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1

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

UK PubMed Central (United Kingdom)

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.

Chen XW; Cai LZ; Wu C; Peng X; Cao J; Xu P; Liu S; Fu SJ

2012-04-01

2

The distribution of acid-volatile sulfide and simultaneously extracted metals in sediments from a mangrove forest and adjacent mudflat in Zhangjiang Estuary, China.  

UK PubMed Central (United Kingdom)

The distribution of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) were studied in sediments collected from mangrove forest, forest fringe and adjacent mudflat in the Zhangjiang Estuary, China. The aim was to examine the spatial distribution of AVS and SEM in sediments of the Estuary and determine the influence of mangrove trees on AVS and SEM concentrations in the sediments. The results indicated that AVS concentrations in forest sediments were significantly lower than those in mudflat sediments. There was a significant positive correlation between AVS values and moisture contents in forest sediments, while LOI played an important role in AVS concentrations of mudflat sediments. In the forest sediment core, the peak value of AVS appeared deeper in the sediment profile compared to it appeared in the mudflat core. The distribution of SEM showed different trends from that of AVS, and potential toxicity existed in the upriver forest sediments.

Jingchun L; Chongling Y; Spencer KL; Ruifeng Z; Haoliang L

2010-08-01

3

Mouth Bar Formation in Yangtze River Estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The periodic shifting of the bifurcation point of the North Channel and South Channel of the Yangtze river is very important in the estuary. The North Channel is bifurcated from the South Branch by cutting a channel through the submerged sandbanks. Once a bifurcation channel is formed, the differen...

Wei, C.

4

Benthic primary production in the Columbia River Estuary. Final report  

Energy Technology Data Exchange (ETDEWEB)

The general objective of the research associated with the Benthic Primary Production Work Unit of Columbia River Estuary Development Program was to determine mechanisms that control the production dynamics and species composition of benthic plant assemblages in the Columbia River Estuary. In particular, the work was concerned with effects of selected physical variables on structural and functional attributes of micro- and macro- vegetation, and on the productivity and biomass of benthic autotrophs on the tidal flats of the estuary.

McIntire, C.D.; Amspoker, M.C.

1984-02-01

5

Methane in surface waters of Oregon estuaries and rivers  

Energy Technology Data Exchange (ETDEWEB)

Methane concentrations in surface waters of Oregon rivers and estuaries were measured over a four-year period. Geographic variations in riverine CH{sub 4} were observed. Results from undisturbed forest streams indicate that rivers can contain high natural levels of CH{sub 4} not attributable to pollution. Lateral diffusion and runoff from saturated forest and fertilized agricultural soils may be important in determining methane levels in rivers. Methane concentrations in well-flushed estuaries appear to be controlled mainly by mixing between high CH{sub 4}-containing river water and low CH{sub 4}-containing seawater endmembers. Rivers and estuaries were found to be sources of methane to the atmosphere. Calculated daily fluxes to the atmosphere ranged from 1.2 to 71 mg CH{sub 4} sq m for rivers and from 0.04 to 21 mg CH{sub 4} sq m for estuarine samples. 24 refs., 4 figs., 3 tabs.

de Angelis, M.A.; Lilley, M.D. (Washington Univ., Seattle (USA))

1987-05-01

6

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

Energy Technology Data Exchange (ETDEWEB)

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

Dion, E.P.

1983-01-01

7

Conservation of Thane Creek and Ulhas River Estuary, India.  

Science.gov (United States)

There has been a steady decrease in the area occupied by wetlands in creeks and estuaries adjacent urban areas due to unprecedented urban growth in coastal cities, for example, Thane Creek and Ulhas River Estuary near Mumbai, India. Urban cities serve as centres of employment and attract a large number of migrants from other places. In case of coastal cities, due to inadequate infrastructure, wastewater and solid waste are disposed of into wetlands and estuary. Discharge of sediments and solid waste into the creeks from drains and construction activities has resulted in decreased flow depth in the coastal waters of Thane Creek and Ulhas River Estuary. Various researchers have studied individual elements of Thane Creek and Ulhas River Estuary at micro level. However, a holistic approach for restoration and conservation of the creek and estuary is required. This paper presents the details of an integrated approach incorporating different conservation measures such as sewerage and sewage treatment, urban drainage management, solid waste management, mangrove plantation and dredging. PMID:21117428

Nikam, Vinay S; Kumar, Arun; Lalla, Kamal; Gupta, Kapil

2009-07-01

8

Conservation of Thane Creek and Ulhas River Estuary, India.  

UK PubMed Central (United Kingdom)

There has been a steady decrease in the area occupied by wetlands in creeks and estuaries adjacent urban areas due to unprecedented urban growth in coastal cities, for example, Thane Creek and Ulhas River Estuary near Mumbai, India. Urban cities serve as centres of employment and attract a large number of migrants from other places. In case of coastal cities, due to inadequate infrastructure, wastewater and solid waste are disposed of into wetlands and estuary. Discharge of sediments and solid waste into the creeks from drains and construction activities has resulted in decreased flow depth in the coastal waters of Thane Creek and Ulhas River Estuary. Various researchers have studied individual elements of Thane Creek and Ulhas River Estuary at micro level. However, a holistic approach for restoration and conservation of the creek and estuary is required. This paper presents the details of an integrated approach incorporating different conservation measures such as sewerage and sewage treatment, urban drainage management, solid waste management, mangrove plantation and dredging.

Nikam VS; Kumar A; Lalla K; Gupta K

2009-07-01

9

Tritium in the Savannah River estuary and adjacent marine waters  

International Nuclear Information System (INIS)

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

1976-06-21

10

Hydrographic and chemical observations in the Sierra Leone River estuary  

International Nuclear Information System (INIS)

Hydrographic and chemical observations in the Sierra Leone River estuary are reported, a West-African river in the tropics. Because of the typical change between rainy season in the sommer months and dry season in winter time the research work has been adapted to these semi-annual changes. The collected data and results are given and discussed under this aspect of the seasonal fluctuations. (orig.)

1979-01-01

11

Trace elements distribution in bottom sediments from Amazon River estuary  

International Nuclear Information System (INIS)

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

1994-09-02

12

The recreational value of river inflows into South African estuaries  

Scientific Electronic Library Online (English)

Full Text Available 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, river 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 re (more) duced. This paper reports findings on these negative impacts for selected estuaries. The contingent valuation method was used to estimate the value of recreational benefits that would result at 40 South African estuaries if water-inflow reductions were averted. The studies were undertaken between 2000 and 2007. All the estuaries selected were known to be vulnerable to changes in river inflows. Expert opinions on the consequences of specified hypothetical changes to water inflows into estuaries were used to generate the scenarios valued. User populations were estimated and surveys administered to samples of these populations. From the elicited responses median estuary user willingness to pay bids were predicted using Tobit and OLS models. An internal credibility assessment was conducted over the plausibility of the predictive model, the consistency of the values to those estimated using an alternative valuation method (the contingent travel cost method), and the reliability of the estimates. For the 37 estimates deemed reliable (but not necessarily valid), the average of the predicted median values of river inflow into estuaries was calculated to be 3.4 c/m³ (South African cents, ZAR) and standard deviation 3.84 c/m³. The average of the predicted mean values was calculated to be 7.4 c/m³ and the standard deviation 6.7 c/m³. It was also found that where there had been extensive economic development around the river system, the values of inflows into estuaries tended to be less than the value of water abstracted upstream.

Hosking, Stephen

2011-01-01

13

78 FR 23746 - Takes of Marine Mammals Incidental to Specified Activities; Russian River Estuary Management...  

Science.gov (United States)

...Mammals Incidental to Specified Activities; Russian River Estuary Management Activities AGENCY...activities conducted at the mouth of the Russian River, Sonoma County, California. DATES...Biological Opinion (2008) on the effects of Russian River management activities on...

2013-04-22

14

???????????????? Research on Changes of Peak Water Level in the Pearl River Estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

???????????????????????????????????????????????????????????????????????1) 20??50???????????????????????????2) ???????????????20??90???????????????????????????????????????1981??1983??3) ??????????????????????????????????? Higher peak water level of the Pearl River Estuary gives a great t...

??; ???; ???; ???; ???; ???

15

Linking the river to the estuary: influence of river discharge on tidal damping  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of river discharge on tidal damping in estuaries is explored within one consistent theoretical framework where analytical solutions are obtained by solving four implicit equations, i.e., the phase lag, the scaling, the damping and the celerity equation. In this approach the damping equation is obtained by subtracting the envelope curves of high water and low water occurrence, taking into account that the flow velocity consists of a tidal and river discharge component. Different approximations of the friction term are considered in deriving the damping equation, resulting in as many analytical solutions. In this framework it is possible to show that river discharge affects tidal damping primarily through the friction term. The application to the Modaomen and Yangtze estuaries demonstrates that the influence of river discharge on tidal damping can be significant in the upstream part of an estuary where the ratio of river flow to tidal flow amplitude is substantial. The analytical model is able to describe the main tidal dynamics with realistic roughness values in the upper part of the estuary, while a model with negligible river discharge can be made to fit observations only with unrealistically high roughness values. Moreover, the damping equation can be used to estimate river discharge on the basis of observed tidal damping, which makes the proposed analytical model a tool to obtain indirect information about quantities that are difficult to measure in the tidal region.

H. Cai; H. H. G. Savenije; M. Toffolon

2013-01-01

16

Water and suspended sediment dynamics in Selangor River estuary  

International Nuclear Information System (INIS)

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

2001-01-01

17

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 plume were studied to elucidate processes which control the flux of nuclides to the sea. Major ions (Ca, Mg, Na, Cl, Bicarbonate) and selected trace elements (Ra, Ba, Cu, Si) are introduced to the Connecticut River in proportion to the total dissolved load of various groundwaters. Si, Ra, and Ba are subject to removal from solution by seasonal diatom productivity; whereas the other groundwater-derived elements are found in proportion to TDS both time and space. These nuclides are released in the estuary when a portion of the Ra, Ba, and Si in riverine biogenic detritus is trapped in salt marshes and coves bordering the estuary where it redissolves and is exported to the main river channel at ebb tide. In the Amazon River estuary, the Ra and Ba are released in mid-salinity waters. Ra and Ba together with Si are subsequently removed by diatom productivity as reflected in increased Ra and Ba in the suspended particles and depleted dissolved nuclide concentrations in samples from the high productivity zone. In both the Connecticut River system and the Amazon River plume, Cu behaves conservatively; whereas the fates of Fe and Al are linked to soil-derived humic acids. Trace elements in Amazon plume sediments are found simply in proportion to the percentage of fine-grained size materials, despite low Th-228/Ra-228 mean residence times in the plume and the presence of Cs-137 in the sediment column. Estimates of the total flux of nuclides to the oceans can best be calculated on a mass balance basis using groundwater inputs. Unless significant repositories for nuclides exist in the river-estuarine system, the groundwater flux of dissolved nuclides is net flux to the ocean despite the reactions which occur in both rivers and estuaries.

1983-01-01

18

Local flows in the Quequen Grande River Estuary, Argentina  

International Nuclear Information System (INIS)

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

2009-05-01

19

Macrobenthic community in the Xiaoqing River Estuary in Laizhou Bay, China  

Science.gov (United States)

The macrobenthic community of the Xiaoqing River Estuary and the adjacent sea waters was investigated in May and November 2008, August 2009, and May and September 2010, respectively. A total of 95 species of macrobenthos were identified in the five cruises and most of them were polychaetes (46.39%), mollusks (28.86%) and crustaceans (20.62%). The Shannon-Wiener index of macrobenthos was lower than 2 in 67% sites. Along the stream channel, estuary and the coastal waters, the species of polychaetes reduced gradually, while the abundance increased at first and then decreased. The abundance was the biggest at regions with salinity of 5-20 in the estuary. The species and abundance of mollusks and crustaceans increased gradually. As for seasonal distribution, the species, abundance and biomass were higher in spring and lower in summer and autumn. Contemporaneously compared with Laizhou Bay and Yellow River Estuary, the species of macrobenthos appeared in the Xiaoqing River Estuary were much less, while the percentage of polychaetes was higher. Abundance and biomass were higher in Xiaoqing River estuary, then consequently followed by Laizhou Bay and Yellow River Estuary. The dominant species in Xiaoqing River Estuary was polychaete, and Layzhou Bay mollusk. The community structure characteristics of macrobenthos in the Xiaoqing River Estuary revealed a significant pollution status in this region.

Luo, Xianxiang; Zhang, Shanshan; Yang, Jianqiang; Pan, Jinfen; Tian, Lin; Zhang, Longjun

2013-09-01

20

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.)

2003-01-01

 
 
 
 
21

Organic matter in North Dvina River estuary  

Energy Technology Data Exchange (ETDEWEB)

The dissolved and suspended C /SUB org/ and hydrocarbons were studied in the mixing zone of river and sea water in the southern part of the Dvina gulf. Differences were established in the distribution of C /SUB org/ in the surface and benthic waters. It was shown that with water chlorine content about 2%, there is an increased concentration of suspended C /SUB org/ in the surface waters with simultaneous decrease in the dissolved C /SUB org/ as a result of colloid flocculation when the fresh and sea waters mix.

Artem' yev, V.Ye.; Idzhiyan, M.G.; Lazareva, Ye.V.

1984-01-01

22

Environmental contaminants in bald eagles in the Columbia River estuary  

Energy Technology Data Exchange (ETDEWEB)

Eggs, blood, and carcasses of bald eagles (Haliaeetus leucocephalus) and fish were collected and breeding success of eagles was monitored in the Columbia River estuary, 1980-87, to determine if contaminants were having an effect on productivity. High levels of dichloro diphenyl dichloroethylene (DDE), polychlorinated biphenyls (PCB's), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were found in eggs, blood from adults, and 2 eagle carcasses. Detectable levels of DDE and PCB's were found in blood of nestlings indicating they were exposed to these contaminants early in life. Increasing concentrations of DDE and PCB's with age also indicated accumulation of these contaminants. Adult eagles also had higher levels of mercury (Hg) in blood than subadults or young indicating accumulation with age. The high levels of DDE and PCB's were associated with eggshell thinning ([bar x] = 10%) and with productivity ([bar x] = 0.56 young/occupied site) that was lower than that of healthy populations (i.e., [ge]1.00 young/occupied site). DDE and PCB's had a deleterious effect on reproduction of bald eagles in the estuary. The role dioxins play in eagle reproduction remains unclear, but concentrations in eagle eggs were similar to those in laboratory studies on other species where dioxins adversely affected hatchability of eggs. Probable source of these contaminants include dredged river sediments and hydroelectric dams, and the proper management of each may reduce the amount of contaminants released into the Columbia River estuary. 46 refs., 1 fig., 4 tabs.

Anthony, R.G.; Garrett, M.G. (Oregon State Univ., Corvallis (United States)); Schuler, C.A. (Fish and Wildlife Service, Portland, OR (United States))

1993-01-01

23

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Highly mutagenic compounds such as some PAHs have been identified in surface waters and sediments of the Seine river estuary. Suspended particulate matter (SPM) represents a dynamic medium that may contribute to the exposure of aquatic organisms to toxic compounds in the water column of the estuary....

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

24

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

25

Zooplankton, Water Temperature, and Salinities in the Columbia River Estuary, December 1971 through December 1972.  

Science.gov (United States)

Sampling was conducted at seven stations in the Columbia River estuary throughout 1972 to provide baseline information on species diversity, relative abundance, and seasonal occurrence of zooplankton, as well as ambient water temperatures and salinities. ...

D. A. Misitano

1974-01-01

26

Time Series Analysis of Water Level and Temperature in the St Louis River Estuary  

Science.gov (United States)

Pressure and temperature loggers were deployed at 9 sites in the St Louis River estuary between 6/23 10/31 2011. A reference sensor was place on the shore to correct pressure data. Sensors were paced at ...

27

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...

28

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

Energy Technology Data Exchange (ETDEWEB)

The Tinto and Odiel river drain 100 km from the Rio Tinto sulphide mining district and join at a 20-km estuary entering the Atlantic Ocean. A reconnaissance study of heavy metal anomalies in channel sand and overbank mud of the river and estuary shows the following upstream to downstream ranges in ppm ([mu]g g[sup [minus]1]): As 3,000 to <200, Cd 30 to <0.1, Cu 1,500 to 10, Pb 2,000 to <10, Sb 300 to <150, and Zn 3,000 to <200. Organic-rich sandy-silty overbank clay has been analyzed to represent suspended load materials. The high content of heavy metals in the overbank clay throughout the river and estuary systems indicates the importance of suspended sediment transport for dispersing heavy metals from natural erosion and anthropogenic mining activities of the sulfide deposit. The organic-poor river bed sand has been analyzed to represent bedload transport of naturally-occurring sulfide minerals. The sand has high concentrations of metals upstream, decreasing by an order of magnitude in the lower estuary. Although heavy metal contamination of estuary mouth beach sand has been diluted to background levels, estuary mud exhibits increased contamination apparently related to finer grain size, higher organic carbon content, precipitation of river-borne dissolved solids, and input of anthropogenic heavy metals from industrial sources. The contaminated estuary mud disperses to the inner shelf mud belt and offshore suspended sediment, which exhibit metal anomalies from natural erosion and mining of upstream Rio Tinto sulphide lode sources (Pb, Cu, Zn) and industrial activities within the estuary (Fe, Cr, Ti). Because heavy metal contamination of Tinto-Odiel river sediment reaches or exceeds the highest levels encountered in other river sediments of Spain and Europe, a detailed analysis of metals in water and suspended sediment throughout the system, and epidemiological analysis of heavy metal effects in humans is appropriate. 36 refs., 8 figs., 4 tabs.

Nelson, C.H.; Lamothe, P.J. (Geological Survey, Menlo Park, CA (United States))

1993-12-01

29

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.

Kalina M. Manoylov; Joseph N. Dominy Jr.

2013-01-01

30

Dissolved inorganic nutrients and chlorophyll A in an estuary receiving sewage treatment plant effluents: Cachoeira River estuary (NE Brazil).  

UK PubMed Central (United Kingdom)

Sampling was conducted monthly during a transition period between the dry and rainy seasons in order to evaluate the effectiveness of a municipal sewage treatment plant (STP) in eutrophication control. STP effluent and fluvial input data were also estimated. In the dry period, high concentrations of nutrients, chlorophyll a (up to 360 ?g?L(-1)), and anoxia in bottom waters were observed in the upper portion of the estuary. Nitrate was scarce during the dry months, although high concentrations were observed at the river sources and the upper estuary. The N:P and Si:P molar ratios were usually below 16:1, and the Si:N ratio was higher than 1:1. The fluvial inputs were a greater source of nutrients to the estuary than the STP, but nutrient loading by these effluents were also important in contributing to the eutrophication of the upper estuarine zone, especially in the dry season when symptoms were more intense.

Silva MA; Eça GF; Santos DF; Guimarães AG; Lima MC; de Souza MF

2013-07-01

31

Salinity intrusions into the Selangor River estuary and its effect on the mangrove species sonneratia caseolaris  

International Nuclear Information System (INIS)

Vertical profiles of salinity, temperature and suspended sediment concentration (using OBS sensors) were measured along the longitudinal axis of the Sungai Selangor estuary during neap and spring high waters for different river discharges. These were supplemented by anchor station measurements (Which include tidal current velocity) in the lower and middle of the estuary over neap and spring tidal cycles. The results of these measurements showed that for low and medium river discharges the estuary changed from partially-mixed during the neaps to a well -mixed one during the springs. During high river discharges, the estuary became a salt-wedge type for both neap and spring tidal cycles. The maximum limit of salt water intrusion reached some 16 km from the river mouth which was recorded during a low river discharges (6.0 m3/s) on a medium tide ( tidal range 3.2 m), but this was reduced to about half the distance during high river discharges. During the maximum intrusion, the salt water did not reach Kg Kuantan, the attraction centre for the fireflies display, which dwells on mangrove species sonneratia caseolaris (Beremban trees). The measurements also indicated that the mangrove species was not found in the lower estuary where the salinity frequently exceeded 10 ppt. However, these trees grow along the river banks upstream of Kg Kuantan where it could occasionally exposed to salt water. This indicates that the salinity has some influence on the distribution of sonneratia caseolaris along Sungai Selangor and this natural balance shall maintained. (Author)

2002-01-01

32

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

Science.gov (United States)

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

Jiang, Xuezhong; Lu, Bing; He, Yuhong

2013-10-01

33

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

34

Heavy metals in bivalves collected from river estuaries of Thailand. [Perna viridis  

Energy Technology Data Exchange (ETDEWEB)

This investigation was undertaken to determine the levels of lead, zinc, copper, cadmium, and mercury in five species of bivalves collected from six river estuaries of Thailand during July 1978 to January 1979. The in situ bioassay for studying heavy metals uptake by green mussels (Perna viridis) was also conducted at the Chao Phraya river estuary during February 1980 to March 1981. The results revealed high contamination of lead in mussels during the period of river run-off. The factors that might contribute to this incidence were discussed. Contaminations of the other four metals in bivalves did not show great variation and they were still within the acceptable limits.

Menasveta, P.; Cheevapora, V.; Wongwit, C.

1984-01-01

35

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

Science.gov (United States)

The Tinto and Odiel rivers drain 100 km from the Rio Tinto sulphide mining district, and join at a 20-km long estuary entering the Atlantic Ocean. A reconnaissance study of heavy metal anomalies in channel sand and overbank mud of the river and estuary by semi-quantitative emission dc-arc spectrographic analysis shows the following upstream to downstream ranges in ppm (??g g-1): As 3,000 to Tinto sulphide lode sources (Pb, Cu, Zn) and industrial activities within the estuary (Fe, Cr, Ti). Because heavy metal contamination of Tinto-Odiel river sediment reaches or exceeds the highest levels encountered in other river sediments of Spain and Europe, a detailed analysis of metals in water and suspended sediment throughout the system, and epidemiological analysis of heavy metal effects in humans is appropriate. ?? 1993 Estuarine Research Federation.

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

1993-01-01

36

Electrochemical determination of dissolved uranium in Krka River estuary.  

Science.gov (United States)

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

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

2001-06-01

37

Electrochemical determination of dissolved uranium in Krka River estuary.  

UK PubMed Central (United Kingdom)

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

Djogi? R; Pizeta I; Branica M

2001-06-01

38

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

39

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 (

1992-01-01

40

Comprehensive analysis of an ecological risk assessment of the Daliao River estuary, China.  

UK PubMed Central (United Kingdom)

At present, most estuarine ecological risk studies are based on terrestrial ecosystem models, which ignore spatial heterogeneity. The Daliao River estuary has representative characteristics of many estuaries in China, and we used this estuary as the study area to formulate an estuarine ecological risk evaluation model. Targeting the estuary's special hydrodynamic condition, this model incorporated variables that were under the influence of human activities and used them as the major factors for partitioning sections of the river according to risk values. It also explored the spatial and temporal distribution laws of estuarine ecological risk. The results showed that, on the whole, the ecological risk of the Daliao River estuary area was relatively high. At a temporal level, runoff was the main factor resulting in differences in ecological risk, while at the spatial level, the ecological risk index was affected by pollutants carried by runoff from upstream, as well as downstream pollution emissions and dilution by seawater at the mouth of the sea. The characteristics of this model make it possible to simulate the spatial and temporal risk distribution in different regions and under different rainfall regimes. This model can thus be applied in other estuarine areas and provides some technical support for analysis and control of ecological destruction in estuary areas.

Yu G; Chen J; Zhang X; Li Z

2013-08-01

 
 
 
 
41

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

UK PubMed Central (United Kingdom)

Highly mutagenic compounds such as some PAHs have been identified in surface waters and sediments of the Seine river estuary. Suspended particulate matter (SPM) represents a dynamic medium that may contribute to the exposure of aquatic organisms to toxic compounds in the water column of the estuary. In order to investigate major sources of mutagenic contaminants along the estuary, water samples were taken at 25 m downstream of the outlet of an industrial wastewater-treatment plant (WWTP). SPM samples were analyzed for their genotoxicity with two short-term tests, the Salmonella typhimurium mutagenicity assay (TA98+S9 mix) and the comet assay in the human HepG2 cell line. Sampling sites receiving effluents from a chemical dye industry and WWTP showed the highest mutagenic potencies, followed by petrochemical industries, petroleum refinery and pulp and paper mills. These data indicate that frame-shift mutagens are present in the Seine river estuary. Furthermore, the comet assay revealed the presence of compounds that were genotoxic for human hepatocytes (HepG2 cells). We also observed a high level of mutagenic potency in the sediment of the lower estuary (3 × 10? revertants/g). The source of mutagenic and genotoxic compounds seems to be associated with various types of effluents discharged in the Seine river estuary. Both test systems resulted in the same assessment of the genotoxicity of particulate matter, except for three of the 14 samples, underlying the complementarity of bioassays.

Vincent-Hubert F; Heas-Moisan K; Munschy C; Tronczynski J

2012-01-01

42

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.

1985-01-01

43

PREDICTION OF TSUNAMI PROPAGATION IN THE PEARL RIVER ESTUARY  

Directory of Open Access Journals (Sweden)

Full Text Available Tsunamis entering into shallow water regions may become highly nonlinear and this may be due to the irregularity of sea bottom roughness relative to the water depth and the complex coastline geometry. The elliptic mild-slope equation is commonly used to predict the nonlinear wave propagation in shallow water regions but it requires huge amount of computer resources which may not be practical for tsunami propagation predictions. An efficient finite element approach has been adopted in the present project to resolve the nonlinear problem of wave transformation in near shore zones as well as to better conform the model grids to any complex coastline configurations. The efficient approach is based on the wave action conservation equation that takes into account of wave refraction-diffraction and energy dissipation due to bottom roughness. An operator splitting scheme is employed to solve the wave action conservation equation. Firstly, to increase numerical stability, the Eulerian-Lagrangian method is applied to solve the advection terms in the equation. The horizontal terms are then discretized by an implicit finite element method and, finally, the vertical terms are approximated by an implicit finite difference method. A nominal-time iteration method is used to efficiently solve the non-linear irrotational wave number equation for the wave direction. Over 6000 nine-node elements have been used to mesh the Pearl River estuary region. The boundary conditions are based on the results obtained from a simulation applied for a larger computation domain encompassing the entire South China Sea. The computed result provides a general picture of tsunami propagation in the desired region. Model validation and result verification, however, are necessary for any future prediction exercises.

Sun J. S.; Wai, O.W.H.; Chau, K.T.; Wong, R.H.C

2009-01-01

44

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.

2008-01-01

45

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

Science.gov (United States)

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

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

2000-05-01

46

BEHAVIOUR OF WATER QUALITY PARAMETERS DURING EBB TIDE IN DUNGUN RIVER ESTUARY, TERENGGANU.  

Directory of Open Access Journals (Sweden)

Full Text Available A study has been carried out to determine the behaviour of selected water quality (WQ) parameters in Dungun river estuary. Samplings were carried out twice during October 2001 under similar tidal conditions (ebb tide) whereby samples were collected as a function of salinity i.e. along the salinity gradients from 0 ppt (freshwater end-member) to 31 ppt (coastal water end-member). WQ parameters monitored were the general physical parameters (viz. temperature, pH, dissolved oxygen, suspended solids and redox potential), dissolved metals (copper, cadmium and lead), dissolved nutrients (nitrogen- and phosphate-based nutrients) and chlorophyll-a. The physical water quality parameters were measured in situ using a multi-parameter data logger whilst nutrients and chlorophyll-a analyses were carried out based on the colorimetric method. Dissolved metals were analysed using GF-AAS technique following the pre-concentration step using APDC-MIBK method. Results in general indicated that most of the parameters measured appear to behave non-conservatively with salinity. In the case of nutrients, with the exception of nitrate which exhibited removal behaviour, all other nitrogen- and phosphorus-based nutrients, exhibited addition behaviour in the estuary. Cadmium and lead were also found to behave in a non-conservative manner in the estuary i.e. positive deviation was observed for cadmium whilst lead exhibited a negative deviation from the theoretical dilution line. These observations suggest that the estuary act as a source for cadmium but a sink for lead. Copper on the hand exhibited a linear relationship with salinity indicating a conservative distribution along the estuary. Results obtained in the present study clearly show the different behaviour of a given water quality parameter in the estuary and also illustrate the important role played by Dungun River estuary in modifying the nutrient and metal concentrations during the transportation from the river to the coastal waters.

Norhayati Mohd Tahir1*, Suhaimi Suratman1, Noor Azhar Mohd Shazili2, Marinah Mohd Ariffin1, Mohd Shafaril Mohd Amin1, Nik Faris Malik Nik Iskandar Ariff1, Wan Nor Hasmizan Wan Sulaiman1

2008-01-01

47

Dissolved inorganic nutrients and chlorophyll A in an estuary receiving sewage treatment plant effluents: Cachoeira River estuary (NE Brazil).  

Science.gov (United States)

Sampling was conducted monthly during a transition period between the dry and rainy seasons in order to evaluate the effectiveness of a municipal sewage treatment plant (STP) in eutrophication control. STP effluent and fluvial input data were also estimated. In the dry period, high concentrations of nutrients, chlorophyll a (up to 360 ?g?L(-1)), and anoxia in bottom waters were observed in the upper portion of the estuary. Nitrate was scarce during the dry months, although high concentrations were observed at the river sources and the upper estuary. The N:P and Si:P molar ratios were usually below 16:1, and the Si:N ratio was higher than 1:1. The fluvial inputs were a greater source of nutrients to the estuary than the STP, but nutrient loading by these effluents were also important in contributing to the eutrophication of the upper estuarine zone, especially in the dry season when symptoms were more intense. PMID:23179722

Silva, Maria Aparecida Macêdo; Eça, Gilmara Fernandes; Santos, Danielle Felix; Guimarães, Alonso Góes; Lima, Michelle Coêlho; de Souza, Marcelo Friederichs Landim

2012-11-24

48

Heavy metal content evaluation of species of Spartina Schreb. Genera (Graminae) from the Tinto river Estuary (Huelva, Spain)  

Energy Technology Data Exchange (ETDEWEB)

Estuaries, as skinks of residues and sediments transported by river waters, are ecosystems especially sensitive to pollution. From this point of view, Tinto River estuary, located in Huelva province (Spain), is particularly interesting. Tinto River presents an average pH of 2.3 and elevated concentrations of metals as Fe, Cu, Zn, As and Pb in most of its length (nearly 100 km). (Author)

Rufo, L.; Ortunez, E.; Rodriguez, N.; Amils, R.; Fuente, V.

2009-07-01

49

Heavy metal content evaluation of species of Spartina Schreb. Genera (Graminae) from the Tinto river Estuary (Huelva, Spain)  

International Nuclear Information System (INIS)

Estuaries, as skinks of residues and sediments transported by river waters, are ecosystems especially sensitive to pollution. From this point of view, Tinto River estuary, located in Huelva province (Spain), is particularly interesting. Tinto River presents an average pH of 2.3 and elevated concentrations of metals as Fe, Cu, Zn, As and Pb in most of its length (nearly 100 km). (Author)

2008-09-00

50

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

51

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...

52

Distribution of submerged aquatic vegetation in the St. Louis River estuary: Maps and models  

Science.gov (United States)

In late summer of 2011 and 2012 we used echo-sounding gear to map the distribution of submerged aquatic vegetation (SAV) in the St. Louis River Estuary (SLRE). From these data we produced maps of SAV distribution and we created logistic models to predict the probability of occurr...

53

Pollution history of the Savannah River estuary. Final report, September 1, 1976--December 31, 1977  

International Nuclear Information System (INIS)

Records of natural and pollutant fluxes to the Savannah River Estuary are found in some river and marsh deposits into which time frames can be introduced by Pb-210 or plutonium geochronologies. Plutonium releases from the Savannah River Plant are evident in only one deposit and in marsh grass which received the transuranic element from atmospheric transport. The pollution records can be disturbed by bioturbative activities of organisms, by the input of marine solid phases to the estuarine deposits, and by river scour and fill.

1978-01-01

54

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

Energy Technology Data Exchange (ETDEWEB)

To determine the origin of sediments in the Savannah River estuary, we have measured {sup 137}Cs 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 {sup 137}Cs 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 {sup 137}Cs 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).

Mulholland, P.J.; Olsen, C.R. (Oak Ridge National Lab., TN (United States))

1992-01-01

55

A modeling study on saltwater intrusion to western four watercourses in the Pearl River estuary  

Science.gov (United States)

Saltwater intrusion has been serious in the Pearl River estuary in recent years. For better understanding and analysis of the saltwater movement to the estuary, the three-dimensional Finite-Volume Coastal Ocean Model (FVCOM) is made to simulate the salinity intrusion to the four western watercourses in the Pearl River estuary under three semilunar conditions. With the measured and simulated Root Mean Square Error (RMSE) and the mean absolute percentage error of water level and salinity at multiple sites, the results show that the numerical water levels, salinity and flow velocities are in agreement with the measured data. It is acceptable and feasible to apply the FVCOM to simulate the salt water intrusion in the western four watercourses of the Pearl River. With the numerical data, the time and spatial movement patterns of saltwater intrusion along the Modao watercourse are analyzed. The salinity contour reaches its peak generally during 3˜5 days before the spring tide. The salinity stratification is more obvious in the period of ebb tide than that in the rising tide whether in the spring or neap tides. Salt fluxes reflect changes of salt into the estuary, and the change rules are close to the rules of salinity intrusion.

Cheng, Xiang-ju; Zhan, Wei; Guo, Zhen-ren; Yuan, Li-rong

2012-12-01

56

Estimating sediment budgets at the interface between rivers and estuaries with application to the Sacramento-San Joaquin River Delta  

Science.gov (United States)

[1] Where rivers encounter estuaries, a transition zone develops where riverine and tidal processes both affect sediment transport processes. One such transition zone is the Sacramento-San Joaquin River Delta, a large, complex system where several rivers meet to form an estuary (San Francisco Bay). Herein we present the results of a detailed sediment budget for this river/estuary transitional system. The primary regional goal of the study was to measure sediment transport rates and pathways in the delta in support of ecosystem restoration efforts. In addition to achieving this regional goal, the study has produced general methods to collect, edit, and analyze (including error analysis) sediment transport data at the interface of rivers and estuaries. Estimating sediment budgets for these systems is difficult because of the mixed nature of riverine versus tidal transport processes, the different timescales of transport in fluvial and tidal environments, and the sheer complexity and size of systems such as the Sacramento-San Joaquin River Delta. Sediment budgets also require error estimates in order to assess whether differences in inflows and outflows, which could be small compared to overall fluxes, are indeed distinguishable from zero. Over the 4 year period of this study, water years 1999-2002, 6.6 ?? 0.9 Mt of sediment entered the delta and 2.2 ?? 0.7 Mt exited, resulting in 4.4 ?? 1.1 Mt (67 ?? 17%) of deposition. The estimated deposition rate corresponding to this mass of sediment compares favorably with measured inorganic sediment accumulation on vegetated wetlands in the delta.

Wright, S. A.; Schoellhamer, D. H.

2005-01-01

57

Plutonium speciation and isotope ratios in Yenisey and Ob river and Yenisey estuary  

International Nuclear Information System (INIS)

Plutonium isotope ratios are known to vary with reactor type, nuclear fuel-burn up time, neutron flux, and energy, and for fallout from nuclear detonations, weapon type and yield. Weapons-grade plutonium is characterized by a low content of the 240Pu isotope, with 240Pu/239Pu isotope ratio less than 0.05. In contrast, both global weapons fallout and spent nuclear fuel from civil reactors have higher 240Pu/239Pu isotope ratios (civil nuclear power reactors have 240Pu/239Pu atom ratios of between about 0.2-1). Thus, different sources often exhibit characteristic plutonium isotope ratios and these ratios can be used to identify the origin of contamination, calculate inventories, or follow the migration of contaminated sediments and waters. Together with activity measurements and isotope ratios, knowledge of plutonium speciation in the Ob and Yenisey rivers and processes controlling its behaviour in estuarine systems is a prerequisite for predicting the transfer and subsequent environmental impact to Arctic Seas. With this in mind, the study had two objectives: first to determine whether discharges from nuclear installations in the river catchment areas are having any influence on Pu levels in the estuaries; and, second, to investigate the transfer and mobility of plutonium in the Yenisey river and estuary. Plutonium 240/239 ratios were determined using accelerator mass spectrometry (AMS). The data indicated a clear influence from a low 240Pu:239Pu source in surface sediments collected from the Yenisey Estuary, whereas plutonium in the Ob Estuary sediments are dominated by global fallout. The results also show an increase in plutonium concentration and a decrease in isotope ratio going upstream from the estuary. Sequential extractions of sediments indicate that up 70% of the Pu in the Yenisey river is easily mobilized with weak oxidizing agents, which indicates that the Pu is organically bound, while the Pu is more strongly irreversible bound further out in the estuaries. This means that the organic bound Pu i the river is mobilized in the estuary. (author)

2004-01-01

58

Plutonium speciation and isotope ratios in Yenisey and Ob river and Yenisey estuary  

Energy Technology Data Exchange (ETDEWEB)

Plutonium isotope ratios are known to vary with reactor type, nuclear fuel-burn up time, neutron flux, and energy, and for fallout from nuclear detonations, weapon type and yield. Weapons-grade plutonium is characterized by a low content of the {sup 240}Pu isotope, with {sup 240}Pu/{sup 239}Pu isotope ratio less than 0.05. In contrast, both global weapons fallout and spent nuclear fuel from civil reactors have higher {sup 240}Pu/{sup 239}Pu isotope ratios (civil nuclear power reactors have {sup 240}Pu/{sup 239}Pu atom ratios of between about 0.2-1). Thus, different sources often exhibit characteristic plutonium isotope ratios and these ratios can be used to identify the origin of contamination, calculate inventories, or follow the migration of contaminated sediments and waters. Together with activity measurements and isotope ratios, knowledge of plutonium speciation in the Ob and Yenisey rivers and processes controlling its behaviour in estuarine systems is a prerequisite for predicting the transfer and subsequent environmental impact to Arctic Seas. With this in mind, the study had two objectives: first to determine whether discharges from nuclear installations in the river catchment areas are having any influence on Pu levels in the estuaries; and, second, to investigate the transfer and mobility of plutonium in the Yenisey river and estuary. Plutonium 240/239 ratios were determined using accelerator mass spectrometry (AMS). The data indicated a clear influence from a low {sup 240}Pu:{sup 239}Pu source in surface sediments collected from the Yenisey Estuary, whereas plutonium in the Ob Estuary sediments are dominated by global fallout. The results also show an increase in plutonium concentration and a decrease in isotope ratio going upstream from the estuary. Sequential extractions of sediments indicate that up 70% of the Pu in the Yenisey river is easily mobilized with weak oxidizing agents, which indicates that the Pu is organically bound, while the Pu is more strongly irreversible bound further out in the estuaries. This means that the organic bound Pu i the river is mobilized in the estuary. (author)

Skipperud, L.; Oughton, DH.; Fifield, K.; Lind, O.C.; Salbu, B.; Brown, J. [Norway Univ. Agricultural, Dept. of Soil and Water Science, Aas (Norway)

2004-07-01

59

Distribution of 137Cs in the Lena River estuary-Laptev Sea system.  

UK PubMed Central (United Kingdom)

Surface sediment samples in the Laptev Sea have average 137Cs content of 7.1 Bq kg(-1), a value intermediate between that of the western Kara Sea (23 Bq kg(-1) and the East Siberian Sea (4.2 Bq kg-'). Both surface sediment content and sediment inventory of 137Cs in the Laptev Sea sediments show significant variability, and the influence of a variety of environmental factors.137Cs concentrations in the Laptev Sea surface sediments range from 0.8 to 16 Bq kg(-1). There is a marked increase in 137Cs content of surface sediment samples collected near the Lena River delta, and a local enrichment in the 137Cs inventories at these sites is also evident. Fine-grained mixed-layer illite/ smectite rich sediments in the estuary provide effective adsorption sites to fix 137Cs, in spite of desorption processes associated with low salinities in estuarine mixing. The Lena River-Laptev Sea mixing zone is a major site of sea-ice production. River and shelf sediments are incorporated into sea-ice formed in this region (Holmes and Creager, 1974). The irregular 137Cs activity profiles of the Lena River estuary cores indicate disturbance or removal of 137Cs-laden sediments via sea-ice related processes. Lena River and Estuary sediments may have served as a secondary source (i.e. other than direct fallout) of 137Cs in sea-ice. North-east of the Lena River estuary, sediment contains a thin layer of 137Cs-bearing material over an erosion surface. The 137Cs-laden surface layer may be the result of transient deposition of estuarine sediments being delivered by sea-ice or spring floods.

Johnson-Pyrtle A; Scott MR

2001-10-01

60

Contrasting metal concentrations in selectively extracted suspended versus deposited sediments of the Fraser River Estuary  

Energy Technology Data Exchange (ETDEWEB)

In order to assess the relative importance of Suspended Particulate Material (SPM) and deposited sediment as potential sources of trace metals to estuarine organisms, both SPM and deposited sediment were collected from three sites in the midestuarine region of the Fraser River Estuary over the course of one year. Selective chemical extractions were employed to assess differences in metal geochemical association between SPM and deposited sediment. Results indicate that SPM is an important metal-bearing vector in the estuary. SPM has significantly higher organic content (1--8 times) and metal levels (2--10 times) than deposited sediment and is also made up of smaller material (and therefore has a larger surface area to volume). The geochemical phase with which the metal associates also differs among the two sources and is metal specific. Such differences can have important implications in regards to metal exposure and uptake in suspension and deposit feeding organisms of the estuary.

Stecko, J.R.P.; BendellYoung, L.I. [Simon Fraser Univ., Burnaby, British Columbia (Canada). Dept. of Biological Sciences

1995-12-31

 
 
 
 
61

Historic Habitat Opportunities and Food-Web Linkages of Juvenile Salmon in the Columbia River Estuary, Annual Report of Research.  

Energy Technology Data Exchange (ETDEWEB)

In 2002 with support from the U.S. Army Corps of Engineers (USACE), an interagency research team began investigating salmon life histories and habitat use in the lower Columbia River estuary to fill significant data gaps about the estuary's potential role in salmon decline and recovery . The Bonneville Power Administration (BPA) provided additional funding in 2004 to reconstruct historical changes in estuarine habitat opportunities and food web linkages of Columbia River salmon (Onchorhynchus spp.). Together these studies constitute the estuary's first comprehensive investigation of shallow-water habitats, including selected emergent, forested, and scrub-shrub wetlands. Among other findings, this research documented the importance of wetlands as nursery areas for juvenile salmon; quantified historical changes in the amounts and distributions of diverse habitat types in the lower estuary; documented estuarine residence times, ranging from weeks to months for many juvenile Chinook salmon (O. tshawytscha); and provided new evidence that contemporary salmonid food webs are supported disproportionately by wetland-derived prey resources. The results of these lower-estuary investigations also raised many new questions about habitat functions, historical habitat distributions, and salmon life histories in other areas of the Columbia River estuary that have not been adequately investigated. For example, quantitative estimates of historical habitat changes are available only for the lower 75 km of the estuary, although tidal influence extends 217 km upriver to Bonneville Dam. Because the otolith techniques used to reconstruct salmon life histories rely on detection of a chemical signature (strontium) for salt water, the estuarine residency information we have collected to date applies only to the lower 30 or 35 km of the estuary, where fish first encounter ocean water. We lack information about salmon habitat use, life histories, and growth within the long tidal-fresh reaches of the main-stem river and many tidally-influenced estuary tributaries. Finally, our surveys to date characterize wetland habitats within island complexes distributed in the main channel of the lower estuary. Yet some of the most significant wetland losses have occurred along the estuary's periphery, including shoreline areas and tributary junctions. These habitats may or may not function similarly as the island complexes that we have surveyed to date. In 2007 we initiated a second phase of the BPA estuary study (Phase II) to address specific uncertainties about salmon in tidal-fresh and tributary habitats of the Columbia River estuary. This report summarizes 2007 and 2008 Phase II results and addresses three principal research questions: (1) What was the historic distribution of estuarine and floodplain habitats from Astoria to Bonneville Dam? (2) Do individual patterns of estuarine residency and growth of juvenile Chinook salmon vary among wetland habitat types along the estuarine tidal gradient? (3) Are salmon rearing opportunities and life histories in the restoring wetland landscape of lower Grays River similar to those documented for island complexes of the main-stem estuary? Phase II extended our analysis of historical habitat distribution in the estuary above Rkm 75 to near Bonneville Dam. For this analysis we digitized the original nineteenth-century topographic (T-sheets) and hydrographic (H-sheets) survey maps for the entire estuary. Although all T-sheets (Rkm 0 to Rkm 206) were converted to GIS in 2005 with support for the USACE estuary project, final reconstruction of historical habitats throughout the estuary requires completion of the remaining H-sheet GIS maps above Rkm 75 and their integration with the T-sheets. This report summarizes progress to date on compiling the upper estuary H-sheets above Rkm 75. For the USACE estuary project, we analyzed otoliths from Chinook salmon collected near the estuary mouth in 2003-05 to estimate variability in estuary residence times among juvenile out migrants. In Phase II we expanded these a

Bottom, Daniel L.; Simenstad, Charles A.; Campbell, Lance [Northwest Fisheries Science Center

2009-05-15

62

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

63

Distribution characteristics of transparent exopolymer particles in the Pearl River estuary, China  

Science.gov (United States)

Distribution of Transparent Exopolymer Particles (TEP) in the Pearl River estuary, China, was investigated during two cruises in August 2009 and January 2010. TEPcolor concentrations were 521.5-1727.4 ?g Xeq.L-1 (?g Gum Xanthan equivalent liter-1) in August 2009 and 88.7-1586.9 ?g Xeq.L-1 in January 2010, respectively. The size of TEP generally increased in the seaward along the longitudinal section with the dominant size of 2-40 ?m during the cruises. Experimental work suggested that both concentration and size of TEP increased with Ca2+ concentration (from 0.8 mmol L-1 to 10 mmol L-1). In the field study, Ca2+ concentration had a positive correlation with TEPcolor concentration in the surface layer with salinity <16. Decrease of TEP concentration seaward from intermediary salinity was partly due to dilution of seawater as well as enhanced aggregation and sedimentation of TEP via increasing divalent cation concentration. TEP concentration and turbidity maximum coexisted at the tip of salt wedge in the bottom layer during the wet season, and positive correlation between TEP and turbidity was observed in the winter. Relationships between TEP and turbidity suggested the important contribution of TEP aggregation to flocculation and sedimentation of particles in estuaries. Different pattern of TEP during two cruises can be attributed to physical process (i.e., mixing type) in estuaries. These findings indicated that formation and distribution of TEP were largely influenced by interaction between physical and biogeochemical processes in the Pearl River estuary. A conceptual model for TEP formation and distribution in the Pearl River estuary was developed.

Sun, Cui-Ci; Wang, You-Shao; Li, Qian P.; Yue, Wei-Zhong; Wang, Yu-Tu; Sun, Fu-Lin; Peng, Ya-Lan

2012-12-01

64

Depth- and current-induced effects on wave propagation into the Altamaha River Estuary, Georgia  

Science.gov (United States)

A study of sea surface wave propagation and its energy deformation was carried out using field observations and numerical experiments over a region spanning the midshelf of the South Atlantic Bight (SAB) to the Altamaha River Estuary, GA. Wave heights on the shelf region correlate with the wind observations and directional observations show that most of the wave energy is incident from the easterly direction. Comparing midshelf and inner shelf wave heights during a time when there was no wind and hence no wave development led to an estimation of wave energy dissipation due to bottom friction with corresponding wave dissipation factor of 0.07 for the gently sloping continental shelf of the SAB. After interacting with the shoaling region of the Altamaha River, the wave energy within the estuary becomes periodic in time showing wave energy during flood to high water phase of the tide and very little wave energy during ebb to low water. This periodic modulation inside the estuary is a direct result of enhanced depth and current-induced wave breaking that occurs at the ebb shoaling region surrounding the Altamaha River mouth at longitude 81.23°W. Modelling results with STWAVE showed that depth-induced wave breaking is more important during the low water phase of the tide than current-induced wave breaking during the ebb phase of the tide. During the flood to high water phase of the tide, wave energy propagates into the estuary. Measurements of the significant wave height within the estuary showed a maximum wave height difference of 0.4 m between the slack high water (SHW) and slack low water (SLW). In this shallow environment these wave current interactions lead to an apparent bottom roughness that is increased from typical hydraulic roughness values, leading to an enhanced bottom friction coefficient.

Kang, K.; Di Iorio, D.

2006-02-01

65

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

UK PubMed Central (United Kingdom)

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.

Roegner GC; Needoba JA; Baptista AM

2011-01-01

66

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

Science.gov (United States)

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

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

2011-12-01

67

Evaluation of Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2010  

Energy Technology Data Exchange (ETDEWEB)

This is the seventh and final annual report of a project (2004–2010) addressing evaluation of the cumulative effects of habitat restoration actions in the 235-km-long lower Columbia River and estuary. The project, called the Cumulative Effects (CE) study, was conducted for the U.S. Army Corps of Engineers Portland District by a collaboration of research agencies led by the Pacific Northwest National Laboratory. We achieved the primary goal of the CE study to develop a methodology to evaluate the cumulative effects of habitat actions in the Columbia Estuary Ecosystem Restoration Program. We delivered 1) standard monitoring protocols and methods to prioritize monitoring activities; 2) the theoretical and empirical basis for a CE methodology using levels-of-evidence; 3) evaluations of cumulative effects using ecological relationships, geo-referenced data, hydrodynamic modeling, and meta-analyses; and 4) an adaptive management process to coordinate and coalesce restoration efforts in the LCRE. A solid foundation has been laid for future comprehensive evaluations of progress made by the Columbia Estuary Ecosystem Restoration Program to understand, conserve, and restore ecosystems in the lower Columbia River and estuary.

Johnson, Gary E.; Diefenderfer, Heida L.; Thom, Ronald M.; Roegner, G. Curtis; Ebberts, Blaine D.; Skalski, John R.; Borde, Amy B.; Dawley, Earl; Coleman, Andre M.; Woodruff, Dana L.; Breithaupt, Stephen A.; Cameron, April; Corbett, C.; Donley, Erin E.; Jay, D. A.; Ke, Yinghai; Leffler, K.; McNeil, C.; Studebaker, Cindy; Tagestad, Jerry D.

2012-05-01

68

???????????????? Research on Changes of Peak Water Level in the Pearl River Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available ???????????????????????????????????????????????????????????????????????1) 20??50???????????????????????????2) ???????????????20??90???????????????????????????????????????1981??1983??3) ??????????????????????????????????? Higher peak water level of the Pearl River Estuary gives a great threat to life and construction losses in these developed areas. The peak water level series of the Denglongshan and Hengmen stations are analyzed by several methods. The results show that: 1) the peak water level has significant upward trend at representative station in the Pearl River Estuary since 1950s; 2) the increasing of the peak water level belongs to mutations phenomenon since early 1990s, the Denglongshan and Hengmen stations began to mutate re-spectively in 1981 and 1983; 3) the influence of sea level rise on change trend of the peak water level is greater than that of the maximum flow.  

??; ???; ???; ???; ???; ???

2012-01-01

69

[Leaf consumption by herbivores in mangroves of the Dagua river estuary, Pacific coast of Colombia].  

UK PubMed Central (United Kingdom)

Herbivore leaf consumption of various mangrove species in relation to environmental factors and leaf hardness were studied in the Dagua river estuary, Colombia. Leaf consumption and damage were assessed by measuring the percentage of area attacked by herbivores, distinguishing between consumption and damage. The species that suffered the highest consumption, such as Avicennia germinans (Avicenniaceae) and Laguncularia racemosa (Combretaceae), had softer leaves and less herbivore species when compared with Rhizophora spp. (Rhizophoraceae) and Pelliciera rhizophorae (Theaceae). The abundance and diversity of leaf grazing and its variability among mangrove species in the Dagua River estuary, show the importance of the trophic dynamics of live vegetable matter, in spite of their relatively low contribution to removing organic matter.

Romero IC; Cantera K JR; Peña S EJ

2006-12-01

70

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

International Nuclear Information System (INIS)

[en] 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

1989-01-01

71

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

Energy Technology Data Exchange (ETDEWEB)

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.

Olsen, C.R.; Thein, M.; Larsen, I.L.; Byrd, J.T.; Windom, H.L.

1989-01-01

72

[Leaf consumption by herbivores in mangroves of the Dagua river estuary, Pacific coast of Colombia].  

Science.gov (United States)

Herbivore leaf consumption of various mangrove species in relation to environmental factors and leaf hardness were studied in the Dagua river estuary, Colombia. Leaf consumption and damage were assessed by measuring the percentage of area attacked by herbivores, distinguishing between consumption and damage. The species that suffered the highest consumption, such as Avicennia germinans (Avicenniaceae) and Laguncularia racemosa (Combretaceae), had softer leaves and less herbivore species when compared with Rhizophora spp. (Rhizophoraceae) and Pelliciera rhizophorae (Theaceae). The abundance and diversity of leaf grazing and its variability among mangrove species in the Dagua River estuary, show the importance of the trophic dynamics of live vegetable matter, in spite of their relatively low contribution to removing organic matter. PMID:18457159

Romero, Isabel C; Cantera K, Jaime R; Peña S, Enrique J

2006-12-01

73

Benthic foraminiferal assemblages and trace metals reveal the environment outside the Pearl River Estuary.  

UK PubMed Central (United Kingdom)

We investigated the distribution patterns of the benthic foraminiferal assemblages outside the Pearl River Estuary in relation to trace metals, organic carbon and sedimentary particle fractions. The study area is unpolluted to moderately polluted by Cr, Cu, Pb and Zn and is completely polluted by Ni. The highest levels are found in the western coastal zone. Spatial distributions of the measured elements are strongly related to the behavior of the sedimentary clay fraction. The analyses of species abundance and community diversity as well as subsequent canonical correspondence analysis were used to reveal the relationship between foraminifera data and environmental parameters. Four sampling site groups established by factor analysis were distributed from the coastal area to the inner shelf. Their distribution patterns have a strong correlation with Cu, Pb and Ba. This research shows that benthic foraminifera can be used as bioindicators of trace metal pollutants outside the Pearl River Estuary.

Li T; Xiang R; Li T

2013-08-01

74

The geochemistry of rare earth elements in the Amazon River estuary  

Energy Technology Data Exchange (ETDEWEB)

The estuarine geochemistry of rare earth elements (REEs) was studied using samples collected in the Amazon River estuary from the AmasSeds (Amazon Shelf SEDiment Study) cruise of August 1989. Extensive removal of dissolved (0.22 [mu]m filtered) trivalent REEs from river water occurs in the low (0--6) salinity region. Removal by the salt-induced coagulation of river colloids leads to fractionation among the REE(III) series; the order of removal is light REEs > middle REEs > heavy REEs. There also is the enhanced removal of Ce (relative to trivalent La and Nd) in the low salinity (0--6) zone and in the zone of high biological activity. This is the first field observation of strong Ce removal associated with coagulation of river colloids and biological productivity. The argument is made that the decrease in the Ce anomaly across a biological front is caused by biologically mediated oxidation of Ce(III) to Ce(IV). Coagulation of river colloids and biologically mediated oxidation of Ce(III) lead to fractionation of REE(III) and redox modification of Ce. These processes result in the REE composition becoming fractionated relative to the Amazon River water and crust and more evolved toward the REE composition of the oceans. This study implies that reactions in estuaries play significant, yet poorly understood roles in controlling the REE composition and Ce anomaly of the oceans. 46 refs., 9 figs., 2 tabs.

Shokovitz, E.R. (Woods Hole Oceanographic Institution, MA (United States))

1993-05-01

75

Simulation of chlorinated water discharges from power plants on estuaries and rivers  

International Nuclear Information System (INIS)

The fast-transient (tidal-transient) one-dimensional discrete-element chemical transport model and its associated computer code CHMONE were applied to study the effects of chlorinated water discharges from power plants on tidal estuaries and controlled rivers. The mathematical model has the capability to predict simultaneously the hydrodynamic, thermal, and chemical composition of water as one-dimensional time-dependent distributions

1977-12-02

76

Stratified communities of active archaea in shallow sediments of the Pearl River Estuary, Southern China.  

UK PubMed Central (United Kingdom)

Marine subsurface sediments represent a novel archaeal biosphere with unknown physiology. To get to know the composition and ecological roles of the archaeal communities within the sediments of the Pearl River Estuary, Southern China, the diversity and vertical distribution of active archaea in a sediment core were characterized by 16S rRNA phylogenetic analysis of clone libraries derived from RNA. In this study, the archaeal diversity above, within, and beneath the sulfate-methane transition zone (SMTZ) in the Pearl River Estuary sediment core was described. The majority of the clones obtained from the metabolically active fraction of the archaeal community were most closely related to miscellaneous crenarchaeotal group and terrestrial miscellaneous euryarchaeotal group. Notably, although the Pearl River Estuary sediment belong to high methane and high organic carbon environment, sequences affiliated with methanotrophic and methanogenic archaea were detected as minor group in 16S rRNA clone libraries. No obvious evidence suggested that these unknown archaeal phylotypes related directly to anaerobic oxidation of methane in SMTZ. This is the first phylogenetic analysis of the metabolically active fraction of the archaeal community in the coastal sediment environments.

Chen J; Wang F; Jiang L; Yin X; Xiao X

2013-07-01

77

Trace Metal Concentration in Water of the Karnaphuli River Estuary of the Bay of Bengal  

Directory of Open Access Journals (Sweden)

Full Text Available A study was conducted for the determination of some trace metal (Cr, Mn, Zn, Ni, Cu, Pb, Cd and Fe) concentrations in water of the Karnaphuli River estuary analyzing seasonally viz., pre-monsoon, monsoon and post-monsoon by employing air acetylene flame in combination with single element hollow cathode lamps and atomic absorption spectrophotometer. Sub-surface water samples were collected from 4 stations namely Mouth, Naval base, Sadarghat and Kalurghat regions of the Karnaphuli River estuary. The concentrations (?;g g -1 dry weight) of Cr, Mn, Zn, Ni, Cu, Pb, Cd and Fe were found to range from 0.421 to 0.925, 0.498 to 1.372, 0.472 to 1.186, 0.356 to 0.865, 0.372 to 0.973, 0.405 to 1.195, 0.090 to 0.217 and 20.025 to 42.203 respectively. The concentrations of Pb, Cu, Fe, Ni and Cr were observed higher and concentrations of Mn and Cd were found lower than that of the recommended values. It is assumed from the analytical findings that the estuary has been polluted from domestic sewage, land washout, river run-off and shipping activities.

Biplob Das; Yusuf Sharif Ahmed Khan; Mohammad Abdul Karim Sarker

2002-01-01

78

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.

1982-01-01

79

Foraging patterns of Caspian terns and double-crested cormorants in the Columbia River estuary  

Science.gov (United States)

We examined spatial and temporal foraging patterns of Caspian terns and double-crested cormorants nesting in the Columbia River estuary, to potentially identify circumstances where juvenile salmonids listed under the U.S. Endangered Species Act might be more vulnerable to predation by these avian piscivores. Data were collected during the 1998 and 1999 breeding seasons, using point count surveys of foraging birds at 40 sites along the river's banks, and using aerial strip transect counts throughout the estuary for terns. In 1998, terns selected tidal flats and sites with roosting beaches nearby for foraging, making greater use of the marine/mixing zone of the estuary later in the season, particularly areas near the ocean jetties. In 1999, cormorants selected foraging sites in freshwater along the main channel with pile dikes present, particularly early in the season. Foraging trends in the other year for each species were generally similar to the above but usually not significant. During aerial surveys we observed 50% of foraging and commuting terns within 8 km of the Rice Island colony, and ??? 5% of activity occurred ??? 27 km from this colony in both years. Disproportionately greater cormorant foraging activity at pile dikes may indicate greater vulnerability of salmonids to predation at those features. Colony relocations to sites at sufficient distance from areas of relatively high salmonid abundance may be a straightforward means of reducing impacts of avian predation on salmonids than habitat alterations within the Columbia River estuary, at least for terns. ?? 2007 by the Northwest Scientific Association. All rights reserved.

Lyons, D. E.; Roby, D. D.; Collis, K.

2007-01-01

80

Some chemical characteristics of the River Pra Estuary in the Western region of Ghana  

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Full Text Available This paper discusses the nutrients budget and transfers of mineral nutrients from land to the sea that influence significantly the biogeochemical process operating in the coastal ecosystem. Water samples were collected fortnightly from six sites in the estuary and analysed using standard methods of analyses. It was observed that the estuary is alkaline in nature and the alkalinity increases, in the lower reach of the river as it flowed into the sea. The estuary could be classified as a well-mixed estuary due to the vertical homogenous distribution of salinity. The inorganic nitrogen in the water body exists predominately in the form of nitrate (NO3-), as compared to concentrations of ammonium (NH4+) and nitrite (NO2-). The ranges of NO3-, NH4+ and NO2- concentrations are (4.98-8.27), (0.11-0.46) and (0.005-10.95) x 10-3 mg/L. The concentrations of nitrate, nitrite, ammonium and phosphate were found to be within WHO specification. The calculated residual flow (VR) for both November and December are -2.7 x 107 m3 day-1 and -1.01 x 107 m3 day-1, respectively. The negative value of VR implies that water flows from the system. The corresponding residence and flush times are 324 and 109 seconds and 828 and 595.2 seconds for November and December, respectively.

J.K. Tufuor; D.K. Dodoo; A.K. Armah; G.A. Darpaah; D.K. Essumang

2007-01-01

 
 
 
 
81

Influence of multiple dam passage on survival of juvenile Chinook salmon in the Columbia River estuary and coastal ocean.  

UK PubMed Central (United Kingdom)

Multiple dam passage during seaward migration is thought to reduce the subsequent survival of Snake River Chinook salmon. This hypothesis developed because juvenile Chinook salmon from the Snake River, the Columbia River's largest tributary, migrate >700 km through eight hydropower dams and have lower adult return rates than downstream populations that migrate through only 3 or 4 dams. Using a large-scale telemetry array, we tested whether survival of hatchery-reared juvenile Snake River spring Chinook salmon is reduced in the estuary and coastal ocean relative to a downstream, hatchery-reared population from the Yakima River. During the initial 750-km, 1-mo-long migration through the estuary and coastal ocean, we found no evidence of differential survival; therefore, poorer adult returns of Snake River Chinook may develop far from the Columbia River. Thus, hydrosystem mitigation efforts may be ineffective if differential mortality rates develop in the North Pacific Ocean for reasons unrelated to dam passage.

Rechisky EL; Welch DW; Porter AD; Jacobs-Scott MC; Winchell PM

2013-04-01

82

Direct measurement of dissolved N? and denitrification along a subtropical river-estuary gradient, China.  

UK PubMed Central (United Kingdom)

The spatial pattern and seasonal variation of denitrification were investigated during 2010-2011 in the Jiulong River Estuary (JRE) in southeast China. Dissolved N? was directly measured by changes in the N?:Ar ratio. The results showed that excess dissolved N? ranged from -9.9 to 76.4 ?mol L?¹. Tidal mixing leads to a seaward decline of dissolved gaseous concentrations and water-air fluxes along the river-estuary gradient. Denitrification at freshwater sites varied between seasons, associated with changes in N input and water temperature. The denitrification process was controlled by the nitrate level at freshwater sites, and the excess dissolved N? observed at the tidal zone largely originated from upstream water transport. Compared to other estuaries, JRE has a relative low gaseous removal efficiency (E(d)=12% of [DIN]; annual N removal=24% of DIN load), a fact ascribed to strong tidal mixing, coarse-textured sediment with shallow depth before bedrock and high riverine DIN input.

Wu J; Chen N; Hong H; Lu T; Wang L; Chen Z

2013-01-01

83

Influence of Environmental Variables on the Distribution of Macrobenthos in the Han River Estuary, Korea  

Science.gov (United States)

We compared environmental effects on the macrobenthic community of the Han River Estuary in summer, when freshwater input from the Han River increased, and in spring, when freshwater input decreased. Field samples were taken from the upper region of the Shingok reservoir to the southern area of Ganghwado at 18 sampling sites after rainy (August 2006) and dry (March 2007) seasons. Macrobenthic fauna were collected using a Van Veen Grab (0.025 m2 and 0.1 m2) and environmental factors were measured simultaneously. Dominant species of macrobenthic fauna and the macrobenthic community were divided into two areas, the area of the Han River with no salinity ( 20 psu). The dominant species Byblis japonicus appeared at Junruri in the dry season. The distributions of two polychaetes, Hediste japonica and Nephtys caeca, were divided into the lower and upper areas of the Singok submerged weir. BIO-ENV (the matching of biotic to environmental patterns) analysis revealed that salinity was the most important factor affecting macrobenthic communities in the Han River Estuary, with other factors such as sediment grain size, bottom dissolved oxygen, and total organic carbon of sediment being secondary.

Yu, Ok Hwan; Lee, Hyung-Gon; Lee, Jae-Hac

2012-12-01

84

Wader migration and distribution in South West estuaries. V. 2. Appendices. [In Britain - potential effect of River Severn tidal barrage  

Energy Technology Data Exchange (ETDEWEB)

Two sets of data tables relating to a study of the potential effect on wading birds and wildfowl of a tidal barrage on the River Severn are presented. The first set records recoveries of ringed birds of six species which indicate the origins of waders and wildfowl using the Severn estuary. The second set records the distribution of fifteen species feeding on the mudflats of the Severn estuary. (U.K.).

1989-01-01

85

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

86

The Gambia River estuary: A reference point for estuarine fish assemblages studies in West Africa  

Science.gov (United States)

The Gambia River is one of the last aquatic ecosystems in West Africa that has not yet been affected by strong environmental changes and human disturbances. In contrast to the neighbouring Casamance and Sine Saloum estuaries, the Gambia estuary is free of major climatic perturbation and remains a “normal” estuary, with a salinity range from freshwater to 39. The present paper aims to study the spatial and seasonal variability of fish assemblages in this estuary in terms of bio-ecological categories and of their relation with some environmental variables. Four surveys were conducted, from June 2001 to April 2002, in order to cover the major hydroclimatic events, at 44 sampling sites along the lower, intermediate and upper zones of the Gambia estuary (up to 220 km). Fish assemblages were sampled using a purse seine net, fish were identified to species level and environmental variables such as water depth, transparency, salinity, temperature and percentage oxygen saturation were measured. The main spatial structure of the fish assemblages and its seasonal changes were first studied using the STATIS-CoA multitable method. The combination of fish assemblages and environmental variables was then analysed using the STATICO method, designed for the simultaneous analysis of paired ecological tables. A total of 67 species were observed, belonging to all bio-ecological categories characterizing West African estuaries. The marine component of the community was largely dominant throughout the estuary, while the freshwater component was permanently observed only in the upstream zone. The main spatial structure was a longitudinal gradient contrasting marine and freshwater affinity assemblages, with strong seasonal variations. The most complete gradient was observed in December, at the beginning of the dry and cool season, while in June, at the end of the dry and warm season, there was the least structured gradient. The role of salinity, always correlated with temperature, was emphasized, while turbidity appeared to be another important factor. Oxygen and depth did not play a major role at the estuary scale. The relative importance of the bio-ecological categories varied according to the season and the distance to sea. Stable fish assemblages were observed in the lower zone at the end of the dry season, in the upper zone during the flood and in the middle zone throughout the year. In some situations, a relative inadequacy between fish assemblages and their environment was noticed. The present study contributes to the definition of the functioning of a “normal” West African estuary, the Gambia estuary, with balanced effects of marine and freshwater influences and the presence of all bio-ecological categories. The Gambia estuary can therefore be considered to be a reference ecosystem for further comparisons with other tropical estuarine ecosystems, subjected to natural or artificial perturbations.

Simier, Monique; Laurent, Charline; Ecoutin, Jean-Marc; Albaret, Jean-Jacques

2006-09-01

87

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

Energy Technology Data Exchange (ETDEWEB)

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 {sup 240}Pu/{sup 239}Pu 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 HNO{sub 3}-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, {sup 240}Pu/{sup 239}Pu ratios were relatively consistent between different extraction fractions, although, in whole 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.

Skipperud, Lindis [Isotope Laboratory, Department of Plant and Environmental Science, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Aas (Norway)], E-mail: lindis.skipperud@umb.no; Brown, Justin [Norwegian Radiation Protection Authority, P.O. Box 55, Osteras (Norway); Fifield, L. Keith [Department of Nuclear Physics, Australian National University, Canberra, ACT 0200 (Australia); Oughton, Deborah H.; Salbu, Brit [Isotope Laboratory, Department of Plant and Environmental Science, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Aas (Norway)

2009-04-15

88

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

Science.gov (United States)

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 (240)Pu/(239)Pu 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 HNO(3)-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, (240)Pu/(239)Pu ratios were relatively consistent between different extraction fractions, although, in whole 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. PMID:19157655

Skipperud, Lindis; Brown, Justin; Fifield, L Keith; Oughton, Deborah H; Salbu, Brit

2009-01-21

89

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

UK PubMed Central (United Kingdom)

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 (240)Pu/(239)Pu 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 HNO(3)-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, (240)Pu/(239)Pu ratios were relatively consistent between different extraction fractions, although, in whole 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.

Skipperud L; Brown J; Fifield LK; Oughton DH; Salbu B

2009-04-01

90

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

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a preliminary approach on the hydrodynamics of the Cubatão River estuary based on hydrographic data from a thirteen-hour campaign (a complete tidal cycle) under spring tide condition. Current speed and direction, salinity, temperature and turbidity were recorded at 1.5 m bellow the water surface near the estuary mouth, with a moored acoustic currentmeter. Vertical profiles of salinity and temperature were done close to the mooring every hour with a CTD to give the vertical estuarine structure. Vertical profiles of CTD were also done along the estuary during the flood slack water. The results show that the Cubatão River estuary is vertically homogeneous almost time, with small periods with weak stratification during the ebb. The tidal regime was assimetric, with ebb currents stronger than flood currents. Este trabalho apresenta uma caracterização preliminar da hidrodinâmica do estuário do Rio Cubatão baseada em dados hidrográficos obtidos durante uma campanha de treze horas (um ciclo completo de maré) em condições de maré de sizígia. Dados de velocidade e direção de corrente, salinidade, temperatura e turbidez foram obtidos à 1,5 m abaixo da superfície, próximo da desembocadura do estuário com o fundeio de um correntógrafo acústico. Perfis verticais de salinidade e temperatura foram realizados próximos ao fundeio a cada hora com um CTD para fornecer a estrutura vertical. Perfis de CTD também foram realizados ao longo do estuário durante a preamar. Os resultados mostram que o estuário do Rio Cubatão apresenta-se verticalmente homogêneo com períodos menores de estratificação durante a vazante. O regime de maré mostra uma assimetria acentuada, com correntes de vazante muito mais intensas do que as correntes de enchente.

C. A. SCHETTINI; J. L. CARVALHO

2000-01-01

91

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

Directory of Open Access Journals (Sweden)

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; Leszek KSI??EK

2013-01-01

92

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

93

Chromium in water, suspended particles, sediments and biota in the Iraja River estuary  

Energy Technology Data Exchange (ETDEWEB)

Analyses of chromium concentrations in waters, suspended particles, bottom sediments, fish (Poecilia reticulata), plants (Paspalum vaginatum, Sesuvium portulacastrum, Philoxeros vermicularis), soils and barnacles (Balanus sp.) were performed from August 1976 to September 1980 in samples collected from the Iraja River and inside its estuary in Guanabara Bay (Rio de Janeiro, Brazil). Sediments and water from the Iraja River showed chromium concentrations of 17536 and 23.39 ppm--a thousand times higher than the published data for freshwater systems. Chromium removed from solution by bottom sediments reaches Guanabara Bay linked to particulate matter. Fish and emergent grass inside the river concentrate chromium from water and/or sediment, returning the metal to the system as detritus. Soil and plants inside the estuary concentrate chromium thirty and ten times higher than in the control area. The vegetal community exhibits a concentration factor smaller than that related to soil and prevents the return of chromium to the estuarine waters. Inside the Guanabara Bay, Balanus sp. appears to be an effective biological monitor as it concentrates chromium in soft tissues 10/sup 3/ times higher than values found in suspended particles (0.012 ..mu..g ml/sup -1/).

Pfeiffer, W.C.; Fiszman, M.; de Lacerda, L.D.; van Weerfelt, M.; Carbonell, N.

1982-11-01

94

Historical records of eutrophication in Changjiang (Yangtze) River estuary and its adjacent East China Sea  

Directory of Open Access Journals (Sweden)

Full Text Available Two sediment cores from the Changjiang (Yangtze) River estuary and its adjacent East China Sea were collected and studied for eutrophication history using paleoecological records of environmental changes over the last century. A multiproxy approach by using biological and geochemical analyses revealed changes in diatom assemblages, total organic carbon (TOC), total nitrogen (TN) and biogenic silica (BSi) and give an indication of nutrient in status and trends in Changjiang River estuary and its adjacent East China Sea. The diatom assemblages in the two cores generally increased gradually from the 1970s, and accelerated from the 1990s until now, reflecting the increased eutrophication and causing large algae blooms/red tides. The TOC, TN and BSi showing the similar trends, supported the interpretation of the eutrophication process indicated by diatom analyses. The two cores were located in different sea areas of the East China Sea, and we discuss their relative changes based on their environment characteristics. We also discuss the potential effect of anthropogenic influences and ongoing projects on eutrophication in the Changjiang River and its adjacent East China Sea.

F. Cheng; X. Song; Z. Yu; D. Liu

2012-01-01

95

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.

2009-01-01

96

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

97

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

UK PubMed Central (United Kingdom)

Multitracers were used to study water mixing in the Paraíba 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 approximately 35). During the rainy period this value decreased to 6 days. Based on the radium results, it was possible to calculate diffusion coefficients (K(h)) of 23 km(2) d(-1) and 38 km(2) d(-1) for 224Ra and 223Ra, respectively, during the dry season (winter). Values of 65 km(2) d(-1) and 68 km(2) d(-1) for 223Ra and 224Ra, respectively, were found for the rainy period (summer).

Souza TA; Godoy JM; Godoy ML; Moreira I; Carvalho ZL; Salomão MS; Rezende CE

2010-07-01

98

Foraging ecology of Caspian Terns in the Columbia River Estuary, USA  

Science.gov (United States)

Comparisons were made of the foraging ecology of Caspian Terns (Sterna caspia) nesting on two islands in the Columbia River estuary using radio telemetry and observations of prey fed to chicks and mates at each colony. Early in the chick-rearing period, radio-tagged terns nesting at Rice Island (river km 34) foraged mostly in the freshwater zone of the estuary close to the colony, while terns nesting on East Sand Island (river km 8) foraged in the marine or estuarine mixing zones close to that colony. Late in the chick-rearing period, Rice Island terns moved more of their foraging to the two zones lower in the estuary, while East Sand Island terns continued to forage in these areas. Tern diets at each colony corresponded to the primary foraging zone (freshwater vs. marine/ mixing) of radio-tagged individuals: Early in chick-rearing, Rice Island terns relied heavily on juvenile salmonids (Oncorhynchus spp., 71% of identified prey), but this declined late in chick-rearing (46%). East Sand Island terns relied less on salmonids (42% and 16%, early and late in chick-rearing), and instead utilized marine fishes such as Anchovy (Engraulis mordax) and Herring (Clupea pallasi). Throughout chick-rearing, Rice Island terns foraged farther from their colony (median distance: 12.3 km during early chick-rearing and 16.9 km during late chick-rearing) than did East Sand Island terns (9.6 and 7.7 km, respectively). The study leads to the conclusion that Caspian Terns are generalist foragers and make use of the most proximate available forage fish resources when raising young.

Lyons, D. E.; Roby, D. D.; Collis, K.

2005-01-01

99

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

Directory of Open Access Journals (Sweden)

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.

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

2012-01-01

100

Biogeochemical behavior of organic carbon in a small tropical river and estuary, Hainan, China  

Science.gov (United States)

The biogeochemistry of a small tropical river and estuary (the Wanquan River (WQR)) in Hainan, China, was studied to obtain information on the sources, transformation and fate of riverine organic matter. Water and total suspended matter were sampled along a salinity gradient during four field campaigns in December 2006, August 2007, July-August 2008 and April 2009. We were able to observe the effect of heavy precipitation associated with the tropical cyclone Kammuri (2008) and a strong first-rain event (2009) on the export of organic carbon. Both dissolved organic carbon (DOC) and particulate organic carbon (POC) generally decreased with increasing salinity in the estuary, with minimal seasonal or annual variations. The POC concentrations were in the range of 18-178?M for the WQR and were significantly correlated with chlorophyll a concentrations. The highest average values of DOC (˜190?M) were observed in 2009. These values could be the result of the flushing effect of the first rain. In the high-salinity zone, in situ productivity could be an important source for DOC. The ?13Corg values of particles (-29.5‰ to -23.2‰), combined with the ratio of organic carbon to total nitrogen (OC/TN), reflect a mixture of terrestrial organic matter and in situ production. The amplitudes of the POC and DOC variations on the occasion of the first-rain event of 2009 were larger than those observed during Kammuri. It is estimated that 29.8tday-1 of DOC and 10.4tday-1 of POC, representing 6-10% of the annual loads, were delivered to the coast during the 10-day period of the first flush event in 2009. Our results demonstrate the important role of short-term aperiodic events on small rivers and estuaries along tropical coasts.

Wu, Ying; Bao, Hong-Yan; Unger, Daniela; Herbeck, Lucia S.; Zhu, Zhuo-Yi; Zhang, Jing; Jennerjahn, Tim C.

2013-04-01

 
 
 
 
101

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.)

1972-01-01

102

Multivariate statistical study of heavy metal enrichment in sediments of the Pearl River Estuary  

International Nuclear Information System (INIS)

Multivariate statistical analysis identified the heavy metal accumulation layers of sediment profiles and showed the various sources of metals in the estuary. - The concentrations and chemical partitioning of heavy metals in the sediment cores of the Pearl River Estuary were studied. Based on Pearson correlation coefficients and principal component analysis results, Al was selected as the concentration normalizer for Pb, while Fe was used as the normalizing element for Co, Cu, Ni and Zn. In each profile, sections with metal concentrations exceeding the upper 95% prediction interval of the linear regression model were regarded as metal enrichment layers. The heavy metal accumulation mainly occurred at sites in the western shallow water areas and east channel, which reflected the hydraulic conditions and influence from riparian anthropogenic activities. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. Since the residual, Fe/Mn oxides and organic/sulfide fractions were dominant geochemical phases in the enriched sections, the bioavailability of heavy metals in sediments was generally low. The 206Pb/207Pb ratios in the metal-enriched sediment sections also revealed the influence of anthropogenic sources. The spatial distribution of cumulative heavy metals in the sediments suggested that the Zn and Cu mainly originated from point sources, while the Pb probably came from non-point sources in the estuary.

2003-01-01

103

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

UK PubMed Central (United Kingdom)

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.

Xu W; Yan W; Li X; Zou Y; Chen X; Huang W; Miao L; Zhang R; Zhang G; Zou S

2013-08-01

104

Impacts of Mississippi River diversions on salinity gradients in a deltaic Louisiana estuary: Ecological and management implications  

Science.gov (United States)

Large-scale river diversions on the lower Mississippi River are considered to be an important component of wetland restoration efforts in coastal Louisiana. Diversions are used primarily for salinity control but increasingly proposed also as a major way to deliver sediments and nutrients to coastal wetlands impacted by the construction of flood control levees. We used a coupled hydrology-hydrodynamics model of the Barataria estuary, a site of the Davis Pond Diversion - the world's largest river diversion project, to examine salinity variations under different diversion discharge scenarios. Discharge scenarios were selected based on actual freshwater discharges in different years and management alternatives that included a scenario with several new diversions. The model results indicate that river diversions strongly affect salinities only in the middle section of the Barataria estuary. The upper parts of the estuary are fresh most of the time and so the excess fresh water from river diversions has only a minor impact on salinity in this region. Also, the Davis Pond diversion has little impact on salinities in the coastal section of the estuary because of strong marine influence in this area adjacent to the Gulf of Mexico. Interestingly, the predicted salinity differences between different model scenarios can be as high as 10 in some months and places. These differences can be biologically significant depending on the salinity tolerance of different species and could cause a shift in community composition within the affected region.

Das, Anindita; Justic, Dubravko; Inoue, Masamichi; Hoda, Asif; Huang, Haosheng; Park, Dongho

2012-10-01

105

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.).

1980-01-01

106

Ecosystem health assessment in the pearl river estuary of China by considering ecosystem coordination.  

UK PubMed Central (United Kingdom)

Marine ecosystem is a complex nonlinear system. However, ecosystem health assessment conventionally builds on a linear superposition of changes in ecosystem components and probably fails to evaluate nonlinear interactions among various components. To better reflect the intrinsic interactions and their impacts on ecosystem health, an ecosystem coordination index, defined as the matching level of ecosystem structure/services, is proposed and incorporated into the ecosystem health index for a systematic diagnosis in the Pearl River Estuary, China. The analysis results show that the ecosystem health index over the last three decades decreased from 0.91 to 0.50, indicating deteriorating from healthy to unhealthy status. The health index is 3-16% lower than that calculated using the common method without considering ecosystem coordination. Ecosystem health degradation in the Pearl River Estuary manifested as significant decreases in structure/services and somewhat mismatching among them. Overall, the introduction of coordination in ecosystem health assessment could improve the understanding of the mechanism of marine ecosystem change and facilitate effective restoration of ecosystem health.

Chen X; Gao H; Yao X; Chen Z; Fang H; Ye S

2013-01-01

107

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

108

[Spectroscopic characteristics of different molecular weight dissolved organic matter in water from Yangtze River estuary].  

UK PubMed Central (United Kingdom)

Cross flow ultrafiltration systems and three dimensional fluorescence spectrum were used to investigate the fluorescence characterization of different molecular weight dissolved organic matter in water of wet season and dry season from Yangtze River estuary, in order to find out the sources and influencing factors. The results showed that four types of dissolved organic carbon (DOM) fluorescence peaks were observed in the water: humic-like fluorescence peak A and C, and protein-like fluorescence peak B and D. Fluorescent substances mainly existed in the truly dissolved organic matter (UOM, < 1 kDa), secondly in low and medium molecular weight of colloidal organic matter (1-500 kDa). Protein of DOM in water mainly originated from anthropogenic sources, then from autochthonous sources. Compared to protein, humic acid of DOM in wet season was both terrigenous and autochthonous sources, while in dry season mainly from terrestrial organic matter. In addition, humic acid in UOM was mainly derived from biological decomposition, however, in colloidal organic matter (COM) came from terrestrial organic matter and was affected by resuspension effects. There was linear correlation between fluorescence intensity and environmental parameters. It was revealed that the complex environmental conditions would influence the fluorescent substance of DOM in water from Yangtze River estuary.

Huang WD; Zhou LM; Zheng XM; Huang J; Chen SJ

2013-04-01

109

[Spectroscopic characteristics of different molecular weight dissolved organic matter in water from Yangtze River estuary].  

Science.gov (United States)

Cross flow ultrafiltration systems and three dimensional fluorescence spectrum were used to investigate the fluorescence characterization of different molecular weight dissolved organic matter in water of wet season and dry season from Yangtze River estuary, in order to find out the sources and influencing factors. The results showed that four types of dissolved organic carbon (DOM) fluorescence peaks were observed in the water: humic-like fluorescence peak A and C, and protein-like fluorescence peak B and D. Fluorescent substances mainly existed in the truly dissolved organic matter (UOM, < 1 kDa), secondly in low and medium molecular weight of colloidal organic matter (1-500 kDa). Protein of DOM in water mainly originated from anthropogenic sources, then from autochthonous sources. Compared to protein, humic acid of DOM in wet season was both terrigenous and autochthonous sources, while in dry season mainly from terrestrial organic matter. In addition, humic acid in UOM was mainly derived from biological decomposition, however, in colloidal organic matter (COM) came from terrestrial organic matter and was affected by resuspension effects. There was linear correlation between fluorescence intensity and environmental parameters. It was revealed that the complex environmental conditions would influence the fluorescent substance of DOM in water from Yangtze River estuary. PMID:23841416

Huang, Wen-Dan; Zhou, Li-Min; Zheng, Xiang-Min; Huang, Jing; Chen, Shi-Ji

2013-04-01

110

Paleoenvironmental and paleoclimatic conditions in the Tagus River Estuary during the Holocene  

Science.gov (United States)

Estuaries constitute the frontier between terrestrial, fluvial and marine environments, representing areas of high biological productivity that are particularly sensitive to global, regional and local environmental and climatic changes. The lower Tagus valley experienced a transgression period from 12000 - 7000 calendar (cal) years BP (Vis et al., 2008;QSR). Trying to understand the interaction between land-river and ocean, we are studying paleoenvironmental conditions of the Tagus river estuary, using a 52,76 m long core drilled near Vila Franca de Xira (38°56´24´´N; 8°56´19´´W, 2 meters elevation). The age model of this core is based on 6 AMS 14C dates. Marine/estuarine productivity and river input have been reconstructed for the last 14 000 calendar years BP, using a high resolution, multi-proxy study of diatoms, C37 alkenones, higher plant C23 - C33 n-alkanes and C20 - C30 n-alkan-1-ols, Fe and Ca content derived from XRF analysis and Total Organic Carbon (TOC). Our data shows that major river input events (as revealed by higher concentrations of terrestrial lipid biomarkers and phytoliths) control the primary productivity at this site because increased productivity - maxima in diatoms, C37 alkenones and TOC - are synchronous. Marine and brackish diatom genera and C37 alkenones occur between ca. 11500- 4500 cal years BP indicating a marine to brackish environment, probably in a shallow marine pro-delta. After 4500 cal years sea level had risen so much that the marine influence was reduced (low abundance of marine diatoms) and the environmental was similar to the modern, i.e., a brackish tidal flat. Further work is needed to improve the understanding of this estuarine record.

Santos, Célia; Abrantes, Fátima; Rodrigues, Teresa; Voelker, Antje; Vis, Geert-Jan

2010-05-01

111

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

UK PubMed Central (United Kingdom)

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.

Chung CY; Chen JJ; Lee CG; Chiu CY; Lai WL; Liao SW

2011-02-01

112

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

2006-01-01

113

Genotype and Seeding Date Effects on Performance of Mangrove Rice (Oryza sativa L.) In the Cross River Estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The mangrove swamp soils of the Cross River estuary are suitable for intensive rice cultivation because of ample water supply, large level units and high inherent fertility. However, because water is abundant, rainfall does not determine the sowing period. Field studies were conducted in 2006 and 20...

W.B. Binang; J.D. Ntia; O.J. Shiyam

114

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

1995-01-01

115

The pollution history of the Savannah River Estuary. Final report 1 Sep 1976--31 Dec 1977  

International Nuclear Information System (INIS)

Records of natural and pollutant fluxes to the Savannah River Estuary are found in some river and marsh deposits into which time frames can be introduced by 210Pb or plutonium geochronologies. Plutonium releases from the Savannah River Plant are evident in only one deposit and in marsh grass which received the transuranic element from atmospheric transport. The pollution records can be disturbed by bioturbative activities of organisms, by the input of marine solid phases to the estuarine deposits, and by river scour and fill.

1976-09-01

116

Influence of river discharge patterns on the hydrodynamics and potential contaminant dispersion in the Douro estuary (Portugal).  

UK PubMed Central (United Kingdom)

Freshwater input to estuaries is a fundamental feature of these ecosystems, which may be profoundly altered by river damming as human needs for water consumption, irrigation or energy production increase. The Douro estuary is limited upstream by a dam since 1985, which reduced its length by ca. 60%. Freshwater inputs to the estuary are now irregular and greatly dependent on hydroelectric power demand; values ranging from zero to over 1000m(3)s(-1), in a matter of hours, especially in summer are common. In the present study, a three-dimensional hydrodynamic model was applied to the Douro estuary. The model was calibrated and validated against water elevation, current velocity, salinity and temperature data. Thereafter, it was used to analyse the effects of different flow regimes and magnitudes on estuarine hydrodynamics and contaminant dispersion. Results obtained suggest that the highly variable flow regimes, currently observed in the Douro, tend to reduce water column stratification and to enhance seawater intrusion, when compared with flow discharges of similar average magnitude, but lower variability. Stable flows seem to be the most effective in dispersing contaminants eventually introduced into the estuary through its small river tributaries. Overall results suggest that flow management may have important effects on estuarine hydrodynamics through non-linear interactions between flow magnitude and variability.

Azevedo IC; Bordalo AA; Duarte PM

2010-05-01

117

Impact of seasonal tide variation on saltwater intrusion in the Changjiang River estuary  

Science.gov (United States)

An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch (NB) and the South Branch (SB). The study assumes that the river discharge and wind are constant. The model successfully reproduced the saltwater intrusion. During spring tide, there is water and salt spillover (WSO and SSO) from the NB into the SB, and tidally averaged (net) water and salt fluxes are 985 m3/s and 24.8 ton/s, respectively. During neap tide, the WSO disappears and its net water flux is 122 m3/s. Meanwhile, the SSO continues, with net salt flux of 1.01 ton/s, much smaller than during spring tide. Because the tidal range during spring tide is smaller in June than in March, overall saltwater intrusion is weaker in June than in March during that tidal period. However, the WSO and SSO still exist in June. Net water and salt fluxes in that month are 622 m3/s and 15.35 ton/s, respectively, decreasing by 363 m3/s and 9.45 ton/s over those in March. Because tidal range during neap tide is greater in June than in March, saltwater intrusion in June is stronger than in March during that tidal period. The WSO and SSO appear in June, with net water and salt fluxes of 280 m3/s and 8.55 ton/s, respectively, increasing by 402 m3/s and 7.54 ton/s over those in March. Saltwater intrusion in the estuary is controlled by the river discharge, semi-diurnal flood-ebb tide, semi-monthly spring or neap tide, and seasonal tide variation.

Qiu, Cheng; Zhu, Jianrong; Gu, Yuliang

2012-03-01

118

Stratification of Archaeal communities in shallow sediments of the Pearl River Estuary, Southern China.  

UK PubMed Central (United Kingdom)

Microorganisms are known to play fundamental roles in the biogeochemical cycling of carbon in the coastal environments. To get to know the composition and ecological roles of the archaeal communities within the sediments of the Pearl River Estuary, Southern China, the diversity and vertical distribution of archaea in a sediment core was reported based on the 16S rRNA and mcrA genes for the first time. Quantitative PCR analysis revealed that archaea were present at 10(6)-10(7) 16S rRNA gene copies/g (wet weight) in the sediment core, and the proportion of mcrA versus 16S rRNA gene copies varied from 11 to 45%. 16S rRNA gene libraries were constructed and analyzed for the top layer (0-6 cm), middle layer (18-24 cm), sulfate-methane transition zone (SMTZ, 32-42 cm), and bottom layer (44-50 cm) sediments. The results indicated that Miscellaneous Crenarchaeotal Group (MCG) was the main component in the sediments. The MCG archaea could be further divided into six subgroups: MCG-A, B, C, D, E, and F. On the other hand, mcrA sequences from methanogens related to the order Methanomicrobiales and ANME-2 methanotrophs were detected in all sediment layers. Taken together, our data revealed a largely unknown archaeal community in which MCG dominated within the Pearl River estuarine sediments, while methanogens and methane-oxidizing archaea putatively involving in methane metabolism, were also found in the community. This is the first important step towards elucidating the biogeochemical roles of these archaea in the Pearl River Estuary.

Jiang L; Zheng Y; Chen J; Xiao X; Wang F

2011-05-01

119

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

UK PubMed Central (United Kingdom)

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.

Kessarkar PM; Shynu R; Rao VP; Chong F; Narvekar T; Zhang J

2013-05-01

120

Recent sediments of the St. Marks River coast, northwest Florida, a low-energy, sediment-starved estuary  

Energy Technology Data Exchange (ETDEWEB)

The St. Marks river of northwest Florida drains parts of the central panhandle of northwestern Florida, and a small area in southwestern Georgia. It traverses nearly 56.3 kilometers through a watershed of 1,711 square kilometers. The slow-moving river carries little sediment and terminates in Apalachee Bay, a low-energy embayment in the northeasternmost Gulf of Mexico. The coastal region is characterized by mudflats, seagrass beds, and an absence of sandy beaches and barrier islands. Clastic sediments of the coast and shelf rest on a shallow-dipping carbonate platform. The upper surface of the platform is locally karstic. As a result, like other rivers in this region of northwest Florida, the St. Marks watershed is marked by sinkholes and disappearing streams. The fact that the river travels underground through part of its lower watershed serves to trap or sieve some of its clastic load. In the estuary, the undulating karst topography causes the estuarine sediments to vary in thickness from 0 to 4+ meters. The concave shape of the coastline and its orientation with respect to prevailing winds result in low average wave energy. Sedimentation is therefore controlled by riverine and tidal forces. The relatively low energy conditions result in good preservation of the sedimentary record in the St. Marks estuary. A suite of sediment cores has been collected in the lower river, estuary and adjacent Gulf of Mexico. Lead-210 dating results indicate a slow average sedimentation rate ([approximately] 1mm/yr). Investigation of sedimentation rates and sediment characteristics over time in the St. Marks estuary indicate that sedimentologic conditions in this low-energy environment have been relatively stable during the recent geologic history of the estuary.

Highly, A.B. (Florida State Univ., Tallahassee (United States). Dept. of Geology Florida Geological Survey, Tallahassee, FL (United States)); Donoghue, J.F. (Florida State Univ., Tallahassee, FL (United States). Dept. of Geology); Garrett, C.; Hoenstine, R.W.; Hertler, H. (Florida Geological Survey, Tallahassee, FL (United States))

1994-03-01

 
 
 
 
121

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)

[en] 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

1992-01-01

122

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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-...

Akira Haraguchi

123

Antibiotic-resistant bacteria in the Hudson River Estuary linked to wet weather sewage contamination.  

UK PubMed Central (United Kingdom)

Heterotrophic bacteria resistant to tetracycline and ampicillin were assessed in waterways of the New York City metropolitan area using culture-dependent approaches and 16S rRNA gene sequence analysis of resultant isolates. Resistant microbes were detected at all 10 sampling sites in monthly research cruises on the lower Hudson River Estuary (HRE), with highest concentrations detected at nearshore sites. Higher frequency sampling was conducted in Flushing Bay, to enumerate resistant microbes under both dry and wet weather conditions. Concentrations of ampicillin- and tetracycline-resistant bacteria, in paired samples, were positively correlated with one another and increased following precipitation. Counts of the fecal indicator, Enterococcus, were positively correlated with levels of resistant bacteria, suggesting a shared sewage-associated source. Analysis of 16S rRNA from isolates identified a phylogenetically diverse group of resistant bacteria, including genera containing opportunistic pathogens. The occurrence of Enterobacteriaceae, a family of enteric bacteria, was found to be significantly higher in resistant isolates compared to total heterotrophic bacteria and increased following precipitation. This study is the first to document the widespread distribution of antibiotic-resistant bacteria in the HRE and to demonstrate clearly a link between the abundance of antibiotic-resistant bacteria and levels of sewage-associated bacteria in an estuary.

Young S; Juhl A; O'Mullan GD

2013-06-01

124

Bacterial polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenases in the sediments from the Pearl River estuary, China.  

Science.gov (United States)

Bacterial community compositions were characterized using denaturing gradient gel electrophoresis analysis of bacterial 16S rRNA gene in the sediments of the Pearl River estuary. Sequencing analyses of the excised bands indicated that Gram-negative bacteria, especially Gammaproteobacteria, were dominant in the Pearl River estuary. The diversity of polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenase (PAH-RHD) gene in this estuary was then assessed by clone library analysis. The phylogenetic analyses showed that all PAH-RHD gene sequences of Gram-negative bacteria (PAH-RHD[GN]) were closely related to the nagAc gene described for Ralstonia sp. U2 or nahAc gene for Pseudomonas sp. 9816-4, while the PAH-RHD gene sequences of Gram-positive bacteria (PAH-RHD[GP]) at sampling site A1 showed high sequence similarity to the nidA gene from Mycobacterium species. Meanwhile, molecular diversity of the two functional genes was higher at the upstream of this region, while lower at the downstream. Redundancy analysis indicated that environmental factors, such as NH4-N, ?PAHs, pH, SiO3-Si, and water depth, affected the distribution of the PAH-RHD[GN] gene in the Pearl River estuary. PMID:23558584

Wu, Peng; Wang, You-Shao; Sun, Fu-Lin; Wu, Mei-Lin; Peng, Ya-Lan

2013-04-01

125

Bacterial polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenases in the sediments from the Pearl River estuary, China.  

UK PubMed Central (United Kingdom)

Bacterial community compositions were characterized using denaturing gradient gel electrophoresis analysis of bacterial 16S rRNA gene in the sediments of the Pearl River estuary. Sequencing analyses of the excised bands indicated that Gram-negative bacteria, especially Gammaproteobacteria, were dominant in the Pearl River estuary. The diversity of polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenase (PAH-RHD) gene in this estuary was then assessed by clone library analysis. The phylogenetic analyses showed that all PAH-RHD gene sequences of Gram-negative bacteria (PAH-RHD[GN]) were closely related to the nagAc gene described for Ralstonia sp. U2 or nahAc gene for Pseudomonas sp. 9816-4, while the PAH-RHD gene sequences of Gram-positive bacteria (PAH-RHD[GP]) at sampling site A1 showed high sequence similarity to the nidA gene from Mycobacterium species. Meanwhile, molecular diversity of the two functional genes was higher at the upstream of this region, while lower at the downstream. Redundancy analysis indicated that environmental factors, such as NH4-N, ?PAHs, pH, SiO3-Si, and water depth, affected the distribution of the PAH-RHD[GN] gene in the Pearl River estuary.

Wu P; Wang YS; Sun FL; Wu ML; Peng YL

2013-04-01

126

The distribution and partitioning of common antibiotics in water and sediment of the Pearl River Estuary, South China.  

UK PubMed Central (United Kingdom)

Antibiotics released into the aquatic environment play an important role in the spread of antibiotic resistance. In the Pearl River Estuary (PRE) and the coastal zone, the concentrations of antibiotics decreased from the Pearl River to the estuary, suggesting that antibiotics primarily originated from river tributaries and terrigenous sources. Within the PRE area, the concentrations of antibiotics in water were higher in the west coast than the east side, reflecting the high density of anthropogenic activities and hydraulic conditions along the west riverbank. Seasonal variations were also observed for most of detected antibiotics in water. The pseudo-partitioning coefficient of norfloxacin had a good correlation with the TOC content of sediments, as did erythromycin-H2O with the pH of water. The results suggest that environmental conditions can significantly affect the distribution of antibiotics between water and sediment.

Liang X; Chen B; Nie X; Shi Z; Huang X; Li X

2013-09-01

127

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

Scientific Electronic Library Online (English)

Full Text Available 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 p (more) rocesso 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 i (more) n 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.

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

2011-11-01

128

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

129

Mechanistic and statistical models of total Vibrio abundance in the Neuse River Estuary.  

UK PubMed Central (United Kingdom)

Bacteria in the genus Vibrio are ubiquitous to estuarine waters worldwide and are often the dominant genus recovered from these environments. This genus contains several potentially pathogenic species, including Vibrio vulnificus, Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio alginolyticus. These bacteria have short generation times, as low as 20-30 min, and can thus respond rapidly to changing environmental conditions. A five-parameter mechanistic model was generated based on environmental processes including hydrodynamics, growth, and death rates of Vibrio bacteria to predict total Vibrio abundance in the Neuse River Estuary of eastern North Carolina. Additionally an improved statistical model was developed using the easily monitored parameters of temperature and salinity. This updated model includes data that covers more than eight years of constant bacterial monitoring, and incorporates extreme weather events such as droughts, storms, and floods. These models can be used to identify days in which bacterial abundance might coincide with increased health risks.

Froelich B; Bowen J; Gonzalez R; Snedeker A; Noble R

2013-07-01

130

[Sanitary and microbiological evaluation of the hydrosystem in the Volga river estuary upon anthropogenic pollution  

UK PubMed Central (United Kingdom)

The paper gives many years' data on the size of the opportunistic and sanitary-significant microflora of pike perches (Stizostedion) and water in the producer's food fish areas of the Volga river estuary, as well as the results of ecological and microbiological studies of the water from the above areas, which include the determination of the total amount of the bacterial plankton on membrane filters, the number of heterotrophic bacteria, which has provided an assessment of the habitat quality of hydrocoles in accordance with the complex ecological classification of the quality of the land's surface water. The paper analyzes the seasonal abundance and spatial distribution of the most common opportunistic microorganisms, as well as the markers of their pathogenicity.

Obukhova OV; Lartseva LV; Lisitskaia IA

2009-01-01

131

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2007  

Energy Technology Data Exchange (ETDEWEB)

The goal of this multi-year study (2004-2010) 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. Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. Field research in 2005, 2006, and 2007 involved intensive, comparative studies paired by habitat type (tidal swamp vs. marsh), trajectory (restoration vs. reference site), and restoration action (tide gate vs. culvert vs. dike breach). The field work established two kinds of monitoring indicators for eventual cumulative effects analysis: core and higher-order indicators. Management implications of limitations and applications of site-specific effectiveness monitoring and cumulative effects analysis were identified.

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

2008-10-01

132

Comprehensive assessment of heavy metal contamination in sediment of the Pearl River Estuary and adjacent shelf.  

UK PubMed Central (United Kingdom)

Total metal concentrations (Cr, Ni, Cu, Zn, and Pb), acid volatile sulfide and simultaneously extracted metals (AVS-SEM), and heavy metal fractionation were used to assess the heavy metals contamination status and ecological risk in the sediments of the Pearl River Estuary (PRE) and adjacent shelf. Elevated concentrations at estuarine sites and lower concentrations at adjacent shelf sites are observed, especially for Cu and Zn. Within the PRE, the concentration of heavy metals in the western shore was mostly higher than that in the middle shore. The metals from anthropogenic sources mainly occur in the labile fraction and may be taken up by organisms as the environmental parameters change. A combination of total metal concentrations, metal contamination index and sequential extraction analysis is necessary to get the comprehensive information on the baseline, anthropogenic discharge and bioavailability of heavy metals.

Yang Y; Chen F; Zhang L; Liu J; Wu S; Kang M

2012-09-01

133

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 Bangpakong 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.

Thanomsak Boonphakdee

2008-01-01

134

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

2007-01-01

135

Large-river delta-front estuaries as natural "recorders" of global environmental change.  

UK PubMed Central (United Kingdom)

Large-river delta-front estuaries (LDE) are important interfaces between continents and the oceans for material fluxes that have a global impact on marine biogeochemistry. In this article, we propose that more emphasis should be placed on LDE in future global climate change research. We will use some of the most anthropogenically altered LDE systems in the world, the Mississippi/Atchafalaya River and the Chinese rivers that enter the Yellow Sea (e.g., Huanghe and Changjiang) as case-studies, to posit that these systems are both "drivers" and "recorders" of natural and anthropogenic environmental change. Specifically, the processes in the LDE can influence ("drive") the flux of particulate and dissolved materials from the continents to the global ocean that can have profound impact on issues such as coastal eutrophication and the development of hypoxic zones. LDE also record in their rapidly accumulating subaerial and subaqueous deltaic sediment deposits environmental changes such as continental-scale trends in climate and land-use in watersheds, frequency and magnitude of cyclonic storms, and sea-level change. The processes that control the transport and transformation of carbon in the active LDE and in the deltaic sediment deposit are also essential to our understanding of carbon sequestration and exchange with the world ocean--an important objective in global change research. U.S. efforts in global change science including the vital role of deltaic systems are emphasized in the North American Carbon Plan (www.carboncyclescience.gov).

Bianchi TS; Allison MA

2009-05-01

136

Bioconcentration of polycyclic aromatic hydrocarbons in roots of three mangrove species in Jiulong River Estuary  

Energy Technology Data Exchange (ETDEWEB)

The polycyclic aromatic hydrocarbons (PAHs) concentrations were determined in the root of three mangrove species (Kandelia candel, Avicennia marina and Bruguiera gymnorrhiza) and their growing environment (sediment) in mangrove wetlands of Jiulong River Estuary, Fujian, China. The total PAHs (16 parent PAHs) in mangrove sediments ranged from 193.44 to 270.53 ng/g dw, with a mean value of 231.76 +/- 31.78 ng/g dw. Compared with other mangrove and coastal marine sediments, the PAHs concentrations of all the sampling areas in this study were at relatively lower level. The total PAHs (13 parent PAHs) values varied from 30.83 to 62.73 ng/g dw in mangrove roots. Benzo(a) pyrene, fluoranthene and pyrene dominated in mangrove sediments. Based on ratios of phenathrene/anthracene, fluoranthene/pyrene and fluoranthene/pyrene + fluoranthene, the main possible sources of surface sediment PAHs were identified as grass, wood or coal combustion for mangrove wetlands of Jiulong River Estuary. Naphthalene and phenathrene were the most abundant compounds in mangrove roots. Sediment-to-vegetation bioconcentration factors (BCF(SV)s) were calculated and their relationships with PAHs' physico-chemical properties were investigated. The average BCF(SV)s of PAHs for three mangrove species roots were almost all under the level of 1 except for naphthalene. Good linear relationship between BCFSV values for mangrove roots and PAHs water solubility, octanol-water partitioning coefficients was derived in present study. The solubility and the octanol-water partition coefficient were proved to be good predictors for the accumulation of PAHs in mangrove roots, respectively.

Lu, Z.Q.; Zheng, W.J.; Ma, L. [Xiamen University, Xiamen (China). School of Life Science

2005-07-01

137

[Methane fluxes and controlling factors in the intertidal zone of the Yellow River estuary in autumn].  

UK PubMed Central (United Kingdom)

The characteristics of methane (CH4) fluxes from tidal wetlands of the Yellow River estuary were observed in situ with static-chamber and GC methods in September and October 2009, and the key factors affecting CH4 fluxes were discussed. From the aspect of space, the CH4 flux ranges in high tidal wetland, middle tidal wetland, low tidal wetland, bare flat are - 0.206-1.264, -0.197-0.431, -0.125-0.659 and -0.742-1.767 mg x (m2 x h)(-1), the day average fluxes are 0.089, 0.038, 0.197 and 0.169 mg x (m2 x h)(-1), respectively, indicating that the tidal wetlands are the sources of CH4 and the source function of CH4 differed among the four study sites, in the order of low tidal wetland > bare flat > high tidal wetland > middle tidal wetland. From the aspect of time, the ranges of CH4 fluxes from the tidal wetland ecosystems are -0.444-1.767 and - 0.742- 1.264 mg x (m2 x h)(-1), and the day average fluxes are 0.218 and 0.028 mg x (m2 x h)(-1) in September and October, respectively. The CH4 fluxes in each tidal wetland in September are higher than those in October except that the high tidal wetland acts as weak sink in September. Further studies indicate that the changes of environmental factors in the Yellow River estuary are complicated, and the CH4 fluxes are affected by multiple factors. The differences of CH4 fluxes characteristics among different tidal wetlands in autumn are probably related to temperature (especially atmospheric temperature) and vegetation growth status, while the effects of water or salinity condition and tide status on the CH4 flux characteristics might not be ignored.

Jiang HH; Sun ZG; Wang LL; Mou XJ; Sun WL; Song HL; Sun WG

2012-02-01

138

Macrobenthos from unvegetated intertidal areas in the Caeté river estuary in Bragança, Pará  

Directory of Open Access Journals (Sweden)

Full Text Available The macrobenthic community structure was studied in inter-tidal, non-vegetated areas of the Caeté river estuary, Pará, Brazil, during the dry season of 2003. Four samples were collected at four stations on the downstream direction (P1 to P4) using a corer (0.008 m2 and 20 cm long). Samples were sieved through a 0,3 mm mesh and the organisms preserved in a 5% formaline saline solution stained with Bengal rose. At each station, sediment samples were collected and salinity and water temperature recorded. A total of 105,500 individuals were collected, divided in 17 taxa comprising the fphyla: Nemertea, Arthropoda and Annelida. Polychaeta dominated the assemblages (11 taxa and 87.25% of the individuals). The most abundant taxa were Mediomastuscalifornienses, Nephtys Huviatilisand Oligochaeta (Tubificidae). Density and richness values varied from 2625 ind.m-2 and 3 taxa at station P1 to 96625 ind.m-2 among 16 taxa at station P4. Cluster analysis seperated three groups (50% similarity): Group 1, including samples from stations P3 and P4, was characterized by a relatively high salinity (22.6 to 26.5) and a fine sand substrate. This group, dominated by Sigambra grubii, was the richest (13 taxa), most diverse (?H´ = 1.18) and abundant (?= 12220 ind.m-2); Group 2, including samples from station P1, was characterized by a salinity of 5,1 and a silt-sandy substrate. This group presented the lowest richness (3 taxa), diversity (?H´ = 0.67) and abundance (?= 665 ind.m-2) values, and was dominated by the species Namalicastysabiuma; and Group 3, including samples from station P2, was characterized by a salinity of 3.6 and a silt-sandy substrate. N. abiuma was the most abundant species of this group that was characterized by intermediate richness (5 taxa), abundance (?= 2010 ind.m-2) and diversity (?H´ = 0.71) values. Thus, it is concluded that in the inter-tidal area of the non-vegetated Caeté river the species number is low; Annelida is the most abundant group; the species composition reflects the estuary salinity gradient; and richness, diversity and abundance increase from the upper to the lower estuary.

José Souto Rosa Filho; Debora Vieira Busman; Andréa Pontes Viana; Aderson Manoel Gregório; Diogo Marques Oliveira

2006-01-01

139

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

Directory of Open Access Journals (Sweden)

Full Text Available The present work was carried out to verify the occurrence and distribution of Cymbasoma longispinosum Bourne, 1890 in a tropical Amazon estuary from North Brazil. Samplings were performed bimonthly from July/2003 to July/2004 at two different transects (Muriá and Curuçá rivers) situated along the Curuçá estuary (Pará, North Brazil). Samples were collected during neap tides via gentle (1 to 1.5 knots) 200 ?m-mesh net tows from a small boat. Additional subsurface water samples were collected for the determination of environmental parameters. Males and females of Cymbasoma longispinosum were only observed during September and November/2003. The highest number of organisms was found in September/2003 at the Muriá River transect. The presence of C. longispinosum in samples obtained during September and November/2003 could probably be related to the reproductive period of this species in the studied estuary, which is directly related to the dry period in the region. The highest salinity values and the highest number of individuals observed in September/2003 corroborate with the previous assumption, since no C. longispinosum was found during the months comprising the rainy period (January to June).O presente trabalho foi desenvolvido para verificar a ocorrência e distribuição de Cymbasoma longispinosum Bourne, 1890 em um estuário tropical amazônico da região norte do Brasil. As coletas foram realizadas bimestralmente de julho/2003 a julho/2004 em dois diferentes transectos (rios Muriá e Curuçá) situados ao longo do estuário do Curuçá (Pará, Norte do Brasil). Amostras foram coletadas durante marés de quadratura por intermédio de arrastos com redes de plâncton de 200?m de abertura de malha, através de um pequeno barco a motor (1 a 1,5 knots). Amostras adicionais de água subsuperficial foram coletadas para determinação dos parâmetros ambientais. Machos e fêmeas de C. longispinosum foram observados apenas durante os meses de setembro e novembro/2003. O maior número de organismos foi encontrado em setembro/2003, no transecto do rio Muriá. A presença de C. longispinosum nas amostras obtidas durante setembro e novembro/2003 poderia estar provavelmente relacionada ao período reprodutivo desta espécie no estuário estudado, o qual está diretamente relacionado ao período seco na região. Os mais elevados valores de salinidade, bem como os elevados números de indivíduos observados no mês de setembro/2003 confirmam a suposição anterior, visto que nenhum indivíduo de C. longispinosum foi registrado durante os meses que incluem o período chuvoso (janeiro a junho).

Natália R. Leite; Luci C.C. Pereira; Fernando Abrunhosa; Marcus A.B. Pires; Rauquírio M. da Costa

2010-01-01

140

Application of Bayesian structural equation modeling for examining phytoplankton dynamics in the Neuse River Estuary (North Carolina, USA)  

Science.gov (United States)

We introduce a Bayesian structural equation modeling framework to explore the spatiotemporal phytoplankton community patterns in the Neuse River Estuary (study period 1995 2001). The initial hypothesized model considered the influence of the physical environment (flow, salinity, and light availability), nitrogen (dissolved oxidized inorganic nitrogen, and total dissolved inorganic nitrogen), and temperature on total phytoplankton biomass and phytoplankton community structure. Generally, the model gave plausible results and enabled the identification of the longitudinal role of the abiotic factors on the observed phytoplankton dynamics. River flow fluctuations and the resulting salinity and light availability changes (physical environment) dominate the up-estuary processes and loosen the coupling between nitrogen and phytoplankton. Further insights into the phytoplankton community response were provided by the positive path coefficients between the physical environment and diatoms, chlorophytes, and cryptophytes in the down-estuary sections. The latter finding supports an earlier hypothesis that these three groups dominate the phytoplankton community during high freshwater conditions as a result of their faster nutrient uptake and growth rates and their tolerance on low salinity conditions. The relationship between dissolved inorganic nitrogen concentrations and phytoplankton community becomes more apparent as we move to the down-estuary sections. A categorization of the phytoplankton community into cyanobacteria, dinoflagellates and an assemblage that consists of diatoms, chlorophytes, and cryptophytes provided the best results in the upper and middle segments of the estuary. Finally, the optimal down-estuary grouping aggregates diatoms and chlorophytes, lumps together dinoflagellates with cryptophytes, while cyanobacteria are treated separately. These structural shifts in the temporal phytoplankton community patterns probably result from combined bottom-up and top-down control effects.

Arhonditsis, G. B.; Paerl, H. W.; Valdes-Weaver, L. M.; Stow, C. A.; Steinberg, L. J.; Reckhow, K. H.

2007-03-01

 
 
 
 
141

Nitrous oxide in the Changjiang (Yangtze River) Estuary and its adjacent marine area: Riverine input, sediment release and atmospheric fluxes  

Directory of Open Access Journals (Sweden)

Full Text Available Dissolved nitrous oxide (N2O) was measured in the waters of the Changjiang (Yangtze River) Estuary and its adjacent marine area during five surveys covering the period of 2002–2006. Dissolved N2O concentrations ranged from 6.04 to 21.3 nM, and indicate great temporal and spatial variations. Distribution of N2O in the Changjiang Estuary was influenced by multiple factors and the key factor varied between cruises. Dissolved riverine N2O was observed monthly at station Xuliujing of the Changjiang, and ranged from 12.4 to 33.3 nM with an average of 19.4 ± 7.3 nM. N2O concentrations in the river waters showed obvious seasonal variations with higher values occurring in both summer and winter. Annual input of N2O from the Changjiang to the estuary was estimated to be 15.0 × 106 mol/yr. N2O emission rates from the sediments of the Changjiang Estuary in spring ranged from ?1.88 to 2.02 ?mol m?2 d?1, which suggests that sediment can act as either a source or a sink of N2O in the Changjiang Estuary. Average annual sea-to-air N2O fluxes from the studied area were estimated to be 7.7 ± 5.5, 15.1 ± 10.8 and 17.0 ± 12.6 ?mol m?2d?1 using LM86, W92 and RC01 relationships, respectively. Hence the Changjiang Estuary and its adjacent marine area are a net source of atmospheric N2O.

G.-L. Zhang; J. Zhang; S.-M. Liu; J.-L. Ren; Y.-C. Zhao

2010-01-01

142

Shallow Sediment Trace Metal Concentrations and Short-Term Accumulation Rates in the Neponset River Estuary, Massachusetts, USA  

Science.gov (United States)

The Neponset River estuary is a small estuary that drains into the Boston Harbor on the east coast of the United States. It is also a highly urbanized estuary and has a long history of urban development over 450 years. In July 2006, six sediment cores were collected in the Neponset River estuary to examine particle dynamics and sediment accumulation via radionuclide (Beryllium-7) dating, and to determine sediment metal concentrations (As, Cu, Pb, and Zn) via ED-XRF measurements. Measured sediment Be-7 profiles indicate various sedimentation environments, where sediment accumulation, resuspension or redeposition is likely to occur. High metal concentrations were often corresponding to high Be-7 inventories in sediment cores. Possible sources of trace metal contaminants in the water column include: storm water run-off, Combined Sewer Overflows (CSOs), a well-documented industrial pollution event that occurred upstream in the early to mid twentieth century, and the resuspension of sediment. Existing and future data will provide baseline information for quantifying the effects of the proposed and pending environmental restoration project, which includes the removal of the Baker Dam. The combined pre- and post-Dam removal data may then be used in cost-benefit analyses for other similar estuarine restoration projects.

Spencer, J. R.; Zhu, J.; Olsen, C. R.

2010-12-01

143

Great earthquakes and tsunamis of the past 2000 years at the Salmon River estuary, central Oregon coast, USA  

Science.gov (United States)

Four buried tidal marsh soils at a protected inlet near the mouth of the Salmon River yield definitive to equivocal evidence for coseismic subsidence and burial by tsunami-deposited sand during great earthquakes at the Cascadia subduction zone. An extensive, landward-tapering sheet of sand overlies a peaty tidal-marsh soil over much of the lower estuary. Limited pollen and macrofossil data suggest that the soil suddenly subsided 0.3-1.0 m shortly before burial. Regional correlation of similar soils at tens of estuaries to the north and south and precise 14C ages from one Salmon River site imply that the youngest soil subsided during the great earthquake of 26 January A.D. 1700. Evidence for sudden subsidence of three older soils during great earthquakes is more equivocal because older-soil stratigraphy can be explained by local hydrographic changes in the estuary. Regional 14C correlation of two of the three older soils with soils at sites that better meet criteria for a great-earthquake origin is consistent with the older soils recording subsidence and tsunamis during at least two great earthquakes. Pollen evidence of sudden coseismic subsidence from the older soils is inconclusive, probably because the amount of subsidence was small (<0.5 m). The shallow depths of the older soils yield rates of relative sea-level rise substantially less than rates previously calculated for Oregon estuaries.

Nelson, A. R.; Asquith, A. C.; Grant, W. C.

2004-01-01

144

Distribution and sources of organochlorine pesticides in water and sediments from Daliao River estuary of Liaodong Bay, Bohai Sea (China)  

Science.gov (United States)

The levels of 19 kinds of organochlorine pesticides (OCPs) in the aqueous phase, suspended particulate matter (SPM), pore water and sediments from Daliao River estuary of Liaodong Bay (Bohai Sea) in northeast China were investigated to evaluate their potential pollution risks. The total OCPs concentrations in the aqueous phase, SPM, pore water and sediments were 3.7-30.1 ng l -1, 4.6-52.6 ng l -1, 157-830 ng l -1 and 2.1-21.3 ng g -1 dry weight, respectively. The concentrations of OCPs, in the Daliao River estuary, are in the mid-range, as compared to those reported in other estuaries worldwide. The distribution of HCHs and DDTs were different indicating different contamination sources. Lindane is the main type of HCH and continuing use in northeast China of 'pure' HCH (lindane) rather than technical HCH accounts for the source. The ratios of (DDE + DDD)/DDT in the samples indicate no recent inputs of these chemicals to the estuary.

Tan, Li; He, Mengchang; Men, Bin; Lin, Chunye

2009-08-01

145

Multi-Scale Action Effectiveness Research in the Lower Columbia River and Estuary, 2011 - FINAL ANNUAL REPORT  

Energy Technology Data Exchange (ETDEWEB)

The study reported here was conducted by researchers at Pacific Northwest National Laboratory (PNNL), the Oregon Department of Fish and Wildlife (ODFW), the University of Washington (UW), and the National Marine Fisheries Service (NMFS) for the U.S. Army Corps of Engineers, Portland District (USACE). This research project was initiated in 2007 by the Bonneville Power Administration to investigate critical uncertainties regarding juvenile salmon ecology in shallow tidal freshwater habitats of the lower Columbia River. However, as part of the Washington Memorandum of Agreement, the project was transferred to the USACE in 2010. In transferring from BPA to the USACE, the focus of the tidal freshwater research project shifted from fundamental ecology toward the effectiveness of restoration in the Lower Columbia River and estuary (LCRE). The research is conducted within the Action Agencies Columbia Estuary Ecosystem Restoration Program (CEERP). Data reported herein spans the time period May 2010 to September 2011.

Sather, Nichole K.; Storch, Adam; Johnson, Gary E.; Teel, D. J.; Skalski, J. R.; Bryson, Amanda J.; Kaufmann, Ronald M.; Woodruff, Dana L.; Blaine, Jennifer; Kuligowski, D. R.; Kropp, Roy K.; Dawley, Earl M.

2012-05-31

146

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

147

A new record of Cleantioides emarginata Kwon & Kim, 1992 (Crustacea, Isopoda, Valvifera) from Changjiang River estuary, China  

Science.gov (United States)

At present, descriptions of Cleantioides emarginata Kwon & Kim, 1992 have been limited to the type locality of Pusan, Korea. In this study, we discovered this species in the Changjiang (Yangtze) River estuary, China. This represents an extension of the known geographical range of C. emarginata. In addition, we present information of a colour pattern not previously described, along with details on the estuarine habitat of the species.

Liu, Wenliang; Poore, Gary C. B.

2013-05-01

148

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

Energy Technology Data Exchange (ETDEWEB)

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.

Luo, X.J.; Chen, S.J.; Mai, B.X.; Yang, Q.S.; Sheng, G.Y.; Fu, J.M. [Chinese Academy of Sciences, Ghangzhou (China)

2006-01-01

149

Nitrous oxide in the Changjiang (Yangtze River) Estuary and its adjacent marine area: riverine input, sediment release and atmospheric fluxes  

Directory of Open Access Journals (Sweden)

Full Text Available Dissolved nitrous oxide (N2O) was measured in the waters of the Changjiang (Yangtze River) Estuary and its adjacent marine area during five surveys covering the period of 2002–2006. Dissolved N2O concentrations ranged from 6.04 to 21.3 nM, and indicate seasonal variations with high values occurring in summer and spring. Dissolved riverine N2O was observed monthly at station Xuliujing of the Changjiang, and ranged from 12.4 to 33.3 nM with an average of 20.8±7.8 nM. The average annual input of N2O from the Changjiang to the estuary and its adjacent area was estimated to be 15.8×106 mol/yr. N2O emission rates from the sediments of the Changjiang Estuary in spring ranged from ?1.88 to 2.02 ?mol m?2 d?1, which suggest that sediment can act as either a source or a sink of N2O in the Changjiang Estuary. The annual sea to air N2O fluxes from the Changjiang Estuary were estimated to be 6.8±3.7, 13.3±7.2 and 14.9±8.3 ?mol m?2 d?1 using LM86, W92 and RC01 relationships, respectively. The annual sea to air N2O fluxes from the adjacent marine area were estimated to be 8.5±7.8, 15.3±13.5 and 17.4±15.7 ?mol m?2 d?1 using LM86, W92 and RC01 relationship, respectively. Hence the Changjiang Estuary and its adjacent marine area is a net source of atmospheric N2O.

G.-L. Zhang; J. Zhang; S.-M. Liu; J.-L. Ren; Y.-C. Zhao

2010-01-01

150

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

151

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

152

Nested-grid models for simulating saltwater intrusion in the Pearl River Estuary  

Science.gov (United States)

The primary tool for my research is a nested grid implementation using the Regional Ocean Modeling System (ROMS) composed of basin-scale models that span the tropical Pacific and high-resolution model nests of the South China Sea (SCS)-Northern South China Sea (NSCS)-Pearl River Estuary(PRE). The inner nest resolutions will be chosen so that both geometric (complex coastlines and bathymetry) and dynamical features (such as baroclinic tides, submesoscale eddies and nonlinear estuarine current) are resolved. Three nested-grid models were set up and one-way offline. The outer model (L0) is used to simulate climatological circulation in SCS at approximate 15km resolution. The intermediate model (L1) is at 5km resolution and covers the continental shelf and PRE in the NSCS. The inner model (L2) is at averaged 1km resolution and reproduces the hydrological process by using the realistic forcing in the winter of 2007. The model results of saltwater intrusion and salt transport in the PRE will be presented.

Zhou, W.; Wang, D.

2010-12-01

153

Remotely sensed assessment of water quality levels in the Pearl River Estuary, China.  

UK PubMed Central (United Kingdom)

In this paper, a method of assessing water quality from satellite data is introduced. The composite pollution index (CPI) was calculated from measured chemical oxygen demand (COD) and nutrient concentration. The relationships between CPI and 240 band combinations of SeaWiFS water-leaving radiance were analyzed and the optimal band combination for estimating CPI was chosen from the 240 band combinations. An algorithm for retrieval of CPI was developed using the optimal band combination, (L(443)xL(510))/(L(412)+L(490)). The CPI was estimated from atmospherically corrected SeaWiFS data by employing the algorithm. Furthermore, the CPI value range for each water quality level was determined based on data obtained from 850 samples taken in the Pearl River Estuary. The remotely sensed CPIs were then transferred to water quality levels and appropriate maps were derived. The remotely sensed water quality level maps displayed a similar distribution of levels based on in situ investigation issued by the State Ocean Administration, China. This study demonstrates that remote sensing can play an important role in water quality assessment.

Chen C; Tang S; Pan Z; Zhan H; Larson M; Jönsson L

2007-08-01

154

Variation in fecal pollution indicators through tidal cycles in the Fraser River estuary  

Energy Technology Data Exchange (ETDEWEB)

Daily fluctuations in fecal pollution indicators in the Fraser River estuary were examined by sampling through 24 h at four sites; water levels, currents, and salinities were observed simultaneously. Fecal coliforms were measured on shipboard using the membrane filter technique, and coprostanol and cholesterol were extracted using hexane and analyzed by gas chromatography. Maximum concentrations of fecal sterols and coliforms occurred after high tide at the station upstream of major sewage outfalls and on the ebb or at low tide at the stations downstream of major sewage outfalls. Fecal coliform counts were highly correlated with coprostanol and cholesterol levels at sites near sewage treatment plants. Coprostanol was highly correlated with cholesterol except where concentrations approached detection limits. In receiving waters, fecal coliform counts but not sterol concentrations were reduced by chlorination of sewage treatment plant effluents during the summer months. Researchers concluded that, dependent on the objectives of a future monitoring program, samples should be collected either randomly in time such that the seasonal or annual mean includes tidal variability or systematically during the ebb tide to assess contributions to bathing beaches and shellfish harvesting areas. Fecal sterols deserve consideration as potentials indicators of fecal contamination from chlorinated sewage effluents.

Churchland, L.M.; Kan, G.; Ages, A.

1982-02-01

155

Methane (CH4) emission from a tidal marsh in the Min River estuary, southeast China.  

UK PubMed Central (United Kingdom)

The total methane emission to the atmosphere and hydrosphere, and its seasonal variation, were estimated using an enclosed static chamber technique from a tidal marshes dominated by Phragmites australis (common reed) in the Min River estuary, southeast China. Measurements were taken at three tidal stages (before flood, during the flooding and ebbing process, and after ebb). Potential rates of methane production from the marsh sediment layers were also measured using an incubation technique. This P. australis tidal marsh was a net methane source, emitting 32.59 and 6.87 g CH(4) x m(-2) x yr(-1) to the atmosphere and hydrosphere, respectively. There was considerable monthly variation with emissions greater before flood in some months, whereas at other months emission was greater after ebb. The average methane fluxes were 5.13, 5.06 and 4.74 mg CH(4) m(-2) h(-1) before flood, during flooding and ebbing, and after ebb, respectively. Emissions to the tidewater and the atmosphere during the flooding and ebbing process were 2.98 and 2.08 mg CH(4) m(-2) h(-1),respectively. Sediment methane production potential (0-40 cm depth) ranged from 0.028-0.123 micro g CH(4) x g(-1) x d(-1), with the greatest production was in the surface soil. Methane fluxes had a significant correlation with atmospheric, sediment temperature and above ground biomass. The implications of these data for global warming are discussed briefly.

Tong C; Wang WQ; Zeng CS; Marrs R

2010-01-01

156

Lower Columbia River and Estuary Ecosystem Restoration Program Reference Site Study: 2011 Restoration Analysis - FINAL REPORT  

Energy Technology Data Exchange (ETDEWEB)

The Reference Site (RS) study is part of the research, monitoring, and evaluation (RME) effort developed by the Action Agencies (Bonneville Power Administration [BPA], U.S. Army Corps of Engineers, Portland District [USACE], and U.S. Bureau of Reclamation) in response to Federal Columbia River Power System (FCRPS) Biological Opinions (BiOp). While the RS study was initiated in 2007, data have been collected at relatively undisturbed reference wetland sites in the LCRE by PNNL and collaborators since 2005. These data on habitat structural metrics were previously summarized to provide baseline characterization of 51 wetlands throughout the estuarine and tidal freshwater portions of the 235-km LCRE; however, further analysis of these data has been limited. Therefore, in 2011, we conducted additional analyses of existing field data previously collected for the Columbia Estuary Ecosystem Restoration Program (CEERP) - including data collected by PNNL and others - to help inform the multi-agency restoration planning and ecosystem management work underway in the LCRE.

Borde, Amy B.; Cullinan, Valerie I.; Diefenderfer, Heida L.; Thom, Ronald M.; Kaufmann, Ronald M.; Zimmerman, Shon A.; Sagar, Jina; Buenau, Kate E.; Corbett, C.

2012-05-31

157

Beryllium-7 atmospheric deposition and sediment inventories in the Neponset River estuary, Massachusetts, USA.  

UK PubMed Central (United Kingdom)

Measured monthly atmospheric depositional fluxes of cosmogenically produced (7)Be ranged from 1 to 67 mBq/cm(2) in Boston, Massachusetts between September 2000 and August 2007. These fluxes exhibited seasonality and supported a decay-corrected (7)Be atmospheric depositional running inventory that ranged from 36 to 144 mBq/cm(2). Annual (7)Be deposition exhibited an increasing trend that may reflect a general decrease in solar activity and a general increase in precipitation over the 7-year sampling period. To investigate short-term sediment dynamics and accumulation patterns in the Neponset River estuary, we collected six sediment cores in July 2006 and measured (7)Be sediment inventories ranging from 48 to 546 mBq/cm(2) Comparisons of these sediment inventories with the (7)Be running inventory from atmospheric deposition (101 mBq/cm(2)) at the time of core collection indicated a large degree of spatial heterogeneity in sediment accumulation patterns and its potential use as a tool for assessing the impacts of environmental restoration activities in estuarine environments.

Zhu J; Olsen CR

2009-02-01

158

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

UK PubMed Central (United Kingdom)

We measured dissolved N(2)O, CH(4), O(2), NH(4)(+), NO(3)(-) and NO(2)(-) on 7 transects along the polluted Adyar River-estuary, SE India and estimated N(2)O and CH(4) emissions using a gas exchange relation and a floating chamber. High NO(2)(-) implied some nitrification of a large anthropogenic NH(4)(+) pool. In the lower catchment CH(4) was maximal (6.3+/-4.3 x 10(4)nM), exceeding the ebullition threshold, whereas strong undersaturation of N(2)O and O(2) implied intense denitrification. Emissions fluxes for the whole Adyar system approximately 2.5 x 10(8) g CH(4)yr(-1) and approximately 2.4 x 10(6)gN(2)O yr(-1) estimated with a gas exchange relation and approximately 2 x 10(9) g CH(4)yr(-1) derived with a floating chamber illustrate the importance of CH(4) ebullition. An equivalent CO(2) flux approximately 1-10 x 10(10)gy r(-1) derived using global warming potentials is equivalent to total Chennai motor vehicle CO(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; Barnes J; Ramesh R; Purvaja R; Upstill-Goddard RC

2008-12-01

159

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

Science.gov (United States)

We measured dissolved N(2)O, CH(4), O(2), NH(4)(+), NO(3)(-) and NO(2)(-) on 7 transects along the polluted Adyar River-estuary, SE India and estimated N(2)O and CH(4) emissions using a gas exchange relation and a floating chamber. High NO(2)(-) implied some nitrification of a large anthropogenic NH(4)(+) pool. In the lower catchment CH(4) was maximal (6.3+/-4.3 x 10(4)nM), exceeding the ebullition threshold, whereas strong undersaturation of N(2)O and O(2) implied intense denitrification. Emissions fluxes for the whole Adyar system approximately 2.5 x 10(8) g CH(4)yr(-1) and approximately 2.4 x 10(6)gN(2)O yr(-1) estimated with a gas exchange relation and approximately 2 x 10(9) g CH(4)yr(-1) derived with a floating chamber illustrate the importance of CH(4) ebullition. An equivalent CO(2) flux approximately 1-10 x 10(10)gy r(-1) derived using global warming potentials is equivalent to total Chennai motor vehicle CO(2) emissions in one month. Studies such as this may inform more effective waste management and future compliance with international emissions agreements. PMID:18814890

Nirmal Rajkumar, A; Barnes, J; Ramesh, R; Purvaja, R; Upstill-Goddard, R C

2008-09-23

160

Mercury distribution, speciation and bioavailability in sediments from the Pearl River Estuary, Southern China.  

UK PubMed Central (United Kingdom)

Surface sediments and sediment cores collected from the Pearl River Estuary (PRE) were analyzed for total mercury (THg) concentrations and speciation using a sequential extraction method. The mobility of Hg in sediments was also assessed using a series of single extraction methods. The surface sediments from the PRE showed slightly elevated levels of Hg, with concentrations ranging from 109 to 453 ng/g. The vertical profile of THg in sediment cores indicated an accelerated input of Hg over the past decades. The organo-chelated and strong-complexed Hg species were the dominant Hg species in the sediments, while the more mobile phases of Hg made up less than 0.5% of THg. Less than 10% of the Hg in the sediments was extracted by single extraction, depending on the extractant employed. Significant relationships were found between the total organic carbon and THg, geochemical speciation, and extractability, indicating the important role of organic matter in controlling the distribution, mobility, and bioavailability of Hg in sediments.

Yu X; Li H; Pan K; Yan Y; Wang WX

2012-08-01

 
 
 
 
161

[Phytoplankton assemblage in Yangtze River estuary and its adjacent waters in winter time].  

UK PubMed Central (United Kingdom)

Water samples were collected from Yangtze River Estuary and its adjacent waters in 28th February-10th March, 2005, and the species composition of phytoplankton was analyzed by Utermöhl method. A total of 130 taxa (including 25 uncertain species) which belong to 67 genera of 5 phyla were identified. The phytoplankton community was mainly composed of Bacillariophyta, followed by Dinophyta. There were also a few species belonging to Chrysophyceae, Cyanophyceae and Chlorophyceae. The dominant species were Paralia sulcata, Skeletonema costatum, Thalassiosira rotula, Bleakeleya notata, Coscinodiscus radiatus and Thalassiosira excentrica. The cell abundance of phytoplankton ranged from 0.1 to 90.0 cells x ml(-1), with an average of 10.1 cells x ml(-1). Horizontally, the cell abundance was relatively high in inshore and low in offshore; while vertically, it was high in surface water and decreased slightly with increasing water depth. The cell abundance and chl a concentration of phytoplankton positively correlated with the concentrations of nitrate, nitrite, ammonium, phosphate and silicate in water, but negatively correlated with water salinity. The Shannon-Wiener diversity index and Pielou evenness index were higher in the center of survey area but lower in northeast part and inshore area.

He Q; Sun J; Luan QS; Song SQ; Shen ZL; Wang D

2007-11-01

162

[Phytoplankton assemblage in Yangtze River estuary and its adjacent waters in winter time].  

Science.gov (United States)

Water samples were collected from Yangtze River Estuary and its adjacent waters in 28th February-10th March, 2005, and the species composition of phytoplankton was analyzed by Utermöhl method. A total of 130 taxa (including 25 uncertain species) which belong to 67 genera of 5 phyla were identified. The phytoplankton community was mainly composed of Bacillariophyta, followed by Dinophyta. There were also a few species belonging to Chrysophyceae, Cyanophyceae and Chlorophyceae. The dominant species were Paralia sulcata, Skeletonema costatum, Thalassiosira rotula, Bleakeleya notata, Coscinodiscus radiatus and Thalassiosira excentrica. The cell abundance of phytoplankton ranged from 0.1 to 90.0 cells x ml(-1), with an average of 10.1 cells x ml(-1). Horizontally, the cell abundance was relatively high in inshore and low in offshore; while vertically, it was high in surface water and decreased slightly with increasing water depth. The cell abundance and chl a concentration of phytoplankton positively correlated with the concentrations of nitrate, nitrite, ammonium, phosphate and silicate in water, but negatively correlated with water salinity. The Shannon-Wiener diversity index and Pielou evenness index were higher in the center of survey area but lower in northeast part and inshore area. PMID:18260464

He, Qing; Sun, Jun; Luan, Qing-shan; Song, Shu-qun; Shen, Zhi-liang; Wang, Dan

2007-11-01

163

Speciation of selected heavy metals geochemistry in surface sediments from Tirumalairajan river estuary, east coast of India.  

UK PubMed Central (United Kingdom)

Surface sediment samples from the Tirumalairajan river estuary were studied for grain size pattern, organic matter, and heavy metals (Fe, Mn, Zn, and Pb) using the sequential and bulk metal extraction methods to evaluate metal behavior. Ten surface sediment samples were collected during the monsoon and summer seasons of the year 2009. The observed orders of concentrations of heavy metals in the sediments were as follows: Fe?>?Mn?>?Zn?>?Pb. The results obtained from sequential extraction showed that, among the metals studied, a larger portion of the metals were associated with the residual phase, although they are available in other fractions. The low concentration of metals available in bioavailable phases indicated that the sediments of Tirumalairajan river estuary were relatively unpolluted. Correlation analysis was also carried out to understand the associations of metals in different phases with sand, silt, clay, and organic matter. To understand the risk of heavy metals to sediment-dwelling organisms, the data were compared with risk assessment code and sediment quality values using the screening quick reference table. The main source of metals to the estuary is from the irrigation field and its associated activities in the study area.

Venkatramanan S; Ramkumar T; Anithamary I; Jonathan MP

2013-08-01

164

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; P. L. M. Cook; I. Teakle; M. R. Hipsey

2013-01-01

165

Shipworm (Bankia setacea) activity within the Port of Everett and the Snohomish River Estuary: defining the problem.  

UK PubMed Central (United Kingdom)

Log rafts stored in the Snohomish River estuary, a facility maintained by the Port of Everett, Washington, were infested by shipworms (Bankia setacea) during 1987. Studies were done to identify when the log rafts were infested, establish relationships between estuarine conditions and shipworm attack, and examine the potential for future infestations. The first two objectives were studied by retracing in time and place the patterns of log raft movements and by developing a salt water intrusion model. The last objective was met by developing a river flow predictive model. The timing of log refit movements and storage during periods of low river flow and high B. setacea larval settlement were responsible for the shipworm infestations. In particular, uncommonly low river flow in 1987 created estuarine salt water conditions favorable for shipworm activity in the normally safe log storage areas. If the late summer trend in freshwater flow reduction observed since 1963 continues, then by the year 2000, the average monthly flow during the period of maximum shipworm settlement will drop by about a third from current flow levels. Under these conditions, saltwater intrusion and B. setacea damage will become more common within the estuary.

Gara RI; Greulich FE

1995-04-01

166

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

2011-01-01

167

Simulation of potential oyster density with variable freshwater inflow (1965-2000) to the caloosahatchee river estuary, southwest Florida, USA.  

UK PubMed Central (United Kingdom)

Oyster beds are disappearing worldwide through a combination of over-harvesting, diseases, and salinity alterations in the coastal zone. Sensitivity of oysters to variable discharge and salinity is particularly acute in small sub-tropical estuaries subject to regulated freshwater releases. South Florida has sub-tropical estuaries where watershed flood control sometimes results in excessive freshwater inflow to estuaries during the wet season (May-Oct) and reduced discharge and increased salinities in the dry season (Nov-Apr). The potential to reserve freshwater accumulated during the wet season could offer the capacity to regulate freshwater at different temporal scales, thus optimizing salinity conditions for estuarine biota. The goal of this study was to use simulation modeling to explore the effects of freshwater inflows and salinity on adult oyster survival in the Caloosahatchee River Estuary (CRE) in southwest Florida. Water managers derived three different freshwater inflow scenarios for the CRE based on historical and modified watershed attributes for the time period of 1965-2000. Three different salinity time series were generated from the inflow scenarios at each of three sites in the lower CRE and used to conduct nine different oyster simulations. Overall, the predicted densities of adult oysters in the upstream site were 3-4 times greater in seasons that experienced reduced freshwater inflow (e.g., increased salinity) with oyster density in the lower estuary much less influenced by the inflows. Potential storage of freshwater reduced the frequency of extreme flows in the wet season and helped to maintain minimum inflow in the dry season near the estuarine mouth. Analyses of inflows indicated that discharges ranging from 0 to 1,500 cfs could promote favorable salinities of 10-25 in the lower CRE depending on wet versus dry season climatic conditions. This range of inflows is similar to that derived in other studies of the CRE and emphasizes the value of simulation models to help prescribe freshwater releases which benefit estuarine biota.

Buzzelli C; Doering PH; Wan Y; Gorman P; Volety A

2013-10-01

168

Simulation of Potential Oyster Density with Variable Freshwater Inflow (1965-2000) to the Caloosahatchee River Estuary, Southwest Florida, USA  

Science.gov (United States)

Oyster beds are disappearing worldwide through a combination of over-harvesting, diseases, and salinity alterations in the coastal zone. Sensitivity of oysters to variable discharge and salinity is particularly acute in small sub-tropical estuaries subject to regulated freshwater releases. South Florida has sub-tropical estuaries where watershed flood control sometimes results in excessive freshwater inflow to estuaries during the wet season (May-Oct) and reduced discharge and increased salinities in the dry season (Nov-Apr). The potential to reserve freshwater accumulated during the wet season could offer the capacity to regulate freshwater at different temporal scales, thus optimizing salinity conditions for estuarine biota. The goal of this study was to use simulation modeling to explore the effects of freshwater inflows and salinity on adult oyster survival in the Caloosahatchee River Estuary (CRE) in southwest Florida. Water managers derived three different freshwater inflow scenarios for the CRE based on historical and modified watershed attributes for the time period of 1965-2000. Three different salinity time series were generated from the inflow scenarios at each of three sites in the lower CRE and used to conduct nine different oyster simulations. Overall, the predicted densities of adult oysters in the upstream site were 3-4 times greater in seasons that experienced reduced freshwater inflow (e.g., increased salinity) with oyster density in the lower estuary much less influenced by the inflows. Potential storage of freshwater reduced the frequency of extreme flows in the wet season and helped to maintain minimum inflow in the dry season near the estuarine mouth. Analyses of inflows indicated that discharges ranging from 0 to 1,500 cfs could promote favorable salinities of 10-25 in the lower CRE depending on wet versus dry season climatic conditions. This range of inflows is similar to that derived in other studies of the CRE and emphasizes the value of simulation models to help prescribe freshwater releases which benefit estuarine biota.

Buzzelli, Christopher; Doering, Peter H.; Wan, Yongshan; Gorman, Patricia; Volety, Aswani

2013-10-01

169

Recent sedimentary history of anthropogenic impacts on the Culiacan River Estuary, northwestern Mexico: geochemical evidence from organic matter and nutrients.  

UK PubMed Central (United Kingdom)

210Pb geochronology and sediment profiles of carbon, phosphorus and nitrogen were used to study time dependent changes in nutrients fluxes to Culiacan River Estuary. Results indicate that the release of urban sewage and agriculture wastes transported through Culiacan River has produced historically increased carbon, phosphorus and nitrogen fluxes to the study area. C:N:P elemental ratios showed that increments in the nutrients input begins simultaneously for C, N and P in 1948 with the clearing of the catchment for agriculture; although excess of nutrients input increased most importantly around the 1970s to roughly follow the rapidly growing population of Culiacan City. C/N ratios, delta13C and delta15N suggested that nutrient enrichment is mostly influenced by sewage delivered through Culiacan River.

Ruiz-Fernández AC; Hillaire-Marcel C; Ghaleb B; Soto-Jiménez M; Páez-Osuna F

2002-01-01

170

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‰).

Li-Gang Fang; Shui-Sen Chen; Dong Li; Hong-Li Li

2009-01-01

171

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

Scientific Electronic Library Online (English)

Full Text Available 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 (more) 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). Thirty 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 v (more) alue 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.

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

2012-12-01

172

Heavy metal and Pb isotopic compositions of aquatic organisms in the Pearl River Estuary, South China  

International Nuclear Information System (INIS)

The accumulation of trace metals in aquatic organisms may lead to serious health problems through the food chain. The present research project aims to study the accumulation and potential sources of trace metals in aquatic organisms of the Pearl River Estuary (PRE). Four groups of aquatic organisms, including fish, crab, shrimp, and shellfish, were collected in the PRE for trace metal and Pb isotopic analyses. The trace metal concentrations in the aquatic organism samples ranged from 0.01 to 2.10 mg/kg Cd, 0.02 to 4.33 mg/kg Co, 0.08 to 4.27 mg/kg Cr, 0.15 to 77.8 mg/kg Cu, 0.17 to 31.0 mg/kg Ni, 0.04 to 30.7 mg/kg Pb, and 8.78 to 86.3 mg/kg Zn (wet weight). High concentrations of Cd were found in crab, shrimp and shellfish samples, while high concentration of Pb was found in fish. In comparison with the baseline reference values in other parts of the world, fish in the PRE had the highest elevated trace metals. The results of Pb isotopic compositions indicated that the bioaccumulation of Pb in fish come from a wide variety of food sources and/or exposure pathways, particularly the anthropogenic inputs. - Relative high concentrations of Cd were found in crab, shrimp and shellfish samples while high concentration of Pb was found in fish, particularly from the anthropogenic inputs.

2005-01-01

173

Heavy metal and Pb isotopic compositions of aquatic organisms in the Pearl River Estuary, South China  

Energy Technology Data Exchange (ETDEWEB)

The accumulation of trace metals in aquatic organisms may lead to serious health problems through the food chain. The present research project aims to study the accumulation and potential sources of trace metals in aquatic organisms of the Pearl River Estuary (PRE). Four groups of aquatic organisms, including fish, crab, shrimp, and shellfish, were collected in the PRE for trace metal and Pb isotopic analyses. The trace metal concentrations in the aquatic organism samples ranged from 0.01 to 2.10 mg/kg Cd, 0.02 to 4.33 mg/kg Co, 0.08 to 4.27 mg/kg Cr, 0.15 to 77.8 mg/kg Cu, 0.17 to 31.0 mg/kg Ni, 0.04 to 30.7 mg/kg Pb, and 8.78 to 86.3 mg/kg Zn (wet weight). High concentrations of Cd were found in crab, shrimp and shellfish samples, while high concentration of Pb was found in fish. In comparison with the baseline reference values in other parts of the world, fish in the PRE had the highest elevated trace metals. The results of Pb isotopic compositions indicated that the bioaccumulation of Pb in fish come from a wide variety of food sources and/or exposure pathways, particularly the anthropogenic inputs. - Relative high concentrations of Cd were found in crab, shrimp and shellfish samples while high concentration of Pb was found in fish, particularly from the anthropogenic inputs.

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

2005-12-15

174

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

175

Dynamic sedimentary environments of an Arctic glacier-fed river estuary (Adventfjorden, Svalbard). II: Meio- and macrobenthic fauna  

Science.gov (United States)

The paper examines the meio- and macrobenthic responses to physical disturbance and sediment instabilities in a small Arctic glacier-fed river estuary. Zajiczkowski and W?odarska-Kowalczuk [Zajiczkowski, M., W?odarska-Kowalczuk, M., 2007. Dynamic sedimentary environments of Arctic glacier-fed river estuary (Adventfjorden, Svalbard). I. Flux, deposition, and sediment dynamics. Estuarine, Coastal and Shelf Science 74(1 2), 285 296] distinguished three zones in Adventfjorden (west Spitsbergen) estuary: the tidal flat, the slope (high sedimentation, frequent sediment slides), the central basin (low sedimentation, stable sediments). The numbers of individuals and species of meio- and macrofauna were very low on the tidal flat. The total densities of meio- and macrofauna were significantly lower on the slope of the glacio-fluvial delta than in the central basin. Only the macrofauna responded to sediment instabilities on the slope by a significant decrease in total biomass. Nematodes inhabiting the slope sediments were larger than those in the central basin, although there was no significant difference in the size of harpacticoids in the two zones. The frequently disturbed, resuspended, and redeposited slope sediments were colonized by the opportunistic polychaete Capitella capitata agg. and by the high sedimentation resistant polychaetes Chaetozone setosa agg. and Cossura longocirrata. Tube-dwelling, sedentary, or suspension-feeding fauna only occurred at the central basin stations. The species richness and ratio of surface-dwelling to burrowing deposit-feeders in the macrobenthic communities decreased towards the river mouths. The differences in the taxonomic composition of communities inhabiting the sediments of the slope and the central basin were less pronounced in meiofauna (studied at a higher taxonomic level) than in the macrofauna (identified to the species level). Nevertheless, the differences were significant for both benthic compartments (ANOSIM test, P < 0.05). The simultaneous survey of meio- and macrobenthic communities in an Arctic glacier-fed river estuary shows that both benthic compartments are sensitive to sediment instabilities and physical disturbance caused by high sedimentation and frequent sediment gravity flows.

W?odarska-Kowalczuk, Maria; Szymelfenig, Maria; Zajiczkowski, Marek

2007-08-01

176

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; Luiz Loureiro Fernandes

2006-01-01

177

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 Abstract in portuguese 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 temperatur (more) a. 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 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 obtaine (more) d. 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.

Sterza, José Mauro; Fernandes, Luiz Loureiro

2006-12-01

178

Distribution of submerged aquatic vegetation in the St. Louis River estuary: Maps and models (Presentation)  

Science.gov (United States)

SAV provides the biophysical basis for several ecosystem services in Great Lakes estuaries including rearing and adult habitat for commercially and recreationally important fishes, foraging habit for waterfowl, and nutrient retention. Understanding sources of variation in SAV in ...

179

Surficial sediment distribution and the associated net sediment transport pattern retain-->in the Pearl River Estuary, South China  

Science.gov (United States)

Spatial variations in grain-size parameters contain information on sediment transport patterns. Therefore, in this study, 106 surficial sediment samples taken from the Pearl River Estuary (PRE), South China, were analyzed, to better understand the net sediment transport pattern in this region. The PRE is an area of fine-grained sediment and shows muddy patches with relatively coarse sediment in the north. The sorting coefficient of surficial sediment over the whole estuary is higher than 2, indicating a very poor sorting in this region. The relationship between the sand, silt and clay contents of the sediments was analyzed by a log-ratio analysis, and it was indicated that the selective deposition is a non-linear function of the sediment mixture composition. The net sediment transport pathways indicate four distinct characteristics of sediment transport over the PRE. The sediment is transported obviously southeastward in the upper part of the estuary due to the relatively stronger fluvial dynamics and northwestward in the lower part, due to the stronger tidal dynamics. However, in the central part of the PRE, the sediment transport vectors display a clockwise rotation trend and net deposition is taking place, as indicated by the convergence of the grain size trend. The trend vectors show that some of the sedimentary material is supplied from upper and lower parts of the estuary to this depocenter. This result is consistent with the residual current circulation pattern near Neilingding Island. The patterns of sediment transport reveal directions with the main areas of deposition and possible dispersal patterns in the PRE.

Zhang, Wei; Zheng, Jinhai; Xiaomei, Ji; Hoitink, A. J. F.; van der Vegt, M.; Zhu, Yuliang

2013-07-01

180

Perfluorooctane sulfonate (PFOS) distribution and effect factors in the water and sediment of the Yellow River Estuary, China.  

UK PubMed Central (United Kingdom)

The distribution of perfluorooctane sulfonate (PFOS) was investigated in a total of 15 water and sediment samples from the Yellow River Estuary, China in April 2011. The results indicated that the concentrations of PFOS in the water and sediment samples averaged 157.5 ng/L and 198.8 ng/g and ranged from 82.30 to 261.8 ng/L and 75.48 to 457.0 ng/g, respectively. The concentrations of PFOS in the sediment column increased from 45.32 to 379.98 ng/g with the decrease of the sampling depth, which showed that the increased PFOS pollution in the sediment appeared in this region in over recent years. The distribution coefficient (K d) of PFOS between water and sediment linearly increased from 0.37 to 4.80 L/g as the salinity (S‰) increased from 0.18 to 4.47. Correlation analysis revealed that K d was significantly and positively correlated to the contents of total organic carbon and clay of the sediment, and salinity. Therefore, salinity was an important parameter in controlling the sediment-water interactions and the fate or transport of PFOS in the aquatic environment. The results of this study showed that the estuary was an important sink for PFOS and suggested that PFOS might be carried with the river water and transported for long distances before it reached to the sea and largely scavenged to the sediment in the estuaries due to the change in salinity.

Wang S; Wang H; Deng W

2013-10-01

 
 
 
 
181

Impact of flood events on macrobenthic community structure on an intertidal flat developing in the Ohta River Estuary.  

UK PubMed Central (United Kingdom)

We investigated the effects of river floods on the macrobenthic community of the intertidal flat in the Ohta River Estuary, Japan, from 2005 to 2010. Sediment erosion by flood events ranged from about 2-3 cm to 12 cm, and the salinity dropped to 0‰ even during low-intensity flood events. Cluster analysis of the macrobenthic population showed that the community structure was controlled by the physical disturbance, decreased salinity, or both. The opportunistic polychaete Capitella sp. was the most dominant species in all clusters, and populations of the long-lived polychaete Ceratonereis erythraeensis increased in years with stable flow and almost disappeared in years with intense flooding. The bivalve Musculista senhousia was also an important opportunistic species that formed mats in summer of the stable years and influenced the structure of the macrobenthic community. Our results demonstrate the substantial effects of flood events on the macrobenthic community structure.

Nishijima W; Nakano Y; Nakai S; Okuda T; Imai T; Okada M

2013-09-01

182

Impact of flood events on macrobenthic community structure on an intertidal flat developing in the Ohta River Estuary.  

Science.gov (United States)

We investigated the effects of river floods on the macrobenthic community of the intertidal flat in the Ohta River Estuary, Japan, from 2005 to 2010. Sediment erosion by flood events ranged from about 2-3cm to 12cm, and the salinity dropped to 0‰ even during low-intensity flood events. Cluster analysis of the macrobenthic population showed that the community structure was controlled by the physical disturbance, decreased salinity, or both. The opportunistic polychaete Capitella sp. was the most dominant species in all clusters, and populations of the long-lived polychaete Ceratonereis erythraeensis increased in years with stable flow and almost disappeared in years with intense flooding. The bivalve Musculista senhousia was also an important opportunistic species that formed mats in summer of the stable years and influenced the structure of the macrobenthic community. Our results demonstrate the substantial effects of flood events on the macrobenthic community structure. PMID:23831317

Nishijima, Wataru; Nakano, Yoichi; Nakai, Satoshi; Okuda, Tetsuji; Imai, Tsuyoshi; Okada, Mitsumasa

2013-07-04

183

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.

1000-01-00

184

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

Energy Technology Data Exchange (ETDEWEB)

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 {sup 210}Pb 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.

Shi Jianbo [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Ip, Carman C.M. [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Zhang Gan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Jiang Guibin [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Li Xiangdong, E-mail: cexdli@polyu.edu.h [Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

2010-05-15

185

Distribution, sources, and ecological risks of organochlorine pesticides in surface sediments from the Yellow River Estuary, China.  

UK PubMed Central (United Kingdom)

Thirty-four surface sediment samples were analyzed for organochlorine pesticides (OCPs), in order to provide information on levels, distribution and sources of these compounds in the Yellow River Estuary, China. The levels of the organochlorine pesticides in samples were detected by the technique of soxhlet extraction followed by analysis by gas chromatography (GC) coupled with a mass selective detector. Total concentrations of OCPs ranged widely from 0.06 to 53.4 ng g(-1), with a mean value of 44.84 ng g(-1), at the mid level of pesticide concentrations compared to those reported in other regions worldwide. HCHs were the predominant species in the study area. The ratios of ?-HCH/?-HCH indicated that the technical HCH contamination was mainly due to a recent input of lindane in upper reach of Yellow River Estuary. The ratios of (DDD + DDE)/DDTs and DDD/DDE suggested that DDTs in sediments came mainly from the degradation of historical DDT in the environment, and DDT could be much easier to degrade into DDD under anaerobic conditions. Principal component analysis (PCA) could conclude that most of the OCPs came from early input and historical degradation products in the study area. Based on the sediment quality guidelines, ?-HCH and p'p-DDE would be of more concern for the ecotoxicological risk in this study area.

Da C; Liu G; Tang Q; Liu J

2013-10-01

186

Temporal and spatial distribution of red tide outbreaks in the Yangtze River Estuary and adjacent waters, China.  

UK PubMed Central (United Kingdom)

Between 1972 and 2009, evidence of red tide outbreaks in the Yangtze River Estuary and adjacent waters was collected. A geographic information system (GIS) was used to analyze the temporal and spatial distribution of these red tides, and it was subsequently used to map the distribution of these events. The results show that the following findings. (1) There were three red tide-prone areas: outside the Yangtze River Estuary and the eastern coast of Sheshan, the Huaniaoshan-Shengshan-Gouqi waters, and the Zhoushan areas and eastern coast of Zhujiajian. In these areas, red tides occurred 174 total times, 25 of which were larger than 1000 km(2) in areal extent. After 2000, the frequency of red tide outbreaks increased significantly. (2) During the months of May and June, the red tide occurrence in these areas was 51% and 20%, respectively. (3) Outbreaks of the dominant red tide plankton species Prorocentrum dong-haiense, Skeletonema costatum, Prorocentrum dantatum, and Noctiluca scientillan occurred 38, 35, 15, and 10 times, respectively, during the study interval.

Liu L; Zhou J; Zheng B; Cai W; Lin K; Tang J

2013-07-01

187

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2004  

Energy Technology Data Exchange (ETDEWEB)

The restoration of wetland salmon habitat in the tidal portion of the Columbia River is occurring at an accelerating pace and is anticipated to improve habitat quality and effect hydrological reconnection between existing and restored habitats. Currently multiple groups are applying a variety of restoration strategies in an attempt to emulate historic estuarine processes. However, the region lacks both a standardized means of evaluating the effectiveness of individual projects as well as methods for determining the cumulative effects of all restoration projects on a regional scale. This project is working to establish a framework to evaluate individual and cumulative ecosystem responses to restoration activities in order to validate the effectiveness of habitat restoration activities designed to benefit salmon through improvements to habitat quality and habitat opportunity (i.e. access) in the Columbia River from Bonneville Dam to the ocean. The review and synthesis of approaches to measure the cumulative effects of multiple restoration projects focused on defining methods and metrics of relevance to the CRE, and, in particular, juvenile salmon use of this system. An extensive literature review found no previous study assessing the cumulative effects of multiple restoration projects on the fundamental processes and functions of a large estuarine system, although studies are underway in other large land-margin ecosystems including the Florida Everglades and the Louisiana coastal wetlands. Literature from a variety of scientific disciplines was consulted to identify the ways that effects can accumulate (e.g., delayed effects, cross-boundary effects, compounding effects, indirect effects, triggers and thresholds) as well as standard and innovative tools and methods utilized in cumulative effects analyses: conceptual models, matrices, checklists, modeling, trends analysis, geographic information systems, carrying capacity analysis, and ecosystem analysis. Potential indicators for detecting a signal in the estuarine system resulting from the multiple projects were also reviewed, i.e. organic matter production, nutrient cycling, sedimentation, food webs, biodiversity, salmon habitat usage, habitat opportunity, and allometry. In subsequent work, this information will be used to calculate the over net effect on the ecosystem. To evaluate the effectiveness of habitat restoration actions in the lower Columbia River and estuary, a priority of this study has been to develop a set of minimum ecosystem monitoring protocols based on metrics important for the CRE. The metrics include a suite of physical measurements designed to evaluate changes in hydrological and topographic features, as well as biological metrics that will quantify vegetation and fish community structure. These basic measurements, intended to be conducted at all restoration sites in the CRE, will be used to (1) evaluate the effectiveness of various restoration procedures on target metrics, and (2) provide the data to determine the cumulative effects of many restoration projects on the overall system. A protocol manual is being developed for managers, professional researchers, and informed volunteers, and is intended to be a practical technical guide for the design and implementation of monitoring for the effects of restoration activities. The guidelines are intended to standardize the collection of data critical for analyzing the anticipated ecological change resulting from restoration treatments. Field studies in 2005 are planned to initiate the testing and evaluation of these monitoring metrics and protocols and initiate the evaluation of higher order metrics for cumulative effects.

Diefenderfer, Heida L.; Roegner, Curtis; Thom, Ronald M.; Dawley, Earl M.; Whiting, Allan H.; Johnson, Gary E.; Sobocinski, Kathryn L.; Anderson, Michael G.; Ebberts, Blaine

2005-12-15

188

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 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 (more) 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 o (more) f 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

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

2011-01-01

189

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

190

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...

191

Estuarine Landcover Along the Lower Columbia River Estuary Determined from Compact Ariborne Spectrographic Imager (CASI) Imagery, Technical Report 2003.  

Energy Technology Data Exchange (ETDEWEB)

Developing an understanding of the distribution and changes in estuarine and riparian habitats is critical to the management of biological resources in the lower Columbia River. In a recently completed comprehensive ecosystem protection and enhancement plan for the lower Columbia River Estuary (CRE), Jerrick (1999) identified habitat loss and modification as one of the key threats to the integrity of the CRE ecosystem. This management plan called for an inventory of habitats as key first step in the CRE long-term restoration effort. While previous studies have produced useful data sets depicting habitat cover types along portions of the lower CRE (Thomas, 1980; Thomas, 1983; Graves et al., 1995; NOAA, 1997; Allen, 1999), no single study has produced a description of the habitats for the entire CRE. Moreover, the previous studies differed in data sources and methodologies making it difficult to merge data or to make temporal comparisons. Therefore, the Lower Columbia River Estuary Partnership (Estuary Partnership) initiated a habitat cover mapping project in 2000. The goal of this project was to produce a data set depicting the current habitat cover types along the lower Columbia River, from its mouth to the Bonneville Dam, a distance of {approx}230-km (Fig. 1) using both established and emerging remote sensing techniques. For this project, we acquired two types of imagery, Landsat 7 ETM+ and Compact Airborne Spectrographic Imager (CASI). Landsat and CASI imagery differ in spatial and spectral resolution: the Landsat 7 ETM+ sensor collects reflectance data in seven spectral bands with a spatial resolution of 30-m and the CASI sensor collects reflectance data in 19 bands (in our study) with a spatial resolution of 1.5-m. We classified both sets of imagery and produced a spatially linked, hierarchical habitat data set for the entire CRE and its floodplain. Landsat 7 ETM+ classification results are presented in a separate report (Garono et al., 2003). This report presents classification results from analysis of the CASI imagery. Data sets produced for this project from both types of imagery fill a critical information gap by creating a current description of the condition and extent of estuarine habitat cover types along the lower Columbia River. Results from this study will be used by the Estuary Partnership and its cooperators to: (1) develop indicators of 'habitat health' and biological integrity; (2) develop definitions of 'critical salmonid habitat'; (3) identify and evaluate potential wetland conservation and restoration sites; (4) track exotic and invasive species; and (5) develop an understanding of how estuarine and riverine habitats have changed over the past 200 years. This study focuses on estuarine and riparian habitat cover types important to native species, particularly juvenile salmonids. This study is meant to provide support to the multiple efforts currently underway to recover 12 species of Columbia River salmonids identified as endangered or threatened under the Endangered Species Act.

Garono, Ralph; Robinson, Rob

2003-10-01

192

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; Yasushi Tamura; Masato Moteki; Hiroshi Kohno

2012-01-01

193

Natural heavy metal and metalloid concentrations in sediments of the Minho River estuary (Portugal): baseline values for environmental studies.  

UK PubMed Central (United Kingdom)

Forty-nine surface sediment samples from the Minho estuary sector between Tui and Caminha were analyzed for grain-size contents, Al, As, Cr, Cu, Hg, Li, Pb, Sn, and Zn concentrations. Selected heavy metal (Cu, Cr, Hg, and Zn) and metalloid (As and Sn) distributions were normalized against Al and Li with the main goal of compensating for natural grain-size variability and to separate natural from anthropogenic contributions, by using a combination of normalization techniques (definition of regional geochemical baselines (RGB) and determination of enrichment factors (EF)). Lead did not reveal a significant relationship with Al and Li. Aluminum explained more variance than Li for As, Cu, Hg, and Zn. Assuming the general non-impacted metal character of the Minho River estuary sediments, RGBs are defined for differentiating between natural and anthropogenic contributions. Based on RGB defined for each heavy metal/metalloid, the degree of enrichment is estimated through the determination of EF. Despite the relatively low total heavy metal and metalloid concentrations, the defined RGB identifies a set of samples characterized by presenting As, Cu, Cr, Hg, and Zn enrichments relatively to expected natural levels. Mercury is the element showing the highest level of enrichment relative to the baseline values being spread through all the study area. Tin present enrichments relatively to Al and or Li always lower than 1.5 suggesting natural contributions.

Mil-Homens M; Costa AM; Fonseca S; Trancoso MA; Lopes C; Serrano R; Sousa R

2013-07-01

194

Natural heavy metal and metalloid concentrations in sediments of the Minho River estuary (Portugal): baseline values for environmental studies.  

Science.gov (United States)

Forty-nine surface sediment samples from the Minho estuary sector between Tui and Caminha were analyzed for grain-size contents, Al, As, Cr, Cu, Hg, Li, Pb, Sn, and Zn concentrations. Selected heavy metal (Cu, Cr, Hg, and Zn) and metalloid (As and Sn) distributions were normalized against Al and Li with the main goal of compensating for natural grain-size variability and to separate natural from anthropogenic contributions, by using a combination of normalization techniques (definition of regional geochemical baselines (RGB) and determination of enrichment factors (EF)). Lead did not reveal a significant relationship with Al and Li. Aluminum explained more variance than Li for As, Cu, Hg, and Zn. Assuming the general non-impacted metal character of the Minho River estuary sediments, RGBs are defined for differentiating between natural and anthropogenic contributions. Based on RGB defined for each heavy metal/metalloid, the degree of enrichment is estimated through the determination of EF. Despite the relatively low total heavy metal and metalloid concentrations, the defined RGB identifies a set of samples characterized by presenting As, Cu, Cr, Hg, and Zn enrichments relatively to expected natural levels. Mercury is the element showing the highest level of enrichment relative to the baseline values being spread through all the study area. Tin present enrichments relatively to Al and or Li always lower than 1.5 suggesting natural contributions. PMID:23179725

Mil-Homens, M; Costa, A M; Fonseca, S; Trancoso, M A; Lopes, C; Serrano, R; Sousa, R

2012-11-21

195

Evaluation of Life History Diversity, Habitat Connectivity, and Survival Benefits Associated with Habitat Restoration Actions in the Lower Columbia River and Estuary, Annual Report 2009  

Energy Technology Data Exchange (ETDEWEB)

This report describes the 2009 research conducted under the U.S. Army Corps of Engineers (USACE or Corps) project EST-09-P-01, titled “Evaluation of Life History Diversity, Habitat Connectivity, and Survival Benefits Associated with Habitat Restoration Actions in the Lower Columbia River and Estuary.” The research was conducted by the Pacific Northwest National Laboratory, Marine Science Laboratory and Hydrology Group, in partnership with the University of Washington, School of Aquatic and Fishery Sciences, Columbia Basin Research, and Earl Dawley (NOAA Fisheries, retired). This Columbia River Fish Mitigation Program project, referred to as “Salmonid Benefits,” was started in FY 2009 to evaluate the state-of-the science regarding the ability to quantify the benefits to listed salmonids1 of habitat restoration actions in the lower Columbia River and estuary.

Diefenderfer, Heida L.; Johnson, Gary E.; Sather, Nichole K.; Skalski, John R.; Dawley, Earl M.; Coleman, Andre M.

2010-08-01

196

Foraging strategies of Southern sea lion females in the La Plata River Estuary (Argentina-Uruguay)  

Science.gov (United States)

The stocks of Southern sea lions (Otaria flavescens, SSL) and South American fur seals (SAFS) that breed on coastal islands of Uruguay constitute the most important focal concentration of pinnipeds in South America, with a significant increase in SAFS and a steady decrease of SSL over the past decades. Because females are a key element of population dynamics and no information exists on the post-breeding pup rearing period, we studied the foraging patterns of SSL females in the La Plata River Estuary (LPRE) during mid and late lactation (late austral autumn and winter), analyzing the foraging performance, geographic coverage and ontogenetic differences in foraging strategies for a period of 1-5 months. At-sea movements of 22 SSL females (6 subadults and 16 adults) from Isla de Lobos (IL, 35°01?28”S-54°52?59”W, Uruguay) were monitored using satellite transmitters (SPOT4, SPOT5 and STDR-S16, Wildlife Computers) in 2007 and 2010. An algorithm [McConnell, B.J., Chambers, C., Fedak, M.A., 1992. Foraging ecology of southern elephant seals in relation to the bathymetry and productivity of the Southern Ocean. Antarct. Sci. 4, 393-398.] with a maximum transit speed of 3 m s-1 was applied to the Argos information, resulting in a total of 2522 filtered locations. A daily mean of 3.5±1.74 filtered locations per animal was received. One hundred and eighty three foraging trips (FT) were recorded with no significant differences (pSSL showed directional fidelity to foraging sites, indicated by high mean vector (r) values (0.74±0.14) calculated from FT mean bearings. Kernel ranges for 50% and 95% of all FT locations were 5420 km2 and 36,222 km2, respectively, and the extension of the foraging areas appeared to be influenced by a combination of bathymetry and ecological boundaries within LPRE. Regardless of their reproductive condition, females showed a strong fidelity to IL, and their foraging activity was restricted to relatively shallow areas (10-100 m) on the continental shelf. During autumn and winter, SSL females made significantly longer FTs than during the breeding season, when lactating females decrease FT duration by increasing transit speed but maintain a similar spatial coverage compared with FT later in lactation. Although several aquatic areas of high priority for conservation in LPRE have been identified and proposed, only 15% of the foraging habitat of SSL females is currently included in these areas. This emphasizes the importance of the inclusion of the at-sea foraging distributions of central point foragers in marine protected areas. If conservation efforts focus only on coastal breeding concentrations, key elements of the life cycle are excluded with potential unpredictable effects.

Rodríguez, Diego H.; Dassis, Mariela; Ponce de León, Alberto; Barreiro, César; Farenga, Marcelo; Bastida, Ricardo O.; Davis, Randall W.

2013-04-01

197

Enzymatic biomarkers in the crab Carcinus maenas from the Minho River estuary (NW Portugal) exposed to zinc and mercury.  

Science.gov (United States)

Zinc and mercury are common contaminants of estuaries and coastal ecosystems where they may induce adverse effects on the biota. Carcinus maenas is a key-species in several European estuaries, living in close association with the sediment where a considerable number of environmental contaminants, including zinc and mercury may accumulate. In the present study, the acute effects of zinc and mercury on C. maenas from the Minho River Estuary (NW Portugal) were investigated by using the activity of the enzymes cholinesterase (ChE), lactate dehydrogenase (LDH) and glutathione S-transferases (GST) as effects' criteria. Crabs were exposed for 96h to several concentrations of Zn(2+) (0, 1.84, 3.71, 7.39 and 14.79mg/l) or Hg(2+) (0, 0.09, 0.19, 0.37 and 0.74mg/l). The choice of Zn(2+) test concentrations was based on the LC50 value (14.86mg/l) determined in a first part of the study, while the choice of Hg(2+) concentrations was based on values from the literature. At the end of the bioassays, eye, muscle and hepatopancreas tissues were isolated and used for ChE, LDH and GST determinations, respectively. Zinc significantly inhibited ChE activity (p<0.05, EC50=14.68mg/l), caused significant alterations of GST activity (p<0.05) and induced LDH activity (p<0.05) at the exposure of 14.79mg/l. Mercury significantly inhibited ChE activity (p<0.001, LOEC=0.09mg/l, EC50=0.235mg/l) and increased both GST (p<0.05, LOEC=0.774mg/l) and LDH activities (p<0.05, LOEC=0.119mg/l). These results suggest that both metals interfere with cholinergic neurotransmission in C. maenas by inhibiting ChE activity. In addition, they also interfere with GST activity and this may reduce the capacity of detoxification of some chemicals and/or to increase the probability of oxidative stress to occur. Furthermore, both metals increase LDH activity, suggesting an interference with energy production pathways. Therefore, the presence of zinc and mercury in estuaries at concentrations in the mg/l or mug/l range, respectively, may have a negative impact on C. maenas. PMID:16949639

Elumalai, M; Antunes, C; Guilhermino, L

2006-09-01

198

Enzymatic biomarkers in the crab Carcinus maenas from the Minho River estuary (NW Portugal) exposed to zinc and mercury.  

UK PubMed Central (United Kingdom)

Zinc and mercury are common contaminants of estuaries and coastal ecosystems where they may induce adverse effects on the biota. Carcinus maenas is a key-species in several European estuaries, living in close association with the sediment where a considerable number of environmental contaminants, including zinc and mercury may accumulate. In the present study, the acute effects of zinc and mercury on C. maenas from the Minho River Estuary (NW Portugal) were investigated by using the activity of the enzymes cholinesterase (ChE), lactate dehydrogenase (LDH) and glutathione S-transferases (GST) as effects' criteria. Crabs were exposed for 96h to several concentrations of Zn(2+) (0, 1.84, 3.71, 7.39 and 14.79mg/l) or Hg(2+) (0, 0.09, 0.19, 0.37 and 0.74mg/l). The choice of Zn(2+) test concentrations was based on the LC50 value (14.86mg/l) determined in a first part of the study, while the choice of Hg(2+) concentrations was based on values from the literature. At the end of the bioassays, eye, muscle and hepatopancreas tissues were isolated and used for ChE, LDH and GST determinations, respectively. Zinc significantly inhibited ChE activity (p<0.05, EC50=14.68mg/l), caused significant alterations of GST activity (p<0.05) and induced LDH activity (p<0.05) at the exposure of 14.79mg/l. Mercury significantly inhibited ChE activity (p<0.001, LOEC=0.09mg/l, EC50=0.235mg/l) and increased both GST (p<0.05, LOEC=0.774mg/l) and LDH activities (p<0.05, LOEC=0.119mg/l). These results suggest that both metals interfere with cholinergic neurotransmission in C. maenas by inhibiting ChE activity. In addition, they also interfere with GST activity and this may reduce the capacity of detoxification of some chemicals and/or to increase the probability of oxidative stress to occur. Furthermore, both metals increase LDH activity, suggesting an interference with energy production pathways. Therefore, the presence of zinc and mercury in estuaries at concentrations in the mg/l or mug/l range, respectively, may have a negative impact on C. maenas.

Elumalai M; Antunes C; Guilhermino L

2007-01-01

199

Occurrence and distribution of heavy metals in surface sediments of the Changhua River Estuary and adjacent shelf (Hainan Island).  

Science.gov (United States)

Heavy metal (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) concentrations in surface sediments from the Changhua River Estuary and adjacent shelf, western Hainan Island, were conducted to evaluate the level of contamination. Numerical Sediment Quality Guidelines (TEL and PEL) were applied to assess adverse biological effects of these metals, suggesting that occasional biological effect may occur due to As, Cr, Cu, Ni, and Pb. Enrichment factors shown that the significant As and Pb contaminations in the study area. Multivariate analysis indicated that the sources of Cd, Cr, Cu, Hg, Ni and Zn resulted primarily from natural weathering processes, whereas As and Pb were mainly attributed to anthropogenic sources. The results of this study would provide a useful aid for sustainable marine management in the region. PMID:24035428

Hu, Bangqi; Cui, Ruyong; Li, Jun; Wei, Helong; Zhao, Jingtao; Bai, Fenglong; Song, Weiyu; Ding, Xue

2013-09-12

200

Spatial-temporal variation and moon effects on estuarine ichthyofauna: evidence for the Joanes River estuary – Bahia  

Directory of Open Access Journals (Sweden)

Full Text Available Abundance, biomass, length, richness, diversity and equitability data were obtained to investigate the effect of lunar cycle and spatial-temporal variation on the ichthyofauna of the Joanes River estuary. 1,497 fish were captured, weighing 7,760g and belonging to 48 species of 22 families. The analysis of the community indicated no significant differences regarding the effects of the moon, although the waning moon was responsible for higher captures. The composition and structure of the ichthyofauna varied with the sediment type and mangrove vegetation, where more individuals and more species preferred the muddy sediment in areas with preserved marginal vegetation. Groupings based on the abundance data did not follow the temporal variations of a long period of time, but fish assemblages with similar niches in relation to the habitat use preferred certain areas according to the sediment type.

José Amorim Reis-Filho; Gabriel Barros Gonçalves de Souza; Lauro Diógenes Cavalcante Nunes; Bruno Lima de Menezes

2010-01-01

 
 
 
 
201

FLOWER: a computer code for simulating three-dimensional flow, temperature, and salinity conditions in rivers, estuaries, and coastal regions  

Energy Technology Data Exchange (ETDEWEB)

FLOWER is a three-dimensional computer code for simulating fast-transient, free-surface flow, temperature, and salinity conditions in rivers, estuaries, and coastal regions. The model also includes rotational effects (Coriolis force) and is capable of accommodating wind-stress coupling, a capability which enables the model to be applied to large water bodies with significant wind-driven currents, such as the Great Lakes. The mathematical formulation utilizes the integral form of the governing equations of the discrete-element method. In this method, interior flow regions are represented as rectangular elements of variable size, while impermeable boundary elements are constructed from truncated rectangles, thus allowing accurate representations of complex shorelines. 83 references, 45 figures, 2 tables.

Eraslan, A; Lin, W.L.; Sharp, R.D.

1983-12-01

202

A new species of Pseudodiaptomus (Crustacea, Copepoda, Calanoida, Pseudodiaptomidae) from the Prasae River Estuary, Gulf of Thailand.  

Science.gov (United States)

A new species of the calanoid copepod genus Pseudodiaptomus was collected from the Prasae River Estuary, Rayong Province, on the eastern coast of the Gulf of Thailand. This species is definitely assigned to the lobus species group sensu Walter (1986a). The female of the new species differs from other congeners in the elongate genital double-somite with a blunt process ventrally and the second urosomite about 2.54 times as long as wide. The male is also easily distinguished from other congeners by the structure of the right fifth leg. The present new species is a euryhaline species and occurred in brackish waters with salinity ranging from 0.7 to 23.3. Its breeding season may be from June to October, as indicated by the presence of egg-sacs. PMID:24146583

Srinui, Khwanruan; Nishida, Shuhei; Ohtsuka, Susumu

2013-10-02

203

A new species of Pseudodiaptomus (Crustacea, Copepoda, Calanoida, Pseudodiaptomidae) from the Prasae River Estuary, Gulf of Thailand.  

UK PubMed Central (United Kingdom)

A new species of the calanoid copepod genus Pseudodiaptomus was collected from the Prasae River Estuary, Rayong Province, on the eastern coast of the Gulf of Thailand. This species is definitely assigned to the lobus species group sensu Walter (1986a). The female of the new species differs from other congeners in the elongate genital double-somite with a blunt process ventrally and the second urosomite about 2.54 times as long as wide. The male is also easily distinguished from other congeners by the structure of the right fifth leg. The present new species is a euryhaline species and occurred in brackish waters with salinity ranging from 0.7 to 23.3. Its breeding season may be from June to October, as indicated by the presence of egg-sacs.

Srinui K; Nishida S; Ohtsuka S

2013-01-01

204

Long-term effects of changing land use practices on surface water quality in a coastal river and lagoonal estuary.  

UK PubMed Central (United Kingdom)

The watershed of the Neuse River, a major tributary of the largest lagoonal estuary on the U.S. mainland, has sustained rapid growth of human and swine populations. This study integrated a decade of available land cover and water quality data to examine relationships between land use changes and surface water quality. Geographic Information Systems (GIS) analysis was used to characterize 26 subbasins throughout the watershed for changes in land use during 1992-2001, considering urban, agricultural (cropland, animal as pasture, and densities of confined animal feed operations [CAFOs]), forested, grassland, and wetland categories and numbers of wastewater treatment plants (WWTPs). GIS was also used together with longitudinal regression analysis to identify specific land use characteristics that influenced surface water quality. Total phosphorus concentrations were significantly higher during summer in subbasins with high densities of WWTPs and CAFOs. Nitrate was significantly higher during winter in subbasins with high numbers of WWTPs, and organic nitrogen was higher in subbasins with higher agricultural coverage, especially with high coverage of pastures fertilized with animal manure. Ammonium concentrations were elevated after high precipitation. Overall, wastewater discharges in the upper, increasingly urbanized Neuse basin and intensive swine agriculture in the lower basin have been the highest contributors of nitrogen and phosphorus to receiving surface waters. Although nonpoint sources have been emphasized in the eutrophication of rivers and estuaries such as the Neuse, point sources continue to be major nutrient contributors in watersheds sustaining increasing human population growth. The described correlation and regression analyses represent a rapid, reliable method to relate land use patterns to water quality, and they can be adapted to watersheds in any region.

Rothenberger MB; Burkholder JM; Brownie C

2009-09-01

205

Study of Tidal Propagation in the Lower Columbia River (LCR) Estuary using Numerical Modeling  

Science.gov (United States)

A numerical model Adaptive Hydraulics (AdH) was utilized to study the propagation of tides in the LCR estuary. Model results and observations show that the symmetric tide at the inlet rapidly degenerates as the tide propagates upstream due to shallow water, friction and riverine influences. At the inlet M2 is the major tidal component however, upstream energy is progressively transferred from the M2 and other primary components to the MSf, M4 and S4 components, with a majority of the energy passing to the MSf component. An analysis was performed to determine the mechanism of this transfer and it was found that the nonlinear interactions between the M2 and S2 components due to the shallow water effects causes ~80% of the transfer. The presentation will demonstrate the model, results from the model, a detailed description of the tide in the LCR estuary and the analysis of tidal behavior.

Savant, G.; McAlpin, T. O.; McAdory, R.

2011-12-01

206

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

UK PubMed Central (United Kingdom)

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.

Pereira LC; Monteiro MC; Guimarães DO; Matos JB; Costa RM

2010-06-01

207

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

2008-01-01

208

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

UK PubMed Central (United Kingdom)

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.

Sun J; Zhao R; Zhang LY

2011-04-01

209

[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

210

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

211

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

212

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, pscavenged by adsorption onto SS and/or sediments in estuarine environments. In addition, values for K(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. 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

2013-01-16

213

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

UK PubMed Central (United Kingdom)

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, p<0.01); K(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(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.

Hong S; Khim JS; Park J; Kim M; Kim WK; Jung J; Hyun S; Kim JG; Lee H; Choi HJ; Codling G; Giesy JP

2013-02-01

214

[Phenomena of pH instant increasing and its effect on dissolved inorganic carbon flux to sea in Yellow River estuary].  

UK PubMed Central (United Kingdom)

Dissolved inorganic carbon (DIC), pH, the partial pressure of CO (pCO2), total alkalinity (TA), dissolved oxygen saturation (DO), chlorophyll a (Chl-a), and NH4+, PO4(3-) were studied in mixing zone of Yellow River estuary from September 2004 to April 2006. The results indicate that pH value is higher than that of freshwater in low salinity area where DIC is non-conservative. NH4+, PO4(3-) sharply decreasing indicates that biogenic respiration is possibly inhibited in early mixing of freshwater and seawater, then pCO2, which is derived from biogenic respiration, swiftly decrease and lead to CaCO3 precipitation in low salinity area, and the pH value will simultaneously increase in this area. Instant increasing pH value can be used as index of CaCO3 precipitation in Yellow River estuary. According to dissolved matter mixing model in estuary, the observation of 1:1 removal of TA and DIC provides just evidence that DIC removal we observed in the field is a result of CaCO3 precipitation. The process can clean 10% (1.21 x 10(5) tons) DIC which is transported by freshwater both in dry and wet weathers, and the annually effective DIC flux to sea of Yellow River is 10.86 x 10(5) tons. Ten percent of CO2 (2.24 x 10(5) t) which is absorbed by chemical weathering process in drainage basin will release to atmosphere in Yellow River estuary.

Zhang XS; Zhang LJ

2007-06-01

215

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

Directory of Open Access Journals (Sweden)

Full Text Available 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. Model simulations showed that salinity as far as15-25km from the coast. The model simulations show tidal effects on Brisbane River and surrounding groundwater and water quality deterioration appear to be related to coastal seawater intrusion over time.

G. A. TULARAM; R. SINGH

2009-01-01

216

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

International Nuclear Information System (INIS)

[en] 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 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

2004-01-01

217

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

Directory of Open Access Journals (Sweden)

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; Danielle Paludo; Eunice Maria Almeida de Oliveira; Régis Pinto de Lima; Ricardo José Soavinski

2011-01-01

218

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

Energy Technology Data Exchange (ETDEWEB)

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{sup -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{sup -3} and total suspended matter from 9.9 to 21.5 g m{sup -3}. A close relationship was found between chl-a concentration and total suspended matter concentration with the determining coefficient (R{sup 2}) above 0.89. The MBR calculated in the spectral bands of MODIS proved to be a good proxy for chl-a concentration (R{sup 2} > 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{sup -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.

Zhang Yuanzhi; Lin Hui [Institute of Space and Earth Information Science, Yuen Yuen Research Centre for Satellite Remote Sensing, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Chen, Chuqun [South China Institute of Oceanology, Chinese Academy of Sciences, Guangzhou (China); Chen Liding [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing (China); Zhang Bing [Center for Earth Observation and Digital Earth, Chinese Academy of Sciences, Beijing (China); Gitelson, Anatoly A, E-mail: yuanzhizhang@cuhk.edu.hk [Center for Advanced Land Management Information Technologies (CALMIT), School of Natural Resources, University of Nebraska-Lincoln (United States)

2011-04-15

219

Genotype and Seeding Date Effects on Performance of Mangrove Rice (Oryza sativa L.) In the Cross River Estuary  

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Full Text Available The mangrove swamp soils of the Cross River estuary are suitable for intensive rice cultivation because of ample water supply, large level units and high inherent fertility. However, because water is abundant, rainfall does not determine the sowing period. Field studies were conducted in 2006 and 2007 at Obufa Esuk Orok adjacent the University of Calabar Teaching and Research Farm to determine the best seeding date for two salt-tolerant rice varieties grown on a mangrove swamp soil in the Cross River estuary, southeastern Nigeria. Two mangrove rice varieties namely ROC 5 and CK 73 were raised in nurseries on 6 December, 8 January, 4 February and 4 March, of each year and 30 day-old seedlings transplanted at a plant spacing of 20x20 cm and at 2 seedlings per hill. Treatments comprised factorial combinations of four seeding dates and two varieties laid out in a split-plot design; the main- plot being the date of seeding and the sub-plot the variety. Significant varietal differences were observed, with CK 73 performing better than ROC 5. During the 2006 and 2007 growing seasons, paddy yield of 4.35 and 5.14 t ha-1 obtained from sowing in February was higher than yield values for December, January and March plantings by 14.5, 27.6 and 18.2% (2006) and 37.9, 41.8 and 18.9% (2007). Seeding conditions in December through January were unfavorable because in the absence of water control, the frequent and unpredictable tidal water flow washed away seeds and seedlings, leading to poor germination, seedling establishment and reduction of the crop’s tillering capacity and panicle formation. These conditions were ameliorated in February and March and the favorable solar radiation levels and temperature regime that subsisted in April and May when the February sown crop matured accounted for the superiority of this seeding period. It would however, be unsuitable to seed late-maturing varieties at this period because they would mature during the peak rains when natural drying conditions would be unfavorable.

W.B. Binang; J.D. Ntia; O.J. Shiyam

2012-01-01

220

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

International Nuclear Information System (INIS)

[en] 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)

1979-01-01

 
 
 
 
221

78 FR 14985 - Takes of Marine Mammals Incidental to Specified Activities; Russian River Estuary Management...  

Science.gov (United States)

...seal (Phoca vitulina), California sea lion (Zalophus californianus), and northern...Most recently, a solitary male sea lion was observed hauled out at the river...flushing from the beach. One California sea lion was observed, but did not...

2013-03-08

222

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

2013-09-05

223

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.

Yuanzhi Zhang; Yufei Wang; Yunpeng Wang; Hongyan Xi

2009-01-01

224

Development of a Hydrodynamic Model for Skagit River Estuary for Estuarine Restoration Feasibility Assessment  

International Nuclear Information System (INIS)

[en] The Skagit River is the largest river in the Puget Sound estuarine system. It discharges about 39% of total sediment and more than 20% of freshwater into Puget Sound. The Skagit River delta provides rich estuarine and freshwater habitats for salmon and many other wildlife species. Over the past 150 years, economic development in the Skagit River delta has resulted in significant losses of wildlife habitat, particularly due to construction of dikes. Diked portion of the delta is known as Fir Island where irrigation practices for agriculture land over the last century has resulted in land subsidence. This has also caused reduced efficiency of drainage network and impeded fish passages through the area. In this study, a three-dimensional tidal circulation model was developed for the Skagit River delta to assist estuarine restoration in the Fir Island area. The hydrodynamic model used in the study is the Finite Volume Coastal Ocean Model (FVCOM). The hydrodynamic model was calibrated using field data collected from the study area specifically for the model development. Wetting and drying processes in the estuarine delta are simulated in the hydrodynamic model. The calibrated model was applied to simulate different restoration alternatives and provide guidance for estuarine restoration and management. Specifically, the model was used to help select and design configurations that would improve the supply of sediment and freshwater to the mudflats and tidal marsh areas outside of diked regions and then improve the estuarine habitats for salmon migration

2005-11-02

225

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

226

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; Rosebel Cunha Nalesso

2006-01-01

227

Vertical distribution of total mercury and methylmercury in sediment of the Fugong mangrove area at Jiulong River Estuary, Fujian, China.  

UK PubMed Central (United Kingdom)

The concentrations and vertical distributions of total mercury (Hg) and methylmercury (methyl Hg) in the sediment of the Fugong mangrove area, located at the Jiulong River Estuary, Fujian, China, were investigated. The concentrations of total mercury were between 0.12-0.17 and 0.11-40.14 microg/g, while concentrations of methylmercury were between 0.15-1.8 and 0.081-0.58 ng/g (as mercury), in the dry and rainy seasons, respectively. The total mercury concentration was not correlated with the sampling depth. As the depth increased, methylmercury concentrations first increased to their maximum level at a depth of 10-25 cm, and then decreased; this was similar to the vertical distribution characteristics of methylmercury/total mercury ratios. The mangrove ecosystem was considered as a source of methylmercury for adjacent areas, due to the higher average methylmercury concentration in the mangrove sediment than other sediments nearby. Statistically significant logarithmic correlations, conic correlations, and negative correlations were observed for methylmercury and sulfide concentration, sediment organic matter, and sediment pH, respectively.

Liang Y; Yuan D; Chen Y; Liu X

2013-06-01

228

Vertical distribution of total mercury and methylmercury in sediment of the Fugong mangrove area at Jiulong River Estuary, Fujian, China.  

Science.gov (United States)

The concentrations and vertical distributions of total mercury (Hg) and methylmercury (methyl Hg) in the sediment of the Fugong mangrove area, located at the Jiulong River Estuary, Fujian, China, were investigated. The concentrations of total mercury were between 0.12-0.17 and 0.11-40.14 microg/g, while concentrations of methylmercury were between 0.15-1.8 and 0.081-0.58 ng/g (as mercury), in the dry and rainy seasons, respectively. The total mercury concentration was not correlated with the sampling depth. As the depth increased, methylmercury concentrations first increased to their maximum level at a depth of 10-25 cm, and then decreased; this was similar to the vertical distribution characteristics of methylmercury/total mercury ratios. The mangrove ecosystem was considered as a source of methylmercury for adjacent areas, due to the higher average methylmercury concentration in the mangrove sediment than other sediments nearby. Statistically significant logarithmic correlations, conic correlations, and negative correlations were observed for methylmercury and sulfide concentration, sediment organic matter, and sediment pH, respectively. PMID:23833815

Liang, Ying; Yuan, Dongxing; Chen, Yaojin; Liu, Xiyao

2013-06-01

229

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

International Nuclear Information System (INIS)

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 206Pb/207Pb 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.

2007-01-01

230

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

231

Taxonomic and biological studies on organisms causing a large scale red tide in Zhujiang River Estuary in spring, 1998 III  

UK PubMed Central (United Kingdom)

The dominant causative organism of the bloom was identified to be Gyr. instriatum with the highest density of 3.6×10~(7) cells/L, followed by Skeletonema costatum (1.6×10~(7) cells/L), Prorocentrum (6.1×10~(6) cells/L), Gym. mikimotoi (1.1×10~(6) cells/L) and Ceratium furca. The red tide organisms also included Gym. sanguineum, Polykrikos schwartzii, P. hartmannii and Gym. catenatum. Apparently, the bloom occurred in Shenzhen Bay was the same as that in Guishan Island, for almost all of the dominant causative organisms of Guishan Island bloom were found in the Shenzhen Bay bloom. However, diatom S. costatum was the second dominant in Shenzhen Bay bloom, indicating that the unarmored dinoflagellate bloom occurred in Zhujiang River Estuary would end. The percentages of diatom increased while the total densities of the bloom samples decreased, showing that the normal diatom community was replacing the unarmored dinoflagellate community when the bloom was going to its end.

Huang Changjiang; Dong Qiaoxiang

2001-01-01

232

Application of temperature gradient gel electrophoresis to the study of yeast diversity in the estuary of the Tagus river, Portugal.  

UK PubMed Central (United Kingdom)

Temperature gradient gel electrophoresis (TGGE) was employed for the assessment of yeast diversity in the estuary of the Tagus river (Portugal). The molecular detection of yeasts was carried out directly from water samples and, in parallel, a cultivation approach by means of an enrichment step was employed. A nested PCR was employed to obtain a fungal amplicon containing the D2 domain of the 26S rRNA gene. For identification the TGGE bands were extracted, re-amplified, and sequenced. Fourteen fungal taxa were detected and all except one were yeasts. Most yeast sequences corresponded to members of the Ascomycota and only three belonged to the Basidiomycota. Five yeasts (four ascomycetes and one basidiomycete) could not be identified to the species level due to the uniqueness of their sequences. The number of species detected after enrichment was higher than the number of taxa found using the direct detection method. This suggests that some yeast populations are present in densities that are below the detection threshold of the method. With respect to the analysis of the yeast community structure, our results indicate that the dominant populations belong to Debaryomyces hansenii, Rhodotorula mucilaginosa, Cryptococcus longus, and to an uncultured basidiomycetous yeast phylogenetically close to Cr. longus. The combined analysis of direct detection and cultivation approaches indicates a similar community structure at the two sampled sites since nine species were present at both localities.

Gadanho M; Sampaio JP

2004-12-01

233

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

UK PubMed Central (United Kingdom)

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.

Barbieri E; Passos Ede A; Aragão KA; Santos DB; Garcia CA

2010-12-01

234

Habitat values for artificial oyster ( Crassostrea ariakensis) reefs compared with natural shallow-water habitats in Changjiang River estuary  

Science.gov (United States)

Oyster reefs have an equivalent, complex 3-dimensional structure to vegetated habitats and may provide similar functions in estuarine environments. Nevertheless, few studies have compared oyster reefs with adjacent natural shallow-water habitats. Here the resident benthic macroinvertebrate communities in an artificial oyster ( Crassostrea ariakensis) reef and in adjacent natural estuarine shallow-water habitats (salt marsh, intertidal mudflat, and subtidal soft bottom) in the Changjiang (Yangtze) River estuary were described. The mean total densities and biomass, Margalef's species richness, Pielou's evenness and Shannon-Weaver biodiversity indices of the resident benthic macroinvertebrate communities differed significantly among the habitats. Significantly higher densities and biomass of benthic macroinvertebrates occurred in the oyster reef compared with the other three habitats. Ordination plots showed a clear separation in benthic macroinvertebrate communities among the four habitat types. The results demonstrated that the artificial oyster reef supported distinct and unique benthic communities, playing an important role in the complex estuarine habitat by supplying prey resources and contributing to biodiversity. In addition, the results suggested that the oyster reef had been restored successfully.

Quan, Weimin; Zheng, Lin; Li, Beijun; An, Chuanguang

2013-09-01

235

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

UK PubMed Central (United Kingdom)

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.

Chen Q; Liu J; Ho KC; Yang Z

2012-03-01

236

Nitrate flux into the sediments of a shallow oligohaline estuary during large flood pulses of Mississippi River water.  

UK PubMed Central (United Kingdom)

Lake Pontchartrain is a large, oligohaline estuary located in coastal Louisiana that receives episodic diversions of nitrogen-rich Mississippi River water via the Bonnet Carré Spillway to alleviate flood threats to the city of New Orleans. These events may be linked to expressions of eutrophication, and it is therefore important to investigate pathways of nitrate (NO) loss. Nitrate flux into the sediments of Lake Pontchartrain was investigated using two independent methods: (i) simulating high NO flood events under aerobic and anaerobic incubations in intact sediment cores collected during 2010 and (ii) in situ field measurements of the vertical profiles of dissolved inorganic nitrogen species at the sediment-water interface during the 2011 Bonnet Carré Spillway opening. Mean rates of NO flux into sediments based on mass transfer in intact cores collected in 2010 and in situ porewater measurements in 2011 were -17.4 and -1.4 mg NO-N m d, respectively, for water column NO concentrations observed in situ in 2011. During the laboratory incubations, there was no significant difference in NO flux between oxygen treatments. We estimate that NO flux into sediments accounted for up to 3.1% (309 Mg NO-N) of water column NO loss during the 2008 Bonnet Carré Spillway event. Sediment characteristics, field measurements, and results from the laboratory experiment suggest that denitrification is the primary pathway for NO reduction. Even though there is significant NO reduction occurring in Lake Pontchartrain sediments during Mississippi River diversion events, this pathway of NO loss from the water column plays a relatively minor role in the transformation of the very large amount of NO received during these times.

Roy ED; White JR

2012-09-01

237

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

UK PubMed Central (United Kingdom)

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.

Fernández-Gómez C; López-López JA; Matamoros V; Díez S; García-Vargas M; Moreno C

2013-04-01

238

Toxic organic compounds in surface sediments from the Elizabeth and Patapsco Rivers and estuaries  

International Nuclear Information System (INIS)

The study is an extension of a Chesapeake Bay-wide analysis of toxic organic substances into the Elizabeth and Patapsco River subestuaries. Twenty-eight surface sediment samples from the Elizabeth River and 40 surface sediment samples from the Patapsco, were analyzed in detail for the presence of mainly aromatic and polar organic compounds. Approximately 310 distinct compounds were identified by gas chromatography-mass spectrometry in the Elizabeth River samples, and about 480 in the Patapsco. Total aromatic concentrations ranged from 440,000 to 3,100 ppb in the Elizabeth and from 2.7 x 106 to 6100 ppb in the Patapsco. Similar to observation in the Chesapeake Bay, unsubstituted polynuclear aromatic hydrocarbons dominated, contributing about 50% to the total resolved concentration.

1982-01-01

239

6) Structural variation in mangrove forests of the estuary of the River Itabapoana, ES-RJ  

Directory of Open Access Journals (Sweden)

Full Text Available We analyzed the structure of 13 sites of mangrove vegetation in the Itabapoana estuary by use of the methodology of permanent plots. Considering all individuals >1m within the plots, the average height of forests ranged from 4.0 to 10.1m, the average DBH (diameter at breast height) ranged from 3.7 to 13.5cm, the basal area of living individuals was 13.5 to 48.3m2.ha-1, and the density of trunks was 1,475 to 21,000 trunks.ha-1. Overall, there was a greater contribution of the live basal area in relation to diameter >10.0cm (59%). Forests with better structural development exhibited a dominance of Avicennia germinans (L.) Stearn, while Laguncularia racemosa (L.) Gaertn. f. was dominant in less-developed forests. Our results showed that environmental features and biotic factors contribute to mangrove differentiation among sites. Such differences highlight the peculiarities of each mangrove and emphasize the need of specific management plans for ecosystem maintenance.

Elaine Bernini; Carlos Eduardo Rezende

2010-01-01

240

Impact of Iron Ore Tailing on Foraminifera of the Uppateru River Estuary, East Coast of India  

Directory of Open Access Journals (Sweden)

Full Text Available Benthic foraminiferal assemblages have been used to determine the effects of Iran ore tailing pollution on the marine environment. The present paper attempts to unveil pollution impact as responded by foraminiferal species of Uppateru estuary. The faunal data thus generated is compared with earlier data sets for possible adverse effects. There has been substantial reduction in total foraminiferal number (TFN), from 574 in 2006 to 213 in 2008 species (st.no.3) per10 gram sediment. Even the total species number (TSN) decreased from 27 in (st.no.8) 2006 to 8 (st.no.1) in 2008. Ammonia accounted for its share (68%), followed by Elphidium (7.4%) and Quinqueloculina (6.5%). These genera are considered to be robust and opportunistic type in the study area. This faunal variation in terms of density (TFN) may be owing to the pollution caused by iron ore tailing. This study also supports the view that benthic foraminiferal biota can be used as a tool to monitor marine pollution in general and estuarine environment in specific.

Nadimikeri Jayaraju; Balam C. S. R. Reddy; Kambham Reddeppa Reddy; Addula Nallapa Reddy

2011-01-01

 
 
 
 
241

Economic compensation standard for irrigation processes to safeguard environmental flows in the Yellow River Estuary, China  

Science.gov (United States)

Economic compensation for irrigation stakeholders to safeguard environmental flows. We calculate economic compensation under different water management practices. Non-linear relationship is more obvious with higher river flow rates. Crops with stable planting areas should be used to assess economic compensation.

Pang, Aiping; Sun, Tao; Yang, Zhifeng

2013-03-01

242

Estuarine and Tidal Freshwater Habitat Cover Types Along the Lower Columbia River Estuary Determined from Landsat 7 Enhanced Thematic Mapper (ETM+) Imagery, Technical Report 2003.  

Energy Technology Data Exchange (ETDEWEB)

Developing an understanding of the distribution and changes in estuarine and tidal floodplain ecosystems is critical to the management of biological resources in the lower Columbia River. Columbia River plants, fish, and wildlife require specific physicochemical and ecological conditions to sustain their populations. As habitats are degraded or lost, this capability is altered, often irretrievably; those species that cannot adapt are lost from the ecosystem. The Lower Columbia River Estuary Partnership (Estuary Partnership) completed a comprehensive ecosystem protection and enhancement plan for the lower Columbia River and estuary in 1999 (Jerrick, 1999). The plan identified habitat loss and modification as a critical threat to the integrity of the lower Columbia River ecosystem and called for a habitat inventory as a key first step in its long term restoration efforts. In 2000, the Estuary Partnership initiated a multiphase project to produce a spatial data set describing the current location and distribution of estuarine and tidal freshwater habitat cover types along the lower Columbia River from the river mouth to the Bonneville Dam using a consistent methodology and data sources (Fig. 1). The first phase of the project was the development of a broadbrush description of the estuarine and tidal freshwater habitat cover classes for the entire study area ({approx}146 river miles) using Landsat 7 ETM+ satellite imagery. Phase II of the project entailed analysis of the classified satellite imagery from Phase I. Analysis of change in landcover and a summary of the spatial relationships between cover types are part of Phase II. Phase III of the project included the classification of the high resolution hyperspectral imagery collected in 2000 and 2001 for key focal areas within the larger study area. Finally, Phase IV consists of this final report that presents results from refining the Landsat ETM+ classification and provides recommendations for future actions. Previous studies (Thomas, 1980; Thomas, 1983; Graves et al., 1995; NOAA, 1997; Allen, 1999) produced similar landcover data sets; however, most of these studies used multiple and varied data sources and differed from one another in methodologies. Currently, no single data set has been produced using a consistent methodology and uniform scale data, which describes current estuarine and tidal freshwater floodplain cover types from the Columbia's mouth to the Bonneville Dam (Fig. 1). Results from this study will be used by the Estuary Partnership and its cooperators to: (1) develop indicators of 'habitat health' for target species and populations, and biological integrity at the community and ecosystem scales; (2) develop definitions of 'important salmonid habitat'; (3) identify and evaluate potential wetland conservation and restoration sites; (4) track non-indigenous and invasive species; and (5) develop an understanding of how estuarine and floodplain habitats have changed over the past 200 years. This study focused on estuarine and tidal freshwater floodplain habitat cover types, which are important to native species, particularly juvenile salmonids. Results from this study are meant to provide support for the multiple efforts currently underway to recover 12 species of Columbia River salmonids identified as endangered or threatened under the Endangered Species Act. Spatial scale was an important consideration in this study. Our goal was to create a geographic information system (GIS) coverage depicting habitat cover types for the entire 146 river miles of the study area and the associated floodplain, at a spatial resolution sufficient to resolve important estuarine and floodplain features, wherever possible. Thus, in addition to the small scale (30 m pixel size) satellite imagery covering the study area described in this report, we also acquired high spatial resolution imagery ({approx}1.5 m pixel size) for key portions of the study area using a Compact Airborne Spectrographic Imager (CASI). Compared to the rather coarse, low spectral resolu

Garono, Ralph; Robinson, Rob

2003-10-01

243

Mid to late-Holocene diatom microfossils and geochemical proxies as evidence for paleoclimate in the Hudson River estuary, New York  

Science.gov (United States)

New methodologies that combine the use of microfossil diatom assemblages, and elemental geochemistry (bromine (Br)) are being developed to assess late Holocene climatic variability in estuaries. The main idea is that in an estuary the saltwater wedge fluctuates in response to the volume of fluvial discharge that depends on surface runoff from precipitation and melting of snow (spring freshet). During times of high precipitation the saltwater wedge is pushed seaward. In contrast, during times of drought the saltwater wedge moves landward into the estuary. The Hudson River estuary in New York was flooded by marine waters in the early Holocene and at present its sedimentation patterns are in a state of dynamic equilibrium. Guided by high-resolution multibeam bathymetry, sediment cores (˜6 m in length) were recovered from the oligohaline parts of the estuary where discharge and precipitation changes have more impact on the saltwater wedge fluctuations. In those cores that showed continuous sedimentation, diatom assemblages and Br (ppm) were studied and used as proxies for salinity. Diatom assemblages (marine, freshwater and brackish) were identified and counted and Br (ppm) was measured by X-ray fluorescence spectrometry with an Innov-X portable system. The results were calibrated to an Pb-210 age model and compared with instrumental data of precipitation, river discharge, and Palmer Drought Severity Index (PDSI), The results obtained from two different locations show that marine diatom abundance and Br content correlate with periods of high precipitation during 1992-1988; 1985-1980; 1976-1968; 1962-1958; and increase with periods of low precipitation or droughts in 1987-1985; 1980-1975; 1967-1962; 1943-1938. The mid to late Holocene record shows a variability on the scale of ˜300 to 400 years similar to that obtained by Cronin et al. (2003) for Chesapeake Bay and related to the North Atlantic Oscillation. From 1992 to the present, both marine diatoms and Br ppm increase dramatically and do not correlate to the precipitation record. This increase in salinity is observed in all the cores and could be the result of relative sea level rise into the estuary.

Gurung, D.; McHugh, C. M.; Kenna, T. C.; Burckle, L.

2009-05-01

244

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

UK PubMed Central (United Kingdom)

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 <1000 ng/g dry weight (wt.). However, we found PAHs in stomach contents of salmon from all sites at concentrations ranging from <100 to >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.

Yanagida GK; Anulacion BF; Bolton JL; Boyd D; Lomax DP; Paul Olson O; Sol SY; Willis M; Ylitalo GM; Johnson LL

2012-02-01

245

Scenarios involving future climate and water extraction: ecosystem states in the estuary of Australia's largest river.  

UK PubMed Central (United Kingdom)

Management of natural resources, particularly water, increasingly requires that likely benefits of particular actions (e.g., allocating an environmental flow) are quantified in advance. Therefore, new techniques are required that enable those potential benefits to be objectively compared among competing options for management (e.g., compared to a "do nothing" scenario). Scenario modeling is one method for developing such an objective comparison. We used existing hydrologic, hydrodynamic, and ecosystem response models for a case study location, the Coorong, an inverse estuary in South Australia, to illustrate the potential for such scenario modeling to inform natural resource management. We modeled a set of 12 scenarios that included different levels of water extraction, potential future climate change, and sea-level change, thereby enabling a comparison of the different drivers of possible future reductions in water availability in the Coorong. We discovered that potential future climate change combined with current extraction levels has the capacity to devastate the ecology of the Coorong, but also that much of the degradation could be averted by reducing upstream extractions of water. The inclusion of possible sea-level change had a surprising effect, whereby higher sea levels increased hydrodynamic connectivity between the Coorong's two lagoons. Increased hydrodynamic connectivity limited the occurrence of extremely low water levels and high salinities due to evapoconcentration that were simulated for dry future climates in the absence of sea-level rise. These findings strongly suggest that future ecological degradation in the Coorong is not a foregone conclusion, and that management decisions regarding water allocations upstream will determine the ecological future of this coastal lagoon.

Lester RE; Fairweather PG; Webster IT; Quin RA

2013-07-01

246

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

2012-07-28

247

Seasonal variations of sulfur in Suaeda salsa under different habitats in the intertidal zone of Yellow River Estuary, China  

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Full Text Available Aims Our objective was to determine the characteristics of sulfur (S) accumulation and allocation by Suaeda salsa in two different habitats of the intertidal zone in the Yellow River Estuary of China.Methods We established two plots (30 m × 30 m) in two different tidal flats and collected different organs of S.salsa every 20 days from May to November 2008 from four or five sites selected at random from the two plots.Important findings The biomass of different organs of S. salsa in middle tidal flat (JP1) and low tidal flat (JP2) showed significant seasonal dynamics, and the values of JP1 tended to be higher than those of JP2. For JP1 and JP2, the ratios of aboveground biomass to belowground biomass changed similarly, but the values of JP2 tendedto be larger than those of JP1. The litter biomass of JP1 and JP2 increased exponentially during the growing season. Although the total sulfur (TS) contents in leaves, stems or litter of JP1 and JP2 fluctuated greatly during the growing season, they all initially increased and then decreased. In comparison, values in roots decreased at all times following an exponential decay model. The TS accumulation amount and rate (VS) of different organs and litter also had seasonal changes, and the values of above-ground organs of JP1 were much higher than those of JP2. Moreover, the TS accumulation amount and VS of above-ground parts were higher than those of below-ground parts. The S allocation ratios of different parts of JP1 and JP2 also had significant differences. Leaves had the highest allocation ratio, and values of JP1 and JP2 were (38.34 ± 16.19)% and (66.27 ± 12.09)%, respectively, indicating that leaves were the most important site of S storage.

SUN Wan-Long; SUN Zhi-Gao; LIN Guang-Hui; MU Xiao-Jie; WANG Ling-Ling

2011-01-01

248

Experimental research on the marine hydrodynamic action on the consolidation process of the sediments in the Yellow River Estuary  

Science.gov (United States)

Based on the in-situ measurements, the impact of the marine hydrodynamics, such as wave and tide, in the rapidly deposited sediments consolidation process was studied. In the tide flat of Diaokou delta-lobe, one 2 m×1m×1 m test pit was excavated. The seabed soils were dug and dehydrated, and then the powder of the soil was mixed with seawater to be fluid sediments. And an iron plate covered part of the test pit to cut off the effect of the marine hydrodynamics. By field-testing methods, like static cone penetration test (SPT) and vane shear test (VST), the variation of strength is measured as a function of time, and the marine hydrodynamics impact on the consolidation process of the sediments in the Yellow River estuary was studied. It is shown that the self-consolidated sediments' strength linearly increases with the depth. In the consolidation process, in the initial, marine hydrodynamics play a decisive role, about 1.5 times as much as self-consolidated in raising the strength of the sea-bed soils, and with the extension of the depth the role of the hydrodynamics is reduced. In the continuation of the consolidation process, the trend of the surface sediments increased-strength gradually slows down under the water dynamics, while the sediments below 50 cm are in opposite ways. As a result, the rapidly deposited silt presents a nonuniform consolidation state, and the crust gradually forms. The results have been referenced in studying the role of the hydrodynamics in the soil consolidation process.

Yang, Xiu-Juan; Jia, Yong-Gang; Li, Xiang-Ran; Shan, Hong-Xian

2011-03-01

249

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

Scientific Electronic Library Online (English)

Full Text Available 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, 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, (more) 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 (more) 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.

Alvarenga, Luciana; Nalesso, Rosebel Cunha

2006-01-01

250

Pt and Pd in sediments from the Pearl River Estuary, South China: background levels, distribution, and source.  

UK PubMed Central (United Kingdom)

PURPOSE: This study assessed the concentrations of platinum (Pt) and palladium (Pd) in surface sediments and sedimentary cores collected from the Pearl River Estuary with a view of evaluating the distribution, background levels, possible sources, and contamination level of anthropogenic Pt and Pd. MATERIALS AND METHODS: Thirty-six samples of surface sediments and 12 samples from sedimentary cores were collected. Al(2)O(3) was analyzed on fused glass disks by X-ray fluorescence spectrometer. Heavy metal elements were measured by inductively coupled plasma-mass spectrometry. Pt and Pd were separated from the sample matrix by anion exchange chromatography and subsequent solvent extraction after samples had been digested in Carius tubes using aqua regia. The analysis of Pt and Pd was performed by isotopic dilution-inductively coupled plasma-mass spectrometry. RESULTS AND DISCUSSION: Pt and Pd concentrations in surface sediments were 0.28-2.11 and 0.39-38.30 ng/g, respectively, and Pt and Pd concentrations in sedimentary cores were 0.19-1.18 and 0.15-1.76 ng/g, respectively. Background values of Pt and Pd were 0.20-1.17 and 0.10-1.34 ng/g, respectively. The spatial distribution of the enrichment factor differed between Pt and Pd in surface sediments. Down-core variations in Pt, Pd, and other heavy metal elements were similar in all cases and were related to sediment type. CONCLUSIONS: Some of the Pt and Pt in surface samples were derived from anthropogenic emissions. Pt and Pd were delivered to the sediment by fluvial input. In addition to vehicle exhaust catalysts, Pt and Pd were derived from other sources (e.g., industrial process). An important post-burial remobilization process of Pt and Pd is likely to be particle mixing by billows caused by typhoon.

Zhong LF; Yan W; Li J; Tu XL; Liu BM; Xia Z

2012-05-01

251

Structure of the phytoplankton communities and primary production in the Ob River estuary and over the adjacent Kara Sea shelf  

Science.gov (United States)

The material was collected in the Ob River estuary and over the adjacent shallow Kara Sea shelf between 71°14'0 and 75°33'0N at the end of September 2007. Latitudinal zoning in the phytoplankton distribution was demonstrated; this zoning was determined by the changes in the salinity and concentration of nutrients. Characteristic of the phytocenosis in the southern desalinated zone composed of freshwater species of diatom and green algae were the high population density (1.5 × 106 cells/l), biomass (210 ?gC/l), chlorophyll concentration (4.5 ?g/l), and uniform distribution in the water column. High primary production (˜40 ?gC/l/day) was recorded in the upper 1.5-m layer. The estuarine frontal zone located to the north contained a halocline at a depth of 3-5 m. Freshwater species with low population density (2.5 × 105 cells/l), biomass (24 ?gC/l), and chlorophyll concentration (1.5 ?g/l) dominated above the halocline. Marine diatom algae, dinoflagellates, and autotrophic flagellates formed a considerable part of the phytocenosis below the halocline; the community characteristics were twofold lower as compared with the upper layer. The maximal values of the primary production (˜10 ?gC/l per day) were recorded in the upper 1.5-m layer. The phytocenosis in the seaward zone was formed by marine alga species and was considerably poorer as compared with the frontal zone. The assimilation numbers at the end of the vegetation season in the overall studied area were low, amounting to 0.4-1.0 ?gC/?gChl/h in the upper layer and 0.03-0.1 ?gC/?gChl/h under the pycnocline.

Sukhanova, I. N.; Flint, M. V.; Mosharov, S. A.; Sergeeva, V. M.

2010-10-01

252

[Diurnal variations of greenhouse gas fluxes at the water-air interface of aquaculture ponds in the Min River estuary].  

UK PubMed Central (United Kingdom)

Wetland reclamation and aquaculture is one of the main disturbance types in coastal wetlands. Diurnal variations of CO2, CH4 and N2O fluxes at the water-air interface were determined using a floating chambers + gas chromatography method in a shrimp pond, and a mixed culture pond of fish and shrimp in October in the Shanyutan Wetland of the Min River estuary, southeast China. Meanwhile, the meteorological indicators in ground surface and physical, chemical and biological indicators of surface water were also measured. CO2, CH4 and N2O fluxes at the water-air interface all demonstrated distinct diurnal variations. Both shrimp pond and mixed culture pond of fish and shrimp functioned as a sink of CO2 [the diurnal averaged CO2 fluxes were -48.79 and -105.25 mg x (m2 x h)(-1), respectively], and a source of CH4 [the diurnal averaged CH4 fluxes were 1.00 and 5.74 mg x (m2 x h)(-1), respectively]; the diurnal averaged CO2 and CH4 fluxes at the water-air interface of the mixed culture of fish and shrimp pond were higher than that of the shrimp pond. Greenhouse gas fluxes at the water-air interface from the aquaculture ponds were influenced by many factors. Multiple stepwise regression analysis showed that the concentration of Chlorophyll was the major factor affecting the CO2 fluxes, and the concentrations of SO4(2-) and PO4(3-) were the major factors affecting the CH4 fluxes at the water-air interface of the shrimp pond; whereas water temperature and Chlorophyll were the major factors affecting the CO2 fluxes, and dissolved oxygen, PO4(3-) and pH were the major factors affecting the CH4 fluxes at the water-air interface of the mixed culture pond of fish and shrimp.

Yang P; Tong C; He QH; Huang JF

2012-12-01

253

Heavy-metal Concentrations in the Mangrove Snail, Nerita lineata and Surface Sediments Collected from Klang River Estuary, Selangor, Malaysia.  

Directory of Open Access Journals (Sweden)

Full Text Available The mangrove snail, Nerita lineata, and the surface sediments were collected from the Klang River Estuary, potentially receiving anthropogenic inputs such as domestic, sewage and industrial waste. The snails were divided into three parts, namely soft tissues, operculum and shells and analysed for heavy-metal (Cd, Cu, Fe, Ni, Pb and Zn) concentrations. The total concentrations (µg/g dry weight) of heavy-metals in the surface sediments collected from the four sampling sites ranged from 0.21-1.45, 5.29-53.9, 22121-24175, 14.2-19.5, 30.4-62.3 and 46.4-207 for Cd, Cu, Fe, Ni, Pb and Zn, respectively. The ranges of heavy-metal concentrations (µg/g dry weight) in the shells were 3.45-7.48, 5.54-7.27, 39.8-49.6, 23.8-28.6, 66.3-71.8 and 4.10-7.33 for Cd, Cu, Fe, Ni, Pb and Zn, respectively. The ranges of heavy-metal concentrations (µg/g dry weight) in the operculum were 3.28-5.81, 6.67-11.2, 45.4-68.8, 23.5-24.7, 62.5-66.2 and 14.5-24.9, for Cd, Cu, Fe, Ni, Pb and Zn, respectively. As for the soft tissues, the heavy-metal concentrations (µg/g dry weight) ranges were 1.54-4.47, 17.3-24.4, 627-716, 4.41-5.32, 10.8-43.6 and 87.5-109 for Cd, Cu, Fe, Ni, Pb and Zn, respectively. It was found that the concentrations of Cu, Fe and Zn were higher in the soft tissues while the concentrations of Cd, Ni and Pb were higher in the operculum and shells of the snails.

Yap, C.K., Mohd Ruszaidi, S., Cheng, W.H. and Tan, S.G.

2010-01-01

254

The impact of poultry litter application on sediment chemistry of the Broadkill River estuary system, Delaware.  

UK PubMed Central (United Kingdom)

This project examined the impact of long-term poultry litter application on the chemical signatures of As, Cu, Zn, and P in stream sediments of the Broadkill River watershed within the Delmarva Peninsula, a region of intense poultry production. Thirty-seven sediment samples were collected from Broadkill River drainage systems and analyzed for litter-derived elements (As, Cu, Zn, P) and basic soil parameters such as particle size distribution, organic matter, and soluble salts. Results showed that concentrations of elements in stream sediments are approximately log-normally distributed. Spatial variability in concentrations of elements was evident, with most elements increasing in concentration and enrichment from upgradient headwaters to downgradient reaches draining predominantly agricultural areas. Results of correlation analyses showed positive significant correlation among elements; elements were also positively correlated with percent clay and silt in the sediment. Using GIS maps with overlays of hydrology and land use activities, statistical correlations between As, Cu, Zn, and P enrichment factors and land use were examined. Results showed statistically significant relationships between As, Mn, and Zn enrichment factors and residential areas within the watershed, but did not show a statistically significant relationship between element enrichment factors and agricultural land use. Factors that complicate this type of landscape-scale study include the presence of poultry processing plants, impoundments, changes in land use over time, and the influence of tides, all of which can have direct and indirect influences on element mobility.

Oyewumi O; Schreiber ME; Ciparis S

2013-08-01

255

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

UK PubMed Central (United Kingdom)

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.

Quevauviller P; Lavigne R; Cortez L

1989-01-01

256

Data from an instrumented navigational light tower off the Savanah River estuary  

International Nuclear Information System (INIS)

An oceanographic and meteorological instrumentation system operating on the Savannah Navigational Light Tower is providing synoptic information on ocean temperatures, currents, tides, and meteorological conditions. The Savannah Navigational Light Tower, an unmanned U.S. Coast Guard tower, is located about nine miles off Savannah Beach, Georgia, in about 16 m of water. The tower is currently instrumented to measure and record water temperatures from six depths, water velocities at two depts, tides, air temperature, barometric pressure, and wind speed and velocity at two heights. The outputs are currently being recorded every 10 minutes. These data aid in the interpretation of the processes governing pollutant transport in the Savannah River marine region and support other DOE funded programs in the southeastern United States. This past year, computer programs were written and are being tested for processing the raw data from the tower and for performing correlative analysis of the data

1978-01-01

257

Sulfate reduction and iron sulfide formation in sediments of the Pamlico River Estuary, North Carolina  

Energy Technology Data Exchange (ETDEWEB)

A seasonal study of sulfate reduction rates and iron sulfide concentration profiles was made and their interrelationships were investigated. Certain aspects of /sup 35/S-sulfate reduction rate methodology were also investigated in detail. Typical methods for recovery of labelled acid-volatile sulfide (AV/sup 35/S) were found to yield poor recoveries. Subsequent distillation with Cr/sup +2/, recovers some additional label, but under certain circumstances the final recoveries may still be very low. The partitioning of the label between AVS and pyrite is meaningless unless precautions are taken to prevent partial oxidation during the initial distillation. Methods were developed to improve recoveries and appropriate partitioning of label between the two pools. Another methodological aspect of /sup 35/S-sulfate reduction rate measurements considered in this study pertains to measurements made at low sulfate concentrations. Secondary subsurface maxima in /sup 35/S rats can be explained as being due to measurements being made in samples with small-scale spatial heterogeneity in sulfate concentrations. Sulfate reduction rates in Pamlico River sediments showed strong depth and temperature dependencies. Acid volatile sulfides (AVS) showed pronounced peaks below the sediment-water interface at both sites, but concentrations in upstream sediments were about twice as high as downstream. The subsurface peaks in AVS profiles were interpreted as being due to the balance between sulfate reduction and pyrite formation rather than a reflection of the depth distribution of sulfate reduction rates.

Albert, D.B.

1986-01-01

258

Sulfate reduction and iron sulfide formation in sediments of the Pamlico River Estuary, North Carolina  

International Nuclear Information System (INIS)

A seasonal study of sulfate reduction rates and iron sulfide concentration profiles was made and their interrelationships were investigated. Certain aspects of 35S-sulfate reduction rate methodology were also investigated in detail. Typical methods for recovery of labelled acid-volatile sulfide (AV35S) were found to yield poor recoveries. Subsequent distillation with Cr+2, recovers some additional label, but under certain circumstances the final recoveries may still be very low. The partitioning of the label between AVS and pyrite is meaningless unless precautions are taken to prevent partial oxidation during the initial distillation. Methods were developed to improve recoveries and appropriate partitioning of label between the two pools. Another methodological aspect of 35S-sulfate reduction rate measurements considered in this study pertains to measurements made at low sulfate concentrations. Secondary subsurface maxima in 35S rats can be explained as being due to measurements being made in samples with small-scale spatial heterogeneity in sulfate concentrations. Sulfate reduction rates in Pamlico River sediments showed strong depth and temperature dependencies. Acid volatile sulfides (AVS) showed pronounced peaks below the sediment-water interface at both sites, but concentrations in upstream sediments were about twice as high as downstream. The subsurface peaks in AVS profiles were interpreted as being due to the balance between sulfate reduction and pyrite formation rather than a reflection of the depth distribution of sulfate reduction rates.

1986-01-01

259

n-alkanes as indicators of natural and anthropogenic organic matter sources in the Siak River and its estuary, E Sumatra, Indonesia.  

UK PubMed Central (United Kingdom)

Along the Siak River and its estuary a total of 100 sediment and 57 plant samples were taken for the analysis of n-alkanes from 2003 to 2005. Sediment n-alkanes exhibit in the majority of samples a pronounced odd over even predominance with maxima at C29 and C31 indicative of a plant origin. Plant n-alkanes analysed have chain lengths up to C39. These compounds are also present in the river sediments. In some plants the Carbon Preference Index (CPI) has extremely low values normally only found in petroleum-contaminated samples. A distinction between vegetation- and petroleum-derived n-alkanes is therefore only possible by a combination of CPI and and the absence/presence of a prominent unresolved complex mixture. Based on these criteria only a limited number of the 100 sediments analysed exhibit clear indications of a petroleum contamination.

Liebezeit G; Wöstmann R

2009-09-01

260

n-alkanes as indicators of natural and anthropogenic organic matter sources in the Siak River and its estuary, E Sumatra, Indonesia.  

Science.gov (United States)

Along the Siak River and its estuary a total of 100 sediment and 57 plant samples were taken for the analysis of n-alkanes from 2003 to 2005. Sediment n-alkanes exhibit in the majority of samples a pronounced odd over even predominance with maxima at C29 and C31 indicative of a plant origin. Plant n-alkanes analysed have chain lengths up to C39. These compounds are also present in the river sediments. In some plants the Carbon Preference Index (CPI) has extremely low values normally only found in petroleum-contaminated samples. A distinction between vegetation- and petroleum-derived n-alkanes is therefore only possible by a combination of CPI and and the absence/presence of a prominent unresolved complex mixture. Based on these criteria only a limited number of the 100 sediments analysed exhibit clear indications of a petroleum contamination. PMID:19448964

Liebezeit, Gerd; Wöstmann, Ralf

2009-05-16

 
 
 
 
261

[Distribution characteristics of dissolved oxygen and its affecting factors in the Pearl River Estuary during the summer of the extremely drought hydrological year 2011].  

UK PubMed Central (United Kingdom)

More and more attention has focused on assessing impacts of extreme hydrologic events on estuarine ecosystem under the background of climate change. Based on a summer cruise conducted in the Pearl River Estuary in 2011 (extreme drought event), we have investigated the spatial distribution of dissolved oxygen (DO) and its relationships to water column stability, nutrient concentrations, and organic matter; besides, the major reason which caused the oxygen depletion was discussed. Under the influence of the extreme drought event, low bottom water dissolved oxygen was apparent in regions characterized by great depths, with an oxygen minimum value of 1.38 mg x L(-1). Statistical analysis shows significant correlations among deltaDO, deltaT, deltaS and deltaPOC. A comparison was conducted to show the mechanisms of oxygen depletion during the summers of 1999, 2009 and 2011, respectively. The result indicates that prolonged residence time of water due to the extremely low discharge and the subsequently decomposition of organic substance are major factors causing the formation of hypoxia during the summer drought in 2011. Despite the changing nutrient and organic matter regime in the Pearl River Estuary, there was no apparent trend in the minimum values of DO over the past 2 decades.

Ye F; Huang XP; Shi Z; Liu QX

2013-05-01

262

Characterization of heavy-metal contamination in surface sediments of the Minho river estuary by way of factor analysis.  

Science.gov (United States)

Surface sediments were collected in August 2009 from 49 sites along the Minho estuary (between Tui and Caminha) and analyzed for grain size, organic carbon (Corg) and total nitrogen (Ntot) contents, and major (silicon [Si], aluminum [Al], iron [Fe], calcium [Ca], magnesium [Mg], sodium [Na], potassium [K], titanium [Ti], and mangesese [Mn]) and trace element (arsenic [As], chromium [Cr], copper [Cu], mercury [Hg], lithium [Li], lead [Pb], rubidium [Rb], tin [Sn], and zinc [Zn]) concentrations. Factor analysis was used to decrease 22 selected variables into 4 factors accounting for 85.9 % of the total variance explained, suggesting distinct elemental sources or sediment components affecting their spatial distributions. Although factors 1 (detrital component; elements strongly associated with fine- [Na, Mg, Ti, Li, Cr, Cu, Fe, Al, Zn, Ca, and As] and coarse-grained sediments [Si, K, Rb; mean grain-size [MGS]) and 3 (Fe-Mn oxyhydroxide sediment component; Fe, Mn, As, fine fraction) are interpreted as reflecting predominance of natural contributions, factors 2 (urban and industrial contamination: sediment components [Pb, Hg, organic carbon [Corg], total nitrogen [Ntot] and 4 (components associated with contamination by nautical activities; the association of tin [Sn] and calcium [Ca]) seem to indicate anthropogenic contributions). Nevertheless, the influence of elemental contributions derived from tungsten (W)-Sn mineralizations and those resulting from mining activities can also contribute to the obtained geochemical associations and should be considered. Spatial distribution of dominant factor scores shows the dominance of factors 2 and 4 between Tui and Vila Nova de Cerveira, whereas samples dominated by factors 3 and 1 are found between Ilha da Boega and Seixas and in the Caminha areas, respectively. Despite the dominance of factor score 1 in the Caminha area, the distribution pattern of dominant factor scores shows samples dominated by other factor scores that can be explained by dredging activities in this river sector that restore ancient sedimentary characteristics or expose contaminated sediments. Through the identification of sample locations dominated by factors associated with contamination, it will be possible to select them as priority areas where new environmental (e.g., toxicity tests, organic Sn compounds, tracers of sewage contamination) studies should be implemented in the future. PMID:23299253

Mil-Homens, M; Costa, A M; Fonseca, S; Trancoso, M A; Lopes, C; Serrano, R; Sousa, R

2013-01-09

263

Characterization of heavy-metal contamination in surface sediments of the Minho river estuary by way of factor analysis.  

UK PubMed Central (United Kingdom)

Surface sediments were collected in August 2009 from 49 sites along the Minho estuary (between Tui and Caminha) and analyzed for grain size, organic carbon (Corg) and total nitrogen (Ntot) contents, and major (silicon [Si], aluminum [Al], iron [Fe], calcium [Ca], magnesium [Mg], sodium [Na], potassium [K], titanium [Ti], and mangesese [Mn]) and trace element (arsenic [As], chromium [Cr], copper [Cu], mercury [Hg], lithium [Li], lead [Pb], rubidium [Rb], tin [Sn], and zinc [Zn]) concentrations. Factor analysis was used to decrease 22 selected variables into 4 factors accounting for 85.9 % of the total variance explained, suggesting distinct elemental sources or sediment components affecting their spatial distributions. Although factors 1 (detrital component; elements strongly associated with fine- [Na, Mg, Ti, Li, Cr, Cu, Fe, Al, Zn, Ca, and As] and coarse-grained sediments [Si, K, Rb; mean grain-size [MGS]) and 3 (Fe-Mn oxyhydroxide sediment component; Fe, Mn, As, fine fraction) are interpreted as reflecting predominance of natural contributions, factors 2 (urban and industrial contamination: sediment components [Pb, Hg, organic carbon [Corg], total nitrogen [Ntot] and 4 (components associated with contamination by nautical activities; the association of tin [Sn] and calcium [Ca]) seem to indicate anthropogenic contributions). Nevertheless, the influence of elemental contributions derived from tungsten (W)-Sn mineralizations and those resulting from mining activities can also contribute to the obtained geochemical associations and should be considered. Spatial distribution of dominant factor scores shows the dominance of factors 2 and 4 between Tui and Vila Nova de Cerveira, whereas samples dominated by factors 3 and 1 are found between Ilha da Boega and Seixas and in the Caminha areas, respectively. Despite the dominance of factor score 1 in the Caminha area, the distribution pattern of dominant factor scores shows samples dominated by other factor scores that can be explained by dredging activities in this river sector that restore ancient sedimentary characteristics or expose contaminated sediments. Through the identification of sample locations dominated by factors associated with contamination, it will be possible to select them as priority areas where new environmental (e.g., toxicity tests, organic Sn compounds, tracers of sewage contamination) studies should be implemented in the future.

Mil-Homens M; Costa AM; Fonseca S; Trancoso MA; Lopes C; Serrano R; Sousa R

2013-05-01

264

Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions  

Science.gov (United States)

Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized using a variety of techniques, including elemental (C and N) ratio, bulk stable organic carbon isotopic composition (?13C), and carbohydrate composition analyses. Total organic carbon (TOC) content was 1.21±0.45% in the upper reach, down to 1.00±0.22% in Lingdingyang Bay and to 0.80±0.10% on the inner shelf and 0.58±0.06% on the outer shelf. ?13C values ranged from -25.1‰ to -21.3‰ in Lingdingyang Bay and the South China Sea shelf, with a trend of enrichment seawards. The spatial trend in C/N ratios mirrored that of ?13C, with a substantial decrease in C/N ratio offshore. Total carbohydrate yields ranged from 22.1 to 26.7 mg (100 mg OC)-1, and typically followed TOC concentrations in the estuarine and shelf sediments. Total neutral sugars, as detected by the nine major monosaccharides (lyxose, rhamnose, ribose, arabinose, fucose, xylose, galactose, mannose, and glucose), were between 4.0 and 18.6 mg (100 mg OC)-1 in the same sediments, suggesting that significant amounts of carbohydrates were not neutral aldoses. Using a two end-member mixing model based on ?13C values and C/N ratios, we estimated that the terrestrial organic carbon contribution to the surface sediment TOC was ca. 78±11% for Lingdingyang Bay, 34±4% for the inner shelf, and 5.5±1% for the outer shelf. The molecular composition of the carbohydrate in the surface sediments also suggested that the inner estuary was rich in terrestrially derived carbohydrates but that their contribution decreased offshore. A relatively high abundance of deoxyhexoses in the estuary and shelf indicated a considerable bacterial source of these carbohydrates, implying that sediment organic matter had undergone extensive degradation and/or transformation during transport. Sediment budget based on calculated regional accumulation rates showed that only ~50% of the influxes of terrestrial organic carbon were accumulated in the estuary. This relatively low accumulation efficiency of terrestrial organic matter as compared to the total suspended solids (accumulation efficiency ~73%) suggested significant degradation of the terrestrial organic carbon within the estuarine system after its discharge from the river. This study demonstrated that the combination of the bulk organic matter properties together with the isotopic composition and molecular-level carbohydrate compositions can be an efficient way to track down the source and fate of organic matter in highly dynamic estuarine and coastal systems. The predominance of terrestrially originated organic matter in the sediment and its generally low accumulation efficiency within the estuary is not surprising, and yet it may have important implications in light of the heavy anthropogenic discharges into the Pearl River Estuary during the past thirty years.

He, B.; Dai, M.; Huang, W.; Liu, Q.; Chen, H.; Xu, L.

2010-10-01

265

Caracterización hidrográfica del estuario del río Valdivia, centro-sur de Chile/ Hydrographic features of Valdivia river estuary south-central Chile  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La costa sureste del Océano Pacífico entre 37° y 41°S, se caracteriza por la presencia de un gran número de estuarios micromareales (rango mareal menor a 2 m). Uno de los estuarios más importantes dentro de estas latitudes es el estuario del río Valdivia, cuya estructura y dinámica termal y halina es poco conocida. Mediante mediciones hidrográficas de temperatura y salinidad tomadas durante un ciclo estacional anual y el análisis de sus principales forzantes (ma (more) rea, caudal del río, vientos y radiación solar) se explica la variabilidad así como sus cambios en la estratificación vertical. El análisis de la estructura termohalina de la columna de agua reveló que el estuario varió estacionalmente comportándose como un estuario de cuña salina en invierno y primavera producto del mayor caudal de los ríos afluentes, mientras que en verano y otoño se comportó como parcialmente mezclado, producto del menor caudal de los ríos. En invierno y primavera la columna de agua presentó inversión térmica, la cual fue asociada a pérdida de calor superficial y a la advección sub-superficial de aguas cálidas desde el océano adyacente hacia el interior del estuario que no se mezclaron con las de la superficie debido a la intensa estratificación salina. El cambio en el régimen estuarino de cuña salina a parcialmente mezclado según la estación del año y presencia de la inversión térmica estacional, son características hidrográficas necesarias tanto para la implementación de esfuerzos de conservación de hábitat vulnerables presentes en la zona (áreas de crianza de juveniles de especies explotadas), como para la utilización de este sistema para actividades de acuicultura y manejo de recursos marinos. Abstract in english The area between 37° and 41°S of the southeastern Pacific coast, have a great number of microtidal (tidal range less than 2 m) estuaries. One of the most important estuaries in these latitudes is the Valdivia River estuary, whose thermal and haline structure is poorly known. Thus, this work, through hydrographic measurements of temperature and salinity taken during an annual seasonal cycle and the analysis of the main forcings (tide, river flow, wind and solar radiation (more) ) explain the variability and its changes in vertical stratification. The analysis of the the thermohaline structure of the water column revealed that the estuary varied seasonally behaving like a salt-wedge estuary in winter and spring due to a higher flow of tributaries. However, in summer and autumn behaved as partially mixed due the lower river flow. In winter and spring the water column showed a temperature inversion which was associated with a large surface heat loss and subsurface advection of warm waters from the adjacent ocean to into the estuary that is not mixed with the surface due to intense stratification by salinity. The change in the estuarine salt-wedge regime to partially mixed according to the season and the presence of thermal inversion seasonal are necessary hydrographic features to implement conservation efforts of vulnerable habitat into the zone (nursery areas of juvenile species), and use of this system for aquaculture activities and marine resources management.

Garcés-Vargas, José; Ruiz, Marcela; Pardo, Luis Miguel; Nuñez, Sergio; Pérez-Santos, Iván

2013-03-01

266

Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions  

Directory of Open Access Journals (Sweden)

Full Text Available Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized using a variety of techniques, including elemental (C and N) ratio, bulk stable organic carbon isotopic composition (?13C), and carbohydrate composition analyses. Total organic carbon (TOC) content was 1.21±0.45% in the upper reach, down to 1.00±0.22% in Lingdingyang Bay and to 0.80±0.10% on the inner shelf and 0.58±0.06% on the outer shelf. ?13C values ranged from ?25.1‰ to ?21.3‰ in Lingdingyang Bay and the South China Sea shelf, with a trend of enrichment seawards. The spatial trend in C/N ratios mirrored that of ?13C, with a substantial decrease in C/N ratio offshore. Total carbohydrate yields ranged from 22.1 to 26.7 mg (100 mg OC)?1, and typically followed TOC concentrations in the estuarine and shelf sediments. Total neutral sugars, as detected by the nine major monosaccharides (lyxose, rhamnose, ribose, arabinose, fucose, xylose, galactose, mannose, and glucose), were between 4.0 and 18.6 mg (100 mg OC)?1 in the same sediments, suggesting that significant amounts of carbohydrates were not neutral aldoses. Using a two end-member mixing model based on ?13C values and C/N ratios, we estimated that the terrestrial organic carbon contribution to the surface sediment TOC was ca. 78±11% for Lingdingyang Bay, 34±4% for the inner shelf, and 5.5±1% for the outer shelf. The molecular composition of the carbohydrate in the surface sediments also suggested that the inner estuary was rich in terrestrially derived carbohydrates but that their contribution decreased offshore. A relatively high abundance of deoxyhexoses in the estuary and shelf indicated a considerable bacterial source of these carbohydrates, implying that sediment organic matter had undergone extensive degradation and/or transformation during transport. Sediment budget based on calculated regional accumulation rates showed that only ~50% of the influxes of terrestrial organic carbon were accumulated in the estuary. This relatively low accumulation efficiency of terrestrial organic matter as compared to the total suspended solids (accumulation efficiency ~73%) suggested significant degradation of the terrestrial organic carbon within the estuarine system after its discharge from the river. This study demonstrated that the combination of the bulk organic matter properties together with the isotopic composition and molecular-level carbohydrate compositions can be an efficient way to track down the source and fate of organic matter in highly dynamic estuarine and coastal systems. The predominance of terrestrially originated organic matter in the sediment and its generally low accumulation efficiency within the estuary is not surprising, and yet it may have important implications in light of the heavy anthropogenic discharges into the Pearl River Estuary during the past thirty years.

B. He; M. Dai; W. Huang; Q. Liu; H. Chen; L. Xu

2010-01-01

267

Meroplankton spatial and temporal variability at the Piraquê- açú river estuary, Aracruz, Espírito Santo State. Variação espaço-temporal do meroplâncton no estuário do rio Piraquê-açú, Aracruz, Espírito Santo  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Meroplankton was studied at the Piraquê-açú River Estuary, city of Aracruz, State of Espírito Santo, with the aim to understand their temporal and spatial distribution in the environment. Samples were collected monthly (between May and December 2003) in four sampling locations distributed along the ...

R. A. Magris; L. Loureiro Fernandes

268

Dissolved oxygen in contrasting estuaries of the Bay of Biscay:effects of temperature, river discharge and chlorophyll a  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effects of environmental factors on variations of dissolved oxygen (DO) saturation was assessed in 2 estuaries (Bilbao and Urdaibai) in the Bay of Biscay with contrasting hydrography and anthropogenic impact, for the period 1997 to 2006, using generalised additive models (GAMs) and generalised a...

Iriarte, Arantza; Aravena, Guillermo; Villate, Fernando; Uriarte, Ibon; Ibáñez, Berta; Llope, Marcos; Stenseth, Nils Christian

269

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 showed that the sediment was enriched with Cd, Zn, Cu and Pb. The results of geo-accumulation index (Igoe) indicated that sediments are unpolluted with Fe, moderately polluted with Cr, Cu, Pb, strongly polluted with Cd and extremely polluted with Ni. This was attributed mainly to oil contaminating wastes and metal scraps. The results of the modified degree of contamination (mCd) revealed that the sediment of Qua Iboe estuary and associated creeks fall between 8 ? mCd ? 16 indicating very high degree of contamination.

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

2013-01-01

270

Potential remobilization of 137Cs, 60Co, 90Tc, and 90Sr from contaminated Mayak sediments in river and estuary environments.  

Science.gov (United States)

Following 50 years of nuclear production at Mayak PA, sediments in storage reservoirs are significantly contaminated. Dam failure or flooding could potentially transport large amounts of sediments, via rivers, to the Ob estuary and Kara Sea. The objectives of this work were to investigate fresh and seawater remobilization of 137Cs, 50Co, 99Tc, and 90Sr from contaminated Reservoir 10 sediments. Sediments were extracted sequentially using synthetic Techa freshwater, seawater, and chemical reagents with increasing dissolution powers. 137Cs and 90Sr freshwater distribution coefficients (apparent Kd) agreed quite well with published values; values for 99Tc were higher and values for 60Co were lower than expected. In seawater, mean apparent Kd values decreased by 94, 77, 48, and 73% (137Cs, 60Co, 99Tc, and 90Sr, respectively), indicating increased radionuclide mobility. Remobilization in seawater was 5, 15, 1, and 23% of total activities (i.e., releases of 165, 11, 0.3, and 170 kBq kg(-1) d.w.) for 137Cs, 60Co, 99Tc, and 90Sr, respectively. 137Cs and 99Tc were strongly bound to sediments (60% and 80%, respectively). 60Co and 90Sr were more mobile (70% reversibly bound). In conclusion, Mayak Reservoir sediments could potentially contaminate the Ob estuary due to remobilization of sediment-held radionuclides upon contact with seawater. PMID:12075786

Standring, William J F; Oughton, Deborah H; Salbu, Brit

2002-06-01

271

Potential remobilization of 137Cs, 60Co, 90Tc, and 90Sr from contaminated Mayak sediments in river and estuary environments.  

UK PubMed Central (United Kingdom)

Following 50 years of nuclear production at Mayak PA, sediments in storage reservoirs are significantly contaminated. Dam failure or flooding could potentially transport large amounts of sediments, via rivers, to the Ob estuary and Kara Sea. The objectives of this work were to investigate fresh and seawater remobilization of 137Cs, 50Co, 99Tc, and 90Sr from contaminated Reservoir 10 sediments. Sediments were extracted sequentially using synthetic Techa freshwater, seawater, and chemical reagents with increasing dissolution powers. 137Cs and 90Sr freshwater distribution coefficients (apparent Kd) agreed quite well with published values; values for 99Tc were higher and values for 60Co were lower than expected. In seawater, mean apparent Kd values decreased by 94, 77, 48, and 73% (137Cs, 60Co, 99Tc, and 90Sr, respectively), indicating increased radionuclide mobility. Remobilization in seawater was 5, 15, 1, and 23% of total activities (i.e., releases of 165, 11, 0.3, and 170 kBq kg(-1) d.w.) for 137Cs, 60Co, 99Tc, and 90Sr, respectively. 137Cs and 99Tc were strongly bound to sediments (60% and 80%, respectively). 60Co and 90Sr were more mobile (70% reversibly bound). In conclusion, Mayak Reservoir sediments could potentially contaminate the Ob estuary due to remobilization of sediment-held radionuclides upon contact with seawater.

Standring WJ; Oughton DH; Salbu B

2002-06-01

272

Design and Analysis of Salmonid Tagging Studies in the Columbia Basin : Evaluating Wetland Restoration Projects in the Columbia River Estuary using Hydroacoustic Telemetry Arrays to Estimate Movement, Survival, and Residence Times of Juvenile Salmonids, Volume XXII (22).  

Energy Technology Data Exchange (ETDEWEB)

Wetlands in the Columbia River estuary are actively being restored by reconnecting these habitats to the estuary, making more wetland habitats available to rearing and migrating juvenile salmon. Concurrently, thousands of acoustically tagged juvenile salmonids are released into the Columbia River to estimate their survival as they migrate through the estuary. Here, we develop a release-recapture model that makes use of these tagged fish to measure the success of wetland restoration projects in terms of their contribution to populations of juvenile salmon. Specifically, our model estimates the fraction of the population that enter the wetland, survival within the wetland, and the mean residence time of fish within the wetland. Furthermore, survival in mainstem Columbia River downstream of the wetland can be compared between fish that remained the mainstem and entered the wetland. These conditional survival estimates provide a means of testing whether the wetland improves the subsequent survival of juvenile salmon by fostering growth or improving their condition. Implementing such a study requires little additional cost because it takes advantage of fish already released to estimate survival through the estuary. Thus, such a study extracts the maximum information at minimum cost from research projects that typically cost millions of dollars annually.

Perry, Russell W.; Skalski, John R.

2008-08-01

273

Fluxes of nitrous oxide and methane in different coastal Suaeda salsa marshes of the Yellow River estuary, China.  

UK PubMed Central (United Kingdom)

The spatial and temporal variations of the fluxes of nitrous oxide (N(2)O) and methane (CH(4)) and associated abiotic sediment parameters were quantified for the first time across the coastal marsh dominated by Suaeda salsa in the Yellow River estuary during 2009/2010. During all times of day and the seasons measured, N(2)O and CH(4) fluxes from coastal marsh ranged from -0.0147 mg N(2)O m(-2) h(-1) to 0.0982 mg N(2)O m(-2) h(-1) and -0.7421 mg CH(4) m(-2) h(-1) to 0.4242 mg CH(4) m(-2) h(-1), respectively. The mean N(2)O fluxes in spring, summer, autumn and winter were 0.0325 mg N(2)O m(-2) h(-1), 0.0089 mg N(2)O m(-2) h(-1), 0.0119 mg N(2)O m(-2) h(-1) and 0.0140 mg N(2)O m(-2) h(-1), and the average CH(4) fluxes were -0.0109 mg CH(4) m(-2) h(-1), -0.0174 mg CH(4) m(-2) h(-1), -0.0141 mg CH(4) m(-2) h(-1) and -0.0089 mg CH(4) m(-2) h(-1), respectively, indicating that the coastal marsh acted as N(2)O source and CH(4) sink. Both N(2)O and CH(4) fluxes differed significantly between times of day of sampling. N(2)O fluxes differed significantly between sampling seasons as well as between sampling positions, while CH(4) fluxes had no significant differences between seasons or positions. Temporal variations of N(2)O emissions were probably related to the effects of vegetation (S. salsa) during summer and autumn and the frequent freeze/thaw cycle of sediment during spring and winter, while those of CH(4) fluxes were controlled by the interactions of thermal conditions and other abiotic factors (soil moisture and salinity). Spatial variations of N(2)O and CH(4) fluxes were primarily affected by soil moisture fluctuation derived from astronomic tide, sediment substrate and vegetation composition. N(2)O and CH(4) fluxes, expressed as CO(2)-equivaltent (CO(2)-e) emissions, showed that N(2)O comprised the principal part of total calculated CO(2)-e emissions during spring and winter, while the contributions of CH(4) could not be ignored during summer and autumn. This study highlights the importance of seasonal N(2)O and CH(4) contributions, particularly during times of significant CH(4) consumption. For the accurate up-scaling of N(2)O and CH(4) fluxes to annual rates, a careful sampling design at site-level is required to capture the potentially considerable temporal and spatial variations of N(2)O and CH(4) emissions.

Sun Z; Wang L; Tian H; Jiang H; Mou X; Sun W

2013-01-01

274

Preliminary assessment of heavy metal levels in Mytella falcata (Bivalvia, Mytilidae) from Bacanga River estuary, São Luis, State of Maranhão, Northeastern Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available The concentrations of Cu, Zn, Pb, and Cd were determined in the mussel Mytella falcata from the Bacanga River estuary, in order to evaluate the potential role of domestic effluents released "in natura" on the quality of the estuarine environment with consequences to shellfish resources. Cu concentrations ranged from 5.2 mg.g-1 to 13.1 mg.g-1, while Zn concentrations ranged from 49.1 mg.g-1 to 76.3 mg.g-1. Pb and Cd showed concentrations lower than 2 mg.g-1. The results showed low concentrations of Cu, Pb and Cd in the filter-feeding Mytella falcata in the study area in comparison with the maximum values stablished to foods by the Brazilian Government (Decree Law Nº 55,871). Finally, Zn presented slightly higher values than the maximum ones stablished by the Brazilian government.

CARVALHO G. P. de; CAVALCANTE P. R. S.; CASTRO A. C. L. de; ROJAS M. O. A. I.

2000-01-01

275

Protist 18S rRNA gene Sequence Analysis Reveals Multiple Sources of Organic Matter Contributing to Turbidity Maxima of the Columbia River Estuary  

Energy Technology Data Exchange (ETDEWEB)

The Columbia River estuary is traditionally considered a detritus-based ecosystem fueled in summer by organic matter (OM) from expired freshwater diatoms. Since Estuarine Turbidity Maxima (ETM) are sites of accumulation and transformation of this phytoplankton-derived OM, to further characterize the ETM protist assemblage, we collected in August 2007 bottom waters throughout an ETM event, as well as surface water during the peak of bottom turbidity, and performed biogeochemical, microscopic and molecular (18S rRNA gene clone libraries) analyses. These data confirmed that the majority of the particulate OM in ETMs is derived from chlorophyll a-poor particulate organic carbon tagged by DNA too damaged to be detected by molecular analysis.

Herfort, Lydie; Peterson, Tawnya D.; McCue, Lee Ann; Zuber, Peter A.

2011-10-05

276

Linking Species Traits to the Abiotic Template of Flowing Waters: Contrasting Eco physiologies Underlie Displacement of Zebra Mussels by Quagga Mussels in a Large River-Estuary  

Science.gov (United States)

The St. Lawrence River-Estuary was the gateway of entry for dreissenids to North America and holds some of the oldest populations. The St. Lawrence also has four distinct physical-chemical water masses (a regional scale abiotic template) that both species inhabit. Despite their ecological similarities, quagga mussels are supplanting zebra mussels in much of their shared range. In order to try to better understand the changing distributions of these two species we compared glycogen, shell mass and tissue biomass in each of the water masses. This comparative physiological combined with experimental approaches (estuarine salinity experiments and reciprocal transplants) showed that while quagga mussels should dominate in most habitats, that abiotic/bioenergetic constraints in two regions (the Ottawa River plume and the freshwater-marine transition zone) might prevent them from dominating these locations. These findings are an example of how the interaction of landscape scale abiotic heterogeneity and a species-specific physiology can have strong impacts of distribution of biota large rivers.

Casper, A. F.

2005-05-01

277

TRANSIT TIME IN ITAJAÍ-AÇÚ RIVER ESTUARY ESTIMAÇÃO DO TEMPO DE TRÂNSITO DAS ÁGUAS NO ESTUÁRIO DO RIO ITAJAÍ-AÇÚ  

Directory of Open Access Journals (Sweden)

Full Text Available The Itajaí-Açu estuary is classified as a highly stratified and presents most of the time a salt wedge. Considering this characteristic, it was used a box model, based on Knudsen hidrographic teorem, to estimate the salt balance and the transit time of fluvial and marine waters in this estuary. This model enables to verify the steady state of mixture conditions and should not be confused as the mean conditions of the estuary. A positive characteristic of this model is that it needs a small number of parameters such as salinity profiles, the estuary volume and currents data, being the latter estimated from river discharge. Seven days of data were assessed, comprising a half synodical cycle (spring-neap tide). Vertical velocities data, estimated by the model, showed that spring tide condition causes a more effective mixing. It was stated a ratio of content of fluvial water to the content of mixohaline water, which confirmed the early findings of intensification of mixing during spring tide period. The estimation of the transit time of fluvial and marine water in the estuary for medium discharge condition, ~ 215 m3.s-1, were 13.2 and 50.7 hours, respectively. It shows that the marine water spends 3 times more time in the estuary than the fluvial water. O Estuário do rio Itajaí-Açu é um estuário altamente estratificado, e apresenta durante a maior parte do ano uma proeminente cunha salina. Devido a esta característica foi possível aplicar o modelo de caixa, baseado no teorema hidrográfico de Knudsen, para se estimar o balanço salino e o tempo de trânsito das águas fluvial e marinha no estuário. Este modelo possibilita verificar o estado estático das condições de mistura no estuário e não deve ser confundido com as condições médias do estuário. Uma característica positiva deste modelo é o fato dele precisar de um numero pequeno de parâmetros, como perfil de salinidade, volume do estuário e dados de corrente, estes últimos estimados a partir de dados de descarga fluvial. Foram analisados sete dias de dados, compreendendo um ciclo completo de maré (sizígia-quadratura). Dados de velocidade vertical, estimados pelo modelo, mostraram que as condições de maré de sizígia causam um maior grau de mistura. Para confirmar isto foi definido um coeficiente de mistura dado pela razão do conteúdo de água fluvial pelo de água de mistura, o que comprovou tal padrão. Quanto ao tempo de transito, verificou-se que em situações de média descarga, cerca de 215 m3.s-1, o tempo de trânsito da água marinha foi três vezes maior do que o da água fluvial. Os valores estimados foram de 13.2 horas para a água fluvial e 50.7 horas para água marinha.

A. R. ZALESKI; C A SCHETTINI

2003-01-01

278

Temporal variability of stable carbon and nitrogen isotopic composition of size-fractionated particulate organic matter in the hypertrophic Sumida River Estuary of Tokyo Bay, Japan  

Science.gov (United States)

To clarify the major factors that control stable carbon and nitrogen isotopic compositions (? 13C and ? 15N) of suspended particulate organic matter in a hypertrophic estuary, seasonal variation in concentrations and stable isotopic compositions of particulate organic carbon and nitrogen (POC, PN), chlorophyll a content (Chl) and dry weight of suspended solid (SS) was studied in the Sumida River estuary of Tokyo Bay. Particulate material was fractioned into four size-fractions (3-20, 20-53, 53-250, 250-1000 ?m). At the lower-estuarine (LE) site, the finer size fraction (80% Chl) during the autumnal bloom (Aug-Sep 2003). The middle size fractions (20-53 and 53-250 ?m) however increased during the spring bloom (50-80% Chl; Feb-Apr 2004), reflecting difference in taxonomic composition of phytoplankton. At the upper-estuarine and the riverine sites, the <20 ?m fraction was most abundant throughout the survey period. ? 13C POC and ? 15N PN varied between -32 and -16‰ and between -8 and +12‰, respectively. Relationships of ? 13C POC with POC/Chl and POC/PN ratios could be explained by assuming two end members: allochthonous (terrestrial) POC with a ? 13C close to -26.5‰, and autochthonous (planktonic) POC whose ? 13C was variable and apparently correlated with ? 13C of ambient DIC (-10 to 0‰) and phytoplankton abundance (Chl). ? 15N PN was apparently controlled by water temperature and NH 4+ concentration. The variability of ? 13C and ? 15N was different between size fractions: the apparent dependence of ? 13C on Chl as well as that of ? 15N on water temperature was significantly stronger for the middle size fractions (mainly diatoms) than the finer fraction (mainly microflagellates), suggesting different physiological response between taxa. The second objective of this study was to evaluate contribution of terrestrial organic carbon (TPOC) to the POC size fractions by using ? 13C of isolated chlorophyll a at LE site as surrogate for the autochthonous ? 13C end member. During the autumnal bloom, TPOC was 23-36% on average for the middle size fractions (20-53 and 53-250 ?m), and ?59% for the finest (3-20 ?m) and coarsest (250-1000 ?m) fractions. During the spring bloom, the average contribution of TPOC was generally low (?21%) except for the finest fraction (36%). Negative correlation between salinity and calculated TPOC suggested that transport of terrestrial organic carbon to this estuary was controlled principally by the river discharge.

Sato, Taeko; Miyajima, Toshihiro; Ogawa, Hiroshi; Umezawa, Yu; Koike, Isao

2006-06-01

279

General description of the Scheldt estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A general description of the Scheldt estuary, including the hydrology, the sediment transport, the productivity and the biodegradation with respect to their influence on the trace metal behaviour in the Scheldt estuary, is given. The river basin can be divided in several sections according to their ...

Baeyens, W.F.J.; Van Eck, B.T.M.; Lambert, C.; Wollast, R.; Goeyens, L.

280

Suspended matter in the Scheldt estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Scheldt estuary is characterised by a specific energy pattern resulting from the interaction of wave energy, tidal energy and river energy. It divides the estuary into three parts and governs suspended matter transport and distribution pattern. Observation of suspended matter transport shows the...

Chen, M.S.; Wartel, S.; Van Eck, B.T.M.; van Maldegem, D.

 
 
 
 
281

Cirripedia Balanomorpha del estuario del Río Paripe (Isla de Itamaracá, Pernambuco, Brasil)/ Cirripedia Balanomorpha of Paripe River estuary (Itamaracá Island, Pernambuco, Brazil)  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Los cirrípedos son animales característicos y abundantes en la región intermareal de los ambientes marinos y estuarinos de todo el mundo, pero son poco conocidos en las áreas de manglares tropicales. El presente estudio fue realizado con el objetivo de conocer las especies de cirrípedos en el estuario del Río Paripe (Pernambuco - Brasil), señalando algunas características de su distribución a lo largo del estuario. En la estación de estiaje de 2006, los animales (more) fueron colectados en tres estaciones del estuario, en todos los substratos duros disponibles, observando su distribución vertical en los mismos. En la estación polihalina (salinidades variando de 28,7 hasta 36,1), se encontraron ocho especies: Amphibalanus amphitrite, A. improvisus, A. reticulatus, A. venustus, Chthamalus proteus, C. bisinuatus, Microeuraphia rhizophorae y Striatobalanus amaryllis. Las especies clasificadas como eurihalinas, encontradas hasta la región mesohalina del estuario (salinidades variando de 10,8 hasta 19,6) fueran: Amphibalanus amphitrite, A. improvisus, A. reticulatus, Chthamalus proteus y Microeuraphia rhizophorae, mientras que en la región oligohalina (salinidades variando de 0,2 hasta 5,2), solamente M. rhizophorae estuvo presente, sendo por tanto, clasificada como componente estuarino. Una zonación horizontal de especies de cirrípedos fue claramente observada a partir de la desembocadura hasta al montante del río, con disminución gradual del número de especies y fue confirmado su padrón de distribución vertical en relación a las alturas de mareas, observadas las respectivas valencias ecológicas. Las especies exóticas introducidas en Brasil, Amphibalanus reticulatus y Striatobalanus amaryllis, estaban bien adaptadas en los substratos naturales y artificiales del estuario. Abstract in english Barnacles are animals characteristic and abundant of intertidal region on marine and estuarine environments worldwide, but they are little known in the areas of tropical mangroves. This study was done with the aim to know the barnacles' species of the estuary of the Paripe River (Pernambuco, Brazil), indicating some characteristics of its distribution throughout the estuary. In dry season of 2006, the animals were collected in three stations of the estuary, in all hard su (more) bstrata available, observing their vertical distribution. In polihaline station (salinities varying from 28.7 to 36.1), it was found eight species: Amphibalanus amphitrite, A. improvisus, A. reticulatus, A. venustus, Chthamalus proteus, C. bisinuatus, Microeuraphia rhizophorae and Striatobalanus amaryllis. The species classified as euryhaline, found until the mesohaline region of the estuary (salinities varying from 10.8 to 19.6) were: Amphibalanus amphitrite, A. improvisus, A. reticulatus, Chthamalus proteus and Microeuraphia rhizophorae, whereas in the oligohaline region (salinities varying from 0.2 to 5.2), only M. rhizophorae was present, being classified as estuarine component. A horizontal zonation of species of barnacles was clearly observed from the mouth until the upstream, with gradual decrease of number of species and it was confirmed their pattern of vertical distribution in relation to the height of tides, according with its respective ecological valences. The introduced exotic species in Brazil, Amphibalanus reticulatus and Striatobalanus amaryllis, were well adapted on natural and artificial substrata of the estuary.

Farrapeira, Cristiane Maria Rocha

2008-09-01

282

The transition from wave-dominated estuary to wave-dominated delta: The Late Quaternary stratigraphic architecture of Tiber River deltaic succession (Italy)  

Science.gov (United States)

This paper presents a detailed description of the stratigraphic architecture of the Late Pleistocene/Holocene Tiber delta succession in order to document the passage from wave-dominated estuary to wave-dominated delta in the broader context of Late Quaternary sea level fluctuations.This succession constitutes a sequence-stratigraphic unit known as Tiber Depositional Sequence (TDS), which was deposited during the last glacial-interglacial cycle (last 120 ka). Our study is based on the examination of an enormous amount of data derived from the stratigraphy of about 300 wells, petrographical and paleontological data (foraminifera, ostracoda, pollen, and plant macrofossils), 14C dating, and from the integration of geomorphological and geoarcheological data. Recently a 100 m deep core (Pesce Luna well) was studied through a multidisciplinary approach and a detailed description of sedimentary facies, foraminifer and ostracod assemblages, pollen and 14C dating is presented in this paper. The new data allowed to produce three new correlation panels and to describe in more detail, with respect to previous interpretations, the stratigraphic-depositional architecture of the TDS, which internally shows the preservation of sediment deposited during the early and late lowstand, the transgressive and the highstand systems tracts. Alluvial and coastal depositional systems characterize the early lowstand phase of the TDS, which developed during the eustatic sea-level fall between about 120 and 30-26 yr BP. During the late lowstand phase, which is characterized by stillstand and slow eustatic sea-level rise a prograding delta and an aggrading incised-valley fluvial fill developed. The Tiber incised valley was transformed into a wave-dominated estuary during the transgressive phase (TST), whereas a coastal-shelf sedimentation took place during the subsequent highstand phase (HST). This study confirms the lithofacies distribution resulting from transgression and infilling of the wave-dominated estuaries, but also shows how the transition to a wave-dominated delta, prograding at the time of sea-level highstand occurred. Changes in sediment input, climatic variations and, more recently, human activities played a major role in the development of the Tiber delta during the last 20,000 yr BP. In the last 3000 years a relationship between progradational phases of the delta and flood events of the Tiber river has been highlighted, suggesting also the formation and merging of barrier-spits to the mainland.

Milli, Salvatore; D'Ambrogi, Chiara; Bellotti, Piero; Calderoni, Gilberto; Carboni, Maria Gabriella; Celant, Alessandra; Di Bella, Letizia; Di Rita, Federico; Frezza, Virgilio; Magri, Donatella; Pichezzi, Rita Maria; Ricci, Valeria

2013-02-01

283

Organic fluxes of Cameroonian rivers into the Gulf of Guinea: a quantitative approach to biodegradation in estuary and plume  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The modern organic carbon flux of the Sanaga River and the rivers around the Bay of Douala is estimated to be 0.62-0.79 x 10(6) t yr(-1). In reality, mean Holocene sedimentation of organic carbon, including a presumed low biological production in the euphotic zone, is only 41-52 % of this-value. Sub...

Giresse, P; Cahet, G

284

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 identific...

T.K. Gyedu-Ababio

285

Integration of shelf evolution and river basin models to simulate Holocene sediment dynamics of the Humber Estuary during periods of sea-level change and variations in catchment sediment supply.  

UK PubMed Central (United Kingdom)

Three modelling elements and sedimentary evidence provide an understanding of sediment characteristics, river basin processes, tidal regimes and sea-level changes to explain sediment supply to the Humber Estuary through the Holocene (the last 10,000 years). An upscaled cellular catchment model simulates water and sediment fluxes from river basins, illustrating significant variations in response to climate change, especially precipitation and vegetation changes, principally deforestation. Much of the sediment mobilised remains in stores within the catchment and only a small fraction reaches the Humber tidal system. An empirical model helps to explain sediment erosion, transport and deposition from the offshore and coastal zones through the Holocene and sea-level rise caused the transgression of the continental shelf of the North Sea. Comparison with the sediment fill of the lowlands around of the Humber estuary, that represent the extent of the estuary during the Holocene, demonstrates that most of the fill (approximately 95-98%) was derived from non-fluvial sources. A shelf evolution model, with reconstructions of sea level, palaeogeography and palaeobathymetry for 1,000 year time steps through the Holocene predicts significant changes in tidal regimes, first over wide areas of the coast as the transgression of the continental shelf progresses. The most significant changes occur with the inner reaches of the palaeo-estuaries, especially those of the Humber and the Fenland. Throughout the mid-Holocene they are characterised by significantly lower tidal ranges (MWHST approximately 2.5 m less than present) and low tidal currents. The simulated patterns of tidal currents concur with the transport of fine grain sediment from the coastal zone into the estuaries. The major tidal range changes revise estimates of late Holocene and ongoing relative sea and land level changes.

Shennan I; Coulthard T; Flather R; Horton B; Macklin M; Rees J; Wright M

2003-10-01

286

Diversity of bird communities in southern Hangzhou Bay and the Qiantang River estuary and their responses to reclamation of intertidal mudflats  

Directory of Open Access Journals (Sweden)

Full Text Available Bird communities were surveyed in southern Hangzhou Bay and the Qiantang River estuary from November 2008 to September 2011. A total of 220 bird species belonging to 16 orders and 52 families were recorded, of which, 173 (78.6%) were migrants and 24 were listed as state key protected wildlife grade I or II. The composition and diversity of bird communities in eight habitat types were compared using the G-F index and the Jaccard index. Ninety-five species (43.2%) were observed in the ponds located in Cixi Wetland Centre with common reed (Phragmites australis) marshes, 93 species (42.3%) in the coastal woodland, and 78 species (35.5%) in intertidal mudflats and coastal reservoirs. About 82.5% of the Charadriiformes species were recorded in intertidal mudflats; 69.2% of the Anatidae species in coastal reservoirs, and 73.4% of the Passeriformes species in the coastal woodland which provides the breeding habitat for the Ardeidae birds. Compared with intertidal mudflats, the highest value of the Jaccard index was obtained for bird communities in the newly reclaimed but undeveloped areas (0.56), followed by coastal reservoirs (0.34) and ponds located in Cixi Wetland Centre with common reed marshes (0.30). For the whole bird community, the highest value of G-F index was obtained in coastal reservoirs and coastal woodland, whereas the lowest value was recorded in the intertidal mudflats. However, newly reclaimed but undeveloped sites had the highest value of G-F index for the waterbird community, followed by coastal reservoirs and intertidal mudflats. Our results indicate that suitable habitat availability and human disturbance are the main factors influencing the spatial distribution of bird communities in the Hangzhou Bay and the Qiantang River estuary. The most serious human disturbance in this region was found to be coastal reclamation. Thus, diversity of local avian communities in the Hangzhou Bay and the Qiantang River estuary could increase if moderate-intensity reclamation and reasonable land use patterns were practiced. Moderate-intensity reclamation is the mode that maintains an intertidal wetland containing a sufficient width of mudflat and upper intertidal zone as well as other important habitatvariables for shorebirds and other birds. Local governments should take action to protect the natural wetlands while using them reasonably and efficiently. It is necessary to maintain several main high-tide roosting sites with sufficient areas for shorebirds and other waterbirds. Some appropriate management measures such as controlling water level in newly reclaimed but undeveloped areas should be carried out to increase the availability of suitable habitat for waterbirds. A variety of artificial wetlands should also be constructed to provide potential habitats for waterbirds and other birds after large scale coastal reclamation.

Keyi Jiang; Ming Wu; Xuexin Shao; Yong Lü

2013-01-01

287

Macrofauna del curso inferior y estuario del río Biobío (Chile): cambios asociados a variabilidad estacional del caudal hídrico Macrofauna of the lower reach and estuary of Biobío river (Chile): changes associated to seasonal changes of the river flow  

Directory of Open Access Journals (Sweden)

Full Text Available Uno de los sistemas lóticos chilenos de mayor importancia de acuerdo a su caudal es el río Biobío (ca. 37º S). Su estuario es reducido, especialmente en las épocas de máximo caudal. Con el objetivo de poner a prueba la hipótesis de que en verano la disminución del caudal del río Biobío, determina una mayor depositación del material particulado fino y que el aumento del caudal en invierno resulta en el lavado y transporte del material depositado hacia el mar, y consecuentemente en una disminución de la macrofauna bentónica, se recolectaron muestras para análisis sedimentológicos y faunísticos en el curso inferior y estuario del río Biobío, durante agosto de 1993 y marzo de 1994. Los análisis sedimentológicos indican que el tamaño medio del sedimento correspondió a arenas gruesas. La depositación del material fino suspendido, que ocurre durante el verano se manifiesta en el mayor porcentaje de finos y materia orgánica durante este período. La macrofauna bentónica estuvo compuesta por 16 taxa en el muestreo de invierno y 42 taxa en el de verano. Durante el invierno, la mayoría de ellas estuvo representada por muy pocos individuos. Durante el verano aumentó la riqueza específica y abundancias totales de la macrofauna. Los taxa más abundantes fueron un Archiannelida indeterminado y el poliqueto Perinereis gualpensis. El aumento del caudal en la época invernal, determina el transporte del material depositado hacia el mar y consecuentemente el arrastre de organismos bentónicos. Aún cuando los valores de abundancia y biomasa de macrofauna durante el verano fueron de un orden de magnitud mayor que en la fase invernal, fueron menores que los citados para otros estuarios del centro-sur de Chile (ca. 39º S). Eso contribuye a confirmar el carácter atípico del estuario del río Biobío, el que debido a sus cambios estacionales de caudal genera cambios significativos en la estructura comunitaria de la macrofauna bentónicaThe Biobío river (ca. 37º S) is one of the most important Chilean lotic systems with regard to their water flow. Its estuary is reduced, especially during maximum flow. With the purpose of testing the hypothesis that during summer, the decrease of river flow results in a higher deposition of fine particles, and that the increase in river flow during winter results in the washing and transport of deposited particles, and consequently in a decrease of the benthic macrofauna. Sediment samples were collected for sedimentological and faunistical analysis during August 1993 and March 1994. The sedimentological analyses indicate that mean size of sediment corresponded to coarse sands. During summer, the deposition of suspended particles is facilitated by the decrease in the river flow and results in higher percentage of fine particles and organic matter in the sediment. The benthic macrofauna was composed by 16 taxa during winter and 42 taxa during summer. During winter, that macrofauna was represented by just a few individuals. During summer, the species richness and macrofaunal abundances increased. The most abundant taxa were an archiannelid species and the polychaete Perinereis gualpensis. The increase of river flow during winter determines the transport of the deposited material toward the sea and consequently, the washing of benthic organisms. Even though, values of macrofaunal abundance and biomass during summer were about one order of magnitude higher than during winter, they are still lower than those mentioned for other estuaries of south-central Chile (ca. 39º S). That confirms the atypical character of the Biobío river estuary, which due to its seasonal changes, significantly affects the community structure of the benthic macrofauna

CARLOS BERTRÁN; JOSÉ ARENAS; OSCAR PARRA

2001-01-01

288

Macrofauna del curso inferior y estuario del río Biobío (Chile): cambios asociados a variabilidad estacional del caudal hídrico/ Macrofauna of the lower reach and estuary of Biobío river (Chile): changes associated to seasonal changes of the river flow  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Uno de los sistemas lóticos chilenos de mayor importancia de acuerdo a su caudal es el río Biobío (ca. 37º S). Su estuario es reducido, especialmente en las épocas de máximo caudal. Con el objetivo de poner a prueba la hipótesis de que en verano la disminución del caudal del río Biobío, determina una mayor depositación del material particulado fino y que el aumento del caudal en invierno resulta en el lavado y transporte del material depositado hacia el mar, y (more) consecuentemente en una disminución de la macrofauna bentónica, se recolectaron muestras para análisis sedimentológicos y faunísticos en el curso inferior y estuario del río Biobío, durante agosto de 1993 y marzo de 1994. Los análisis sedimentológicos indican que el tamaño medio del sedimento correspondió a arenas gruesas. La depositación del material fino suspendido, que ocurre durante el verano se manifiesta en el mayor porcentaje de finos y materia orgánica durante este período. La macrofauna bentónica estuvo compuesta por 16 taxa en el muestreo de invierno y 42 taxa en el de verano. Durante el invierno, la mayoría de ellas estuvo representada por muy pocos individuos. Durante el verano aumentó la riqueza específica y abundancias totales de la macrofauna. Los taxa más abundantes fueron un Archiannelida indeterminado y el poliqueto Perinereis gualpensis. El aumento del caudal en la época invernal, determina el transporte del material depositado hacia el mar y consecuentemente el arrastre de organismos bentónicos. Aún cuando los valores de abundancia y biomasa de macrofauna durante el verano fueron de un orden de magnitud mayor que en la fase invernal, fueron menores que los citados para otros estuarios del centro-sur de Chile (ca. 39º S). Eso contribuye a confirmar el carácter atípico del estuario del río Biobío, el que debido a sus cambios estacionales de caudal genera cambios significativos en la estructura comunitaria de la macrofauna bentónica Abstract in english The Biobío river (ca. 37º S) is one of the most important Chilean lotic systems with regard to their water flow. Its estuary is reduced, especially during maximum flow. With the purpose of testing the hypothesis that during summer, the decrease of river flow results in a higher deposition of fine particles, and that the increase in river flow during winter results in the washing and transport of deposited particles, and consequently in a decrease of the benthic macrofau (more) na. Sediment samples were collected for sedimentological and faunistical analysis during August 1993 and March 1994. The sedimentological analyses indicate that mean size of sediment corresponded to coarse sands. During summer, the deposition of suspended particles is facilitated by the decrease in the river flow and results in higher percentage of fine particles and organic matter in the sediment. The benthic macrofauna was composed by 16 taxa during winter and 42 taxa during summer. During winter, that macrofauna was represented by just a few individuals. During summer, the species richness and macrofaunal abundances increased. The most abundant taxa were an archiannelid species and the polychaete Perinereis gualpensis. The increase of river flow during winter determines the transport of the deposited material toward the sea and consequently, the washing of benthic organisms. Even though, values of macrofaunal abundance and biomass during summer were about one order of magnitude higher than during winter, they are still lower than those mentioned for other estuaries of south-central Chile (ca. 39º S). That confirms the atypical character of the Biobío river estuary, which due to its seasonal changes, significantly affects the community structure of the benthic macrofauna

BERTRÁN, CARLOS; ARENAS, JOSÉ; PARRA, OSCAR

2001-06-01

289

Fluxes and major transport routes of arsenic in the Scheldt estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The estuary of the Scheldt was monitored for As during seven seasonally spread sampling campaigns. The resulting data indicated that As did not behave conservatively in the estuary; an important mobilisation of As was observed from the river up to halfway the estuary. Both input flux (from river to ...

De Gieter, M.; Elskens, M.; Baeyens, W.

290

[Phytoplankton in Yangtze River estuary and its adjacent waters in spring in 2009: species composition and size-fractionated chlorophyll a].  

Science.gov (United States)

Based on the multidisciplinary cruise investigation in the Yangtze River estuary and its adjacent waters in April 2009, the phytoplankton species and their abundance were analyzed by the Utermöhl method, and the size-fractionated chlorophyll a concentrations were determined. In the meantime, the relationships between the dominant phytoplankton species and environmental physicochemical factors were explored by Canonical Correspondence Analysis (CCA). A total of 3 phyla, 46 genera, and 64 species (not including uncertain species) were found, mostly diatoms and dinoflagellates, with diatoms dominant. Most of these species were temperate and coastal, but a few brackish and oceanic species also presented. There were 33 diatom genera including 45 species. The dominant species were Skeletonema dohrnii, Paralia sulcata, Thalassionema nitzschioides, Pseudo-nitzschia pungens, Melosira granulata var. angustissima, Pseudo-nitzschia delicatissima, and Guinardia delicatula. The phytoplankton cell abundance ranged from 0.3 to 13447.7 cells x ml(-1), with an average of 1142.385 cells x ml(-1). Concerning the horizontal distribution, cell abundance was the highest in the middle-northern part of the survey area, with S. dohrnii dominant. The phytoplankton cell abundance was high in the surface layer water, and decreased with increasing depth. The Shannon diversity index and Pielou evenness index were consistently low in the middle-northern part of the survey area, in contrast to the trend of phytoplankton cell abundance. The chlorophyll a concentrations ranged from 0.34 to 29 g x L(-1), with an average of 3.3 g x L(-1), consistent with the cell abundance distribution. Size-fractionated chlorophyll a results showed that the biomass in the middle-northern part of the survey area was mainly composed of microphytoplankton (> 20 microm), while that in offshore waters was mainly composed of nanophytoplankton (2-20 microm) and picophytoplankton (< 2 microm). The CCA showed that the distribution of predominant species S. dohrnii was mainly affected by the water nitrate content, pH value, and microzooplankton grazing. On the contrary, the distribution of other common species including dinoflagellates was mainly associated with water salinity, and phosphate and silicate contents. The paper also compared the differences in the methods of phytoplankton quantification used by the present study and by the previous studies based on net samples. It was suggested that in future work, the autecological study of genus Skeletonema in the Yangtze River estuary and its adjacent waters should be strengthened. PMID:21548314

Sun, Jun; Tian, Wei

2011-01-01

291

Evaluation of Life History Diversity, Habitat Connectivity, and Survival Benefits Associated with Habitat Restoration Actions in the Lower Columbia River and Estuary, Annual Report 2010  

Energy Technology Data Exchange (ETDEWEB)

This report describes the 2010 research conducted under the U.S. Army Corps of Engineers (USACE) project EST-P-09-1, titled Evaluation of Life History Diversity, Habitat Connectivity, and Survival Benefits Associated with Habitat Restoration Actions in the Lower Columbia River and Estuary, and known as the 'Salmon Benefits' study. The primary goal of the study is to establish scientific methods to quantify habitat restoration benefits to listed salmon and trout in the lower Columbia River and estuary (LCRE) in three required areas: habitat connectivity, early life history diversity, and survival (Figure ES.1). The general study approach was to first evaluate the state of the science regarding the ability to quantify benefits to listed salmon and trout from habitat restoration actions in the LCRE in the 2009 project year, and then, if feasible, in subsequent project years to develop quantitative indices of habitat connectivity, early life history diversity, and survival. Based on the 2009 literature review, the following definitions are used in this study. Habitat connectivity is defined as a landscape descriptor concerning the ability of organisms to move among habitat patches, including the spatial arrangement of habitats (structural connectivity) and how the perception and behavior of salmon affect the potential for movement among habitats (functional connectivity). Life history is defined as the combination of traits exhibited by an organism throughout its life cycle, and for the purposes of this investigation, a life history strategy refers to the body size and temporal patterns of estuarine usage exhibited by migrating juvenile salmon. Survival is defined as the probability of fish remaining alive over a defined amount of space and/or time. The objectives of the 4-year study are as follows: (1) develop and test a quantitative index of juvenile salmon habitat connectivity in the LCRE incorporating structural, functional, and hydrologic components; (2) develop and test a quantitative index of the early life history diversity of juvenile salmon in the LCRE; (3) assess and, if feasible, develop and test a quantitative index of the survival benefits of tidal wetland habitat restoration (hydrologic reconnection) in the LCRE; and (4) synthesize the results of investigations into the indices for habitat connectivity, early life history diversity, and survival benefits.

Diefenderfer, Heida L.; Johnson, Gary E.; Sather, Nichole K.; Skalski, J. R.; Dawley, Earl M.; Coleman, Andre M.; Ostrand, Kenneth G.; Hanson, Kyle C.; Woodruff, Dana L.; Donley, Erin E.; Ke, Yinghai; Buenau, Kate E.; Bryson, Amanda J.; Townsend, Richard L.

2011-10-01

292

Identification of some trace metal minerals in recently compacted and stratified beach rocks close to the estuary of the Nerbioi-Ibaizabal river (Bilbao, Bay of Biscay)  

International Nuclear Information System (INIS)

Complete text of publication follows. The aim of the work is the identification of some trace metal minerals inside recently compacted and stratified sand of beaches close to the Estuary of the Nerbioi-Ibaizabal River (Bilbao, Bay of Biscay). This characterisation work is the first step of a research programme aiming to understand the processes responsible of the cementation that probably started between XIXth and XXth centuries. Several hypotheses have been formulated till now, most of them related to the high metallic stress which impacted the surroundings of the Estuary during the whole XXth century from uncontrolled spills coming from both mining and industrial activities. In this work samples collected from the first 50 cms of 'beachrocks (stratified and cemented sands)' have been analysed by optical microscopy (31 thin plates), micro-X-Ray Fluorescence (more than 100 determinations) and micro-Raman spectroscopy (more than 250 spots). These analyses indicated the presence of a high and different number of elements and mineral phases. Using the geological information available for the Basin of the Nerbioi-Ibaizabal River, we can propose which minerals are coming from weathering processes of naturally minerals, who is the mineral acting as the cementing material and which are the new mineral phases appearing as a consequence of the mining and industrial uncontrolled spills of the past. The naturally occurring mineral phases detected during the analyses were quartz, clay, calcite, hematite, pyrite, rutile. Other minor natural minerals must be also present, containing elements like Mn, Sr, Ba and Rb. Surprisingly, the cementing material was identified as aragonite being a thin layer rounding both naturally occurring grains (sand, clays, calcite, etc.) as well as anthropic mineral phases of different shape. Among the anthropic trace metal minerals, iron hydroxioxide, calcium arsenate, magnesium arsenate, organic carbon and mineral carbon (both can be distinguished by Raman spectroscopy), zinc carbonate and calcium phosphate have been detected. Other mineral phases must be also present because the micro-X-Ray Fluorescence measurements gave appreciable amounts of other anthropic elements like Pb, Sn, Cu, Ni, Co, Cr, Hg and Au. Acknowledgements. This work has been financially supported by the Basque Government through the BERRILUR III Project (ETORTEK Progr.).

2009-09-03

293

Sources, transformation and fate of particulate amino acids and hexosamines under varying hydrological regimes in the tropical Wenchang/Wenjiao Rivers and Estuary, Hainan, China  

Science.gov (United States)

The small tropical Wenchang and Wenjiao Rivers on the island of Hainan, tropical China, are affected by effluents from municipal sewage, aquaculture and agriculture, and by contrasting hydrological regimes related to monsoon and tropical storms. In order to obtain information on the sources, transformation and fate of organic matter (OM) we investigated the amount and composition of amino acids and hexosamines as well as the carbon isotope composition in suspended particulate matter (SPM) from the Wenchang/Wenjiao Estuary. SPM was collected along the salinity gradient starting from the river sites, along the lagoon-shaped Bamen Bay to coastal waters during four sampling campaigns between 2006 and 2009. SPM concentrations ranged between 4.7 and 58.2mgL-1. Apart from highest values after heavy rain events in spring and summer, SPM showed little seasonal variation, but increased with salinity. From SPM POC% (1.2-20.9%), C/N (4.9-16.5) and ?13Corg (-31.5 to -19.5‰), the molar composition and content of amino acids and hexosamines (8.2-156.2mgg-1 dry weight) and by comparison with sediments, mangroves, soils and plants we are able to show that soil-derived material, freshwater and marine plankton were the major sources of suspended OM. High POC and amino acid contents were related to primary production sustained by dissolved nutrients to a large extent stemming from municipal and aquaculture effluents. Factor analysis showed that the suite of biogeochemical parameters measured clearly depict the terrestrial vs. marine origin and the freshness/reactivity of OM. The four groups of samples resulting from cluster analysis were basically related to varying hydrological regimes. With respect to the sources, degradation and fate of particulate OM the major factors were: (i) the year round input of labile, amino acid rich riverine OM matter at the freshwater dominated sites, (ii) high input of degraded soil OM after heavy rains with dispersal throughout the estuary and export to the adjacent coastal area, (iii) significant production of labile marine OM especially during summer inside the bay and the (iv) dominance of refractory marine OM during winter and spring season and in the offshore region. While a major part of the fresh OM fuelled by anthropogenic nutrients appears to be stored or recycled inside the bay, periodic torrential rainfalls can lead to a pulsed export of this OM to the coastal area where it may adversely affect seagrass meadows and coral reefs.

Unger, Daniela; Herbeck, Lucia S.; Li, Min; Bao, Hongyan; Wu, Ying; Zhang, Jing; Jennerjahn, Tim

2013-04-01

294

Comparison of selected biomarkers in flounder (Platichthys flesus L.) from the Douro (Portugal) and Vistula (Poland) River estuaries.  

UK PubMed Central (United Kingdom)

Sixty female flounder (Platichthys flesus) were collected in Autumn 2011, 15 from each of the following sampling sites: at the mouths of the Douro and Vistula Rivers, and at nearby open sea locations. The aim of the study was to assess several biomarkers in the two geographically distant regions. Hepatic EROD, GST, SOD, GPx, POx, LP; muscular AChE, BChE, LP; and branchial Na(+)/K(+)-ATPase were analysed. Moreover, BTI, PY, and three gross morphometric indices were calculated. The results were analysed with t-test, ANOVA, and PCA. Many differences were found between the open sea sites and the river mouths, mainly in Portugal, and between the two rivers. Salinity and pollution seem to be the main factors that affected the biomarkers. Effects of chronic pollution were observed at the river mouths, and an indication of a possible temporary exposure to pollutants was found at the open ocean site in Portugal.

Kopecka-Pilarczyk J

2013-08-01

295

Influence of freshwater discharges and tides on the abundance and distribution of larval and juvenile Munida gregaria in the Baker river estuary, Chilean Patagonia  

Science.gov (United States)

Zooplankton time series collected with different temporal resolution and coverage were examined to characterize seasonal and diel patterns in the abundance of Munida gregaria larvae and juveniles in the Baker river estuary. Zoeae were more abundant in late winter and spring, coinciding with the season of lower sediment transport and higher primary production in the region. The occurrence of juveniles was exclusively in summer. There was a significant correlation between the abundance of zoeae and high-frequency temperature variability near the pycnocline over periods of 7–20 and 26–30 days prior to each plankton sampling. These time scales of correlation suggest that internal motions may be a proximal environmental cue for lunar rhythms in larval hatching, rather than directly causing the aggregation of larvae at the sampling area. To characterize shorter-term patterns in larval abundance and vertical distribution, stratified samples were collected every 3 h over a full late-spring day (November 2008) near one of the monitoring stations. Zoeae were significantly more abundant at 10–25 m depth (p=0.039), and changes in depth-integrated abundance of both zoea and megalopae were strongly associated with the tidal cycle. Together, these results suggest that the spatial structure and population dynamics of M. gregaria in this region may respond to the combined forcing of seasonal changes in freshwater inputs, tidally-driven processes such as lateral transport of larvae and juveniles, and internal-wave mediated changes in local conditions.

Meerhoff, Erika; Castro, Leonardo; Tapia, Fabián

2013-07-01

296

Distribution study of fatty acids (FAs) in sediments of Al-Kabeer Al-Shemali river estuary area using (HPLC) technique  

International Nuclear Information System (INIS)

[en] Samples of sediments from fife sites of Al-kabeer Al-shemali river estuary area were collected during the period (22/2/2007-7/11/2007). The samples were extracted to determine their content of Fatty acids qualitatively and quantitatively by using ( HPLC) technique for determination resources of organic matter in studied sediments . The total concentrations of (FAs) varied from (0.36-1245.5?g/g dry weight).The saturated fatty acids were dominated in all samples (12.1 - 100 %) of total fatty acids. The levels of polyunsaturated fatty acids (PUFAs) were tested percent (0-18 %) of total fatty acids except one sample from surficial sediments in St3 during 8/8/2007 .while the concentrations of monounsaturated fatty acids (MUFAs) were low (0 -21.6 %) of total fatty acids . We can use the saturated long chain fatty acid (C-22) as terrestrial biomarker. poly unsaturated fatty acid (C18: 2?6) as plankton biomarker and the Mono unsaturated fatty acid (C18 : 1?7) as bacterial biomarker.(author)

2010-01-01

297

Assessment of heavy metal pollution in wetland soils from the young and old reclaimed regions in the Pearl River Estuary, South China  

International Nuclear Information System (INIS)

Soils were sampled in three types of wetlands from the young (A) and old (B) reclaimed regions of the Pearl River Estuary. They were analyzed for total concentrations of heavy metals to investigate their distributions and pollution levels in both regions. Results showed that most heavy metals in ditch and riparian wetlands did not significantly differ from those in reclaimed wetlands in A region, while significantly lower for Cd, Cu, Pb, and Zn in reclaimed wetlands in B region, suggesting higher effects of long-term reclamation. Iron, Cr and Cu were identified as metal pollutants of primary concern and had higher contributions to the total toxic units compared to other metals. Almost all metals exceeded their lowest effect levels and Fe and Cr even exceeded the severe effect levels. Multivariate analysis shows that Fe and Mn are controlled by parent rocks and other metals mainly originate from anthropogenic source. - Research highlights: ? Fe, Cr and Cu have higher contributions to the sum of toxic units. ? More than 75.4% soil samples have moderate toxicity in PRE. ? Heavy metals in typical soil profiles exceed the LEL thresholds. ? Heavy metals (except Fe and Mn) mainly originate from anthropogenic source. ? Long reclamation history can lead to greater heavy metal loss in wetland soils. - The findings of this study reveal higher effects of long-term reclamation on heavy metal pollution of wetland soils and contribute to coastal wetland management in subtropical regions.

2011-01-01

298

Levels and bioaccumulation of organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in fishes from the Pearl River estuary and Daya Bay, South China  

International Nuclear Information System (INIS)

[en] Fifty fish samples were collected from the Pearl River estuary (PRE) and Daya Bay, South China and were analyzed for DDTs, HCHs, chlordanes and polybrominated biphenyl ethers (PBDEs). Except the high concentrations of DDT observed in fishes, the concentrations of HCHs, chlordanes and PBDEs were low when compared to other regions. BDE-47 was the predominant PBDE congener and the BDE-209 concentrations were relatively low, despite its high concentration in surface sediments. The absence of significant increase of DDT, HCH, chlordane and PBDE concentrations towards higher ?15N values, as well as the lack of a significant correlation (p 15N, may indicate a weak biomagnification of these chemicals in the food webs. Good agreement was observed between their concentrations and lipid contents of the organisms. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms in the studied subtropical waters. - Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms of subtropical waters

2008-01-01

299

Levels and bioaccumulation of organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in fishes from the Pearl River estuary and Daya Bay, South China  

Energy Technology Data Exchange (ETDEWEB)

Fifty fish samples were collected from the Pearl River estuary (PRE) and Daya Bay, South China and were analyzed for DDTs, HCHs, chlordanes and polybrominated biphenyl ethers (PBDEs). Except the high concentrations of DDT observed in fishes, the concentrations of HCHs, chlordanes and PBDEs were low when compared to other regions. BDE-47 was the predominant PBDE congener and the BDE-209 concentrations were relatively low, despite its high concentration in surface sediments. The absence of significant increase of DDT, HCH, chlordane and PBDE concentrations towards higher {delta}{sup 15}N values, as well as the lack of a significant correlation (p < 0.1) between log concentrations (lipid normalized) and {delta}{sup 15}N, may indicate a weak biomagnification of these chemicals in the food webs. Good agreement was observed between their concentrations and lipid contents of the organisms. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms in the studied subtropical waters. - Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms of subtropical waters.

Guo Lingli [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Guangdong 510640 (China); Qiu Yaowen [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Guangdong 510640 (China); Key Laboratory of Tropic Marine Environmental Dynamics, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301 (China); Zhang Gan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Guangdong 510640 (China)], E-mail: zhanggan@gig.ac.cn; Zheng, Gene J.; Lam, Paul K.S. [Department of Biology and Chemistry, Centre for Coastal Pollution and Conservation, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Li Xiangdong [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

2008-04-15

300

Pattern recognition and classification of sediments according to their metal content using chemometric tools. A case study: the estuary of Nerbioi-Ibaizabal River (Bilbao, Basque Country).  

UK PubMed Central (United Kingdom)

Chemometrics are increasingly used in environmental monitoring studies, but are still far from being accepted as routine tools by field specialists. The multivariate character of usually highly correlated environmental data recommends the use of advanced chemometrics as part of the analytical methodology in order to get information on the basic structure of data. In this work, we have applied a battery of non-supervised (Principal Component Analysis (PCA)) and supervised (k-Nearest Neighbour (k-NN), Soft Independent Modelling of Class Analogies (SIMCA), Linear Discriminant Analysis (LDA) and Artificial Neural Networks (ANNs)) multivariate techniques on a specific environmental dataset. The dataset consists on the concentration of 14 elements (Al, As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, V and Zn) in 95 sediments collected at eight different locations of the estuary of the Nerbioi-Ibaizabal River (Bilbao, Basque Country) during 12 sampling campaigns conducted every 3 months between 2005 and 2008. The study aims to present a simple methodology of general applicability which may result in a flexible and practical tool to assess chemical pollution in sediments of a given specific site.

Fdez-Ortiz de Vallejuelo S; Arana G; de Diego A; Madariaga JM

2011-11-01

 
 
 
 
301

Partial least squares X-ray fluorescence determination of trace elements in sediments from the estuary of Nerbioi-Ibaizabal River.  

UK PubMed Central (United Kingdom)

The feasibility of partial least squares (PLS) regression modeling of X-ray fluorescence (XRF) spectra of estuarine sediments has been evaluated as a tool for rapid trace element content monitoring. Multivariate PLS calibration models were developed to predict the concentration of Al, As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, V and Zn in sediments collected from different locations across the estuary of the Nerbioi-Ibaizabal River (Metropolitan Bilbao, Bay of Biscay, Basque Country). The study was carried out on a set of 116 sediment samples, previously lyophilized and sieved with a particle size lower than 63 microm. Sample reference data were obtained by inductively coupled plasma mass spectrometry. 34 samples were selected for building PLS models through a hierarchical cluster analysis. The remaining 82 samples were used as a test set to validate the models. Results obtained in the present study involved relative root mean square errors of prediction varying from 21%, for the determination of Pb at hundreds microg g(-1) level, up to 87%, for Ni determination at little tens microg g(-1) level. An average prediction error of +/-37% for the 14 elements under study was obtained, being in all cases mean differences between predicted and reference results of the same order than the standard deviation of three replicates from a same sample. Residual predictive deviation values obtained ranged from 1.1 to 3.9.

Moros J; Gredilla A; Fdez-Ortiz de Vallejuelo S; de Diego A; Madariaga JM; Garrigues S; de la Guardia M

2010-09-01

302

Seasonal pattern and community structure of fishes in the shallow tidal creek of Obitsu-gawa River Estuary of inner Tokyo Bay, central Japan  

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Full Text Available Seasonal pattern and the community structure of fishes in the shallow tidal creek of ObitsugawaRiver Estuary of inner Tokyo Bay was studied for one year. Family Gobiidae corresponded to 98%of the total catch. Dominant species were Gymnogobius uchidai, Gymnogobius macrognathos,Gymnogobius breunigii, Eutaeniichthys gilli, Pseudogobius masago and Favonigobius gymnauchen.Stepwise modelling in canonical correspondence analysis indicated that season (p=0.02) best explainedthe variation in abundance of fish in this shallow habitat. There was a difference in fish communitybetween spring and summer while only a small difference was observed between summer and autumn aswell as winter and autumn. Species dominance was an inherent property of the tidal creek fishcommunity particularly in spring because of the remarkable abundance of G. uchidai. However, the fishcommunity had the tendency to become proportionately even as the season progresses from spring towinter. The occurrence of a particular life history stage generally showed a strong association with monthand water temperature. Adults substantially contributed to the population size structure of P. masagoand G. uchidai while juvenile 2 for G. breunigii and E. gilli . Larvae significantly contributed to thepopulation size structure of F. gymnauchen while juvenile 1 and juvenile 2 for G. macrognathos. Thecurrent study indicated that natural shallow habitat within a highly urbanized metropolitan area in innerTokyo Bay can serve as a habitat for fishes and the prevalence of certain life history stages of estuarinespecies indicated the importance of the said habitat at certain part of their life history.

Joeppette J. Hermosilla; Yasushi Tamura; Daisuke Okazaki; Yukihiro Hoshino; Masato Moteki; Hiroshi Kohno

2012-01-01

303

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

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Full Text Available 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 in July (100.2cm) while the least was obtained in June (15.30cm). The highest weight was 1410g obtained in October while the least was obtained in September (22.10g) and there were significant differences in monthly distribution of length and weight (P<0.05) of the specimens. Correction coefficient (r) between length and weight of C. nigrodigitatus from June November, 2011 lied between 0.89 and 0.98 representing strong relationship between length and weight, the relationship was found to be linear but in logarithmic form. Generally condition factor, (K) values decreased proportionately with the length of the fish. A total of seventy two (72) (17.14%) parasite specimens were recovered from the fish, out of which helminthes parasites include a cestode Proteocephalis 9 (12.5%) and aspidogastrid trematode, Aspidogastrea africanus 10 (13.89%) and Nematodes; Paracamallanus cyathopharynx 34 (47.22%) and Contracacum sp. 19 (26.64%). Parasitic worm burden and Intensity of infection low and independent of length and weight.

Usip Lawrence Patrick Esiest

2013-01-01

304

Episodic closure of the tidal inlet at the mouth of the Russian River — A small bar-built estuary in California  

Science.gov (United States)

Bar-built estuaries with relatively small (cross sectional area climates and along wave-exposed coasts. While similarly important to coastal sediment balances and estuarine ecosystems and more numerous than larger inlet systems, they suffer from a relative lack of understanding. This is especially true regarding the process of inlet closure, when the channel is filled with sediment deposited by wave-driven processes. Mouth closure is of growing concern owing to changes in inlet behavior in many systems in response to human influences. The use of many existing conceptual and quantitative models for closure is precluded by rapid morphological change, unsteady freshwater inputs, and difficulties in scaling well-established inlet relationships in these smaller systems. In this paper, over 60 years of daily closure records are analyzed for the Russian River mouth, a prototypical bar-built system in northern California. We show that the time-dependent closure pattern can be explained by an interaction of processes that act to scour the inlet (driven by tides and river) with those that act to deposit sand in the inlet (driven by waves). Tidal, weather-related, seasonal, and interannual cycles are observed. We improve an existing parametric model to evaluate these separate influences and show that it works well for predicting closure events at both the tidal and seasonal scales. Finally, we compare our data with closure records from the nineteenth and twentieth centuries to show that inlet closures have become shorter and more sporadic over time at this site and to identify anthropogenic drivers of this observed change.

Behrens, Dane K.; Bombardelli, Fabián A.; Largier, John L.; Twohy, Elinor

2013-05-01

305

ANÁLISE UNIDIMENSIONAL DOS PROCESSOS DE MISTURA NO SISTEMA ESTUARINO DO RIO PERIÁ (MA), BRASIL / One-dimension analysis of mixing processes of the Periá River Estuary (MA), Brazil  

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Full Text Available The objective of present work is to analyze the processes of mixture in the estuarinesystem of the Periá River (MA) and to classify the system into zones following Kjerfve (1987). The mathematical model of Dyer and Taylor (1973) was used in order toanalyze the mixture processes. To attain the objectives, the bathymetry of the estuarinesystem was obtained, allowing to define the limits of high and low tides. The one-dimension analysis considered: salinity and the water concentration and/or fresh waterfraction, in high and low tides; the rates and times of discharges; and the volumes offresh water restrained in the estuary in high and low water slacks. The followingresults were obtained: the water volume in the system has maximum of 64,96 * 106 m3and minimum of 0,12 * 106 m3; the tidal prism has maximum of 7,1 * 106 m3 andminimum of 0,045 * 106 m3; the fresh water concentration was higher in low tide (0,99* 106 m3 ) than in high tide (0,91 * 106 m3 ); the salt concentration was always larger inhigh than in low tides, having maximum of 34 ups and minimum of 0,34 ups; regardingthe water volume restrained in the low and high water slacks, it was larger in theebbing (5,36* 106 m3) than flooding (1,12 * 106 m3); and finally, the discharge timespresented larger values in high tides (2 tidal periods) and smaller in low tides (1.2tidal periods).The study allows to conclude that the salinity and fresh water dischargein the estuarine system of Periá River are the dominant factors in the processes ofmixture.

Enner Herenio de Alcântara; Joseph Harari

2006-01-01

306

Nitrogen dynamics in the tidal freshwater Potomac River, Maryland and Virginia, water years 1979-81: A water-quality study of the tidal Potomac River and estuary  

International Nuclear Information System (INIS)

On an annual basis, river supplied nitrate is the predominant form of N supplied to the tidal Potomac River from external sources. Much of the nitrate is associated with high flows that have rapid transit times through the tidal river. After the fall of 1980, initiation of advanced wastewater treatment at the Blue Plains Sewage Treatment Plant (STPP) reduced ammonia loading to the river by 90% and increased nitrate loading by a similar percentage. As a result, concentrations of ammonia during the 1981 low flow period were 1.50 mg/L as N. Despite the reduced availability of ammonia, 15-N uptake studies showed that phytoplankton preferred ammonia to nitrate unless ammonia concentrations were

307

Plutonium and cesium radionuclides in the Hudson River Estuary. Annual technical progress report, 1 December 1975--30 November 1976  

International Nuclear Information System (INIS)

[en] We have obtained a large set of cores from the Hudson Estuary covering nearly all of the ambient salinity range. A number of core sections have been analyzed for 137Cs, 134Cs, 60Co and 40K by direct gamma counting and for 239,240Pu and 238Pu by alpha-spectrometry. Rapid accumulation, up to 20 cm/year, of sediments containing 239,240Pu, 137Cs, 134Cs and 60Co occurs in New York Harbor. Marginal coves upstream from the harbor also serve as depositional environments. The ratio of sediment /sup 239,240/Pu to 137Cs is higher than the fallout ratio in the seaward end of New York Harbor, despite the presence of a significant component of reactor 137Cs in the sediments, but lower than the range of ratios observed by others for nearshore environments with low sediment deposition rates. A substantial portion of gamma emitting fission product and activation nuclides released from the Indian Point nuclear facility have accumulated in New York Harbor, more than 60 km downstream from the release area. We have not yet established whether local transuranic releases to the Hudson have occurred

1975-12-01

308

Sea level variability in South African estuaries  

Scientific Electronic Library Online (English)

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

Schumann, Eckart H.

2013-01-01

309

ANALYSIS OF FISHERIES DATA IN ASSOCIATION WITH THE DEVELOPMENT OF MINIMUM FLOWS AND LEVELS FOR THE LOWER SUWANNEE RIVER/ESTUARY  

Science.gov (United States)

The model determines the impact of freshwater inflow on the diversity of species in the estuary. The very nature of estuaries as "regions of mixing of fresh and salt water", in conjunction with their importance as nursery areas for many commercial and recreational fishery specie...

310

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Este trabalho foi desenvolvido junto a duas comunidades de pescadores artesanais: Barra de Mamanguape e Tramataia, Nordeste do Brasil. O objetivo foi estudar o conhecimento e a percepção dos pescadores artesanais sobre a classificação das marés e dos ventos bem como as técnicas e estratégias de pesca. A metodologia empregada envolveu várias técnicas: entrevistas livres, entrevistas semiestruturadas, turnês guiadas e observação direta. Os resultados obtidos jun (more) to aos pescadores mostraram a classificação das marés de acordo com as fases lunares em: 'maré de quebramento', 'maré de lançamento', 'maré morta' e 'maré grande', designadas tecnicamente estas últimas como maré de quadratura e maré de sizígia, respectivamente. O vento é também um fator essencial no sucesso da pescaria, eles o classificam de acordo com a direção: Norte, Sul, Leste, Sudeste, Sudoeste, Nordeste, Noroeste. Os dados obtidos nesta pesquisa mostraram que o conhecimento dos pescadores pode ser útil na elaboração de planos de manejo e nos estudos de conservação para este estuário. Abstract in english This work was carried out in two small fishing communities, Barra de Mamanguape and Tramataia, Northeastern Brazil. The aim was to study these traditional fishermen's knowledge and perception about tide and wind classifications, as well as their fishing strategies and techniques. Our research methodology involved various techniques: free interviews and semi-structured ones, guided tours and direct observations. The results obtained show the fishermen's classification of t (more) he tides according to the phases of the moon: 'breaking tide', 'flushing tide', 'dead tide' and 'big tide' designated technically these last as neap tide and spring tide, respectively. Wind is also an essential factor for the fishermen to make successful catches, and they classify it according to direction: North, South, East, Southeast, Southwest, Northeast and Northwest. The data show that fishermen's knowledge can also be useful in devising plans for management and conservation studies for this estuary.

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

2012-09-01

311

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

Directory of Open Access Journals (Sweden)

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

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

2012-01-01

312

Determination of volatile, toxic hydrogen phosphides in the sediments of the Elbe river, the Elbe estuaries and the Heligoland Bay  

International Nuclear Information System (INIS)

The distribution and concentraion of phosphines in the sediments of the Elbe river were determined by selective preparation and analysis. The concentration of phosphines in one kilogram wet sediment was in the range of 0.1 to 57 n g with the bulking, anaerobic mud from harbors having the highest and the sandy, aerobic sediments having the lowest concentrations. Phosphines in fluvial sediments were detected successfully for the first time applying the method described. (orig.)

1992-01-01

313

Investigation of the methanogen-related archaeal population structure in shallow sediments of the Pearl River Estuary, Southern China.  

UK PubMed Central (United Kingdom)

Few studies have specifically dealt so far with methanogen-related archaea in estuarine sediments. In this study, methanogen-related archaeal populations were investigated by 16S rRNA gene clone library, T-RFLP analysis, and methanogen enrichment in Pearl River estuarine sediments. The majority of obtained sequences in clone libraries and T-RF peaks from T-RFLP analysis were assigned mainly to Methanosaeta, Methanomicrobiales, and Methanosarcinales/ANME. The fragments of Methanosarcinales/ANME were most dominant group (mean 47%) and composed largely of ANME-2a which are characterized as anaerobic methane oxidizing archaea in broad environments. Furthermore Methanosaeta and Methanomicrobiales accounted for 23 and 29% of fragments, respectively, for all depths. Therefore, the presence of Methanomicrobiales and Methanosaeta in Pearl River estuarine sediments was indicative of both acetoclastic and hydrogenotrophic methanogenesis. In addition, the enrichments of methanogens also suggested the presence of acetoclastic and hydrogenotrophic methanogens in Pearl River estuarine sediments. This study is a significant step toward understanding methane cycling association of representative archaea in estuarine environments.

Chen J; Wang F; Zheng Y; Jiang L; Xiao X

2013-05-01

314

Ictiofauna associada às raízes de mangue do estuário do Rio Pacoti - CE, Brasil/ Fish fauna associated to mangrove roots at the Pacoti River estuary  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Margens de estuários com a vegetação de manguezal formam um importante hábitat para peixes, pois são zonas de alimentação, abrigo e berçário. O presente trabalho tem como objetivo caracterizar a ictiofauna associada às raízes de mangue do estuário do Rio Pacoti (CE). Foram realizados 10 censos visuais com duração de 90 minutos cada. Foram feitas 671 avistagens, com densidade média de 0,74 avistagens/minuto. Os indivíduos pertencem a 22 espécies e 18 famí (more) lias. Todas as espécies registradas são de origem marinha, apesar das amostragens serem realizadas principalmente no período chuvoso. As famílias que apresentaram um maior número de espécies foram Gerreidae e Lutjanidae. As espécies que apresentaram maior frequência de ocorrência foram Lutjanus alexandrei, Lutjanus jocu e Bathygobius soporator, estando presentes em todos os censos. As duas espécies mais abundantes foram L. alexandrei (48%) e L. jocu (17%). Levando-se em consideração as estimativas de tamanho destas espécies, foi verificado que as raízes de mangue são habitadas principalmente por indivíduos jovens de ambas as espécies, o que leva a supor que estas utilizam tal habitat como área de berçário. Contudo, na estação de coleta com menor complexidade estrutural foi avistado o maior número de indivíduos do gênero Lutjanus, em praticamente todas as faixas de comprimento, o que sugere que no Rio Pacoti a quantidade de raízes pode não influenciar na quantidade de indivíduos abrigados. Aproximadamente 70% das espécies avistadas também ocorrem em ambientes recifais, o que demonstra a existência de fortes conexões entre esses dois ecossistemas. Os resultados encontrados enfatizam a importância do habitat estudado para a conservação da ictiofauna costeira e apontam a necessidade de pesquisas relacionadas principalmente ao recrutamento, padrões reprodutivos e tróficos das duas espécies mais representativas. Abstract in english The mangrove vegetation along the margins of estuaries is an important habitat for fish, serving as feeding, shelter and nursery zones. The present work describes the fish fauna associated to mangrove roots at the Pacoti River estuary. A total of ten visual censuses of 90 minutes each were conducted, yielding the number of 671 fish counted, with an average of 0.74 counts/minute. The fishes were identified pertaining to 22 species from 18 different families. All the studie (more) d species are originally marine, although the samples were mainly carried out during the rainy season. Gerreidae and Lutjanidae were the more representative families. The species Lutjanus alexandrei, Lutjanus jocu and Bathygobius soporator were present in all censuses and the first two were also the most abundant, with 48 and 17% of the total counts, respectively. Taking into account size estimations of the fish, it was verified that mangrove roots are inhabited mainly by juveniles of both species, indicating the use of this habitat as a nursery area. However, in the least complex sampling site, specimens of genus Lutjanus were sought in higher quantities, comprinsing all size classes, thus suggesting the abundance of roots in Pacoti River might not influence the abundance of sheltered fishes. Another important observation is that almost 70% of the species present in the mangrove roots are typical of reef habitats, indicating the existence of strong connections between these two ecosystems. The results emphasize the importance of this habitat for ichthyofauna conservation to coastal areas. In addition, studies regarding to fish recruitment, reproductive and trophic patterns are needed, especially to those two main important species described herein.

Osório, Frederico Moreira; Godinho, Wander Oliveira; Lotufo, Tito Monteiro da Cruz

2011-03-01

315

Occurrence of pesticides and polychlorinated biphenyls in water of the Nile river at the estuaries of Rosetta and Damiatta branches, north of Delta, Egypt.  

UK PubMed Central (United Kingdom)

A study was conducted from summer 1995 to summer 1997 to assess the seasonal occurrence of pesticide residues and other organic contaminants, polychlorinated biphenyls (PCBs), in water at the estuaries of Rosetta and Damiatta branches of the Nile river. The results indicated that organochlorine compounds (OCs) including HCB, lindane, p,p'-DDE, p,p'DDD, p,p'-DDT, aroclor 1254 and aroclor 1260 were present in all the water samples at concentration levels ranging between 0.195-0.240, 0.286-0.352, 0.035-0.067, 0.019-0.033, 0.024-0.031, 0.390-0.70 and 0.166-0.330 microgram/l, respectively. The levels of these compounds were higher in water of Damiatta branch than those found in water of Rosetta branch. Aldrin, dieldrin and endrin were not detected in all water samples. Only 4 compounds from 36 organophosphorus insecticides, fungicides and s-triazine herbicides tested were detected in water samples collected during summer and autumn seasons from Rosetta branch. The concentration levels of these detected compounds, dimethoate, malathion, captan, and ametryne, ranged from 0.011 to 0.340 microgram/l, respectively. Similar compounds during the same seasons as found in water of Rosetta branch were also detected in water of Damiatta branch except ametryne. The levels of the detected compounds (dimethoate, malathion and captan) ranged between 0.030 and 0.330 microgram/l. The levels of detected organophosphorus insecticides, fungicides and s-triazine herbicides were in the order: dimethoate > malathion > captan > ametryne.

Abbassy MS; Ibrahim HZ; el-Amayem MM

1999-03-01

316

Occurrence of pesticides and polychlorinated biphenyls in water of the Nile river at the estuaries of Rosetta and Damiatta branches, north of Delta, Egypt.  

Science.gov (United States)

A study was conducted from summer 1995 to summer 1997 to assess the seasonal occurrence of pesticide residues and other organic contaminants, polychlorinated biphenyls (PCBs), in water at the estuaries of Rosetta and Damiatta branches of the Nile river. The results indicated that organochlorine compounds (OCs) including HCB, lindane, p,p'-DDE, p,p'DDD, p,p'-DDT, aroclor 1254 and aroclor 1260 were present in all the water samples at concentration levels ranging between 0.195-0.240, 0.286-0.352, 0.035-0.067, 0.019-0.033, 0.024-0.031, 0.390-0.70 and 0.166-0.330 microgram/l, respectively. The levels of these compounds were higher in water of Damiatta branch than those found in water of Rosetta branch. Aldrin, dieldrin and endrin were not detected in all water samples. Only 4 compounds from 36 organophosphorus insecticides, fungicides and s-triazine herbicides tested were detected in water samples collected during summer and autumn seasons from Rosetta branch. The concentration levels of these detected compounds, dimethoate, malathion, captan, and ametryne, ranged from 0.011 to 0.340 microgram/l, respectively. Similar compounds during the same seasons as found in water of Rosetta branch were also detected in water of Damiatta branch except ametryne. The levels of the detected compounds (dimethoate, malathion and captan) ranged between 0.030 and 0.330 microgram/l. The levels of detected organophosphorus insecticides, fungicides and s-triazine herbicides were in the order: dimethoate > malathion > captan > ametryne. PMID:10192956

Abbassy, M S; Ibrahim, H Z; el-Amayem, M M

1999-03-01

317

Estimation of persistent pollutants in estuaries  

Energy Technology Data Exchange (ETDEWEB)

Synthetic organic compounds, such as pesticides, plasticizers and technical products could be identified and quantified in German estuaries. Processes of biodegradation and sorption are essentially responsible for most of the compounds. Heterotrophic activities are declining down the estuaries to arrive at very low levels in the open sea. Measurements of a number of organic contaminants in the estuaries of the rivers Weser and Elbe as well as in adjacent coastal waters reveal that the estuarine degradation potential is not sufficient to eliminate these compounds.

Ernst, W.

1988-03-01

318

Water quality in the Knysna estuary  

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Full Text Available Measurements of water temperature, salinity, pH, dissolved oxygen, secchi disk depth, turbidity and total suspended solids were taken monthly in the Knysna estuary between 1991 and 1994. Measurements of turbidity and total suspended solids of waters entering the Knysna estuary via rivers and man-made inlets were also taken on an ad hoc basis. These results are described and compared to published data on past water quality conditions. No clear long-term changes in water quality in the estuary were evident. High inputs of sediments from minor catchments indicate the necessity for remedial actions.

I.A. Russell

1996-01-01

319

Associated fauna to the mangroves and other marshes in the Delta-estuary of the River Magdalena, Colombia  

International Nuclear Information System (INIS)

A synthesis of observations and collections of fauna associated with different vegetative communities and bodies of water present in the estuarine-delta of Magdalena river, with emphasis in the Via Park Isla Salamanca (56.200 acres) and National Reserve Flora and Fauna Sanctuary of the Cienaga Grande de Santa Marta (23.000 acres), between 1978-1985. The information was gathered through samplings and manual captures affected during 1978 and period 1981-1985, as well as accomplished direct observations sporadically in the period 1986-1998. The records of 10 species of amphibians, 40 species of reptiles, 194 species of birds and 46 species of mammals show the great variety of fauna in this Caribbean area of Colombia.

2003-01-01

320

Anthropogenic source assessment of 226Ra and 210Pb in a sediment core from the Cubatao River estuary (SE Brazil)  

International Nuclear Information System (INIS)

A sediment core from an estuarine area receiving drainage from the highly industrialized Cubatao River basin (SE Brazil) showed 226Ra and 210Pb activities up to 80 and 213 Bq kg-1, respectively, which are greater than activities considered as regional background levels. Radionuclides and the elevated phosphorus concentrations (up to 0.3% sediment dry weight) found along the sediment core were significantly correlated with each other, indicating source similarity. These results indicate that 226Ra and 210Pb activities are affected by fertilizer industry-derived inputs in addition to natural sources. This interpretation was supported by 210Pb/226Ra ratios (found to be between 2.6 and 3.9) that indicate disequilibrium between 226Ra and its decay product 210Pb, as expected for phosphogypsum-affected sediments. (author)

2011-01-01

 
 
 
 
321

Composition and spatial distribution of the benthic macrofauna in the Cachoeira River estuary, Ilhéus, Bahia, Brazil/ Composición y distribución espacial de la macrofauna bentónica en el estuario del Río de Cachoeira, Ilhéus, Bahía, Brasil  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En este estudio se analizó la composición y la distribución espacial del macrobentos en el estuario del río Cachoeira, Ilhéus, Bahía, Brasil. Las muestras fueron recolectadas cada dos meses desde julio de 2008 a mayo de 2009 en seis estaciones de muestreo. En total, se recogieron 613 individuos pertenecientes a 71 taxa. Los gasterópodos mostraron la mayor riqueza y abundancia, seguidos por los poliquetos. La distribución del macrobentos fue influenciada por la sal (more) inidad y los parámetros de sedimentos. En la parte externa del estuario fueron abundantes los microgastrópodos, el bivalvo Donax gemmula y el poliqueto Drilonereis sp. En la desembocadura predominaron gasterópodos carnívoros Olivella minuta y Anachis obesa y pastoreadores Neritina virginea y Littorina ziczac. Predominaron en la zona intermedia el poliqueto Hemipodia californiensis y en el sector interno bivalvos eurihalinos Tellina sp., Anomalocardia brasiliana y Tagelus plebeius y los poliquetos depositívoros Heteromastus filiformes y Capitella cf. capitata. Características de salinidad, sedimentos, y hábitos alimentarios son importantes en la composición y distribución de los organismos en este estuario. Abstract in english We analyzed the composition and spatial distribution of macrobenthos in the Cachoeira River estuary, Ilhéus, Bahia, Brazil. Samples were taken bimonthly from July 2008 to May 2009 at six stations along the estuary. In total, 613 individuals belonging to 71 taxa were collected. Molluscs showed the highest richness and abundance, followed by polychaetes. The spatial distribution of macrobenthos was influenced by salinity and by sediment characteristics. In the outer area m (more) icrogastropods, the bivalve Donax gemmula, and the polychaete Drilonereis sp., were conspicuous. In the river mouth, the carnivorous gastropods Olivella minuta and Anachis obesa and the algal grazers Neritina virginea and Littorina ziczac predominated. In the middle estuary, there was a predominance of the polychaete Hemipodia californiensis. The euryhaline bivalves Tellina sp., Anomalocardia brasiliana, and Tagelus plebeius and the deposit-feeding polychaetes Heteromastus filiformis and Capitella cf. capitata were predominant in the inner estuary. Salinity, sediment characteristics, and dietary habits were important in the composition and distribution of organisms in this estuary.

Ourives, Thailla M; Rizzo, Alexandra E; Boehs, Guisla

2011-04-01

322

A COMPARATIVE ANALYSIS OF NUTRIENT LOADING, NUTRIENT RETENTION AND NET ECOSYSTEM METABOLISM IN THREE TIDAL RIVER ESTUARIES DIFFERING PREDOMINATELY BY THEIR WATERSHED LAND USE TYPES.  

Science.gov (United States)

Abstract and oral presentation for the Estuarine Research Federation Conference. Estuarine retention of watershed nutrient loads, system-wide nutrient biogeochemical fluxes, and net ecosystem metabolism (NEM) were determined in three estuaries exhibiting differing magnitud...

323

Phytoplankton and environmental factors in the Paraíba do Norte River Estuary, northeastern Brazil: composition, distribution and quantitative remarks  

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Full Text Available This paper reports the results obtained from studies on the estuarine phytoplankton of the Paraíba do Norte River in northeastern Brazil. Surface and near-bottom samples were taken at four stations numbered seawards, during high and low tides from September 1978 to September 1979. A total of 139 phytoplankters were encountered. Diatoms and dinoflagellates showed highest diversity in most saline areas. Typical freshwater organisms were restricted to stations I and II where salinity was more reduced. Maximum cell densities were: 11,256,000 cells/1, 4,380,000 cells/1, 1,276,000 cells/1 and 1,035,000 cells/1, for stations I, II, III and IV, respectively. Sewage enrichments were probably responsible for the greatest values of the first two stations. However, in these stations the turbidity reduces light penetration, limiting phytoplankton growth particularly during the rainy season. The phytoflagellates (maximum of up to 4,874,000 cells/1) and the diatoms Thalassiosira spp (maximum of up to 9,262,000 cells/1) were dominant during the annual cycle. Other important taxa were Navicula spp, Cylindrotheca closterium, Paralia sulcata, Thalassionema nitzschioides and the dinoflagellate Protoperidinium spp. Seasonal variations of phytoplankton densities, dissolved oxygen, phosphate, water transparency, temperature, salinity and suspended material are also presented.

Roberto Sassi

1991-01-01

324

Impacts of the construction of the Port of Suape on phytoplankton in the Ipojuca River estuary (Pernambuco-Brazil)  

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Full Text Available In order to address the impact on phytoplankton, sampling was conducted monthly at 4 fixed stations, from April/86 to March/87 at diurnal low and high tide using a plankton net (65 mum mesh size) and a 1 L Van Dorn bottle. Among the 133 taxa identified, marine littoral euryhaline species were most common, outranking Gyrosigma balticum (Ehrenberg) Rabenhorst, Nitzschia sigma (Kützing) Wm. Smith, Licmophora abbreviata Agardh, Climacosphenia moniligera Ehrenberg, Surirella febigerii Lewis, Terpsinoe musica Ehrenberg and Cylindrotheca closterium (Ehrenberg) Reiman and Lewis. The port construction caused significant changes to the phytoplankton community with a strong influence of marine species (mainly dinoflagellate) because of the opening of the reef near the river mouth in 1983. The shallow depth and hydrodynamic brought many littoral species to the water columm. The community was composed by marine euryhaline and limnetic organisms, influenced by the salinity, rain and tide. Species diversity was high (> 3 bits.cel-1) owing to the high environmental heterogeneity (marine, freshwater and benthic interactions). After the port implantation, a strong decrease occurred in phytoplankton density owing to high loads of suspended matter. Lowest values (121,00 cells.l-1) were registered during rainy season. During dry season, when light intensity was higher, phytoplankton presented highest density ( 1,789,000 cells.l-1).

Koening Maria Luise; Leça Enide Eskinazi; Neumann-Leitão Sigrid; Macêdo Silvio José de

2003-01-01

325

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

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

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

2013-01-01

326

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

Directory of Open Access Journals (Sweden)

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

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

2012-01-01

327

Measuring natural phytoplankton fluorescence and biomass: a case study of algal bloom in the Pearl River estuary.  

UK PubMed Central (United Kingdom)

A moored optical buoy was deployed in the Pearl River estuarine waters for a 15-day period. A four-day algal bloom event occurred during this study period. Both chlorophyll a concentration and algal cell density (a proxy for biomass) changed dramatically before and after the event. The chlorophyll concentration at a 2.3m depth rose from 5.15 mg/m(-3) at 15:00 h on August 19 to 23.62 mg/m(-3) at 9:00 h on August 21, and then decreased to 3.24 mg/m(-3) at 15:00 h on August 24. The corresponding cell density ranged from 1.57 x 10(5) to 1.76 x 10(6)cells/L. We used normalized fluorescence line height (NFLH) and normalized fluorescence intensity (NFI) in order to determine fluorescence activity. Combined with the in situ sampling dataset, we were able to correlate natural fluorescence (NFLH and NFI) with chlorophyll a concentrations, and found correlation coefficients of 0.72 and 0.75, respectively. We also found correlations between natural fluorescence and cell density, with correlation coefficients of 0.71 and 0.65, respectively. These results indicate that applying continuous time series of natural fluorescence can reflect changes in biomass. This technique will prove extremely useful for in situ and real-time observations using an optical buoy. Although there are still problems to solve in the real-time observation of natural fluorescence in algal bloom events, we discuss the primary factors affecting fluorescence signals and suggest possible methods for mitigating these issues.

Zhao J; Cao W; Yang Y; Wang G; Zhou W; Sun Z

2008-10-01

328

Sensitivity mapping for oil spill response at the estuaries of the rivers Eider, Elbe, Weser and Ems; Sensitivitaetskartierung zur Oelbekaempfung an den Unterlaeufen von Eider, Elbe, Weser und Ems  

Energy Technology Data Exchange (ETDEWEB)

During this project the estuaries of the rivers Eider, Elbe, Weser and Ems, meeting the North Sea, were evaluated with respect to their vulnerability against oil accidents. Thus a corresponding intention concerning the ''Wadden Sea'' at the German North Sea Coast could be proceeded and completed (GKSS 2007/2). The assessment of different watersides shall provide decision support for oil spill response. Only comparatively near-natural areas of river banks were incorporated, with the basic evaluation of their importance for nature conservation as well as their oil spill sensitivity. Socioeconomic characteristics have not been evaluated, but some important properties are depicted on charts by symbols. The data used for the evaluation process cover the types of biotopes, tidal flats, nesting/non-nesting birds, rare plants as well as fishes, morphological conditions of watersides and official area-categories (i.e. protected natural area). Riverine and intertidal areas are fundamentally differentiated. With respect to seasonal aspects, the evaluation was established for three different times of the year. The result of the evaluation process is the classification of the individual watersides into 4 classes of priority (for oil spill response) and 8 classes of sensitivity. The priorityclasses are depicted by colours and the sensitivity-classes by numbers on sea-charts as topographic background (scale 1:25.000). The evaluation results are delayed on printed as well as GIS-based maps, connected to a data base. The amount of very sensitive areas is higher in the estuaries of the rivers Elbe and Eider compared to Ems and Weser and shows the highest values at all rivers during spring. The evaluation procedure is automated to a large extend by use of linked tables and a decision tree of if/then-functions. The underlying structure provides for a reliable transformation of new data into the corresponding evaluation during updating processes. (orig.)

Bernem, K.H. van; Krasemann, H. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Kuestenforschung; Fleischmann, J.; Krueger, D.; Luebbe, T.P.

2007-07-01

329

Community structure of the ichthyofauna associated with seagrass beds ( Halodule wrightii) in Formoso River estuary - Pernambuco, Brazil  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Pradarias de fanerógamas são utilizadas pela ictiofauna, de maneira geral como ambiente de berçário, abrigo contra predadores, diminuição de competição em aior disponibilidade de recursos alimentares, estabelecendo uma relação de conectividade com demais ecossistemas costeiros. No presente estudo foi avaliada a estrutura da ictiofauna associada às pradarias de fanerógamas do estuário do Rio Formoso no litoral de Pernambuco durante o inverno de 2008. Foram rea (more) lizados no total 27 arrastos manuais (15 diurnos e 12 noturnos), nos quais foram amostrados 358 peixes pertencentes a 18 famílias, 21 gêneros e 25 espécies. A Captura por unidade de esforço (CPUE) média por arrasto foi de 13,5 indivíduos e 4,95 espécies por arrasto. As famílias mais abundantes foram Scaridae (n = 111), Tetraodontidae (n = 63), Lutjanidae (n = 56), Mullidae (n = 39) e Engraulidae (n = 19). Analisando os índices ecológicos, observou-se que os mesmos foram sempre maiores para o período da noite, confirmando o fato do uso de tais áreas pela ictiofauna de forma mais intensa neste período. A necessidade de medidas para proteção destas áreas é evidente na região devido a sua importância e vulnerabilidade a impactos antrópicos. Abstract in english Seagrass beds are used by juvenile fishes in different ways, generally as nursery sites, shelter from predators, reducing competition and increasing availability of food resources, thus establishing a relationship of connectivity with other ecosystems. In the present study, the community structure of the ichthyofauna associated with seagrass beds on the Formoso River (Pernambuco - Brazil) was evaluated during the winter of 2008. Twenty-seven manual trawls (15 daytime and (more) 12 nighttime) were performed, and a total of 358 fishes belonging to 18 families, 21 genus and 25 species were collected. The Catch Per Unit Effort (CPUE) by trawling average was 13.5 and 4.95 individuals per species per trawl. The most abundant families were Scaridae (n = 111), Tetraodontidae (n = 63), Lutjanidae (n = 56), Mullidae (n = 39) and Engraulidae (n = 19). Ecological indices for dial changes were always higher for the night period, confirming that such areas are used more frequently during this period. The need for measures to conserve these areas is emphasized, by its importance and vulnerability to human impacts.

Pereira, Pedro H.C.; Ferreira, Beatrice P.; Rezende, Sérgio M.

2010-09-01

330

Community structure of the ichthyofauna associated with seagrass beds ( Halodule wrightii) in Formoso River estuary - Pernambuco, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available Seagrass beds are used by juvenile fishes in different ways, generally as nursery sites, shelter from predators, reducing competition and increasing availability of food resources, thus establishing a relationship of connectivity with other ecosystems. In the present study, the community structure of the ichthyofauna associated with seagrass beds on the Formoso River (Pernambuco - Brazil) was evaluated during the winter of 2008. Twenty-seven manual trawls (15 daytime and 12 nighttime) were performed, and a total of 358 fishes belonging to 18 families, 21 genus and 25 species were collected. The Catch Per Unit Effort (CPUE) by trawling average was 13.5 and 4.95 individuals per species per trawl. The most abundant families were Scaridae (n = 111), Tetraodontidae (n = 63), Lutjanidae (n = 56), Mullidae (n = 39) and Engraulidae (n = 19). Ecological indices for dial changes were always higher for the night period, confirming that such areas are used more frequently during this period. The need for measures to conserve these areas is emphasized, by its importance and vulnerability to human impacts.Pradarias de fanerógamas são utilizadas pela ictiofauna, de maneira geral como ambiente de berçário, abrigo contra predadores, diminuição de competição em aior disponibilidade de recursos alimentares, estabelecendo uma relação de conectividade com demais ecossistemas costeiros. No presente estudo foi avaliada a estrutura da ictiofauna associada às pradarias de fanerógamas do estuário do Rio Formoso no litoral de Pernambuco durante o inverno de 2008. Foram realizados no total 27 arrastos manuais (15 diurnos e 12 noturnos), nos quais foram amostrados 358 peixes pertencentes a 18 famílias, 21 gêneros e 25 espécies. A Captura por unidade de esforço (CPUE) média por arrasto foi de 13,5 indivíduos e 4,95 espécies por arrasto. As famílias mais abundantes foram Scaridae (n = 111), Tetraodontidae (n = 63), Lutjanidae (n = 56), Mullidae (n = 39) e Engraulidae (n = 19). Analisando os índices ecológicos, observou-se que os mesmos foram sempre maiores para o período da noite, confirmando o fato do uso de tais áreas pela ictiofauna de forma mais intensa neste período. A necessidade de medidas para proteção destas áreas é evidente na região devido a sua importância e vulnerabilidade a impactos antrópicos.

Pedro H.C. Pereira; Beatrice P. Ferreira; Sérgio M. Rezende

2010-01-01

331

PCBs and organochlorine pesticides in blubber biopsies from free-ranging St. Lawrence River Estuary beluga whales (Delphinapterus leucas), 1994-1998  

International Nuclear Information System (INIS)

[en] Measuring contaminants only in stranded whales may result in overestimation of organochlorines. - For the first time, organochlorine (OC) contaminants were measured in blubber biopsies from free-ranging St. Lawrence River Estuary beluga whales (Delphinapterus leucas), to compare contaminant levels to those previously measured in dead stranded belugas. PCBs, DDTs, toxaphene and chlordane-related compounds were the major OC contaminants detected in 44 belugas biopsied in 1994-1998. ?PCB (the sum of 104 congeners) ranged from 2080 to 128,000 ng/g lipid in males (n=34; minimum estimated ages 8-22 years), and from 148 to 44,100 ng/g lipid in females (n=10; minimum estimated ages 7-22 years). The concentrations of PCBs and OC pesticides in the blubber of these whales overlapped those observed in stranded belugas from an earlier study, and demonstrated comparable age and sex-related trends. However, lower proportions of mirex, HCB, DDTs, and many of the highly chlorinated PCBs occurred in the biopsy samples compared to results for blubber from stranded carcasses. Most major OC compounds were present at lower concentrations in the biopsies, but this does not appear to be solely related to age differences between the two groups, or to emaciation in the stranded whales. Nor does it appear to be associated with the use of superficial biopsies, and the possible stratification of lipids and OCs in the blubber layer. Nevertheless, given these possible confounding factors, and the uncertainty in age estimates for the biopsied whales, the results point to the need for careful interpretation of biopsy results when comparing with data taken from the full depth of the blubber mantle in stranded whales. Taken together, results from both biopsied whales and previously studied stranded belugas indicate that PCB and OC pesticide contamination of St. Lawrence beluga whales may occur across a broader range of levels than previously thought, at least for males which formed the largest group in this study, possibly due to different degrees of dietary exposure. It also appears that measuring contaminant concentrations only in stranded whales, may overestimate OC levels in the population as a whole, especially for highly chlorinated OCs

332

Impacts of the construction of the Port of Suape on phytoplankton in the Ipojuca River estuary (Pernambuco-Brazil)  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese A implantação do Complexo Industrial Portuário de Suape (Pernambuco-Brasil) entre 1979 e 1984, modificou os processos ecológicos observados no estuário do rio Ipojuca. As amostras foram coletadas mensalmente em 4 estações fixas, no período de abril/86 a março/87 nas preamares e baixa-mares diurnas, utilizando-se uma rede de plâncton com abertura de malha de 65 mim e garrafas de Van Dorn. Foram identificados um total de 133 taxa. As espécies marinhas litorais fo (more) ram as mais comuns e freqüentes, destacando-se: Gyrosigma balticum (Ehrenberg) Rabenhorst, Nitzschia sigma (Kützing) Wm. Smith, Licmophora abbreviata Agardh, Climacosphenia moniligera Ehrenberg, Surirella febigerii Lewis, Terpsinoe musica Ehrenberg and Cylindrotheca closterium (Ehrenberg) Reiman and Lewis. A composição florística do fitoplâncton mostrou diferenças significativas após a construção do Porto, tendo ocorrido uma maior representação de espécies marinhas, principalmente de dinoflagelados, as quais, com a abertura dos recifes foram mais facilmente carreadas para o estuário. A flora esteve caracterizada por espécies litorais, que em virtude da pequena profundidade e aumento do hidrodinamismo, chegam à camada superficial da coluna da água. A comunidade fitoplanctônica está influenciada pela salinidade, precipitação pluviométrica e variações de marés. Devido à interação de diversos fluxos, a diversidade específica foi elevada (> 3 bits.cel-1), demonstrando haver uma heterogeneidade ambiental. Após a construção do Porto, foi verificado uma diminuição da densidade fitoplanctônica devido à grande quantidade de material em suspensão, sendo a luz o fator limitante. Os menores valores foram registrados no período chuvoso (121.000 cel.l-1), apesar das concentrações elevadas de nutrientes. No período seco, quando a intensidade luminosa é mais intensa, o fitoplâncton apresenta as maiores densidades (1.789.000 cel.l-1). Abstract in english In order to address the impact on phytoplankton, sampling was conducted monthly at 4 fixed stations, from April/86 to March/87 at diurnal low and high tide using a plankton net (65 mum mesh size) and a 1 L Van Dorn bottle. Among the 133 taxa identified, marine littoral euryhaline species were most common, outranking Gyrosigma balticum (Ehrenberg) Rabenhorst, Nitzschia sigma (Kützing) Wm. Smith, Licmophora abbreviata Agardh, Climacosphenia moniligera Ehrenberg, Surirella (more) febigerii Lewis, Terpsinoe musica Ehrenberg and Cylindrotheca closterium (Ehrenberg) Reiman and Lewis. The port construction caused significant changes to the phytoplankton community with a strong influence of marine species (mainly dinoflagellate) because of the opening of the reef near the river mouth in 1983. The shallow depth and hydrodynamic brought many littoral species to the water columm. The community was composed by marine euryhaline and limnetic organisms, influenced by the salinity, rain and tide. Species diversity was high (> 3 bits.cel-1) owing to the high environmental heterogeneity (marine, freshwater and benthic interactions). After the port implantation, a strong decrease occurred in phytoplankton density owing to high loads of suspended matter. Lowest values (121,00 cells.l-1) were registered during rainy season. During dry season, when light intensity was higher, phytoplankton presented highest density ( 1,789,000 cells.l-1).

Koening, Maria Luise; Leça, Enide Eskinazi; Neumann-Leitão, Sigrid; Macêdo, Silvio José de

2003-01-01

333

Impacts of the construction of the Port of Suape on phytoplankton in the Ipojuca River estuary (Pernambuco-Brazil)  

Directory of Open Access Journals (Sweden)

Full Text Available In order to address the impact on phytoplankton, sampling was conducted monthly at 4 fixed stations, from April/86 to March/87 at diurnal low and high tide using a plankton net (65 mum mesh size) and a 1 L Van Dorn bottle. Among the 133 taxa identified, marine littoral euryhaline species were most common, outranking Gyrosigma balticum (Ehrenberg) Rabenhorst, Nitzschia sigma (Kützing) Wm. Smith, Licmophora abbreviata Agardh, Climacosphenia moniligera Ehrenberg, Surirella febigerii Lewis, Terpsinoe musica Ehrenberg and Cylindrotheca closterium (Ehrenberg) Reiman and Lewis. The port construction caused significant changes to the phytoplankton community with a strong influence of marine species (mainly dinoflagellate) because of the opening of the reef near the river mouth in 1983. The shallow depth and hydrodynamic brought many littoral species to the water columm. The community was composed by marine euryhaline and limnetic organisms, influenced by the salinity, rain and tide. Species diversity was high (> 3 bits.cel-1) owing to the high environmental heterogeneity (marine, freshwater and benthic interactions). After the port implantation, a strong decrease occurred in phytoplankton density owing to high loads of suspended matter. Lowest values (121,00 cells.l-1) were registered during rainy season. During dry season, when light intensity was higher, phytoplankton presented highest density ( 1,789,000 cells.l-1).A implantação do Complexo Industrial Portuário de Suape (Pernambuco-Brasil) entre 1979 e 1984, modificou os processos ecológicos observados no estuário do rio Ipojuca. As amostras foram coletadas mensalmente em 4 estações fixas, no período de abril/86 a março/87 nas preamares e baixa-mares diurnas, utilizando-se uma rede de plâncton com abertura de malha de 65 mim e garrafas de Van Dorn. Foram identificados um total de 133 taxa. As espécies marinhas litorais foram as mais comuns e freqüentes, destacando-se: Gyrosigma balticum (Ehrenberg) Rabenhorst, Nitzschia sigma (Kützing) Wm. Smith, Licmophora abbreviata Agardh, Climacosphenia moniligera Ehrenberg, Surirella febigerii Lewis, Terpsinoe musica Ehrenberg and Cylindrotheca closterium (Ehrenberg) Reiman and Lewis. A composição florística do fitoplâncton mostrou diferenças significativas após a construção do Porto, tendo ocorrido uma maior representação de espécies marinhas, principalmente de dinoflagelados, as quais, com a abertura dos recifes foram mais facilmente carreadas para o estuário. A flora esteve caracterizada por espécies litorais, que em virtude da pequena profundidade e aumento do hidrodinamismo, chegam à camada superficial da coluna da água. A comunidade fitoplanctônica está influenciada pela salinidade, precipitação pluviométrica e variações de marés. Devido à interação de diversos fluxos, a diversidade específica foi elevada (> 3 bits.cel-1), demonstrando haver uma heterogeneidade ambiental. Após a construção do Porto, foi verificado uma diminuição da densidade fitoplanctônica devido à grande quantidade de material em suspensão, sendo a luz o fator limitante. Os menores valores foram registrados no período chuvoso (121.000 cel.l-1), apesar das concentrações elevadas de nutrientes. No período seco, quando a intensidade luminosa é mais intensa, o fitoplâncton apresenta as maiores densidades (1.789.000 cel.l-1).

Maria Luise Koening; Enide Eskinazi Leça; Sigrid Neumann-Leitão; Silvio José de Macêdo

2003-01-01

334

OCEANOGRAPHIC AND BIOGEOCHEMICAL CHARACTERIZATION OF TAVARES AND DEFUNTOS RIVERS ESTUARIES, PIRAJUBAÉ EXTRACTIVIST RESERVE, FLORIANÓPOLIS, SC CARACTERIZAÇÃO OCEANOGRÁFICA E BIOGEOQUÍMICA DOS ESTUÁRIOS DOS RIOS TAVARES E DEFUNTOS, RESERVA EXTRATIVISTA DE PIRAJUBAÉ, FLORIANÓPOLIS, SC  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a preliminary assessment on the oceanographic and biogeochemical characteristics of the Tavares River (ERT) and Defuntos River (ERD) estuaries, located in the Limões Bight, Pirajubaé Extractivist Reserve, Florianópolis, SC. Field surveys were carried out in the estuaries at June 30th on July 1st, 2000, along complete tidal cycles, 13 hours, under spring tide condition. At every survey the follow parameters were monitored: current speed and direction, salinity, temperature, particulate suspended matter (PSM), pH, dissolved oxygen, and inorganic dissolved nutrients concentration (ammonium, nitrite, nitrate, phosphate and silicon). In spite of being close one another less than 1 km, the estuaries showed considerably differences in the intra-tidal variation of the monitored parameters. The parameters in the ERT showed good coherence with flood and ebb tidal phases, meanwhile in the ERD they showed more complex pattern. In terms of net transport, the ERT exports PSM and nutrients towards Limões bight, and the ERD imports PSM though exports nutrients. Beside the major influence of the astronomical semi-diurnal tide, seiches are also important to these estuaries. The main seiches periods ranged between 1 and 2 hours. Este artigo apresenta uma caracterização preliminar das condições oceanográficas e biogeoquímicas dos estuários dos rios Tavares (ERT) e Defuntos (ERD), localizados no Saco dos Limões, Reserva Extrativista de Pirajubaé, Florianópolis, SC. Nos dias 30 de junho e 1 de julho de 2000 foram realizadas campanhas de coleta de dados em cada estuário durante ciclos completos de maré, 13 horas, sob condição de maré de sizígia. Nestas campanhas foram monitorados: velocidade e direção de corrente, salinidade, temperatura, material particulado em suspensão (MPS), pH e oxigênio dissolvido, e concentração de nutrientes inorgânicos dissolvidos (amônio, nitrito, nitrato, fosfato e silício). Apesar de estarem distantes menos de 1 km, os estuários apresentaram significativas diferenças na variação intramareal dos parâmetros amostrados. Os parâmetros observados no ERT apresentaram maior coerência com as fases de enchente e vazante de maré, ao passo que no ERD as variações apresentaram padrões mais complexos. Em termos de transporte residual, observou-se que o ERT exporta sedimentos e nutrientes para o Saco dos Limões enquanto o ERD importa sedimentos, porém exporta nutrientes. Além da influência principal da maré astronômica semi-diurna sobre os estuários, seiches também desempenham papel importante, apresentando estes períodos entre 1 e 2 horas.

C. A. SCHETTINI; J. PEREIRA Fo.; L. SPILLERE

2000-01-01

335

Historic Habitat Opportunities and Food-Web Linkages of Juvenile Salmon in the Columbia River Estuary and Their Implications for Managing River Flows and Restoring Estuarine Habitat, Physical Sciences Component, Progress Report.  

Energy Technology Data Exchange (ETDEWEB)

Long-term changes and fluctuations in river flow, water properties, tides, and sediment transport in the Columbia River and its estuary have had a profound effect on Columbia River salmonids and their habitat. Understanding the river-flow, temperature, tidal, and sediment-supply regimes of the Lower Columbia River (LCR) and how they interact with habitat is, therefore, critical to development of system management and restoration strategies. It is also useful to separate management and climate impacts on hydrologic properties and habitat. This contract, part of a larger project led by the National Oceanic and Atmospheric Administration (NOAA), consists of three work elements, one with five tasks. The first work element relates to reconstruction of historic conditions in a broad sense. The second and third elements consist, respectively, of participation in project-wide integration efforts, and reporting. This report focuses on the five tasks within the historic reconstruction work element. It in part satisfies the reporting requirement, and it forms the basis for our participation in the project integration effort. The first task consists of several topics related to historic changes in river stage and tide. Within this task, the chart datum levels of 14 historic bathymetric surveys completed before definition of Columbia River Datum (CRD) were related to CRD, to enable analysis of these surveys by other project scientists. We have also modeled tidal datums and properties (lower low water or LLW, higher high water or HHW, mean water level or MWL, and greater diurnal tidal range or GDTR) as a function of river flow and tidal range at Astoria. These calculations have been carried for 10 year intervals (1940-date) for 21 stations, though most stations have data for only a few time intervals. Longer-term analyses involve the records at Astoria (1925-date) and Vancouver (1902-date). Water levels for any given river flow have decreased substantially (0.3-1.8 m, depending on river flow and tidal range), and tidal ranges have increased considerably (by a factor of 1.5 to 4 for most river-flow levels) since the 1900-1940 period at most stations, with the largest percentage changes occurring at upriver stations. These changes have been caused by a combination of changes in channel roughness, shape and alignment, changes in coastal tides, and (possibly) bed degradation. Tides are growing throughout the Northeast Pacific, and Astoria (Tongue Pt) has one of the most rapid rates of increase in tidal range in the entire Eastern Pacific, about 0.3m per century. More than half of this change appears to result from changes within the system, the rest from larger scale changes in coastal tides. Regression models of HHW have been used to estimate daily shallow water habitat (SWHA) available in a {approx}25 mile long reach of the system from Eagle Cliff to Kalama for 1925-2004 under four different scenarios (the four possible combinations of diked/undiked and observed flow/ virgin flow). More than 70% of the habitat in this reach has been lost (modern conditions vs. virgin flow with not dikes). In contrast, however, to the reach between Skamokawa and Beaver, selective dike removal (instead of a combination of dike removal and flow restoration) would suffice to increase spring SWHA. The second task consists of reconstruction of the hydrologic cycle before 1878, based on historic documents and inversion of tidal data collected before the onset of the historic flow record in 1878. We have a complete list of freshet times and peak flows for 1858-1877, and scattered freshet information for 1841-1857. Based on tidal data, we have reconstructed the annual flow cycles for 1870 and 1871; other time periods between 1854 and 1867 are under analysis. The three remaining tasks relate to post-1878 hydrologic conditions (flows, sediment supply and water temperature), and separation of the human and climate influences thereon. Estimated ob-served (sometimes routed), adjusted (corrected for reservoir manipulation) and virgin (corrected also for irrigation div

Jay, David A. [Portland State University

2009-08-03

336

Statistical Summary: EMAP-Estuaries Virginian Province, 1990 to 1993.  

Science.gov (United States)

Monitoring of indicators of the ecological condition of bays, tidal rivers, and estuaries within the Virginian Biogeographic Province (Cape Cod, Massachusetts to Cape Henry, Virginia) was conducted annually by the U.S. EPA's Environmental Monitoring and A...

C. J. Strobel D. R. Reifsteck E. A. Petrocelli H. W. Buffum S. J. Benyi

1995-01-01

337

Modelo Geomorfológico De Un Estuario Tropical Caribeño: Desembocadura Del Río Hueque, Costa Oriental Del Estado Falcón, Venezuela/ Geomorphologic Model Of A Tropical Estuary In The Caribbean Region: The Mouth Of The Hueque River, East Coast Of The Falcon State, Venezuela  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish El propósito principal de este trabajo es establecer un modelo geomorfológico que sintetice la dinámica del sistema estuarino de la desembocadura del río Hueque. Para el desarrollo del modelo se realizaron trabajos de campo en los que se recolectaron muestras de sedimentos de los ambientes depositacionales identificados, así como mediciones de las dimensiones de éstos, pendientes de playa, batimetría, oleaje y mareas. Se midieron parámetros físicos y químicos de (more) l agua como temperatura, pH, salinidad, conductividad eléctrica y transparencia. El trabajo de laboratorio se fundamentó en los análisis de textura, carbonatos, materia orgánica, minerales pesados y mineralogía por difracción de rayos X de las muestras de sedimentos. Se analizaron datos de clima, red de drenaje, mareas y oleaje y se realizó una fotointerpretación detallada del área. El estuario del río Hueque se comporta similar a un caño de marea, con aguas mezcladas y sin estratificación, fuerte tendencia a la hipersalinidad y pH entre neutro y ligeramente básico. Sobre la base de los factores y los procesos implicados, las características sedimentológicas de los ambientes depositacionales y el desarrollo y evolución del área, se concluyó que la desembocadura del río Hueque puede ser definida como un sistema estuarino de edad reciente. Abstract in english The main purpose of this article is to establish a geomorphologic model that synthesizes the dynamics of the estuary system at the mouth of the Hueque River. To develop the model a field study was conducted to collect and measure samples of sediments within the identified depositional environments. Simultaneously other measurements, including beach incline, tides and swell, were carried out. Physical and chemical parameters of the water were measured: temperature, pH, ele (more) ctric conductivity, transparency, and salinity. The laboratory work was based on analysis of textures, carbonates, organic matter, heavy minerals and mineralogy by X-ray diffraction of the sediment samples. Other types of data that was analyzed included, climate, drainage, tides, and swell. In addition, a detail photographic interpretation of the area was done. The Hueque River estuary behaves similarly to a tidal stream with mixed, non-stratified waters, strong tendency to hypersalinity and neutral pH or slightly basic. Based on the factors and implied processes, the sedimentary characteristics of the depositional environments and the development and evolution of the area, it was concluded that the mouth of the Hueque River can be define as a recent estuary system.

Cartaya, Scarlet; Méndez, Williams

2005-04-01

338

Levels of chromium contamination in the estuary of the Iraja river (Guanabara Bay) and experimental incorporation of 51Cr in barnacles (Balanus sp)  

International Nuclear Information System (INIS)

[en] Levels were determined of chromium contamination in the estuary of Iraja River, produced by an electroplating industry located 3 km upstream the study area. Uptake-and release kinetics of Cr(VI) and Cr(III) in barnacles (Balanus sp.) were studied. Samples of barnacles and suspended particles from Guanabara Bay were analysed. Chromium concentrations (dry weight) ranged from not detectable (ND) to 154,66 ?g/g for soft tissues and from ND to 423,76 ?g/g for suspended particles. Mean of maximum concentrations of chromium in samples from Guanabara Bay are 3 and 4 times above those of identical samples from control area (Coroa Grande). Soft tissues presented a concentration factor (CF) of 103 related to chromium available in suspended particles. 51Cr(VI) is preferentiably incorparated by soft tissues (biological half life being 100 days). Chromium uptake by Balanus sp from solution is as significant as it is from particulate matter available in sea water from experimental sets. CF for Cr(VI) in soft tissues in laboratory conditions was 102 related to 51Cr present in sea water. Environmental chromium contamination was found to be of the same order of magnitude or above levels reported for other areas subjected to industrial impacts. Barnacles appear to be able to accumulate chromium in soft tissues from the available metal in the environment. Cr(VI) is the critical form, being greatly accumulated in soft tissues of barnacles, that act as a long-term integrator of this metal. For Cr(III), this organism can only be regarded as an instantaneous indicator of environmental contamination of chromium attached to suspended particles. (M.A.)[pt] Avalia-se o grau de contaminacao por cromo do estuario do rio Iraja, produzida pelo lancamento de uma industria de eletrodeposicao de cromo, 3 km a montante do local de estudo. Estuda-se a cinetica de incorporacao e eliminacao do Cr(VI) e Cr(III) em cracas (Balanus sp.). Analisam-se amostras de cracas e particulas em suspensao da Baia de Guanabara (BG). Os resultados variaram entre nao detectavel (ND) e 154,66 ?g/g (tecidos moles) e ND e 423,76 ?g/g (particulas em suspensao). As medidas das concentracoes maximas da BG para tecidos moles e particulas em suspensao encontram-se 3 e 4 vezes acima daquelas de amostras identicas da area controle (Coroa Grande). Encontrou-se fator de concentracao (FC) de 103 para tecidos moles em relacao ao cromo disponivel nas particulas em suspensao. In vitro, 51Cr(VI) e preferencialmente incorporado nos tecidos moles (meia-vida biologica de 100d) sendo seu FC da ordem de 102 em relacao ao cromo das aguas dos aquarios. Conclui-se que ha contaminacao ambiental significativa por cromo. As cracas concentram cromo em seus tecidos moles a partir da disponibilidade do metal no meio ambiente. A forma hexavalente e critica pelo seu grande acumulo nos tecidos moles da craca, tornando-a um integrador do metal a longo prazo. Para Cr(III), este organismo so pode ser encarado como um indicador instantaneo de lancamentos ambientais de cromo. (M.A.)

1982-01-01

339

Short-term changes and longitudinal distribution of carbon metabolism in the Piauí River estuary (Sergipe, Brazil)/ Variações de curto prazo e distribuição longitudinal do metabolismo do carbono no estuário do Rio Piauí (Sergipe, Brasil)  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O metabolismo pelágico líquido (MPL) e o metabolismo líquido do ecossistema (MLE) foram medidos pela variação do sigmaCO2 em três pontos de amostragem no estuário do Rio Piauí. Na estação a montante, a amostragem foi conduzida durante 48 h. As amostras apresentaram uma alta relação NID:PID. A clorofila-a variou entre 0,2 e 2,5 mig.l-1, com concentrações superiores na estação a montante àquelas de maior influência marinha. O MPL oscilou de -13,2 a 61,2 mg (more) C.m-2.d-1. A presença de material mucilaginoso algal pode explicar os resultados de taxas metabólicas negativas (mineralização). Durante o período fótico, o MPL variou de -0,05 a 3,04 mgC.m-2.h-1. O MLE variou de -7,77 a 6,65 mgC.m-2.d-1. Ressuspensão de sedimento e uma pluma de alta turbidez refletiram-se em episódios de mineralização. Uma estimati