WorldWideScience
1

Impact of climate change on Gironde estuary  

International Nuclear Information System (INIS)

Within the THESEUS European project, a simplified mathematical model for storm surge levels in the Bay of Biscay was adjusted on 10 events at Le Verdon using wind and pressure fields from CLM/SGA, so that the water levels at Le Verdon have the same statistic quantiles as observed tide records for the period [1960-2000]. A numerical model of the Gironde Estuary was used to evaluate future water levels at 6 locations of the estuary from Le Verdon to Bordeaux and to assess the changes in the quantiles of water levels during the 21. century using ONERC's pessimistic scenario for sea level rise (60 cm). The analysis of future storm surge levels shows a decrease in their quantiles at Le Verdon,, whereas there is an increase of the quantiles of total water levels. This increase is smaller than the sea level rise and gets even smaller as one enters farther upstream in the estuary. A series of flood maps for different return periods between 2 and 100 years and for four time periods ([1960-1999], [2010-2039], [2040-2069] and [2070-2099]) have been built for the region of Bordeaux. Quantiles of water levels in the flood plain have also been calculated. The impact of climate change on the evolution of flooded areas in the Gironde Estuary and on quantiles of water levels in the flood plain mainly depends on the sea level rise. Areas which are not currently flooded for low return periods will be inundated in 2100. The influence of river discharges and dike breaching should also be taken into account for more accurate results. (authors)

2

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

Science.gov (United States)

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

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

2013-12-01

3

EVOLUTION OF PARTICULATE CHLOROPHYLL IN THE GIRONDE ESTUARY  

OpenAIRE

The spatio-temporal evolution of particulate chlorophyll in suspension in the Gironde estuary has been studied by photo acoustic spectroscopy. Disapearance of fluvial chlorophyll has been observed in the upper part of the estuary ; it has been correlated with the increase in turbidity. Quantitative measurements have been tempted using calibration with algaes cultures of varying turbidity. Chlorophyll again appears near by the sea. Marine chlorophyll has a shifted spectrum relative to the fluv...

Merle, A.; Cherqaoui, A.; Brzezinski, L.

1983-01-01

4

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

International Nuclear Information System (INIS)

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

5

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.)

6

Turbidity in the fluvial Gironde Estuary (S-W France) based on 10 year continuous monitoring: sensitivity to hydrological conditions  

Science.gov (United States)

Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in the southwest France, the Gironde fluvial-estuarine systems has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and high-frequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low-water, inter-annual changes). Turbidity shows hysteresis loops at different time scales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the TMZ installation in the fluvial stations. Hydrological indicators of the persistence and turbidity level of the TMZ are also defined. The long-term evolution of these indicators confirms the influence of discharge decrease on the intensification of the TMZ in tidal rivers, and provides a tool to evaluate future scenarios.

Jalón-Rojas, I.; Schmidt, S.; Sottolichio, A.

2015-03-01

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

8

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

OpenAIRE

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

Do, Lan Anh

2012-01-01

9

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

Science.gov (United States)

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

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

2008-06-01

10

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

International Nuclear Information System (INIS)

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

11

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

Science.gov (United States)

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

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

12

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

13

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)

14

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 (Leman) 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 exchanges 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)

15

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

Science.gov (United States)

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

16

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

Science.gov (United States)

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

David, Valérie; Sautour, Benoît; Chardy, Pierre

2007-02-01

17

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

Science.gov (United States)

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

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

2014-05-01

18

Recording and chronology of a cadmium contamination by 137Cs in the Gironde estuary (SW France)  

International Nuclear Information System (INIS)

The detailed analysis of the Cd distribution coupled with 137Cs measurements have been conducted in a core recovered from a flood-tidal dock of the Bordeaux harbour. They enabled reconstruction and dating of the record of industrial contamination which has developed over recent decades. The cadmium distribution accurately reflects the different stages of activity of a foundry at Vivies-Decazeville. The 137Cs curve likely records the fallout of the nuclear tests performed between 1950 and 1970, and probably also the Chernobyl fallout, that has never been mentioned in the Southwest of France until now. (authors)

19

Tidal and fluvial controls on the morphological evolution of a lobate estuarine tidal bar: The Plassac Tidal Bar in the Gironde Estuary (France)  

Science.gov (United States)

This study shows the short-term sediment dynamics (2010) and the long-term morphological evolution (1905 to 2008) of a tidal sand bar emplaced in the Gironde Estuary, the Plassac Tidal Bar. This tidal sand bar was selected because it corresponds to a morphological category (lobate shape) that was not previously studied in the setting of estuarine bay-head deltas. A recent high-resolution bathymetric survey (2010) evidences the sediment transport pattern, inferred from the lee face orientation of subaqueous dunes. This sediment transport pattern, together with results from previous studies, explains the five main mechanisms for the tidal bar evolution identified from 29 bathymetric maps since 1905: namely, flood ramp infill, partial ebb shield breaching, lateral accretion of the ebb spits and ebb shield lengthening, generated by the merging of mini-flood lobes on the outer sides of the ebb spits. Lateral accretion seems to be a key-process of sediment accretion for lobate tidal sand bars. Most of the evolutions are explained by tidal processes, but a fluvial influence is evidenced by correlating the presence of mini-flood lobes (migrating seaward from the upper reaches of the bay-head delta) and the lengthening of the tidal bar with periods of high fluvial discharge. A ca. 25-year periodicity in both the fluvial discharge and the tidal bar width, length and volume variations is evidenced and suggests a climate control on the tidal bar evolution. A classification of lobate tidal sand bars is proposed in order to distinguish tide-dominated and wave-influenced sand bars emplaced in large estuary mouth or tidal inlets, from tide-dominated and fluvial-influenced sand bars emplaced in bay-head deltas.

Billy, Julie; Chaumillon, Eric; Féniès, Hugues; Poirier, Clément

2012-10-01

20

Persistent organic pollutants in a marine bivalve on the Marennes-Oléron Bay and the Gironde Estuary (French Atlantic Coast)-Part 1: Bioaccumulation.  

Science.gov (United States)

The aim of this study was to determine 1) the relevance of using the Pacific oyster Crassostrea gigas as a sentinel organism, at a juvenile stage, for polycyclic aromatic hydrocarbon (PAH) and persistent organic pollutant (polychlorobiphenyl, PCB, polybromodimethylether, PBDE, and organochlorine pesticide, OCP) contamination, 2) the potential levels of chemical organic contamination in the Marennes-Oléron Bay, and their potential sources and 3) the potential influence of physiological or environmental factors on contaminant body burdens in oysters. To this end, juvenile oysters purchased from an oyster hatchery were transplanted to a reference site, in Bouin, and to different transplantation sites in the Marennes-Oléron Bay, the first oyster production area in France, and in the Gironde Estuary, the biggest estuary in Occidental Europe. Transplantations were done during summer and winter. Whole oyster soft tissues from each site were analysed for PAHs, PCBs, PBDEs and OCPs. Results obtained with a transplantation period of 3months suggest that C. gigas, at the juvenile stage, is a relevant sentinel organism for short-term assessment of contamination for these contaminants. In addition, no significant effects of physiological factors on contaminant body burdens were observed. Principal component analysis revealed two distinct groups of contaminants (PAHs and OPCs, and PCBs and PBDEs) and three groups of sites: 1) the reference site, 2) Les Palles (LP) and Boyard (BOY) in winter and 3) all the other sites. The group of LP and BOY was clearly defined by the levels of PAHs and OCPs, suggesting higher levels of contamination of these chemical compounds on these sites, potentially due to local contamination sources. In addition, no relevant effects of physiological or environmental factors on contaminant body burdens were observed. Results suggest also a predominance of contaminants related to agricultural activities along the Marennes-Oléron Bay, and therefore, further studies on the presence of pesticides in this region should be considered. PMID:25440063

Luna-Acosta, A; Budzinski, H; Le Menach, K; Thomas-Guyon, H; Bustamante, P

2015-05-01

21

Persistent organic pollutants in a marine bivalve on the Marennes-Oléron Bay and the Gironde Estuary (French Atlantic Coast)-Part 2: Potential biological effects.  

Science.gov (United States)

Contaminant effects on defence responses of ecologically and economically important organisms, such as the Pacific oyster Crassostrea gigas, are likely to influence their ability to resist infectious diseases, particularly at the young stages. The aim of this study was to explore the potential relationships between organic contaminants accumulated in the soft tissues of juvenile oysters, defence responses and physiological condition. Oysters were transplanted during summer and winter periods in different sites in the Marennes-Oléron Bay, the first area of oyster production in France, and in the Gironde Estuary, the biggest estuary in Occidental Europe. Amongst the battery of biochemical and physiological biomarkers applied in the present work [superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), malondyaldehyde (MDA), catecholase, laccase and lysozyme in gills, digestive glands, mantle and haemolymph, glycogen, proteins and lipids in the digestive gland and the condition index at the whole-organism level], MDA and lysozyme in the digestive gland and SOD, GPx and laccase in plasma contributed in order to significantly discriminate the sites in which oysters bioaccumulated different levels of heavy polycyclic aromatic hydrocarbons (HPAHs), polychlorobiphenyls (PCBs), polybromodiphenylethers (PBDEs), dichlorodiphenyltrichloroethanes (DDTs) and lindane. These results strengthen the hypothesis that it is possible to differentiate sites depending on their contamination levels and biological effects by carrying out studies with transplanted juvenile oysters. In addition, correlations were found between antioxidant and immune-defence responses, and PAH and DDT body burdens in the first area of oyster production in France (the Marennes-Oléron Bay) and where considerable oyster mortalities have been reported. This result suggests that the presence of organic chemical contaminants in the Marennes-Oléron Bay may influence defence responses in juveniles of C. gigas, and, therefore, could influence their ability to resist infectious diseases. PMID:25666833

Luna-Acosta, A; Bustamante, P; Budzinski, H; Huet, V; Thomas-Guyon, H

2015-05-01

22

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).  

Science.gov (United States)

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 O(2) 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 O(2) saturations ( approximately 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 microg 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 microg 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 approximately 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. PMID:15626396

Baudrimont, M; Schäfer, J; Marie, V; Maury-Brachet, R; Bossy, C; Boudou, A; Blanc, G

2005-01-20

23

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

International Nuclear Information System (INIS)

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

24

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

25

Spatiotemporal variation of dissolved 238U in the Gironde fluvial-estuarine system (France)  

International Nuclear Information System (INIS)

Dissolved uranium (238UD) was measured within the Gironde fluvial-estuarine system (France), which is well known for its heavy metal pollution and its subsequent environmental effects. Dissolved 238U activities exhibit the highest levels and variability in the small watersheds of the Isle and Riou-Mort rivers, ascribed to low discharges and the occurrence of peculiar features (local U ore deposits; Permian layers). The major tributaries of the Gironde Estuary: Garonne, Lot and Dordogne, show rather stable 238UD, higher than the global mean riverine uranium activity. In the Gironde Estuary 238UD behaves conservatively along the river-estuary-ocean transect. Dissolved 238U distribution in the Gironde fluvial-estuarine system can be explained by the characteristics of considered drainage basins. There is no evidence of anthropogenic pollution

26

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)

The short-lived natural radionuclides 7Be (T1/2 = 53 days), 234Thxs (T1/2 = 24.1 days) and 210Pbxs (T1/2 = 22.3 years), i.e. 234Th and 210Pb in excesses of that supported within particles by the decay of their parent isotopes, were analysed in suspended particulate matter (SPM) to study the particle dynamics in the Gironde fluvial estuarine system (France), strongly impacted by heavy metal pollution. From surveys of this land-ocean interface in 2006 and 2007, we established a times series of these radioisotopes and of their activity ratios (7Be/210Pbxs and 234Th/210Pbxs ARs) in particles sampled under different hydrological conditions. The particulate 7Be/210Pbxs AR varies along the fluvial estuarine system mainly due to variations in 7Be activities, controlled by riverine, oceanic and atmospheric inputs and by resuspension of old 7Be-deficient sediments. These processes vary with river discharge, tidal cycle and season. Therefore, seasonal particle transport processes can be described using variations of the SPM 7Be/210Pbxs ARs. During high river discharge, the SPM 7Be/210Pbx ARs decrease from river to the ocean. The turbidity maximum zone (TMZ) is dispersed and the particles 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.

27

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

OpenAIRE

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 mesoz...

Bergeron, Jean-pierre

2006-01-01

28

Seasonal variations of selected biomarkers in sand gobies Pomatoschistus minutus from the Guadalquivir Estuary, Southwest Spain.  

Science.gov (United States)

Sand gobies, Pomatoschistus minutus, were collected monthly from September 2002 to August 2003 at a station situated 8 km upstream from the mouth of the Guadalquivir estuary (southwest Spain). Physical parameters of the water and selected biomarkers of organic pollution were recorded in the fish to discuss its potential as a sentinel species in estuaries. The biomarkers selected were the activities of catalase (CAT), 7-ethoxyresorufin-O-deethylase (EROD), and glutathione S-transferase (GST) in the liver and acetylcholinesterase (AChE) and lipid peroxidation (LP) in the head. The results showed an increase in total protein synthesis in late spring and early summer coinciding with the reproductive period as well as the release of fresh water from a dam situated 110 km upstream. During the same period, a significant depletion of hepatic GST and head AChE but higher LP levels in this tissue suggest exposure to pesticides such as those applied to crops established along the course of the river and reaching the estuary mostly when the freshwater discharges occur. Changes in CAT and EROD activities fluctuated randomly and were not noted as seasonally dependent. Biomarker fluctuations in sand goby are discussed as normal seasonal variations, but other variables-such as potential local pollution inputs-cannot be disregarded. PMID:16328622

Solé, M; Kopecka, J; Parra, L M García de la

2006-02-01

29

Estuaries  

Science.gov (United States)

An estuary is a body of water that is created when freshwater from rivers and streams flows into the saltwater of an ocean. To understand this mixing of fresh and salt water, learners go through several activities: 1) in Salt and Water, learners dissolve salt crystals in water to observe their effects on water; 2) in Making a Salt Wedge, learners make a model of a salt wedge estuary, which occurs in nature when the mouth of a river flows directly into seawater; 3) in Plant Dehydration learners observe the effects of salinity (salt content in the water) on live plants. Includes a wrap-up guide for group discussions.

New Jersey

2006-01-01

30

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

Science.gov (United States)

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

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

2014-12-01

31

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

Science.gov (United States)

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

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

2014-12-01

32

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

Science.gov (United States)

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

Sadri, Saeed S; Thompson, Richard C

2014-04-15

33

Behaviour of Organic Carbon in Nine Contrasting European Estuaries  

Science.gov (United States)

A cross-system comparison of organic carbon origin and behaviour in nine European estuaries is presented. The study sites display a very large range of hydrological and environmental conditions. The watershed of the respective estuaries were characterized by plotting the total organic carbon (TOC) in the rivers versus the inhabitants/discharge ratio. This allows to distinguish four types of watershed with regard to anthropogenic forcing and organic carbon levels: polluted by sewage inputs (Scheldt and to a much lesser extent, Ems, Sado and Thames), decontaminated (Elbe and Rhine), pristine (Gironde and Douro) and eutrophized (Loire and Scheldt). In the estuarine zone, dissolved organic carbon (DOC) almost always decreased linearly with increasing salinity. Exceptions were: the Scheldt, where a net consumption of sewage-derived DOC was observed, the Gironde, where a net production of DOC occurred in the maximum turbidity zone (MTZ) and the Sado and Ems, where DOC was supplied from large intertidal areas. By contrast, a large fraction of the riverine particulate organic carbon (POC) was mineralized in all the estuaries, except the Douro, where residence time of waters is only a few days. A fraction of POC appeared however refractory and accumulated in the MTZs, where terrestrial soil-derived material dominates (Elbe, Ems, Loire, Gironde and Sado). In the marine regions of most estuaries, autochthonous POC was present during spring and summer. The analysis of all river and estuarine data allows estimation of the loss of continental POC occurring in each estuary. It decreases in the following order: Scheldt?Thames>Ems=Sado=Loire>Gironde>Elbe>Rhine>Douro, which almost corresponds to the anthropogenic pressure in the respective watersheds. Two major variables appear to control the intensity of this mineralization: the origin of the POC, the lability increasing with pollution, and the residence time of particles in the estuarine zone.

Abril, G.; Nogueira, M.; Etcheber, H.; Cabeçadas, G.; Lemaire, E.; Brogueira, M. J.

2002-02-01

34

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

Science.gov (United States)

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

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

2012-08-01

35

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

Science.gov (United States)

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

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

2009-01-01

36

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.

37

Southwest Economy  

Science.gov (United States)

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

38

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

39

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.

40

Estuary regime  

International Nuclear Information System (INIS)

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

41

DYNAMIC ESTUARY MODEL PERFORMANCE  

Science.gov (United States)

Applications of the Dynamic Estuary Model (DEM) to both the Delaware and Potomac Estuaries by the Environmental Protection Agency during the 1970s are summarized and evaluated. Methods for calibrating, refining, and validating this model, and statistics for evaluating its perform...

42

Phytoplankton and bacterial alkaline phosphatase activities in relation to phosphate and DOP availability within the Gironde plume waters (Bay of Biscay)  

OpenAIRE

Previous studies conducted on the continental shelf in the Southeast Bay of Biscay influenced by Gironde waters (one of the two largest rivers on the French Atlantic coast) showed the occurrence of late winter phytoplankton blooms and phosphorus limitation of algal growth thereafter. In this context, the importance of dissolved organic phosphorus (DOP) for both algae and bacteria was investigated in 1998 and 1999 in terms of stocks and fluxes. Within the mixed layer, although phosphate decrea...

Labry, Claire; Delmas, Daniel; Herbland, Alain

2005-01-01

43

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

44

Preserving Southwest Virginia's Folklore.  

Science.gov (United States)

Describes Southwest Virginia's rich tradition of folklore and culture and the need for its preservation. Summarizes the author's time-consuming process of preparing an inventory and indexing the vast archival collections gathered by students in American Folklore classes at Mountain Empire Community College and by the Southwest Virginia Folklore…

Burgin, Ramond

1997-01-01

45

Restore America's Estuaries  

Science.gov (United States)

This non-profit organization promotes the restoration and protection of America's estuaries. Projects encompass scientific research, education and community-based action, including restoration by young students, as well as policy initiatives at the national level. An introduction to estuaries contains concise definitions, value in ecology and economics, current threats, and elements of restoration. Also offers: links to educational resources; news and photo gallery; a CD-rom guide to estuarine restoration.

46

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

OpenAIRE

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

Do, Lan Anh

2012-01-01

47

Estuaries: Finding the Balance  

Science.gov (United States)

This lesson will examine the conflict between development and the environment, and the attempts for a sound compromise while still helping the earth sustain the economic growth, expansion, and pressure we are exerting on its natural resources. Using estuaries as a case study, students will be encouraged to consider the interaction between environmental and economic demands, and to seek a balance that will protect both the estuarine habitat and economic growth.

48

¡Salud! Southwest Tour  

OpenAIRE

During this summer of 2009, 12 American medical students from the Escuela Latinoamericana de Medicina (ELAM – Latin American School of Medicine) in Havana, Cuba will board a Recreational Vehicle (RV) to travel across the Southwest region of the United States visiting a number of tribal settlements of American Indian Nations, community colleges and universities. While at the various sites the students will share their personal experiences of what it’s like to study at ELAM while promoting ...

Joanna Mae Mae Souers

2009-01-01

49

Go Southwest, Old Man  

OpenAIRE

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

Materassi, Mario

2009-01-01

50

¡Salud! Southwest Tour  

Directory of Open Access Journals (Sweden)

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

Joanna Mae Mae Souers

2009-06-01

51

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.

52

Have the bioavailabilities of trace metals to a suite of biomonitors changed over three decades in SW England estuaries historically affected by mining?  

Science.gov (United States)

Many estuaries of southwest England were heavily contaminated with toxic metals associated with the mining of copper and other metals, particularly between 1850 and 1900. The question remains whether the passage of time has brought remediation to these estuaries. In 2003 and 2006 we revisited sites in 5 metal-contaminated estuaries sampled in the 1970s and 1980s - Restronguet Creek, Gannel, West Looe, East Looe and Tavy. We evaluate changes in metal contamination in sediments and in metal bioavailabilities in sediments and water to local organisms employed as biomonitors. We find that the decline in contamination in these estuaries is complex. Differences in bioavailable contamination in the water column were detectable, as were significant detectable changes in at least some estuaries in bioavailable metal contamination originating from sediments. However, in the 100 years since mining activities declined, bioavailable contamination has not declined to the regional baseline in any estuary affected by the mine wastes. The greatest decline in contamination occurred in the one instance (East Looe) where a previous industrial source of (Ag) contamination was considered. We used the macroalgae Fucus vesiculosus and Ascophyllum nodosum as biomonitors of dissolved metal bioavailabilities and the deposit feeders Nereis diversicolor and Scrobicularia plana as biomonitors of bioavailable metal in sediments. We found no systematic decrease in the atypically high Ag, Cu, Pb and Zn concentrations in the estuarine sediments over a 26 year period. Accumulated metal (Ag, As, Cu, Pb, and Zn) concentrations in the deposit feeders are similarly still atypically high in at least one estuary for each metal, and there is no consistent evidence for general decreases in sediment metal bioavailabilities over time. We conclude that the legacy of mining in sheltered estuaries of southwest England is the ongoing presence of sediments rich in metals bioavailable to deposit feeders, while dissolved metal bioavailabilities from this historical source alone are no longer atypically high. PMID:21315427

Rainbow, P S; Kriefman, S; Smith, B D; Luoma, S N

2011-03-15

53

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...

54

Phosphorous speciation in surface sediments of the Cochin estuary.  

Science.gov (United States)

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

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

2013-03-01

55

Oil spill trajectory analysis for the Calcasieu Estuary  

International Nuclear Information System (INIS)

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

56

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

57

Birds of the Severn Estuary and Bristol Channel: their current status and key environmental issues.  

Science.gov (United States)

The Severn Estuary and Bristol Channel encompass a number of designated sites supporting populations of waterbirds and seabirds that are of national or international importance, including the Severn Estuary and Burry Inlet Special Protection Areas (SPAs)/Ramsar Sites and Carmarthen Bay, the UK's first marine SPA. Here, we provide an overview of the present numbers and trends of the waterbirds and seabirds using these sites, updating previous reviews undertaken prior to these designations. We further provide a summary of the main issues that have affected the status of the area's bird populations. Declines in the numbers of waders on the Severn Estuary and the southwest over the last two decades have been linked to climate change. The Sea Empress oil-spill impacted both breeding seabirds and the wintering Common Scoters in Carmarthen Bay, though numbers of the latter recovered 3years after the spill. At the Burry Inlet, Oystercatcher numbers have fallen over the last 25years and considerable research has been undertaken into the conflict with cockle and mussel fisheries. A long-term study at Cardiff Bay, at the mouth of the Severn, revealed a significant impact on the survival of Redshanks following its impoundment and has helped to further understanding of responses of waterbirds to estuarine habitat loss. The potential impacts of the construction of a tidal power scheme on the Severn Estuary are also discussed. PMID:20153484

Burton, N H K; Musgrove, A J; Rehfisch, M M; Clark, N A

2010-01-01

58

Bacterial growth efficiency in a tropical estuary: seasonal variability subsidized by allochthonous carbon.  

Science.gov (United States)

Bacterial growth efficiency (BGE) is a key factor in understanding bacterial influence on carbon flow in aquatic ecosystems. We report intra-annual variability in BGE, and bacteria-mediated carbon flow in the tropical Mandovi and Zuari estuaries (southwest India) and the adjoining coastal waters (Arabian Sea). BGE ranged from 3% to 61% and showed clear temporal variability with significantly (ANOVA, p estuaries (mean, 28 +/- 14%) than coastal waters (mean, 12 +/- 6%). The greater variability of BGE in the estuaries than coastal waters suggest some systematic response to nutrient composition and the variability of dissolved organic matter pools, as BGE was governed by bacterial secondary production (BP). Monsoonal rains and its accompanied changes brought significant variability in BGE and bacterial productivity/primary productivity (BP/PP) ratio when compared to nonmonsoon seasons in the estuaries and coastal waters. High BP/PP ratio (>1) together with high carbon flux through bacteria (>100% of primary productivity) in the estuarine and coastal waters suggests that bacterioplankton consumed dissolved organic carbon in excess of the amount produced in situ by phytoplankton of this region, which led to the mismatch between primary production of carbon and amount of carbon consumed by bacteria. Despite the two systems being subsidized by allochthonous inputs, the low BGE in the coastal waters may be attributable to the nature and time interval in the supply of allochthonous carbon. PMID:17356948

Pradeep Ram, A S; Nair, Shanta; Chandramohan, D

2007-05-01

59

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

60

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

61

Water quality in the Knysna estuary  

OpenAIRE

Measurements of water temperature, salinity, pH, dissolved oxygen, secchi disk depth, turbidity and total suspended solids were taken monthly in the Knysna estuary between 1991 and 1994. Measurements of turbidity and total suspended solids of waters entering the Knysna estuary via rivers and man-made inlets were also taken on an ad hoc basis. These results are described and compared to published data on past water quality conditions. No clear long-term changes in water quality in the estuary ...

Russell, I. A.

1996-01-01

62

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.

63

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

64

Snow in Southwest United States  

Science.gov (United States)

In late December, the Southwest was blanketed with snow, and this scence was captured by MODIS on December 27, 2001. The white drape contrasts sharply with the red rock of the Colorado Plateau, a geologic region made up of a succession of plateaus and mesas composed mostly of sedimentary rock, whose reddish hues indicate the presence of oxidized iron. The Plateau covers the Four Corners area of the Southwest, including (clockwise from upper left) southern Utah, Colorado, New Mexico, and Arizona. The region gets its name from the Colorado River, seen most prominently as a dark ribbon running southwest through southern Utah. At the upper left of the image, a bank of low clouds partially obscures Utah's Great Salt Lake, but its faint outline is still visible. To the east and southeast of the lake, some high peaks of the Wasatch Mountain range break free of the clouds. The Park City area, one of the 2002 Winter Olympic venues, can be seen poking through the cloud deck about 75km southeast of the lake. Farther east, the dark Uinta Mountains follow the border between Colorado and Wyoming. The Uinta are one of the rare east-west running ranges of the Rocky Mountains.

2002-01-01

65

Rapid rise in effective sea-level in southwest Bangladesh: Its causes and contemporary rates  

Science.gov (United States)

Evidence is presented from three estuarine tide gauges located in the Sundarban area of southwest Bangladesh of relative sea level rise substantially in excess of the generally accepted rates from altimetry, as well as previous tide-gauge analyses. It is proposed that the difference arises from the use of Relative Mean Sea Level (RMSL) to characterise the present and future coastal flood hazard, since RMSL can be misleading in estuaries in which tidal range is changing. Three tide gauges, one located in the uninhabited mangrove forested area (Sundarban) of southwest Bangladesh, the others in the densely populated polder zone north of the present Sundarban, show rates of increase in RMSL ranging from 2.8 mm a- 1 to 8.8 mm a- 1. However, these trends in RMSL disguise the fact that high water levels in the polder zone have been increasing at an average rate of 15.9 mm a- 1 and a maximum of 17.2 mm a- 1. In an area experiencing tidal range amplification, RMSL will always underestimate the rise in high water levels; consequently, as an alternative to RMSL, the use of trends in high water maxima or ‘Effective Sea Level Rise’ (ESLR) is adopted as a more strategic parameter to characterise the flooding hazard potential. The rate of increase in ESLR is shown to be due to a combination of deltaic subsidence, including sediment compaction, and eustatic sea level rise, but principally as a result of increased tidal range in estuary channels recently constricted by embankments. These increases in ESLR have been partially offset by decreases in fresh water discharge in those estuaries connected to the Ganges. The recognition of increases of the effective sea level in the Bangladesh Sundarban, which are substantially greater than increases in mean sea level, is of the utmost importance to flood management in this low-lying and densely populated area.

Pethick, John; Orford, Julian D.

2013-12-01

66

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.

67

Scouting contaminated estuaries: heavy metal resistant and plant growth promoting rhizobacteria in the native metal rhizoaccumulator Spartina maritima.  

Science.gov (United States)

Spartina maritima is a native endangered heavy metal rhizoaccumulator cordgrass naturally growing in southwest coasts of Spain, where is used as a biotool to rehabilitate degraded salt marshes. Fifteen bacterial strains were isolated from the rhizosphere of S. maritima growing in the estuary of the Tinto River, one of the most polluted areas in the world. A high proportion of bacteria were resistant towards several heavy metals. They also exhibited multiple plant growth promoting (PGP) properties, in the absence and the presence of Cu. Bacillus methylotrophicus SMT38, Bacillusaryabhattai SMT48, B. aryabhattai SMT50 and Bacilluslicheniformis SMT51 were selected as the best performing strains. In a gnobiotic assay, inoculation of Medicago sativa seeds with the selected isolates induced higher root elongation. The inoculation of S. maritima with these indigenous metal-resistant PGP rhizobacteria could be an efficient method to increase plant adaptation and growth in contaminated estuaries during restoration programs. PMID:25467875

Mesa, J; Mateos-Naranjo, E; Caviedes, M A; Redondo-Gómez, S; Pajuelo, E; Rodríguez-Llorente, I D

2015-01-15

68

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

69

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

70

USGS: Southwest Biological Science Center  

Science.gov (United States)

The Southwest Biological Science Center (SBSC) is "the newest of the 17 science centers that are part of the U.S. Geological Survey's Biological Resources Discipline." Research at the SBSC "includes water use and the effects of livestock grazing, wild land fires, invasive species, environmental contaminants, declining populations of native species, and urban development on the Southwest region." The four main research stations that operate under the auspices of the SBSC include the Canyonlands Research Station, Colorado Plateau Research Station, Grand Canyon Monitoring & Research Station, and Sonoran Desert Research Station. In addition to links to the different research station sites, the SBSC site contains contact information for its many staff members, and a Products Database with nearly 1,500 references for technical reports, journal articles, book chapters, webpages, and more. A number of the documents are available in PDF. Note: Sections of the website are still under development, and SBSC should be offering more information about its research activities in the future.

71

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

72

[Environmental characteristics of heavy metals in surface sediments from the Huanghe estuary].  

Science.gov (United States)

The contents of Cu, Pb, Zn, Cr, As and Hg in surface sediment from 14 sampling sites in the Huanghe estuary during July-August, 2011 were measured to investigate environmental geochemical characteristics of heavy metals related to multiple factors. The distribution, relationship with fine fraction and TOC, and sediment quality assessment concerning heavy metals were analyzed. The results showed that average concentrations of Cu, Pb, Zn, Cr, As and Hg in the Huanghe estuary were (16.5 +/- 2.7), (16.0 +/- 3.4), (21.0 +/- 3.3), (17.4 +/- 3.1), (6.5 +/- 1.2), (0.0444 +/- 0.0307) mg x kg(-1), respectively, which were lower than those in other typical areas along the coast of China. The distribution of metals displayed higher profiles in south than that in north of the Huanghe estuary, with a trend of increase seaward, especially for stations in southwest of the Laizhou bay. The insignificant correlation among metals indicated the complex sources of heavy metals in flood season. Pearson correlation was also conducted between metal contents and percentage of fine particulates and TOC, which was also insignificant, suggesting heavy metal concentration and distribution in the study region were also controlled by other factors except grain size and TOC. There was a good correlation between clay fraction and TOC (r = 0.724, P heavy metals in surface sediments from the Huanghe estuary implied a low probability of toxic effect, despite a sharp contamination trend pertaining to Hg and Pb since 1980s. PMID:23798109

Wu, Bin; Song, Jin-Ming; Li, Xue-Gang

2013-04-01

73

Estuaries.  

Science.gov (United States)

This publication is designed for use in standard science curricula to develop oceanologic manifestations of certain science topics. Included are teacher guides, student activities, and demonstrations designed to impart ocean understanding to high school students. When the student has completed this unit, he should be able to: (1) define an…

Awkerman, Gary L.

74

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

Science.gov (United States)

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

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

2007-11-01

75

ESTIMATING THE CONDITION OF GULF OF MEXICO ESTUARIES: NATIONAL COASTAL ASSESSMENT AND NATIONAL ESTUARY PROGRAM  

Science.gov (United States)

Estuaries in the Gulf of Mexico have been monitored since 1991 to determine the condition of water, sediment, and biota. More recently, through the National Coastal Assessment (NCA), U.S. EPA has provided a comprehensive estimate of the condition of U.S. estuaries, including a re...

76

The Estuary Book: A Guide to Promoting Understanding and Regional Management of Maine's Estuaries and Embayments.  

Science.gov (United States)

The objective of this document is to provide information about estuaries, the impact of uses on the environmental health of an estuary, and what communities and concerned individuals can do to manage and protect their local estuarine resources successfully. Much of the information presented here pertains to other embayments along the Maine coast…

Ruffing, Jenny

77

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

Science.gov (United States)

...Commission Notice of Staff Attendance at Southwest...Regional State Committee Meeting and Southwest Power Pool Board of Directors Meeting April 9, 2010. The...notice that members of its staff may attend the meetings of the Southwest...

2010-04-16

78

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

International Nuclear Information System (INIS)

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

79

Tidal currents assessment in the Tagus estuary  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-07-01

80

Environmental flow assessments for transformed estuaries  

Science.gov (United States)

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

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

2015-01-01

81

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

82

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)

83

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 (Tapi Estuary has impacted the coastal water of the Arabian Sea in recent years with fish kills attributed to its hypoxic/anoxic condition. Enhanced concentrations of nutrients and organic matter from indiscriminate discharge of sewage into the Tapi Estuary and restricted flushing as a result of construction of a series of dams in the catchment area of the estuary are the primary factors that have lead to the development of hypoxia.

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

2014-07-01

84

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

Science.gov (United States)

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

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

2013-12-01

85

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 phycocyanin-rich (Synechococcus-PC) dominant at lower salinities. Downstream stratification during monsoon caused Synechococcus group segregation in the surface and near-bottom waters. During monsoon-break and non-monsoon period stabilized waters, increased salinity, temperature, solar radiation and low rainfall favored high Synechococcus abundance whereas unstable waters, increased turbidity and low solar radiation during active monsoon lowered abundance. SYN-PC positively co-related with nitrate and phosphate and SYN-PEI with phosphate. Synechococcus contribution to phytoplankton carbon biomass ranged from 9 to 29%. In monsoonal estuaries, rainfall intensity regulates freshwater runoff which modulates the estuarine environment, creating temporal-spatial niche segregation of Synechococcus groups thereby serving as indicator organisms of the estuarine hydrodynamics. PMID:24094891

K M, Rajaneesh; Mitbavkar, Smita

2013-12-01

86

Radiological assessment of the Esk Estuary  

Energy Technology Data Exchange (ETDEWEB)

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

Howorth, J.M.; Barr, H.M.; Toole, J.; Strange, L.P.

1993-12-31

87

BCG Approaches for Improved Management of Estuaries  

Science.gov (United States)

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

88

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

International Nuclear Information System (INIS)

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

89

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

90

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

Science.gov (United States)

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

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

1989-12-01

91

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

92

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

93

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

94

Historical changes in the Columbia River Estuary  

Science.gov (United States)

Historical changes in the hydrology, sedimentology, and physical oceanography of the Columbia River Estuary have been evaluated with a combination of statistical, cartographic, and numerical-modelling techniques. Comparison of data digitized from US Coast and Geodetic Survey bathymetric surveys conducted in the periods 1867-1875, 1926-1937, and 1949-1958 reveals that large changes in the morphology of the estuary have been caused by navigational improvements (jetties, dredged channels, and pile dikes) and by the diking and filling of much of the wetland area. Lesser changes are attributable to natural shoaling and erosion. There has been roughly a 15% decrease in tidal prism and a net accumulation of about 68 × 10 6m 3 of sediment in the estuary. Large volumes of sediment have been eroded from the entrance region and deposited on the continental shelf and in the balance of the estuary, contributing to formation of new land. The bathymetric data indicate that, ignoring erosion at the entrance, 370 to 485 × 10 6m 3 of sediment has been deposited in the estuary since 1868 at an average rate of about 0.5 cm y -1, roughly 5 times the rate at which sea level has fallen locally since the turn of the century. Riverflow data indicate that the seasonal flow cycle of the Columbia River has been significantly altered by regulation and diversion of water for irrigation. The greatest changes have occurred in the last thirty years. Flow variability over periods greater than a month has been significantly damped and the net discharge has been slightly reduced. These changes in riverflow are too recent to be reflected in the available in the available bathymetric data. Results from a laterally averaged, multiple-channel, two-dimensional numerical flow model (described in HAMILTON, 1990) suggest that the changes in morphology and riverflow have reduced mixing, increased stratification, altered the response to fortnightly (neap-spring) changes in tidal forcing, and decreased the salinity intrusion length and the transport of salt into the estuary. The overall effects of human intervention in the physical processes of the Columbia River Estuary (i.e. decrease in freshwater inflow, tidal prism, and mixing; increase in flushing time and fine sediment deposition, and net accumulation of sediment) are qualitatively similar to those observed in less energetic and more obviously altered estuarine systems. A concurrent reduction in wetland habitats has resulted in an estimated 82% reduction in emergent plant production and a 15% reduction in benthic macroalgae production, a combined production loss of 51,675 metric tons of organic carbon per year. This has been at least partially compensated by a large increase in the supply of riverine detritus derived from freshwater phytoplankton primary production. Comparison of modern and estimated preregulation organic carbon budgets for the estuary indicates a shift from a food web based on comparatively refractory macrodetritus derived from emergent vegetation to one involving more labile microdetritus derived from allochthonous phytoplankton. The shift has been driven by human-induced changes to the physical environment of the estuary. While this is a relatively comprehensive study of historical physical changes, it is incomplete in that the sediment budget is still uncertain. More precise quantification of the modern estuarine sediment budget will require both a better understanding of the fluvial input and dredging export terms and a sediment tranport model designed to explain historical changes in the sediment budget. Oceanographic studies to better determine the mechanisms leading to the formation of the turbidity maximum are also needed. The combination of cartography and modelling used in this study should be applicable in other systems where large changes in morphology have occurred in historical time.

Sherwood, Christopher R.; Jay, David A.; Bradford Harvey, R.; Hamilton, Peter; Simenstad, Charles A.

95

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

Science.gov (United States)

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

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

2014-10-01

96

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

International Nuclear Information System (INIS)

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

97

Marine geology of the St. Lawrence Estuary  

International Nuclear Information System (INIS)

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

98

Eutrophication in a western Australian estuary  

OpenAIRE

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

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

1982-01-01

99

Tidal exchange between a freshwater tidal marsh and an impacted estuary: the Scheldt estuary, Belgium  

Science.gov (United States)

Tidal marsh exchange studies are relatively simple tools to investigate the interaction between tidal marshes and estuaries. They have mostly been confined to only a few elements and to saltwater or brackish systems. This study presents mass-balance results of an integrated one year campaign in a freshwater tidal marsh along the Scheldt estuary (Belgium), covering oxygen, nutrients (N, P and Si), carbon, chlorophyll, suspended matter, chloride and sulfate. The role of seepage from the marsh was also investigated. A ranking between the parameters revealed that oxygenation was the strongest effect of the marsh on the estuarine water. Particulate parameters showed overall import. Export of dissolved silica (DSi) was more important than exchange of any other nutrient form. Export of DSi and import of total dissolved nitrogen (DIN) nevertheless contributed about equally to the increase of the Si:N ratio in the seepage water. The marsh had a counteracting effect on the long term trend of nutrient ratios in the estuary.

Van Damme, Stefan; Frank, Dehairs; Micky, Tackx; Olivier, Beauchard; Eric, Struyf; Britta, Gribsholt; Oswald, Van Cleemput; Patrick, Meire

2009-11-01

100

Tidal Propagation in a Branching Tidal Estuary  

Science.gov (United States)

In branching tidal systems, tidal dissipation, propagation and reflection together define the spatial distribution of tidal energy. When specific locations or regions are altered, for example through the restoration of tidal marsh, there is uncertainty as to how the system will respond, including the spatial influence of the changes. When tidal marsh habitat is restored, it creates local tidal dissipation which may alter tidal energy in other parts of the estuary, potentially altering the function of tidal marshes elsewhere. It is important that this interaction be analyzed and understood before management decisions are made. We present results of a simple analytic model of tidal propagation in a branching system. We develop wave equations for along-channel velocity and wave height which account for friction and changes in channel geometry. By linearizing the friction term in the depth-averaged along-channel momentum equation and including an amplification factor in the wave form, then combining it with the continuity equation, we solve for wave speed and amplification as a function of friction and channel geometry. We also solve for the tidal velocity and stage as a function of position and time. Using this solution within an idealized branching channel estuary and applying matching conditions at the branches, we analyze the effects of changes to the geometry or reflection characteristics of one branch on tidal regimes throughout the estuary.

Wagner, R.; Stacey, M. T.

2012-12-01

101

Origin of suspended matter and sediment inferred from the residual metal fraction: Application to the Marennes Oleron Bay, France  

Science.gov (United States)

Total and HCl-available (extracted by HCl 1 M) trace metal (V, Cu, As, Cd, Pb and Th) concentrations were measured in suspended particulate matter (SPM) and surface sediments from the Garonne and the Charente Rivers (Southwest France), from their respective estuaries and from the adjacent coastal zone including the Marennes Oleron Bay. The objectives were to explore the potential of trace element signatures in the residual (non-reactive) fraction to trace the origin of particles, i.e. major contaminant carriers, in complex coastal systems. The observation period covered 12 months and a wide range of hydrological conditions. Selective extractions (HCl 1 M) showed that Pb, Cd and Cu in SPM and surface sediments from the entire system, including freshwater and marine environments, were highly reactive with potentially available fractions representing 64±13%, 60±18% and 43±13%, of the respective total metal concentrations. In contrast, V, As and Th showed low reactivity, with potentially available fractions lower than 19±7%, 11±3%, and 1.6±0.9%, respectively. Two combinations of Th-normalised (i.e. grain size corrected) metal concentrations in the residual fraction (Vres+Asres)/Thres and (Cdres+Cures+Pbres)/Thres represented two distinct signatures corresponding to the Charente and Garonne River endmembers. The respective Mres signals showed that both SPM and surface sediments sampled in the Marennes Oleron Bay mainly (>54%) originated from the Gironde Estuary watershed. Furthermore, SPM from the tidal ranges of the Charente Estuary contained close to 100% of particles from the Gironde watershed. These results, together with SPM flux estimates for the Charente River, suggest that particle transport from the Gironde Estuary to the Marennes Oleron Bay accounts for 81,000 t a-1-435,000 t a-1, representing 5-29% of the total SPM expulsed by the Gironde Estuary. Application of this novel approach to determine SPM and sediment origin to other aquatic environments may require adapting the choice and association of residual metal concentrations.

Dabrin, Aymeric; Schäfer, Jörg; Bertrand, Olivia; Masson, Matthieu; Blanc, Gérard

2014-01-01

102

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...

103

Nitrogen Source and Loading Data for EPA Estuary Data Mapper  

Science.gov (United States)

Nitrogen source and loading data have been compiled and aggregated at the scale of estuaries and associated watersheds of the conterminous United States, using the spatial framework in EPA's Estuary Data Mapper (EDM) to provide system boundaries. Original sources of data include...

104

WATER QUALITY MODELING IN THE RIO CHONE ESTUARY  

Science.gov (United States)

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

105

Approaches for Development of Nutrient Criteria in Oregon Estuaries With a Focus on Tillamook Estuary  

Science.gov (United States)

Development of nutrient criteria for all water body types of the US remains a top priority for EPA. Estuaries in the Pacific Northwest receive nutrients from both the watershed and the coastal ocean, and thus are particularly complex systems in which to establish water quality c...

106

Early Cambrian sipunculan worms from southwest China.  

OpenAIRE

We report the discovery of sipunculan worms from the Lower Cambrian Maotianshan Shale, near Kunming (southwest China). Their sipunculan identity is evidenced by the general morphology of the animals (sausage-shaped body with a slender retractable introvert and a wider trunk) and by other features, both external (e.g. perioral crown of tentacles, and hooks, papillae and wrinkle rings on the body surface) and internal (U-shaped gut, and the anus opening near the introvert-trunk junction). The t...

Huang, Di-ying; Chen, Jun-yuan; Vannier, Jean; Saiz Salinas, J. I.

2004-01-01

107

Impressions from South-West Uganda  

OpenAIRE

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 product...

Hardouin, J.

1987-01-01

108

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 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.

2013-12-01

109

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

Science.gov (United States)

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

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

2015-01-01

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

Dissolved vanadium in rivers and estuaries  

Science.gov (United States)

New measurements of dissolved vanadium in a variety of rivers and estuaries are presented here. The data indicate that the average concentration of dissolved vanadium in major rivers entering the ocean is ˜ 15 nmol/kg. Weathering rate and type of source rock, rather than solution chemistry or anthropogenic influences, appear to be the important factors in determining fluvial dissolved vanadium concentrations. Laboratory experiments suggest that in oxic waters vanadium is found predominantly in its most oxidized, anionic form (V(V)). Complexation with organic matter and formation of large colloidal species appear to be unimportant. Adsorption also appears to be a less important influence for vanadium than for some other trace elements such as zinc. In estuaries, vanadium behaves as a bioactive element, showing a close correspondence with the distribution of phosphate. The extent of estuarine vanadium removal is presently uncertain but may be low due to rapid remineralization of this element. Based on the river flux, the oceanic residence time for dissolved vanadium is estimated to be 100,000 years.

Shiller, Alan M.; Boyle, Edward A.

1987-12-01

112

Mercury distribution in Douro estuary (Portugal).  

Science.gov (United States)

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 <20 mg dm(-3), and concentrations of DOC in the range <1.0-1.8 mg dm(-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 approximately 7 microg g(-1) and the bottom waters were always <1 microg g(-1). Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 microg 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. PMID:15893331

Ramalhosa, E; Pereira, E; Vale, C; Válega, M; Monterroso, P; Duarte, A C

2005-11-01

113

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

114

Summer hypoxia adjacent to the Changjiang Estuary  

Science.gov (United States)

Changjiang, the third largest runoff in the world, empties into the East China Sea from Shanghai, the fastest developing area of China. With the increasing nutrient load from the river, a severe hypoxia zone was found to about 2 * 10 4 km 2. The mechanism of hypoxia formation adjacent to the Changjiang Estuary receives more and more attention from both scientists and managers. This paper discusses the relationship between hypoxia and the water masses, primary production, particulate material transport and the density stratification in these areas according to data obtained from a cruise in September, 2003. Hypoxia is formed by organic detritus decay. The particulate organisms do not mainly come from the Changjiang river, or from the dead algal deposed locally, but from the local benthic algae or particles advected from the south. Maintenance of hypoxia is due to the large density stratification caused by the significant salinity difference between the fresh plume and salty water from Taiwan Strait. This applies also to other estuaries with large runoff and rapid economic growth drainage, such as the Pearl River. It is suggested that the hypoxic zone here is much more sensitive than that outside Mississippi River. More cruises over different weather and tide conditions are needed to prove this hypothesis. Interdisciplinary research should be further developed in the future.

Wei, Hao; He, Yunchang; Li, Qingji; Liu, Zhiyu; Wang, Haitang

2007-09-01

115

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

116

The branching channel network in the Yangtze Estuary:  

OpenAIRE

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

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

2012-01-01

117

Study of the dynamic behaviour of the Sancti Petri Channel, southwest coast of Spain  

Directory of Open Access Journals (Sweden)

Full Text Available The dynamic behaviour of the Sancti Petri tidal channel (southwest coast of Spain, which is open at both ends and connected to water bodies with different dynamic characteristics (Atlantic Ocean and Cádiz Bay, is studied herein. This singular estuary is characterized by double inflow-outflow extremes, the tide penetrating almost simultaneously through both ends with a small difference of amplitude. For this study, sea level recordings were obtained from different points throughout the channel and the corresponding harmonic constituents were determined. The results show that the phases of the semidiurnal tides increase from the mouths to a zone located in the vicinity of the channel’s halfway point, while their amplitudes increase from the Atlantic Ocean to Cádiz Bay along the channel. A one-dimensional numerical model with geometry that is representative of the channel was used to reproduce the features observed for the semidiurnal and diurnal tidal constituents. The data supplied by the model were verified with values obtained at strategically chosen sites of the inner domain. The model developed may be used for operational predictions of tides in the study area, especially for the ports of Gallineras and Sancti Petri.

2005-01-01

118

Plutonium in Atlantic coastal estuaries in the southeastern United States  

International Nuclear Information System (INIS)

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

119

Monitoring Radio Frequency Interference in Southwest Virginia  

Science.gov (United States)

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

Rapp, Steve

2010-01-01

120

A Numerical Study of Coupled Estuary-shelf Circulation Around the Pearl River Estuary  

Science.gov (United States)

A three-dimensional, primitive equation regional ocean model (ROMS) is utilized to study the circulation, estuary-shelf water exchange rate and buoyant plume in a coupled estuary-shelf system around the Pearl River Estuary (PRE) during upwelling period. Their responses to the variation and interaction of the wind, tide and buoyancy forcing are investigated by several “process-oriented” sensitivity tests after the model performance is validated by the available tidal gauge data. By comparing the simulation results with dynamic analysis under different forcing conditions, we find that the currents are rather steady and mainly flow seaward in the narrower and shallower upper PRE, while they are more complex and variable in the wider and deeper lower PRE, for the circulation pattern is influenced by wind, tide, buoyancy and the coastal intrusion currents in the deep channel and around the entrance of the PRE, and the stratification has distinct spring-neap cycle, which leads to the asymmetry of flooding-ebbing current during neap and advance/retreat of the ebbing/flooding plume front during spring. Over the shelf the interactive roles of the topography, wind, tide and buoyancy forcing are shown by the unsymmetrical strength of the wind-driven coastal upwelling currents on the western and eastern shelf, and the different responses of the currents during upwelling relaxation. The net water transport between estuary and shelf is closely related with the variation of the along-shore wind, which indicates the importance of the shelf process in affecting the estuarine circulation, and the water exchange rate is evidently enhanced by upwelling favorable wind. The horizontal and vertical structures of the plume are modified by the shelf currents and the vertical mixing induced by tide and wind, and stronger mixing enhances the thickness but shrinks the horizontal size of the plume. In conclusion, the numerical results highlight the interaction between the estuary and shelf processes and the roles of the physical forcing on the dynamic processes in this coupled system.

Zu, T.; Gan, J.; Wang, D.

2010-12-01

121

Nutrient cycling and plant dynamics in estuaries: A brief review  

OpenAIRE

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

Flindt, Mogens R.; Pardal, Miguel A?ngelo; Lillebø, Ana Isabel; Martins, Irene; Marques, Joa?o Carlos

1999-01-01

122

Continuous resistivity profiling data from the Corsica River Estuary, Maryland  

Science.gov (United States)

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

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

2011-01-01

123

Juvenile salmon usage of the skeena river estuary.  

Science.gov (United States)

Migratory salmon transit estuary habitats on their way out to the ocean but this phase of their life cycle is more poorly understood than other phases. The estuaries of large river systems in particular may support many populations and several species of salmon that originate from throughout the upstream river. The Skeena River of British Columbia, Canada, is a large river system with high salmon population- and species-level diversity. The estuary of the Skeena River is under pressure from industrial development, with two gas liquefaction terminals and a potash loading facility in various stages of environmental review processes, providing motivation for understanding the usage of the estuary by juvenile salmon. We conducted a juvenile salmonid sampling program throughout the Skeena River estuary in 2007 and 2013 to investigate the spatial and temporal distribution of different species and populations of salmon. We captured six species of juvenile anadromous salmonids throughout the estuary in both years, and found that areas proposed for development support some of the highest abundances of some species of salmon. Specifically, the highest abundances of sockeye (both years), Chinook in 2007, and coho salmon in 2013 were captured in areas proposed for development. For example, juvenile sockeye salmon were 2-8 times more abundant in the proposed development areas. Genetic stock assignment demonstrated that the Chinook salmon and most of the sockeye salmon that were captured originated from throughout the Skeena watershed, while some sockeye salmon came from the Nass, Stikine, Southeast Alaska, and coastal systems on the northern and central coasts of British Columbia. These fish support extensive commercial, recreational, and First Nations fisheries throughout the Skeena River and beyond. Our results demonstrate that estuary habitats integrate species and population diversity of salmon, and that if proposed development negatively affects the salmon populations that use the estuary, then numerous fisheries would also be negatively affected. PMID:25749488

Carr-Harris, Charmaine; Gottesfeld, Allen S; Moore, Jonathan W

2015-01-01

124

Contamination and restoration of an estuary affected by phosphogypsum releases.  

Science.gov (United States)

The Huelva Estuary in Huelva, Spain, has been one of the most studied environmental compartments in the past years from the point of view of naturally occurring radioactive material (NORM) releases. It has been historically affected by waste releases, enriched in radionuclides from the U-decay series, from factories located in the area devoted to the production of phosphoric acid and phosphate fertilizers. Nevertheless, changes in national regulations forced a new waste management practice in 1998, prohibiting releases of phosphogypsum into the rivers. The input of natural radionuclides from phosphate factories to rivers was drastically reduced. Because of this there was a unique opportunity for the study of the response of a contaminated environmental compartment, specifically an estuary affected by tidal influences, after the cessation of the contaminant releases to, in this case, the Huelva Estuary (henceforth referred to as the Estuary). To investigate the environmental response to this new discharge regime, the specific activities of radionuclides 226Ra and 210Pb in water and sediment samples collected in four campaigns (from 1999 to 2005) were determined and compared with pre-1998 values. From this study it is possible to infer the most effective mechanisms of decontamination for the Estuary. Decontamination rates of 210Pb and 226Ra in the sediments and water have been calculated using exponential fittings and corresponding half-lives have been deduced from them. The cleaning half-life in the whole area of the Estuary is about 6 and 3.5 years for 226Ra and 210Pb respectively. The observed trend clearly shows that contamination of the Estuary by natural radionuclides is now decreasing and radioactive levels in waters and sediments are approaching the natural background references. This work attempts to evaluate whether it can be expected that the decontamination of the enhanced levels of natural radioactivity in the Estuary can be performed via natural processes. PMID:19822348

Villa, M; Mosqueda, F; Hurtado, S; Mantero, J; Manjón, G; Periañez, R; Vaca, F; García-Tenorio, R

2009-12-15

125

Contamination and restoration of an estuary affected by phosphogypsum releases  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-12-15

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

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

128

Columbia Bay, Alaska: an 'upside down' estuary  

Science.gov (United States)

Circulation and water properties within Columbia Bay, Alaska, are dominated by the effects of Columbia Glacier at the head of the Bay. The basin between the glacier terminus and the terminal moraine (sill depth of about 22 m) responds as an 'upside down' estuary with the subglacial discharge of freshwater entering at the bottom of the basin. The intense vertical mixing caused by the bouyant plume of freshwater creates a homogeneous water mass that exchanges with the far-field water through either a two- or a three-layer flow. In general, the glacier acts as a large heat sink and creates a water mass which is cooler than that in fjords without tidewater glaciers. The predicted retreat of Columbia Glacier would create a 40 km long fjord that has characteristics in common with other fjords in Prince William Sound. ?? 1988.

Walters, R.A.; Josberger, E.G.; Driedger, C.L.

1988-01-01

129

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 Ultrafiltration, high-resolution 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 Modeling, based on Visual MINTEQ version 3.0 and the Stockholm Humic Model after revision and updating, predicted that the dissolved (<0.45 ?m) 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

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

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

International Nuclear Information System (INIS)

The Ribble Estuary in the UK is contaminated by radionuclides derived from BNFL Sellafield and Springfield. Following the temporary shutdown of the Springfields plant, beta dose and gamma air kerma rates were measured at a range of sites in the estuary. Sediment surface samples were analysed for 137Cs, 234mPa, 234Th and 241Am activity concentrations by gamma spectrometry, 230Th and Pu isotopes by alpha spectrometry and sediment grain size (percentage 234Th/137Cs activity concentration ratio and calculating environmental beta dose rate and 234Th half-lives allow the estuary to be split into three areas: (a) upper estuary where fine grained sediments tend to be deposited during periods of low and average river flow; (b) middle reaches of the estuary which encompass most of the main channel sites where fine grained sediments are probably deposited and removed on most tides; (c) outer estuary including large areas of salt marshes which tend to accumulate fine grained sediment. This is confirmed by similar results derived from the 234Th/239,240234Th/239,240Pu ratio. (author)

133

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-07-01

134

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.

Prayaga Murty PRAGADA

2010-09-01

135

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

International Nuclear Information System (INIS)

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

136

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

Science.gov (United States)

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

2010-07-01

137

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

Science.gov (United States)

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

2010-07-01

138

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

Science.gov (United States)

...Administration Desert Southwest Customer Service Region-Rate Order No. WAPA-152...Regional Manager, Desert Southwest Customer Service Region, Western Area Power...Rates Manager, Desert Southwest Customer Service Region, Western Area...

2011-05-18

139

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

Science.gov (United States)

...Administration Desert Southwest Customer Service Region-Rate Order No. WAPA-151...Regional Manager, Desert Southwest Customer Service Region, Western Area Power...location is the Desert Southwest Customer Service Regional Office, 615...

2011-02-15

140

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

141

Sr in estuaries: Impact of Submarine Ground Water Discharge  

Science.gov (United States)

Submarine Groundwater Discharge (SGD) could be an important source of biogeochemical inputs into the coastal ocean either in form of fresh groundwater or re-circulated seawater. In the present study, an effort has been made to track the SGD along the western coast of India using dissolved Sr isotopes, a naturally occurring geochemical tracer, in three estuaries i.e. the Narmada, Tapi and the Mandovi. Dissolved Sr concentration and its isotope composition were measured in the Narmada, Tapi and the Mandovi estuary in the Arabian Sea along the salinity gradient. Sr concentrations varies from 1.4 to 77?M, 2.5 to 51 ?M and 0.7 to 82 ?M and 87Sr/86Sr display a range of 0.710761 to 0.709195, 0.708939 to 0.709152 and 0.710623 to 0.709118 in the Narmada, Tapi and the Mandovi estuaries respectively. Sr concentrations increase linearly with salinity in all three estuaries showing conservative mixing between seawater and river water Sr and the extrapolated Sr content at 35‰ salinity correspond to the global average seawater Sr. However, the mixing plots between 87Sr/86Sr versus 1/Sr clearly show systematic deviation from the theoretical mixing line towards higher salinity side, indicating non-conservative behaviour of Sr in the estuary. This observation is found in all the estuaries considered in this study, however, magnitude and direction of deviations from the expected mixing line are variable in different estuaries and depends on the continental 87Sr/86Sr in the particular estuary. Systematic deviation from the conservative mixing line observed for the Sr is possibly due the influence of submarine ground water discharge which supplies Sr with continental 87Sr/86Sr to the seawater at higher salinity side. As the continental Sr is more radiogenic compared to seawater in the Mandovi, SGD is causing a hump in the Sr mixing line where as 87Sr/86Sr decreases in case of the Tapi estuary compared to expected mixing line as its riverine 87Sr/86Sr is lower with respect to seawater. The location at which the SGD is impacting the seawater depends on the morphology of the river mouth, hydraulic gradient of the coastal aquifer and relationship between water table and local topography. Mass balance calculations estimate 2-6 % contribution of Sr from SGD in these estuaries. In addition to Sr, SGD could supply large amount of other trace elements and isotopes (TEIs) to the ocean and could influence significantly to the biogeochemical cycles of the TEIs.

Rahaman, W.; Singh, S. K.

2009-12-01

142

Desert Life in the American Southwest  

Science.gov (United States)

DesertUSA.com (DUSA) provides this interesting site, offering a plethora of general information on the deserts of the United States. Designed as an educational tool for discovering "the beauty, life and culture of North American deserts," the site contains illustrated text, factual summaries, virtual reality tours, movie/audio clips, and stories. All materials focus on desert-related topics, including plants, animals, geology, cultural and natural history, and parks, among others. The site has much to offer -- from the basics of the desert environment, to a photo-illustrated guide of desert flora and fauna, to details on specific arid and semi-arid deserts of the American Southwest. A glossary of desert terms and brief descriptions of features of the Chihuahuan, Great Basin, Mojave and Sonoran Deserts round out the site.

143

Early Cambrian sipunculan worms from southwest China.  

Science.gov (United States)

We report the discovery of sipunculan worms from the Lower Cambrian Maotianshan Shale, near Kunming (southwest China). Their sipunculan identity is evidenced by the general morphology of the animals (sausage-shaped body with a slender retractable introvert and a wider trunk) and by other features, both external (e.g. perioral crown of tentacles, and hooks, papillae and wrinkle rings on the body surface) and internal (U-shaped gut, and the anus opening near the introvert-trunk junction). The three fossil forms (Archaeogolfingia caudata gen. et sp. nov., Cambrosipunculus tentaculatus gen. et sp. nov. and Cambrosipunculus sp.) have striking similarities to modern sipunculans, especially the Golfingiidae to which their evolutionary relationships are discussed. This study suggests that most typical features of extant sipunculans have undergone only limited changes since the Early Cambrian, thus indicating a possible evolutionary stasis over the past 520 Myr. PMID:15306286

Huang, Di-Ying; Chen, Jun-Yuan; Vannier, Jean; Saiz Salinas, J I

2004-08-22

144

Insect fauna visiting carrion in Southwest Virginia.  

Science.gov (United States)

Successional patterns of insect fauna on pig carcasses were studied in southwest Virginia. The objective was to identify and qualitatively assess the major taxa of forensic importance in this region. Studies were conducted in spring and summer 2001 and 2002, and fall 2002. Over 50 taxa were collected and identified. Phormia regina was the dominant fly species in the spring (>90%) and co-dominant with Phaenicia coeruleiviridis in the summer. Phaenicia sericata, Lucilia illustris, and Calliphora spp. were collected in spring and summer, but less frequently. Eleven species of Sarcophagidae also were collected with Sarcophaga utilis and Helicobia rapax the most common. In the fall, the dominant fly species were Calliphora vomitoria, L. illustris, and P. coeruleiviridis. The primary beetle species collected in spring and summer included three Staphylinidae (Creophilis maxillosus, Platydracus maculosus, and Aleochara lata) and three Silphidae (Oiceoptoma noveboracense, Necrodes surinamensis, and Necrophila americana). No beetles were collected in the fall. PMID:15837010

Tabor, Kimberly L; Fell, Richard D; Brewster, Carlyle C

2005-05-28

145

Southwest Regional Partnership on Carbon Sequestration  

Energy Technology Data Exchange (ETDEWEB)

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

Brian McPherson

2006-04-01

146

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

147

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

OpenAIRE

The Mandovi estuary is a prominent water body that runs along the west coast ofIndia. It forms an estuarine network with the adjacent Zuari estuary, connected via the Cumbharjua canal. The physico-chemical conditions seen in the Mandovi estuary are influenced by two factors: the presence of several other groups of phytoplankton, the presence of which is yet to be reported in many other tropical estuaries. It includes chrysophytes, cyanobacteria, prasinophytes, prymnesiophytes and chlorophyte...

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

2013-01-01

148

Dynamics of intertidal flats in the Loire estuary  

Science.gov (United States)

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

Kervella, Stephane; Sottolichio, Aldo; Bertier, Christine

2014-05-01

149

Spatial distribution of subtidal Nematoda communities along the salinity gradient in two Southern European estuaries (Portugal).  

OpenAIRE

of two Portuguese estuaries exposed to different degrees of anthropogenic stress: the Mira and the Mondego. The nematode communities were mainly composed of Sabatieria, Metachromadora, Daptonema, Anoplostoma, Sphaerolaimus and Terschellingia species, closely resembling the communities of Northern European estuaries. In both estuaries, nematode density and community composition followed the salinity gradient, naturally establishing three distinct estuarine sections: (i) freshwater and olig...

Ada?o, Helena; Alves, A.; Patricio, J.; Neto, J. M.; Costa, M. J.; Marques, J. C.

2009-01-01

150

Metals in sediments and benthic organisms in the Mersey estuary  

Science.gov (United States)

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

Langston, W. J.

1986-08-01

151

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

152

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

153

Effects of heavy metal contamination on the macrobenthic fauna in estuaries: The case of the Seine estuary  

International Nuclear Information System (INIS)

Heavy metal contamination levels are generally higher in estuaries than in the open sea. Some estuaries, the Seine estuary for example, have particularly high pollution levels of metals, yet continue to support a very high benthic biomass and remain quite productive. Measurements of sediment contamination are highly variable due to diverse chemical analysis methods, sediments origin and sources of contaminants found in the estuaries. Salinity appears to be the principal factor controlling contaminant distribution in the sediment and the overlying and/or interstitial waters; it also affects the bioavailability of contaminants in estuarine sediments. Of course, the response to contaminants varies greatly among species and assemblages. Trace metals explain only a small part of the variation in benthic community structure. Some species, such as the shrimp Crangon crangon, appears vulnerable to metal pollution, while other species, such as Scrobicularia plana, are able to tolerate quite high levels of cadmium in their tissue. This paper demonstrates the wide variability of benthic responses to contamination, which is probably due to the high spatio-temporal heterogeneity of the estuary. To reduce the problems due the heterogeneity and variability observed to date in the available results, it will be necessary to encourage integrated estuarine studies, in which sedimentologists, chemists, and biologists work together on the same campaigns at the same sitespaigns at the same sites

154

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

Science.gov (United States)

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

Pye, Kenneth; Blott, Simon J.

2014-10-01

155

?-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)

156

Modern hydrological status of the estuary of Ili River  

Science.gov (United States)

The study addresses the problems and the history of formation and functioning of one of the largest intracontinental estuaries in Kazakhstan—the Ili River waterway. Being a natural regulator of the ecological status of the region, the estuary of Ili River also influences the water regime of Lake Balkhash. This work studied the current state of hydrographic and hydrological networks in a selected area and the distribution of water flow entering the estuary through the various ducts. Using a water balance method, this study calculated the loss of water in the delta, estimated runoff to the peak of delta and the inflow of river water into Lake Balkhash for two periods: the natural-conditioned and disturbed. As a result of the work performed, it was possible to trace the dynamics of hydraulic parameters for a multiyear period.

Dostay, Zhakupbay; Alimkulov, Sayat; Tursunova, Aisulu; Myrzakhmetov, Akhan

2012-09-01

157

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

International Nuclear Information System (INIS)

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

158

The validation of ecosystem models of turbid estuaries  

Science.gov (United States)

The ecosystem model of the Bristol Channel and Severn Estuary (GEMBASE) was fitted to 3 years of survey data, and has subsequently been validated against a further 5 years of monitoring data. A control chart technique clearly demonstrates that the model is, on the whole, an adequate representation of the estuarine carbon cycle, although the precision of model estimates reduces with increasing trophic level. An ecosystem model of the Ems Estuary has been adapted to simulate the Severn Estuary, and the impact of introducing a notional tidal power scheme assessed. The results were compared to those obtained using GEMBASE in the Severn. The broad predictions from both models are in agreement, although some detail is at variance, which implies that the fundamental ecological assumptions of the models are compatible.

Radford, P. J.; Ruardij, P.

1987-11-01

159

75 FR 61790 - Capital Southwest Corporation; Notice of Application  

Science.gov (United States)

...treatment of investment company insiders and the use of options and other rights by insiders to obtain control of the investment company; (b...Plan would not become a means for insiders to obtain control of Capital Southwest because...

2010-10-06

160

Use of marine space by Black-browed albatrosses during the non-breeding season in the Southwest Atlantic Ocean  

Science.gov (United States)

Marine birds like albatrosses have shown a profound deterioration of their conservation status in recent years. The Black-browed albatross (Thalassarche melanophris) is the most abundant threatened albatross species in the Southwest Atlantic continental shelf. Declines in their breeding populations have been largely attributed to the impact of incidental mortality in fisheries. Data on at-sea distribution for the species during breeding is abundant, but movements of individuals during winter are poorly known. Here, we investigate the at-sea distribution of Black-browed albatrosses during the non-breeding seasons 2011 and 2012. Eleven adult individuals were captured at-sea and equipped with satellite tags. Distribution of tracked Black-browed albatrosses was mostly restricted to waters within the continental shelf of Argentina, Uruguay and southern Brazil; from 29° to 51°S. Two large marine areas, comprising the ca. 90% of the core area (50% utilization distribution) were identified; one from the mouth of Rio de la Plata toward the E and SE reaching the shelfbreak, and another in El Rincón estuary and waters to the South. Tracked birds were distributed over nine oceanographic regimes in the SW Atlantic continental shelf, spending between 5 and 34% of their time at sea in marine fronts of high productivity such as Río de la Plata, Los Patos lagoon estuary front, the shelfbreak and the mixed front. The identified core areas could be considered as proxy indicators of priority areas at the time of implementing conservation measures for the species. The analysis of overlapping with fisheries on the Argentinean Continental Shelf will provide further insights about critical areas where those measures should be more stringent.

Copello, Sofía; Seco Pon, Juan Pablo; Favero, Marco

2013-05-01

161

Southwest Research Institute intensified detector development capability  

Science.gov (United States)

Imaging detectors for wavelengths between 10 nm and 105 nm generally rely on microchannel plates (MCPs) to provide photon detection (via the photo-electric effect) and charge amplification. This is because silicon-based detectors (CCD or APS) have near zero quantum detection efficiency (QDE) over this wavelength regime. Combining a MCP based intensifier tube with a silicon detector creates a detector system that can be tuned to the wavelength regime of interest for a variety of applications. Intensified detectors are used in a variety of scientific (e.g. Solar Physics) and commercial applications (spectroscopic test instrumentation, night vision goggles, low intensity cameras, etc.). Building an intensified detector requires the mastery of a variety of technologies involved in integrating and testing of these detector systems. We report on an internally funded development program within the Southwest Research Institute to architect, design, integrate, and test intensified imaging detectors for space-based applications. Through a rigorous hardware program the effort is developing and maturing the technologies necessary to build and test a large format (2k × 2k) UV intensified CCD detector. The intensified CCD is designed around a commercially available CCD that is optically coupled to a UV Intensifier Tube from Sensor Sciences, LLC. The program aims to demonstrate, through hardware validation, the ability to architect and execute the integration steps necessary to produce detector systems suitable for space-based applications.

Wilkinson, Erik; Vincent, Michael; Kofoed, Christopher; Andrews, John; Brownsberger, Judith; Siegmund, Oswald

2012-09-01

162

Materials of conference: Hydrogeological Problems of South-West Poland  

International Nuclear Information System (INIS)

Hydrogeological problems of South-west Poland is the collection of conference papers held in Szklarska Poreba on 20-22 June 1996. The materials have been gathered in three topical groups: water quality problems in hydrological cycle, regional hydrogeology of South-west Poland, theoretical problems and research methods in hydrogeology. More of performed articles have a interdisciplinary character taking into account the precipitation and surface water quality and their influence on ground water features

163

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.

164

Impacts of pesticides in a Central California estuary.  

Science.gov (United States)

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

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

2014-03-01

165

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

166

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

Science.gov (United States)

...ENERGY Federal Energy Regulatory Commission Notice of Staff Attendance at Southwest Power Pool Regional State Committee Meeting and...Committee, and SPP Board of Directors, as noted below. Their attendance is part of the Commission's ongoing outreach efforts....

2010-07-19

167

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

Science.gov (United States)

...ENERGY Federal Energy Regulatory Commission Notice of Staff Attendance at Southwest Power Pool Regional State Committee Meeting and...Committee, and SPP Board of Directors, as noted below. Their attendance is part of the Commission's ongoing outreach efforts....

2010-10-15

168

Flash flood awareness in southwest Virginia.  

Science.gov (United States)

Flash floods are one of the most dangerous weather-related natural disasters in the world. These events develop less than six hours after a rainfall event and create hazardous situations for people and extensive damage to property. It is critical for flash flood conditions to be warned of in a timely manner to minimize impacts. There is currently a knowledge gap between flood experts and the general public about the level of perceived risk that the latter has toward the powerful flood waters and how events should be warned of, which affects the communication capabilities and efficiency of the warning process. Prior research has addressed risk perception of natural disasters, but there is little emphasis on flash floods within flood-prone regions of the United States. This research utilizes an online survey of 300 respondents to determine the current state of flash flood awareness and preparation in southwest Virginia. Analysis of trends involved the use of chi-squared tests (chi2) and simple frequency and percentage calculations. Results reveal that a knowledge base of flash floods does exist, but is not advanced enough for proper awareness. Young adults have a lower understanding and are not as concerned about flood impacts. Increased exposure and perceived risk play a key role in shaping the way a person approaches flash floods. People do monitor flood events, but they are unaware of essential guidance and communication mechanisms. Finally, results suggest that the current method of warning about flash floods is not provided at an appropriate level of detail for effective communication. PMID:17362407

Knocke, Ethan T; Kolivras, Korine N

2007-02-01

169

Nutrient transport through estuaries: The importance of the estuarine geography  

Science.gov (United States)

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

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

2014-10-01

170

The tidal asymmetries and residual flows in Ems Estuary  

Science.gov (United States)

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

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

2014-12-01

171

PERSISTENCE OF AROCLOR (TRADE NAME) 1254 IN A CONTAMINATED ESTUARY  

Science.gov (United States)

The brief report summarizes the concentrations of PCB's in oyster tissue (Crassostrea virginica) observed from April 1969 to June 1976 at three locations in the Escambia Bay estuary, following elimination of an accidental leak of Aroclor 1254 from an industrial site. Data showed ...

172

Forward for book entitled "Estuaries: Classification, Ecology, and Human Impacts"  

Science.gov (United States)

The author was introduced to the science of estuaries as a graduate student in the early 1980s, studying the ecology of oyster populations in Chesapeake Bay. To undertake this research, he needed to learn not only about oyster biology, but also about the unique physical and chemi...

173

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)

174

Laboratory Investigations on Estuary Salinity Mixing: Preliminary Analysis  

Directory of Open Access Journals (Sweden)

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

F. H. Nuryazmeen

2014-05-01

175

Approaches for Development of Nutrient Criteria in Oregon Estuaries  

Science.gov (United States)

Development of nutrient criteria for all water body types of the US remains a top priority for EPA. Estuaries in the Pacific Northwest receive nutrients from both the watershed and the coastal ocean, and thus are particularly complex systems in which to establish water quality c...

176

COASTAL BEND BAYS & ESTUARIES PROGRAM IMPLEMENTATION REVIEW 2004  

Science.gov (United States)

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

177

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

Science.gov (United States)

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

178

Environmental flow assessments in estuaries related to preference of phytoplankton  

OpenAIRE

We developed an approach to assess environmental flows in estuaries related to preference of phytoplankton considering the complex relationship between hydrological modification and biomass in ecosystems. As a first step, a relationship was established between biomass requirements for organisms of primary and higher nutritional levels based on the principle of nutritional energy flow of ecosystem. Then, diagnostic pigments were employed to represent phytopl...

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

2014-01-01

179

CHEMICAL CONSTITUENTS OF AVICENNIA ALBA OF KRISHNA ESTUARY  

OpenAIRE

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.

Mvv, Ramanjaneyulu And Venkateswara Rao

2013-01-01

180

The dynamics of a frictionally-dominated Amazonian estuary  

Scientific Electronic Library Online (English)

Full Text Available 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

181

The dynamics of a frictionally-dominated Amazonian estuary  

Directory of Open Access Journals (Sweden)

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

Nils Edvin Asp

2012-09-01

182

Biogeochemical value of managed realignment, Humber estuary, UK  

International Nuclear Information System (INIS)

We outline a plausible, albeit extreme, managed realignment scenario ('Extended Deep Green' scenario) for a large UK estuary to demonstrate the maximum possible biogeochemical effects and economic outcomes of estuarine management decisions. Our interdisciplinary approach aims to better inform the policy process, by combining biogeochemical and socioeconomic components of managed realignment schemes. Adding 7494 ha of new intertidal area to the UK Humber estuary through managed realignment leads to the annual accumulation of a 1.2 x 105 t of 'new' sediment and increases the current annual sink of organic C and N, and particle reactive P in the estuary by 150%, 83% and 50%, respectively. The increase in intertidal area should also increase denitrification. However, this positive outcome is offset by the negative effect of enhanced greenhouse gas emissions in new marshes in the low salinity region of the estuary. Short-term microbial reactions decrease the potential benefits of CO2 sequestration through gross organic carbon burial by at least 50%. Net carbon storage is thus most effective where oxidation and denitrification reactions are reduced. In the Humber this translates to wet, saline marshes at the seaward end of estuaries. Cost-benefit analysis (CBA) was used to determine the economic efficiency of the Extended Deep Green managed realignment. When compared to a 'Hold-the-Line' future scenario, i.e. the present state/extent of sea defences inhe present state/extent of sea defences in the estuary, the CBA shows that managed realignment is cost effective when viewed on > 25 year timescales. This is because capital costs are incurred in the first years, whereas the benefits from habitat creation, carbon sequestration and reduced maintenance costs build up over time. Over 50- and 100-year timescales, the Extended Deep Green managed realignment scenario is superior in efficiency terms. The increased sediment accumulation is also likely to enhance storage of contaminant metals. In the case of Cu, a metal that currently causes significant water quality issues, Cu removal due to burial of suspended sediment in realigned areas translates to a value of approximately Pounds 1000 a-1 (avoided clean up costs). Although this is not formally included in the CBA it illustrates another likely positive economic outcome of managed realignment. Although we focus on the Humber, the history of reclamation and its biogeochemistry is common to many estuaries in northern Europe

183

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

184

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

Science.gov (United States)

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

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

2012-10-01

185

Flux of 238U and 232Th in Changjiang estuary  

International Nuclear Information System (INIS)

The study of fluxes of the U, Th of Changjiang River into the East China Sea and its adjacent waters is basic work to understanding of U, Th tracer theirselves and their corresponding biogeochemical cycles process in estuaries, coastal. By sampling in the Xuliujing (i.e. the interface between fresh water and sea water) every month, 200 L water was filtered through 0.45?m fabric cartridge to collect particle nuclides. The dissolved nuclides were co-precipitated using Fe(OH)3 and MnO2. The range of 238U activity in water is 2.30-10.32 Bq·m-3, with an average of 5.48±1.19 Bq·m-3; the activity of 232Th is 1.08-2.32 Bq·m-3, with an average of 1.75±0.29 Bq·m-3. Changjiang River conveyed 238U 4.06 x 1012Bq, 232Th 1.54 x 1012 Bq into the estuary every year. Further study of the seasonal variations 238U, 232Th input to the sea, indicating that: the activity of 238U and Changjiang River estuary water flux have a certain degree of negative correlation (R2=0.65, n=12); the main source of 232Th is the weathering of the river. The activity of 232Th is large on the spring and autumn because of strong weathering in Changjiang Basin comparison with other seasons. Compared with the other estuaries in the world, the flux of 238U and 232Th of the Changjiang River e2Th of the Changjiang River estuary is large because of its large fluxes of sediments and runoff in the world. (authors)

186

Salinity and turbidity distributions in the Brisbane River estuary, Australia  

Science.gov (United States)

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

Yu, Yingying; Zhang, Hong; Lemckert, Charles

2014-11-01

187

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

Directory of Open Access Journals (Sweden)

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

V. R. Shevchenko

2005-01-01

188

Difference in the crab fauna of mangrove areas at a southwest Florida and a northeast Australia location: Implications for leaf litter processing  

Science.gov (United States)

Existing paradigms suggest that mangrove leaf litter is processed primarily via the detrital pathway in forests in the Caribbean biogeographic realm whereas herbivorous crabs are relatively more important litter processors in the Indo-West Pacific. To test this hypothesis, we used pitfall traps to collect intertidal crabs to characterize the crab fauna in a mangrove estuary in southwest Florida. We also tethered mangrove leaves to determine if herbivorous crabs are major leaf consumers there. We compared the results with previously published data collected in an analogous manner from forests in northeastern Australia. The crab fauna in Rookery Bay, Florida, is dominated by carnivorous xanthid and deposit-feeding ocypodid crabs whereas that of the Murray River in northeastern Australia is dominated by herbivorous grapsid crabs. No leaves tethered at five sites in the forests in Southwest Florida were taken by crabs. This contrasts greatly with reported values of leaf removal by crabs in Australian forests of 28-79% of the leaves reaching the forest floor. These differences in the faunal assemblages and in the fate of marked or tethered leaves provide preliminary support for the hypothesis that leaf litter is in fact processed in fundamentally different ways in the two biogeographic realms.

McIvor, C.C.; Smith, T. J., III

1995-01-01

189

Residual fluxes of suspended sediment in a tidally dominated tropical estuary  

Science.gov (United States)

This paper assesses the fine sediment fluxes in the Caravelas estuarine system (Bahia, Brazil, 17o45'S and 039o12'W). The estuary reaches the ocean at the shore across from the Abrolhos Bank, the largest tropical reef habitat in the South Atlantic. The Caravelas estuarine system is composed of several meandering channels, which are connected to the ocean by a double inlet system. These two openings - the Caravelas and Nova Viçosa estuaries - are connected by a narrow, 30 km long channel. The Caravelas estuary does not receive significant continental input, while the Nova Viçosa estuary receives the contribution of the Peruíbe River, which drains an area of approximately 5000 km2. To understand the fine sediment dynamics and net transport, observations of tides, currents, salinity and suspended sediment concentration (SSC) were recorded in 13-h tidal surveys (spring and neap tide) and with 20-day long CTDs/ADCP moorings at the Caravelas estuary and in the interconnection channel. The SSC dynamic in the Caravelas estuary is primarily driven by advection, with SSC originating in the inlet and inner shelf area. Residual water and sediment transport are up-estuary in the Caravelas estuary and toward the Caravelas estuary in the interconnection channel. The residual transport showed pronounced synodical modulation and was stronger during spring tide. The Caravelas estuary function as a trap for inner shelf materials and fine sediments delivered by the Peruípe River at Nova Viçosa.

Schettini, Carlos Augusto França; Duarte Pereira, Marçal; Siegle, Eduardo; de Miranda, Luiz Bruner; Silva, Mário P.

2013-11-01

190

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

Science.gov (United States)

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

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

2014-04-01

191

Feeding preferences of estuarine mysids Neomysis integer and Rhopalophthalmus tartessicus in a temperate estuary (Guadalquivir Estuary, SW Spain)  

Science.gov (United States)

Mysid shrimps are an important component of estuarine food webs because they play a key role in energy transfer as intermediate prey. We investigated the seasonal, tidal and depth specific variation in the diet of the estuarine mysids Neomysis integer and Rhopalophthalmus tartessicus and explored its implications for the planktonic community structure of a temperate estuary (Guadalquivir Estuary, SW Spain). Neomysis integer is an opportunistic omnivore feeding mainly on mesozooplankton and on members of the detrital-microbial loop, shifting prey seasonally according to availability. In contrast, R. tartessicus showed a more carnivorous diet and shifted its target prey during seasons of low resource availability. Despite statistically significant differences in diet composition, both species shared prey of similar size, particularly juvenile Mesopodopsis slabberi, the most abundant mysid species in this estuary, and copepods. Although these similarities imply inter-specific resource competition, their co-existence is achieved by niche partitioning and spatial segregation: the higher osmoregulatory capacity and foraging plasticity of N. integer confers a broader niche breadth for this species allowing N. integer to inhabit the more stressful oligohaline region of the estuary where R. tartessicus cannot survive. We propose that this mechanism relaxes the potential for competition between N. integer and R. tartessicus.

Vilas, César; Drake, Pilar; Fockedey, Nancy

2008-04-01

192

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...

193

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...

194

Heavy metal assessment using geochemical and statistical tools in the surface sediments of Vembanad Lake, Southwest Coast of India.  

Science.gov (United States)

The geochemical distribution and enrichment of ten heavy metals in the surface sediments of Vembanad Lake, southwest coast of India was evaluated. Sediment samples from 47 stations in the Lake were collected during dry and wet seasons in 2008 and examined for heavy metal content (Al, Fe, Mn, Cr, Zn, Ni, Pb, Cu, Co, Cd), organic carbon, and sediment texture. Statistically significant spatial variation was observed among all sediment variables, but negligible significant seasonal variation was observed. Correlation analysis showed that the metal content of sediments was mainly regulated by organic carbon, Fe oxy-hydroxides, and grain size. Principal component analysis was used to reduce the 14 sediment variables into three factors that reveal distinct origins or accumulation mechanisms controlling the chemical composition in the study area. Pollution intensity of the Vembanad Lake was measured using the enrichment factor and the pollution load index. Severe and moderately severe enrichment of Cd and Zn in the north estuary with minor enrichment of Pb and Cr were observed, which reflects the intensity of the anthropogenic inputs related to industrial discharge into this system. The results of pollution load index reveal that the sediment was heavily polluted in northern arm and moderately polluted in the extreme end and port region of the southern arm of the lake. A comparison with sediment quality guideline quotient was also made, indicating that there may be some ecotoxicological risk to benthic organisms in these sediments. PMID:22068311

Selvam, A Paneer; Priya, S Laxmi; Banerjee, Kakolee; Hariharan, G; Purvaja, R; Ramesh, R

2012-10-01

195

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

Directory of Open Access Journals (Sweden)

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

Carlos Augusto França Schettini

2010-03-01

196

Southwest Florida shelf ecosystems study, Volume 1: Executive summary  

Energy Technology Data Exchange (ETDEWEB)

The 6-year Southwest Florida Shelf Ecosystems Program began in 1980 as an interdisciplinary study. The study area extends seaward from the west coast of Florida to the 200-meter isobath and from 27/degree/N latitude southward to the Florida Keys and Dry Tortugas. The region includes Florida Bay but not other estuarine areas. This area contains numerous live-bottom habitats and associated communities in a complex, patchy matrix. Live-bottom areas are often separated by wide expanses of sand or mud bottom areas. This report concludes the 6-year Southwest Florida Shelf Ecosystems Program's environmental study. The ultimate objective of the program was to determine the potential impact of OCS oil and gas offshore activities on live-bottom habitats and communities, which are integral components of the southwest Florida shelf ecosystems.

1987-04-01

197

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

198

A lightning climatology of the South-West Indian Ocean  

OpenAIRE

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

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

2012-01-01

199

Retail Demand Response in Southwest Power Pool  

Energy Technology Data Exchange (ETDEWEB)

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

Bharvirkar, Ranjit; Heffner, Grayson; Goldman, Charles

2009-01-30

200

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

Directory of Open Access Journals (Sweden)

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

M. Taufik Kaisupy

2006-04-01

201

[Phytoplankton assemblages in Yangtze River Estuary in the first sluice discharge duration of Three Gorges Dam in late spring].  

Science.gov (United States)

In June 15-25, 2003, the first sluice discharge duration of the Three Gorges Dam, water samples were taken from a grid of survey stations around the Yangtze River Estuary and its adjacent waters to analyze the characteristics of phytoplankton assemblages. In the survey area, the major phytoplankton groups were diatoms and dinoflagellates, and a few species belonging to Chrysophyceae and Chlorophyceae were observed. The cell abundance of the assemblages ranged from 0.2 to 1504.2 cells ml(-1), with an average of 72.7 cells ml(-1), and the dominant species were Skeletonema spp., Prorocentrum dentatum, and Scrippsiella trochoidea. The highest cell abundance was appeared in north diluted waters and southwest inshore waters. The cell abundance was the maximum in mid (10 m) water layer, and the minimum in bottom layer. In diluted waters, Skeletonema spp. was the dominant species, and mainly presented in surface water layer; while in the waters with the diluted water of Yangtze River and the mixed water of Taiwan Warmer Current and Yellow Sea, Prorocentrum dentatum dominated, and mainly distributed in surface and mid water layers. PMID:21774331

Sun, Jun; Zhao, Ran; Zhang, Li-yong

2011-04-01

202

33 CFR 207.200 - Mississippi River below mouth of Ohio River, including South and Southwest Passes; use...  

Science.gov (United States)

...Ohio River, including South and Southwest Passes...Ohio River, including South and Southwest Passes... Except in case of great emergency, no...Rouge, La., including South and Southwest Passes...12-inch black letters on a white background...

2010-07-01

203

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

OpenAIRE

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

Costa, Sonia; Azeiteiro, Ulisses; Pardal, Miguel

2013-01-01

204

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

OpenAIRE

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

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

2009-01-01

205

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

OpenAIRE

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

Ham, Joris L.; Mutsert, Kim

2014-01-01

206

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

OpenAIRE

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

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

1992-01-01

207

Response of Nereis diversicolor population (Polychaeta, Nereididae) to the pollution impact - Authie and Seine estuaries (France)  

Science.gov (United States)

A survey within the French National Programme of Ecotoxicology was carried out in 2002, 2003 and 2004 to study the response of Nereis diversicolor populations (Polychaeta, Nereididae) to the impact of pollution in the Authie estuary (non-contaminated site) and in the Seine estuary (contaminated site). In the period studied, the density varied from 672 ind. m -2 to 3584 ind. m -2 in the Authie estuary and from 80 ind. m -2 to 920 ind. m -2 in the Seine estuary. Biomass varied from 3.94 g m -2 (dry weight) in February 2004 to 38.0 g m -2 in August 2003 in the Authie estuary and from 3.4 g m -2 in February 2002 to 0.6 g m -2 in February 2004 in the Seine estuary. Density and biomass of the populations of N. diversicolor were consistently lower in the Seine estuary than in the Authie estuary. Size frequency histograms permit the analysis of the cohorts as well as the elaboration of the growth curves. For the individuals from the Authie estuary, the relation between dry weight (DW) and length L3 (prostomium, peristomium and chaetiger 1) was DW = 4.2205 L3 2.9832. For those from the Seine estuary, the relation between dry weight and L3 was DW = 0.4697e 1.7209L3. The individuals of N. diversicolor should belong to eight cohorts in Authie estuary (two cohorts each year) instead of six cohorts for those from the Seine estuary. These differences can be attributed to the effect of pollution on the population of N. diversicolor.

Gillet, P.; Mouloud, M.; Durou, C.; Deutsch, B.

2008-01-01

208

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

OpenAIRE

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

Harrold, Lydia Rebecca

2006-01-01

209

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

OpenAIRE

This paper reviews the current state of knowledge of the open waters of the San Francisco Estuary. This estuary is well known for the extent to which it has been altered through loss of wetlands, changes in hydrography, and the introduction of chemical and biological contaminants. It is also one of the most studied estuaries in the world, with much of the recent research effort aimed at supporting restoration efforts. In this review I emphasize the conceptual foundations for our current under...

Wim Kimmerer

2004-01-01

210

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

Science.gov (United States)

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

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

2014-11-01

211

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. PMID:22669343

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

2012-08-01

212

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

OpenAIRE

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 ...

Curt Peterson; Sandy Vanderburgh; Roberts, Michael C.

2014-01-01

213

40 CFR 81.255 - Southwest Kansas Intrastate Air Quality Control Region.  

Science.gov (United States)

...81.255 Southwest Kansas Intrastate Air Quality...Region. The Southwest Kansas Intrastate Air... In the State of Kansas: Barber County, Clark County, Comanche...County, Seward County, Stafford County, Stanton...

2010-07-01

214

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

Science.gov (United States)

...Regulatory Commission Notice of Staff Attendance at Southwest Power...Committee and Board of Directors Meetings The Federal Energy Regulatory...gives notice that members of its staff may attend the meetings of the Southwest Power...

2011-10-19

215

33 CFR 110.195 - Mississippi River below Baton Rouge, LA, including South and Southwest Passes.  

Science.gov (United States)

...false Mississippi River below Baton Rouge, LA, including South and Southwest...195 Mississippi River below Baton Rouge, LA, including South and Southwest...measured from the LWRP. (30) Baton Rouge General Anchorage. An area...

2010-07-01

216

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...public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include...land-use planning, invasive species management, energy...

2011-04-29

217

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...public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include...land use planning, invasive species management, energy...

2010-05-03

218

78 FR 62657 - Notice of Public Meeting, Southwest Colorado Resource Advisory Council  

Science.gov (United States)

...INFORMATION: The Southwest Colorado RAC advises the Secretary...public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include...land use planning, invasive species management, energy...

2013-10-22

219

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...public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include...land use planning, invasive species management, energy...

2010-02-05

220

78 FR 43915 - Notice of Public Meeting; Southwest Colorado Resource Advisory Council  

Science.gov (United States)

...INFORMATION: The Southwest Colorado RAC advises the Secretary...public land issues in Colorado. Topics of discussion for all Southwest Colorado RAC meetings may include...land use planning, invasive species management, energy...

2013-07-22

221

Nutrient cycling and plant dynamics in estuaries: A brief review  

Science.gov (United States)

Eutrophication of European estuaries due to massive nutrient loading from urban areas and diffuse runoff from extensively cultivated land areas is analysed. Consequences for the ecology of estuaries, namely changes in plant species composition, which also affects heterotrophic organisms, are approached based on examples showing that the result is often a fundamental structural change of the ecosystem, from a grazing and/or nutrient controlled stable systems to unstable detritus/mineralisation systems, where the turnover of oxygen and nutrients is much more dynamic and oscillations between aerobic and anaerobic states frequently occur. Several relevant aspects are examined, namely the influence of rooted macrophytes on nutrient dynamics, by comparing bare bottom sediments with eelgrass covered sediments, primary production and the development of organic detritus, and hydrodynamics and its relations to the spatial distribution of macrophytes in estuarine systems.

Flindt, Mogens R.; Pardal, Miguel Ângelo; Lillebø, Ana Isabel; Martins, Irene; Marques, João Carlos

1999-07-01

222

Estimation of bed shear stresses in the pearl river estuary  

Science.gov (United States)

Mean and fluctuating velocities were measured by use of a pulse coherent acoustic Doppler profiler (PC-ADP) and an acoustic Doppler velocimeter in the tidal bottom boundary layer of the Pearl River Estuary. The bed shear stresses were estimated by four different methods: log profile (LP), eddy correlation (EC), turbulent kinetic energy (TKE), and inertial dissipation (ID). The results show that (a) all four methods for estimating bed stresses have advantages and disadvantages, and they should be applied simultaneously to obtain reliable frictional velocity and to identify potential sources of errors; (b) the LP method was found to be the most suitable to estimate the bed stresses in non-stratified, quasi-steady, and homogeneous flows; and (c) in the estuary where the semi-diurnal tidal current is dominant, bed shear stresses exhibit a strong quarter-diurnal variation.

Liu, Huan; Wu, Jia-xue

2015-03-01

223

Multibiomarker assessment of three Brazilian estuaries using oysters as bioindicators  

International Nuclear Information System (INIS)

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

224

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

225

Effects of wave forcing on a subterranean estuary  

OpenAIRE

Wave and tide are important forcing factors that typically co-exist in coastal environments. A numerical study was conducted to investigate individual and combined effects of these forces on flow and mixing processes in a near-shore subterranean estuary. A hydrodynamic model based on the shallow water equations was used to simulate dynamic sea level oscillations driven by wave and tide. The oscillating sea levels determined the seaward boundary condition of the coastal aquifer, where variably...

Xin, Pei; Robinson, Clare; Li, Ling; Barry, David Andrew; Bakhtyar, Roham

2010-01-01

226

Status of the belugas of the St Lawrence estuary, Canada  

OpenAIRE

A population of belugas (Delphinapterus leucas) inhabiting the estuary of the St Lawrence river in Quebec, Canada, was depleted by unregulated hunting, not closed until 1979. Surveys in 1977 showed only a few hundred in the population. Surveys since then have produced increasing estimates of population indices. An estimate of the population, fully corrected for diving animals, was 1,238 (SE 119) in September 1997. The population was estimated to have increased from 1988 through 1997 by 3...

Cs, Michael Kingsley

2014-01-01

227

5.04 - Carbon Dioxide and Methane Dynamics in Estuaries  

OpenAIRE

Estuaries profoundly transform the large amounts of carbon delivered from rivers before their transfer to the adjacent coastal zone. As a consequence of the complex biogeochemical reworking of allochthonous carbon in the sediments and the water column, CO2 and CH4 are emitted into the atmosphere. We attempt to synthesize available knowledge on biogeochemical cycling of CO2 and CH4 in estuarine environments, with a particular emphasis on the exchange with the atmosphere. Unlike CH4, the global...

Borges, Alberto; Abril, Gwenae?l

2011-01-01

228

Suspended matter and heavy metal content of the Elbe Estuary  

International Nuclear Information System (INIS)

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

229

Subtidal variability in water levels inside a subtropical estuary  

Science.gov (United States)

Year-long time series of water level are analyzed at five locations along the St. Johns River Estuary, Florida, to investigate propagation of subtidal pulses. Hilbert-transformed Empirical Orthogonal Functions (HEOFs) are obtained after a dominant seasonal signal is extracted from the data. These functions provide information on spatial structure and propagation phase of subtidal water level pulses. The first HEOF mode explains 96% of the subtidal variability and features an unusual spatial structure: amplitude attenuation (averaging 1 mm/km) to 55 km upstream, slight amplification (0.16 mm/km) over the middle 70 km, and attenuation (2.3 mm/km) over the final 18 km of the estuary. The phase suggests a shift from progressive to quasi-standing wave behavior at 55 km from the estuary mouth. Additionally, local minima in the phase suggest two sources of subtidal forcing: the coastal ocean and the upstream end. An analytical model describing the evolution of long waves through a channel with frictional damping is fit to the amplitude of HEOF mode 1. Solutions are obtained as a function of two parameters: the nondimensional length of the basin, ?, and the nondimensional frictional depth, ?. Values of ? between 0.55 and 0.67 and ? between 1.45 and 1.7 provide the best fit with the HEOF results (1% error or less). These values indicate a highly frictional environment in which the average subtidal wavelength is 10 times the basin length. Subtidal pulses in this estuary, therefore, behave as damped waves that can be represented with idealized models.

Henrie, Krista; Valle-Levinson, Arnoldo

2014-11-01

230

Distribution of endocrine disruptors in the Mondego River estuary, Portugal  

OpenAIRE

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

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

2008-01-01

231

Nuclear free security in the South-West Pacific  

International Nuclear Information System (INIS)

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

232

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

233

LAGS and the "Southwest" Dialect of Texas English.  

Science.gov (United States)

The "Southwest" dialect, previously isolated in San Antonio, Texas, has been isolated south of that area. Data were drawn from the Linguistic Atlas of the Gulf States (LAGS) and interviews with ten lower-middle/upper-lower class informants. Seven communities were represented by seven female and three male English speakers (four monolingual Blacks,…

Baird, Scott

234

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

235

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

236

Intertidal macrofaunal communities in an intensely polluted estuary.  

Science.gov (United States)

The Bilbao estuary (northern Spain) has suffered a serious environmental deterioration due to industrial and domestic discharges during decades. A total of 21 sampling stations were selected in order to: (1) study the intertidal fauna distribution on both hard and soft bottoms; (2) link this information with the prevalence of certain environmental variables at the sampling sites; and (3) define distinct biological zones with all the information gathered. Up to 50 taxa were identified mainly in the outer estuary with an abrupt decrease upstream. In general, fauna on hard substrates was more diverse, while soft bottom communities exhibited a more consistent structure. Sporadic hypoxic events were recorded in the water column of all the sites studied, which affects the distribution of species. Three major biotic zones are proposed in the estuary. This provides a reliable biomonitoring tool for assessing the effectiveness of a sewerage and remediation scheme ongoing on the river and evaluating the future use of each area in the urban development of the city of Bilbao and conurbation. PMID:17370137

Bustamante, M; Tajadura-Martín, F J; Saiz-Salinas, J I

2007-11-01

237

Local flows in the Quequen Grande River Estuary, Argentina  

Energy Technology Data Exchange (ETDEWEB)

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.

Pereyra, M G; Marino, B M [Instituto de Fisica Arroyo Seco, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Thomas, L P, E-mail: mpereyra@exa.unicen.edu.a, E-mail: lthomas@exa.unicen.edu.a, E-mail: bmarino@exa.unicen.edu.a

2009-05-01

238

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

239

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.

240

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

Science.gov (United States)

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

241

Spatial and temporal variations in trace metal concentrations in surface sediments of the Marennes Oleron Bay. Relation to hydrodynamic forcing  

OpenAIRE

Sediments quality assessment is of priority concern to provide a comprehensible overview of ecological and chemical state of an ecosystem. The Marennes-Oleron Bay, hosting the largest oyster production in France, is influenced by the historic polymetallic pollution of the Gironde Estuary. Despite, management efforts and decreasing emissions in the Gironde watershed, Cd levels in oysters from the bay are close to consumption limit (5 pig g(-1) dw. EC no. 466/2001). In this context, the aim of ...

Strady, Emilie; Kervella, Stephane; Blanc, Gerard; Robert, Serge; Stanisiere, Jean-yves; Coynel, Alexandra; Schaefer, Joerg

2011-01-01

242

[Estuary health assessment using a benthic-index of biotic integrity in Yangtze Estuary and its adjacent waters].  

Science.gov (United States)

A benthic index of biotic integrity (B-IBI) was developed for application in estuaries health assessment of the Yangtze Estuary and its adjacent waters. Benthic macro-invertebrate samples were collected from 41 stream sites (13 non-degraded stations and 28 degraded stations) in the Yangtze Estuary and its adjacent waters in July, 2005. The analyses of the range of index value distribution, Pearson correlation and judgment ability were performed on fourteen candidate metrics. Six biological metrics were selected for the establishment of B-IBI, which were Shannon-Wiener index, the species number, total density, total biomass, Carapace Animals density percentage and Echinoderms density percentage. B-IBI was obtained by sum up all these indices after which were transformed into a uniform score by using the ratio scoring method. Base on 50 percentile of B-IBI value in reference sites, the criteria of health ranking was determined. The proposed criteria of benthic-index of biotic integrity were as follows: B-IBI > 2.48 was regarded as health, 1.86-2.48 sub-health, 1.24-1.86 fair, 0.62-1.24 poor, and B-IBI < 0.62 very poor. Assessing with these criteria, the results showed that among the 41 sites in Yangtze Estuary and its adjacent waters, 7 sites were health, 2 sites were sub-health, 8 sites were fair, 8 sites were poor and 16 sites were very poor. An independent data set sampled in June of 2006 was used to validate the index, the results indicated that final combined index correctly classified 89% of stations in the validation data set. PMID:19353888

Zhou, Xiao-wei; Wang, Li-ping; Zheng, Bing-hui; Liu, Lu-san; Fu, Qing

2009-01-01

243

???–??????????????????? Intertidal Heavy Metal Distribution Characteristics and Environmental Effects from the Luanhe Estuary to Douhe Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????13???????????????31????X??????(XRF??????(AAS???????????(ICP-MS?????????????????????????????????????Pb?????????????Zn????????Ni??????????As?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????Accompanied by urbanization and industrialization process in Tangshancoastal zone, the heavy metal pollution increased. The representative parts, such as Jianhe Estuary, the Luannan Zuidong Industrial Zone, Caofeidian Industrial Zone, the Qinglonghe Estuary, Caofeidian Wetlands, the Laoting Qianshui Bay, and Jingtang Port in Bohai West Bank, were chosen, selecting the 13 sampling sites, 31 surface sediment samples.

???

2012-09-01

244

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

Science.gov (United States)

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

245

E-Estuary: Developing a Decision-support System for Coastal Management in the Counterminous Untied States (Coastal Geotools 09)  

Science.gov (United States)

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

246

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

Science.gov (United States)

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

247

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

248

Suspended Sediment Exchange through the Sub-tropical Richmond River Estuary, Australia: a Balance Approach  

Science.gov (United States)

Major sources of suspended sediments and their exchanges with the continental shelf for the Richmond River estuary were investigated during two hydrological years. Of the major sources of suspended sediment inputs into the Richmond River estuary, fluvial input from the upper catchment area was about 92-99% of the total yearly balance, and more than 90% of this fluvial sediment was transported into the estuary during less than 5% time of the year. The Richmond River estuary received net sediment input of about 1-2% of the total yearly balance from the continental shelf during dry seasons when upper catchment freshwater input was less than 45×10 6 m 3. Bank erosion in the Richmond River estuary was least (mangrove coverage along the banks. Percentage of sediment export from the Richmond River estuary depends on the magnitude of floods, which was evident from 47% export during dry year when the estuary experienced a minor flood compared to 88% export during the wet year when the estuary experienced one minor and one moderate flood.

Hossain, S.; Eyre, B.

2002-10-01

249

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

OpenAIRE

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

Freeborough, K.; Wagner, D.

2005-01-01

250

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

251

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

Scientific Electronic Library Online (English)

Full Text Available The objective of this study was to determine the liver oxidative stress status of grey mullets living in heavy-metal-rich polluted Ennore estuary compared with unpolluted Kovalam estuary. Fish were collected from both estuaries during the monsoon and summer seasons from October 2004 to September 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

252

Urogenital papilla feminization in male Pomatoschistus minutus from two estuaries in northwestern Iberian Peninsula.  

Science.gov (United States)

Recently, male urogenital papilla feminization (UGPF) in the sand goby Pomatoschistus minutus was reported in several UK estuaries with high levels of estrogenic compounds. The fact that this species is also common in southern European estuaries, together with its life-cycle characteristics, prompted us to investigate P. minutus UGPF in the northwestern of Iberian Peninsula. Specimens of P. minutus were periodically sampled during 2004 at several locations in two estuaries (Minho and Lima). Evidence for UGPF was recorded in both estuaries, the highest incidence being observed in the Lima estuary (50%). Estrogen levels (17beta-estradiol and estrone) above 100 pg/l were observed in both estuaries, the higher concentrations being found in the Lima estuary. Overall, the results suggest a relationship between the feminization of male P. minutus urogenital papilla and the presence of estrogenic compounds. In the future, more in-depth studies are required in order to use P. minutus as a sentinel species for estrogenic compound monitoring in estuaries. PMID:16709430

Rodrigues, P; Reis-Henriques, M A; Campos, J; Santos, M M

2006-07-01

253

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

Science.gov (United States)

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

254

A CLASSIFICATION OF U.S. ESTUARIES BASED ON PHYSICAL, HYDROLOGIC ATTRIBUTES  

Science.gov (United States)

A classification of U.S. estuaries is presented based on estuarine characteristics that have been identified as important for quantifying stressor-response relationships in coastal systems. Estuaries within a class have similar physical/hydrologic and land use characteris...

255

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

256

Potential Climate-Induced Runoff Changes and Associated Uncertainty in Four Pacific Northwest Estuaries  

Science.gov (United States)

As part of a larger investigation into potential impacts of climate change on estuarine habitats in the Pacific Northwest (PNW), we estimated changes in freshwater inputs into four estuaries. These were the Coquille River estuary, the South Slough of Coos Bay, and the Yaquina Bay...

257

Report on benthic survey/sampling at Coquille Estuary, OR: June 30-July 3, 2008  

Science.gov (United States)

Zostera japonica is a non-native seagrass first reported in the PNW in Willapa Bay in 1957 (Harrison and Bigley 1982). Since the, Z. japonica has been reported from 16 estuaries in the PNW (Lee and Reusser 2007), including the Yaquina Estuary in 1974-1975 (Bayer 1996). Besides ...

258

Total mercury in sediments and in Brazilian Ariidae catfish from two estuaries under different anthropogenic influence.  

Science.gov (United States)

Santos-São Vicente estuary, located in São Paulo State, Brazil, has a history of contamination by inorganic chemicals such as mercury (Hg). In the 1980s the Cubatão was considered one of the most polluted sites in the world as a consequence of the intense industrial activities located in the city close to the estuary. To provide data and evaluate the local biota, total mercury (THg) contents were determined in sediments and in fish, Cathorops spixii, from different areas of the Santos-São Vicente estuary. For comparison, samples were also collected in a non-polluted system with similar hydrochemistry characteristics, the Cananeia estuary. The water characteristics and THg levels in sediment and fish samples confirmed a high human influence in the Santos-São Vicente estuary. The lowest THg values, observed in Cananeia, were evidence of low anthropogenic influence. High values observed in Santos-São Vicente show the necessity for a monitoring program. PMID:22030105

Azevedo, Juliana S; Braga, Elisabete S; Favaro, Deborah T; Perretti, Adriana R; Rezende, Carlos Eduardo; Souza, Cristina Maria M

2011-12-01

259

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

Science.gov (United States)

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

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

260

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

Science.gov (United States)

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

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

2015-01-01

261

Detecting benthic community responses to pollution in estuaries: a field mesocosm approach.  

Science.gov (United States)

Biological stress responses in individuals are used as indicators of pollution in aquatic ecosystems, but detecting ecologically relevant responses in whole communities remains a challenge. We developed an experimental approach to detect the effects of pollution on estuarine communities using field-based mesocosms. Mesocosms containing defaunated sediments from four estuaries in southeastern Australia that varied in sediment contamination were transplanted and buried in sediments of the same four estuaries for six weeks. Mesocosm sediment properties and metal concentrations remained representative of their source locations. In each estuary, fauna communities associated with sediments derived from the site with the highest metal concentrations were significantly different from other communities. This pattern was evident for some of the individual taxa, in particular the polychaete Capitella sp. Consistent responses across estuaries suggest numbers of individuals, and especially Capitella sp., could be used to identify contaminated sediments in estuaries with similar fauna and site characteristics. PMID:23333486

O'Brien, Allyson L; Keough, Michael J

2013-04-01

262

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

Science.gov (United States)

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

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

2007-01-01

263

An examination of Southwest Pacific explosive cyclones, 1989 to 2009  

International Nuclear Information System (INIS)

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

264

An examination of Southwest Pacific explosive cyclones, 1989 to 2009  

Energy Technology Data Exchange (ETDEWEB)

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

Black, M T; Pezza, A B [Department of Earth Sciences, University of Melbourne, Victoria 3010 (Australia); Kreft, P, E-mail: m.black4@pgrad.unimelb.edu.a [Meteorological Service of New Zealand Limited, Kelburn, Wellington 6012 (New Zealand)

2010-08-15

265

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

266

Coastal upwelling along the southwest coast of India – ENSO modulation  

Directory of Open Access Journals (Sweden)

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

K. Muni Krishna

2008-04-01

267

A Suspended Sediment Budget for the Modified Subtropical Brisbane River Estuary, Australia  

Science.gov (United States)

Annual suspended sediment budgets, for an average flow year and a wet year, were constructed for the sub-tropical Brisbane River estuary. The input of marine sediment from Moreton Bay is the dominant source of suspended sediment (about 456 000 t) to the Brisbane River estuary during an average flow year, contributing more than 1·5 times the sediment delivered from the catchment (about 178 000 t) and urban areas (about 112 000 t) combined. As the volume of water discharged during floods increases, the sediment retention efficiency of the Brisbane River estuary decreases rapidly due to the flushing of sediment through its mouth. As such, although the input of sediment from the catchment increased three-fold (600 000 t) during 1996 associated with a 20 year return period flood, marine sediment was still the dominant source of sediment deposited in the estuary because 77% of the fluvial sediment was exported to Moreton Bay. Dredging has increased the sediment trapping capacity of the estuary with more than a two-fold increase in the flood water volume needed (about 2000×10 6 m 3) to flush the estuary fresh at the mouth compared to pre-1962. An upstream dam traps a large proportion of the catchment sediment load, but the upstream retention of flood water has also increased the trapping capacity of the estuary by reducing the freshwater flow. As such, about 22% (33 000 t) more sediment was deposited in the estuary during a 20 year return period flood in May 1996 than would have been deposited prior to dam construction. The sub-tropical Brisbane River estuary has a lower and more variable sediment trapping efficiency than typical temperate northern hemisphere estuaries.

Eyre, B.; Hossain, S.; McKee, L.

1998-10-01

268

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

269

Epidemiological evaluation of onchocerciasis along Ogun River System, southwest Nigeria  

OpenAIRE

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

S O Sam-wobo, M. A. Adeleke

2012-01-01

270

Iron-deficiency anemia among children in southwest Iran  

OpenAIRE

Background. Iron deficiency is a major health problem worldwide and especially in developing countries. Irondeficiency anemia has adverse effects on the development of children. Objective. The purpose of this study was to determine the prevalence of iron-deficiency anemia in children under 5 years of age in southwest Iran. The study also sought to investigate the association between socioeconomic,demographic, cultural, and nutritional factors and iron-deficiency anemia in the selected area...

Tabibi, Ramin

2007-01-01

271

Migmatitic rocks southwest of the Barberton greenstone belt  

International Nuclear Information System (INIS)

A geologic survey was done on the migmatitic rocks southwest of the Barberton greenstone belt. A table is given on the chemical analyses of components from migmatic outcrops in this area, as well as on the chemical analyses of some selected rock types found in greenstone xenoliths, together with leuco-biotite tomalite/tronomjemite gneisses in the area surrounding the Boesmanskop syenite pluton. Isotope dating was also used in the survey

272

Evaluation of agricultural extension and delivery services in southwest Nigeria  

OpenAIRE

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

Ogunsumi L.O.; Abegunde B.O.

2011-01-01

273

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

274

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

275

Marine mammal strandings in the New Caledonia region, Southwest Pacific  

OpenAIRE

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

Borsa, Philippe

2006-01-01

276

Factors Associated with Treatment Compliance in Hypertension in Southwest Nigeria  

OpenAIRE

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

Osamor, Pauline E.; Owumi, Bernard E.

2011-01-01

277

Ostracods from Upper Ordovician (Katian) carbonate lithofacies in southwest Scotland  

OpenAIRE

The Ordovician Craighead Limestone Formation of southwest Scotland was formed on a carbonate platform on the eastern tropical margin of the Laurentia palaeocontinent during the early Katian (c. 456 Ma). It yields the most diverse and well-preserved ostracod fauna yet recovered from the Scottish Ordovician succession, with some 25 species divisible into two distinct marine biotopes comprising shallow lagoonal and deeper platform margin settings, respectively. The ostracods show strong biogeogr...

Mohibullah, M.; Afzal, J.; Williams, M.; Meidla, T.; Siveter, Dj; Zalasiewicz, Ja

2010-01-01

278

Lattice Boltzmann Hydrodynamic and Transport Modeling of Everglades Mangrove Estuaries  

Science.gov (United States)

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

Sukop, M. C.; Engel, V.

2010-12-01

279

The importance of estuary head waters as nursery areas for young estuary- and marine-spawned fishes in temperate South Africa  

Science.gov (United States)

The restriction of freshwater flow into estuaries, the presence of in-stream barriers and the occurrence of invasive fish species in these habitats are identified as major threats to these young estuary- and marine-spawned fish species. These aspects have been investigated using the distribution and abundance of young estuary- and marine-spawned fish species in the headwater environments of four permanently open estuaries of the Eastern Cape, South Africa. Fishes were collected twice per season over the 2009 and 2010 period, using mixed method sampling with seine net hauls and overnight fyke net deployments. Of the 74,751 fishes collected, 37,444 fishes, 18 families and 34 species were taken in fyke net catches, while 34,308 fishes, 21 families and 38 species were caught in seine nets. In the Great Fish, Kowie, Kariega and Sundays River systems, juveniles of estuarine residents dominated headwater catches, followed by juveniles of estuary-dependent marine species. The prevalence of larval and small juvenile stages of estuary- and marine-spawned fish species highlights the potential importance of these transitional areas for young fish.

Wasserman, Ryan J.; Strydom, Nadine A.

2011-07-01

280

Pennsylvanian foreland deformation of Wichita uplift, southwest Oklahoma  

Energy Technology Data Exchange (ETDEWEB)

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

McConnell, D.

1986-05-01

281

Arsenic cancer risk confounder in southwest Taiwan data set.  

Science.gov (United States)

Quantitative analysis for the risk of human cancer from the ingestion of inorganic arsenic has been based on the reported cancer mortality experience in the blackfoot disease (BFD) -endemic area of southwest Taiwan. Linear regression analysis shows that arsenic as the sole etiologic factor accounts for only 21% of the variance in the village standardized mortality ratios for bladder and lung cancer. A previous study had reported the influence of confounders (township, BFD prevalence, and artesian well dependency) qualitatively, but they have not been introduced into a quantitative assessment. In this six-township study, only three townships (2, 4, and 6) showed a significant positive dose-response relationship with arsenic exposure. The other three townships (0, 3, and 5) demonstrated significant bladder and lung cancer risks that were independent of arsenic exposure. The data for bladder and lung cancer mortality for townships 2, 4, and 6 fit an inverse linear regression model (p < 0.001) with an estimated threshold at 151 microg/L (95% confidence interval, 42 to 229 microg/L) . Such a model is consistent with epidemiologic and toxicologic literature for bladder cancer. Exploration of the southwest Taiwan cancer mortality data set has clarified the dose-response relationship with arsenic exposure by separating out township as a confounding factor. Key words: arsenic, blackfoot disease, bladder cancer, cancer risk, confounder, dose-response relationship, southwest Taiwan, threshold model. PMID:16835062

Lamm, Steven H; Engel, Arnold; Penn, Cecilia A; Chen, Rusan; Feinleib, Manning

2006-07-01

282

The Southwest Pacific Ocean circulation and climate experiment (SPICE)  

Science.gov (United States)

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

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

2014-11-01

283

Characteristics of moisture flux convergence in Central Southwest Asia  

Science.gov (United States)

The National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis data have been used to compute the moisture flux convergence (MFC) over Central Southwest Asia (CSWA) between 45°-75° E and 25°-40° N. The present study focuses on the 1969-2007 period, and both horizontal distributions and vertical profiles of MFC have been calculated and compared. Moisture is transported into the region from the west throughout the year. In this region, winter is the wettest season with the most precipitation. Areas of high moisture convergence are observed in the east and southwest. Moisture convergence in the east and southwest are associated with topographic effects. Our study also examined composites of moisture flux convergence that characterized the wettest and the driest years in this area. The magnitude of the monthly MFC differs considerably between these two extremes. The spatial distribution of moisture flux convergence during the recent drought period (1999-2001) was also examined in order to understand how moisture transport affects drought. Deficiency of precipitation during drought periods appears to be due to deviation of moisture transport away from the region.

Malik, Khalid M.; Taylor, Peter A.; Szeto, Kit

2014-06-01

284

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

285

Oil spill response planning on the Columbia river estuary  

International Nuclear Information System (INIS)

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

286

The Mattole River Estuary: Restoration Efforts in a Dynamic System  

Science.gov (United States)

Despite extensive scientific advancement integrating our understanding of hydrology, geomorphology, and ecology in recent decades, the application of restoration in the field has been slow to evolve. This presentation will highlight 20 years of restoration practices in the Mattole River Estuary and how these practices have informed our understanding of this complex system. The Mattole River Watershed is a 304 square-mile basin located near the Mendocino Triple Junction in a remote region of California known as the “The Lost Coast” for its rugged mountains and undeveloped coastline. In addition to numerous species of fish, mammals, and over 250 bird species, the Mattole Watershed is home to three Federally-listed Threatened salmonids: California Coastal Chinook salmon, Southern Oregon/Northern California Coasts coho salmon, and Northern California steelhead trout. The 64 mile-long river meets the Pacific Ocean at the northern end of the 64,000 acre King Range National Conservation Area (KRNCA), managed by the Bureau of Land Management (BLM). The watershed is dynamic, with some of the nation’s highest annual rainfall (mean = 158 cm/yr), naturally occurring steep slopes, erosive sedimentary geology, and frequent earthquakes. All of these factors have amplified the negative effects of extensive logging and associated road building between 1945 and 1970, which left a legacy of increased sediment loads and high water temperatures that have yet to recover to pre-disturbance levels, severely impairing riparian and aquatic habitats. Prior to major land disturbances, the Mattole estuary/lagoon was notable for its deep, thermally-stratified pools and numerous functioning north and south bank slough channels that flushed sediments from the river and received marine water. As flows decline in late spring, a sandbar closes off surface flow from the river to the Pacific Ocean, forming a lagoon, which persists until flows increase in the fall. Today, the estuary is poor habitat for all salmon and steelhead species: the water too warm, habitat cover poor, the channel lacks riparian vegetation, and only remnant, non- functioning slough channels are present. Over the last 20 years, the Mattole Salmon group has installed and monitored 12 large wood structures that have had various effects on the instream habitat and geomorphic processes that influence river and estuary dynamics. Methods of construction and hydrologic and geomorphic effects will be discussed, as will developing designs to reconnect abandon slough tributary channels.

Barber, D.; Liquori, M.

2010-12-01

287

Lidar monitoring of organic matter in the Pearl River Estuary  

Science.gov (United States)

A dual-wavelength lidar fluorosensor system for fast diagnosis of chromophoric dissolved matter (CDOM) in water in the Pearl River estuary was discussed. The laser-induced fluorescence (LIF) system used two lasers as excitation sources with wavelength at 355nm and 532 nm, and a hyperspectral CCD spectrometer was used to record the fluorescence signal. The overlapping fluorescence spectra of water Raman scattering and CDOM were separated with fitting bi- Gaussian of the least squares method. High correlation was observed between concentration of CDOM and fluorescence normalized to water Raman scattering. The in situ results demonstrated rapid characterization of dissolved organic matter can be done by the LIF technique.

Chen, Peng; Pan, Delu; Hu, Chuanwen; Mao, Zhihua

2014-11-01

288

Infralittoral fish assemblages in the Zrmanja estuary, Adriatic Sea  

OpenAIRE

The infralittoral fish assemblage was investigated inside the temperate Zrmanja river estuary, Adriatic Sea. The specimens were caught using a beach seine at three stations and four times over the year. A total of 10 035 individuals, belonging to 47 species and to 17 families were represented in the catch, out of these Atherina boyeri (60.3%), Symphodus ocellatus (14.4%) and Pomatoschistus marmoratus (7.5%) were most abundant, comprising 82.2% of the total catch. Marine and estuarine species ...

Baz?daric?, Branimir; Cukrov, Marijana; Pallaoro, Armin; Peharda, Melita; Matic?-skoko, Sanja

2007-01-01

289

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

290

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

Science.gov (United States)

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

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

2014-09-01

291

Mercury speciation, reactivity, and bioavailability in a highly contaminated estuary, Berry's Creek, New Jersey Meadowlands.  

Science.gov (United States)

Speciation and reactivity of mercury were examined in Berry's Creek estuary downstream of a highly mercury-contaminated U.S. EPA Superfund site during the summers of 2002 and 2003. Surface water samples from Berry's Creek estuary, its confluence with the Hackensack River, and upstream of that confluence were analyzed for total (THg), particulate (PHgT), and dissolved (DHg) mercury, total and particulate monomethylmercury (MeHg), dissolved gaseous mercury (DGM), and bacterial merA gene and transcript abundances. Surface water concentrations of THg in Berry's Creek estuary (210-6800 pM) are among the highest in North America. A downstream gradient of Hg contamination is a permanent feature of Berry's Creek estuary, and the upper estuary appears to be a perennial source of Hg to the lower estuary and the Hackensack River. MeHg concentrations in Berry's Creek surface waters ranged from 2 to 14 pM, with the highest concentrations occurring at a midestuary site 2 km downstream of the tide gate. The suspended particle phase dominated Hg and MeHg speciation throughout this system, accounting for > 90% of THg in Berry's Creek estuary and 35-94% of THg in the Hackensack River. Concentrations of DGM in Berry's Creek estuary (0.1-1.0 pM) are similar to levels of DGM in other much less contaminated estuaries (0.04-0.75 pM). In addition, expression levels of the bacterial mercuric reductase gene, merA, a gene of the inorganic Hg(II)-regulated, mercury resistance (mer) operon, were low throughout Berry's Creek estuary. Thus, despite very high concentrations of mercury in Berry's Creek estuary, relatively low concentrations of DGM and merA gene expression levels indicate limited bioavailability of inorganic Hg in the estuary's surface waters. A system-wide limitation on the bioavailability of inorganic Hg, together with bacterial demethylation activity, may account for observed MeHg concentrations that, although elevated, are lower than expected given the concentrations of THg in this estuary. PMID:18200850

Cardona-Marek, Tamara; Schaefer, Jeffra; Ellickson, Kristie; Barkay, Tamar; Reinfelder, John R

2007-12-15

292

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

293

Transport of suspended matter in a bar-built Danish estuary  

Science.gov (United States)

The river Varde Å discharges into the bay of Ho Bugt on the western coast of Jutland forming a small, bar-built estuary. This paper deals with tidal fluxes of water and sediment in the Varde Å estuary. The inflowing water at flood tide is part of a turbidity maximum in the northern part of the bay. At high tide slack water the suspended material deposits inside the estuary. During ebb-tide it is resuspended, and the estuary bottom is washed clean coinciding with the influx of relatively pure freshwater from the drainage area. From one station in the estuary mouth, current velocities and concentrations of suspended material have been measured during 10 tidal periods covering all four seasons. It is shown how these data can be used in a quantitative calculation of the transport of water and suspended material through the cross-section of study. A model has been formulated which—based on half-tidal periods—quantifies the transport of water and suspended material through the estuary mouth. The model is calibrated on the basis of measurements made during the above-mentioned 10 tidal periods. The rather small number of measurements is to some extent compensated for by a carefully pre-arranged selection of tidal periods. The model is discussed in relation to the prediction of net suspended transport through the estuary mouth in different weather and tidal situations.

Bartholdy, Jesper

1984-05-01

294

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

295

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

Directory of Open Access Journals (Sweden)

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

Yen-Chang Chen

2014-08-01

296

Dissolved organic carbon in the freshwater tidal reaches of the Schelde estuary  

DEFF Research Database (Denmark)

To unravel the factors that regulate DOC dynamics in the freshwater tidal reaches of the Schelde estuary, DOC concentration and biodegradability were monitored in the upper Schelde estuary and its major tributaries. Although the Schelde estuary possesses a densely populated and industrialized catchment, our data suggest that the bulk of DOC in the freshwater tidal reaches is not derived from waste water. This was concluded from the low biodegradability of DOC (on average 9%), DOC concentrations that are close to the mean for European rivers (4.61 mg/l) and the absence of an inverse relationship between DOC and discharge. Most DOC originating from waste water being discharged in tributaries of the estuary appears to be remineralised before these tributaries reach the main estuary. Although dense phytoplankton blooms were observed in the upper estuary during summer (up to 700 mg chl a/l), these blooms did not appear to produce large quantities of DOC in the freshwater tidal reaches as DOC concentrations were low when phytoplankton biomass was high. The fact that DOC concentrations were high in winter and decreased in summer suggests a predominantly terrestrial source of DOC in the freshwater tidal reaches of the Schelde estuary.

Muylaert, K.; Dasseville, R.

2005-01-01

297

Estimation of total suspended matter in the Zhujiang (Pearl) River estuary from Hyperion imagery  

Science.gov (United States)

Although remote sensing data have been used to estimate total suspended matter (TSM) in coastal waters, it has limitations when applied to estuary waters in low spatial resolution situations. The spatial resolution of ocean color satellites such as SeaWiFS and MODIS is usually ˜1 km, and therefore is not adequate for small, local-scale areas such as the Zhujiang (Pearl) River estuary. In contrast, 30 m-resolution EO-1 Hyperion imagery has potential for studying TSM in localized areas. We measured the surface spectral radiance reflectance of the river estuary water in the visible and near infra-red spectral range. Sensitivity analysis indicated that the ratio of remote sensing reflectance at 813 nm ( R rs(813)) to reflectance at 559 nm ( R rs(559)) could be used to estimate TSM concentration, and a linear relationship was established between the ratio and in-situ TSM concentration. We applied the linear relationship to Hyperion imagery to map TSM concentration in the estuary. The Hyperion imagery provided sufficient spatial resolution to detect spatiotemporal changes in TSM concentrations in the estuary small estuary area. This study demonstrated the usefulness of Hyperion imagery for mapping the distribution of TSM in estuary waters.

Liu, Dazhao; Fu, Dongyang; Xu, Bing; Shen, Chunyan

2012-01-01

298

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

299

Geospatial Habitat Analysis in Pacific Northwest Coastal Estuaries  

Energy Technology Data Exchange (ETDEWEB)

We assessed historical changes in the location and amount of estuarine habitat in three of the four largest coastal estuaries in the Pacific Northwest (Grays Harbor, Willapa Bay, and Coos Bay) as part of the Pacific Northwest Coastal Ecosystem Regional Study (PNCERS). To accomplish this, navigation charts, hydrographic survey data, maps, and published descriptions were used to gain information on the location of the shoreline, bathymetry, and vegetated habitats, which was then digitized and subjected to geospatial analysis using a geographic information system. In addition, we used present-day elevational boundaries for marshes, flats, and eelgrass meadows to help define habitat areas where they were not indicated on historical maps. The analysis showed that tidal flats have decreased in all study areas; potential eelgrass habitat has increased in Grays Harbor and Willapa Bay and decreased slightly in Coos Bay; tidal wetland area has declined in all three coastal estuaries, with increases in localized areas due to filling and sedimentation; and dramatic changes have occurred at the mouths of Grays Harbor and Willapa Bay. As has been shown before, these data illustrate that direct physical alteration (filling and diking) has resulted in large changes to habitats. However, indirect impacts from forest practices in the watershed, as well as variation in climatic factors and oceanographic processes, may also have contributed to changes. The information provides more evidence for managing estuarine habitats in the region and a employing a historical template to plan habitat restoration in the future.

Borde, Amy B.(BATTELLE (PACIFIC NW LAB)); Thom, Ronald M.(BATTELLE (PACIFIC NW LAB)); Rumrill, Steven (South Slough Estuarine Research Reserve); Miller, L M.(GEORGE A GRANT INC)

2003-08-01

300

Density-driven Secondary Circulation in a Tropical Mangrove Estuary  

Science.gov (United States)

Observations of suspended sediment concentration (SSC), salinity and current were made in the Normanby River estuary, Cape York Peninsula, Northern Australia. The estuarine reaches are approximately 80 km in length, and are fringed by mangroves. A well-developed axial convergence was found to exist almost unbroken for a distance of at least 30 km on flood tides, clearly delineated by an accumulation of mangrove leaves and seed pods on the water surface. The convergence migrated to the inside of most bends. Suspended sediment concentration profiles were very well-mixed both vertically and laterally. Salinity profiles showed a cross-channel salinity gradient of 0·2/25 m, sufficient to form density-driven secondary cells. The cells produce an effective transverse mixing coefficient of 0·25 m 2 s -1, of the same order of magnitude as the conventional transverse diffusion coefficients for natural meandering channels. Mangrove seeds were present in the channel centre during flood tides, and were moved to the channel banks during ebb tides. Due to the lateral shear in longitudinal currents, mangrove seeds are predicted to move landward up the estuary at a rate of 1 km per day when density-driven circulation cells are active, influencing mangrove seed dispersal.

Ridd, P. V.; Stieglitz, T.; Larcombe, P.

1998-11-01

301

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)

302

Radium and radon in Charlotte Harbor Estuary, Florida  

International Nuclear Information System (INIS)

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

303

Major hydrogeochemical processes in an acid mine drainage affected estuary.  

Science.gov (United States)

This study provides geochemical data with the aim of identifying and quantifying the main processes occurring in an Acid Mine Drainage (AMD) affected estuary. With that purpose, water samples of the Huelva estuary were collected during a tidal half-cycle and ion-ion plots and geochemical modeling were performed to obtain a general conceptual model. Modeling results indicated that the main processes responsible for the hydrochemical evolution of the waters are: (i) the mixing of acid fluvial water with alkaline ocean water; (ii) precipitation of Fe oxyhydroxysulfates (schwertmannite) and hydroxides (ferrihydrite); (iii) precipitation of Al hydroxysulfates (jurbanite) and hydroxides (amorphous Al(OH)3); (iv) dissolution of calcite; and (v) dissolution of gypsum. All these processes, thermodynamically feasible in the light of their calculated saturation states, were quantified by mass-balance calculations and validated by reaction-path calculations. In addition, sorption processes were deduced by the non-conservative behavior of some elements (e.g., Cu and Zn). PMID:25530015

Asta, Maria P; Calleja, Maria Ll; Pérez-López, Rafael; Auqué, Luis F

2015-02-15

304

Interaction of lateral baroclinic forcing and turbulence in an estuary  

Science.gov (United States)

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

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

2003-03-01

305

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

306

Reducing Nitrogen loadings to estuaries in Denmark, 1990-2010. Results and costs of measures applied in catchments to 10 Danish estuaries  

Science.gov (United States)

The Nitrogen loading to 10 Danish estuaries has since 1990 been reduced by on average 42%. Thirty percent of this reduction is due to a reduction in Nitrogen loss from diffuse sources. Nitrogen surplus and the change in this surplus is shown to be a strong overall indicator for the trends in Nitrogen loading to most estuaries. The Nitrogen surplus has been reduced due to general national regulations and mitigation measures applied leading to an increased efficiency of Nitrogen use in cattle slurry (30%) and in pig slurry (ca. 40%). These improvements are paralleled by a reduced application of commercial N-fertilizer. Mean flow-weighted total Nitrogen concentrations in inlet fresh waters to estuaries have been reduced by 18-56% resulting in reductions of total Nitrogen concentrations (24-62%) in the inner and middle parts of the estuaries. The large variations in total Nitrogen loadings and concentrations in estuaries are due to both attenuation and time delays of Nitrogen in groundwater aquifers depending on catchment soil type and geology. This also implies varying costs of reducing the Nitrogen loadings from agricultural land (24-94 Euro/kg N reduced). Knowledge of the outcome of responses in the form of national regulations of agricultural N management for the N cycling from field to estuaries is important for decision makers and catchment managers working with the implementation of EU Directives such as the Water Framework Directive. Based on our findings we suggest that further reductions of Nitrogen loadings from agricultural land should be based on targeted and catchment specific measures leading to the most cost efficient way to achieve good ecological quality in the individual estuaries.

Windolf, J.; Blicher-Mathiesen, G.; Carstensen, N. J.; Kronvang, B.

2012-04-01

307

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

OpenAIRE

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

Pereyra Lago, R.

2012-01-01

308

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

Directory of Open Access Journals (Sweden)

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

Tatsuya Yurimoto

2014-08-01

309

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)

310

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

311

Volcanoes magnify Metro Manila's southwest monsoon rains and lethal floods  

Science.gov (United States)

Many volcanoes worldwide are located near populated cities that experience monsoon seasons, characterised by shifting winds each year. Because of the severity of flood impact to large populations, it is worthy of investigation in the Philippines and elsewhere to better understand the phenomenon for possible hazard mitigating solutions, if any. During the monsoon season, the change in flow direction of winds brings moist warm air to cross the mountains and volcanoes in western Philippines and cause lift into the atmosphere, which normally leads to heavy rains and floods. Heavy southwest monsoon rains from 18-21 August 2013 flooded Metro Manila (population of 12 million) and its suburbs paralyzing the nation’s capital for an entire week. Called the 2013 Habagat event, it was a repeat of the 2012 Habagat or extreme southwest monsoon weather from 6-9 August, which delivered record rains in the mega city. In both the 2012 and 2013 Habagat events, cyclones, the usual suspects for the delivery of heavy rains, were passing northeast of the Philippine archipelago, respectively, and enhanced the southwest monsoon. Analysis of Doppler data, rainfall measurements, and Weather Research and Forecasting (WRF) model simulations show that two large stratovolcanoes, Natib and Mariveles, across from Manila Bay and approximately 70 km west of Metro Manila, played a substantial role in delivering extreme rains and consequent floods to Metro Manila. The study highlights how volcanoes, with their shape and height create an orographic effect and dispersive tail of rain clouds which constitutes a significant flood hazard to large communities like Metro Manila.

Lagmay, Alfredo Mahar; Bagtasa, Gerry; Crisologo, Irene; Racoma, Bernard Alan; David, Carlos Primo

312

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

313

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

314

Design and fabrication of the BDM southwest photovoltaic residence prototype  

Energy Technology Data Exchange (ETDEWEB)

As part of the Department of Energy residential photovoltaic demonstration program, BDM has designed a photovoltaic, all-electric residence suitable for the southwestern United States and built a prototype structure to test the design concept. The prototype was built at the Southwest Residential Experimental Station operated by the Solar Energy Institute at New Mexico State University along with prototypes from other contractors. The use of prototypes permits testing of the PV array which produces DC power, the power conversion equipment which converts DC to AC, and the utility interface equipment which operates the power system interactively with the electric utility. The array mounting and structural aspects can also be evaluated.

Lambarski, T.J.; Forrester, D.L.; Hoover, C.G.

1982-09-01

315

A Novel Approach for Evaluation of Water Quality Trends in Gulf Coast Estuaries  

Science.gov (United States)

Water quality data form the backbone of management programs aimed at protecting environmental resources. The increasing availability of long-term monitoring data for estuaries can improve detection of temporal and spatial changes in water quality. However, the relatively simple...

316

Aerobic and anaerobic biodegradation of nonylphenol ethoxylates in estuary sediment of Yangtze River, China  

Science.gov (United States)

The biodegradation behavior of nonylphenol ethoxylates (NPEOs) in estuary sediment of Yangtze River, China, was investigated. NPEOs were readily degraded in the estuary sediment under both aerobic and anaerobic conditions. The highest biodegradation rate constants for the aerobic biodegradation and anaerobic biodegradation were 0.333 and 0.194 day-1, respectively. Anaerobic biodegradation of NPEOs in estuary sediment was enhanced under sulfate-reducing or nitrate-reducing conditions. The biodegradation constants increased by 23.4 and 56.7% in sulfate-adding treatment and nitrate-adding treatment, respectively. NPEOs were biodegraded through the terminal oxidative pathway in estuary sediment under aerobic conditions while these compounds were biodegraded through the non-oxidative pathway under anaerobic conditions. Estrogenic intermediates were formed during NPEO biodegradation under both aerobic and anaerobic conditions. Both treatments reached their highest estrogenicities on day 21. Short-chain nonylphenol ethoxycarboxylates (NPECs), which were feasibly mobile, were only formed under aerobic conditions.

Lu, Jian; He, Yiliang; Wu, Jun; Jin, Qiang

2009-03-01

317

Water policy effectiveness: 30 years of change in the hypernutrified Colne estuary, England.  

Science.gov (United States)

Wastewater discharges and agricultural run-off have caused nutrient enrichment leading to eutrophication, in receiving waters worldwide. Analysis of a 30 year data set (1981-2010) for the Colne estuary, a hypernutrified estuary in the south-east of England, revealed significant reductions in nutrient concentrations in freshwater inputs and along the estuarine gradient linked to management actions. DIN concentrations decreased, mainly as a result of reduced ammonia outputs from Colchester STW and reduced nitrate loads from the catchment. Declines in phosphate concentrations occurred due to improved STW processes. There were significant declines in phytoplankton chlorophyll a over the period. Long-term trajectories of nutrient decreases were also strongly influenced by interannual patterns of rainfall and climatic signals (winter NAO). Standardised winter DIN concentrations in the Colne estuary significantly exceed the Water Framework Directive good status target, but the estuary shows no symptoms of eutrophication. PMID:24556358

McMellor, S; Underwood, G J C

2014-04-15

318

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

Science.gov (United States)

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

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

2005-01-01

319

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

320

DISTINGUISHING AND QUANTIFYING NATURAL AND ANTHROPOGENIC NUTRIENT LOADING TO PACIFIC NORTHWEST ESTUARIES  

Science.gov (United States)

Many coastal ecosystems are experiencing environmental problems due to excess nutrients, particularly nitrogen. Identifying the sources of dissolved inorganic nitrogen (DIN) in estuaries is complicated by the multiple sources and pathways, temporal variability in inputs, and var...

321

PARASITIC AND SYMBIONIC FAUNA IN OYSTERS (CRASSOSTREA VIRGINICA) COLLECTED FROM THE CALOOSAHATCHEE RIVER AND ESTUARY, FLORIDA  

Science.gov (United States)

Studies of oysters, Crassostrea virginica, collected from ten sites in the Caloosahatchee River and Estuary, Florida, revealed a varied parasite and symbiotic fauna that have never been reported from this area. Organisms observed included ovacystis virus infecting gametes...

322

EFFECTS OF FRESHWATER RELEASES AND SEASON ON OYSTERS (CRASSOSTREA VIRGINICA) IN CALOOSAHATCHEE ESTUARY, FLORIDA  

Science.gov (United States)

The influence of freshwater releases and season on disease prevalence and intensity of Perkinsus marinus, condition index, gonadal condition, recruitment potential, and growth of oysters was examined monthly at five locations along the Caloosahatchee estuary, Florida. Temperature...

323

A GUIDE TO MAPPING INTERTIDAL EELGRASS AND NONVEGETATED HABITATS IN ESTUARIES OF THE PACIFIC NORTHWEST USA  

Science.gov (United States)

This document provides technical guidance for planning and implementing the production of aerial photomaps of intertidal vegetative habitats in coastal estuaries of the Pacific Northwest USA (PNW). The focus is on methods of documenting the intertidal distribution of the seagras...

324

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. ...

325

Modeling transportation of suspended solids in Zhujiang River estuary, South China  

Science.gov (United States)

A three-dimensional transportation model for suspended solids (SS) in Zhujiang (Pearl) River estuary, South China, was developed by coupling with a three-dimensional hydrodynamic model. The model was validated using hourly measured data of sediment contents during 25 26, July 1999. The results showed that modeled contents matched well with measured ones and that the modeled top layer distribution agreed with the remotely sensed image of suspended solids in summer. The modeled results showed clearly the layers of suspended solids in depth, with larger sediment contents in lower layers though in the interface between salt water and freshwater the lowest contents appeared in middle layer. In overall, the suspended solids inflow from 8 rivers, transport southwestward, and carried by strong coastal flow in Zhujiang River estuary. Contours of sediment contents in the estuary spread further to the open sea during ebb tide rather than flood tide which reflects that the suspended solids in the estuary are land sourced.

Chen, Xiaohong; Chen, Yongqin; Lai, Guoyou

2005-03-01

326

Diel-Cycling Hypoxia in Northern Gulf of Mexico Estuaries: Impacts and Protection of Aquatic Life  

Science.gov (United States)

Eutrophication of coastal ecosystems is a longstanding environmental concern, exacerbated by population growth and associated nutrient pollution, and ultimately resulting in increased incidence of hypoxia. Shallow and highly productive estuaries and embayments are particularly su...

327

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

328

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

Directory of Open Access Journals (Sweden)

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

Nandadeep U. Fal Dessai

2013-09-01

329

The mid-Pleistocene transition in the subtropical southwest Pacific  

Science.gov (United States)

Reconstructions of subtropical southwest Pacific climate variability over the Pleistocene were derived from coupled planktic foraminiferal ?18O-Mg/Ca measurements taken from a southern Coral Sea sediment core. A clear shift from ˜40 kyr to ˜100 kyr modes of reconstructed glacial-interglacial sea surface temperature (SST) variability is seen over the mid-Pleistocene transition, and these fluctuations are shown to have remained coherent with the orbital obliquity cycle across the transition. The likely origin of this strong obliquity signal in subtropical southwest Pacific SST is shown to be the southern high latitudes, and comparison with existing SST reconstructions from the equatorial Pacific is consistent with the communication of the signal occurring principally by greenhouse gas forcing. In contrast to the SST reconstruction, regional hydrological cycle variability (based on the calculated local component of ?18Osw change) does not show significant coherence with obliquity after ˜1000 ka. The decoupling of the SST and hydrological cycle responses over the mid-Pleistocene transition allows constraints to be placed on the evolution and extent of orbitally paced fluctuations within the coupled low-latitude ocean-atmosphere system.

Russon, T.; Elliot, M.; Sadekov, A.; Cabioch, G.; Corrège, T.; De Deckker, P.

2011-03-01

330

Evolution of an anticyclonic eddy southwest of Taiwan  

Science.gov (United States)

Satellite images of sea-surface temperature, surface chlorophyll a concentration, and sea-level anomaly, together with ocean reanalysis data of Asia and Indian-Pacific Ocean (AIPOcean1.0), are utilized to study the three-dimensional characteristics and evolution of an anticyclonic warm eddy adjacent to the southwest coast of Taiwan during October and November 2006. Originated from the Kuroshio intrusion in the Luzon Strait, but unlike previously found westward moving anticyclonic eddies (AE) in the northeastern South China Sea, this AE was so close to the Taiwan coast and stayed where it was formed for over 1 month until it dissipated. Energy analysis is utilized to study the evolution process of the AE, and it shows that the barotropic instability (BTI) and baroclinic instability introduced by the Kuroshio intrusion flow appear to be the main energy sources for the AE. Periodical enhancement/relaxation of local northeasterly monsoon and its associated negative wind stress curl modify the current patterns in this region, reinforce the intraseasonal variability of the Kuroshio intrusion flow, and act together with Kuroshio to form the AE. Eddies detected from AIPOcean1.0 data also show that AEs are most likely to be generated southwest of Taiwan during the transition period of summer monsoon to winter monsoon, and generally, the BTI of Kuroshio intrusion contributes more than the direct wind stress work to the increase of the eddy kinetic energy for the generation and growth of the AEs.

Zu, Tingting; Wang, Dongxiao; Yan, Changxiang; Belkin, Igor; Zhuang, Wei; Chen, Ju

2013-05-01

331

Genetic diversity of Broussonetia papyrifera populations in southwest China.  

Science.gov (United States)

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

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

2014-01-01

332

Reproductive biology of Sciades herzbergii (Siluriformes: Ariidae) in a tropical estuary in Brazil  

OpenAIRE

The present study investigated the reproductive biology of Sciades herzbergii in the Paraíba do Norte River Estuary, Brazil. We aimed to characterize the reproduction of the species with respect to sex ratio, spawning season, condition factor and length at first maturity. Specimens were captured between August 2009 and July 2010 in a stretch of the main channel of the estuary. In the laboratory, they were measured, weighed and macroscopically classified with regard to sex and gonad developme...

Queiroga, Fernando R.; Golzio, Je?ssica E.; Dos Santos, Raphaela B.; Martins, Tayna? O.; Ana Lúcia Vendel

2012-01-01

333

Distribution of carbon in a tropical hypersaline estuary, the Casamance (Senegal, West Africa)  

OpenAIRE

The Casamance estuary, on the coast of Senegal, is an inverse hypersaline estuary : salinity increases landward, and dry season salinity values are up to 172 psu due to the evaporation of seawater. Dissolved inorganic carbon (DIC) concentrations decreased landward as a negative linear function of salinity. Thermodynamic modelling and the absence of CaCO3 in the sediments indicate that this loss of DIC was not due to calcite precipitation in the main water body. The intermost, almost landlocke...

Page?s, Jean; Lemoalle, Jacques

1995-01-01

334

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

Science.gov (United States)

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

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

2014-10-01

335

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

OpenAIRE

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

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

2007-01-01

336

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

337

The Filling Dynamics of an Estuary: From the Process to the Modelling  

OpenAIRE

The aim of this chapter is to summarise the main hydrosedimentary processes that take place in estuaries and to present different approaches for their modelling. Section 2 is dedicated to the description of the physical processes involved in estuaries. Section 3 presents the classical (single phase) approach focussing on different ways to model the bed evolutions; the rheological and erosion properties of mud are discussed. Section 4 deals with the two-phase model for sediment transport. Seve...

Guillou, Sylvain; Thiebot, Je?ro?me; Chauchat, Julien; Verjus, Romuald; Besq, Anthony; Nguyen, Duc Hau; Keang, Se? Pouv

2011-01-01

338

Phosphorus sorption and buffering mechanisms in suspended sediments from the Yangtze Estuary and Hangzhou Bay, China  

OpenAIRE

The adsorption isotherm and the mechanism of the buffering effect are important controls on phosphorus behaviors in estuaries and are important for estimating phosphate concentrations in aquatic environments. In this paper, we derive phosphate adsorption isotherms in order to investigate sediment adsorption and buffering capacity for phosphorus discharged from sewage outfalls in the Yangtze Estuary and Hangzhou Bay near Shanghai, China. Experiments were also carried out at different temperatu...

Li, M.; Whelan, M. J.; Wang, G.; White, S. M.

2012-01-01

339

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

OpenAIRE

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

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

2010-01-01

340

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

Directory of Open Access Journals (Sweden)

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

Kolobov Vladimir Yurievich

2013-09-01

341

Cadmium and mercury in Seine Estuary flounders and mussels: the results of two decades of monitoring  

OpenAIRE

The flounder (Platichthys flesus) is a flatfish that inhabits marine coastal environments, especially estuaries. It is an alternative quantitative biological indicator to the common marine mussel (Mytilus spp.), which is currently used as a sentinel species to monitor chemical contamination in numerous monitoring programmes. Findings from two decades of monitoring cadmium (Cd) and mercury (Hg) using both sentinel species in the Seine Estuary (France) are reported. For comparison, time-series ...

Nakhle, K.; Cossa, Daniel; Claisse, Didier; Beliaeff, Benoit; Simon, S.

2007-01-01

342

Geochemical characteristics and sources of some chemical components in sediments of Zhujiang (Pearl) River Estuary  

Science.gov (United States)

Sediment cores with length of 25 45cm at 12 stations in Zhujiang (Pearl) River Estuary were sampled in summer of 1999. Chemical components (Al2O3, Fe2O3, CaO, TiO2, Cu, Pb, Cr, Zn, Co, Ni, V, Ba, Sr and Y) and grain sizes were analyzed. Sediments in Zhujiang River Estuary are characterized by relatively coarse grain size. The grain sizes of the sediments in the area outside the estuary are relatively finer than those in the north part of the estuary but coarser than those in the middle of Lingdingyang and have a trend similar to the spatial distribution trend of some chemical components such as Fe2O3, Al2O3, TiO2, V, Cu, Ni, Zn and Y. This showed that grain size is an important factor that controls the spatial distribution and depth profile of chemical elements in the Zhujiang River Estuary. Frequent re-suspension, re-transportation and redistribution of settled sediment on estuary floor could be deduced from the spatial distributions and depth profiles of chemical components. Except for CaO and Sr, the chemical components always enrich at the west side of, in the middle of, and at the north side of, the estuary. Fe2O3, Al2O3, Ti, V, Cr, Ni, Zn, Cu and Y in Zhujiang River Estuary sediments mainly result from rock and soil weathering except that parts of Cr, Ni, Zn Cu and Y are anthropogenic. CaO and Sr in sediments originate from marine source. Although Co as well as Pb derives from anthropogenic sources, human activities related to Co might differ from the activities related to Pb.

Zhou, Huaiyang; Peng, Xiaotong; Pan, Jianming

2004-03-01

343

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 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

344

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

OpenAIRE

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

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

2006-01-01

345

Space-time distribution of the ichthyofauna from Saco da Fazenda estuary, Itajaí, Santa Catarina, Brazil  

OpenAIRE

ABSTRACT: From July 2003 to June 2004, the physiographic characteristics of the ichthyofauna of the estuary of Saco da Fazenda were studied in four defined areas representative of the estuary. A total of 4502 individuals were captured, with 42 species, 35 genera, and 21 families. Engraulidae were the most abundant fish, and Cetengraulis edentulus dominated the captures. The species of occasional occurrence prevailed in the samplings and were represented mainly by juvenile individuals. The hig...

Barreiros, Joa?o P.; Branco, Joaquim O.; Freitas Jr, Felipe; Machado, Leonardo F.; Hostim-silva, Mauri?cio; Verani, Jose? R.

2009-01-01

346

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

OpenAIRE

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

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

2003-01-01

347

An introduction to the San Francisco Estuary tidal wetlands restoration series  

OpenAIRE

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

Brown, Larry R.

2003-01-01

348

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

OpenAIRE

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

Balls, Pw

1992-01-01

349

Contemporary hydrodynamics and morphological change of a microtidal estuary: a numerical modelling study  

Science.gov (United States)

Contemporary hydrodynamics and morphological change are examined in a shallow microtidal estuary, located on a wave-dominated coast (Port Stephens, NSW, Australia). Process-based numerical modelling is undertaken by combining modules for hydrodynamics, waves, sediment transport and bathymetry updates. Model results suggest that the complex estuarine bathymetry and geometry give rise to spatial variations in the tidal currents and a marked asymmetry between ebb and flood flows. Sediment transport paths correspond with tidal asymmetry patterns. The SE storms significantly enhance the quantities of sediment transport, while locally generated waves by the westerly strong winds also are capable of causing sediment entrainment and contribute to the delta morphological change. The wave/wind-induced currents are not uniform with flow over shoals driven in the same direction as waves/winds while a reverse flow occurring in the adjacent channel. The conceptual sediment transport model developed in this study shows flood-directed transport occurs on the flood ramp while ebb-directed net transport occurs in the tidal channels and at the estuary entrance. Accretion of the intertidal sand shoals and deepening of tidal channels, as revealed by the model, suggest that sediment-infilling becomes advanced, which may lead to an ebb-dominated estuary. It is likely that a switch from flood- to ebb-dominance occurs during the estuary evolution, and the present-day estuary acts as a sediment source rather than sediment sink to the coastal system. This is conflictive to the expectation drawn from the estuarine morphology; however, it is consistent with previous research suggesting that, in an infilling estuary, an increase in build-up of intertidal flats/shoals can eventually shift an estuary towards ebb dominance. Thus, field data are needed to validate the result presented here, and further study is required to investigate a variety of estuaries in the Australian area.

Jiang, Angela Wenping; Ranasinghe, Roshanka; Cowell, Peter

2013-01-01

350

Physical and biogeochemical controls on light attenuation in a eutrophic, back-barrier estuary  

OpenAIRE

Light attenuation is a critical parameter governing the ecological function of shallow estuaries. In these systems primary production is often dominated by benthic macroalgae and seagrass; thus light penetration to the bed is of primary importance. We quantified light attenuation in three seagrass meadows in Barnegat Bay, New Jersey, a shallow eutrophic back-barrier estuary; two of the sites were located within designated Ecologically Sensitive Areas (ESAs). We sequentially ...

Ganju, N. K.; Miselis, J. L.; Aretxabaleta, A. L.

2014-01-01

351

Nitrification in the Schelde estuary: methodological aspects and factors influencing its activity  

OpenAIRE

We present a 15-month dataset on nitrification measurements in the Schelde estuary (Belgium and The Netherlands). Nitrification was estimated using the N-serve sensitive dark 14C-bicarbonate incorporation technique. A peak of nitrification activity was observed in the freshwater part of the estuary. Downstream from this peak, nitrification declined, probably because of ammonium limitation. A range of nitrification inhibitors was tested on both a Nitrosomonas europaea culture and estu...

Bie, M. J. M.; Starink, M.; Boschker, H. T. S.; Peene, J. J.; Laanbroek, H. J.

2002-01-01

352

Composition and Diversity of Phytoplankton from Mangrove Estuaries in Sarawak, Malaysia  

OpenAIRE

The composition and diversity of phytoplankton were studied along with physico-chemical parameters of water of two mangrove-dominated estuaries i.e., Kuala Sibuti (KS) and Kuala Nyalau (KN), Sarawak, Malaysia. A total of 46 species of phytoplankton with the mean density of 147000 cells L-1 were recorded from KS estuary i.e., 3 species of Cyanophyceae; 22 species of Bacillariophyceae; 20 species of Dinophyceae and 1 species of Chlorophyceae. The recorded mean ...

Saifullah, A. S. M.; Abu Hena, M. K.; Idris, M. H.; Halimah, A. R.; Johan, I.

2014-01-01

353

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

354

A Lagrangian-trajectory study of a gradually mixed estuary  

Science.gov (United States)

When modelling is used for investigating estuarine systems, a choice generally has to be made between applying simple mass-balance considerations or using a process-resolving three-dimensional (3-D) numerical circulation model. In the present investigation of the Gulf of Finland, a gradually mixed estuary in the Baltic Sea, it is demonstrated how Lagrangian-trajectory analysis applied to the output from a 3-D model minimizes the disadvantages associated with both of the modelling techniques referred to above. This formalism made it possible to demonstrate that the main part of the Gulf is dominated by water originating from the Baltic proper, and that the most pronounced mixing with fresh water from the river Neva takes place over a limited zone in the inner part of the Gulf. Dynamical insights were furthermore obtained by using the Lagrangian formalism to construct overturning stream-functions for the two source waters.

Jönsson, Bror F.; Döös, Kristofer; Myrberg, Kai; Lundberg, Peter A.

2011-11-01

355

UC-Berkeley Department of Geography's San Francisco Bay Estuary  

Science.gov (United States)

Created by researchers from the Geography Department at UC-Berkeley, this cool website was created as an image resource for researchers working to identify seeds collected in sediment cores -- thereby allowing them to date a species occurrence in a given area. The seeds available for viewing represent both saltwater and freshwater plants and "were selected from a list of common vascular plants in tidal marshes of the San Francisco Bay Estuary included in Atwater et al, 1979." Common and scientific names are provided for each plant, and the species are organized alphabetically by family. Species are included from over twenty different families including Alismataceae, Caryophyllaceae, Cyperaceae, Juncaceae, and more. Most seed image profiles contain two photographs taken at both lower and higher levels of magnification.

356

Agrochemical and nutrient impacts on estuaries and other aquatic systems.  

Science.gov (United States)

This paper summarizes the "Agrochemical and Nutrient Impacts on Estuaries" symposium held at the 220th National Meeting of the American Chemical Society. The focus of the symposium was to highlight ongoing research efforts to understand estuarine function and pollutant fate in these important ecosystems. Expanding urbanization and agricultural activity can result in increased particulate and chemical loads, resulting in decreased light penetration and degraded aquatic habitats. Legislative and regulatory protections, such as the Clean Water Act and Total Maximum Daily Loads (TMDLs), are considered here. Measurement of nutrient and pesticide loads and their ecotoxicological impacts are explored, as well as potential mitigation practices. The complexity and high visibility of estuarine ecosystem health will require continued examination to develop more effective agricultural and land management strategies and sound science-based regulations. PMID:12105974

Hapeman, Cathleen J; Dionigi, Christopher P; Zimba, Paul V; McConnell, Laura L

2002-07-17

357

Emissions of biogenic sulfur gases from a Danish estuary  

Energy Technology Data Exchange (ETDEWEB)

The diurnal variations in sulfur emission were studied at seven sites in a Danish estuary, Norsminde Fjord. The sites comprised grass vegetation, intertidal mud flats, accretions of green algae, an exposed shore and a river outlet. Direct measurements of emission rates from soil and water were done by a dynamic flux chamber technique in connection with gas chromatographic detection and separation of the cryogenically trapped sulfur gases. Sulfur gas concentrations in air and seawater were measured together with emission rates at 0.5-1 h intervals over 25-40 h periods. DMS was the most important sulfur gas released from grass and algae, while mostly H2S was released from intertidal mud flats. OCS, CH3SH and CS2 were released from most sites at lower rates. Emission of DMS followed the daylight variations, often with a delay towards maximum emission rates in the evening. H2S was mostly emitted at night or in short outburst during low tides. Total sulfur emission rates were 1-10 mol S m S d . Extreme rates of 335 mol DMS m S d were measured over decomposing green algae (Ulva lactuca). H2S emission fractions were < 10 W to 2 x 10 U. H2S was detected, along with DMS, CH3SH, OCS and CS2, in the oxic seawater of the estuary at diurnal mean concentrations of 0.1-6.5 nmol Sl . This may indicate a more widespread occurrence of H2S in shallow, near-shore waters at nanomolar levels.

Joergensen, B.B.; Okholm-Hansen, B.

1985-01-01

358

Emissions of biogenic sulfur gases from a danish estuary  

Science.gov (United States)

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

Barker Jørgensen, Bo; Okholm-Hansen, Bolette

359

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

360

Optical changes in a eutrophic estuary during reduced nutrient loadings  

DEFF Research Database (Denmark)

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

Pedersen, Troels MØller; Sand-Jensen, Kaj

2014-01-01

361

Numerical modeling of an estuary: A comprehensive skill assessment  

Science.gov (United States)

Numerical simulations of the Hudson River estuary using a terrain-following, three-dimensional model (Regional Ocean Modeling System (ROMS)) are compared with an extensive set of time series and spatially resolved measurements over a 43 day period with large variations in tidal forcing and river discharge. The model is particularly effective at reproducing the observed temporal variations in both the salinity and current structure, including tidal, spring neap, and river discharge-induced variability. Large observed variations in stratification between neap and spring tides are captured qualitatively and quantitatively by the model. The observed structure and variations of the longitudinal salinity gradient are also well reproduced. The most notable discrepancy between the model and the data is in the vertical salinity structure. While the surface-to-bottom salinity difference is well reproduced, the stratification in the model tends to extend all the way to the water surface, whereas the observations indicate a distinct pycnocline and a surface mixed layer. Because the southern boundary condition is located near the mouth the estuary, the salinity within the domain is particularly sensitive to the specification of salinity at the boundary. A boundary condition for the horizontal salinity gradient, based on the local value of salinity, is developed to incorporate physical processes beyond the open boundary not resolved by the model. Model results are sensitive to the specification of the bottom roughness length and vertical stability functions, insofar as they influence the intensity of vertical mixing. The results only varied slightly between different turbulence closure methods of k-?, k-?, and k-kl.

Warner, John C.; Geyer, W. Rockwell; Lerczak, James A.

2005-05-01

362

Use of glacier river-fed estuary channels by juvenile coho salmon: transitional or rearing habitats?  

Science.gov (United States)

Estuaries are among the most productive ecosystems in the world and provide important rearing environments for a variety of fish species. Though generally considered important transitional habitats for smolting salmon, little is known about the role that estuaries serve for rearing and the environmental conditions important for salmon. We illustrate how juvenile coho salmonOncorhynchus kisutch use a glacial river-fed estuary based on examination of spatial and seasonal variability in patterns of abundance, fish size, age structure, condition, and local habitat use. Fish abundance was greater in deeper channels with cooler and less variable temperatures, and these habitats were consistently occupied throughout the season. Variability in channel depth and water temperature was negatively associated with fish abundance. Fish size was negatively related to site distance from the upper extent of the tidal influence, while fish condition did not relate to channel location within the estuary ecotone. Our work demonstrates the potential this glacially-fed estuary serves as both transitional and rearing habitat for juvenile coho salmon during smolt emigration to the ocean, and patterns of fish distribution within the estuary correspond to environmental conditions.

Hoem Neher, Tammy D.; Rosenberger, Amanda E.; Zimmerman, Christian E.; Walker, Coowe M.; Baird, Steven J.

2014-01-01

363

Predicting oxygen in small estuaries of the Baltic Sea: a comparative approach  

Science.gov (United States)

Coastal eutrophication, manifested as hypoxia and anoxia, is a global problem. Only a few empirical models, however, exist to predict bottom oxygen concentration and percentage saturation from nutrient load or morphometry in coastal waters, which are successfully used to predict phytoplankton biomass both in lakes and in estuaries. Furthermore, hardly any empirical models exist to predict bottom oxygen from land-use. A data set was compiled for 19 estuaries in the northern Baltic Sea, which included oxygen concentration and percentage saturation, water chemistry, estuary morphometry, and land-use characteristics. In regression analyses, bottom oxygen was predicted both as a function of the percentage of watershed under agriculture and of mean depth. These models accounted for ca. 55% of the variation in oxygen. Additionally, oxygen was linked to fetch (diameter of the area in the direction of the prevailing wind), which accounted for 30% of the variation in oxygen. This suggests that shallow Finnish estuaries are wind-sensitive. In 'pits' (sub-thermocline waters of deep basins), near-bottom total nitrogen strongly correlated with oxygen percentage saturation ( R2=0.81). Neither chlorophyll a, total phosphorus nor nutrient loading explained oxygen variation in entire estuaries or in 'pits', probably mainly due to annual sedimentation/sediment-water flux dynamics. On the basis of the results of cross-validation, the models have general applicability among Finnish estuaries.

Kauppila, Pirkko; Meeuwig, Jessica J.; Pitkänen, Heikki

2003-08-01

364

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

Science.gov (United States)

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

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

2015-01-01

365

CO2 air-sea fluxes across the Portuguese estuaries Tagus and Sado  

Science.gov (United States)

Generally, estuaries and proximal shelves under the direct influence of river runoff and large inputs of organic matter are mostly heterotrophic and, therefore, act as a carbon source. In this context the CO2 dynamics in Tagus and Sado estuaries (SW Portugal) was studied under two different climate and hydrological situations. These moderately productive mesotidal coastal-plain lagoon-type estuaries, localised in the center of Portugal and distant 30-40 km apart, present quite different freshwater inflows, surface areas and water residence times. A study performed in 2001 revealed that the magnitude of CO2 fluxes in the two estuarine systems varied seasonally. CO2 emissions during the huge rainfall winter were similar in both estuaries, reaching a mean value of ~50 mmol m-2 d-1, while in spring emissions from Sado were ~6 times higher then Tagus ones, attaining a mean value of 62 mmol m-2 d-1. Nevertheless, in both sampling periods, Sado estuary showed, within the upper estuary (salinity

Oliveira, A. P.; Cabeçadas, G.; Nogueira, M.

2009-04-01

366

A classification of U.S. estuaries based on physical and hydrologic attributes  

Science.gov (United States)

A classification of U.S. estuaries is presented based on estuarine characteristics that have been identified as important for quantifying stressor-response relationships in coastal systems. Estuaries within a class have similar physical and hydrologic characteristics and would be expected to demonstrate similar biological responses to stressor loads from the adjacent watersheds. Nine classes of estuaries were identified by applying cluster analysis to a database for 138 U.S. estuarine drainage areas. The database included physical measures of estuarine areas, depth and volume, as well as hydrologic parameters (i.e., tide height, tidal prism volume, freshwater inflow rates, salinity, and temperature). The ability of an estuary to dilute or flush pollutants can be estimated using physical and hydrologic properties such as volume, bathymetry, freshwater inflow and tidal exchange rates which influence residence time and affect pollutant loading rates. Thus, physical and hydrologic characteristics can be used to estimate the susceptibility of estuaries to pollutant effects. This classification of estuaries can be used by natural resource managers to describe and inventory coastal systems, understand stressor impacts, predict which systems are most sensitive to stressors, and manage and protect coastal resources. ?? Springer Science+Business Media B.V. 2007.

Engle, V.D.; Kurtz, J.C.; Smith, L.M.; Chancy, C.; Bourgeois, P.

2007-01-01

367

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

Directory of Open Access Journals (Sweden)

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

Joaquim I. Goes

2013-03-01

368

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 (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

369

Migration dynamics of clupeoids in the Schelde estuary: a stable isotope approach  

DEFF Research Database (Denmark)

Large numbers of young of the year herring (Clupea harengus L.) and sprat (Sprattus sprattus (L.)) typically enter and remain within North Sea estuaries during the winter months. The main purpose of this study was to examine their migration dynamics between the North Sea and the Schelde estuary using C and N stable isotopes. Prior to this,  stomach contents were used to verify the isotopic differences between the food sources at the sampling stations. From May 2000 to April 2001 fish were collected monthly in the upper and lower estuary. Muscle tissue and stomach contents were analyzed for d13C and d15N using an EA-IRMS. Based on the stomach contents, it was demonstrated that d15N could not be used as a tracer for fish migration because the longitudinal estuarine d15N gradient had reversed completely during autumn. The d13C gradient, however, was found to be reliable for studying fish movement in the Schelde estuary. Seasonal movements of clupeoids in the Schelde estuary were analyzed by separating the temporal abundance patterns into migration groups based on their muscle isotopic composition. Immigration and emigration seem to occur continuously throughout the year. Most exchange occurred in November. During winter, immigration remained high but gradually decreased. Although the herring and sprat abundance further declined in the estuary during February and March, large seaward emigration was not fully demonstrated. As temporal overlap between immigration and emigration is concluded the results support the hypothesis that migration to estuarine nurseries is individually based.

Guelinckx, J.; Maes, J.

2006-01-01

370

Migration dynamics of clupeoids in the Schelde estuary: A stable isotope approach  

Science.gov (United States)

Large numbers of young of the year herring ( Clupea harengus L.) and sprat ( Sprattus sprattus (L.)) typically enter and remain within North Sea estuaries during the winter months. The main purpose of this study was to examine their migration dynamics between the North Sea and the Schelde estuary using C and N stable isotopes. Prior to this, stomach contents were used to verify the isotopic differences between the food sources at the sampling stations. From May 2000 to April 2001 fish were collected monthly in the upper and lower estuary. Muscle tissue and stomach contents were analyzed for ?13C and ?15N using an EA-IRMS. Based on the stomach contents, it was demonstrated that ?15N could not be used as a tracer for fish migration because the longitudinal estuarine ?15N gradient had reversed completely during autumn. The ?13C gradient, however, was found to be reliable for studying fish movement in the Schelde estuary. Seasonal movements of clupeoids in the Schelde estuary were analyzed by separating the temporal abundance patterns into migration groups based on their muscle isotopic composition. Immigration and emigration seem to occur continuously throughout the year. Most exchange occurred in November. During winter, immigration remained high but gradually decreased. Although the herring and sprat abundance further declined in the estuary during February and March, large seaward emigration was not fully demonstrated. As temporal overlap between immigration and emigration is concluded the results support the hypothesis that migration to estuarine nurseries is individually based.

Guelinckx, Jef; Maes, Joachim; De Brabandere, Loreto; Dehairs, Frank; Ollevier, Frans

2006-02-01

371

A model to predict the level of artificial radionuclides in environmental materials in the Severn Estuary and the Bristol Channel  

International Nuclear Information System (INIS)

The NRPB SEVERN compartment model, of the Bristol Channel and Severn Estuary, has been developed for used in predicting environmental concentrations of artificial radionuclides present in the estuary. A comparison between predicted and measured values of salinity and environmental 137Cs concentrations has demonstrated the overall validity of the model. SEVERN has been used to assess the radiological impact of radionuclides present in the estuary which result from low-level routine discharges from the nuclear power industry. (author)

372

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

OpenAIRE

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

Wu, Steven M.

2012-01-01

373

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.)

374

Role of different salt marsh plants on metal retention in an urban estuary (Lima estuary, NW Portugal)  

Science.gov (United States)

The aim of the present work was to understand the role different salt marsh plants on metal distribution and retention in the Lima River estuary (NW Portugal), which to our knowledge have not been ascertained in this area yet. The knowledge of these differences is an important requirement for the development of appropriate management strategies, and is poorly described for Eurosiberian estuaries, like the one selected. In addition it is important to understand the difference among introduced and native salt marsh plants. In this work, metal levels (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were surveyed (by atomic absorption spectrometry) in sediments from sites vegetated with Juncus maritimus, Spartina patens, Phragmites australis and Triglochin striata (rhizo-sediments), in non-vegetated sediments and in the different tissues of the plants (roots, rhizomes and aerial shoots). In general, rhizo-sediments had higher metal concentrations than non-vegetated sediments, a feature that seems common to sediments colonized by salt marsh plants of different estuarine areas. All plants concentrated metals, at least Cd, Cu and Zn (and Pb for T. striata) in their belowground structures ([ M] belowground tissues/[ M] non-vegetated sediment > 1). However, when considered per unit of salt marsh area, the different selected plants played a different role on sediment metal distribution and retention. Triglochin striata retained a significant metal burden in it belowground structures (root plus rhizomes) acting like a possible phyto-stabilizer, whereas P. australis had an higher metal burden in aboveground tissues acting as a possible phyto-extractor. As for J. maritimus and S. patens, metal burden distribution between above and belowground structures depended on the metal, with J. maritimus retaining, for instance, much more Cd and Cu in the aboveground than in the belowground structures. Therefore, the presence of invasive and exotic plants in some areas of the salt marsh may considerably affect metal distribution and retention in the estuarine region.

Almeida, C. M. R.; Mucha, Ana P.; Teresa Vasconcelos, M.

2011-01-01

375

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

International Nuclear Information System (INIS)

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

376

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

Science.gov (United States)

...Regulatory Commission Notice of Staff Attendance at Southwest Power...and Strategic Planning Committee Meetings January 5, 2011. The Federal...gives notice that members of its staff may attend the meetings of the Southwest Power...

2011-01-13

377

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

Science.gov (United States)

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

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

2014-05-01

378

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

Science.gov (United States)

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

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

2013-10-01

379

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

Science.gov (United States)

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

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

2002-01-01

380

Exploring new drilling prospects in the southwest Pacific  

Science.gov (United States)

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

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

2014-04-01

381

Radionuclide transfer from Sellafield to south-west Scotland  

International Nuclear Information System (INIS)

A transect of surface marine sediment was collected off and between Sellafield and Kirkcudbright Bay in south-west Scotland. The results indicate that anthropogenic radionuclide activity concentrations are variable primarily as a function of sediment type or particle size distribution and are independent of distance from source. This fact, together with relative uniformity of radionuclide activity quotients and chemical associations, clearly demonstrates direct physical migration of particle-associated activity from the point of discharge off the Cumbrian coast to the north Solway coast. Relative constancy of 241Am/241Pu activity quotients suggests that this transport process is rapid, occurring on a timescale of years rather than decades. In summary, dissolved nuclide transport of actinides is of secondary importance in this region. (author)

382

Regional analysis of stream salinisation in southwest Western Australia  

Science.gov (United States)

Stream salinities in southwest Western Australia are strongly influenced by land use, soil salt storage and rainfall. The salinities of forest catchments are fresh and have declined over the last two decades due to decreasing groundwater solute discharge under lower than average rainfall conditions. Catchments extending to or lying in lower rainfall areas ( < 900 mm yr -1) where agricultural clearing has taken place have stream salinities ranging from marginal to saline. Over the last 20 years stream salinities have increased rapidly on these catchments. Higher stream salinities are associated with higher catchment salt storage (lower rainfall) and a higher proportion of catchment cleared. Annual salinities of salt-affected catchments vary inversely with annual rainfall. A projected trend of decreasing rainfall is likely to exacerbate the stream salinity problem.

Schofield, N. J.; Ruprecht, J. K.

1989-12-01

383

Radioactivity of Phosphogypsum in South-West of Spain  

International Nuclear Information System (INIS)

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

384

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

385

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

386

Marine mammal strandings in the New Caledonia region, Southwest Pacific.  

Science.gov (United States)

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 (18 single strandings, 2 pair strandings), pygmy sperm whale, Kogia breviceps (5 single strandings), dwarf sperm whale, K. sima (2 single strandings, 1 triple stranding), Blainville's beaked whale, Mesoplodon densirostris (2 single strandings), short-finned pilot whale, Globicephala macrorhynchus (4 strandings, 56 individuals), melon-headed whale, Peponocephala electra (1 single stranding and 2 mass strandings totalling 231 individuals), common dolphin, Delphinus delphis (1 single stranding), spinner dolphin, Stenella longirostris (1 pair stranding and 2 mass strandings of groups of approximately 30 individuals each), Indian Ocean bottlenose dolphin, Tursiops aduncus (2 single strandings), dugong, Dugong dugon (14 single strandings), and New Zealand fur seal, Arctocephalus forsteri (3 single strandings). A stranded rorqual identified as an Antarctic minke whale (B. bonaerensis), with coloration patterns that did not match known descriptions, was also reported. Sei whale was recorded for the first time in the tropical Southwest Pacific region and Antarctic minke whale, melon-headed whale, and Indian Ocean bottlenose dolphin were recorded for the first time in New Caledonia. Strandings of sperm whales were most frequent in the spring, but also occurred in autumn months, suggesting a seasonal pattern of occurrence possibly related to seasonal migration. One stranded humpback whale bore the scars of a killer whale's attack and one dugong was injured by a shark. Scars left by propellers were noted on several stranded animals including one Antarctic minke whale, one pygmy sperm whale, one dwarf sperm whale, and four dugongs. Collisions with vessels were suspected to be a frequent cause of death for dugong. PMID:16644500

Borsa, Philippe

2006-04-01

387

Stable isotopic variations in precipitation in Southwest China  

Science.gov (United States)

This study analyzes the relationships of stable isotopes in precipitation with temperature, air pressure and humidity at different altitudes, and the potential influencing mechanisms of control factors on the stable isotopes in precipitation in Southwest China. There appear marked negative correlations of the ? 18O in precipitation with precipitation amount, vapor pressure and atmospheric precipitable water (PW) at the Mengzi, Simao and Tengchong stations on the synoptic timescale; the marked negative correlations between the ? 18O in precipitation and the diurnal mean temperature at 400 hPa, 500 hPa, 700 hPa and 850 hPa are different from the temperature effect in middle-high-latitude inland areas. In addition, the notable positive correlation between the ? 18O in precipitation and the dew-point deficit ? T d at different altitudes is found at the three stations. Precipitation is not the only factor generating an amount effect. Probably, the amount effect is related to the variations of atmospheric circulation and vapor origins. On the annual timescale, the annual precipitation amount weighted-mean ? 18O displays negative correlations not only with annual precipitation but also with annual mean temperature at 500 hPa. It can be deduced that, in the years with an abnormally strong summer monsoon, more warm and wet air from low-latitude oceans is transported northward along the vapor channel located in Southwest China and generates abnormally strong rainfall on the way. Meanwhile, the abnormally strong condensation process will release more condensed latent heat in the atmosphere, and this will lead to a rise of atmospheric temperature during rainfall but a decline of ? 18O in the precipitation. On the other hand, in the years with an abnormally weak summer monsoon, the precipitation and the atmospheric temperature during rainfalls decrease abnormally but the ? 18O in precipitation increases.

Zhang, Xinping; Jin, Huijun; Sun, Weizhen

2006-12-01

388

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.

389

Temporal variation of the water budget in Central Southwest Asia  

Science.gov (United States)

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

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

2009-05-01

390

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

391

Variability of macrobenthic assemblages under abnormal climatic conditions in a small scale tropical estuary  

Science.gov (United States)

Macrobenthic assemblages associated with mangrove mud flats were studied at three stations in the Dagua River Estuary (Colombian coast, Tropical Eastern Pacific) to assess broad distribution patterns with relation to hydrographical and sediment conditions during the cold (La Niña) phase of the 1997-2000 El Niño/Niña Phenomenon (ENSO Niño/Niña). During the study period, abnormal water and interstitial temperature, high dissolved oxygen and low salinity conditions were present in the water column of the small scale (5.5 km long) estuary, reducing its extension and moving estuarine conditions downstream. Sediment samples were collected for sediment analysis (grain size, water content) and biological studies (specific composition, relative abundance, diversity, evenness and trophic structure) from quadrates (25 × 25 cm) located in the lower, middle and upper regions of the estuary. Macrobenthic assemblages at the upper estuary were composed of 78 species and dominated by Tanaidaceans, suggesting the direct effect of freshwater inflow, and by some polychaetes in the lower region, showing marine influence. Diversity and evenness increased along the salinity gradient from the upper region of the estuary towards the lower region. Surface deposit feeders (SDF, 72.2%) and sub-surface deposit feeders (SSDF, 21%) were dominant as trophic groups. SDF were the most abundant group in the upper estuary, SSDF dominated the lower estuary. These patterns were controlled by the abnormal conditions generated by the cold phase of ENSO (Niño/Niña) in water temperature, higher deposition of organic matter and low salinity that changed the estuarine's typical macrobenthic assemblage structure, with dominance of marine species to one characterized by few abundant freshwater species (Tanaidaceans, insects).

Lucero R., Carlos H.; Cantera K., Jaime R.; Romero, Isabel C.

2006-06-01

392

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

393

Sr and 87Sr/86Sr in estuaries of western India: Impact of submarine groundwater discharge  

Science.gov (United States)

Dissolved Sr and 87Sr/86Sr are measured in the Narmada, Tapi and the Mandovi estuaries linked to the eastern Arabian Sea. The concentration of dissolved Sr and 87Sr/86Sr in the river water endmembers show significant differences reflecting the lithologies they drain. The distribution of Sr in all these estuaries shows a near perfect two endmember mixing between river water and seawater suggesting that there is no discernible net addition/removal of Sr from the estuarine waters. In contrast, 87Sr/86Sr shows non-conservative behaviour in all these estuaries, its distribution exhibits significant departure from the theoretical mixing lines. A likely mechanism for this difference in the behaviour between dissolved Sr and its 87Sr/86Sr is the discharge of submarine groundwater (SGD) which can modify the 87Sr/86Sr of the estuarine waters by exchange with sediments without causing measurable changes in Sr concentration. The impact of such an exchange process on the 87Sr/86Sr of the estuaries and therefore on the Sr isotope composition of dissolved Sr entering the Arabian Sea differs among the three estuaries and also between seasons in the Narmada. The non-conservative behaviour of 87Sr/86Sr provides a handle to estimate the quantum of SGD to these estuaries. The Sr concentration, 87Sr/86Sr ratio and salinity of the submarine groundwater and estimate of its fluxes to the Narmada estuary have been made using inverse model calculations. The model derived SGD flow rates are ˜5 and 280 cm/day during pre-monsoon and monsoon, respectively. The more radiogenic Sr isotope composition of SGD relative to the seawater suggests that SGD acts as an additional source of 87Sr to the Arabian Sea.

Rahaman, Waliur; Singh, Sunil Kumar

2012-05-01

394

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

395

Quantifying reduction in ecological risk in Penrhyn Estuary, Sydney, Australia, following groundwater remediation.  

Science.gov (United States)

The environmental risk associated with discharge of contaminated groundwater containing a complex mixture of at least 14 volatile chlorinated hydrocarbons (VCHs) to Penrhyn Estuary, Sydney, Australia has previously been assessed. That probabilistic ecological risk assessment (ERA) was undertaken using surface water monitoring data from 2004 to 2005. Subsequently, in 2006, a groundwater remediation system was installed and commissioned to prevent further discharge of VCHs into the estuary. The present study assessed the ecological risk posed to the estuary after 2006 to evaluate the success of the remediation system. The ERA was undertaken using toxicity data derived from direct toxicity assessment (DTA) of preremediation contaminated groundwater using indigenous species, exposure data from surface water monitoring between 2007 and 2008 and the joint probability curve (JPC) methodology. The risk posed was measured in 4 zones of the entire site: source area (2), tributary (2), the inner estuary and outer estuary at high, low, and a combination of high and low tides. In the 2 source areas, risk decreased by over 2 and over 1 orders of magnitude to maximum values of less than 0.5%. In 1 estuary, risk decreased by over 1 order of magnitude, from a maximum of 36% to a maximum of 2.3%. At the other tributary and both the inner and outer estuaries, the risk decreased to less than 1%, regardless of the tide. This analysis revealed that the remediation system was very effective and that the standard level of protection required for slightly to moderately affected ecosystems (95% of species) by the Australian and New Zealand Guidelines for Fresh and Marine Water Quality was met postremediation. PMID:21557465

Hunt, James; Birch, Gavin; Warne, Michael

2012-01-01

396

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

397

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

398

Concerns in assessing radiological releases to a major estuary  

International Nuclear Information System (INIS)

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

399

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

400

Density-dependent surface water-groundwater interaction and nutrient discharge in the Swan-Canning Estuary  

Science.gov (United States)

Salinity in the Swan-Canning Estuary, Western Australia, varies seasonally from freshwater conditions in winter up to the salinity of seawater in summer. Field observations show that the resulting seasonal density contrasts between the estuary and the adjacent fresh groundwater system are sufficient to drive mixed-convection cells that give rise to circulation of river water in the aquifer. In this study, we examine the role of steady density-driven convection as a mechanism that contributes to the exchange of dissolved nutrients, particularly ammonium, between the Swan-Canning Estuary and the local groundwater system. We present results from two-dimensional (section) and three-dimensional density-coupled flow and mass transport modelling, in comparison with Glover's abrupt-interface solution for saltwater intrusion. The modelling is focused on developing an understanding of the physical processes that influence the long-term or mean convective behaviour of groundwater beneath the estuary. It is shown that the convective stability depends fundamentally on the interplay between two factors: (1) the downward destabilizing buoyancy effect of density contrasts between the estuary and aquifer; and (2) the upward stabilizing influence of regional groundwater discharge. The structure of convection cells beneath the estuary and recirculation rates of estuary water within the groundwater system are shown to be related to a flow-modified Rayleigh number that depends critically on the aquifer anisotropy and estuary meander pattern. The recirculation of estuary water by these mechanisms is responsible for transport of high concentrations of ammonium, observed in pore fluids in the estuary bed sediments, into groundwater and its eventual return to the estuary.

Smith, Anthony J.; Turner, Jeffrey V.

2001-09-01

401

Tide-driven fluid mud transport in the Ems estuary  

Science.gov (United States)

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

Becker, Marius; Maushake, Christian; Winter, Christian

2014-05-01

402

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