WorldWideScience
1

[Polychaete community in mangrove and salt marsh in Zhangjiang River Estuary, Fujian Province of East China].  

Science.gov (United States)

In order to understand the community structure of polychaete in different botanic habitats in Zhangjiang River Estuary, an investigation was conducted in the habitats of Kandelia candel, Aegiceras corniculatum, Spartina alterniflora, and Avicennia marina in four seasons, 2010. A total of 15 polychaete species were recorded, and 6 species including Eteone delta, Namalycastis abiuma, Paraleonnates uschakovi, Polydora ciliata, Capitella capitata, and Mediomastus californiensis were found in the four habitats and four seasons. The density, biomass, richness index, evenness index, and diversity index of the polychaete had no significant differences among seasons but significant differences among habitats, and the dominant species of polychaete in S. alterniflora habitat differed from that in the other three mangrove habitats. Pearson correlation analysis showed that in the mangrove and salt marsh, there were no significant correlations between the polychaete parameters (density, biomass, richness index, evenness index, and diversity index) and the environmental factors (sediment temperature, salinity, total organic carbon, and total nitrogen), except that the species number of polychaete had significant correlation with sediment temperature due to the common species of polychaete such as Capitella capitata, Mediomastus californiensis, and Namalycastis abiuma in the mangrove and salt marsh in Zhangjiang River Estuary being of eurytherm and eurysalinity, and resistant to high organic matter content. PMID:22803456

Chen, Xin-Wei; Cai, Li-Zhe; Wu, Chen; Peng, Xin; Cao, Jing; Xu, Peng; Liu, Sha; Fu, Su-Jing

2012-04-01

2

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.

3

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...

4

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

5

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.

6

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

7

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

8

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

9

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

10

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

11

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

12

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

13

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

14

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

15

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

16

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.

17

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

18

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

19

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

20

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

21

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

22

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.

23

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

24

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

25

Expertise mission at the Rance river estuary  

International Nuclear Information System (INIS)

The Rance tidal power plant was inaugurated in 1968. This report presents the environmental impacts of the dam (choking up of Rance river with marine sediments) and proposes several remedial actions for the preservation of the site: dredging and agricultural valorization of muds by spreading. This project leads to several questions which are analyzed in the document: populations reaction, salinity of muds, dimensions of the decantation pool, impact of muds on cultures, lack of alternative solutions etc.. (J.S.)

26

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

27

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

28

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

29

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

30

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

31

Plutonium AMS measurements in Yangtze River estuary sediment  

International Nuclear Information System (INIS)

The Yangtze River is the largest single source of sediment to the continental shelf of the East China Sea. The quantity of material exported by the river is expected to decrease substantially as a consequence of an extensive continuing program of dam construction within the river catchment. We report here AMS measurements of plutonium isotope concentrations and ratios for selected depth increments from a sediment core, collected from the sub-aqueous delta of the Yangtze River estuary. The Pu derives from atmospheric nuclear weapons testing in the 1950s and 1960s, and is potentially a useful tracer of sediment deposition times in the marine environment. The results show considerable structure in the depth-concentration profile, and offer an excellent opportunity to compare Pu with the more commonly used 137Cs isotopic tracer. The AMS data show superior sensitivity and indicate that the 240Pu/239Pu ratio can provide a check on the deposition dates. The changes in the 240Pu and 239Pu concentrations and the 240Pu/239Pu ratios with sediment depth all indicate the possibility of using Pu as a geochronological tool for coastal sediment studies.

32

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

33

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...

34

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

35

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

36

Changes in Epipelic Diatom Diversity from the Savannah River Estuary  

Directory of Open Access Journals (Sweden)

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

Joseph N. Dominy Jr.

2013-02-01

37

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

38

The behavior of selenium and arsenic in the Zhujiang (Pearl River) Estuary, South China Sea  

Science.gov (United States)

Two cruises were undertaken to study the selenium species and arsenic, and their relationship with marine production in the Zhujiang (Pearl River) Estuary, covering both wet (July, 1999) and dry (January, 2000) seasons. Concentrations of dissolved Se (IV), Se (VI) and arsenic in the Zhujiang River are generally within the range of Chinese rivers and other large systems, like the Rhone River and Panama River. In January 2000, the concentration of selenium was lower than that in the July 1999. Total dissolved inorganic selenium averaged 2.77 nmol L -1 in the winter and 4.15 nmol L -1 in the summer, with Se (VI) accounting for 55% and 58%, respectively. Total dissolved inorganic arsenic averaged 25.8 nmol L -1 in the winter and 22.3 nmol L -1 in the summer. The data indicated that dissolved arsenic and selenium did not behave conservatively in the estuary. An important mobilization of dissolved selenium and arsenic was observed from the river up to halfway in the estuary. Both input flux (from river to estuary) and output flux (from estuary to coastal zone) of dissolved selenium and arsenic were calculated from statistical interpretations of the salinity profiles.

Yao, Qing-Zheng; Zhang, Jing; Qin, Xiao-Guang; Xiong, Hui; Dong, Li-Xian

2006-03-01

39

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

40

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

41

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

42

Sediment trapping by haloclines of a river plume in the Pearl River Estuary  

Science.gov (United States)

Sediment trapping by the halocline of a river plume was investigated over a spring-neap tidal cycle in the 2010 dry season in the Pearl River Estuary. Benthic tripod observations and concurrent shipboard measurements were conducted to examine mean and turbulent flows, and sediment distributions. The field observations showed that suspended particles are apparently concentrated on the halocline of the river plume, forming a patchy high-concentration suspension with larger floc sizes. This sediment trapping occurred only on the neap tide when the estuary was highly stratified. An estimation of the gradient Richardson number indicates that stratification suppression is dominant below the halocline, whereas shear-induced instability occurs above the halocline. The turbulent kinetic energy balance demonstrates that the buoyancy flux dominates over viscous dissipation in turbulence destruction. Therefore, the trapping of suspended sediment with large floc sizes on the halocline is induced by both salinity stratification and buoyancy-induced instability. This finding can explain the role of salinity stratification in the mechanism for estuarine turbidity maxima and long-distance transportation of suspended sediment.

Ren, Jie; Wu, Jiaxue

2014-07-01

43

Proceedings of the Columbia River Estuary Conference on Ecosystem Restoration.  

Energy Technology Data Exchange (ETDEWEB)

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

U.S. Bonneville Power Administration

2008-08-01

44

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

45

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

46

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

47

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

International Nuclear Information System (INIS)

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

48

Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments of rivers and an estuary in Shanghai, China  

International Nuclear Information System (INIS)

Concentrations, spatial distribution and sources of 17 polycyclic aromatic hydrocarbons (PAHs) and methylnaphthalene were investigated in surface sediments of rivers and an estuary in Shanghai, China. Total PAH concentrations, excluding perylene, ranged from 107 to 1707 ng/g-dw. Sedimentary PAH concentrations of the Huangpu River were higher than those of the Yangtze Estuary. The concentration of the Suzhou River was close to the average concentration of the Huangpu River. PAHs source analysis suggested that, in the Yangtze Estuary, PAHs at locations far away from cities were mainly from petrogenic sources. At other locations, both petrogenic and pyrogenic inputs were significant. In the Huangpu and Suzhou Rivers, pyrogenic input outweighed other sources. The pyrogenic PAHs in the upper reaches of the Huangpu River were mainly from the incomplete combustion of grass, wood and coal, and those in the middle and lower reaches were from vehicle and vessel exhaust. - Surface sediments of two rivers and an estuary in Shanghai were contaminated by PAHs

49

Hydromedusae composition, occurrence, and distribution in the Caeté river estuary, Pará  

Directory of Open Access Journals (Sweden)

Full Text Available Species composition and spatio-temporal variation in density of hydromedusae along a salinity gradient were investigated in the Caeté river estuary, northern Brazil in June and December, 1998 (dry season and in February and May, 1999 (rainy season. The Caeté river estuary was characterized by high spatial and temporal variations in salinity. Twelve taxa were recorded of which Octocanna haeckeli represent to new record for coastal waters of the northeast coast of Pará state. In general, the highest and lowest densities were found in December and May, respectively. This observation was probably due to differences in the rainfall rates between the two studied periods.

André Magalhães

2006-12-01

50

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

51

Occurrence and fate of triclosan and triclocarban in a subtropical river and its estuary.  

Science.gov (United States)

The occurrence of triclosan (TCS) and triclocarban (TCC) in a subtropical river (Jiulong River) and its estuary was investigated for two years. TCS and TCC were ubiquitously detected in the Jiulong River and its estuary. The levels of TCS and TCC ranged from less than the method detection limit to 64 ng/L and from 0.05 to 14.1 ng/L in the river, respectively. The levels of TCS and TCC in the estuary ranged from 2.56 to 27.25 ng/L and 0.38 to 5.76 ng/L, respectively. Temporal and spatial variations of TCS and TCC in the Jiulong River and its estuary were observed during the investigation. The weather conditions did not show significant correlations with TCS and TCC, whereas several water quality parameters showed high correlations with TCS and TCC. The microcosm studies showed that both direct photolysis and biodegradation contributed to TCS removal, whereas indirect photolysis was important for TCC removal in the surface water. PMID:25227953

Lv, Min; Sun, Qian; Xu, Haili; Lin, Lifeng; Chen, Meng; Yu, Chang-Ping

2014-11-15

52

River discharge controls phytoplankton dynamics in the northern San Francisco Bay estuary  

Science.gov (United States)

Phytoplankton dynamics in the upper reach of the northern San Francisco Bay estuary are usually characterized by low biomass dominated by microflagellates or freshwater diatoms in winter, and high biomass dominated by neritic diatoms in summer. During two successive years of very low river discharge (the drought of 1976-77), the summer diatom bloom was absent. This is consistent with the hypothesis that formation of the diatom population maximum is a consequence of the same physical mechanisms that create local maxima of suspended sediments in partially-mixed estuaries: density-selective retention of particles within an estuarine circulation cell. Because the estuary is turbid, calculated phytoplankton growth rates are small in the central deep channel but are relatively large in lateral shallow embayments where light limination is less severe. When river discharge falls within a critical range (100-350 m3 s-1) that positions the suspended particulate maximum adjacent to the productive shallow bays, the population of neritic diatoms increases. However, during periods of high discharge (winter) or during periods of very low discharge (drought), the suspended particulate maximum is less well-defined and is uncoupled (positioned downstream or upstream) from the shallow bays of the upper estuary, and the population of neritic diatoms declines. Hence, the biomass and community composition of phytoplankton in this estuary are controlled by river discharge. ?? 1983.

Cloern, J.E.; Alpine, A.E.; Cole, B.E.; Wong, R.L.J.; Arthur, J.F.; Ball, M.D.

1983-01-01

53

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

Directory of Open Access Journals (Sweden)

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

Curt Peterson

2014-03-01

54

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

55

Preliminary evaluation of ecological risk for the city area from the Pearl River Estuary.  

Science.gov (United States)

It is essential to evaluate the ecological risk for the estuary cities area for the environmental restoration of the estuary. The ecological risk of six city areas from the Pearl River Estuary were evaluated by using the relative risk model. The relative risk assessment method was developed by considering the river network density in the sub-region. The results indicated that Dongguan had the largest ecological risk pressure with total risk scores as high as 10,846.3, and Hong Kong had the lowest ecological risk pressure with total risk scores up to 4,104.6. The greatest source was domestic sewage with total risk scores as high as 1,798.6, followed by urbanization and industry. Oxygen-consuming organic pollutants, organic toxic pollutants and nutrients were the major stressors of the water environment. In terms of habitats, the water environment was enduring the greatest pressure. For the endpoints, water deterioration faced the largest risk pressure. PMID:25429453

Chen, Qiuying; Ho, KinChung; Liu, Jingling

2014-01-01

56

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2005  

Energy Technology Data Exchange (ETDEWEB)

This report is the second annual report of a six-year project to evaluate the cumulative effects of habitat restoration projects in the Columbia River Estuary, conducted by Pacific Northwest National Laboratory's Marine Sciences Laboratory, NOAA's National Marine Fisheries Service Pt. Adams Biological Field Station, and the Columbia River Estuary Study Taskforce for the US Army Corps of Engineers. In 2005, baseline data were collected on two restoration sites and two associated reference sites in the Columbia River estuary. The sites represent two habitat types of the estuary--brackish marsh and freshwater swamp--that have sustained substantial losses in area and that may play important roles for salmonids. Baseline data collected included vegetation and elevation surveys, above and below-ground biomass, water depth and temperature, nutrient flux, fish species composition, and channel geometry. Following baseline data collection, three kinds of restoration actions for hydrological reconnection were implemented in several locations on the sites: tidegate replacements (2) at Vera Slough, near the city of Astoria in Oregon State, and culvert replacements (2) and dike breaches (3) at Kandoll Farm in the Grays River watershed in Washington State. Limited post-restoration data were collected: photo points, nutrient flux, water depth and temperature, and channel cross-sections. In subsequent work, this and additional post-restoration data will be used in conjunction with data from other sites to estimate net effects of hydrological reconnection restoration projects throughout the estuary. This project is establishing methods for evaluating the effectiveness of individual projects and a framework for assessing estuary-wide cumulative effects including a protocol manual for monitoring restoration and reference sites.

Diefenderfer, Heida L.; Thom, Ronald M.; Borde, Amy B.; Roegner, G. C.; Whiting, Allan H.; Johnson, Gary E.; Dawley, Earl; Skalski, John R.; Vavrinec, John; Ebberts, Blaine D.

2006-12-20

57

The Partitioning of Triclosan between Aqueous and Particulate Phases in the Hudson River Estuary  

Science.gov (United States)

The distribution of Triclosan within the Hudson River Estuary can be explained by a balance among the overall effluent inputs from municipal sewage treatment facilities, dilution of Triclosan concentrations in the water column with freshwater and seawater inputs, removal of Tricl...

58

[Shrimp community structure and its influential factors in the Jiaojiang River estuary during spring and autumn].  

Science.gov (United States)

Based on the data from two oceanographic surveys during April and October 2010, the spatial and seasonal variations in composition, dominance, and diversity of shrimp communities, as well as the influential factors in the Jiaojiang River estuary were analyzed. A total of 16 species of shrimp were found, which belonged to 12 families under 8 genera. 14 species of shrimp were found in spring (April) and 12 species in autumn (October). With the employment of index of relative importance (IRI), in spring 6 dominant species were identified, as Acetes chinensis, Alpheus distinguendus, Parapenaeopsis hardwickii, Leptochela gracilis, Alpheus juponicus and Palaemon gravieri, and in autumn 3 dominant species were found as Solenocera crassicornis, Parapenaeopsis hardwickii and Metapenaeus joyneri. Eurythermal and eurysaline shrimp community prevailed in the Jiaojiang River estuary, followed by eurythermal and hyposaline shrimp community. Margalef index (D), Shannon index (H) and Pielou's evenness index were used to evaluate the diversity of shrimp community in the studied area. The stations with higher value of D and H were mainly located in the west of the Dachen Island, whereas the Pielou's evenness index was stable all across the Jiaojiang River estuary. By hierarchical cluster analysis and non-metric multidimensional scaling (NMDS) method, the results indicated that shrimp communities had significant seasonal and spatial variations. Depth was the most important factor that affected variations in the shrimp community structure in the Jiaojiang River estuary. PMID:24697077

Qi, Hai-Ming; Sun, Yue; Xu, Zhao-Li; Sun, Lu-Feng; Gao, Qian; Que, Jiang-Long; Tian, Wei

2013-12-01

59

MODELLING KEPONE IN THE STRIPED BASS FOOD CHAIN OF THE JAMES RIVER ESTUARY  

Science.gov (United States)

A mathematical model that computes the accumulation of Kepone in the striped bass food chain of the James River estuary was developed. The purpose of the model was to help understand the relationship of Kepone levels in important fish species to sediment and water column Kepone c...

60

Protocols for Monitoring Habitat Restoration Projects in the Lower Columbia River and Estuary  

Energy Technology Data Exchange (ETDEWEB)

Protocols for monitoring salmon habitat restoration projects are essential for the U.S. Army Corps of Engineers' environmental efforts in the Columbia River estuary. This manual provides state-of-the science data collection and analysis methods for landscape features, water quality, and fish species composition, among others.

Roegner, G. Curtis; Diefenderfer, Heida L.; Borde, Amy B.; Thom, Ronald M.; Dawley, Earl M.; Whiting, Allan H.; Zimmerman, Shon A.; Johnson, Gary E.

2008-04-25

61

Chemical speciation of inorganic pollutants in river-estuary-sea water systems.  

Science.gov (United States)

Monitoring studies and thermodynamic modeling were used to reveal the changes of inorganic chemical species of some water pollutants (nutrients and trace metals such as Fe, Mn, Zn, Cu, Cd and Pb) inthe river-estuary-sea water system. The case studies were two rivers, Kamchiya and Ropotamo, representing part of the Bulgarian Black Sea water catchment area, and having different flow characteristics. There were no major differences in inorganic chemical species of the two river systems. NO3(-) and NO2(-) chemical species showed no changes along the river-estuary-sea water system. Concerning phosphates six different species were calculated and differences between the three parts of the systems were established. The HPO4(2-) and H2PO4(-) species were found to be dominant in river waters. The H2PO4(-) species quickly decreased at the expense of HPO4(2-) and Ca, Mg and Na phosphate complexes in estuary and seawater. Trace metals showed a great variety of chemical species. Fe(OH)2(+) species prevailed in river waters, and Fe(OH)3(0) species--in sea waters. Me2+ and MeCO3(0) (Me = Cu, Pb) and PbHCO3(+) were dominant in river waters, while Cu(CO3)2(2-) and PbCl(-) species appear also in sea waters. Cd2+ species prevailed in river and estuary waters, and CdCln(2-n) (n = 1-3) species, in seawater. Free Zn2+ species predominated in all systems but downstream their percentage decreased at the expense of Zn phosphates, carbonates,sulfates and chlorides complexes. Only free Mn2+ species were dominant along the systems. PMID:18247147

Tepavitcharova, Stefka; Todorov, Tihomir; Rabadjieva, Diana; Dassenakis, Manos; Paraskevopoulou, Vasiliki

2009-02-01

62

Variability of Organic Carbon Content in Bottom Sediment of Pahang River Estuary, Pahang, Malaysia  

OpenAIRE

The percentage organic carbon content of 62 bottom estuarine sediment in Pahang river estuary were analyzed using the wet dichromate oxidation method. In this study, the organic carbon distribution ranged from 0.09 to 2.05%. The high concentration can be found near the Pahang river mouth while the low concentration occurred at upstream. The sediment particle size at the same transects were also measured with the dry sieving and laser diffraction method. The average concentration of organic ca...

Kamaruzzaman, B. Y.; Siti Waznah, A.; Ong, M. C.; Shahbudin, S.; Jalal, K. C. A.

2009-01-01

63

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

64

A numerical study of the plume in Cape Fear River Estuary and adjacent coastal ocean  

Science.gov (United States)

Cape Fear River Estuary (CFRE), located in southeast North Carolina, is the only river estuary system in the state which is directly connected to the Atlantic Ocean. It is also an important nursery for economically and ecologically important juvenile fish, crabs, shrimp, and other species because of the tidal influence and saline waters. In this study, Environmental Fluid Dynamic Code (EFDC) is used to simulate the salinity plume and trajectory distribution at the mouth of the CFRE and adjacent coastal ocean. Prescribed with the climatological freshwater discharge rates in the rivers, the modeling system was used to simulate the salinity plume and trajectory distribution distribution in the mouth of the CFRE under the influence of climatological wind conditions and tidal effect. We analyzed the plume formation processes and the strong relationship between the various plume distributions with respect to the wind and river discharge in the region. The simulations also indicate that strong winds tend to reduce the surface CFRE plume size and distorting the bulge region near the estuary mouth due to enhanced wind induced surface mixing. Even moderate wind speeds could fully reverse the buoyancy-driven plume structure in CFRE under normal river discharge conditions. Tide and the river discharge also are important factors to influence the plume structure. The comparions between the distribution of salinity plume and trajectory also are discussed in the study.

Xia, M.; Xia, L.; Pietrafesa, L. J.

2006-12-01

65

Marine origin of Savannah river estuary sediments: evidence from radioactive and stable isotope tracers  

International Nuclear Information System (INIS)

To determine the origin of sediments in the Savannah River estuary, we have measured 137Cs and stable isotope ratios of C, N and S in suspended particles and bottom sediments at several sites in the Savannah River and estuary and offshore on the continental shelf. The 137Cs and stable isotope data were used with a two-endmember mixing model to partition the suspended and bottom sediments at sites along a salinity gradient into riverine and marine fractions. Results from the 137Cs measurements indicated that ? 65% of inorganic sediments in suspension or in the top 5 cm of bottom deposits in the estuary were of marine origin. Stable carbon isotope ratios indicated that ?74% of the organic sediments in suspension or on the bottom of the estuary were of marine origin, except for sediments at the lowest salinity estuarine site (< 5ppt) were ? 22% of the sediments were marine-derived. Stable N and S isotope ratios were inconclusive, perhaps reflecting isotopic fractionation during sediments diagenesis at some of the sites. Our results suggest that estuaries, particularly those along submergent coastlines such as the eastern United States, are important sinks for inorganic and organic particles and particle-associated materials from the coastal ocean. (author)

66

Spatial and temporal structure of fluxes between a lateral embayment and the Columbia River estuary channel  

Science.gov (United States)

Estuary channels are often bordered by lateral bays and intertidal flats, which have shallow water depths but large surface areas compared to the neighboring estuary channel. Lateral bays play an important role in production of biogeochemicals in costal margins, and large biogeochemical fluxes are believed to be exchanged between lateral bays, estuary channels, and ultimately the coastal ocean. Due to seasonal weather variation, quantification of biogeochemical production is difficult. To quantify the spatial and temporal structure of water mass and biogeochemical fluxes between an intertidal lateral bay (Cathlamet Bay) and the main channel of the Columbia River estuary, surveys were conducted over semidiurnal tidal cycles during spring and neap tides and during high river flow (May/June) and low flow (September) conditions in 2012. A shipboard downward facing ADCP was used to take continuous measurements on current velocity while at three to five sampling stations along the transect a profiling package measured conductivity, temperature, water depth, dissolved oxygen concentration, chlorophyll fluorescence and optical backscatter. By comparing data from the wet and dry season, we study the influence of salt stratification and buoyancy forcing on the spatial and temporal structure of water mass exchange at the bay/estuary interface as well as gain an understanding of the role of lateral bays in biogeochemical production over the full range of seasonal weather variations.

Haugland, S. M.; Lerczak, J. A.; Needoba, J. A.

2012-12-01

67

Recovery of the critically endangered river pipefish, Syngnathus watermeyeri, in the Kariega Estuary, Eastern Cape province  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english An intensive ichthyofaunal SURVEY IN the permanently open Kariega Estuary along the Eastern Cape coast has identified a breeding population of the critically endangered river pipefish, Syngnathus watermeyeri, within the middle and upper reaches of the system. This is the first recorded capture of th [...] is species in the estuary for over four decades. We suggest that the presence of S. watermeyeri is the result of the heavy rainfall within the region, which contributed to the establishment of optimum habitat requirements (mesohaline conditions and increased food availability) of the pipefish.

P.D., Vorwerk; P.W., Froneman; A.W., Paterson.

2007-06-01

68

Urbanization around the Pearl River Estuary in China from 1973 through 2001 (WMS)  

Science.gov (United States)

The region around the Pearl River Estuary in southern China experienced rapid urban growth in the 1980s and 1990s. This growth was spurred by the establishment of special government economic zones, particularly in Shenzhen, just to the east of the estuary. Urban areas increased by more than 300% between 1988 and 1996. This growth can be directly assessed by remote sensing measurements from space, particularly by comparing images from the Landsat sensors for the last thirty years. This animation shows nine such images in sequence, from the years 1973, 1975, 1977, 1979, 1988, 1992, 1995, 2000, and 2001.

Eric Sokolowsky

2004-02-13

69

Patterns of Chinook salmon migration and residency in the Salmon River estuary (Oregon)  

Science.gov (United States)

We examined variations in the juvenile life history of fall-spawning Chinook salmon, Oncorhynchus tshawytscha, for evidence of change in estuarine residency and migration patterns following the removal of dikes from 145 ha of former salt-marsh habitat in the Salmon River estuary (Oregon). Mark-recapture studies and abundance patterns in the estuary during 2000-2002 describe the following life-history types among Chinook salmon: (1) fry disperse throughout the estuary, and many move into restored tidal-marsh habitats in the early spring soon after emergence; (2) juveniles reside in freshwater for several months, enter the estuary in June or July, and remain for (a) a few weeks or (b) several months before entering the ocean; and (3) juveniles enter the ocean later in the fall after an extended period of rearing upriver and/or in the estuary. The absence of fry migrants in the estuary during spring and early summer in 1975-1977 — a period that precedes restoration of any of the diked marshes — and the extensive use of marsh habitats by fry and fingerlings April-July, 2000-2002 indicate that wetland restoration has increased estuarine rearing opportunities for juvenile Chinook salmon. Year-to-year patterns of estuarine rearing and abundance by juvenile salmon may be influenced by flood and drought conditions that affected adult spawner distribution and over-winter survival of salmon eggs. However, persistent changes in spawner distribution since 1975-1977, including the concentration of hatchery strays in the lower river, may account for the large proportion of fry that now disperse into the estuary soon after emergence in the spring. Although few of these earliest migrants survived to the river mouth, many fry and fingerlings from mid- and upper-basin spawning areas distributed throughout a greater portion of the estuary during the spring and summer and migrated to the ocean over a broader range of sizes and time periods than thirty years ago. The results suggest that wetland recovery has expanded life history variation in the Salmon River population by allowing greater expression of estuarine-resident behaviors.

Bottom, Daniel L.; Jones, Kim K.; Cornwell, Trevan J.; Gray, Ayesha; Simenstad, Charles A.

2005-07-01

70

Contrasts between estuarine and river systems in near-bed turbulent flows in the Zhujiang (Pearl River) Estuary, China  

Science.gov (United States)

A bottom-mounted instrumental tripod was deployed in the tidally energetic Zhujiang (Pearl River) Estuary to examine the contrasting properties of the bottom boundary layer (BBL) flows between estuarine and tide-affected river systems. Three aspects of the BBL flows were investigated to understand the mechanism of the turbulence responses to the large-scale ambient forcing: the flow structures (profile, anisotropy, and spectra), shearing strains and stresses, and the balance of turbulent kinetic energy (TKE). Single log-law profiles and turbulence anisotropy predominated in the two systems, but the non-log regime and stronger anisotropy occurred more frequently at the slack tide in the estuary. The ADV-based turbulence intensities and shearing strains both exceeded their low-frequency counterparts (frictional velocities and mean shears) derived from the logarithmic law. On the contrary, the ADV-based Reynolds stresses were smaller than the log profile-derived bottom stresses, so the hypothesis of a constant stress layer cannot be well satisfied, especially in the river. The bandwidth of the inertial subrange in the river was of one decade larger than in the estuary. The balance between shear production and viscous dissipation was better achieved in the straight river. This first-order balance was significantly broken in the estuary and in the meandering river, by non-shear production/dissipation due to wave-induced fluctuations or salinity/sediment stratification. All these disparities between two systems in turbulence properties are essentially controlled by the anisotropy induced by the large-scale processes such as secondary currents, density stratification. In conclusion, the acceleration of unsteady flows determines the profile structure of the BBL flow, and turbulence anisotropy results in the invalidation of the phenomenological relations such as the constant stress hypothesis and the first-order TKE balance.

Liu, Huan; Wu, Chaoyu; Xu, Weiming; Wu, Jiaxue

2009-08-01

71

The Subtropical Zhujiang (Pearl River) Estuary: Nutrient, Trace Species and Their Relationship to Photosynthesis  

Science.gov (United States)

Two cruises were undertaken to study the nutrients and trace species and their relation to marine production in the Zhujiang (Pearl River) Estuary, which cover both wet (August-September, 1996) and dry (January-February, 1997) seasons. Concentrations of nutrients (NO 3-, NH 4+, PO 43-, and dissolved SiO 2) and other major and trace species (alkalinity, DOC and Al) in the Zhujiang are generally within the range of Chinese rivers and comparable to other large systems, like the Huanghe (Yellow River) and Changjiang (Yangtze River). In the estuary, some species (e.g. SiO 2) illustrate a fairly defined relationship with chlorinity, whereas others show considerable remobilization and/or changes in freshwater end-members, owing to the fact that fresh water enters the South China Sea from eight channels with various water flow and different compositions. The incubation experiments using in situ water samples reveal that while phosphate is the limiting element in riverine effluent plume, the photosynthesis turns to be nitrogen and/or silicon limited further offshore on the shelf region. Trace species (e.g. Cu 2+and Fe 2+) have important impact on the photosynthesis in the Zhujiang Estuary, with Fe 2+to be a more limiting element than Cu 2+. Atmospheric wet deposition may well stimulate photosynthesis and hence demonstrate a potential link with algal blooms in this area. Atmospheric impact on the photosynthesis increases from estuary toward the interior of South China Sea. The experimental data further suggest that in the turbid region of the Zhujiang Estuary, radiation reduction by suspended materials could be an important issue limiting photosynthesis, although the eutrophication is quite common in coastal environments of China.

Zhang, J.; Yu, Z. G.; Wang, J. T.; Ren, J. L.; Chen, H. T.; Xiong, H.; Dong, L. X.; Xu, W. Y.

1999-09-01

72

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

73

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

Science.gov (United States)

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

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

2014-03-15

74

The morphology and morphodynamics of sand-gravel subaquatic dunes: the Raba River estuary, Poland  

OpenAIRE

In the outlet of the Raba River to the Vistula, the biggest river in Poland, the morphology and morphodynamics of sand and fine-gravel subaquatic dunes were investigated. The site is situated in highland region just about the entrance to Polish Carpathians. The dunes formed on the Raba River bed estuary are composed of sand and fine gravel (d50 up to 11 mm). Systematic observation (within the 2000-2005) were made of geometry, sediment composition and hydraulic climate under which the dunes gr...

Radecki-pawlik, Artur; Ksia?z?ek, Leszek

2013-01-01

75

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2006  

Energy Technology Data Exchange (ETDEWEB)

This report is the third annual report of a six-year project to evaluate the cumulative effects of habitat restoration action in the Columbia River Estuary (CRE). The project is being conducted for the U.S. Army Corps of Engineers (Corps) by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory, the Pt. Adams Biological Field Station of the National Marine Fisheries Service, and the Columbia River Estuary Study Taskforce. Measurement of the cumulative effects of ecological restoration projects in the Columbia River estuary is a formidable task because of the size and complexity of the estuarine landscape and the meta-populations of salmonids in the Columbia River basin. Despite the challenges presented by this system, developing and implementing appropriate indicators and methods to measure cumulative effects is the best way to enable estuary managers to track the overall effectiveness of investments in estuarine restoration projects. This project is developing methods to quantify the cumulative effects of multiple restoration activities in the CRE. The overall objectives of the 2006 study were to continue to develop techniques to assess cumulative effects, refine the standard monitoring protocols, and initiate development of an adaptive management system for Corps of Engineers’ habitat restoration monitoring efforts in the CRE. (The adaptive management effort will be reported at a later date.) Field studies during 2006 were conducted in tidal freshwater at Kandoll Farm on the lower Grays River and tidal brackish water at Vera Slough on Youngs Bay. Within each of area, we sampled one natural reference site and one restoration site. We addressed the overall objectives with field work in 2006 that, coupled with previous field data, had specific objectives and resulted in some important findings that are summarized here by chapter in this report. Each chapter of the report contains data on particular monitored variables for pre- and post-restoration conditions at both the Kandoll and Vera study areas.

Johnson, Gary E.; Borde, Amy B.; Dawley, Earl; Diefenderfer, Heida L.; Ebberts, Blaine D.; Putman, Douglas A.; Roegner, G. C.; Thom, Ronald M.; Vavrinec, John; Whiting, Allan H.

2007-12-06

76

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

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Full Text Available Intensive measurements of salt intrusion in the Sumjin River estuary were taken at high and low waters during both spring and neap tides in each season from August 2004 to April 2007. The estuary demonstrated partially- and well-mixed characteristics during the spring tide and stratified condition during the neap tide. The salt intrusion at high water varied from about 13.39 km in summer 2005 to 25.62 km in autumn 2006. The salt intrusion depended primarily on the freshwater discharges rather than those of spring-neap tidal oscillations. Analysis of three years of observed salinity data indicated that the salt intrusion length scale in the Sumjin River estuary was proportional to the river discharge to the ?1/5 power. Five empirical models were applied to the Sumjin River estuary to explore the most suitable as an easy-to-use tool for prediction of the salt intrusion length as functions of the geometry, river discharge and tide. Comparative results showed that the Nguyen and Savenije (2006 model developed under both partially- and well-mixed estuaries yielded the most satisfactory results of all the models studied for computing the salt intrusion length in the Sumjin River estuary. Our study suggests that the model can generate reasonable results for stratified conditions also.

D. C. Shaha

2009-03-01

77

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

78

Coastal upwelling supplies oxygen-depleted water to the Columbia River estuary.  

Science.gov (United States)

Low dissolved oxygen (DO) is a common feature of many estuarine and shallow-water environments, and is often attributed to anthropogenic nutrient enrichment from terrestrial-fluvial pathways. However, recent events in the U.S. Pacific Northwest have highlighted that wind-forced upwelling can cause naturally occurring low DO water to move onto the continental shelf, leading to mortalities of benthic fish and invertebrates. Coastal estuaries in the Pacific Northwest are strongly linked to ocean forcings, and here we report observations on the spatial and temporal patterns of oxygen concentration in the Columbia River estuary. Hydrographic measurements were made from transect (spatial survey) or anchor station (temporal survey) deployments over a variety of wind stresses and tidal states during the upwelling seasons of 2006 through 2008. During this period, biologically stressful levels of dissolved oxygen were observed to enter the Columbia River estuary from oceanic sources, with minimum values close to the hypoxic threshold of 2.0 mg L(-1). Riverine water was consistently normoxic. Upwelling wind stress controlled the timing and magnitude of low DO events, while tidal-modulated estuarine circulation patterns influenced the spatial extent and duration of exposure to low DO water. Strong upwelling during neap tides produced the largest impact on the estuary. The observed oxygen concentrations likely had deleterious behavioral and physiological consequences for migrating juvenile salmon and benthic crabs. Based on a wind-forced supply mechanism, low DO events are probably common to the Columbia River and other regional estuaries and if conditions on the shelf deteriorate further, as observations and models predict, Pacific Northwest estuarine habitats could experience a decrease in environmental quality. PMID:21533083

Roegner, G Curtis; Needoba, Joseph A; Baptista, António M

2011-01-01

79

Inventories and sorption-desorption trends of radiocesium and radiocobalt in James River estuary sediments  

International Nuclear Information System (INIS)

Anthropogenic radionuclides (Cs137, Cs134, Co60) have been introduced to the James River estuary as a result of low-level releases from the Surry Reactor site since 1973 and worldwide atmospheric fallout from nuclear weapons tests since the early 1950s. The total radionuclide burden in the estuary sediments has been estimated by integrating radionuclide activities in 29 box cores and extrapolating these integrated values over surface areas subdivided on the basis of sediment type, rate of accumulation, and proximity to the reactor release site. The results indicate that 30% of the Co60, but only 15% of the Cs134 released from the reactor site, has been retained in the estuary sediments, and about 40% of the Cs134 and Co60 sediment inventory is in areas that represent less than 5% of the total estuarine surface area. Depletion of the Cs134 in downstream sediments forms a noticeable trend in the James River estuary, and it is postulated that seawater cation competition and exchange is primarily responsible. 26 references, 1 figure, 4 tables

80

Nitrification and inorganic nitrogen distribution in a large perturbed river/estuarine system: the Pearl River Estuary, China  

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Full Text Available We investigated the spatial distribution and seasonal variation of dissolved inorganic nitrogen in a large perturbed estuary, the Pearl River Estuary, based on three cruises conducted in winter (January 2005, summer (August 2005 and spring (March 2006. On-site incubation was also carried out for determining ammonium and nitrite oxidation rates (nitrification rates. We observed a year-round pattern of dramatic decrease in NH4+, increase in NO3? but insignificant change in NO2? in the upper estuary at salinity ~0–5. However, species and concentrations of inorganic nitrogen at estuary significantly changed with season. In winter with low runoff the most upper reach of the Pearl River Estuary showed relatively low rates of ammonia oxidation (0–5.4 ?mol N L?1 d?1 and nitrite oxidation (0–5.2 ?mol N L?1 d?1, accompanied by extremely high concentrations of ammonia (up to >800 ?mol L?1 and nitrate (up to >300 ?mol L?1. In summer, the upper estuary showed higher nitrification rates (ammonia oxidation rate ~1.5–33.1 ?mol N L?1 d?1, nitrite oxidation rate ~0.6–32.0 ?mol N L?1 d?1 with lower concentrations of ammonia (<350 ?mol L?1 and nitrate (<120 ?mol L?1. The Most Probable Number test showed relatively lower nitrifier abundance in summer at most sampling stations, indicating a greater specific nitrification rate per cell in the warm season. Temperatures appeared to control nitrification rates to a large degree in different seasons. In addition to aerobic respiration, nitrification contributed significantly to the consumption of dissolved oxygen (DO and production of CO2 at the upper estuary. Nitrification-induced DO consumption accounted for approximately up to one third of the total water column community DO consumption in the upper estuary during surveyed periods, boosting environmental stress on this large estuarine ecosystem.

Minhan Dai

2008-04-01

81

The partitioning of Triclosan between aqueous and particulate bound phases in the Hudson River Estuary  

International Nuclear Information System (INIS)

The distribution of Triclosan within the Hudson River Estuary can be explained by a balance among the overall effluent inputs from municipal sewage treatment facilities, dilution of Triclosan concentrations in the water column with freshwater and seawater inputs, removal of Triclosan from the water column by adsorption to particles, and loss to photodegradation. This study shows that an average water column concentration of 3 ± 2 ng/l (in the lower Hudson River Estuary) is consistent with an estimate for dilution of average wastewater concentrations with seawater and calculated rates of adsorption of Triclosan to particles. An average Triclosan sediment concentration of 26 ± 11 ng/g would be in equilibrium with the overlying water column if Triclosan has a particle-to-water partitioning coefficient of kd ? 104, consistent with laboratory estimates.

82

Radionuclide tracers for the fate of metals in the Savannah estuary: River-ocean exchange processes  

International Nuclear Information System (INIS)

Plutonium-238 from the US Department of Energy's Savannah River Plant labels riverborne particles, providing a unique opportunity for examining the fate of metals in estuaries and for tracing river-ocean exchange processes. Results indicate that plutonium and lead-210 are enriched on estuarine particles and that inputs of plutonium from oceanic sources greatly exceed inputs from riverborne or drainage-basin sources as far upstream as the landward limit of seawater penetration. We suggest that these radionuclides (and other chemically reactive metals) are being scavenged from oceanic water by sorption onto particles in turbid estuarine and coastal areas. Since estuaries, bays, mangroves, and intertidal areas serve as effective traps for fine particles and associated trace substances, these results have important implications concerning the disposal of chemically reactive substances in oceanic waters. 13 refs., 1 fig., 1 tab

83

Spatial Distribution of Lead and Copper in the Bottom Sediments of Pahang River Estuary, Pahang, Malaysia  

International Nuclear Information System (INIS)

Bottom sediment samples from 30 stations of Pahang River estuary collected in April 2008 were analyzed for the concentration of Pb and Cu using the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The average concentrations of Pb and Cu were 74.31 ± 22.97 ?g/ g dry weights and 18.65± 7.65 ?g/ g dry weights, respectively. In this study, the concentrations were significantly higher near the mouth river and declined as the sampling points were further away from the estuary. Generally, the concentrations of heavy metals were relatively low when compare with other studies in Malaysia. However, the calculated enrichment factors (EF) obtained for Pb, has a slightly higher value, and was probably influenced by anthropogenic input. The concentration for both metals increased with the decrease of mean size, suggesting their association with the fine fraction of the sediments. (author)

84

Nitrate sources and dynamics in a salinized river and estuary - a ?15N-NO3- and ?18O-NO3- isotope approach  

Science.gov (United States)

To trace NO3- sources and assess NO3- dynamics in salinized rivers and estuaries, three rivers (Haihe River: HH River, Chaobaixin River: CB River and Jiyun River: JY River) and two estuaries (HH Estuary and CJ Estuary) along the Bohai Bay (China) have been selected to determine dissolved inorganic nitrogen (DIN: NH4+, NO2- and NO3-. Upstream of the HH River, NO3- was removed 30.9 ± 22.1% by denitrification, resulting from effects of the floodgate: limiting water exchange with downstream and prolonging water residence time to remove NO3-. Downstream of the HH River NO3- was removed 2.5 ± 13.3% by NO3- turnover processes. Conversely, NO3- was increased 36.6 ± 25.2% by external N source addition in the CB River and 34.6 ± 35.1% by in-stream nitrification in the JY River. The HH and CY Estuaries behaved mostly conservatively excluding the sewage input in the CJ Estuary. Hydrodynamics in estuaries has been changed by the ongoing reclamation projects, aggravating the loss of the attenuation function of NO3- in the estuary.

Xue, D.; Boeckx, P.; Wang, Z.

2014-10-01

85

Nitrogen and greenhouse gas dynamics in rivers and estuaries of the Bothnian Bay (Northern Baltic Sea)  

Energy Technology Data Exchange (ETDEWEB)

Denitrification (microbial reduction of nitrate to molecular nitrogen and nitrous oxide) can diminish the anthropogenic nitrogen (N) load in aquatic ecosystems. This thesis focuses on denitrification rates and associated nitrous oxide (N{sub 2}O) effluxes in boreal rivers discharging into the Bothnian Bay, in the northern Baltic Sea. The capacity of river sediment denitrification to diminish N loading to the Baltic Sea and the contribution of N{sub 2}O to the gaseous end-products of denitrification were evaluated. Additionally, emissions of the greenhouse gases carbon dioxide (CO{sub 2}), methane (CH{sub 4}) and N{sub 2}O were measured from a boreal eutrophic river-estuary-bay continuum. Production of N{sub 2} and N{sub 2}O in denitrification and the environmental factors regulating the process were studied with undisturbed sediments in a continuous water flow laboratory microcosm, which allowed control of the temperature, oxygen status and nutrient load of the sediments. Greenhouse gas emissions in the Temmesjoki River and its estuary were also studied in situ. The results showed that denitrification rates in high latitude river sediments were low (330-905 mumol N m-2 d-1) and denitrification had minor importance in reducing NO{sub 3} - loading in the river water. At the nitrate concentrations currently prevailing in the Temmesjoki River (10 muM) no more than 8 % of the added nitrate was removed via denitrification. However, increased NO{sub 3} - loading and temperature, and decreased near-bottom oxygen concentrations, would increase the denitrification rates. The N{sub 2}O production in sediments also increased with increased NO{sub 3} - load, but decreased with increasing temperature. As the NO{sub 3}- concentration in high latitude rivers is highest in winter when the temperature is low, the N{sub 2}O/N{sub 2} ratio in denitrification is highest in winter. However, as the N{sub 2}O/N{sub 2} ratio in denitrification in high latitude rivers always remains low (< 4%), denitrification in river sediments does not substantially increase N{sub 2}O effluxes to the atmosphere. The Temmesjoki River was a source of greenhouse gases to the atmosphere, CO{sub 2} (70-14,300 mg CO{sub 2}-C m-2 d-1) and CH{sub 4} (3.2-120 mg CH{sub 4}-C m-2 d-1) emissions being in the range reported for boreal and temperate rivers, whereas the N{sub 2}O (180-650 mug N{sub 2}O-N m-2 d-1) emissions were lower than emissions from highly N loaded rivers but similar to emissions from pristine temperate rivers. The Temmesjoki River estuary at Liminganlahti Bay was a minor source of or sink for atmospheric greenhouse gases. Greenhouse gases emitted from the Temmesjoki River were mainly leached from the catchment. The upstream sites, surrounded by forests and peatlands, exhibited the highest CO{sub 2} and CH{sub 4} emissions, whereas the N{sub 2}O emissions increased towards the estuary concurrently with the appearance of agricultural fields in the downstream areas of the catchment. This shows that the greenhouse gas emissions from boreal rivers can be attributed to the land use and associated greenhouse gas production in the catchments. The greenhouse gas emissions from boreal rivers showed substantial seasonal variation. The wintertime emissions from unfrozen parts of the river were shown to be important in the annual greenhouse gas budget of the river. (orig.)

Silvennoinen, H.

2008-07-01

86

Effects of river discharge and tidal asymmetry on residual sediment transport and long-term morphodynamics in the river estuary  

Science.gov (United States)

The morphodynamics are of ubiquitous importance to the estuarine function with respect to navigation and ecology. This study examines the hydrodynamics, residual sediment transport processes and long-term morphodynamics in the river estuary forced by river discharge and marine tides. We systematically investigated the generation of tidal asymmetry and its modulation by varying river discharges, the interactions between the river discharge and the tides, and the induced residual sediment transport and associated morphodynamic adjustment and then the feedback mechanisms by deploying the Delft3D model in 1D mode. The model shows that the internally generated tidal asymmetry behaves nonlinearly with increasing river discharge. The internal tidal asymmetry is flood dominated in the absence of river discharge and tidal flat. Introduction of a river discharge promotes the overtide generation which reinforces the tidal asymmetry. An increasing river discharge dissipates the tidal energy and damps the tides that the overtide generation is confined in the downstream. A river discharge threshed can be figured out at which the energy transformation from the principle tide (M2) to the overtide (M4) reaches maximum. The tidal averaged residual sediment transport is decomposed into components according to a bed load transport mode. The tidal asymmetry induces a residual sediment transport whose direction is determined by the nature of the tidal asymmetry. The river discharge induces a net seaward residual transport due to enhanced seaward residual current. Moreover, the interaction between the river discharge and tides generates a river-induced asymmetry. The river-induced asymmetry enhances the seaward residual sediment transport to a large degree that it plays a significant role in flushing sediment seaward. The estuarine morphodynamics reach a (quasi-) equilibrium in a time scale of millennia. The morphodynamic equilibrium is characterized by a reducing longitudinal residual sediment transport gradient. The longitudinal residual sediment transport pattern governs the shape of the final equilibrium bed profiles which can be regionally convex or concave. A flood tidal dominance leads to sediment import. An increasing river discharge deepens the equilibrium bed profile by reinforcing the seaward residual sediment transport. Further increasing discharge rise the bed profile owing to excessive supplied sediment. The estuarine basin may be filled and it eventually evolves toward a delta in long term. This study indicates that the river discharge, the modified tidal asymmetry and the interaction between the river discharge and the tides are the driving mechanisms governing the residual sediment transport and the long-term morphodynamics in the river estuaries.

Guo, L.; Van der Wegen, M.; Roelvink, J.; He, Q.

2013-12-01

87

Hydrochemical characteristics and metallic quality in fish in the Loukkos river estuary of Morocco  

OpenAIRE

The region of Larache endures a big problem of pollution of the surface waters. This pollution takes various origins, domestic, agricultural and industrial. The study of the physicochemical characteristics (Water temperature, pH, Salinity, DO, Conductivity, SM, TOC, NO3, COD and BOD) of the effluents exits of the industrial units of the Loukkos river estuary shows, that these units are responsible of important organic discharges and heavy metals. Indeed, the wastewaters used to drain rice fie...

El Morhit, M.; Fekhaoui, M.; El Morhit, A.; Elie, P.; Yahyaoui, A.

2013-01-01

88

Morphodynamic processes of the Elbe River estuary, Germany: the Coriolis effect, tidal asymmetry and human dredging  

Science.gov (United States)

The Digital Elevation Model (DEM) based on the historical sea-charts and on-site hydrological records were used to examine the morphological change of the Elbe River estuary. The results show that siltation predominated in the tidal flat in the northern estuary, with a net siltation rate of 1.8 cm·a-1 during 1927-2006. In contrast, a continuous erosion prevailed in the main river channel, south of the estuary, with a net erosion rate of 2.5 cm·a-1 in the same time. In addition, a seaward shift of the estuarine island has happened with the old island coalescing to the northern tidal flat and new one emerging through siltation process. The tidal asymmetry via ebbing flow (maximum at 140 cm·s-1, and average at 76 cm·s-1) prevailed in the tidal flat, meaning continuous aggradation northwestward, while flooding flow (maximum at 100 cm ·s-1, and average at 67 cm·s-1) dominated in the main river channel with deepening thaweg at south, showing a landward sedimentation via the tidal pumping processes. This dextral extension of the estuarine morphology is due to the Coriolis force, leading to the inconsistent directions of in-out flows, which enables to facilitate the estuarine siltation. Human dredging prevailing in the estuary has dramatically altered the nature of the silted river channel to erosional since the last century. This is characterized by a net erosion rate of 3.2 cm·a-1 derived from the DEMs mapping, but only partially accounting for the dredging amount of 1994-2006, when the total dredging volume was 67 × 106 m3, equal to 5.9 cm·a-1.

Li, Maotian; Ge, Jianzhong; Kappenberg, Jens; Much, Dagmar; Nino, Ohle; Chen, Zhongyuan

2014-06-01

89

Resuspension and estuarine nutrient cycling: insights from the Neuse River Estuary  

OpenAIRE

For at least the past several decades, North Carolina's Neuse River Estuary (NRE) has been subject to water quality problems relating to increased eutrophication. Research studies initiated in the past several years have addressed the complex nutrient cycles in this system. Most of this research, however, is concerned with the nutrient processes of the water column and the passive diffusion processes of the benthic sedimentary environment. Resuspension of bottom sediments, by bioturbation, ti...

Corbett, D. R.

2010-01-01

90

Nitrogen Source Apportionment for the Catchment, Estuary, and Adjacent Coastal Waters of the River Scheldt  

OpenAIRE

Using the systems approach framework (SAF), a coupled model suite was developed for simulating land-use decision making in response to nutrient abatement costs and water and nutrient fluxes in the hydrological network of the Scheldt River, and nutrient fluxes in the estuary and adjacent coastal sea. The purpose was to assess the efficiency of different long-term water quality improvement measures in current and future climate and societal settings, targeting nitrogen (N) load reduction. The s...

Joachim Maes; Hans Van der Kwast; Jean Luc De Kok; Fritz Hellmann; Bert Van Eck; Guy Engelen; Steven Broekx; Vermaat, Jan E.; Wim Salomons; Willem Van Deursen

2012-01-01

91

Multi-Scale Action Effectiveness Research in the Lower Columbia River and Estuary, 2012  

Energy Technology Data Exchange (ETDEWEB)

The study reported herein was conducted for the U.S. Army Corps of Engineers, Portland District (USACE) by researchers at the Pacific Northwest National Laboratory (PNNL), Oregon Department of Fish and Wildlife (ODFW), National Marine Fisheries Service (NMFS), University of Washington (UW), and U.S. Fish and Wildlife Service (USFWS). The goal of the study was to evaluate the ecological benefits of restoration actions for juvenile salmon in the lower Columbia River and estuary (LCRE; rkm 0–234).

Johnson, Gary E.; Sather, Nichole K.; Storch, Adam; Johnson, Jeff; Skalski, J. R.; Teel, D. J.; Brewer, Taylor; Bryson, Amanda J.; Dawley, Earl M.; Kuligowski, D. R.; Whitesel, T.; Mallette, Christine

2013-11-30

92

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

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Full Text Available Performance of empirical models has been compared with extensively observed data to determine the most suitable model for prediction of salt intrusion in the Sumjin River estuary, Korea. Intensive measurements of salt intrusion were taken at high and low waters during both spring and neap tide in each season from August 2004 to April 2007. The stratification parameter varied with the distance along the estuary, tidal period and freshwater discharge, indicating that the Sumjin River estuary experiences a transition from partially- or well-mixed during spring tide to stratified during neap tide. The salt intrusion length at high water varied from 13.4 km in summer 2005 to 25.6 km in autumn 2006. The salt intrusion mostly depends on the freshwater discharge rather than spring-neap tidal oscillation. Analysis of three years observed salinity data indicates that the scale of the salt intrusion length in the Sumjin River estuary is proportional to the river discharge to the ?1/5 power. Four empirical models have been applied to the Sumjin River estuary to explore the most suitable model for prediction of the salt intrusion length. Comparative results show that the Nguyen and Savenije (2006 model, developed under both partially- and well-mixed estuaries, performs best of all models studied (relative error of 4.6%. The model was also applied under stratified neap tide conditions, with a relative error of 5.2%, implying applicability of this model under stratified conditions as well.

D. C. Shaha

2009-06-01

93

Metal surveys in South African estuaries I. Swartkops River  

International Nuclear Information System (INIS)

Water, surface sediment and sediment core samples were collected from sites in the Swartkops River up to 15 km from the mouth and analysed for up to sixteen elements. The results indicate the presence of four main areas of contamination in the river, at Redhouse, Swartkops, the brickworks and Amsterdam Hoek. The accumulation of zinc, copper, lead and nickel by oysters grown at the mouth of the river confirms the presence of greater than normal metal concentrations in the river. Fish-water Flats outfall contributes metals to the nearshore marine environment, but the strong tidal sweep disperses the effluent relatively quickly so that metal build-up in the area is minimal. In general, metal levels in the Swartkops River are low and, as yet, the area cannot be described as 'polluted' in the true sense of the word

94

Lower Columbia River and Estuary Habitat Monitoring Study, 2011 - Final Report  

Energy Technology Data Exchange (ETDEWEB)

The Ecosystem Monitoring Program is a collaborative effort between the Lower Columbia River Estuary Partnership (LCREP), University of Washington, Wetland Ecosystem Team (UW), US Geological Survey, Water Science Center (USGS), National Oceanic and Atmospheric Administration, National Marine Fisheries Service (NOAA-Fisheries, hereafter NOAA), and Pacific Northwest National Laboratory, Marine Sciences Laboratory (PNNL). The goal of the program is to conduct emergent wetland monitoring aimed at characterizing salmonid habitats in the lower Columbia River and estuary (LCRE) from the mouth of the estuary to Bonneville Dam (Figure 1). This is an ecosystem based monitoring program focused on evaluating status and trends in habitat and reducing uncertainties regarding these ecosystems to ultimately improve the survival of juvenile salmonids through the LCRE. This project comprehensively assesses habitat, fish, food web, and abiotic conditions in the lower river, focusing on shallow water and vegetated habitats used by juvenile salmonids for feeding, rearing and refugia. The information is intended to be used to guide management actions associated with species recovery, particularly that of threatened and endangered salmonids. PNNL’s role in this multi-year study is to monitor the habitat structure (e.g., vegetation, topography, channel morphology, and sediment type) as well as hydrologic patterns.

Borde, Amy B.; Kaufmann, Ronald M.; Cullinan, Valerie I.; Zimmerman, Shon A.; Thom, Ronald M.; Wright, Cynthia L.

2012-03-22

95

Seasonal air-water exchange fluxes of polychlorinated biphenyls in the Hudson River Estuary  

International Nuclear Information System (INIS)

Polychlorinated biphenyls (PCBs) were measured in the air and water over the Hudson River Estuary during six intensive field campaigns from December 1999 to April 2001. Over-water gas-phase ?PCB concentrations averaged 1100 pg/m3 and varied with temperature. Dissolved-phase ?PCB concentrations averaged 1100 pg/L and displayed no seasonal trend. Uncertainty analysis of the results suggests that PCBs with 5 or fewer chlorines exhibited net volatilization. The direction of net air/water exchange could not be determined for PCBs with 6 or more chlorines. Instantaneous net fluxes of ?PCBs ranged from +0.2 to +630 ng m-2 d-1. Annual fluxes of ?PCBs were predicted from modeled gas-phase concentrations, measured dissolved-phase concentrations, daily surface water temperatures and wind speeds. The net volatilization flux was +62 ?g m-2 yr-1, corresponding to an annual loss of +28 kg/yr of ?PCBs from the Hudson River Estuary for the year of 2000. - Investigation of the air-water exchange of PCBs in the Hudson River Estuary suggests that PCBs with 5 or fewer chlorines undergo net volatilization

96

Distribution and abundance of American eels in the White Oak River estuary, North Carolina  

Science.gov (United States)

Apparent widespread declines in abundance of Anguilla rostrata (American eel) have reinforced the need for information regarding its life history and status. We used commercial eel pots and crab (peeler) pots to examine the distribution, condition, and abundance of American eels within the White Oak River estuary, NC, during summers of 2002-2003. Catch of American eels per overnight set was 0.35 (SE = 0.045) in 2002 and 0.49 (SE = 0.044) in 2003. There was not a significant linear relationship between catch per set and depth in 2002 (P = 0.31, depth range 0.9-3.4 m) or 2003 (P = 0.18, depth range 0.6-3.4 m). American eels from the White Oak River were in good condition, based on the slope of a length-weight relationship (3.41) compared to the median slope (3.15) from other systems. Estimates of population density from grid sampling in 2003 (300 mm and larger: 4.0-13.8 per ha) were similar to estimates for the Hudson River estuary, but substantially less than estimates from other (smaller) systems including tidal creeks within estuaries. Density estimates from coastal waters can be used with harvest records to examine whether overfishing has contributed to the recent apparent declines in American eel abundance.

Hightower, J.E.; Nesnow, C.

2006-01-01

97

Migratory Behavior and Survival of Juvenile Salmonids in the Lower Columbia River and Estuary in 2009  

Energy Technology Data Exchange (ETDEWEB)

The study reported herein was funded as part of the Anadromous Fish Evaluation Program, which is managed by the U.S. Army Corps of Engineers (USACE). The Anadromous Fish Evaluation Program study code is EST P 02 01: A Study of Salmonid Survival and Behavior through the Columbia River Estuary Using Acoustic Tags. The study was conducted by the Pacific Northwest National Laboratory (PNNL) and National Oceanic and Atmospheric Administration (NOAA) Fisheries for the USACE Portland District. Estimated survival of acoustic-tagged juvenile Chinook salmon and steelhead through the lower Columbia River and estuary in 2009 was lowest in the final 50 km of the estuary. Probability of survival was relatively high (>0.90) for yearling and subyearling Chinook salmon from the Bonneville Dam forebay (rkm 236) to Three-tree Point (rkm 49.6). Survival of juvenile Chinook salmon declined sharply through the lower 50 km of the estuary. Acoustic-tagged steelhead smolts did not survive as well as juvenile Chinook salmon between Bonneville Dam and the mouth of the Columbia River. Steelhead survival began to decline farther upstream (at rkm 86) relative to that of the Chinook salmon stocks. Subyearling Chinook salmon survival decreased markedly as the season progressed. It remains to be determined whether later migrating subyearling Chinook salmon are suffering increasing mortality as the season progresses or whether some portion of the apparent loss is due to fish extending their freshwater residence. This study provided the first glimpse into what promises to be a very informative way to learn more about how juvenile salmonid passage experiences through the FCRPS may influence their subsequent survival after passing Bonneville Dam. New information regarding the influence of migration pathway through the lower 50 km of the Columbia River estuary on probability of survival of juvenile salmonids, combined with increased understanding regarding the foraging distances and time periods of avian predators should prove useful in developing or assessing management actions to reduce losses of juvenile salmonid smolts that attempt to pass through the estuary on their seaward migration.

McMichael, Geoffrey A.; Harnish, Ryan A.; Bellgraph, Brian J.; Carter, Jessica A.; Ham, Kenneth D.; Titzler, P. Scott; Hughes, Michael S.

2010-08-01

98

A dynamic water-quality modeling framework for the Neuse River estuary, North Carolina  

Science.gov (United States)

As a result of fish kills in the Neuse River estuary in 1995, nutrient reduction strategies were developed for point and nonpoint sources in the basin. However, because of the interannual variability in the natural system and the resulting complex hydrologic-nutrient inter- actions, it is difficult to detect through a short-term observational program the effects of management activities on Neuse River estuary water quality and aquatic health. A properly constructed water-quality model can be used to evaluate some of the potential effects of manage- ment actions on estuarine water quality. Such a model can be used to predict estuarine response to present and proposed nutrient strategies under the same set of meteorological and hydrologic conditions, thus removing the vagaries of weather and streamflow from the analysis. A two-dimensional, laterally averaged hydrodynamic and water-quality modeling framework was developed for the Neuse River estuary by using previously collected data. Development of the modeling framework consisted of (1) computational grid development, (2) assembly of data for model boundary conditions and model testing, (3) selection of initial values of model parameters, and (4) limited model testing. The model domain extends from Streets Ferry to Oriental, N.C., includes seven lateral embayments that have continual exchange with the main- stem of the estuary, three point-source discharges, and three tributary streams. Thirty-five computational segments represent the mainstem of the estuary, and the entire framework contains a total of 60 computa- tional segments. Each computational cell is 0.5 meter thick; segment lengths range from 500 meters to 7,125 meters. Data that were used to develop the modeling framework were collected during March through October 1991 and represent the most comprehensive data set available prior to 1997. Most of the data were collected by the North Carolina Division of Water Quality, the University of North Carolina Institute of Marine Sciences, and the U.S. Geological Survey. Limitations in the modeling framework were clearly identified. These limitations formed the basis for a set of suggestions to refine the Neuse River estuary water-quality model.

Bales, Jerad D.; Robbins, Jeanne C.

1999-01-01

99

Restoration of Hydrodynamic and Hydrologic Processes in the Chinook River Estuary, Washington ? Feasibility Assessment  

International Nuclear Information System (INIS)

A hydrodynamic and hydrologic modeling analysis was conducted to evaluate the feasibility of restoring natural estuarine functions and tidal marine wetlands habitat in the Chinook River estuary, located near the mouth of the Columbia River in Washington. The reduction in salmonid populations is attributable primarily to the construction of a Highway 101 overpass across the mouth of the Chinook River in the early 1920s with a tide gate under the overpass. This construction, which was designed to eliminate tidal action in the estuary, has impeded the upstream passage of salmonids. The goal of the Chinook River Restoration Project is to restore tidal functions through the estuary, by removing the tide gate at the mouth of the river, filling drainage ditches, restoring tidal swales, and reforesting riparian areas. The hydrologic model (HEC-HMS) was used to compute Chinook River and tributary inflows for use as input to the hydrodynamic model at the project area boundary. The hydrodynamic model (RMA-10) was used to generate information on water levels, velocities, salinity, and inundation during both normal tides and 100-year storm conditions under existing conditions and under the restoration alternatives. The RMA-10 model was extended well upstream of the normal tidal flats into the watershed domain to correctly simulate flooding and drainage with tidal effects included, using the wetting and drying schemes. The major conclusion of the hydrologic and hydrodynamic modelinof the hydrologic and hydrodynamic modeling study was that restoration of the tidal functions in the Chinook River estuary would be feasible through opening or removal of the tide gate. Implementation of the preferred alternative (removal of the tide gate, restoration of the channel under Hwy 101 to a 200-foot width, and construction of an internal levee inside the project area) would provide the required restorations benefits (inundation, habitat, velocities, and salinity penetration, etc.) and meet flood protection requirements. The alternative design included design of storage such that relatively little difference in the drainage or inundation upstream of Chinook River Valley Road would occur as a result of the proposed restoration activities

100

Restoration of Hydrodynamic and Hydrologic Processes in the Chinook River Estuary, Washington - Feasibility Assessment  

International Nuclear Information System (INIS)

A hydrodynamic and hydrologic modeling analysis was conducted to evaluate the feasibility of restoring natural estuarine functions and tidal marine wetlands habitat in the Chinook River estuary, located near the mouth of the Columbia River in Washington. The reduction in salmonid populations is attributable primarily to the construction of a Highway 101 overpass across the mouth of the Chinook River in the early 1920s with a tide gate under the overpass. This construction, which was designed to eliminate tidal action in the estuary, has impeded the upstream passage of salmonids. The goal of the Chinook River Restoration Project is to restore tidal functions through the estuary, by removing the tide gate at the mouth of the river, filling drainage ditches, restoring tidal swales, and reforesting riparian areas. The hydrologic model (HEC-HMS) was used to compute Chinook River and tributary inflows for use as input to the hydrodynamic model at the project area boundary. The hydrodynamic model (RMA-10) was used to generate information on water levels, velocities, salinity, and inundation during both normal tides and 100-year storm conditions under existing conditions and under the restoration alternatives. The RMA-10 model was extended well upstream of the normal tidal flats into the watershed domain to correctly simulate flooding and drainage with tidal effects included, using the wetting and drying schemes. The major conclusion of the hydrologic and hydrodynamic modelinof the hydrologic and hydrodynamic modeling study was that restoration of the tidal functions in the Chinook River estuary would be feasible through opening or removal of the tide gate. Implementation of the preferred alternative (removal of the tide gate, restoration of the channel under Hwy 101 to a 200-foot width, and construction of an internal levee inside the project area) would provide the required restorations benefits (inundation, habitat, velocities, and salinity penetration, etc.) and meet flood protection requirements. The alternative design included design of storage such that relatively little difference in the drainage or inundation upstream of Chinook River Valley Road would occur as a result of the proposed restoration activities

101

Holocene and modern sediment storage in the subtropical macrotidal Fitzroy River estuary, Southeast Queensland, Australia  

Science.gov (United States)

The Fitzroy River estuary is a macrotidal, tide-dominated estuary located in the dry tropics of central Queensland, and represents the major source of terrestrial sediment to the southern Great Barrier Reef (GBR) lagoon. The estuary currently receives most of its sediment during large episodic floods that are typically associated with cyclones. Mean annual sediment budgets for such systems are difficult to estimate due to the sporadic nature of flood discharge events, which are highly seasonal and vary greatly in magnitude between years. We have estimated the quantity and long-term rate of accumulation of catchment-derived sediment in the estuarine floodplain using the Holocene stratigraphic sequence determined from a series of sediment cores, dated with radiocarbon and optically stimulated luminescence (OSL) methods. Approximately 13,760 million tonnes (Mt) of fluvial sediment has accumulated in the Fitzroy estuary during the past 8000 years, which equates to an average of 1720 kt yr - 1 . Over the past 100 years, sediment accumulation has been focused around mangrove and tidal creek environments, which cover an area of 130 km 2. Cores from the tidal creeks, dated using 137Cs, 210Pb, and OSL, provide sedimentation rates of approximately 15 mm yr - 1 for the past 45-120 years, or sediment mass accumulation of 1700 kt yr - 1 , which includes a component that is reworked into the estuary by tidal currents. Combined with the small amount of sediment that accumulates on the floodplain during floods (˜ 1 mm yr - 1 , 640 kt yr - 1 ), we estimate that approximately 2350 kt yr - 1 of sediment is trapped in the modern lower floodplain and estuary. This estimate of sediment storage suggests that greater than 50% of the modern mean annual sediment discharge of the Fitzroy River, 4162 kt yr - 1 , may be retained in the lower floodplain and estuary. These results provide useful insights into the spatial pattern of sedimentation, long-term rates of accumulation and estimates of sediment trapping in a tropical, macrotidal sedimentary system.

Bostock, Helen C.; Brooke, Brendan P.; Ryan, David A.; Hancock, Gary; Pietsch, Tim; Packett, Robert; Harle, Kate

2007-10-01

102

Continuous resistivity profiling data from the upper Neuse River Estuary, North Carolina, 2004-2005  

Science.gov (United States)

The Neuse River Estuary in North Carolina has suffered impacts of eutrophication in recent years. As part of a larger project to better constrain nutrient budgets in the estuary, field investigations were performed to study occurrence and discharge of fresh and brackish ground water and nutrients beneath the estuary itself (fig. 1). A Continuous Resistivity Profiling (CRP) system (Manheim and others, 2004) was used to map the depth of the freshwater-saltwater interface (FSI) in sub-estuarine groundwater. This study area serves as a typological representation of a submarine groundwater environment characteristic of a shallow estuary in a wide coastal plain that has not experienced glaciation. Similar settings extend from New Jersey to Georgia, and along the Gulf of Mexico in the U.S. This report archives 29 lines of data collected during 2004 and 2005 surveys representing almost 210 km of survey lines. These data are further explained in the Data Processing section of the report and previews available of the processed data are available.

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

2006-01-01

103

Bathymetric controls on sediment transport in the Hudson River estuary: Lateral asymmetry and frontal trapping  

Science.gov (United States)

Analyses of field observations and numerical model results have identified that sediment transport in the Hudson River estuary is laterally segregated between channel and shoals, features frontal trapping at multiple locations along the estuary, and varies significantly over the spring-neap tidal cycle. Lateral gradients in depth, and therefore baroclinic pressure gradient and stratification, control the lateral distribution of sediment transport. Within the saline estuary, sediment fluxes are strongly landward in the channel and seaward on the shoals. At multiple locations, bottom salinity fronts form at bathymetric transitions in width or depth. Sediment convergences near the fronts create local maxima in suspended-sediment concentration and deposition, providing a general mechanism for creation of secondary estuarine turbidity maxima at bathymetric transitions. The lateral bathymetry also affects the spring-neap cycle of sediment suspension and deposition. In regions with broad, shallow shoals, the shoals are erosional and the channel is depositional during neap tides, with the opposite pattern during spring tides. Narrower, deeper shoals are depositional during neaps and erosional during springs. In each case, the lateral transfer is from regions of higher to lower bed stress, and depends on the elevation of the pycnocline relative to the bed. Collectively, the results indicate that lateral and along-channel gradients in bathymetry and thus stratification, bed stress, and sediment flux lead to an unsteady, heterogeneous distribution of sediment transport and trapping along the estuary rather than trapping solely at a turbidity maximum at the limit of the salinity intrusion.

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

2012-01-01

104

Effects of Spartina alterniflora Invasion on Soil Respiration in the Yangtze River Estuary, China  

Science.gov (United States)

Many studies have found that plant invasion can enhance soil organic carbon (SOC) pools, by increasing net primary production (NPP) and/or decreased soil respiration. While most studies have focused on C input, little attention has been paid to plant invasion effects on soil respiration, especially in wetland ecosystems. Our study examined the effects of Spartina alterniflora invasion on soil respiration and C dynamics in the Yangtze River estuary. The estuary was originally occupied by two native plant species: Phragmites australis in the high tide zone and Scirpus mariqueter in the low tide zone. Mean soil respiration rates were 185.8 and 142.3 mg CO2 m?2 h?1 in S. alterniflora and P. australis stands in the high tide zone, and 159.7 and 112.0 mg CO2 m?2 h?1 in S. alterniflora and S. mariqueter stands in the low tide zone, respectively. Aboveground NPP (ANPP), SOC, and microbial biomass were also significantly higher in the S. alterniflora stands than in the two native plant stands. S. alterniflora invasion did not significantly change soil inorganic carbon or pH. Our results indicated that enhanced ANPP by S. alterniflora exceeded invasion-induced C loss through soil respiration. This suggests that S. alterniflora invasion into the Yangtze River estuary could strengthen the net C sink of wetlands in the context of global climate change. PMID:25799512

Bu, Naishun; Qu, Junfeng; Li, Zhaolei; Li, Gang; Zhao, Hua; Zhao, Bin; Li, Bo; Chen, Jiakuan; Fang, Changming

2015-01-01

105

Fouling community of the Loxahatchee River estuary, Florida, 1980-81  

Science.gov (United States)

Monthly growth of the fouling community at eight test panel sites in the Loxahatchee River Estuary was related to salinity and temperature. Growth was lowest in January 1981 (averaging 23 g per m2, dry weight), and increased during spring and early summer with increasing water temperature. Maximum growth occurred during early or midsummer at upstream locations, before river or canal discharge substantially reduced salinity, and in late summer at downstream locations. Growth was greatest at salinities slightly less than that of seawater and decreased at salinities less than about 10???. Growth was suppressed throughout the estuary in August 1981, probably because of the sudden decrease in temperature and salinity, and perhaps the increase in physical scouring, caused by runoff from Tropical Storm Dennis. Large loads of nutrients transported to the estuary from storm runoff, however, may have subsequently stimulated growth, which increased in September 1981 to the maximum for the year (averaging 683 g per m2, dry weight). ?? 1984 Estuarine Research Federation.

McPherson, B.F.; Sonntag, W.H.; Sabanskas, M.

1984-01-01

106

Distributions of picophytoplankton and phytoplankton pigments along a salinity gradient in the Changjiang River Estuary, China  

Science.gov (United States)

We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary. The average numbers of Synechococcus spp. ( Syn) and picoeukaryotes (Euk) were (2.7 ± 5.1) ×103 and (1.1±1.4) ×103 cells mL-1, respectively. Prochlorococcus spp. ( Pro) was only found in the high-salinity brackish water with the concentration of 3.0×103 cells mL-1. Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk. The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean. The response of different picophytoplankton groups to environmental variables was different. Water temperature was more important in its control over Euk than over Syn, while nutrients were more important in their influence over Syn than over Euk. Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient ( i.e., freshwater zone with 0-5 range, fresh and saline water mixing zone with 5-20 range, and high-salinity brackish water zone with 20-32 range), where three different phytoplankton communities were discovered, suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.

Wang, Baoli; Liu, Congqiang; Wang, Fushun; Li, Siliang; Patra, Sivaji

2014-08-01

107

Sediment transport and morphodynamic changes in Ziarat Estuary and Mond River Delta, the Persian Gulf  

Science.gov (United States)

The Mond River, which is considered as one of the Major Iranian rivers discharging in to the Persian Gulf, is bounded within the region from 51°10' to 54°28' E and 27°20' to 29°51' N, flowing in two provinces of Fars and Boushehr. The latest part of the river is completely meandered and the river mouth has been migrating twice during the past 50 years. Total sediment discharge of the river is estimated as 12 million cubic meter per year. Analysis of meandering river phenomenon and river mouth migration as well as evolution of the down-stream sand spits has long been one of the challenges in hydrodynamic discussions. This natural process usually takes place in rivers to provide energy equilibrium and its integration with human desires has posed as a management issue. The sediment discharging to the Persian Gulf plays an essential role in formation of Mond River Delta as well as a set of sand spits formed in downstream of the river mouth. The morpho-dynamic of entire environment of the Mond River - Mond Delta highly affects marine environment in the surrounding area. The present study offers the results of a numerical and field investigation of various features of river-delta interaction on Ziarat Estuary and the Mond Delta area. A numerical model has been utilized to investigate cases of flow and sediment transport behaviour in the coastal Mond area and future migration patterns of the River Mouth is estimated. Sediment sources and relevant contributions in morphodynamic changes of the sand spits are widely investigated through sediment constituent analysis. The results of the numerical model are compared with field observations and comprehensive GIS based analysis of historic shoreline changes from aerial photos and satellite imagery. It is concluded that the model achievements are capable to predict the observed phenomena. Management guidelines and suggestions are deducted and drawn from the calibration and verification of the results with field observations and satellite image analysis.

Razavi Arab, Azadeh; Haghshenas, S. Abbas; Samsami, Farzin

2014-05-01

108

Nitrate sources and dynamics in the salinized rivers and estuaries – a ?15N- and ?18O-NO3– isotope approach  

Directory of Open Access Journals (Sweden)

Full Text Available To trace NO3– sources and assess NO3– dynamics in the salinized rivers and estuaries, three rivers (HH River, CB River and JY River and two estuaries (HH Estuary and CJ Estuary along the Bohai Bay (China have been selected to determine DIN and ?15N and ?18O-NO3–. Upstream of the HH River NO3– was removed 30.9 ± 22.1% by aerobic denitrification, resulting from effects of the floodgate: limiting water exchange with downstream and prolonging water residence time to remove NO3–. Downstream of the HH River NO3– was removed 2.5 ± 13.3% by NO3– turnover processes. Conversely, NO3– was increased 36.6 ± 25.2% by external N source addition in the CB River and 34.6 ± 35.1% by in-stream nitrification in the JY River, respectively. The HH and CY Estuaries behaved mostly conservative excluding the sewage input in the CJ Estuary. Hydrodynamics in estuaries have been changed by the ongoing reclamation projects, aggravating the estuaries losing the attenuation function of NO3–.

D. Xue

2014-03-01

109

Disposal of radioactive wastes into rivers, lakes and estuaries  

International Nuclear Information System (INIS)

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

110

Regime shifts in muddy estuaries: tidal response to river deepening and canalization  

Science.gov (United States)

Johan C. Winterwerp, Zheng Bing Wang A number of tidal rivers in Europe, amongst which the Ems River in Germany/Netherlands, and the Loire River in France are characterized by hyper-concentrated conditions with pronounced layers of fluid mud and suspended sediment concentrations exceeding 30 g/l. From an ecological point of view the sedimentary conditions in these rivers are highly problematic, as oxygen levels and primary production are very low. The present study aims at defining the conditions at which a regime shift in these rivers may occur, yielding a transition from a "normal estuary" with a classical estuarine turbidity maximum governed by estuarine circulation mainly, to hyper-concentrated conditions where sediment dynamics are mainly governed by tidal asymmetry. We hypothesize that these hyper-concentrated conditions are the result of large amplification of the tide and strong flood-dominant conditions, induced by ongoing deepening and embanking of the tidal river. Indeed, today many European rivers, amongst which the Loire and Ems, can be classified as synchronous, with an almost constant tidal amplitude along the main part of the river. Here we present the behavior of tidal asymmetry in response to deepening and embanking based on an analytical solution of the one-dimensional, linearized water movement in a converging channel, with or without intertidal area.

Winterwerp, J. C.; Wang, Z. B.

2012-04-01

111

Mercury in the Mackenzie River delta and estuary: concentrations and fluxes during open-water conditions.  

Science.gov (United States)

Estimates of mercury (Hg) loadings to the Arctic Ocean from circumpolar rivers have not considered biogeochemical changes that occur when river water is temporarily stored in large deltas (delta effect). There are also few data describing Hg changes across the freshwater-saltwater transition zone (FSTZ) of these rivers. We assessed temporal changes in unfiltered total mercury (THg) and methylmercury (MeHg) concentrations during open-water 2004 in the Mackenzie River upstream of the Mackenzie River delta, and in 6 floodplain lakes across an elevation gradient. These data were used to calculate Hg fluxes from the Mackenzie River and to evaluate a delta effect on Hg using an estimate of delta river water storage and a mixing analysis. Mean THg concentrations were highest in river water (9.17+/-5.51 ng/L) and decreased up the lake elevation gradient. Mean MeHg concentrations were highest in lakes periodically connected to the river (0.213+/-0.122 ng/L) and MeHg concentrations in elevated lakes showed a mid-summer peak. Results from the mixing analysis showed that the delta effect may be large enough to affect Hg loadings to the Arctic Ocean. THg concentrations exiting the delta (10.2 ng/L) were 16% lower than those entering (12.1 ng/L), whereas MeHg showed little change. We calculated 2.5-month (open-water) THg and MeHg fluxes from the Mackenzie River of 1208 and 8.4 kg. These fluxes are similar in magnitude to previous annual estimates in the arctic literature suggesting that previously published annual Hg fluxes from the Mackenzie River may be large underestimates. We also assessed changes in Mackenzie River water THg and MeHg concentrations as it crossed the FSTZ during an open-water cruise. THg decreased non-conservatively across the estuary from 3.8-0.6 ng/L, possibly due to mixing and particle settling. MeHg concentrations were variable and near detection. Our results show that the Mackenzie River estuary is a dynamic environment and may have important controls on Hg delivered to the Arctic Ocean. PMID:19215970

Graydon, Jennifer A; Emmerton, Craig A; Lesack, Lance F W; Kelly, Erin N

2009-04-01

112

An assessment of natural radionuclides in water of Langat River estuary, Selangor  

Science.gov (United States)

An estuary is an area that has a free connection with the open sea and it is a dynamic semi-enclosed coastal bodies. Ex-mining, aquaculture and industrial areas in Selangor are the sources of pollutants discharged into the estuary water. Radionuclides are considered as pollutants to the estuary water. Gamma radiations emitted by natural radionuclides through their decaying process may give impact to human. The radiological effect of natural radionuclides which are 226Ra, 228Ra, 40K, 238U and 232Th, were explored by determining the respective activity concentrations in filtered water along the Langat estuary, Selangor. Meanwhile, in- situ water quality parameters such as temperature, dissolve oxygen (DO), salinity, total suspended solid (TSS), pH and turbidity were measured by using YSI portable multi probes meter. The activity concentration of 226Ra, 228Ra and 40K were determined by using gamma-ray spectrometry with high-purity germanium (HPGe) detector. The activity concentrations of 226Ra, 228Ra and 40K in samples are in the range of 0.17 - 0.67 Bq/L, 0.16 - 0.97 Bq/L and 1.22 - 5.57 Bq/L respectively. On the other hand, the concentrations of uranium-238 and thorium-232 were determined by using Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF). The thorium concentrations are between 0.17 ppm to 0.28 ppm and uranium concentrations were 0.25 ppm to 0.31 ppm. The results show activity concentrations of radionuclides are slightly high near the river estuary. The Radium Equivalent, Absorbed Dose Rate, External Hazard Index, and Annual Effective Dose of 226Ra, 228Ra and 40K are also studied.

Hamzah, Zaini; Rosli, Tengku Nurliana Tuan Mohd; Saat, Ahmad; Wood, Ab. Khalik

2014-02-01

113

An assessment of natural radionuclides in water of Langat River estuary, Selangor  

Energy Technology Data Exchange (ETDEWEB)

An estuary is an area that has a free connection with the open sea and it is a dynamic semi-enclosed coastal bodies. Ex-mining, aquaculture and industrial areas in Selangor are the sources of pollutants discharged into the estuary water. Radionuclides are considered as pollutants to the estuary water. Gamma radiations emitted by natural radionuclides through their decaying process may give impact to human. The radiological effect of natural radionuclides which are {sup 226}Ra, {sup 228}Ra, {sup 40}K, {sup 238}U and {sup 232}Th, were explored by determining the respective activity concentrations in filtered water along the Langat estuary, Selangor. Meanwhile, in- situ water quality parameters such as temperature, dissolve oxygen (DO), salinity, total suspended solid (TSS), pH and turbidity were measured by using YSI portable multi probes meter. The activity concentration of {sup 226}Ra, {sup 228}Ra and {sup 40}K were determined by using gamma-ray spectrometry with high-purity germanium (HPGe) detector. The activity concentrations of {sup 226}Ra, {sup 228}Ra and {sup 40}K in samples are in the range of 0.17 - 0.67 Bq/L, 0.16 - 0.97 Bq/L and 1.22 - 5.57 Bq/L respectively. On the other hand, the concentrations of uranium-238 and thorium-232 were determined by using Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF). The thorium concentrations are between 0.17 ppm to 0.28 ppm and uranium concentrations were 0.25 ppm to 0.31 ppm. The results show activity concentrations of radionuclides are slightly high near the river estuary. The Radium Equivalent, Absorbed Dose Rate, External Hazard Index, and Annual Effective Dose of {sup 226}Ra, {sup 228}Ra and {sup 40}K are also studied.

Hamzah, Zaini, E-mail: tengkuliana88@gmail.com; Rosli, Tengku Nurliana Tuan Mohd, E-mail: tengkuliana88@gmail.com; Saat, Ahmad, E-mail: tengkuliana88@gmail.com; Wood, Ab. Khalik, E-mail: tengkuliana88@gmail.com [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

2014-02-12

114

An assessment of natural radionuclides in water of Langat River estuary, Selangor  

International Nuclear Information System (INIS)

An estuary is an area that has a free connection with the open sea and it is a dynamic semi-enclosed coastal bodies. Ex-mining, aquaculture and industrial areas in Selangor are the sources of pollutants discharged into the estuary water. Radionuclides are considered as pollutants to the estuary water. Gamma radiations emitted by natural radionuclides through their decaying process may give impact to human. The radiological effect of natural radionuclides which are 226Ra, 228Ra, 40K, 238U and 232Th, were explored by determining the respective activity concentrations in filtered water along the Langat estuary, Selangor. Meanwhile, in- situ water quality parameters such as temperature, dissolve oxygen (DO), salinity, total suspended solid (TSS), pH and turbidity were measured by using YSI portable multi probes meter. The activity concentration of 226Ra, 228Ra and 40K were determined by using gamma-ray spectrometry with high-purity germanium (HPGe) detector. The activity concentrations of 226Ra, 228Ra and 40K in samples are in the range of 0.17 - 0.67 Bq/L, 0.16 - 0.97 Bq/L and 1.22 - 5.57 Bq/L respectively. On the other hand, the concentrations of uranium-238 and thorium-232 were determined by using Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF). The thorium concentrations are between 0.17 ppm to 0.28 ppm and uranium concentrations were 0.25 ppm to 0.31 ppm. The results show activity concentrations of radionuclides are slightly high near the river estuary. The Radium Equivalent, Absorbed Dose Rate, External Hazard Index, and Annual Effective Dose of 226Ra, 228Ra and 40K are also studied

115

An assessment of natural radionuclides in water of Langat River estuary, Selangor  

International Nuclear Information System (INIS)

Full-text: An estuary is an area that has a free connection with the open sea and it is a dynamic semi-enclosed coastal bodies. Ex-mining, aquaculture and industrial areas in Selangor are the sources of pollutants discharged into the estuary water. Radionuclides are considered as pollutants to the estuary water. Gamma radiations emitted by natural radionuclides through their decaying process may give impact to human. The radiological effect of natural radionuclides which are 226Ra, 228Ra, 40K, 238U and 232Th, were explored by determining the respective activity concentrations in filtered water along the Langat estuary, Selangor. Meanwhile, in- situ water quality parameters such as temperature, dissolve oxygen (DO), salinity, total suspended solid (TSS), pH and turbidity were measured by using YSI portable multi probes meter. The activity concentration of 226Ra, 228Ra and 40K were determined by using gamma-ray spectrometry with high-purity germanium (HPGe) detector. The activity concentrations of 226Ra, 228Ra and 40K in samples are in the range of 0.17 - 0.67 Bq/ L, 0.16 - 0.97 Bq/ L and 1.22 - 5.57 Bq/ L respectively. On the other hand, the concentrations of uranium-238 and thorium-232 were determined by using Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF). The thorium concentrations are between 0.17 ppm to 0.28 ppm and uranium concentrations were 0.25 ppm to 0.31 ppm. The results show activity concentrations of radionuclides are slightly high near the river estuary. The Radium Equivalent, Absorbed Dose Rate, External Hazard Index, and Annual Effective Dose of 226Ra, 228Ra and 40K are also studied. (author)

116

A Comparative Analysis of the Estuary Ecosystems of Russia’s Large Rivers in Terms of Anthropogenic Load  

Directory of Open Access Journals (Sweden)

Full Text Available Based on monitoring hydro-chemical information, amassed for many years (1980–2012, from the State Service for Observations (SSO, the author conducts an assessment of anthropogenic load on the estuary ecosystems of Russia’s large rivers, as well as of their condition by hydro-chemical indicators. The results have helped to rank the estuary ecosystems by anthropogenic load and their condition with a view to identifying the more prosperous ecosystems.

Olga S. Reshetnyak

2014-10-01

117

Evaluation of Genotoxicity of Sediments from the Sado-River Estuary Using Solvent Extractions of Diferent Polarities  

OpenAIRE

Located in the western coast of Portugal, our case study, the river Sado Estuary, is affected by various sources of pollution, such as heavy-industry, urbanism, mining, agriculture and maritime traffic. Recent studies showed that sediment samples were contaminated with a mixture of different groups of contaminants related to the different anthropogenic pressures along the estuary. The present study aims to assess the cytotoxic and genotoxic potential of these sediments following a fractioning...

Vicente, Ana Margarida; Sacadura, Joana; Pinto, Miguel; Louro, Henriqueta; Costa, Pedro Manuel; Lavinha, Joa?o; Caeiro, Sandra; Silva, Maria Joa?o

2013-01-01

118

FLOW PATTERN AND SUSPENDED SEDIMENT TRANSPORT AROUND SPUR DIKES IN THE KIKUCHI RIVER ESTUARY  

Science.gov (United States)

A series of spur dikes was constructed to reinforce an embankment at bends in the lower reach of the Kikuchi River. In recent years, eutrophicated fine sediment accumulation around spur dikes has caused a serious problem in estuary ecosystem. Therefore, Ministry of Land, Infrastructure and Transport has developed the renaturalization project of sand beach in the estuary. In this study, we have particularly investigated flow patterns and fine sediment transport around these spur dikes by using Stream-pro Acoustic Doppler Current Profiler (ADCP) and radio-controlled model boat equipped with Workhorse ADCP in the period of spring tide. The results show that these spur dikes weakened flow and SS transport in the concave, and strengthened them in the convex of the bend. In addition, fine sediment accumulation were discussed through streamwise distribution of SS transport in both cases of flood and ebb tide.

Ohmoto, Terunori; Hirakawa, Ryuichi

119

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

Science.gov (United States)

The contamination of semi-volatile organic compounds (SVOCs) in the surface sediments of the Guan River Estuary, China was fully investigated. Total concentrations of 56 species of SVOCs ranged from 132 to 274 ng/g with an average of 186 ng/g (dry weight). Polycyclic aromatic hydrocarbon (PAH) concentrations were positively correlated with clay content and negatively correlated with sediment grain size. Source identification indicated that PAHs originated mainly from pyrolytic sources. However, intense ship traffic in the estuary may provide sources of petrogenic PAHs. Organochlorine pesticides (OCPs) mainly originated from direct input of dichlorodiphenyltrichloroethanes (DDTs) during some industrial processes. The SVOC concentrations were also compared with International Sediments Quality Guidelines and Sediments Quality Criteria, and the results indicated that negative biological impacts may originate from high concentrations of FLO, p,p'-DDE, and total DDTs. PMID:24554020

He, Xinran; Song, Xiaojuan; Pang, Yong; Li, Yiping; Chen, Binlin; Feng, Zhihua

2014-07-01

120

Association of plutonium with sediments from the Ob and Yenisey Rivers and Estuaries  

International Nuclear Information System (INIS)

The present study applied sequential extraction techniques to investigate the binding and mobility of plutonium (Pu) in sediments from the rivers and estuaries of the Ob and Yenisey. As a study site, the Ob and Yenisey are particularly interesting as both rivers have weapons-grade Pu sources in their catchment areas, including the Russian Pu production and reprocessing plants at Mayak, Tomsk-7 and Krashnoyarsk, and the Semipalantinsk nuclear weapons testing site in Kazakhstan. Plutonium activity and 240Pu/239Pu ratios were determined using accelerator mass spectrometry (AMS). Sequential extractions showed that between 47 and 80% of the Pu in Yenisey River sediments and 35-53% of the Pu in soils around the Techa River are mobilized with weak oxidising agents, which can indicate that Pu is bound to organic material. In contrast, Pu in Ob and Yenisey Estuarine sediments was more strongly bound, with 60-100% being found in the HNO3-extractable fraction. This change in speciation could reflect either that Pu bound to organic material in the Techa and Yenisey River sediments becomes more fixed to the sediments with time, or that organic-bound Pu is mobilized and released to the water when the sediments encounter the more saline water of the Ob and Yenisey estuaries. In general, 240Pu/239Pu ratios were relatively consistent between different extraction fractions, although, in whole sediments, an increase in ratio was obsle sediments, an increase in ratio was observed with distance from the source. This reflects the increased influence of weapon fallout from catchment runoff within the river systems, as compared to the weapons-grade sources close to the production and reprocessing plants. Knowledge of Pu speciation in the Ob and Yenisey Rivers, and the processes controlling its behaviour in estuarine systems, can improve predictions of its transfer and subsequent environmental impact to Arctic Seas

121

Antibiotics in riverine runoff of the Pearl River Delta and Pearl River Estuary, China: Concentrations, mass loading and ecological risks  

International Nuclear Information System (INIS)

Ten antibiotics belonging to three groups (macrolides, fluoroquinolones and sulfonamides) were investigated in riverine runoff of the Pearl River Delta (PRD) and Pearl River Estuary (PRE), South China for assessing the importance of riverine runoff in the transportation of contaminants from terrestrial sources to the open ocean. All antibiotics were detected in the eight outlets with concentrations ranging from 0.7 to 127 ng L?1. The annual mass loadings of antibiotics from the PRD to the PRE and coast were 193 tons with 102 tons from the fluoroquinolone group. It showed that antibiotics decreased from the riverine outlets to the PRE and open ocean. Risk assessment showed that most of these antibiotics showed various ecological risks to the relevant aquatic organisms, in which ofloxacin (OFL), erythromycin (ETM) and ciprofloxacin (CIP) posed high ecological risks to the studied aquatic environments. -- Highlights: •Antibiotics were ubiquitous in the river water and costal water in the Pearl River Delta. •Antibiotics exhibited distinct temporal and spatial trends in the riverine runoff outlets. •Annual outflows of antibiotics were 193 tons from the Pearl River to coastal ocean. •Some antibiotics posed high risks to some organisms in the PRD environments. -- Antibiotics were ubiquitous in the river and coastal water in the Pearl River Delta and posed various ecological risks to the relevant aquatic organisms

122

Importance of budgets for estimating the input of groundwater-derived nutrients to an eutrophic tidal river and estuary  

Science.gov (United States)

Groundwater is often overlooked as a source of nutrients to estuaries and most previous groundwater-surface water exchange studies did not consider the input of dissolved organic nutrients. Here, we hypothesize that groundwater is contributing to high dissolved inorganic and organic nutrient concentrations in an eutrophic subtropical tidal river and estuary (Caboolture River, Queensland, Australia). Several spatial radon (222Rn, a natural groundwater tracer) surveys indicated that the majority of groundwater discharge occurred in the tidal river just upstream of the estuary, and that the radon hotspot did not necessarily coincide with the nutrient hotspot. A radon mass balance revealed that groundwater discharge into the tidal river was equivalent to about 50% of the gauged river flow in February 2012. Groundwater discharge apparently contributed 85% of ammonium and 35% of phosphate entering the estuary. In spite of significant correlations between radon and nitrate and dissolved organic nitrogen (DON) during spatial surveys, groundwater could account for only 7% of nitrate and 9% of DON inputs due to low groundwater concentrations and other sources (i.e., apparently a sewage treatment plant for nitrate and floodplain tributaries for DON). Because total dissolved nitrogen (TDN) was dominated by DON (69%) and nitrate (23%), the groundwater ammonium inputs were a minor source to the TDN pool within the tidal river and estuary. This study demonstrated that correlations between a groundwater tracer and nutrient concentrations do not necessarily illustrate causation. To assess how groundwater drives nutrient dynamics in estuaries, it may be important to include the tidal river (not only the estuarine salinity gradient) in field investigations, consider DON (not only ammonium and nitrate), and perform detailed budgets that include minor tributaries.

Makings, Uriah; Santos, Isaac R.; Maher, Damien T.; Golsby-Smith, Lindsay; Eyre, Bradley D.

2014-04-01

123

Benthic bacterial biomass and production in the Hudson River estuary  

International Nuclear Information System (INIS)

Bacterial biomass, production, and turnover were determined for two freshwater march sites and a site in the main river channel along the tidally influenced Hudson River. The incorporation of [methyl-3H]thymidine into DNA was used to estimate the growth rate of surface and anaerobic bacteria. Bacterial production at marsh sites was similar to, and in some cases considerably higher than, production estimates reported for other aquatic wetland and marine sediment habitats. Production averaged 1.8-2.8 mg C·m-2· hour-1 in marsh sediments. Anaerobic bacteria in marsh sediment incorporated significant amounts of [methyl-3H]thymidine into DNA. Despite differences in dominant vegatation and tidal regime, bacterial biomass was similar (1 x 103 ± 0.08 mg C·m-2) in Trapa, Typha, and Nuphar aquatic macrophyte communities. Bacterial abundance and productivity were lower in sandy sediments associated with Scirpus communities along the Hudson River (0.2 x 103 ± 0.05 mg C·m-2 and 0.3 ± 0.23 mg C · m-2· hour-1, respectively)

124

The morphology and morphodynamics of sand-gravel subaquatic dunes: the Raba River estuary, Poland  

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Full Text Available In the outlet of the Raba River to the Vistula, the biggest river in Poland, the morphology and morphodynamics of sand and fine-gravel subaquatic dunes were investigated. The site is situated in highland region just about the entrance to Polish Carpathians. The dunes formed on the Raba River bed estuary are composed of sand and fine gravel (d50 up to 11 mm. Systematic observation (within the 2000-2005 were made of geometry, sediment composition and hydraulic climate under which the dunes grew and decomposed. The investigation focuses here mostly on the geometrical parameters of these bed forms such as height, length, as well as granulometric characteristics of the sediment. Based on in-site measurements different hydraulic parameters were calculated such as shear stresses, resistant coefficient, Froude and Reynolds numbers and roughness coefficient. It was found that the relation between height (H and length (L of the Raba estuary dunes describes the formula: H = 0.05L0.35. Also these dunes are steeper and flatter then classical H/L index is: H/L = 0.0518L0.622. During the field campaign, when the foot access to the estuary was possible and dunes were spotted on the river bed the range of measured water velocity was from v = 0.39 m?s-1 to v = 0.81 m?s-1 with the highest velocity over the dune crest. At the same time the measured range of shear stresses within the dune field formation were from t = 0.115 N×m-2 to t = 1.59 N×m-2. On the field investigations the CCHE2D - two-dimensional unsteady flow and sediment transport model for non-equilibrium transport of non-uniform sediment mixtures – was applied. The model was used to simulate the morphodynamic changes along the outlet of the Raba River basing on field observations of the 2005 summer flood as well as calculate hydraulics parameters. It was also used to test and confirm the range of morphodynamic changes, which take place along the research reach where the dunes are being developed. The maximum water flow velocity for and the shear stresses for the summer flood caused the hydrodynamic conditions when water velocity as well as shear stresses values reached respectively up to v = 1,93 m×s-1, and t = 19.74 N×m-2 which shows that critical conditions of bed load movement were exceeded for the Raba estuary

Artur RADECKI-PAWLIK

2012-08-01

125

The influence of estuarine conditions on the dynamics of a coastal phytoplankton community in a micro-tidal estuary: Yura River Estuary, Japan  

Science.gov (United States)

The western side of Wakasa Bay, Tango Sea, Japan receives most of its allochthonous nutrient input from the Yura River. The Yura Estuary is classified as micro-tidal with a spring tidal range of less than 0.5 m. In summer, generally, the river discharge is low and the sea level is high, so the salt wedge extends 20 km upstream. Then, phytoplankton blooms occur due to an influx of riverine nutrients in the estuary. In contrast, during spring, river discharge is high and the salt wedge is not formed. These seasonal differences in estuarine physical and biological conditions may affect the coastal zone. The objective of this study is to examine the influence of estuarine conditions on the dynamics of the coastal phytoplankton community in this micro-tidal estuary. For this objective, field surveys were conducted both in the coastal zone and the river side of this estuary. Four sampling stations with depths of 5, 10, 20 and 30 m were set in the coastal zone, and weekly surveys were conducted from December 2009 to June 2011. Six sampling stations were set between the mouth of the Yura River and 16 km upstream, and monthly surveys were conducted in summer (from June 2010 to August 2010) and spring (from February 2011 to April 2011). Vertical profiles of salinity, water temperature and chlorophyll fluorescence were measured with a CTD profiler at each station. With water samples taken from the surface, middle, and bottom layers at each station, concentrations of chlorophyll a, pheophytin, and nutrients were analyzed. The nutrients flux from the upstream to the estuary correlated strongly with river discharge, not with nutrient concentrations. In summer, when estuarine water were stratified, marine phytoplankton (mainly diatoms) developed in the middle layer of the estuary while freshwater phytoplankton (mainly green algae) increased in the surface layer of the river mouth. Nitrate concentration in riverine water was estimated to decline 15% while the water flowed from the 16 km upstream to the river mouth, and this nutrient depression could be caused by phytoplankton growth in the estuary. Due to a combination of low river discharge and high nutrient utilization by phytoplankton, the flux of nutrients to the coastal zone decreased (e.g. nitrate flux was ranged from 0.89 to 6.54 tN/d) and phytoplankton biomass in the coastal zone remained low (chl. a concentration was ranged from 0.19 to 2.14 ?g/L) during summer. In contrast, during spring, river discharge was high and nutrient utilization was low, so the flux of nutrients was relatively high (e.g. nitrate flux was ranged from 4.60 to 17.49 tN/d). As a result, nutrient concentration increased and phytoplankton bloomed in the coastal zone (chl. a concentration was ranged from 0.65 to 8.82 ?g/L). This study reveals the role of increased spring river flow, mainly due to melting snow, on phytoplankton blooms in the coastal community.

Watanabe, K.; Fukuzaki, K.; Akiyama, S.; Ichimi, K.; Kasai, A.; Fukushima, K.; Ueno, M.; Yoshioka, T.; Yamashita, Y.

2011-12-01

126

Temporal and spatial dynamics of amphioxus population (Branchiostoma belcheri tsingtaneuse) and its influential factors in Luan River Estuary, China.  

Science.gov (United States)

Population distribution of amphioxus (Branchiostoma belcheri tsingtauense) was investigated in the Luan River Estuary from 1999 to 2011, to describe its trends and discover the factors that influence its decline. Amphioxus are distributed on the seabed at 5-10 m depth, between the Xinkai Estuary and the Dapu River Estuary, where the primary sand components of the sediment are medium and fine, with particle size ranging from 0.001 to 1 mm. In recent years, the population density and biomass of amphioxus have sharply decreased. Changes in sediment granularity composition may significantly influence amphioxus distribution. Our data showed that the highest density region of amphioxus occurred where >90% of the sediment particles were between 0.063 and 0.5 mm in size. A reduction in sediment discharge from Luan River and the expansion of raft-breeding mariculture may be causing the decline in amphioxus through habitat destruction. PMID:25247060

Hao, Luo; Minghui, Ma; Bin, Liang; Chenguang, Bao

2014-08-01

127

Sediment quality in Rivers and their estuaries of an olive oil production area, Messinia, Greece.  

Science.gov (United States)

Sediment analysis at four major rivers (Pamisos, Aris, Velikas and Nedon) and their estuaries towards heavy metals took place in the Prefecture of Messinia, Greece, during two sampling campaigns in 2008 and 2011. The main industrial activity in the region is the operation of 250 olive oil industries and the main problem concerning pollution derives from the vast quantities of olive mill waste waters that are being generated annually most of which is currently discharged in nearby streams. Chemical parameters such as phenols, total organic carbon and certain heavy metals were found to be strongly correlated with the wastes from the olive oil industries. Major and minor elements (heavy metals) were measured in riverine and estuarine sediments. In parallel heavy metals were determined in the olive waste from a local industry, using atomic absorption spectrometry, in order to correlate the results with the sediment analysis. Major and Minor elements were recorded based upon the total percentage of the sediment samples and in order to eliminate the grain size effect, the concentrations were normalized towards Al. A pollution indice, the sediment enrichment factor, was also calculated, the high values of which towards Cr are of particular interest. Additionally organic carbon and total phenolic compounds were determined in rivers and their estuaries. High concentrations of Chromium were recorded in River Aris sediment, which seems to be the most polluted. Relatively high concentrations of zinc were encountered at rivers Aris and Pamisos while the chromium load seems to be higher near the estuaries of the rivers. The olive mill waste water analysis confirmed the existence of chromium in the waste and extremely elevated values were also found at a nearby station where these wastes tend to accumulate for decades. In contrast the results from the Nedon River indicated that it is not affected, since the low values found remained constant from the source of the river until its outfall in the Messinian Gulf. A significant enrichment in phenolic content of sediments as well in organic carbon was observed in 2011 when compared to 2008, in most of the cases, indicating degradation of the study aquatic ecosystems of Messinia Prefecture.

Anastasopoulou, Evaggelia; Pavlidou, Alexandra; Skoulikidis, Nikos; Dassenakis, Manos; Hatzianestis, Ioannis

2014-05-01

128

Fate of polybrominated diphenyl ethers in the environment of the Pearl River Estuary, South China  

International Nuclear Information System (INIS)

Ninety-six riverine runoff samples collected at eight major outlets in the Pearl River Delta (PRD), South China, during 2005-2006 were analyzed for 17 brominated diphenyl ether (BDE) congeners (defined as ?17PBDE). Fourteen and 15 congeners were detected, respectively, in the dissolved and particulate phases. These data were further used to elucidate the partitioning behavior of BDE congeners in riverine runoff. Several related fate processes, i.e. air-water exchange, dry and wet deposition, degradation, and sedimentation, within the Pearl River Estuary (PRE), were examined to estimate the inputs of ?10PBDE (sum of the target BDE congeners, BDE-28, -47, -66, -85, -99, -100, -138, -153, -154, and -183) and BDE-209 from the PRD to the coastal ocean based on mass balance considerations. The results showed that annual outflows of ?10PBDE and BDE-209 were estimated at 126 and 940 kg/year, respectively from the PRE to coastal ocean. Besides sedimentation and degradation, the majority of ?10PBDE and BDE-209 discharged into the PRE via riverine runoff was transported to the coastal ocean. - Fate of polybrominated diphenyl ethers in the environment the Pearl River Estuary, South China.

129

Fate of polybrominated diphenyl ethers in the environment of the Pearl River Estuary, South China  

Energy Technology Data Exchange (ETDEWEB)

Ninety-six riverine runoff samples collected at eight major outlets in the Pearl River Delta (PRD), South China, during 2005-2006 were analyzed for 17 brominated diphenyl ether (BDE) congeners (defined as SIGMA{sub 17}PBDE). Fourteen and 15 congeners were detected, respectively, in the dissolved and particulate phases. These data were further used to elucidate the partitioning behavior of BDE congeners in riverine runoff. Several related fate processes, i.e. air-water exchange, dry and wet deposition, degradation, and sedimentation, within the Pearl River Estuary (PRE), were examined to estimate the inputs of SIGMA{sub 10}PBDE (sum of the target BDE congeners, BDE-28, -47, -66, -85, -99, -100, -138, -153, -154, and -183) and BDE-209 from the PRD to the coastal ocean based on mass balance considerations. The results showed that annual outflows of SIGMA{sub 10}PBDE and BDE-209 were estimated at 126 and 940 kg/year, respectively from the PRE to coastal ocean. Besides sedimentation and degradation, the majority of SIGMA{sub 10}PBDE and BDE-209 discharged into the PRE via riverine runoff was transported to the coastal ocean. - Fate of polybrominated diphenyl ethers in the environment the Pearl River Estuary, South China.

Guan Yufeng [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School, Chinese Academy of Sciences, Beijing 100049 (China); Sojinu, O.S. Samuel [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Li Shaomeng [Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4 (Canada); Zeng, Eddy Y., E-mail: eddyzeng@gig.ac.c [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

2009-07-15

130

Use of multitracers for the study of water mixing in the Paraiba do Sul River estuary  

International Nuclear Information System (INIS)

Multitracers were used to study water mixing in the Paraiba do Sul River estuary region in August 2007 (dry season) and March 2008 (rainy season) and to evaluate the reach of the river plume in the direction of the open ocean. Two sampling campaigns were carried out, each in a different season. Based on these results, it was possible to conclude that the multitracers used in this study (salinity, Si, Ba and U, as well as the radium isotopes 223Ra, 224Ra, 226Ra and 228Ra) presented satisfactory results toward defining the plume reach and determining the residence time and water-mixing processes in the estuary. A strong correlation was observed between tracers and the distance to the coast. During the low river water discharge period, the riverine water took about 10 days to reach open ocean waters (salinity ? 35). During the rainy period this value decreased to 6 days. Based on the radium results, it was possible to calculate diffusion coefficients (Kh) of 23 km2 d-1 and 38 km2 d-1 for 224Ra and 223Ra, respectively, during the dry season (winter). Values of 65 km2 d-1 and 68 km2 d-1 for 223Ra and 224Ra, respectively, were found for the rainy period (summer).

131

Use of multitracers for the study of water mixing in the Paraiba do Sul River estuary  

Energy Technology Data Exchange (ETDEWEB)

Multitracers were used to study water mixing in the Paraiba do Sul River estuary region in August 2007 (dry season) and March 2008 (rainy season) and to evaluate the reach of the river plume in the direction of the open ocean. Two sampling campaigns were carried out, each in a different season. Based on these results, it was possible to conclude that the multitracers used in this study (salinity, Si, Ba and U, as well as the radium isotopes {sup 223}Ra, {sup 224}Ra, {sup 226}Ra and {sup 228}Ra) presented satisfactory results toward defining the plume reach and determining the residence time and water-mixing processes in the estuary. A strong correlation was observed between tracers and the distance to the coast. During the low river water discharge period, the riverine water took about 10 days to reach open ocean waters (salinity {approx} 35). During the rainy period this value decreased to 6 days. Based on the radium results, it was possible to calculate diffusion coefficients (K{sub h}) of 23 km{sup 2} d{sup -1} and 38 km{sup 2} d{sup -1} for {sup 224}Ra and {sup 223}Ra, respectively, during the dry season (winter). Values of 65 km{sup 2} d{sup -1} and 68 km{sup 2} d{sup -1} for {sup 223}Ra and {sup 224}Ra, respectively, were found for the rainy period (summer).

Souza, Thaisa Abreu, E-mail: abreu.thaisa@gmail.co [Departamento de Quimica, Pontificia Universidade Catolica, 22453-900 Rio de Janeiro, RJ (Brazil); Godoy, Jose Marcus [Departamento de Quimica, Pontificia Universidade Catolica, 22453-900 Rio de Janeiro, RJ (Brazil); Instituto de Radioprotecao e Dosimetria IRD/CNEN, 22780-160 Rio de Janeiro, RJ (Brazil); Godoy, Maria Luiza D.P. [Instituto de Radioprotecao e Dosimetria IRD/CNEN, 22780-160 Rio de Janeiro, RJ (Brazil); Moreira, Isabel [Departamento de Quimica, Pontificia Universidade Catolica, 22453-900 Rio de Janeiro, RJ (Brazil); Carvalho, Zenildo L. [Instituto de Radioprotecao e Dosimetria IRD/CNEN, 22780-160 Rio de Janeiro, RJ (Brazil); Salomao, Marcos Sarmet M.B.; Rezende, Carlos E. [Centro de Biociencias e Biotecnologia, Universidade Estadual do Norte Fluminense, 28013-600 Campos dos Goytacazes, RJ (Brazil)

2010-07-15

132

Heavy metals in coastal wetland sediments of the Pearl River Estuary, China  

International Nuclear Information System (INIS)

Sediment quality in coastal wetlands of the Pearl River Estuary was concerned since the wetlands were used for land reclamation, aquaculture and wildlife protection, and meanwhile served as one of the main ultimate sinks for large amount of heavy metals discharged from the rapidly developing Pearl River Delta. Total concentrations of heavy metal, such as Zn, Ni, Cr, Cu, Pb, and Cd, and their chemical speciation were investigated. Results showed that the sediments were significantly contaminated by Cd, Zn and Ni with concentration ranges of 2.79-4.65, 239.4-345.7 and 24.8-122.1 mg/kg, respectively. A major portion (34.6-46.8%) of Pb, Cd, and Zn was strongly associated with exchangeable fractions, while Cu, Ni and Cr were predominantly associated with organic fractions, residual, and Fe-Mn oxide. Cd and Zn would be the main potential risk and the sediment quality is no longer meeting the demand of the current wetland utilization strategies. - We found that the sediment in coastal wetlands of the Pearl River Estuary was polluted by Cd, Zn and no longer suitable for the current wetland utilization strategies

133

Nitrogen Source Apportionment for the Catchment, Estuary, and Adjacent Coastal Waters of the River Scheldt  

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Full Text Available Using the systems approach framework (SAF, a coupled model suite was developed for simulating land-use decision making in response to nutrient abatement costs and water and nutrient fluxes in the hydrological network of the Scheldt River, and nutrient fluxes in the estuary and adjacent coastal sea. The purpose was to assess the efficiency of different long-term water quality improvement measures in current and future climate and societal settings, targeting nitrogen (N load reduction. The spatial-dynamic model suite consists of two dynamically linked modules: PCRaster is used for the drainage network and is combined with ExtendSim modules for farming decision making and estuarine N dispersal. Model predictions of annual mean flow and total N concentrations compared well with data available for river and estuary (r² ? 0.83. Source apportionment was carried out to societal sectors and administrative regions; both households and agriculture are the major sources of N, with the regions of Flanders and Wallonia contributing most. Load reductions by different measures implemented in the model were comparable (~75% remaining after 30 yr, but costs differed greatly. Increasing domestic sewage connectivity was more effective, at comparatively low cost (47% remaining. The two climate scenarios did not lead to major differences in load compared with the business-as-usual scenario (~88% remaining. Thus, this spatially explicit model of water flow and N fluxes in the Scheldt catchment can be used to compare different long-term policy options for N load reduction to river, estuary, and receiving sea in terms of their effectiveness, cost, and optimal location of implementation.

Joachim Maes

2012-06-01

134

Some ecological studies of the lower Cape Fear River Estuary, ocean outfall, and Dutchman Creek, 1971  

International Nuclear Information System (INIS)

A survey of the hydrography and biological components of the Cape Fear River Estuary and nearshore ocean off Oak Island was conducted. Species diversity indices were computed from nekton samples and phytoplankton, zooplankton, and benthos samples are being analysed. A computer program was developed whereby data were alphabetized by species, sorted by location, station, and date, and printed. Experiments were conducted to determine the Critical Thermal Maximum of shrimp. Measurements were made on water temperature, salinity, and dissolved oxygen from June through October. (U.S.)

135

Stratified active archaeal communities in the sediments of Jiulong River estuary, China  

OpenAIRE

Here the composition of total and active archaeal communities in a sediment core of Jiulong River estuary at Fujian Province, Southern China was reported. Profiles of CH4 and SO2?4 concentrations from the sediment core indicated the existence of a sulfate-methane transition zone (SMTZ) in which sulfate reduction-coupled anaerobic oxidation of methane (AOM) occurs. Accordingly, three sediment layers (16–18.5 cm, 71–73.5 cm, and 161–163.5 cm) from the 1.2 m sediment core were sectioned ...

QianqianLi; ZhiweiChen; XijieYin

2012-01-01

136

Cesium-137, metals and organic carbon in the sediments of the James River estuary, Virginia  

International Nuclear Information System (INIS)

The concentrations of cesium 137, copper, lead, zinc and organic carbon in the sedimentary sub-environments found in a 10 km stretch of the the estuary of the James River, Virginia, were determined. Sedimentation rates in the different regions were estimated by cesium 137 geochronology and were found to vary from .4 to 3 cm/yr. Concentrations of cesium 137, lead, zinc, copper and carbon vary by a factor of 2 to 3 in surface sediments. Inventories for fine-grain sediments correlate well. Concentrations in coarse-grained sediments are considerably lower. (U.K.)

137

Biogeographical distribution of diverse anaerobic ammonium oxidizing (anammox) bacteria in Cape Fear River Estuary.  

Science.gov (United States)

Anaerobic ammonium oxidation (anammox) specific PCR method was developed to examine diversity and distribution of anammox bacteria in sediments collected from three different sites at Cape Fear River Estuary, North Carolina, where environmental parameters vary greatly over the year. Abundance and activities of anammox bacteria in these sediments were measured using the quantitative PCR (Q-PCR) method and (15)N isotope tracer incubations. Different anammox bacterial communities composed with Brocadia, Kuenenia, Jettenia or Scalindua were found among sites along the estuarine gradient. Seasonal variations of anammox community structures were observed along the estuary based on terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes. Correlation analysis suggested that salinity variation influenced the diversity and distribution of different anammox bacteria in the estuary. Q-PCR assays of anammox bacteria showed temporal and spatial variations of their abundances, which were highly correlated to salinity variation. (15)N isotope tracer incubations measured different anammox rates and its per cent contribution to total N(2) production among sites. The highest anammox rate was found at the site where Scalindua organisms dominated with the highest anammox bacterial abundance. Thus, we demonstrated a biogeographical distribution of diverse anammox bacteria influenced by salinity, and provide evidence to link anammox abundance and activities in estuarine sediments. PMID:19161435

Dale, Olivia R; Tobias, Craig R; Song, Bongkeun

2009-05-01

138

Historical deposition behaviors of PAHs in the Yangtze River Estuary: role of the sources and water currents.  

Science.gov (United States)

Historical profiles and sources of PAHs at two typical sediment cores (i.e., the shipping route site and the shoal site) were fully compared to probe the controlling factors, specifically the water currents, for the PAHs deposition processes in the Yangtze River Estuary. Compared with ocean water currents, river runoff affected by the water impoundment of the Three Gorges Dam greatly affected the PAHs levels and percent contribution of PAHs sources in the two cores. River runoff hindered the PAHs deposition in shoal site, while a contrary phenomenon was observed for the shipping route site. Though the PAHs in the estuary were mainly from river catchment, only low ring PAHs in the shipping route site were mainly from the upper reach of the river. Coarse sediments with higher organic carbon content also accounted for the higher deposition levels of PAHs in the shipping route site. PMID:23200571

Wang, Dongxin; Feng, Chenghong; Huang, Luxia; Niu, Junfeng; Shen, Zhenyao

2013-02-01

139

Shoreline Change along Sheltered Coastlines: Insights from the Neuse River Estuary, NC, USA  

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Full Text Available Coastlines are constantly changing due to both natural and anthropogenic forces, and climate change and associated sea level rise will continue to reshape coasts in the future. Erosion is not only apparent along oceanfront areas; shoreline dynamics in sheltered water bodies have also gained greater attention. Additional estuarine shoreline studies are needed to better understand and protect coastal resources. This study uses a point-based approach to analyze estuarine shoreline change and associated parameters, including fetch, wave energy, elevation, and vegetation, in the Neuse River Estuary (NRE at two contrasting scales, Regional (whole estuary and Local (estuary partitioned into eight sections, based on orientation and exposure. With a mean shoreline-change rate of –0.58 m yr?1, the majority (93% of the NRE study area is eroding. Change rates show some variability related to the land-use land-cover classification of the shoreline. Although linear regression analysis at the Regional Scale did not find significant correlations between shoreline change and the parameters analyzed, trends were determined from Local Scale data. Specifically, erosion rates, fetch, and wave exposure increase in the down-estuary direction, while elevation follows the opposite trend. Linear regression analysis between mean fetch and mean shoreline-change rates at the Local Scale provide a first-order approach to predict shoreline-change rates. The general trends found in the Local Scale data highlight the presence of underlying spatial patterns in shoreline-change rates within a complex estuarine system, but Regional Scale analysis suggests shoreline composition also has an important influence.

J.P. Walsh

2011-07-01

140

Impact of entrainment and impingement on fish populations in the Hudson River estuary. Volume I. Entrainment-impact estimates for six fish populations inhabiting the Hudson River estuary  

International Nuclear Information System (INIS)

This volume is concerned with the estimation of the direct (or annual) entrainment impact of power plants on populations of striped bass, white perch, Alosa spp. (blueback herring and alewife), American shad, Atlantic tomcod, and bay anchovy in the Hudson River estuary. Entrainment impact results from the killing of fish eggs, larvae, and young juveniles that are contained in the cooling water cycled through a power plant. An Empirical Transport Model (ETM) is presented as the means of estimating a conditional entrainment mortality rate (defined as the fraction of a year class which would be killed due to entrainment in the absence of any other source of mortality). Most of this volume is concerned with the estimation of several parameters required by the ETM: physical input parameters (e.g., power-plant withdrawal flow rates); the longitudinal distribution of ichthyoplankton in time and space; the duration of susceptibility of the vulnerable organisms; the W-factors, which express the ratios of densities of organisms in power plant intakes to densities of organisms in the river; and the entrainment mortality factors (f-factors), which express the probability that an organism will be killed if it is entrained. Once these values are obtained, the ETM is used to estimate entrainment impact for both historical and projected conditions

141

Impact of entrainment and impingement on fish populations in the Hudson River estuary. Volume I. Entrainment-impact estimates for six fish populations inhabiting the Hudson River estuary  

Energy Technology Data Exchange (ETDEWEB)

This volume is concerned with the estimation of the direct (or annual) entrainment impact of power plants on populations of striped bass, white perch, Alosa spp. (blueback herring and alewife), American shad, Atlantic tomcod, and bay anchovy in the Hudson River estuary. Entrainment impact results from the killing of fish eggs, larvae, and young juveniles that are contained in the cooling water cycled through a power plant. An Empirical Transport Model (ETM) is presented as the means of estimating a conditional entrainment mortality rate (defined as the fraction of a year class which would be killed due to entrainment in the absence of any other source of mortality). Most of this volume is concerned with the estimation of several parameters required by the ETM: physical input parameters (e.g., power-plant withdrawal flow rates); the longitudinal distribution of ichthyoplankton in time and space; the duration of susceptibility of the vulnerable organisms; the W-factors, which express the ratios of densities of organisms in power plant intakes to densities of organisms in the river; and the entrainment mortality factors (f-factors), which express the probability that an organism will be killed if it is entrained. Once these values are obtained, the ETM is used to estimate entrainment impact for both historical and projected conditions.

Boreman, J.; Barnthouse, L.W.; Vaughn, D.S.; Goodyear, C.P.; Christensen, S.W.; Kumar, K.D.; Kirk, B.L.; Van Winkle, W.

1982-01-01

142

Analysis of thermal impact in tidal rivers and estuaries  

International Nuclear Information System (INIS)

The paper presents a far field mathematical model for numerical simulation of transient one or two-dimensional thermal distributions in regions with severe reversing flow conditions. The Eulerian formulation employs the integral form of the conservation principles for mass and thermal energy. The two-dimensional (2 D) solution area is spanned by discrete elements of variable size and shape. The three-dimensional geometry of the flow region is accounted for by spatially intergrating over the enclosure surfaces of the discrete element. The derivation of the two-dimensional depth-averaged temperatur equations includes the constributions of the vertical variations of velocity and temperature. Surface heat transfer as well as turbulent effects are taken into account. Important mathematical and computational features of the model are summarized. There is a discussion of the four main algorithms, necessary to treat flow regions with complex shoreline geometries, viz. (i) specification of the boundary (ii) determination of all discrete element midpoints lying within the (possibly multiconnected) solution area (iii) construction of discrete elements of irregular geometry exactly matching the (curved) boundary, (iv) treatment of boundary condiditons and numerical solution of the resulting mathematical system of weakly coupled, ordinary differential equations derived from the conservation principles. Preliminary results of a computer simulation are compared with the available data for a section of the Lower Elbe river. The calculation of the two-dimensional temperature distribution includes existing power plants and industrial sites. (orig.)

143

Continuous resistivity profiling and seismic-reflection data collected in 2006 from the Potomac River Estuary, Virginia and Maryland  

Science.gov (United States)

In 2006 the U.S. Geological Survey conducted a geophysical survey on the Chesapeake Bay and the Potomac River Estuary in order to test hypotheses about groundwater flow under and into Chesapeake Bay. Resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge and are contributing to eutrophication. The research carried out as part of this study was designed to help refine nutrient budgets for Chesapeake Bay by characterizing submarine groundwater flow and groundwater discharge beneath part of the bay?s mainstem and a major tributary, the Potomac River Estuary. The data collected indicate that plumes of reduced-salinity groundwater are commonly present along the shorelines of Chesapeake Bay and the Potomac River Estuary. Data also show that buried paleochannels generally do not serve as conduits for flow of groundwater from land to underneath the bay and estuary but rather may focus discharge of reduced-salinity water along their flanks, and provide routes for migration of saltwater into the sediments.

Cross, V.A.; Foster, D.S.; Bratton, J.F.

2010-01-01

144

Spatial distribution and quantification of endocrine-disrupting chemicals in Sado River estuary, Portugal.  

Science.gov (United States)

The important Portuguese Sado River estuary has never been investigated for the presence of potentially endocrine-disrupting chemicals (EDCs), such as natural estrogens (estradiol, estrone), pharmaceutical estrogens (17alpha-ethynylestradiol), phytoestrogens (daidzein, genistein and biochanin A), or industrial chemicals (4-octylphenol, 4-nonylphenol, and bisphenol A). Thus, the main objective of this study was to evaluate their presence at 13 sampling points distributed between both the industrial and the natural reserve areas of the estuary, zones 1 and 2, respectively. For that, water samples collected in summer and winter were processed by solid phase extraction and analyzed by high-performance liquid chromatography with photodiode array detection and gas chromatography-mass spectroscopy. Results showed that estrone, ethynylestradiol, all the aforementioned phytoestrogens as well as bisphenol A and 4-octylphenol were found in zone 1. In zone 2, neither estrogens nor 4-OP were found. However, in the same zone, daidzein (500 ng/L) and genistein (320 ng/L) attained their highest levels in summer, whereas biochanin A peaked in winter (170 ng/L). Furthermore, bisphenol A was also found in some areas of zone 2, but showed similar concentrations in both surveys (about 220 ng/L). This study demonstrated that the Sado River estuary had low EDCs levels, suggesting that the Sado's high hydrodynamic activity may be involved in the dilution of local pollution. It was suggested that at the current levels of concentrations, all assayed EDCs are unlikely to individually cause endocrine disruption in local animals. However, under a continuous exposure scenario, an additive and/or synergistic action of the estrogenic chemicals load can not be excluded, and so, continuous monitoring is advisable. PMID:19107565

Ribeiro, Cláudia; Pardal, Miguel Angelo; Tiritan, Maria Elizabeth; Rocha, Eduardo; Margalho, Rui Miguel; Rocha, Maria João

2009-12-01

145

Relationship of Caspian tern foraging ecology to nesting success in the Columbia River estuary, Oregon, USA  

Science.gov (United States)

The prevalence of juvenile salmonids ( Oncorhynchus spp.) and marine forage fishes in the diet of Caspian terns ( Hydroprogne caspia) nesting in the Columbia River estuary has been established, but the relationship between diet composition, foraging distribution, and productivity of these birds has received little attention. We used radio-telemetry and on-colony observations to relate changes in off-colony distribution to patterns of colony attendance, diet composition, and productivity of adult terns nesting on East Sand Island during two years of different river and prey conditions. Average distance from the East Sand Island colony (located in the marine zone of the estuary) was 38% (6.6 km) greater in 2000 compared to 2001, associated with lower availability of marine forage fish near East Sand Island and lower prevalence of marine prey in tern diets. Colony attendance was much lower (37.0% vs. 62.5% of daylight hours), average trip duration was 40% longer (38.9 min), and nesting success was much lower (0.57 young fledged pair -1 vs. 1.40 young fledged pair -1) in 2000 compared to 2001. Higher proportions of juvenile salmonids in the diet were associated with relatively high use of the freshwater zone of the estuary by radio-tagged terns, which occurred prior to chick-rearing and when out-migrating salmonid smolts were relatively abundant. Lower availability of marine prey in 2000 apparently limited Caspian tern nesting success by markedly reducing colony attendance and lengthening foraging trips by nesting terns, thereby increasing chick mortality rates from predation, exposure, and starvation.

Anderson, Scott K.; Roby, Daniel D.; Lyons, Donald E.; Collis, Ken

2007-07-01

146

Variability of Organic Carbon Content in Bottom Sediment of Pahang River Estuary, Pahang, Malaysia  

Directory of Open Access Journals (Sweden)

Full Text Available The percentage organic carbon content of 62 bottom estuarine sediment in Pahang river estuary were analyzed using the wet dichromate oxidation method. In this study, the organic carbon distribution ranged from 0.09 to 2.05%. The high concentration can be found near the Pahang river mouth while the low concentration occurred at upstream. The sediment particle size at the same transects were also measured with the dry sieving and laser diffraction method. The average concentration of organic carbon was 0.88% while the average grain size was 2.44 ?. In this study, the carbon organic showed a significant relationship with the mean size (p<0.05 with the organic carbon content increase with the increase of mean size values.

B.Y. Kamaruzzaman

2009-01-01

147

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2009  

Energy Technology Data Exchange (ETDEWEB)

This is the sixth annual report of a seven-year project (2004 through 2010) to evaluate the cumulative effects of habitat restoration actions in the lower Columbia River and estuary (LCRE). The project, called the Cumulative Effects Study, is being conducted for the U.S. Army Corps of Engineers Portland District (USACE) by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory (PNNL), the Pt. Adams Biological Field Station of the National Marine Fisheries Service (NMFS), the Columbia River Estuary Study Taskforce (CREST), and the University of Washington. The goal of the Cumulative Effects Study is to develop a methodology to evaluate the cumulative effects of multiple habitat restoration projects intended to benefit ecosystems supporting juvenile salmonids in the 235-km-long LCRE. Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. From 2005 through 2009, annual field research involved intensive, comparative studies paired by habitat type (tidal swamp versus marsh), trajectory (restoration versus reference site), and restoration action (tidegate replacement vs. culvert replacement vs. dike breach).

Johnson, Gary E.; Diefenderfer, Heida L.; Borde, Amy B.; Bryson, Amanda J.; Cameron, April; Coleman, Andre M.; Corbett, C.; Dawley, Earl M.; Ebberts, Blaine D.; Kauffman, Ronald; Roegner, G. Curtis; Russell, Micah T.; Silva, April; Skalski, John R.; Thom, Ronald M.; Vavrinec, John; Woodruff, Dana L.; Zimmerman, Shon A.

2010-10-26

148

Preliminary study on the dissolved and colloidal organic carbon in the Zhujiang River estuary  

Science.gov (United States)

This paper reports data on the dissolved and colloidal organic carbon in the Zhujiang (Pearl) River estuary. DOC concentration was 142 to 239 ?mol/L in the freshwater taken in March 1997 from the four Zhujiang River tributaries flowing into the Lingdingyang estuary. High concentration was observed in the Humen tributary located near Guangzhou. The rapidly increased DOC concentration at low salinities (˜5) may be attributed to the exchange between macroparticulate and dissolved organic matter during the early stage of estuarine mixing. DOC concentration overall followed the mixing line until salinity 25, where the Deep Bay is located and where DOC was elevated. This elevated DOC may suggest a local organic matter source from Shenzhen. Using a cross-flow ultrafiltration (CFF) system equipped with a Millipore Prep-scale CFF 1 kD regenerated cellulose membrane, we also separated the colloidal organic matter from the truly dissolved fraction (<1 kD). CFF membranes were carefully evaluated for their applicability (retention characteristics, blank level and mass balance) to separate colloidal organic matter. COC in the study area ranged from 5 to 85 ?mol/L, representing 3% 32% of DOC. The highest COC percentage was found at low salinities (<5) in both winter and summer. Evidence suggests in-situ production of colloidal material at this salinity range. Beyond this point, a very modest removal was observable until high salinities. Again, an increase in COC concentration was shown in the samples taken from the Deep Bay.

Dai, Min-Han; Martin, Jean-Marie; Hong, Hua-Sheng; Zhang, Zu-Lin

2000-09-01

149

Integrated estuary management for diffused sediment pollution in Dapeng Bay and neighboring rivers (Taiwan).  

Science.gov (United States)

This work investigated sediment samples collected from Dapeng Bay and three neighboring rivers (Kaoping River, Tungkang River, and Lingbeng River) in southwestern Taiwan, Republic of China. Multivariate statistical analysis techniques, i.e., factor analysis, cluster analysis, and canonical discriminant analysis were used for the evaluation of spatial variations to determine the types of pollution and to identify pollutant sources from neighboring rivers. Factor analysis results showed that the most important latent factors in Dapeng Bay are soil texture, heavy metals, organic matter, and nutrients factors. Contour maps incorporating the factor scores showed heavy metals accumulate along the lakesides, especially on the southeastern banks of the lakes. A cluster analysis was performed using factor scores computed from these latent factors. We then classified these areas into five distinct classes using sampling stations, and we illustrate that in the three river classes, the sediment properties are influenced by industrial and domestic wastewater and agricultural activities (including livestock rearing and farm activities). However, in Dapeng Bay, the rivers were influenced more by complicated biogeochemical processes; these could be identified as a type of pollution. Canonical discriminant analysis illustrated that two constructed discriminant functions made a marked contribution to most of the discriminant variables, and the significant parameters of porosity and Cd, Cr, Al, and Pb content were combined as the "heavy metal factor". The recognition capacities of the two discriminant functions were 82.6% and 17.4%, respectively. It is also likely that the annual mean of the water exchange rate is insufficient (taking about 7 days to eliminate pollutants) and therefore has significantly influenced the carbon and nutrient biogeochemical processes and budgets in the semi-enclosed ecosystem. Thus, the sediment properties are not similar between the lagoon and the neighboring rivers. Our results yield useful information concerning estuary recovery and water resources management and may be applicable to other basins with similar characteristics that are experiencing similar coastal environmental issues. PMID:20195746

Chung, Chung-Yi; Chen, Jen-Jeng; Lee, Chang-Gai; Chiu, Chun-Yen; Lai, Wen-Liang; Liao, Shao-Wei

2011-02-01

150

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

151

Emergy and Economic Evaluations of Four Fruit Production Systems on Reclaimed Wetlands Surrounding the Pearl River Estuary, China  

Science.gov (United States)

Emergy and economic methods were used to evaluate and compare a traditional tropical fruit cultivation system, for bananas, and three newly introduced fruit cultivation systems, for papaya, guava and wampee, on reclaimed wetlands of the Pearl River Estuary, China. The evaluations...

152

Evaluation of the Level of Organochlorinated Pesticides Contamination in Environment of the Red River and its Balat Estuary  

International Nuclear Information System (INIS)

The pollution level of OC pesticides such as Lindane, DDT and its metabolites contaminants in water, sediments and Biota collected along the Red River and from the Balat estuary have, for the first time in the North of Vietnam, been determined by GC technique using capillary columns and electron capture detection (ECD). The concentration of DDT and DDE was found to be up to 38.4 ppb and 27.3 ppb, respectively, in sediments from the Red River and its Balat estuary. Lindane residue in Red River's and Balat estuary's sediments was found at level of 1.3-4.2 and 14.6-52.6 ppb, respectively. In water Lindane contaminant was detected in the sample collected from the estuarine area only, while DDE was found in both River and estuarine water. Residue of Lindane in mussel flesh was found to be always higher (up to 145 ppb) than that of any DDT's metabolites, e.g. the highest value of DDE contaminant is 66 ppb. The finding shows that Lindane contamination in marine environmental samples from the Balat estuary is higher as compared with those from the Mediterranean Sea but DDT's ones are at the same level. (author). 8 refs., 6 tabs., 1 map

153

Polycyclic aromatic hydrocarbons in suspended particulate matter and sediments from the Pearl River Estuary and adjacent coastal areas, China  

International Nuclear Information System (INIS)

The spatial distribution, composition, and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments and suspended particulate matter (SPM) from the Pearl River Estuary and adjacent coastal areas were examined. Total PAH concentrations varied from 189 to 637 ng/g in sediments and 422 to 1850 ng/g in SPM. PAHs were dominated by 5,6-ring compounds in sediments and by 2,3-ring compounds in SPM samples. Assessment of PAH sources suggested that biomass and coal combustion is the major PAH source to the outer part of the estuary sediments and that petroleum combustion is the major PAH source to the inner part of estuary sediments. As for SPM samples, PAH isomer pair ratios indicated multiple (petroleum, petroleum combustion, and biomass and coal combustion) PAH sources, and significant temporal variations could exist for the sources of water column PAHs in the study area. The distribution of perylene in SPM samples indicated that the river was the dominant source of perylene in SPM and that perylene could be taken as an index to assess the contribution of river inflow to the total PAHs in SPM samples. The high concentration of perylene in the sediment was indicative of an in situ biogenic origin. - PAH were determined in suspended particulate matter and sediments from Pearl River Estuary

154

Long time series of Landsat images to reconstruct river surface temperature and turbidity regimes of Guadalquivir Estuary  

OpenAIRE

In the last century the Guadalquivir River in Andalusia has been dramatically transformed affecting its ecological and hydrological functioning. In view of a new dredging plan to increase ship size and number arriving to Seville, a research consortium has started to study the state of the Guadalquivir Estuary. The Remote Sensing and GIS laboratory of Doñana Biological Station participates in the project with the aim to reconstruct the last 35 years regime of turbidity and river surface tempe...

Ameztoy, Iban; Di?az-delgado, Ricardo; Cristobal, Jordi; Bustamante, Javier

2010-01-01

155

Geochemistry of the suspended sediment in the estuaries of the Mandovi and Zuari rivers, central west coast of India.  

Science.gov (United States)

The geochemistry of the suspended particulate matter (SPM) collected during the monsoon was determined to identify the sources of SPM and to understand the physicochemical processes in the Mandovi and Zuari river estuaries. The concentrations of SPM decrease seaward in both estuaries, but are relatively high at bay stations. Kaolinite is the most dominant clay mineral in the upstream of both rivers. Smectite increases seaward in both estuaries and is abundant in the bay. Upstream stations of Mandovi, where ore deposits are stored on the shore, exhibit high Fe, Mn, total rare earth elements (?REE), and middle REE- and heavy REE-enriched patterns. Channel stations of both estuaries exhibit middle REE- and light REE-enriched patterns, which gradually changed seaward to middle REE- and heavy REE-enriched patterns. Canal stations exhibit the highest concentrations of major and trace metals. High metal/Al ratios occur at stations in the upstream of Zuari and at the confluence of canals in the Mandovi estuary. Enrichment factors of metals indicate that Mn is significantly polluted while other metals are moderately polluted. The ?(13)C and ?(15)N of organic matter indicate that the terrigenous organic matter at the upstream is diluted seaward by marine organic matter. Organic matter at bay stations is largely marine and altered-type. The compositions of SPM are controlled by the particulates from ore dust, the geology of the drainage basins, and the physicochemical processes in the estuaries. Particulates resuspended from the bay are dominated by ore dust, which are advected into the channels of both estuaries during the lull periods of the monsoon. PMID:23054263

Kessarkar, Pratima M; Shynu, R; Rao, V Purnachandra; Chong, Feng; Narvekar, Tanuja; Zhang, Jing

2013-05-01

156

Report on the workshop examining the potential effects of hydroelectric development on Beluga of the Nelson River Estuary, Winnipeg, Manitoba, November 6 and 7, 1990  

International Nuclear Information System (INIS)

A summary is presented of discussions and conclusions at a workshop held to examine the potential effects of hydroelectric development on beluga whales of the Nelson River estuary in Manitoba. Background information is provided on the estuary, beluga whales and their use of arctic and subarctic estuaries, and hydroelectric development on the Nelson River. Potential impacts of such development on the whales are reviewed in the categories of direct effects of changes in physical-chemical conditions (temperature and discharge), indirect effects of disturbances mediated through the food chain, and effects on socioeconomic conditions that may affect beluga whales. Since the biology of beluga whales and other phenomena of interest in this study are poorly known, recommendations are made for research and monitoring activities in the Nelson River estuary. In general, the workshop participants felt that changes in the estuary due to hydroelectric development would not be large enough to affect beluga whales strongly. 34 refs., 1 fig

157

Parasitological survey of mangrove oyster, Crassostrea rhizophorae, in the Pacoti River Estuary, Ceará State, Brazil.  

Science.gov (United States)

The mangrove oyster, Crassostrea rhizophorae (Bivalvia, Ostreidae) is commonly collected by fisherwomen in the estuaries of the Ceará State (CE), Northeastern Brazil. Despite the socioeconomic importance of this natural resource, there are few studies on the health of the oysters in this region. This study aimed to survey pathological changes in the mangrove oyster C. rhizophorae in the estuary of the Pacoti River, CE. Adult oysters were collected in August 2008 (N=450) and December 2009 (N=450) at three sites of the Pacoti estuary and in 2010 (N=600) samplings were done quarterly at one site which has showed the higher prevalence de Perkinsus. Macroscopical and histological analyses were used to evaluate pathological changes, Ray's Fluid Thioglycollate Medium (RFTM) to detect Perkinsus spp. and polymerase chain reactions (PCR) and DNA sequencing to identify Perkinsus species. In 2009, RFTM assay detected Perkinsus sp. infecting the tissues of C. rhizophorae with low prevalences of 1.3%, 6.7% e 7.3% in sites 1, 2 and 3, respectively, and in 2010, in site 3, prevalence was 2% (12 of 600 oysters). PCR did not confirm any positive case in 2009 and only 5 in 2010. The phylogenetic analyses strongly indicate that the Perkinsus species infecting oysters C. rhizophorae of this study belongs to Perkinsus beihaiensis. The histology confirmed 11 cases of Perkinsus sp. infecting the C. rhizophorae in 2009, and only two cases in 2010. Nematopsis sp. was the protozoan observed with greater prevalence (up 96.7%). Other found protozoa were: Trichodina, Sphenophrya, Ancistrocoma - like and an unknown ovarian parasite. The metazoa found were the polychaete Polydora with high prevalences, a turbellarian, possibly of the genus Urastoma, an unidentified digenean metacercariae and larvae of cestode Tylocephalum. A continuous monitoring of diseases in bivalves from this natural population is recommended, since the phylogenetic analyses indicate the occurrence of P. beihaiensis infecting oysters C. rhizophorae whose pathogenic potential is unknown. PMID:23147104

Sabry, Rachel Costa; Gesteira, Tereza Cristina Vasconcelos; Magalhães, Aimê Rachel Magenta; Barracco, Margherita Anna; Guertler, Cristhiane; Ferreira, Liana Pinho; Vianna, Rogério Tubino; da Silva, Patrícia Mirella

2013-01-01

158

Modeling the transport of freshwater and dissolved organic carbon in the Neuse River Estuary, NC, USA following Hurricane Irene (2011)  

Science.gov (United States)

Numerical models are useful tools that aid in understanding complex flows and the distribution of suspended material over large geographic areas and during extreme weather events. Here we describe the use of a three-dimensional numerical model (Delft3D) to simulate freshwater and dissolved organic carbon (DOC) transport over a 3-week period, following intense precipitation that led to high river discharge into the brackish Neuse River Estuary (NRE), NC, from Hurricane Irene (Aug. 2011). The model was calibrated and validated using field measurements of water level elevations, vertical salinity profiles, and surface DOC concentrations in the estuary. DOC was simulated as a conservative tracer over the study period. Model results indicate differences in the intensity of the freshwater and DOC-laden plumes as they propagated along estuary due to a one week time lag between the maximum discharge of 540 m3 s-1 and maximum DOC concentration of 29.85 mg L-1 entering the NRE from the river. In the upper estuary, the surface DOC concentration increased by 18 mg L-1 above the pre-storm value of 7 mg L-1; the maximum concentration occurred 10 days after the passage of the storm. In the lower estuary, the outer edge of the DOC plume reached Pamlico Sound after 3 weeks with a surface DOC concentration that was 3 mg L-1 above the pre-storm value. Results also indicate cross-channel salinity differences up to 10 ppt and DOC concentration differences up to 15 mg L-1 in the upper NRE to due to wind-driven motion of the estuary. The methods described here could be applied to other coastal plain estuarine systems to simulate and characterize flow rates and DOC transport during and succeeding storm events where field measurements are often limited.

Brown, Matthew M.; Mulligan, Ryan P.; Miller, Richard L.

2014-02-01

159

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2008  

International Nuclear Information System (INIS)

Draft annual report for the Cumulative Effects Study for the US Army Corps of Engineers, Portland District. This is the fifth annual report of a seven-year project (2004 through 2010) to evaluate the cumulative effects of habitat restoration actions in the 235-km-long Columbia River estuary. The project, called the Cumulative Effects Study, is being conducted for the U.S. Army Corps of Engineers, Portland District (CENWP), by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory (PNNL), the Pt. Adams Biological Field Station of the National Marine Fisheries Service (NMFS), and the Columbia River Estuary Study Taskforce (CREST). The goal of the Cumulative Effects Study is to develop a methodology to evaluate the cumulative effects of multiple habitat restoration projects intended to benefit ecosystems supporting juvenile salmonids in the lower Columbia River and estuary (LCRE). Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. From 2005 through 2008, annual field research involved intensive, comparative studies paired by habitat type (tidal swamp versus marsh), trajectory (restoration versus reference site), and restoration action (tide gate versus culvert versus dike breach). During 2008, the specific objectives for the Cumulative Effects Study were to do the following: (1) Summarize the adaptive management framework for LCRE habitat restoration ac framework for LCRE habitat restoration activities; (2) Finalize the levels-of-evidence approach and ecological theory underpinning the analysis, synthesis, and evaluation of the cumulative effects of multiple habitat restoration projects in the LCRE; (3) Summarize new results from analyses from 2005-2008 project research for the purpose of cumulative effects evaluation in the LCRE; (4) Initiate a synthesis and evaluation of cumulative effects in the LCRE; (5) Assess management implications, lessons learned, decision-making, 2009-2010 research, and final project deliverables; and (6) Provide a hydrodynamic model assessment of synergistic effects, analysis summaries of the additive modeling pilot study, natural breach and habitat creation sites, wetted area, hydrology and fish, monitoring summaries for Julia Butler Hanson Wildlife Refuge and Crims Island, and a preliminary meta-analysis of effectiveness monitoring data.

160

Distribution of Chromium, Manganese and Cobalt in the Bottom Sediment of Pahang River-Estuary, Pahang, Malaysia  

OpenAIRE

Bottom sediments from 62 stations at Pahang river-estuary were analyzed for the concentrations of Chromium (Cr), Manganese (Mn) and Cobalt (Co). Heavy metal concentrations were analyzed by using an Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The average dry weight concentrations of Cr, Mn and Co were 62.80±20.04, 416.21±127.41 and 7.93±3.25 ?g g-1, respectively. The observed concentrations of the studied metals were significantly higher near the estuary and declining as the sam...

Goddard, J. S.; Al-barwani, S. M.; Joseph, B.; Akbar John, B.; Shuhada, A. T.; Rina Sharlinda, Z.; Jalal, K. C. A.; Shahbudin, S.; Ong, M. C.; Mohd Zahir, M. S.; Siti Waznah, A.; Kamaruzzaman, B. Y.

2010-01-01

161

Geomorphological characteristics and variability of Holocene mass-transport complexes, St. Lawrence River Estuary, Canada  

Science.gov (United States)

Recently acquired multibeam bathymetry data are used to investigate seafloor instability features along a 310 km-long segment of the St. Lawrence River Estuary. The analysis of this dataset indicates that submarine slides occur over a much larger area than previously recognized and that Holocene sediments are reworked by mass-transport along significant portions of both the northwest and southeast margins of the Laurentian Channel. In the surveyed area, 96 individual mass-transport complexes (MTCs) were identified representing 13% of the seabed. MTCs vary in area from less than 1 km2 to more than 40 km2 and exhibit various geomorphological signatures. Qualitative observation reveals an apparent disparity between MTCs that remain coherent and those that disintegrate during downslope transport evolving into a blocky morphological signature. For all MTCs, morphological parameters have been measured (area, length, and height) or calculated (slope and roughness). This quantitative analysis provides a unique opportunity to study these parameters in a statistically significant and homogeneous dataset located in a relatively small area that experienced a similar Quaternary history. In many cases, mass transport events appear to initiate in the vicinity of steep bedrock walls located along some segments of the estuary. The timing of mass-transport events was not constrained during this study. However, the fact that the region hosts the Charlevoix seismic zone, the most tectonically active area in eastern Canada, strongly suggests that earthquakes acted as a trigger for submarine landsliding.

Pinet, Nicolas; Brake, Virginia; Campbell, Calvin; Duchesne, Mathieu J.

2015-01-01

162

Species composition and gear characteristics of the Macrobrachium fishery of the Cross River Estuary, Nigeria  

Science.gov (United States)

The Cross River Estuary, Nigeria, is an important shrimping area for artisanal fishermen of the coastal communities. The multi-species Macrobrachium fishery is exploited with three main gears, namely beach seine, push net and trap. Studies on species composition of this fishery recorded thirteen shrimp species, one swimming crab ( Callinectes amnicola) and two fish species ( Eleotris sp. and Pellonula leonensis). The shrimp species identified included Macrobrachium macrobrachion (83.39% and 55.69% by number and weight, respectively), M. vollenhovenii (9.66% and 37.18%), M. equidens (3.8% and 2.87%), juveniles-sub-adults of Penaeus notialis (1.11% and 1.3%), M. dux, M. felicinum, Palaemonetes africanus, Palaemon maculatus, Palaemon elegans, Desmocaris sp., Leander sp., Nematopalaemon hastatus and Alpheus pontederiae. While the selectivity index for trap was 0.25, beach seine and push net had a lower index of 0.063. The results present the first comprehensive and representative report for the Estuary shrimp fishery and will assist in the management of the biodiversity of this ecosystem.

Nwosu, Francis M.

2010-03-01

163

Water abstraction along the lower Yangtze River, China, and its impact on water discharge into the estuary  

Science.gov (United States)

The impact of human activities on river discharge has become a worldwide issue due to rapid developments. In recent years, water abstraction along the lower Yangtze River downstream from Datong has received much attention due to the increase of salt intrusion in the estuary. This study has been conducted to estimate the water abstraction and drainage along the lower Yangtze River for the critical period between September and April, identify their spatial differences and temporal variations, and analyze their impact on water discharge into the estuary. The results show that the drainage is dominant in the upper portion, and does not follow any obvious pattern. However, the water abstraction mainly occurs in the lower portion, and follows set patterns in daily variation according to the tidal situation and the seasonal variation corresponding with the water demands. They have both increased in recent similar hydrological years due to rapid developments. The water abstraction decreases the discharge into the estuary in dry years or dry periods, most dramatically during spring tide. The highest impact occurs between January and March of a dry year. After the commissioning of the Three Gorges Reservoir (TGR), this impact increased in October and November due to its filling, more so when a drought occurs in the upper and middle basin. However, the reverse applies between January and April owing to the increase of its outflow. In the future, the water abstraction will continue to increase in the same hydrological years, possibly increasing problems with salt intrusion in the Yangtze Estuary.

Zhang, Erfeng; Savenije, Hubert H. G.; Chen, Shenliang; Chen, Jiyu

164

226Ra and 228Ra in the mixing zones of the Pee Dee River-Winyah Bay, Yangtze River and Delaware Bay Estuaries  

International Nuclear Information System (INIS)

226Ra and 228Ra have non-conservative excess concentrations in the mixing zones of the Pee Dee River-Winyah Bay estuary, the Yangtze River estuary, and the Delaware Bay estuary. Laboratory experiments, using Pee Dee River sediment, indicate desorption of 226Ra to increase with increasing salinities up to 20 per mille. In Winyah Bay desorption from river-borne sediments could contribute almost all of the increases for both isotopes. Desorption adds only a portion of the excess 228Ra measured in the Yangtze River and adjacent Shelf waters and Delaware Bay. In the Yangtze River the mixing zone extends over a considerable portion of the Continental Shelf where 228Ra is added to the water column by diffusion from bottom sediments, while 226Ra concentrations decrease from dilution. Diffusion of 228Ra from bottom sediments in Delaware Bay primarily occurs in the upper part of the bay (228Ra of 0.33 dpm cm-2 year was determined for Delaware Bay. (author)

165

Characterization of dissolved organic matter in the Piauí river estuary, Northeast Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A espectroscopia de fluorescência e o carbono orgânico dissolvido (COD) foram utilizados para caracterização da matéria orgânica dissolvida (MOD) no estuário do Rio Piauí, um estuário tropical situado no Estado de Sergipe, nordeste do Brasil. As intensidades de fluorescência foram maiores no período [...] chuvoso e menores no período seco, evidenciando que a variabilidade das propriedades fluorescentes da MOD é ditada, principalmente, pela descarga fluvial e pelo processo de diluição no estuário. No período chuvoso, os compostos tipo triptofano e húmicos predominaram na composição da MOD, enquanto no período seco ocorreu um aumento significativo dos constituintes tipo proteínas. As relações das intensidades de fluorescência com a salinidade sugerem um comportamento não conservativo para a MOD fluorescente. O COD mostrou um comportamento conservativo no período seco e não conservativo no período chuvoso, com produção de COD na parte superior do estuário. A complexação da MOD com o Cu(II), estudada usando a técnica de supressão da fluorescência, evidenciou o potencial de complexação dos fluoróforos tipo proteínas, tripofano e húmico. Abstract in english Fluorescence spectroscopy and dissolved organic carbon (DOC) measurements were used to characterize the dissolved organic matter (DOM) in the Piauí River estuary, a tropical estuary situated in the State of Sergipe, Northeast Brazil. Fluorescence intensities were greater during the rainy period than [...] the dry period, demonstrating that variability in the fluorescence properties of the DOM was determined mainly by the fluvial discharge and the dilution processes occurring in the estuary. During the rainy period, tryptophan-like and humic substances were the main components of the DOM, while during the dry period there was a significant increase of protein-like constituents. Relationships identified between fluorescence intensities and salinity were indicative of non-conservative behavior of the fluorescent DOM. DOC showed behavior that was conservative during the dry period, and non-conservative during the rainy period, with production of DOC in the upper reaches of the estuary. The complexation of DOM with Cu(II), studied using the fluorescence suppression technique, showed the complexation potentials of protein, tryptophan and humic type fluorophores.

Adnivia Santos, Costa; Elisangela de Andrade, Passos; Carlos A. B., Garcia; José do Patrocinio H., Alves.

2139-21-01

166

The biogeochemistry of photosynthetic pigments in the Jiulong River estuary and Western Xiamen Bay  

Science.gov (United States)

High performance liquid chromatography (HPLC) analysis of photosynthetic pigments in samples from Western Xiamen Bay and the Jiulong River Estuary showed that their major carotenoids were fucoxanthin, peridinin, zeaxanthin, violaxanthin, and diadinoxanthin. Diatoms dominated in the spring bloom, dinoflagellates in summer. Violaxanthin and chlorophyll b indicated the appearance of chrysophytes and green algae, most of which were freshwater species. The high phytoplankton biomass region was located at the inner part of the bay. Diatoms and dinoflagellates dominnated phytoplankton communities, contributing to over 50% of total biomass. All the main diagnostic carotenoids were significantly (P<0.01) correlated negatively to dissolved inorganic phosphorus, suggesting that they were limited by phosphorus. The high negative linear relationship (P<0.0001) between dissolved inorganic phosphorus and peridinin (dinoflagellates indicator) implied the potential of dissolved inorganic phosphorus for triggering red tide events in this region.

Xu, Li; Hong, Hua-Sheng; Wang, Hai-Li; Chen, Wei-Qi

2001-06-01

167

Assessment of essential elements and heavy metals content on Mytilus galloprovincialis from river Tagus estuary.  

Science.gov (United States)

Trace elemental content was analysed in edible tissues of Mytilus galloprovincialis collected in five different sampling areas near the mouth of river Tagus estuary in Lisbon. The concentrations of essential elements (S, K, Ca, Fe, Cu, Zn, As, Br and Sr) were determined by energy-dispersive X-ray fluorescence (EDXRF) spectrometry, while toxic elements (Cr, Cd, Hg, Se and Pb) were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results show that the essential elements K and S are present at the highest concentrations in all the studied samples reaching 2,920 and 4,520 ?g g(-1) (fresh weight), respectively. The highest levels of heavy metals found were in two areas close to the city for Pb and Cd, but below the maximum allowed values. PMID:24763710

Santos, I; Diniz, M S; Carvalho, M L; Santos, J P

2014-06-01

168

The hydrokinetic power resource in a macrotidal estuary: the Kennebec River of the central Maine coast  

Science.gov (United States)

Power levels available from the kinetic energy of tidal flows can be significant in coastal or estuarine regions with relatively modest tidal ranges. For example, the central Maine coast, where the mean semidiurnal tidal range is about 3 m, includes several river estuaries with narrow interconnecting passages where tidal currents exceed 2 m s-1. A numerical circulation model applied to this region shows that the vigorous tidal flows lead to available power peaks exceeding 3 Kw per square meter of turbine aperture in several sites during a spring tide. At one promising location, the peak power density is 6.5 Kw/m2 near the surface and the energy capacity in a 500 m2 section under mean tidal conditions is about 2700 Mwh per year, sufficient to meet the average consumption needs of about 150 homes connected to an electrical grid capable of accepting the tidal power pulses and blending them with traditional sources.

Brooks, D. A.

2012-12-01

169

A dinoflagellate Cochlodinium geminatum bloom in the Zhujiang (Pearl) River estuary in autumn 2009  

Science.gov (United States)

A severe Cochlodinium geminatum red tide (>300 km2) was observed in the Zhujiang (Pearl) River estuary, South China Sea in autumn 2009. We evaluated the environmental conditions and phytoplankton community structure during the outbreak. The red tide water mass had significantly higher dissolved inorganic phosphate (DIP), ammonia, and temperature, but significantly lower nitrite, nitrate, dissolved inorganic nitrogen (DIN), and DIN/DIP relative to the non-red-tide zones. The phytoplankton assemblage was dominated by dinoflagellates and diatoms during the red tide. C. geminatum was the most abundant species, with a peak density of 4.13×107 cell/L, accounting for >65% of the total phytoplankton density. The DIN/DIP ratio was the most important predictor of species, accounting for 12.45% of the total variation in the phytoplankton community. Heavy phosphorus loading, low precipitation, and severe saline intrusion were likely responsible for the bloom of C. geminatum.

Ke, Zhixin; Huang, Liangmin; Tan, Yehui; Song, Xingyu

2012-05-01

170

239 240Pu and 238Pu in sediments of the Hudson River estuary  

International Nuclear Information System (INIS)

Plutonium-239,240 and plutonium-238 were determined in 59 Hudson River sediment dredge samples collected during 1973-77 in the vicinity of the Indian Point Nuclear Power Station. Acid leaching followed by solvent extraction, electrodeposition, and alpha-spectrometry were used to extract, purify, and quantitate plutonium isotopes present in these samples. Annual median plutonium-238/plutonium-239,240 isotopic activity ratios in surficial sediments were 0.032 (1973-74), 0.035 (1975), 0.042 (1976), and 0.040 (1977). The source of these nuclides in the estuary was identified by analysis of the sample isotopic activity ratios. On the basis of the sampling regimen and the methods used, it is concluded that no input, other than that of fallout, has contributed significantly to the plutonium burden in Hudson sediments

171

Estimates of entrainment mortality for striped bass and other fish species inhabiting the Hudson River estuary  

International Nuclear Information System (INIS)

An empirically derived age-, time-, and space-variant equation was used to estimate entrainment mortality at power plants for seven fish species inhabiting the Hudson River estuary. Entrainment mortality is expressed as a conditional rate, which is the fractional reduction in year-class strength due to entrainment if other sources of mortality are density-independent. Estimates of the conditional entrainment mortality, based on historical and projected once-through cooling operation of five power plants, were 11-22% for striped bass, 11-17% for white perch, 5-7% for Atlantic tomcod, 14-21% for American shad, 4-11% for river herring (alewife and blueback herring combined), and 35-79% for bay anchovy. Closed-cycle cooling (natural-draft cooling towers) at three of the power plants (Indian Point, Bowline Point, and Roseton) would reduce entrainment mortality of striped bass by 50-80%, of white perch by 75-80%, of Atlantic tocod by 65-70%, of American shad by 80%, of river herring by 30-90%, and of bay anchovy by 45-80%. The life stages most vulnerable to entrainment mortality were post-yolk-sac larva and entrainable size juvenile. 18 refs., 7 tabs

172

Combined Stable Carbon Isotope and C/N Ratios as Indicators of Source and Fate of Organic Matter in the Bang Pa kong River Estuary, Thailand  

International Nuclear Information System (INIS)

Full text: Stable carbon isotopes and C/N ratios of particulate organic matter (POM) in suspended solids and surficial sediment were used to define the spatial and temporal variability in an anthropogenic tropical river estuary, the Bang Pa kong River Estuary. Samples were taken along salinity gradients during the four different river discharges in the beginning, high river discharge and at the end of the wet season, and low river discharge during the dry season. The values of [C/N]a ratio and d13C in the river estuary revealed significant differences from those of the offshore station. Conservative behaviors of [C/N]a and d13C in the estuary during the wet season indicated major contribution of terrigenous C3 plants derived OM. By contrast, during the dry season, marine input mainly dominated OM contribution with an evidence of anthropogenic input to the estuary. These compositions of the bulk sedimentary OM were dominated by paddy rice soils and marine derived OM during the wet and dry seasons, respectively. These results show that the combined stable carbon isotopes and C/N ratios can be used to identify the source and fate of OM even in a river estuary. This tool will be useful to achieve sustainable management in coastal zone

173

A 2011 drought event affecting distribution of nutrients and chlorophyll in the Zhujiang River estuary  

Science.gov (United States)

During the summer of 2011, a severe drought event occurred throughout the Zhujiang (Pearl) River Basin of South China. This decreased runoff into the river, resulting in increased salinity and reduced suspended substance. To examine the effects of this extreme drought on the distribution of nutrients and chlorophyll, we compared two surveys from 2006 and 2011. Results show that dissolved inorganic nitrogen concentration did not change from 2006 to 2011, whereas the proportions of NO{2/-} and NH{4/+} to DIN in 2011 increased. PO{4/3-} concentration was lower in 2011 than in 2006, whereas there was no difference in SiO{3/2-} concentration between these years. Correlation coefficients of salinity with levels of NO{3/-}, NO{2/-}, NH{4/+}, PO{4/3-} and SiO{3/2-} in 2011 were all much higher than those in 2006, suggesting greater conservation of dissolved nutrients during the extreme drought event. Furthermore, calculated amounts of regenerated nitrate and phosphorus and their proportions to observed nutrients in 2011 were much lower than in 2006, indicating that nutrient regeneration decreased during the extreme drought period. Mean concentration of chlorophyll a (Chl- a) was considerably higher in 2011 than in 2006, and a harmful algal bloom of Cochlodinium geminatum was observed in the estuary, owing to water stagnancy and lower turbidity as a consequence of drought. Therefore, the extreme drought event in 2011 changed the composition ratio of nutrients, enhanced nutrient conservative behavior, and reduced nutrient regeneration. This affected some key ecological processes in the estuary.

Shi, Zhen; Huang, Xiaoping; Zhang, Xia; Ye, Feng; Liang, Ximei; Ni, Zhixin; Cai, Weixu

2014-03-01

174

[Purification function and ecological services value of Crassostrea sp. in Yangtze River estuary].  

Science.gov (United States)

Oyster reef ecosystem is a natural decontamination plant of estuarine environment. This paper analyzed the bioaccumulation of heavy metals by Crassostrea sp. population at the dams of Yangtze River estuary, with its purification capacity and ecological services value assessed. The results indicated that Crassostrea sp. had a high capacity in bio-accumulating Cu, Zn and Cd, with the bio-concentration factor (BCF) and biota-sediment accumulation factor (BSAF) being (14.28 +/- 2.41) x 10(3), (12.75 +/- 2.02) x 10(3) and (14.51 +/- 3.71) x 10(3), and 26.78 +/- 4.53, 23.24 +/- 3.69 and 16.62 +/- 4.25, respectively. The bioaccumulation capacity decreased in the order of Cu > Zn > Cd > As > Pb > Hg. The total weight and fresh meat weight of the oyster at the dams of Yangtze River estuary were about 1.07 x 10(6) t and 1.75 x 10(5) t, respectively, and the total storage of nutrients and heavy metals were 1.462 x 10(6) kg N, 1 x 10(5) kg P, 24 745 kg Cu, 58 257 kg Zn, 609 kg Pb, 254 kg Cd, 0.18 kg Hg and 329 kg As. The total ecological services value of the oyster reef was estimated at about 8.27 x 10(6) RMB x a(-1), including habitat value of about 5.10 x 10(6) RMB x a(-1) and environmental value of about 3.17 x 10(6) RMB x a(-1). Such an environmental value was equivalent to the value of treating about 7.31 x 10(6) t combined sewage each year, and corresponded to a large municipal sewage plant with a treatment capacity about 20 000 t d(-1). PMID:17615887

Quan, Wei-Min; Zhang, Jin-Ping; Ping, Xian-Yin; Shi, Li-Yan; Li, Pei-Jun; Chen, Ya-Qu

2007-04-01

175

Distribution of Chromium, Manganese and Cobalt in the Bottom Sediment of Pahang River-Estuary, Pahang, Malaysia  

Directory of Open Access Journals (Sweden)

Full Text Available Bottom sediments from 62 stations at Pahang river-estuary were analyzed for the concentrations of Chromium (Cr, Manganese (Mn and Cobalt (Co. Heavy metal concentrations were analyzed by using an Inductively Coupled Plasma Mass Spectrometry (ICP-MS. The average dry weight concentrations of Cr, Mn and Co were 62.80±20.04, 416.21±127.41 and 7.93±3.25 ?g g-1, respectively. The observed concentrations of the studied metals were significantly higher near the estuary and declining as the sampling points were further away from the estuary. The Enrichment Factors (EFs were calculated and all elements showed metal contamination was predominantly of terrigenous in origin.

J.S. Goddard

2010-01-01

176

Effects of intratidal and tidal range variability on circulation and salinity structure in the Cape Fear River Estuary, North Carolina  

Science.gov (United States)

Tidal influences on circulation and the salinity structure are investigated in the largely unstudied Cape Fear River Estuary (CFRE), North Carolina, a partially mixed estuary along the southeast coast of the United States. During two different tidal conditions (high versus low tidal range) and when river flow was low, salinity and velocity data were collected over a semidiurnal tidal cycle in a 2.8 km long transect along the estuary axis. Water level data were recorded nearby. Mechanisms that influence salt transport characteristics are diagnosed from an analysis of the field data. Specifically, we investigated the relationship between tidal range and salinity through comparison of along-channel circulation characteristics, computed salt fluxes, and coefficients of vertical eddy diffusivity (Kz) based on a parameterization and on salt budget analysis. Findings indicate up-estuary tidally driven salt fluxes resulting from oscillatory salt transport are dominant near the pycnocline, while mean advective transport dominates near the bottom during both tidal range periods. Earlier research related to salt transport in estuaries with significant gravitational circulation suggests that up-estuary salt transport increases during low tidal ranges as a result of increased gravitational circulation. In the CFRE, in contrast, net (tidally averaged) near-bottom along-channel velocities are greater during higher tidal range conditions than during lower tidal range conditions. Findings indicate stronger tidal forcing and associated mixing contribute to greater near-bottom salinity gradients and, consequently, increased baroclinic circulation. Lower near-bottom salinities during the higher tidal range period are a result of a combination of increased vertical turbulent salt fluxes near the pycnocline and increased bottom-generated mixing.

Becker, May Ling; Luettich, Richard A.; Seim, Harvey

2009-04-01

177

The impact of river regulation and climate change on the barred estuary of the Oued Massa, southern Morocco  

Energy Technology Data Exchange (ETDEWEB)

The estuary of the Oued Massa, southern Morocco, has experienced alternating phases of tidal and lagoon conditions. Using field surveys, aerial photographs and rainfall-runoff records the dominant processes and recent evolution of the estuary are described. These data suggest that the character of the estuary has changed since the upstream impoundment of the river by the Youssef Ben Tachfine reservoir. The frequency of low-flows has been significantly increased by river regulation, as has the mean interval between flood events. Using reconstructed flow series it is speculated that lagoon conditions have become more common in the post-impoundment era than at any time since the 1920s. Although increases in winter precipitation projected by the global climate model HadCM2 for 2030-2049 imply a higher frequency of flood flows entering the reservoir in the future, the magnitude and frequency of such inflows are still within historic variability. Nonetheless, higher inflows may produce more frequent spills with concomitant bar breaching and termination of lagoon phases. Despite this, it is argued that the presence of the dam is ultimately of greater consequence to the functioning of the estuary-lagoon system than future precipitation changes over the region. (author)

Fox, H.R.; Moore, H.M. [University of Derby (United Kingdom). Division of Geography; Wilby, R.L. [University of Derby (United Kingdom). Division of Geography; National Center for Atmospheric Research, Boulder, CO (United States)

2001-07-01

178

Assessing the influence of sea-level rise on salt transport processes and estuarine circulation in the Changjiang River estuary  

Science.gov (United States)

Global sea-level rise has been greatly concerned with its impacts on material transports in estuaries, which threaten freshwater habitat. A numerical model ECOM-si was used to assess the influences on salt transport processes and estuarine circulation pattern in the Changjiang River estuary. Results show that the increments of salt transport are quite distinct between each channel as sea level rises. The analyses of residual salt transport show that the Stokes drift transport is the major mechanism for the up-estuary salt transport, while the seaward Eulerian transport is of the same order in magnitude. The flux of saltwater-spill-over (SSO) from the North Branch into the South Branch increases for stronger Stokes transport as sea level rises. The landward salt transport is strengthened in the North Channel and may further affect the upper reaches under strengthened tidal pumping and vertical shear transports for higher sea level. The overtopping flow affected by tidal pumping is the dominant mechanism for salt exchange between the North Passage and South Passage and further affected the South Channel. The increment of residual salt transport (a) and decomposed components in S3 relative to the base case. (b) Lagrangian transport; (c) Eulerian transport; (d) Stokes transport; (e) tidal pumping transport; (f) vertical shear transport. Negative value indicates increment of landward salt transport, and positive value indicates increment of seaward transport. Topography of the Changjiang River estuary, and the along-channel transects for later analyses are marked by the white lines

Qiu, C.

2013-12-01

179

Management of a tropical river: Impacts on the resilience of the Senegal river estuary  

OpenAIRE

Tropical rivers are under constant pressure and are subjected to flood control policy and planning. The Senegal River has been, for more than thirty years, under multiple types of management and planning. That has become recently more important because of significant hydro-climatic variability that has occurred during recent years. Higher levels of winter rainfall have resulted in frequent occurrence of flooding which guided Senegalese authorities to create an artificial opening on the sand o...

Kane, Coura; Kane, Alioune; Humbert, Joe?l

2014-01-01

180

Artificial radionuclides in sediments of the Don River Estuary and Azov Sea  

International Nuclear Information System (INIS)

The Don River Estuary-Azov Sea system is an extension of the shallow continental shelf area of the Black Sea. A large data set of artificial radionuclides in bottom sediments of the Azov Sea has been compiled in order to examine the storage and migration of radionuclides within this highly restricted inland sea and to estimate the annual dose received by individuals in the local population who regularly consume fish. In recent years (1997-1999), the radionuclide content of surface sediments has been: 137Cs?0.5-100 Bq/kg d.w. (mean=33.8±25.9 Bq/kg d.w., n=57), 90Sr=0.2-5.7 Bq/kg d.w. (mean=2.1±1.4 Bq/kg d.w., n=34) and 239,240Pu=0.31-0.51 Bq/kg d.w. (n=2). In general, 137Cs activities increase with distance from the mouth of the Don River and correlate negatively with sediment grain size (r2=0.77, n=21). The annual 137Cs-derived dose received by an individual through the trophic chain water-fish-humans (?10-6 Sv/yr) is well below regulatory recommended limits, indicating that current levels of radioactivity in the environment pose no threat to commercial fisheries operations for the bordering nations of Russia and Ukraine

181

Migratory Behavior and Survival of Juvenile Salmonids in the Lower Columbia River, Estuary, and Plume in 2010  

Energy Technology Data Exchange (ETDEWEB)

Uncertainty regarding the migratory behavior and survival of juvenile salmonids passing through the lower Columbia River and estuary after negotiating dams on the Federal Columbia River Power System (FCRPS) prompted the development and application of the Juvenile Salmon Acoustic Telemetry System (JSATS). The JSATS has been used to investigate the survival of juvenile salmonid smolts between Bonneville Dam (river kilometer (rkm) 236) and the mouth of the Columbia River annually since 2004. In 2010, a total of 12,214 juvenile salmonids were implanted with both a passive integrated transponder (PIT) and a JSATS acoustic transmitter. Using detection information from JSATS receiver arrays deployed on dams and in the river, estuary, and plume, the survival probability of yearling Chinook salmon and steelhead smolts tagged at John Day Dam was estimated form multiple reaches between rkm 153 and 8.3 during the spring. During summer, the survival probability of subyearling Chinook salmon was estimated for the same reaches. In addition, the influence of routes of passage (e.g., surface spill, deep spill, turbine, juvenile bypass system) through the lower three dams on the Columbia River (John Day, The Dalles, and Bonneville) on juvenile salmonid smolt survival probability from the dams to rkm 153 and then between rkm 153 and 8.3 was examined to increase understanding of the immediate and latent effects of dam passage on juvenile salmon survival. Similar to previous findings, survival probability was relatively high (>0.95) for most groups of juvenile salmonids from the Bonneville Dam tailrace to about rkm 50. Downstream of rkm 50 the survival probability of all species and run types we examined decreased markedly. Steelhead smolts suffered the highest mortality in this lower portion of the Columbia River estuary, with only an estimated 60% of the tagged fish surviving to the mouth of the river. In contrast, yearling and subyearling Chinook salmon smolts survived to the mouth of the river at higher rates, with estimated survival probabilities of 84% and 86%, respectively. The influence of route of passage at the lower three dams in the FCRPS on juvenile salmonid survival appeared to be relatively direct and immediate. Significant differences in estimated survival probabilities of juvenile salmonid smolts among groups with different dam passage experiences were often detected between the dams and rkm 153. In contrast, the influence of route of passage on survival to the mouth of the Columbia River was not apparent among the groups of tagged juvenile salmonids with different FCRPS passage experiences after they had already survived to a point about 80 km downstream of Bonneville Dam. Yearling Chinook salmon and steelhead smolts that migrated through the lower estuary in off-channel habitats took two to three times longer to travel through these lower reaches and their estimated survival probabilities were not significantly different from that of their cohorts which migrated in or near the navigation channel. A large proportion of the tagged juvenile salmonids migrating in or near the navigation channel in the lower estuary crossed from the south side of the estuary near Astoria, Oregon and passed through relatively shallow expansive sand flats (Taylor Sands) to the North Channel along the Washington shore of the estuary. This migratory behavior may contribute to the avian predation losses observed on for fish (2 to 12% of fish in this study).

McMichael, Geoffrey A.; Harnish, Ryan A.; Skalski, John R.; Deters, Katherine A.; Ham, Kenneth D.; Townsend, Richard L.; Titzler, P. Scott; Hughes, Michael S.; Kim, Jin A.; Trott, Donna M.

2011-09-01

182

Salmon Life Histories, Habitat, and Food Webs in the Columbia River Estuary: An Overview of Research Results, 2002-2006.  

Energy Technology Data Exchange (ETDEWEB)

From 2002 through 2006 we investigated historical and contemporary variations in juvenile Chinook salmon Oncorhynchus tshawytscha life histories, habitat associations, and food webs in the lower Columbia River estuary (mouth to rkm 101). At near-shore beach-seining sites in the estuary, Chinook salmon occurred during all months of the year, increasing in abundance from January through late spring or early summer and declining rapidly after July. Recently emerged fry dispersed throughout the estuary in early spring, and fry migrants were abundant in the estuary until April or May each year. Each spring, mean salmon size increased from the tidal freshwater zone to the estuary mouth; this trend may reflect estuarine growth and continued entry of smaller individuals from upriver. Most juvenile Chinook salmon in the mainstem estuary fed actively on adult insects and epibenthic amphipods Americorophium spp. Estimated growth rates of juvenile Chinook salmon derived from otolith analysis averaged 0.5 mm d-1, comparable to rates reported for juvenile salmon Oncorhynchus spp. in other Northwest estuaries. Estuarine salmon collections were composed of representatives from a diversity of evolutionarily significant units (ESUs) from the lower and upper Columbia Basin. Genetic stock groups in the estuary exhibited distinct seasonal and temporal abundance patterns, including a consistent peak in the Spring Creek Fall Chinook group in May, followed by a peak in the Western Cascades Fall Chinook group in July. The structure of acanthocephalan parasite assemblages in juvenile Chinook salmon from the tidal freshwater zone exhibited a consistent transition in June. This may have reflected changes in stock composition and associated habitat use and feeding histories. From March through July, subyearling Chinook salmon were among the most abundant species in all wetland habitat types (emergent, forested, and scrub/shrub) surveyed in the lower 100 km of the estuary. Salmon densities within wetland habitats fell to low levels by July, similar to the pattern observed at mainstem beach-seining sites and coincident with high water temperatures that approached or exceeded 19 C by mid-summer. Wetland habitats were used primarily by small subyearling Chinook salmon, with the smallest size ranges (i.e., rarely exceeding 70 mm by the end of the wetland rearing season) at scrub/shrub forested sites above rkm 50. Wetland sites of all types were utilized by a diversity of genetic stock groups, including less abundant groups such as Interior Summer/Fall Chinook.

Bottom, Daniel L.; Anderson, Greer; Baptisa, Antonio

2008-08-01

183

Resuspension and estuarine nutrient cycling: insights from the Neuse River Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available For at least the past several decades, North Carolina's Neuse River Estuary (NRE has been subject to water quality problems relating to increased eutrophication. Research studies initiated in the past several years have addressed the complex nutrient cycles in this system. Most of this research, however, is concerned with the nutrient processes of the water column and the passive diffusion processes of the benthic sedimentary environment. Resuspension of bottom sediments, by bioturbation, tides, or wind-generated waves, may have a significant effect on the flux of nutrients in an estuarine system These processes can result in the advective transport of sediment porewater, rich with nitrogen, phosphorus and carbon, into the water column. Thus, estimates of nutrient and carbon inputs from the sediments may be too low.

This study focused on the potential change in porewater and bottom water nutrient concentrations associated with measured resuspension events. Previous research used short-lived radionuclides and meteorological data to characterize the sediment dynamics of the benthic system of the estuary. These techniques in conjunction with the presented porewater inventories allowed evaluation of the depth to which sediments have been disturbed and the advective flux of nutrients to the water column. The largest removal episode occurred in the lower NRE as the result of a wind event and was estimated that the top 2.2 cm of sediment and corresponding porewater were removed. NH4+ advective flux (resuspended was 2 to 6 times greater than simply diffusion. Phosphate fluxes were estimated to be 15 times greater than the benthic diffusive flux. Bottom water conditions with elevated NH4+ and PO43? indicate that nutrients stored in the sediments continue to play an important role in overall water quality and this study suggests that the advective flux of nutrients to the water column is critical to understand estuarine nutrient cycling.

D. R. Corbett

2010-04-01

184

Resuspension and estuarine nutrient cycling: insights from the Neuse River Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available For at least the past several decades, North Carolina's Neuse River Estuary (NRE has been subject to water quality problems relating to increased eutrophication. Research initiated in the past several years have addressed the nutrient processes of the water column and the passive diffusion processes of the benthic sedimentary environment. Resuspension of bottom sediments, by bioturbation, tides, or winds, may also have a significant effect on the flux of nutrients in an estuarine system These processes can result in the advective transport of sediment porewater, rich with nitrogen, phosphorus and carbon, into the water column. Thus, estimates of nutrient and carbon inputs from the sediments may be too low.

This study focused on the potential change in bottom water nutrient concentrations associated with measured resuspension events. Previous research used short-lived radionuclides and meteorological data to characterize the sediment dynamics of the benthic system of the estuary. These techniques in conjunction with the presented porewater inventories allowed evaluation of the depth to which sediments have been disturbed and the advective flux of nutrients to the water column. The largest removal episode occurred in the lower NRE as the result of a wind event and was estimated that the top 2.2 cm of sediment and corresponding porewater were removed. NH4+ advective flux (resuspended was 2 to 6 times greater than simply diffusion. Phosphate fluxes were estimated to be 15 times greater than the benthic diffusive flux. Bottom water conditions with elevated NH4+ and PO43? indicate that nutrients stored in the sediments continue to play an important role in overall water quality and this study suggests that the advective flux of nutrients to the water column is critical to understand estuarine nutrient cycling.

D. R. Corbett

2010-10-01

185

Seasonal variations in the inorganic carbon system in the Pearl River (Zhujiang) estuary  

Science.gov (United States)

Seasonal variations in the inorganic carbon system in the Pearl River estuary are examined based on data from five surveys during the spring, summer, fall, and winter seasons. Both total dissolved inorganic carbon (DIC) and total alkalinity (TAlk) values in the freshwater end-members are high in the dry season (>2700 ?mol kg -1 for DIC and >2400 ?mol kg -1 for TAlk) and substantially lower in the wet season (DIC and TAlk were ˜1000 and 700 ?mol kg -1, respectively). Riverine DIC flux and drainage basin weathering rates, however, are significantly higher in the wet season (611×10 9 mol yr -1 and 13.6×10 5 mol km -2 yr -1) than in the dry season (237×10 9 mol yr -1 and 5.3×10 5 mol km -2 yr -1). In the estuarine mixing zone, DIC and TAlk are generally conservative at salinities >5, while in the low-salinity zone the carbonate system shows a much more complex distribution pattern. In the dry season, DIC and TAlk show a decreasing pattern with salinity, while they have an increasing pattern in the wet season. This complex behavior is mainly a result of mixing between tributaries with distinct and seasonally variable DIC and TAlk values. Distributions of inorganic carbon parameters, in particular pH and pCO 2, are however noticeably modified by local acid-generating biogeochemical processes in the upper estuary. Processes such as nitrification increase acidity during the dry season when freshwater discharge is low and NH 4+-rich pollutant discharge from the neighboring metropolitan areas is relatively high.

Guo, Xianghui; Cai, Wei-Jun; Zhai, Weidong; Dai, Minhan; Wang, Yongchen; Chen, Baoshan

2008-07-01

186

Distribution, biomass and production of Ceratonereis erythraeensis (Fauvel) and Ceratonereis keiskama (Day) at the Berg River Estuary, South Africa  

OpenAIRE

ENGLISH ABSTRACT: Population dynamics of the polychaetes Ceratonereis keiskama and C. erythraeensis were studied at the Berg River estuary, South Africa, from December 1987 to April 1989. There was marked size-related depth stratification of both species, with small worms being concentrated in the upper layer of the substratum and larger ones deeper down. Reproduction of both species occurred in summer. Three cohorts were distinguished in both populations. Recruitment of C. keiskama peaked in...

Kalejta, B.

2012-01-01

187

Diversity and Distribution of nirK-Harboring Denitrifying Bacteria in the Water Column in the Yellow River Estuary  

OpenAIRE

We investigated the diversity and community composition of denitrifying bacteria in surface water from the Yellow River estuary. Our results indicated that the diversity of the denitrifying community in freshwater based on the nirK gene was higher than that in seawater. Furthermore, phylogenetic analysis suggested that the bacteria community could be distributed into eight clusters (Clusters I to VIII). Redundancy analysis (RDA) revealed that community compositions were related to multiple en...

Li, Jing; Wei, Guangshan; Wang, Ningxin; Gao, Zheng

2014-01-01

188

Species diversity of the old genus Navicula Bory (Bacillariophyta) on intertidal sand-flats in the Nakdong River estuary, Korea  

OpenAIRE

Remarkable diversity of diatom taxa occurs in intertidal sand-flats of the Nakdong River estuary, one of the most dynamic and productive ecosystem in Korea. Benthic diatoms were collected from the sandy sediments to clarify the taxonomic accounts and distribution of the old genus Navicula, i.e., the naviculoid flora. Total 92 taxa belonging to Navicula sensu stricto and 22 genera separated from Navicula sensu lato are reported with brief descriptions and micrographs, and many species remain u...

Gyeong-je Joh

2013-01-01

189

Distribution and abundance of Cladocera (Branchiopoda) in the Paraíba do Sul River estuary, Rio de Janeiro, Brazil  

OpenAIRE

To characterize the cladoceran community of the Paraíba do Sul River estuary, located in the district of São João da Barra, Rio de Janeiro, Brazil, cladocerans were collected monthly in nine sampling stations from September 2002 until August 2003. Samples were obtained by subsurface tows using a plankton net with a 30 cm opening mouth and 70 micron mesh size, fitted with a mechanical flowmeter. Environmental parameters such as salinity and temperature were also obtained. Seventeen species ...

José Mauro Sterza; Luiz Loureiro Fernandes

2006-01-01

190

PAHs in sediment cores at main river estuaries of Chaohu Lake: implication for the change of local anthropogenic activities.  

Science.gov (United States)

In the present study, 28 polycyclic aromatic hydrocarbons (PAHs) were investigated in four sediment cores collected from the main river estuaries of Chaohu Lake, one of the severely polluted lakes in China. The results indicate that elevated concentrations of total PAHs (?28PAH) were found in the samples from the estuary of Nanfei River (ENF), considering BaP-based total toxicity equivalent (TEQ-BaP) and toxic unit (TU) results; there are potential adverse environmental implications. The total organic carbon (TOC) played an important role on the accumulation of PAHs at ENF and the estuary of Tongyang River (ETY). The predominant PAHs are high molecular weight (HMW) homologous for all samples; as a result, industrial wastewater from a steel company is expectedly the key source of PAHs in ENF, while coke consumption would be the important source of PAHs at other three sampling sites. Vertical distribution of PAHs in the sediment cores could be explained by the local social and economic activities. Furthermore, a minor variation of PAH composition in the sediment core could be justified by the stable structure of energy consumption in the Anhui Province. These results justify the need for further enhancement of industrial wastewater treatment and development of renewable energies which are the key factors on the control of PAH pollution in China. PMID:24946702

Ren, Chen; Wu, Yaketon; Zhang, Shuo; Wu, Liang-Liang; Liang, Xiao-Guo; Chen, Tian-Hu; Zhu, Cheng-Zhu; Sojinu, Samuel O; Wang, Ji-Zhong

2015-02-01

191

[Ecological niche breadth and niche overlap of dominant species of fish assemblage in Yangtze river estuary and its adjacent waters].  

Science.gov (United States)

Based on the fishery resources data from the bottom trawl surveys conducted on the R/V Beidou in the Yangtze River estuary and its adjacent waters in June, August and October of 2006, the index of relative importance (IRI) was measured to determine the dominant species of fish assemblage, and the niche indicators and their seasonal variations of the dominant species were analyzed. A total of 10 dominant species in the 3 survey cruises were recorded, which were divided into two groups by the Bray-curtis similarity clustering and non-metric multidimensional scaling (MDS) analysis, with a significant seasonal variation of niche breadth and niche overlap. One group included Engraulis japonicus, Champsodon capensis, and Acropoma japonicum, whose niche breadth and niche overlap were larger in summer than in autumn, with a migration from the Yangtze River estuary and its adjacent waters to outer deeper waters, while the other group included Trichiurus haumela, Chaeturichthys stigmatias, Apogon lineatus, Larimichthys polyactis, Psenopsis anomala, Argyrosomus argentatus, and Benthosema pterotum, whose niche breadth and niche overlap were larger in autumn than in summer, with a reverse migration from southern Yellow Sea and northern East China Sea to the Yangtze River estuary and its adjacent waters. The different migration direction of the two groups was related to their ecological habits and environmental factors. PMID:24380359

Li, Xian-sen; Yu, Zhen-hai; Sun, Shan; Jin, Xian-shi

2013-08-01

192

[Spatial distribution characteristics of Fe and Mn contents in the new-born coastal marshes in the Yellow River estuary].  

Science.gov (United States)

The spatial distribution characteristics of Fe and Mn contents in soils of nine different vegetation communities, located in the new-born marshes of the northern Yellow River estuary, were studied in May 2009. The results showed that the horizontal distributions of Fe and Mn contents showed an increasing tendency from Sparganiaceae-Potentilla supina marsh to bare flat. The vertical distribution characteristics of Fe and Mn contents in different marsh soils fluctuated significantly with the vegetation succession. The soil parent materials determined the Fe, Mn contents in the new-born marshes, and seawater, vegetations and soil fine particle also had important influences on their contents. Further analysis showed that Fe contents had significant positive correlation with Mn contents (P River estuary, the mangrove swamps and inland lake wetland. The Mn contents ranged from 305.87 mg x kg(-1) to 711.39 mg x kg(-1) and the average was 451.09 mg x kg(-1), which was lower than the Mn contents in the Loess Plateau and the China soil background value. Hydrology and Water Resources Survey Bureau of the Yellow River Estuary, Dongying 257091, China) PMID:24455953

Sun, Wen-Guang; Gan, Zhuo-Ting; Sun, Zhi-Gao; Li, Li-Li; Sun, Jing-Kuan; Sun, Wan-Long; Mou, Xiao-Jie; Wang, Ling-Ling

2013-11-01

193

Weight-of-evidence approach in assessment of ecotoxicological risks of acid sulphate soils in the Baltic Sea river estuaries.  

Science.gov (United States)

Acidity and leaching of metals from acid sulphate soils (ASSs) impair the water quality of receiving surface waters. The largest ASS areas in Europe are found in the coasts of the northern Baltic Sea. We used weight-of-evidence (WoE) approach to assess potential risks in 14 estuary sites affected by ASS in the Gulf of Finland, northern Baltic Sea. The assessment was based on exposure and effect profiles utilizing sediment and water metal concentrations and concurrent pH variation, sediment toxicity tests using the luminescent bacterium Vibrio fischeri and the midge Chironomus riparius, and the ecological status of benthic macroinvertebrate communities. Sediment metal concentrations were compared to national sediment quality criteria/guidelines, and water metal concentrations to environmental quality standards (EQSs). Hazard quotients (HQs) were established for maximum aluminium, cadmium and zinc concentrations at low pH based on applicable US EPA toxicity database. Sediment metal concentrations were clearly elevated in most of the studied estuaries. The EQS of cadmium (0.1 ?g/l) was exceeded in 3 estuaries out of 14. The pH-minima were below the national threshold value (5.5) between good and satisfactory water quality in 10 estuaries. V. fischeri bioluminescence indicated toxicity of the sediments but toxic response was not observed in the C. riparius emergence test. Benthic invertebrate communities were deteriorated in 6 out of 14 sites based on the benthic invertebrate quality index. The overall ecotoxicological risk was assessed as low in five, moderate in three and high in five of the estuary sites. The risk assessment utilizing the WoE approach indicated that harmful effects of ASSs are likely to occur in the Baltic Sea river estuaries located at the ASS hotspot area. PMID:25506908

Wallin, Jaana; Karjalainen, Anna K; Schultz, Eija; Järvistö, Johanna; Leppänen, Matti; Vuori, Kari-Matti

2015-03-01

194

A network model shows the importance of coupled processes in the microbial N cycle in the Cape Fear River Estuary  

Science.gov (United States)

Estuaries serve important ecological and economic functions including habitat provision and the removal of nutrients. Eutrophication can overwhelm the nutrient removal capacity of estuaries and poses a widely recognized threat to the health and function of these ecosystems. Denitrification and anaerobic ammonium oxidation (anammox) are microbial processes responsible for the removal of fixed nitrogen and diminish the effects of eutrophication. Both of these microbial removal processes can be influenced by direct inputs of dissolved inorganic nitrogen substrates or supported by microbial interactions with other nitrogen transforming pathways such as nitrification and dissimilatory nitrate reduction to ammonium (DNRA). The coupling of nitrogen removal pathways to other transformation pathways facilitates the removal of some forms of inorganic nitrogen; however, differentiating between direct and coupled nitrogen removal is difficult. Network modeling provides a tool to examine interactions among microbial nitrogen cycling processes and to determine the within-system history of nitrogen involved in denitrification and anammox. To examine the coupling of nitrogen cycling processes, we built a nitrogen budget mass balance network model in two adjacent 1 cm3 sections of bottom water and sediment in the oligohaline portion of the Cape Fear River Estuary, NC, USA. Pathway, flow, and environ ecological network analyses were conducted to characterize the organization of nitrogen flow in the estuary and to estimate the coupling of nitrification to denitrification and of nitrification and DNRA to anammox. Centrality analysis indicated NH4+ is the most important form of nitrogen involved in removal processes. The model analysis further suggested that direct denitrification and coupled nitrification-denitrification had similar contributions to nitrogen removal while direct anammox was dominant to coupled forms of anammox. Finally, results also indicated that partial nitrification-anammox may play an important role in anammox nitrogen removal in the Cape Fear River Estuary.

Hines, David E.; Lisa, Jessica A.; Song, Bongkeun; Tobias, Craig R.; Borrett, Stuart R.

2012-06-01

195

Freshwater fluxes in the Berau estuary and shelf during peak river discharge conditions  

Science.gov (United States)

The Berau Continental Shelf is located close to the Equator in the Indonesian Archipelago, hosting a complex of coral reefs and atolls along its oceanic edge. It is important to understand how river water, sediments, and other materials derived from land are carried to reefs by physical mechanisms, since they can have beneficial as well as negative effects. Furthermore, at several of the atolls unique seagrass meadows are found. These ecosystems need exclusively marine conditions and are intolerant to freshwater. In the Berau Continental shelf much uncertainty remains about how much of the riverine water reaches the reefs and the atolls. In a recent study we showed that tides are the main contributor to the spreading of freshwater at the Berau Continental Shelf under average conditions: relatively small river discharge, weak winds, strong tides. A three-dimensional model (ECOMSED) was calibrated and validated with observational data collected in the context of the East Kalimantan Research Programme. Data-model comparison showed high skill scores and small systematic errors. Model analysis has shown that tides effect the plume by causing vertical mixing, by stratifying the plume due to tidal straining and by transporting freshwater. This causes the depth-integrated freshwater transport to be mainly north-eastward, toward the barrier reef. Under these average conditions freshwater does not reach the atolls. The main aim of this study is to study plume dynamics at the Berau shelf during peak river discharge and peak wind conditions. Because the Berau delta is urbanizing rapidly increasing peak river discharges and sediment loads are expected. In addition, although the yearly mean wind is small, peak wind events concurrent with peak floods might push the stratified top layer of the water column towards the reefs and atolls. Using the results of a hydrological model we estimated realistic peak values of the river discharge based on scenarios for the economical development of the Berau delta. These peak discharges are used as input for the 3D hydrodynamic model. This calibrated ECOMSED model is used to study the transport of freshwater from Berau estuary to the shelf in extreme conditions. We will analyze the different pathways through the estuarine channel network and the pathways across the shelf as a function of tides, wind and peak discharge. Furthermore, we will discuss the plume dynamics as a function of hydrodynamic forcing and compare it to other systems in the world.

Van Der Vegt, M.; Tarya, A.; Hoitink, A.

2011-12-01

196

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

197

Four arguments why so many alien species settle into estuaries, with special reference to the German river Elbe  

Science.gov (United States)

In one of the largest European rivers, the Elbe, from its source in the Czech Republic to the German North Sea, 31 alien macrozoobenthic species have been recorded in total. Most of these species have been introduced by shipping activities. With a total number of 21 species, many of the established aliens occur—partly exclusively—in the brackish area of the Elbe estuary. In order to explain this observed settlement characteristic, four main arguments come into consideration: (1) estuaries with intensive international shipping have a higher potential infection rate than other aquatic zones; (2) brackish water species have, due to specific physiological characteristics, a better chance of being transported alive than euhaline or freshwater species and they also probably have a higher perennation and establishment potential after release; (3) brackish waters have the greatest natural ‘indigenous species minimum’, so that more alien species can potentially establish; and (4) salt-tolerant limnetic alien species introduced into inland water reached the coast at first in the estuaries. It seems that the combination of brackish water with its unsaturated ecological niches and intensive international ship traffic has the highest potential infection rate for aquatic systems with alien macrozoobenthic species. And, estuaries are subjected to a two-sided invasion pressure by alien species, via the ocean (mainly shipping) and via inland waters (mainly shipping canal construction). The identification of such patterns is an important prerequisite for the development of a forward-looking alien monitoring and management strategy.

Nehring, Stefan

2006-05-01

198

Geographic specificity of Aroclor 1268 in bottlenose dolphins (Tursiops truncatus) frequenting the Turtle/Brunswick River Estuary, Georgia (USA)  

International Nuclear Information System (INIS)

Coastal marine resources are at risk from anthropogenic contaminants, including legacy persistent organic pollutants (POPs) with half-lives of decades or more. To determine if polychlorinated biphenyl (PCB) signatures can be used to distinguish among local populations of inshore bottlenose dolphins (Tursiops truncatus) along the southeastern U.S. coast, blubber from free-ranging and stranded animals were collected along the Georgia coast in 2004 and analyzed for PCB congeners using gas chromatography with electron capture and negative chemical ionization mass spectrometric detection (GC-ECD and GC-NCI-MS). Mean total PCB concentrations (77 ± 34 ?g/g lipid) were more than 10 fold higher and congener distributions were highly enriched in Cl7-Cl10 homologs in free-ranging animals from the Turtle/Brunswick River estuary (TBRE) compared with strandings samples from Savannah area estuaries 90 km to the north. Using principal components analysis (PCA), the Aroclor 1268 signature associated with TBRE animals was distinct from that observed in Savannah area animals, and also from those in animals biopsied in other southeastern U.S estuaries. Moreover, PCB signatures in dolphin blubber closely resembled those in local preferred prey fish species, strengthening the hypothesis that inshore T. truncatus populations exhibit long-term fidelity to specific estuaries and making them excellent sentinels for assessing the impact of stressors on coastal ecosystem mpact of stressors on coastal ecosystem health

199

Geographic specificity of Aroclor 1268 in bottlenose dolphins (Tursiops truncatus) frequenting the Turtle/Brunswick River Estuary, Georgia (USA)  

Energy Technology Data Exchange (ETDEWEB)

Coastal marine resources are at risk from anthropogenic contaminants, including legacy persistent organic pollutants (POPs) with half-lives of decades or more. To determine if polychlorinated biphenyl (PCB) signatures can be used to distinguish among local populations of inshore bottlenose dolphins (Tursiops truncatus) along the southeastern U.S. coast, blubber from free-ranging and stranded animals were collected along the Georgia coast in 2004 and analyzed for PCB congeners using gas chromatography with electron capture and negative chemical ionization mass spectrometric detection (GC-ECD and GC-NCI-MS). Mean total PCB concentrations (77 {+-} 34 {mu}g/g lipid) were more than 10 fold higher and congener distributions were highly enriched in Cl{sub 7}-Cl{sub 10} homologs in free-ranging animals from the Turtle/Brunswick River estuary (TBRE) compared with strandings samples from Savannah area estuaries 90 km to the north. Using principal components analysis (PCA), the Aroclor 1268 signature associated with TBRE animals was distinct from that observed in Savannah area animals, and also from those in animals biopsied in other southeastern U.S estuaries. Moreover, PCB signatures in dolphin blubber closely resembled those in local preferred prey fish species, strengthening the hypothesis that inshore T. truncatus populations exhibit long-term fidelity to specific estuaries and making them excellent sentinels for assessing the impact of stressors on coastal ecosystem health.

Pulster, Erin L. [Marine Sciences Department, Savannah State University, Savannah, Georgia, 31404 (United States); Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, Georgia, 31411 (United States)], E-mail: epulster@mote.org; Maruya, Keith A. [Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, Georgia, 31411 (United States)

2008-04-15

200

The fish community of the Berg River estuary and an assessment of the likely effects of reduced freshwater inflows  

Directory of Open Access Journals (Sweden)

Full Text Available ENGLISH ABSTRACT: Data concerning the species composition, abundance and distribution of fishes in habiting the Berg River estuary are presented and used to assess the value of the estuary to fish, and the likely effects of reduced freshwater in flows. A total of 31 species was recorded, eight of which were classified as estuarine residents, 11 as marine estuarine-opportunist, six as marine stragglers and six were freshwater species. Liza richardsonii, an opportunist, was the most abundant (54% N and widely distributed species encountered during the winter and summer seine-net surveys. Three other species (all residents contributed more than 10% of the total catch; Atherina breviceps and Caffrogobius nudiceps occurring most abundantly in the lower estuary, and Gilchristella estuaria in the middle estuary. The low number of species compared with estuaries in other regions of the South African coast reflect a well-established marine biogeographical trend. The higher proportions of resident species, entirely dependent species and partially dependent species suggest, however, that west coast estuaries may be more important to the fish that inhabit them than are estuaries in other regions. It is concluded that the fish community of the estuary is already suffering the effects of habitat degradation and that further reducation in freshwater inflows are not desirable.********AFRIKAANSE OPSOMMING: Data betreffende die spesiessamestelling, talrykheid en verspreiding van visse wat die Bergriviermond bewoon, word aangebied en gebruik in 'n raming van die waarde van die mond vir die bewonende visse, en die moontlike gevolge van verminderde varswaterinvloei. 'n Totaal van 31 spesies is aangeteken, agt waarvan geklassiliseer is as mondinwoners, 11 as mariene trekvisse, ses as mariene swerwers en ses as varswateisoorte. Liza richardsonii, 'n trekvis, was die volopste (54%N en mees wydverspreide spesies wat teëgekom is gedurende die winter- en someropnames. Die ander spesies (almal inwoners het meer as 10% bygedra tot die totale vangs, met Atherina breviceps en Caffrogobius nudiceps wat volopste in die laer-, en Gilchristella estuaria in die middelgedeeltes van die strandmeer, voorkom. Die klein aantal spesies weerspieël 'n goed vasgelegde mariene biogeografiese neiging. Die groter proporsie van inwonerspesies, total afhanklike en gedeeltelik afhanklike spesies suggereer egter dat Weskusriviermonde belangrikerr mag wees vir die visse wat hulle bewoon as riviermonde in ander streke. Die gevolgtrekking word gemaak dat die visgemeenskap van die riviermonde reeds onder die gevolge van habitatvernieling ly en dat verdere verminderings in varswater invloei onwenslik is.

B.A. Bennett

2012-01-01

201

Estuarine Habitats for Juvenile Salmon in the Tidally-Influenced Lower Columbia River and Estuary : Reporting Period September 15, 2008 through May 31, 2009.  

Energy Technology Data Exchange (ETDEWEB)

This work focuses on the numerical modeling of Columbia River estuarine circulation and associated modeling-supported analyses conducted as an integral part of a multi-disciplinary and multi-institutional effort led by NOAA's Northwest Fisheries Science Center. The overall effort is aimed at: (1) retrospective analyses to reconstruct historic bathymetric features and assess effects of climate and river flow on the extent and distribution of shallow water, wetland and tidal-floodplain habitats; (2) computer simulations using a 3-dimensional numerical model to evaluate the sensitivity of salmon rearing opportunities to various historical modifications affecting the estuary (including channel changes, flow regulation, and diking of tidal wetlands and floodplains); (3) observational studies of present and historic food web sources supporting selected life histories of juvenile salmon as determined by stable isotope, microchemistry, and parasitology techniques; and (4) experimental studies in Grays River in collaboration with Columbia River Estuary Study Taskforce (CREST) and the Columbia Land Trust (CLT) to assess effects of multiple tidal wetland restoration projects on various life histories of juvenile salmon and to compare responses to observed habitat-use patterns in the mainstem estuary. From the above observations, experiments, and additional modeling simulations, the effort will also (5) examine effects of alternative flow-management and habitat-restoration scenarios on habitat opportunity and the estuary's productive capacity for juvenile salmon. The underlying modeling system is part of the SATURN1coastal-margin observatory [1]. SATURN relies on 3D numerical models [2, 3] to systematically simulate and understand baroclinic circulation in the Columbia River estuary-plume-shelf system [4-7] (Fig. 1). Multi-year simulation databases of circulation are produced as an integral part of SATURN, and have multiple applications in understanding estuary/plume variability, the role of the estuary and plume on salmon survival, and functional changes in the estuary-plume system in response to climate and human activities.

Baptista, António M. [Oregon Health & Science University, Science and Technology Center for Coastal Margin Observation and Prediction

2009-08-02

202

Distributions and sources of polycyclic aromatic hydrocarbons in surface sediments from the Cross River estuary, S.E. Niger Delta, Nigeria.  

Science.gov (United States)

Polycyclic aromatic hydrocarbon (PAH) analyses of surface sediments from the Cross River estuary by gas chromatography-mass spectrometry indicated natural diagenetically derived PAHs in the upper estuary, with minor and variable amounts of petrogenic and combustion-derived PAHs from human activities (lower estuary). The occurrence of significant amounts of perylene (average 23% of all PAHs) with the diagenetic natural PAHs in the middle estuary bordered by mangrove forests supports its origin from terrestrial organic matter. The natural PAHs represent the highest percentage (average 76%) of the total PAHs in this tropical environment. The traditional geochemical parameters, including the petrogenic PAHs, confirmed trace petroleum contamination in the estuary. Specific PAH ratios such as Fl/Py and Fl/(Fl+Py) also support this source contribution. PMID:21472387

Ekpo, Bassey Offiong; Oyo-Ita, Orok E; Oros, Daniel R; Simoneit, Bernd R T

2012-01-01

203

Zooplankton community analysis in the Changjiang River estuary by single-gene-targeted metagenomics  

Science.gov (United States)

DNA barcoding provides accurate identification of zooplankton species through all life stages. Single-gene-targeted metagenomic analysis based on DNA barcode databases can facilitate longterm monitoring of zooplankton communities. With the help of the available zooplankton databases, the zooplankton community of the Changjiang (Yangtze) River estuary was studied using a single-gene-targeted metagenomic method to estimate the species richness of this community. A total of 856 mitochondrial cytochrome oxidase subunit 1 (cox1) gene sequences were determined. The environmental barcodes were clustered into 70 molecular operational taxonomic units (MOTUs). Forty-two MOTUs matched barcoded marine organisms with more than 90% similarity and were assigned to either the species (similarity>96%) or genus level (similarity<96%). Sibling species could also be distinguished. Many species that were overlooked by morphological methods were identified by molecular methods, especially gelatinous zooplankton and merozooplankton that were likely sampled at different life history phases. Zooplankton community structures differed significantly among all of the samples. The MOTU spatial distributions were influenced by the ecological habits of the corresponding species. In conclusion, single-gene-targeted metagenomic analysis is a useful tool for zooplankton studies, with which specimens from all life history stages can be identified quickly and effectively with a comprehensive database.

Cheng, Fangping; Wang, Minxiao; Li, Chaolun; Sun, Song

2014-07-01

204

Dissolved Fe(II) in a river-estuary system rich in dissolved organic matter  

Science.gov (United States)

Reduced iron, Fe(II), accounts for a significant fraction of dissolved Fe across many natural surface waters despite its rapid oxidation under oxic conditions. Here we investigate the temporal and spatial variation in dissolved Fe redox state in a high dissolved organic matter (DOM) estuarine system, the River Beaulieu. We couple manual sample collection with the deployment of an autonomous in situ analyser, designed to simultaneously measure dissolved Fe(II) and total dissolved Fe, in order to investigate processes operating on the diurnal timescale and to evaluate the performance of the analyser in a high DOM environment. Concentrations of dissolved Fe available to the ligand ferrozine are elevated throughout the estuary (up to 21 ?M in freshwater) and notably higher than those previously reported likely due to seasonal variation. Fe(II) is observed to account for a large, varying fraction of the dissolved Fe available to ferrozine (25.5 ± 12.5%) and this fraction decreases with increasing salinity. We demonstrate that the very high DOM concentration in this environment and association of this DOM with dissolved Fe, prevents the accurate measurement of dissolved Fe concentrations in situ using a sensor reliant on rapid competitive ligand exchange.

Hopwood, Mark J.; Statham, Peter J.; Milani, Ambra

2014-12-01

205

Diagenetic alterations of amino acids and organic matter in the upper Pearl River Estuary surface sediments  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this study was to investigate the diagenetic alteration of sediment organic matter (OM in the upper Pearl River Estuary. Sediment analyses were conducted for three size fractions of OM, including coarse particulate OM (CPOM, fine particulate OM (FPOM, and ultrafiltered dissolved OM (UDOM. Results showed that the highest and lowest carbon (C: nitrogen (N ratios were in CPOM and UDOM, respectively, indicating that CPOM was relatively enriched in organic C. The highest average total N content in the FPOM fraction showed that FPOM was enriched in N-containing molecules. Our study showed that the "size-reactivity continuum" model was applicable to sediment particulate and dissolved OM. Distributions of amino acids and their D-isomers among the sediment fractions indicated that the amino acid-based diagenetic index, C:N ratio, and percentage of total N represented by total hydrolysable amino acids could be used as diagenetic indicators. Furthermore, the diagenetic state of sediment OM could also be characterized by C- and N-normalized yields of total D-amino acids, and C- and N-normalized yields of D-alanine, D-glutamic acid, and D-serine.

J. Zhang

2012-01-01

206

Dynamics of arsenic in salt marsh sediments from Dongtan wetland of the Yangtze River Estuary, China.  

Science.gov (United States)

The mobility and transformation of arsenic (As) in salt marsh sediments were investigated in Dongtan wetland of the Yangtze River estuary, China. As in surface water, pore water and the rhizosphere sediments were quantified. The microcosm incubation experiments were conducted during the flooding of the sediments to examine As dynamics that occurred during changing redox conditions. The concentrations of dissolved As in pore water (0.04-0.95 micromol/L) were significantly greater than that in surface water (0.03-0.06 micromol/L). Under anoxic conditions, the reactive As could be initially mobilized by the reductive dissolution of Fe(III) (hydr)oxides. Subsequently, most of the dissolved As was likely to be associated with secondary iron (hydr)oxide phases and remained in solid phases. The seasonal variability of acid volatile sulfide concentrations suggest the anoxic conditions are enhanced during summer by Spartina alterniflora compared to Phragmites australis and Scirpus mariqueter, causing a notable increase in As mobility. Generally, there was a typical variation in redox conditions with season in salt marsh sediments of Dongtan wetland, in which the dynamics of As mobility and transformation possibly were controlled by iron, and all of this could be significantly influenced by the rapid spread of S. alterniflora. PMID:23534207

Wang, Yongjie; Zhou, Limin; Zheng, Xiangmin; Qian, Peng; Wu, Yonghong

2012-01-01

207

Body condition and gametogenic cycle of Galatea paradoxa (Mollusca: Bivalvia) in the Volta River estuary, Ghana  

Science.gov (United States)

The reproductive cycle of Galatea paradoxa which is the basis for an artisanal fishery in the Volta River estuary, Ghana, was studied using condition indices and histological methods from March 2008 to July 2009. The cycle is annual with a single spawning event between June and October. Gametogenesis starts in November progressing steadily to a peak in June-July when spawning begins until October when the animal is spent. The condition indices (shell-free wet weight/total wet weight, ash-free dry weight/shell weight and gonad wet weight/shell weight) showed a clear relationship with the gametogenic stage rising from a minimum at stage (I) start of gametogenesis, to their highest values at stages (IIIA) ripe and (IIIB) start of spawning before declining significantly to stage (IV) spent.It is suggested that condition index may prove a valuable technique in fishery management to recognise the reproductive stages of G. paradoxa as it is less expensive and time consuming than histological techniques in addition to being easier to teach to non-specialists. The data presented in this study provide information on the timing of spawning events for G. paradoxa, which is necessary for developing sustainable management strategies and selection of broodstock for aquaculture.

Adjei-Boateng, D.; Wilson, J. G.

2013-11-01

208

The hydrokinetic power resource in a tidal estuary: The Kennebec River of the central Maine coast  

Energy Technology Data Exchange (ETDEWEB)

Power levels available from the kinetic energy of tidal flows can be significant in coastal or estuarine regions with relatively modest tidal ranges. For example, the central Maine coast, where the mean semi-diurnal tidal range is about 3 m, includes several river estuaries with narrow interconnecting passages where tidal currents exceed 2 m s{sup -1}. A numerical circulation model applied to this region shows that the vigorous tidal flows lead to available power peaks exceeding 3 kW per square meter of turbine aperture in several sites during a spring tide. At one promising location, the peak power density is 6.5 kW/m{sup 2} near the surface and the energy capacity in a 500 m{sup 2} section under mean tidal conditions is about 2700 MWh per year, sufficient to meet the average consumption needs of about 150 homes connected to an electrical grid capable of accepting the tidal power pulses and blending them with traditional sources. (author)

Brooks, David A. [Department of Oceanography, Texas A and M University, College Station, TX 77840 (United States)

2011-05-15

209

Methane and nitrous oxide fluxes in the polluted Adyar River and estuary, SE India  

International Nuclear Information System (INIS)

We measured dissolved N2O, CH4, O2, NH4+, NO3- and NO2- on 7 transects along the polluted Adyar River-estuary, SE India and estimated N2O and CH4 emissions using a gas exchange relation and a floating chamber. High NO2- implied some nitrification of a large anthropogenic NH4+ pool. In the lower catchment CH4 was maximal (6.3 ± 4.3 x 104 nM), exceeding the ebullition threshold, whereas strong undersaturation of N2O and O2 implied intense denitrification. Emissions fluxes for the whole Adyar system ?2.5 x 108 g CH4 yr-1 and ?2.4 x 106 g N2O yr-1 estimated with a gas exchange relation and ?2 x 109 g CH4 yr-1 derived with a floating chamber illustrate the importance of CH4 ebullition. An equivalent CO2 flux ?1-10 x 1010 g yr-1 derived using global warming potentials is equivalent to total Chennai motor vehicle CO2 emissions in one month. Studies such as this may inform more effective waste management and future compliance with international emissions agreements

210

Controls on oxygen dynamics in a riverine salt-wedge estuary – a three-dimensional model of the Yarra River estuary, Australia  

Directory of Open Access Journals (Sweden)

Full Text Available Oxygen depletion in estuarine waters is an important factor governing water quality and ecological health. A complex and dynamic balance of physical and biogeochemical factors drive the extent and persistence of hypoxia and anoxia making it difficult to predict. An increased understanding of the effect of changing flow regimes and temperature on patterns of estuarine oxygen depletion is required to support ongoing management. Coupled physical and biogeochemical models have been applied to study the interaction of physical processes and seasonal hypoxia, however, application to riverine estuaries with tight curvature and more sporadic periods of oxygen depletion is rare. In this study we apply a finite volume 3-D hydrodynamic-biogeochemical model (TUFLOW-FV–FABM to the Yarra River estuary, Australia, in order to predict the extent of salt-wedge intrusion and consequent patterns of oxygen depletion. The predictive capacity of the model was evaluated using a series of model verification metrics and the results evaluated to determine the dominant mechanisms affecting salt-wedge position and the extent and persistence of anoxia and hypoxia. Measures of model fit indicated that the model reasonably captured the strength of stratification and the position and extent of the salt wedge (r2 ~ 0.74. The extent of the salt wedge intrusion was controlled by riverine flow and the strength of stratification or mixing dominated by topographical features corresponding to areas of tight curvature ("horseshoe" bends. The model predicted that the extent of anoxic waters generally mimicked the extent of the salt wedge (r2 ~ 0.65 increasing during periods of low flow and reduced following episodic high flow events. The results showed two sporadically isolated "hot spots" of anoxia, the first downstream of the horseshoe bend and the second downstream of a sill. Simulated oxygen concentrations indicated that whilst a threshold salt wedge intrusion was a requirement of oxygen depletion, temperature was critical in determining the extent of hypoxia and anoxia in the estuary. These findings highlight the importance of how seasonal changes in flow events and environmental flow management can impact on estuarine oxygen depletion in a warming climate. This study provides an improved understanding of the controls on hypoxia and anoxia in riverine estuaries, which is essential to support improved prediction of nutrient dynamics and ecological heath.

L. C. Bruce

2013-07-01

211

Avian ecological risk potential in an urbanized estuary: Lower Hackensack River, New Jersey, USA.  

Science.gov (United States)

As part of a comprehensive ecological risk assessment on a broad range of species, the potential for adverse effects in birds was evaluated at a chromate ore processing residue disposal site, Study Area 7, located at the confluence of the Lower Hackensack River, Passaic River, and Upper Newark Bay. Although detection of elevated concentrations of total chromium in sediment prompted the study, it was also necessary to consider potential risks related to other chemicals present in elevated concentrations due to widespread anthropogenic activities in Upper Newark Bay and its watershed. U.S. Army Corps of Engineers' TrophicTrace software was used to predict exposure to avian receptors using measured concentrations of chemicals in sediment, measured concentrations of chemicals in benthic invertebrates, and measured site physicochemical parameters. The TrophicTrace model was improved as part of the Study Area 7 ecological risk assessment to account for (1) incidental ingestion of sediment by dabbling and diving birds, (2) area use factors for spatial overlap of wide-ranging fish species and piscivorous birds, (3) spatially-explicit utilization of the site by birds with a variety of foraging strategies, and (4) temporal patterns of site utilization by migratory species. The ecological risk assessment demonstrated that chromium in sediment does not pose unacceptable hazards to avian receptors. Potentially unacceptable hazards were indicated for several organic chemicals (i.e., pesticides, polychlorinated biphenyls, and dioxins/furans), with hazard quotients highest for Upper Newark Bay reference conditions, reflecting potential widespread chemical impacts to the estuary. The modifications to TrophicTrace conducted for this assessment may be prudent and applicable for improving the accuracy and realism of other assessments involving avian receptors exposed to chemicals via contaminated sediment and transfer through the food web. PMID:19004475

Conder, Jason M; Sorensen, Mary T; Leitman, Paige; Martello, Linda B; Wenning, Richard J

2009-01-15

212

Anthropogenic effects on greenhouse gas (CH4 and N2O) emissions in the Guadalete River Estuary (SW Spain).  

Science.gov (United States)

Coastal areas are subject to a great anthropogenic pressure because more than half of the world's population lives in its vicinity causing organic matter inputs, which intensifies greenhouse gas emissions into the atmosphere. Dissolved concentrations of CH4 and N2O have been measured seasonally during 2013 in the Guadalete River Estuary, which flows into the Cadiz Bay (southwestern Spanish coast). It has been intensely contaminated since 1970. Currently it receives wastewater effluents from cities and direct discharges from nearby agriculture crop. Eight sampling stations have been established along 18 km of the estuary. CH4 and N2O were measured using a gas chromatograph connected to an equilibration system. Additional parameters such as organic matter, dissolved oxygen, nutrients and chlorophyll were determinate as well, in order to understand the relationship between physicochemical and biological processes. Gas concentrations increased from the River mouth toward the inner part, closer to the wastewater treatment plant discharge. Values varied widely within 21.8 and 3483.4 nM for CH4 and between 9.7 and 147.6 nM for N2O. Greenhouse gas seasonal variations were large influenced by the precipitation regime, masking the temperature influence. The Guadatete Estuary acted as a greenhouse gas source along the year, with mean fluxes of 495.7 ?mol m(-2)d(-1) and 92.8 ?mol m(-2)d(-1) for CH4 and N2O, respectively. PMID:24993513

Burgos, M; Sierra, A; Ortega, T; Forja, J M

2015-01-15

213

Long-term changes in sedimentary diatom assemblages and their environmental implications in the Changjiang (Yangtze) River estuary, China  

Science.gov (United States)

Long-term data on diatom assemblages in a sediment core (60 cm) obtained from the Changjiang (Yangtze) River estuary were analyzed in order to assess the environmental changes that took place in the approximately 38 years (as determined by 210Pb measurements), i.e., between 1974 and 2012, of sediment accumulation. From the sediment core, 62 diatom taxa and genera were identified. The diatom biomass in the core generally increased beginning in the mid-1990s (core depth: 35 cm), accompanied by a shift in the dominant species from Podosira stelliger and two species of Cyclotella ( C. stylorum and C. striata) to Paralia sulcata, three species of Thalassiosira ( T. eccentria, T. oestrupii, and T. excentrica), Actinoptychus undulates, and Thalassionema nitzschioides. The changes in both species diversity and abundance suggested that since the 1980s the estuary has undergone extensive eutrophication. This conclusion was supported by the increased proportion of planktonic species, another indicator of high nutrients inputs, in the Changjiang River estuary.

Cheng, Fangjin; Yu, Zhiming; Song, Xiuxian

2014-01-01

214

A choice experiment application to estimate willingness to pay for controlling excessive recreational fishing demand at the Sundays River Estuary, South Africa  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english The Sundays River Estuary, situated in the Eastern Cape, South Africa, has excessive recreational demand for estuarine services, specifically recreational fishing. The estuary has been over-fished, putting its sustainability at risk. Various management interventions may be required in order to save [...] it, but how is this to be done without reducing welfare? The main aim of this paper is twofold: first, to assess and comprehend the economic value of the estuarine resources at stake; and, second, to propose policy measures to redress the situation (excessive demand, specifically recreational fishing). An application of a choice experiment reveals that the physical size of fish stocks is a very important predictor of recreational choice at the Sundays River Estuary, and it is recommended that demand be curtailed through an increase in the boat license fee for using the estuary of ZAR174 per annum

DE, Lee; SG, Hosking; M, du Preez.

2014-01-01

215

Uranium isotopes in rivers, estuaries and adjacent coastal sediments of western India: their weathering, transport and oceanic budget  

International Nuclear Information System (INIS)

The two major river systems on the west coast of India, Narbada and Tapti, their estuaries and the coastal Arabian sea sediments have been extensively studied for their uranium concentrations and 234U/238U activity ratios. The 238U concentrations in the aqueous phase of these river systems exhibit a strong positive correlation with the sum of the major cations, and with the HCO3- ion contents. The abundance ratio of dissolved U to the sum of the major cations in these waters is similar to their ratio in typical crustal rocks. In the estuaries, both 238U and its great-grand daughter 234U behave conservatively beyond chlorosities 0.14 g/l. A review of the uranium isotope measurements in river waters yield a discharge weighted-average 238U concentration of 0.22 ?g/l with a 234U/238U activity ratio of 1.20 +-0.06. The residence time of uranium isotopes in the oceans estimated from the 238U concentration and the 234U/238U A.R. of the rivers yield conflicting results; the material balance of uranium isotopes in the marine environment still remains a paradox. If the disparity between the results is real, then an additional 234U flux of about 0.25 dpm/cm2.103 yr into the oceans is necessitated. (author)

216

Pollution Status of Two River Estuaries in the Eastern Cape, South Africa, based on Benthic Meiofauna Analyses  

Directory of Open Access Journals (Sweden)

Full Text Available The benthic meiofauna of the two river systems, the Swartkops and Gamtoos, in the Eastern Cape of South Africa has been studied extensively. Various biological indices and statistical packages were used to assess the biological status of the nematode communities in the two rivers. Nematode identification was done to the genus level. Various environmental conditions, including, concentrations of Zn, Mn, Fe, Cu and Pb, organic carbon and chlorophyll-a in the sediments, were investigated in relation to the nematode density, diversity and community structure. The results of the studies indicate that higher concentrations of heavy metals had a negative impact on the nematode density, diversity and community structure. Nematode genera such as Rhabditis, Monhystera and Theristus were found to be tolerant to pollution or indicators of pollution. The Swartkops River estuary was found to be polluted more severely than the Gamtoos. It was realised that some nematode genera such as Viscosia can establish themselves along the river estuaries, irrespective of the salinity gradient. The quantitative effects of individual metals on the structure of meiobenthic communities could not be differentiated from one another. Similarly, the effects of metals and organic carbon on the structuring of the nematode communities could not be distinguished from one another. It is suggested that more studies of this kind be carried out along the coast of Africa to establish the potential indicator value of nematodes on the African continent.

T.K. Gyedu-Ababio

2011-07-01

217

Phosphorus Release from Sediments in a Riparian Phragmites australis Community at the Estuary of the Chikugogawa River, Western Japan  

OpenAIRE

In order to determine the contribution of aquatic macrophyte communities on nutrition to sustain the high primary productivity of an estuary aquatic community, we analyzed the process of phosphorus release from sediments in aquatic macrophyte community in the estuary of the Chikugogawa River, South-Western Japan. Vertical profile of PD3-4 concentration and redox potential (Eh) of pore water in sediments were investigated within and outside the <...

Akira Haraguchi

2012-01-01

218

Comparative Study among Microflora in El-manzala Lake Water and Rashid (Rosetta Estuary of Nile River, Egypt  

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Full Text Available Phytoplankton and microbiological analysis of three different sites of each of El-Manzala Lake Water and Rashid branch of the River Nile of Egypt were examined. The results were compared and correlated with each other and with certain physico-chemical parameters using MVSP Ver. 3.1 program for Canonical Corresponding Analysis (CCA. Chlorophyceae and Bacillariophyceae represented 47.6 and 45.9% of the total phytoplankton in El-Manzala Lake Water, which was more, polluted than Rashid estuary water. Chlorophyceae was predominant (51.7% in Rashid estuary water. Heterotrophic plate counts and indicators of faecal contamination were higher in El-Manzala than in Rashid water whereas both halophilic and halotolerant bacteria were higher at Rashid than El-Manzala locations. Thermophilic and/or thermotolerant fungi and bacteria were more abundant in El-Manzala water than in Rashid water.

Sohair A. Mostafa

2003-01-01

219

Factors affecting the distribution and abundance of Macrobrachium petersi (Hilgendorf) in the Keiskamma River and estuary, South Africa  

Science.gov (United States)

A dry (1979-1980) and a wet (1980-1981) season had a marked effect on the freshwater inflow into the Keiskamma estuary. Under low inflow conditions, which results in elevated salinities in the upper reaches, an upstream migration of adult Macrobrachium petersi (Hilgendorf) to freshwater takes place. During periods of increased river inflow adult M. petersi move downstream to the more saline reaches of the estuary. These two migratory responses have been interpreted as (a) a breeding migration under high inflow conditions which ensures that larvae are in close proximity to salinities that favour growth and development, and (b) an adult upstream migration back to freshwater to escape elevated estuarine salinities as a result of the low freshwater inflow.

Read, G. H. L.

1985-09-01

220

Pluriannual watershed discharges of hg into a tropical semi-arid estuary of the Jaguaribe river, NE Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Fluxos de Hg foram determinados entre 2005 e 2009 nas estações seca e chuvosa no estuário do Rio Jaguaribe, que desagua no Oceano Atlântico Equatorial, NE do Brasil. Na estação chuvosa a massa d'água no estuário apresenta um curto tempo de residência no estuário (0,8 dias), quatro vezes menor que na [...] seca (3,1 dias). As concentrações e fluxos de Hg dissolvido ( Abstract in english Mercury fluxes were measured during the dry and rainy seasons (2005 to 2009) at the Jaguaribe River estuary, which discharges into the Equatorial Atlantic Ocean in NE Brazil. During rainy periods, the water masses exhibited a short residence time within the estuary (0.8 days). During dry periods, se [...] awater choked the fluvial discharge, resulting in longer residence times (3.1 days). Dissolved (

Luiz D., Lacerda; Francisco J. S., Dias; Rozane V., Marins; Talita M., Soares; José Marcos O., Godoy; Maria Luiza D. P., Godoy.

1719-17-01

221

A study of anthropogenic and climatic disturbance of the New River Estuary using a Bayesian belief network.  

Science.gov (United States)

The present paper utilizes a Bayesian Belief Network (BBN) approach to intuitively present and quantify our current understanding of the complex physical, chemical, and biological processes that lead to eutrophication in an estuarine ecosystem (New River Estuary, North Carolina, USA). The model is further used to explore the effects of plausible future climatic and nutrient pollution management scenarios on water quality indicators. The BBN, through visualizing the structure of the network, facilitates knowledge communication with managers/stakeholders who might not be experts in the underlying scientific disciplines. Moreover, the developed structure of the BBN is transferable to other comparable estuaries. The BBN nodes are discretized exploring a new approach called moment matching method. The conditional probability tables of the variables are driven by a large dataset (four years). Our results show interaction among various predictors and their impact on water quality indicators. The synergistic effects caution future management actions. PMID:24814252

Nojavan A, Farnaz; Qian, Song S; Paerl, Hans W; Reckhow, Kenneth H; Albright, Elizabeth A

2014-06-15

222

Sources and distribution of organic matter in a river-dominated estuary (Winyah Bay, SC, USA)  

Science.gov (United States)

The sources and distribution of organic matter (OM) in surface waters and sediments from Winyah Bay (South Carolina, USA) were investigated using a variety of analytical techniques, including elemental, stable isotope and organic biomarker analyses. Several locations along the estuary salinity gradient were sampled during four different periods of contrasting river discharge and tidal range. The dissolved organic carbon (DOC) concentrations of surface waters ranged from 7 mg l -1 in the lower bay stations closest to the ocean to 20 mg l -1 in the river and upper bay samples. There was a general linear relationship between DOC concentrations and salinity in three of the four sampling periods. In contrast, particulate organic carbon (POC) concentrations were significantly lower (0.1-3 mg l -1) and showed no relationship with salinity. The high molecular weight dissolved OM (HMW DOM) isolated from selected water samples collected along the bay displayed atomic carbon:nitrogen ratios ([C/N]a) and stable carbon isotopic compositions of organic carbon ( ?13C OC) that ranged from 10 to 30 and from -28 to -25‰, respectively. Combined, such compositions indicate that in most HMW DOM samples, the majority of the OM originates from terrigenous sources, with smaller contributions from riverine and estuarine phytoplankton. In contrast, the [C/N]a ratios of particulate OM (POM) samples varied significantly among the collection periods, ranging from low values of ˜5 to high values of >20. Overall, the trends in [C/N]a ratios indicated that algal sources of POM were most important during the early and late summer, whereas terrigenous sources dominated in the winter and early spring. In Winyah Bay bottom sediments, the concentrations of the mineral-associated OM were positively correlated with sediment surface area. The [C/N]a ratios and ?13C OC compositions of the bulk sedimentary OM ranged from 5 to 45 and from -28 to -23‰, respectively. These compositions were consistent with predominant contributions of terrigenous sources and lesser (but significant) inputs of freshwater, estuarine and marine phytoplankton. The highest terrigenous contents were found in sediments from the river and upper bay sites, with smaller contributions to the lower parts of the estuary. The yields of lignin-derived CuO oxidation products from Winyah Bay sediments indicated that the terrigenous OM in these samples was composed of variable mixtures of relatively fresh vascular plant detritus and moderately altered soil OM. Based on the lignin phenol compositions, most of this material appeared to be derived from angiosperm and gymnosperm vascular plant sources similar to those found in the upland coastal forests in this region. A few samples displayed lignin compositions that suggested a more significant contribution from marsh C 3 grasses. However, there was no evidence of inputs of Spartina alterniflora (a C 4 grass) remains from the salt marshes that surround the lower sections of Winyah Bay.

Goñi, Miguel A.; Teixeira, Maria J.; Perkey, David W.

2003-08-01

223

Change in Land Cover along the Lower Columbia River Estuary as Determined from Landsat Thematic Mapper (TM) Imagery, Technical Report 2003.  

Energy Technology Data Exchange (ETDEWEB)

The Lower Columbia River Estuary Management Plan (Jerrick, 1991) recognizes the positive relationship between the conservation of fish and wildlife habitat, and sustaining their populations. An important component of fish and wildlife conservation and management is the identification of habitats, trends in habitat change, and delineation of habitat for preservation, restoration or enhancement. Alterations to the environment, such as hydropower generation, dredging, forestry, agriculture, channel alteration, diking, bank stabilization and floodplain development, have dramatically altered both the type and distribution of habitats along the Columbia River Estuary (CRE) and its floodplain. Along the Columbia River, tidally influenced habitats occur from the river mouth to the Bonneville Dam, a distance of 230 km. If we are to effectively manage the natural resources of the Columbia River ecosystem, there is a need to understand how habitats have changed because fish and wildlife populations are known to respond to changes in habitat quality and distribution. The goal of this study was to measure the amount and type of change of CRE land cover from 1992 to 2000. We performed a change analysis on two spatial data sets describing land cover along the lower portion of the estuary (Fig. 1). The 1992 data set was created by the NOAA Coastal Remote Sensing, Coastal Change Analysis Program (C-CAP) in cooperation with Columbia River Estuary Study Task Force (CREST), the National Marine Fisheries Service (NMFS) Point Adams Field Station, and State of Washington Department of Natural Resources (DNR). The 2000 data set was produced by Earth Design Consultants, Inc. (EDC) and the Wetland Ecosystem Team (WET: University of Washington) as part of a larger Lower Columbia River Estuary Partnership (Estuary Partnership) habitat mapping study. Although the image classification methodologies used to create the data sets differed, both data sets were produced by classifying Landsat Thematic Mapper (TM) satellite imagery, making it feasible to assess land cover changes between 1992 and 2000.

Garono, Ralph; Anderson, Becci; Robinson, Rob

2003-10-01

224

Bayesian networks for environmental flow decision-making and an application in the Yellow River estuary, China  

Science.gov (United States)

We proposed an approach for environmental flow decision-making based on Bayesian networks considering seasonal water use conflicts between agriculture and ecosystems. Three steps were included in the approach: water shortage assessment after environmental flow allocation using a production-loss model considering temporal variations of river flows; trade-off analysis of water use outcomes by Bayesian networks; and environmental flow decision-making based on a risk assessment under different management strategies. An agricultural water shortage model and a production-loss model were integrated after satisfying environmental flows with temporal variability. The case study in the Yellow River estuary indicated that the average difference of acceptable economic loss for winter wheat irrigation stakeholders was 10% between water saving measures and water diversion projects. The combination of water diversion projects and water-saving measures would allow 4.1% more river inflow to be allocated to ecological needs in normal years without further economic losses in agriculture.

Pang, A. P.; Sun, T.

2014-05-01

225

Integrated River and Coastal Hydrodynamic Flood Risk Mapping of the LaHave River Estuary and Town of Bridgewater, Nova Scotia, Canada  

Directory of Open Access Journals (Sweden)

Full Text Available Bridgewater, Nova Scotia, is located 20 km inland from the mouth of the LaHave River estuary on the Atlantic Coast of Canada. Bridgewater is at risk of flooding due to the combined effects of river runoff and a storm surge on top of high tide. Projected increases in sea-level and possible increased river runoff with climate change increase the risk of future flooding. A set of river and ocean water level simulations were carried out to determine the risk of flooding to Bridgewater today and in the future under climate change. The hydrodynamic simulation developed incorporates return periods of a time series of river discharge measurements for the LaHave watershed, ocean water dynamics at the mouth of the river under normal tidal conditions and with two levels of storm surge, near shore and river bathymetry, as well as high precision topographic lidar derived ground elevations and survey grade GPS. The study was supported by data from two tide gauge sensors, and qualitative evidence provided by the community such as historical flood levels and photographs. Results show that areas upstream of the town are vulnerable to large discharge events of the LaHave River. The downtown waterfront and infrastructure are not susceptible to fluvial flooding, but is vulnerable to sea-level rise and storm surge flooding.

Tim Webster

2014-03-01

226

Use of Reflectance Ratios as a Proxy for Coastal Water Constituent Monitoring in the Pearl River Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available Spectra, salinity, total suspended solids (TSS, in mg/L and colored dissolved organic matter (CDOM, ag(400 at 400 nm sampled in stations in 44 different locations on December 18, 19 and 21, in 2006 were measured and analyzed. The studied field covered a large variety of optically different waters, the absorption coefficient of CDOM ([ag(400] in m-1 varied between 0.488 and 1.41 m-1, and the TSS concentrations (mg/L varied between 7.0 and 241.1 mg/L. In order to detect salinity of the Pearl River Estuary, we analyzed the spectral properties of TSS and CDOM, and the relationships between field water reflectance spectra and water constituents’ concentrations based on the synchronous in-situ and satellite hyper-spectral image analysis. A good correlation was discovered (the positive correlation by linear fit, between in-situ reflectance ratio R680/R527 and TSS concentrations (R2 = 0.65 for the salinity range of 1.74-22.12. However, the result also showed that the absorption coefficient of CDOM was not tightly correlated with reflectance. In addition, we also observed two significant relationships (R2 > 0.77, one between TSS concentrations and surface salinity and the other between the absorption coefficient of CDOM and surface salinity. Finally, we develop a novel method to understand surface salinity distribution of estuarine waters from the calibrated EO-1 Hyperion reflectance data in the Pearl River Estuary, i.e. channels with high salinity and shoals with low salinity. The EO-1 Hyperion derived surface salinity and TSSconcentrations were validated using in-situ data that were collected on December 21, 2006, synchronous with EO-1 Hyperion satellite imagery acquisition. The results showed that the semi-empirical relationships are capable of predicting salinity from EO-1 Hyperion imagery in the Pearl River Estuary (RMSE < 2‰.

Hong-Li Li

2009-01-01

227

Plutonium and radiocesium in the water column of the Hudson River Estuary  

International Nuclear Information System (INIS)

Isotopes of plutonium (Pu), cesium (Cs), and cobalt (Co) introduced into the Hudson River Estuary from fallout deposition, the erosion of fallout-contaminated surface soils, and nuclear reactor effluent (isotopes of Cs and Co only) have been measured in water column samples collected from 1975 to 1980. The major conclusions drawn from the work are that: for water samples collected by the two laboratories over similar time periods, the mean concentrations of nonfilterable /sup 239,240/Pu (137Cs and /sup 239,240/Pu in suspended particulates were more divergent at 2270 +/- 920 pCi/kg (+/- 1 SD) and 1430 +/- 430 pCi/kg for 137Cs, and 19 +/- 8 pCi/kg and 12 +/- 4 pCi/kg for /sup 239,240/Pu. The behavior of /sup 239,240/Pu and 137Cs within the water column is shown to diverge within brackish waters. Specifically, the magnitude of the 137Cs distribution-coefficient (K/sub d/) can be expressed as an inverse power function of the chloride ion concentrations for chlorinities between 0.1 and 4 g Cl-/l. No difference in the /sup 239,240/Pu k/sub d/ has been observed between fresh and brackish waters. Based on the expected inventories of /sup 239,240/Pu and 137Cs within watershed soils, the current downstream transport of these radionuclides represents fractional mobilization rates on the order of 1-4 (x 10-4) per yearsup>-4) per year

228

Concentration and fractionation of heavy metals in the old yellow river estuary, china.  

Science.gov (United States)

A sequential extraction procedure was applied to determine the concentration and fractionation characteristics of eight heavy metals (HMs) (Cu, Zn, Pb, Cd, Cr, Fe, Mn, and Ni) in a sediment core collected from the old Yellow River Estuary, China. The results revealed that the mean deposition rate of this sediment core, which spanned 87 yr (1925-2012), was approximately 0.5 cm yr. The mean concentrations and ranges of HMs were Cu: 26.9 (18.3-38.5), Zn: 76.4 (51.0-107), Pb: 37.3 (17.8-53.8), Cd: 0.23 (0.20-0.27), Cr: 84.7 (45.5-116), Fe: 24,000 (16,500-31,700), Mn: 709 (388-1020), and Ni: 36.1 (24.8-47.2) mg kg (dry weight). Six HMs (Cu, Zn, Cr, Cd, Fe, and Ni) were present in their highest proportion in the residual fraction; their lowest proportion was observed in the exchangeable fraction. Lead primarily existed in the oxidizable or residual fraction. Manganese was mainly presented in the exchangeable fraction. The risk assessment code results revealed that the sediments displayed a low risk for Cu, Zn, Pb, Cr, Cd, Fe, Mn, and Ni. The HMs Cu, Zn, Cr, Cd, Mn, and Ni displayed minor enrichment in the sediment core, whereas for Pb, moderate contamination enrichment was observed. Overall, an increase in and total concentration of HMs occurred since 1925 and reached a maximum value around 1980, after which there was a larger fluctuation or decline until 2012. We also found that the degree of HM pollution during the 1976-1996 period was less serious than before 1976. All the sediment samples exceeded the effect range low (ERL) for Ni, whereas 56.1, 7.32, and 17.1% exceeded the ERL values for Cr, Cu, and Pb; no samples exceeded the ERL for Zn or Cd. PMID:25602332

Liu, Houqi; Liu, Guijian; Da, Chunnian; Yuan, Zijiao; Wang, Jie

2015-01-01

229

Osprey: worldwide sentinel species for assessing and monitoring environmental contamination in rivers, lakes, reservoirs, and estuaries.  

Science.gov (United States)

In the United States, many fish and wildlife species have been used nationwide to monitor environmental contaminant exposure and effects, including carcasses of the bald eagle (Haliaeetus leucocephalus), the only top avian predator regularly used in the past. Unfortunately, bald eagles are sensitive to investigator intrusion at the nest. Thus, the osprey (Pandion haliaetus) is evaluated as a potential sentinel species for aquatic ecosystems. Several characteristics support the choice of the osprey as a sentinel species, including: (1) fish-eating diet atop the aquatic food web, (2) long-lived with strong nest fidelity, (3) adapts to human landscapes (potentially the most contaminated), (4) tolerates short-term nest disturbance, (5) nests spatially distributed at regular intervals, (6) highly visible nests easily located for study, (7) ability to accumulate most, if not all, lipophilic contaminants, (8) known sensitivity to many contaminants, and (9) nearly a worldwide distribution. These osprey traits have been instrumental in successfully using the species to understand population distribution, abundance, and changes over time; the effects of various contaminants on reproductive success; how contaminants in prey (fish on biomass basis) contribute to egg concentrations (i.e., biomagnification factors); and spatial residue patterns. Data summarized include nesting population surveys, detailed nesting studies, and chemical analyses of osprey egg, organ, blood, and feather samples for contaminants that bioaccumulate and/or biomagnify in aquatic food webs; and biochemical evaluations of blood and various organs. Studies in the United States, Canada, Mexico, Europe, and elsewhere have shown the osprey to be a useful sentinel species for monitoring selected environmental contaminants, including some emerging contaminants in lakes, reservoirs, rivers, and estuaries. PMID:19117208

Grove, Robert A; Henny, Charles J; Kaiser, James L

2009-01-01

230

Stratified active archaeal communities in the sediments of Jiulong River Estuary, China  

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Full Text Available Here the composition of total and active archaeal communities in a sediment core of Jiulong River estuary at Fujian Province, Southern China was reported. Profiles of CH4 and SO42- concentrations from the sediment core indicated the existence of a sulfate-methane transition zone (SMTZ in which sulfate reduction-coupled anaerobic oxidation of methane occurs. Accordingly, three sediment layers (16-18.5 cm, 71-73.5 cm, 161-163.5 cm from the 1.2 m sediment core were sectioned and named top, middle and bottom, respectively. Total DNA and RNA of each layer were extracted and used for clone libraries and sequence analysis of 16S rRNA genes, the reverse transcription (RT-PCR products of 16S rRNA and methyl CoM reductase alpha subunit (mcrA genes. Phylogenetic analysis indicated that archaeal communities of the three layers were dominated by the Miscellaneous Crenarchaeotal Group (MCG whose ecological functions were still unknown. The MCG could be further divided into seven subgroups, named MCG-A, B, C, D, E, F and G. MCG-A and MCG-G were the most active groups in the estuarine sediments. Known anaerobic methanotrophic archaea (ANMEs were only found as minor components in these estuarine archaeal communities. This study, together with the studies of deep subsurface sediments, would be a very good start point to target and compare the specific active archaeal groups and their roles in the dark, deep subsurface sediment environments.

QianqianLi

2012-08-01

231

Particle Association of Enterococcus and Total Bacteria in the Lower Hudson River Estuary, USA  

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Full Text Available Bacterial particle association has important consequences for water-quality monitoring and modeling. Particle association can change vertical and horizontal transport of bacterial cells, as well as patterns of persistence and production. In this study, the abundance and particle association of total bacteria and the fecal-indicator, Enterococcus, were quantified between June and October 2008 in the lower Hudson River Estuary (HRE. Twelve sites were sampled, including mid-channel, near shore, and tributary habitats, plus a sewage outfall. Total bacterial cell counts averaged 9.2 × 109 ± 6.4 × 109 cell l–1 (1 standard deviation, comparable to previous sampling in the HRE. Unlike earlier studies, bacterial abundance did not change consistently along the north/south estuarine salinity gradient. Enterococcus concentrations were highly variable, but mid-channel stations had significantly lower values than other habitat categories. Counts of total bacteria and Enterococcus were both correlated with turbidity, which was also significantly lower at mid-channel stations. A larger fraction of Enterococci were associated with particles (52.9 ± 20.9%, 1 standard deviation than in the pool of total bacteria (23.8 ± 15.0%. This high frequency of particle association, relative to total bacteria, could cause Enterococcus to be preferentially retained near input sources because of enhanced deposition to bottom sediments, where they would be available for later resuspension. In turn, retention and resuspension in nearshore environments may explain the observed cross-channel variability of turbidity and Enterococcus. Assessments and predictive models of estuarine water quality may be improved by incorporating cross-channel variability and the effects of particle association on key indicators.

Elizabeth Suter

2011-10-01

232

Waterbird Population Changes in the Wetlands at Chongming Dongtan in the Yangtze River Estuary, China  

Science.gov (United States)

We studied the changes in wetland habitats and waterbird communities between the 1980s and the 2000s at Chongming Dongtan, a Ramsar site in the Yangtze River estuary, an ecologically important region. This region is an important stopover site for shorebirds along the East Asian-Australasian flyway and is extensively used by waterfowl. A net loss of 11% of the wetland area was estimated during study periods at Chongming Dongtan. The change was dependent on wetland types: while the area of artificial habitats such as paddy fields and aquacultural ponds more than doubled, more than 65% of natural habitats including sea bulrush ( Scirpus mariqueter) and common reed ( Phragmites australis) marshes were lost over the two decades. An exotic plant species introduced from North America, smooth cordgrass ( Spartina alterniflora), occupied 30% of the vegetated intertidal zone by the 2000s. Although waterbird species richness did not change between the 1980s (110) and the 2000s (111), 13 species found in 1980s were replaced by 14 newly recorded species. Moreover, there were more species with declining trends (58) than with increasing trends (19). The population trends of species were affected by residential status and habitat types. Transients, wintering migrants, and habitat specialists were more likely to show declining trends compared to those breeding at Dongtan (including year-round and summer residents) and habitat generalists. Furthermore, species associated mainly with natural wetlands were more likely to decline than those associated mainly with artificial wetlands. These patterns suggest that the loss and change of wetland habitats at Chongming Dongtan adversely affected local population dynamics and might have contributed to the global decline of some waterbird species. Because Chongming Dongtan provides stopover and wintering habitats for many migratory waterbirds, protection and restoration of natural wetlands at Chongming Dongtan are urgently needed.

Ma, Zhijun; Wang, Yong; Gan, Xiaojing; Li, Bo; Cai, Yinting; Chen, Jiakuan

2009-06-01

233

[Photodegradation of chromophoric dissolved organic matter from Jiulong River Estuary under natural solar radiation].  

Science.gov (United States)

Low salinity water sample collected from Jiulong River Estuary filtered using 0.2 microm Millipore filter was exposed to natural solar radiation from 10:00 to 16:00 each day during one week period in early and late May, 2005. Photodegradation of fluorescence and absorption properties of CDOM (chromophoric dissolved organic matter) was observed. The results showed that humic-like fluorescence (lambda Ex/lambda Em = 350/450 nm), tryptophan-like fluorescence (lambda Ex/lambda Em = 225/350 nm) and absorption coefficient of CDOM can be significantly photodegraded during short-term solar exposure in early summer. These photodegradation processes followed the first-order dynamic equation. The degradation half time of humic-like fluorescence, tryptophan-like fluorescence and a (280) were calculated as 3.5-5.1 d, 3.0-4.5 d and 6.3 d. The absorption loss spectra of CDOM indicated that the solar UV radiation was responsible for the photochemical degradation of CDOM. The loss of humic-like fluorescence (70%) was obviously higher than loss of a (280) (about 40%), suggesting that photobleaching ability of CDOM fluorophores were much stronger than CDOM chromophores. However, the correlation relationship between humic-like fluorescence and absorption coefficient are still kept. A250/A350 of CDOM increased till the end of radiation experiment compared with the control group, suggesting photodegradation may decrease the average molecular size of CDOM. These findings show that terrestrial CDOM can be transformed and removed by photochemical decomposition after transport into the sea, and photodegradation might be an important sink for terrestrial CDOM. PMID:18763485

Guo, Wei-dong; Cheng, Yuan-yue

2008-06-01

234

Methane and nitrous oxide fluxes in the polluted Adyar River and estuary, SE India  

Energy Technology Data Exchange (ETDEWEB)

We measured dissolved N{sub 2}O, CH{sub 4}, O{sub 2}, NH{sub 4}{sup +}, NO{sub 3}{sup -} and NO{sub 2}{sup -} on 7 transects along the polluted Adyar River-estuary, SE India and estimated N{sub 2}O and CH{sub 4} emissions using a gas exchange relation and a floating chamber. High NO{sub 2}{sup -} implied some nitrification of a large anthropogenic NH{sub 4}{sup +} pool. In the lower catchment CH{sub 4} was maximal (6.3 {+-} 4.3 x 10{sup 4} nM), exceeding the ebullition threshold, whereas strong undersaturation of N{sub 2}O and O{sub 2} implied intense denitrification. Emissions fluxes for the whole Adyar system {approx}2.5 x 10{sup 8} g CH{sub 4} yr{sup -1} and {approx}2.4 x 10{sup 6} g N{sub 2}O yr{sup -1} estimated with a gas exchange relation and {approx}2 x 10{sup 9} g CH{sub 4} yr{sup -1} derived with a floating chamber illustrate the importance of CH{sub 4} ebullition. An equivalent CO{sub 2} flux {approx}1-10 x 10{sup 10} g yr{sup -1} derived using global warming potentials is equivalent to total Chennai motor vehicle CO{sub 2} emissions in one month. Studies such as this may inform more effective waste management and future compliance with international emissions agreements.

Nirmal Rajkumar, A. [Institute for Ocean Management, Anna University, Chennai 600 025 (India); Barnes, J. [Ocean Research Group, School of Marine Science and Technology, Ridley Building, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom); Ramesh, R.; Purvaja, R. [Institute for Ocean Management, Anna University, Chennai 600 025 (India); Upstill-Goddard, R.C. [Ocean Research Group, School of Marine Science and Technology, Ridley Building, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom)], E-mail: rob.goddard@ncl.ac.uk

2008-12-15

235

Use of fishing resources by women in the Mamanguape River Estuary, Paraíba state, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Nós analisamos a apropriação e o uso dos recursos pesqueiros pelas mulheres que moram no Estuário do Rio Mamanguape, Estado da Paraíba, Brasil. Foi usada uma combinação de métodos qualitativos (entrevistas e observações diretas) e quantitativos (valor de uso e concordância de uso principal corrigido [...] ). Foram entrevistadas 30 mulheres e registrado o uso de 41 espécies (peixes - 30, crustáceos - 08 e moluscos - 03), principalmente para consumo local e venda. As espécies com maior valor de uso foram Genidens genidens (0,7), Callinectes exasperatus (0,73) e Anomalocardia brasiliana (0,46). A diversidade de recursos explorados demonstra a importância do manguezal para as famílias do ERM, e os dados coletados podem servir de base para a formulação de políticas públicas que promovam a participação igualitária de mulheres na pesca, e na conservação ambiental. Abstract in english We evaluated the appropriation and use of fishing resources by women residing near the Mamanguape River Estuary (MRE), Paraíba state, Brazil. Were used combinations of qualitative (interviews and direct observations) and quantitative methods (use value and corrected principal use concordance). Thirt [...] y women were interviewed and reported the use of 41 species (30 fish, 8 crustaceans, and 3 mollusks), mainly for local consumption and sale. The species with the highest use value were Genidens genidens (0.7), Callinectes exasperatus (0.73) and Anomalocardia brasiliana (0.46). The diversity of resources exploited demonstrates the importance of the mangrove ecosystem to MRE families, and the data gathered can serve as a basis for formulating public policies to promote the equal participation of women in fishing and environmental conservation.

Michelle S.P., Rocha; Idalina M.F.L., Santiago; Creuza S., Cortez; Priscila M., Trindade; José S., Mourão.

1189-11-01

236

Sciaenidae fish of the Caeté River estuary, Northern Brazil: mitochondrial DNA suggests explosive radiation for the Western Atlantic assemblage  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Sciaenids are fish which are normally abundant in tropical estuaries of the western Atlantic. Studies on the Caeté river estuary in the northern Brazilian state of Pará have revealed that in this area Sciaenidae is the dominant family, comprising almost 50% of all teleosts sampled. In this paper we [...] present the results of the first phylogenetic study on South American estuarine sciaenids, during which we obtained mitochondrial gene 16S sequences from 15 species belonging to eight genera occurring in the Caeté estuary. Intergeneric nucleotide divergences varied from 5 to 15%, Lonchurus and Menticirrhus being the most divergent lineages. Nucleotide divergences were quite variable amongst species of the same genus, ranging from 1.2% (Stellifer microps x Stellifer naso) to 8.4% (Menticirrhus americanus x Menticirrhus littoralis). Cladograms based on maximum parsimony, minimum evolution and maximum likelihood depicted an explosive diversification pattern for the western Atlantic sciaenid assemblage. Our analysis further reveals a very close relationship between Bairdiella and Stellifer, a monophyletic clade which emerged during the more recent diversification events of the Sciaenidae family. The phylogenetic reconstruction suggests the need for a revision of the taxonomy and nomenclature of the Bairdiella/Stellifer group.

Christina, Vinson; Grazielle, Gomes; Horacio, Schneider; Iracilda, Sampaio.

237

Sciaenidae fish of the Caeté River estuary, Northern Brazil: mitochondrial DNA suggests explosive radiation for the Western Atlantic assemblage  

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Full Text Available Sciaenids are fish which are normally abundant in tropical estuaries of the western Atlantic. Studies on the Caeté river estuary in the northern Brazilian state of Pará have revealed that in this area Sciaenidae is the dominant family, comprising almost 50% of all teleosts sampled. In this paper we present the results of the first phylogenetic study on South American estuarine sciaenids, during which we obtained mitochondrial gene 16S sequences from 15 species belonging to eight genera occurring in the Caeté estuary. Intergeneric nucleotide divergences varied from 5 to 15%, Lonchurus and Menticirrhus being the most divergent lineages. Nucleotide divergences were quite variable amongst species of the same genus, ranging from 1.2% (Stellifer microps x Stellifer naso to 8.4% (Menticirrhus americanus x Menticirrhus littoralis. Cladograms based on maximum parsimony, minimum evolution and maximum likelihood depicted an explosive diversification pattern for the western Atlantic sciaenid assemblage. Our analysis further reveals a very close relationship between Bairdiella and Stellifer, a monophyletic clade which emerged during the more recent diversification events of the Sciaenidae family. The phylogenetic reconstruction suggests the need for a revision of the taxonomy and nomenclature of the Bairdiella/Stellifer group.

Christina Vinson

2004-01-01

238

Zooplankton spatial and diurnal variations in the Changjiang River estuary before operation of the Three Gorges Dam  

Science.gov (United States)

Estuarine plankton communities can serve as indicators of ecosystem modification in response to anthropogenic influences. The main objectives of this study were to describe the spatial distribution and diurnal variability in zooplankton abundance and biomass over almost entire salinity gradient of the Changjiang (Yangtze) River estuary and to provide a background reference for future studies. To accomplish this, data were collected from 29 stations in the estuary from May 19 to 26, 2003, including two anchor stations. The spatial and diurnal variations in zooplankton characteristics, i.e. abundance, biomass, and gross taxonomic composition, were examined. Generally, both the abundance and biomass gradually increased seaward and presented distinct spatial variations. In addition, the spatial data revealed a significant correlation between abundance and biomass; however, there was no significant correlation between abundance and biomass for the diurnal data. Although the zooplankton composition indicated distinct spatial differences in terms of dominant groups, copepods accounted for >50% of the total zooplankton abundance in most regions and times. Three zooplankton assemblages were recognized through hierarchical cluster analysis. These assemblages existed along the salinity gradient from fresh water to seawater, and their positions coincided with those of the three principal water masses in the estuary. The assemblages were classified as: (1) true estuarine, (2) estuarine and marine, and (3) euryhaline marine, which were characterized by the copepods Sinocalanus dorrii, Labidocera euchaeta, and Calanus sinicus, respectively. Both spatial and diurnal data indicated that there was no significant correlation between zooplankton abundance/biomass and depth-integrated phytoplankton abundance.

Gao, Xuelu; Song, Jinming; Li, Xuegang

2011-05-01

239

Nutrient fluxes in the Changjiang River estuary and adjacent waters — a modified box model approach  

Science.gov (United States)

To solve nutrient flux and budget among waters with distinct salinity difference for water-salt-nutrient budget, a traditional method is to build a stoichiometrically linked steady state model. However, the traditional way cannot cope appropriately with those without distinct salinity difference that parallel to coastline or in a complex current system, as the results would be highly affected by box division in time and space, such as the Changjiang (Yangtze) River estuary (CRE) and adjacent waters (30.75°2-31.75°N, 122°10'-123°20'E). Therefore, we developed a hydrodynamic box model based on the traditional way and the regional oceanic modeling system model (ROMS). Using data from four cruises in 2005, horizontal, vertical and boundary nutrient fluxes were calculated in the hydrodynamic box model, in which flux fields and the major controlling factors were studied. Results show that the nutrient flux varied greatly in season and space. Water flux outweighs the nutrient concentration in horizontal flux, and upwelling flux outweighs upward diffusion flux in vertical direction (upwelling flux and upward diffusion flux regions overlap largely all the year). Vertical flux in spring and summer are much greater than that in autumn and winter. The maximum vertical flux for DIP (dissolved inorganic phosphate) occurs in summer. Additional to the fluxes of the Changjiang River discharge, coastal currents, the Taiwan Warm Current, and the upwelling, nutrient flux inflow from the southern Yellow Sea and outflow southward are found crucial to nutrient budgets of the study area. Horizontal nutrient flux is controlled by physical dilution and confined to coastal waters with a little into the open seas. The study area acts as a conveyer transferring nutrients from the Yellow Sea to the East China Sea in the whole year. In addition, vertical nutrient flux in spring and summer is a main source of DIP. Therefore, the hydrodynamic ROMS-based box model is superior to the traditional one in estimating nutrient fluxes in a complicated hydrodynamic current system and provides a modified box model approach to material flux research.

Wang, Xiaohong; Yu, Zhiming; Fan, Wei; Song, Xiuxian; Cao, Xihua; Yuan, Yongquan

2015-01-01

240

Population characteristics of the swimming crab Callinectes amnicola De Rocheburne, 1883 (Crustacea, Brachyura, Portunidae in the Qua Iboe River estuary, Nigeria  

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Full Text Available Aspects of the biology of Callinectes amnicola, from the Qua Iboe River estuary, south-eastern Nigeria, was investigated for twelve months from June 2008 to May 2009, with respect to its size composition and population characteristics. A total of 1,193 specimens were obtained comprising 508males and 685 females with overall (1:1.35, ?2 = 26.26, 1 df, p 2 =2.17, I df, p 2 = 11.44, 1 df, p C. amnicola inhabiting the lower reaches of the Qua Iboe River estuary, Nigeria.

James P. Udoh

2011-07-01

241

Inventories of 239 240Pu, 241Am, 137Cs, and 60Co in Columbia River sediments from Hanford to the Columbia River estuary  

International Nuclear Information System (INIS)

The inventories of 239 240Pu, 241Am, 137Cs, and 60Co in sediments of the lower Columbia River and its estuary have been estimated from the measured activities of these radionuclides in 50 cores raised in 1977-1978. Cobalt-60 activities are attributed to the operation of the now inoperative plutonium production reactors located on the Hanford Reservation in Washington State; the majority of the 239 240Pu and 137Cs activities and all of the 241Am activity are derived from global fallout. At the time of sampling, the operation of the Trojan nuclear power plant near St. Helens, OR, had not introduced detectable amounts of these radionuclides to the sandy sediments downstream from the plant location. Despite the substantial, past addition of artificial radioactivity to the river from the Hanford reactors, present inventories of artificial radioactivity are small. Erosional processes within the river's drainage basin remove negligible quantities of fallout radionuclides to the ocean. 31 references

242

Infilling of the Hudson River Estuary During the Late Holocene (3000ka to Present): Implications for Estuarine Stratigraphic Models  

Science.gov (United States)

Estuaries are widely preserved in the geologic record and the estuarine fill, contained between non-marine sediment, provides an excellent temporal marker for continental margin studies. Estuarine stratigraphic models have provided a framework within which to interpret the estuarine fill. However, estuarine systems differ greatly in the shape of their valleys, the tectonic boundaries they cross, and in sediment supply so that their position in the geologic record may be out of sequence with that predicted by the models. New insights into estuarine systems and models are provided by the Hudson River Estuary (HRE; New York State) based on >150 cores and grab sediment samples and acoustic images documenting in great detail how the HRE filled its earlier excavated valley during the latest Holocene (3ka to present). Radiocarbon and 137-Cs radioisotope ages, borehole, and core data document the sedimentation patterns of the estuary. Diatom assemblages provide estimates of the shallowing-upwards of the estuary as its basin filled with sediments. The three areas of the stratigraphic model present in the HRE, include zones formed within inner fluvial and outer marine areas, (containing coarse-grained, sands and gravels), and a central area (containing fine-grained, silts and clays), that are nearly filled with little room for sediments to accumulate at or near sea-level. This has resulted in sedimentary bypass for almost the entire length the estuary. South of Kingston, fine-grained sediments have ceased accumulating when the bottom approaches wave base. Upstream from Kingston, final filling occurs as sediments fill in the remaining accommodation, forming islands. This should result in the export of sediment to the coastal zone. Instead, localized areas of sediment trapping still exist, which are related to the Hudson Valley Highlands and to the location of the estuarine turbidity maximum that hold large volumes of sediment. As a result minor volumes of Recent sediment are accumulating in coastal bays (Sandy Hook, New Jersey) and on the inner shelf, and sediment export to the Hudson Shelf Valley on the mid-shelf is nearly non-existent, with sediments dated at 14ka from 14-C on the outer shelf. Additionally, anthropogenic activities (construction of bridges and dredging) alter sedimentation patterns in the estuary leading to continued localized erosion and deposition. For example, sediment export onto the shelf is taking place, not by natural processes but by dredging. The variability documented for the HRE indicates that although estuarine and stratigraphic models provide a framework for continental margin studies, the models need to be interpreted, taking into consideration these factors.

McHugh, C. M.; Pekar, S. F.; Ryan, W. B.; Carbotte, S.; Bell, R.; Burckle, L.

2002-12-01

243

[Succession of rotifer community and its relationship with environmental factors in a new Estuarial Landscape River, Shanghai].  

Science.gov (United States)

The community structures of rotifers were surveyed in Lin'gang B Gang River, a new estuarial river in Shanghai, from December 2011 to November 2012. A total of 23 rotifer species were identified, of which 19 species were the indicator of environmental pollution. Rotifer species' number rose monthly from 2 to 13. A conspicuous succession of dominant species was observed from a single dominant species (Keratella cochlearis) to several species. The rotifer community structure of Lin'gang B Gang River differs with that of the outer water body (Lu Chaoyin River). Pearson analysis showed that the rotifers' density had a significant correlation with water temperature and chlorophyll-a (P index between every month demonstrated that aquatic ecosystem of Lin'gang B Gang River was in the unstable state. However, the increase of Margalef index and Shannon-Wiener index of rotifers and the decline of E/O value monthly showed the water environment of Lin'gang B Gang. River was improved. PMID:25518674

Ma, Wen-hua; Zhang, Weil; Gu, Wan-wen; Zhang, Rui-lei; Wang, Li-qing

2014-09-01

244

Distribution and abundance of Cladocera (Branchiopoda) in the Paraíba do Sul River estuary, Rio de Janeiro, Brazil  

Scientific Electronic Library Online (English)

Full Text Available O presente estudo teve como objetivo caracterizar a comunidade zooplanctônica de cladóceros no estuário do Rio Paraíba do Sul, localizado no município de São João da Barra, RJ. O zooplâncton foi coletado mensalmente de setembro/2002 a agosto/2003 em nove estações através de arrastos subsuperficiais [...] com uma rede de plâncton com abertura de boca de 30 cm e malha de 70 mµ, dotada de fluxômetro mecânico. Foram medidas simultaneamente a salinidade e a temperatura. Foram identificadas dezessete espécies de cladóceros: Pseudoevadne tergestina, Penilia avirostris, Macrothrix triserialis, Moina micrura, Simocephalus Kerhervei, Simocephalus vetalus, Simocephalus latirostris, Simocephalus serrulatus, Alona rectangula, Alona quadrangularis, Bosmina longirostris, Bosminopsis deitersi, Camptocercus dadayi, Ceriodaphnia richardi, Diaphanosoma fluviatile, Kurzia latissima e Pleuroxus similis. As maiores abundâncias de cladóceros ocorreram no mês de abril na zona marinha do estuário. A espécie mais abundante nesse período foi Penilia avirostris. Na zona de mistura e fluvial do estuário, as espécies mais abundantes foram Moina micrura, principalmente durante o mês de janeiro; Simocephalus vetalus e Bosmina longirostris na primavera. Diante desse cenário, pode-se dizer que a comunidade de cladóceros no estuário do Rio Paraíba do Sul apresenta características de ambientes marinhos, estuarinos e limnicos. A salinidade e a temperatura parecem limitar a ocorrência e distribuição dos cladóceros no estuário. Abstract in english To characterize the cladoceran community of the Paraíba do Sul River estuary, located in the district of São João da Barra, Rio de Janeiro, Brazil, cladocerans were collected monthly in nine sampling stations from September 2002 until August 2003. Samples were obtained by subsurface tows using a pla [...] nkton net with a 30 cm opening mouth and 70 micron mesh size, fitted with a mechanical flowmeter. Environmental parameters such as salinity and temperature were also obtained. Seventeen species of Cladocera were identified: Pseudoevadne tergestina, Penilia avirostris, Macrothrix triserialis, Moina micrura, Simocephalus kerhervei, Simocephalus vetalus, Simocephalus latirostris, Simocephalus serrulatus, Alona rectangula, Alona quadrangularis, Bosmina longirostris, Bosminopsis deitersi, Camptocercus dadayi, Ceriodaphnia richardi, Diaphanosoma fluviatile, Kurzia latissima and Pleuroxus similis. The highest total abundance of Cladocera occurred in April in the marine zone of the estuary. The most abundant species during this period was Penilia avirostris. At the mixing and freshwater zones of the estuary, the most abundant species were Moina micrura, mainly in January; and Simocephalus vetalus and Bosmina longirostris during spring. From this scenario, it can be inferred that the cladoceran community of the Paraíba do Sul River estuary presents characteristics of marine, brackish and freshwater environments. Temperature and salinity seem to limit the occurrence and distribution of cladocerans in the estuary.

José Mauro, Sterza; Luiz Loureiro, Fernandes.

2006-12-01

245

Distribution and abundance of Cladocera (Branchiopoda in the Paraíba do Sul River estuary, Rio de Janeiro, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available To characterize the cladoceran community of the Paraíba do Sul River estuary, located in the district of São João da Barra, Rio de Janeiro, Brazil, cladocerans were collected monthly in nine sampling stations from September 2002 until August 2003. Samples were obtained by subsurface tows using a plankton net with a 30 cm opening mouth and 70 micron mesh size, fitted with a mechanical flowmeter. Environmental parameters such as salinity and temperature were also obtained. Seventeen species of Cladocera were identified: Pseudoevadne tergestina, Penilia avirostris, Macrothrix triserialis, Moina micrura, Simocephalus kerhervei, Simocephalus vetalus, Simocephalus latirostris, Simocephalus serrulatus, Alona rectangula, Alona quadrangularis, Bosmina longirostris, Bosminopsis deitersi, Camptocercus dadayi, Ceriodaphnia richardi, Diaphanosoma fluviatile, Kurzia latissima and Pleuroxus similis. The highest total abundance of Cladocera occurred in April in the marine zone of the estuary. The most abundant species during this period was Penilia avirostris. At the mixing and freshwater zones of the estuary, the most abundant species were Moina micrura, mainly in January; and Simocephalus vetalus and Bosmina longirostris during spring. From this scenario, it can be inferred that the cladoceran community of the Paraíba do Sul River estuary presents characteristics of marine, brackish and freshwater environments. Temperature and salinity seem to limit the occurrence and distribution of cladocerans in the estuary.O presente estudo teve como objetivo caracterizar a comunidade zooplanctônica de cladóceros no estuário do Rio Paraíba do Sul, localizado no município de São João da Barra, RJ. O zooplâncton foi coletado mensalmente de setembro/2002 a agosto/2003 em nove estações através de arrastos subsuperficiais com uma rede de plâncton com abertura de boca de 30 cm e malha de 70 mµ, dotada de fluxômetro mecânico. Foram medidas simultaneamente a salinidade e a temperatura. Foram identificadas dezessete espécies de cladóceros: Pseudoevadne tergestina, Penilia avirostris, Macrothrix triserialis, Moina micrura, Simocephalus Kerhervei, Simocephalus vetalus, Simocephalus latirostris, Simocephalus serrulatus, Alona rectangula, Alona quadrangularis, Bosmina longirostris, Bosminopsis deitersi, Camptocercus dadayi, Ceriodaphnia richardi, Diaphanosoma fluviatile, Kurzia latissima e Pleuroxus similis. As maiores abundâncias de cladóceros ocorreram no mês de abril na zona marinha do estuário. A espécie mais abundante nesse período foi Penilia avirostris. Na zona de mistura e fluvial do estuário, as espécies mais abundantes foram Moina micrura, principalmente durante o mês de janeiro; Simocephalus vetalus e Bosmina longirostris na primavera. Diante desse cenário, pode-se dizer que a comunidade de cladóceros no estuário do Rio Paraíba do Sul apresenta características de ambientes marinhos, estuarinos e limnicos. A salinidade e a temperatura parecem limitar a ocorrência e distribuição dos cladóceros no estuário.

José Mauro Sterza

2006-12-01

246

CO2 flux and seasonal variability in the turbidity maximum zone and surrounding area in the Changjiang River estuary  

Science.gov (United States)

The turbidity maximum zone (TMZ) is one of the most important regions in an estuary. However, the high concentration of suspended material makes it difficult to measure the partial pressure of CO2 ( pCO2) in these regions. Therefore, very little data is available on the pCO2 levels in TMZs. To relatively accurately evaluate the CO2 flux in an example estuary, we studied the TMZ and surrounding area in the Changjiang (Yangtze) River estuary. From seasonal cruises during February, August, November 2010, and May 2012, the pCO2 in the TMZ and surrounding area was calculated from pH and total alkalinity (TA) measured in situ, from which the CO2 flux was calculated. Overall, the TMZ and surrounding area acted as a source of atmosphere CO2 in February and November, and as a sink in May and August. The average FCO2 was -9, -16, 5, and 5 mmol/(m2·d) in May, August, November, and February, respectively. The TMZ's role as a source or sink of atmosphere CO2 was quite different to the outer estuary. In the TMZ and surrounding area, suspended matter, phytoplankton, and pH were the main factors controlling the FCO2, but here the influence of temperature, salinity, and total alkalinity on the FCO2 was weak. Organic carbon decomposition in suspended matter was the main reason for the region acting as a CO2 source in winter, and phytoplankton production was the main reason the region was a CO2 sink in summer.

Li, Xuegang; Song, Jinming; Yuan, Huamao; Li, Ning; Duan, Liqin; Qu, Baoxiao

2015-01-01

247

Spatial variation, environmental assessment and source identification of heavy metals in sediments of the Yangtze River Estuary.  

Science.gov (United States)

In order to analyze the spatial distribution patterns, pollution sources and ecological risks of heavy metals (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn), 30 sediment samples were taken from in the Yangtze River Estuary (YRE). The results indicated that the contamination ranking of heavy metals was As>Cr>Cd>Ni>Mn>Pb>Zn>Cu. In the various areas, the pollution magnitude decreased as follows: adjacent sea>river mouth>inner-region. Compared to data published for other regions, the YRE data indicated that the sediment was not severely contaminated by heavy metals. In the YRE, natural and anthropogenic inputs dominated the distribution patterns of the heavy metals. Beyond that, the hydrodynamic conditions, such as the Taiwan warm current, coastal current and Yangtze diluted water, also caused distribution variations in the study areas. PMID:25103899

Wang, Jiawei; Liu, Ruimin; Zhang, Peipei; Yu, Wenwen; Shen, Zhenyao; Feng, Chenghong

2014-10-15

248

Temporal trends of hydrocarbons in sediment cores from the Pearl River Estuary and the northern South China Sea.  

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Concentrations and fluxes of unresolved complex mixture of hydrocarbons (UCM) and polycyclic aromatic hydrocarbons (PAHs) were analyzed for two (210)Pb dated sediment cores from the Pearl River Estuary (PRE) and the adjacent northern South China Sea (NSCS). Compound-specific stable carbon isotopic compositions of individual n-alkanes were also measured for identification of the hydrocarbon sources. The historical records of PAHs in the NSCS reflected the economic development in the Pearl River Delta during the 20th century. PAHs in the NSCS predominantly derive from combustion of coal and biomass, whereas PAHs in the PRE are a mixture of petrogenic and pyrogenic in origins. The isotopic profiles reveal that the petrogenic hydrocarbons in the PRE originate predominantly from local spillage/leakage of lube oil and crude oils. The accumulation rates of pyrogenic PAHs have significantly increased, whereas UCM accumulation has slightly declined in the NSCS in the recent three decades. PMID:18339464

Peng, Xianzhi; Wang, Zhendi; Yu, Yiyi; Tang, Caiming; Lu, Hong; Xu, Shiping; Chen, Fanrong; Mai, Bixian; Chen, Shejun; Li, Kechang; Yang, Chun

2008-11-01

249

Mercury profiles in sediments of the Pearl River Estuary and the surrounding coastal area of South China  

International Nuclear Information System (INIS)

The spatial and temporal variations of mercury (Hg) in sediments of the Pearl River Estuary (PRE) and the surrounding coastal area (South China Sea) were studied. In surface sediments, the concentrations of Hg ranged from 1.5 to 201 ng/g, with an average of 54.4 ng/g, displaying a decreasing trend with the distance from the estuary to the open sea. This pattern indicates that the anthropogenic emissions from the Pearl River Delta (PRD) region are probably the main sources of Hg in this coastal region. Using the 210Pb dating technique, the historical changes in the concentrations and influxes of Hg in the last 100 years were also investigated. The variations in Hg influxes in sediment cores obviously correlate with the economic development and urbanization that has occurred the PRD region, especially in the last three decades. - The spatial and historical changes of Hg in sediment reflect the industrial development and urbanization of the region in south China.

250

[Study on dynamics of hydrogen sulfide and carbonyl sulfide emission fluxes from Suaeda salsa marsh in the Yellow River estuary].  

Science.gov (United States)

The H2S and COS emission fluxes from Suaeda salsa marsh in the Yellow River estuary were measured using the static chamber and Chromatogram method during the growth season (May to October), the results showed that the seasonal and diurnal variations of H2S and COS emission fluxes were obvious, and Suaeda salsa marsh in the Yellow River estuary was the sources for both H2S and COS during the growth time, and the mean H2S and COS emission fluxes from Suaeda salsa marsh were 4.97 microg x (m2 x h)(-1) and 0.92 microg x (m2 x h)(-1), respectively. Different environmental factors had different effects on the emission fluxes of H2S and COS from Suaeda salsa marsh, in which the SO4(2-) content and water content in the soil were the main factors that affected the H2S and COS emission fluxes, respectively. Sulfur gases emissions from Suaeda salsa marsh may be affected by many factors, such as plant, tide status and so on, so that should be further studied. PMID:24812979

Li, Xin-Hua; Guo, Hong-Hai; Yang, Li-Ping; Zhu, Zhen-Lin; Sun, Xiao-Qing

2014-02-01

251

Effect of the exotic plant Spartina alterniflora on macrobenthos communities in salt marshes of the Yangtze River Estuary, China  

Science.gov (United States)

The Yangtze River Estuary is an important eco-region of China; it has, however, been heavily infested with the invasive plant Spartina alterniflora. This study examined the benthic communities associated with the invasive S. alterniflora and two native plants ( Scirpus mariqueter and Phragmites australis) at three tidal elevations to provide a comprehensive evaluation of the impacts of marsh plant invasions on intertidal macrofauna of the Yangtze River Estuary. Spartina alterniflora had significantly sparser and taller stems than S. mariqueter, whereas the traits of S. alterniflora and P. australis were relatively similar. A total of 23 macrofaunal taxa were recorded during this study and their mean density was 1885 ind. m -2. Numerically, gastropods and bivalves were the dominant group; together they constituted 95.72% of the total macrofaunal individuals. The differences in macrofaunal community structure were greater among different elevations than between native and exotic plants. The effects of plant types on species richness and densities of macroinvertebrates were generally weak. Densities of only one species ( Glaucomya chinensis) differed significantly between S. alterniflora and S. mariqueter marshes at the lower elevation. The tolerance of the macrobenthos to plant invasions thus depends on various factors, including habitats, species of macrofauna, and local plants.

Chen, Zhongbing; Guo, Li; Jin, Binsong; Wu, Jihua; Zheng, Guanghong

2009-04-01

252

Distribution, historical trends and inventories of polychlorinated biphenyls in sediments from Yangtze River Estuary and adjacent East China Sea  

International Nuclear Information System (INIS)

A large portion of polychlorinated biphenyls (PCBs) from e-waste released into the coastal areas may be the potential source of PCBs to the global oceans. The paper presents data of PCBs concentrations in fifty surface sediment samples and a dated sediment core in Yangtze River Delta (YRE) and adjacent East China Sea (ECS). The total PCBs levels varied from 5.08 to 19.64 ng/g dry weight, with the highest concentrations situate within the river-sea boundary zone which is so-called “marginal filter”. Concurrent with the operation of e-waste recycling over the last two decades, PCB fluxes started to rise again after 1980s and reached a maximum in this century. The full data set was used to estimate the burden of PCBs in YRE and adjacent ECS. A total sediment burdens were 192.8 tons, with the spatial density of 364 ng/cm2 which accounts for 1.9% of all the PCBs in China. - Highlights: ? PCBs residues remained widespread in Yangtze River Delta and adjacent East China Sea. ? Highest PCBs concentrations situate within the river-sea boundary zone. ? Congener profiles and PCA highlight the influence of e-waste recycling. ? Temporal distributions indicated PCB fluxes reached a maximum in this century. ? Total sediment burdens accounts for 1.9 % of all the PCBs in China. - Spatial and temporal distributions of polychlorinated biphenyls have been delineated in sediments from Yangtze River Estuary and adjacent East China Sea.

253

Surficial and vertical distribution of heavy metals in different estuary wetlands in the Pearl river, South China  

Energy Technology Data Exchange (ETDEWEB)

A total of 87 soil profiles sampled from five types of wetlands in the Pearl River estuary were analyzed to investigate the surficial and vertical distributions of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn). The results show that wetlands directly connected with rivers (e.g., riparian wetlands, estuarine wetlands, and mangrove wetlands) has much higher metal concentrations than those indirectly connected with rivers (e.g., pond wetlands and reclaimed wetlands). The river water is the major pollution source for all investigated heavy metals. The vertical distribution of heavy metals can be classified into three patterns: (i) linear distribution pattern. The concentration of heavy metals gradually decreases with an increase in soil depth (for riparian and estuarine wetlands); (ii) irregular and stable pattern (for pond and reclaimed wetlands); and (iii) middle enrichment pattern (for mangrove wetlands). In addition to river-borne inputs, a variety of vegetation composition, hydraulic conditions, and human activities also contribute to the variation in distribution of heavy metals in different wetlands. Soil properties (e.g., particle size, pH, salinity, and SOM) also affect the distribution of trace metals in each soil layer. The major pollution source of heavy metals is industrial wastewater. Other sources include agriculture and domestic premises, and atmospheric deposition. This study provides a sound basis for the risk assessment of heavy metals in the studied wetlands and for wetland conservation in general. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Zhang, Honggang; Cui, Baoshan [State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing (China); Zhang, Kejiang [Xinjiang Research Center of Water and Wastewater Treatment, Xinjiang Deland Co., LTD., Urumqi (China)

2012-10-15

254

PAHs contamination and bacterial communities in mangrove surface sediments of the Jiulong River Estuary, China.  

Science.gov (United States)

Sixteen sediment samples collected from eight transects in a mangrove swamp of the Jiulong River Estuary, Fujian, China were investigated for their content of polycyclic aromatic hydrocarbons (PAHs) and the biodegradation potential of the indigenous microorganisms. The bacterial community structures in the mangrove sediments and in enrichment cultures were also investigated. The results showed that the total PAHs concentration of mangrove sediments ranged from 280 to 1074 ng g(-1) dry weight, that the PAHs composition pattern in the mangrove sediments was dominated by high molecular weight PAH components (4-6 rings), and that Benzo[ghi]perylene and Indeno[1,2,3-cd]pyrene were the most dominant at different stations. Abundant PAH-degrading bacteria were found in all the stations, the values of phenanthrene-degrading bacteria ranged from 5.85 x 10(4) to 7.80 x 10(5) CFU g(-1) dry weight, fluoranthene-degrading bacteria ranged from 5.25 x 10(4) to 5.79 x 10(5) CFU g(-1) dry weight, pyrene-degrading bacteria ranged from 3.10 x 10(4) to 6.97 x 10(5) CFU g(-1) dry weight and the benzo(a)pyrene-degrading bacteria ranged from 5.25 x 10(4) to 7.26 x 10(5) CFU g(-1) dry weight. DGGE analysis of PCR-amplified 16S rDNA gene fragments confirmed that there was a remarkable shift in the composition of the bacterial community due to the addition of the different model PAH compound phenanthrene (three ring PAH), fluoranthene(four ring PAH), pyrene(four ring PAH) and benzo(a)pyrene(five ring PAH) during enrichment batch culture. Eleven strains were obtained with different morphology and different degradation ability. The presence of common bands for microbial species in the cultures and in the native mangrove sediment DNA indicated that these strains could be potential in situ PAH-degraders. PMID:18439626

Tian, Y; Liu, H J; Zheng, T L; Kwon, K K; Kim, S J; Yan, C L

2008-01-01

255

Magnetofossils as tracers of oxygenation change: a case study from the stratified Pettaquamscutt River Estuary  

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Magnetotactic bacteria (MB) are motile organisms commonly found around the oxic-anoxic-interface (OAI) in sediments and stratified water columns. Magnetite and greigite crystals synthesized by MB intracellularly, termed magnetosomes, can be preserved in sediments as magnetofossils. Changes in OAI thickness (due to changes in temperature, clathrate dissociation & methane oxidation, organic carbon supply/oxidation, or sedimentation rate) would produce proportional changes in MB population and sedimentary magnetofossil concentration. While potentially useful as an oxygenation proxy, magnetofossil quantification techniques and variables controlling their preservation in sediments need to be better understood. Most prior work focused on cultured magnetite-MB and sediment mixtures while studies of greigite-MB (found just below the OAI in the sulfidic hypolimnion) is lacking because axenic cultures do not exist. To address these issues, we study wild magnetite- and greigite-MB from the seasonally stratified Pettaquamscutt River Estuary Upper Basin (RI, USA) as a function of water depth, d. Transmission electron microscope imaging of 21 MB (377 magnetosomes) revealed a complexity in wild MB not found in cultures. From d=3.9 m-7.0 m, live-cell assays confirmed the presence of multiple MB morphotypes, both north- (majority) and south-seeking (minority), and a few magnetic protists. Based on a previous microscopy study just 1.4 km south of Upper Basin (Bazylinski et al., 1995), magnetite-MB are expected for d6.0 m. Coercivity distributions for all depths are characterized by a small variance, reflecting uniformity in magnetosome size. Interestingly, despite changing from dominant magnetite to greigite-MB with increasing depth, the median coercivity remained largely unchanged. Median coercivity is therefore not diagnostic of magnetosome mineralogy. We also report ferromagnetic resonance spectroscopy (FMR) results. The first derivative of the absorption spectra for dmultiple low-field maxima, which is consistent with observations from magnetite-MB cultures. In contrast, only one maximum in the spectra was observed for 6.0 m

Chen, A. P.; Berounsky, V. M.; Chan, M. K.; Moskowitz, B. M.; Andrade Lima, E.; Kopp, R. E.; Cady, C.; Weiss, B. P.; Hesse, P. P.

2013-12-01

256

High CO2 emissions from the tropical Godavari estuary (India) associated with monsoon river discharges  

Science.gov (United States)

Estuaries have been under sampled to establish them as sources or sinks of the atmospheric carbon dioxide. Such poor coverage is well known for tropical, particularly monsoon driven, estuaries. In an attempt to study the variability in CO2 in a tropical monsoon estuary we made systematic time-series observations in the Gautami Godavari estuarine system in the east coast of India. Our 18 month-long extensive monitoring in the tropical Godavari estuarine system revealed pH >7.8 during dry period that decreased by 1.5 ± 0.01 during peak discharge period. The decrease in pH was associated with high nutrients and bacterial activities suggesting significant organic carbon decomposition. High bacterial respiration (20.6 ± 7.2 ?MC l-1 d-1) in the estuary resulted in very high pCO2 of ˜30,000 ?atm during peak discharge period, which otherwise were <500 ?atm during dry period. Such high pCO2 levels were unknown to occur in any aquatic region. Several major and minor estuaries flow into the northern Indian Ocean from the Indian subcontinent and the monsoon associated processes make these systems chimney for emitting CO2 to atmosphere unrealized hitherto.

Sarma, V. V. S. S.; Kumar, N. A.; Prasad, V. R.; Venkataramana, V.; Appalanaidu, S.; Sridevi, B.; Kumar, B. S. K.; Bharati, M. D.; Subbaiah, C. V.; Acharyya, T.; Rao, G. D.; Viswanadham, R.; Gawade, L.; Manjary, D. T.; Kumar, P. P.; Rajeev, K.; Reddy, N. P. C.; Sarma, V. V.; Kumar, M. D.; Sadhuram, Y.; Murty, T. V. R.

2011-04-01

257

Eelgrass Enhancement and Restoration in the Lower Columbia River Estuary, Period of Performance: Feb 2008-Sep 2009.  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study was to evaluate the ability to enhance distribution of eelgrass (Zostera marina) in the Columbia River Estuary to serve as refuge and feeding habitat for juvenile salmon, Dungeness crab, and other fish and wildlife. We strongly suspected that limited eelgrass seed dispersal has resulted in the present distribution of eelgrass meadows, and that there are other suitable places for eelgrass to survive and form functional meadows. Funded as part of the Bonneville Power Administration's call for Innovative Projects, we initiated a multistage study in 2008 that combined modeling, remote sensing, and field experimentation to: (1) Spatially predict habitat quality for eelgrass; (2) Conduct experimental plantings; and (3) Evaluate restoration potential. Baseline in-situ measurements and remote satellite observations were acquired for locations in the Lower Columbia River Estuary (LCRE) to determine ambient habitat conditions. These were used to create a habitat site-selection model, using data on salinity, temperature, current velocity, light availability, wave energy, and desiccation to predict the suitability of nearshore areas for eelgrass. Based on this model and observations in the field, five sites that contained no eelgrass but appeared to have suitable environmental conditions were transplanted with eelgrass in June 2008 to test the appropriateness of these sites for eelgrass growth. We returned one year after the initial planting to monitor the success rate of the transplants. During the year after transplanting, we carried out a concurrent study on crab distribution inside and outside eelgrass meadows to study crab usage of the habitat. One year after the initial transplant, two sites, one in Baker Bay and one in Young's Bay, had good survival or expansion rates with healthy eelgrass. Two sites had poor survival rates, and one site had a total loss of the transplanted eelgrass. For submerged aquatic vegetation (SAV) restoration projects, these are reasonable success results and represent a small net gain in eelgrass in the LCRE. Crabs used both the eelgrass and unvegetated substrate, though in neither were there great abundance of the young-of-the-year crabs. During the field assessment of 12 potential transplant sites, divers discovered one site in southern Young's Bay that contained a previously undocumented eelgrass bed. This integrated project developed the first predictive maps of sites suitable for eelgrass and other SAV in the lower estuary. In addition, techniques developed for this project to assess light levels in existing and potential submerged habitats have great potential to be used in other regions for nearshore and coastal monitoring of SAV. Based on these preliminary results, we conclude that eelgrass distribution could likely be expanded in the estuary, though additional information on current eelgrass locations, usage by species of interest, and monitoring of current conditions would help develop a baseline and verify benefit. Our recommendations for future studies include: (1) Site Monitoring. Continued monitoring of restoration sites along with physical metrics of light, temperature and salinity within beds. Continued monitoring will both assist managers in understanding the longevity and expansion rate of planted sites and inform practical guidance on the minimum planted eelgrass required to develop a resilient meadow. (2) Natural bed documentation and monitoring. Document current eelgrass habitat conditions in the Columbia River by mapping eelgrass and other SAV species and monitoring physical metrics in natural beds. This will assist by better defining the factors that control the annual and spatial variation in eelgrass in the estuary, and thus lead to improved management. Improved information on conditions will help refine a habitat suitability model that can more accurately predict where eelgrass can be restored or areas under duress. (3) Monitor Species Use. Expanded monitoring of Dungeness crab and salmon use and benefit from eelgrass in the estuary t

Judd, C.; Thom, R; Borde, A. [Pacific Northwest National Laboratory

2009-09-08

258

Evaluation of HCMM satellite data for estuarine tidal circulation patterns and thermal inertia soil moisture measurements. [Delaware Bay, Cooper River, and the Potomac River estuaries; Luverne, Minnesota, soil moisture, and water temperature of Lake Anna, Virginia  

Science.gov (United States)

Digital thermal maps of the Cooper River (SC) and the Potomac River estuaries were prepared from heat capacity mapping radiometer (HCMR) tapes. Tidal phases were correctly interpreted and verified. Synoptic surface circulation patterns were charted by location thermal fronts and water mass boundaries within the estuaries. Thermal anomalies were detected adjacent of a conventional power plant on the Potomac. Under optimum conditions, estuaries as small as the Cooper River can be monitored for generalized thermal/tidal circulation patterns by the HCMM-type IR sensors. The HCMM thermal inertia approach to estimating soil moisture at the Luverne (MN) test site was found to be unsatisfactory as a NESS operational satellite technique because of cloud cover interference. Thermal-IR data show similar structure of the Baltimore and Washington heat islands when compared to NOAA AVHRR thermal-IR data. Thermal anomalies from the warm water discharge water of a nuclear power plant were mapped in Lake Anna, Virginia.

Wiesnet, D. R.; Mcginnis, D. F., Jr. (principal investigators); Matson, M.; Pritchard, J. A.

1981-01-01

259

INVESTIGATIONS INTO THE EFFECTS OF SEASON AND WATER QUALITY ON OYSTERS (CRASSOSTREA VIRGINICA) AND ASSOCIATED FISH ASSEMBLAGES IN THE CALOOSAHATCHEE RIVER ESTUARY, FLORIDA: IMPLICATIONS OF ALTERED FRESHWATER INFLOW  

Science.gov (United States)

A suite of biological and ecological responses of a Valued Ecosystem Component species, Crassostrea virginica, was used to investigate ecosystem-wide health effects of watershed alterations in the Caloosahatchee River estuary, Florida. The influence of water quality and season on...

260

The N-isotope effect and fractionation of nitrification in the tidal influenced Elbe River estuary, Germany  

Science.gov (United States)

Estuaries act as a nutrient filter for coastal waters. The eutrophic Elbe River estuary is loaded with fertilizer-derived nitrogen, but management efforts have started to reduce this load effectively. However, an internal nitrate source in turn gained in importance and the estuary changed from a sink to a source of reactive nitrogen. Nitrification plays a key role in this estuarine nutrient regeneration but has to be quantified. The aim of our study was to assess the impact of nitrification on seasonal nitrogen loads and turnover using stable N- isotopes to identify the natural fractionation factor of nitrification. Therefor we measured the dissolved inorganic nitrogen (ammonium, nitrite and nitrate), their stable isotope signatures and the in-situ nitrification rates in the tidal influenced part of the river during 9 cruises from August 2011 to August 2013. The DIN load was higher in winter than in summer, the main compound was nitrate. In summer concentrations of nitrate entering the estuary were between 50 and 100 ?M and ?15N and ?18O were enriched to 15.5 to 21.5 o and 7.5 to 11.5 o respectively. Strong nitrification was found in the Hamburg port region. The nitrate concentrations increased significantly downstream after the port of Hamburg, along with a decrease of isotope values. Ammonium and nitrite peaked in the Hamburg port region with up to 25 ?M and 12 ?M, respectively. In July 2013, ?15N of ammonium has shown a mean value of 16.2±3.3 o and nitrite of -9.8±4.7 ‰The N-fractionation of nitrification in July 2013 was 15?nit -10o the sub-process ammonia oxidation 15?amox-24o and the nitrite oxidation of 15?niox 13o while fractionation was less pronounced during the other cruises Our data show that N-isotope fractionation generally confirmed culture experiments, but that it strongly depended on discharge, availability of substrate, temperature and the coupling of ammonia and nitrite oxidation.

Sanders, Tina; Dähnke, Kirstin

2014-05-01

261

Polycyclic aromatic hydrocarbons in sediments from the Old Yellow River Estuary, China: occurrence, sources, characterization and correlation with the relocation history of the Yellow River.  

Science.gov (United States)

The levels of 16 USEPA priority PAHs were determined in surface sediments and one dated sediment core from the abandoned Old Yellow River Estuary, China. Total PAH concentrations in the surface sediments ranged from 100.4 to 197.3 ng g(-1) dry weight and the total toxic equivalent quantity (TEQ(carc)) values of the carcinogenic PAHs were very low. An evaluation of PAH sources based on diagnostic ratios and principal component analysis suggested that PAHs in the surface sediments mainly derived from combustion sources. The total PAH concentrations altered significantly with year of deposition and showed quite different patterns of change compared with other studies: it is hypothesized that the principal cause of these changes is the relocation of the course of the Yellow River to the sea in 1976 and 1996. PMID:25203973

Yuan, Zijiao; Liu, Guijian; Wang, Ruwei; Da, Chunnian

2014-11-01

262

226Ra behavior in the Pee Dee river-Winyah Bay estuary  

International Nuclear Information System (INIS)

Concentrations of dissolved 226Ra in Winyah Bay, South Carolina, and in the adjacent Atlantic Ocean are augmented by the desorption of radium from sediments in the low-salinity area of the estuary and diffusion from bottom sediments. Desorption of 226Ra is reflected by lower concentrations in suspended sediments from higher-salinity regions of the estuary. Bottom sediments from the high-salinity region have lower 226Ra/230Th activity ratios than those from the low-salinity end. (orig./ME)

263

A model study of the effects of river discharges and interannual variation of winds on the plume front in winter in Pearl River Estuary  

Science.gov (United States)

A three-dimensional numerical model, Estuarine, Coastal and Ocean Modeling System with Sediments (ECOMSED), is employed to study the mechanism of plume front in the Pearl River Estuary (PRE) in detail. The model is forced by winds, tides and river discharges. The modeled results of tidal elevation, current velocity and salinity are in reasonable agreement with observational data in the PRE. By analyzing momentum and saltwater transport balance equations, it is found that the wind stress term, the pressure gradient term and the local time derivative term of velocity are dominant in the momentum equation, while the local time derivative term, the horizontal advective term and the vertical mixing term of salinity are dominant in the salinity transport equation. The residual current at surface along the plume front is seaward and stronger, whilst that in the bottom layer is mainly landward. A series of sensitive experiments is also run to examine the responses of plume front to changes of river discharges at different inlets in Lingdingyang Bay and interannual variation of northeast winds in winter. The location of plume front responds differently to the change of river discharge at different inlets. An increase in the river discharge at Dahu inlet seems to affect the location of plume front most among the four river inlets, it makes the plume front move eastward and southward wholly; the variation of river discharge at Nansha or Fengmamiao inlet on the location of plume front is more local and weaker; whilst the variation of river discharge at Hengmen inlet has little effect on the plume front. The location of plume front also changes in response to the interannual variation of northeast winds in winter, the stronger or the more eastward the winds are, the more westward the plume front moves, and only in the northern PRE, the response of plume front to the variation of wind speeds is largely different from that to the variation of wind directions.

Zheng, Shu; Guan, Weibing; Cai, Shuqun; Wei, Xing; Huang, Daji

2014-02-01

264

Evaluation of the Ecotoxicity of Sediments from Yangtze River Estuary and Contribution of Priority PAHs to Ah Receptor-Mediated Activities  

Science.gov (United States)

In this study, in vitro bioassays were performed to assess the ecotoxicological potential of sediments from Yangtze River estuary. The cytotoxicity and aryl hydrocarbon receptor (AhR)-mediated toxicity of sediment extracts with rainbow trout (Oncorhynchus mykiss) liver cells were determined by neutral red retention and 7-ethoxyresorufin-O-deethylase assays. The cytotoxicity and AhR-mediated activity of sediments from the Yangtze River estuary ranged from low level to moderate level compared with the ecotoxicity of sediments from other river systems. However, Yangtze River releases approximately 14 times greater water discharge compared with Rhine, a major river in Europe. Thus, the absolute pollution mass transfer of Yangtze River may be detrimental to the environmental quality of estuary and East China Sea. Effect-directed analysis was applied to identify substances causing high dioxin-like activities. To identify unknown substances contributing to dioxin-like potencies of whole extracts, we fractionated crude extracts by open column chromatography. Non-polar paraffinic components (F1), weakly and moderately polar components (F2), and highly polar substances (F3) were separated from each crude extract of sediments. F2 showed the highest dioxin-like activities. Based on the results of mass balance calculation of chemical toxic equivalent concentrations (TEQs), our conclusion is that priority polycyclic aromatic hydrocarbons indicated a low portion of bio-TEQs ranging from 1% to 10% of crude extracts. Further studies should be conducted to identify unknown pollutants. PMID:25111307

Liu, Li; Chen, Ling; Shao, Ying; Zhang, Lili; Floehr, Tilman; Xiao, Hongxia; Yan, Yan; Eichbaum, Kathrin; Hollert, Henner; Wu, Lingling

2014-01-01

265

Distribution and community structure of fish in Obitsu-gawa River Estuary of inner Tokyo Bay, central Japan  

Directory of Open Access Journals (Sweden)

Full Text Available The distribution and community structure of fish in Obitsu-gawa River Estuary of inner TokyoBay, central Japan was studied from May to December 2005 and March to April 2006. A total of 19,006individuals, represented by 25 species and some unidentified species under family Clupeidae, Cyprinidae,Gobiidae, Hemiramphidae, Mugilidae, Platycephidae, Pleuronectidae and Triglidae were collected. FamilyGobiidae had the most number of taxa with 13 genera and 10 species. Greatest fish abundancehappened in August and secondarily in April and May. Species richness was evident in the warmermonths particularly in May (17 taxa, August (21 taxa, September (15 taxa and October (17 taxa.Marine teleosts significantly contributed to the species richness and abundance of fish, whichcorresponded to 52.9% (10,046 individuals of the total catch while the estuarine fishes were the secondmost abundant group with 33.5% (6,372 individuals of the total catch. Species dominance was acoherent feature of this community. The proportional contribution of marine teleosts to the fishcommunity decreased with increase distance upstream while that of estuarine fishes increased withincrease distance upstream. The developmental stages of gobies range from larvae to adult but juvenilesconstitute 77.06% of the total sample. The distribution of developmental stage of estuarine gobies wasinfluenced to a greater extent by variation in monthly water temperature and station or the interaction ofboth. Adult estuarine gobies had the tendency to aggregate in the middle estuary reflecting their hightolerance to a wide range of water salinity inherent in this station but avoided the lower estuary mostlikely due to the predominance of high salinity waters.

Joeppette J. Hermosilla

2012-09-01

266

In situ fate and partitioning of waterborne perfluoroalkyl acids (PFAAs) in the Youngsan and Nakdong River Estuaries of South Korea.  

Science.gov (United States)

Concentrations, distributions, fate, and partitioning of perfluoroalkyl acids (PFAAs) were investigated in surface water (n=34) collected from the Youngsan and Nakdong River Estuaries of South Korea. Thirteen individual PFAAs in water and suspended solids (SS) were quantified by use of HPLC-MS/MS. PFAAs were detected in all samples, which indicated that they were widely distributed in the study area. Greater concentrations of PFAAs were found at some inland sites which seemed to be affected by direct input from point sources, such as wastewater treatment plants, and/or indirect diffusive sources, such as surface runoff. Spatial distributions of PFAAs in estuaries along transects toward the open sea demonstrated that these chemicals were transported to the outer region primarily by water discharged during the rainy season. Field-based partition coefficients (K(d)) for long-chain PFAAs (C?8) were significantly correlated with salinity (r(2)=0.48 to 0.73, porganic contaminants, which indicated that adsorption of PFAAs is largely associated with salinity. Overall, the results of the present study will provide better understanding of the fate and transport of PFAAs in the zone of salinity boundary that can be used for developing fate models of PFAAs in the coastal marine environment. PMID:23333509

Hong, Seongjin; Khim, Jong Seong; Park, Jinsoon; Kim, Minhee; Kim, Woong-Ki; Jung, Jinho; Hyun, Seunghun; Kim, Jeong-Gyu; Lee, Hyojin; Choi, Heeseon J; Codling, Garry; Giesy, John P

2013-02-15

267

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

268

Biological effects of simulated discharge plume entrainment at Indian Point Nuclear Power Station, Hudson River estuary, USA  

International Nuclear Information System (INIS)

Laboratory and field simulations of the discharge plume entrainment of phytoplankton, zooplankton and fish were carried out at the Indian Point Nuclear Station, Hudson River estuary, USA. Phytoplankton assemblages studied on two dates produced different response patterns measured as photosynthetic activity. Chlorophyll-a levels did not change following simulated entrainment. Possible explanations for the differences are discussed. The two abundant copepods Acartia tonsa and Eurytemorta affinis appear to tolerate exposure to discharge plume ?T without adverse effects. Copepods subjected to plume entrainment may suffer considerable mortality during periods of condenser chlorination. In general, the amphipod Gammarus spp. did not appear to suffer significant mortality during simulated entrainment. Juvenile striped bass, Morone saxatilis, were not affected by simulated plume transit before and during plant condenser chlorination; however, a simulated ''worst possible case'' plume ?T produced statistically significant moralities. (author)

269

The 137Cs distribution in sediment profiles from the Yangtze River estuary: a comparison of modeling and experimental results  

International Nuclear Information System (INIS)

It has been generally accepted when estimating sedimentation rates using the 137Cs dating method that the position of the 137Cs maximum in a sediment profile represents the year 1963. In this paper we validated this approach by developing a model in which the annual 137Cs global fallout flux for the Yangtze River estuary was established on the basis of the Tokyo flux corrected for precipitation rates observed in Shanghai. As the 137Cs maxima in the sediment deposition profiles depend on the sedimentation rates, the sub-sampling intervals were calculated accordingly. Higher measured than the calculated values were found in some cores, what may be due to fluctuating sedimentation rates and an additional deposition of 137Cs from land-based sources. The study provides useful information on the reliability of the measured 137Cs maxima in sediment profiles frequently used for dating of sediments in marine (coastal regions, open seas) as well as in terrestrial (lakes) environments. (author)

270

Non-aromatic hydrocarbons in surface sediments near the Pearl River estuary in the South China Sea.  

Science.gov (United States)

Surface sediment samples at 4 sites along an offshore transect from outer continental shelf off the Pearl River estuary to the shelf slope region of the northern South China Sea, have been analyzed for total organic carbon (TOC), total nitrogen (TN), solvent extractable organic matter (EOM) and non-aromatic hydrocarbons. TOC, TN and EOM show distinct spatial variations. Their highest values are all recorded at the shelf slope region. EOM varies from 18.70-38.58 microgg(-1) dry sediment and accounts for 0.20-0.72% of the TOC contents. The non-aromatic hydrocarbons are an important fraction of EOM. Their contents range from 3.43-7.06 microgg(-1) dry sediment. n-Alkanes with carbon number ranging from 15-38 are identified. They derive from both biogenic and petrogenic sources in different proportions. Results of isoprenoid hydrocarbons, hopanes and steranes also suggest possible petroleum contamination. PMID:17240011

Gao, Xuelu; Chen, Shaoyong; Xie, Xueliang; Long, Aimin; Ma, Fujun

2007-07-01

271

Tissue distribution and fate of persistent organic pollutants in Indo-Pacific humpback dolphins from the Pearl River Estuary, China.  

Science.gov (United States)

Eleven persistent organic pollutant (POP) compounds including ?PCBs, ?DDTs, ?HCHs, aldrin, mirex, endrin, ?CHLs, dieldrin, HCB, heptachlor and pentachlorobenzene were measured in the kidney, liver, muscle, melon and other tissues of Sousa chinensis stranded on the western coast of the Pearl River Estuary in China during 2007-2013. For most parameters of POPs measured, melon tissues contained the highest mean concentrations with the exception of aldrin, which was higher in the kidney and liver tissues. The concentrations of PCBs, DDTs, heptachlor and endrin in the melon tissue exhibited significant correlations with body length, whereas PCBs and heptachlor also displayed significant regression with age. Our studies showed hepatic concentrations of ?DDTs, ?HCHs and mirex in S. chinensis were generally higher than those found in cetaceans from other geographic locations. The high levels of POP residues in the testis of one male dolphin suggested an increasing risk of infertility in the species. PMID:25066456

Gui, Duan; Yu, Riqing; He, Xuan; Tu, Qin; Wu, Yuping

2014-09-15

272

Fish community changes in the St. Louis River estuary, Lake Superior, 1989-1996: Is it ruffe or population dynamics?  

Science.gov (United States)

Ruffe (Gymnocephalus cernuus) have been implicated in density declines of native species through egg predation and competition for food in some European waters where they were introduced. Density estimates for ruffe and principal native fishes in the St. Louis River estuary (western Lake Superior) were developed for 1989 to 1996 to measure changes in the fish community in response to an unintentional introduction of ruffe. During the study, ruffe density increased and the densities of several native species decreased. The reductions of native stocks to the natural population dynamics of the same species from Chequamegon Bay, Lake Superior (an area with very few ruffe) were developed, where there was a 24-year record of density. Using these data, short- and long-term variations in catch and correlations among species within years were compared, and species-specific distributions were developed of observed trends in abundance of native fishes in Chequamegon Bay indexed by the slopes of densities across years. From these distributions and our observed trend-line slopes from the St. Louis River, probabilities of measuring negative change at the magnitude observed in the St. Louis River were estimated. Compared with trends in Chequamegon Bay, there was a high probability of obtaining the negative slopes measured for most species, which suggests natural population dynamics could explain, the declines rather than interactions with ruffe. Variable recruitment, which was not related to ruffe density, and associated density-dependent changes in mortality likely were responsible for density declines of native species.

Bronte, Charles R.; Evrard, Lori M.; Brown, William P.; Mayo, Kathleen R.; Edwards, Andrew J.

1998-01-01

273

Analyses of elutriates, native water, and bottom material in selected rivers and estuaries in western Oregon and Washington  

Science.gov (United States)

Chemical analyses of elutriates, bottom sediment and water samples for selected metals, nutrients and organic compounds including insecticides and herbicides have been made to provide data to determine short-term water quality conditions associated with dredging operations in rivers and estuaries. Between May and December 1980 data were collected as far south as the Coos River in Western Oregon, as far north as Baker Bay in Southwestern Washington and as far inland as Bonneville Dam on the Columbia River. In an elutriation test, bottom material from a dredging site is mixed with native water and the filtrate is analysed. Elutriation test results showed variability in concentrates of dissolved chemicals as follows: in micrograms per liter (micro g/l), manganese ranged from 0 to 10,000, iron from 10 to 4300, zinc from 1 to 90, and phenols from 9 to 420; in milligrams per liter (mg/l), ammonia as nitrogen ranged from 0.03 to 46 and organic carbon from 0.5 to 45. (USGS)

Fuhrer, Gregory J.; Rinella, Frank A.

1983-01-01

274

The diverse species of the genus Hantzschia (Bacillariophyta in sand flats of the Nakdong River estuary in Korea  

Directory of Open Access Journals (Sweden)

Full Text Available To collect the diatom species belonging to the genus Hantzschia, bottom sediments were collected from 32 sampling sites in 23 sand-flat areas in the intertidal zone and river reaches of Nakdong River estuary, Korea. The sand sediments contained a total of 19 species of genus Hantzschia, Hantzschia amphioxys (Ehrenberg Grunow, H. amphioxys f. capitata O. Müller, H. baltica Simonsen, H. distinctepunctata (Hustedt Hustedt, H. elegantula (Østrup Witkowski et al., H. longiareolata Garcia-Baptista, H. marina (Donkin Grunow, H. pseudomarina Hustedt, H. virgata (Roper Grunow, H. virgata var. gracilis Hustedt, H. virgata var. kariana Grunow, H. virgata var. leptocephala Østrup and H. weyprechtii Grunow, including six unconfirmed species. Eleven Hantzschia species are reported as new to Korea. Hantzschia virgata, its infraspecies, and neighboring speceis showed large morphological variations within a single species or among the closely related species. Hantzschia amphioxys, H. distinctepunctata, and H. virgata var. leptocephala prefer freshwater habitats in the upper reaches of the river, while others occurred mainly in the sand flats composed of coarse sand in the intertidal area. In the estuarine sediments, the Hantzschia taxa are classified to be typical sand-attached forms.

Gyeongje Joh

2014-12-01

275

Shoreline-change Rates of the Barrier Islands in Nakdong River Estuary Using Aerial Photography and SPOT-5 Image  

Directory of Open Access Journals (Sweden)

Full Text Available Shoreline data of the barrier islands in Nakdong River Estuary for the last three decades wereassembled using six sets of aerial photographs and seven sets of satellite images. Canny Algorithm wasapplied to untreated data in order to obtain a wet-dry boundary as a proxy shoreline. Digital ShorelineAnalysis System (DSAS 4.0 was used to estimate the rate of shoreline changes in terms of five statisticalvariables; SCE (Shoreline Change Envelope, NSM (Net Shoreline Movement, EPR(End Point Rate, LRR(Linear Regression Rate, and LMS (Least Median of Squares. The shoreline in Jinwoodo varieddifferently from one place to another during the last three decades; the west tail has advanced (i.e., seawardor southward, the west part has regressed, the south part has advanced, and the east part has regressed.After the 2000s, the rate of shoreline changes (?2.5~6.7 m/yr increased and the east advanced. Theshoreline in Shinjado shows a counterclockwise movement; the west part has advanced, but the east part hasretreated. Since Shinjado was built in its present form, the west part became stable, but the east part hasregressed faster. The rate of shoreline changes (?16.0~12.0 m/yr in Shinjado is greater than that ofJinwoodo. The shoreline in Doyodeung has advanced at a rate of 31.5 m/yr. Since Doyodeung was built inits present form, the south part has regressed at the rate of "18.2 m/yr, but the east and west parts haveadvanced at the rate of 13.5~14.3 m/yr. Based on Digital Shoreline Analysis, shoreline changes in thebarrier islands in the Nakdong River Estuary have varied both temporally and spatially, although the exactreason for the shoreline changes requires more investigation.

Sang-Hun Jeong

2013-03-01

276

A multi-band semi-analytical algorithm for estimating chlorophyll-a concentration in the Yellow River Estuary, China.  

Science.gov (United States)

In this study, two sample semi-analytical algorithms and one new unified multi-band semi-analytical algorithm (UMSA) for estimating chlorophyll-a (Chla) concentration were constructed by specifying optimal wavelengths. The three sample semi-analytical algorithms, including the three-band semi-analytical algorithm (TSA), four-band semi-analytical algorithm (FSA), and UMSA algorithm, were calibrated and validated by the dataset collected in the Yellow River Estuary between September 1 and 10, 2009. By comparing of the accuracy of assessment of TSA, FSA, and UMSA algorithms, it was found that the UMSA algorithm had a superior performance in comparison with the two other algorithms, TSA and FSA. Using the UMSA algorithm in retrieving Chla concentration in the Yellow River Estuary decreased by 25.54% NRMSE (normalized root mean square error) when compared with the FSA algorithm, and 29.66% NRMSE in comparison with the TSA algorithm. These are very significant improvements upon previous methods. Additionally, the study revealed that the TSA and FSA algorithms are merely more specific forms of the UMSA algorithm. Owing to the special form of the UMSA algorithm, if the same bands were used for both the TSA and UMSA algorithms or FSA and UMSA algorithms, the UMSA algorithm would theoretically produce superior results in comparison with the TSA and FSA algorithms. Thus, good results may also be produced if the UMSA algorithm were to be applied for predicting Chla concentration for datasets of Gitelson et al. (2008) and Le et al. (2009). PMID:25630126

Chen, Jun; Quan, Wenting; Cui, Tingwei

2015-01-01

277

Pathways of organic matter through food webs of diverse habitats in the regulated Nakdong River estuary (Korea)  

Science.gov (United States)

The benthic macroinvertebrates of the Nakdong River estuary were sampled at three different habitats: two salt marsh ( Scirpus triqueter and Phragmites australis) beds and a bare intertidal flat. Fishes were sampled in the main channel. The trophic importance of marsh vascular plants, microphytobenthos, and riverine and channel particulate organic matter to macroinvertebrate and fish production was studied using stable carbon and nitrogen isotope tracers. There was a dramatic change in coverage of macrophytes (salt marshes and seagrass) after the construction of an estuarine barrage in 1987 in the Nakdong River estuary, with the S. triqueter bed increasing, the P. australis bed decreasing, and Zostera marina habitats being nearly lost. Although the invertebrate ? 13C were within a narrower range than those of the primary producers, the values varied considerably among consumers in these habitats. However, the isotope signatures of consumers showed similarities among different habitats. Cluster analysis based on their isotopic similarity suggested that the isotope variability among species was related more to functional feeding groups than to habitats or taxonomic groups. While ? 13C values of suspension feeders were close to that of the channel POM (mainly phytoplankton), other benthic feeders and predators had ? 13C similar to that of microphytobenthos. Isotopic mixing model estimates suggest that algal sources, including microphytobenthos and phytoplankton, play an important role in supporting the benthic food web. Despite the huge productivity of emergent salt marshes, the contribution of the marsh-derived organic matter to the estuarine food webs appears to be limited to some nutrition for some invertebrates just within marsh habitats, with little on the bare intertidal flats or in the channel fish communities. Isotope signatures of the channel fishes also confirm that algal sources are important in supporting fish nutrition. Our findings suggest that benthic and pelagic microalgae made a large contribution to consumer diets, while marsh plants may not have a large role in supporting food webs in this estuarine system.

Choy, Eun Jung; An, Soonmo; Kang, Chang-Keun

2008-06-01

278

Distribuição de elementos tóxicos no estuário do rio Amazonas / Toxic elements distribution in the Amazon River estuary  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A presença de elementos não essenciais nas águas superficiais do rio Amazonas é uma preocupação global, o objetivo da pesquisa foi estudar a distribuição dos elementos As, Al, Mn, e Pb na água do estuário do rio Amazonas. As amostras foram coletadas em três regiões distintas: Canal Norte (AP), Canal [...] Sul (PA) e rio Pará (PA) em três profundidades, com um total de 84 amostras. A espectrometria de emissão atômica com plasma indutivamente acoplado (ICPAES) foi utilizada para avaliar os teores de Al, Mn e Pb e a espectrofotometria de absorção atômica com geração de hidretos (HGAAS) foi usada para a análise do As. O As variou de Abstract in english The non-essential elements found in the superficial waters of the Amazon River is a global worry since the local hydric resources represent the world's largest fresh water reservoir. This research aimed at studying the occurrence of As, Al, Mn and Pb in the waters of the Amazon River estuary. The 84 [...] samples in three depths were collected in three different regions: North Channel of the Amazon River, in the state of Amapá; South Channel of the Amazon River, in the state of Pará; and Pará River, also in the state of Pará. Inductively coupled plasma atomic emission spectrometry (ICPAES) method was employed to determine the concentrations of Al, Mn and Pb in the samples while hydride generation atomic absorption spectrometry (HGAAS) method was employed in determining their As concentrations. As concentrations varied from

Simone de Fátima Pinheiro, Pereira; Otílio Othon, Pires; Augusto Fonseca, Saraiva; Geiso Rafael, Oliveira; Pedro Moreira de, Sousa Junior; Rafaella Galvão, Miranda; Cleber Silva e, Silva; Reginaldo da Silva, Sales.

279

Effects of runoff changes and sea level rise on salinity in the Delaware River estuary  

Science.gov (United States)

The objective of this study is to investigate changes in the spatial distribution of salt in the Delaware Estuary resulting from climate induced changes in freshwater inflows and in the position of mean sea level. The approach adopted for this study is composed of two parts: An analysis of existing physical data in order to derive a basic understanding of the salt dynamics, and numerical simulation of future conditions based upon this analysis.

Walters, Roy A.

1989-01-01

280

Seasonal effects of wastewater to the water quality of the Caeté river estuary, Brazilian Amazon.  

Science.gov (United States)

Bragança's socioeconomic situation is highly dependent on estuarine and marine biological resources that are influenced by tidal cycles and climatology. Field measurements (hydrological, hydrodynamic and microbiological variables) were taken in the most urbanized zone from Caeté estuary to characterise the quality of the local environment. During the dry period, the estuary was more eutrophic and presented the highest temperature (30.5 degrees C in Oct./06), salinity (17 psu in Feb./07), pH (8.24 in Feb./07) and fecal coliform (> 1000 MPN/100 ml in Dec./06 and Feb./07) values. The phytoplankton Cyclotella meneghiniana, Coscinodiscus centralis and other r-strategist species were observed. The lack of basic hydric canalization was responsible for the local contamination, especially during the dry period when more concentrated wastewater from the city was emitted into the estuary, showing the human influence on the reduction of local estuarine water quality. In Bragança, the fishery is considered one of the main economic activities so, this contamination is worrisome because a large part of the local economy depends on biological resources and, thus, the contamination could negatively affect the environmental health of this Amazon ecosystem. PMID:20563427

Pereira, Luci C C; Monteiro, Marcela C; Guimarães, Danielly O; Matos, Jislene B; Costa, Rauquírio M da

2010-06-01

281

[Contribution of different processes in wetland soil N2O production in different restoration phases of the Yellow River estuary, China].  

Science.gov (United States)

By using the method of time-space mutual substitution, the contribution of different processes in wetland soil N2O production was studied in the un-restoration wetland (R0), restoration wetland since 2007 (R2007) and restoration wetland since 2002 (R2002) of the Yellow River estuary to evaluate the effectiveness of the restoration projects. Results showed wetland soil total N2O production had a significant difference in different restoration phases, but the N2O release was the main source. The N2O production in restoration wetland was higher than that in un-restoration wetland. The N2O production wss mainly due to the nitrification and nitrifier denitrification processes, while the denitrification process had great weakening effects on N2O production, which was closely related to the physical and chemical properties of wetland soils in different restoration phases. The non-biological processes made greater contributions to N2O production and these were mainly due to that iron was reductive, while the Yellow River estuary was an area of highly active iron. Although N2O production in wetland soils was the results of biological processes combined with non-biological processes in different restoration phases, non-biological processes had larger influences and should be paid a special attention. There were different influences on wetland soil processes generating N2O between temperature and water content, indicating responses of soil microbial activities to temperature and water content were different. In addition, the N2O production contents ranged from 0.37 +/- 0.08 nmol x (kg x h) (-1) to 9.75 +/- 7.64 nmol x (kg x h) (-1) in marshes of the Yellow River estuary, which was slightly higher than those in the S. alterniflora wetland soils of the Min River estuary, but significantly lower than those in the C. malaccensis wetland soils of the Min River estuary, the grassland soils and the aerobic forest soils. We found that the long-term implements of ecological restoration project in the Yellow River estuary obviously promoted N2O production, so we should consider two factors of landscape restoration and weakening greenhouse gases in the next wetland restoration project. PMID:25338387

Sun, Wen-Guang; Sun, Zhi-Gao; Gan, Zhuo-Ting; Sun, Wan-Long; Wang, Wei

2014-08-01

282

The source of natural and anthropogenic heavy metals in the sediments of the Minjiang River Estuary (SE China): implications for historical pollution.  

Science.gov (United States)

Two sedimentary cores in the Minjiang River estuary (SE China) are documented for grain size, clay minerals, heavy metals, magnetic parameters and Pb isotopes to investigate the source and historical variation of heavy metals. The MJK9 core was collected outside of the Minjiang River estuary, and the core is composed of mixed sediments, of which ~70% from the Yangtze River and 30% from the Minjiang River. It is thus difficult to be used for tracing the human activity along the Minjiang River. In contrast, the sediments of MJK16 core which was collected in a nearshore area are primarily from the Minjiang River. The enrichment factors of the sediments were mineral concentration and (206)Pb/(207)Pb and (206)Pb/(208)Pb of the sediments. We compared the Pb isotopic compositions between our results and those for the deposit mining in the Minjiang River basin, and aerosols and coal dust in south China, and considered that Pb in the sediments of the MJK16 core was derived primarily from weathered rocks as well as industrial emission (e.g. coal combustion). The sediments have anthropogenic Pb concentrations ranging from 6% in 1950 to 23.7% in 2010, consistent with the impact of rapid urban and industrial development in China. PMID:24995639

Xu, Yonghang; Sun, Qinqin; Yi, Liang; Yin, Xijie; Wang, Aijun; Li, Yunhai; Chen, Jian

2014-09-15

283

Size-fractionated thorium isotopes (228Th, 230Th, 232Th) in surface waters in the Jiulong River estuary, China  

International Nuclear Information System (INIS)

Thorium isotopes (228Th, 230Th, 232Th and 234Th) are useful tracers for studying particle dynamics and trace element scavenging in marine environments. In this study, surface waters were collected along a salinity gradient from the Jiulong River estuary, China, for determination of activity concentrations of 228Th, 230Th and 232Th in different size fractions, namely, the >53 ?m, 10-53 ?m, 2-10 ?m, 0.4-2 ?m, 10 kDa-0.4 ?m and the 228Th, 230Th and 232Th in the Jiulong River estuarine waters were significantly higher than most of the previously reported values in coastal and oceanic seawaters, suggesting a higher lithogenic U and Th contribution from the Jiulong River Basin. When normalized to the particulate mass concentration, the activity concentrations of the three thorium isotopes decreased with increasing particle size, demonstrating the important role of surface areas of particles in controlling the scavenging of thorium from the water column. The partitioning of three thorium isotopes showed a common characteristic, i.e., the >53 ?m fraction had the least share (0-1%), while the 10-53 ?m fraction had the largest share of Th isotopes. The average value of the 230Th/232Th activity ratio (230Th/232Th)A.R. increased from 0Th)A.R. increased from 0.8 in the >53 ?m fraction to 3.7 in the 10 kDa-0.4 ?m fraction, indicating that the radiogenic Th isotopes are preferentially scavenged by the small size particles. (230Th/232Th)A.R. in the 228Th had the highest concentration in the mid-salinity region, showing a non-conservative behavior with additional input. In contrast, dissolved 232Th showed a concave profile, indicating a net removal of 232Th during the mixing of fresh water with seawater. The behavior of Th isotopes in the <10 kDa fraction followed those in the dissolved phases. The difference in geochemical behaviors among three Th isotopes was ascribed to their different sources in the estuary

284

[Effects of macro-jellyfish abundance dynamics on fishery resource structure in the Yangtze River estuary and its adjacent waters].  

Science.gov (United States)

Based on the bottom trawl survey data in May 2007 and May and June 2008, this paper analyzed the effects of the abundance dynamics of macro-jellyfish on the species composition, distribution, and abundance of fishery resource in the Yangtze River estuary and its adjacent waters. From May 2007 to June 2008, the average catch per haul and the top catch per haul of macro-jellyfish increased, up to 222.2 kg x h(-1) and 1800 kg x h(-1) in June 2008, respectively. The macro-jellyfish were mainly distributed in the areas around 50 m isobath, and not beyond 100 m isobath where was the joint front of the coastal waters of East China Sea, Yangtze River runoff, and Taiwan Warm Current. The main distribution area of macro-jellyfish in June migrated northward, as compared with that in May, and the highest catches of macro-jellyfish in May 2007 and May 2008 were found in the same sampling station (122.5 degrees E, 28.5 degrees N). In the sampling stations with higher abundance of macro-jellyfish, the fishery abundance was low, and the fishery species also changed greatly, mainly composed by small-sized species (Trachurus japonicus, Harpadon nehereus, and Acropoma japonicum) and pelagic species (Psenopsis anomala, Octopus variabilis) and Trichiurus japonicus, and P. anomala accounted for 23.7% of the total catch in June 2008. Larimichthys polyactis also occupied higher proportion of the total catch in sampling stations with higher macro-jellyfish abundance, but the demersal species Lophius litulon was not found, and a few crustaceans were collected. This study showed that macro-jellyfish had definite negative effects on the fishery community structure and abundance in the Yangtze River estuary fishery ecosystem, and further, changed the energy flow patterns of the ecosystem through cascading trophic interactions. Therefore, macro-jellyfish was strongly suggested to be an independent ecological group when the corresponding fishery management measures were considered. PMID:22384604

Shan, Xiu-Juan; Zhuang, Zhi-Meng; Jin, Xian-Shi; Dai, Fang-Qun

2011-12-01

285

Temporal trends of hydrocarbons in sediment cores from the Pearl River Estuary and the northern South China Sea  

International Nuclear Information System (INIS)

Concentrations and fluxes of unresolved complex mixture of hydrocarbons (UCM) and polycyclic aromatic hydrocarbons (PAHs) were analyzed for two 210Pb dated sediment cores from the Pearl River Estuary (PRE) and the adjacent northern South China Sea (NSCS). Compound-specific stable carbon isotopic compositions of individual n-alkanes were also measured for identification of the hydrocarbon sources. The historical records of PAHs in the NSCS reflected the economic development in the Pearl River Delta during the 20th century. PAHs in the NSCS predominantly derive from combustion of coal and biomass, whereas PAHs in the PRE are a mixture of petrogenic and pyrogenic in origins. The isotopic profiles reveal that the petrogenic hydrocarbons in the PRE originate predominantly from local spillage/leakage of lube oil and crude oils. The accumulation rates of pyrogenic PAHs have significantly increased, whereas UCM accumulation has slightly declined in the NSCS in the recent three decades. - The accumulation rates of pyrogenic PAHs have significantly increased in the northern South China Sea in the recent decades

286

Elevated ammonium concentrations from wastewater discharge depress primary productivity in the Sacramento River and the Northern San Francisco Estuary.  

Science.gov (United States)

Primary production in the Northern San Francisco Estuary (SFE) has been declining despite heavy loading of anthropogenic nutrients. The inorganic nitrogen (N) loading comes primarily from municipal wastewater treatment plant (WTP) discharge as ammonium (NH(4)). This study investigated the consequences for river and estuarine phytoplankton of the daily discharge of 15 metric tons NH(4)-N into the Sacramento River that feeds the SFE. Consistent patterns of nutrients and phytoplankton responses were observed during two 150-km transects made in spring 2009. Phytoplankton N productivity shifted from NO(3) use upstream of the WTP to productivity based entirely upon NH(4) downstream. Phytoplankton NH(4) uptake declined downstream of the WTP as NH(4) concentrations increased, suggesting NH(4) inhibition. The reduced total N uptake downstream of the WTP was accompanied by a 60% decline in primary production. These findings indicate that increased anthropogenic NH(4) may decrease estuarine primary production and increase export of NH(4) to the coastal ocean. PMID:22236959

Parker, Alexander E; Dugdale, Richard C; Wilkerson, Frances P

2012-03-01

287

Tracking historical lead pollution in the coastal area adjacent to the Yangtze River Estuary using lead isotopic compositions  

International Nuclear Information System (INIS)

The rapid economic development in the Yangtze River Delta (YRD), China in the last three decades has had a significant impact on the environment of the East China Sea (ECS). Lead isotopic compositions of a 210Pb dated sediment core collected from the coastal ECS adjacent to the Yangtze River Estuary were analyzed to track the Pb pollution in the region. The baseline Pb concentration in the coastal ECS sediments before the industrialization in China was 32 ?g g-1, and the corresponding 206Pb/207Pb ratio was 1.195. The high-resolution profiles of Pb flux and 206Pb/207Pb ratios had close relationships with the economic development and the history of the use of leaded gasoline in China, and they were clearly different from those of most European countries and United States. - The combination of Pb concentration, sedimentary flux, Pb isotopic composition and 210Pb dating in the coastal ECS sediments revealed the historical Pb pollution in China

288

Fate of mercury species in the coastal plume of the Adour River estuary (Bay of Biscay, SW France).  

Science.gov (United States)

Because mercury (Hg) undergoes significant biogeochemical processes along the estuarine-coastal continuum, the objective of this work was to investigate the distribution and reactivity of methylmercury (MeHg), inorganic mercury (Hg(II)) and gaseous Hg (DGM) in plume waters of the Adour River estuary (Bay of Biscay). Vertical profiles, spatial and tidal variability of Hg species concentrations were evaluated during two campaigns (April 2007 and May 2010) characterized by significant plume extents over the coastal zone. Incubations with isotopically enriched tracers were performed on bulk and filtered waters under sunlight or dark conditions to investigate processes involved in Hg methylation, demethylation and reduction rates. Total Hg(II) concentrations were more dispersed in April 2007 (5.2 ± 4.9 pM) than in May 2010 (2.5 ± 1.1 pM) while total MeHg concentrations were similar for both seasons and averaged 0.13 ± 0.07 and 0.18 ± 0.11 pM, respectively. DGM concentrations were also similar between the two campaigns, averaging 0.26 ± 0.10 and 0.20 ± 0.09 pM, respectively. Methylation yields remained low within the estuarine plume (coastal waters (33-69 g (Hg) d(-1)). These processes are thus considered to be most significant in controlling the fate of Hg transferred from the river to the coastal zone. PMID:25091142

Sharif, Abubaker; Monperrus, Mathilde; Tessier, Emmanuel; Bouchet, Sylvain; Pinaly, Hervé; Rodriguez-Gonzalez, Pablo; Maron, Philippe; Amouroux, David

2014-10-15

289

[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

290

ESTUARY, RIVER AND SURROUNDING GROUNDWATER QUALITY DETERIORATION ASSOCIATED WITH TIDAL INTRUSION  

OpenAIRE

Salinity intrusion is a problem in many coastal estuarine and waterways in various parts of the world. Brisbane is a river city close to the coast and as such the condition of the river influences the surrounding groundwater quality. The data gathered by various agencies relating to the river system are used in this paper to develop and calibrate a 3D model of tidal intrusion into the river and surrounding groundwater. The FEMWATER finite element package is used to solve the model equations. ...

Singh, R.; Tularam, G. A.

2009-01-01

291

Feeding ecology and trophic relationships of fish species in the lower Guadiana River Estuary and Castro Marim e Vila Real de Santo António Salt Marsh  

Science.gov (United States)

In this study we analyze the feeding ecology and trophic relationships of some of the main fish species (Soleidae, Moronidae, Mullidae, Sparidae, Mugilidae, and Batrachoididae) of the lower Estuary of the Guadiana River and the Castro Marim e Vila Real de Santo António Salt Marsh. We examined the stomachs of 1415 fish caught monthly between September 2000 and August 2001. Feeding indices and coefficients were determined and used along with the results of multivariate analysis to develop diagrams of trophic interactions (food webs). Results show that these species are largely opportunistic predators. The most important prey items are amphipods, gobies (Gobiidae), shrimps ( Palaemon serratus and Crangon crangon), and polychaete worms. The lower Estuary and associated salt marshes are important nurseries and feeding grounds for the species studied. In this area, it is therefore important to monitor the effects of changes in river runoff, nutrient input, and temperature that result from construction of the Alqueva Dam upstream.

Sá, Rita; Bexiga, Constança; Veiga, Pedro; Vieira, Lina; Erzini, Karim

2006-10-01

292

In situ fate and partitioning of waterborne perfluoroalkyl acids (PFAAs) in the Youngsan and Nakdong River Estuaries of South Korea  

Energy Technology Data Exchange (ETDEWEB)

Concentrations, distributions, fate, and partitioning of perfluoroalkyl acids (PFAAs) were investigated in surface water (n = 34) collected from the Youngsan and Nakdong River Estuaries of South Korea. Thirteen individual PFAAs in water and suspended solids (SS) were quantified by use of HPLC–MS/MS. PFAAs were detected in all samples, which indicated that they were widely distributed in the study area. Greater concentrations of PFAAs were found at some inland sites which seemed to be affected by direct input from point sources, such as wastewater treatment plants, and/or indirect diffusive sources, such as surface runoff. Spatial distributions of PFAAs in estuaries along transects toward the open sea demonstrated that these chemicals were transported to the outer region primarily by water discharged during the rainy season. Field-based partition coefficients (K{sub d}) for long-chain PFAAs (C ? 8) were significantly correlated with salinity (r{sup 2} = 0.48 to 0.73, p < 0.01); K{sub d} values increased exponentially as a function of salinity. Due to the ‘salting-out’ effect, PFAAs were largely scavenged by adsorption onto SS and/or sediments in estuarine environments. In addition, values for K{sub d} of those PFAAs were directly proportional to the number of carbon atoms in the PFAAs. Salting constants of selected PFAAs were notably greater than those of other environmental organic contaminants, which indicated that adsorption of PFAAs is largely associated with salinity. Overall, the results of the present study will provide better understanding of the fate and transport of PFAAs in the zone of salinity boundary that can be used for developing fate models of PFAAs in the coastal marine environment. - Highlights: ? In situ fate and partitioning of PFAAs were described along salinity gradients in estuaries. ? Salinity was found to be the key factor controlling adsorption of waterborne PFAAs. ? The K{sub d} for longer-chain PFAAs (C ? 8) increased as a function of salinity (salting-out effect). ? Salting constants of PFAAs were notably greater than those of other organic contaminants. ? Results of this study will provide better understanding of PFAAs fate in the field.

Hong, Seongjin [School of Earth and Environmental Sciences, Seoul National University, Seoul (Korea, Republic of); Khim, Jong Seong, E-mail: jskocean@snu.ac.kr [School of Earth and Environmental Sciences, Seoul National University, Seoul (Korea, Republic of); Park, Jinsoon [School of Earth and Environmental Sciences, Seoul National University, Seoul (Korea, Republic of); Kim, Minhee; Kim, Woong-Ki; Jung, Jinho; Hyun, Seunghun; Kim, Jeong-Gyu [Division of Environmental Science and Ecological Engineering, Korea University, Seoul (Korea, Republic of); Lee, Hyojin; Choi, Heeseon J. [Department of Environmental Chemistry and Ecology, GeoSystem Research Corporation, Gunpo (Korea, Republic of); Codling, Garry [Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK (Canada); Giesy, John P. [Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK (Canada); Department of Zoology, Center for Integrative Toxicology, Michigan State University, East Lansing, MI (United States); Department of Biology and Chemistry and State Key Laboratory in Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, SAR (China)

2013-02-15

293

Distribution, biomass and production of Ceratonereis erythraeensis (Fauvel and Ceratonereis keiskama (Day at the Berg River Estuary, South Africa  

Directory of Open Access Journals (Sweden)

Full Text Available ENGLISH ABSTRACT: Population dynamics of the polychaetes Ceratonereis keiskama and C. erythraeensis were studied at the Berg River estuary, South Africa, from December 1987 to April 1989. There was marked size-related depth stratification of both species, with small worms being concentrated in the upper layer of the substratum and larger ones deeper down. Reproduction of both species occurred in summer. Three cohorts were distinguished in both populations. Recruitment of C. keiskama peaked in December whereas that of C. erythraeensis varied between years and sites (December-April. The population biomass of C. keiskama peaked in midsummer and was lowest during the spring and winter. C. erythraeensis maintained a high population biomass during winter and reached its lowest biomass during January-February. The total annual production of C. keiskama in the restricted area of the estuary where it occurred was 7,58 9 m-2 y-l, with a mean annual biomass of 4,11 9 m-2 making PIB = 1,84. Total annual production of C. erythra88nsis for the whole estuary was 14,42 9 m-2 y-l, mean annual biomass was 7,59 9 m'"2, and P/B = 1,90.******* AFRIKAANSE OPSOMMING: Die populasie-dinamika van die polychaete Ceratonereis keiskama en C. erythraeensis by die Bergrivier strandmeer, Suid Afrika, is van Desember 1987 tot April 1989 bestudeer. 'n Opvallende grootteverwante diepte-stratifikasie is vir beide spesies waargeneem, met kleiner wurms gekonsentreer in die boonste laag van die substraat en met die grater wurms dieper a1. Reproduksie vind by albei spesies in die somer plaas. Drie kohorte is in beide populasies onderskei. Rekrutering van C. keiskama het 'n piek in Desember getoon terwyl dit in C. erythraeensis van jaar tot jaar en tussen lokaliteite gevarieer het (Desember-April. Die bevolkingsbiomassa van C. keiskama het in die middel van die somer 'n maksimum bereik en was die laagste in die winter. Die biomassa van C. erythraeensis het 'n hoe vlak in die winter gehandhaaf en was die laagste gedurende Januarie-Februarie. Die totale jaarlikse produksie van C. keiskama, in die beperkte gebied van die strandmeer waar dit voorgekom het, was 7,58 9 m-2 r1 , met 'n gemiddelde jaarlikse biomassa van 4,11 9 m-2, en 'n PIB van 1,84. Die totale jaarlikse produksie van C. erythraeensis vir die hele strandmeer was 14,42 9 m-2 r die gemiddelde jaarlikse biomassa was 7,59 9 m-2 , en P/B 1,90.

B. Kalejta

2012-01-01

294

In situ fate and partitioning of waterborne perfluoroalkyl acids (PFAAs) in the Youngsan and Nakdong River Estuaries of South Korea  

International Nuclear Information System (INIS)

Concentrations, distributions, fate, and partitioning of perfluoroalkyl acids (PFAAs) were investigated in surface water (n = 34) collected from the Youngsan and Nakdong River Estuaries of South Korea. Thirteen individual PFAAs in water and suspended solids (SS) were quantified by use of HPLC–MS/MS. PFAAs were detected in all samples, which indicated that they were widely distributed in the study area. Greater concentrations of PFAAs were found at some inland sites which seemed to be affected by direct input from point sources, such as wastewater treatment plants, and/or indirect diffusive sources, such as surface runoff. Spatial distributions of PFAAs in estuaries along transects toward the open sea demonstrated that these chemicals were transported to the outer region primarily by water discharged during the rainy season. Field-based partition coefficients (Kd) for long-chain PFAAs (C ? 8) were significantly correlated with salinity (r2 = 0.48 to 0.73, p d values increased exponentially as a function of salinity. Due to the ‘salting-out’ effect, PFAAs were largely scavenged by adsorption onto SS and/or sediments in estuarine environments. In addition, values for Kd of those PFAAs were directly proportional to the number of carbon atoms in the PFAAs. Salting constants of selected PFAAs were notably greater than those of other environmental organic contaminants, which indicated that adsorption of PFAAs is largely associated with salinity. Overall, the results of the present study will provide better understanding of the fate and transport of PFAAs in the zone of salinity boundary that can be used for developing fate models of PFAAs in the coastal marine environment. - Highlights: ? In situ fate and partitioning of PFAAs were described along salinity gradients in estuaries. ? Salinity was found to be the key factor controlling adsorption of waterborne PFAAs. ? The Kd for longer-chain PFAAs (C ? 8) increased as a function of salinity (salting-out effect). ? Salting constants of PFAAs were notably greater than those of other organic contaminants. ? Results of this study will provide better understanding of PFAAs fate in the field

295

Composition of shrimp populations (Crustacea: Decapoda) in non-vegetated areas of two river islands in a Brazilian Amazon estuary  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english This study investigates the shrimp found in non-vegetated areas of an estuary of the Amazon River. We ascertained the input of juveniles, species' biometrics and the influence of environmental factors on the abundance of species. The samples were collected monthly, from August 2006 to July 2007, in [...] two places in the estuary, each next to an island. For collecting, we used a manual trawl to perform three hauls per month, totaling 36 samples per site. The abundance of shrimps was estimated as a function of the density of specimens per unit area. We used the Spearman's correlation to test the hypothesis that there is significant correlation between the average of the environmental variables measured and variations in shrimp density. The Kruskal-Wallis and the Mann-Whitney tests showed that there were significant differences in environment factors (temperature and salinity) among the months and sites. We obtained 6,091 shrimps, from which 5,231 (85.88%) were caught off the Arapiranga Island and 860 (14.12%) off the Mosqueiro Island, Palaemonidae and Penaeidae were the only families recorded. Five species were collected: Macrobrachium amazonicum (Heller, 1862), Macrobrachium surinamicum Holthuis, 1948, Macrobrachium carcinus (Linnaeus, 1758), Macrobrachium rosenbergii (De Man, 1879), and Farfantepenaeus subtilis (Pérez-Farfante, 1967). The latter (pink shrimp) was found for the first time in oligohaline environments (0-8). Macrobrachium amazonicum was the most abundant species. The recruitment of M. amazonicum juveniles was continuous throughout the year. The population of M. surinamicum was composed by juveniles and adults and that of F. subtilis exclusively by juveniles. The environmental factors analyzed were variable throughout the year and seem to explain the patterns of shrimp species occurrence in the region, the variation in their abundance and juvenile recruitment.

Priscila Sousa Vilela da, Nóbrega; Bianca, Bentes; Jussara Moretto, Martinelli-Lemos.

2013-12-01

296

Quality and Behavior of Juvenile Salmonids in the Columbia River Estuary and Nearshore Ocean and Effects of the Ocean Environment on the Survival of Columbia River Juvenile Salmonids, 1989-1994 Technical Report.  

Energy Technology Data Exchange (ETDEWEB)

In response to this limited understanding of the factors responsible for the continuing decline of spring chinook salmon in the Columbia River, this research plan was developed. The overall goal of the proposed research is to investigate and identify relationships among smolt quality (measured in the hatchery and after recovery in the estuary and nearshore ocean), environmental conditions in the estuary and nearshore ocean during smolt migration, and long-term survival (as measured by adult returns to the hatchery of origin and contributions to the recreational, commercial, and tribal fisheries). 16 refs., 15 figs., 3 tabs.

Francis, R.C.; Schiewe, Michael H.; Fisher, J.P.

1989-05-01

297

Evaluation of Status of Heavy Metals Pollution of Sediments in Qua-Iboe River Estuary and Associated Creeks, South-Eastern Nigeria  

OpenAIRE

Sixteen bottom sediment samples collected from Qua-Iboe River estuary and associated creeks were analyzed for Cd, Cr, Cu, Fe, Pb, Zn, Ni, pH, Organic carbon (orgC),and grain size in order to assess the current pollution status in sediment of the study area. Concentration data were processed using Pearson correlation analysis. Sediment pollution assessment was carried out using Enrichment factor, Geo-accumulation index and Modified degree of contamination. The calculated enrichment factor show...

Uwah, Ikama E.; Dan, Solomon F.; Etiuma, Rebecca A.; Umoh, Unyime E.

2013-01-01

298

Distribution and Sources of Polycyclic Aromatic Hydrocarbons in Sediments, Suspended Particulate Matter and Waters from the Siak River System, Estuary and Coastal Area of Sumatra, Indonesia  

OpenAIRE

This study examined the overall distribution and sources of polycyclic aromatic hydrocarbons (PAHs), particularly the 16 parent PAHs of the US Environmental Protection Agency priority pollutant, as an indicator for anthropogenic pollution, in the surface sediments, suspended particulate matter (SPM) and water solution of the peatland aquatic system of Siak river system, its estuary and the Riau coast, Sumatra, Indonesia from 2004 - 2006. The results show that PAHs significantly impact the Sia...

Lukman, Muhammad

2010-01-01

299

Length-weight relationship and parasites of Chrysichthys nigrodigitatus in Cross River Estuary Itu local government area Akwa Ibom State, Nigeria  

OpenAIRE

The study describes the length-weight relationship and helminthes bioload of Chrysichthys nigrodigitatus (Catfish) in the Cross river estuary purchased at Ayaedehe, Itu Local Government Area, Akwa Ibom State. A total of four hundred and twenty (420) life specimens of C. nigrodigitatus were collected by local fishing gear between June and November, 2011. Data obtained were statistically analyzed using descriptive and inferential statistics. Results showed that the highest length was obtained i...

Usip Lawrence Patrick Esiest

2013-01-01

300

Novel Method for Estimating Variations in Salinity and River Discharge in the Hudson Estuary Using Stable Isotopes of Leaf Waxes  

Science.gov (United States)

Understanding variations in the hydrological cycle of the Hudson Valley has important implications for water resources management, affecting millions of New Yorkers. Paleoclimatological records of hydrological variability from this region, however, are sparse, as the typical enivronments used for paleohydrological reconstruction do not exist. However, salt marshes are common features of the Hudson River, where the influence of tides is felt far upstream. To take advantage of these environments as recorders of paleohydrology, we present a new method for estimating annual river discharge using salt marsh sediments. We will be examining hydrogen isotopes of leaf waxes in vascular plants to estimate salinity, which will be calibrated to Hudson River discharge using United States Geological Survey (USGS) streamflow data. Freshwater flux from the Hudson Valley is proportional to the salinity at a particular location in the estuary. We estimate the relationship between the salinity and ?D using a two-part mixing model where the salinity and ?D of ocean water is 35 ppt and 0‰ VSMOW respectively, and the salinity and ?D of continental water is 0 ppt and -55‰ (approximately annual average precipitation in the region). It has been shown that the ?D of the leaf waxes of aquatic vegetation accurately reflect the ?D of growth water. For our experiment, we collected common members of the generaTypha, Spartina, Phragmites, and Scirpus from salt marshes along the Hudson River, and the north and south shores of Long Island to calibrate the specific relationship between marsh plant leaf wax ?D and marsh water ?D. We compare the measured ?D of these plant waxes to the ?D of marsh water estimated from salinity measurements made at USGS gage stations near each collection location. We then used the new calibration to estimate late Holocene variations in marsh salinity and thus Hudson River discharge using fossil leaf waxes. This novel method will help us better understand the frequency and severity of hydrologic variability in the Hudson River valley, and can potentially be applied in salt marsh ecosystems globally.

Tabanpour, B.; Nichols, J. E.; Isles, P. D.; Peteet, D. M.

2010-12-01

301

Effects of Projected Twenty-First Century Sea Level Rise, Storm Surge, and River Flooding on Water Levels in the Skagit River Floodplain and Estuary  

Science.gov (United States)

Near coastal environments have been identified as some of the most likely to be impacted by climate change. Observed changes in Puget Sound sea level and flood magnitudes are in line with those projected by previous climate change impacts studies. Current understanding of the combined effects of these changes is relatively low and has prompted us to explore the ways in which their co-occurrence will influence near coastal ecosystems and infrastructure. Using numerical simulation models the project examines the projected effects of climate change on water levels and inundation in the lower reaches of the Skagit River in western WA due to the combined effects of changes in storm surge, sea level rise, and riverine flooding. Global climate model simulations from the ECHAM-5 climate model were used as the climate forcings and were 1) statistically downscaled using the hybrid delta method, and 2) dynamically downscaled using the WRF regional climate model. Naturalized flows produced using the Variable Infiltration Capacity hydrology model were used to drive reservoir models that simulate flood control operations and regulated flow during extreme events. Storm surge was calculated using a regression approach that included atmospheric pressure patterns simulated by the WRF model and ENSO. A 2D hydrodynamic model was used to estimate water surface elevations in the Skagit River estuary and floodplain using resampled hourly hydrographs keyed to regulated daily flood flows produced by the daily time step reservoir simulation model and tide predictions adjusted for SLR and storm surge. Combining peak annual storm surge with expected sea level rise, the historic (1970-1999) 100-yr peak tidal anomaly is found to be exceeded every year by the 2020s. By the 2050s, the extrapolated 100-yr riverine flood events are found to increase by 30% and 25% in the Skagit and Nisqually Rivers, respectively. In the Skagit River, the combined effect of sea level rise and larger floods yields increased areal flood inundation up to 80% relative to the present "100-year" flood.

Hamman, J.; Hamlet, A. F.; Grossman, E. E.; Fuller, R.

2012-12-01

302

Seasonal effects of wastewater to the water quality of the Caeté river estuary, Brazilian Amazon  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A situação socioeconômica de Bragança depende principalmente dos recursos biológicos estuarinos e marinhos, que são influenciados pelos ciclos de marés e climatologia. Coletas oceanográficas (com medidas de variáveis hidrológicas, hidro-dinâmicas e microbiológicas) foram realizadas na área mais urba [...] nizada do estuário do Caeté, para caracterizar a qualidade das águas no setor estudado. Durante o período seco, o estuário foi mais eutrófico e apresentou os maiores valores de temperatura (30,5°C em Out./06), salinidade (17 psu em Fev./07), pH (8,24 em Fev./07) e coliformes fecais (>1000 MNP/ 100 ml em Dez./06 e Fev./07). As espécies fitoplanctô-nicas Cyclotella meneghiniana, Coscinodiscus centralis e outras espécies r-estrategistas também foram observadas. A falta de saneamento básico foi responsável pela contaminação local, especialmente durante o período seco, quando o esgoto foi lançado mais concentrado no estuário, mostrando a influência humana na redução da qualidade da água estuarina estudada. A pesca é considerada uma das principais atividades econômicas do município de Bragança e, portanto, esta contaminação poderá afetar negativamente a qualidade ambiental deste ecossistema amazônico. Abstract in english Bragança's socioeconomic situation is highly dependent on estuarine and marine biological resources that are influenced by tidal cycles and climatology. Field measurements (hydrological, hydrodynamic and microbiological variables) were taken in the most urbanized zone from Caeté estuary to character [...] ise the quality of the local environment. During the dry period, the estuary was more eutrophic and presented the highest temperature (30.5 °C in Oct./06), salinity (17 psu in Feb./07), pH (8.24 in Feb./07) and fecal coliform (> 1000 MPN/100 ml in Dec./06 and Feb./07) values. The phytoplankton Cyclotella meneghiniana, Coscinodiscus centralis and other r-strategist species were observed. The lack of basic hydric canalization was responsible for the local contamination, especially during the dry period when more concentrated wastewater from the city was emitted into the estuary, showing the human influence on the reduction of local estuarine water quality. In Bragança, the fishery is considered one of the main economic activities so, this contamination is worrisome because a large part of the local economy depends on biological resources and, thus, the contamination could negatively affect the environmental health of this Amazon ecosystem.

Luci C.C., Pereira; Marcela C., Monteiro; Danielly O., Guimarães; Jislene B., Matos; Rauquírio M. da, Costa.

2010-06-01

303

Seasonal effects of wastewater to the water quality of the Caeté river estuary, Brazilian Amazon  

Directory of Open Access Journals (Sweden)

Full Text Available Bragança's socioeconomic situation is highly dependent on estuarine and marine biological resources that are influenced by tidal cycles and climatology. Field measurements (hydrological, hydrodynamic and microbiological variables were taken in the most urbanized zone from Caeté estuary to characterise the quality of the local environment. During the dry period, the estuary was more eutrophic and presented the highest temperature (30.5 °C in Oct./06, salinity (17 psu in Feb./07, pH (8.24 in Feb./07 and fecal coliform (> 1000 MPN/100 ml in Dec./06 and Feb./07 values. The phytoplankton Cyclotella meneghiniana, Coscinodiscus centralis and other r-strategist species were observed. The lack of basic hydric canalization was responsible for the local contamination, especially during the dry period when more concentrated wastewater from the city was emitted into the estuary, showing the human influence on the reduction of local estuarine water quality. In Bragança, the fishery is considered one of the main economic activities so, this contamination is worrisome because a large part of the local economy depends on biological resources and, thus, the contamination could negatively affect the environmental health of this Amazon ecosystem.A situação socioeconômica de Bragança depende principalmente dos recursos biológicos estuarinos e marinhos, que são influenciados pelos ciclos de marés e climatologia. Coletas oceanográficas (com medidas de variáveis hidrológicas, hidro-dinâmicas e microbiológicas foram realizadas na área mais urbanizada do estuário do Caeté, para caracterizar a qualidade das águas no setor estudado. Durante o período seco, o estuário foi mais eutrófico e apresentou os maiores valores de temperatura (30,5°C em Out./06, salinidade (17 psu em Fev./07, pH (8,24 em Fev./07 e coliformes fecais (>1000 MNP/ 100 ml em Dez./06 e Fev./07. As espécies fitoplanctô-nicas Cyclotella meneghiniana, Coscinodiscus centralis e outras espécies r-estrategistas também foram observadas. A falta de saneamento básico foi responsável pela contaminação local, especialmente durante o período seco, quando o esgoto foi lançado mais concentrado no estuário, mostrando a influência humana na redução da qualidade da água estuarina estudada. A pesca é considerada uma das principais atividades econômicas do município de Bragança e, portanto, esta contaminação poderá afetar negativamente a qualidade ambiental deste ecossistema amazônico.

Luci C.C. Pereira

2010-06-01

304

The role of class I integrons in the dissemination of sulfonamide resistance genes in the Pearl River and Pearl River Estuary, South China.  

Science.gov (United States)

Antibiotic resistance genes (ARGs), as a newly emerging contaminant, are unique because they are disseminated through horizontal gene transfer in the environment. In the present study, a class 1 integron gene (int1) and various ARGs (sul1, sul2, sul3, qnrS, and ermB) were measured in water and sediment samples from the Pearl River (PR) to the Pearl River Estuary (PRE), where there is a distinct gradient in anthropogenic impact. The int1, sul1, and sul2 genes were detected in all samples, and their concentrations exhibited a clear trend of decline consistent with anthropogenic impact. Both the int1 and sul genes had dynamically migrated between water and sediments. The relative abundance of the int1 gene normalized to the 16S rRNA gene correlated significantly with the total concentrations of antibiotics in water and sediments. Good correlations were also observed between the abundance of int1 and each type of sul gene in the samples. However, the sul1 gene showed a much stronger relationship with int1 in different seasons, probably due to the presence of sul1 in the conserved region of class 1 integron. Our results strongly support that integrons play an important role in the dissemination of ARGs in human-impacted aquatic environments. PMID:24994022

Chen, Baowei; Liang, Ximei; Nie, Xiangping; Huang, Xiaoping; Zou, Shichun; Li, Xiangdong

2015-01-23

305

Modeling the influence of river discharge on salt intrusion and residual circulation in Danshuei River estuary, Taiwan  

Science.gov (United States)

A 3-D, time-dependent, baroclinic, hydrodynamic and salinity model was implemented and applied to the Danshuei River estuarine system and the adjacent coastal sea in Taiwan. The model forcing functions consist of tidal elevations along the open boundaries and freshwater inflows from the main stream and major tributaries in the Danshuei River estuarine system. The bottom friction coefficient was adjusted to achieve model calibration and verification in model simulations of barotropic and baroclinic flows. The turbulent diffusivities were ascertained through comparison of simulated salinity time series with observations. The model simulation results are in qualitative agreement with the available field data. The validated model was then used to investigate the influence of freshwater discharge on residual current and salinity intrusion under different freshwater inflow condition in the Danshuei River estuarine system. The model results reveal that the characteristic two-layered estuarine circulation prevails most of the time at Kuan-Du station near the river mouth. Comparing the estuarine circulation under low- and mean flow conditions, the circulation strengthens during low-flow period and its strength decreases at moderate river discharge. The river discharge is a dominating factor affecting the salinity intrusion in the estuarine system. A correlation between the distance of salt intrusion and freshwater discharge has been established allowing prediction of salt intrusion for different inflow conditions. ?? 2007 Elsevier Ltd. All rights reserved.

Liu, W.-C.; Chen, W.-B.; Cheng, R.T.; Hsu, M.-H.; Kuo, A.Y.

2007-01-01

306

Temporal variations and bioaccumulation of heavy metals in different Suaeda salsa marshes of the Yellow River estuary, China.  

Science.gov (United States)

To understand the temporal variations and bioaccumulation of heavy metals in the coastal marshes, the concentrations of heavy metals (Cr, Ni, Pb, and Cu) in the two Suaeda salsa marshes [middle S. salsa marsh (MM) and low S. salsa marsh (LM)] of the Yellow River estuary were determined from May to November in 2008 by in situ sampling and inductively coupled plasma mass spectrometry (ICP-MS) analysis. Results showed that heavy metal concentrations in S. salsa of MM and LM were generally in the order of Cu > Cr > Pb > Ni, while those in sediments fell in the order of Cr > Ni > Cu > Pb. Heavy metal concentrations of S. salsa in MM and LM were different, and significant differences were observed in stems (F = 4.797, p = 0.046) and litters (F = 6.799, p = 0.026) for Ni. Litter was the main stock of heavy metals, and the allocations of Cr, Ni, and Pb reached 31.25-51.31, 28.49-42.58, and 29.55-66.79 % (in MM) and 36.73-48.60, 41.70-57.87, and 33.30-60.64 % (in LM), respectively. The ratios of roots/leaves (R/L) and roots/stems (R/S) for Cr and Ni in MM were mostly greater than 1, while those ratios in LM were mostly less than 1, indicating that Cr and Ni in S. salsa at LM had greater mobility compared with those at MM. Moreover, the [accumulation factor, AF]plant of Cr, Ni, Cu, and Pb in LM, especially [AF]root and [AF]stem of Cr and [AF]litter of Ni, was also higher than that in MM. These indicated that S. salsa grown in LM was more suitable for potential biomonitor or phytoremediation of Cr, Ni, Cu, and Pb if intertidal sediments were seriously contaminated with an increase of pollutant loading (especially heavy metals) in the Yellow River estuary. The use of biomonitor (S. salsa) living and growing in LM could yield valuable information not only on the presence of anthropogenic stressors, but, more importantly, on the adverse influence the stressors are having on the environment. PMID:25056745

Song, Hongli; Sun, Zhigao

2014-12-01

307

Estimation of chlorophyll-a concentration in estuarine waters: case study of the Pearl River estuary, South China Sea  

International Nuclear Information System (INIS)

The objective of this work is to estimate chlorophyll-a (chl-a) concentration in the Pearl River estuary in China. To test the performance of algorithms for the estimation of the chl-a concentration in these productive turbid waters, the maximum band ratio (MBR) and near-infrared-red (NIR-red) models are used in this study. Specific focus is placed on (a) comparing the ability of the models to estimate chl-a in the range 1-12 mg m-3, which is typical for coastal and estuarine waters, and (b) assessing the potential of the Moderate Resolution Imaging Spectrometer (MODIS) and Medium Resolution Imaging Spectrometer (MERIS) to estimate chl-a concentrations. Reflectance spectra and water samples were collected at 13 stations with chl-a ranging from 0.83 to 11.8 mg m-3 and total suspended matter from 9.9 to 21.5 g m-3. A close relationship was found between chl-a concentration and total suspended matter concentration with the determining coefficient (R2) above 0.89. The MBR calculated in the spectral bands of MODIS proved to be a good proxy for chl-a concentration (R2 > 0.93). On the other hand, both the NIR-red three-band model, with wavebands around 665, 700, and 730 nm, and the NIR-red two-band model (with bands around 665 and 700 nm) explained more than 95% of the chl-a variation, and we were able to estimate chl-a concentrations with a root mean square error below 1 mg m-3. The two- and three-band NIR-rep>-3. The two- and three-band NIR-red models with MERIS spectral bands accounted for 93% of the chl-a variation. These findings imply that the extensive database of MODIS and MERIS images could be used to quantitatively monitor chl-a in the Pearl River estuary.

308

The distribution and occurrence of the marine manatee (Trichechus manatus in the estuary of the Mamanguape River, Paraíba, Brazil  

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Full Text Available Although the existing historical records of marine manatees in the Brazilian coast since the 17th century, few studies about this species were conducted in Brazil. Among them, the estuary of the Mamanguape River is told to be the main place of this species concentration in the northeastern coast of Brazil, but this one is suffering oppression due to the improvement of human activities which can compromise the ecosystem as a whole. In this way, this work viewed to obtain information about the marine manatee´s ecology and behavior in the estuary of the Mamanguape River, establishing seasonal modifications in its emergence, checking preferable places of occupation and detecting possible human activities which interfere in its biological cycle. With this purpose, it was developed one program for marine manatee groups in the region of Bar of Mamanguape and adjacent, by direct observation and interviews with fishers from 1988 to 1991. During the studies period, 608 monitoring visits were made to Bar of Mamanguape, totalizing 285 watching of isolated or grouped manatees and 2.185 hours of observation in fixed places. The major number of sightings happened from October to May, when the animals were seen more regularly and frequently in groups. From June to September, the animals went to that region sporadically and almost always alone. The biggest group observed was one formed by nine animals and the biggest one of registered animals at the same time was by 11 manatees. It was detected that the human activities which produce many noises in the water interfere with the animals´ behavior, scaring and dispersing the groups. Purse seines, drift and gill nets, used in the region, when closer to the groups, besides scaring away the animals, can be damaged due to the possible collisions with the marine manatees. Already the more resistant gill nets (caçoás imply extreme danger, because can flog the animals and get them to death. It is concluded that the region of the Bar of Mamanguape is of paramount importance for the maintenance of the reproductive cycle of the marine manatee, because it is one of their most concentration in the Northeast of Brazil. Creating restrictive zones within the Area of Environmental Preservation (AEP of the Bar of Mamanguape and ranking human activities are essential for the preservation of this species.

Kleber Grubel da Silva

2011-12-01

309

Concentrations and fluxes of dissolved uranium in the Yellow River estuary: seasonal variation and anthropogenic (Water-Sediment Regulation Scheme) impact  

International Nuclear Information System (INIS)

The Water-Sediment Regulation Scheme (WSRS) of the Yellow River is a procedure implemented annually from June to July to expel sediments deposited in Xiaolangdi and other large middle-reach reservoirs and to scour the lower reaches of the river, by controlling water and sediment discharges. Dissolved uranium isotopes were measured in river waters collected monthly as well as daily during the 2010 WSRS (June 19–July 16) from Station Lijin (a hydrologic station nearest to the Yellow River estuary). The monthly samples showed dissolved uranium concentrations of 3.85–7.57 ?g l?1 and 234U/238U activity ratios of 1.24–1.53. The concentrations were much higher than those reported for other global major rivers, and showed seasonal variability. Laboratory simulation experiments showed significant uranium release from bottom and suspended sediment. The uranium concentrations and activity ratios differed during the two stages of the WSRS, which may reflect desorption/dissolution of uranium from suspended river sediments of different origins. An annual flux of dissolved uranium of 1.04 × 108 g y?1 was estimated based on the monthly average water discharge and dissolved uranium concentration in the lower reaches of the Yellow River. The amount of dissolved uranium (2.65 × 107 g) transported from the Yellow River to the sea during the WSRS constituted about 1/4 of the annual flux. -- Highlights: • Dissolved U in the Yellow River estuary has distinct seasonal variability. • Geochemistry of dissolved U influenced by the WSRS has been analyzed. • Uranium flux during the WSRS has been evaluated

310

Dynamics of carbon-and oxygen stable isotopes in Paraguacu river estuary-Bahia, Brazil  

International Nuclear Information System (INIS)

Measurements of ?C13 and ?O18 have been made in water samples and carbonate sediments from the Paraguacu estuary with to a precision of X0,1%. Water samples were collected in the complete salinity range from 0% to 35% with the fresh water having the lowest O18/O16 ratios of 4,3%. Alinear correlations exists between salinity and the oxygen isootopic composition suggesting that O18/O16 behaves as a conservative property during the mixing of fresh water with sea water. With respect to the carbonate sediments, there exists a correlation between ?O18 and ?C13, indicating the need of ?C13 measurements when ?O18is being used as a temperature indicator. Since the carbonate shells are derivedfrom soluble HCO3 the possibility is shown of using ?O18 as an indicator of the mean salinity at a given locality. (Author)

311

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

Science.gov (United States)

...Northwest Power and Conservation Council, 2004...with the Northwest Power and Conservation Council, the Mid-Columbia...entire continuum where tidal forces and river flows...2005; Northwest Power and Conservation Council,...

2011-02-14

312

Downstream nutrient changes through the Mackenzie River Delta and Estuary, western Canadian Arctic  

OpenAIRE

The effect of the large lake-rich delta and freshwater-saltwater transition zone (FSTZ) on nutrients from the Mackenzie River was investigated during open water of 2003-2004. Water volume storage in the Mackenzie Delta at peak levels was estimated by quantitatively partitioning the landscape (via GIs analysis) into discrete floodplain lake, wetland and channel environments. A river and lake mixing model and biogeochemical sampling of upstream and downstream delta channels were used to estimat...

Emmerton, Craig A.

2006-01-01

313

Compound- and mixture-specific differences in resistance to polycyclic aromatic hydrocarbons and PCB-126 among Fundulus heteroclitus subpopulations throughout the Elizabeth River estuary (Virginia, USA).  

Science.gov (United States)

Atlantic killifish (Fundulus heteroclitus) inhabiting the Atlantic Wood Industries Superfund Site (Elizabeth River, Portsmouth, VA, USA) are resistant to the acute toxicity and cardiac teratogenesis caused by high levels of polycyclic aromatic hydrocarbons (PAHs) from creosote. The resistance is linked to down regulation of the aryl hydrocarbon receptor (AHR) pathway. We investigated the association between CYP1 activity, as a marker of potential AHR pathway suppression, and contaminant resistance in killifish subpopulations from sites throughout the estuary that varied significantly in PAH contamination level. Adult killifish and sediments were collected from seven sites across approximately 13.7 km in river length within the estuary and from a nearby reference site. Sediment PAH levels were determined using gas chromatography mass spectrometry. Embryos obtained via manual spawning were exposed to individual AHR agonists and PAH mixtures 24 h post fertilization (hpf); CYP1 activity was determined by in ovo ethoxyresorufin-o-deethylase (EROD) at 96 hpf, and cardiac deformity severity was scored at 144 hpf. The total PAH levels measured among the sites varied from approximately 200 to 125,000 ng/g dry sediment. Overall, the resistance to teratogenesis was strongest in the subpopulations from sites in or closest to the major PAH contamination sites, but even embryos from less-contaminated sites within the Elizabeth River demonstrated at least partial resistance to many challenges. Surprisingly, all of the subpopulations tested were highly resistant to PCB-126 (3,3',4,4',5-pentachlorobiphenyl). However, the degree of CYP1 activity response varied significantly among subpopulations and did not always correlate strongly with resistance to teratogenesis; some subpopulations resisted the cardiac teratogenesis caused by the challenges at doses that still elicited strong EROD induction. Our results suggest that there is variation in the adaptive phenotype exhibited by laboratory-spawned embryos from killifish subpopulations throughout the estuary. Furthermore, the results show that contaminants have affected killifish subpopulations throughout the estuary, even in sites with lower levels of PAHs. PMID:24003986

Clark, Bryan W; Cooper, Ellen M; Stapleton, Heather M; Di Giulio, Richard T

2013-09-17

314

Tidal wetlands of the Yaquina and Alsea River estuaries, Oregon: Geographic Information Systems layer development and recommendations for National Wetlands Inventory revisions  

Science.gov (United States)

Geographic Information Systems (GIS) layers of current, and likely former, tidal wetlands in two Oregon estuaries were generated by enhancing the 2010 National Wetlands Inventory (NWI) data with expert local field knowledge, Light Detection and Ranging-derived elevations, and 2009 aerial orthophotographs. Data were generated for two purposes: First, to enhance the NWI by recommending revised Cowardin classifications for certain NWI wetlands within the study area; and second, to generate GIS data for the 1999 Yaquina and Alsea River Basins Estuarine Wetland Site Prioritization study. Two sets of GIS products were generated: (1) enhanced NWI shapefiles; and (2) shapefiles of prioritization sites. The enhanced NWI shapefiles contain recommended changes to the Cowardin classification (system, subsystem, class, and/or modifiers) for 286 NWI polygons in the Yaquina estuary (1,133 acres) and 83 NWI polygons in the Alsea estuary (322 acres). These enhanced NWI shapefiles also identify likely former tidal wetlands that are classified as upland in the current NWI (64 NWI polygons totaling 441 acres in the Yaquina estuary; 16 NWI polygons totaling 51 acres in the Alsea estuary). The former tidal wetlands were identified to assist strategic planning for tidal wetland restoration. Cowardin classifications for the former tidal wetlands were not provided, because their current hydrology is complex owing to dikes, tide gates, and drainage ditches. The scope of this project did not include the field evaluation that would be needed to determine whether the former tidal wetlands are currently wetlands, and if so, determine their correct Cowardin classification. The prioritization site shapefiles contain 49 prioritization sites totaling 2,177 acres in the Yaquina estuary, and 39 prioritization sites totaling 1,045 acres in the Alsea estuary. The prioritization sites include current and former (for example, diked) tidal wetlands, and provide landscape units appropriate for basin-scale wetland restoration and conservation action planning. Several new prioritization sites (not included in the 1999 prioritization) were identified in each estuary, consisting of NWI polygons formerly classified as nontidal wetland or upland. The GIS products of this project improve the accuracy and utility of the NWI data, and provide useful tools for estuarine resource management.

Brophy, Laura S.; with contributions from: Reusser, Deborah A.; Janousek, Christopher N.

2013-01-01

315

Investigating the Impacts of Landuse-landcover (LULC Change in the Pearl River Delta Region on Water Quality in the Pearl River Estuary and Hong Kong’s Coast  

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Full Text Available Water quality information in the coastal region of Hong Kong and the Pearl River Estuary (PRE is of great concern to the local community. Due to great landuse-landcover (LULC changes with rapid industrialization and urbanization in the Pearl River Delta (PRD region, water quality in the PRE has worsened during the last 20 years. Frequent red tide and harmful algal blooms have occurred in the estuary and its adjacent coastal waters since the 1980s and have caused important economic losses, also possibly threatening to the coastal environment, fishery, and public health in Hong Kong. In addition, recent literature shows that water nutrients in Victoria Harbor of Hong Kong have been proven to be strongly influenced by both the Pearl River and sewage effluent in the wet season (May to September, but it is still unclear how the PRE diluted water intrudes into Victoria Harbor. Due to the cloudy and rainy conditions in the wet season in Hong Kong, ASAR images will be used to monitor the PRE river plumes and track the intruding routes of PRE water nutrients. In this paper, we first review LULC change in the PRD and then show our preliminary results to analyze water quality spatial and temporal information from remote observations with different sensors in the coastal region and estuary. The study will also emphasizes on time series of analysis of LULC trends related to annual sediment yields and critical source areas of erosion for the PRD region since the 1980s.

Hongyan Xi

2009-11-01

316

Cycling of transuranic radionuclides in the Columbia River, its estuary, and the North Pacific Ocean. Progress report, February 1, 1978--February 15, 1979  

International Nuclear Information System (INIS)

Progress from February 1978 through January 1979 on the measurement of radionuclides in the Columbia River and its estuary, with principal emphasis on plutonium isotopes is reported. The goal is to budget the inventory of transuranic radionuclides in the Columbia River system below the Hanford Complex and to estimate the amounts of Pu and Am being carried to the Northeast Pacific Ocean by the river. The results to date have led to conclusions of some importance to the Department of Energy. These are as follows: (1) previously published data on the concentrations of plutonium in McNary reservoir are incorrect. The reported analyses show Pu concentrations significantly lower than those reported by Battelle; (2) sedimentation rates in McNary reservoir do not appear to be as high as those estimated by previous workers. Using Pu and 137Cs subsurface maxima and 238 239 240Pu ratios, it is concluded that the sedimentation rates in the lower portion of McNary reservoir near the Oregon shore are between 4 and 5 cm/yr and decrease dramatically as the Washington shore is approached. Sedimentation rates at Ice Harbor Dam on the Snake River and at Bonneville Dam on the Columbia are about 2 cm/yr; (3) in the Columbia River estuary where fine sediments are accumulating at a rate of about 3 to 4 cm/yr, plutonium does not appear to be migrating from depth toward the surface.; (4) evidence suggests that the contribution of the eight plutoniumat the contribution of the eight plutonium production reactors to the integrated plutonium inventory of Columbia River sediments is small; (5) a surprising fraction of the plutonium in Columbia River water is not retained by 0.3? millipore filters; and (6) in certain regions Columbia River sediments contain rather high mean plutonium loads (mCi/km2). Each of these topics is discussed as well as the results of participation in both national and international quality control and intercalibration exercises

317

Assessment of trace metal levels in catfish (Cathorops spixii) from Sal River estuary, Aracaju, state of Sergipe, northeastern Brazil.  

Science.gov (United States)

The concentrations of cadmium, copper, nickel, zinc, and lead were determined in the catfish (Cathorops spixii) from the Sal River estuary, Brazil, to evaluate the potential role of domestic and industrial effluents released without treatment on the quality of the estuarine environment with consequences to fish resources. Muscle, liver, and kidney samples were analyzed for trace metal composition by flame atomic absorption spectrophotometry. The mean concentration (microg/g wet weight) of trace metals in the tissues of C. spixii were as follows: cadmium = 1.65, 2.81, and 0.71 microg/g; copper = 29.07, 4.38, and 3.40 microg/g; zinc = 229, 312, and 15.57 microg/g; nickel = 1.22, 1.04, and 117 microg/g; and lead = 7.09, 10.77, and 11.18 microg/g. The results show that metal accumulation in organs indicates the difference between them. The results showed high concentrations of copper, zinc, nickel, lead, and cadmium in the Cathorops spixii compared with the maximum values registered from fish in studies reported in other coastal regions of Brazil. PMID:21214023

Barbieri, Edison; Passos, Elisangela de Andrade; Aragão, Kennedy Alexandre Sousa; Santos, Danielle Barros; Garcia, Carlos Alexandre Borges

2010-12-01

318

Valuing Ecosystem Services with Fishery Rents: A Lumped-Parameter Approach to Hypoxia in the Neuse River Estuary  

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Full Text Available Valuing ecosystem services with microeconomic underpinnings presents challenges because these services typically constitute nonmarket values and contribute to human welfare indirectly through a series of ecological pathways that are dynamic, nonlinear, and difficult to quantify and link to appropriate economic spatial and temporal scales. This paper develops and demonstrates a method to value a portion of ecosystem services when a commercial fishery is dependent on the quality of estuarine habitat. Using a lumped-parameter, dynamic open access bioeconomic model that is spatially explicit and includes predator-prey interactions, this paper quantifies part of the value of improved ecosystem function in the Neuse River Estuary when nutrient pollution is reduced. Specifically, it traces the effects of nitrogen loading on the North Carolina commercial blue crab fishery by modeling the response of primary production and the subsequent impact on hypoxia (low dissolved oxygen. Hypoxia, in turn, affects blue crabs and their preferred prey. The discounted present value fishery rent increase from a 30% reduction in nitrogen loadings in the Neuse is $2.56 million, though this welfare estimate is fairly sensitive to some parameter values. Surprisingly, this number is not sensitive to initial conditions.

Larry B. Crowder

2011-11-01

319

Residues and potential health risks of DDTs and HCHs in commercial seafoods from two coastal cities near Yangtze River Estuary.  

Science.gov (United States)

Five species of commercial seafoods collected from the local markets in two coastal cities near Yangtze River Estuary (Ningbo and Zhoushan) in 2010 were analyzed to study the residues, potential sources, and health risks of dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) in these areas. The total levels of DDTs and HCHs in the samples ranged from 1.13-20.2 ng g(-1) and 1.23-3.05 ng g(-1) wet weight, respectively, and were at a middle level compared with those from other marine systems. Results from one-way analysis of variance (ANOVA) indicated species-specific distributions of DDTs and HCHs in the seafoods of the studied area, which may be related to their different lipid contents and ecological characteristics. Compositional analysis suggested that historical usage dominates in this area, and fresh inputs of lindane and dicofol may also have part contributions. With respect to DDTs, it can be metabolized into both DDD and DDE simultaneously in seafoods tested. Assessment based on maximum residue levels, acceptable or tolerable daily intakes, and hazard ratios for non-carcinogens suggested no obvious adverse health effects, while the lifetime cancer risks may be increased from dietary exposure to DDTs and HCHs. PMID:25602149

Jin, Mei Q; Zhou, Shan S; Liu, Wei P; Zhang, Dong; Lu, Xian T

2015-01-01

320

Spacial Distribution of Salinity and the Mechanism of Saltwater Intrusion in the Modaomen Water Channel of Pear River Estuary  

Science.gov (United States)

Modaomen channel is an important fresh water resource in Pearl River Delta. It has been impacted by saltwater intrusion frequently in the last decade. This has drawn more and more attention from scientists and engineers. The hydrodynamic mechanism of saltwater intrusion is still impercipient. In the present paper, hydrographs of velocity and salinity in the channel are analyzed based on field observations of velocity and salinity of upper, middle, and lower water layers at several stations along the Modaomen channel. It is found that the transport of salinity in Modaomen channel is obviously different from other estuaries. As the tidal range increases from neap to spring tide, the salinity in each water layer decreases unexpectedly. This peculiar phenomenon is attributed to the extraordinary flow process in the channel. When salinity value in each layer and vertical salinity gradient are lower during spring tide, no matter on rising or ebbing tide, the flow velocity monotonously decreases from water surface to the bottom, which is suggested by common sense. However, when salinity values and vertical salinity gradient are higher during neap tide, the flow velocity unexpectedly increases from water surface to the bottom during flood period, and flood duration of the bottom current is surprisingly as long as 15-18 hours. In addition, an inflexional velocity profile may remain amazingly for about 9 hours. This could be driven by the baroclinic pressure under the condition of tides, topography and upstream runoff discharge of this channel.

Liu, J. B.; Bao, Y.

2011-09-01

321

Preliminary assessment of the potential for mangrove oyster cultivation in Piraquê-açu river estuary (Aracruz, ES  

Directory of Open Access Journals (Sweden)

Full Text Available At Piraquê-açu river estuary, Aracruz, ES, the technical viability of Crassostrea rhizophorae cultivation was determined through monthly measures in shell length and weight. Seeds of C. rhizophorae were put in cages and suspended in rafts. Increase in height and weight (flesh and dry of the oysters was measured. During ten months (July/98 to May/99, oyster shell reached an average of 37.6 mm in shell height and 3.0 g in flesh weight (the whole animal. High mortality rates were registered and could be related to the high salinity water and to high predation observed, especially by flatworms Stylochophana divae and snails Cymatium parthenopeum, as well as fouling organisms such as barnacles, Serpulidae polychaetes and seed of the same species.No estuário do Rio Piraquê-açu, município de Aracruz, ES, foi avaliada a viabilidade técnica da implantação do cultivo de ostras Crassostrea rhizophorae em lanternas suspensas numa balsa de cultivo, através da estimativa de crescimento e ganho de peso fresco e seco das ostras. Verificou-se que, durante os dez meses de cultivo (junho/98 a maio/99, as ostras atingiram, em média, 37,6 mm de altura e 3,0 g no peso total. Foi registrada uma alta taxa de mortalidade, que poderia ser atribuída aos altos valores de salinidade na água e também aos predadores observados como planárias Stylochoplana divae e gastrópodos Cymatium parthenopeum, além de incrustantes como cracas, poliquetos Serpulidae e principalmente sementes da própria ostra.

Luciana Alvarenga

2006-01-01

322

Soil As Levels and Bioaccumulation in Suaeda salsa and Phragmites australis Wetlands of the Yellow River Estuary, China.  

Science.gov (United States)

Little information is available on As contamination dynamics in the soil-plant systems of wetlands. Total arsenic (As) in soil and plant samples from Suaeda salsa and Phragmites australis wetlands was measured in the Yellow River Estuary (YRE) in summer and autumn of 2007 to investigate the seasonal changes in As concentrations in different wetlands. The results showed that soil As levels greatly exceeded the global and regional background values. As levels in soil and the roots and stems of both types of plants were much higher in summer than in autumn, whereas leaf As showed higher level in autumn. Soil sulfur was the main factor influencing As levels in Suaeda salsa wetlands, whereas soil porosity was the most important factor for Phragmites australis wetlands. The contamination factor (CF) showed moderately to considerably polluted levels of As in both wetland soils. Plant roots and leaves of Suaeda salsa had higher As concentrations and biological concentration factors (BCFs) than stems, while the leaves and stems of Phragmites australis showed higher As levels and BCFs than roots. Compared to Phragmites australis, Suaeda salsa generally showed higher translocation factor (TF), while TF values for both plant species were higher in summer than in autumn. PMID:25685781

Wang, Junjing; Bai, Junhong; Gao, Zhaoqin; Lu, Qiongqiong; Zhao, Qingqing

2015-01-01

323

Metabolic and phylogenetic profile of bacterial community in Guishan coastal water (Pearl River Estuary), South China Sea  

Science.gov (United States)

Characteristics of a microbial community are important as they indicate the status of aquatic ecosystems. In the present study, the metabolic and phylogenetic profile of the bacterioplankton community in Guishan coastal water (Pearl River Estuary), South China Sea, at 12 sites (S1-S12) were explored by community-level physiological profiling (CLPP) with BIOLOG Eco-plate and denaturing gradient gel electrophoresis (DGGE). Our results showed that the core mariculture area (S6, S7 and S8) and the sites associating with human activity and sewage discharge (S11 and S12) had higher microbial metabolic capability and bacterial community diversity than others (S1-5, S9-10). Especially, the diversity index of S11 and S12 calculated from both CLPP and DGGE data ( H>3.2) was higher than that of others as sewage discharge may increase water nitrogen and phosphorus nutrient. The bacterial community structure of S6, S8, S11 and S12 was greatly influenced by total phosphorous, salinity and total nitrogen. Based on DGGE fingerprinting, proteobacteria, especially ?- and ?-proteobacteria, were found dominant at all sites. In conclusion, the aquaculture area and wharf had high microbial metabolic capability. The structure and composition of bacterial community were closely related to the level of phosphorus, salinity and nitrogen.

Hu, Xiaojuan; Liu, Qing; Li, Zhuojia; He, Zhili; Gong, Yingxue; Cao, Yucheng; Yang, Yufeng

2014-10-01

324

The Role of Submarine Groundwater Discharge in the Delivery of Nitrogen to the Corsica River Estuary, Maryland  

Science.gov (United States)

This study examined the role that submarine groundwater discharge plays in transporting land-derived nitrogen, primarily from agricultural fertilizer use, to a tributary of Chesapeake Bay, and the degree of removal by denitrification in the freshwater aquifer and fresh/saline groundwater mixing zone prior to discharge. Nutrient analysis, salinity measurements, age dating using dissolved anthropogenic tracers, and membrane-inlet mass spectrometry (MIMS), were combined to examine nutrient loading from the upper 8 m of the submarine aquifer to the Corsica River Estuary. The site was intensively sampled, using hand-driven piezometers along a five-point transect perpendicular to the shoreline spanning the nearshore discharge zone. The total length of the transect was 42 m, and an average of nine depths were sampled at each piezometer location. There is fresh water present in the aquifer (salinity beneath a brackish mixing zone at the sediment surface. This freshwater plume extends about 20 m offshore. Dissolved inorganic nitrogen speciation mimics the patterns seen in the salinity, with high nitrate concentrations (up to 220?M) in fresh groundwater, and high ammonium concentrations (as high as 140?M) in the saline groundwater. The deepest freshwater samples, however, contain low concentrations of nitrogen, and when compared to recharge dates calculated from tritium and chlorofluorocarbon analyses, indicate the presence of older water which is less impacted by anthropogenic nitrogen inputs. MIMS results show large concentrations of excess gas above equilibrium concentrations, but interpretation of a denitrification signal may be confounded by artificial recharge due to irrigation.

Baldwin, S. M.; Bratton, J. F.; Kroeger, K. D.; Crusius, J. C.; Green, A. C.; Erban, L.

2008-12-01

325

Trace metal distribution in sediments of the Pearl River Estuary and the surrounding coastal area, South China  

Energy Technology Data Exchange (ETDEWEB)

Surface sediments and sediment cores collected at the Pearl River Estuary (PRE) and its surrounding coastal area were analysed for total metal concentrations, chemical partitioning, and Pb isotopic compositions. The distribution of Cu, Cr, Pb, and Zn demonstrated a typical diffusion pattern from the land to the direction of the sea. Two hotspots of trace metal contamination were located at the mixed zone between freshwater and marine waters. The enrichment of metals in the sediments could be attributed to the deposition of the dissolved and particulate trace metals in the water column at the estuarine area. The similar Pb isotopic signatures of the sediments at the PRE and its surrounding coastal area offered strong evidence that the PRE was a major source of trace metals to the adjacent coastal area. Slightly lower {sup 206}Pb/{sup 207}Pb ratios in the coastal sediments may indicate other inputs of Pb in addition to the PRE sources, including the inputs from Hong Kong and other parts of the region. - The distribution of trace metals in sediments reflected contaminant sources, physical and chemical deposition processes.

Ip, Carman C.M. [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Li Xiangdong [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)]. E-mail: cexdli@polyu.edu.hk; Zhang Gan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Wai, Onyx W.H. [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Li, Y.-S. [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

2007-05-15

326

Non-aromatic hydrocarbons in surface sediments near the Pearl River estuary in the South China Sea  

International Nuclear Information System (INIS)

Surface sediment samples at 4 sites along an offshore transect from outer continental shelf off the Pearl River estuary to the shelf slope region of the northern South China Sea, have been analyzed for total organic carbon (TOC), total nitrogen (TN), solvent extractable organic matter (EOM) and non-aromatic hydrocarbons. TOC, TN and EOM show distinct spatial variations. Their highest values are all recorded at the shelf slope region. EOM varies from 18.70-38.58 ?g g-1 dry sediment and accounts for 0.20-0.72% of the TOC contents. The non-aromatic hydrocarbons are an important fraction of EOM. Their contents range from 3.43-7.06 ?g g-1 dry sediment. n-Alkanes with carbon number ranging from 15-38 are identified. They derive from both biogenic and petrogenic sources in different proportions. Results of isoprenoid hydrocarbons, hopanes and steranes also suggest possible petroleum contamination. - Anthropogenic activities have influences on the composition of non-aromatic hydrocarbons in the surface sediments of the northern South China Sea outer continental shelf

327

Influence of Spartina alterniflora on the mobility of heavy metals in salt marsh sediments of the Yangtze River Estuary, China.  

Science.gov (United States)

Using bio-disturbed sulphide to trace the mobility and transformation of Cu, Pb, Ni and Zn in the sediments of the Spartina alterniflora-dominated salt marsh in the Yangtze River Estuary, measurements were made of the seasonal variations of acid-volatile sulphide (AVS) and of the simultaneously extracted metals (SEM) in the rhizosphere sediments. Microcosm incubation experiments recreating flooding conditions were conducted to evaluate the effect of AVS and other metal binding phases upon the dynamics of Cu, Pb, Ni and Zn in the salt marsh sediments. The results demonstrate that the ratio values of SEM/AVS have a significant seasonal variation in the rhizosphere sediments and that the anoxic conditions in the sediments were likely enhanced by S. alterniflora during the summer and autumn compared with the anoxic conditions resulting from the native species Phragmites australis and Scirpus mariqueter. The incubation experiments suggest that Fe(III) and Mn(IV/III) (hydr)oxides provide important binding sites for heavy metals under oxic conditions, and sulphide provides important binding sites for the Cu and Pb under anoxic conditions. Our observations indicate that the mobility of heavy metals in the salt marsh sediments is strongly influenced by biogeochemical redox processes and that the invasive S. alterniflora may increase the seasonal fluctuation in heavy metal bioavailability in the salt marsh ecosystem. PMID:22821343

Wang, Yongjie; Zhou, Limin; Zheng, Xiangmin; Qian, Peng; Wu, Yonghong

2013-03-01

328

Species diversity of the old genus Navicula Bory (Bacillariophyta on intertidal sand-flats in the Nakdong River estuary, Korea  

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Full Text Available Remarkable diversity of diatom taxa occurs in intertidal sand-flats of the Nakdong River estuary, one of the most dynamic and productive ecosystem in Korea. Benthic diatoms were collected from the sandy sediments to clarify the taxonomic accounts and distribution of the old genus Navicula, i.e., the naviculoid flora. Total 92 taxa belonging to Navicula sensu stricto and 22 genera separated from Navicula sensu lato are reported with brief descriptions and micrographs, and many species remain unidentified. The genera are ranked by the number of diatom species: Navicula of 33 species and varieties, Fallacia of 17 species, Placoneis of five species, Fogedia and Parlibellus of four species, Austariella, Hippodonta and Petroneis of three species, Cosmioneis, Diadesmis, Luticola, Moreneis and Sellaphora of two species and variety, Berkeleya, Chamaepinnularia, Cocconeiopsis, Diademoides, Dickieia, Eolimna, Geissleria, Haslea, Lyrella and Mayamaea of one species. Through 32 samplings of the 12 areas, the important species were identified Navicula perminuta, N. gregaria, N. torneensis, Fallacia cunoniae, F. litoricola, F. subforcipata, F. tenera. The naviculoid diatoms constitute an average of 27% (range: minimum to maximum, 5-75%, of the benthic diatom assemblages. The diatom assemblages are characterized by the colonizing of a few dominant or frequent species and many occasional or rare species. The dominant species were observed to fluctuate with sampling site and time. Among the reported naviculoid diatoms, 46 taxa are newly reported in Korea.

Gyeong-je Joh

2013-12-01

329

Reproductive cycle of Tagelus plebeius (Mollusca: Bivalvia) in the estuary of the Cachoeira River, Ilhéus, Bahia, Brazil.  

Science.gov (United States)

This study characterized the reproductive cycle of the stout razor clam Tagelus plebeius in the estuary of the Cachoeira River, Ilhéus, Bahia, northeastern Brazil. Samples of 20 animals per collection were taken biweekly from August 2005 to August 2006. The 480 specimens were measured on the antero-posterior axis (length) and then removed from the shell. After macroscopic analysis, the gonads were fixed in Davidson's solution, processed by routine histology and stained by Harris hematoxylin and eosin. The gonads of both males and females appeared milky white, without sexual dimorphism. Microscopic analyses indicated a M: F ratio of 1.06: 1 and continuous reproduction of T. plebeius in the region. The period from August to October showed the most intense spawning. This study provides another example of continuous reproduction of bivalves in tropical waters, and because this species is a heavily exploited fishery resource in the region, it draws attention to the need for a management plan aimed at reducing harvests. PMID:22990828

Ceuta, L O; Boehs, G

2012-08-01

330

Biogeochemical alteration of dissolved organic material in the Cape Fear River Estuary as a function of freshwater discharge  

Science.gov (United States)

This study presents the first extensive examination of the controls on optical properties of chromophoric dissolved organic matter (CDOM) within the Cape Fear River Estuary (CFRE) utilizing spectral slope ratios (SR). The application of SUVA254 values, absorption spectral slopes (S) and SR values has presented a distinct opportunity to observe compositional changes in CDOM in the CFRE that was not possible using bulk DOC and aCDOM(350) values alone. By comparing estuarine trends in CDOM spectral shape during both normal and historically low flow conditions, we found that diagenetic processing of CDOM in the CFRE is controlled primarily by riverine discharge rates. These findings suggest that the chromophoric fraction of DOM is altered during estuarine transport under low flow regimes but reaches the coastal ocean relatively unaltered under higher flow conditions. This highlights the tendency for autochthonous sources of DOC to offset photochemical losses and indicates that in situ DOC production can significantly contribute to the overall carbon load if discharge is low or sufficient biogeochemical alteration of the terrestrial DOM end-member occurs. This provides new insight into the usefulness of these optical properties into understanding the cycling, fate and transport of CDOM to the coastal ocean. SR values provide a simple but potentially powerful tool in understanding the flux, transport and impact of terrestrially derived organic material deposited in the coastal ocean.

Dixon, Jennifer L.; Helms, John R.; Kieber, Robert J.; Avery, G. Brooks

2014-08-01

331

Background values for evaluation of heavy metal contamination in sediments in the Parnaíba River Delta estuary, NE/Brazil.  

Science.gov (United States)

This study establishes regional background levels and upper thresholds (geochemical baseline) for Zn, Cu, Pb, Cr, Mn, and Fe from surface samples and profiles taken in 16 sedimentary environments of the Parnaíba River Delta estuary, NE-Brazil. Three approaches were applied to evaluate metal contamination: normalization to Fe, statistical analysis and sediment quality guidelines or environmental assessment criteria (TEL-PEL). Metal concentrations in sediments ranged from 2.4 to 31mgZnkg(-1), 1.5 to 48mgCukg(-1), 1.3 to 28mgPbkg(-1), 1.5 to 38mgCrkg(-1); 145 to 1,356mgMnkg(-1), and 0.3% to 2.5% for Fe. All metals showed positive correlations with the <0.63?m sediment fraction, indicating a significant association with rich lithogenic sources of iron oxide-hydroxides. Results suggest a low probability of adverse effects to the local aquatic biota. The background values of the area were lower than those reported for other areas of the northeastern coast of Brazil. PMID:25284444

de Paula Filho, Francisco José; Marins, Rozane Valente; de Lacerda, Luiz Drude; Aguiar, José Edvar; Peres, Tiago Farias

2015-02-28

332

Proceedings of the Columbia River Estuary Conference on Ecosystem Restoration, April 29-30, 2008, Astoria, Oregon.  

Energy Technology Data Exchange (ETDEWEB)

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

Johnson, Gary E. [Pacific Northwest National Laboratory; Sutherland, G. Bruce [Oregon Department of Environmental Quality (retired)

2008-09-29

333

Geochemistry of carbon stable isotope in Shatt AL-Arab River and Khor AL-Zubair Estuary, South Iraq  

International Nuclear Information System (INIS)

24 samples of Mollusc shells from Shatt AL-Arab river and Khor AL-Zubair estuary were analyzed in order to determine the concentration of carbon stable isotope and also to clarify the factors that control the geochemical distribution of carbon isotopes in these two different environments. The carbon stable isotope were measured using the dosed tube method, in which shell samples are combusted to carbon dioxide for carbon isotope analysis. The carbon dioxide samples are analyzed on a Finnigan Mat 251 isotope ratio mass spectrometer equipped with a triple collector and controlled by an Apple He microcomputer. Measurements are made relative to several working standards {Norit (-24 per mille),NBS-22 (-29 per mille)}, and several secondary light methane standards at -43.4 per mille and -62.6 per mille. All values are reported versus PDB. These analyses are conducted in the department, of Oceanography in Texas A and M University. This study indicates that the differences in carbon stable isotopes were due to three factors: environmental conditions, under which these three molluscs are lived, chemistry of the water in Shatt AL-Arab and Khor AL-Zubair and feeding quality of these of these molluscs. The factors are close related with another important factor that it. is the pollution present in these two different environments. (author)

334

Development of a relative risk model for evaluating ecological risk of water environment in the Haihe River Basin estuary area.  

Science.gov (United States)

Ecological risk assessment for water environment is significant to water resource management of basin. Effective environmental management and systems restoration such as the Haihe River Basin require holistic understanding of the relative importance of various stressor-related impacts throughout the basin. As an effective technical tool for evaluating the ecological risk, relative risk model (RRM) was applied in regional scale successfully. In this study, the risk transfer from upstream of basin was considered and the RRM was developed through introducing the source-stressor-habitat exposure filter (SSH), the endpoint-habitat exposure filter (EH) and the stressor-endpoint effect filter (SE) to reflect the meaning of exposure and effect more explicit. Water environment which includes water quality, water quantity and aquatic ecosystems was selected as the assessment endpoints. We created a conceptual model which depicting potential and effect pathways from source to stressor to habitat to endpoint. The Haihe River Basin estuary (HRBE) was selected as the model case. The results showed that there were two low risk regions, one medium risk region and two high risk regions in the HRBE. The results also indicated that urbanization was the biggest source, the second was shipping and the third was industry, their risk scores are 5.65, 4.71 and 3.68 respectively. Furthermore, habitat destruction was the largest stressor with the risk scores (2.66), the second was oxygen consuming organic pollutants (1.75) and the third was pathogens (1.75). So these three stressors were the main influencing factors of the ecological pressure in the study area. For habitats, open waters (9.59) and intertidal mudflat were enduring the bigger pressure and should be taken considerable attention. Ecological service values damaged (30.54) and biodiversity decreased were facing the biggest risk pressure. PMID:22321901

Chen, Qiuying; Liu, Jingling; Ho, Kin Chung; Yang, Zhifeng

2012-03-15

335

A survey of benthic sediment contaminants in reaches of the Columbia River Estuary based on channel sedimentation characteristics.  

Science.gov (United States)

While previous studies have documented contaminants in fish, sediments, water, and wildlife, few specifics are known about the spatial distribution of contaminants in the Columbia River Estuary (CRE). Our study goal was to characterize sediment contaminant detections and concentrations in reaches of the CRE that were concurrently being sampled to assess contaminants in water, invertebrates, fish, and osprey (Pandion haliaetus) eggs. Our objectives were to develop a survey design based on sedimentation characteristics and then assess whether sediment grain size, total organic carbon (TOC), and contaminant concentrations and detections varied between areas with different sedimentation characteristics. We used a sediment transport model to predict sedimentation characteristics of three 16km river reaches in the CRE. We then compartmentalized the modeled change in bed mass after a two week simulation to define sampling strata with depositional, stable, or erosional conditions. We collected and analyzed bottom sediments to assess whether substrate composition, organic matter composition, and contaminant concentrations and detections varied among strata within and between the reaches. We observed differences in grain size fractions between strata within and between reaches. We found that the fine sediment fraction was positively correlated with TOC. Contaminant concentrations were statistically different between depositional vs. erosional strata for the industrial compounds, personal care products and polycyclic aromatic hydrocarbons class (Indus-PCP-PAH). We also observed significant differences between strata in the number of detections of Indus-PCP-PAH (depositional vs. erosional; stable vs. erosional) and for the flame retardants, polychlorinated biphenyls, and pesticides class (depositional vs. erosional, depositional vs. stable). When we estimated mean contaminant concentrations by reach, we observed higher contaminant concentrations in the furthest downstream reach with a decreasing trend in the two upstream reaches. Contaminant survey designs that account for sedimentation characteristics could increase the probability that sampling is allocated to areas likely to be contaminated. PMID:24703225

Counihan, Timothy D; Waite, Ian R; Nilsen, Elena B; Hardiman, Jill M; Elias, Edwin; Gelfenbaum, Guy; Zaugg, Steven D

2014-06-15

336

Red waters of Myrionecta rubra are biogeochemical hotspots for the Columbia River estuary with impacts on primary/secondary productions and nutrient cycles  

Energy Technology Data Exchange (ETDEWEB)

The localized impact of blooms of the mixotrophic ciliate Myrionecta rubra in the Columbia River estuary during 2007-2010 was evaluated with biogeochemical, light microscopy, physiological and molecular data. M. rubra affected surrounding estuarine nutrient cycles, as indicated by high and low concentrations of organic nutrients and inorganic nitrogen, respectively, associated with red waters. M. rubra blooms also altered the energy transfer pattern in patches of the estuarine water that contain the ciliate by creating areas characterized by high primary production and elevated levels of fresh autochthonous particulate organic matter, therefore shifting the trophic status in emergent red water areas of the estuary from net heterotrophy towards autotrophy. The pelagic estuarine bacterial community structure was unaffected by M. rubra abundance, but red waters of the ciliate do offer a possible link between autotrophic and heterotrophic processes since they were associated with elevated dissolved organic matter and enhanced microbial secondary production. Taken together these findings suggest that M. rubra red waters are biogeochemical hotspots of the Columbia River estuary.

Herfort, Lydie; Peterson, Tawnya D.; Prahl, Fredrick G.; McCue, Lee Ann; Needoba, Joe A.; Crump, Byron C.; Roegner, G. Curtis; Campbell, Victoria; Zuber, Peter A.

2012-02-29

337

Phytoplankton nyctemeral variation at a tropical river estuary (Itamaracá-Pernambuco-Brazil).  

Science.gov (United States)

The Botafogo estuary is of socio-economical importance for Pernambuco State. It is located at the north of Santa Cruz Channel, Itamaracá, Pernambuco, Brazil (07 degrees 42' 50 "S and 34 degrees 52' 10" W). There is a critical need to understand its functioning because of the rate at which this area is being converted to land uses. The phytoplankton dynamics was studied to enhance the knowledge of and verify the possible changes which have occurred in this ecosystem. Sampling was carried out with a plankton net 65 micrometers mesh size for qualitative data, and a Van Dorn bottle for quantitative data. Concurrent hydrological and chlorophyll-a data were collected. Samplings were made in one fixed station in July 1996 (rainy season) and December 1996 (dry season), at 3-hour intervals during 24 hours. Eighty-seven specific and infra-specific taxa were identified from net plankton samples. Diatoms were most frequent, mainly Coscinodiscus centralis and Odontella regia in the rainy and dry seasons, respectively. Phytoplankton density varied from 205,000 to 1,210,000 cell.L-1 in the dry season, and from 230,000 to 2,510,000 cell.L-1 in the rainy season, indicating eutrophic conditions. Most numerically abundant were the diatoms Cyclotella meneghiniana and Cylindrotheca closterium and the phytoflagellates. The ecosystem is polluted, and deleterious effects are minimized by the marine influence which allows periodic water renewal. PMID:15195367

Lacerda, S R; Koening, M L; Neumann-Leitão, S; Flores-Montes, M J

2004-02-01

338

Sources of heavy metals in sediments of the Hudson River Estuary  

International Nuclear Information System (INIS)

Sediments in the Hudson Estuary contain zinc, copper and lead from metal pollutants discharged to the harbor in the New York City area, from dispersed sources of contamination introduced upstream, and from natural weathering processes. The magnitude of the contribution from each of these three sources to particular sites can be estimated on the basis of total metal abundances, relative proportions of several metals, and other sediment properties. The pattern of recent heavy-metal contamination in Hudson sediments closely follows the distribution in sediments of 137Cs which was derived over the past two decades from global fallout and local releases from a commercial nuclear reactor. Several simple empirical corrections related to grain size and mineralogy variations are suggested for comparing heavy-metal contamination levels of sandy continental shelf sediments with fine-grained estuarine and coastal sediments. Iron has little variation in Hudson sediments while manganese is greater in surface sediment of some low-salinity and fresh-water areas than deeper in the sediments, and generally less in the high-salinity area of rapid sediment deposition in New York harbor. Much of the pollutant Cu added to the harbor appears to be rapidly deposited in the sediments. (Auth.)

339

Anthropogenic sources and distribution of phosphorus in sediments from the Jaguaribe River estuary, NE, Brazil Emissão e distribuição de fósforo de fontes antrópicas no estuário do rio Jaguaribe, Nordeste do Brasil  

OpenAIRE

This paper estimates annual P emission to the Jaguaribe River estuary, NE Brazil, responsible for approximately 30% of the country's farmed shrimp production. Emissions increased three times between 2001 and 2006 and reached 43.9 t.year-1. These emissions make aquaculture the third main source of P for this estuary and are much smaller than emissions from agricultural sources and slightly lower than emissions from wastewater. Their relative contribution also increased from 10.5% to 20.5%. Tem...

Rv, Marins; Fj, Paula Filho; Sa, Eschrique; Ld, Lacerda

2011-01-01

340

Mid-Holocene variability of the East Asian monsoon based on bulk organic ?13C and C/N records from the Pearl River estuary, southern China  

Science.gov (United States)

Understanding the mid-Holocene dynamics of the East Asian monsoon (EAM) is integral to modelling the Holocene development of the global climate system (Webster et al., 1998). Thus the mid-Holocene EAM history was reconstructed using bulk organic carbon isotopes (?13C), total carbon to total nitrogen (C/N) ratios and total organic carbon (TOC) from a sediment core (UV1), at a mean resolution of 7-10 years, from the Pearl River estuary, southern China. Sedimentary ?13C, C/N and TOC from the Pearl River estuary is a good indicator of changes in monsoonal precipitation strength (Zong et al., 2006; Yang et al., 2010; Yu et al., 2010), eg sediments buried during a period of high precipitation exhibit a high proportion of terrigenous sediments, and have low ?13C and high C/N, and vice versa (Yu et al., 2010). Results suggest a general decreasing trend in monsoonal precipitation from 6650 to 2215 cal yr BP because of the weakening Northern Hemisphere insolation most likely related to the current precession circle (An, 2000). Superimposed on this trend are apparent dry-wet oscillations at centennial to millennial timescales most likely in response to solar activity. Mismatch between ?13C and results from the Dongge Cave in southern China at millennial-timescale oscillations (Wang et al., 2005), may indicate that the ?13C from the Pearl River estuary reveals changes in precipitation in a broader area than the ?18O from Dongge Cave does. Reference An Z (2000) The history and variability of the East Asian paleomonsoon climate. Quaternary Science Reviews 19: 171-187. Wang Y, Cheng H, Edwards RL, He Y, Kong X, An Z, Wu J, Kelly MJ, Dykoski CA and Li X (2005) The Holocene Asian Monsoon: Links to Solar Changes and North Atlantic Climate. Science 308: 854-857. Webster PJ, Magaña VO, Palmer TN, Shukla J and Tomas RA (1998) Monsoons: Processes, predictability, and the prospects for prediction. Journal of Geophysical Research 103(C7): 14451-14510. Yang S, Tang M, Yim WWS, Zong Y, Huang G, Switzer AD and Saito Y (2011) Burial of organic carbon in Holocene sediments of the Zhujiang (Pearl River) and Changjiang (Yangtze River) estuaries. Marine Chemistry 123(1-4): 1-10. Yu F, Zong Y, Lloyd JM, Huang G, Leng MJ, Kendrick C, Lamb AL and Yim WWS (2010) Bulk organic ?13C and C/N as indicators for sediment sources in the Pearl River delta and estuary, southern China. Estuarine, Coastal and Shelf Science 87(4): 618-630. Zong Y, Lloyd JM, Leng MJ, Yim WW-S and Huang G (2006) Reconstruction of Holocene monsoon history from the Pearl River Estuary, southern China, using diatoms and carbon isotope ratios. The Holocene 16(2): 251-263.

Yu, F.; Zong, Y.; Lloyd, J. M.; Leng, M. J.; Switzer, A. D.; Yim, W. W.; Huang, G.

2012-12-01

341

Application of Acoustic and Optic Methods for Estimating Suspended-Solids Concentrations in the St. Lucie River Estuary, Florida  

Science.gov (United States)

Acoustic and optic methods were applied to estimate suspended-solids concentrations in the St. Lucie River Estuary, southeastern Florida. Acoustic Doppler velocity meters were installed at the North Fork, Speedy Point, and Steele Point sites within the estuary. These sites provide varying flow, salinity, water-quality, and channel cross-sectional characteristics. The monitoring site at Steele Point was not used in the analyses because repeated instrument relocations (due to bridge construction) prevented a sufficient number of samples from being collected at the various locations. Acoustic and optic instruments were installed to collect water velocity, acoustic backscatter strength (ABS), and turbidity data that were used to assess the feasibility of estimating suspended-solids concentrations in the estuary. Other data collected at the monitoring sites include tidal stage, salinity, temperature, and periodic discharge measurements. Regression analyses were used to determine the relations of suspended-solids concentration to ABS and suspended-solids concentration to turbidity at the North Fork and Speedy Point sites. For samples used in regression analyses, measured suspended-solids concentrations at the North Fork and Speedy Point sites ranged from 3 to 37 milligrams per liter, and organic content ranged from 50 to 83 percent. Corresponding salinity for these samples ranged from 0.12 to 22.7 parts per thousand, and corresponding temperature ranged from 19.4 to 31.8 ?C. Relations determined using this technique are site specific and only describe suspended-solids concentrations at locations where data were collected. The suspended-solids concentration to ABS relation resulted in correlation coefficients of 0.78 and 0.63 at the North Fork and Speedy Point sites, respectively. The suspended-solids concentration to turbidity relation resulted in correlation coefficients of 0.73 and 0.89 at the North Fork and Speedy Point sites, respectively. The adequacy of the empirical equations seems to be limited by the number and distribution of suspended-solids samples collected throughout the expected concentration range at the North Fork and Speedy Point sites. Additionally, the ABS relations for both sites seem to overestimate at the low end and underestimate at the high end of the concentration range. Based on the sensitivity analysis, temperature had a greater effect than salinity on estimated suspended-solids concentrations. Temperature also appeared to affect ABS data, perhaps by changing the absorptive and reflective characteristics of the suspended material. Salinity and temperature had no observed effects on the turbidity relation at the North Fork and Speedy Point sites. Estimates of suspended-solids concentrations using ABS data were less 'erratic' than estimates using turbidity data. Combining ABS and turbidity data into one equation did not improve the accuracy of results, and therefore, was not considered.

Patino, Eduardo; Byrne, Michael J.

2004-01-01

342

Polycyclic aromatic hydrocarbons and risk to threatened and endangered Chinook salmon in the Lower Columbia River estuary.  

Science.gov (United States)

Polycyclic aromatic hydrocarbons (PAHs), derived from oil and fuel combustion, are ubiquitous nonpoint source pollutants that can have a number of detrimental effects on fish and wildlife. In this study, we monitored PAH exposure in outmigrant juvenile Chinook salmon from the Lower Columbia River to evaluate the risk that these contaminants might pose to the health and recovery of threatened and endangered salmonids. Juvenile Chinook salmon (Oncorhynchus tshawytscha) were collected by beach seine from five sites in the Lower Columbia River from Bonneville Dam to the mouth of the estuary (Warrendale, the Willamette-Columbia Confluence, Columbia City, Beaver Army Terminal, and Point Adams) and from a site in the Lower Willamette near downtown Portland (Morrison Street Bridge). Sediment samples were also collected at the same sites. Concentrations of PAHs in sediment samples were relatively low at all sites with average total PAH concentrations 10,000 ng/g wet wt. Metabolites of low and high molecular-weight PAHs were also detected in bile of salmon from all sites; for metabolites fluorescing at phenanthrene (PHN) wavelengths, concentrations ranged from 1.1 to 6.0 ?g/mg bile protein. Levels of PAHs in stomach contents and PAH metabolites in bile were highest in salmon from the Morrison Street Bridge site in Portland and the Willamette-Columbia Confluence, Columbia City, and Beaver Army Terminal sites. Mean PAH concentrations measured in some stomach content samples from the Columbia City, Beaver Army Terminal, and Morrison Street Bridge sites were near the threshold concentration (approximately 7200-7600 ng/g wet wt.) associated with variability and immune dysfunction in juvenile salmonids (Meador et al., Can J Fish Aquat Sci 63:2364-2376, 2006; Bravo et al., Environ Toxicol Chem 30:704-714, 2011). Mean levels of biliary fluorescent aromatic compounds (FACs)-PHN in juvenile Chinook collected at the Morrison Street Bridge site in Portland, at the Confluence and Columbia City sites, and at the Beaver Army Terminal site were at or above a threshold effect concentration of 2 ?g/mg protein for FACs-PHN linked to growth impairment, altered energetics, and reproductive effects (Meador et al., Environ Toxicol Chem 27(4):845-853, 2008). These findings suggest that PAHs in the food chain are a potential source of injury to juvenile salmon in the Lower Columbia and Lower Willamette rivers. PMID:21894559

Yanagida, Gladys K; Anulacion, Bernadita F; Bolton, Jennie L; Boyd, Daryle; Lomax, Daniel P; Paul Olson, O; Sol, Sean Y; Willis, Maryjean; Ylitalo, Gina M; Johnson, Lyndal L

2012-02-01

343

Estuarial migration of Atlantic salmon in the River Dee (N. Wales)  

International Nuclear Information System (INIS)

This report describes work undertaken during the period April 1991 to December 1993 by the Welsh Region of the National Rivers Authority to investigate the behaviour of radio-tagged adult Atlantic salmon (Salmo salar L.) in the Welsh Dee. Partial funding for work in 1992 and 1993 was provided by the Department of Trade and Industry under their Tidal Energy research and development programme. (author)

344

Atmospheric influence on the distribution of organic pollutants in the Guadalquivir River estuary, SW Spain.  

Science.gov (United States)

In the lower Guadalquivir river basin, a system stressed by a wide variety of anthropogenic activities, eight pesticides (four triazines, two chloroacetanilide herbicides, one organochlorine, and one organophosphorus insecticide); and four emerging pollutants (two personal care products, one organophosphorous flame retardant, and one xanthine alkaloid) were analyzed in river water during a 2-year monitoring program, and after rain episodes. Samples were extracted using the solid phase extraction (SPE) technique prior to determination of compounds using gas chromatograph coupled to a mass spectrometer detector. Except for caffeine, recoveries were mostly above 80 %, while limits of detection and quantification were in the low nanograms per liter level (except for dimethoate). Terbuthylazine, simazine (triazine herbicides), and dimethoate (organophosphorus insecticide), present in agrochemicals, were predominant in the river water, although concentrations were below the quality standards established by the EU Water-Framework-Directive. A general trend to increase concentration was observed after rain events, in particular for pesticides, possibly as a consequence of surface runoff. PMID:23010894

Fernández-Gómez, Cristal; López-López, José Antonio; Matamoros, Victor; Díez, Sergi; García-Vargas, Manuel; Moreno, Carlos

2013-04-01

345

Cycling of transuranic radionuclides in the Columbia River, its estuary and the northeast Pacific Ocean. Progress report, 1 January 1983-31 December 1984  

International Nuclear Information System (INIS)

This report summarizes progress from 1 January 1983 through 31 December 1983 in research dealing with the behavior of transuranic and other radionuclides in the Columbia River downstream from the Hanford Reservation and in the northeast Pacific Ocean. The work summarized includes: (1) a comparison of the mass-spectrometric determination of Pu in biological samples between Savannah River and Battelle-Northwest; (2) the collection of biological samples from the Columbia River between Bonneville Dam and Ice Harbor Dam on the Snake River; (3) preparation of a manuscript detailing the sedimentation regimes in the lower Columbia River and the Columbia River Estuary; (4) preparation of a manuscript summarizing results to date on the inventories, sources and geochemical behavior of transuranic and other radionuclides in the lower Columbia River; (3) completion of measurements of McNary Reservoir cores for 152Eu and 154Eu; and (6) completion of initial measurements of selected McNary Reservoir sediments to confirm the presence of Ni-63

346

The salt water encroachment along the Lamone river artificial estuary: an issue for the coastal management in the Southern Po Plain Adriatic Coast (Italy).  

Science.gov (United States)

Recently, the problem of saltwater intrusion in shallow aquifers has been recognized across Europe as one of the major threats for freshwater resources in coastal areas. Italy is indicated as one of the countries most severely affected. The problem of saltwater encroachment into the coastal water system attracted the public opinion attention during the last summers, when, due to low rainfall and low discharge rates, the ingression of seawater along the Po river branches was measured 12 kilometres upstream of the river delta. This situation caused a weakening of agricultural activities (inability to irrigate crops and orchards) and led, in same cases, to the shutdown of electric power generation plants due to the lack of freshwater used for cooling. This study is carried out to quantify the saltwater encroachment along the Lamone river and to estimate its possible contribution to the salinization process of the shallow sandy aquifer in the area. The Lamone River is typical for one of the many small low-discharge rivers flowing from the Appennines and reaching the Adriatic sea after a 88 km course through the southern Po Plain. Its estuary was artificially constrained to the actual position in 1960 and this is the reason of its artificially rectified shape. The salt water encroachment phenomenon has been analyzed during 2008 with a monthly monitoring of electrical conductivity profiles in 31 stations along the terminal 8 kilometres of the river, from its upstream physical boundary (represented by an artificial dam built to collect water for the Ravenna city water treatment plant) and the sea. Measurements point out that the Lamone river estuary has sharp vertical water stratification. Bottom water conductivity values show the presence of saltwater (45 mS/cm) in the first 24 stations (starting from the sea) in almost all monitoring campaigns. At 6.5 km from the sea, the presence of a rocky sill protecting a pipeline represents an efficient threshold that blocks or in some cases just hinders the salt wedge traveling inland. The bathymetry of the river was also surveyed showing a very irregular bottom surface, characterized by the presence of deep holes. Saltwater remains trapped in these holes for a long time and this fact possibly represents the major source of salt in the interaction process between river and groundwater. On the basis of the field data, a simple analytical model, based on the equation of Schijf & Schoenfeld (1953) describing the length of the salt wedge intrusion with no tides, was built and calibrated. This simple tool was useful to evaluate the physical friction coefficient of the system and to investigate the relationships between friction and river discharge. The aim of this part of the study was to use such a model to evaluate the theoretical values of river discharge to be maintained in order to keep the salt wedge away from those sections of the river in direct connection with the permeable phreatic aquifer. We are currently evaluating some other analytical solutions proposed by Fisher (1974) and Savenije (1993), considering the influence of tides, to refine the values of the river's hydraulic parameters and to test the possibility of applying these more complex analytical models to small estuaries such as the Lamone river mouth, very different in spatial scale related to the study cases presented by these authors. The possibility of using these new analytical techniques will give us a tool for building a predictive model to be used in estimating the influence of different river management solutions and sea level rise scenarios in the salt wedge intrusion process.

Laghi, M.; Antonellini, M.; Minchio, A.; Stecchi, F.

2009-04-01

347

Preliminary assessment of the potential for mangrove oyster cultivation in Piraquê-açu river estuary (Aracruz, ES)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese No estuário do Rio Piraquê-açu, município de Aracruz, ES, foi avaliada a viabilidade técnica da implantação do cultivo de ostras Crassostrea rhizophorae em lanternas suspensas numa balsa de cultivo, através da estimativa de crescimento e ganho de peso fresco e seco das ostras. Verificou-se que, dura [...] nte os dez meses de cultivo (junho/98 a maio/99), as ostras atingiram, em média, 37,6 mm de altura e 3,0 g no peso total. Foi registrada uma alta taxa de mortalidade, que poderia ser atribuída aos altos valores de salinidade na água e também aos predadores observados como planárias Stylochoplana divae e gastrópodos Cymatium parthenopeum, além de incrustantes como cracas, poliquetos Serpulidae e principalmente sementes da própria ostra. Abstract in english At Piraquê-açu river estuary, Aracruz, ES, the technical viability of Crassostrea rhizophorae cultivation was determined through monthly measures in shell length and weight. Seeds of C. rhizophorae were put in cages and suspended in rafts. Increase in height and weight (flesh and dry) of the oysters [...] was measured. During ten months (July/98 to May/99), oyster shell reached an average of 37.6 mm in shell height and 3.0 g in flesh weight (the whole animal). High mortality rates were registered and could be related to the high salinity water and to high predation observed, especially by flatworms Stylochophana divae and snails Cymatium parthenopeum, as well as fouling organisms such as barnacles, Serpulidae polychaetes and seed of the same species.

Luciana, Alvarenga; Rosebel Cunha, Nalesso.

2006-01-01

348

The environment effect on fish assemblage structure in waters adjacent to the Changjiang (Yangtze) River estuary (1998-2001)  

Science.gov (United States)

We collected fish abundance data in the Changjiang (Yangtze River) estuary and adjacent waters in November 1998, May 1999, November 2000, and May 2001. Using the data, we evaluated the characteristics of the fish assemblages at each site and investigated the effect of several environmental factors. We used a multivariate analysis, including community ordination methods such as detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA), and two-way indicator species analysis (TWINSPAN). We analyzed the biological community structure and environmental factors to determine their spatial distributions, temporal dynamics, and seasonal variations. Among the fish species, five exceeded 5% of the total abundance: Harpodon nehereus (42.82%), Benthosema pterotum (13.85%), Setipinna taty (11.64%), Thryssa kammalensis (9.17%) and Apogonichthys lineatus (6.49%). These were separated into four ecological assemblages: hypsithermal-saline, hypsithermal-brackish, hypothermal-brackish, and hypothermal-saline. We evaluated the degree of influence of environmental factors on the fish community. Our analyses suggested that environmental factors including water depth, salinity, turbidity, transparency, nutrient, and suspended matter formed a synthetic spatial gradient between the coastal and pelagic areas. Ecological and environmental factors changed temporally from 1998 to 2001, and drove the fish community succession. The environmental factors driving the fish community structure included bottom temperature, water depth, bottom and surface pH, surface total phosphorous, and bottom dissolved oxygen. This investigation was completed before completion of the Three Gorges Dam; therefore the results of this study provide an important foundation for evaluating the influence of the human activities.

Yu, Haicheng; Xian, Weiwei

2009-09-01

349

Ecophysiological characteristics of invasive Spartina alterniflora and native species in salt marshes of Yangtze River estuary, China  

Science.gov (United States)

Biological invasions represent one of the significant components of global change. A comparative study of invaders and co-occurring natives is a useful approach to gaining insights into the invasiveness of exotic plants. Spartina alterniflora, a C 4 grass, is a widespread invader in the coastal wetlands in China and other regions of the world. We conducted a comparative study of S. alterniflora and native C 3 species, Phragmites australis and Scirpus mariqueter, in terms of their gas exchange and efficiencies in resource utilization. We tested the hypothesis that S. alterniflora has growth-related ecophysiological advantages over the natives in its non-native range, which result in its rapid growth and enhance its invasiveness. Photosynthesis, leaf area index (LAI), specific leaf area (SLA), and the efficiency of resource use (light, water, and nitrogen) were examined monthly for eight months in 2004. Overall, S. alterniflora had greater LAI, higher maximal net photosynthetic rate ( Amax), and longer growing season than those of the native species. On average, the efficiencies of S. alterniflora in light, water, and nitrogen utilization were respectively 10.1%, 26.1%, and 33.1% higher than those of P. australis, and respectively 70.3%, 53.5%, 28.3% higher than those of S. mariqueter. However, SLA of S. alterniflora was significantly lower than those of P. australis and S. mariqueter. Although there was no general pattern in the relationship between invasiveness and plant photosynthetic types, in this study, most of the ecophysiological characteristics that gave S. alterniflora a competitive advantage in the Yangtze River estuary were associated with photosynthetic pathways. Our results offer a greater understanding of the relationship between invasiveness and plant photosynthetic type. Our results also indicate that LAI and the length of the photosynthetic season, which vary with habitats, are also important in invasion success.

Jiang, Li-Fen; Luo, Yi-Qi; Chen, Jia-Kuan; Li, Bo

2009-01-01

350

[Community composition, seasonal dynamics and interspecific correlation of waterbirds in the Qiantangjiang River estuary and Hangzhou Bay].  

Science.gov (United States)

Waterbird surveys were conducted regularly in the Qiantangjiang River estuary and Hangzhou Bay from July 2007 to November 2011. A total of 128 species (nine orders and 18 families) were recorded, including 119 migrants which accounted for 93% of the total species; eleven species were listed as National Protected Species. Inter-specific correlation analysis for 13 shorebird populations and nine duck populations recorded over time found that 21 pairs of shorebirds and 23 pairs of ducks were correlated. By looking at seasonal dynamics and migration patterns we were able to divide the migration process into six stages: (1) late July to late September was the migration peak of shorebirds, which were dominated by Limosa limosa, Calidris ruficollis and Charadrius mongolus. (2) Early October to mid-December was the migration peak of wintering migrants of shorebirds and ducks, which were the first two large groups in our study areas. (3) Late December to mid-February was the wintering period of migration waterbirds. (4) Late February to late March was the peak migration of ducks and the winter migrants of shorebirds dominated by Calidris alpina. (5) Early April to mid-May was the migration peak of passage migrants such as, Calidris ruficollis, Calidris acuminate and Limosa limosa but the population size of shorebird winter migrants dominated by Calidris alpine was still larger than the former. (6) Late May to mid-July was the breeding season of all egrets, summer migrants of gulls and several species of shorebirds. Our surveys show that interaction among species is possibly an important determinant of community composition of shorebirds and wintering ducks during the migration season. It may be the geographical position and community composition of migrant shorebirds across Hangzhou Bay that mean during the northward migration there are far more shorebirds than during the southward migration. PMID:22184022

Jiang, Ke-Yi; Wu, Ming; Shao, Xue-Xin

2011-12-01

351

Impacts of potential future sea level rise on the North branch of the Changjiang river estuary: Quantifying the saline water intrusion in the dry season  

OpenAIRE

The phenomenon of global sea level rise (SLR) is undeniable; the 4th IPCC report summaries that the average rise rate of global is 1.8 mm/y since 1961. It is widely taken for granted that SLR will have a severe impact on saline water intrusion processes in estuarine areas. In this paper, by using a two-dimensional hydrodynamic model (MIKE21) and SLR scenarios of 0.5m, 1m and 2m, the impacts of potential future SLR on the North Branch of the Changjiang River Estuary are evaluated b...

Kuang, C. P.; Chen, W.; Gu, J.; Mao, X. D.; Huang, H. C.

2013-01-01

352

Cycling of transuranic radionuclides in the Columbia River, its estuary and the northeast Pacific Ocean. Progress report, February 1979-February 1980  

International Nuclear Information System (INIS)

This report summarizes progress from February 1979 through January 1980 on the measurement of radionuclides in the Columbia River and its estuary, with principal emphasis on transuranic radionuclides. Accomplishments and pertinent findings of the 3 year interval are summarized and future directions for the research are presented. The first part of the report will draw on information contained in the previous two submissions as well as results from this contract year. This will hopefully present a synoptic view for outside reviewers and the Department of Energy

353

Spatial and temporal variations of nitrous oxide flux between coastal marsh and the atmosphere in the Yellow River estuary of China  

OpenAIRE

To investigate the spatial and seasonal variations of nitrous oxide (N2O) fluxes and understand the key controlling factors, we explored N2O fluxes and environmental variables in high marsh (HM), middle marsh (MM), low marsh (LM), and mudflat (MF) in the Yellow River estuary throughout a year. Fluxes of N2O differed significantly between sampling periods as well as between sampling positions. During all times of day and the seasons measured, N2O fluxes ranged from ?0.0051 to 0.0805 mg N2O ...

Sun, Zhigao; Wang, Lingling; Mou, Xiaojie; Jiang, Huanhuan; Sun, Wanlong

2013-01-01

354

DISTRIBUTIONS AND SOURCES OF ALIPHATIC HYDROCARBONS AND KETONES IN SURFACE SEDIMENTS FROM THE CROSS RIVER ESTUARY, S.E. NIGER DELTA, NIGERIA  

OpenAIRE

Surface sediments from the Cross River estuary were analyzed for the quantitative determination of aliphatic lipids such as n-alkanes, n-alkanones and unresolved complex mixtures (UCMs) of branched and cyclic hydrocarbons. The concentrations of the hydrocarbons, including pristane and phytane, were in the range of 0.02-16.84 mg kg-1 (mean 2.23 ± 2.25 mg kg-1 dry weight). The high standard deviations for the n-alkanes most likely reflect the variation in sediment grain size and differences in...

Oros, Daniel R.; Ekpo, Bassey O.; Oyo-ita, Orok E.; Simoneit, Bernd R. T.

2010-01-01

355

Strontium isotope record of seasonal scale variations in sediment sources and accumulation in low-energy, subtidal areas of the lower Hudson River estuary  

Science.gov (United States)

Strontium isotope (87Sr/86Sr) profiles in sediment cores collected from two subtidal harbor slips in the lower Hudson River estuary in October 2001 exhibit regular patterns of variability with depth. Using additional evidence from sediment Ca/Sr ratios, 137Cs activity and Al, carbonate (CaCO3), and organic carbon (OCsed) concentration profiles, it can be shown that the observed variability reflects differences in the relative input and trapping of fine-grained sediment from seaward sources vs. landward sources linked to seasonal-scale changes in freshwater flow. During high flow conditions, the geochemical data indicate that most of the fine-grained sediments trapped in the estuary are newly eroded basin materials. During lower (base) flow conditions, a higher fraction of mature materials from seaward sources with higher carbonate content is trapped in the lower estuary. Results show that high-resolution, multi-geochemical tracer approaches utilizing strontium isotope ratios (87Sr/86Sr) can distinguish sediment sources and constrain seasonal scale variations in sediment trapping and accumulation in dynamic estuarine environments. Low-energy, subtidal areas such as those in this study are important sinks for metastable, short-to-medium time scale sediment accumulation. These results also show that these same areas can serve as natural recorders of physical, chemical, and biological processes that affect particle and particle-associated material dynamics over seasonal-to-yearly time scales. ?? 2009.

Smith, J.P.; Bullen, T.D.; Brabander, D.J.; Olsen, C.R.

2009-01-01

356

Impact of industrial and mine drainage wastes on the heavy metal distribution in the drainage basin and estuary of the Sado River (Portugal).  

Science.gov (United States)

This paper presents results from a survey of the heavy metal distribution in sediments in the drainage basin and estuary of the Sado River (Portugal). In the drainage basin, heavy metals originate mostly from pyrite outcrop erosion and mining activities (Cd, Zn, Cu and locally Hg, Pg), and also from crust erosion (Sn, Ni, Ti, Zr). These sources are not correlated with the particulate organic carbon (POC) and so the metals are thought to be in inorganic forms in this area. Anthropogenic heavy metal sources (urban and industrial) are found in the lower estuary (Sn, Cd, Hg, Zn, Pb and Cu) along with high POC concentrations. In this zone, these metals are thought to be strongly adsorbed onto organic particles. Furthermore, organo-metallic species are likely to be present, as demonstrated in the case of Sn, since methyl- and butyl-tin species were detected in sediments from this area. This suggests the need for the detection of organo-metallic species to understand the heavy metal geochemical cycles. No long-term changes in metal concentrations are found in sediment cores, except in the middle estuary (Zn, Cu) due to the development of mining activities on an industrial scale in the 1860s. PMID:15092396

Quevauviller, P; Lavigne, R; Cortez, L

1989-01-01

357

Mercury emission factors from intensive shrimp aquaculture and their relative importance to the Jaguaribe River Estuary, NE Brazil.  

Science.gov (United States)

This study estimated Hg emission factors (EFs) and total Hg loading to the Jaguaribe Estuary, NE Brazil, from intensive shrimp farming, and compares this with other local anthropogenic activities. The EF reached 83.5 mg ha(-1) cycle(-1) (about 175 mg ha(-1) year(-1)), resulting in an annual Hg load to the estuary of 0.35 kg. The calculated EF is comparable to Hg EFs from urban wastewaters (200 mg ha(-1)) and solid waste disposal (400 mg ha(-1) year(-1)) from cities located in the estuary's basin. However, due to the smaller area of aquaculture (2,010 ha), total annual loads are much lower than from these other sources (75 and 150 kg year(-1), respectively). Since shrimp farming effluents are released directly into the estuary, the estimated high EF raises environmental concerns with this expanding industry, suggesting the inclusion of this element in ongoing environmental monitoring programs. PMID:21922284

Lacerda, L D; Soares, T M; Costa, B G B; Godoy, M D P

2011-12-01

358

Geographic variability in amoeboid protists and other microbial groups in the water column of the lower Hudson River Estuary (New York, USA)  

Science.gov (United States)

In comparison to other groups of planktonic microorganisms, relatively little is known about the role of amoeboid protists (amebas) in planktonic ecosystems. This study describes the first geographic survey of the abundance and biomass of amebas in an estuarine water column. Samples collected in the lower Hudson River Estuary were used to investigate relationships between ameba abundance and biomass and hydrographic variables (temperature, salinity, and turbidity), water depth (surface and near bottom), distance from mid-channel to shore, phytoplankton biomass (chlorophyll fluorescence) and the occurrence of other heterotrophic microbial groups (heterotrophic bacteria, nanoflagellates, and ciliates) in the plankton. Although salinity increased significantly towards the mouth of the estuary, there were no significant differences in the abundance or biomass of any microbial group in surface samples collected at three stations separated by 44 km along the estuary's mid-channel. Peak biomass values for all microbial groups were found at the station closest to shore, however, cross-channel trends in microbial abundance and biomass were not statistically significant. Although ameba abundance and biomass in most samples were low compared to other microbial groups, clear patterns in ameba distribution were nevertheless found. Unlike other microbial groups examined, ameba numbers and biomass greatly increased in near bottom water compared to surface samples. Ameba abundance and biomass (in surface samples) were also strongly related to increasing turbidity. The different relationships of ameba abundance and biomass with turbidity suggest a rising contribution of large amebas in microbial communities of the Hudson estuary when turbidity increases. These results, emphasizing the importance of particle concentration as attachment and feeding surfaces for amebas, will help identify the environmental conditions when amebas are most likely to contribute significantly to estuarine bacterivory and C-flux.

Juhl, Andrew R.; Anderson, O. Roger

2014-12-01

359

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 dis