastewater, as well as accidental spills of oil and chemicals. Traditional approaches to the study of transport processes in New York Harbor include fluorescent dyes, moored current profilers, and numerical models, but these methods are limited by low temporal and spatial resolution and/or uncertain accuracy, particularly with regard to mixing. In July 2001, sulfur hexafluoride (SF_6) was injected into the Hudson River estuary near Newburgh, NY, about 100 km upstream from New York City. The resulting tracer patch was surveyed by boat (average resolution: 400 m) with an automated measurement system. After 13 days, the tracer patch was more than 100 km long. Net advection (0.5 km d-1), longitudinal dispersion (70 ± 4 m^2 s-1) and gas transfer velocity (6.5 ± 0.5 cm h-1) were determined from the tracer data. Tidal motions dominated river flow, and considerable quantities of tracer propagated upstream from the injection site. In July 2002, SF_6 was injected in the inner harbor, a complex of estuarine channels adjacent to the city. The tracer was tracked for 11 days. Due to tidal mixing, the shorter of two channels (9 km and 20 km) that connect with the outer harbor was the dominant seaward pathway, despite subtidal circulation in the opposite direction. As a result of gas transfer and seaward flushing, tracer mass in the inner harbor declined quasi-exponentially with a loss term of 0.29 ± 0.03 day-1. The loss term due to flushing alone (0.13 ± 0.02 day-1) indicated a mean residence time for water and solutes in the inner harbor of 8 days (without gas transfer). Further projects, including an investigation of wastewater fate, are planned within the lower estuary.

Caplow, T.; Schlosser, P.; Ho, D. T.; Santella, N.

2003-04-01

317

Remote Sensing Technologies for Estuary Research and Management (Invited)  

Science.gov (United States)

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

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

2013-12-01

318

Seine estuary modelling and AirSWOT measurements validation  

Science.gov (United States)

In the context of global climate change, knowing water fluxes and storage, from the global scale to the local scale, is a crucial issue. The future satellite SWOT (Surface Water and Ocean Topography) mission, dedicated to the surface water observation, is proposed to meet this challenge. SWOT main payload will be a Ka-band Radar Interferometer (KaRIn). To validate this new kind of measurements, preparatory airborne campaigns (called AirSWOT) are currently being designed. AirSWOT will carry an interferometer similar to Karin: Kaspar-Ka-band SWOT Phenomenology Airborne Radar. Some campaigns are planned in France in 2014. During these campaigns, the plane will fly over the Seine River basin, especially to observe its estuary, the upstream river main channel (to quantify river-aquifer exchange) and some wetlands. The present work objective is to validate the ability of AirSWOT and SWOT, using a Seine estuary hydrodynamic modelling. In this context, field measurements will be collected by different teams such as GIP (Public Interest Group) Seine Aval, the GPMR (Rouen Seaport), SHOM (Hydrographic and Oceanographic Service of the Navy), the IFREMER (French Research Institute for Sea Exploitation), Mercator-Ocean, LEGOS (Laboratory of Space Study in Geophysics and Oceanography), ADES (Data Access Groundwater) ... . These datasets will be used first to validate locally AirSWOT measurements, and then to improve a hydrodynamic simulations (using tidal boundary conditions, river and groundwater inflows ...) for AirSWOT data 2D validation. This modelling will also be used to estimate the benefit of the future SWOT mission for mid-latitude river hydrology. To do this modelling,the TUGOm barotropic model (Toulouse Unstructured Grid Ocean model 2D) is used. Preliminary simulations have been performed by first modelling and then combining to different regions: first the Seine River and its estuarine area and secondly the English Channel. These two simulations h are currently being improved, by testing different roughness coefficients, adding tributary inflows. Groundwater contributions will also be introduced (digital TUGOm development in progress) . The model outputs will be validated using data from the GPMR tide gauge data and measurements from the Topex/Poseidon and Jason-1/-2 altimeters for year 2007.

Chevalier, Laetitia; Lyard, Florent; Laignel, Benoit

2013-04-01

319

Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program  

Science.gov (United States)

The activities are reported of the NASA Biomedical Applications Team at Southwest Research Institute between 25 August, 1972 and 15 November, 1973. The program background and methodology are discussed along with the technology applications, and biomedical community impacts.

Culclasure, D. F.; Sigmon, J. L.; Carter, J. M.

1973-01-01

320

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

Science.gov (United States)

...Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, Salmon-Challis, and Sawtooth National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting. The meeting is open to...

2011-02-03

 
 
 
 
321

77 FR 43805 - Notice of Southwest Idaho Resource Advisory Committee Meeting  

Science.gov (United States)

...Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, Salmon-Challis, Sawtooth, and Wallowa-Whitman National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting....

2012-07-26

322

77 FR 53170 - Notice of Southwest Idaho Resource Advisory Committee Meeting  

Science.gov (United States)

...Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, Salmon-Challis, Sawtooth, and Wallowa-Whitman National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting....

2012-08-31

323

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

Science.gov (United States)

...Rural Schools and Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, and Sawtooth National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting. The meeting is open to...

2010-03-01

324

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

Science.gov (United States)

...Rural Schools and Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, and Sawtooth National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting. The meeting is open to...

2010-11-05

325

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

Science.gov (United States)

...Rural Schools and Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, and Sawtooth National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting. The meeting is open to...

2010-05-06

326

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

Science.gov (United States)

...Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, Salmon-Challis, and Sawtooth National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting. The meeting is open to...

2011-03-08

327

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

Science.gov (United States)

...Rural Schools and Community Self-Determination Act of 2000, as amended, (Pub. L. 110-343), the Boise, Payette, and Sawtooth National Forests' Southwest Idaho Resource Advisory Committee will conduct a business meeting. The meeting is open to...

2010-03-31

328

77 FR 34381 - Pacific Northwest-Pacific Southwest Intertie Project-Rate Order No. WAPA-157  

Science.gov (United States)

...Southwest Intertie Project--Rate Order No. WAPA-157 AGENCY: Western Area Power Administration...Phoenix, AZ 85005-6457, email moe@wapa.gov. Written comments may also be faxed...process on its Web site at...

2012-06-11

329

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

330

77 FR 9233 - Southwest Gas Storage Company; Notice of Request Under Blanket Authorization  

Science.gov (United States)

...Specifically, Southwest proposes to (1) drill dual horizontal wellbore extensions in two injection/withdrawal wells; (2) convert three injection/withdrawal wells to observation wells; (3) replace pipe associated with four storage...

2012-02-16

331

77 FR 40846 - Santa Fe National Forest; New Mexico; Southwest Jemez Mountains Landscape Restoration Project...  

Science.gov (United States)

...National Forest; New Mexico; Southwest Jemez Mountains...Jemez Springs, New Mexico. The goal is to make...traditional cultural properties, sacred sites, and...traditional cultural properties and sacred sites. All...permit from the New Mexico Environment...

2012-07-11

332

Understanding the Influence of Retention Basin on Tidal Dynamics in Tidal Estuaries  

Science.gov (United States)

Both the tidal motion and suspended sediment concentration (SSC) in tidal embayments and estuaries are influenced by anthropogenic (e.g. deepening ) and natural changes. An example of such an estuary is the Ems estuary, situated on the border of the Netherlands and Germany. The mean tidal range towards the end of the Ems estuary has increased from 1.5m in the 1950s to more than 3m in the 1990s while the suspended concentration has increased by a factor 10. To possibly reduce these negative effects, the construction of retention basin(s) (RB) is considered. In this contribution, the influence of location and geometry of RBs on tidal dynamics and SSC is investigated. For this purpose, a three-dimensional semi-analytic idealized model is developed. This model is an extension of the model proposed by Winant (2007) to arbitrary domain and realistic bathymetry with partial slip boundary condition at the bottom. The sea surface elevation (SSE) is calculated numerically using a finite element method. Next, the three-dimensional velocities are calculated by combining the analytically calculated vertical profiles and the gradients of the SSE which are obtained numerically. Firstly, the influence of a RB on the tidal dynamics in an infinitely long, rectangular, frictionless estuary is considered. The SSE decreases when the RB is located between a node and a landward antinode, consistent with the work of Alebregtse et al. (2013). Secondly, an estuary of finite length is connected to a sea. By varying the width of the sea, not only the effect of the distance of the RB to the landward end plays a role, but also the distance to the open sea becomes important. Finally, we discuss the influence of a RB on the tidal motion and initial sediment transport, considering the Ems estuary with realistic bathymetry. Results show that the SSE at the landward end of the Ems estuary decreases for all locations of the RBs. This decrease is most pronounced for the RB which is closest to the end of the Ems estuary. Concerning the initial sediment transport, introduction of a RB creates a convergence zone at the location of RB with enhanced along-channel transport seaward and reduced along-channel transport landward of the location of the RB. The intensity of the change in the along-channel transport decreases as the RB is located closer to the landward end. A Similar trend is obtained for cross-channel transport, meaning that the RB will fill more slowly when located closer to the end. The mechanisms resulting in these observed changes, and their sensitivity to the parameters (such as friction, geometry of RBs ,etc) will be discussed in detail.

Kumar, Mohit; Schuttelaars, Henk; Roos, Pieter

2014-05-01

333

A theoretical framework for analyzing the effect of external change on tidal dynamics in estuaries  

Science.gov (United States)

The most densely populated areas of the world are usually located in coastal areas near estuaries. As a result, estuaries are often subject to intense human interventions, such as dredging for navigation, dam construction and fresh water withdrawal etc., which in some areas has led to serious deterioration of invaluable ecosystems. Hence it is important to understand the influence of such interventions on tidal dynamics in these areas. In this study, we present one consistent theoretical framework for tidal hydrodynamics, which can be used as a rapid assessment technique that assist policy maker and managers to make considered decisions for the protection and management of estuarine environment when assessing the effect of human interventions in estuaries. Analytical solutions to the one-dimensional St. Venant equations for the tidal hydrodynamics in convergent unbounded estuaries with negligible river discharge can be cast in the form of a set of four implicit dimensionless equations for phase lag, velocity amplitude, damping, and wave celerity, as a function of two localized parameters describing friction and convergence. This method allows for the comparison of the different analytical approaches by rewriting the different solutions in the same format. In this study, classical and more recent formulations are compared, showing the differences and similarities associated to their specific simplifications. The envelope method, which is based on the consideration of the dynamics at high water and low water, can be used to derive damping equations that use different friction approximations. This results in as many analytical solutions, and thereby allows one to build a consistent theoretical framework. Analysis of the asymptotic behaviour of the equations shows that an equilibrium tidal amplitude exits reflecting the balance between friction and channel convergence. The framework is subsequently extended to take into account the effect of river discharge. Hence, the analytical solutions are applicable even in the upstream part of an estuary, where the influence of river discharge is remarkable. The proposed analytical solutions are transparent and practical, allowing a quantitative and qualitative assessment of human interventions (e.g., dredging, flow reduction) on tidal dynamics. Moreover, they are rapid assessment techniques that enable the users to set up a simple model and to understand the functioning of the system with a minimum of information required. The analytical model is illustrated in three large-scale estuaries with significant influence by human activities, i.e., the Scheldt estuary in the Netherlands, the Modaomen and the Yangtze estuaries in China. In these estuaries, the correspondence with observations is good, which suggests that the proposed model is a useful, yet realistic and reliable instrument for quick detection of the effect of human interventions on tidal dynamics and subsequent environmental issues, such as salt intrusion.

CAI, H.; Savenije, H.; Toffolon, M.

2013-12-01

334

Landscape practices and representations in eighteenth-century Dongchuan, Southwest China  

Digital Repository Infrastructure Vision for European Research (DRIVER)

My doctorial thesis, entitled ‘Landscape Practices and Representations in Dongchuan, Southwest Eighteenth-Century China’, focuses on the interdisciplinary study of landscape, space and architecture in Southwest eighteenth-century China. Through intensive archival research and contemporary ethnographic fieldwork I demonstrate that despite the Qing Empire’s remaking of the indigenous landscape in the eighteenth century, indigenous concepts of landscape and space have survived to the prese...

Huang, Fei

2012-01-01

335

Weak and habitat-dependent effects of nutrient pollution on macrofaunal communities of southeast Australian estuaries.  

Science.gov (United States)

Among the impacts of coastal settlements to estuaries, nutrient pollution is often singled out as a leading cause of modification to the ecological communities of soft sediments. Through sampling of 48 sites, distributed among 16 estuaries of New South Wales, Australia, we tested the hypotheses that (1) anthropogenic nutrient loads would be a better predictor of macrofaunal communities than estuarine geomorphology or local sediment characteristics; and (2) local environmental context, as determined largely by sediment characteristics, would modify the relationship between nutrient loading and community composition. Contrary to the hypothesis, multivariate multiple regression analyses revealed that sediment grain size was the best predictor of macrofaunal assemblage composition. When samples were stratified according to median grain size, relationships between faunal communities and nitrogen loading and latitude emerged, but only among estuaries with sandier sediments. In these estuaries, capitellid and nereid polychaetes and chironomid larvae were the taxa that showed the strongest correlations with nutrient loading. Overall, this study failed to provide evidence of a differential relationship between diffuse nutrient enrichment and benthic macrofauna across a gradient of 7° of latitude and 4°C temperature. Nevertheless, as human population growth continues to place increasing pressure on southeast Australian estuaries, manipulative field studies examining when and where nutrient loading will lead to significant changes in estuarine community structure are needed. PMID:23799037

Nicastro, Andrea; Bishop, Melanie J

2013-01-01

336

The effect of residual water level slope on tidal propagation in the Yangtze estuary  

Science.gov (United States)

As the tidal wave propagates into the estuary, usually the tidally averaged water level rises in landward direction. This effect is even stronger if there is substantial river discharge. In this study, we focus on the effect of this phenomenon on tidal wave propagation in Yangtze estuary, which is the largest river in China with an annual mean freshwater discharge of 28300 m3/s measured at the upstream boundary of the estuary (Datong station, 1950--2010). This is done by exploiting a one-dimensional analytical model for tidal hydrodynamics, which accounts for the effect of residual water level slope. The aim of this study is to provide insights into the relative importance of residual water level slope on tidal dynamics, which could be used for improving the prediction of tidal propagation in estuaries, especially when the influence of river discharge is significant. Subsequently, it is in principle possible to develop a method for estimating river discharge with observed tidal damping along the estuary by using an inverse analytical model.

Cai, Huayang; Savenije, Hubert H. G.; Jiang, Chenjuan

2014-05-01

337

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

Science.gov (United States)

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

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

2014-07-01

338

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-10-10

339

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

Energy Technology Data Exchange (ETDEWEB)

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

Johnson, Gary E.; Diefenderfer, Heida L.

2007-10-10

340

Late Holocene Geomorphology of the Columbia River Estuary, Oregon and Washington, USA  

Directory of Open Access Journals (Sweden)

Full Text Available Abundant river sediment supply and an open-water central bay area characterize the geomorphology of the large Columbia River estuary (~ 100 km in length. Lateral floodplains and marsh islands do constrict the uppermost reaches of the estuary, but the central axes of the lower estuary are dominated by shallow sand shoals (0–4 m water depth. A total of 58 vibracores are used to document the grain size and age (0–2,500 14CyrBP of late Holocene deposits in the estuary. Sedimentation rates in stable floodplains (1.1 m ka-1 reflect rates of relative sea level rise (0.75 m ka-1. Sedimentation rates of muddy sand accretionary banks and prehistoric sand shoals (1.5–7 m ka-1 greatly exceed coeval rates of sea level rise, so they must represent short–term rates of vertical accretion resulting from channel lateral migration and associated cut and fill processes. The apparent paradox of unfilled accommodation space in the estuary is resolved by 1 winter wind–wave erosion of sand shoals to -3 m NAVD88 elevation and 2 asymmetric fluvial-tidal advection that results in net seaward transport of bed load in shallow tidal channels (> – 10 m NAVD88 and shallow subtidal shoals (> – 4 m NAVD88 during spring river flooding. 

Curt Peterson

2014-03-01

 
 
 
 
341

Pollution history of the Savannah Estuary. National status and trends program for marine environmental quality  

Energy Technology Data Exchange (ETDEWEB)

Dated cores collected from different sites in the Savannah Estuary were analyzed for 16 metals, 22 polycyclic aromatic hydrocarbons (PAH), 20 polychlorinated biphenyls (PCB) congeners, 16 pesticides and 3 butylins. Time stratigraphy of the cores were determined by measurements of Pb-210 and Cs-137 activities down the cores. Those chemicals which showed significant temporal changes down dated cores in the Savannah Estuary included mercury, lead, chromium, PAHs, DDT isomers and metabolites, PCBs and dieldrin. The present study used cores from the Savannah Estuary, where the population is relatively low (approximately 150,000) and industrial growth has occurred over the past 30 years. Thus, the concentrations of most anthropogenic chemical found in the cores of the Savannah Estuary were comparatively low. An interesting aspect of the study, which has been noted by many pollution history studies, was the decrease in the concentration of anthropogenic chemicals during the past two decades suggesting that many pollution control laws have been effective, even while industrial and population growth continues in an area. In summation, the authors` studies present evidence of relatively large inputs of anthropogenic chemicals, including mercury, chromium, lead, polycycloic aromatic hydrocarbons, dieldrin, DDT isomers, and polychlorinated biphenyls, during the 1950s and 1960 into the Savannah Estuary followed by a gradual decrease of these chemicals during the past 20 to 30 years.

Alexander, C.; Ertel, J.; Lee, R.; Loganathan, B.; Martin, J.

1997-09-01

342

Fingerprinting of bed sediment in the Tay Estuary, Scotland: an environmental magnetism approach  

Directory of Open Access Journals (Sweden)

Full Text Available Sediment fingerprinting is commonly used for sediment provenance studies in lakes, rivers and reservoirs and on hillslopes and floodplains. This investigation explores the mixing of terrestrial and marine-derived sediment in the Tay Estuary, Scotland, using mineral magnetic attributes for fingerprinting. Samples representative of the estuary sediments and of four sources (end-members were subjected to a suite of magnetic susceptibility and remanence measurements. Sediment samples from the beds of the Rivers Tay and Earn represented fluvial inputs while samples from the Angus and Fife coasts represented marine input. Multivariate discriminant and factor analysis showed that the sources could be separated on the basis of six magnetic parameters in a simple multivariate unmixing model to identify source contributions to estuarine bed sediments. Multi-domain magnetite signatures, characteristic of unweathered bedrock, dominate the magnetic measurements. Overall contributions of 3% from the River Earn, 17% from the River Tay, 29% from the Angus coast and 51% from the Fife coast source end-members, demonstrated the present-day regime of marine sediment derivation in the Tay Estuary. However, this conceals considerable spatial variability both along-estuary and in terms of sub-environments, with small-scale variations in sediment provenance reflecting local morphology, particularly areas of channel convergence. Keywords: bed sediment, environmental magnetism, fingerprinting, Tay Estuary, Scotland

P. A. Jenkins

2002-01-01

343

RELATIONSHIP BETWEEN BOTTOM SHEAR STRESS AND TURBIDITY IN ESTUARIES  

Science.gov (United States)

The formation of oxygen-poor water and the occurrence of hydrogen sulfide in estuary are caused by the sludge which contains a lot of organic substance. In order to examine measures against the water environment problems caused by the sludge, it is necessary to estimate bottom shear stress which is considered to be that exert influence on the behavior of bottom material. Based on our study, the bottom shear stress was estimated by the method of using the change of water level obtained by one-dimensional unsteady flow analysis and the density distribution obtained by field observation. The estimated bottom shear stress was validated by comparison with coefficient of eddy viscosity. In addition, the relationship between the bottom shear stress and the turbidity is discussed. The summary of the results is shown as follows; Increase in turbidity during flood tide is caused that the tip of saline wedge passes through a cross section; Due to increase in the velocity of toward downstream, the turbidity also increase during ebb tide.

Sakamoto, Jun-Ichi; Matsumoto, Haruhiko; Hadano, Kesayoshi; Amano, Takuzo; Mitsunobu, Kiyonobu

344

Radioactivity and United Kingdom estuaries: an overview identifying research priorities  

International Nuclear Information System (INIS)

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

345

Impacts of the Garafiri hydroelectric dam on the Konkoure estuary  

International Nuclear Information System (INIS)

This article described the environmental impacts caused by the exploitation of one or several dams in tropical coastal basins. In particular, it proposed a methodological approach for analyzing the vulnerability of ecosystems to modifications caused by the exploitation of the Garafiri hydroelectric dam in Guinea. With an installed power capacity of 75 MW, this dam has been operational since 1999 and has supplied electricity to coastal and mid Guinea since 2000. Since then, the ecosystem of the Konkoure River has undergone important changes. This study focused primarily on impacts during the dry season. Data was collected at different hydroelectric stations along the Konkoure Basin to estimate changes in water flow in the estuary. The study showed several changes, including noticeable impacts on the soil salt content. In addition, changes in vegetation were attributed to changes in soil content. The study revealed that rice production has increased 65 per cent since 2000, while salt exploitation has been completely discontinued. It was concluded that the hydraulic management of the dam can have a significant impact on the region's ecosystem which can in turn influence ecological and social economic functions. It was concluded that the vulnerability of the ecosystem can be worsened in the context of climate change. 25 refs., 9 figs

346

REE in the Great Whale River estuary, northwest Quebec  

Science.gov (United States)

A report on REE concentrations within the estuary of the Great Whale River in northwest Quebec and in Hudson Bay is given, showing concentrations which are less than those predicted by conservative mixing of seawater and river water, indicating removal of REE from solution. REE removal is rapid, occurring primarily at salinities less than 2 percent and ranges from about 70 percent for light REE to no more than 40 percent for heavy REE. At low salinity, Fe removal is essentially complete. The shape of Fe and REE vs. salinity profiles is not consistent with a simple model of destabilization and coagulation of Fe and REE-bearing colloidal material. A linear relationship between the activity of free ion REE(3+) and pH is consistent with a simple ion-exchange model for REE removal. Surface and subsurface samples of Hudson Bay seawater show high REE and La/Yb concentrations relative to average seawater, with the subsurface sample having a Nd concentration of 100 pmol/kg and an epsilon(Nd) of -29.3; characteristics consistent with river inputs of Hudson Bay. This indicates that rivers draining the Canadian Shield are a major source of nonradiogenic Nd and REE to the Atlantic Ocean.

Goldstein, Steven J.; Jacobsen, Stein B.

1988-01-01

347

Environmental flow assessments in estuaries related to preference of phytoplankton  

Science.gov (United States)

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

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

2014-05-01

348

Measuring hydrodynamics and sediment transport processes in the Dee estuary  

Directory of Open Access Journals (Sweden)

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

R. Bolaños

2010-03-01

349

Measuring hydrodynamics and sediment transport processes in the Dee Estuary  

Directory of Open Access Journals (Sweden)

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

R. Bolaños

2010-06-01

350

Eutrophication in an Urban Estuary: Famosa Slough, California  

Science.gov (United States)

Increased nutrient loads and hydromodification in urban California coastal lagoons have fueled macroalgal blooms; leading to water column hypoxia, and poor habitat. Additionally, sediment-derived nutrients from decomposition of accumulated organic matter are biologically available to primary producers and may cause blooms to persist even when nutrient loading is reduced. Eutrophication can be further exacerbated by hydromodification which increases residence time and thereby increases nutrient availability. In this study, we estimated nutrient budgets for Famosa Slough, an urban estuary with an anthropogenically muted tidal regime in San Diego County, California. Nitrogen (N) and phosphorus (P) sources from terrestrial runoff, atmospheric deposition, and benthic flux were estimated over a one year period and compared with estimates of N and P required to support macroalgal blooms in the Slough. Macroalgal blooms and chronic nighttime hypoxia (DO nutrient concentrations suggest that the slough is N-limited. The contribution of benthic flux was important in overall N budget of Famosa Slough, representing about 50% of the terrestrial runoff from local catchment annually. During periods of peak algal blooms and hypoxia, benthic flux represents 56% of the TN and 75% of the bioavailable nitrate and ammonia. Remineralization of organic matter will likely continue to cause problems with algal blooms and hypoxia, even with terrestrial nutrient reductions, unless restoration is undertaken to flush the slough of the fine-grained sediments and improve circulation.

McLaughlin, K.; Sutula, M.; Cable, J. E.; Fong, P.; Green, L.

2010-12-01

351

Chronic oil pollution harms Magellanic penguins in the Southwest Atlantic.  

Science.gov (United States)

Petroleum pollution is a problem for seabirds along the Southwest Atlantic coast. Twenty-five groups from Salvador, Brazil (12 degrees 58'S) to San Antonio Oeste, Argentina (40 degrees 43'S) survey or rehabilitate sick or oiled seabirds. Four groups, one each in Brazil and Uruguay, and two in Argentina, kept counts of birds found alive and in need of rehabilitation. An average of 63.7% of the seabirds found were Magellanic penguins (Spheniscus magellanicus), with 3869 reported since 1987. Mainly adult penguins were found in Argentina (1605 of 2102 penguins of known age class) and Uruguay (158 of 197). Juveniles were most common in Brazil (234 of 325). Oil fouling was the most frequent cause of injury or sickness. The number of oiled penguins reported in their wintering range has greatly increased since the early 1990s and is strongly correlated with petroleum exports from Argentina. Our results show that chronic petroleum pollution is a problem for wildlife from Southern Brazil through Northern Argentina, and regulations and enforcement are failing to protect living resources. PMID:16364372

García-Borboroglu, Pablo; Boersma, P Dee; Ruoppolo, Valeria; Reyes, Laura; Rebstock, Ginger A; Griot, Karen; Rodrigues Heredia, Sergio; Adornes, Andrea Corrado; da Silva, Rodolfo Pinho

2006-02-01

352

Chronic oil pollution harms Magellanic penguins in the Southwest Atlantic  

Energy Technology Data Exchange (ETDEWEB)

Petroleum pollution is a problem for seabirds along the Southwest Atlantic coast. Twenty-five groups from Salvador, Brazil (12{sup o}58'S) to San Antonio Oeste, Argentina (40{sup o}43'S) survey or rehabilitate sick or oiled seabirds. Four groups, one each in Brazil and Uruguay, and two in Argentina, kept counts of birds found alive and in need of rehabilitation. An average of 63.7% of the seabirds found were Magellanic penguins (Spheniscus magellanicus), with 3869 reported since 1987. Mainly adult penguins were found in Argentina (1605 of 2102 penguins of known age class) and Uruguay (158 of 197). Juveniles were most common in Brazil (234 of 325). Oil fouling was the most frequent cause of injury or sickness. The number of oiled penguins reported in their wintering range has greatly increased since the early 1990s and is strongly correlated with petroleum exports from Argentina. Our results show that chronic petroleum pollution is a problem for wildlife from Southern Brazil through Northern Argentina, and regulations and enforcement are failing to protect living resources. (author)

Garcia-Borboroglu, P. [Centro Nacional Patagonico (CONICET), Chubut (Argentina); Wildlife Conservation Society, New York, NY (United States); Boersma, P.D. [Wildlife Conservation Society, New York, NY (United States); University of Washington, Seattle, WA (United States); Ruoppolo, V. [International Fund for Animal Welfare, Emergency Relief Team - Oiled Wildlife Division, Sao Paolo (BR)] (and others)

2006-02-15

353

Epidemiological evaluation of onchocerciasis along Ogun River System, southwest Nigeria  

Directory of Open Access Journals (Sweden)

Full Text Available 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 prevalence ofonchocerciasis ranged from 19.1 to 45.6%, while the CMFL ranged from 0.11 to 1.03 microfilariae per skinsnip. The CMFL recorded was <5 microfilariae per skin snip, i.e. recognized by WHO as threshold value incertifying the communities to be free of onchocerciasis as public health problem, thus, signifying the possibilityof onchocerciasis elimination in the study area.Conclusion: Efforts should therefore be intensified to achieve improved ivermectin coverage and compliance inannual ivermectin treatment in order to completely eliminate onchocerciasis as a public health problem in thestudied communities.

S.O. Sam-Wobo , M.A. Adeleke , O.A. Jayeola , A.O. Adeyi , A.S. Oluwole , M. Ikenga , A. Lawniye , J. Gazama , A. Kagni , T.O. Kosoko , O. Agbeyangi , S. Bankole , L. Toé , C.F. Mafiana & L. Yameogo

2012-06-01

354

Precipitation Patterns Observed over the Southwest Region of Saudi Arabia  

Science.gov (United States)

During 2008 and 2009, an intensive field program has been conducted in the southwest region of Saudi Arabia, which is adjacent to the Red Sea and is bounded by the Yemen border to the south and the region around Jeddah to the north. The period of study focused on analysis of observations for the months of June-August. This period coincides with a climatological peak in precipitation over the region. This region is mountainous with terrain ranging from sea level to a maximum height of about 2800 m. During the field program, convection was observed almost daily during mid-afternoon was focused along the mountain peaks. This peak in convection coincided with the sea breeze reaching the top of the tallest terrain features. The intensity of convection was modulated by the strength of the sea breeze (predominate wind direction, amount of moisture in the boundary layer, etc.) and strength of a persistent mid-level inversion. The main objective of this study focuses on characterizing the spatial and temporal features of convection and related it to the atmospheric conditions that were observed during the months of June-August. The study examines precipitation and atmospheric conditions using a network of C-Band radars (Abha, Baha, Jeddah, Jizan, and Taif) and surface and upper data collected from the site located in Abha. The presentation will provide an overview of the field program and give a summary of the precipitation and atmospheric characteristics for the two years used in the study.

Kucera, Paul; Chapman, Michael

2010-05-01

355

Estimate of winter wheat yield from ERTS-1. [southwest Kansas  

Science.gov (United States)

A model for estimating wheat yield per acre has been applied to acreage estimates derived from ERTS-1 imagery to project the 1973 wheat yields for a ten county area in southwest Kansas. The results (41.04 million bushels) are within 3 per cent of the preharvest estimates for the same area prepared by the USDA Statistical Reporting Service (39.91 million bushels). The projection from ERTS data is based on a visual enumeration of all detectable wheat fields in the study area and was completed while the harvest was in progress. Visual identification of winter wheat is readily achieved by using a temporal sequence of images (band 5 for Sept.-Oct.; band 5 for Dec.-Jan.; and band 5 and 7 for March-April). Identification can be improved by stratifying the project area into subregions having more or less homogeneous agricultural practices and crop mixes. By doing this, small changes in the spectral appearance of wheat related to soil type, irrigation, etc. can be accounted for. The interpretation rules developed by visual analysis can be automated for rapid computer surveys.

Morain, S. A.; Williams, D. W.

1974-01-01

356

Analysis of tectonic features in US southwest from Skylab photographs  

Science.gov (United States)

The author has identified the following significant results. Skylab photographs were utilized to study faults and tectonic lines in selected areas of the U.S. Southwest. Emphasis was on elements of the Texas Zone in the Mojave Desert and the tectonic intersection in southern Nevada. Transverse faults believed to represent the continuation of the Texas Zone were found to be anomalous in strike. This suggests that the Mojave Desert block was rotated counterclockwise as a unit with the Sierra Nevada. Left-lateral strike-slip faults in Lake Mead area are interpreted as elements of the Wasatch tectonic zone; their anomalous trend indicates that the Lake Mead area has rotated clockwise with the Colorado Plateau. A tectonic model relating major fault zones to fragmentation and rotation of crustal blocks was developed. Detailed correlation of the high resolution S190B metric camera photographs with U-2 photographs and geologic maps demonstrates the feasibility of utilizing S190B photographs for the identification of geomorphic features associated with recent and active faults and for the assessment of seismic hazards.

Abdel-Gawad, M. (principal investigator); Tubbesing, L.

1975-01-01

357

Local Impact of State Testing in Southwest Washington  

Directory of Open Access Journals (Sweden)

Full Text Available A decade after implementation of a state testing and accountability mandate, teachers' practices and perspectives regarding their classroom assessments and their state's assessments of student achievement were documented in a study of 31 teachers in southwest Washington state. Against a background of national trends and standards of psychometric quality, the data were analyzed for teachers' beliefs and practices regarding classroom assessment and also regarding state assessment, commonalities and differences among teachers who taught at grade levels tested by the state and those who did not, teachers' views about the impact of state assessment on their students and their classrooms, and their views about whether state testing promoted educational improvement or reform as intended. Data registered (1 teachers' preferences for multiple measures and their objections to single-shot high-stakes testing as insufficiently informative, unlikely to promote valid inferences of student achievement, and often distortive of curriculum and pedagogy; (2 teachers' objections to the state test as inappropriate for nonproficient speakers of English, for students eligible for special services, and for impoverished students; and (3 teachers' preferences for personalized assessments respectful of student circumstances and readiness, rather than standardized assessments. Teachers' practical wisdom thus appeared more congruent than the state testing program with measurement principles regarding (1 multiple methods and (2 validation for specific test usage, including usage with disadvantaged subgroups of test-takers. Findings contrasted a distinction of emphasis: state focus on "testing students" as distinct from teachers' focus on "testing students."

Linda Mabry

2003-07-01

358

Creation of security engineering programs by the Southwest Surety Institute  

Science.gov (United States)

The Southwest Surety Institute includes Arizona State University (ASU), Louisiana State University (LSU), New Mexico Institute of Mining and Technology (NM Tech), New Mexico State University (NMSU), and Sandia National Laboratories (SNL). The universities currently offer a full spectrum of post-secondary programs in security system design and evaluation, including an undergraduate minor, a graduate program, and continuing education programs. The programs are based on the methodology developed at Sandia National Laboratories over the past 25 years to protect critical nuclear assets. The programs combine basic concepts and principles from business, criminal justice, and technology to create an integrated performance-based approach to security system design and analysis. Existing university capabilities in criminal justice (NMSU), explosives testing and technology (NM Tech and LSU), and engineering technology (ASU) are leveraged to provide unique science-based programs that will emphasize the use of performance measures and computer analysis tools to prove the effectiveness of proposed systems in the design phase. Facility managers may then balance increased protection against the cost of implementation and risk mitigation, thereby enabling effective business decisions. Applications expected to benefit from these programs include corrections, law enforcement, counter-terrorism, critical infrastructure protection, financial and medical care fraud, industrial security, and border security.

Romero, Van D.; Rogers, Bradley; Winfree, Tim; Walsh, Dan; Garcia, Mary Lynn

1998-12-01

359

The chimpanzees of Oluwa Forest Reserve, southwest Nigeria  

Directory of Open Access Journals (Sweden)

Full Text Available 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 reserve. This portion is approximately 39.22km2 representing 5.78% of the total size of the original area of the reserve. Four sightings of Chimpanzee groups were achieved with an average of 9.50 ± 1.55 individuals observed. We observed nests built on rock platforms. The numbers of tree nests observed at sleeping sites were usually fewer than the number of animals seen, indicating that not all of them build nest on trees at their nesting sites. These observations were new in nesting behavior of chimpanzees across Nigeria and it is postulated to be on account of insecurity and deprivation of essential material necessary for nesting in their night sleeping sites. We explained this on the conceptual frame work of psycho-infrastructuralism model.

B.G. Ogunjemite

2012-12-01

360

Curvilinear ridges and related features in southwest Cydonia Mensae, Mars  

Science.gov (United States)

Examined is a region on Mars in southwest Cydonia Mensae (32 deg lat., 17 deg long.) just northwest of the lowland/upland boundary escarpment. The dominant morphological features in this region are the clusters of large massifs and plateau outliers (PI), knobby material (K), and smooth lowland plains (Ps). Surrounding the clusters and linking many isolated knobs is a system of curvilinear ridges and arcuate terrain boundaries which tend to separate the massifs and knobs from the smooth plains. Curvilinear ridges are arcuate to nearly linear and smoother in plan than wrinkle ridges and show no apparent correlation with regional structural grain. They are typically 5 to 10 km long but can range from as little as 2 or 3 km to greater than 50 km long. The widths vary from about 100 m to as much as 2 km. Curvilinear ridges are most numerous within 100 km of the lowland/upland boundary escarpment and are associated with massifs and knobby terrain. Arcuate terrain boundaries appear between units of different apparent albedo or arcuate breaks in slope.

Parker, Timothy J.; Schneeberger, Dale M.; Pieri, David C.; Saunders, R. Stephen

1987-01-01

 
 
 
 
361

Many southwest hosptials will receive decreased CMS reimbursement  

Directory of Open Access Journals (Sweden)

Full Text Available No abstract available. Article truncated at 150 words. More hospitals are receiving penalties than bonuses in the second year of the Centers for Medicare and Medicaid Services’ (CMS quality incentive program, and the average penalty is steeper than last year according to a report from Jordan Rau in Kaiser Health News (1. Southwest hospitals reflect that trend with New Mexico and Arizona exceeding the US average both in percentage of hospitals receiving penalties and the average size of the penalty (Table 1. Colorado approximated the national averages (Table 1. Most hospitals are gaining or losing <0.2% but in some instances the penalties are substantial. Gallup Indian Medical Center in New Mexico, a federal government hospital on the border of the Navajo Reservation, will be paid 1.14 percent less for each patient and New Mexico’s average of a -0.31% decline in reimbursement are the largest changes nationally. “This program is driving what we want in health care,” said Dr. …

Robbins RA

2013-11-01

362

Sequence stratigraphic control on prolific HC reservoir development, Southwest Iran  

Science.gov (United States)

An important carbonate formation in the Persian Gulf and the onshore oil fields of Southwest Iran is the Lowermost Cretaceous Fahliyan formation. The formation in Darkhowain field consists of unconformity-bounded depositional sequences containing prolific hydrocarbon reservoirs of contrasting origin. Located in the high stand systems tract (HST) of the lower sequence encompassing over 200m of oil column are the most prolific reservoir. Another reservoir is over 80m thick consisting of shallowing-upward cycles that are best developed within the transgressive systems tract of the upper sequence. Vertical facies distribution and their paleobathymetry and geophysical log signatures of the Fahliyan formation in the Darkhowain platform reveal the presence of two unconformity-bounded depositional sequences in Vail et al., Van Wagoner et al., and Sarg. The Fahliyan formation mainly consists of platform carbonates composed of restricted bioclastic lime mudstone to packstone of the platform interior, Lithocodium boundstone or ooid-intraclast-bioclast grainstone of the high energy platform margin and the bioclast packstone to lime mudstone related to the off-platform setting.

Lasemi, Y.; Kondroud, K.N.

2008-01-01

363

Flood/ebb tidal asymmetry in a shallow sandy estuary and the impact on net sand transport  

Science.gov (United States)

Flood/ebb tidal dominance plays a pivotal role in estuarine sediment transport. The Dyfi Estuary, mid-Wales, UK, is used as a case study, together with an idealized trumpet-shaped estuary morphology, to illustrate key processes giving rise to flood/ebb dominance. Observations made in the main entrance channel to the Dyfi indicate that the system is presently ebb-dominant with regard to both the relatively long duration of the ebb tide and also the faster ebb velocities. Predictions made across the mouth of the estuary using the Telemac Modelling System suggest further that the net sand transport presently occurs out of the estuary. In contrast, due to the varying distribution of channels and flats within the estuary, the tidal flow in the upper estuary is flood-asymmetric and here the net transport is up-estuary. Flood versus ebb dominance is shown to be attributable to the relative extent of the channels and sandflats in relation to the mean water level. An attempt is made to develop a simple metric to determine present-day transport pathways within an estuary in response to its cross-channel flow asymmetries.

Brown, J. M.; Davies, A. G.

2010-01-01

364

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

Science.gov (United States)

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

365

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

Science.gov (United States)

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

366

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

Energy Technology Data Exchange (ETDEWEB)

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

Johnson, Gary E.; Diefenderfer, Heida L.

2008-09-29

367

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-09-29

368

A review of land-sea coupling by groundwater discharge of nitrogen to New England estuaries: Mechanisms and effects  

International Nuclear Information System (INIS)

Hydrologists have long been concerned with the interface of groundwater flow into estuaries, but not until the end of the last century did other disciplines realize the major role played by groundwater transport of nutrients to estuaries. Mass balance and stable isotopic data suggest that land-derived NO3, NH4, and dissolved organic N do enter estuaries in amounts likely to affect the function of the receiving ecosystem. Because of increasing human occupancy of the coastal zone, the nutrient loads borne by groundwater have increased in recent decades, in spite of substantial interception of nutrients within the land and aquifer components of watersheds. Groundwater-borne nutrient loads have increased the N content of receiving estuaries, increased phytoplankton and macroalgal production and biomass, decreased the area of seagrasses, and created a cascade of associated ecological changes. This linkage between land use and eutrophication of estuaries occurs in spite of mechanisms, including uptake of land-derived N by riparian vegetation and fringing wetlands, 'unloading' by rapid water removal, and direct N inputs to estuaries, that tend to uncouple the effects of land use on receiving estuaries. It can be expected that as human activity on coastal watersheds continues to increase, the role of groundwater-borne nutrients to the receiving estuary will also increase

369

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

Science.gov (United States)

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

370

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

International Nuclear Information System (INIS)

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

371

User's guide and metadata for WestuRe: U.S. Pacific Coast estuary/watershed data and R tools  

Science.gov (United States)

There are about 350 estuaries along the U.S. Pacific Coast (U.S. Fish andWildlife 2011). Basic descriptive data for these estuaries, such as their size and watershed area, are important for coastal-scale research and conservation planning. However, this information is spread among many sources, making it difficult to find and standardize. The goal of the WestuRe Project is to provide a framework to: (1) make general descriptive data for estuaries and their watersheds more accessible, and (2) provide tools to make analyzing and visualizing these data easier. The WestuRe download includes data describing U.S. Pacific Coast estuaries and their corresponding watersheds from northern Washington (including the region located along the Strait of Juan de Fuca that goes from Port Townsend to Cape Flattery, 48.383°N) to southern California (Tijuana Estuary,

Frazier, M.R.; Reusser, D.A.; Lee, H., II; McCoy, L.M.; Brown C.; Nelson, W.

2013-01-01

372

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

International Nuclear Information System (INIS)

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

373

Variability in waterfowl distribution within hypertidal estuaries in relation to sediments  

International Nuclear Information System (INIS)

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

374

PSE and G's Estuary Enhancement Program restoration of the Dennis Township Salt Hay Farm  

International Nuclear Information System (INIS)

In July 1994, the New Jersey Department of Environmental Protection (NJDEP) issued a final New Jersey Pollutant Discharge Elimination System Permit for Public Service Electric and Gas Company's (PSE and G) Generating System. This permit included several special conditions that addressed concerns about loss of aquatic organisms resulting from the Station's once-through cooling system and the potential impacts to the sustained health of the Delaware Estuary ecosystem. One special condition was to restore, enhance, and preserve a minimum of 8,000 acres of degraded wetlands along the Delaware Estuary. PSE and G's Estuary Enhancement Program is the largest salt marsh restoration project in the US. This project will significantly increase the number of acres of health, salt marsh along the Delaware River, will greatly increase the available habitat for fish production, and will increase the green space available to the public for varied recreational and educational uses

375

A survey of radioactivity in the Ribble Estuary. I: Activity concentrations and estuarine dynamics  

International Nuclear Information System (INIS)

Activity concentrations of Sellafield-derived (137Cs, 241Am, 238Pu and 238,240Pu) and Springfields-derived (234mPa, 234Th, uranium and thorium) radionuclides in surface sediments were measured at sites throughout the Ribble Estuary between September, 1991 and January, 1993. Measurements were made during periods when BNFL, Springfields were discharging effluent from the processing of uranium ore concentrates (UOC) and during periods following shutdown of the process. The activity concentrations measured agreed well with observations made by other workers. The geology of the Ribble Estuary catchment made only a small contribution to the measured radionuclide activity concentrations. Sellafield-derived radionuclides exhibited a well defined relationship with grain-size (% -1 for 234mPa, were seen in fine-grained sediments deposited near the tidal limit of the Ribble Estuary and Savick Brook. (author)

376

Identification of the toxic constituents of sediments in a Brazilian subtropical estuary.  

Science.gov (United States)

Phase 1 of the TIE method was applied to samples of elutriates from sediments of the Itajaí-Açu estuary and adjacent coastal region in southern Brazil. Embryo-larval toxicity assays were used with the sea urchin Arbacia lixula in samples of raw elutriate, and treated with Ulva fasciata, EDTA and sodium thiosulfate. Inside the estuary, ammonia was responsible for more than 40% of the toxicity in both the dredged and undredged regions. A toxicity gradient was observed, between the estuary and the coastal region, with an increase in the importance of metals for the latter. Temporally, there is strong evidence of the influence of dredging and disposal of sediments in the contamination of the coastal dumping site. The results indicating that this area presents limitations in its saturation capacity. Chemical analysis indicated the metal Cu is probably responsible for the toxicity of the sediments observed, without the interference of ammonia. PMID:24503379

Poleza, Fernanda; Souza, Rafael C; Resgalla, Charrid

2014-03-15

377

Mercury distribution in contaminated surface sediments from four estuaries, khuzestan shore, north part of persian gulf.  

Science.gov (United States)

The distribution of mercury in surface sediment from four estuaries along the Khuzestan shore, north part of Persian Gulf, was measured. The concentration of mercury varied among sampling stations (p sediments from Musa estuary. The percentage of mercury associated with different fractions in the sediment from all stations were in the order of residual (70.4 %) > organic matter (16.6 %) > easily and exchangeable (2.2 %) > acid reduction (0.8 %). I geo values calculated for mercury (1.5) showed higher values in Musa estuary than in the other stations. The bioavailability of mercury in sediments could be controlled by physicochemical factors such as pH, oxidation and reduction potential, organic carbon content and cation exchange capacity. PMID:25186811

Sarasiab, Abdolah Raeisi; Hosseini, Mehdi; Mirsalari, Zohreh

2014-11-01

378

Sediment-water distribution of perfluorooctane sulfonate (PFOS) in Yangtze River Estuary.  

Science.gov (United States)

Analysis of Perfluorooctane sulfonate (PFOS) distribution in water and sediment in Yangtze River Estuary showed that the estuary was a sink for PFOS. Salinity was an important parameter in controlling the sediment-water interactions and the fate or transport of PFOS in the aquatic environment. As the salinity (S per thousand) increased from 0.18 to 3.31, the distribution coefficient (K(d)) between sediment and water linearly increased from 0.76 to 4.70 L g(-1). The study suggests that PFOS may be carried with the river water and transported for long distances before it reaches to the sea and largely scavenged to the sediment in the estuaries due to the dramatic change in salinity. PMID:20170997

Pan, Gang; You, Chun

2010-05-01

379

Runoff and flocculation modify underwater light environment of the Hudson River Estuary  

Science.gov (United States)

Spectral quality of underwater irradiance was measured in the Hudson River Estuary at ten stations, which ranged from Albany to Battery Park, Manhattan. Incoming light is attenuated by a large, fluctuating load of terrigenous sediments and by phytoplankton. Photic depth ranged from only 0·6 m in late winter to 4·3 m in summer. All but the yellow and red wavelengths are eliminated near the surface. Much of the suspended material flocculates and settles within a day or more of standing in the laboratory. Floc patterns were also observed in the estuary from the air. Light transmission improves during the summer interval in direct proportion to the size of the algal crop, as measured by chlorophyll concentration. Circumstantial evidence indicates a self-clearing system which is based on co-flocculation of algae with clays and fine silts. The study suggests that a clearer estuary is possible when inputs of algal nutrients and suspended solids are managed.

Stross, R. G.; Sokol, R. C.

1989-10-01

380

Trace element contamination in the Guadalquivir River Estuary ten years after the Aznalcóllar mine spill.  

Science.gov (United States)

Sediments, clams Scrobicularia plana and worms Hediste diversicolor from the Guadalquivir estuary were collected ten years after the Aznalcóllar mine spill and analyzed for metals. Significant seasonal and spatial effects were detected for most elements, so data from different sampling periods and locations were treated separately. Overall, the most polluted sites were found upstream, although Zn and Cu tended to accumulate at the estuary mouth. A significant decline of Zn in sediments and clams was observed compared to levels reported following the spill, so the estuarine ecosystem has recovered. However, the concentrations of some elements in S. plana were still higher than those of heavily contaminated regions. In this mollusk, Pb and As levels were higher in 2008 than in previous years, suggesting a new source entering into the estuary. Metals in sediments presented low bioavailability for biota, so other sources must account for the concentrations observed in these species. PMID:25048729

Tornero, Victoria; Arias, Alberto M; Blasco, Julián

2014-09-15

 
 
 
 
381

Trace metals in the estuary of the Seine and its approaches  

International Nuclear Information System (INIS)

The distribution and behaviour of trace metals (Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Ti, V and Zn) were studied in the waters and deposited or suspended sediments of the estuary and eastern bay of the Seine river. The various physico-chemical forms - hydrosoluble, exchangeable, chelated, organic forms, were determined by successive fractionations. The abundance of the ionic stock in the estuary cannot explain the decrease of trace metal contents by purely chemical processes. Mixing processes with open sea particles and release of metals induced by the erosion-sedimentation cycles resulting in sediment washing can explain the observations. Metals first trapped in the sediments are freed in the dissolved state; they can be expelled from the estuary and participate in the biological cycles. In the bay sediments, the trace metals were used as tracers of sediment masses, allowing to determine the river deposit areas. The human contribution to trace metal deposits in the Seine river bay was also estimated. (author)

382

The effect of a storm surge event on the macrophytes of a temporarily open/closed estuary, South Africa  

Science.gov (United States)

Temporarily open/closed estuaries typically open to the sea due to freshwater inflow coupled with storm surge events. In September 2008, in the absence of freshwater inflow, the mouth of the East Kleinemonde Estuary breached in response to a storm surge. The mouth of the estuary closed the following day at a high level. Marine overwash events following the breach introduced large volumes of saline water into the estuary and raised the water level by 0.07-0.33 m. Salinity was significantly higher in the 15 month closed phase after the breach (31 ± 0.9) compared to 21.9 ± 0.9 in the closed brackish phase before the breach. The historical average salinity for the estuary during a closed period is 23-25. The increase in salinity has reduced submerged macrophytes Ruppia cirrhosa and Chara vulgaris cover by 38.1%. Macroalgal cover of species such as Dictyota dichotoma, Caulacanthus ustulatus, Codium tenue and Ulva spp. have increased by 7.9%. The saline high water levels have also