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1

Nutrient and caloric dynamics in Avicennia marina leaves at different developmental and decay stages in Zhangjiang River Estuary, China  

Science.gov (United States)

Avicennia marina is a typical mangrove species in the subtropical coastlines of China. The main objective of this study was to assess nutrient and caloric dynamics in A. marina leaves at different developmental and decay stages. Decomposition studies using litter bags suggested that the time required for the loss of half of the initial dry weight ( t50) was 19 days. The extracts of A. marina leaves contained non-tannin phenolics and tannin phenolics (hydrolysable tannin), but no condensed tannin. Non-tannin phenolics and tannin phenolics contents did not differ significantly from each other at various developmental stages, but decreased rapidly during leaf decomposition. Avicennia marina leaves had high N levels, and both N and P concentrations decreased significantly during senescence. During decomposition, N concentration of the leaf litter increased gradually but the phosphorus concentration showed a decrease in the first week, and both N and P remained the same towards the end of the experiment. The gross caloric value (GCV) of mature leaves was significantly higher than those of young and senescent leaves, while ash-free caloric value (AFCV) did not change significantly during leaf development and senescence. During leaf decomposition, both GCV and AFCV increased gradually and remained the same at late stages. In subtropical Zhangjiang River Estuary, high N levels and lack of condensed tannins in A. marina leaves were responsible for the fast rate of decay. Non-tannin phenolics and tannin phenolics had no great effect on rate of decay. Nitrogen resorption during leaf senescence, and high litter decomposition followed by nitrogen immobilization are the important nutrient conservation strategy for A. marina.

Zhou, Hai-Chao; Wei, Shu-Dong; Zeng, Qi; Zhang, Li-Hua; Tam, Nora Fung-yee; Lin, Yi-Ming

2010-03-01

2

Gammaridean amphipods in the Columbia River Estuary  

Energy Technology Data Exchange (ETDEWEB)

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

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

1976-01-01

3

LIMNETIC LARVAL FISH OF THE MAUMEE AND SANDUSKY RIVER ESTUARIES  

Science.gov (United States)

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

4

Estuaries: Where Rivers Meet the Sea  

Science.gov (United States)

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

5

Denitrification in the river estuaries of the northern Baltic Sea.  

Science.gov (United States)

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

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

2007-04-01

6

Rhenium and Molybdenum in Rivers and Estuaries.  

Science.gov (United States)

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

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

2004-12-01

7

Sediment Transport Processes In River Dominated Sub-Tropical Estuaries  

Science.gov (United States)

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

DAquino, Carla; Schettini, Carlos

2014-05-01

8

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

International Nuclear Information System (INIS)

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

9

Temporal Variability of Nutrient Budgets in a Tropical River Estuary  

Directory of Open Access Journals (Sweden)

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

Thanomsak Boonphakdee

2008-01-01

10

Physical biological coupling in the Pearl River Estuary  

Science.gov (United States)

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

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

2008-07-01

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

12

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

Science.gov (United States)

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

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

2005-01-01

13

The recreational value of river inflows into South African estuaries  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Estuarine habitats are subject to increasing demand pressures. Some of these are direct, for the appealing space they provide for residences and recreation; and some are indirect, in the form of competitive demand for the inputs required to maintain their ecological functionality, for instance, rive [...] r inflows. As a result of increasing demand for river water the connection of many of South Africa's estuaries with the sea has been undermined and their recreational appeal reduced. This paper reports findings on these negative impacts for selected estuaries. The contingent valuation method was used to estimate the value of recreational benefits that would result at 40 South African estuaries if water-inflow reductions were averted. The studies were undertaken between 2000 and 2007. All the estuaries selected were known to be vulnerable to changes in river inflows. Expert opinions on the consequences of specified hypothetical changes to water inflows into estuaries were used to generate the scenarios valued. User populations were estimated and surveys administered to samples of these populations. From the elicited responses median estuary user willingness to pay bids were predicted using Tobit and OLS models. An internal credibility assessment was conducted over the plausibility of the predictive model, the consistency of the values to those estimated using an alternative valuation method (the contingent travel cost method), and the reliability of the estimates. For the 37 estimates deemed reliable (but not necessarily valid), the average of the predicted median values of river inflow into estuaries was calculated to be 3.4 c/m³ (South African cents, ZAR) and standard deviation 3.84 c/m³. The average of the predicted mean values was calculated to be 7.4 c/m³ and the standard deviation 6.7 c/m³. It was also found that where there had been extensive economic development around the river system, the values of inflows into estuaries tended to be less than the value of water abstracted upstream.

Stephen, Hosking.

14

Modeling residual circulation and stratification in Oujiang River estuary  

Science.gov (United States)

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

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

2012-06-01

15

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

International Nuclear Information System (INIS)

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

16

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

Scientific Electronic Library Online (English)

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

JS, Beck; GR, Basson.

17

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)

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.

19

Local flows in the Quequén Grande River Estuary, Argentina  

Science.gov (United States)

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

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

2009-05-01

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.)

 
 
 
 
21

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

International Nuclear Information System (INIS)

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

22

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

Science.gov (United States)

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

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

2014-04-01

23

Occurrence and distribution of dissolved tellurium in Changjiang River estuary  

Science.gov (United States)

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

Wu, Xiaodan; Song, Jinming; Li, Xuegang

2014-03-01

24

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Drago Maguš

2009-01-01

25

REE in the Great Whale River estuary, northwest Quebec  

Science.gov (United States)

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

Goldstein, Steven J.; Jacobsen, Stein B.

1988-01-01

26

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

27

Primary fish survey in the Huanghe River estuary  

Science.gov (United States)

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

Yang, Jiming; Wang, Cunxin

1993-12-01

28

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

Science.gov (United States)

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

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

2007-06-01

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Identifying nearshore groundwater and river hydrochemical variables influencing water quality of Kaoping River Estuary using dynamic factor analysis  

Science.gov (United States)

SummaryThe Kaoping River Estuary receives a large amount of nonpoint source pollution and sedimentary discharge from the Kaoping and Tungkang Rivers each year. The Kaoping River Estuary is an integral part of the Kaoping River, shelf, and submarine canyon, which makes prediction of water quality variation difficult. This study attempts to determine the main factors regulating temporal and spatial variations in the water quality in the Kaoping River Estuary over a 9-year period (2003-2011), using dynamic factor analysis (DFA) and min/max autocorrelation factor analysis (MAFA). The result from the MAFA shows that Chlorophyll-a (Chl-a) has the highest canonical correlation coefficient with the min/max autocorrelation factor (MAF) axis of water quality. Therefore, Chl-a can be used as an indicator of water quality in the Kaoping River Estuary. The water quality and environmental variables measured downstream of the Kaoping and Tungkang Rivers, as well as submarine groundwater, influence temporal variations of Chl-a in the estuary. The optimal DFA model successfully described Chl-a variations (coefficient of efficiency = 0.969) in the Kaoping River Estuary. DFA results indicate that dissolved oxygen (DO), total suspended sediment (TSS), dissolved inorganic nitrogen (DIN), chemical oxygen demand (COD), as well as the biological oxygen demand (BOD) of river discharge, and the ammonium-nitrogen (NH4-N) concentration of groundwater discharge significantly influenced Chl-a dynamics. Submarine groundwater discharge, which is a significant source of nutrients for the coastal ocean, appears to impact the level of Chl-a concentration substantially. Understanding the relationship between environmental variables and the variability of Chl-a concentration provides a useful approach for setting water quality criteria and pollution prevention plans for the Kaoping River Estuary.

Kuo, Yi-Ming; Jang, Cheng-Shin; Yu, Hwa-Lung; Chen, Su-Chin; Chu, Hone-Jay

2013-04-01

30

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

Science.gov (United States)

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

Gong, Wenping; Shen, Jian; Jia, Liangwen

2013-02-01

31

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

Science.gov (United States)

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

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

1993-01-01

32

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

Science.gov (United States)

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

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

1984-01-01

33

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

Science.gov (United States)

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

Yang, Zhaoqing; Khangaonkar, Tarang

34

River input of dissolved uranium to the oceans; the Zaire river and estuary  

International Nuclear Information System (INIS)

A systematic sampling survey was carried out in the Zaire (Congo) river and estuary during November 1976 and May 1978. Dissolved 238U and 234U concentrations in filtered fresh waters are low. Simple mixing between fresh and seawater accounts for dissolved uranium concentrations in the estuary but it was not possible to confirm the predicted conservative behaviour of riverine uranium by comparison of its distribution with the theoretical dilution curve. Uranium removal in near-bottom samples taken from the almost anoxic water-body located near the head of the canyon probably accounts for the lower concentrations found in these samples. Data concerning dissolved 238U in world rivers are well correlated with total dissolved solids. This correlation permits a reassessment of 238U concentration in rivers flowing to the ocean resulting in a world wide estimate of 0.24 ?g/l. The dissolved river input of 238U to the ocean is comparable with output through the main sink processes

35

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

Science.gov (United States)

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

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

2012-08-01

36

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

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Pollution in the estuary of the Baracoa river, La Habana, Cuba  

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Full Text Available The environmental quality of the Baracoa river estuary was studied from the physic (temperature and salinity, chemic variables (dissolved oxygen, oxygen biochemical demand (DBO, oxygen chemical demand (DQO, nitrogen cycle, inorganic phosphorus and total phosphorus and the microbiological variables (total and thermotolerant coliforms and faecal streptococci. The samplings were made on February 2006, May and October 2007. Spatial distribution of the physical and chemical parameters measured suggests that the estuary is dominated by the marine conditions. The salinity and temperature analyses show that in general the characteristics of the estuary could be influenced by the contribution of the river basin drainage. In general, the concentrations of the measured parameters in the Baracoa river estuary, strongly suggest that this area is under influence of human activities on the river basin, due to the low levels of dissolved oxygen and an oxygen average deficit of -1.6 mg/L. nthropogenic actions in this estuary are mainly related to the emission of domestic and farming rejects without suitable treatment. This is visibly associated with the observed values of the total coliforms concentrations as well as the concentration of faecal streptococci, that surpassed reference values from the Cuban norm for water quality, following on bad or doubtful quality levels pointing out negatively measurements made next to the communication channel the estuary and the El Doctor lagoon.

Regla Duthit Somoza

2011-04-01

38

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

Science.gov (United States)

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

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

2014-01-01

39

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

40

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

International Nuclear Information System (INIS)

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

 
 
 
 
41

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-05-15

42

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

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

Drago Maguš

2009-10-01

43

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

44

PREDICTION OF TSUNAMI PROPAGATION IN THE PEARL RIVER ESTUARY  

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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.

2009-01-01

45

Nutrient input from the Loxahatchee River Environmental Control District sewage-treatment plant to the Loxahatchee River Estuary, southeastern Florida  

Science.gov (United States)

Two test discharges of treated-sewage effluent were made to the Loxahatchee River in February and September 1981 from the ENCON sewage-treatment plant to document nutrient loading and downstream transport of the effluent to the estuary under maximum daily discharge allowable by law (4 million gallons per day). Concentrations of total nitrogen in the effluent exceeded background concentrations by as much as 7 times during the February test, while concentrations of total phosphorus exceeded background concentrations by as much as 112 times during the September test. The effluent was transported downstream to the estuary in less than 24 hours. Discharge of treated sewage effluent to the river-estuary system in the 1981 water year accounted for less than 0.5 percent of the total nitrogen and 8 percent of the total phosphorus discharged from the major tributaries to the estuary. If maximum discharges of effluent (4 million gallons per day) were sustained throughout the year, annual nitrogen loading from the effluent would account for 5 to 18 percent of the total nitrogen input by the major tributaries to the estuary. With maximum discharges of effluent, annual phosphorus loading would exceed the amount of phosphorus input by the major tributaries to the estuary by 54 to 167 percent. (USGS)

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

1984-01-01

46

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

Science.gov (United States)

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

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

2005-05-01

47

Biogeochemical transport in the Loxahatchee River estuary, FL: The role of submarine groundwater discharge  

Science.gov (United States)

The distributions of dissolved organic carbon (DOC), silica, select trace elements (Mn, Fe, Ba, Sr, Co, V,) and a suite of naturally-occurring radionuclides in the U/Th decay series (222Rn, 223,224,226,228Ra, 238U) were studied during high and low discharge conditions in the Loxahatchee River estuary, Florida. The zero-salinity endmember of this still relatively pristine estuary may reflect not only river-borne constituents, but also those advected during active groundwater/surface-water discharge. During low discharge conditions, with the notable exception of Co, trace metals indicate nearly conservative mixing from a salinity of ~12 through the estuary (This statement contracdicts with what is said in p. 7). In contrast, of the trace metals studied, only Sr, Fe, U and V exhibited conservative estuarine mixing during high discharge. Dissolved organic carbon and Si concentrations were highest at zero salinities, and generally decreased with an increase in salinity during both discharge regimes, indicating removal of land-derived dissolved organic matter and silica in the estuary. Suspended particulate matter (SPM) concentrations were generally lowest ( 28 dpm L-1) at the freshwater endmember of the estuary, and appear to identify regions of the river most influenced by active submarine groundwater discharge (where is the data that show this?). Activities of four naturally-occurring isotopes of Ra (223,224,226,228Ra) in this estuary and select adjacent shallow groundwater wells indicate mean estuarine water mass residence times of less than 1 day; values in close agreement to those calculated by tidal prism and tidal period. A radium-based model for estimating submarine groundwater discharge to the Loxahatchee River estuary yielded an average of 1.03 V 3.84 x 105 m3 day-1, depending on river discharge stage as well as slight variations in the particular Ra models used. Such calculated flux estimates are in close agreement with results obtained from a 2-day electromagnetic seepage meter (0.9 x 105 m3 d-1) deployment during high discharge at the confluence of Kitching Creek and the Loxahatchee River, as well as with surficial aquifer recharge estimates. Calculated submarine ground-water discharge rates yield NH4+ and PO4-3 flux estimates to the Loxahatchee River estuary that range from 63 - 1060 ?Ymol m-2 d-1 and 69 - 379 ?Ymol m-2 d-1, respectively.

Swarzenski, P.; Orem, B.; McPherson, B.; Baskaran, M.; Wan, Y.

2005-05-01

48

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

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

Curt Peterson

2014-03-01

49

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

Science.gov (United States)

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

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

2010-04-01

50

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

Science.gov (United States)

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

Pan, Gang; You, Chun

2010-05-01

51

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

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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

52

Trace metals in estuaries in the Russian Far East and China: Case studies from the Amur River and the Changjiang.  

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This paper compares the distributions of dissolved and particulate forms of Mn, Fe, Ni, Cu, Zn, Cd, and Pb in the estuaries of the largest rivers in East Asia: the Amur River and the Changjiang (Yangtze River). High suspended solid concentrations, elevated pH, and relatively low dissolved trace metal concentrations are characteristics of the Changjiang. Elevated dissolved Fe and Mn concentrations, neutral pH, and relatively low suspended solid concentrations are characteristics of the Amur River. The transfer of dissolved Fe to suspended forms is typical in the Amur River estuary, though Cd and Mn tend to mobilize to solution, and Cu and Ni are diluted in the estuarine system. Metal concentrations in suspended matter in the Amur River estuary are controlled by the ratio of terrigenous riverine material, enriched in Al and Fe, and marine biogenic particles, enriched in Cu, Mn, Cd, and in some cases Ni. The increase in dissolved forms of Mn, Fe, Ni, Cu, Cd, and Pb compared with river end-member is unique to the Changjiang estuary. Particle-solution interactions are not reflected in bulk suspended-solid metal concentrations in the Changjiang estuary due to the dominance of particulate forms of these metals. Cd is an exception in the Changjiang estuary, where the increase in dissolved Cd is of comparable magnitude to the decrease in particulate Cd. Despite runoff in the Amur River being lower than that in the Changjiang, the fluxes of dissolved Mn, Zn and Fe in the Amur River exceed those in the Changjiang. Dissolved Ni, and Cd fluxes are near equal in both estuaries, but dissolved Cu is lower in the Amur River estuary. The hydrological and physico-chemical river characteristics are dominated at the assessment of river influence on the adjoining coastal sea areas despite differences in estuarine processes. PMID:25190045

Shulkin, Vladimir; Zhang, Jing

2014-11-15

53

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

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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...

54

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

Science.gov (United States)

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

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

2009-02-01

55

Nonlinear interaction between the tide and river flow in the Maule estuary, Chile  

Science.gov (United States)

The hydrodynamics features of an estuary are the resulting of two main driving forces, the tide and the river flow, interacting one each other and with the bathymetry. This periodic modulation may interact with the bathymetry such that exciting new tide harmonics, as a result of the nonlinear effect of bottom friction and advection terms. This nonlinear coupling between the tide and the estuary change when the river flow increases, which explains early theoretical studies that showed that when the river flow increases, there is a shift between M4 and M6 tide harmonic in the estuary. The objective of this study is to analyze field observation where this phenomenon is observed, for which numerical simulations conducted with FVCOM are used for fully understanding this nonlinear interactions between river inflow and tide harmonic excited in an estuary. Field measurements were conducted in June of 2011 in Maule estuary located in central Chile (°35.3S,°72.4W). During this period, the water surface and current were measured along the Thalweg. Also, river flow was continuously recorded at 29km upstream the estuary mouth, and these observations shows a river flow change that rapidly increased in a factor of two, changing the hydrodynamics conditions. Field observations were analyzing based on a least squares analysis, Fourier transforms and continuous wavelet transforms methodologies for processing measured time series. It is obtained that the dominant modes in the estuary are the M4 and M6 tide harmonic. Furthermore, the FVCOM numerical model was implemented to the estuary to study the response of the semi-enclosed system forced by a synthetic time series of the monochromatic M2 tide constituent, to see the excitation of M4 and M6 tide constituents. The results at the mouth of the estuary show that the magnitude of the current induced by the M4 and M6 tide constituents are higher at the bottom after the flood event by a factor of 1.5 and 2.3 respectively, with respect to conditions before the flood. In the contrary, M4 and M6 in the surface decreased because of the flood in a factor of 0.46 and 0.92. Finally, numerical simulation where the estuary was forced with a monochromatic M2 shows similar tendency with the anterior analysis. These results are coherent with the theoretical studies showed that bottom friction shift the magnitude of these harmonics; however, our observations in the surface indicates that the interaction between river flow and the tide depends on the vertical location. 1D numerical models or simple Fourier decomposition of the harmonics in the estuary are not enough to understand the real interaction of the river inflow with the induced current tides. Consequently, vertical variations in the flow velocity are required to be included.

Arce Morán, D. A.; De La Fuente, A.; Zamorano Riquelme, L.

2013-12-01

56

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

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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

57

Fish utilization of a salt marsh intertidal creek in the Yangtze River estuary, China  

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The structure and temporal variations of the fish community in salt marshes of Chinese estuaries are poorly understood. Fish utilization of a salt marsh intertidal creek in the Yangtze River estuary was studied based on quarterly sampling surveys in July and November, 2004, and February and May, 2005. Fishes were collected by consecutive day and night samplings using fyke nets during the ebbing spring tides. A total of 25,010 individuals were caught during the study. 17 families and 33 species were documented, and the most species-rich family was Gobiidae. Three species, Synechogobius ommaturus, Chelon haematocheilus and Lateolabrax maculatus together comprised 95.65% of the total catch, which were also the most important commercial fishery species in the Yangtze River estuary. The fish community was dominated by juvenile individuals of estuarine resident species. Time of year significantly affected fish use of salt marshes, but no significant effects of diel periodicity on the fish community were found except for fish sampling in July. These findings indicate that salt marshes in the Yangtze River estuary may play important nursery roles for fish community.

Jin, Binsong; Fu, Cuizhang; Zhong, Junsheng; Li, Bo; Chen, Jiakuan; Wu, Jihua

2007-07-01

58

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

Science.gov (United States)

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

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

2014-02-15

59

BED VARIATION ANALYSIS IN THE CHIKUGO RIVER ESTUARY BY THE FLOOD FLOWS  

Science.gov (United States)

A series of fisherie issues in the Ariake sea has been believed to be caused by a lack of sand supply from the Chikugo river on the basis of few investigations of characteristics and amount of sediment transport in the the Chikugo river estuary. The core sampling and super-sonic echo sounder indicates that the vertical structure of mid stream of the Chikugo river estuary is consists of complex alternate layer and the rate of water content is much different to each layer. To make the rate of sand transport in the Chikugo river estuary clear, the authors applied unsteady quasi-three dimensional flood flow and river bed variation analysis using observed temporal changes in water surface profiles of flood. In the analysis, the bed layer which the rate of water content upper than 70% is calculated 2009by the experimental equation of erosion speed of the cohesive material. The results of analysis indicates that the rate of sand supply is strongly affected by the tidal level change of the Ariake sea.

Suzuki, Kenta; Shimamoto, Hisanori; Kubo, Seiki; Fukuoka, Shoji

60

Hydrodynamic response of the Breton Sound estuary to pulsed Mississippi River inputs  

Science.gov (United States)

Pulsed re-introduction of Mississippi River water into the deltaic plain has been proposed as a wetland restoration strategy for coastal Louisiana. In this study, the hydrodynamic response of the Breton Sound estuary to a two-week pulse of Mississippi River water via the Caernarvon river diversion structure was investigated using a barotropic, three-dimensional, Finite-Volume Coastal Ocean Model (FVCOM). The numerical model was driven by tidal and subtidal forcing at the open Gulf boundary, freshwater discharge from the Caernarvon river diversion structure, as well as wind stress at the water surface. After successfully validating the model with field observations, three numerical experiments were run to assess the response of current, water level, and marsh flooding to different diversion discharge scenarios. The three scenarios considered were: a pulsed scenario of ˜200 m 3 s -1 corresponding to the actual diversion discharge in March 2001, a constant discharge scenario of 40 m 3 s -1 corresponding to the annually averaged discharge of 2001, and a scenario with no discharge. Numerical simulation results indicated that constant 40 m 3 s -1 discharge caused little change in wetland inundation comparing to the no discharge case and, thus, inter-exchange between deep channels and the wetlands was not improved by this rate of diversion discharge. In contrast, the two-week ˜200 m 3 s -1 discharge caused enhanced water exchange between wetlands and adjacent water bodies, substantially increasing water velocity in the bayous and channels of the upper estuary. These effects occurred in the estuary to about 20-25 km from the diversion structure, and caused a noticeable increase in down-estuary residual current with a significant reduction of local estuarine residence times for the whole estuary. Beyond 30 km from the diversion structure, the impact of high water discharge was small and the hydrodynamics was mostly controlled by tides and wind.

Huang, Haosheng; Justic, Dubravko; Lane, Robert R.; Day, John W.; Cable, Jaye E.

2011-11-01

 
 
 
 
61

Phytoplankton dynamics in and near the highly eutrophic Pearl River Estuary, South China Sea  

Science.gov (United States)

The dynamics of size-fractionated phytoplankton along the salinity gradient in the Pearl River Estuary and the adjacent near-shore oceanic water was investigated using microscopic, flow cytometric, and chlorophyll analyses in the early spring (March) and early autumn (September) of 2005. In the inner part of the estuary where salinity was less than 30, the phytoplankton community was dominated by micro- and nano-sized (3-200 ?m) cells, particularly the diatom Skeletonema costatum, both in early spring and early autumn. In areas where salinity >30, including the mixing zone and nearshore oceanic water, micro- and nano-sized cell populations dominated the phytoplankton assemblage during early spring when influence of river discharge was minimal, whereas pico-sized (?3 ?m) cell populations were dominant during early autumn as a result of strong river discharge in the summer, with Synechococcus and pico-eukaryotes being predominant. Picophytoplankton were two orders of magnitude more abundant in early autumn (10 6 cells mL -1) than in early spring in the nearshore oceanic water. Nutrients delivered by freshwater input to the estuary were pushed toward high salinity (>30) areas as a result of short residence time, exerting a strong influence on phytoplankton abundance, especially picophytoplankton in the nearshore, otherwise oligotrophic, water. Influenced by high abundance of DIN and limitation in phosphorus, picophytoplankton in the adjacent nearshore oceanic water rose to prominence seasonally. Our results indicate that eutrophication in the Pearl River Estuary not only stimulates the growth of S. costatum in the nutrient-rich areas of the estuary but also appears to promote the growth of Synechococcus and pico-eukaryotes in the adjacent usually oligotrophic oceanic water at least during our autumn cruise.

Qiu, Dajun; Huang, Liangmin; Zhang, Jianlin; Lin, Senjie

2010-02-01

62

Numerical simulation of seawater intrusion from estuary into river using a coupled modeling system  

Science.gov (United States)

One of the most important causes of the freshwater shortage in estuarine area is the increasing seawater intrusion into the river. To simulate seawater intrusion properly, two important factors should be considered. One is the bidirectional and time-dependent coupling effects between river discharges and tidal forces. The other is the three-dimensional and stratified structure of dynamic processes involved. However, these two factors have rarely been investigated simultaneously, or they were often simplified in previous researches, especially for the estuary connected with an upstream river network through multiple outlets such as the Pearl River Estuary (PRE). In order to consider these two factors, a numerical modeling system, which couples a one-dimensional river network model with a three-dimensional unstructured-grid Finite-Volume Coastal Ocean Model (FVCOM), has been developed and successfully applied to the simulation of seawater intrusion into rivers emptying into the PRE. By treating the river network with a one-dimensional model, computational efficiency has been improved. With coupling 1D and 3D models, the specification of upstream boundary conditions becomes more convenient. Simulated results are compared with field measured data. Good agreement indicates that the modeling system may correctly capture the physical processes of seawater intrusion into rivers.

Zou, Huazhi; Li, Huajun

2010-09-01

63

Sediment discharge into a subsiding Louisiana deltaic estuary through a Mississippi River diversion  

Science.gov (United States)

Wetlands of the Mississippi River deltaic plain in southeast Louisiana have been hydrologically isolated from the Mississippi River by containment levees for nearly a century. The ensuing lack of fluvial sediment inputs, combined with natural submergence processes, has contributed to high coastal land loss rates. Controlled river diversions have since been constructed to reconnect the marshes of the deltaic plain with the river. This study examines the impact of a pulsed diversion management plan on sediment discharge into the Breton Sound estuary, in which duplicate 185 m 3 s -1-diversions lasting two weeks each were conducted in the spring of 2002 and 2003. Sediment delivery during each pulse was highly variable (11,300-43,800 metric tons), and was greatest during rising limbs of Mississippi River flood events. Overland flow, a necessary transport mechanism for river sediments to reach the subsiding backmarsh regions, was induced only when diversion discharge exceeded 100 m 3 s -1. These results indicate that timing and magnitude of diversion events are both important factors governing marsh sediment deposition in the receiving basins of river diversions. Though the diversion serves as the primary source of river sediments to the estuary, the inputs observed here were several orders of magnitude less than historical sediment discharge through crevasses and uncontrolled diversions in the region, and are insufficient to offset present rates of relative sea level rise.

Snedden, Gregg A.; Cable, Jaye E.; Swarzenski, Christopher; Swenson, Erick

2007-01-01

64

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

Science.gov (United States)

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

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

1989-10-01

65

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

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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 t...

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

2013-01-01

66

Sonar Investigation of Sediment Deposition Patterns in the Delaware River Estuary  

Science.gov (United States)

Sedimentation in the Delaware River Estuary is influenced by natural hydrographic properties and engineering practices such as channel dredging and shoreline bulkheading, which influence sediment transport among its subenvironments. To better understand the regional sediment dynamics of this estuary, bottom sediments and morphologies were mapped using 390 miles of dual-frequency side-scan and Chirp sonar data between Trenton, NJ and New Castle, DE, a highly urbanized region. Sediment grabs (188) and cores (48) were collected to groundtruth the sonar data. Sonar imagery and grain size analysis reveal a sediment textural pattern that, in general, parallels the longitudinal salinity gradient of the estuary. In the northern extent of the study area (0-1 PSU), fluvial sands grade down estuary to muddy sands of possible marine origin in the southern extent (1-5 PSU). At the head of the salinity intrusion, three distinct locations of low acoustic backscatter are present within a larger area of higher backscatter. The low backscatter bottom corresponds to seasonally active mud deposits, whereas the high backscatter characterizes a dense mud bottom, mantled by a mobile veneer of sand and gravel. The zones of active deposition compose merely 8% of the total area of study, yet they contain a significant fraction of the suspended sediment inventory. The depositional zones are interpreted to reflect localized suspended sediment trapping, likely due to flocculation, as well as other processes that maintain the estuary turbidity maximum. The new sonar imagery has provided important insight into sediment budgetary and contaminant transport issues in the Delaware River Estuary; timeseries measurements of sediment transport are needed to elucidate the physical processes responsible for sediment trapping and deposition in the turbidity maximum region.

Walsh, D. R.; Sommerfield, C. K.

2002-12-01

67

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

Science.gov (United States)

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

Stanley, Donald W.

1993-08-01

68

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

69

Importance of a winter dinoflagellate-microflagellate bloom in the Patuxent River estuary  

Science.gov (United States)

A dense bloom of Katodinium rotundatum was observed in the Patuxent River estuary from December to February 1989. The dinoflagellate dominated phytoplankton densities reaching 10 8 cells l -1 and contributed up to 1900 ?gC l -1 in near-surface depths. The bloom maintained a distinct patch extending over 10-25 km of the estuary or approximately one-third to one-half of the total estuary (salinities from 5-13 ppt) and was restricted to regions immediately upriver of the transition between the shallow upriver (3-4 m) and deeper lower estuary (10 m). Daily measurements collected in the primary bloom area at the same time each day in the study area indicated 80- and 120-fold variations in chlorophyll and cell densities from day to day. Densities of potential grazers in the region were high with rotifers, primarily Synchaeta baltica, reaching densities of 1000 l -1 in early winter, and the copepod Eurytemora affinis reaching levels exceeding 1·15 × 10 5 m -3 in February. Estimates of grazing pressure by these planktonic herbivores indicated substantial grazing losses for the bloom, with up to 67% of bloom biomass consumed day -1 in February. Nutrient concentrations and ratios of N/P during the bloom suggested potentially N-limited conditions; bloom demise was coincident with a shift to high N/P ratios and high river flows. These data as well as other historical data suggest that dinoflagellate blooms in the lower Patuxent River estuary could be the primary source of carbon to the system during the winter and supply a large reservoir of labile organic matter to planktonic secondary producers prior to annual spring diatom blooms in the region.

Sellner, K. G.; Lacouture, R. V.; Cibik, S. J.; Brindley, A.; Brownlee, S. G.

1991-01-01

70

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

International Nuclear Information System (INIS)

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

71

Simulation of tidal flow and circulation patterns in the Loxahatchee River Estuary, southeastern Florida  

Science.gov (United States)

Results of a two-dimensional, vertically averaged, computer simulation model of the Loxahatchee River estuary show that under typical low freshwater inflow and vertically well mixed conditions, water circulation is dominated by freshwater inflow rather than by tidal influence. The model can simulate tidal flow and circulation in the Loxahatchee River estuary under typical low freshwater inflow and vertically well mixed conditions, but is limited, however, to low-flow and well mixed conditions. Computed patterns of residual water transport show a consistent seaward flow from the northwest fork through the central embayment and out Jupiter Inlet to the Atlantic Ocean. A large residual seaward flow was computed from the North Intracoastal Waterway to the inlet channel. Although the tide produces large flood and ebb flows in the estuary, tide-induced residual transport rates are low in comparison with freshwater-induced residual transport. Model investigations of partly mixed or stratified conditions in the estuary need to await development of systems capable of simulating three-dimensional flow patterns. (Author 's abstract)

Russell, G. M.; Goodwin, C. R.

1987-01-01

72

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

73

???????????????? 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.  

??

2012-10-01

74

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

International Nuclear Information System (INIS)

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

75

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

International Nuclear Information System (INIS)

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

76

Feeding of juvenile kaluga and amur sturgeon in the Amur river estuary  

Directory of Open Access Journals (Sweden)

Full Text Available Data on feeding of juvenile kaluga and Amur sturgeon in the Amur river estuary are presented for the first time. It is established that kaluga main food consists of fishes (98.4 %, as mollusks are dominant in Amur sturgeon food compositon (63.0 %. Kaluga main food components are fishes of Cyprinidae (43.1 %, Bagridae (24.5 % and Osmeridae (19.1 %, Amur sturgeon dominant prey are mollusks of Amuropaludina chloantha (39.6 % and Corbicula sp. (17.4 %. Dynamics of food composition in the period from May to October is described. It is defined that there is no competitive activity between juvenile kaluga and Amur sturgeon in the Amur river estuary part.

Koshelev Vsevolod Ni?kolaevich

2013-04-01

77

Density-salinity-suspended sediment experimental curves for Guadalquivir River estuary conditions  

Science.gov (United States)

Estuarine water in Mediterranean watersheds contains high suspended sediment concentrations due to both the fine textured nature of the materials reaching the final stretch of the fluvial network, and the agricultural predominance of soil uses upstream. Saline conditions induce flocculation processes which alter the original behavior of the soil particles in water. The final high density mixture of water-salts-sediments has physicochemical characteristics very different from the saline water alone. However, this is not often included when modeling the dynamics of estuaries, adopting the density, viscosity, etc., values corresponding to the present level of salinity found at each point. The nature of the local sediments influences the density values finally found. The Guadalquivir River estuary (southwestern Spain) extends along the 105 km between the Alcalá del Río dam, upstream, and its mouth in Sanlúcar de Barrameda. It is an Atlantic mesotidal estuary (Díez-Minguito et al., 2010) with a mainly longitudinal salinity gradient. The sediments in the estuary are very fine-textured due to the great length of the river and, mainly, the extreme trapping efficiency of the dense reservoir network upstream along the 57400 km2 of the contributing area. With an average value of 0.5 - 4.5 g L-1 for the suspended sediment range along the estuary, extreme values up to 160 g L-1 can be found associated with persistent turbidity events forced by different combinations of conditions. This work shows the density variation with changing bivariate conditions of salinity-suspended sediments, following the combined range found along the estuary. Laboratory measurements were made at 19° C for synthetic seawater with 35 g L-1salinity and the decreasing range found upstream by dilution until a final value of 0.2 g L-1, for which an increasing suspended sediment concentration (SSC) was induced by adding sediments locally extracted from the estuary. The final density of these sets of mixtures with SSC values from 0 to 4.5 g L-1 was determined. The results from the blank set of samples (0 SSC) followed the seawater state equation by UNESCO (1985) with a correlation coefficient of 0.9986. The results show the expected increasing trend for density with SSC for every salinity level, with a linear relationship and density values from 1023.5 to 1025.5 g L-1for SSC between 0 and 4.5 g L-1 (35 g L-1salinity), from 1009.5 g L-1to 1012.5 g L-1 (17.5 g/l salinity), and from 997 g L-1to 1000 g L-1 (0.3 g L-1salinity). Characteristic curves were obtained by using the density for 0 SSC at each salinity level as a reference value for each stretch along the estuary, with a resulting linear coefficient of around 0.6 for the low and medium range salinity values; however, this coefficient decreased to 0.4 for the high salinity samples. Additional work including temperature variation in the environmental range found for the Guadalquivir River estuary water is being carried out. These local curves will used in the hydrodynamic model of the estuary, and are applicable for other estuaries along the Andalusian coast with similar sediment patterns.

Carpintero García, M.; Jurado López, A.; Contreras Arribas, E.; Polo Gómez, M. J.

2012-04-01

78

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2013-01-01

79

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-11-30

80

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Corbett, D. R.

2010-01-01

 
 
 
 
81

Spatial Distribution of Copepods along the Salinity Gradient of Perai River Estuary, Penang, Malaysia  

Directory of Open Access Journals (Sweden)

Full Text Available Investigation on copepod communities in Perai river estuary was conducted from November 2005 to May 2006. Five stations were established for monthly sampling and were located from the river mouth to the upper reaches of the river. Copepod samples were collected from vertical tows using a standard zooplankton net. The Perai river estuary was slightly stratified and salinity decreases significantly from the mouth of the river towards the upper reaches of the river. A total of 28 species of copepods were recorded and comprised of 14 families, Paracalanidae, Oithonidae, Corycaeidae, Acartiidae, Calanidae, Centropagidae, Eucalanidae, Pontellidae, Pseudodiaptomidae, Tortanidae, Ectinosomatidae, Euterpinidae, Clausidiidae and Cyclopidae. A total of 10 species showed high positive affiliation towards salinity (R>0.60, Acartia spinicauda, Euterpina acutifrons, Microsetella norvegica, Oithona nana, Oithona simplex, Paracalanus crassirostris, Paracalanus elegans, Paracalanus parvus, Pseudodiaptomus sp. and Hemicyclops sp. The copepod species Pseudodiaptomus dauglishi were negatively affiliated towards salinity (R = -0.71. The copepod assemblages classified into two distinct groups according to salinity regimes, euryhaline-polyhaline group (25 marine affiliated species and oligohaline-mesohaline group (3 freshwater affiliated species.

S.M.N. Amin

2012-01-01

82

Spatial distribution of copepods along the salinity gradient of Perai river estuary, Penang, Malaysia.  

Science.gov (United States)

Investigation on copepod communities in Perai river estuary was conducted from November 2005 to May 2006. Five stations were established for monthly sampling and were located from the river mouth to the upper reaches of the river. Copepod samples were collected from vertical tows using a standard zooplankton net. The Perai river estuary was slightly stratified and salinity decreases significantly from the mouth of the river towards the upper reaches of the river. A total of 28 species of copepods were recorded and comprised of 14 families, Paracalanidae, Oithonidae, Corycaeidae, Acartiidae, Calanidae, Centropagidae, Eucalanidae, Pontellidae, Pseudodiaptomidae, Tortanidae, Ectinosomatidae, Euterpinidae, Clausidiidae and Cyclopidae. A total of 10 species showed high positive affiliation towards salinity (R > 0.60), Acartia spinicauda, Euterpina acutifrons, Microsetella norvegica, Oithona nana, Oithona simplex, Paracalanus crassirostris, Paracalanus elegans, Paracalanus parvus, Pseudodiaptomus sp. and Hemicyclops sp. The copepod species Pseudodiaptomus dauglishi were negatively affiliated towards salinity (R = -0.71). The copepod assemblages classified into two distinct groups according to salinity regimes, euryhaline-polyhaline group (25 marine affiliated species) and oligohaline-mesohaline group (3 freshwater affiliated species). PMID:24218935

Johan, I; Maznah, W O Wan; Mashhor, M; Abu Hena, M K; Amin, S M N

2012-07-01

83

Predicting water age distribution in the Pearl River Estuary using a three-dimensional model  

Science.gov (United States)

The age of water (AW) concept is applied to investigate the water exchange process in a large and density stratified estuary, namely the Pearl River Estuary. A three-dimensional AW model has been built based on an existing hydrodynamic and solute transport model. The model is used to determine the AW distributions inside the Pearl River Estuary under various hydrodynamic conditions. The predicted mean AW values during the dry and wet seasons are approximately 25 and 10 days, respectively. In general, lower AW values are observed in the upper layers near the water surface, while higher values are observed in the lower layers near the bed. The difference becomes more pronounced during the wet season when the river discharge is very large. The tidal influence is relatively small. The variation of tidal forcing impacts mainly on the AW fluctuation range, but it has limited impact on the tidally averaged AW value. Moreover, the AW vertical difference is enhanced during neap tides. A comparison between the predictions using barotropic and baroclinic models indicates that the density-induced circulation has a significant impact on the water exchange rate.

Ren, Yuheng; Lin, Binliang; Sun, Jian; Pan, Shunqi

2014-11-01

84

[Ecological risk assessment of organophosphorus pesticides in aquatic ecosystems of Pearl River Estuary].  

Science.gov (United States)

The risk quotient method and a probabilistic risk assessment method were applied for assessing aquatic ecological risk of nine organophosphorus pesticides, including thimet, dichlorovos, disulfoton, dimethoate, dimethyl parathion, chlorpyrifos, ethoprophos, sumithion and malathion on eight aquatic organisms in the Pearl River Estuary. Results using the risk quotient method revealed that the risk level of opossum shrimp was the highest among eight aquatic organisms of the Pearl River Estuary. The risk of water flea and midge was in medium level, followed by the rest six aquatic organisms, including diatom, oyster, carp, catfish and eel, which were in the low risk by the examined organophosphorus pesticides. It was found that thimet made the largest contribution to total aquatic ecological risk among nine organophosphorus pesticides to every organism. The results from probabilistic risk assessment showed that the total ecological risk in high water period was higher than that in low water period determined by the HC5 under the 95% confidence level. The largest contribution of thimet to total aquatic ecological risk subject to the HC5 in 50% confidence level was regarded as the toxic reference value. The probabilistic risk of a single contaminant showed that thimet and disulfoton were harmful to exceeded 10% organisms in the estuarine. The probabilistic risk of nine pesticides mixture in high water period was also higher than that in low water period, and both risks were greater than 5% which exceeded safety threshold for 95% organisms in the Pearl River Estuary. PMID:24881393

Guo, Qiang; Tian, Hui; Mao, Xiao-Xuan; Huang, Tao; Gao, Hong; Ma, Jian-Min; Wu, Jun-Nian

2014-03-01

85

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

Science.gov (United States)

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

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

2013-12-01

86

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

Science.gov (United States)

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

Bales, Jerad D.; Robbins, Jeanne C.

1999-01-01

87

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-08-01

88

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

International Nuclear Information System (INIS)

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

89

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

Energy Technology Data Exchange (ETDEWEB)

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

Khangaonkar, Tarang P.; Breithaupt, Stephen A.; Kristanovich, Felix C.

2006-01-01

90

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

Energy Technology Data Exchange (ETDEWEB)

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

Khangaonkar, Tarang P.; Breithaupt, Stephen A.; Kristanovich, Felix C.

2006-08-03

91

Hydrodynamics in the Yellow River Estuary via radium isotopes: Ecological perspectives  

Science.gov (United States)

We used radium isotopes as tracers to characterize coastal hydrodynamics and submarine groundwater discharge (SGD) in the Yellow River Estuary in order to assess the ecological effects in one of the most turbid estuaries in the world. Based on apparent water ages calculated by 224Ra/223Ra activity ratios, we found that the river plume flowed mainly southeast at a flow rate of 5-7 km d-1, while a small portion of the river plume was diverted northeast to the central Bohai Sea at a flow rate of less than 2 km d-1. We estimate that with this flow regime, nutrients would be consumed within about two weeks mostly by microplankton and nanoplankton near shore, and picoplankton further offshore to support an average primary production of 0.14 g C m-2 d-1. We then used a 226Ra mass balance model to quantify the SGD flux in the study area. The estimated SGD flux was 1.3×109 m3 d-1 with a range of 2.8×108-3.0×109 m3 d-1. Even the minimum SGD value was about 3 times higher than the Yellow River discharge at that time. The SGD input of dissolved nutrients was shown to be very important to the estuarine nutrient budget, at least 5 times higher than river input. Sediment regeneration of nutrients proved to be very small relative to the SGD flux in this region.

Xu, Bochao; Burnett, William; Dimova, Natasha; Diao, Shaobo; Mi, Tiezhu; Jiang, Xueyan; Yu, Zhigang

2013-09-01

92

Integrated Database Construction for Efficient Support of Yeongsan River Estuary Management System  

Science.gov (United States)

Yeongsan River is one of the four major rivers in South Korea, and it flows toward the Yellow Sea by passing through Damyang and Gwangju. In particular, the skewness of the main stream in Yeongsan River is relatively higher compared to other rivers. Accordingly, flood damage occurred frequently due to the flooding of sea water during tidal periods. Additionally, the environment of the estuary in Yeongsan River has been severely damaged due to indiscreet development and the inflow of various waste waters. Therefore, water quality improvement and management are crucial. For better water quality management, the government ministry is collecting various data from different fields to identify the water quality conditions. The necessity of collected data is being heightened in order to apply them into the estuary management system. However, in terms of the observed data, the observed field or items frequently modified according to social interests. Additionally, index is needed in order to search for massive amount of observation data. Due to this, the process of construction into database is relatively difficult. Therefore, in this study, these characteristics were considered for construction into the integrated DB.

Lee, G. H.; Kim, K. H.; Lee, S. J.

2014-02-01

93

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

Science.gov (United States)

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

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

2012-10-01

94

Data-collection program for Pamlico River Estuary model calibration and validation  

Science.gov (United States)

An investigation is being conducted to collect and interpret continuous records relating to the flow characteristics of the Pamlico River Estuary, North Carolina, and to calibrate and validate a numerical model of estuarine hydrodynamics. The study reach is 50 kilometers long and ranges in width from 330 meters at the upstream boundary to 6.4 kilometers at the downstream end. Water levels are recorded at 6 locations along the estuary; daily water-level range is typically greater at the head of the estuary than at the mouth, most likely due to upstream narrowing of the channel. Water-quality data are recorded at 14 locations. These data indicate that saline waters with low dissolved oxygen concentrations move upstream along the bottom of the estuary. Point velocities were monitored for 3 weeks at 7 locations; vertical profiles of horizontal velocity were made at the boundaries of the study reach for about 32 hours. Local tributary inflows and wind speed and direction are also being determined.

Bales, Jerad D.

1989-01-01

95

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

96

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

Science.gov (United States)

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

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

2013-01-01

97

Oil spill response planning on the Columbia river estuary  

International Nuclear Information System (INIS)

identification of pre-designed command posts. The local spill response cooperative and oil transportation industry are using the plan to coordinate the purchase of response equipment and the staging of this equipment at numerous locations along the river. The key to success is ensuring that all the groups responding to an event participate in the planning process together. This process has worked well and will serve as a model for response planning for other areas along the Columbia River and coastal areas of Washington and Oregon

98

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

Science.gov (United States)

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

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

2014-08-01

99

Sediment accumulation rate and radiological characterisation of the sediment of Palmones River estuary (southern of Spain)  

International Nuclear Information System (INIS)

Chemical analyses and radioecological methods were combined in order to estimate the sediment accumulation rate in the upper 20 cm depth of the Palmones River estuary. Organic matter, total carbon, C:N and 137Cs vertical profiles showed changes at 13 cm depth. These changes could be associated with the decrease in river input since 1987 when a dam situated in the upper part of the estuary started to store water. Using 1987 as reference to date the sediment, accumulation rate was 1.2 cm yr-1. As alternative method, two layer model of 210Pbxs vertical distribution showed a sedimentation rate of 0.7 cm yr-1 with a surface mixing layer of 7 cm thickness. The high ammonium, potassium and sodium content in pore water and the strong correlation between 137Cs activities and organic matter in dry sediment suggests that 137Cs (the only anthropogenic product detected) is mainly accumulated in the estuary associated with the particulate organic material from the catchment area

100

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

Science.gov (United States)

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

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

2014-05-01

 
 
 
 
101

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-02-12

102

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

International Nuclear Information System (INIS)

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

103

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

International Nuclear Information System (INIS)

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

104

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

Science.gov (United States)

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

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

2014-02-01

105

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

106

Grain size trend and hydrodynamic condition of tirumalairajan River estuary, east coast of India  

Science.gov (United States)

The estuary can be considered as environments characterized by high productivity and uncommensurable ecological value. However, marine ecosystems are also subjected to high human pressures that increase their vulnerability. The aim of this work is to analyze grain size trend of sediment due to the action of the main hydrodynamic condition. The spatial distribution patterns of sediments were monitored according to season. The grain-size trend of surficial sediments revealed a dominant sediment transport trend towards the eastern and south eastern part of study area. This study shows that there is an agreement among sediments path ways, hydrodynamic condition and the sediment spatial distribution in the estuarine environment. The agitation by waves is an important sorting mechanism in the study area. The findings are based on the grain size trend and also corroborated by short term observations of the estuarine sediment dynamics and transport during the monsoon, postmonsoon, summer and premonson seasons in Tirumalairajan River estuary.

Venkatramanan, S.; Chung, S. Y.; Ramkumar, T.; Park, N.

2014-07-01

107

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

2013-04-01

108

River flow and ammonium discharge determine spring phytoplankton blooms in an urbanized estuary  

Science.gov (United States)

Nutrient loadings to urbanized estuaries have increased over the past decades in response to population growth and upgrading to secondary sewage treatment. Evidence from the San Francisco Estuary (SFE) indicates that increased ammonium (NH4) loads have resulted in reduced primary production, a counter-intuitive finding; the NH4 paradox. Phytoplankton uptake of nitrate (NO3), the largest pool of dissolved inorganic nitrogen, is necessary for blooms to occur in SFE. The relatively small pool of ambient NH4, by itself insufficient to support a bloom, prevents access to NO3 and bloom development. This has contributed to the current rarity of spring phytoplankton blooms in the northern SFE (Suisun Bay), in spite of high inorganic nutrient concentrations, improved water transparency and seasonally low biomass of bivalve grazers. The lack of blooms has likely contributed to deleterious bottom-up impacts on estuarine fish. This bloom suppression may also occur in other estuaries that receive large amounts of anthropogenic NH4. In 2010 two rare diatom blooms were observed in spring in Suisun Bay (followed by increased abundances of copepods and pelagic fish), and like the prior bloom observed in 2000, chlorophyll accumulated after NH4 concentrations were decreased. In 2010, low NH4 concentrations were apparently due to a combination of reduced NH4 discharge from a wastewater treatment plant and increased river flow. To understand the interactions of river flow, NH4 discharge and bloom initiation, a conceptual model was constructed with three criteria; 1) NH4 loading must not exceed the capacity of the phytoplankton to assimilate the inflow of NH4, 2) the NH4 concentration must be ?4 ?mol L-1 to enable phytoplankton NO3 uptake, 3) the dilution rate of phytoplankton biomass set by river flow must not exceed the phytoplankton growth rate to avoid "washout". These criteria were determined for Suisun Bay; with sufficient irradiance and present day discharge of 15 tons NH4-N d-1at the upstream wastewater treatment plant (WTP). The loading criterion requires phytoplankton NH4 uptake to exceed 1.58 mmol m-2 d-1; the concentration criterion requires river flow >800 m3 s-1 at the WTP for sufficient NH4 dilution and the washout criterion requires river flow at Suisun Bay estuaries.

Dugdale, Richard; Wilkerson, Frances; Parker, Alexander E.; Marchi, Al; Taberski, Karen

2012-12-01

109

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

Science.gov (United States)

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

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

2014-04-01

110

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

International Nuclear Information System (INIS)

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

111

The low water-leaving radiances phenomena around the Yangtze River Estuary  

Science.gov (United States)

Based on the in-situ data and ocean color remote sensing data of SeaWiFS, we found there was a black water region with the normalized water-leaving radiances less than 0.5 mW/(cm2•?m•sr) at the visible light wavelength. Yangtze River Estuary locates in the East China Sea shelf with shallow water. Affected by the tide mixing and the runoff of the Yangtze River and Qiantang River, the turbidity is very high. Generally, the water-leaving radiance is high in the turbid water because of the large particle scattering. The reason of the occurrence of this black water was analyzed by the inherent optical properties and the ocean color components. The results showed that black water was caused by the relative low values of the suspended particle matter concentration and the back scattering ratio.

He, Xianqiang; Bai, Yan; Mao, Zhihua; Chen, Jianyu

2009-09-01

112

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

Science.gov (United States)

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

Pang, A. P.; Sun, T.

2013-12-01

113

Late Holocene evolution of the River Bensafrim estuary, Lagos (Portugal) - Gearchaeological remarks concerning geomorphological changings  

Science.gov (United States)

1. The site Lagos is a city in western Algarve situated on the right margin of the Ribeira de Bensafrim. Its dissymmetric estuary has two hills: one that supports the town of Lagos and the hill of Monte Molião, known for its archaeological site. During the Late Iron Age the establishment was constrained to the top of that small hill Molião After that period, in Roman Age, people moved their location to the right river margin, founding what was then known as Laccobriga - Lagos. 2. Objectives and methodology The main objective of this study is to understand the possible causes for the abandonment of Monte Molião and what were the reasons behind the foundation of the roman city of Laccobriga? The data used were the results from the sedimentary analysis of cores in the alluvial plain of the Bensafrim valley, radiocarbon data, together with the previous excavation results and structure analysis. 3. First results: (i) In the sedimentary record, the rate sand/clay as well as several statistical parameters and shells, show different energetic environments. (ii) Radiocarbon data shows that the estuary remained open until 2800 cal BP, when a spit developed at the mouth of the estuary and a salt marsh begin to develop behind the sand barrier. (iii) Remnants of fishing activities since the Iron Age found in the archaeological site highlight different strategies for the establishment around the estuary. Archeological data tells us that, the Iron Age fishing was mainly fluvial, while later shellfish remains point that in the roman period fishing activities were made in open sea. (iv) The analyzed roman structures in the archaeological site of Monte Molião, show a clear sign of a violent seismic destruction probably related to the known 63 b.C. earthquake. 4. Conclusions (i) It is proven that in the river Bensafrim the estuary changed from an open estuary before 2800 cal BP to a closed one. This could have forced the change of the fishing habits of the populations that depended on that river. We also believe that this could have contributed to the foundation of the roman city of Lagos on the right river margin. (ii) The 63 b.C. earthquake was strong enough to alter the establishment strategy. Archaeological record shows us that in Monte Molião there was a period with no occupation between the second half of the first century b.C. and the beginning of the first century a.D.. (iii) This study not only highlights the importance of the estuary in the occupation History of Lagos city but also shows that this kind of multi-disciplinary investigations are fundamental to understand human establishment processes. Acknowledgements This research was funded by the research project, PTDC/CTE-GIX/104035/2008 - FMI 5000: Environmental changes: Fluvio-marine interactions over the last 5000 yrs, from Portuguese Science and Technology Foundation (FCT-MCTES).

Gomes, J. A.; Ramos-Pereira, A.; Trindade, J.

2012-04-01

114

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

Science.gov (United States)

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

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

2014-05-01

115

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

Science.gov (United States)

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). PMID:20004500

Souza, Thaísa Abreu; Godoy, José Marcus; Godoy, Maria Luiza D P; Moreira, Isabel; Carvalho, Zenildo L; Salomão, Marcos Sarmet M B; Rezende, Carlos E

2010-07-01

116

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

117

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

International Nuclear Information System (INIS)

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

118

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.

119

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

Energy Technology Data Exchange (ETDEWEB)

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

Li Qusheng [Department of Environmental Engineering, JiNan University, Guangzhou 510632 (China)], E-mail: liqusheng@21cn.com; Wu Zhifeng [Guangdong Institute of Eco-environment and Soil Sciences, Guangzhou 510650 (China); Chu Bei; Zhang Na; Cai Shasha; Fang Jianhong [Department of Environmental Engineering, JiNan University, Guangzhou 510632 (China)

2007-09-15

120

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.

Joachim Maes

2012-06-01

 
 
 
 
121

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

122

Levels of Some Heavy Metals in Fishes From Pahang River Estuary, Pahang, Malaysia  

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Full Text Available In this study, the concentration of Pb, Cu and Zn were determined in muscle, gills and stomach of six fish species caught from Pahang river estuary. These metals concentration were measured by ICP-MS in order to assess the fish contamination with these metals. This study showed that all catfishes (Arius sp. presented the highest metals content. Tissue analysis revealed that the stomach accumulated the highest level of these metals. Based on the results, metal concentration in the edible part of the examined fish (muscle were in the safety permissible levels for human consumption.

B.Y. Kamaruzzaman

2010-01-01

123

Aquatic organism contamination by mercury residues in the Coatzacoalcos river estuary, Mexico  

International Nuclear Information System (INIS)

Mercury residues in the biotic and abiotic elements of the Coatzacoalcos river estuary have been determined over a two-year period. Main attention was given to aquatic species considered as indicators of the accumulation of Hg in the sediments. The highest levels were found in sediments and benthonic organisms. Mercury in human blood and hair was measured in two groups. The first group, which was chosen from occupationally exposed workers, showed higher values than the second group of non-occupationally exposed persons. The neutron activation analysis and atomic absorption analysis methods are discussed and results are presented. (author)

124

Roberts Bank: Ecological crucible of the Fraser River estuary  

Science.gov (United States)

Roberts Bank, part of the Fraser River delta system on Canada's Pacific coast, is a dynamic estuarine environment supporting important fisheries as well as internationally significant populations of migratory shorebirds. The 8000 ha bank environment comprises a complex of riparian boundaries, intertidal marshes, mud and sand flats, eelgrass meadows, macroalgae and biofilms. Anthropogenic developments (a ferry causeway in 1961 and a port causeway in 1969) have been responsible for changes in tidal flow patterns, tidal elevation, sediment transport and the net expansion of eelgrass beds. The goals of the present study were to (1) directly compare geotechnical properties spanning each side of the coalport causeway, and (2) enhance our understanding of the intercauseway ecosystem under a high-resolution sampling design. Sediment properties (grain size, porosity, organic content, and chlorophyll) and biological communities (eelgrass, macrofauna (0.5-1.0 mm) and meiofauna (0.063-0.5 mm)) were surveyed in 1997 at three stations outside the intercauseway area and three lateral transects spanning the intercauseway tidal flat at tidal heights representing three different habitats: biofilm, Zostera japonica, and Zostera marina. A fine-silt organic-rich porous deposit was observed on the shoreward north side of the coalport causeway relative to the south counterpart, suggesting that consolidation and erosion processes could likely not keep pace with the deposition of Fraser River silt. High chlorophyll levels were found in the protected shoreward northern border of the ferry causeway where fine sands dominate and higher water transparency exists, owing to the redirection of the silt-laden river plume by the coalport causeway. Principle Components Analysis revealed a positive relationship between these porous, organic-rich sediments and cumacean abundance in all regions where eelgrass was absent, including the north side of the coalport causeway. Further, a positive relationship was found between biofilm components (chlorophyll and silt), polydora, and harpacticoid copepod abundance, which, together with cumaceans, are food for Western Sandpipers, Calidris mauri. Finally, 52% of the intercauseway variation was explained by direct correlations between eelgrass attributes and fauna consisting of bivalves, caprellids, and harpacticoid copepods (root biomass, leaf area index), the latter being prey for juvenile salmon which depend on eelgrass beds as rearing habitat. These habitats are vulnerable to changes in tidal flow patterns, tidal elevation, sediment transport, and water clarity that could be caused by future port development and/or sea level rise in response to climate change.

Sutherland, Terri F.; Elner, Robert W.; O'Neill, Jennifer D.

2013-08-01

125

Detection of estuarine and tidal river hydromorphology using hyper-spectral and LiDAR data: Forth estuary, Scotland  

Science.gov (United States)

High spatial resolution hyper-spectral imagery (CASI) and light detection and ranging (LiDAR) imagery acquired for the tidal River Carron and Forth estuary, Scotland, were used in conjunction with field surveys to assess the feasibility of monitoring hydromorphology and human alterations with satellite and airborne remote sensing data. The study was undertaken in the context of the European Union Water Framework Directive (WFD) that requires member states to monitor hydromorphological elements as a component of the ecological status of rivers, estuaries and shorelines. Visual assessment and automated classifications of the imagery were compared with field survey data for an estuarine reach comprising saline waters, mudflats, a tidal reach of a tributary river and an urban/industrialised shoreline. The morphology of the estuary and inflowing tidal waters together with most artificial features of interest could be clearly seen in the CASI imagery at 1 m spatial resolution. Supervised classification of the imagery produced an overall accuracy value of 72%. Downgrading the imagery to simulate the spatial resolution of 4 m IKONOS satellite data surprisingly improved the accuracy to 74%. Simulation of 10 m SPOT imagery resulted in an image where many artificial features of interest such as roads, pipelines and jetties were rendered invisible. Adding LiDAR data as an additional data set aided manual and automated identification of features and visualisation of the hydromorphology of the rivers and estuaries in the study area. Shadows cast from tall objects were a feature of the winter imagery and reduced automated classification accuracy. Overall, the study demonstrates that high spatial resolution remotely sensed digital imagery has the potential to be a useful tool for panoptic mapping of the geomorphology and human impact on tidal rivers and estuaries. In the context of the WFD, remote sensing provides a potential way forward for monitoring the physical status of rivers and estuaries at the national scale. The possibilities and constraints, in light of the findings of this study, are discussed.

Gilvear, David; Tyler, Andrew; Davids, Corine

2004-11-01

126

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 sources, while the Pb probably came from non-point sources in the estuary

127

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

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

J.P. Walsh

2011-07-01

128

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.)

129

An Ecosystem-Based Restoration Plan with Emphasis on Salmonid Habitats in the Lower Columbia River and Estuary  

Energy Technology Data Exchange (ETDEWEB)

The Bonneville Power Administration (BPA), in coordination with the U. S. Army Corps of Engineers (COE) and NOAA Fisheries, originated this project (BPA Project No. 2002-076; Contract No. DE-AC06-76RL01830, Release No. 652-24). Their intent was to develop a useful habitat restoration plan for the lower Columbia River and estuary to help guide restoration efforts and fulfill Reasonable and Prudent Alternative Action 159 of the 2000 National Marine Fisheries Service Biological Opinion on operation of the Federal Columbia River Power System. This document focuses on salmon habitat, although its ecosystem-based approach necessarily affects other species as well. Salmon habitat restoration is best undertaken within the context of other biota and physical processes using an ecosystem perspective. The anticipated audience for the plan includes entities responsible for, interested in, or affected by habitat restoration in the lower Columbia River and estuary. Timeframes to apply this plan extend from the immediate (2003-2004) to the near-term (2005-2006) to the long-term (2007 and beyond). We anticipate and encourage that the plan be revised as new knowledge and experience are attained. A team comprised of the Columbia River Estuary Study Taskforce (CREST), the Lower Columbia River Estuary Partnership (Estuary Partnership), and Pacific Northwest National Laboratory (PNNL) wrote this document. The BPA and the COE, as the responsible Action Agencies, provided technical oversight. The Estuary Partnership's Science Work Group, NOAA Fisheries Habitat Conservation Division, Northwest Power Planning Council (NPPC) staff, and state and tribal fisheries management agencies reviewed drafts. The Independent Scientific Advisory Board of the NPPC reviewed and commented on the 90% draft. Revisions were incorporated into the final draft document subsequently released for public review. Extensive efforts were made to ensure a sound technical and policy basis and to solicit input from all interested parties.

Johnson, Gary E.; Thom, Ronald M.; Whiting, Allan H.; Sutherland, George B.; Berquam, Taunja J.; Ebberts, Blaine; Ricci, Nicole M.; Southard, John A.; Wilcox, Jessica D.

2003-10-14

130

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

Science.gov (United States)

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. PMID:23995020

Xu, Weihai; Yan, Wen; Li, Xiangdong; Zou, Yongde; Chen, Xiaoxiang; Huang, Weixia; Miao, Li; Zhang, Ruijie; Zhang, Gan; Zou, Shichun

2013-11-01

131

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

Science.gov (United States)

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

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

2010-01-01

132

A simple optical model to estimate suspended particulate matter in Yellow River Estuary.  

Science.gov (United States)

Distribution of the suspended particulate matter (SPM) concentration is a key issue for analyzing the deposition and erosion variety of the estuary and evaluating the material fluxes from river to sea. Satellite remote sensing is a useful tool to investigate the spatial variation of SPM concentration in estuarial zones. However, algorithm developments and validations of the SPM concentrations in Yellow River Estuary (YRE) have been seldom performed before and therefore our knowledge on the quality of retrieval of SPM concentration is poor. In this study, we developed a new simple optical model to estimate SPM concentration in YRE by specifying the optimal wavelength ratios (600-710 nm)/ (530-590 nm) based on observations of 5 cruises during 2004 and 2011. The simple optical model was attentively calibrated and the optimal band ratios were selected for application to multiple sensors, 678/551 for the Moderate Resolution Imaging Spectroradiometer (MODIS), 705/560 for the Medium Resolution Imaging Spectrometer (MERIS) and 680/555 for the Geostationary Ocean Color Imager (GOCI). With the simple optical model, the relative percentage difference and the mean absolute error were 35.4% and 15.6 gm(-3) respectively for MODIS, 42.2% and 16.3 gm(-3) for MERIS, and 34.2% and 14.7 gm(-3) for GOCI, based on an independent validation data set. Our results showed a good precision of estimation for SPM concentration using the new simple optical model, contrasting with the poor estimations derived from existing empirical models. Providing an available atmospheric correction scheme for satellite imagery, our simple model could be used for quantitative monitoring of SPM concentrations in YRE. PMID:24514305

Qiu, Zhongfeng

2013-11-18

133

Dissolved insecticides and polychlorinated biphenyls in the Pearl River Estuary and South China Sea.  

Science.gov (United States)

Persistent organic pollutants (POPs) such as organochlorine (OCl) insecticides and polychlorinated biphenyls (PCB), together with the new generation of organophosphorus (OP) insecticides, are of global concern, due to their widespread occurrence, persistence, bioaccumulation and hormone disruption potential. This paper represents an attempt to study the source and transportation of such pollutants in estuarine and coastal environments as an integrated ecosystem, by determining the levels of 18 OCl insecticides, 21 PCB congeners, and 17 OP insecticides in the Pearl River Estuary and South China Sea. The total concentrations varied from 126-1198 ng l(-1) for OCl insecticides, 33.38-1064 ng l(-1) for PCB congeners, and 4.44-6356 ng l(-1) for OP insecticides in the Pearl River Estuary. In comparison, their levels in the South China Sea were significantly lower, varying from 57.09-202 ng l(-1) for OCl insecticides, 21.72-144 ng l(-1) for PCBs, and 1.27-122 ng l(-1) for OP insecticides, respectively. The predominance of beta-HCH in HCHs, and DDE in DDTs in all water samples was clearly observed, suggesting beta-HCH and DDE's resistance to further degradation. The PCBs were dominated by those with 3-6 chlorines. The distribution characteristic of OP insecticides shows that five compounds (methamidophos, dimethoate, malathion, dichlorvos and omethoate) accounted for 56% and 72% of the total OP insecticide concentration. The relationship between pollutant concentrations and salinity in the estuary showed that they were all removed during the mixing process, therefore behaving non-conservatively. PMID:12509046

Zhang, Z; Dai, M; Hong, H; Zhou, J L; Yu, G

2002-12-01

134

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

Science.gov (United States)

The prevalence of juvenile salmonids (Oncorhynchus spp.) and marine forage fishes in the diet of Caspian terns (Hydroprogne caspia) nesting in the Columbia River estuary has been established, but the relationship between diet composition, foraging distribution, and productivity of these birds has received little attention. We used radio-telemetry and on-colony observations to relate changes in off-colony distribution to patterns of colony attendance, diet composition, and productivity of adult terns nesting on East Sand Island during two years of different river and prey conditions. Average distance from the East Sand Island colony (located in the marine zone of the estuary) was 38% (6.6 km) greater in 2000 compared to 2001, associated with lower availability of marine forage fish near East Sand Island and lower prevalence of marine prey in tern diets. Colony attendance was much lower (37.0% vs. 62.5% of daylight hours), average trip duration was 40% longer (38.9 min), and nesting success was much lower (0.57 young fledged pair-1 vs. 1.40 young fledged pair-1) in 2000 compared to 2001. Higher proportions of juvenile salmonids in the diet were associated with relatively high use of the freshwater zone of the estuary by radio-tagged terns, which occurred prior to chick-rearing and when out-migrating salmonid smolts were relatively abundant. Lower availability of marine prey in 2000 apparently limited Caspian tern nesting success by markedly reducing colony attendance and lengthening foraging trips by nesting terns, thereby increasing chick mortality rates from predation, exposure, and starvation. ?? 2007 Elsevier Ltd. All rights reserved.

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

2007-01-01

135

Nutrient transport from mangrove river to seagrass bed in the Fukido estuary, Japan  

Science.gov (United States)

Many subtropical estuaries have the interlinked ecosystem of mangroves, seagrass beds and coral reefs and have kept the delicate balance in nature. This study investigated the spatial and temporal variation of nutrients (NH4-N, NO3-N, PO4-P and SS) and water currents in discussing the material transport between mangrove river mouth to seagrass beds. TN and NH4-N in the mangrove river mouth were 2~5 times higher than in seagrass bed. PO4-P increased in seagrass beds at the low tide. Water current exhibited the strong seaward flow in the ebb tide and circulating flow in the northeast of the bay. These movements could have affected the material exchanges between the mangrove and adjacent seagrass beds.

terada, K.; Kutsumi, M.; Kanno, A.

2012-12-01

136

Three-dimensional simulation of flow, salinity, sediment, and radionuclide movements in the Hudson River estuary  

International Nuclear Information System (INIS)

The three-dimensional, finite difference model, FLESCOT simulates time-varying movements of flow, turbulent kinetic energy, salinity, water temperature, sediment, and contaminants in estuarine, coastal, and ocean waters. The model was applied to a 106-km (66-mi) reach of the Hudson River estuary in New York between Chelsea and the mouth of the river. It predicted the time-varying, three-dimensional distributions of tidal flow, salinity, three separate groups of sediments (i.e., sand, silt, and clay), and a radionuclide (137Cs) in both dissolved and particulate (those sorbed by sediments) forms for over 40 days. The model also calculated riverbed elevation changes caused by sediment deposition and bed erosion, bed sediment size distribution and armoring, and distributions of the particulate 137Cs sorbed by sand, silt, and clay in the bed

137

210Pb chronology and trace metal geochemistry in the intertidal sediment of Qinjiang River estuary, China  

Science.gov (United States)

Historical records of metal inputs were studied by using a sediment core collected from a sand-rich mudflat in the Qinjiang River estuary, China. 210Pb chronology was used to reconstruct the fluxes of Hg, Cu, Pb, Zn, Cd, Cr and As to the core site during the last 86 years. Based on the constant initial concentration model, the sedimentation rates are 1.18 cm year-1 in the top 30 cm sandy layer and 0.92 cm year-1 in the muddy bottom layer. To compensate for grain-size and mineralogy effects on metal concentrations, aluminum was used as the normalizing element. The enrichment factors ( EF) indicate that the natural inputs had prevailed up to the early 1980s. After this period, the intensity of human activities has resulted in continual increasing trend of metals towards the surface. Recent sediment samples from the Qinjiang River estuary are found moderately enriched by Cd ( EF>1.5) and slightly enriched by other metals ( EFCd may be due to the usage of fertilizers and pesticides in agricultural activities and the combustion of fossil fuels.

Xia, Peng; Meng, Xianwei; Feng, Aiping; Yin, Ping; Wang, Xiangqin; Zhang, Jun

2012-06-01

138

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

139

Nutrient exchange across the sediment-water interface in the Potomac River estuary  

Science.gov (United States)

The flux of ammonia, phosphate, silica and radon-222 from Potomac tidal river and estuary sediments is controlled by processes occurring at the sediment-water interface and within surficial sediment. Calculated diffusive fluxes range between 0·6 and 6·5 mmol m -2 day -1 for ammonia, 0·020 and 0·30 mmol m -2 day -1 for phosphate, and 1·3 and 3·8 mmol m -2 day -1 for silica. Measured in situ fluxes range between 1 and 21 mmol m -2 day -1 for ammonia, 0·1 and 2·0 mmol m -2 day -1 for phosphate, and 2 and 19 mmol m -2 day -1 for silica. The ratio of in situ fluxes to diffusive fluxes (flux enhancement) varied between 1·6 and 5·2 in the tidal river, between 2·0 and 20 in the transition zone, and from 1·3 to 5·1 in the lower estuary. The large flux enhancements from transition zone sediments are attributed to macrofaunal irrigation. Nutrient flux enhancements are correlated with radon flux enhancements, suggesting that fluxes may originate from a common region and that nutrients are regenerated within the upper 10-20 cm of the sediment column. The low fluxes of phosphate from tidal viver sediments reflect the control benthic sediment exerts on phosphorus through sorption by sedimentary iron oxyhydroxides. In the tidal river, benthic fluxes of ammonia and phosphate equal one-half and one-third of the nutrient input of the Blue Plains sewage treatment plant. In the tidal Potomac River, benthic sediment regeneration supplies a significant fraction of the nutrients utilized by primary producers in the water column during the summer months.

Callender, Edward; Hammond, Douglas E.

1982-10-01

140

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

Science.gov (United States)

SummaryAgriculture and ecosystems are increasingly competing for water. We propose an approach to assess the economic compensation standard required to release water from agricultural use to ecosystems while taking into account seasonal variability in river flow. First, we defined agricultural water shortage as the difference in water volume between agricultural demands and actual supply after maintaining environmental flows for ecosystems. Second, we developed a production loss model to establish the relationship between production losses and agricultural water shortages in view of seasonal variation in river discharge. Finally, we estimated the appropriate economic compensation for different irrigation stakeholders based on crop prices and production losses. A case study in the Yellow River Estuary, China, demonstrated that relatively stable economic compensation for irrigation processes can be defined based on the developed model, taking into account seasonal variations in river discharge and different levels of environmental flow. Annual economic compensation is not directly related to annual water shortage because of the temporal variability in river flow rate and environmental flow. Crops that have stable planting areas to guarantee food security should be selected as indicator crops in economic compensation assessments in the important grain production zone. Economic compensation may be implemented by creating funds to update water-saving measures in agricultural facilities.

Pang, Aiping; Sun, Tao; Yang, Zhifeng

2013-03-01

 
 
 
 
141

Autonomous Acoustic Receiver Deployment and Mooring Techniques for Use in Large Rivers and Estuaries  

Energy Technology Data Exchange (ETDEWEB)

Autonomous acoustic receivers are often deployed across a range of aquatic habitats to study aquatic species. The Juvenile Salmon Telemetry System autonomous acoustic receiver packages we deployed in the Columbia River and its estuary were comprised of an acoustic receiver, acoustic release, and mooring line sections and were deployed directly on the river bottom. Detection ranges and reception data from past optimization deployments helped determine acoustic receiver spacing in order to achieve acceptable detection probabilities for juvenile salmon survival estimation. Methods used in 2005, which resulted in a high equipment loss rate, were modified and used between 2006 and 2008 to increase crew safety and optimize receiver deployment and recovery operations in a large river system. By eliminating surface buoys and taglines (for anchor recovery), we experienced a recovery success rate greater than previous acoustic receiver deployment techniques used in the Columbia River and elsewhere. This autonomous acoustic receiver system has optimized deployment, recovery, and servicing efficiency to successfully detect acoustic-tagged salmonids in a variety of river environments.

Titzler, P. Scott; McMichael, Geoffrey A.; Carter, Jessica A.

2010-08-01

142

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

Science.gov (United States)

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

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

2011-02-01

143

Identifying the breeding areas of locusts in the Yellow River estuary using Landsat ETM+ imagery  

Science.gov (United States)

The Yellow River Estuary became an important plague region of locusts because of its special geographic location. Many years' survey data showed that the environment was the chief factor that influenced locust pest occurring. In the recent years, because the amount of water from the Yellow River and precipitation reduced and distributed asymmetrically, and soil salinization became serious much more, and many farmlands went out of cultivation, which improved the habitats for locusts, the plague of locusts happened frequently under condign climate. The field survey data from 1991 to 2000 showed that the plague of locust became more aggravating year after year. Therefore, it is important to monitor and control the plague of locusts. According to many years' investigation data analysis, got the condign habitat conditions for Locusta Migratoria Manilensis (Meyen) in the Yellow River Estuary. So the breeding areas of locusts monitoring with remote sensing imagery was to identify those regions according to the condign habitat conditions. Landsat ETM+ imagery (2000-05-02) data was chosen to identify the breeding areas of locusts in the Yellow River Estuary. Firstly classified Landsat TM imagery (2000-5-2) and extract reed lands and lawn lands and slightly salinized soils. Secondly made mask images through transforming these three raster classes into vector layers, then calculated a anti-atmospheric visible light vegetation index VARIg = (B2-B3)/(B2+B3-B1). According to field investigation data of vegetation fractional cover in 2000, got the relationship between vegetation fractional cover and VARIg values, 70% to 3.0, 50% to 2.3. As a result, the infrequent areas were where VARIg values were great than 3.0, and the moderate areas were where VARIg values were between 2.3 and 3.0, and frequent areas were where VARIg values were under 2.3. According to statistical analysis, the infrequent areas were percent 10 of the lands that have the condign soil salt content for locust growth, and the moderate areas of locusts were percent 40, and the frequent areas were percent 50. Because of the low spatial resolution of ETM+ imagery not enough to identify vegetation structure and components, and the quick spatial and temporal change of soil water content, this research only discussed vegetation fractional cover and soil salt content, and quantitative assessment of the identification results and a detailed research need more high spatial and temporal resolution remote sensing data and surface data supports in the future.

Liu, Qingsheng; Liu, Gaohuan; Yang, Yuzhen; Liu, Peng; Huang, Jianjie

2006-03-01

144

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

145

Acetylcholinesterase activity in copepods (Tigriopus brevicornis) from the Vilaine River estuary, France, as a biomarker of neurotoxic contaminants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

From April 1997 to June 1998, 14 measurements of acetylcholinesterase (AChE) enzymatic activity were performed with the copepod, Tigriopus brevicornis, collected at five stations in the Vilaine River estuary (South Brittany, France). Simultaneously, four chemical analyses of triazines and one analysis of total pesticides in water were undertaken. AChE activity levels in T brevicornis were compared to the levels measured at a reference site not exposed to effluents from Vilaine River. Results ...

Forget, Joelle; Beliaeff, Benoit; Bocquene, Gilles

2003-01-01

146

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

International Nuclear Information System (INIS)

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

147

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

International Nuclear Information System (INIS)

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

148

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

Science.gov (United States)

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

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

2014-02-01

149

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

Science.gov (United States)

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

Nwosu, Francis M.

2010-03-01

150

[Seasonal distribution of macrozoobenthos and its relations to environmental factors in Oujiang River estuary sea area].  

Science.gov (United States)

To evaluate the seasonal distribution of macrozoobenthos and its relations to environmental factors in Oujiang River estuary and adjacent waters, two cruise surveys were conducted in May 2006 (spring) and January 2007 (winter). A total of 65 species were collected, among which, polychaeta and mollusk were the dominant groups, Capitella capitata and Nassarius succinctus were the dominant species in spring and winter, respectively. The species number of macrozoobenthos was more in adjacent sea area than in estuary, and more in spring than in winter. The average biomass and density in the two seasons were 19.66 g x m(-2) and 131 ind x m(-2), respectively. There was a significant difference in the macrozoobenthos density between the two seasons, while less difference was observed in the biomass. The Shannon-Weiner index had significant difference between the two seasons, while Pielou eveness index, Margalef abundance index, and Simpsom dominance index had not. Water temperature and phytoplankton were the key factors affecting the macrozoobenthic taxa in spring, and water total organic carbon and dissolve oxygen were the key affecting factors in winter. PMID:19947218

Shou, Lu; Zeng, Jiang-Ning; Liao, Yi-Bo; Zhao, Yong-Qiang; Jiang, Zhi-Bing; Chen, Quan-Zhen; Gao, Ai-Gen; Yang, Jia-Xin

2009-08-01

151

Metals and acid volatile sulfide in sediment cores from the Sergipe River Estuary, Northeast, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Foram estudados o sulfeto volatilizado em meio ácido (AVS), os metais simultaneamente extraídos (SEM) e os metais em sítios de sedimentos do Estuário do Rio Sergipe, Brasil. As concentrações de AVS e SEM foram, em geral, maiores nos sedimentos dos sítios situados nas áreas que recebem maior aporte a [...] ntrópico devido à poluição urbana. Nesses sítios, o sulfeto parece ser a principal fase de ligação para os metais. No sítio do sedimento situado na área de maior influência marinha, as fases mais importantes de ligação para os metais parecem estar associadas à matéria orgânica e aos carbonatos. Os perfis de AVS permitiram identificar dois tipos de processos de sedimentação no estuário. Em todos os sítios, as relações SEM/AVS foram muito menores do que 1. Abstract in english Acid volatile sulfide (AVS), simultaneously extracted metals (SEM) and metals were studied in sediment cores from the Sergipe River Estuary, Brazil. AVS and SEM concentrations were, in general, higher in the core sediments from areas which receive a higher anthropic contribution due to urban polluti [...] on. In these cores, the sulfide seemed to be the main connection for the metals. In the core obtained from the area of major marine influence, the most important binding phases for the metals seemed to be associated with organic matter and carbonates. The AVS profiles allow identification of two types of sedimentation processes in the estuary. In all cores SEM/AVS ratios were much lower than 1.

José do Patrocínio H., Alves; Elisângela de Andrade, Passos; Carlos A. B., Garcia.

152

Diversity and distribution of nirK-harboring denitrifying bacteria in the water column in the Yellow River estuary.  

Science.gov (United States)

We investigated the diversity and community composition of denitrifying bacteria in surface water from the Yellow River estuary. Our results indicated that the diversity of the denitrifying community in freshwater based on the nirK gene was higher than that in seawater. Furthermore, phylogenetic analysis suggested that the bacteria community could be distributed into eight clusters (Clusters I to VIII). Redundancy analysis (RDA) revealed that community compositions were related to multiple environment factors, such as salinity and nitrate concentration. The results of the present study have provided a novel insight into the denitrifying community in water columns in estuaries. PMID:24621509

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

2014-01-01

153

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bridgewater, Nova Scotia, is located 20 km inland from the mouth of the LaHave River estuary on the Atlantic Coast of Canada. Bridgewater is at risk of flooding due to the combined effects of river runoff and a storm surge on top of high tide. Projected increases in sea-level and possible increased river runoff with climate change increase the risk of future flooding. A set of river and ocean water level simulations were carried out to determine the risk of flooding to Bridgewater today and i...

Tim Webster; Kevin McGuigan; Kate Collins; Candace MacDonald

2014-01-01

154

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

Scientific Electronic Library Online (English)

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

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

155

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

Scientific Electronic Library Online (English)

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

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

2139-21-01

156

Late Holocene (~ 2 ka) East Asian Monsoon variations inferred from river discharge and climate interrelationships in the Pearl River Estuary  

Science.gov (United States)

A sediment core from the Pearl River Estuary (PRE) was analyzed for grain size and organic geochemistry parameters (TOC and ?13Corg). The results showed that high mean grain-size value and increased sand content were correlated with the high TOC and negative ?13Corg. These results indicated high river runoff in the PRE area. Peak river discharge occurred during the periods 1900-1750, 1500-1600, 1400-1200, 1000-900 and 750-600 cal yr BP. The main changes recorded in grain-size distributions, TOC contents, and ?13Corg variations appear to be directly related to monsoon precipitation in the sediment source area. An increased East Asian summer monsoon rainfall (EASM) and/or an enhanced East Asian winter monsoon rainfall could result in the increasing of monsoon rainfall. Typhoon related rainfalls could act as positive influence on precipitation levels. The study of the correlations between the rainfall records and ENSO activities revealed a close relationship between the monsoon rainfall in the PRE and the tropical Pacific variations. The frequent occurrence of ENSO might result in the southern migration of the EASM rain belt and lead to more typhoon-derived rainfall in the PRD during the late Holocene.

Nan, Qingyun; Li, Tiegang; Chen, Jinxia; Nigma, Rajiv; Yu, Xinke; Xu, Zhaokai; Yang, Zaibao

2014-03-01

157

Effects of the sandbar breaching on hydrobiological parameters and zooplankton communities in the Senegal River Estuary (West Africa).  

Science.gov (United States)

This study describes the changes in hydrology, zooplankton communities and abundance in the Senegal River Estuary (SRE) before and after the breaching of the sandbar in October 2003. Samples were taken in 2003 at 3 stations located upstream (DI), in mid estuary (HY) and downstream (RM), and in 2005 at the same stations (RM becoming Old River Mouth: ORM), plus the new river mouth (NRM) resulting from the morphological evolution of the SRE. The study showed marked seasonal variations that affected the structure and distribution of zooplankton as well as major changes caused by the sandbar opening: increased marine influence throughout the whole SRE, changes in the horizontal gradients, arrival of euryhaline species and increase in meroplankton, in particular decapod larvae, transformation of the ORM area into a slackwater area with limited exchanges and the highest zooplankton numbers during high waters. PMID:24685450

Champalbert, Gisèle; Pagano, Marc; Arfi, Robert; Chevalier, Cristèle

2014-05-15

158

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

159

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

Science.gov (United States)

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

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

2014-06-01

160

Changes in archaeal abundance and community structure along a salinity gradient in the lower Pearl River and its estuary  

Science.gov (United States)

Archaea occur in a wide range of habitats and across broad environmental gradients. At the global scale, salinity is known to be a major driving force for archaeal species diversity. The goal of this study was to examine changes in abundance and diversity of archaeal community DNA and membrane lipids in the water column along a salinity gradient in the lower Pearl River and estuary in the context of water/gas chemistry (pH, nitrate/nitrite, ammonia, methane, carbon dioxide). The pH increased and nitrate/nitrite and ammonia decreased from the lower Pearl River to the estuary. Methane and carbon dioxide fluxes were high in the lower Pearl River and decreased sharply in the estuary and toward the open ocean. The archaeal lipid profile exhibited abrupt changes from dominance of GDGT-0 (a glycerol diakly glycerol tetraether with zero cyclopentyl ring, which is commonly present in methanogens) to dominance of crenarchaeol (a specific biomarker for Thaumarchaeota) with increasing salinity from zero in the lower Pearl River to >0.5% in the estuary. Quantification of the 16S rRNA gene abundance using qPCR revealed a switch from bacteria-dominance to archaea-dominance and the ratio of archaeal nirK/bacterial-amoA genes had a peak value in the estuary, suggesting enhanced activity of ammonia oxidation by archaea. Pyrosequencing of archaeal 16S rRNA, amoA and nirK genes exhibited systematic variation defined by habitat types. Our current studies employ rate measurements of carbon fixation, ammonia oxidation, and nitrate reduction using isotope labeling approaches, which will allow us to link changes in archaeal community structure and ecological function.

Zhang, C.; Wang, J.; Xie, W.; Wang, P.; Wei, Y.; Chen, S.; Zhou, X.

2013-12-01

 
 
 
 
161

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

International Nuclear Information System (INIS)

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

162

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

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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

163

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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 Curuç [...] á) 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). Abstract in english 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 Cu [...] ruçá 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).

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

2010-09-01

164

Delineation of the sources and sinks of heterogeneously distributed methane in the Pearl River and its estuary  

Science.gov (United States)

Methane in low temperature environments is mostly produced by methanogens. Sharp decrease in methane concentration has been observed from freshwater to marine water in coastal regions. The goal of this study was to delineate the sources and sinks of methane from the lower Pearl River (including, North, West, and East segments) and its estuary along a salinity gradient (0.0 % to 3.4%). Methane concentration in lower Pearl River ranged from 50.1 to 10578 nmol L-1 in the winter (average = 565.5 × 1464.9 nmol L-1) and from 38.4 to 974.1 nmol L-1 in the summer (average = 179.6 × 165.7 nmol L-1). In the estuary, however, methane concentration was 5-10 folds lower in winter and 3-8 folds lower in summer. The sea-to-air methane flux was also much higher in the fresh water (3159.6 umol/d.m2) than in the estuary (528.1 umol/d.m2). Abnormally high methane concentrations and methane flux in the East Pearl River appear to be associated with effluents of industrial or municipal wastes. DNA sequencing of the archaeal 16S rRNA gene indicates predominance of methanogens in the freshwater and their disappearance in the estuary. This is supported by the archaeal lipoid analysis, which showed the predominance of archaeol and caldarchaeol that characterize the methanogens. It is unknown, however, how aerobic (bacteria) and anerobic (archaea) methanotrophs may be involved in the oxidation of methane in the estuary environment where methane consumption is apparently occurring.

Wang, J.; Xie, W.; Wei, Y.; Zhang, C.

2013-12-01

165

Soil phosphorus forms and profile distributions in the tidal river network region in the Yellow River Delta estuary.  

Science.gov (United States)

Modified Hedley fraction method was used to study the forms and profile distribution in the tidal river network region subjected to rapid deposition and hydrologic disturbance in the Yellow River Delta (YRD) estuary, eastern China. The results showed that the total P (Pt) ranged from 612.1 to 657.8 mg kg(-1). Dilute HCl extractable inorganic P (Pi) was the predominant form in all profiles, both as absolute values and as a percentage of total extracted Pi. The NaOH extractable organic P (Po) was the predominant form of total extracted Po, while Bicarb-Pi and C.HCl-Po were the lowest fractions of total extracted Pi and Po in all the P forms. The Resin-P concentrations were high in the top soil layer and decreased with depth. The Pearson correlation matrix indicated that Resin-P, Bicarb-Pi, NaOH-Pi, and C.HCl-Pi were strongly positively correlated with salinity, TOC, Ca, Al, and Fe but negatively correlated with pH. The significant correlation of any studied form of organic P (Bicarb-Po, NaOH-Po, and C.HCl-Po) with geochemical properties were not observed in the study. Duncan multiple-range test indicated that the P forms and distribution heterogeneity in the profiles could be attributed to the influences of vegetation cover and hydrologic disturbance. PMID:24971393

Yu, Junbao; Qu, Fanzhu; Wu, Huifeng; Meng, Ling; Du, Siyao; Xie, Baohua

2014-01-01

166

Soil Phosphorus Forms and Profile Distributions in the Tidal River Network Region in the Yellow River Delta Estuary  

Science.gov (United States)

Modified Hedley fraction method was used to study the forms and profile distribution in the tidal river network region subjected to rapid deposition and hydrologic disturbance in the Yellow River Delta (YRD) estuary, eastern China. The results showed that the total P (Pt) ranged from 612.1 to 657.8?mg?kg?1. Dilute HCl extractable inorganic P (Pi) was the predominant form in all profiles, both as absolute values and as a percentage of total extracted Pi. The NaOH extractable organic P (Po) was the predominant form of total extracted Po, while Bicarb-Pi and C.HCl-Po were the lowest fractions of total extracted Pi and Po in all the P forms. The Resin-P concentrations were high in the top soil layer and decreased with depth. The Pearson correlation matrix indicated that Resin-P, Bicarb-Pi, NaOH-Pi, and C.HCl-Pi were strongly positively correlated with salinity, TOC, Ca, Al, and Fe but negatively correlated with pH. The significant correlation of any studied form of organic P (Bicarb-Po, NaOH-Po, and C.HCl-Po) with geochemical properties were not observed in the study. Duncan multiple-range test indicated that the P forms and distribution heterogeneity in the profiles could be attributed to the influences of vegetation cover and hydrologic disturbance. PMID:24971393

Yu, Junbao; Qu, Fanzhu; Wu, Huifeng; Meng, Ling; Du, Siyao; Xie, Baohua

2014-01-01

167

SOURCES AND TRANSFORMATIONS OF NITROGEN, CARBON, AND PHOSPHORUS IN THE POTOMAC RIVER ESTUARY  

Science.gov (United States)

Global transport of nitrogen (N), carbon (C), and phosphorus (P) in river ecosystems has been dramatically altered due to urbanization. We examined the capacity of a major tributary of the Chesapeake Bay, the Potomac River, to transform carbon, nitrogen, and phosphorus inputs from the world’s largest advanced wastewater treatment facility (Washington D.C. Water and Sewer Authority). Surface water and effluent samples were collected along longitudinal transects of the Potomac River seasonally and compared to long-term interannual records of carbon, nitrogen, and phosphorus. Water samples from seasonal longitudinal transects were analyzed for dissolved organic and inorganic nitrogen and phosphorus, total organic carbon, and particulate carbon, nitrogen, and phosphorus. The source and quality of organic matter was characterized using fluorescence spectroscopy, excitation emission matrices (EEMs), and PARAFAC modeling. Sources of nitrate were tracked using stable isotopes of nitrogen and oxygen. Along the river network stoichiometric ratios of C, N, and P were determined across sites and related to changes in flow conditions. Land use data and historical water chemistry data were also compared to assess the relative importance of non-point sources from land-use change versus point-sources of carbon, nitrogen, and phosphorus. Preliminary data from EEMs suggested that more humic-like organic matter was important above the wastewater treatment plant, but more protein-like organic matter was present below the treatment plant. Levels of nitrate and ammonia showed increases within the vicinity of the wastewater treatment outfall, but decreased rapidly downstream, potentially indicating nutrient uptake and/or denitrification. Phosphate levels decreased gradually along the river with a small increase near the wastewater treatment plant and a larger increase and decrease further downstream near the high salinity zone. Total organic carbon levels show a small decrease downstream. Ecological stoichiometric ratios along the river indicate increases in C/N ratios downstream, but no corresponding trend with C/P ratios. The N/P ratios increased directly below the treatment plant and then decreased gradually downstream. The C/N/P ratios remained level until the last two sampling stations within 20 miles of the Chesapeake Bay, where there is a large increase. Despite large inputs, there may be large variations in sources and ecological stoichiometry along rivers and estuaries, and knowledge of these transformations will be important in predicting changes in the amounts, forms, and stoichiometry of nutrient loads to coastal waters.

Pennino, M. J.; Kaushal, S.

2009-12-01

168

Analysis of HCHs and DDTs in a sediment core from the Old Yellow River Estuary, China.  

Science.gov (United States)

The present study analyzed the distribution of HCHs and DDTs in a sediment core from the Old Yellow River Estuary, China. The OCP levels were detected by Soxhlet extraction followed by gas chromatography (GC) using a mass-selective detector. Sediment age was analyzed for (210)Pb using an Ortec GWL HPGe gamma spectrometer. The results indicated that the concentrations of ?DDT in the sediment core were much lower than those of ?HCH. Compared with the other estuarine and coastal regions in Chinese rivers, HCHs levels in this area were higher or similar, while DDTs levels were lower. The compositional analysis indicated that ?-HCH and p, p'-DDD were the predominant species. The temporal trends indicated that levels of HCHs and DDTs were related with their historical usage, emission and soil residues. According to the analysis of the ratio, HCHs in this area was mainly due to the technical historical residue and recent lindane. DDTs was mainly due to historical residue. The biodegradation conditions for DDTs were anaerobic. The dicofol-type DDTs application occurred in this area. PMID:24268742

Da, Chunnian; Liu, Guijian; Yuan, Zijiao

2014-02-01

169

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

International Nuclear Information System (INIS)

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

170

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

171

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

172

Spatiotemporal variability of wet atmospheric nitrogen deposition to the Neuse River Estuary, North Carolina  

Energy Technology Data Exchange (ETDEWEB)

Excessive nitrogen (N) loading to N-sensitive waters such as the Neuse River estuary (North Carolina) has been shown to promote changes in microbial and algal community composition and function (harmful algal blooms), hypoxia and anoxia, and fish kills. Previous studies have estimated that wet atmospheric deposition of nitrogen (WAD-N), as deposition of dissolved inorganic nitrogen (DIN: NO{sub 3}{sup -} NH{sub 3}/NH{sub 4}{sup +}) and dissolved organic nitrogen, may contribute at least 15% of the total externally supplied or 'new' N flux to the coastal waters of North Carolina. In a 3-yr study from June 1996 to June 1999, the weekly wet deposition of inorganic and organic N was counted at eleven sites on a northwest-southeast transect in the watershed. The annual mean total (wet DIN + wet organics) WAD-N flux for (15,026 Mg N/yr). Seasonally the spring (March-May) and summer (June - August) months contain the highest total weekly N depositions; this pattern appears to be driven by N concentration in precipitation. There is also spatial variability in WAD-N deposition; in general, the upper portion of the watershed receives the lowest annual deposition and the middle portion of the watershed receives the highest deposition. Based on a range of watershed N retention and in-stream riverine processing values, it was estimated that this flux contributes approximately 24% of the total 'new' N flux to the estuary. 61 refs., 4 figs., 4 tabs.

Whitall, D.R.; Paerl, H.W. [University of North Carolina, Morehad City, NC (USA). Inst. of Marine Sciences

2001-10-01

173

Dynamics of heterotrophic dinoflagellates off the Pearl River Estuary, northern South China Sea  

Science.gov (United States)

Variations in abundance, biomass, vertical profile and cell size of heterotrophic dinoflagellates (HDFs) between summer and winter and its controlling factors were studied in the northern South China Sea (SCS). It was found that HDF abundance and carbon biomass were 4-102 × 10 3 cells L -1 and 0.34-12.3 mg C L -1 in winter (February 2004), respectively, while they were 2-142 × 10 3 cells L -1 and 0.22-31.4 ?g C L -1 in summer (July, 2004), respectively, in the northern SCS. HDF abundance and carbon biomass decreased from the estuary to inshore and then offshore. Vertical profiles of HDF abundance were heterogeneous, which accorded well with that of chlorophyll a (Chl. a). Higher abundance of HDFs was often observed at a depth of 30-70 m offshore waters, matching well with the Chl. a maximum, while it showed high abundance at the surface in some coastal and estuary stations. Small HDFs (?20 ?m) dominated the assemblage in term of abundance accounting for more than 90%. However, large HDFs (>20 ?m) generally contributed equally in terms of carbon biomass, accounting for 47% on average. HDFs showed different variation patterns for the different study regions; in the estuarine and continental shelf regions, abundance and biomass values were higher in summer than those in winter, while it was the reverse pattern for the slope waters. Hydrological factors (e.g. water mass, river outflow, monsoon and eddies) associated with biological factors, especially the size-fractionated Chl. a, seemed to play an important role in regulating HDF distribution and variations in the northern South China Sea.

Lan, Wenlu; Huang, Bangqin; Dai, Minhan; Ning, Xiuren; Huang, Lingfeng; Hong, Huasheng

2009-11-01

174

Herbivorous and microbial grazing pathways of metazooplankton in the Senegal River Estuary (West Africa)  

Science.gov (United States)

The trophic relationships between metazooplankton and natural particles were studied in May 2002 in the Senegal River Estuary (16°N, 16°W) in low water conditions (dry season). Environmental factors, micro-organism and metazooplankton were analyzed through sampling at a fixed station. Gut fluorescence measurements of and field experiments on zooplankton metabolism were also performed. Chlorophyll a concentrations ranged from 6.5 to 10.2 ?g l -1. The phytoplankton was dominated by picoplanktonic cells (83-94% of total numbers). The particulate organic carbon (1.2-2.7 mg l -1) originated for a large amount from organic detritus (20-70%). The zooplankton biomass was dominated by Cirripedia larvae and calanoid copepods ( Acartia clausi, Temora stylifera and Paracalanus spp.). These taxa showed diel vertical migrations and maximal gut fluorescence at night, independently of tidal effects. Metabolic budgets show that their daily ingestion rates on phytoplankton (27-55% of body carbon weight) were insufficient to balance their respiration needs (40-51% of body carbon) and suggest that a selective feeding upon micro-heterotrophs (Heterotrophic NanoFlagellates, HNF) and/or detritus would be necessary to complete their energetic needs. The daily grazing pressure of metazooplankton represented only 5% of the in situ chlorophyll a and 14% of the primary production, but this pressure was mainly orientated towards nanophytoplankton. The daily recycling of nutrients by the metazooplankton excretion was rather high (83 and 46% of the in situ NH 4-N and PO 4-P concentrations, respectively). Therefore, the impact of metazooplankton on phytoplankton through top-down (grazing) and bottom-up (nutrient recycling) processes seemed substantial in this tropical estuary.

Pagano, Marc; Champalbert, Gisèle; Aka, Maryse; Kouassi, Ernest; Arfi, Robert; Got, Patrice; Troussellier, Marc; N'Dour, E. H.; Corbin, Daniel; Bouvy, Marc

2006-04-01

175

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

Directory of Open Access Journals (Sweden)

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

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

D. R. Corbett

2010-04-01

176

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

Directory of Open Access Journals (Sweden)

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

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

D. R. Corbett

2010-10-01

177

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-09-01

178

Influence of bathymetry evolution on position of tidal shear front and hydrodynamic characteristics around the Yellow River estuary  

Science.gov (United States)

A three dimensional numerical model based on the hydrodynamic module of finite-volume coastal ocean (FVCOM) was established for the Yellow River estuary. The model has been calibrated by observed data and proved to be suitable to reflect the hydrodynamic force in the research area. We employed the model to simulate the tidal shear front off the Yellow River estuary and analyzed the formation, spread and duration of two different types of shear front. To examine the effect of bathymetry evolution on the position of tidal shear front, subaqueous bathymetry of the Yellow River estuary was changed according to the changing patterns obtained from the past few years. Tidal shear front was modeled on both the original and the changed bathymetry. The results show that the position of shear front moved from a shallow to a deep area due to the deposition of bathymetry. The influence of bathymetry evolution on hydrodynamic characteristics including the distribution of salinity and the movement of particles was studied. We found the dispersion areas of low salinity became larger after changing bathymetry and the particles on the surface, middle and bottom layer are able to move further both north and west of Laizhou Bay on the changed bathymetry.

Lu, Yucen; Shen, Yongming

2012-12-01

179

Suspended sediment transport in the Deepwater Navigation Channel, Yangtze River Estuary, China, in the dry season 2009: 2. Numerical simulations  

Science.gov (United States)

A three-dimensional wave-current-sediment coupled numerical model with wetting and drying process is developed to understand hydrodynamics and sediment transport dynamics in the Deepwater Navigation Channel (DNC), the North Passage of the Yangtze River Estuary (YRE), China. The model results are in good agreement with observed data, and statistics show good model skill scores and correlation coefficients. The model well reproduces the spring-neap variation between a well-mixed estuary and a highly stratified estuary. Model results indicate that the estuarine gravitational circulation plays the most important role in the estuarine turbidity maximum (ETM) formation in the DNC. The upstream nonlocal sediment intrusion through the spillover mechanism is a major source of sediment trapping in the North Passage after the morphological changes. Numerical studies are conducted to show scenarios in the YRE under the effects of different forcings (river discharges, waves, and winds). Between these study cases, surface-wave-breaking relieves the sediment trapping and bottom-wave-current-interaction aggravates the bed erosion and elevates the SSC in the ETM; the former and the latter have the least and largest influence on the suspended sediment transport in the DNC. The wind effects have a greater influence on sediment trapping than the river discharges, and the steady northwesterly wind condition favors the siltation in the DNC most. The significance of density-driven turbidity current is also assessed, which can enhance the saline-water intrusion and suppress the turbulent mixing in the bottom boundary layer.

Song, Dehai; Wang, Xiao Hua

2013-10-01

180

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

Science.gov (United States)

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

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

2013-08-01

 
 
 
 
181

Remotely sensed variability of the suspended sediment concentration and its response to decreased river discharge in the Yangtze estuary and adjacent coast  

Science.gov (United States)

Satellite observation is an excellent tool for exploring the variability of the suspended sediment concentration (SSC) of turbid estuarine and coastal waters. We used a recently developed semi-empirical radiative transfer model combined with a multi-wavelength switching algorithm for the SSC retrieval from MEdium Resolution Imaging Spectrometer (MERIS) satellite data. This method can successfully retrieve SSC from satellite data in turbid estuarine and coastal waters with a wide range of sediment concentrations (20-2500 mg l-1) and is robust for quantifying realistic patterns of the surface sediment dynamics. The seasonal and annual variability of the MERIS-derived SSC from 2003 to 2010 were analysed in this work. Five regions-of-interest (ROIs) in the Yangtze estuary and coast are included in the analysis: the upper estuary, the lower estuary, the outer estuary, the Hangzhou Bay and the Qidong shore. The results reveal that the SSC of the upper estuary has significant seasonal and annual variations in response to seasonal cycling and annual fluctuation of the river discharge. A long-term continuing decrease of river discharge may cause an overall decline of the SSC in the entire estuary and adjacent areas. The existence of horizontal exchanges of the sediments between the Yangtze estuary and the Jiangsu coast implies that the decreased fluvial sediment loads of the estuary may partially be compensated by supplementing contributions from other origins.

Shen, Fang; Zhou, Yunxuan; Li, Jiufa; He, Qing; Verhoef, Wouter

2013-10-01

182

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

Science.gov (United States)

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

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

2012-06-01

183

Aquatic ecology of the Elwha River estuary prior to dam removal: Chapter 7 in Coastal habitats of the Elwha River, Washington--biological and physical patterns and processes prior to dam removal  

Science.gov (United States)

The removal of two long-standing dams on the Elwha River in Washington State will initiate a suite of biological and physical changes to the estuary at the river mouth. Estuaries represent a transition between freshwater and saltwater, have unique assemblages of plants and animals, and are a critical habitat for some salmon species as they migrate to the ocean. This chapter summarizes a number of studies in the Elwha River estuary, and focuses on physical and biological aspects of the ecosystem that are expected to change following dam removal. Included are data sets that summarize (1) water chemistry samples collected over a 16 month period; (2) beach seining activities targeted toward describing the fish assemblage of the estuary and migratory patterns of juvenile salmon; (3) descriptions of the aquatic and terrestrial invertebrate communities in the estuary, which represent an important food source for juvenile fish and are important water quality indicators; and (4) the diet and growth patterns of juvenile Chinook salmon in the lower Elwha River and estuary. These data represent baseline conditions of the ecosystem after nearly a century of changes due to the dams and will be useful in monitoring the changes to the river and estuary following dam removal.

Duda, Jeffrey J.; Beirne, Matthew M.; Larsen, Kimberly; Barry, Dwight; Stenberg, Karl; McHenry, Michael L.

2011-01-01

184

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

Science.gov (United States)

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

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

2011-12-01

185

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

International Nuclear Information System (INIS)

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

186

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-04-15

187

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

Science.gov (United States)

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

Chen, XinJian

2012-06-01

188

Myrionecta Rubra Population Genetic Diversity and Its Cryptophyte Chloroplast Specificity in Recurrent Red Tides in the Columbia River Estuary  

Energy Technology Data Exchange (ETDEWEB)

For at least a decade, annually recurring blooms of the photosynthetic ciliate, Myrionecta rubra have been observed in the Columbia River estuary in late summer. In an effort to understand the dynamics of these blooms, we investigated the genetic variability of M. rubra and its cryptophyte plastids within three large estuarine blooms formed in consecutive years (2007-2009), and conducted a broader spatial survey along the coasts of Oregon/Washington. Analysis of the ‘18S-28S’ sequences specific for Mesodiniidae uncovered at least 7 variants of M. rubra within the Columbia River coastal margin in spring and summer, but only one of these M. rubra variants was implicated in estuary bloom formation. Using a multigene approach, we show that the bloom-forming variant of M. rubra appears to harbor the same cryptophyte chloroplast in recurring blooms. Analyses of chloroplast 16S rRNA, cryptophyte RuBisCO and Photosystem II D2 genes together suggest that the plastid is derived from Teleaulax amphioxeia. Free-living cells of this species and of other cryptophytes were practically absent from the bloom patches in the estuary main channels based on 18S rDNA sequence analyses. The respectively low and high proportions of T. amphioxeia nuclei and chloroplasts signals found in the M. rubra bloom of the Columbia River estuary in successive years supports the notion of a transient association between T. amphioxeia and the bloom-forming M. rubra variant, with loss of cryptophyte nuclei. The genetic variability of M. rubra uncovered here is relevant to the controversy in the literature regarding the cryptophyte /M. rubra association.

Herfort, Lydie; Peterson, Tawnya D.; McCue, Lee Ann; Crump, Byron C.; Prahl, Fredrick G.; Baptista, Antonio M.; Campbell, Victoria; Warnick, Rachel; Selby, Mikaela; Roegner, G. Curtis; Zuber, Peter A.

2011-01-04

189

On the role of wind and tide in generating variability of Pearl River plume during summer in a coupled wide estuary and shelf system  

Science.gov (United States)

A numerical simulation of the buoyant river plume over the Pearl River Estuary (PRE) and adjacent shelf during a typical upwelling favorable wind period of the summer monsoon is utilized to explore the responses of the plume to wind and tide forcing. The model is forced with time-dependent river discharge, wind and tide, and it shows reasonable ability to capture the basic structure and responses of the plume. Additional numerical experiments that are forced without either wind or tide are used to evaluate the relative importance of wind and tide in generating plume variability. Results show that the vertical structure of the plume and the strength of the stratification in the estuary are determined by the combination of the buoyancy forcing associated with river discharge and tidal forcing, and vary with the advection process, while the horizontal shape and spreading of the plume over the shelf are highly influenced by the wind-driven coastal current, and are more susceptible to the change of vertical mixing. Mechanical energy analysis in each dynamical region (upper, middle, lower estuary, and shelf) reveals that this is because the system mainly gains energy from tide (wind) in the estuary (shelf), and loses energy to the bottom friction (internal-shear mixing) in the estuary (shelf). The largest forcing and dissipation terms in the middle PRE, and at the entrances of smaller estuaries such as Huang Mao Hai, are due to tidal forcing, which enables the middle PRE to serve dynamically as the entrance of an estuary, where the transition of the river plume into coastal buoyancy current usually takes place. In addition, the mixing efficiency increases from upper PRE to the shelf and from strong to weak mixing period, thus the plume in the well-mixed upper estuary is not as sensitive to the changes of wind and tide as that over the highly stratified shelf.

Zu, Tingting; Wang, Dongxiao; Gan, Jianping; Guan, Weibing

2014-08-01

190

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

191

Abundance exchange models of fish assemblages along the Hudson River Estuary Gradient, New York.  

Science.gov (United States)

The spatially explicit abundance exchange model (AEM) was built for four fish species: winter flounder (Pseudopleuronectes americanus), Atlantic silverside (Menidia menidia), eastern silvery minnow (Hybognathus regius), and striped bass (Morone saxatilis) along the Hudson River estuary gradient, New York. The fish and habitat data during 1974-1997 were used to develop and calibrate the AEM; and the fish data during 1998-2001 was used to validate the model. Preference indexes of fish species for dissolved oxygen, salinity, water temperature, and bottom substrates along the gradient were estimated; and these were used to compute habitat preference (HP) of the associated fish species. The species HP was a key variable in the AEM to quantify abundance and distribution patterns of the associated species along the gradient. The AEM could efficiently predict abundance and distribution patterns of all modeled species except striped bass. The model ability for predicting a local distribution range of a fish species with broad tolerance on changing environment like striped bass should be improved. PMID:19092189

Singkran, Nuanchan; Bain, Mark B

2008-01-01

192

[Distribution of polybrominated diphenyl ethers in aquatic species from the Pearl River Estuary].  

Science.gov (United States)

Polybrominated diphenyl ethers (PBDEs) were detected in biota samples collected from the Pearl River Estuary. The concentrations of sigma10 PBDEs (BDE28, 47, 66, 100, 99, 85, 154, 153, 138, 183) in fish species (including Platycephalus indicus, Pseudosiaena crocea , Pampus argenteus, Cynoglossus robustus, and Harpodon nehereus), shrimps (including Metapenaeus ensis and Metapenaeus affinis) and Squilla oratoria were from 37.8 ng x g(-1) to 407.1 ng x g(-1) (normalized to lipid), from 49.0 ng x g(-1) to 239.1 ng x g(-1) and from 142 ng x g(-1) to 444.5 ng x g(-1), respectively. BDE47 was the dominant congener in all biota samples, with a contribution to sigma10 PBDEs ranging from 53.7% to 66.9%. Differences in concentrations of PBDEs and PBDE patterns in different species may be related to the different feeding habit, living environment and uptaking or elimination rate. High ratios of concentrations of PBDEs in liver /muscle in fish species indicated that PBDEs tended to accumulate more in liver than in muscle. PMID:17117624

Xiang, Cai-hong; Luo, Xiao-jun; Yu, Mei; Meng, Xiang-zhou; Mai, Bi-xian; Zeng, Eddy

2006-09-01

193

Influence of climate factors on Vibrio cholerae dynamics in the Pearl River estuary, South China.  

Science.gov (United States)

Current research has seldom focused on the quantitative relationships between Vibrio cholerae (V. cholerae) and climate factors owing to the complexities and high cost of field observation in the aquatic environment. This study has focused on the relationships between V. cholerae and climate factors based on linear regression method and data partition method. Data gathered from 2008 to 2009 in the Pearl River estuary, South China, were adopted. Positive rate of V. cholerae was correlated closely with monthly climate factors of water temperature and air temperature, respectively in 2009. Quarterly data analysis from 2008 to 2009 showed that there existed seasonal characteristic for V. cholerae. Positive rate of V. cholerae was correlated positively with quarterly climate factors of land surface temperature, pH, water temperature, air temperature and rainfall, respectively and negatively with quarterly air pressure. Partition data analysis in 2009 showed that there existed geography region characteristic for V. cholerae. V. cholerae dynamics was closely correlated to climate factors in the downstream area. However, it was more greatly affected by human geography factors in the urban area. Positive annual rate of V. cholerae was higher in the downstream area than in the urban area both in 2008 and 2009. At last, a cellular automaton model was used to simulate V. cholerae diffusion downstream, and the distribution of V. cholerae obtained from this model was similar to that obtained from the field observations. PMID:24442820

Yue, Yujuan; Gong, Jianhua; Wang, Duochun; Kan, Biao; Li, Baisheng; Ke, Changwen

2014-06-01

194

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

Science.gov (United States)

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

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

2013-11-01

195

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

Science.gov (United States)

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

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

2014-07-01

196

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

197

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

Science.gov (United States)

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

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

2014-12-01

198

Over one hundred years of trace metal fluxes in the sediments of the Pearl River Estuary, South China  

International Nuclear Information System (INIS)

The rapid economic development in the Pearl River Delta (PRD) region in South China in the last three decades has had a significant impact on the local environment. Estuarine sediment is a major sink for contaminants and nutrients in the surrounding ecosystem. The accumulation of trace metals in sediments may cause serious environmental problems in the aquatic system. Thirty sediment cores were collected in the Pearl River Estuary (PRE) in 2000 for a study on trace metal pollution in this region. Heavy metal concentrations and Pb isotopic compositions in the four 210Pb-dated sediment cores were determined to assess the fluxes in metal deposits over the last one hundred years. The concentrations of Cu, Pb and Zn in the surface sediment layers were generally elevated when compared with the sub-surface layers. There has been a significant increase in inputs of Cu, Pb and Zn in the PRE since the 1970s. The results also showed that different sampling locations in the estuary received slightly different types of inputs. Pb isotopic composition data indicated that the increased Pb in the recent sediments was of anthropogenic origin. The results of trace metal influxes showed that about 30% of total Pb and 15% of total Zn in the sediments in the 1990s were from anthropogenic sources. The combination of trace metal analysis, Pb isotopic composition and 210Pb dating in an estuary can provide vital information on the long-term accumulation of metals in sediments

199

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

Scientific Electronic Library Online (English)

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

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

200

Pore water nutrient characteristics and the fluxes across the sediment in the Pearl River estuary and adjacent waters, China  

Science.gov (United States)

Spatio-temporal distribution of pore water nutrients and the fluxes at the sediment-water interface (SWI) were investigated to probe into the geochemical behavior of nutrients associated with early diagenesis of organic matter (OM), and to study the accumulation and transformation processes of nutrients at the SWI, as well as to discuss the impact of riverine inputs on nutrients in the Pearl River estuary (PRE) and adjacent offshore areas. Nutrient concentrations decreased from the upper to the lower reaches of the estuary, suggesting that there was a high input of anthropogenic nutrients and the estuary was acting as a nutrient sink. Dissolved inorganic nitrogen (DIN: the sum of NH4-N, NO3-N and NO2-N) concentrations in the water column and the pore water were higher in the estuary than at offshore areas due to the riverine discharge and the high accumulation rate in the estuary. NO3-N concentration was the highest of the three forms of DIN in the overlying water and showed a sharp decrease from the surficial sediment with increasing sediment depth, indicating that there was strong denitrification at the SWI. NH4-N, mainly deriving from the anaerobic degradation of OM, was the main form of DIN in the pore water and increased with depth. Negative NO3-N fluxes (into the sediment) and positive NH4-N fluxes (from the sediment) were commonly observed from incubation experiments, indicating the denitrification occurred at the SWI. DIN flux suggested that the sediment was a sink of DIN in spring, however, the sediment was the source of DIN in summer and winter. Nutrients dominantly diffused out of the sediment, suggesting that the sediment was the source of nutrients in spring at adjacent offshore areas. The fluxes directed that PO4-P mainly diffused into the sediment while SiO4-Si mainly diffused out of the sediment.

Zhang, Ling; Wang, Lu; Yin, Kedong; Lü, Ying; Zhang, Derong; Yang, Yongqiang; Huang, Xiaoping

2013-11-01

 
 
 
 
201

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

Directory of Open Access Journals (Sweden)

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

T.K. Gyedu-Ababio

2011-07-01

202

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

International Nuclear Information System (INIS)

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

203

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

Science.gov (United States)

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

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

2014-06-15

204

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

Directory of Open Access Journals (Sweden)

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

Sohair A. Mostafa

2003-01-01

205

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

Science.gov (United States)

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

Read, G. H. L.

1985-09-01

206

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

Scientific Electronic Library Online (English)

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

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

1719-17-01

207

Status of the population structure of the mangrove crab Ucides cordatus (Decapoda: Ocypodidae) on the Piraquê-açu River estuary, Espírito Santo, Brazil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The land crab Ucides cordatus is a keystone species of neotropical mangrove forests and an important resource of the artisanal fisheries. The spatial and temporal distribution of U. cordatus in the mangrove area of the Piraquê-açu river estuary was determined following a longitudinal estuarine salinity gradient (lower, middle, upper estuary) and along the vertical intertidal gradient. The numbers of open and closed burrows were counted monthly on fixed transects, the inhabiting crabs were c...

Rita de Cássia Conti; Rosebel Cunha Nalesso

2010-01-01

208

Historical trends of hypoxia in Changjiang River estuary: Applications of chemical biomarkers and microfossils  

Science.gov (United States)

Over the past two decades China has become the largest global consumer of fertilizers, which has enhanced river nutrient fluxes and caused eutrophication and hypoxia in the Yangtze (Changjiang) large river delta-front estuary (LDE). In this study, we utilized plant pigments, lignin-phenols, stable isotopes (? 13C and ? 15N) and foraminiferal microfossils in 210Pb dated cores to examine the history of hypoxia in the Changjiang LDE. Two sediment cores were collected onboard R/V Dong Fang Hong 2 using a stainless-steel box-corer; one at a water depth of 24.7 m on Jun. 15, 2006 and the other at 52 m on Nov. 20, 2007, both in the hypoxic region off the Changjiang LDE. There has been a significant increase in the abundance of plant pigments after 1979 that are indicators of enhanced diatom and cyanobacterial abundance, which agrees with post-1980 record of increasing nutrient loads in the Changjiang River. The increased inputs of terrestrially derived materials to the LDE are largely woody plant sources and most likely due to deforestation that began in the early 1950s. However, post-1960 lignin data did not reflect enhanced loading of woody materials despite continued deforestation possibly due to increased trapping from greater dam construction, a reduction of deforestation in the drainage basin since the last 1990s, and soil conservation practices. The lack of linkages between bulk indices (stable isotopes, % OC, molar C/N ratios) and microfossil/chemical biomarkers may reflect relative differences in the amount of carbon tracked by these different proxies. Although NO 3- is likely responsible for most of the changes in phytoplankton production (post 1970s), historical changes in N loading from the watershed and hypoxia on the LDE shelf may not be as well linked in East China Sea (ECS) sediments due to possible denitrification/ammonification processes; finally, increases in low-oxygen tolerant foraminiferal microfossils indicate there has been an increase in the number of hypoxic bottom water events on the Changjiang LDE over the past 60 years.

Li, Xinxin; Bianchi, Thomas S.; Yang, Zuosheng; Osterman, Lisa E.; Allison, Mead A.; DiMarco, Steven F.; Yang, Guipeng

2011-06-01

209

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

Energy Technology Data Exchange (ETDEWEB)

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

Garono, Ralph; Anderson, Becci; Robinson, Rob

2003-10-01

210

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

Science.gov (United States)

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

Pang, A. P.; Sun, T.

2014-05-01

211

Sediment transport in response to changes in river discharge and tidal mixing in a funnel-shaped micro-tidal estuary  

Science.gov (United States)

Huangmaohai Estuary is a micro-tidal funnel-shaped estuary, located along the southwestern side of the Pearl River Delta complex. Variations of sediment transport patterns under different conditions of river discharge and tidal mixing are investigated by using field measurements and data analysis during both dry and wet seasons, respectively. The intratidal variation of sediment dynamics is largely controlled by the tidal asymmetry. The typical pattern of 25-hour mean sediment transport during the dry season is that the transport is landward in the channel and seaward on the shoals. A bifurcation pathway of sediment transport shows that sediments are imported from the East Opening and exported through the Middle Opening. However, this pattern can be altered by mixing processes and river discharge. Enhanced mixing or increased discharge can result in a predominantly seaward transport. Conversely, weak mixing can result in an emphatic landward transport. In general, the sediment transport is closely associated with the morphological evolution in the estuary.

Gong, Wenping; Jia, Liangwen; Shen, Jian; Liu, James T.

2014-03-01

212

Atmospheric nitrogen deposition to forest and estuary environments in the Pearl River Delta region, southern China  

Directory of Open Access Journals (Sweden)

Full Text Available Due to its significant ecological and climate consequences, atmospheric nitrogen (N deposition is a growing global concern, especially in the severely N-polluted regions such as the Pearl River Delta (PRD region of southern China. One-year measurements of reactive N species, including ammonium nitrogen ( -N, nitrate nitrogen (-N and total organic nitrogen (ON in dry and wet deposition, were conducted using an automated wet–dry sampler incorporated with a DDAS (dry deposition on aqueous surface sampling device at Dinghushan (DHS, a natural forest site in the northwest of PRD and at Hengmen (HM, an estuary site in the south of PRD during 2006–2007. Total deposition fluxes of N at DHS and HM were up to 48.2 and 37.8 kg ha?1 yr?1, respectively, with most of the deposition occurring in the rainy season. Wet deposition was the dominant form, contributing 65–70% to the total deposition. -N was the largest contributor to the total N deposition at DHS (47% due to significant influence of agriculture emissions. ON was the most important N component at HM (41%, which is probably attributed to the marine sources. However, -N deposition is increasing rapidly recently and is expected to be more important in the near future. The current N deposition level in PRD is much higher than those in Europe and North America. Great challenges exist in reducing reactive N emission in this region. Thus, a scenario of rising N deposition in PRD in the near future cannot be ruled out. The environmental consequences due to elevated N deposition should therefore be paid more attention in the future.

Xuemei Wang

2013-09-01

213

Microphytobenthic biomass and species composition in intertidal flats of the Nakdong River estuary, Korea  

Science.gov (United States)

Intertidal microphytobenthos (MPB) were investigated monthly from August 2006 to March 2008 at four different sites in the sand flats of Nakdong River estuary, Korea. Samples of surface sediment (ca. 1 cm) were collected, and chlorophyll a was extracted as biomass estimation. Species identification and enumeration were carried out by light microscopy, assisted where necessary by scanning electronic microscopy. Biomass varied between 0.47 and 16.58 ?g cm -3, abundance changed from 5.25 to 414.75 × 10 3 cells cm -3, while the Shannon diversity indexes ranged between 0.69 and 2.35 H'. Thirty-nine MPB taxa were identified, primarily composed of epipelic diatoms, among which Amphora and Navicula were the most abundant genera. Based on the biomass, abundance, species composition and their dynamics, MPB assemblages of sampling sites were grouped into three distinct communities corresponding to their sediment composition characteristics. Multivariate correlation analysis revealed that biomass was positively related to mud and very fine sand, negatively related to fine and medium sand, but not significantly related to environmental factors such as pore water nutrients, light intensity and salinity, which fluctuated rapidly during emersion period. Cluster analysis corroborated the division of MPB communities according to site types on seasonal scales, and also showed seasonality between sites by cluster of all summer groups. Principal component analysis identified that variability in species composition was significantly affected by mud, very fine sand, fine sand, light intensity, and sediment temperature. This study suggests that sediment composition plays an important role in the functioning of intertidal MPB communities in estuarine ecosystems.

Du, GuoYing; Son, Moonho; Yun, Misun; An, Soonmo; Chung, Ik Kyo

2009-05-01

214

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

Science.gov (United States)

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

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

2009-06-01

215

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

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

QianqianLi

2012-08-01

216

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

Science.gov (United States)

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

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

2009-01-01

217

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

Scientific Electronic Library Online (English)

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

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

218

Porewater advection of ammonium into the Neuse River Estuary, North Carolina, USA  

Science.gov (United States)

Radon-222 ( 222Rn) and ammonium (NH 4+) were measured in interstitial water of the Neuse River Estuary (NRE), North Carolina, USA to determine the advective flux of NH 4+ from sediments to the overlying water column. Porewater samples were collected over an annual cycle from multi-level piezometers installed in nearshore sites. NH 4+ concentrations in sandy environments of the NRE were 10-fold higher than concentrations in the overlying water column. Shallow porewaters exhibited seasonal variations in NH 4+ concentrations, which resulted in temporal changes in NH 4+ flux from the sediment. Submarine groundwater discharge (SGD) was measured indirectly by using 222Rn as a tracer and directly via seepage meters. Discharge rates were variable depending upon the sampling location and season. The mean SGD was 9.1 ± 1.5 cm d -1 with a maximum SGD during spring at a rate of 13.6 cm d -1 based on 222Rn porewater distribution. High porewater NH 4+ concentrations in sandy nearshore sediments contributed NH 4+ to the overlying water via groundwater discharge as an advective process. The overall mean NH 4+ flux was 11.2 ± 2.0 mmol NH 4+ m -2 d -1. Seasonal trends in groundwater seepage rates and NH 4+ concentration suggest that groundwater is an important mechanism advecting nutrients from porewaters to surface waters, which is comparable to riverine NH 4+ discharge. SGD N:P ratios (NH 4+ as N) were >16:1, indicating that SGD is an important contributor of inorganic N for phytoplankton growth and may influence the NRE toward a less N-limited system. The data from this study will advance current understanding about the role of NH 4+ in the progressive eutrophication of shallow estuarine ecosystems.

Null, Kimberly A.; Corbett, D. Reide; DeMaster, David J.; Burkholder, JoAnn M.; Thomas, Carrie J.; Reed, Robert E.

2011-12-01

219

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

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

Tim Webster

2014-03-01

220

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Luciana Alvarenga; Rosebel Cunha Nalesso

2006-01-01

 
 
 
 
221

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Phytoplankton and microbiological analysis of three different sites of each of El-Manzala Lake Water and Rashid branch of the River Nile of Egypt were examined. The results were compared and correlated with each other and with certain physico-chemical parameters using MVSP Ver. 3.1 program for Canonical Corresponding Analysis (CCA). Chlorophyceae and Bacillariophyceae represented 47.6 and 45.9% of the total phytoplankton in El-Manzala Lake Water, which was more, polluted than Rashid estuary w...

Mostafa, Sohair A.; Hewedy, Maha A.; Hussein; Touliabah, E.; Sanaa; Ashour, M.; Abdallah, Soad A.

2003-01-01

222

Carbon dynamics of Deep Bay, eastern Pearl River Estuary, China. I: a mass balance budget and implications for shorebird conservation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Deep Bay is a shallow embayment (112 km2) in the eastern Pearl River Estuary, China, and comprises 4 major wetland components: (1) a shallow brackish water body of 2.9 m average depth, (2) 2700 ha of intertidal mudflat, (3) 200 ha of tidal mangroves and (4) 300 ha of traditional tidal aquaculture ponds excavated in the mid-to-high intertidal region. A carbon budget is proposed for Deep Bay based on published information on the 4 major landscape components. Despite the usual emphasis placed on...

Li, Ms; Lee, Sy

1998-01-01

223

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

Scientific Electronic Library Online (English)

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

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

224

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

Science.gov (United States)

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

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

2014-10-01

225

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

International Nuclear Information System (INIS)

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

226

Mercury dynamics in sulfide-rich sediments: Geochemical influence on contaminant mobilization within the Penobscot River estuary, Maine, USA  

Science.gov (United States)

Research concerning the fate and biogeochemical cycling of mercury (Hg) within coastal ecosystems has suggested that microbially mediated diagenetic processes control Hg mobilization and that ligands with strong affinity for Hg, such as dissolved inorganic sulfide (S(-II)) and dissolved organic matter (DOM), control Hg partitioning between the dissolved and particulate phases. We have studied total Hg cycling in the sediments of the Penobscot River estuary using a combination of equilibrium porewater samplers and kinetic modeling. The Penobscot estuary has been subject to Hg contamination from multiple industries including a recently closed chlor-alkali production facility. The Hg concentration within the estuary surface sediments ranges from 1.25 to 27.5 nmol Hg g -1 sediment and displays an association with sediment organic matter and a concentration maximum within 3 cm of the sediment-water interface (SWI). Porewater profiles for the Penobscot estuary are divisible into three kinetically discrete intervals with respect to Hg dynamics. Beginning at depth in the sediment and moving upward toward the SWI we have defined: (1) a zone of net Hg solubilization at depth, with a zero-order net Hg production rate (RnetHg)=3.7-5.2×10-20mol cms, (2) a zone of net Hg consumption within the zone dominated by FeS (s) precipitation with RnetHg=-0.75to-1.4×10-20mol cms, and (3) a zone of net diffusive transfer within the vicinity of the SWI. Zone 1 is characterized by dissolved S(-II) concentrations ranging from 400 to 500 ?M. Equilibrium modeling in this zone suggests that inorganic S(-II) plays the dominant role in both mobilization of sediment-bound Hg and complexation of dissolved Hg. In zone 2, FeS (s) precipitation occurs concomitant with Hg consumption. Net transfer within zone 3 is consistent with the potential for ligand-mediated Hg efflux across the SWI. S(-II)-mediated Hg mobilization at depth in Penobscot estuary sediments suggests a broadening of the depth interval over which biogeochemical Hg cycling must be examined. Our results also show that, while estuary sediments act as a net sink for particulate Hg inputs, they may also function for a considerable time interval as a source of dissolved Hg.

Merritt, Karen A.; Amirbahman, Aria

2007-02-01

227

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

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

José Mauro Sterza

2006-12-01

228

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

José Mauro, Sterza; Luiz Loureiro, Fernandes.

229

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

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

James P. Udoh

2011-07-01

230

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

International Nuclear Information System (INIS)

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

231

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

Science.gov (United States)

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. PMID:23591678

Wang, Shiliang; Wang, Hui; Deng, Wenjing

2013-10-01

232

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

233

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

Science.gov (United States)

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

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

2014-10-15

234

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

Energy Technology Data Exchange (ETDEWEB)

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

Xianzhi Peng; Zhendi Wang; Yiyi Yu (and others) [Chinese Academy of Sciences, Guangzhou (China). State Key Laboratory of Organic Geochemistry

2008-11-15

235

A Synthesis of Environmental and Plant Community Data for Tidal Wetland Restoration Planning in the Lower Columbia River and Estuary  

Energy Technology Data Exchange (ETDEWEB)

This report reanalyzes and synthesizes previously existing environmental and plant community data collected by PNNL at 55 tidal wetlands and 3 newly restored sites in the lower Columbia River and estuary (LCRE) between 2005 and 2011. Whereas data were originally collected for various research or monitoring objectives of five studies, the intent of this report is to provide only information that will have direct utility in planning tidal wetland restoration projects. Therefore, for this report, all tidal wetland data on plants and the physical environment, which were originally developed and reported by separate studies, were tabulated and reanalyzed as a whole. The geographic scope of the data collected in this report is from Bonneville Lock and Dam to the mouth of the Columbia River

Diefenderfer, Heida L.; Borde, Amy B.; Cullinan, Valerie I.

2013-12-01

236

An experimental transplantation to select the optimal site for restoration of the eelgrass Zostera marina in the Taehwa River estuary  

Science.gov (United States)

To select the optimal site for the restoration of seagrass habitats in the Taehwa River estuary, we transplanted the eelgrass Zostera marina to three potential candidate sites in March 2007 and monitored the transplanted seagrass and associated environmental factors for six months. In all three sites, the transplanted seagrasses exhibited no initial morphological loss due to transplanting stress. The transplanted seagrass communities at sites 2 and 3 showed more than a 180% increase in density over the entire survey period. In contrast, despite a density increase in the first month after transplantation, most of the transplanted seagrasses at site 1 died. This may be due to the large decrease in underwater irradiance reaching the seagrass leaves at site 1 for two months during June and July, which fell below the level of compensation irradiance. The growth rate and size of the seagrass shoots were also larger at sites 2 and 3 compared with site 1. This is probably due to higher nutrient concentrations in the sediment pore water at sites 2 and 3 compared with site 1, although water depth, salinity, and the nutrient concentrations in the water columns from the three sites were similar. Therefore, for the restoration of seagrass habitats in the Taehwa River estuary, sites 2 and 3 were preferable to site 1 as transplantation sites.

Park, Jung-Im; Kim, Jeong Bae; Lee, Kun-Seop; Son, Min Ho

2013-12-01

237

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

238

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.

239

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

International Nuclear Information System (INIS)

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

240

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

 
 
 
 
241

Current status and ecological roles of Zostera marina after recovery from large-scale reclamation in the Nakdong River estuary, Korea  

Science.gov (United States)

Large Zostera marina meadows (covering 13.6 km 2) existed in the Nakdong River estuary on the south coast of Korea until the mid-1980s, but these Z. marina beds nearly disappeared due to reclamation of adjacent mud flats for the construction of a port and industrial complex during the late 1980s. Partial recovery of Z. marina meadows occurred recently, and Z. marina coverage of about 0.3 km 2 was observed in this estuary. In this study, shoot morphology, density, biomass, productivity, and tissue nutrient content were measured to evaluate the current status of the Z. marina meadows by comparing these data to those for persistent seagrass meadows in similar geographical areas. Additionally, we examined the ecological roles of Z. marina in this estuary after recovery from the large-scale disturbance. Shoot density (151 shoots m -2) and total biomass (141 g DW m -2) in the estuary were similar to those reported from other Z. marina meadows in Korea. Annual leaf production (1726 g DW m -2 y -1) was higher than generally observed for Z. marina in other geographical areas. These results imply that the existing Z. marina meadows in this estuary have adjusted to local environmental conditions that changed after large-scale reclamation. Estimated annual whole plant carbon (C) and nitrogen (N) incorporations based on shoot production and tissue C and N content were 810.0 g C m -2 y -1 and 59.7 g N m -2 y -1, respectively. These values were equivalent to 2.4 × 10 5 kg C y -1 and 1.8 × 10 4 kg N y -1 for all Z. marina beds in the Nakdong River estuary. This high C and N incorporation into Z. marina tissues suggests that existing Z. marina meadows play important roles in C and N cycles in this estuary. Although the currently existing Z. marina beds in this estuary are persisting and play an important ecological role, anthropogenic factors that cause seagrass declines still affect the estuary. Thus, effective management and monitoring of Z. marina beds and environmental factors are critical to protecting and conserving this invaluable component of the Nakdong River estuary.

Park, Sang Rul; Kim, Jong-Hyeob; Kang, Chang-Keun; An, Soonmo; Chung, Ik Kyo; Kim, Jeong Ha; Lee, Kun-Seop

2009-01-01

242

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

Science.gov (United States)

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

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

2014-09-15

243

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

International Nuclear Information System (INIS)

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

244

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

Science.gov (United States)

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

Sanders, Tina; Dähnke, Kirstin

2014-05-01

245

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

246

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

Science.gov (United States)

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

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

2014-11-01

247

Mercury in bottom sediments of the Amur River, its flood-plain lakes and estuary, Eastern Siberia.  

Science.gov (United States)

Mercury (Hg) is an element of a special concern in the Amur River basin, where numerous cinnabar deposits and manifestations have been prospected. Moreover, the territory is under heavy anthropogenic pressure due to intensive economic development that includes activities accompanied by noticeable emissions of Hg to the environment through poor waste management practices and accidental emergency discharges. Yet, information on Hg distribution and behavior in this region is scarce and inadequate. In order to evaluate Hg levels and fate in this vast territory, surveys of river, lake, and estuarine bottom sediments, as integral indicators of environmental status, were carried out in 1990, 1991, 1997, and 2004. The results showed the following: (1) stagnation of the Russian economy in the 1990s has resulted in a noticeable decrease of the Hg content in the Amur River sediments to the basin pristine level of about 0.05 mg kg(-1); (2) Hg distribution in the sediment depth proves the element redox-dependent behavior; (3) in some cases, Hg enrichment may be related to the long-term anthropogenic emission; (4) Hg concentration in bottom sediments was found to increase in the following order-the Amur River mouth, the estuary, and the Sea of Okhotsk, showing the weakly non-conservative Hg behavior during estuarine water mixing. PMID:19629736

Kot, Fyodor S; Bakanov, Konstantin G; Goryachev, Nikolay A

2010-09-01

248

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

Science.gov (United States)

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

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

2014-02-01

249

Use of Satellite Images to map Flood Extension around the city of Saint Louis in the Senegal River Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available The traditional method of landsat satellite data combination and the gathering of important information made it possible to produce a Geographical Information System to monitor floods in the lower estuary of the Senegal River valley (Sandholt,I., Fog, B. & Fensholt, R., 2001. This technical approach is a powerful tool for combining important information for a better comprehension of the floods and the characterization of surface qualities on the estuary. By way of a multi-temporal approach, the study team established the qualitative and quantitative impact of floods on the various geographical objects, a detailed cartography of the land use and the surfaces flooded in 1998 and 1999. The study undertaken in Saint Louis made it possible to consider surfaces flooded in 1999, and to understand the extent of these floods compared to those of 1998. The constitution of a tool of decision-making aid makes it possible to have information relating to the extent of the flood, the scope of flooded surfaces and to detect the more exposed zones in order to establish a hierarchical map according to the percentage of exposure to the risk of the geographical objects affected by the floods (populations, road infrastructures and tracks, medical and social infrastructures and perimeters of cultures (agriculture.

Aliou Dia

2006-04-01

250

Chesapeake Bay habitat criteria scores and the distribution of submersed aquatic vegetation in the tidal Potomac River and Potomac Estuary, 1983-1997  

Science.gov (United States)

The Chesapeake Bay Program has identified habitat requirements for the restoration of submersed aquatic vegetation (SAV) in the Chesapeake Bay estuary and tidal reaches of contributing river systems conditioned on the salinity regime of a specific location. The tidal Potomac River and Potomac Estuary is an important component of the Chesapeake Bay system to which these requirements can be applied. The SAV habitat requirements are formulated as threshold criteria that certain critical water-quality characteristics must satisfy during the SAV growing season. A multivariate scoring system based on these criteria was developed in order to synopsize water quality conditions during the 1983-1997 SAV growing seasons. Chesapeake Bay habitat criteria scores are displayed relative to annual SAV coverage for each Potomac River and Potomac Estuary segment. It is seen that although there is some correspondence in the inter-annual expansion or contraction of SAV coverage and compliance with Chesapeake Bay SAV habitat criteria, individual criteria provide neither necessary nor sufficient conditions to explain inter-annual dynamics of SAV coverage, especially in the Potomac Estuary.

Landwehr, J. M; Reel, J. T.; Rybicki, N. B.; Ruhl, H. A.; Carter, Virginia

1999-01-01

251

Correlations among seasonal water quality, discharge, weather, and coverage by submersed aquatic vegetation in the tidal Potomac River and Potomac Estuary, 1983-96  

Science.gov (United States)

The U.S. Geological Survey has been cooperating with other scientists under the auspices of the Interstate Commission on the Potomac River Basin to utilize existing data from the tidal Potomac River and Estuary for investigating linkages among living resources (primary producers, consumers) and abiotic components of the environment. Because the distribution and abundance of submersed aquatic vegetation in the tidal Potomac River and Estuary are controlled largely by light availability, the first step in investigating linkages with submersed aquatic vegetation is to examine the correlations that exist among vegetative cover, discharge, water quality and weather, all of which can affect light availability directly or indirectly. Growing season (April-October), spring (April-June), and summer (July-August) correlations are presented along with figures demonstrating the significant relationships among variables.

Carter, Virginia; Rybicki, N. B.; Landwehr, J. M.; Reel, J. T.; Ruhl, H. A.

1998-01-01

252

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

253

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

Science.gov (United States)

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

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

2014-09-15

254

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

International Nuclear Information System (INIS)

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

255

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

International Nuclear Information System (INIS)

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

256

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

Science.gov (United States)

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

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

2008-06-01

257

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

Science.gov (United States)

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

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

1998-01-01

258

Relationships between pesticides and organic carbon fractions in sediments of the Danshui River estuary and adjacent coastal areas of Taiwan  

International Nuclear Information System (INIS)

In order to understand the fate of pesticides in marine environments, concentrations of pesticides and different carbonaceous fractions were determined for surface sediments in the Danshui River and nearby coastal areas of Taiwan. The major compounds detected were tetrachlorobenzene, HCHs, chlordane, aldrin, DDDs, DDEs and DDTs. Total concentrations of pesticides in the sediments ranged from not detectable to 23 ng g-1, with the maximum value detected near the discharge point of the marine outfall from the Pali sewage treatment plant. These results confirm that pesticides persist in estuarine and nearby coastal environments of the Danshui River well after their ban. Concentrations of total pesticides significantly correlate with concentrations of total organic carbon and black carbon in these sediments, suggesting that total organic carbon and black carbon regulate the distribution of trace organic pollutants in fluvial and coastal marine sediments. - Total organic carbon and black carbon regulate the distribution of trace organic pollutants in sediments of the Danshui River estuary and adjacent coastal areas of Taiwan

259

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

Science.gov (United States)

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

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

2011-12-01

260

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

Energy Technology Data Exchange (ETDEWEB)

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

Peng Xianzhi [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehau Street, Guangzhou 510640 (China)], E-mail: pengx@gig.ac.cn; Wang Zhendi [Environmental Science and Technology Centre, Environment Canada, 335 River Road, Ottawa, Ontario K1A 0H3 (Canada); Yu Yiyi; Tang Caiming; Lu Hong; Xu Shiping; Chen Fanrong; Mai Bixian; Chen Shejun; Li Kechang [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehau Street, Guangzhou 510640 (China); Yang Chun [Environmental Science and Technology Centre, Environment Canada, 335 River Road, Ottawa, Ontario K1A 0H3 (Canada)

2008-11-15

 
 
 
 
261

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

International Nuclear Information System (INIS)

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

262

Identification of heavy metal sources in the reclaimed farmland soils of the pearl river estuary in China using a multivariate geostatistical approach.  

Science.gov (United States)

Heavy metals in the reclaimed farmland soils of the Pearl River Estuary in China have attracted much attention because of the health risk posed to local residents. The identification of heavy metal sources in these soils is necessary to reduce their health risk. Reclaimed farmland soil samples were collected from 144 sites in the Pearl River Estuary and the contents of heavy metals (Cd, Pb, Cr, Ni, Cu, and Zn) were determined. All these heavy metals showed concentrations substantially higher than their background values, indicating possible anthropogenic pollution. The results of a multivariate geostatistical method demonstrate that grouped Cd, Cr, and Cu were mainly controlled by chemical fertilizers. Grouped Pb and Zn were the most severely impacted by atmospheric deposition from Guangzhou and Foshan, and Ni was primarily impacted by electroplating factories' wastewater discharge. PMID:24780227

Gu, Yang Guang; Li, Qu Sheng; Fang, Jian Hong; He, Bao Yan; Fu, Hong Bo; Tong, Ze Jun

2014-07-01

263

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-02-15

264

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

International Nuclear Information System (INIS)

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

265

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

Science.gov (United States)

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 microm, 10-53 microm, 2-10 microm, 0.4-2 microm, 10 kDa-0.4 microm and the 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 microm fraction had the least share (0-1%), while the 10-53 microm 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 microm fraction to 3.7 in the 10 kDa-0.4 microm fraction, indicating that the radiogenic Th isotopes are preferentially scavenged by the small size particles. (230Th/232Th)(A.R.) in the removal of 232Th during the mixing of fresh water with seawater. The behavior of Th isotopes in the <10 kDa fraction followed those in the dissolved phases. The difference in geochemical behaviors among three Th isotopes was ascribed to their different sources in the estuary. PMID:15511559

Zhang, Lei; Chen, Min; Yang, Weifeng; Xing, Na; Li, Yanping; Qiu, Yusheng; Huang, Yipu

2005-01-01

266

Uptake and distribution of N, P and heavy metals in three dominant salt marsh macrophytes from Yangtze River estuary, China.  

Science.gov (United States)

We examined the variation in aboveground biomass accumulation and tissue concentrations of nitrogen (N), phosphorus (P), copper (Cu), zinc (Zn) and lead (Pb) in Phragmites australis (common reed), Spartina alterniflora (salt cordgrass), and Scirpus mariqueter throughout the growing season (April-October 2005), in order to determine the differences in net element accumulation and distribution between the three salt marsh macrophytes in the Yangtze River estuary, China. The aboveground biomass was significantly greater in the plots of S. alterniflora than in the plots of P. australis and S. mariqueter throughout the growing season (Ppatterns. There was a steady decline in element concentrations of the aboveground tissues from April to October. Relative element concentrations in aboveground tissues were at a peak during the spring sampling intervals with minimum levels during the fall. But the concentrations of total nitrogen and total phosphorus in the belowground tissues were relatively constant throughout growing season. Generally, trace metal concentrations in the aboveground tissues of S. mariqueter was the highest throughout the growing season, and the metal concentrations of S. alterniflora tissues (aboveground and belowground) were greater than those of P. australis. Furthermore, the aboveground pools of nutrients and metals were consistently greater for S. alterniflora than for P. australis and S. mariqueter, which suggested that the rapid replacement of native P. australis and S. mariqueter with invasive S. alterniflora would significantly improve the magnitude of nutrient cycling and bioavailability of trace metals in the salt marsh and maybe transport more toxic metals into the water column and the detrital food web in the estuary. PMID:17306362

Quan, W M; Han, J D; Shen, A L; Ping, X Y; Qian, P L; Li, C J; Shi, L Y; Chen, Y Q

2007-07-01

267

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

Scientific Electronic Library Online (English)

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

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

2013-12-01

268

SEASONAL VARIATIONS IN RIVER DISCHARGE AND NUTRIENT EXPORT TO A NORTHEASTERN PACIFIC ESTUARY  

Science.gov (United States)

Seasonal variations in dissolved nitrogen and silica loadings were related to seasonal variability in river discharge. Dissolved nutrient concentrations measured weekly at three stations in the Yaquina River, Oregon from 1999 through 2001, and then monthly in 2002 were used as th...

269

SEASONAL VARIATIONS IN RIVER DISCHARGE AND NUTRIENT EXPORT TO A NORTHEASTERN PACIFIC ESTUARY (FINAL)  

Science.gov (United States)

Seasonal variations in dissolved nitrogen and silica loadings were related to seasonal variability in river discharge. Dissolved nutrient concentrations measured weekly at three stations in the Yaquina River, Oregon from 1999 through 2001, and then monthly in 2002 were used as th...

270

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.

R. SINGH

2009-08-01

271

[Heavy metal accumulation during last hundred years and its assessment of potential ecological risk in the coastal wetland of Qi'ao Island, Pearl River Estuary of China].  

Science.gov (United States)

The processes of fine sediment transport and deposition can record some relative anthropogenic information in estuarine environments. Grain size analysis of the sediment core collected from coastal wetland of Qi'ao Island in the Pearl River Estuary of China show that the sediment is mainly composed by clayey silt, and the mean grain size, contents of clay and silt increase upward gradually. Chronology analysis show that the sedimentation rate above 59 cm is about 4.15 cm x a(-1), and 0.97 cm x a(-1) beneath 59 cm. Heavy metal analysis indicate that the contents of the each heavy metal increased slowly with a slight intensity of potential ecological risk; however, from 1966 to 1992, the heavy metal contents increased obviously because of the quick social-economy development around the Pearl River Estuary area, and the order of polluting degree of these heavy metals in core sediment is Cd > Ni > Pb > Cu > Cr > Zn. The potential ecological risk intensity of Cd increased from slight risk before 1966 to strong risk since 1992, and the potential ecological risk intensities other heavy metal are slight risk; the potential ecological risk index is weak level. The variations of core sediment heavy metal contents and its ecological risk assessments along the vertical profile reveal the interaction processes and intent of anthropogenic influences from the areas around the Pearl River Estuary and the catchments. PMID:21780584

Wang, Ai-jun; Ye, Xiang; Li, Tuan-jie; Huang, Cai-bin

2011-05-01

272

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

Scientific Electronic Library Online (English)

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

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

2010-06-01

273

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

Science.gov (United States)

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

Song, Hongli; Sun, Zhigao

2014-12-01

274

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

2011-12-01

275

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

Science.gov (United States)

...alternative management technique...mitigate impacts of flood...lagoon management period...Russian River watershed (NMFS...development and evaluation of management alternatives...the jetty impacts beach...

2013-04-22

276

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

International Nuclear Information System (INIS)

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

277

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

Science.gov (United States)

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

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

2013-01-01

278

Compound- and mixture-specific differences in resistance to PAHs 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 kilometers 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 hours post fertilization (hpf); CYP1 activity was determined by in ovo ethoxyresorufin-o-deethylase (EROD) 96 hpf and cardiac deformity severity was scored 144 hpf. The total PAH levels measured among the sites varied from approximately 200–125,000 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.

2014-01-01

279

Contribution of priority PAHs and POPs to Ah receptor-mediated activities in sediment samples from the River Elbe Estuary, Germany.  

Science.gov (United States)

The estuary of the River Elbe between Hamburg and the North Sea (Germany) is a sink for contaminated sediment and suspended particulate matter (SPM). One major concern is the effect of human activities on the hydrodynamics, particularly the intensive dredging activities in this area that may result in remobilization of sediment-bound pollutants. The aim of this study was to identify pollutants contributing to the toxicological risk associated with re-suspension of sediments in the Elbe Estuary by use of an effect-directed analysis that combines chemical and biological analyses in with specific fractionation techniques. Sediments were collected from sites along the Elbe Estuary and a site from a small harbor basin of the Elbe Estuary that is known to be polluted. The sixteen priority EPA-PAHs were quantified in organic extracts of sediments. In addition, dioxin equivalents of sediments were investigated by use of the 7-ethoxyresorufin O-deethylase assay with RTL-W1 cells and the Ah receptor-mediated luciferase transactivation assay with H4IIE-luc cells. Quantification of the 16 priority PAHs revealed that sediments were moderately contaminated at all of the sites in the Elbe River Estuary (<0.02-0.906 µg/g dw). Sediments contained relatively small concentrations of dioxin equivalents (Bio-TEQ) with concentrations ranging from 15.5 to 322 pg/g dw, which were significantly correlated with dioxin equivalents calculated based on toxicity reference values and concentrations of PAH. The concentration of Bio-TEQ at the reference site exceeded 200,000 pg/g dw. In a potency balance the 16 PAHs explained between 47 and 118% of the Bio-TEQ in the luciferase assay, which can be explained by the constant input of PAHs bound to SPM from the upper course of the Elbe River into its estuary. Successful identification of a significant portion of dioxin-like activity to priority PAHs in complex environmental samples such as sediments has rarely been reported. PMID:24146763

Otte, Jens C; Keiter, Steffen; Faßbender, Christopher; Higley, Eric B; Rocha, Paula Suares; Brinkmann, Markus; Wahrendorf, Dierk-Steffen; Manz, Werner; Wetzel, Markus A; Braunbeck, Thomas; Giesy, John P; Hecker, Markus; Hollert, Henner

2013-01-01

280

Sources and Transformations of Carbon and Nitrogen in the Potomac River Estuary  

Science.gov (United States)

Urbanization has altered the transport of nitrogen (N) and carbon (C) in river ecosystems, making it important to understand how rivers are responding to these increased inputs of C and N. This study examines the capacity of a major tributary of the Chesapeake Bay, the Potomac River, to transform N and C inputs from the world's largest advanced wastewater treatment facility (Washington D.C. Water and Sewer Authority). Surface water and effluent samples were collected monthly for one year, along longitudinal transects of the Potomac River. Water samples were analyzed for the major dissolved and particulate forms of C and N. Nitrate stable isotopes were used to trace the fate of wastewater nitrate, as well as how other nitrate sources vary downriver. Sources of carbon downriver were traced using fluorescence spectroscopy, excitation emission matrices (EEMs), and PARAFAC modeling. Historical influent and effluent data on C and N levels were also compared with regional population growth data, climate change data, and long-term interannual records of C and N levels within downstream stations along the Potomac River. Improvements in treatment technology over the past two decades have shown significant decreases in effluent nitrogen levels, with corresponding decreases overtime of nutrients at downstream sampling stations. Levels of nitrate show increases within the vicinity of the wastewater treatment outfall, but decrease rapidly downstream, potentially indicating nutrient uptake and/or denitrification. Total organic carbon levels show a smaller decrease downstream, resulting in an increase in the C:N ratio downstream. Longitudinal river chemistry data also show that dissolved inorganic nitrogen goes down while total organic nitrogen goes up with distance downriver, indicating biological transformations are taking place along the river. Preliminary data from fluorescence EEMs suggested that more humic-like organic matter is important above the wastewater treatment plant, but more protein-like organic matter is present below the treatment plant. However, this fluorescence signal from wastewater organic matter disappears within 2-4 km downriver, indicating rapid processing of the labile organic matter within the river. Nitrate isotope data for both upriver and downriver samples show a signal from manure or sewage inputs, indicating a potential influence from animal farms upstream in the Potomac. However, only the downriver samples show evidence for denitrification. Additionally, the higher 15N isotope levels of nitrate, which are characteristic of wastewater sources, disappear by 20 km downriver. Majors rivers like the Potomac may have a huge capacity for transforming and processing large carbon and nitrogen inputs within a short distance. Greater knowledge of how land management and climate change impacts these transformations will be important in predicting changes in the amounts, forms, and stoichiometry of nutrient loads to coastal waters.

Pennino, M. J.; Kaushal, S.; Murthy, S.

2011-12-01

 
 
 
 
281

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

Energy Technology Data Exchange (ETDEWEB)

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.

Yang, Zhaoqing; Liu, Hedong; Khangaonkar, Tarang P.

2006-08-03

282

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

International Nuclear Information System (INIS)

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 outsio the mudflats and tidal marsh areas outside of diked regions and then improve the estuarine habitats for salmon migration

283

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  

Directory of Open Access Journals (Sweden)

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

Hongyan Xi

2009-11-01

284

[Serological monitoring of arbovirus infections in the estuary of the Kuban River (the 2006-2007 data)].  

Science.gov (United States)

Solid-phase enzyme immunoassay, neutralization test, and the hemagglutination-inhibition test were used to study the sera from human beings (152 samples), agricultural animals (n = 77), hares (n = 3), and wild birds (n = 69), collected in 2006-2007 in the Kuban River estuary (Temryuk District, Krasnodar Territory). There were specific antibodies against viruses of West Nile (WH), tick-borne encephalitis (TBE) (Flaviviridae, Flavivirus), Sindbis (Togaviridae, Alphavirus), the antigenic complex of California, Batai (Bunyaviridae, Orthobunyavirus), Dhori (Orthomyxoviridae, Thogotovirus). The findings suggest the presence of arboviruses from 6 transmitting mosquitoes and ticks in the study area and human infection by the viruses of the antigenic complex of California (20-47%), Batai (3-15%), West Nile (3-12%), Dhori (2%). The index agricultural animals (horses, cattle) were observed to have specific antibodies to the viruses of WN (8-15%), TBE (0-2%), Sindbis (2-9%), the antigenic complex of California (27-54%). Out of the representatives of the wild fauna, virus-neutralizing antibodies to Sindbis virus were found in European hares (Lepus europaeus), California complex virus in gulls (Larus argentatus) and terns (Sterna hirundo), WN and Sindbis viruses in herons (Ardea purpurea), and WN and California complex viruses in bald-coots (Fulica atra). PMID:18756814

L'vov, D K; Shchelkanov, M Iu; Kolobukhina, L V; L'vov, D N; Galkina, I V; Aristova, V A; Morozova, T N; Proshina, E S; Kulikov, A G; Kogdenko, N V; Andronova, O V; Pronin, N I; Shevkoplias, V N; Fontanetski?, A S; Vlasov, N A; Nepoklonov, E A

2008-01-01

285

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

Science.gov (United States)

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

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

2014-10-01

286

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

Science.gov (United States)

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

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

2014-08-01

287

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

Directory of Open Access Journals (Sweden)

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

Larry B. Crowder

2011-11-01

288

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

Science.gov (United States)

This study examined the role that submarine groundwater discharge plays in transporting land-derived nitrogen, primarily from agricultural fertilizer use, to a tributary of Chesapeake Bay, and the degree of removal by denitrification in the freshwater aquifer and fresh/saline groundwater mixing zone prior to discharge. Nutrient analysis, salinity measurements, age dating using dissolved anthropogenic tracers, and membrane-inlet mass spectrometry (MIMS), were combined to examine nutrient loading from the upper 8 m of the submarine aquifer to the Corsica River Estuary. The site was intensively sampled, using hand-driven piezometers along a five-point transect perpendicular to the shoreline spanning the nearshore discharge zone. The total length of the transect was 42 m, and an average of nine depths were sampled at each piezometer location. There is fresh water present in the aquifer (salinity tritium and chlorofluorocarbon analyses, indicate the presence of older water which is less impacted by anthropogenic nitrogen inputs. MIMS results show large concentrations of excess gas above equilibrium concentrations, but interpretation of a denitrification signal may be confounded by artificial recharge due to irrigation.

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

2008-12-01

289

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

Directory of Open Access Journals (Sweden)

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

Gyeong-je Joh

2013-12-01

290

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

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

Luciana Alvarenga

2006-01-01

291

Spatial intertidal distribution of bivalves and polychaetes in relation to environmental conditions in the Natori River estuary, Japan  

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This paper aims to reveal spatial variation in the abundance of infaunal bivalves and polychaetes at different spatial scales (station: 200-800 m intervals; plot: 5-20 m), and to reveal environmental variables affecting the spatial distribution of animals in the Natori River estuary, Japan. We found six bivalve species and eight polychaete species from 52 plots at 12 stations. Nuttallia olivacea and Heteromastus sp. were found to be the most abundant species of bivalves and polychaetes, respectively. Assemblage patterns of bivalves and polychaetes were classified into five distinct groups. Substrata (silt-clay contents), salinity, and relative elevation were the variables found to affect the infaunal assemblage patterns. Chlorophyll a was not a significant variable, but benthic animals were absent at sites with extremely low chlorophyll a conditions. Macrobenthic assemblage patterns were different not only between stations but often differed between plots at the same station, reflecting the complex assemblage structure of benthic invertebrates. Detailing such animal-environment relationship is essential in understanding the potential food supply for estuarine fishes.

Tomiyama, Takeshi; Komizunai, Nobuhiro; Shirase, Tatsuya; Ito, Kinuko; Omori, Michio

2008-11-01

292

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

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

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

2013-03-01

293

Determination of the trace of some heavy metals (Cd, Pb, Hg) in marine shore sediments of Alkabeer Aljnouby River estuary  

International Nuclear Information System (INIS)

This study aims to determine of concentration of three trace heavy metals (Cd, Pb, Hg) in the marine shore sediments collected from nine sites of Alkabeer Aljnouby river estuary during the period (5/7/2004-29/6/2005), using cold vapor technique for the determination of Hg and (ETA-AAS) for Cd and Pb. Results revealed that the medians accumulation in the marine shore sediments at all studied sites ranged between (3.46-16.60 ?g/g dry wt.), (nd-0.085 ?g/g dry wt.) and (nd-0.096 ?g/g dry wt.) for Pb, Cd, Hg respectively. The results showed that the concentrations of Pb at all studied sites were higher than the concentrations of Cd and Hg. The concentrations of Cd values in the sediment samples were related nearby at all studied sites during the study period, while the concentrations of Hg were decreased in summer 2004 and increased in other seasons.The study of relationships between the values of concentration of the studied element concentrations in the sediment samples indicates no obvious correlation between the studied sites.(author)

294

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

295

Radium isotopes as a tool for the study of water mixing in the Paraiba do Sul River Estuary  

International Nuclear Information System (INIS)

Four isotopes of radium with different half-lives exist in nature. In aquatic systems, radium isotopes present distinct characteristics in salt water and fresh water environments. In fresh waters, radium appears adsorbed to particulate material while in sea water radium presents a conservative behavior, being the concentration of different isotopes of radium governed by the processes of dilution, advection and diffusion, as well as radioactive decay. The four natural isotopes of radium are tracers extensively used to determine ratios of water mixture and to calculate the period since the radium was added to the water column. The short-lived isotopes, 223Ra (half-life = 11.4 days) and 224Ra (half-life = 3.66 days), are continually regenerated from decay of their thorium parents, which are perpetually bound to particles surfaces. On the other hand, the long-lived isotopes, 226Ra (half-life = 1600 yrs) and 228Ra (half-life = 5.7 yrs), require considerable time for regeneration. These fluxes must be sustained by input water from rivers, sediments, SGD, or other sources. In the present work, developed at the estuary of the Paraiba do Sul River, the short half-lived radium isotopes (224Ra and 223Ra) were determined using the technique of coincidence delayed developed. The isotopes of long half-lifed (2226Ra and 2228Ra) were determined by the technique of total alpha and beta counting, after the dissolution of the MnO2 fiber used to pre-concentrate radium. (author)

296

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

Science.gov (United States)

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

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

2014-01-01

297

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

Science.gov (United States)

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

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

2014-06-15

298

The dynamics of the yeast community of the Tagus river estuary: testing the hypothesis of the multiple origins of estuarine yeasts.  

Science.gov (United States)

Yeasts are common inhabitants of different types of aquatic habitats, including marine and estuarine waters and rivers. Although numerous studies have surveyed yeast occurrence in these habitats, the identification of autochthonous populations has been problematic because several yeast species seem to be very versatile and therefore mere presence is not sufficient to establish an ecological association. In the present study we investigated the dynamics of the yeast community in the Tagus river estuary (Portugal) by combining a microbiological study involving isolation, quantification, and molecular identification of dominant yeast populations with the analysis of hydrological and hydrographical data. We set out to test the hypothesis of the multiple origins of estuarine yeast populations in a transect of the Tagus estuary and we postulate four possible sources: open sea, terrestrial, gastrointestinal and the estuary itself in the case of populations that have become resident. Candida parapsilosis and Pichia guilliermondii were correlated with Escherichia coli, which indicated an intestinal origin. Other cream-colored yeasts like Debaryomyces hansenii and Candida zeylanoides had similar dynamics, but no association with E. coli and quite distinct ecological preferences. They might represent a group of resident estuarine populations whose primary origin is diverse and can include marine, terrestrial, and gastrointestinal habitats. Another major yeast population was represented by Rhodotorula mucilaginosa. The cosmopolitan nature of that species and its moderate association with E. coli point to terrestrial sources as primary habitats. PMID:20422287

Coelho, Marco A; Almeida, João M F; Martins, Inês M; da Silva, A Jorge; Sampaio, José Paulo

2010-10-01

299

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

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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

2010-03-01

300

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

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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.

Addula Nallapa Reddy

2011-05-01

 
 
 
 
301

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

Science.gov (United States)

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

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

2004-02-01

302

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  

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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 estuary, using a conical plankton net with a 50cm mouth opening and 200 micron mesh size. The samples were obtained using the net of the plankton. Temperature and salinity were measured in situ...

Magris, R. A.; Loureiro Fernandes, L.

2005-01-01

303

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

Science.gov (United States)

The Water-Sediment Regulation Scheme (WSRS) of the Yellow River is a procedure implemented annually from June to July to expel sediments deposited in Xiaolangdi and other large middle-reach reservoirs and to scour the lower reaches of the river, by controlling water and sediment discharges. Dissolved uranium isotopes were measured in river waters collected monthly as well as daily during the 2010 WSRS (June 19-July 16) from Station Lijin (a hydrologic station nearest to the Yellow River estuary). The monthly samples showed dissolved uranium concentrations of 3.85-7.57 ?g l(-1) and (234)U/(238)U activity ratios of 1.24-1.53. The concentrations were much higher than those reported for other global major rivers, and showed seasonal variability. Laboratory simulation experiments showed significant uranium release from bottom and suspended sediment. The uranium concentrations and activity ratios differed during the two stages of the WSRS, which may reflect desorption/dissolution of uranium from suspended river sediments of different origins. An annual flux of dissolved uranium of 1.04 × 10(8) g y(-1) was estimated based on the monthly average water discharge and dissolved uranium concentration in the lower reaches of the Yellow River. The amount of dissolved uranium (2.65 × 10(7) g) transported from the Yellow River to the sea during the WSRS constituted about 1/4 of the annual flux. PMID:24292394

Juanjuan, Sui; Zhigang, Yu; Bochao, Xu; Wenhua, Dong; Dong, Xia; Xueyan, Jiang

2014-02-01

304

Pair-Trawl Detection of PIT-Tagged Juvenile Salmonids Migrating in the Columbia River Estuary, 2008 Report of Research.  

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In 2008, we sampled migrating juvenile Pacific salmonids Oncorhynchus spp. tagged with passive integrated transponder (PIT) tags using a surface pair trawl in the upper Columbia River estuary (rkm 61-83). The cod-end of the trawl was replaced with a cylindrical PIT-tag detection antenna with an 86-cm-diameter fish-passage opening and two detection coils connected in series. The pair trawl was 105 m long with a 91.5-m opening between the wings and a sample depth of 4.9 m. Also during 2008, we finalized the development of a prototype 'matrix' antenna, which was larger than previous antennas by a considerable magnitude. The matrix antenna consisted of 6 coils: a 3-coil front component and a 3-coil rear component, which were separated by 1.5-m of net mesh. The fish-passage opening was 2.5 m wide by 3.0 m tall and was attached to a standard-size pair trawl net. Intermittent sampling with a single crew began on 7 March and targeted yearling Chinook salmon O. tshawytscha and steelhead O. mykiss. Daily sampling using two crews began on 30 April and continued through 14 June; during this period we detected 2.7% of all juvenile salmonids previously detected at Bonneville Dam--a measure of sample efficiency. Sampling with a single crew continued through 20 August and targeted subyearling Chinook salmon. We detected 7,397 yearling Chinook salmon, 2,735 subyearling Chinook salmon, 291 coho salmon O. kisutch, 5,950 steelhead, and 122 sockeye salmon O. nerka in the upper estuary. We deployed the matrix antenna system and the older, cylindrical antenna system (86-cm-diameter fish-passage opening) simultaneously in mid-May 2008 to test matrix detection efficiency. The cylindrical antenna system had been used successfully in 2007 and early 2008. Because distribution of migrating salmonids in the estuary changes rapidly, we felt that a tandem sampling effort between the two systems was the only way to truly evaluate comparative detection efficiency. We deployed both systems within 1 km of each other during a period of high fish densities on 13, 14, and 15 May. Detections of the matrix system surpassed those of the cylindrical system by 53% in 14 h of simultaneous sampling (total detections 716 and 339, respectively). We believe that the higher detection rate observed with the matrix system was due to fewer smolts escaping the trawl entrance and to more smolts readily passing through the larger fish-passage opening. After tandem sampling, we continued exclusive use of the matrix system for the remainder of the 2008 juvenile migration season. Mean survival rates from Lower Granite to Bonneville Dam for yearling Chinook salmon and steelhead were 42% (SE = 3.7%) and 46% (SE = 1.5%), respectively. Over 358,000 PIT-tagged salmonids were transported, and we detected 4,619 of these fish.

Magie, Robert J.; Morris, Matthew S.; Ledgerwood, Richard D. [Northwest Fisheries Science Center

2009-06-03

305

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

Science.gov (United States)

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

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

2013-04-01

306

Occurrence, population dynamics and habitat characterization of Mytella guyanensis (Lamarck, 1819 (Mollusca, Bivalvia in the Paraíba do Norte river estuary  

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Full Text Available A survey of Mytellaguyanensis occurrence and population dynamics were performed in the Paraíba do Norte river estuary. The characterization and the influence of temperature, salinity and substrate, as well as the associated fauna and flora on the population were also examined. Mytella guyanensis lives buried in the substrate of the mangrove intertidal zone of the Paraíba do Norte river estuary, from the mouth to 24 km upriver. Average annual density of this bivalve species was 5.2 individuals per m², with a predominantly aggregated distribution. The most frequent size was between 4.5 and 5.5 cm in length. Analysis of the substrate demonstrated the presence of two types of substrates in relation to the percentage of silt and clay and the water content. Besides interfering in the population density, the substrate heterogeneity may be a decisive factor in aggregation. Eight species of crustacean decapods and one bivalve species were identified as associated fauna.A ocorrência de M, guyanensis no estuário do Rio Paraíba do Norte foi mapeada, determinando-se sua presença ao longo dos afluentes e ilhas aí existentes. O estudo da dinâmica da população foi realizado em área protegida da Ilha da Restinga, coletando-se os animais ao longo de 37 transecções. A cada mês foram feitos 60 lançamentos com um delimitador de 0,1 m², sobre uma ou mais transecções. Todo o substrato foi retirado juntamente com os exemplares de M. guyanensis e a fauna associada, até a profundidade de 10 cm. A triagem dos exemplares menores foi feita por peneiramento do substrato. O tipo de substrato foi anotado a cada lançamento. Dois tipos de substrato estão presentes na área: um substrato de tipo consistente, constituido por 89.7% de silte e argila e 10.3% de areia fina e outro de tipo não consistente contendo 74.5% de silte e argila e 25.5% de areia fina. O substrato de tipo não consistente apresenta quantidade de água significativamente maior que o de tipo consistente. Mytella guyanensis vive enterrada no solo numa profundidade máxima de 1,0 cm, sempre envolvida pelos filamentos do bisso. A densidade média anual observada para a espécie foi de 5,2 indivíduos por m²; a distribuição espacial predominante foi do tipo agregado, sofrendo interferência do tipo de substrato presente. Houve preferência de fixação da espécie pelo substrato do tipo consistente. Animais entre 4,5 e 5,5 cm de comprimento ocorrem o ano todo, sendo mais numerosos aqueles com comprimento entre 4,5 e 5,0 cm. A presença de formas jovens foi assinalada em baixa frequência em alguns meses do ano. A salinidade da água estuarina variou de acordo com o regime pluviométrico da região, permanecendo dentro dos níveis de tolerância da espécie. A fauna associada está representada por oito espécies de crustáceos e por uma de molusco bivalve.

Alberto Kioharu Nishida

1995-01-01

307

Ionised silica in the estuary of a river as supply to seawater: Identification and ionization efficiency of silica species by FAB-MS  

Science.gov (United States)

Measurement of the dissolution state of silicic acid is difficult. In river water, silica exists in particle form, but silica particles with a diameter of less than approximately 0.45 ?m are considered as dissolved silica. In seawater, silica exists in two forms: ionic silica and particle silica. In this study, we focused on ionic silica. Using fast atom bombardment mass spectrometry (FAB-MS), the silica species in river water and seawater were detected as ionic forms. Ionic silica forms various chemical species in aquatic solutions, including the monomer ([Si]) and dimer ([Si]). The relative abundances of these species in aquatic solutions depend on the chemical and physical conditions. Silica species such as [Si(OH)2O2Na]- ([monomer-Na+]-), [Si2(OH)5O2]- ([dimer]-), [Si2(OH)4O3Na]-([dimer-Na+]-), [Si4(OH)7O5]- ([cyclic tetramer]-), [Si4(OH)6O6Na]- ([cyclic tetramer-Na+]-), [Si4(OH)9O4]- ([linear tetramer]-) and [Si4(OH)8O5Na]- ([linear tetramer-Na+]-) were directly observed by FAB-MS in river water and seawater. Some of these ionic silica species are expected to serve as "nutrients" for diatoms in seawater. Large silica particles are transported in river water, whereas in estuaries, a large amount of silica is precipitated and a small amount of silica is dissolved as ionic forms in sodium chloride solution. In river water, the concentration of silica was high, but the ionic silica species were hardly ionised by FAB-MS. In seawater, the concentration of silica was low, but the ionic silica species were well ionised. Thus, the ionization efficiency of silica species by FAB-MS indicates the type of silica species. The filtration process of silicic acid and the ionization of silicic acid to dissolve the silica species in seawater, which is an electrolyte (sodium chloride), occur in the estuary of a river. Thus, the estuary of a river plays an important role in the restructuring of silica from particle form to ionic form.

Tanaka, Miho; Takahashi, Kazuya

2013-04-01

308

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

Scientific Electronic Library Online (English)

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

Luciana, Alvarenga; Rosebel Cunha, Nalesso.

309

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

Scientific Electronic Library Online (English)

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

Luciana, Alvarenga; Rosebel Cunha, Nalesso.

2006-01-01

310

Importance of food availability for growth of juvenile southern flounder ( Paralichthys lethostigma) in the Pamlico River Estuary, North Carolina, USA  

Science.gov (United States)

Results presented in an earlier paper showed that differences in temperature and salinity could explain approximately 30% of the variability in growth rates of juvenile southern flounder ( Paralichthys lethostigma) in different creeks of the Pamlico River estuary. In addition, the maximal growth rate was lower than expected from published laboratory results, suggesting food limitation. In the present paper, the obtained mean and maximal growth rates are related to simultaneously collected data on the amount of food available in the creeks. Thirteen different groups of food items were observed in the stomachs of the flounder. Most of the stomachs of flounder collected outside the cages contained only mysids (65 to 75%). Inside the cages, 25 to 45% of the flounder stomachs contained only mysids, while 85 to 100% of the stomachs contained both mysids and other food categories. Individual growth rates of the founder were only significantly related to the number of mysids in the stomachs, and not to any of the other food categories. Stomachs of other fish species mostly showed food categories other than mysids. This indicates that interspecific competition for food did not occur. The four creeks of the cage experiment showed significant differences in abundance of mysids. However, in only one of the two trials the abundance of mysids was significantly related to the observed growth rates. It can be concluded that mysid abundance does not unequivocally explain the variability in growth rates of juvenile southern flounder in low salinity nursery areas of Pamlico Sound, and that the hypothesis of food limiting maximal growth is not supported by the results of this study.

Kamermans, Pauline; Guindon, Kathryn Y.; Miller, John M.

311

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

312

Diversity and distribution of amoA-type nitrifying and nirS-type denitrifying microbial communities in the Yangtze River estuary  

Science.gov (United States)

Coupled nitrification-denitrification plays a critical role in the removal of excess nitrogen, which is chiefly caused by humans, to mitigate estuary and coastal eutrophication. Despite its obvious importance, limited information about the relationships between nitrifying and denitrifying microbial communities in estuaries, and their controlling factors have been documented. We investigated the nitrifying and denitrifying microbial communities in the estuary of turbid subtropical Yangtze River (YRE), the largest river in Asia, by analyzing the ammonia monooxygenase gene amoA, including archaeal and bacterial amoA, and the dissimilatory nitrite reductase gene nirS using clone libraries and quantitative PCR (qPCR). The diversity indices and rarefaction analysis revealed a quite low diversity for both ?-proteobacterial and archaeal amoA genes, but qPCR data showed significantly higher amoA gene copy numbers for archaea than ?-proteobacteria. Compared with the amoA gene, a significantly higher level of diversity but lower gene copy numbers were found for the nirS gene. Nitrification and denitrification rates based on 15N incubation experiments supported gene abundance data as denitrification rates were below detection limit, suggesting lower denitrification than nitrification potential. In general, the abundances of the amoA and nirS genes were significantly higher in the bottom samples than the surface ones, and in the high-turbidity river mouth, were significantly higher in the particle-associated (> 3 ?m) than the free-living (0.2 ~ 3 ?m) communities. Notably, positive correlations between the amoA and nirS gene abundances suggested potential gene-based coupling between nitrification and denitrification, especially for the particle-associated assemblages. Statistical analysis of correlations between the community structure, gene abundances and environmental variables further revealed that dissolved oxygen and total suspended material might be the key factors controlling community spatial structure and regulating nitrification and denitrification potentials in the YRE ecosystem.

Zhang, Y.; Xie, X.; Jiao, N.; Hsiao, S. S.-Y.; Kao, S.-J.

2014-04-01

313

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

Science.gov (United States)

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

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

2009-04-01

314

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

315

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 by a variety of techniques, including elemental (C and N), stable carbon isotopic (? 13C) composition, as well as molecular-level analyses. Total organic carbon (TOC) content was 1.61±1.20% in the upper reach down to 1.00±0.22% in Lingdingyang Bay and to 0.80&...

2010-01-01

316

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 concentratio...

Carvalho, G. P.; Cavalcante, P. R. S.; Castro, A. C. L.; Rojas, M. O. A. I.

2000-01-01

317

Effects of climatic variability on phytoplankton community structure and bloom development in the eutrophic, microtidal, New River Estuary, North Carolina, USA  

Science.gov (United States)

The roles of climatically driven freshwater flow, nutrient loading, and temperature on phytoplankton community biomass and composition were examined along a downstream transect within the New River Estuary, North Carolina from 2007 to 2010. This microtidal system has a history of eutrophication symptoms, including harmful algal blooms. Riverine discharge strongly controlled nutrient loading to the estuary. Except during very high flow conditions, loads were generally assimilated near the head of the estuary and low concentrations of dissolved inorganic nitrogen and phosphate, cyanobacteria to exploit low residual nutrient concentrations, and subsidies to the diatom population via sediment resuspension events. In addition to effects of flow, pico-cyanobacteria and harmful raphidophyte taxa demonstrated positive relationships with temperature. Overall, results demonstrate a strong linkage between the phytoplankton community and two important climatic drivers, flow and temperature. The observed sensitivity of phytoplankton biomass to nutrient loads suggests that load reductions (or increases) are likely to decrease (or increase) total phytoplankton biomass in this system. However, phytoplankton community composition appears to be largely determined by environmental factors other than nutrient loading, particularly temperature, stratification and sediment resuspension.

Hall, Nathan S.; Paerl, Hans W.; Peierls, Benjamin L.; Whipple, Anthony C.; Rossignol, Karen L.

2013-01-01

318

Estuary Live!  

Science.gov (United States)

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

319

Effects of the anthropogenic activities on the morphological evolution of the Modaomen Estuary, Pearl River Delta, China  

Science.gov (United States)

Owing to the intensive human activities, the Modaomen Estuary has been significantly modified since 1950s, which has resulted in considerable changes of hydrodynamics and morphodynamics in the area. In this paper, the effects of the anthropogenic activities on the hydrodynamics and morphological evolution in the estuary at different stages are systematically assessed based on the detailed bathymetric data and field survey. The results show that the human activities have caused the channelization of the enclosed sea area in the Modamen Estuary; fast seaward movement of the mouth bar with high siltation; expansion of the channel volume due to channel deepening. The paper also highlights the main hydrodynamic changes in the estuary, including the rise of the water level; the distinguishing changes of tidal range before and after the 1990s (decrease and increase respectively); as well as the increase of the divided flow ratio. It is found that reclamation is the main factor promoting the transition of nature of the estuary from runoff dominant to runoff and wave dominant, and sand mining activities are mainly to strengthen the tidal dynamic and to low the water level. The results provide useful guidance for better planning of the future developments in the estuary and further research in the area.

Jia, Liang-wen; Pan, Shun-qi; Wu, Chao-yu

2013-12-01

320

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 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

 
 
 
 
321

MOD_FreeSurf2D: a Surface Fluid Flow Simulation Model for Rivers, Streams, and Shallow Estuaries  

Science.gov (United States)

The MOD_FreeSurf2D, Modular Free Surface Flow in Two-Dimensions, computer model simulates free surface fluid flow in streams, rivers, and shallow estuaries under the assumptions of a well-mixed water column, a small water depth to width ratio, and a hydrostatic pressure distribution. The dependent variables in the model are free surface elevation, which provides total water depth, and fluid velocity. Primary advantages of MOD_FreeSurf2D relative to other two-dimensional models are a stable and computationally efficient numerical representation and a transparent representation of wetting and drying of the simulation domain. MOD_FreeSurf2D approximates the depth-averaged, shallow water equations with a finite volume, semi-implicit, semi-Lagrangian numerical representation similar to the TRIM method (Casulli, 1990; Casulli and Cheng, 1992; Casulli, 1999). The semi-implicit, semi-Lagrangian approach is computationally efficient because time steps can exceed the Courant-Friedrich-Lewy (CFL) stability criterion without significant accuracy degradation (Robert, 1982; Casulli, 1990). The rectangular, Arakawa C-grid, finite-volume layout allows flooding and drying in response to changing flow conditions without prior channel specification or closed boundary specification. Open boundary conditions available in MOD_FreeSurf2D are specified flux, specified total water depth, specified velocity, radiation free surface, and radiation velocity. MOD_FreeSurf2D requires initial topography, undisturbed water depth, and Manning's roughness coefficient. MOD_FreeSurf2D simulated results are shown to converge to the semi-empirical solution for a simple straight channel case. Two applications demonstrate the accuracy of MOD_FreeSurf2D. The first application is the evolution of water depth in the dambreak-style flume experiment of Bellos et al. (1992). In this case, MOD_FreeSurf2D accurately simulates the changing water depth in the flume during the experiment and models the wetting of the flume below the dam and the drying of the flume above the dam. The second application is simulation of a reach of the Kootenai River, ID studied by Lipscomb et al. (1998). Detailed 3D spatial measurements of water depth and velocity were numerically integrated and compared to the 2D values produced by MOD_FreeSurf2D. Results indicate that MOD_FreeSurf2D accurately simulates depth-averaged velocity and total water depth on the reach scale. Currently, MOD_FreeSurf2D is a fully vectorized set of custom Matlab functions. References: Bellos, C.V., Soulis, J.V., and Sakkas, J.G., 1992, Experimental Investigation of Two-dimensional Dam-break Induced Flows, Journal of Hydraulic Research, v. 20, p. 47-63. Casulli, V., 1999, A Semi-Implicit Finite Difference Method for Non-Hydrostatic, Free-Surface Flows, International Journal for Numerical Methods in Fluids, v. 30, p. 425-440. Casulli, V., 1990, Semi-implicit Finite Difference Methods for the Two-Dimensional Shallow Water Equations, Journal of Computational Physics, v. 86, p. 56-74. Casulli, V. and Cheng, R.T., 1992, Semi-implicit Finite Difference Methods for Three-Dimensional Shallow Water Flow, International Journal for Numerical Methods in Fluids, v. 15, p. 629-648. Lipscomb, S.W., Berenbrock, C., and Doyle, J.D., 1997, Spatial Distribution of Stream Velocities for the Kootenai River Near Bonners Ferry, ID, June 1997. U.S. Geological Survey Open File Report 97-830, 174 p. Robert, A., 1982, A Semi-Lagrangian and Semi-Implicit Numerical Integration Scheme for the Primitive Meteorological Equations, Journal of the Meteorological Society of Japan, v.60, n. 1. p. 319-325.

Martin, N.; Gorelick, S. M.

2003-12-01

322

Determination of water ages and flushing rates using short-lived radium isotopes in large estuarine system, the Yangtze River Estuary, China  

Science.gov (United States)

We investigated the spatial and temporal distribution of naturally-occurring short-lived radium isotopes (224Ra, t1/2 = 3.6 d and 223Ra, t1/2 = 11 d) to examine coastal water mixing dynamics of the third world largest estuary, Yangtze River Estuary (YRE) during two field trips in April 2010 and May 2011. Distributions of the 224Ra/223Ra activity ratios within the YRE area were used to calculate apparent estuarine water ages. Field-derived results were then compared to hydrodynamic assessments obtained by a Lagrangian particle tracking simulation experiment performed using the Princeton Ocean Model (POM). Water ages obtained via both geotracers and particle tracking agree very well. During both field trips an anomalously "younger" water mass (low salinity and higher radium activities) was observed at about 90-170 km offshore distance from the mouth of the river, suggesting an additional terrestrial water source influenced this area. The temporal distribution of the radium isotopes indicated a semi-diurnal tidal pattern in the YRE with relatively constant isotopic composition of less than a 20% variation during our observations. An integrated water flushing rate based on our observations (excluding the additional anomalous source area) was 8.4 km day-1.

Xu, Bo-Chao; Dimova, Natasha T.; Zhao, Liang; Jiang, Xue-Yan; Yu, Zhi-Gang

2013-04-01

323

Population structure, size at maturity and condition of sardine, Sardina pilchardus (Walb., 1792), in the nursery ground of the eastern Adriatic Sea (Krka River Estuary, Croatia)  

Science.gov (United States)

A total of 1125 specimens of sardine, Sardina pilchardus, ranging in total length from 4.9 to 12.5 cm (mean 8.31 ± 1.41 cm) and in weights between 1.02 g and 11.18 g (mean 4.40 ± 1.87 g) were randomly sampled using a beach seine from the Krka River estuary. Samples were collected monthly according to their occurrence in this area from October to February during 2002/03, 2003/04 and 2004/05, which is during the spawning period of this species. Monthly fluctuations in the length frequency distributions of sardine were observed during that time. The length-weight relationship of all sardine specimens was described by the equation: W=0.007L( r2 = 0.9626); and the isometric nature of relative growth was established ( t = -5.1495; p < 0.05). According to the allometric condition factor Ka, sardine specimens were in better somatic condition at the beginning of their appearance (spawning period) in the Krka River estuary. The length at which 50% of sardines were mature ( L50) was calculated to be 7.9 cm.

Sinov?i?, Gorenka; Ke?, Vanja ?ikeš; Zorica, Barbara

2008-03-01

324

Folk classification of the crabs and swimming crabs (Crustacea – Brachyura of the Mamanguape river estuary, Northeastern – Brazil  

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Full Text Available Abstract Background Folk taxonomy is a sub-area of ethnobiology that study the way of how traditional communities classify, identify and name their natural resources. The work present was undertaken in two traditional communities (Barra de Mamanguape and Tramataia. The objective of this study was investigate the ethnobiological classification of the local crabs and swimming crabs used by the crustaceous gatherers of the Mamanguape River Estuary (MRE, Paraíba State, Brazil. Methods The methodology used here involved a combination of qualitative methods (open interviews, semi-structured interviews, direct observations, guided tours, surveys, and interviews in synchronic and diachronic situations that crossed-checked and repeated identifications and quantitative methods (Venn diagram. A total of 32 men and women were interviewed in the two communities. Specimens of the local crustaceans were collected and identified by the harvesters themselves, subsequently fixed in formalin, conserved in 70% ethyl alcohol, identified using appropriate specialized literature, and then deposited in the laboratory of the Zoology Department of the University State of Paraiba. Results The crustaceous gatherers we studied were observed to group crustaceans according to their similarities and differences, producing a hierarchical classification system containing four levels of decreasing taxonomic order: unique beginner, life-form, generic, and specific. A sequential and/or semantic system classification system that is used to classify the ontogeny of the female swimming crab was also identified. Of the nine folk generics identified, 44.5% were monotypic. 55.5% were polytypic and were subdivided into 15 folk specifics. An identification key was elaborated with the data obtained about the folk polytypics generics. Conclusion The detailed knowledge concerning the crabs and swimming crabs revealed by the MRE crustaceous gatherers demonstrates that these people detain a vast knowledge concerning these marine resources. This local knowledge provides a rich but little-known source of information that will aid future ecological and/or zoological studies in the region that will be indispensable for producing management plans to help guarantee the sustainability of these local natural resources.

da S Q Bezerra Dandara

2009-08-01

325

Evaluating sedimentation rates in the estuary and shelf region of the Paraíba do Sul River, Southeastern Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este estudo é uma avaliação das taxas de sedimentação na região do delta do Rio Paraíba do Sul e sua correlação com a forte erosão que ocorre em Atafona, Rio de Janeiro. Os resultados obtidos são baseados 14 testemunhos de sedimentos, com um total de aproximadamente 540 amostras, coletados em janeir [...] o de 2010 e fevereiro de 2011. Os inventários de 210Pb nos pontos de amostragem ao sul da desembocadura do Rio Paraíba do Sul foram maiores do que aqueles observados para os pontos de coleta na região norte e central, o que sugere que os sedimentos são transportados ao longo da costa com as correntes nesta direção. Os resultados da datação 210Pb foram validados com base na variação de concentração elementar ao longo de dois dos testemunhos. Concentrações de Cd e Zn aumentaram significativamente em 1982 e atingindo valores máximos (0,5 mg kg-1 e 139 mg kg-1, respectivamente) em 1984. Estes máximos correspondem ao acidente da indústria Cia Paraibuna de Metais, que ocorreu em 1982. Abstract in english This study aims to evaluate sedimentation rates in the Paraíba do Sul estuary and its shelf regions. These sedimentation rates were correlated with strong erosion occurring in Atafona, Rio de Janeiro. The results were based on four transects, from which 14 sediment cores with approximately 540 sedim [...] ent samples were collected in January 2010 and February 2011. At sampling points south of the Paraíba do Sul River (PSR) mouth, 210Pb inventories were higher than those at the northern and central sampling locations, suggesting that sediment is transported southward by the alongshore current. The 210Pb dating results were validated based on the elemental concentration variation throughout two of the sediment cores. Heavy metal concentrations, such as Cd and Zn, increased significantly in 1982 and reached maximum values (0.5 mg kg-1 and 139 mg kg-1, respectively) in 1984. These maxima correspond to the Cia Paraibuna de Metais industry accident, which occurred in 1982.

Cristiana V. A., Wanderley; José Marcus, Godoy; Maria Luiza D. P., Godoy; Carlos Eduardo, Rezende; Luiz D., Lacerda; Isabel, Moreira; Zenildo L., Carvalho.

326

Evaluating sedimentation rates in the estuary and shelf region of the Paraíba do Sul River, Southeastern Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este estudo é uma avaliação das taxas de sedimentação na região do delta do Rio Paraíba do Sul e sua correlação com a forte erosão que ocorre em Atafona, Rio de Janeiro. Os resultados obtidos são baseados 14 testemunhos de sedimentos, com um total de aproximadamente 540 amostras, coletados em janeir [...] o de 2010 e fevereiro de 2011. Os inventários de 210Pb nos pontos de amostragem ao sul da desembocadura do Rio Paraíba do Sul foram maiores do que aqueles observados para os pontos de coleta na região norte e central, o que sugere que os sedimentos são transportados ao longo da costa com as correntes nesta direção. Os resultados da datação 210Pb foram validados com base na variação de concentração elementar ao longo de dois dos testemunhos. Concentrações de Cd e Zn aumentaram significativamente em 1982 e atingindo valores máximos (0,5 mg kg-1 e 139 mg kg-1, respectivamente) em 1984. Estes máximos correspondem ao acidente da indústria Cia Paraibuna de Metais, que ocorreu em 1982. Abstract in english This study aims to evaluate sedimentation rates in the Paraíba do Sul estuary and its shelf regions. These sedimentation rates were correlated with strong erosion occurring in Atafona, Rio de Janeiro. The results were based on four transects, from which 14 sediment cores with approximately 540 sedim [...] ent samples were collected in January 2010 and February 2011. At sampling points south of the Paraíba do Sul River (PSR) mouth, 210Pb inventories were higher than those at the northern and central sampling locations, suggesting that sediment is transported southward by the alongshore current. The 210Pb dating results were validated based on the elemental concentration variation throughout two of the sediment cores. Heavy metal concentrations, such as Cd and Zn, increased significantly in 1982 and reached maximum values (0.5 mg kg-1 and 139 mg kg-1, respectively) in 1984. These maxima correspond to the Cia Paraibuna de Metais industry accident, which occurred in 1982.

Cristiana V. A., Wanderley; José Marcus, Godoy; Maria Luiza D. P., Godoy; Carlos Eduardo, Rezende; Luiz D., Lacerda; Isabel, Moreira; Zenildo L., Carvalho.

2014-01-01

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Experimental simulation of antimony and chromium forms of residence in the water of the Syr-Darya river, estuary and in the water of the Aral Sea usng sup(124)Sbsup((5)) and sup(51)Crsup((6)) radionuclides  

International Nuclear Information System (INIS)

Using the compbination of radiochemical methods, the physicochemical state of sup(124)Sbsup((5)) and sup(51)Crsup((6)) in the waters of the Syr-Darya river, estuary and the Aral Sea is studied. It is ascertained, that in the river, estuary and Aral Sea water the main amount of sup(124)Sbsup((5)) and sup(51)Crsup((6)) migrates in the form of negatively charged anions Sb(OH)6- and CrOsub(4)sup(2-). However, in the Aral Sea estuary the formation of finely dispersed colloid forms of chromium (6) and antimony (5) is possible due to their sorption on vegetable cellulose, modified by arid water components. There is also a possibility of appearance of antimony (5) sorptional forms on other sorbents in a narrow range of the Aral Sea water salinity

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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 SciELO Chile | Language: Spanish 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 e [...] s poco conocida. Mediante mediciones hidrográficas de temperatura y salinidad tomadas durante un ciclo estacional anual y el análisis de sus principales forzantes (marea, 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) 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.

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

329

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 SciELO Chile | Language: Spanish 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 e [...] s poco conocida. Mediante mediciones hidrográficas de temperatura y salinidad tomadas durante un ciclo estacional anual y el análisis de sus principales forzantes (marea, 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<