WorldWideScience
 
 
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

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

Science.gov (United States)

The distribution of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) were studied in sediments collected from mangrove forest, forest fringe and adjacent mudflat in the Zhangjiang Estuary, China. The aim was to examine the spatial distribution of AVS and SEM in sediments of the Estuary and determine the influence of mangrove trees on AVS and SEM concentrations in the sediments. The results indicated that AVS concentrations in forest sediments were significantly lower than those in mudflat sediments. There was a significant positive correlation between AVS values and moisture contents in forest sediments, while LOI played an important role in AVS concentrations of mudflat sediments. In the forest sediment core, the peak value of AVS appeared deeper in the sediment profile compared to it appeared in the mudflat core. The distribution of SEM showed different trends from that of AVS, and potential toxicity existed in the upriver forest sediments. PMID:20434182

Jingchun, Liu; Chongling, Yan; Spencer, Kate L; Ruifeng, Zhang; Haoliang, Lu

2010-08-01

3

Estuaries  

Science.gov (United States)

Estuaries are bodies of water and their surrounding coastal wetlands typically found where rivers meet the sea. Estuaries harbor unique plant and animal communities because their waters are brackish--a mixture of fresh water draining from the land and salty seawater.Estuaries are some of the most productive ecosystems in the world. Many animal species rely on estuaries for food, places to breed, and migration stopovers. Human communities also rely on estuaries for food, recreation, jobs, and coastal protection.Of the 32 largest cities in the world, 22 are located on estuaries (e.g., New Orleans, London, etc). Not surprisingly, human activities have led to the decline in the health of estuaries, making them one of the most threatened ecosystems on the Earth. NOAA's National Estuarine Research Reserve System in partnership with coastal states monitors the health of estuaries and helps communities manage their coastal resources.

Educator, Laura K.; National Science Teachers Association (NSTA); Review, Steve W.

2005-04-01

4

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

5

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

Energy Technology Data Exchange (ETDEWEB)

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

Dion, E.P.

1983-01-01

6

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

1983-01-01

7

Continuous resistivity profiling data from the Corsica River Estuary, Maryland  

Science.gov (United States)

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

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

2011-01-01

8

Trace elements distribution in bottom sediments from Amazon River estuary  

International Nuclear Information System (INIS)

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

1994-09-02

9

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.

Hosking, Stephen.

10

Numerical Modeling of Groundwater Seepages to River/Estuary Systems  

Science.gov (United States)

An integrated model is developed to simulate seepages from groundwater to river/estuary systems. The model includes a one-dimensional flow module for river/estuary networks and a two-dimensional groundwater flow module for subsurface media. The former was adapted from the one-dimensional module in a watershed model, WASH123D, and the latter was obtained by modifying an existing vertically averaged groundwater flow model, FEWA. The modeling system was applied to St. Lucie Estuary (SLE) to estimate seepages. The seepage measurement data on four seepage-meter transect sites in St. Lucie River were calibrated with results of the computational model. In addition, the computational model results were compared with those of analytical model on seepage meter sites. The model was then applied to predict the groundwater seepage flux into SLE due to interaction between aquifer and river domain during multiple-year period. Seven types of statistics of calibration indicated that the numerical models have improved over the analytical models. Therefore, it should be expected that the forty-year predictions are an improvement over the previous analytical calculations.

Yeh, G.; Lee, J.; Hu, G.; Sun, D.

2009-12-01

11

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 cope...

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

2012-01-01

12

Environmental restoration of the Guadiaro river estuary, Cadiz (Spain)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

During 1998, the Spanish Ministry of Environmental Protection has developed the restoration of the Guadiaro estuary, near the Strait of Gibraltar, through the Coastal General Directorate. The main environmental problems, amongst others, detected at the area were a high eutrophication level of the estuarine waters and fish mortality mainly due to the low summer river effluent, the urban sewage inputs and no tidal renovation caused by the blockage of the sand bar at the mouth...

La Casa, A?ngel; Gomez-pina, Gregorio; Acha Martin, Antonio; Mun?oz-perez, Juan J.

2000-01-01

13

Distribution of endocrine disruptors in the Mondego River estuary, Portugal  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2008-01-01

14

Be isotopes in rivers/estuaries and their oceanic budgets  

International Nuclear Information System (INIS)

10Be and 9Be have been determined in several North American rivers and in the estuaries of San Francisco Bay and the Pearl River (China). The average fluvial concentration of dissolved 10Be in the rivers is 3220±1960 (1?) atoms/g, almost an order of magnitude higher than the observed estuarine values and slightly higher than the 10Be concentration in the ocean (? 1700 atoms/g). For dissolved 9Be, a similar order-of-magnitude drop in concentration also occurs in going from rivers (750±740 pM) to estuaries (80-140 pM). However, in contrast to the 10Be situation, there appears another order-of-magnitude drop from estuaries to the ocean, which has 9Be concentrations of 5-30 pM. In spite of the wide range of concentrations for both isotopes in river and estuarine waters, 10Be/9Be ratios range mostly from 2 to 12x10-9, with a median value of 7x10-9 (atom/atom), and are much lower than the seawater ratio of ?10-7. In the rivers studied, a given volume of water contains roughly equal amounts of particulate and dissovled 10Be. The 10Be concentration in particulate matter ranges from 2x106 to 1x109 atoms/g-particulate with a median value of about 5x107 atoms/g-particulate. A two-box model calculation shows that coastal regions play an important role in the removal of Be isotopes from the ocean and that eolian dusts may be the chief source of oceanic 9Be. Because of the marginal removal effect, the overall oceanic residence time of Be should be shorter than the residence time of 500-1200 yr estimated for the open ocean. (orig.)

1991-01-01

15

Oil spill response planning on the Columbia river estuary  

International Nuclear Information System (INIS)

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

1993-04-01

16

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

Energy Technology Data Exchange (ETDEWEB)

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

Dion, E.P.

1983-01-01

17

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

International Nuclear Information System (INIS)

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

1983-01-01

18

Local flows in the Quequen Grande River Estuary, Argentina  

International Nuclear Information System (INIS)

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

2009-05-01

19

Sediment transport and morphodynamics of the Douro River estuary  

Science.gov (United States)

A combination of dredging data, hydrographic surveys and numerical modelling has been used to assess morphological change and sediment transport in the Douro River estuary. The system is dominated by sand- and gravel-sized sediments and confined by resistant rock types. The evolution of the bed in the last 20 years has been strongly influenced by the opening of a navigation channel. According to the data available to date, the average maintenance dredging volume has been of the order of 0.4 × 106 m3 year-1. Comparisons of hydrographic surveys reveal a rate of volume loss of the same magnitude. Apparently, maintenance dredging mainly involves local material, transported into the channel from shallower areas of the estuary. The results of numerical modelling indicate that the sediment transport capacity due to tidal currents is very limited. River flood events increase the transport capacity by several orders of magnitude, thus playing a critical role in sediment redistribution and supply to the coast. The average sediment transport capacity is estimated to be of the order of 0.1 × 106 m3 year-1 in most of the estuary and 0.5 × 106 m3 year-1 at the inlet, with a large uncertainty. It is concluded that, if morphological stability is set as an environmental objective, the dredged material should not be removed from the system but rather be used to nourish the estuarine beaches and the barrier spit.

Portela, Luís Ivens

2008-04-01

20

Be isotopes in rivers/estuaries and their oceanic budgets  

Energy Technology Data Exchange (ETDEWEB)

{sup 10}Be and {sup 9}Be have been determined in several North American rivers and in the estuaries of San Francisco Bay and the Pearl River (China). The average fluvial concentration of dissolved {sup 10}Be in the rivers is 3220{+-}1960 (1{sigma}) atoms/g, almost an order of magnitude higher than the observed estuarine values and slightly higher than the {sup 10}Be concentration in the ocean ({approx equal} 1700 atoms/g). For dissolved {sup 9}Be, a similar order-of-magnitude drop in concentration also occurs in going from rivers (750{+-}740 pM) to estuaries (80-140 pM). However, in contrast to the {sup 10}Be situation, there appears another order-of-magnitude drop from estuaries to the ocean, which has {sup 9}Be concentrations of 5-30 pM. In spite of the wide range of concentrations for both isotopes in river and estuarine waters, {sup 10}Be/{sup 9}Be ratios range mostly from 2 to 12x10{sup -9}, with a median value of 7x10{sup -9} (atom/atom), and are much lower than the seawater ratio of {proportional to}10{sup -7}. In the rivers studied, a given volume of water contains roughly equal amounts of particulate and dissovled {sup 10}Be. The {sup 10}Be concentration in particulate matter ranges from 2x10{sup 6} to 1x10{sup 9} atoms/g-particulate with a median value of about 5x10{sup 7} atoms/g-particulate. A two-box model calculation shows that coastal regions play an important role in the removal of Be isotopes from the ocean and that eolian dusts may be the chief source of oceanic {sup 9}Be. Because of the marginal removal effect, the overall oceanic residence time of Be should be shorter than the residence time of 500-1200 yr estimated for the open ocean. (orig.).

Kusakabe, M.; Ku, T.L.; Cusimano, G.L.; Nakaya, S. (Dept. of Geological Sciences, Univ. of Southern California, Los Angeles, CA (USA)); Southon, J.R.; Vogel, J.S.; Nelson, D.E. (Archaeology Dept., Simon Fraser Univ., Burnaby (Canada)); Liu Shao (South China Sea Inst. of Oceanology, Academia Sinica, Guangzhou, GD (China))

1991-03-01

 
 
 
 
21

Desorption of Ba and 226Ra from river-borne sediments in the Hudson estuary  

International Nuclear Information System (INIS)

The pronounced desorption of Ba and 226Ra from river-borne sediments in the Hudson estuary can be explained quantitatively by the drastic decrease in the distribution coefficients of both elements from a fresh to a salty water medium. The desorption in estuaries can augment, at least, the total global river fluxes of dissolved Ba and 226Ra by one and nine times, respectively. The desorption flux of 226Ra from estuaries accounts for 17-43% of the total 226Ra flux from coastal sediments. Two mass balance models depicting mixing and adsorption-desorption processes in estuaries are discussed. (Auth.)

1979-01-01

22

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

23

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Highly mutagenic compounds such as some PAHs have been identified in surface waters and sediments of the Seine river estuary. Suspended particulate matter (SPM) represents a dynamic medium that may contribute to the exposure of aquatic organisms to toxic compounds in the water column of the estuary. In order to investigate major sources of mutagenic contaminants along the estuary, water samples were taken at 25 in downstream of the outlet of an industrial wastewater-treatment plant (WWTP). SP...

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

2012-01-01

24

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-02-05

25

Comparison of common persistent organic pollutants (POPs) in flounder (Platichthys flesus) from the Vistula (Poland) and Douro (Portugal) River estuaries.  

Science.gov (United States)

Groups of flounder (Platichthys flesus) females were collected in 2011 from the Vistula River and the Duoro River estuaries and corresponding reference sites in the southern Baltic Sea and Portuguese coast of the Atlantic Ocean to measure and compare the levels and profiles of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). The estuaries' sediments were also investigated. Several differences were found in the POPs between the estuaries and between the two marine regions, which were highlighted by PCA. The Vistula River estuary POPs, significantly higher than in the Douro River estuary, were dominated by DDTs followed by PCBs. PBDEs levels, indifferent between the estuaries, were relatively low. The POP levels in flounder and sediment evaluated against environmental assessment criteria (EACs) indicated that none of the measured contaminants for which EAC had been established exceeded the criterion, except for CB-118 in flounder from the Vistula River estuary. PMID:24492155

Waszak, Ilona; Dabrowska, Henryka; Komar-Szymczak, Katarzyna

2014-04-15

26

Changes in Epipelic Diatom Diversity from the Savannah River Estuary  

Directory of Open Access Journals (Sweden)

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

Joseph N. Dominy Jr.

2013-02-01

27

Climate change drives warming in the Hudson River Estuary, New York (USA).  

Science.gov (United States)

Estuaries may be subject to warming due to global climate change but few studies have considered the drivers or seasonality of warming empirically. We analyzed temperature trends and rates of temperature change over time for the Hudson River estuary using long-term data, mainly from daily measures taken at the Poughkeepsie Water Treatment Facility. This temperature record is among the longest in the world for a river or estuary. The Hudson River has warmed 0.945 °C since 1946. Many of the warmest years in the record occurred in the last 16 years. A seasonal analysis of trends indicated significant warming for the months of April through August. The warming of the Hudson is primarily related to increasing air temperature. Increasing freshwater discharge into the estuary has not mitigated the warming trend. PMID:21720614

Seekell, David A; Pace, Michael L

2011-08-01

28

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

Energy Technology Data Exchange (ETDEWEB)

A systematic sampling survey was carried out in the Zaire (Congo) river and estuary during November 1976 and May 1978. Dissolved /sup 238/U and /sup 234/U 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 /sup 238/U in world rivers are well correlated with total dissolved solids. This correlation permits a reassessment of /sup 238/U concentration in rivers flowing to the ocean resulting in a world wide estimate of 0.24 ..mu..g/l. The dissolved river input of /sup 238/U to the ocean is comparable with output through the main sink processes.

Figueres, G.; Martin, J.M.; Thomas, A.J. (Ecole Normale Superieure, Paris (France))

1982-04-01

29

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 "2"3"8U and "2"3"4U 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 "2"3"8U in world rivers are well correlated with total dissolved solids. This correlation permits a reassessment of "2"3"8U concentration in rivers flowing to the ocean resulting in a world wide estimate of 0.24 ?g/l. The dissolved river input of "2"3"8U to the ocean is comparable with output through the main sink processes

1982-01-01

30

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

31

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

Directory of Open Access Journals (Sweden)

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

Regla Duthit Somoza

2011-04-01

32

River discharge, sediment transport and exchange in the Tana Estuary, Kenya  

Science.gov (United States)

This study focuses on sediment transport and exchange dynamics in the 27 km 2 Tana Estuary located at Kipini in the north Kenya coast. The estuary is drained by the Tana River, which contributes more than 50% of the total river discharges into the Kenyan sector of the Indian Ocean. The study involved measurement of river discharges, estuarine flood-ebb tidal discharges, total and particulate organic suspended sediment concentrations (TSSC, POSC) and fluxes, tidal water elevation, current velocities, temperature and salinity. The study was conducted between February 2001 and November 2003. The results of the study showed that the Tana River discharge ranged between 60 and 750 m 3 s -1. The maximum river discharges during the Southeast and Northeast monsoons were 750 and 350 m 3 s -1, respectively. The peak river discharges occurred in May and November. The total daily sediment load of the Tana River varied from 2796 tons day -1 during the dry season to 24,322 tons day -1 during the rainy season. The annual total sediment load is 6.8 × 10 6 tons yr -1, which is, however, smaller than that before the damming of the river in the Upper Tana Basin. Because of river discharge and occurrence of a wide mangrove wetland, the estuary is mainly ebb tide dominant. The peak ebb tide currents (0.87 m s -1) were 30% larger than the peak flood tide currents (0.65 m s -1). During spring tide, the estuary was partially well mixed. However, in neap tide, the estuary was stratified in the middle zone. The turbidity maximum zone with TSSC > 1.5 g l -1 was generated in spring tide by wave stirring of frontwater zone bed sediments and trapping of fine sediments at the toe of the salt wedge. The peak TSSC ranging from 1.5 to 5.0 g l -1 occurred at low tide due to river supply of sediment and resuspension of channel bed sediments by wind waves, particularly at the last stages of ebb tide and early stages of flood tide. Due to the influx of oceanic water into the estuary at flood tide TSSC decreased to <0.2 g l -1 at high tide in the frontwater zone and was larger in the backwater zones of the estuary. The estuary exports sediments at a rate ranging from 0.02 to 0.08 kg m -2 tidal cycle -1. The net export of sediments causes a net denudation of the estuary at a rate ranging from 0.08 to 0.04 mm tidal cycle -1.

Kitheka, J. U.; Obiero, M.; Nthenge, P.

2005-05-01

33

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

34

Electrochemical determination of dissolved uranium in Krka River estuary.  

Science.gov (United States)

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

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

2001-06-01

35

Proceedings of the Columbia River Estuary Conference on Ecosystem Restoration.  

Energy Technology Data Exchange (ETDEWEB)

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

U.S. Bonneville Power Administration

2008-08-01

36

Sediment transport due to extreme events: The Hudson River estuary after tropical storms Irene and Lee  

Science.gov (United States)

Storms Irene and Lee in 2011 produced intense precipitation and flooding in the U.S. Northeast, including the Hudson River watershed. Sediment input to the Hudson River was approximately 2.7 megaton, about 5 times the long-term annual average. Rather than the common assumption that sediment is predominantly trapped in the estuary, observations and model results indicate that approximately two thirds of the new sediment remained trapped in the tidal freshwater river more than 1 month after the storms and only about one fifth of the new sediment reached the saline estuary. High sediment concentrations were observed in the estuary, but the model results suggest that this was predominantly due to remobilization of bed sediment. Spatially localized deposits of new and remobilized sediment were consistent with longer term depositional records. The results indicate that tidal rivers can intercept (at least temporarily) delivery of terrigenous sediment to the marine environment during major flow events.

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

2013-10-01

37

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

Directory of Open Access Journals (Sweden)

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

38

75 FR 17382 - Small Takes of Marine Mammals Incidental to Specified Activities; Russian River Estuary Water...  

Science.gov (United States)

...Activities; Russian River Estuary Water Level Management Activities...creating the lagoon in terms of water quality/pollution and its...pollutants in the river and ``We wonder how toxicity might accumulate...and extensive monitoring of water quality conditions...

2010-04-06

39

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

Science.gov (United States)

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

Ren, Jie; Wu, Jiaxue

2014-07-01

40

Man-made radionuclides and sedimentation in the Hudson River Estuary  

International Nuclear Information System (INIS)

Recently deposited fine-grained sediments in the Hudson River estuary contain radionuclides from global fallout produced by atmospheric bomb tests as well as from low-level releases of a local nuclear reactor. Accumulation rates of these nuclides are dependent on rates of sediment deposition and vary with location in the estuary by more than two orders of magnitude. Within the Hudson estuary, New York harbor is currently the zone of most rapid deposition of sediments containing radionuclides, some of which were released from a nuclear reactor about 60 kilometers upstream of the harbor

1976-10-08

 
 
 
 
41

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present work was carried out to verify the occurrence and distribution of Cymbasoma longispinosum Bourne, 1890 in a tropical Amazon estuary from North Brazil. Samplings were performed bimonthly from July/2003 to July/2004 at two different transects (Muriá and Curuçá rivers) situated along the Curuçá estuary (Pará, North Brazil). Samples were collected during neap tides via gentle (1 to 1.5 knots) 200 ?m-mesh net tows from a small boat. Additional subsurface water samples were c...

Leite, Nata?lia R.; Pereira, Luci C. C.; Fernando Abrunhosa; Pires, Marcus A. B.; Da Costa, Rauqui?rio M.

2010-01-01

42

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

Energy Technology Data Exchange (ETDEWEB)

Measurements of /sup 226/Ra and /sup 228/Ra 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 /sup 226/Ra and approximately 2.6% of the /sup 228/Ra 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 /sup 226/Ra concentration and quadruple the estuarine /sup 228/Ra concentration above that caused by the dissolved and desorbed river components alone.

Key, R.M.; Sarmiento, J.L.; Stallard, R.F.; Moore, W.S.

1985-07-20

43

PREDICTION OF TSUNAMI PROPAGATION IN THE PEARL RIVER ESTUARY  

Directory of Open Access Journals (Sweden)

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

Sun J. S.

2009-01-01

44

Numerical simulation of the transport and diffusion of dissolved pollutants in the changjiang (Yangtze) river estuary  

Science.gov (United States)

Based on a coupled hydrodynamic-ecological model for regional and shelf seas (COHERENS), a three-dimensional baroclinic model for the Changjiang (Yangtze) River estuary and the adjacent sea area was established using the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. In the study, changing-grid technology and the “dry-wet” method were designed to deal with the moving boundary. The minimum water depth limit condition was introduced for numerical simulation stability and to avoid producing negative depths in the shallow water areas. Using the Eulerian transport approaches included in COHERENS for the advection and dispersion of dissolved pollutants, numerical simulation of dissolved pollutant transport and diffusion in the Changjiang River estuary were carried out. The mass centre track of dissolved pollutants released from outlets in the south branch of the Changjiang River estuary water course has the characteristic of reverse current motion in the inner water course and clockwise motion offshore. In the transition area, water transport is a combination of the two types of motion. In a sewage-discharge numerical experiment, it is found that there are mainly two kinds of pollution distribution forms: one is a single nuclear structure and the other is a double nuclear (dinuclear) structure in the turbid zone of the Changjiang River estuary. The rate of expansion of the dissolved pollutant distribution decreased gradually. The results of the numerical experiment indicate that the maximum turbid zone of the Changjiang River estuary is also the zone enriched with pollutants. Backward pollutant flow occurs in the north branch of the estuary, which is similar to the backward salt water flow, and the backward flow of pollutants released upstream is more obvious.

Wu, De'an; Yan, Yixin

2010-05-01

45

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

46

Variations of turbulent flow with river discharge in the Altamaha River Estuary, Georgia  

Science.gov (United States)

Turbulent flow characteristics under two significantly different river discharge periods were studied in the Altamaha River Estuary, Georgia, using a variety of moored instrumentation, combined with detailed water column profiling from an anchored vessel. Estimates of the Reynolds stress, shear production (P), and dissipation rate (?) were derived and compared for the two contrasting river conditions which essentially characterized the estuary as weakly stratified during low discharge (2001) and partially mixed during high discharge (2003). Wave effects were removed from the measurement of turbulent kinetic energy (TKE) using a linear filtration method and a -5/3 slope was fit for an indirect measurement of ?. We suggest two possible mechanisms for observed flood/ebb asymmetries in the shear production of energy: wave-induced bottom roughness change or the competing effects of the barotropic and baroclinic pressure gradients. For 2001 the buoyancy flux was estimated by calculating the dissipation of temperature variance from rapidly sampled temperature time series over two different tidal cycles. The mixing efficiency ? approached 0.25 but was on average 0.05. The mixing rate depended on the flow and stratification with highest values of 200 cm2/s during maximum flow and weakest stratification and lowest values of 0.1 cm2/s during low flow and greater stratification. A balance of production and dissipation of energy was achieved only during ebb tide in 2001, implying that turbulent transport of TKE maybe a consideration since buoyancy dissipation is too small for 2001 and would only enhance the imbalance further in 2003 because of strong stratification that exists during the flood and ebb tide.

di Iorio, Daniela; Kang, Ki Ryong

2007-05-01

47

A Proposal for Impact Evaluation of the Diversion of the Acheloos River, on the Acheloos Estuary in Western Greece  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper the study of the hydrodynamic circulation at the Acheloos’ river estuary, in Western Greece, is proposed as a complementary approach for evaluating the environmental impacts, during river’s diversion to the Thessaly plain. Up to date, the environmental studies have been restricted only to the upper part of Acheloos river, including mainly hydrologic factors for addressing to the problem. Based on the assumption that the Acheloos diversion project is expected to modify runoff patterns at the lower part of the delta, reducing the ecological flow into the estuary, a hydrodynamic tool is required to quantify the impacts from this ambitious project. More specifically, the application of a hydrodynamic model is required in order to incorporate all thephysical factors that affect the hydrodynamic processes in the estuary, including effects of fresh water reduction scenarios to the overall hydrodynamic diet of the estuary, before and after the diversion project. This hydrodynamic approach will contribute towards a detailed understanding of the estuary’s ecosystem, quantifying the river’s diversion effects at the lower estuary’s environment.

NIKOLAOS TH. FOURNIOTIS

2012-04-01

48

Continuous Resistivity Profiling Data from the Upper Neuse River Estuary, North Carolina, 2004-2005  

Science.gov (United States)

Introduction: The Neuse River Estuary in North Carolina has suffered impacts of eutrophication in recent years. As part of a larger project to better constrain nutrient budgets in the estuary, field investigations were performed to study occurrence and discharge of fresh and brackish ground water and nutrients beneath the estuary itself (fig. 1). A Continuous Resistivity Profiling (CRP) system (Manheim and others, 2004) was used to map the depth of the freshwater-saltwater interface (FSI) in sub-estuarine groundwater. This study area serves as a typological representation of a submarine groundwater environment characteristic of a shallow estuary in a wide coastal plain that has not experienced glaciation. Similar settings extend from New Jersey to Georgia, and along the Gulf of Mexico in the U.S. This report archives 29 lines of data collected during 2004 and 2005 surveys representing almost 210 km of survey lines. These data are further explained in the Data Processing section of the report and previews available of the processed data are available. Eutrophication background -- The Neuse River Estuary suffers from frequent summer fish kills, especially of menhaden, attributed directly or indirectly to natural and anthropogenic eutrophication. Some evidence indicates that these events have become more frequent in recent years. An increasing excess of nutrients is likely derived from accelerating agricultural and residential development of the watershed over the last few decades. Impacts have included declines in dissolved oxygen in stratified estuary water due to consumption by decaying algal biomass, as well as blooms of the toxic dinoflagellate, Pfiesteria piscicida (Burkholder and others, 2005; but see Drgon and others, 2005). Several groups have attempted to develop well-constrained nutrient budgets for the estuary (e.g., Christian and Thomas 2003), and typically have used estimates of direct groundwater delivery in the range of 5% of the total nutrient load. None of the estimates, however, has incorporated specific field measurements in the estuary to determine the actual contribution from direct groundwater discharge. Particular geological features of the estuary suggest that it may receive substantial direct discharge. Background on submarine groundwater discharge -- Contributions of groundwater to flow in rivers have historically been estimated using hydrograph separation (e.g., Sloto and Crouse 1996), but no similar method exists for estuaries. Most efforts have relied on flow modeling based on extrapolation of onshore data on recharge and groundwater flow velocities into the offshore, often assuming that most discharge occurs within a few meters of the shore. Radioisotopic tracer techniques have recently been developed to permit estimation of direct submarine groundwater discharge (SGD) to estuaries and coastal embayments. These approaches can be useful for calculating SGD for regional budgets, and can also be used to broadly identify discharge hotspots (Burnett and Dulaiova 2003; Crusius and others, 2004, 2005a, 2005b). They do not, however, provide subsurface information on the geological controls on the occurrence of freshened groundwater beneath brackish to saline surface water and the style of discharge (i.e., focused vs. diffuse). Geographic and geologic setting -- The Neuse River Estuary (fig. 1) is a drowned river valley located in the Tidewater Region, or the Outer Atlantic Coastal Plain, of North Carolina. It is a tributary of the large Albemarle-Pamlico estuarine system. The estuary has a distinct 'V' shape, with the upper limb oriented NW-SE and the lower limb oriented SW-NE. The hinge is located where the estuary narrows and crosses the Minnesott sand ridge. This feature is a subaerial barrier island complex correlative with the regional Bogue-Suffolk Scarp that separates two marine terraces of different ages to the east and west. Stratigraphic units of Eocene to Pliocene age underlie

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

2006-01-01

49

Atmospheric nitrogen deposition to the Mullica River-Great Bay Estuary.  

Science.gov (United States)

Measurements of nitrate and ammonium in precipitation and associated with aerosols were conducted at Rutgers University Marine Field Station in Tuckerton, New Jersey from March 2004 to March 2005 to characterize atmospheric nitrogen deposition to the Mullica River-Great Bay Estuary. The arithmetic means of nitrate and ammonium concentrations for precipitation samples were 2.3mgL(-1) and 0.42mgL(-1), respectively. Nitrate and ammonium concentrations in aerosol samples averaged 3.7microgm(-3) and 1.6microgm(-3), respectively. Wet deposition rates appeared to vary with season; the highest rate of inorganic nitrogen deposition (nitrate+ammonium) occurred in the spring with an average value of 1.33kg-Nha(-2)month(-1). On an annual basis, the total (wet and dry) direct atmospheric deposition fluxes into the Mullica River-Great Bay Estuary were 7.08kg-Nha(-2)year(-1) for nitrate and 4.44kg-Nha(-2)year(-1) for ammonium. The total atmospheric inorganic nitrogen directly deposited to the Mullica River-Great Bay Estuary was estimated to be 4.79x10(4)kg-Nyear(-1), and the total atmospheric inorganic nitrogen deposited to the Mullica River watershed was estimated to be 1.69x10(6)kg-Nyear(-1). Only a fraction of the nitrogen deposited on the watershed will actually reach the estuary; most of the nitrogen will be retained in the watershed due to utilization and denitrification during transport. The amount of N reaching the Mullica River-Great Bay Estuary indirectly is estimated to be 5.07x10(4)kg-Nyear(-1), approximately 97% is retained within the watershed. This atmospheric nitrogen deposition may stimulate phytoplankton productivity in the Mullica River-Great Bay ecosystem. PMID:17714775

Ayars, Jennifer; Gao, Yuan

2007-12-01

50

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

51

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

Science.gov (United States)

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

52

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

Science.gov (United States)

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

53

Chiral source apportionment of polychlorinated biphenyls to the Hudson River estuary atmosphere and food web.  

Science.gov (United States)

The New York/New Jersey Harbor Estuary is subject to significant contamination of polychlorinated biphenyls (PCBs) from numerous sources, including the historically contaminated Upper Hudson River, stormwater runoff and sewer overflows, and atmospheric deposition from PCBs originating from the surrounding urban area. However, the relative importance of these sources to the estuary's food web is not fully understood. Sources of PCBs to the estuary were apportioned using chiral signatures of PCBs in air, water, total suspended matter, phytoplankton, and sediment. PCBs 91, 95, 136, and 149 were racemic in the atmosphere of the estuary. However, the other phases contained nonracemic PCB 95 and to a lesser extent PCB 149. Thus, the predominant atmospheric source of these congeners is likely unweathered local pollution and not volatilization from the estuary. The similarity in chiral signatures in the other phases is consistent with dynamic contaminant exchange among them. Chiral signatures in the dissolved phase and total suspended matter were correlated with Upper Hudson discharge, suggesting thatthe delivery of nonracemic contaminated sediment from the Upper Hudson, not the atmosphere, controls phytoplankton uptake of some PCBs. Thus, measures to control PCB contamination in the Upper Hudson should be effective in reducing loadings to the estuary's aquatic ecosystem. PMID:17937297

Asher, Brian J; Wong, Charles S; Rodenburg, Lisa A

2007-09-01

54

Diatoms from the Pearl River estuary, China and their suitability as a water salinity indicator for coastal environments.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We collected 77 modern diatom samples from sites across the Pearl River estuary, China to analyze the relationship between diatom assemblages and environmental parameters including water salinity, water depth and sediment particle size. Results showed that marine diatoms were dominant in the high salinity environment around Hong Kong and the outer part of the estuary. Brackish water diatoms were found in high abundance in the central part of the estuary. Both marine and brackish water diatoms...

2010-01-01

55

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two sediment cores from the Changjiang (Yangtze) River estuary and its adjacent East China Sea were collected and studied for eutrophication history using paleoecological records of environmental changes over the last century. A multiproxy approach by using biological and geochemical analyses revealed changes in diatom assemblages, total organic carbon (TOC), total nitrogen (TN) and biogenic silica (BSi) and give an indication of nutrient in status and trends in Changjiang River estuar...

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

2012-01-01

56

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

Science.gov (United States)

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

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

2006-12-01

57

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

Science.gov (United States)

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

Spatial and Temporal Variability of Sedimentary Environments in the Hudson River Estuary  

Science.gov (United States)

Sitting at the interface between marine and terrestrial systems, estuaries are sensitive to natural climatic, sea-level and tectonic changes as well as to anthropogenic impacts. Research on estuarine systems has led to improved understanding of estuarine processes, but relation of those processes to the long-term evolution of estuaries is still uncertain. A geophysical survey funded by the New York State Department of Environmental Conservation resolves details of spatial and temporal variability of sedimentary processes in the Hudson River Estuary. Here we present interpreted sedimentary environments and evidence of past environments for a 30-km stretch of the Lower Hudson River Estuary, between Piermont and Haverstraw Bay. Integration of high-resolution seismic surveys, side-scan sonar imagery and multibeam bathymetry with sediment samples allows differentiation of three distinct sedimentary environments in the estuary: depositional, erosional and dynamic. Modern deposition occurs mainly in Haverstraw Bay on shallow marginal flats bounding the river channel as well as the channel floor. South of Haverstraw Bay, deposition is limited to a local region in a sharp channel bend, and to areas of anthropogenic disturbance. Erosion in the Lower Estuary dominates the broad, shallow western marginal flats in Tappan Zee and Piermont. Man-made and natural obstructions to river flow, such as a relic oyster bed that outcrops on the river bottom in Haverstraw Bay, create local erosional areas. Dynamic environments, incorporating both erosion and deposition, occur where sediment is actively moving through the estuary. Flow-perpendicular sediment waves dominate the channel floor and walls of the Lower Estuary. Dynamic sediment drifts and scouring are associated with man-made constructions, such as the Tappan Zee Bridge and a pipeline crossing the river south of Piermont Pier. Information from sub-bottom seismics and sediment coring provide evidence that sedimentary environments have changed through time. A delta deposit approx. 3-km wide, 7-km long with an average thickness of 3.5-m, sourced from the Sparkill Creek, dominates the marginal flats south of the Tappan Zee Bridge. Radiocarbon dates indicate that the delta was actively depositing between 3370 and 2520 cal yr B.P., but the modern delta surface is eroded with no evidence of recent deposition. Relic oyster beds are imaged in this stretch of the estuary, buried by sediment and outcropping on the river bottom. Existing shell dates suggest that oysters grew during distinct periods in the past but disappeared 500-800 cal yr B.P. Although modern salinities could support oysters, environmental factors such as cooler temperatures during the Little Ice Age and increased storminess may have prevented populations from thriving as they did in the past. These data provide a detailed view of estuarine processes and variability within the Hudson River system and continue to improve our understanding of long-term estuary evolution.

Slagle, A. L.; Carbotte, S. M.; Nitsche, F. O.; Ryan, W. B.; Bell, R.

2004-05-01

59

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

Science.gov (United States)

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

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

2005-01-01

60

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

Science.gov (United States)

The distributions of dissolved organic carbon (DOC), Ba, U, and a suite of naturally occurring radionuclides in the U/Th decay series (222Rn, 223,224,226,228Ra) were studied during high- and low-discharge conditions in the Loxahatchee River estuary, Florida to examine the role of submarine groundwater discharge in estuarine transport. The fresh water endmember of this still relatively pristine estuary may reflect not only river-borne constituents, but also those advected during active groundwater/surface water (hyporheic) exchange. During both discharge conditions, Ba concentrations indicated slight non-conservative mixing. Such Ba excesses could be attributed either to submarine groundwater discharge or particle desorption processes. Estuarine dissolved organic carbon concentrations were highest at salinities closest to zero. Uranium distributions were lowest in the fresh water sites and mixed mostly conservatively with an increase in salinity. 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 the discharge of fresh groundwater. Activities of four naturally occurring isotopes of Ra (223,224,226,228Ra) in this estuary and select adjacent shallow groundwater wells yield mean estuarine water-mass transit times of less than 1 day; these values are in close agreement to those calculated by tidal prism and tidal frequency. Submarine groundwater discharge rates to the Loxahatchee River estuary were calculated using a tidal prism approach, an excess 226Ra mass balance, and an electromagnetic seepage meter. Average SGD rates ranged from 1.0 to 3.8 ?? 105??m3 d- 1 (20-74??L m- 2 d- 1), depending on river-discharge stage. Such calculated SGD estimates, which must include both a recirculated as well as fresh water component, are in close agreement with results obtained from a first-order watershed mass balance. Average submarine groundwater discharge rates yield NH4+ and PO4- 3 flux estimates to the Loxahatchee River estuary that range from 62.7 to 1063.1 and 69.2 to 378.5????mol m- 2 d- 1, respectively, depending on river stage. SGD-derived nutrient flux rates are compared to yearly computed riverine total N and total P load estimates. ?? 2006 Elsevier B.V. All rights reserved.

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

2006-01-01

 
 
 
 
61

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

Science.gov (United States)

Surface sediment samples in the Laptev Sea have average 137Cs content of 7.1 Bq kg(-1), a value intermediate between that of the western Kara Sea (23 Bq kg(-1) and the East Siberian Sea (4.2 Bq kg-'). Both surface sediment content and sediment inventory of 137Cs in the Laptev Sea sediments show significant variability, and the influence of a variety of environmental factors.137Cs concentrations in the Laptev Sea surface sediments range from 0.8 to 16 Bq kg(-1). There is a marked increase in 137Cs content of surface sediment samples collected near the Lena River delta, and a local enrichment in the 137Cs inventories at these sites is also evident. Fine-grained mixed-layer illite/ smectite rich sediments in the estuary provide effective adsorption sites to fix 137Cs, in spite of desorption processes associated with low salinities in estuarine mixing. The Lena River-Laptev Sea mixing zone is a major site of sea-ice production. River and shelf sediments are incorporated into sea-ice formed in this region (Holmes and Creager, 1974). The irregular 137Cs activity profiles of the Lena River estuary cores indicate disturbance or removal of 137Cs-laden sediments via sea-ice related processes. Lena River and Estuary sediments may have served as a secondary source (i.e. other than direct fallout) of 137Cs in sea-ice. North-east of the Lena River estuary, sediment contains a thin layer of 137Cs-bearing material over an erosion surface. The 137Cs-laden surface layer may be the result of transient deposition of estuarine sediments being delivered by sea-ice or spring floods. PMID:11693646

Johnson-Pyrtle, A; Scott, M R

2001-10-01

62

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

Science.gov (United States)

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

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

2014-03-15

63

Temperature, Dissolved Oxygen, Total Alkalinity, and Biochemical Oxygen Demand in the Columbia River Estuary, 1966-67.  

Science.gov (United States)

Temperature, dissolved oxygen, total alkalinity, and biochemical oxygen demand collected at 19 locations in the Columbia River estuary are presented as a reference for researchers in fisheries or in water quality. (Author)

C. W. Sims C. J. Cederholm

1970-01-01

64

Large-river delta-front estuaries as natural “recorders” of global environmental change  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Large-river delta-front estuaries (LDE) are important interfaces between continents and the oceans for material fluxes that have a global impact on marine biogeochemistry. In this article, we propose that more emphasis should be placed on LDE in future global climate change research. We will use some of the most anthropogenically altered LDE systems in the world, the Mississippi/Atchafalaya River and the Chinese rivers that enter the Yellow Sea (e.g., Huanghe and Changjiang) as case-studies, ...

Bianchi, Thomas S.; Allison, Mead A.

2009-01-01

65

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

Science.gov (United States)

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

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

2011-12-01

66

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

Science.gov (United States)

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

Kang, KiRyong; Di Iorio, Daniela

2006-02-01

67

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

Science.gov (United States)

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

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

2012-12-01

68

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

69

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

International Nuclear Information System (INIS)

Anthropogenic radionuclides (Cs"1"3"7, Cs"1"3"4, Co"6"0) have been introduced to the James River estuary as a result of low-level releases from the Surry Reactor site since 1973 and worldwide atmospheric fallout from nuclear weapons tests since the early 1950s. The total radionuclide burden in the estuary sediments has been estimated by integrating radionuclide activities in 29 box cores and extrapolating these integrated values over surface areas subdivided on the basis of sediment type, rate of accumulation, and proximity to the reactor release site. The results indicate that 30% of the Co"6"0, but only 15% of the Cs"1"3"4 released from the reactor site, has been retained in the estuary sediments, and about 40% of the Cs"1"3"4 and Co"6"0 sediment inventory is in areas that represent less than 5% of the total estuarine surface area. Depletion of the Cs"1"3"4 in downstream sediments forms a noticeable trend in the James River estuary, and it is postulated that seawater cation competition and exchange is primarily responsible. 26 references, 1 figure, 4 tables

70

Polycyclic aromatic hydrocarbons in surface sediment of typical estuaries and the spatial distribution in Haihe river basin.  

Science.gov (United States)

Polycyclic aromatic hydrocarbons (PAHs) with carcinogenic and mutagenic characteristics have been detected in many estuaries and bays around the world. To detect the contaminated level in typical estuaries in Haihe river basin, China, a comprehensive survey of 16 PAHs in surface sediment has been conducted and an ecological risk assessment has been taken. It showed that Haihe river estuary had the highest concentration, ranging from 92.91 to 15886.00 ng g(-1). And Luan river estuary has the lowest polluted level, ranging from 39.55 to 328.10 ng g(-1). PAHs in sediment were dominated by low and mid molecular weight PAHs in all the sampling sites. Most of the sampling sites in all sampling seasons indicated a rarely happened ecological risk of ?PAHs, while the S6 in Haihe river estuary was in an occasionally anticipated risk. To illustrate the spatial distribution pattern of PAHs in surface sediment in Haihe river basin, the results were compared with previous research of the research team. Based on data of the comparison, it had been revealed that Haihe river had the most serious PAHs pollution, with an average concentration of 5884.86 ng g(-1), and showed the highest contamination level in all four ecological units. The ?PAHs concentration showed in a rank of reservoir > estuary > rural area > city. PMID:24740319

Liu, Jing L; Zhang, Jing; Liu, Feng; Zhang, Lu L

2014-05-01

71

???????????????? 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

72

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

73

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

Science.gov (United States)

The distribution of Triclosan within the Hudson River Estuary can be explained by a balance among the overall effluent inputs from municipal sewage treatment facilities, dilution of Triclosan concentrations in the water column with freshwater and seawater inputs, removal of 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 k(d) approximately 10(4), consistent with laboratory estimates. PMID:19559448

Wilson, Brittan; Chen, Robert F; Cantwell, Mark; Gontz, Allen; Zhu, Jun; Olsen, Curtis R

2009-01-01

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.

2008-03-02

75

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

International Nuclear Information System (INIS)

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

1989-09-12

76

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1989-01-01

77

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 measure...

Lisset Susana Cobas Gómez; Eusebio Perigó; Roberto Piñeiro; Regla Duthit Somoza

2011-01-01

78

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 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 Thes...

Corbett, D. R.

2010-01-01

79

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

80

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

Science.gov (United States)

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

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

2014-06-01

 
 
 
 
81

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

82

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bacterial particle association has important consequences for water-quality monitoring and modeling. Particle association can change vertical and horizontal transport of bacterial cells, as well as patterns of persistence and production. In this study, the abundance and particle association of total bacteria and the fecal-indicator, Enterococcus, were quantified between June and October 2008 in the lower Hudson River Estuary (HRE). Twelve sites were sampled, including mid-c...

Elizabeth Suter; Juhl, Andrew R.; O’mullan, Gregory D.

2011-01-01

83

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 edib...

2010-01-01

84

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

85

The geochemistry of rare earth elements in the Amazon River estuary  

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-05-01

86

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

87

Analysis of change of red tide species in Yodo River estuary by the numerical ecosystem model.  

Science.gov (United States)

Occurrence number of red tides in Osaka Bay in Japan is more than 20 cases every year. Diatom red tide was dominant in Osaka Bay, but the non-diatom red tide was dominant in early 1990s. Therefore, the material cycling in Yodo River estuary in Osaka Bay during August from 1991 to 2000 was analyzed by using the numerical ecosystem model and field observation data to clarify the reasons of change in red tide species. Year-to-year variation in calculated concentration ratio of diatom to non-diatom corresponds to the variation in observed ratio of red tide days of diatom to non-diatom. Limiting nutrient of primary production is phosphate over the period. Diatom dominated from 1991 to 1993, but it was difficult for non-diatom to grow due to the limitation by physical condition. Non-diatom was able to grow because of good physical and nutrient conditions from 1994 to 1996. And diatom dominated again under the good physical condition, and phosphorus supply was not enough for non-diatom to grow from 1998 to 2000. Phosphate concentration in the lower layer of Yodo River estuary was important to the variation in red tide species in the upper layer of Yodo River estuary. PMID:18513758

Hayashi, Mitsuru; Yanagi, Tetsuo

2008-01-01

88

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

Energy Technology Data Exchange (ETDEWEB)

Polychlorinated biphenyls (PCBs) were measured in the air and water over the Hudson River Estuary during six intensive field campaigns from December 1999 to April 2001. Over-water gas-phase {sigma}PCB concentrations averaged 1100 pg/m{sup 3} and varied with temperature. Dissolved-phase {sigma}PCB concentrations averaged 1100 pg/L and displayed no seasonal trend. Uncertainty analysis of the results suggests that PCBs with 5 or fewer chlorines exhibited net volatilization. The direction of net air/water exchange could not be determined for PCBs with 6 or more chlorines. Instantaneous net fluxes of {sigma}PCBs ranged from +0.2 to +630 ng m{sup -2} d{sup -1}. Annual fluxes of {sigma}PCBs were predicted from modeled gas-phase concentrations, measured dissolved-phase concentrations, daily surface water temperatures and wind speeds. The net volatilization flux was +62 {mu}g m{sup -2} yr{sup -1}, corresponding to an annual loss of +28 kg/yr of {sigma}PCBs from the Hudson River Estuary for the year of 2000. - Investigation of the air-water exchange of PCBs in the Hudson River Estuary suggests that PCBs with 5 or fewer chlorines undergo net volatilization.

Yan Shu [Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901 (United States); Rodenburg, Lisa A. [Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901 (United States)], E-mail: rodenburg@envsci.rutgers.edu; Dachs, Jordi [Department of Environmental Chemistry, IIQAB-CSIC, Jordi Girona 18-26, Barcelona E-08034, Catalunya (Spain)], E-mail: jdmqam@cid.csic.es; Eisenreich, Steven J. [European Chemicals Bureau, Institute for Health and Consumer Protection, Joint Research Center, TP 582, European Commission, Ispra 21020 (Italy)], E-mail: steven.eisenreich@ec.europa.eu

2008-03-15

89

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

International Nuclear Information System (INIS)

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

2008-03-01

90

Assessment of dissolved heavy metal in the Yangtze River estuary and its adjacent sea, China.  

Science.gov (United States)

The purpose of this paper is to determine the concentrations of dissolved heavy metals namely mercury (Hg), lead (Pb), cadmium (Cd), and copper (Cu) and to investigate the relationships between nutrients (nitrate-nitrogen and phosphate) and dissolved heavy metals. For this purpose, the concentrations of dissolved heavy metals were measured through 51 voyages form 1984 to 2006 in the Yangtze river estuary and its adjacent sea. Results analysis showed that dissolved heavy metals were not the main pollutants in the Yangtze river estuary, and the main source of heavy metal contamination was industrial wastewater from terrestrial pollution during the past 20 years. Heavy metal values showed significant abundance in the south branch of the Yangtze River estuary and Hangzhou Bay. In addition, Pb showed negative correlation with nutrients, while the positive correlations between Hg, Cd, and nutrients were shown. The obtained molar ratios, DeltaCd/DeltaN = 1.68 x 10(-5) and DeltaCd/DeltaP = 1.66 x 10(-4), are close to those in plankton, showing the biogeochemical behavior and process of dissolved cadmium. PMID:19373439

An, Qiang; Wu, Yanqing; Wang, Jinhui; Li, Zhien

2010-05-01

91

[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

92

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

93

Bedform signatures of channel erosion: examples from the Delaware and Hudson River estuaries  

Science.gov (United States)

Bedforms are the most ubiquitous and accessible indicators of sediment-transport conditions in river-estuaries and shed light on processes and patterns of deposition and erosion over large spatial scales. Results of recent observational studies in the Delaware and Hudson River estuaries (Mid-Atlantic Region U.S.A.) permit a provisional systemization of bedform morphologies associated with cohesive strata erosion in tidal channels. An understanding of mechanisms and scales of erosion is necessary to predict the long-term fate of pollutants buried within urbanized sections of these estuaries. Side-scan sonographs, high-resolution multibeam bathymetry, and extensive sedimentological data collectively reveal at least two common signatures of channel erosion: (1) depositional bedforms, including flow-perpendicular, sand and gravel ribbons, and flow-parallel, sediment trails and furrows; and (2) sculpted forms, including cohesive sediment ripples and waves, scour depressions, and terraces. Although the ribbons and trails are created through bedload deposition, because these forms are observed only where the channels are deepening on the long term (as per historical bathymetric data), they are in fact manifestations of net erosion. Both depositional and sculpted bedforms exhibit marked cross-channel variations in distribution, presumably due to flood-ebb current asymmetry and transverse gradients in sediment transport. Additionally, sediment supply influences the along-channel continuity of depositional forms, which ranges from patchy (sediment limited) to continuous (sediment rich). Coring observations of sands and shell fragments in the vicinity of the sculpted forms suggest that abrasion is an agent of bed reworking. Indeed, these findings confirm that corrasion is an important mechanism of erosion in muddy estuarine channels, though this elusive process is generally not considered in models of channel morphodynamics. Bedforms are useful for recognizing channel disequilibrium in the Delaware and Hudson River estuaries, and provide context for evaluating temporal change related to natural and human factors.

Sommerfield, C.; Klingbeil, A.; Walsh, D.

2003-04-01

94

Disposal of radioactive wastes into rivers, lakes and estuaries  

International Nuclear Information System (INIS)

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

1971-04-01

95

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

96

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

97

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

Directory of Open Access Journals (Sweden)

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

D. Xue

2014-03-01

98

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

99

Changes in Epipelic Diatom Diversity from the Savannah River Estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Littoral zones can be characterized with temporal exposure of algae to diurnal desiccation at low tides. Combinations of diverse freshwater, marine, and brackish diatoms dominate exposed mud samples. With enlargement of the delta of the Savannah River, Georgia and other anthropogenic influences, changes in the rich epipelic community will not be estimated accurately without baseline data. In the current study, mud sam...

Manoylov, Kalina M.; Dominy Jr, Joseph N.

2013-01-01

100

Mapping ecosystem services in the St. Louis River Estuary  

Science.gov (United States)

Sustainable management of ecosystems for the perpetual flow of services beneficial to human communities requires reliable data about from where in the ecosystem services flow. Our objective is to map ecosystem services in the St. Louis River with the overarching U.S. EPA goal of ...

 
 
 
 
101

Mapping ecosystem services in the St. Louis River estuary (presentation)  

Science.gov (United States)

Management of ecosystems for sustainable provision of services beneficial to human communities requires reliable data about from where in the ecosystem services flow. Our objective is to map ecosystem services in the St. Louis River with the overarching EPA goal of community sust...

102

Factors affecting chick provisioning by Caspian Terns nesting in the Columbia River estuary  

Science.gov (United States)

We investigated factors affecting chick provisioning by radio-tagged Caspian Terns (Sterna caspia) nesting in a large colony on East Sand Island in the Columbia River estuary during 2001. Caspian Tern predation on juvenile salmonids (Oncorhynchus spp.) in the estuary prompted resource managers to relocate ca. 9,000 pairs of terns nesting on Rice Island (river km 34) to East Sand Island (river km 8), where terns were expected to consume fewer salmonids in favor of marine forage fishes. This study investigated factors influencing foraging success, diet composition, and overall reproductive success at the managed Caspian Tern colony. Our results indicated that daytime colony attendance by nesting terns averaged 64% and decreased throughout the chick-rearing period, while duration of foraging trips averaged 47 min and increased during the same period; these seasonal changes were more strongly related to date than chick age. Average meal delivery rates to 2-chick broods (0.88 meals h-1) were 2.6 times greater than to 1-chick broods (0.33 meals h-1). Parents delivered more juvenile salmonids to chicks during ebb tides than flood tides, but meal delivery rates to the nest remained constant, suggesting diet composition tracks relative availability of prey species. Foraging trips resulting in delivery of juvenile salmonids averaged 68% longer than foraging trips for schooling marine forage fishes, indicating higher availability of marine prey near the colony. High availability of marine forage fish in the Columbia River estuary during 2001 was apparently responsible for high colony attendance, short foraging trips, high chick meal delivery rates, and high nesting success of Caspian Terns on East Sand Island.

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

2005-01-01

103

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

Science.gov (United States)

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

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

2009-04-01

104

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

105

Acoustic propagation in the Hudson River Estuary: Analysis of experimental measurements and numerical modeling results  

Science.gov (United States)

Underwater intrusion detection is an ongoing security concern in port and harbor areas. Of particular interest is to detect SCUBA divers, unmanned underwater vehicles and small boats from their acoustic signature. A thorough understanding of the effects of the shallow water propagating medium on acoustic signals can help develop new technologies and improve the performance of existing acoustic based surveillance systems. The Hudson River Estuary provides us with such a shallow water medium to conduct research and improve our knowledge of shallow water acoustics. Acoustic propagation in the Hudson River Estuary is highly affected by the temporal and spatial variability of salinity and temperature due to tides, freshwater inflows, winds etc. The primary goal of this research is to help develop methodologies to predict the formation of an acoustic field in the realistic environment of the lower Hudson River Estuary. Shallow water high-frequency acoustic propagation experiments were conducted in the Hudson River near Hoboken, New Jersey. Channel Impulse Response (CIR) measurements were carried out in the frequency band from 10 to 100 kHz for distances up to 200 meters in a water depth of 8-10 meters which formed the basis for experimental Transmission Loss (TL). CIR data was also utilized to demonstrate multi-path propagation in shallow water. Acoustic propagation models based on Ray Theory and Parabolic Equation methods were implemented in the frequency band from 10 to 100 kHz and TL was estimated. The sound velocity profiles required as input by acoustic propagation models were calculated from in-situ measurements of temperature, salinity and depth. Surface reflection loss was obtained from CIR data and incorporated into the acoustic propagation models. Experimentally obtained TL was used to validate the acoustic model predictions. An outcome of this research is an operational acoustic transmission loss (TL) forecast system based on the existing, Stevens New York Harbor observation and prediction system (NYHOPS) which provides 48-hour forecasts of salinity and temperature profiles. Initial results indicate that the NYHOPS forecast of sound speed profiles used in conjunction with the acoustic propagation model is able to make realistic forecasts of TL in the Hudson River Estuary.

Radhakrishnan, Sreeram

106

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

107

Benthic bacterial biomass and production in the Hudson River estuary  

International Nuclear Information System (INIS)

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

1989-01-01

108

Latest Holocene evolution and human disturbance of a channel segment in the Hudson River Estuary  

Science.gov (United States)

The latest Holocene sedimentary record of a cohesive channel and subtidal shoal in the lower Hudson River Estuary was examined to elucidate natural (sea-level rise, sediment transport) and anthropogenic (bulkheading, dredging) influences on the recent morphodynamic evolution of the system. To characterize the seafloor and shallow subbottom, ??? 100 km of high-resolution seismic reflection profiles (chirp) were collected within a 20-km reach of the estuary and correlated with sediment lithologies provided by eight vibracores recovered along seismic lines. Sediment geochronology with 137Cs and 14C was used to estimate intermediate and long-term sedimentation rates, respectively, and historical bathymetric data were analyzed to identify regional patterns of accretion and erosion, and to quantify changes in channel geometry and sediment volume. The shoal lithosome originated around 4 ka presumably with decelerating eustatic sea level rise during the latest Holocene. Long-term sedimentation rates on the shoal (2.3-2.6 mm/yr) are higher than in the channel (2 mm/yr) owing to hydrodynamic conditions that preferentially sequester suspended sediment on the western side of the estuary. As a result, the shoal accretes oblique to the principal axis of tidal transport, and more rapidly than the channel to produce an asymmetric cross-section. Shoal deposits consist of tidally bedded muds and are stratified by minor erosion surfaces that seismic profiles reveal to extend for 10s of meters to kilometers. The frequency and continuity of these surfaces suggest that the surficial shoal is catastrophically stripped on decadal-centennial time scales by elevated tidal flows; tidal erosion maintains the shoal at a uniform depth below sea level and prevents it from transitioning to an intertidal environment. Consequently, the long-term sedimentation rate approximates the rate of sea-level rise in the lower estuary (1-3 mm/yr). After the mid 1800s, the natural geometry of the lower Hudson River Estuary changed rapidly in response to engineering works that forced the channel to self-deepen. Analysis of historical bathymetric data indicates that the channel lost an estimated 3 ?? 106 tons of sediment between ca. 1939 and 2002 (50,000 tons/yr average) by subaqueous erosion, increasing in depth by as much as 4 m in places. Erosion appears to have been concurrent with systematic bulkheading of the shoreline after ca. 1865, which decreased the estuary surface area by ??? 19% overall. Evidently, self-deepening of the channel is a morphodynamic adjustment to reestablish equilibrium cross-sectional area, yet the state of this change locally and elsewhere in the estuary is unknown. Subaqueous erosion documented in this study is a significant source of sediment with implications to the sediment budget and environmental quality of the Hudson River Estuary. ?? 2005 Elsevier B.V. All rights reserved.

Klingbeil, A. D.; Sommerfield, C. K.

2005-01-01

109

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

2013-11-01

110

Man-induced regime shifts in small estuaries—II: a comparison of rivers  

Science.gov (United States)

This is Part II of two papers on man-induced regime shifts in small, narrow, and converging estuaries, with focus on the interaction between effective hydraulic drag, fine sediment import, and tidal amplification, induced by river engineering works, e.g., narrowing and deepening. Paper I describes a simple linear analytical model for the tidal movement in narrow, converging estuaries and a conceptual model on the response of tidal rivers to river engineering works. It is argued that such engineering works may set in motion a snowball effect bringing the river into an alternative steady state. Part II analyses the historic development in tidal range in four rivers, e.g., the Elbe, Ems, Loire, and Scheldt, all in northwest Europe; data are available for many decades, up to a century. We use the analytical model derived in Part I, showing that the effective hydraulic drag in the Ems and Loire has decreased considerably over time, as anticipated in Part I. We did not find evidence that the Upper Sea Scheldt is close to its tipping point towards hyperturbid conditions, but risks have been identified. In the Elbe, tidal reflections against the profound step in bed level around Hamburg seem to have affected the tidal evolution in the last decades. It is emphasized that the conceptual picture sketched in these papers is still hypothetical and needs to be validated, for instance through hind-cast modeling of the evolution of these rivers. This will not be an easy task, as historical data for a proper calibration of the models required are scarce.

Winterwerp, Johan C.; Wang, Zheng Bing; van Braeckel, Alexander; van Holland, Gijsbert; Kösters, Frank

2013-12-01

111

Distribution and flux of "2"2"6Ra and "2"2"8Ra in the Amazon River estuary  

International Nuclear Information System (INIS)

Measurements of "2"2"6Ra and "2"2"8Ra 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 "2"2"6Ra and approximately 2.6% of the "2"2"8Ra 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 "2"2"6Ra concentration and quadruple the estuarine "2"2"8Ra concentration above that caused by the dissolved and desorbed river components alone

1985-07-20

112

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

113

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1982-11-01

114

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

115

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

International Nuclear Information System (INIS)

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

1972-01-01

116

Lanzavecchia mangrovi sp. n. (Nematoda, Dorylaimida) from mangroves of Red River Estuary, Vietnam.  

Science.gov (United States)

A new nematode species found in the Red River Estuary of Vietnam is described. Lanzavecchia mangrovi sp. n. is morphologically close to L. coomansi Nicholas, Stewart, 1984, but differs in its longer body (L = 2.71-3.76 µm versus L = 2.2-2.9 µm), shorter spicules (63-65 mm versus 72-88), longer prerectum (500-675 mm versus 262-310 µm) and shorter distal portion of tail in relation to the proximal portion (0.6-0.8 versus 0.9-2.3). PMID:24870651

Gagarin, Vladimir G

2014-01-01

117

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

International Nuclear Information System (INIS)

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

2003-03-01

118

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

119

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

International Nuclear Information System (INIS)

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

1982-01-01

120

Analysis of thermal impact in tidal rivers and estuaries  

International Nuclear Information System (INIS)

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

1980-01-01

 
 
 
 
121

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

Science.gov (United States)

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

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

2012-10-01

122

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

123

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

Directory of Open Access Journals (Sweden)

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

B.Y. Kamaruzzaman

2009-01-01

124

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 ("1"3"7Cs) 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 "1"3"7Cs sorbed by sand, silt, and clay in the bed

1985-08-13

125

[Temporal and spatial distribution of red tide in Yangtze River Estuary and adjacent waters].  

Science.gov (United States)

The events of red tide were collected in Yangtze River Estuary and adjacent waters from 1972 to 2009. Based on geographic information system (GIS) analysis on the temporal and spatial distribution of red tide, the distribution map was generated accordingly. The results show: (1) There are three red tide-prone areas, which are outside the Yangtze River estuary and the eastern of Sheshan, Huaniaoshan-Shengshan-Gouqi, Zhoushan and the eastern of Zhujiajian. The red tide occurred 174 times in total, in which there were 25 times covered the area was larger than 1 000 km2. After 2000, the frequency of red tide were significantly increasing; (2) The frequent occurrence of red tide was in May (51% of total occurrence) and June (20% of total occurrence); (3) In all of the red tide plankton, the dominant species were Prorocentrum danghaiense, Skeletonema costatum, Prorocentrum dantatum, Nactiluca scientillans. The red tides caused by these species were 38, 35, 15, 10 times separately. PMID:22165212

Liu, Lu-San; Li, Zi-Cheng; Zhou, Juan; Zheng, Bing-Hui; Tang, Jing-Liang

2011-09-01

126

[Distribution of dinoflagellate resting cysts in surface sediments from the Changjiang River estuary].  

Science.gov (United States)

In order to understand the potential of algal blooms, surface sediments were collected from 12 stations in the Changjiang River estuary with longitude from 122 degrees to 123.5 degrees E and latitude from 29 degrees to 32 degrees N from April to May 2002 to investigate the distribution of dinoflagellate resting cysts, 29 different cyst morphotypes representing 19 genera and 6 groups were identified. Among them, there were 11 autotrophic species and 18 heterotrophic ones. The number of species observed in each sample was low, and varied from 10 to 21. Cyst concentrations varied from 11.7 to 587 cysts per gram dry weight. Cyst concentrations and species diversity were higher in offshore areas, and increased from the west to the east, and from the north to the south within the studied area. Cysts of Alexandrium distributed widely in the Changjiang River estuary, with the maximum concentration of 40.4 cysts per gram dry weight. Cysts of harmful algal bloom causative species such as Alexandrium, Gymnodinium catenatum, Lingulodinium polyedra, Scrippsiellla trochoidea, Polykrikos kofoidii and P. schwartzii were also observed in this survey. PMID:14587318

Wang, Zhaohui; Qi, Yuzao

2003-07-01

127

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

128

Seasonal changes in the demersal nekton community off the Changjiang River estuary  

Science.gov (United States)

The diversity, community structure and seasonal variation in demersal nekton off the Changjiang (Yangtze) River estuary was evaluated using monthly trawl survey data, collected between December 2008 and November 2009. A total of 95 species (56 teleosts, 11 cephalopods, and 28 decapod crustaceans) from 69 genera, 49 families and 15 orders were collected. These species could be classified into six groups on the basis of temporal distribution patterns. The resident crab Ovalipes punctatus dominated the community, both in number and biomass. A clear seasonal succession was observed in the species composition. Cluster analysis revealed three primary seasonal groups corresponding to the samples collected in winter-spring, late spring-summer and late summer-autumn. The highest biomass and lowest diversity were observed in summer, while the lowest biomass and highest diversity in winter. The abundance-biomass comparison curves and community composition suggested that the investigated community was moderately disturbed. The results suggest that reduction in fishing pressure and in the degree of seasonal hypoxia are essential for sustainable resource management off the Changjiang River estuary.

Jiang, Yazhou; Ling, Jianzhong; Li, Jiansheng; Yang, Linlin; Li, Shengfa

2014-03-01

129

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

Science.gov (United States)

Polychlorinated biphenyls (PCBs) were measured in the air and water over the Hudson River Estuary during six intensive field campaigns from December 1999 to April 2001. Over-water gas-phase SigmaPCB concentrations averaged 1100 pg/m3 and varied with temperature. Dissolved-phase SigmaPCB concentrations averaged 1100 pg/L and displayed no seasonal trend. Uncertainty analysis of the results suggests that PCBs with 5 or fewer chlorines exhibited net volatilization. The direction of net air/water exchange could not be determined for PCBs with 6 or more chlorines. Instantaneous net fluxes of SigmaPCBs ranged from +0.2 to +630 ng m(-2) d(-1). Annual fluxes of SigmaPCBs were predicted from modeled gas-phase concentrations, measured dissolved-phase concentrations, daily surface water temperatures and wind speeds. The net volatilization flux was +62 microg m(-2) yr(-1), corresponding to an annual loss of +28 kg/yr of SigmaPCBs from the Hudson River Estuary for the year of 2000. PMID:17854962

Yan, Shu; Rodenburg, Lisa A; Dachs, Jordi; Eisenreich, Steven J

2008-03-01

130

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

Science.gov (United States)

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

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

2010-05-01

131

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

132

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

Science.gov (United States)

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

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

2013-12-01

133

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

Science.gov (United States)

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

134

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

135

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

1990-11-06

136

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

Science.gov (United States)

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

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

2013-01-01

137

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

138

Coastline Change Surround Sekampung River Estuary Estimated by Geographic Information System Technique  

Directory of Open Access Journals (Sweden)

Full Text Available Surround a big river estuary coastline has a dynamic characteristic and change along a period of time, because of a natural process and/or it is accelerated by human activities. The surround Sekampung river estuary coastline located in Rawa Sragi area is one of the most dynamic coastlines in southern Lampung Province that has changed significantly from 1959 (as a natural process to year 1987 (as an accelerated process by human activities since the government of Indonesia has applied swamp drainage system for Rawa Sragi area. It is likely that the coastline has changed significantly in the period of 1987 to 2009 (as an increasing intensity of the human activities in the surrounding Rawa Sragi land. The objective of this research was to analyze the coastline change in the surrounding of Sekampung river estuary in two periods of time: (1 the change of the 1959 – 1987 period coastlines; and (2 the change of the 1987 – 2009 period coastlines. The method of this research was a GIS technique, the implementation was divided into three main steps: (1 the first analysis was conducted in laboratory include raster data source analysis and registration, coastline digitations, and overlaying and analysis of the coastline data; (2 field observation (ground check was conducted to observe and verify the ground existing coastline; and (3 the last analysis was conducted after ground check activity to improve and to verify the first coastline analysis results. The result of this research indicated that coastline change in the period of 1959 to 1987 increased the coast land as much as 717.19 hectares, but decreased the coast land as much as 308.51 hectares. Furthermore the coastline change in the period of 1987 to 2009 increased the coast land as much as 162.504 hectares, but decreased the coast land as much as 492.734 hectares. The 1959 – 1987 coastline change was a coast land increasing period, but the 1987 – 2009 coastline change was a coast land decreasing period.

Fahri

2011-05-01

139

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

140

Tidal currents and bedload transport at the mouth of a rock-bound estuary during low river discharge conditions (Guadiana Estuary, Portugal)  

Science.gov (United States)

The present study documents the poorly-described hydro-sediment dynamics of narrow bedrock-controlled estuaries during periods of low-river discharge. The results also contribute to assess the geomorphological evolution of these systems, when affected by drastic flow regulation. The Guadiana Estuary is a narrow rock-bound mesotidal estuary, 80 km in length, located at the southern border between Spain and Portugal. Until recently, the river inputs to the estuary displayed high (annual and seasonal) variability, characterized by periods of droughts, and episodic flood events with (monthly-averaged) fluvial discharge as high as 5,000 m3s-1 (160 m3s-1 in average, for the period 1947/2001). This pattern has ceased in February 2002, with the impoundment of the main river by the large Alqueva dam, 60 km upstream from the estuary head. At present, the daily-averaged river discharge is generally kept low throughout the year (wide channel entrance using a ship borne Acoustic Doppler Profiler (ADP, operating at 1.5 MHz frequency) during 2 entire tidal cycles, at spring (17 September 2008, 3.0 m tidal range) and at neap tide (21 October 2008, 1.6 m tidal range). Surficial sediment samples were also collected across the channel during the spring tidal cycle. The bed sediment consists of well-sorted medium sand with mean grain size ranging from 0.5 to 0.3 mm (with coarser material at the deepest part of the channel cross-section). Tidal currents were analysed along 6 sub-sections to take into account these grain size variations. The friction velocity and bed shear stress were computed based on the mean depth-averaged velocities of each sub-sections and considering a power law vertical velocity profile. The transport rate of sand was then estimated using Nielsen (1992) formula for bedload transport. The transport of sand in suspension was not considered in the study, as the skin friction velocities were lesser than the estimated settling velocities of the grains. Maximum velocity values (about 1.2 and 0.8 m.s-1 at spring and neap, respectively) were observed near the surface of the deepest sub-section of the channel. The tidal prism was about 1.5 times larger at spring (39x106 m3) than at neap (25x106m3), whereas the fresh water inputs during both tidal cycles were comparatively negligible. Maximum depth-averaged, bed and surface current velocities were ebb-directed at both neap and spring tides, for each of the 6 channel sub-sections. No significant lateral variation of the tidal flow was observed, in relation with the narrowness of the channel. Vertical residual velocity profiles were also directed downstream at both neap and spring tide. At neap, however, the (ebb-directed) residual velocities were slower near the bed and faster near the surface, when compared to the spring tide. These differences were induced by the reinforcement of the estuarine circulation, in relation with enhanced stratified conditions during neap periods (weak currents and reduced mixing). The net bedload transport of sand was also directed downstream for all channel sub-sections. The transport rates of the entire channel were estimated to be of about 30 and 10 m3 for the spring and neap tidal cycles, respectively. Extrapolation of these extreme (i.e. neap and spring) rates yielded a potential seaward export of sand of approximately 15,000 m3yr-1. This study suggests that the Guadiana estuary departs from typical estuaries where landward net transport of sediment is generally described. The outputs of the study are important with respect to the long-term (decades) geomorphological evolutio

Garel, E.; Pacheco, A.; Ferreira, Ó.

2009-04-01

 
 
 
 
141

Quantitative assessment of benthic food resources for juvenile Gulf sturgeon, Acipenser oxyrinchus desotoi in the Suwannee River estuary, Florida, USA  

Science.gov (United States)

Gulf sturgeon, Acipenser oxyrinchus desotoi, forage extensively in the Suwannee River estuary following emigration out of the Suwannee River, Florida. While in the estuary, juvenile Gulf sturgeon primarily feed on benthic infauna. In June-July 2002 and February-April 2003, random sites within the estuary were sampled for benthic macrofauna (2002 n = 156; 2003 n = 103). A mean abundance of 2,562 ind m-2 (SE ?? 204) was found in the summer, with significantly reduced macrofaunal abundance in the winter (mean density of 1,044 ind m-2, SE ?? 117). Benthic biomass was significantly higher in the summer with an average summer sample dry weight of 5.92 g m-2 (SE ?? 0.82) compared to 3.91 g m-2 (SE ?? 0.67) in the winter. Amphipods and polychaetes were the dominant taxa collected during both sampling periods. Three different estimates of food availability were examined taking into account principal food item information and biomass estimates. All three estimates provided a slightly different view of potential resources but were consistent in indicating that food resource values for juvenile Gulf sturgeon are spatially heterogeneous within the Suwannee River estuary. ?? 2005 Estuarine Research Federation.

Brooks, R. A.; Sulak, K. J.

2005-01-01

142

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

Science.gov (United States)

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

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

2014-01-01

143

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.

144

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

145

Seasonal change of community structure and size spectra of zooplankton in the Kaw River estuary (French Guiana)  

Science.gov (United States)

The zooplankton community of the Kaw River estuary in French Guiana and its relationship to its physical and chemical environment are described. Sampling was carried out in November 1998, June 1999, and November 2001, corresponding to the end of the dry season in 1998 and 2001 and to the end of the rainy season in 1999. The Kaw is a small coastal river that drains a vast swamp and flows into the Atlantic Ocean, close to the equator and to the mouth of the Amazon. The hydrodynamic and hydrochemical functioning of the estuary, and the development of littoral mangroves, is strongly constrained by the transport of sediments from the Amazon. During the rainy season the zooplankton, originating from the highly oligotrophic upstream sectors of the Kaw River, was of a strictly freshwater type. It was highly dispersed within the flooding water and dominated (in terms of density) by highly diversified rotifer taxa and (in terms of biomass) by cladocerans. During the dry season the estuary, turbid but enriched by exports from adjacent mudflats and mangroves, was colonized by a large and abundant zooplankton community that was dominated by tintinnids, with copepods as their main associated taxa. Exploiting the rich autochthonous phytoplankton and allochthonous phytobenthos, the microzooplankton components were only constrained when strong hydrodynamic exchanges allowed mixing between the opportunistic estuarine community and coastal mesozooplankton (copepods, chaetognaths, bivalve veligers). Between 1998 and 2001, these two communities were partially isolated from each other due to the gradual arrival of a mud bank, causing the blockage of the estuary. This isolation resulted in the under-exploitation of the microzooplankton. The intensification of tidal currents (spring tide) that occurred during the subsequent stabilization phase of the mudflat induced a more balanced zooplankton community. While the "estuarine" zooplankton of the Kaw River estuary therefore relies on the relative isolation of its water mass, its contribution to the coastal ecosystem also implies the existence of strong tidal currents that temporarily break this isolation.

Lam-Hoai, T.; Guiral, D.; Rougier, C.

2006-06-01

146

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

147

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

148

Determination of acoustic attenuation in the Hudson River Estuary by means of ship noise observations.  

Science.gov (United States)

Analysis of sound propagation in a complex urban estuary has application to underwater threat detection systems, underwater communication, and acoustic tomography. One of the most important acoustic parameters, sound attenuation, was analyzed in the Hudson River near Manhattan using measurements of acoustic noise generated by passing ships and recorded by a fixed hydrophone. Analysis of the ship noise level for varying distances allowed estimation of the sound attenuation in the frequency band of 10-80 kHz. The effective attenuation coefficient representing the attenuation loss above cylindrical spreading loss had only slight frequency dependence and can be estimated by the frequency independent value of 0.058 dBm. PMID:18537300

Roh, Heui-Seol; Sutin, Alexander; Bunin, Barry

2008-06-01

149

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

150

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

Science.gov (United States)

Bacteria in the genus Vibrio are ubiquitous to estuarine waters worldwide and are often the dominant genus recovered from these environments. This genus contains several potentially pathogenic species, including Vibrio vulnificus, Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio alginolyticus. These bacteria have short generation times, as low as 20-30 min, and can thus respond rapidly to changing environmental conditions. A five-parameter mechanistic model was generated based on environmental processes including hydrodynamics, growth, and death rates of Vibrio bacteria to predict total Vibrio abundance in the Neuse River Estuary of eastern North Carolina. Additionally an improved statistical model was developed using the easily monitored parameters of temperature and salinity. This updated model includes data that covers more than eight years of constant bacterial monitoring, and incorporates extreme weather events such as droughts, storms, and floods. These models can be used to identify days in which bacterial abundance might coincide with increased health risks. PMID:23948561

Froelich, Brett; Bowen, James; Gonzalez, Raul; Snedeker, Alexandra; Noble, Rachel

2013-10-01

151

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

152

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-07-01

153

Cycling of Mercury in the Sediments of the Penobscot River (ME) and Great Bay (NH) Estuaries  

Science.gov (United States)

Due to the significant sedimentation of river-borne particulate matter in estuarine, these zones act as repositories for particulate contaminants including Hg. The sediments of estuaries and salt marshes have a high degree of geochemical variability, especially with respect to sulfate and organic matter, and are subject to significant fluctuations in water level and salinity that result in redox transitions in the zone close to the sediment-water interface (SWI). We performed pore water and sediment chemical and molecular analyses to study Hg cycling in the Penobscot River estuary (ME) and Great Bay (NH). At the latter site, sampling was conducted along a transect from the salt marsh to the mudflat. We observed a correspondence between the abundance of sulfate-reducing bacteria and MeHg production, both of which reached a maximum close to the SWI. In some cases, we observed rapid MeHg demethylation close to the SWI that may be due to the activity of iron-reducing bacteria that are dominant close to the SWI, or to the presence bacteria carrying the mer-A gene that may be expressed in Hg contaminated sediments. Our findings suggest that induced shoaling of the redoxcline, such as that observed in salt pannes, may be correlated with a shoaling of the net MeHg production zone and an increase in net MeHg production rate. Based on this, environments such as salt pannes, where the shallow redoxcline leads to the shoaling of the MeHg front, are likely to be Hg methylation and release hotspots.

Amirbahman, A.; Voytek, M. A.; Chen, C. Y.; Brown, L. E.

2008-12-01

154

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

Directory of Open Access Journals (Sweden)

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

J.S. Goddard

2010-01-01

155

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

1988-01-01

156

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.

157

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

Science.gov (United States)

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 man...

B. Anderson R. Garono R. Robinson

2003-01-01

158

A comparison of congeneric PCB patterns in American eels and striped bass from the Hudson and Delaware River estuaries.  

Science.gov (United States)

The Hudson River estuary has enormous spatial variation in polychlorinated biphenyl (PCB) contamination due in large part to historical point source discharges above Troy Dam. The Delaware River estuary has accumulated significant levels of PCBs through decades of industrial, municipal, and non-point source inputs. The overall goal of this research was to use existing data sets to compare and contrast the patterns of accumulated PCB congeners in sub-populations of American eels and striped bass inhabiting these two estuaries and surrounding coastal waters. Using principal component analysis and analysis of covariance (ANCOVA), inter- and intra-estuarine differences in accumulated congeneric patterns were denoted for both species. Results from our study support the idea that migratory behaviors of striped bass hamper the use of accumulated congener-specific PCB patterns in providing information on localized contamination, although major regional differences were seen between upriver Hudson River fish, downriver Hudson River fish and fish from other areas within this study. This study provides additional evidence for the use of the American eel as a biomonitoring tool, since its limited home range provides finer resolution of regional contamination. PMID:14550342

Ashley, Jeffrey T F; Horwitz, Richard; Steinbacher, Joseph C; Ruppel, Bruce

2003-10-01

159

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

160

Effect of deposition and erosion within the main river channel and large lakes on sediment delivery to the estuary of the Yangtze River  

Science.gov (United States)

To examine the influence of deposition and erosion within the main river channel and large lakes on sediment delivery to the estuary at the mouth of the Yangtze River, we established sediment budgets from time series data for 1956-2004 of annual sediment load gauged at 24 stations and estimated data for ungauged areas. Ungauged areas supplied approximately 17% of the total sediment to the estuary, while an average of 34% of sediment is stored in the main river channel complex. Prior to the operation of the Three Gorges Dam (TGD) in 2003, 88% of deposition occurred within a 700-km section immediately downstream from the outlet of the Three Gorges area, including the main channel and a linked lake. Since the operation of the dam, however, deposition has migrated into the Three Gorges area, and downstream erosion has been observed. Patterns of deposition and erosion depend mainly on sediment input, except for the lower 500 km of the river where water discharge is the governing factor. Although sediment supply from the subbasins to the main river system will presumably experience a further decrease because of construction of new dams and afforestation, sediment flux to the estuary is unlikely to fall below 100 × 109 kg/yr over the next 50 years because sediment availability downstream of the TGD will not be a limiting factor over this timescale.

Yang, S. L.; Zhang, J.; Dai, S. B.; Li, M.; Xu, X. J.

2007-06-01

 
 
 
 
161

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

162

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

163

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

164

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

165

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

2011-01-01

166

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

Science.gov (United States)

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

Liu, Wenliang; Poore, Gary C. B.

2013-05-01

167

Chemical risks associated with consumption of shellfish harvested on the north shore of the St. Lawrence River's lower estuary.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Shellfish have the capacity to accumulate chemical contaminants found in their biotope and therefore present a potential risk for consumers. This study was conducted to assess the chemical risks associated with consumption of shellfish harvested on the north shore of the St. Lawrence River's lower estuary. A survey was carried out on 162 recreational harvesters, and shellfish were sampled for chemical contaminant analysis. We quantified 10 metals, 22 polycyclic aromatic hydrocarbons (PAHs), 1...

Gagnon, Fabien; Tremblay, Thierry; Rouette, Justine; Cartier, Jacques-franc?ois

2004-01-01

168

Controls on Bacterial Concentrations in Sediment Grab Samples from the Hudson River Estuary  

Science.gov (United States)

High levels of fecal bacteria resulting from sewage-related pollution are often present in the Hudson River Estuary. Die-off of the fecal bacteria in surface waters is relatively rapid but the fecal bacteria can also attach to particles and settle. It is known that fecal bacteria are present in the shallow sediments but controls on their distribution have not been closely examined. The goal of this work is to examine the relationship between the concentration of fecal indicator bacteria and sediment properties including estimates of sediment age. Forty sediment surface grabs were obtained from the Hudson River Estuary. Twenty samples were collected from near the George Washington Bridge (GWB) and twenty samples from a 15 mile transect near Hudson New York. Concentrations of fecal indicator bacteria were determined by the cultured based Enterolert and Colilert tests (Idexx Laboratories) and molecular based techniques for E. coli and Bacteroides. Sediments were analyzed for total metals, total organic carbon, grain size, and gamma emitting radionuclides including Beryllium-7, Lead-210, and Cesium-137. Enterococcus was present in the samples with a geometric mean of 88 cells/g and a range of 4 to 817 cells /g. Culturable E. Coli was present in the samples with a geometric mean of 168 cells /g and a range of 5 to 2247 cells /g. Enterococcus concentrations were significantly higher (p<0.05) in the northern transect. Molecular based concentrations were determined for the GWB samples and were significantly higher than culture based concentrations. Bacteroides was present in the samples with a geometric mean of 1.1x106 copies/g and a range of 3.9x104 to 4.7x106 copies /g. Molecular E. Coli was present in the samples with a geometric mean of 3.0x106 copies/g and a range of 8.7x104 to 8.9x107 copies /g. The results clearly show that a significant amount of fecal bacteria are present in the sediments. Simple linear correlations between bacterial concentrations and sediment properties have not been observed, but more complex relationships might exist.

Batta, J.; Mailloux, B. J.; Nitsche, F. O.; Kenna, T. C.; Ferguson, A. S.; Cheung, J.; Layton, A.

2010-12-01

169

Short-term changes and longitudinal distribution of carbon metabolism in the Piauí River estuary (Sergipe, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available Net pelagic metabolism (NPM and net ecosystem metabolism (NEM were assessed by sigmaCO2 changes in three sampling stations along Piauí River estuary. At the upper estuary station, sampling was carried out over 48 h. Samples exhibited high DIN:DIP ratios. Chlorophyll-a ranged from 0.2 to 2.5 mug.l-1, being higher at the upper estuarine station than marine ones. Net pelagic metabolic rates ranged from -13.2 to 61.2 mgC.m7-2.d-1. Presence of mucilaginous algal material can explain the net mineralization. In the photic period, NPM ranged from-0.05 to 3.04 mgC.m-2h-1. NEM ranged from -7.77 to 6.65 mgC.m-2.d-1. Bottom ressuspension due to microphytobenthic flotation and a high turbidity plume inside de estuary reflected in negative metabolic rates (mineralization. Benthic metabolism was inferred by net system minus pelagic metabolism. Microphytobenthic community seems to be the main responsible for system metabolism, specially in the upper estuary, although the anthropogenic inputs exert strong long term influence.

SOUZA M. F. L. de

1999-01-01

170

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

171

Heavy metals associated with reduced sulfur in sediments from different deposition environments in the Pearl River estuary, China.  

Science.gov (United States)

Distribution of acid volatile sulfur (AVS) and the simultaneously extracted metals (SEM: Cu, Pb, Zn, Cd, Ni) in sediment profiles has been studied at five sites in Pearl River estuary, China. Of the five sampling locations, Nos.1 and 2 are in the middle shoal, Nos.3 and 4 in the west shoal and No. 5 locates to the south of the estuary. The AVS content in the sediments of the middle shoal varies in a small range (0.25-4.06 micromol g(-1)), while that of west shoal increases with depth from 0 to ultimately 26.09 micromol g(-1). The SEM concentration in the sediment profiles at location Nos. 1, 2 and 5 is generally in the range of 0.95+/-0.2 micromol g(-1) with a slight upward increase, while that in the sediment of west shallows are much higher (1.43-2.42 micromol g(-1)) with a significant upward increase, especially in the upper layer of ca. 15 cm. The observed upward increase of SEM content at all the sites implies that heavy metal contamination of sediment in the Pearl River estuary is increasing. Calculations of the excess heavy metal content which is defined by SEM-AVS molar difference suggests that the upper sediment in the Pearl River estuary, especially on the west shallows, could be a source of heavy metal contaminants and may cause toxicity to the benthos. The site-specific distribution patterns in the AVS and SEM profiles were interpreted according to the hydrogeochemistry of deposition environments. PMID:16767564

Chen, Fanrong; Yang, Yongqiang; Zhang, Derong; Zhang, Ling

2006-06-01

172

Typology Estuaries  

Typology Estuaries Environment Agency copyright and / or database right 2010. All rights reserved. This map includes data supplied under licence from: Crown Copyright and database right 2010. All rights reserved. Ordnance Survey licence number 100026380. Some river features of this map are based on…

173

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

Science.gov (United States)

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

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

2012-01-01

174

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

International Nuclear Information System (INIS)

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

2008-12-01

175

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

176

[Methane fluxes of Cyperus malaccensis tidal wetland in Minjiang River estuary].  

Science.gov (United States)

By using enclosed static chamber-gas chromatograph techniques, this paper measured the methane fluxes of Cyperus malaccensis tidal wetland in Minjiang River estuary. The diurnal variation of the methane fluxes in summer and winter were in the range of 1.29-2.93 mg x m(-2) x h(-1) and 0.06-0.22 mg x m(-2) x h(-1), respectively. The methane fluxes before flooding, in the process of flooding and ebbing, and after ebbing were 0.11-1.52 mg x m(-2) x h(-1), 0.10-1.05 mg x m(-2) x h(-1), and 0.05-1.70 mg x m(-2) x h(-1), and the monthly averaged fluxes were 0.73, 0.47, and 0.72 mg x m(-2) x h(-1), respectively. The methane fluxes peaked in September and reached the lowest in March, and were significantly lower in the process of flooding and ebbing than before flooding and after ebbing (P autumn > spring > winter. Tide was the key factor affecting the diurnal variation of the methane fluxes, while plant growth stage and temperature were the key factors determining the monthly or seasonal variation of the methane fluxes. PMID:20462027

Zeng, Cong-Sheng; Wang, Wei-Qi; Zhang, Lin-Hai; Lin, Lu-Ying; Ai, Jin-Quan; Zhang, Wen-Long

2010-02-01

177

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

178

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

International Nuclear Information System (INIS)

Fallout plutonium and radiocesium derived from both weapons testing and local reactor releases are found in the water column and sediments of the Hudson River in readily measurable amounts. The history of fallout delivery and dissolved phase runoff from the drainage basin of 80Sr, 137Cs, and /sup 239,240/Pu have been extensively documented since the mid-1950s. Sediment and water column concentrations of 134Cs, 137Cs, and /sup 239,240/Pu in the Hudson have also been documented since the mid-1960's and are summarized. Since the peak fallout years, substantial portions of the fallout radionuclides in the drainage basin have become unavailable to normal weathering processes as reflected by a measured decrease in the fallout nuclide transport to the waters of the tidal Hudson. Budget calculations indicate that plutonium may be transported into the estuary from the coastal ocean, and that desorption of radiocesium from particles has allowed a substantial fraction of radiocesium to be exported from the Hudson to marine waters. 29 references, 6 figures, 8 tables

1987-08-01

179

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

Energy Technology Data Exchange (ETDEWEB)

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

Zhu Jun [Department of Environmental, Earth and Ocean Sciences, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125-3393 (United States); Olsen, Curtis R. [Department of Environmental, Earth and Ocean Sciences, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125-3393 (United States)], E-mail: curtis.olsen@umb.edu

2009-02-15

180

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

Science.gov (United States)

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

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

2007-11-01

 
 
 
 
181

[Species composition and ecological distribution of planktonic diatoms in the Changjiang River estuary during spring].  

Science.gov (United States)

53 water samples were collected from 28 stations in typical regions where redtide frequently occurred in the Changjiang River estuary during Spring, 2002. In total, 80 diatom species and varieties belonging to 31 genera were identified, among which, genera with high species biodiversity included Coscinodiscus which contained 17 species and Pleurosigma which contained 8 species and varieties. Quantitative analysis of diatom cell density showed that Pseudo-nitzschia delicatissma (3.48 x 10(3) cells.L-1, 28.54%), Melosira sulcata (1.43 x 10(3) cells.L-1, 16.98%) and Pseudo-nitzschia pungens (0.71 x 10(3) cells.L-1, 9.85%) were dominant species, which occurred at almost all stations. Higher cell density of Pseudo-nitzschia delicatissma and Pseudo-nitzschia pungens occurred at stations along 123 degrees E, while that of Melosira sulcata occurred at stations around Changjiang River at 31-32 degrees N. The total diatom cell density ranged from 0.43 x 10(3)-23.3 x 10(3) cells.L-1, with average of 4.61 x 10(3) cells.L-1. At station DD15 located at 123 degrees E and 30.5 degrees N, the highest diatom cell density was found, which was 1.85 x 10(4) cells.L-1 at surface water layer, and 2.33 x 10(4) cells.L-1 at middle water layer (30 m) respectively. Horizontally, the diatom cell density showed scattered distribution, while vertically, it was commonly higher at surface water layer than that at middle water layer. PMID:14587319

Gao, Yahui; Yu, Qiubo; Qi, Yuzao; Zhou, Jingzhong; Lu, Douding; Li, Yang; Cheng, Changping

2003-07-01

182

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.

183

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

184

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Akira Haraguchi

2012-01-01

185

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

186

Phytosociology of planted and natural mangrove forests in the estuary of the Ostras River, Rio de Janeiro State, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available The phytosociology of planted and natural mangrove forests were compared in the estuary of the Ostras River, Rio de Janeiro State, Brazil. Vegetation sampling was performed by the plot method, and the diameter at breast height (DBH and height of individuals > 1 m tall were recorded. The results indicated that the planted forest had lower average DBH and basal area and higher density of trunks in relation to natural forest. The distribution of individuals by height class and the distribution of stems per diameter class showed that the planted forest was younger. Laguncularia racemosa and Rhizophora mangle occurred in both forests, while Avicennia schaueriana was found only in the planted forest. Laguncularia racemosa showed greater dominance and relative density at all sites analyzed, probably because it is characteristic of sites with less marine influence and the fact that the estuary had been altered by human disturbance.

Elaine Bernini

2014-03-01

187

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

188

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

189

Water Temperature, Specific Conductance, pH, and Dissolved-Oxygen Concentrations in the Lower White River and the Puyallup River Estuary, Washington, August-October 2002  

Science.gov (United States)

The U.S. Geological Survey, Washington State Department of Ecology, and Puyallup Tribe of Indians monitored water temperature, specific conductance, pH, and dissolved-oxygen concentrations in the White River at river miles 4.9 and 1.8 from August until mid-October 2002. Water diverted from the White River upstream from the monitoring sites into Lake Tapps is returned to the river at river mile 3.6 between the two sites. The same characteristics were measured in a cross section of the Puyallup River estuary at river mile 1.5 during high and low tides in September 2002. In late August, maximum daily water temperatures in the White River of 21.1oC (degrees Celsius) at river mile 4.9 and 19.6oC at river mile 1.8 exceeded the water-quality standard of 18oC at both monitoring sites. In mid-September, maximum daily water temperatures at river mile 4.9 exceeded the standard on 5 days. From August 2-25, water temperatures at both monitoring sites were similar and little or no water was discharged from Lake Tapps to the White River. Increases in water temperature at river mile 1.8 in late September and early October were caused by the mixing of warmer water discharged from Lake Tapps with cooler water in the White River. Specific conductance in the White River usually was lower at river mile 1.8 than at river mile 4.9 because of mixing with water from Lake Tapps, which has a lower specific conductance. Maximum values of pH in the White River at river mile 4.9 often exceeded the upper limit of the water-quality standard, 8.5 pH units, from early September until mid-October, when turbidity decreased. The pH standard was not exceeded at river mile 1.8. Dissolved-oxygen concentrations in the White River were often lower at river mile 1.8 than at river mile 4.9 because of mixing with water discharged from Lake Tapps, which has lower dissolved-oxygen concentrations. The lowest concentration of dissolved oxygen observed was 7.9 mg/L (milligrams per liter) at river mile 1.8. The lower limit allowed by the water-quality standard is 8 mg/L. Concentrations of dissolved oxygen measured in a cross section of the Puyallup River estuary at high tide on September 12, 2002, ranged from 9.9 to 10.2 mg/L in fresh water at the surface and from 8.1 to 8.4 mg/L in salt water near the riverbed. These values were within limits set by Washington State water-quality standards for dissolved oxygen of 8 mg/L in fresh water and 6 mg/L in marine water.

Ebbert, James C.

2003-01-01

190

Sources, distribution, and mobility of plutonium and radiocesium in soils, sediments and water of the Hudson River Estuary and watershed  

International Nuclear Information System (INIS)

Results of 239 240Pu, 238Pu and 137Cs measurements are reported for soil cores sampled within the watershed, for many sediment cores and surface dredge samples taken along the length of the Hudson River Estuary and for water samples collected on a continuous basis in both fresh and estuarine reaches. Accumulations of 239 240Pu and 137Cs measured within sediment cores taken from discrete regions of the river-estuary were summed to arrive at total sediment inventories of 1.6 +/- 0.7 Ci and 53 +/- 20 Ci, respectively. The variability observed in the sediment accumulation of radionuclides is discussed in terms of the physical and chemical characteristics of the river-estuary. Plutonium-239,240 and 137Cs were similary distributed in sediments and water sampled from fresh water reaches of the Hudson with activity ratios (i.e., 239 240Pu/12number7Cs) ranging from 0.01 to 0.03. Distribution coefficients, which were determined both in vitro and in situ were similar for both nuclides (i.e., from 1 x 105 to 3 x 105 L.kg-1) in fresh water, but diverged significantly (as a result of increased 137Cs solubility) in brackish waters that exhibited chlorinities in excess of 1-2 g Cl-.L-1. The concentrations of 239 240Pu and 137Cs observed in fresh water samples were primarily functions of the suspended load. Approximately 60-70% of the annual downstream transport of 239 240Pu and 137Cs calculated during 1980 and 1981 (i.e., 4 +/- 0.5 mCi and 515 +/- 84 mCi, respectively) was associated with suspended particulates greater than or equal to 0.45 ?m. An empirical model was developed to determine the rates of vertical migration of these nuclides in soils of the watershed

191

Dietary Studies on the Predatory Fishes of the Norman River Estuary, with Particular Reference to Penaeid Prawns  

Science.gov (United States)

The predatory fish community and their prey in the Norman Rivere estuary, Gulf of Carpentaria Australia, are compared with the communities of other tropical inshore areas, to investigate patterns of predation in tropical inshore areas particularly in relation to penaeid prawns. Abiotic factors (turbidity, freshwater input) and diversity of habitat types affect the composition of both prey and predator communities, resulting in large differences in the communities of tropical inshore waters. The stomach contents of 2059 predatory fish from the Norman River estuary were analysed over four sampling trips in the wet and dry seasons. The stomachs of 61% (1255 fish) of 54 species contained a total of 676·2 g (dry weight) of food, while 39% (804 fish) were empty. Teleosts were the main component of the diet (by dry weight) of 13 of the 22 species analysed, followed by annelids for two species. Five species had only teleosts in their stomachs. Most predator species ate benthic or bentho-pelagic prey, while three species— Rhizoprionodon taylori, Scomberoides commersonianusand Leptobrama mulleri—ate mainly pelagic prey. Although 19 species ate some penaeids, only Polydactylus sheridaniate little else. This species, Lates calcariferand Eleutheronema tetradactylumate 94·5% of all the penaeid prey and 97·9% of all the commercially important penaeid prey recorded in the study. Penaeid predation indices (calculated from gillnet catch rates, proportion of penaeids in the diet and a consumption rate of 3% body weight per day) were 0·23 g of penaeid per net-metre per day for P. sheridani, 0·15 for L. calcariferand 0·03 for E. tetradactylum. Commercially important penaeid predation indices were 0·11, 0·13 and 0·01, respectively. These values are intermediate between those previously recorded for the main penaeid predators in other inshore areas of the Gulf of Carpentaria (Embley River estuary and Groote Eylandt).

Salini, J. P.; Brewer, D. T.; Blaber, S. J. M.

1998-06-01

192

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

Directory of Open Access Journals (Sweden)

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

Hong-Li Li

2009-01-01

193

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.

194

Arbuscular mycorrhizal relations of mangrove plant community at the Ganges river estuary in India.  

Science.gov (United States)

Mangroves are climax formation of hydrohalophytes inhabiting estuarine or marine salt marshes in the tropics and subtropics. As a terrestrial plant community inhabiting tidally inundated estuarine or marine sediments, mangroves show considerable adaptation to salinity, water-logging and nutrient stress. Thirty-one species of mangrove and mangrove associates and 23 species of transported flora, belonging to 25 families at four physiographic stages of succession of the mangrove plant community at the terminal part of the Ganges river estuary in India were examined for arbuscular mycorrhizal (AM) root association. Dominant members of the mangrove plant community were all AM, mostly with 'Paris' type structures. Many of the known non-mycotrophic plant families, except the Cyperaceae, also showed AM association, with intracellular hyphae and vesicles as the most discernible endophyte structures. Intensity of AM colonization varied both with the species and situations of their occurrence, being more intense and also more extensive in less saline dry ridge mangroves than in more saline formative and developed swamp mangroves. Introduced exotic trees on the ridges and embankments were infected by AM, but less than the declining mangroves in the same location. Seven species of AM fungi in common with those of the upstream mesophytic plants were isolated from root-free rhizosphere soils of the mangroves, three of which predominated in root association. These species, individually and as mixtures, infected roots of salinity tolerant herbs and trees in both locational silt and upstream alluvial soil with obvious improvements in their biomass yield and phosphorus nutrition. AM infective potential of root-free rhizosphere soils of the dominant members of the mangrove community were negatively related to salinity level of the sediment soil of the successional stages. The evidences of AM association of mangroves and other salt marsh plants obtained here and those reported elsewhere are discussed. PMID:12189470

Sengupta, Anjan; Chaudhuri, Subhendu

2002-08-01

195

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

International Nuclear Information System (INIS)

Isotopes of plutonium (Pu), cesium (Cs), and cobalt (Co) introduced into the Hudson River Estuary from fallout deposition, the erosion of fallout-contaminated surface soils, and nuclear reactor effluent (isotopes of Cs and Co only) have been measured in water column samples collected from 1975 to 1980. The major conclusions drawn from the work are that: for water samples collected by the two laboratories over similar time periods, the mean concentrations of nonfilterable /sup 239,240/Pu (<0.45 ?m) were identical at 0.13 fCi/I; mean concentrations of both "1"3"7Cs and /sup 239,240/Pu in suspended particulates were more divergent at 2270 +/- 920 pCi/kg (+/- 1 SD) and 1430 +/- 430 pCi/kg for "1"3"7Cs, and 19 +/- 8 pCi/kg and 12 +/- 4 pCi/kg for /sup 239,240/Pu. The behavior of /sup 239,240/Pu and "1"3"7Cs within the water column is shown to diverge within brackish waters. Specifically, the magnitude of the "1"3"7Cs distribution-coefficient (K/sub d/) can be expressed as an inverse power function of the chloride ion concentrations for chlorinities between 0.1 and 4 g Cl"-/l. No difference in the /sup 239,240/Pu k/sub d/ has been observed between fresh and brackish waters. Based on the expected inventories of /sup 239,240/Pu and "1"3"7Cs within watershed soils, the current downstream transport of these radionuclides represents fractional mobilization rates on the order of 1-4 (x 10"-"4) per year

1985-01-01

196

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-12-15

197

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

198

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

Directory of Open Access Journals (Sweden)

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

Tim Webster

2014-03-01

199

RELATIONSHIP BETWEEN FECUNDITY AND BIOMETRIC INDICES OF THE SILVER CATFISH Chrysichthys nigrodigitatus (Lacepede) IN THE CROSS RIVER ESTUARY, NIGERIA  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The relationship between fecundity and biometric parameters of silver catfish, Chrysichthys nigrodigitatus from the Cross River estuary was studied between July and October 2012. A total of 120 gravid female fish were examined. The results show that fecundity of C. nigrodigitatus ranged between 975 eggs for fish of total length 23.2 cm, total weight 99 g, ovary weight 15 g and mean egg diameter 2.43 mm to 11,280 eggs for fish of total length 50.0 cm, total weight 1420.0 g, ovary weight 80.0 g...

2013-01-01

200

From river valley to estuary : the early-mid Holocene transgression of the Rhine-Meuse valley, The Netherlands  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Most present day estuaries formed within incised fluvial valleys, created during the last glacial, that drowned during post-glacial sea-level rise. The sedimentary archive of the associated river-mouth areas contains important information on estuarine evolution under different rates of sea-level rise. This thesis presents a study on the development of the mouth of the Rhine-Meuse system in the Rotterdam area, western Netherlands, between 12000-6000 BP. During the study tens of thousands of co...

Hijma, M. P.

2009-01-01

 
 
 
 
201

Cadmium, manganese, nickel and lead contents in surface sediments of the lower Ulla River and its estuary (northwest Spain)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

[EN] The authors determined the total contents of cadmium, manganese, nickel and lead in 16 surface sediment samples along the last 7 km of the Ulla River and in its estuary. Prior to chemical analysis, the grain-size fractions below 500, 63 and 2 ?m were separated. The metal concentrations were analysed in the fraction below 63 ?m, and in selected samples from the clay fraction (< 2 ?m). The soil samples were digested with a HF + HNO3 + HCl mixture and the total concentrations...

Prego, R.; Belzunce Segarra, Mari?a Jesu?s; Helios-rybicka, E.; Barciela, Mª Del Carmen

1999-01-01

202

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

203

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

204

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.

205

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

206

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

207

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

Science.gov (United States)

Between 1972 and 2009, evidence of red tide outbreaks in the Yangtze River Estuary and adjacent waters was collected. A geographic information system (GIS) was used to analyze the temporal and spatial distribution of these red tides, and it was subsequently used to map the distribution of these events. The results show that the following findings. (1) There were three red tide-prone areas: outside the Yangtze River Estuary and the eastern coast of Sheshan, the Huaniaoshan-Shengshan-Gouqi waters, and the Zhoushan areas and eastern coast of Zhujiajian. In these areas, red tides occurred 174 total times, 25 of which were larger than 1000 km(2) in areal extent. After 2000, the frequency of red tide outbreaks increased significantly. (2) During the months of May and June, the red tide occurrence in these areas was 51% and 20%, respectively. (3) Outbreaks of the dominant red tide plankton species Prorocentrum dong-haiense, Skeletonema costatum, Prorocentrum dantatum, and Noctiluca scientillan occurred 38, 35, 15, and 10 times, respectively, during the study interval. PMID:23628547

Liu, Lusan; Zhou, Juan; Zheng, Binghui; Cai, Wenqian; Lin, Kuixuan; Tang, Jingliang

2013-07-15

208

Spatial and seasonal distributions of estrogens and bisphenol A in the Yangtze River Estuary and the adjacent East China Sea.  

Science.gov (United States)

Surface water and sediments in the Yangtze River Estuary (YRE) and the adjacent East China Sea (ECS) were sampled to investigate the spatial and seasonal distributions of Estrone (E1), 17?-estradiol (E2), 17?-ethinylestradiol (EE2) and bisphenol A (BPA). E1 and BPA were the dominant compounds detected. The zones of the highest E1 and BPA concentrations in water were located at the mouth of the Huangpu River and the outfalls of wastewater treatment plants. The zones of the highest concentrations in sediments were mainly located in the down reach of the estuary and the adjacent sea. The relationship between E1 and BPA in sediments with those in water was not significant (BPA: r=0.16, p=0.21; E1: r=0.18, p=0.24), but positive correlations with the total organic carbon (TOC) contents of sediments (BPA: r=0.57, pcluster analysis further indicated the spatial distributions of BPA and E1 in sediments were obviously affected by TOC and sediment particle sizes, whilst the distributions varied slightly with seasons. PMID:24997937

Shi, Jianghong; Liu, Xiaowei; Chen, Qingcai; Zhang, Hui

2014-09-01

209

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

210

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-10-15

211

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

Science.gov (United States)

Magnetotactic bacteria (MB) are motile organisms commonly found around the oxic-anoxic-interface (OAI) in sediments and stratified water columns. Magnetite and greigite crystals synthesized by MB intracellularly, termed magnetosomes, can be preserved in sediments as magnetofossils. Changes in OAI thickness (due to changes in temperature, clathrate dissociation & methane oxidation, organic carbon supply/oxidation, or sedimentation rate) would produce proportional changes in MB population and sedimentary magnetofossil concentration. While potentially useful as an oxygenation proxy, magnetofossil quantification techniques and variables controlling their preservation in sediments need to be better understood. Most prior work focused on cultured magnetite-MB and sediment mixtures while studies of greigite-MB (found just below the OAI in the sulfidic hypolimnion) is lacking because axenic cultures do not exist. To address these issues, we study wild magnetite- and greigite-MB from the seasonally stratified Pettaquamscutt River Estuary Upper Basin (RI, USA) as a function of water depth, d. Transmission electron microscope imaging of 21 MB (377 magnetosomes) revealed a complexity in wild MB not found in cultures. From d=3.9 m-7.0 m, live-cell assays confirmed the presence of multiple MB morphotypes, both north- (majority) and south-seeking (minority), and a few magnetic protists. Based on a previous microscopy study just 1.4 km south of Upper Basin (Bazylinski et al., 1995), magnetite-MB are expected for d6.0 m. Coercivity distributions for all depths are characterized by a small variance, reflecting uniformity in magnetosome size. Interestingly, despite changing from dominant magnetite to greigite-MB with increasing depth, the median coercivity remained largely unchanged. Median coercivity is therefore not diagnostic of magnetosome mineralogy. We also report ferromagnetic resonance spectroscopy (FMR) results. The first derivative of the absorption spectra for dsamples with a similar FMR specturm have also been observed. Additionally, in contrast with the sharply defined FMR parameters measured from magnetite-MB cultures, a wide range of parameters was found for the water column samples (asymmetry=0.8-1.3, alpha=0.27-0.34, geff=1.93-2.18, and linewidth=93-152 mT). Caution should therefore be taken when using FMR for magnetosome detection.

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

2013-12-01

212

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

213

Variations in Branched Tetraether Lipids in the Lower Pearl River and Estuary: Impact on bGDGT Proxies  

Science.gov (United States)

Branched glycerol dibiphytanyl glycerol tetraethers (bGDGTs) are known as bacterial lipids that occur widely in terrestrial environments, particularly in peat bogs and soil. A number of proxies have been developed using bGDGTs, which have been applied to marine sediments as terrestrial signals. We examined the abundance and distribution of bGDGTs in both core- (C) and polar- (P) lipid (L) fractions from the water column and surface sediments in the lower Pearl River (PR) and estuary. A number of soil samples in the lower PR drainage basin were also collected. The results showed in situ production of bGDGTs and difference in abundance and structure of bGDGTs between the water column and surface sediments. The average PL accounted for over 50% of total bGDGTs in the former but less than 10% in the latter, suggesting that the water column contains a significant population of living organisms that produce bGDGTs whereas the surface sediment contains mostly bGDGTs from nonliving cells. The soil samples also showed predominance of C-bGDGTs with average P-bGDGTs accounting for about 8% of total bGDGTs. The abundance of C-bGDGTs and P-bGDGTs decreased sharply from the lower PR to the estuary in the water column; whereas in surface sediments, only C-bGDGTs showed significant decrease. The bGDGT-based proxies (BIT, CBT, and MBT) showed different patterns of variation with BIT decreasing in both C- and P- lipid fractions from the lower PR to estuary and MBT in the C- lipid fraction remaining constant. These results indicate that the lower PR and estuary is a dynamic system, which experiences considerable changes in the abundance and structure of bGDGTs. This study also indicates the complexity of the estuary system and cautions need to be excised when using bGDGT-based proxies for paleo-continental or soil pH studies in continental margins.

Zhang, C.; Wang, J.; Wei, Y.; Zhu, C.; Huang, L.; Dong, H.

2011-12-01

214

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)

1980-01-01

215

Levels of Chromium Contamination in the Estuary of the Iraja River (Guanabara Bay) and Experimental Incorporation of exp 51 Cr in Barnacles (Balanus SP).  

Science.gov (United States)

Levels were determined of chromium contamination in the estuary of Iraja River, produced by an electroplating industry located 3 km upstream the study area. Uptake-and release kinetics of Cr(VI) and Cr(III) in barnacles (Balanus sp.) were studied. Samples...

M. D. M. V. Weerelt

1982-01-01

216

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

Science.gov (United States)

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

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

1981-01-01

217

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 "2"3"8Pu and "2"3"9,"2"4"0Pu (fallout-derived), "1"3"4Cs and "6"0Co (reactor-released), and "1"3"7Cs (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 "2"3"9,"2"4"0Pu 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 "1"3"7Cs, "1"3"4Cs and "6"0Co delivered to the estuary have been retained on the fine particles which accumulate at a rapid rate in the harbor. (orig./HAE)

1981-01-01

218

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

219

Mercury in some higher aquatic plants and plankton in the estuary of the River Kokemaenjoki, southern Finland  

Energy Technology Data Exchange (ETDEWEB)

Eight species of higher aquatic plants, and seston and zooplankton were collected from 16 sampling sites in the eutrophic estuary of the River Kokemaenjoki and analyzed for mercury. The Kokemaenjoki has a length of 110 km and a mean discharge of 206 cu m/s. The quality of water is poor as it receives agricultural runoff, and waste waters from the wood processing, metal and chemical industries and domestic effluents from urban centers. The mean Hg concentration in the aquatic plants was 0.43 ppM of dry weight, in the seston 0.71 ppM and in the zooplankton 1.19 ppM. Among the aquatic plants, the highest Hg values were recorded in small bottom-rooted submerged Eleocharis acicularis (0.77 ppm) and Elatine spp. (0.80). The lowest Hg concentrations were found in the floating leaves of Nuphar lutae (0.04 ppm). The Hg concentrations of aquatic plants in the estuary were 5-20 times as high as those reported from unpolluted watercourses in Finland. The Hg contents of the seston and zooplankton were 5-20 times as high as the natural background levels. Submerged aquatic plants, seston and zooplankton appeared to be valuable indicators of mercury contamination in the delta area. The dredging operations planned for this area could harm the biota by releasing more Hg from the sediments to the overlying water and thus increasing the amounts circulating in the food webs. 31 references, 2 figures, 3 tables.

Cajander, V.R.; Ihantola, R.

1984-01-01

220

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

 
 
 
 
221

Seasonal changes in interstitial salinities and seasonal movements of subtidal benthic invertebrates in the Fraser River estuary, B.C.  

Science.gov (United States)

The subtidal benthic fauna of the lower Fraser River, a salt-wedge estuary, was sampled monthly from June 1977 to August 1978 in mud substrates at six stations ranging from oligohaline to polyhaline. Subtidal interstitial salinities were also measured and were related to the seasonal distribution of the estuarine benthic fauna. Interstitial salinities of silty sediments do not vary diurnally, but the transition zone between salt and fresh interstitial water is cyclically shifted up- and downstream in relation to freshwater discharge, leading to seasonal shifts in the distribution of benthic infaunal species. Seasonal shifts are shown to occur in the oligochaetes Limnodrilus hoffmeisteri, Tubifex tubifex, Tubificoides gabriellae, Paranais litoralis, Specaria fraseri, Nais communis and Nais elinguis, and of the polychaetes Eteone longa, Amphicteis sp. and Polydora kempi japonica. These species comprised over 25% of the total taxa collected and over 60% of the individuals collected. The data on other species distributions do not conflict with the hypothesis of cyclic changes related to seasonal interstitial salinities. The changes vary in extent in relation to runoff, and appear to be a feature of salt-wedge estuaries in general.

Chapman, Peter M.; Brinkhurst, Ralph O.

1981-01-01

222

Effect of Migration Pathway on Travel Time and Survival of Acoustic-Tagged Juvenile Salmonids in the Columbia River Estuary  

Energy Technology Data Exchange (ETDEWEB)

Off-channel areas (side channels, tidal flats, sand bars, and shallow-water bays) may serve as important migration corridors through estuarine environments for salmon and steelhead smolts. Relatively large percentages (21-33%) of acoustic-tagged yearling and subyearling Chinook salmon and steelhead smolts were detected migrating through off-channel areas of the Columbia River estuary in 2008. The probability of survival for off-channel migrants (0.78-0.94) was similar to or greater than the survival probability of main channel migrants (0.67-0.93). Median travel times were similar for all species or run types and migration pathways we examined, ranging from 1-2 d. The route used by smolts to migrate through the estuary may affect their vulnerability to predation. Acoustic-tagged steelhead that migrated nearest to avian predator nesting colonies experienced higher predation rates (24%) than those that migrated farthest from the colonies (10%). The use of multiple migration pathways may be advantageous to out-migrating smolts because it helps to buffer against high rates of mortality, which may occur in localized areas, and helps to minimize inter- and intraspecific competition.

Harnish, Ryan A.; Johnson, Gary E.; McMichael, Geoffrey A.; Hughes, Michael S.; Ebberts, Blaine D.

2012-02-01

223

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

Science.gov (United States)

The stocks of Southern sea lions (Otaria flavescens, SSL) and South American fur seals (SAFS) that breed on coastal islands of Uruguay constitute the most important focal concentration of pinnipeds in South America, with a significant increase in SAFS and a steady decrease of SSL over the past decades. Because females are a key element of population dynamics and no information exists on the post-breeding pup rearing period, we studied the foraging patterns of SSL females in the La Plata River Estuary (LPRE) during mid and late lactation (late austral autumn and winter), analyzing the foraging performance, geographic coverage and ontogenetic differences in foraging strategies for a period of 1-5 months. At-sea movements of 22 SSL females (6 subadults and 16 adults) from Isla de Lobos (IL, 35°01'28"S-54°52'59"W, Uruguay) were monitored using satellite transmitters (SPOT4, SPOT5 and STDR-S16, Wildlife Computers) in 2007 and 2010. An algorithm [McConnell, B.J., Chambers, C., Fedak, M.A., 1992. Foraging ecology of southern elephant seals in relation to the bathymetry and productivity of the Southern Ocean. Antarct. Sci. 4, 393-398.] with a maximum transit speed of 3 m s-1 was applied to the Argos information, resulting in a total of 2522 filtered locations. A daily mean of 3.5±1.74 filtered locations per animal was received. One hundred and eighty three foraging trips (FT) were recorded with no significant differences (p<0.05) between subadults and adults in the duration of FT (6.1±3.15 day), distance traveled per FT (237.2±105.25 km), mean distance from IL (57.2±25.90 km), maximum straight line (Spider) distance (100.2±41.40 km) and transit speed (1.1±1.04 m s-1). SSL showed directional fidelity to foraging sites, indicated by high mean vector (r) values (0.74±0.14) calculated from FT mean bearings. Kernel ranges for 50% and 95% of all FT locations were 5420 km2 and 36,222 km2, respectively, and the extension of the foraging areas appeared to be influenced by a combination of bathymetry and ecological boundaries within LPRE. Regardless of their reproductive condition, females showed a strong fidelity to IL, and their foraging activity was restricted to relatively shallow areas (10-100 m) on the continental shelf. During autumn and winter, SSL females made significantly longer FTs than during the breeding season, when lactating females decrease FT duration by increasing transit speed but maintain a similar spatial coverage compared with FT later in lactation. Although several aquatic areas of high priority for conservation in LPRE have been identified and proposed, only 15% of the foraging habitat of SSL females is currently included in these areas. This emphasizes the importance of the inclusion of the at-sea foraging distributions of central point foragers in marine protected areas. If conservation efforts focus only on coastal breeding concentrations, key elements of the life cycle are excluded with potential unpredictable effects.

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

2013-04-01

224

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

225

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)

1975-06-02

226

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

Directory of Open Access Journals (Sweden)

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

José Amorim Reis-Filho

2010-06-01

227

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

Directory of Open Access Journals (Sweden)

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

Sang-Hun Jeong

2013-03-01

228

Multi-way analysis for decadal pollution trends assessment: The Guadalquivir River estuary as a case study.  

Science.gov (United States)

Alongside history, human activities have contributed to the deployment of environmental quality. In particular, during the last decades the problem of water preservation has gained increasing attention. Statistical analysis is essential to analyze environmental data and to identify trends of pollutants over space and time. Usually applied techniques for data treatment are based on the organization of data in a two-way array, missing some shades on pollutants distribution. This fact supports the use of multi-way techniques, which allow the analysis of the results through different directions at the same time. For Three Modes Principal Components Analysis (3MPCA) a principal components analysis is conducted using three modes and a "core" matrix that allows assessing their interactions. In the case of environmental studies, it offers information about the spatial-temporal evolution of pollutants in a certain water body. The Guadalquivir River estuary has been used as a model system. It is a representative human influenced system, where different pollution inputs have been characterized. In this study, decadal evolution of pollutants has been discussed, to evaluate among others the effects of EU legislation on river water quality. The aim of this work is the establishment of the evolution, during the last decade, of nutrients and metals ultra-traces distribution in an estuary affected by anthropic activities. As examples, Pb and PO4(3-) show a trend to decrease their weight on water pollution, total suspended solids (TSS) behavior is related with massive rain events, and the rising of new technologies appears as a source of emerging pollutants as Co in urban-industrial areas. PMID:24997899

López-López, José A; Mendiguchía, Carolina; García-Vargas, Manuel; Moreno, Carlos

2014-09-01

229

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 tot...

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

2011-01-01

230

Assessment of microbial dynamics in the Pearl River Estuary by 16S rRNA terminal restriction fragment analysis  

Science.gov (United States)

We have evaluated the feasibility of using the terminal restriction fragment length polymorphism (T-RFLP) pattern of polymerase chain reaction (PCR) amplified 16S rRNA sequences to track the changes of the free-living bacterial community for the Pearl River Estuary surface waters. The suitability of specific PCR primers, PCR bias induced by thermal cycles, and field-sampling volumes were critically evaluated in laboratory tests. We established a workable protocol and obtained TRF patterns that reflected the changes in the bacterial population. The temporal dynamics over a 24 h period were examined at one anchored station, as well as the spatial distribution pattern of the bacterial community at several stations, covering the transects along the river discharge direction and across the river plume. The TRF pattern revealed 9 dominant bacterial groups. Changes in their relative abundance reflecting the changes in the bacterial community composition were documented. Many culturable species were isolated from each field sample and a portion of the 16S rRNA gene for each species was sequenced. The species was identified based on sequence data comparison. In this region, the dominant species belong to the ?-subdivision of proteobacteria and the Bacillus/Clostridium group of Firmicutes. We also detected the wide spread distribution of Acinetobacter spp.; many of these species are known nosocomial pathogen for humans.

Wu, Madeline; Song, Liansheng; Ren, Jianping; Kan, Jianjun; Qian, Pei-Yuan

2004-10-01

231

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

2007-07-01

232

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

Science.gov (United States)

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

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

2010-06-01

233

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

Scientific Electronic Library Online (English)

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

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

234

Reproductive swarming of sympatric nereidid polychaetes in an estuary of the Omuta-gawa river in Kyushu, Japan, with special reference to simultaneous swarming of two Hediste species.  

Science.gov (United States)

Habitat differences and spatial and temporal separation in reproductive swarming among sympatric nereidid polychaetes were examined in an estuary of the Omuta-gawa River, Kyushu, Japan by annual periodical sampling from December 2003 to January 2005. Benthic adults of Tylorrhynchus osawai and Hediste diadroma occupied mainly the upper reaches of the estuary, whereas those of H. japonica usually inhabited the middle reaches, though their distributions overlapped. Reproductive swarming of mature adults occurred in the estuary just after high tide at night during spring tides in four nereidids: H. japonica (in the middle and lower reaches from late December to late February), H. diadroma (throughout the whole estuary from middle December to late April), T. osawai (in the middle reaches and another estuary from late October to late December), and Nectoneanthes oxypoda sensu Imajima, 1972 (in the lower reaches in late April and early May). This result shows that temporal separation of reproductive swarming may act as a reproductive isolation mechanism among these nereidids, except for H. japonica and H. diadroma. Simultaneous swarming and mass-spawning of the two Hediste species were commonly observed in the middle and lower reaches from late December to early February, suggesting the absence of a pre-spawning barrier to reproductive isolation between them. We found no difference in spawning behavior between H. japonica and H. diadroma. Males of both species seemed to participate in swarming earlier than females. PMID:16603813

Hanafiah, Zazili; Sato, Masanori; Nakashima, Hidetoshi; Tosuji, Hiroaki

2006-02-01

235

Biogeochemistry of a tropical river affected by human activities in its catchment: Brantas River estuary and coastal waters of Madura Strait, Java, Indonesia  

Science.gov (United States)

On a global scale tropical SE Asia is critical in terms of fluvial nutrient and sediment input into the ocean as well as in terms of human modifications of the coastal zone altering these inputs. In order to obtain information on the biogeochemistry of the Brantas River estuary and adjacent coastal waters of the Madura Strait in eastern Java, Indonesia, a densely-populated area which is strongly affected by human activities in the river catchment, we investigated water, suspended matter and sediments from estuarine and coastal waters and plants and soils from the catchment collected during the dry season. Water samples were analyzed for dissolved nutrients and phytoplankton abundance and composition. Suspended matter, sediment, plant and soil samples were analyzed for carbon, nitrogen, amino acids and stable carbon and nitrogen isotopes. Nutrient concentrations were high in the river and then decreased rapidly seaward. Runoff from agricultural soils may be a major nutrient source. Phytoplankton was dominated by diatoms and most abundant in the estuarine mixing zone. A fairly high phytoplankton abundance despite nitrate-depletion and an N/P ratio <4 in coastal waters indicates additional nitrogen sources. Biogeochemical characteristics and stable isotopes indicate the autochthonous origin of suspended organic matter (OM) during the dry season. Major part of the fluvial input appears to be trapped in the inner estuary. Similar information obtained from the analysis of sediments suggests seasonal differences in the quantity and origin of suspended sediments and OM transported by the river with high inputs into coastal waters during the rainy season, the period of peak river discharge. The amino acid composition in combination with stable isotopes indicates agricultural soils to be a major OM source during that time. A high proportion of amino acid-bound nitrogen in suspended matter and sediments and the presumed sources of dissolved nitrogen other than nitrate to sustain primary productivity in the coastal zone suggest that organic nitrogen may play a more important role for coastal food webs and the nitrogen cycle in tropical regions than previously thought.

Jennerjahn, T. C.; Ittekkot, V.; Klöpper, S.; Adi, Seno; Purwo Nugroho, Sutopo; Sudiana, Nana; Yusmal, Anyuta; Prihartanto; Gaye-Haake, B.

2004-07-01

236

Partitioning the effects of environmental and spatial heterogeneity on distribution of plant diversity in the Yellow River Estuary.  

Science.gov (United States)

For successful conservation and restoration of biodiversity, it is important to understand how diversity is regulated. In the ecological research community, a current topic of interest is how much of the variation in plant species richness and composition is explained by environmental variation (niche-based model), relative to spatial processes (neutral theory). The Yellow River Estuary (YRE) is a newly formed and fragile wetland ecosystem influenced by both the Yellow River and Bohai Bay. Here, we applied variance partitioning techniques to assess the relative effects of spatial and environmental variables on species richness and composition in the YRE. We also conducted a species indicator analysis to identify characteristic species for three subestuaries within the YRE. Partial redundancy analysis showed that the variations in species richness and composition were explained by both environmental and spatial factors. The majority of explained variation in species richness and composition was attributable to local environmental factors. Among the environmental variables, soil salinity made the greatest contribution to species abundance and composition. Soil salinity was the most important factor in the Diaokou subestuary, while soil moisture was the most important factor influencing species richness in the Qingshui and Chahe subestuaries. The combined effects of soil salinity and moisture determined species richness and composition in the wetlands. These results increase our understanding of the organization and assembly of estuarine plant communities. PMID:22744185

Yuan, Xiu; Ma, Keming; Wang, De

2012-06-01

237

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

238

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.

239

Heavy metal pollution in the Guadiamar river and the Guadalquivir estuary (South West Spain)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Guadalquivir river is the most important course of water of South West Spain. Its tributary, the Guadiamar river, joins the Guadalquivir near its mouth at C~diz Gulf in the Spanish South Atlantic coast, just after skirting the marshy part of the Do~ana National Park. The upper Guadiamar river receives through its tributary the Agrio river the drainage water from an opencast-worked polymetallic sulphide deposit and the effluents from a plant for the treatment and concentration of mineral. ...

Cabrera, Francisco; Soldevilla, Marina; Cordo?n, Rosario; Arambarri, Pablo

1987-01-01

240

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The mangrove swamp soils of the Cross River estuary are suitable for intensive rice cultivation because of ample water supply, large level units and high inherent fertility. However, because water is abundant, rainfall does not determine the sowing period. Field studies were conducted in 2006 and 2007 at Obufa Esuk Orok adjacent the University of Calabar Teaching and Research Farm to determine the best seeding date for two salt-tolerant rice varieties grown on a mangrove swamp soil in the Cro...

2012-01-01

 
 
 
 
241

Challenges and opportunities for the business sector in the fight against poverty : the case of Brazil’s Amazon River estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper explores the actions and strategies of three companies, and the dilemmas and bottlenecks they faced in their attempts to contribute to sustainability and poverty alleviation through business operations in the Amazon River Estuary. The results of the paper are based on three case studies carried out by the Royal Tropical Institute (KIT) using a quick-scan approach, as part of KIT’s research into corporate social responsibility from the perspective of social and gender equity.

Barney Gonzalez, M. J.; Meirelles, J.

2008-01-01

242

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1989-05-01

243

Long-term monitoring of metal pollution in sediments from the estuary of the Nerbioi-Ibaizabal River (2005-2010)  

Science.gov (United States)

This work aims to investigate the spatial and temporal distribution of trace metals in sediment samples taken from the Nerbioi-Ibaizabal River estuary (Bilbao, Basque Country) over the course of a long-term surveillance monitoring programme from 2005 to 2010. Sediment Quality Guidelines (SQGs) and the geoaccumulation indexes (Igeo) were used to assess the environmental risk posed by metal content in the estuary sediment. Sediment was collected at eight different sites in the estuary every three months over the period of investigation. A total of 14 elements (Al, As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, V and Zn) were selected and the concentration of each was measured in all samples. Additionally, conductivity, pH and the concentration of carbonate, total organic carbon and fulvic and humic acids were also measured in those samples collected in sampling campaigns from March 2006 to October 2008. The concentration of most of the metals systematically decreased over the period of investigation. There are still some points of the estuary (those located in the surroundings of the Gobela and Galindo tributaries), however, where concentrations of As, Cd, Cu, Pb and Zn are significantly higher than the background values estimated for the area. According to the mean Effects Range Median quotients (mERMqs) calculated for these sites, sediments may still pose a toxicological threat to living organisms. Metal content in inner estuary sediment is low. Specific point sources of metals to the estuary, together with background contamination of diffuse origin, are probably responsible for this situation.

Gredilla, Ainara; Fdez-Ortiz de Vallejuelo, Silvia; Arana, Gorka; de Diego, Alberto; Madariaga, Juan Manuel

2013-10-01

244

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.

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

245

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

Directory of Open Access Journals (Sweden)

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

Luci C.C. Pereira

2010-06-01

246

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

International Nuclear Information System (INIS)

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

1979-01-01

247

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

248

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

Directory of Open Access Journals (Sweden)

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

O.J. Shiyam

2012-01-01

249

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

Energy Technology Data Exchange (ETDEWEB)

The objective of this work is to estimate chlorophyll-a (chl-a) concentration in the Pearl River estuary in China. To test the performance of algorithms for the estimation of the chl-a concentration in these productive turbid waters, the maximum band ratio (MBR) and near-infrared-red (NIR-red) models are used in this study. Specific focus is placed on (a) comparing the ability of the models to estimate chl-a in the range 1-12 mg m{sup -3}, which is typical for coastal and estuarine waters, and (b) assessing the potential of the Moderate Resolution Imaging Spectrometer (MODIS) and Medium Resolution Imaging Spectrometer (MERIS) to estimate chl-a concentrations. Reflectance spectra and water samples were collected at 13 stations with chl-a ranging from 0.83 to 11.8 mg m{sup -3} and total suspended matter from 9.9 to 21.5 g m{sup -3}. A close relationship was found between chl-a concentration and total suspended matter concentration with the determining coefficient (R{sup 2}) above 0.89. The MBR calculated in the spectral bands of MODIS proved to be a good proxy for chl-a concentration (R{sup 2} > 0.93). On the other hand, both the NIR-red three-band model, with wavebands around 665, 700, and 730 nm, and the NIR-red two-band model (with bands around 665 and 700 nm) explained more than 95% of the chl-a variation, and we were able to estimate chl-a concentrations with a root mean square error below 1 mg m{sup -3}. The two- and three-band NIR-red models with MERIS spectral bands accounted for 93% of the chl-a variation. These findings imply that the extensive database of MODIS and MERIS images could be used to quantitatively monitor chl-a in the Pearl River estuary.

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

2011-04-15

250

Spatial and seasonal distribution of 17 endocrine disruptor compounds in an urban estuary (Mondego River, Portugal): evaluation of the estrogenic load of the area.  

Science.gov (United States)

The Mondego River estuary demonstrates signs of pollution, but the levels of endocrine disrupting compounds (EDCs), such as the natural (17?-estradiol and estrone) and pharmaceutical (17?-ethynylestradiol) estrogens, xenoestrogenic industrial pollutants (4-octylphenol, 4-nonylphenol, and their mono- and diethoxylates and bisphenol A), phytoestrogens (formononetin, biochanin A, daidzein, and genistein), and sitosterol were either poorly or never measured in this area. Thus, to conclude about the influx of EDCs in this estuary, water samples were taken every 2 months, during 1 year (2010) in low tide, at eight sites distributed along the estuary. Water samples (1 L) were preconcentrated in the Oasis HLB cartridges and cleaned in silica cartridges before their analysis by GC-MS. In summer, potentially hazardous amounts of estrogens (?26 ng L(-1)), alkylphenols (?11.5 ?g L(-1)), alkylphenolethoxylates (?13 ?g L(-1)), and phytoestrogens (?5.6 ?g L(-1)) were measured. These data suggest that changes in the hydrodynamics of the estuary coupled with the increase of water temperatures interfere with the amount of EDCs in the water. Complementary physicochemical parameters also point to high levels of anthropogenic pollution in this area. Globally, the estrogenic load, expressed in ethynylestradiol equivalents, attained 71.8 ng L(-1) demonstrating that, all together, the measured EDCs pose important health risks for both biota and humans. PMID:24458306

Rocha, Maria João; Cruzeiro, Catarina; Reis, Mário; Pardal, Miguel Angelo; Rocha, Eduardo

2014-06-01

251

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

2014-02-01

252

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

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. This report consists of four appendices that present lists of concentrations and computer-reconstructed gas chromatograms of aromatic extracts from Elizabeth River sediments

1982-01-01

253

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2006-01-01

254

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

255

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

256

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

International Nuclear Information System (INIS)

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

2007-05-01

257

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-05-15

258

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

Science.gov (United States)

Temperature gradient gel electrophoresis (TGGE) was employed for the assessment of yeast diversity in the estuary of the Tagus river (Portugal). The molecular detection of yeasts was carried out directly from water samples and, in parallel, a cultivation approach by means of an enrichment step was employed. A nested PCR was employed to obtain a fungal amplicon containing the D2 domain of the 26S rRNA gene. For identification the TGGE bands were extracted, re-amplified, and sequenced. Fourteen fungal taxa were detected and all except one were yeasts. Most yeast sequences corresponded to members of the Ascomycota and only three belonged to the Basidiomycota. Five yeasts (four ascomycetes and one basidiomycete) could not be identified to the species level due to the uniqueness of their sequences. The number of species detected after enrichment was higher than the number of taxa found using the direct detection method. This suggests that some yeast populations are present in densities that are below the detection threshold of the method. With respect to the analysis of the yeast community structure, our results indicate that the dominant populations belong to Debaryomyces hansenii, Rhodotorula mucilaginosa, Cryptococcus longus, and to an uncultured basidiomycetous yeast phylogenetically close to Cr. longus. The combined analysis of direct detection and cultivation approaches indicates a similar community structure at the two sampled sites since nine species were present at both localities. PMID:15556087

Gadanho, Mário; Sampaio, José Paulo

2004-12-01

259

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-09-29

260

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

 
 
 
 
261

Responses of summer phytoplankton community to drastic environmental changes in the Changjiang (Yangtze River) estuary during the past 50 years.  

Science.gov (United States)

The phytoplankton community in the Changjiang Estuary is subject to intensive physical and chemical stresses because of human- and climate-driven changes. We obtained historical data on summer phytoplankton communities from 1959 to 2009 to explore responses to long-term environmental changes. The nitrogen (N) and phosphorus (P) concentrations and ratios (N/P and N/Si) increased because of persistent riverine loading, but silicon (Si) levels remained constant. Climatic changes and extensive water diversions and withdrawals (sediment retention) resulted in a series of physical alterations, including increased temperature, turbidity reduction, and river plume shrinkage. These changes induced a dramatic increase in microalgal biomass (cell density and chlorophyll a) with a decreasing diatom-dinoflagellate ratio, and exacerbated harmful algal blooms. In the past dominant net-collected species were usually chain-forming diatoms; however, more recently, large dinoflagellates and filamentous cyanobacteria dominate. This was not consistent with information from water samples (co-dominated by small dinoflagellates), because of the loss of solitary species collected using a 76-?m net. The dominant species shifted from temperate-subtropical/eurythermal to subtropical-tropical/eurythermal taxa in the warmer water caused by global warming and hydrographic changes. There was also an increased dominance of euryhaline/high-salinity species due to increase in Kuroshio transport and the northward Taiwan Warm Current and reduction in Changjiang Diluted Water. All these changes in phytoplankton communities appear to be closely related to an increase in anthropogenic activities and climatic changes. PMID:24531075

Jiang, Zhibing; Liu, Jingjing; Chen, Jianfang; Chen, Quanzhen; Yan, Xiaojun; Xuan, Jiliang; Zeng, Jiangning

2014-05-01

262

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

International Nuclear Information System (INIS)

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

1979-01-01

263

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

264

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)

2008-10-19

265

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

266

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

267

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

International Nuclear Information System (INIS)

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

1982-01-01

268

Sources of heavy metals in sediments of the Hudson River Estuary  

International Nuclear Information System (INIS)

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

1978-01-01

269

Sediment Storage and Heavy Metal Inventories in the Lower Reaches of the Hudson River Estuary  

Science.gov (United States)

Estuaries are important resources and many throughout the world are intensively used and modified by anthropogenic activities, which has resulted in instances of significant environmental contamination (e.g., heavy metals and organic contaminants). Many of these contaminants exhibit a high affinity for fine-grained sediments, making a detailed knowledge of the distribution and contaminant loading crucial to effective estuarine management. We use a hand-held X-ray fluorescence spectrometer to rapidly generate lead and other elemental distribution profiles. This technique, performed on split wet sediment cores, allows information to be collected for a significantly greater number of sediment cores than current techniques allow. When this information is combined with bulk density information that is routinely measured on sediment cores inventories of metals such as Pb, Zn, and Cu derived from anthropogenic activities (i.e., contaminant inventories) can be computed and mapped. Further, the particle reactive nature of the elements measured allows there application as proxies for other particle reactive contaminants with similar release histories. Using the penetration depth of anthropogenic contaminants in conjunction with high resolution acoustic data allows the volume of recently deposited sediments (i.e., sediments impacted by 20th century industrial activities) to be obtained. Presented results will include detailed metal inventory maps (e.g., lead, zinc, and copper) and sediment storage volume estimates from the Hudson Highlands south to the Tappan Zee area.

Kenna, T. C.; Nitsche, F. O.; Baumgarten, J.; Haberman, M.

2008-12-01

270

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

271

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

Science.gov (United States)

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

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

2009-05-01

272

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

Energy Technology Data Exchange (ETDEWEB)

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

273

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

Science.gov (United States)

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

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

2012-02-01

274

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 aq...

Xuemei Wang; Zhiyong Wu; Min Shao; Yunting Fang; Leiming Zhang; Fei Chen; Pak-wai Chan; Qi Fan; Qian Wang; Shengjie Zhu; Ruoyu Bao

2013-01-01

275

Flow model of the Hudson River estuary from Albany to New Hamburg, New York  

Science.gov (United States)

A one-dimensional transient-flow-simulation model was developed to represent a 76-mile reach of the tidal Hudson River between Albany and New Hamburg, N.Y. The river 's direction of flow reverses four times daily as a result of tidal influence, and this process produces complex current patterns and retards the rate at which the river can flush out pollutants. In the model, the reach studied is treated as two subreaches to incorporate differences in channel conditions and to simplify model calibration. This report provides all stage (water-level) and discharge data that were used to calibrate and verify the model and compares the model results with measured data. The model accurately simulated observed flows, but further calibration based upon additional prototype flow measurements would improve simulation of the flow magnitude and phasing of the tide reversal under low-flow conditions. The model can be used to calculate instantaneous stage, velocity, and discharge for any location in the reach and can also be used to calculate net volume flux between tide reversals. (USGS)

Stedfast, David A.

1982-01-01

276

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

International Nuclear Information System (INIS)

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

1983-01-01

277

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

278

RELATIONSHIP BETWEEN FECUNDITY AND BIOMETRIC INDICES OF THE SILVER CATFISH Chrysichthys nigrodigitatus (Lacepede IN THE CROSS RIVER ESTUARY, NIGERIA  

Directory of Open Access Journals (Sweden)

Full Text Available The relationship between fecundity and biometric parameters of silver catfish, Chrysichthys nigrodigitatus from the Cross River estuary was studied between July and October 2012. A total of 120 gravid female fish were examined. The results show that fecundity of C. nigrodigitatus ranged between 975 eggs for fish of total length 23.2 cm, total weight 99 g, ovary weight 15 g and mean egg diameter 2.43 mm to 11,280 eggs for fish of total length 50.0 cm, total weight 1420.0 g, ovary weight 80.0 g and mean egg diameter 3.44 mm. There was a positive significant relationship between fecundity (F and total length (TL, total weight (TW, ovary weight (OW and mean egg diameter (MED as follows: F = 2.457TL1.9225 (r = 0.8457 and r2 = 0.7152, P<0.05, F = 61.51TW0.6098 (r = 0.890, r2 = 0.7921, P<0.05, F = 28.162OW1.2468 (r = 0.9457, r2 = 0.8943, P<0.05,F = 704.44MED1.0624 (r = 0.2128, r2 = 0.0453, P<0.05. Fecundity and mean egg diameter increases with total weight (TW. This finding is essential for evaluating the aquaculture strategies required to intensify commercial production and management of C. nigrodigitatus stock since it is a valuable source of protein in Nigeria.

Victor Oscar Eyo

2013-10-01

279

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

Science.gov (United States)

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

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

2009-01-01

280

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...

2010-01-01

 
 
 
 
281

Prediction of the effects of nutrient loadings from a power plant at Perryman on the water quality of the Bush River estuary. Final report  

International Nuclear Information System (INIS)

A water-quality model consisting of a one-dimensional Hydraulic Module coupled with a Water Quality Module was used to assess the effects of increased nutrient loadings from the proposed Perryman Power Plant on the dissolved oxygen and chlorophyll-a concentrations in the Bush River estuary. The Hydraulic Module represented the longitudinal water movement (and physical transport of associated constituents) among 12 spatial segments. The Water Quality Module represented the biological processes affecting nitrogen, phosphorus, chlorophyll-a, and dissolved oxygen in each segment (e.g., photosynthesis, nutrient uptake, decomposition)

1986-01-01

282

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

Science.gov (United States)

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

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

2009-01-01

283

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

Science.gov (United States)

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

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

2011-12-01

284

Behavior of arsenic in the coastal area of the Changjiang (Yangtze River) Estuary: Influences of water mass mixing, the spring bloom and hypoxia  

Science.gov (United States)

The biogeochemical cycle of arsenic in the aquatic environment has received scientific attention because of the complex forms and toxicity of this element. Previous studies have shown the frequent occurrence of hypoxia in the coastal area of the Changjiang (Yangtze River) Estuary. In an especially dry year (2006), three cruises were conducted (June, August and October) in this area to investigate the impact of hypoxia on total dissolved inorganic arsenic (TDIAs: [TDIAs]=[AsO43?]+[AsO33?]), dissolved organic arsenic (DOAs) and total arsenic in surface sediments. The distribution of TDIAs in the study area was similar among the three field studies, with high concentrations being found in the coastal area and in near bottom waters offshore in the East China Sea (ECS). TDIAs was scavenged in the surface layer in June. The distribution of DOAs was opposite that of TDIAs, especially in the region having high concentrations of chlorophyll-a (Chl-a). The DOAs/TDAs (total dissolved arsenic: [TDAs]=[DOAs]+[TDIAs]) ratio decreased from June to October. The concentrations of total arsenic in surface sediments decreased gradually from the Changjiang Estuary to the central ECS shelf. The behavior of TDIAs was non-conservative in the coastal area of the Changjiang Estuary. Biological mediation and hypoxia are the main factors influencing the internal cycling of arsenic within the study area. The DOAs/TDAs ratio was negatively correlated with apparent oxygen utilization (r=0.71, pcoastal area of the Changjiang Estuary. Sediment-water incubation experiments conducted under various redox conditions showed that hypoxia resulted in the release of arsenic from the sediments into the water; this may contribute to the high TDIAs concentrations in bottom waters in August. With increased toxicity and residence time of inorganic arsenic species during hypoxia, the potential damage to the ecosystem and marine environment should receive more attention.

Li, Lei; Ren, Jing-Ling; Yan, Zhe; Liu, Su-Mei; Wu, Ying; Zhou, Feng; Liu, Cheng-Gang; Zhang, Jing

2014-06-01

285

Profile of trace metals accumulation in core sediment from Seine river estuary (docks basin).  

Science.gov (United States)

The Seine is one of the most polluted rivers in Europe with respect to potentially harmful elements. It receives effluents from the upstream Paris urban and industrial area, and also local inputs from the heavily industrialized Rouen and Le Havre regions. The present study deals with this environmental topic and the concentrations of Cd, Ni, Pb, Hg, Zn and Cu were determined in sediment cores collected in the docks basin of Rouen harbour in 2008. The intensity of metal pollution during recent decades was evaluated using an enrichment factor (EF) and a geoaccumulation index (Igeo). The results of vertical distribution showed that the metal pollution in the past is much higher than in the surface sediment. Mercury was found to be the heaviest pollutant (with Igeo and EF exceeding 4 and 20, respectively), and Cd and Pb were the second most important pollutants. A slight contamination in Ni was observed with very low Igeo values. To estimate the sediment toxicity, simultaneously extracted metals/acid volatile sulfides ratio (SEM/AVS) was calculated. Low values of the toxicity index SEM/AVS were observed in the core sediments indicating the inexistence of metal potential toxicity. Also the concentrations of these trace metals were lower than the probable effect concentration values reported as consensus-based sediment quality guidelines for fresh water ecosystems. PMID:24191442

Hamzeh, Mariam; Ouddane, Baghdad; El-Daye, Mirna; Halwani, Jalal

2013-01-01

286

Nutritive Value of Ethmalosa fimbraita (Clupeidae, Mugil cephalus, (Mugilidae and Cynoglosuss senegalensis (Cynoglossidae of the Cross River Estuary, Nigeria, West Africa  

Directory of Open Access Journals (Sweden)

Full Text Available The nutritive value and the content of some minerals were investigated in three commercially important marine fish species of the Cross River estuary, Nigeria. The fishes studied using standard procedures as recommended by AOAC were Ethmalosa fimbraita, Mugil cephalus and Cynoglosuss senegalensis. The protein, carbohydrate, fat and moisture contents were 18.50%, 9.63%, 8.70% and 66.50% in E. fimbraita while these results in M. cephalus were 19.75%, 11.75%, 8.60% and 63.66% respectively. Data obtained for C. senegalensis were 19.76% for protein, 9.22% as carbohydrate, 9.02% for fat and 65.02% for moisture. Trace elements, e.g. iron and manganese were high in concentration in these species than the major elements. The concentration of most of the studied elements were significantly similar in the species except Copper (Cu2+, which was more concentrated in C. senegalensis than in the other two species. The ash content was higher in C. senegalensis and M. cephalus (p>0.05 while that in E. fimbraita was significantly lower in concentration (p>0.05. These probably underscore the importance of the other two species being richer sources of minerals than E. fimbraita in the Cross river estuary.

Vivian N. Arazu

2012-01-01

287

GAS CHROMATOGRAPHY-FLAME IONIZATION DETECTION FINGERPRINT OF HYDROCARBON EXTRACTS FROM WATER AND SEDIMENTS OF THE GREAT KWA RIVER ESTUARY, SOUTH EASTERN COAST OF NIGERIA  

Directory of Open Access Journals (Sweden)

Full Text Available Various fractions of hydrocarbon in water and sediments from Great Kwa River Estuary (GKRE Southeast coast of Nigeria were studied quarterly for a period of one year by extracting the total hydrocarbons (THC from samples. After pre-treatment, finger prints of various hydrocarbon fractions were determined by (GC-FID. Results analysis show that the sediments contain high level of hydrocarbon of crude petroleum origin, suggesting possible impact of petroleum industries in the area. Only 50% of hydrocarbon fraction from water was in sediment, confirming higher concentration in sediment than in water. The sediments contained wide range of parafinic and aromatic fraction. Their levels were generally higher than the standard recommended by the National Department of Petroleum (DPR and Federal Environmental Protection Agency (FEPA. However, the Great Kwa River Estuary (GKRE appeared only moderately contaminated with hydrocarbons but not polluted as at this study. Continuous monitoring was recommended for environmental quality of this marine environment in view of the offshore petroleum industries and the upstream municipal activities that discharge untreated waste into this marine ecosystem.

O.R. OGRI

2011-09-01

288

Model Behavior and Sensitivity in an Application of the Cohesive Bed Component of the Community Sediment Transport Modeling System for the York River Estuary, VA, USA  

Directory of Open Access Journals (Sweden)

Full Text Available The Community Sediment Transport Modeling System (CSTMS cohesive bed sub-model that accounts for erosion, deposition, consolidation, and swelling was implemented in a three-dimensional domain to represent the York River estuary, Virginia. The objectives of this paper are to (1 describe the application of the three-dimensional hydrodynamic York Cohesive Bed Model, (2 compare calculations to observations, and (3 investigate sensitivities of the cohesive bed sub-model to user-defined parameters. Model results for summer 2007 showed good agreement with tidal-phase averaged estimates of sediment concentration, bed stress, and current velocity derived from Acoustic Doppler Velocimeter (ADV field measurements. An important step in implementing the cohesive bed model was specification of both the initial and equilibrium critical shear stress profiles, in addition to choosing other parameters like the consolidation and swelling timescales. This model promises to be a useful tool for investigating the fundamental controls on bed erodibility and settling velocity in the York River, a classical muddy estuary, provided that appropriate data exists to inform the choice of model parameters.

Kelsey A. Fall

2014-05-01

289

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

1986-01-01

290

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

Directory of Open Access Journals (Sweden)

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

291

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.

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

292

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

Directory of Open Access Journals (Sweden)

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

B. He

2010-10-01

293

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.

294

Organic Matter Sources in the Water Column and Sediments of the Hudson River Estuary: the Use of Plant Pigments as Tracers  

Science.gov (United States)

The purpose of this study was to document inputs of organic matter into the Hudson River Estuary using plant pigments as tracers. Plant pigments (carotenoids and chloropigments) were determined using high pressure liquid chromatography (HPLC). Water column and sediment samples were collected in 1988 and 1989, from stations along a 165 km transect in the Hudson River Estuary. In the water column, high concentrations of lutein were found at stations adjacent to wetland areas indicating inputs of vascular plant detritus, particularly during late fall. Chlorophyll b/lutein ratios at these stations were 2-4 which are similar to that found in fresh vascular plant material collected from the Hudson. Low chlorophyll b/lutein ratios at Haverstraw Bay, a shallow and turbid area of the estuary, indicate high levels of sediment resuspension. Cyanophyte blooms, as indicated by high concentrations of myxoxanthophyll, reach their peak in late summer at the Hudson and Kingston stations. The chlorophyll a from these algae may comprise as much as 78% of the total chlorophyll a pool during these periods. Concentrations of total phaeophorbide, an indicator of grazing activity, were not correlated with chlorophyll a but were correlated with fucoxanthin and/or fucoxanthinol. This correlation suggests that much of the zooplankton grazing activity is associated with high quality food resources such as diatoms and not with cyanophytes. Surface sediments from a coarse-grained sandy habitat had significantly lower amounts of total organic matter than muddy habitats. However, the sandy sediment had higher grazing activity per gram organic matter, as indicated by total phaeophorbides. Higher concentrations of chlorophyll a and fucoxanthin at the sandy habitat indicate the presence of benthic diatoms which are high quality (low C/N ratio) living resources in contrast to the detrital sources (high C/N, mostly vascular plant) at the muddy stations. High concentrations of chlorophyllide a at some muddy stations, near macrophyte beds, suggest inputs of epiphytic diatom detritus. Overall, sediment pigments of the Hudson estuary are derived from vascular plant material that does not reflect the pigment signature of the water column.

Bianchi, Thomas S.; Findlay, Stuart; Dawson, Rodger

1993-04-01

295

Ecologia do microfitoplâncton do estuário do rio Igarassu, PE, Brasil / Microphytoplankton ecology of the Igarassu river estuary, Pernambuco State, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Foram realizadas coletas mensais de outubro/2002 a setembro/2003 em baixa-mar e preamar de um mesmo dia, para estudo da comunidade fitoplanctônica do estuário do rio Igarassu, relacionando-a aos parâmetros abióticos. Foram identificadas 210 espécies, distribuídas em cinco divisões. As Bacillariophyt [...] a tiveram maior representatividade, com 146 espécies, seguidas pelas Cyanophyta (26 espécies), Chlorophyta (15 espécies), Euglenophyta (12 espécies) e Dinophyta (11 espécies). As espécies dominantes foram Chaetoceros curvisetus Cleve (97,8%, na preamar da estação 02, em abril/2003), Thalassionema nitzschioides Grunow (93,67%, na estação 03, na baixa-mar, em agosto/2003), Microcystis aeruginosa Kützing (88,37%, maio/2003, na baixa-mar da estação 02), Rhizosolenia hebetata (Bailey) Gran (87,52%, na estação 03, na preamar de fevereiro/2003) e Thalassiosira rotula Meunier (84,18% na estação 02, durante a preamar do mês de junho/2003). A densidade microfitoplanctônica esteve associada à pluviosidade, tendo ocorrido um florescimento expressivo no fim da período chuvoso e inicio do período de estiagem. A diversidade específica e equitabilidade estiveram diretamente relacionadas à baixa-mar e período de estiagem. A partir da observação dos parâmetros ambientais e da estrutura da comunidade fitoplanctônica verificou-se que existe uma forte influência da água do mar no estuário do rio Igarassu, evidenciada pela presença de espécies neríticas e oceânicas, enquanto que, na época de maior pluviosidade ocorreu à presença dominante da Cyanophyta dulcícola Microcystis aeruginosa Kützing. Abstract in english Studies on the phytoplankton community and its relationship to abiotic parameters were carried out at the Igarassu River estuarine area. Plankton collections were made monthly from October/2002 to September/2003 during low and high tides on the same day. We identified 210 species, distributed in fiv [...] e divisions. Bacillariophyta was the most taxonomically diverse with 146 species, followed by Cyanophyta (26 species), Chlorophyta (15 species), Euglenophyta (12 species) and Dinophyta (11 species). The dominant species were Chaetoceros curvisetus Cleve (97.8%, high tide, station 2, April/2003); Thalassionema nitzschioides Grunow (93.67%, low tide, station 3, August/2003); Microcystis aeruginosa Kützing (88.37%, low tide, station 2, May/2003); Rhizosolenia hebetata (Bailey) Gran (87.52%, high tide, station 3, February/2003); and Thalassiosira rotula Meunier (84.18% high tide, station 2, June/2003). Microphytoplankton density was related to rainfall, with a bloom at the end of the rainy season. Higher species diversity and evenness were related to low tide and dry season. The phytoplankton community was structured by the marine flux during the dry season in the Igarassu River estuary with the presence of neritic and oceanic species. In the rainy season the community was structured by the freshwater flux, with the dominance of the Cyanophyta Microcystis aeruginosa Kützing.

Bruno Machado, Leão; José Zanon de Oliveira, Passavante; Maria da Glória Gonçalves da, Silva-Cunha; Marilene Felipe, Santiago.

296

Evaluation of the sampling methods applied to phycoperiphyton studies in the Ratones River estuary, Brazil Avaliação dos métodos de coleta aplicados no estudo do ficoperifíton no estuário do rio Ratones, SC, Brasil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

AIM: The present study aimed on testing the efficiency of four sampling methods for identification and quantification applied in studies on the biodiversity and spatial-temporal distribution of the phycoperiphyton in the Ratones River estuary; METHODS: The sampling were carried out in three sampling stations along the Ratones River in March and August 2008. The methodologies used for the separation of the periphyton from the sediment were made with the use of sieves and trapping tissue. A rem...

2010-01-01

297

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2000-05-01

298

Macrobenthic succession and characteristics of a man-made intertidal sandflat constructed in the diversion channel of the Ohta River Estuary.  

Science.gov (United States)

We compared succession and characteristics of the macrobenthic community in a small-scale experimental intertidal sandflat constructed in the artificial diversion channel of the Ohta River Estuary with those of three natural intertidal sandflats at lower elevation in the same channel. The macrobenthic population density in the man-made intertidal sandflat increased significantly between 3 and 9 months after construction. Simplisetia erythraeensis was dominant (98% of individuals) after 9 months, but its proportion gradually declined with the increase in biodiversity until 26 months, indicating that succession of the macrobenthic community was nearly complete by 26 months. The macrobenthic community in the man-made intertidal sandflat differed from those of the three natural intertidal sandflats, and its population density was about double that at the natural sites, with smaller temporal fluctuation. The different structures of the macrobenthic communities in the man-made and natural intertidal sandflats were likely caused by differences in elevation. PMID:24667086

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

2014-05-15

299

"2"3"9 "2"4"0Pu and "2"3"8Pu in sediments of the Hudson River estuary  

International Nuclear Information System (INIS)

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

1980-01-01

300

Hermaphroditism among dioecious Tagelus plebeius (Lightfoot, 1786) (Mollusca, Psammobiidae) and Iphigenia brasiliana (Lamarck, 1818) (Mollusca, Donacidae) on the Cachoeira River estuary, Ilhéus, Bahia, Brazil.  

Science.gov (United States)

The samples of Tagelus plebeius and Iphigenia brasiliana were manually collected on the Cachoeira River estuary region (Ilhéus, BA, Brazil) between August 2005 and August 2006, with a periodicity of 15 days, with 20 animals collected/sampled, performing 500 samples from each species. The animals were measured, eviscerated and kept in solution of Davidson and after 24-30 hours, they were transferred to ethanol 70%. The material was processed for routine histology, with paraffin embedding, obtaining 7 microm thick slices, stained with Harris hematoxilin and Eosin (HE). By light microscopy analysis, 2 cases of hermaphroditism (0.4%) in T. plebeius samples and one case (0.2%) in I. brasiliana were registered with predominance of female over male follicles. PMID:20231968

Ceuta, L O; Boehs, G; Santos, J J B

2010-02-01

 
 
 
 
301

Anthropogenic 236U at Rocky Flats, Ashtabula river harbor, and Mersey estuary: three case studies by sector inductively coupled plasma mass spectrometry  

International Nuclear Information System (INIS)

236U (t1/2=2.3x107 y) is formed as a result of thermal neutron capture by 235U. In naturally occurring U ores, where a high neutron flux is present from spontaneous fission of 238U, 236U/238U atom ratios are ?10-4 ppm. In the natural Earth's crust, unaffected by nuclear fallout, these ratios are expected to be on the order of 10-8 ppm. Reactor-irradiated U, however, exhibits high 236U/238U atom ratios approaching 104 ppm. As a result, the presence of very small quantities of reactor-irradiated U will significantly enhance the 'background' 236U/238U atom ratio. When sufficiently elevated 236U/238U ratios are present, the determination of 236U/238U by rapid inductively coupled plasma mass spectrometric (ICPMS) methods is attractive. We have used sector ICPMS at medium resolving power (R=3440) to measure 236U/238U atom ratios with a determination limit of 0.2 ppm. The limiting factors in the measurement are the 235U1H+ isobar and background signal at m/z 236 arising from the 238U+ peak tail. Based upon the analysis of replicates and considerations of possible systematic errors, uncertainties of ±5% are found for 236U/238U atom ratios of 1-100 ppm. This procedure has been demonstrated in studies of anthropogenic 236U in the environment at three locations: (a) offsite soils from the vicinity of the Rocky Flats Environmental Technology site (Golden, Colorado, USA); (b) sediments from the Ashtabula River (Ohio, USA); and (c) sediments from the Mersey estuary (Liverpool, UK). In each of these three locations, definite plumes of elevated 236U/238U are identified and characterized. Maximum 236U/238U atom ratios observed in RFETS-vicinity soils, the Ashtabula River, and the Mersey Estuary are 2.8, 140, and 4.4 ppm, respectively

2003-01-01

302

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effects of environmental factors on variations of dissolved oxygen (DO) saturation was assessed in 2 estuaries (Bilbao and Urdaibai) in the Bay of Biscay with contrasting hydrography and anthropogenic impact, for the period 1997 to 2006, using generalised additive models (GAMs) and generalised additive mixed models (GAMMs). Spatial and temporal variations in DO saturation and the current severity and extent of hypoxia were higher in the culturally eutrophicated and stratified Bilbao estua...

Iriarte, Arantza; Aravena, Guillermo; Villate, Fernando; Uriarte, Ibon; Iba?n?ez, Berta; Llope, Marcos; Stenseth, Nils Christian

2010-01-01

303

Predicting Bankfull Discharge in Ungauged Estuaries by Explaining the Physical Relation Between the Morphology and Hydrology of Estuaries  

Science.gov (United States)

River discharge is a very important parameter in morphological and hydrodynamic studies of estuaries. However, it is always difficult to accurately measure river discharge, and in particular the bankfull discharge in estuaries where the tidal discharge dominates over river discharge. Until today, little research has been done in finding a simple and useful approach to estimate the river discharge in the tidal region, and most of the previous studies focused on the river regime. In this study, we found that there appear to be empirical relations that link together the morphology and hydrology of estuaries, which can be used to estimate river discharge with the least amount of data available. The aims of this study are: 1) to discover the physical explanation for the empirical relation that exists between geometrical characteristics of estuaries and the bankfull flood discharge; and 2) to estimate bankfull discharge in estuaries from the relationship. The physical connection between the estuaries and river regime is found by incorporating the estuary shape analysis and tidal dynamic analysis to Lacey's hydraulic geometry theory. Relationship between the estuary depth and the bankfull river discharge has been analyzed in 19 estuaries around the world (with 9 recently surveyed estuaries). In this study, the discharge data (from gauging station located further upstream) were adjusted by a projection approach to improve the discharge measurement. The outcome of the relationship was compared to Lacey's theory of hydraulic geometry. From the analysis, it shows that the depth of an estuary is a function of the bankfull flood discharge to the power of 1/3 which indicates an agreement with Lacey's formula. With the physical explanation, engineers would be able to estimate flood discharge characteristics from estuary shape indicators. This could be very useful to estimate the flood discharge in ungauged estuaries on the basis of readily available data. In order to verify the accuracy of the relation, existing and new measurement data from estuaries worldwide will be collected and compiled to strengthen the reliability of this finding.

Gisen, J.; Savenije, H.

2013-12-01

304

Total and labile metals in surface sediments of the tropical river-estuary system of Marabasco (Pacific coast of Mexico): Influence of an iron mine  

International Nuclear Information System (INIS)

Marabasco is a tropical river-estuary system comprising the Marabasco river and the Barra de Navidad Lagoon. The river is impacted by the Pena Colorada iron mine, which produces 3.5 million tons of pellets per year. Thirteen surface sediment samples were collected in May 2005 (dry season) in order to establish background levels of Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn in the system and to ascertain the potential mobility of metals in the sediments. Analyses were carried out in the fraction finer than 63 ?m, and labile metals extracted according the BCR procedure. Certified reference materials were used for validation of methods. Total concentrations of Cd, Co, Cu, Ni, Pb, and Zn were in the range of 0.05-0.34, 6-95, 0.7-31, 9-26, 2-18, and 53-179 mg kg-1, respectively; Al and Fe ranges of 24-127, and 26-69 mg g-1 correspondingly. Cadmium was found to be significantly labile in the sediments (20-100%), followed by Co (0-35%), Ni (3-16%) and Zn (0-25%), whereas the labile fraction for Cu, Fe and Pb was almost negligible (<4%). According with the total metal concentrations, background levels and normalised enrichment factors (NEF) of the metals studied, the impact of the Pena Colorada iron mine on the Marabasco system is lower than expected when compared with other similar World systems influenced by mining activities

2007-01-01

305

Modeling the Effects of Potential Salinity Shifts on the Recovery of Striped Bass in the Savannah River Estuary, Georgia-South Carolina, United States  

Science.gov (United States)

Increased salinity in spawning and nursery grounds in the Savannah River estuary was cited as the primary cause of a 97% decrease in adult striped bass ( Morone saxatilis) and a concomitant 96% decrease in striped bass egg production. Restoration efforts focused on environmental remediation and stock enhancement have resulted in restored salinity patterns and increased egg and adult abundances. However, future water needs or harbor development may preclude further recovery by reducing freshwater inflow or increasing salinity intrusion. To assess the effect of potential changes in the salinity regime, we developed models relating discharge, tidal phase, and salinity to striped bass egg and early larval survival and re-cast these in a quantitative Bayesian belief network. The model indicated that a small upstream shift (?1.67 km) in the salinity regime would have the least impact on striped bass early life history survival, whereas shifts >1.67 km would have progressively larger impacts, with a 8.33-km shift potentially reducing our estimated survival probability by >28%. Such an impact could have cumulative and long-term detrimental effects on the recovery of the Savannah River striped bass population. The available salinity data were collected during average and low flows, so our model represents some typical and some extreme conditions during a striped bass spawning season. Our model is a relatively simplistic, “first-order” attempt at evaluating potential effects of changes in the Savannah River estuarine salinity regime and points to areas of concern and potential future research.

Reinert, Thomas R.; Peterson, James T.

2008-05-01

306

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

Scientific Electronic Library Online (English)

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

Cristiane Maria Rocha, Farrapeira.

307

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

Directory of Open Access Journals (Sweden)

Full Text Available Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized 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±0.10% on the inner shelf and 0.58±0.06% on the outer shelf. ?13C values ranged from ?25.11‰ to ?21.28‰ across the studied area, with a trend of enrichment seaward. The spatial trend in C/N ratios mirrored that of ?13C, with a substantial decrease in C/N ratio from 10.9±1.3 in the Lingdingyang Bay surface sediments to 6.5±0.09 in the outer shelf surface sediments. Total carbohydrate yields ranged from 22.1 to 26.7 mg (100 mg OC?1, and typically followed TOC concentrations in the estuarine and shelf sediments, suggesting that the relative abundance of total carbohydrate was fairly constant in TOC. Total neutral sugars as detected by the nine major monosaccharides (lyxose, rhamnose, ribose, arabinose, fucose, xylose, galactose, mannose, and glucose yielded between 4.0 and 18.6 mg (100 mg OC?1 in the same sediments, suggesting that a significant amount of carbohydrates were not neutral aldoses. The bulk organic matter properties, isotopic composition and C/N ratios, combined with molecular-level carbohydrate compositions were used to assess the sources and accumulation of terrestrial organic matter in the Pearl River Estuary and the adjacent northern South China Sea shelf. Results showed a mixture of terrestrial riverine organic carbon with in situ phytoplankton organic carbon in the areas studied. Using a two end-member mixing model based on ?13C values and C/N ratios, we estimated that the terrestrial organic carbon contribution to the surface sediment TOC was ca. 57±13% for Lingdingyang Bay, 19±2% for the inner shelf, which decreased further to 4.3±0.5% on the outer shelf. The molecular composition of the carbohydrate in surface sediments also suggested that the inner estuary was rich in terrestrial-derived carbohydrates but that the contribution of terrestrial-derived carbohydrates decreased offshore. Terrestrial organic carbon accumulation flux was estimated as 1.37±0.92×1011 g yr?1 in Lingdingyang Bay, which accounted for 37±25% of the terrestrial organic carbon transported to the Bay. The burial efficiency of terrestrial organic matter was markedly lower than that of suspended particulate substance (~71% suggesting that the riverine POC undergoes significant degradation and replacement during transportation through the estuary.

B. He

2010-04-01

308

Plutonium, cesium, uranium and thorium series radionuclides in the Hudson River estuary and other environments. Annual technical progress report, December 1, 1983-November 30, 1984  

International Nuclear Information System (INIS)

Radionuclide activities were measured in sediment cores and suspended particle samples from the Hudson River estuary. Activities of 137Cs, 134Cs, and 60Co, 239 240Pu and 238Pu indicate rapid accumulation in marginal cove areas, and very rapid deposition in the harbor adjacent to New York City, resulting in 239 240Pu accumulations of more than an order of magnitude greater than the fallout delivery rate. Fallout 239 240Pu moving downstream appears to be retained within the system by particle deposition, while more than 50% of the 137Cs derived from both reactor releases and fallout has been exported. Significant movement of dissolved plutonium into the estuary from adjacent coastal waters may be occurring. Depth profiles of radionuclides are not significantly altered by physical mixing processes in areas accumulating particles at greater than 1 cm/yr. Transport of fallout radionuclides appears to have decreased faster than would be calculated from continuous removal from a well-mixed soil reservoir, indicating that sequestering of a substantial portion of the soil fallout burden has occurred in the watershed soils over the past two decades. Measurements of fallout 239 240Pu in a saline lake with a high carbonate ion concentration yielded water column activities two orders of magnitude greater than that found for fallout plutonium in other continental waters, indicating extensive mobility in some natural water environments. Experiments using lake water suggest that carbonate ions are likely to be important in regulating plutonium solubility in some environments and that low molecular weight complexes are primarily responsible for enhanced plutonium solubility. 45 references, 17 figures, 14 tables

1984-01-01

309

A study of the composition and distribution of lignin in resuspended and permanently suspended particles in the river Tamar Estuary  

Science.gov (United States)

The composition and distribution of lignin in the permanently suspended and resuspended material of the Tamar Estuary have been investigated by separating particles on the basis of settling characteristics. Lignin was determined using the diagnostic phenols formed by copper oxide oxidation. Samples were collected over a tidal cycle at different depths at a single location and over a 30 km transect 1of the estuary at a constant depth. Summed values of lignin oxidation products in permanently suspended materials ranged from 0·90 to 10·49 mg, normalized to particulate organic carbon. These values are considerably higher than the range 0·22 to 3·87 mg measured in material resuspended as a result of tidal action. The different values reflect the relative buoyancy of the lignin-bearing materials. Ratios of the various lignin components suggest that the permanently suspended fraction contains a significant proportion of degraded angiosperm tissues, while in the resuspended fraction a component of degraded gymnosperm material is indicated.

Reeves, Alison D.; Preston, Martin R.

1991-01-01

310

Bacteria of fecal origin in mangrove oysters (Crassostrea rhizophorae) in the Cocó River estuary, Ceará State, Brazil Bactérias de origem fecal contaminantes de ostra Crassostrea rhizophorae, oriundas do estuário do Rio Cocó, Estado do Ceará, Brasil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study was aimed at evaluating the microbiological quality of mangrove oysters (Crassostrea rhizophorae), collected at a natural oyster bed in the estuary of Cocó river (Fortaleza, Ceará, Brazil). MPN values were used for estimating the total (TC) and fecal (FC) coliforms and Enterococcus spp. TC and FC MPN values in the whole muscle and intervalve liquid ranged from 1,600/g and from 1,1...

Silva, Ana I. M.; Vieira, Regine H. S. F.; Menezes, Francisca G. R.; Fonteles-filho, Antonio A.; Torres, Regina C. O.; Sant Anna, Ernani S.

2004-01-01

311

Nutritive Value of Ethmalosa fimbraita (Clupeidae), Mugil cephalus, (Mugilidae) and Cynoglosuss senegalensis (Cynoglossidae) of the Cross River Estuary, Nigeria, West Africa  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The nutritive value and the content of some minerals were investigated in three commercially important marine fish species of the Cross River estuary, Nigeria. The fishes studied using standard procedures as recommended by AOAC were Ethmalosa fimbraita, Mugil cephalus and Cynoglosuss senegalensis. The protein, carbohydrate, fat and moisture contents were 18.50%, 9.63%, 8.70% and 66.50% in E. fimbraita while these results in M. cephalus were 19.75%, 11.75%, 8...

2012-01-01

312

Size-fractionated phytoplankton biomass in autumn of the Changjiang (Yangtze) River Estuary and its adjacent waters after the Three Gorges Dam construction  

Science.gov (United States)

A cruise was undertaken from 3rd to 8th November 2004 in Changjiang (Yangtze) River Estuary and its adjacent waters to investigate the spatial biomass distribution and size composition of phytoplankton. Chlorophyll- a (Chl- a) concentration ranged 0.42-1.17 ?g L-1 and 0.41-10.43 ?g L-1 inside and outside the river mouth, with the mean value 0.73 ?g L-1 and 1.86 ?g L-1, respectively. Compared with the Chl- a concentration in summer of 2004, the mean value was much lower inside, and a little higher outside the river mouth. The maximal Chl- a was 10.43 ?g L-1 at station 18 (122.67°E, 31.25°N), and the region of high Chl- a concentration was observed in the central survey area between 122.5°E and 123.0°E. In the stations located east of 122.5°E, Chl- a concentration was generally high in the upper layers above 5 m due to water stratification. In the survey area, the average Chl- a in sizes of >20 ?m and <20 ?m was 0.28 ?g L-1 and 1.40 ?g L-1, respectively. High Chl- a concentration of <20 ?m size-fraction indicated that the nanophytoplankton and picophytoplankton contributed the most to the biomass of phytoplankton. Skeletonema costatum, Prorocentrum micans and Scrippsiella trochoidea were the dominant species in surface water. The spatial distribution of cell abundance of phytoplankton was patchy and did not agree well with that of Chl- a, as the cell abundance could not distinguish the differences in shape and size of phytoplankton cells. Nitrate and silicate behaved conservatively, but the former could probably be the limitation factor to algal biomass at offshore stations. The distribution of phosphate scattered considerably, and its relation to the phytoplankton biomass was complicated.

Song, Shuqun; Sun, Jun; Luan, Qingshan; Shen, Zhiliang

2008-08-01

313

[Rother Estuary Final (2).pdf  

…barrier at Scot's Float across the Eastern Rother, which maintains the non tidal Rother for navigation and water resource purposes. This is also the case for the other rivers that flow into the Rother Estuary which can be an issue for fish passage for migratory fish species. Though Scot's Float has a…

314

Effects of river discharge and high-tide stage on salinity intrusion in the Weeki Wachee, Crystal, and Withlacoochee River estuaries, southwest Florida  

Science.gov (United States)

The Weeki Wachee, Crystal, and Withlacoochee Rivers are coastal streams flowing into the Gulf of Mexico that may be affected by either future surface water or groundwater withdrawals. Reduction of river discharge will affect the upstream extent of saltwater intrusion in the rivers; however, under certain reduced low-flow discharges, the estimated change in upstream extent of saltwater intrusion is on the order of several tenths of a mile and frequently is within the range of predicted error. Data on flow, tides, and salinity describe the physical characteristics of the Weeki Wachee, Crystal, and Withlacoochee River systems. Vertical and longitudinal salinity profiles indicate that salinity of the rivers increases downstream and varies substantially at any given location. The Weeki Wachee River system is the best mixed of the three. The Crystal River system exhibited the next best mixed system, and the Withlacoochee River system exhibited the most variation in its salinity regime. The daily maximum upstream extent of salinity intrusion is described by multiple linear-regression analysis based on daily mean streamflow of each river and high-tide stage of the gulf. The equations are used to show the effects of discharge on the daily maximum upstream extent of salinity intrusion in the rivers. (USGS)

Yobbi, D. K.; Knochenmus, L. A.

1989-01-01

315

Anthropogenic {sup 236}U at Rocky Flats, Ashtabula river harbor, and Mersey estuary: three case studies by sector inductively coupled plasma mass spectrometry  

Energy Technology Data Exchange (ETDEWEB)

{sup 236}U (t{sub 1/2}=2.3x10{sup 7} y) is formed as a result of thermal neutron capture by {sup 235}U. In naturally occurring U ores, where a high neutron flux is present from spontaneous fission of {sup 238}U, {sup 236}U/{sup 238}U atom ratios are {approx}10{sup -4} ppm. In the natural Earth's crust, unaffected by nuclear fallout, these ratios are expected to be on the order of 10{sup -8} ppm. Reactor-irradiated U, however, exhibits high {sup 236}U/{sup 238}U atom ratios approaching 10{sup 4} ppm. As a result, the presence of very small quantities of reactor-irradiated U will significantly enhance the 'background' {sup 236}U/{sup 238}U atom ratio. When sufficiently elevated {sup 236}U/{sup 238}U ratios are present, the determination of {sup 236}U/{sup 238}U by rapid inductively coupled plasma mass spectrometric (ICPMS) methods is attractive. We have used sector ICPMS at medium resolving power (R=3440) to measure {sup 236}U/{sup 238}U atom ratios with a determination limit of 0.2 ppm. The limiting factors in the measurement are the {sup 235}U{sup 1}H{sup +} isobar and background signal at m/z 236 arising from the {sup 238}U{sup +} peak tail. Based upon the analysis of replicates and considerations of possible systematic errors, uncertainties of {+-}5% are found for {sup 236}U/{sup 238}U atom ratios of 1-100 ppm. This procedure has been demonstrated in studies of anthropogenic {sup 236}U in the environment at three locations: (a) offsite soils from the vicinity of the Rocky Flats Environmental Technology site (Golden, Colorado, USA); (b) sediments from the Ashtabula River (Ohio, USA); and (c) sediments from the Mersey estuary (Liverpool, UK). In each of these three locations, definite plumes of elevated {sup 236}U/{sup 238}U are identified and characterized. Maximum {sup 236}U/{sup 238}U atom ratios observed in RFETS-vicinity soils, the Ashtabula River, and the Mersey Estuary are 2.8, 140, and 4.4 ppm, respectively.

Ketterer, M.E. E-mail: Michael.Ketterer@nau.edu; Hafer, K.M.; Link, C.L.; Royden, C.S.; Hartsock, W.J

2003-07-01

316

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-10-01

317

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

Directory of Open Access Journals (Sweden)

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

CARLOS BERTRÁN

2001-06-01

318

The cycling of transuranic radionuclides in the Columbia River, its estuary and the northeast Pacific Ocean: Final report  

International Nuclear Information System (INIS)

This review summarizes work during 1985 to 1986 on the radioecology of plutonium, americium and cesium in the Columbia River sediments; radionuclide kinetics of technetium in fish, and radioactivity in the Pacific Ocean

1987-01-01

319

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The benthic meiofauna of the two river systems, the Swartkops and Gamtoos, in the Eastern Cape of South Africa has been studied extensively. Various biological indices and statistical packages were used to assess the biological status of the nematode communities in the two rivers. Nematode 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 rela...

Gyedu-ababio, T. K.

2011-01-01

320

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

International Nuclear Information System (INIS)

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

2010-01-01

 
 
 
 
321

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

Directory of Open Access Journals (Sweden)

Full Text Available The study describes the length-weight relationship and helminthes bioload of Chrysichthys nigrodigitatus (Catfish in the Cross river estuary purchased at Ayaedehe, Itu Local Government Area, Akwa Ibom State. A total of four hundred and twenty (420 life specimens of C. nigrodigitatus were collected by local fishing gear between June and November, 2011. Data obtained were statistically analyzed using descriptive and inferential statistics. Results showed that the highest length was obtained in July (100.2cm while the least was obtained in June (15.30cm. The highest weight was 1410g obtained in October while the least was obtained in September (22.10g and there were significant differences in monthly distribution of length and weight (P<0.05 of the specimens. Correction coefficient (r between length and weight of C. nigrodigitatus from June November, 2011 lied between 0.89 and 0.98 representing strong relationship between length and weight, the relationship was found to be linear but in logarithmic form. Generally condition factor, (K values decreased proportionately with the length of the fish. A total of seventy two (72 (17.14% parasite specimens were recovered from the fish, out of which helminthes parasites include a cestode Proteocephalis 9 (12.5% and aspidogastrid trematode, Aspidogastrea africanus 10 (13.89% and Nematodes; Paracamallanus cyathopharynx 34 (47.22% and Contracacum sp. 19 (26.64%. Parasitic worm burden and Intensity of infection low and independent of length and weight.

Usip Lawrence Patrick Esiest

2013-08-01

322

Plutonium, cesium and uranium series radionuclides in the Hudson River estuary and other environments. Annual technical progress report, 1 December 1980-30 November 1981  

International Nuclear Information System (INIS)

Radionuclide activities were measured in sediment cores and suspended particle samples throughout the salinity range of the Hudson River estuary. Activities of "1"3"7Cs, "1"3"4Cs, "6"0Co, "2"3"9 "2"4"0Pu, and "2"3"8Pu indicate reasonably rapid accumulation rates in the sediments of marginal cove areas, and very rapid deposition in the harbor region adjacent to New York City, resulting in "2"3"9 "2"4"0Pu accumulations there more than an order of magnitude greater than the fallout delivery rate. Fallout "2"3"9 "2"4"0Pu reaching the Hudson is almost completely retained within the systems by particle deposition, while 80 to 90% of the "1"3"7Cs derived from both reactor releases and fallout is exported to the coastal waters in solution. Depth profiles of radionuclides in Hudson sediments are not significantly altered by physical mixing processes in the sediments in areas accumulating particles at greater than 1 cm/yr. Measurements of fallout "2"3"9 "2xperimental quantities

1980-12-01

323

Plutonium, cesium, uranium, and thorium series radionuclides in the Hudson River estuary and other environments. Annual technical progress report, December 1, 1982-November 30, 1983  

International Nuclear Information System (INIS)

We have measured radionuclide activities in a large number of sediment cores and suspended particle samples throughout the salinity range of the Hudson River estuary. Activities of 137Cs, 134Cs and 60Co determined by gamma spectrometry and 239 240Pu and 238Pu determined by alpha spectrometry indicate reasonably rapid accumulation rates in the sediments of marginal cove areas, and very rapid deposition in the harbor region adjacent to New York City, resulting in 239 240Pu accumulations there more than an order of magnitude greater than the fallout delivery rate. Fallout 239 240Pu moving downstream in the Hudson appears to be almost completely retained within the system by particle deposition, while more than 50% of the 137Cs derived from both reactor releases and fallout has been exported from the tidal Hudson to coastal waters. Measurements of fallout 239 240 Pu in a saline lake with a high carbonate ion concentration yielded water column activities about two orders of magnitude greater than has been found for fallout plutonium in other continental waters, indicating extensive mobility in some natural water environments. Experiments using lake water suggest that carbonate ion is likely to be a critical factor in regulating plutonium solubility in some environments and that low molecular weight complexes are primarily responsible for enhanced plutonium solubility. 5 references

1983-01-01

324

Production of branched tetraether lipids in the lower Pearl River and estuary: effects of extraction methods and impact on bGDGT proxies  

Directory of Open Access Journals (Sweden)

Full Text Available Branched glycerol dibiphytanyl glycerol tetraethers (bGDGTs are known as bacterial lipids that occur widely in terrestrial environments, particularly in anaerobic peat bogs and soil. We examined the abundance and distribution of bGDGTs in both core (C and polar (P lipid fractions from the water column and surface sediments in the lower Pearl River (PR and its estuary using two extraction methods (sonication vs. Bligh and Dyer. A number of soil samples in the lower PR drainage basin were also collected and extracted for bGDGTs using the sonication method. The results showed aquatic production of bGDGTs as supported by substantial abundances of P-bGDGTs in the water column and sediment samples. The bGDGT-based proxies (BIT, CBT, and MBT were not affected by the method of extraction when C-bGDGTs were analyzed; in such case, the pHCBT of the sediments reflected the soil pH of the lower PR drainage basin, and the temperature close to the annual mean air temperature in the lower PR basin. On the other hand, the P-bGDGT-derived proxies were inconsistent between the two methods. The P-bGDGTs (particularly those extracted using the sonication method may not be reliable indicators of annual mean air temperatures.

ChuanlunZhang

2012-01-01

325

[A study to assess the microbial contamination of Mya arenaria clams from the north shore of the St Lawrence River estuary, (Québec, Canada)].  

Science.gov (United States)

The aims of the present study were to assess the microbial quality of Mya arenaria clams from the north shore of the St. Lawrence River estuary and to validate various microbial indicator microorganisms of bivalve mollusks contamination. Clams were collected from nine sites, including four harvesting sites closed by virtue of the Canadian Shellfish Sanitation Program (CSSP). Six contamination indicators (fecal coliforms, somatic coliphages, F-specific coliphages, fecal streptococci, Clostridium perfringens, and Escherichia coli) and four pathogens (Campylobacter sp., Cryptosporidium parvum, Giardia sp., and Salmonella sp.) were identified in the clams. Indicators sensibility, specificity and predictive values with respect to the presence of pathogens were calculated. Pathogenic microorganisms detection frequency in clams was important (92%). Globally, pathogens tend to be less frequently detected in opened harvesting sites (p = 0.086). Although the assessed indicators were not perfect, when F-specific coliphages are associated with E. coli or fecal coliforms, a good sensibility (62%-64%) and good positive predictive value (88%) with respect to the investigated pathogens are obtained. PMID:17110967

Lévesque, Benoît; Gagnon, Fabien; Valentin, Alexandra; Cartier, Jacques-François; Chevalier, Pierre; Cardinal, Pierrette; Cantin, Philippe; Gingras, Suzanne

2006-10-01

326

Changes of P, Ca, Al and Fe contents in fringe marshes along a pedogenic chronosequence in the Pearl River estuary, South China  

Science.gov (United States)

Soil and plant samples were collected in four fringe marsh zones (i.e., A, B, C and D zones) along a pedogenic chronosequence in the Pearl River estuary in the Spring of 2009. Samples were subjected to a total digestion technique and analyzed for P, Ca, Al and Fe in order to study the changes of nutrient contents, storages in soils and their bioavailabilities to wetland plants (e.g. Cyperus malaccensis) in four zones. Results showed that soil Ca increased with depth along soil profiles, while P, Al and Fe generally kept constant in soil profiles in four zones. Al and Fe contents in the top 10 cm soils showed significant decreases from D to A zone, while a significant increase in Ca contents ( Pmalaccensis. C. malaccensis in D zone had lower Bio-concentration factors (BCFs) of P in the shoots and Al and Fe in the roots, and higher values of Ca in the shoots than those in older zones ( Pmalaccensis, while only lower TFs for P and higher values for Al and Fe in D zone were observed than those in A and B zones ( P<0.05). Except for Al with no significant changes, the total BCFs for P and Fe showed an increasing trend with soil ages, while a decreasing trend for Ca. The total bio-storage factors (TBSFs) of P and Ca declined with the pedogenic time, whereas an increase for Fe. The results of this study can contribute to the wetland conservation and management in the Pearl River estuarine region.

Xiao, Rong; Bai, Junhong; Zhang, Honggang; Gao, Haifeng; Liu, Xinhui; Wilkes, Andreas

2011-04-01

327

Estuary regime  

International Nuclear Information System (INIS)

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

1994-01-01

328

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

International Nuclear Information System (INIS)

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

1975-12-01

329

Plutonium and cesium radionuclides in the Hudson River estuary. Annual technical progress report, December 1, 1976--November 30, 1977  

International Nuclear Information System (INIS)

We have obtained a large set of sediment cores from the Hudson estuary through much of the ambient salinity range. A number of core sections and samples of suspended particles have been analyzed for 137Cs, 134Cs and 60Co by direct gamma counting, and 239Pu, 240Pu, and 238Pu by alpha spectrometry. The distribution of both 137Cs and 239Pu, 240Pu indicates rapid accumulation in marginal cover areas, and especially in the harbor region adjacent to New York City. The distributions of both 137Cs and 239Pu, 240Pu are similar in surface sediments and with depth in cores, but there are deviations from the fallout ratio due to addition of reactor 137Cs and loss of 137Cs from the particle phases at higher salinities. Measureable amounts of reactor-derived 134Cs and 60Co are found in nearly all sediment samples containing appreciable 137Cs, between 15 km upstream of Indian Point and the downstream extent of our sampling, 70 km south of the reactor. Accumulations of 239Pu, 240Pu in New York harbor sediments are more than an order of magnitude greater than the fallout delivery rate. The most likely explanation is accumulation of fine particles in the harbor which have been transported from upstream areas of the Hudson. Our evidence so far indicates that Indian Point is probably not a significant source of 239Pu, 240Pu or 238Pu compared with the fallout burden of these nuclides already in the sediments

1977-01-01

330

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

Energy Technology Data Exchange (ETDEWEB)

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

Simpson, H.J.; Williams, S.C.

1976-01-01

331

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

Science.gov (United States)

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

332

Plutonium, cesium and uranium series radionuclides in the Hudson River estuary and other environments. Annual technical progress report, December 1, 1979-November 30, 1980  

International Nuclear Information System (INIS)

Radionuclide activities were measured in a large number of sediment cores and suspended particle samples throughout the salinity range of the Hudson River estuary. Activities of "1"3"7Cs, "1"3"4Cs and "6"0Co determined by gamma spectrometry and "2"3"9 "2"4"0Pu and "2"3"8Pu determined by alpha spectrometry indicate reasonably rapid accumulation rates in the sediments of marginal cove areas, and very rapid deposition in the harbor region adjacent to New York City, resulting in "2"3"9 "2"4"0Pu accumulations there more than an order of magnitude greater than the fallout delivery rate. Measurable amounts of reactor-derived "1"3"4Cs and "6"0Co are found in nearly al sediment samples containing appreciable "1"3"7Cs between 15 km upstream of Indian Point and the downstream extent of our sampling about 70 km south of the reactor. Fallout "2"3"9 "2"4"0Pu reaching the Hudson appears to be almost completely retained within the systems by particle deposition, while 70 to 90% of the "1"3"7Cs derived from both reactor releases and fallout has been exported to the coastal waters in solution. Activity levels of "2"3"9 "2"4"0Pu in New York harbor sediments indicate a significant source in addition to suspended particles carried down the Hudson. The most likely cause appears to be transport into the estuary of particles from offshore waters having higher specific activities of "2"3"9 "2"4"0Pu. Measurements of fallout "2"3"9 "2"4"0Pu in a saline lake with a high carbonate ion concentration yielded water column activities about two orders of magnitude greater than has been found for fallout plutonium in other continental waters, indicating extensive mobility in some natural water environments. Experiments using lake water suggest that carbonate ion may indeed be a critical factor in regulating plutonium solubility and that low molecular weight complexes are primarily responsible for enhanced plutonium solubility

1980-01-01

333

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

International Nuclear Information System (INIS)

On an annual basis, river supplied nitrate is the predominant form of N supplied to the tidal Potomac River from external sources. Much of the nitrate is associated with high flows that have rapid transit times through the tidal river. After the fall of 1980, initiation of advanced wastewater treatment at the Blue Plains Sewage Treatment Plant (STPP) reduced ammonia loading to the river by 90% and increased nitrate loading by a similar percentage. As a result, concentrations of ammonia during the 1981 low flow period were 1.50 mg/L as N. Despite the reduced availability of ammonia, 15-N uptake studies showed that phytoplankton preferred ammonia to nitrate unless ammonia concentrations were < 0.10 mg/L as N. Nitrification studies during 1981 using a 14-C uptake technique indicate that rates did not vary with sample location, except for one sample from the head of the tidal river, where the rates were much higher. Process models were used in conjunction with mass-balance determinations and individual process studies to estimate rates of processes that were not directly measured. It is estimated that denitrification removed 10 times as much nitrate from the water column during the summer of 1981 as during the summer of 1980. Sedimentation of particulate N is estimated to be the largest sink for N from the water column and was approximately equal to the external annual loading of all N constituents on a daily basis. In summer, when river flows usually are low, the tidal Potomac River appears to be a partially closed system rather than one dominated by transport. Nitrogen constituents, primarily from point sources, are taken up by phytoplankton converted to organic matter, and sedimented from the water column. Some of this N eventually becomes available again by means of benthic exchange. Removal, by transport, out of the tidal river is significant only during winter. 70 refs., 20 figs., 10 tabs

334

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

Scientific Electronic Library Online (English)

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

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

335

Plutonium and cesium radionuclides in the Hudson River Estuary. Annual technical progress report, December 1, 1974--November 30, 1975  

International Nuclear Information System (INIS)

We have obtained a large set of gravity cores from the Hudson Estuary through much of the ambient salinity range. A number of core sections have been analyzed for "1"3"7Cs, "1"3"4Cs, "6"0Co, and "4"0K by direct gamma counting, and for "2"3"9,"2"4"0Pu by alpha-spectrometry. The distribution of both "1"3"7Cs and "2"3"9,"2"4"0Pu indicates rapid accumulation in marginal cove areas and in the harbor region adjacent to New York City. The distribution of both "1"3"7Cs and "2"3"9,"2"4"0Pu in the sediments is quite similar in surface sediments, and the trends with depth in cores are also similar. The ratio of sediment "2"3"9,"2"4"0Pu to "1"3"7Cs throughout the sampled salinity range (0-20 "0/_0_0) approximates that in fallout, except near the nuclear reactor at Indian Point where releases of "1"3"7Cs result in a ratio lower (0.004 to 0.008) than typical of fallout (0.015). Measurement amounts of reactor-derived "1"3"4Cs, "6"0Co, and "5"4Mn are found in nearly all of the samples containing appreciable "1"3"7Cs. These samples were between 15 km upstream of Indian Point reactor site and the downstream extent of our sampling, 70 km south of the reactor

1975-01-01

336

Evaluation of a three-band model for estimating chlorophyll-a concentration in tidal reaches of the Pearl River Estuary, China  

Science.gov (United States)

Accurate assessment of phytoplankton chlorophyll-a (Chla) concentration in turbid waters by means of remote sensing was challenging due to the optical complexity of turbid waters. Recently, a conceptual model containing reflectance in three spectral bands in the red and near-infrared range of the spectrum was suggested for retrieving Chla concentrations in turbid productive waters. The objective of this paper was to evaluate the performance of this three-band model to estimate Chla concentration in the Pearl River Estuary (PRE), China. Reflectance spectra of surface water and water samples were collected concurrently. The samples contained variable Chla (4.80-92.60 mg/m 3) and total suspended solids (0.4-55.2 mg/L dry wt). Colored dissolved organic matter (CDOM) absorption at 400 nm was 0.40-1.41 m -1; turbidity ranged from 4 to 25 NTU (Nephelometric Turbidity Units). The three-band model was spectrally calibrated by iterative and least-square linear regression methods to select the optimal spectral bands for the most accurate Chla estimation. Strong linear relationships ( R2=0.81, RMSE=1.4 mg/m 3, N=32) were established between measured Chla and the levels obtained from the calibrated three-band model [R-1(684)-R-1(690)]×R(718), where R(?) was the reflectance at wavelength ?. The calibrated three-band model was independently validated ( R2=0.9521, RMSE=6.44 mg/m 3, N=16) and applied to retrieve Chla concentrations from the calibrated EO-1 Hyperion reflectance data in the PRE on December 21, 2006. The EO-1 Hyperion-derived Chla concentrations were further validated using synchronous in situ data collected on the same day ( R2=0.64, RMSE=2 mg/m 3, N=9). The spatial tendency of Chla distribution mapping by Hyperion showed gradually increased concentrations of Chla farther from the river mouths (although decreasing from east to west), which were disturbed by the combination of river outlets and tidal current in Lingding Bay of the PRE. This observation conformed to previous observations and studies, and could reasonably be explained by geographical changes. Also, results indicated that the slope of the three-band regression line decreased as the Chla concentration increased, resulting in the first sensitive band of the three-band model to move towards short wavelengths. These findings validated the rationale behind the conceptual model and demonstrated the robustness of this algorithm for Chla retrieval from in situ data and the Hyperion satellite sensor in turbid estuarine waters of the PRE, China.

Chen, Shuisen; Fang, Ligang; Li, Hongli; Chen, Weiqi; Huang, Wenrui

337

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

International Nuclear Information System (INIS)

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

1992-01-01

338

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

Science.gov (United States)

Few studies have specifically dealt so far with methanogen-related archaea in estuarine sediments. In this study, methanogen-related archaeal populations were investigated by 16S rRNA gene clone library, T-RFLP analysis, and methanogen enrichment in Pearl River estuarine sediments. The majority of obtained sequences in clone libraries and T-RF peaks from T-RFLP analysis were assigned mainly to Methanosaeta, Methanomicrobiales, and Methanosarcinales/ANME. The fragments of Methanosarcinales/ANME were most dominant group (mean 47%) and composed largely of ANME-2a which are characterized as anaerobic methane oxidizing archaea in broad environments. Furthermore Methanosaeta and Methanomicrobiales accounted for 23 and 29% of fragments, respectively, for all depths. Therefore, the presence of Methanomicrobiales and Methanosaeta in Pearl River estuarine sediments was indicative of both acetoclastic and hydrogenotrophic methanogenesis. In addition, the enrichments of methanogens also suggested the presence of acetoclastic and hydrogenotrophic methanogens in Pearl River estuarine sediments. This study is a significant step toward understanding methane cycling association of representative archaea in estuarine environments. PMID:23712531

Chen, Jinquan; Wang, Fengping; Zheng, Yanping; Jiang, Lijing; Xiao, Xiang

2014-06-01

339

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

Energy Technology Data Exchange (ETDEWEB)

On an annual basis, river supplied nitrate is the predominant form of N supplied to the tidal Potomac River from external sources. Much of the nitrate is associated with high flows that have rapid transit times through the tidal river. After the fall of 1980, initiation of advanced wastewater treatment at the Blue Plains Sewage Treatment Plant (STPP) reduced ammonia loading to the river by 90% and increased nitrate loading by a similar percentage. As a result, concentrations of ammonia during the 1981 low flow period were < 0.20 mg/L as N at alexandria, while nitrate concentrations were > 1.50 mg/L as N. Despite the reduced availability of ammonia, 15-N uptake studies showed that phytoplankton preferred ammonia to nitrate unless ammonia concentrations were < 0.10 mg/L as N. Nitrification studies during 1981 using a 14-C uptake technique indicate that rates did not vary with sample location, except for one sample from the head of the tidal river, where the rates were much higher. Process models were used in conjunction with mass-balance determinations and individual process studies to estimate rates of processes that were not directly measured. It is estimated that denitrification removed 10 times as much nitrate from the water column during the summer of 1981 as during the summer of 1980. Sedimentation of particulate N is estimated to be the largest sink for N from the water column and was approximately equal to the external annual loading of all N constituents on a daily basis. In summer, when river flows usually are low, the tidal Potomac River appears to be a partially closed system rather than one dominated by transport. Nitrogen constituents, primarily from point sources, are taken up by phytoplankton converted to organic matter, and sedimented from the water column. Some of this N eventually becomes available again by means of benthic exchange. Removal, by transport, out of the tidal river is significant only during winter. 70 refs., 20 figs., 10 tabs.

Shutz, D.J.

1989-01-01

340

Variation of particulate organic carbon and its relationship with bio-optical properties during a phytoplankton bloom in the Pearl River estuary  

International Nuclear Information System (INIS)

Highlights: ? A study about relationship between POC and optical properties during a phytoplankton bloom. ? Empirical algorithms for retrieving POC concentration from optical data were developed. ? Phytoplankton carbon and it's ratio to Chl-a are estimated and discussed. ? Demonstrates that marine optical buoy can be a new platform for monitoring biogeochemical cycle. - Abstract: In this study, variations in the particulate organic carbon (POC) were monitored during a phytoplankton bloom event, and the corresponding changes in bio-optical properties were tracked at one station (114.29oE, 22.06oN) located in the Pearl River estuary. A greater than 10-fold increase in POC (112.29-1173.36 mg m-3) was observed during the bloom, with the chlorophyll a concentration (Chl-a) varying from 0.984 to 25.941 mg m-3. A power law function is used to describe the relationship between POC and Chl-a, and the POC:Chl-a ratio tends to change inversely with Chl-a. Phytoplankton carbon concentration is indirectly estimated using the conceptual model proposed by , and this carbon is found to contribute 47.21% (±10.65%) to total POC. The estimated carbon-to-chlorophyll ratio of phytoplankton in diatom-dominated waters is found to be comparable with results reported in the literature. Empirical algorithms for determining the concentrations of Chl-a and POC were developed based on the relationships of these variables with the blue-to-green reflectance ratio. With these bio-optical models, the levels of particulate organic carbon and Chl-a could be predicted from the radiometric data measured by a marine optical buoy, which showed much more detailed information about the variability in biogeochemical parameters during this bloom event.

2011-09-01

 
 
 
 
341

Plutonium and cesium radionuclides in the Hudson River estuary and other environments. Annual technical progress report, December 1, 1978-November 30, 1979  

International Nuclear Information System (INIS)

Radionuclide activities were measured in a large number of sediment cores and suspended particle samples throughout the salinity range of the Hudson River estuary. Activities of 137Cs, 134Cs and 60Co determined by gamma spectrometry and 239 240Pu and 238Pu determined by alpha spectrometry indicate reasonably rapid accumulation rates in the sediments of marginal cove areas, and very rapid deposition in the harbor region adjacent to New York City. General distributions of 137Cs and 239 240Pu are similar in surface sediments and with depth in cores, but there are deviations from the fallout ratio due to addition of reactor 137Cs and loss of 137Cs from the particle phases at higher salinities. Measurable amounts of reactor-derived 134Cs and 60Co are found in nearly all sediment samples containing appreciable 137Cs between 15 km upstream of Indian Point and the downstream of our sampling about 70 km south of the reactor. Accumulations of 239 240Pu in New York harbor sediments are more than an order of magnitude greater than the fallout delivery rate, probably primarily due to the accumulation of fine particles containing fallout plutonium in the harbor which have been transported from upstream areas of the Hudson. Measurements of fallout 239 240Pu in a saline lake with a high carbonate ion concentration yielded water column activities about two orders of magnitude greater than has been found for fallout plutonium in other continental waters, indicating extensive mobility in some natural water environments. Experiments using lake water suggest that carbonate ion may indeed be a critical factor in regulatory plutonium solubility

1979-01-01

342

Plutonium, cesium, uranium, and thorium series radionuclides in the Hudson River estuary and other environments. Annual technical progress report, December 1, 1981-November 30, 1982  

International Nuclear Information System (INIS)

Radionuclide activities were measured in a large number of sediment cores and suspended particle samples throughout the salinity range of the Hudson River estuary. Activities of "1"3"7Cs, "1"3"4Cs and "6"0Co determined by gamma spectrometry and "2"3"9 "2"4"0Pu and "2"3"8Pu determined by alpha spectrometry indicate reasonably rapid accumulation rates in the sediments of marginal cove areas, and very rapid deposition in the harbor region adjacent to New York City, resulting in "2"3"9 "2"4"0Pu accumulations there more than an order of magnitude greater than the fallout delivery rate. Fallout "2"3"9 "2"4"0Pu moving downstream in the Hudson appears to be almost completely retained within the system by particle deposition, while 80 to 90% of the "1"3"7Cs derived from both reactor releases and fallout has been exported to the coastal waters in solution. Measurements of fallout "2"3"9 "2"4"0Pu in a saline lake with a high carbonate ion concentration yielded water column activities about two orders of magnitude greater than has been found for fallout plutonium in other continental waters, indicating extensive mobility in some natural water environments. Experiments using lake water suggest that carbonate ion is likely to be a critical factor in regulating plutonium solubility in some environments and that low molecular weight complexes are primarily responsible for enhanced plutonium solubility. Activities of several other nuclides of interest in radioactive waste management ("2"3"8U, "2"3"4U, "2"3"2Th, "2"3"0Th, "2"2"8Th, "2"3"1Pa) were also found to be orders of magnitude greater in high carbonate waters than in other natural waters

1982-01-01

343

Plutonium and cesium radionuclides in the Hudson River Estuary and other environments. Annual technical progress report, 1 December 1977--30 November 1978  

International Nuclear Information System (INIS)

Radionuclide activities were measured in a large number of sediment cores and suspended particle samples throughout the salinity range of the Hudson River estuary. Activities of 137Cs, 134Cs, and 60Co determined by gamma spectrometry and 239,240Pu and 238Pu determined by alpha spectrometry indicate reasonably rapid accumulation rates in the sediments of marginal cove areas, and very rapid deposition in the harbor region adjacent to New York City. General distributions of 137Cs and 239,240Pu are similar in surface sediments and with depth in cores, but there are deviations from the fallout ratio due to (1) addition of reactor 137Cs and (2) loss of 137Cs from the particle phases at higher salinities. Measurable amounts of reactor-derived 134Cs and 60Co are found in nearly all sediment samples containing appreciable 137Cs between 15 Km upstream of Indian Point and 70 Km south of the reactor. Accumulations of 239,240Pu in New York harbor sediments are more than an order of magnitude greater than the fallout delivery rate. Depth profiles of radionuclides and variations of activities with particle size at low salinities in the Hudson indicate the importance of organic phases, including large flocculent particles greater than 180?, in binding plutonium, and no evidence of significant chemical migration within the sediments. Measurements of water column fallout 239,240Pu in a saline lake with a high carbonate ion concentration yielded activities about two orders of magnitude greater than has been found for fallout plutonium in other continental waters, indicating extensive mobility in some natural water environments

1977-12-01

344

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

Science.gov (United States)

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

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

1999-03-01