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Sample records for turbid estuary gironde

  1. Origin and composition of particulate organic matter in a macrotidal turbid estuary: The Gironde Estuary, France

    Science.gov (United States)

    Savoye, Nicolas; David, Valérie; Morisseau, François; Etcheber, Henri; Abril, Gwenaël; Billy, Isabelle; Charlier, Karine; Oggian, Georges; Derriennic, Hervé; Sautour, Benoît

    2012-08-01

    At the interface between continent and ocean, estuaries receive particles, and especially particulate organic matter (POM) originating from these two reservoirs, but also produce POM, through autochthonous primary production. The origin and composition of surface POM in the Gironde Estuary (SW France) and the environmental forcing of its variability was investigated using the data set produced by the French Coastal Monitoring Network SOMLIT (Service d'Observation en Milieu LITtoral; monthly like sampling during years 2007-2009). This estuary is considered as a model of macrotidal turbid estuaries. Using elemental and isotopic composition of the POM, we estimated that, at the inner estuary space scale and inter-annual time scale, surface particulate organic carbon (POC) was composed of terrestrial POM originated from the turbidity maximum (96.4%; refractory POC) and flood events (1.6%; labile and refractory POC), and of riverine (0.1%), estuarine (0.8%) and marine (1.1%) phytoplankton, i.e. that POC was 98% and 2% of terrestrial and phytoplankton origin, respectively. However, there was a clear spatial gradient: the phytoplankton contribution increases from ca. 1% in the upper and middle estuary to 8.5% in the lower estuary, where light condition is more favourable to plankton growth. The low contribution of phytoplankton to the POC is a characteristic of the Gironde estuary and contrast with other large temperate estuaries. Statistical analysis indicates that salinity, river flow and SPM concentration, and thus associated hydro-dynamic and sedimentary processes, were the only environmental forcings to the composition of surface POC in this system, at intra- and inter-annual time scale. In contrast, temperature and nutrient concentrations, and thus associated processes, do not force this composition of POC. By combining POC fluxes entering the inner estuary (literature data), POC loss as dissolved organic carbon and CO2 and as sediment trapping within the inner

  2. Bacterial and phytoplankton production in the maximum turbidity zone of three European estuaries: the Elbe, Westerschelde and Gironde

    NARCIS (Netherlands)

    Goosen, N.K.; Kromkamp, J.C.; Peene, J.; Van Rijswijk, P.; Van Breugel, P.

    1999-01-01

    Biomass and production of phytoplankton and heterotrophic bacteria in spring are presented for three turbid European estuaries, the Elbe (Germany), the Westerschelde (The Netherlands) and the Gironde (France), with emphasis on the effect of turbidity on microbial community densities and activities.

  3. Dynamics of coarse particulate matter in the turbidity maximum zone of the Gironde Estuary

    Science.gov (United States)

    Fuentes-Cid, Ana; Etcheber, Henri; Schmidt, Sabine; Abril, Gwenaël; De-Oliveira, Eric; Lepage, Mario; Sottolichio, Aldo

    2014-01-01

    There is a lack of studies devoted to coarse particulate matter (CPM) in estuaries, although this fraction can disturb activities that filter large volumes of water, such as industrial or fishery activities. In the macrotidal and highly-turbid Gironde Estuary, a monthly sampling of CPM was performed in 2011 and 2013 at two stations in the Turbidity Maximum Zone (TMZ) to understand its seasonal, tidal and hydrological dynamics. Regardless of the season and station, low quantities of CPM (few g m-3) were observed in comparison with suspended particulate matter (several 103 g m-3). The highest concentrations were consistently recorded in bottom waters and at the upstream station. Whereas there is no clear link between the CPM present in the column water and spring or neap tides, an increase in the CPM size has been identified at the two stations after a flood event, fact potentially critical regarding filtering functioning of estuarine activities.

  4. Dynamics of the turbidity maximum zone in a macrotidal estuary (the Gironde, France): Observations from field and MODIS satellite data

    Science.gov (United States)

    Doxaran, David; Froidefond, Jean-Marie; Castaing, Patrice; Babin, Marcel

    2009-02-01

    Over a 1-year period, field and satellite measurements of surface water turbidity were combined in order to study the dynamics of the turbidity maximum zone (TM) in a macrotidal estuary (the Gironde, France). Four fixed platforms equipped with turbidity sensors calibrated to give the suspended particulate matter (SPM) concentration provided continuous information in the upper estuary. Full resolution data recorded by the moderate resolution imaging spectroradiometer (MODIS) sensors onboard the Terra and Aqua satellite platforms provided information in the central and lower estuary twice a day (depending on cloud cover). Field data were used to validate a recently developed SPM quantification algorithm applied to the MODIS 'surface reflectance' product. The algorithm is based on a relationship between the SPM concentration and a reflectance ratio of MODIS bands 2 (near-infrared) and 1 (red). Based on 62 and 75 match-ups identified in 2005 with MODIS Terra and Aqua data, the relative uncertainty of the algorithm applied to these sensors was found to be 22 and 18%, respectively. Field measurements showed the tidal variations of turbidity in the upper estuary, while monthly-averaged MODIS satellite data complemented by field data allowed observing the monthly movements of the TM in the whole estuary. The trapping of fine sediments occurred in the upper estuary during the period of low river flow. This resulted in the formation of a highly concentrated TM during a 4-month period. With increasing river flow, the TM moved rapidly to the central estuary. A part of the TM detached, moved progressively in the lower estuary and was finally either massively exported to the ocean during peak floods or temporary trapped (settled) on intertidal mudflats. The massive export to the ocean was apparently the result of combined favorable environmental conditions: presence of fluid mud near the mouth, high river flow, high tides and limited wind speeds. The mean SPM concentration

  5. Impact of urban effluents on summer hypoxia in the highly turbid Gironde Estuary, applying a 3D model coupling hydrodynamics, sediment transport and biogeochemical processes

    Science.gov (United States)

    Lajaunie-Salla, Katixa; Wild-Allen, Karen; Sottolichio, Aldo; Thouvenin, Bénédicte; Litrico, Xavier; Abril, Gwenaël

    2017-10-01

    Estuaries are increasingly degraded due to coastal urban development and are prone to hypoxia problems. The macro-tidal Gironde Estuary is characterized by a highly concentrated turbidity maximum zone (TMZ). Field observations show that hypoxia occurs in summer in the TMZ at low river flow and a few days after the spring tide peak. In situ data highlight lower dissolved oxygen (DO) concentrations around the city of Bordeaux, located in the upper estuary. Interactions between multiple factors limit the understanding of the processes controlling the dynamics of hypoxia. A 3D biogeochemical model was developed, coupled with hydrodynamics and a sediment transport model, to assess the contribution of the TMZ and the impact of urban effluents through wastewater treatment plants (WWTPs) and sewage overflows (SOs) on hypoxia. Our model describes the transport of solutes and suspended material and the biogeochemical mechanisms impacting oxygen: primary production, degradation of all organic matter (i.e. including phytoplankton respiration, degradation of river and urban watershed matter), nitrification and gas exchange. The composition and the degradation rates of each variable were characterized by in situ measurements and experimental data from the study area. The DO model was validated against observations in Bordeaux City. The simulated DO concentrations show good agreement with field observations and satisfactorily reproduce the seasonal and neap-spring time scale variations around the city of Bordeaux. Simulations show a spatial and temporal correlation between the formation of summer hypoxia and the location of the TMZ, with minimum DO centered in the vicinity of Bordeaux. To understand the contribution of the urban watershed forcing, different simulations with the presence or absence of urban effluents were compared. Our results show that in summer, a reduction of POC from SO would increase the DO minimum in the vicinity of Bordeaux by 3% of saturation. Omitting

  6. Impact of climate change on Gironde estuary

    International Nuclear Information System (INIS)

    Laborie, Vanessya; Hissel, Francois; Sergent, Philippe

    2014-01-01

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

  7. Impact of climate change on Gironde Estuary

    Science.gov (United States)

    Laborie, Vanessya; Hissel, François; Sergent, Philippe

    2014-05-01

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

  8. Transient, tidal-scale, nitrogen transformations in an estuarine turbidity maximum-fluid mud system (The Gironde, S.W. France)

    NARCIS (Netherlands)

    Abril, G.; Riou, S.A.; Etcheber, H.; Frankignoulle, M.; De Wit, R.; Middelburg, J.J.

    2000-01-01

    The maximum turbidity zone (MTZ) of the Gironde Estuary is a site of important mineralization of particulate organic nitrogen. Moreover, this MTZ is characterized by intense cycles of settling and resuspension of anoxic fluid mud at both tidal and neap-spring time-scales. In the upper layer of the

  9. Biogeochemistry of the MAximum TURbidity Zone of Estuaries (MATURE): some conclusions

    NARCIS (Netherlands)

    Herman, P.M.J.; Heip, C.H.R.

    1999-01-01

    In this paper, we give a short overview of the activities and main results of the MAximum TURbidity Zone of Estuaries (MATURE) project. Three estuaries (Elbe, Schelde and Gironde) have been sampled intensively during a joint 1-week campaign in both 1993 and 1994. We introduce the publicly available

  10. Sedimentation and erosion trends over 50 years in the macrotidal Gironde estuary

    Science.gov (United States)

    Sottolichio, Aldo; Hanquiez, Vincent; Arriagada, Joselyn; Jalon-Rojas, Isabel

    2017-04-01

    Recent studies have emphasized on the drastic morphodynamic evolution of many european urbanized estuaries, which have become more turbid during the XXth century because of human-induced deepening and narrowing. For some systems, the availability of data has allowed detailed analysis of evolution, while for some other estuaries, knowledge remains limited. For the latter, it is difficult to elucidate any effect due to climate change, extreme events or human activities. Among them, the Gironde estuary is a macrotidal funnel-shape system, the largest estuary of Western Europe, and characterized by high levels of turbidity. Despite numerous investigations on sedimentary processes carried out in this estuary in the past, there is poor knowledge on the evolution of its morphology and tides over the XXth century. Recently, an investigation on tidal patterns has started in the Garonne tidal river, where it is known that gravel extraction during the sixties has deeply modified the mean depth of the channel. In the meantime, there is evidence of a long-term shift of the turbidity maximum in this area, mainly due to a reduction of river flow in the last 40 years. However, for the main estuarine portion, which represents 80% of the total surface, morphology evolution and associated physical processes remain under-investigated. In this study the morphological evolution of the Gironde estuary has been documented and investigated for the first time, based on some bathymetric and tidal data collected from the archives of the port of Bordeaux. Six bathymetric maps covering a period of 50 years, from the 1953 to year 2000 were compared, highlighting areas of accretion and erosion. Results show that the zone of maximum volume of deposited sediment has migrated continuously towards the upstream portion of the estuary, which is coherent with the intensification of the low river flow periods and the upstream shift of the turbidity maximum zone to the riverine sections. In the meantime

  11. Loire and Gironde turbid plumes: Characterization and influence on thermohaline properties

    Science.gov (United States)

    Costoya, X.; Fernández-Nóvoa, D.; deCastro, M.; Gómez-Gesteira, M.

    2017-12-01

    Knowledge and predictability of turbid river plumes is of great importance because they modulate the properties of the seawater adjacent to river mouths. The Loire and Gironde Rivers form the most important plumes in the Bay of Biscay, as they provide > 75% of total runoff. The development of the turbid plume under the influence of its main drivers was analyzed using Moderate Resolution Imaging Spectroradiometer satellite data from the period 2003-2015. River discharge was found to be the main driver, followed by wind, which also had an important effect in modulating the turbid plume during periods of high river discharge. Seaward and upwelling favorable winds enhanced the dispersion of plumes on seawater, whereas landward and downwelling favorable winds limited mixing with the adjacent ocean water. The maximum extension of the turbid plume was reached under landward winds. In addition, the spatio-temporal evolution of the East Atlantic pattern and the North Atlantic Oscillation was observed to affect the dynamics of plumes: positive values of both indices favored a greater extension of the plume. Thermohaline properties differed inside and outside the area affected by both rivers. In particular, these rivers maintain winter stratification inside the turbid plume, which results in a different warming ratio when compared with the adjacent ocean.

  12. Evolution of bacterial communities in the Gironde Estuary (France) according to a salinity gradient

    Science.gov (United States)

    Prieur, D.; Troussellier, M.; Romana, A.; Chamroux, S.; Mevel, G.; Baleux, B.

    1987-01-01

    Three surveys were performed in the Gironde Estuary (France) in August 1981, March 1982 and July 1982. For each campaign, seventy samples were taken by helicopter, in order to follow the tide along the estuary. Of the parameters that were studied, salinity appeared to be the most important and which controls the bacterial communities along the estuary. This paper deals with the evolution of bacterial communities along a salinity gradient. The information obtained from various bacteriological parameters (total bacterial counts, viable counts on salted and unsalted media, functional evenness) were convergent. The bacterial community is dominated by an halotolerant microflora. In the estuary, a continental microflora is followed by a marine microflora. The succession zone between these two microflora is located between 5 and 10‰ areas of salinity.

  13. Future extreme water levels and floodplains in Gironde Estuary considering climate change

    Science.gov (United States)

    Laborie, V.; Hissel, F.; Sergent, P.

    2012-04-01

    Within THESEUS European project, an overflowing model of Gironde Estuary has been used to evaluate future surge levels at Le Verdon and future water levels at 6 specific sites of the estuary : le Verdon, Richard, Laména, Pauillac, Le Marquis and Bordeaux. It was then used to study the evolution of floodplains' location and areas towards 2100 in the entire Estuary. In this study, no breaching and no modification in the elevation of the dike was considered. The model was fed by several data sources : wind fields at Royan and Mérignac interpolated from the grid of the European Climatolologic Model CLM/SGA, a tide signal at Le Verdon, the discharges of Garonne (at La Réole), the Dordogne (at Pessac) and Isle (at Libourne). A simplified mathematical model of surge levels has been adjusted at Le Verdon with 10 surge storms and by using wind and pressure fields given by CLM/SGA. This adjustment was led so that the statistical analysis of the global signal at Le Verdon gives the same quantiles as the same analysis driven on maregraphic observations for the period [1960 ; 2000]. The assumption used for sea level rise was the pessimistic one of the French national institute for climate change: 60 cm in 2100. The model was then used to study the evolution of extreme water levels towards 2100. The analysis of surge levels at Le Verdon shows a decrease in quantiles which is coherent with the analysis of climatologic fields. The analysis of water levels shows that the increase in mean water levels quantiles represents only a part of sea level rise in Gironde Estuary. Moreover this effect seems to decrease from the maritime limit of the model towards upstream. Concerning floodplains, those corresponding to return periods from 2 to 100 years for present conditions and 3 slices [2010; 2039], [2040; 2069] and [2070; 2099] have been mapped for 3 areas in Gironde Estuary : around Le Verdon, at the confluence between Garonne and Dordogne, and near Bordeaux. Concerning the evolution

  14. Comparison of environmental forcings affecting suspended sediments variability in two macrotidal, highly-turbid estuaries

    Science.gov (United States)

    Jalón-Rojas, Isabel; Schmidt, Sabine; Sottolichio, Aldo

    2017-11-01

    The relative contribution of environmental forcing frequencies on turbidity variability is, for the first time, quantified at seasonal and multiannual time scales in tidal estuarine systems. With a decade of high-frequency, multi-site turbidity monitoring, the two nearby, macrotidal and highly-turbid Gironde and Loire estuaries (west France) are excellent natural laboratories for this purpose. Singular Spectrum Analyses, combined with Lomb-Scargle periodograms and Wavelet Transforms, were applied to the continuous multiannual turbidity time series. Frequencies of the main environmental factors affecting turbidity were identified: hydrological regime (high versus low river discharges), river flow variability, tidal range, tidal cycles, and turbulence. Their relative influences show similar patterns in both estuaries and depend on the estuarine region (lower or upper estuary) and the time scale (multiannual or seasonal). On the multiannual time scale, the relative contribution of tidal frequencies (tidal cycles and range) to turbidity variability decreases up-estuary from 68% to 47%, while the influence of river flow frequencies increases from 3% to 42%. On the seasonal time scale, the relative influence of forcings frequencies remains almost constant in the lower estuary, dominated by tidal frequencies (60% and 30% for tidal cycles and tidal range, respectively); in the upper reaches, it is variable depending on hydrological regime, even if tidal frequencies are responsible for up 50% of turbidity variance. These quantifications show the potential of combined spectral analyses to compare the behavior of suspended sediment in tidal estuaries throughout the world and to evaluate long-term changes in environmental forcings, especially in a context of global change. The relevance of this approach to compare nearby and overseas systems and to support management strategies is discussed (e.g., selection of effective operation frequencies/regions, prediction of the most

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

    International Nuclear Information System (INIS)

    Fontugne, Michel; Jouanneau, J.M.

    1981-01-01

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

  16. Effects of Prevailing Winds on Turbidity of a Shallow Estuary

    OpenAIRE

    Cho, Hyun Jung

    2007-01-01

    Estuarine waters are generally more turbid than lakes or marine waters due to greater algal mass and continual re-suspension of sediments. The varying effects of diurnal and seasonal prevailing winds on the turbidity condition of a wind-dominated estuary were investigated by spatial and statistical analyses of wind direction, water level, turbidity, chlorophyll a, and PAR (Photosynthetically Active Radiation) collected in Lake Pontchartrain, Louisiana, USA. The prolonged prevailing winds were...

  17. Effects of Prevailing Winds on Turbidity of a Shallow Estuary

    Directory of Open Access Journals (Sweden)

    Hyun Jung Cho

    2007-06-01

    Full Text Available Estuarine waters are generally more turbid than lakes or marine waters due to greater algal mass and continual re-suspension of sediments. The varying effects of diurnal and seasonal prevailing winds on the turbidity condition of a wind-dominated estuary were investigated by spatial and statistical analyses of wind direction, water level, turbidity, chlorophyll a, and PAR (Photosynthetically Active Radiation collected in Lake Pontchartrain, Louisiana, USA. The prolonged prevailing winds were responsible for the long-term, large-scale turbidity pattern of the estuary, whereas the short-term changes in wind direction had differential effects on turbidity and water level in varying locations. There were temporal and spatial changes in the relationship between vertical light attenuation coefficient (Kd and turbidity, which indicate difference in phytoplankton and color also affect Kd. This study demonstrates that the effect of wind on turbidity and water level on different shores can be identified through system-specific analyses of turbidity patterns.

  18. Mobility of trace metals associated with urban particles exposed to natural waters of various salinities from the Gironde Estuary, France

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Joerg; Blanc, Gerard [Bordeaux Univ., Talence (France). UMR 5805 EPOC; Norra, Stefan [Karlsruhe Univ. (Germany). Inst. of Mineralogy and Geochemistry; Klein, Daniel [Bordeaux Univ., Talence (France). UMR 5805 EPOC; Karlsruhe Univ. (Germany). Inst. of Mineralogy and Geochemistry

    2009-08-15

    Background, aim and scope: Urban systems are hot spots of environmental pollution caused by manifold anthropogenic activities generating traffic-related, industrial and domestic emissions. Besides air, soil and groundwater pollution, pollution of surface water systems is of major concern because they are often (ab)used to export waste of various consistence out of urban areas and become contaminated on varying scales. The Gironde Estuary (southwest France) is affected by various anthropogenic contaminations derived from historic polymetallic pollution mainly due to former mining and ore-treatment and, additionally, from agriculture and urban areas. Although detailed knowledge is available on the impact of mining and anthropogenic activities on the water quality of the Gironde Estuary, almost nothing is known on the urban impact, even though the Garonne Branch which is one tributary of the Gironde system crosses the large urban agglomeration of Bordeaux. The present work links urban geochemistry and estuary research and aims at evaluating the mobility of potentially toxic trace elements (Cd, Cu, Zn, V, Co, Mo, Pb) associated with urban particles under estuarine conditions owing to the particles' role as potential vectors transporting urban pollutants into the estuary. For this, environmentally available fractions of trace elements in representative urban particles (urban dust, road sediment, riverbank sediment, construction materials) from the city of Bordeaux were extracted by natural estuarine waters of varying salinities and compared to commonly applied HNO{sub 3} extractions. Materials and methods: For the assessment of the urban particles' contribution to the pollution of the Gironde/Garonne system, various particle types were sampled in Bordeaux: road sediments, urban bulk deposition, construction materials (concrete, asphalt, tile and gravel) and flood sediments. Potentially environmental available fractions of Cd, Cu, Zn, V, Co, Mo and Pb were

  19. Double radio-tracer tagging of mud in the Gironde: an experimental study of the behaviour of a metallic pollutant in an estuary

    International Nuclear Information System (INIS)

    Etcheber, H.; Jouanneau, J.M.; Latouche, C.; Azoeuf, P.; Caillot, A.; Hoslin, R.

    1980-01-01

    In order to understand the behaviour of metals accidentally introduced into an estuarine system, an experiment using radioactive tracers was conducted in the Gironde estuary. Based on the preliminary laboratory studies on the reactivity of radioisotopes 65 Zn and 175+181 Hf with different physicochemical agents, they were proved to be suitable for the experiment designed. A quantity of sediment contaminated by these two isotopes was introduced in the upstream part of the Gironde. During transport downstream, it was observed that the Zn/Hf couple on the sediment decreased from an initial ratio of 0.7 to 0.07-0.05 in the fluid mud lenses and in the bottom sediment of the lower estuary at the end of the experiment (3 months). It was lower than 0.2 in the suspended sediments. This is considered to indicate that a part of the zinc is dissociated from the hafnium and released from its particulate support; this signifies a solubilization of the zinc. These experimental data give a new insight into the problem concerning the decrease of stable zinc associated with suspended sediment at the fresh water/salt water interface [fr

  20. The particulate 7Be/210Pbxs and 234Th/210Pbxs activity ratios as tracers for tidal-to-seasonal particle dynamics in the Gironde estuary (France): Implications for the budget of particle-associated contaminants

    International Nuclear Information System (INIS)

    Saari, Hanna-Kaisa; Schmidt, Sabine; Castaing, Patrice; Blanc, Gerard; Sautour, Benoit; Masson, Olivier; Cochran, J. Kirk

    2010-01-01

    The short-lived natural radionuclides 7 Be (T 1/2 = 53 days), 234 Th xs (T 1/2 = 24.1 days) and 210 Pb xs (T 1/2 = 22.3 years), i.e. 234 Th and 210 Pb in excesses of that supported within particles by the decay of their parent isotopes, were analysed in suspended particulate matter (SPM) to study the particle dynamics in the Gironde fluvial estuarine system (France), strongly impacted by heavy metal pollution. From surveys of this land-ocean interface in 2006 and 2007, we established a times series of these radioisotopes and of their activity ratios ( 7 Be/ 210 Pb xs and 234 Th/ 210 Pb xs ARs) in particles sampled under different hydrological conditions. The particulate 7 Be/ 210 Pb xs AR varies along the fluvial estuarine system mainly due to variations in 7 Be activities, controlled by riverine, oceanic and atmospheric inputs and by resuspension of old 7 Be-deficient sediments. These processes vary with river discharge, tidal cycle and season. Therefore, seasonal particle transport processes can be described using variations of the SPM 7 Be/ 210 Pb xs ARs. During high river discharge, the SPM 7 Be/ 210 Pb x ARs decrease from river to the ocean. The turbidity maximum zone (TMZ) is dispersed and the particles, and the associated contaminants, are rapidly transported from river to coastal waters, without significant retention within the TMZ. During low river discharge, the TMZ intrudes into the fluvial estuary, and the lowest 7 Be/ 210 Pb x ARs are observed there due to resuspension of 7 Be-deficient sediments. Away from the TMZ, from the middle to lower estuary, SPM 7 Be/ 210 Pb x ARs increase, indicating that the particles have been recently tagged with 7 Be. We explain this trend as being caused by marine input of dissolved radionuclides, as traced by SPM 234 Th/ 210 Pb xs ARs, followed by scavenging in the estuary. This result indicates that particle transport models based on 7 Be and trace-metal budgets must consider oceanic dissolved inputs as an additional

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

    Science.gov (United States)

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

    2005-01-01

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

  2. Three-dimensional semi-idealized model for estuarine turbidity maxima in tidally dominated estuaries

    NARCIS (Netherlands)

    Kumar, Mohit; Schuttelaars, Henk M.; Roos, Pieter C.

    2017-01-01

    We develop a three-dimensional idealized model that is specifically aimed at gaining insight in the physical mechanisms resulting in the formation of estuarine turbidity maxima in tidally dominated estuaries. First, the three-dimensional equations for water motion and suspended sediment

  3. Feedback between residual circulations and sediment distribution in highly turbid estuaries: an analytical model

    NARCIS (Netherlands)

    Talke, S.A.|info:eu-repo/dai/nl/304823554; de Swart, H.E.|info:eu-repo/dai/nl/073449725; Schuttelaars, H.|info:eu-repo/dai/nl/164035656

    2009-01-01

    Motivated by field studies of the Ems estuary which show longitudinal gradients in bottom sediment concentration as high as O(0.01 kg/m4), we develop an analytical model for estuarine residual circulation based on currents from salinity gradients, turbidity gradients, and freshwater discharge.

  4. Factors governing the pH in a heterotrophic, turbid, tidal estuary

    NARCIS (Netherlands)

    Hofmann, A.F.; Meysman, F.J.R.; Soetaert, K.; Middelburg, J.J.

    2009-01-01

    A method to quantify the influence of kinetically modelled biogeochemical processes on the pH of an ecosystem with time variable acid-base dissociation constants is presented and applied to the heterotrophic, turbid Scheldt estuary (SW Netherlands, N Belgium). Nitrification is identified as the main

  5. Initial growth of phytoplankton in turbid estuaries: a simple model

    NARCIS (Netherlands)

    de Swart, H.E.; Schuttelaars, H.; Talke, S.A.

    2009-01-01

    An idealised model is presented and analysed to gain more fundamental understanding about the dynamics of phytoplankton blooms in well-mixed, suspended sediment dominated estuaries. The model describes the behaviour of subtidal currents, suspended sediments, nutrients and phytoplankton in a channel

  6. Factors governing the pH in a heterotrophic, turbid, tidal estuary

    Science.gov (United States)

    Hofmann, A. F.; Meysman, F. J. R.; Soetaert, K.; Middelburg, J. J.

    2009-01-01

    A method to quantify the influence of kinetically modelled biogeochemical processes on the pH of an ecosystem with time variable acid-base dissociation constants is presented and applied to the heterotrophic, turbid Scheldt estuary (SW Netherlands, N Belgium). Nitrification is identified as the main process governing the pH profile of this estuary, while CO2 degassing and advective-dispersive transport "buffer" the effect of nitrification. CO2 degassing accounts for the largest proton turnover per year in the whole estuary. There is a clear inverse correlation between oxygen turnover and proton turnover. The main driver of long-term changes in the mean estuarine pH from 2001 to 2004 is a changing freshwater flow which influences the pH "directly" via [∑CO2] and [TA] and to a significant amount also "indirectly" via [∑NH4+] and the nitrification rates in the estuary.

  7. Multi-sensor analysis to study turbidity patterns in the Guadalquivir estuary

    OpenAIRE

    I. Caballero; G. Navarro

    2016-01-01

    Revista oficial de la Asociación Española de Teledetección [EN] A detailed study of the mechanisms generated through the turbidity plume and its variability at the Guadalquivir estuary has been carried out with remote sensing and in situ data. Several sensors with different characteristics have been required (spatial, temporal and spectral resolution), thereby providing information for a multi-sensor analysis. The main objective was to determine the water quality parameters (suspended soli...

  8. MASEX '83, a survey of the turbidity maximum in the Weser Estuary

    International Nuclear Information System (INIS)

    Fanger, H.U.; Neumann, L.; Ohm, K.; Riethmueller, R.

    1986-01-01

    A one-week survey of the turbidity maximum in the Weser Estuary was conducted in the Fall of 1983 using the survey ship RV 'Victor Hensen'. Supplemental measurements were taken using in-situ current - conductivity - temperature - turbidity meters. The thickness of the bottom mud was determined using a gamma-ray transmission probe and compared with core sample analysis. The location of no-net tidal averaged bottom flow was determined to be at km 57. The off-ship measurements were taken using a CTD probe combined with a light attenuation meter. A comparison between salinity and attenuation gives insight into the relative importance of erosion, sedimentation and advective transport. (orig.) [de

  9. Characterization of turbidity in Florida's Lake Okeechobee and Caloosahatchee and St. Lucie estuaries using MODIS-Aqua measurements.

    Science.gov (United States)

    Wang, Menghua; Nim, Carl J; Son, Seunghyun; Shi, Wei

    2012-10-15

    This paper describes the use of ocean color remote sensing data from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite to characterize turbidity in Lake Okeechobee and its primary drainage basins, the Caloosahatchee and St. Lucie estuaries from 2002 to 2010. Drainage modification and agricultural development in southern Florida transport sediments and nutrients from watershed agricultural areas to Lake Okeechobee. As a result of development around Lake Okeechobee and the estuaries that are connected to Lake Okeechobee, estuarine conditions have also been adversely impacted, resulting in salinity and nutrient fluctuations. The measurement of water turbidity in lacustrine and estuarine ecosystems allows researchers to understand important factors such as light limitation and the potential release of nutrients from re-suspended sediments. Based on a strong correlation between water turbidity and normalized water-leaving radiance at the near-infrared (NIR) band (nL(w)(869)), a new satellite water turbidity algorithm has been developed for Lake Okeechobee. This study has shown important applications with satellite-measured nL(w)(869) data for water quality monitoring and measurements for turbid inland lakes. MODIS-Aqua-measured water property data are derived using the shortwave infrared (SWIR)-based atmospheric correction algorithm in order to remotely obtain synoptic turbidity data in Lake Okeechobee and normalized water-leaving radiance using the red band (nL(w)(645)) in the Caloosahatchee and St. Lucie estuaries. We found varied, but distinct seasonal, spatial, and event driven turbidity trends in Lake Okeechobee and the Caloosahatchee and St. Lucie estuary regions. Wind waves and hurricanes have the largest influence on turbidity trends in Lake Okeechobee, while tides, currents, wind waves, and hurricanes influence the Caloosahatchee and St. Lucie estuarine areas. Published by Elsevier Ltd.

  10. The influence of channel deepening on estuarine turbidity levels and dynamics, as exemplified by the Ems estuary

    NARCIS (Netherlands)

    de Jonge, V.N.; Schuttelaars, H.M.; van Beusekom, J.E.E.; Talke, S.A.|info:eu-repo/dai/nl/304823554; de Swart, H.E.|info:eu-repo/dai/nl/073449725

    2014-01-01

    Active deepening of tidal channels usually results in the alteration of the vertical and the horizontal tide. This may lead to concurrent significant increases in mean suspended matter concentrations (SPM) in coastal plain estuaries, the turbidity maximum (ETM) included. This is exemplified by an

  11. Comparison of Heterotrophic Bacterial Production-Rates in Early Spring in the Turbid Estuaries of the Scheldt and the Elbe

    NARCIS (Netherlands)

    Goosen, N.K.; Van Rijswijk, P.; Brockmann, U.

    1995-01-01

    In spring bacterial production rates were estimated by tritiated thymidine incorporation in the turbid estuaries of the rivers Scheldt and Elbe. Bacterial production rates in the Scheldt were 5 times higher than in the Elbe. In the Scheldt bacterial production rates correlated better with the DOC

  12. Multi-sensor analysis to study turbidity patterns in the Guadalquivir estuary

    Directory of Open Access Journals (Sweden)

    I. Caballero

    2016-06-01

    Full Text Available A detailed study of the mechanisms generated through the turbidity plume and its variability at the Guadalquivir estuary has been carried out with remote sensing and in situ data. Several sensors with different characteristics have been required (spatial, temporal and spectral resolution, thereby providing information for a multi-sensor analysis. The main objective was to determine the water quality parameters (suspended solids and chlorophyll and implement the methodology to define the empirical and semi-analytical algorithms from satellite data (MODIS, METIS, Deimos-1. The processes occurred in the estuary and adjacent region have been examined identifying those involved in the different variability scales. The forcings associated with rainfall and discharge from Alcalá del Río dam in addition to the climatic NAO index control seasonal and inter-annual fluctuations, while tide effects (semi-daily and fortnightly cycles modulate the plume at the mouth throughout the year with significant variability. Special emphasis is focused on diagnosing the role of these mechanisms on the continental shelf ecosystems, constituting a powerful tool for the water quality management and coastal resources.

  13. Spring habitat use by stocked one year old European sturgeon Acipenser sturio in the freshwater-oligohaline area of the Gironde estuary

    Science.gov (United States)

    Acolas, M. L.; Le Pichon, C.; Rochard, E.

    2017-09-01

    Post release habitat selection was studied on forty eight 10-month-old hatchery reared European sturgeon (mean fork length 31.0 cm ± 3.0) in the tidal part of their native catchment using acoustic telemetry. Most of the fish reached the oligohaline estuary within 2-4 days (70 km downstream the release site). Seventy four percent of the fish migrated rapidly downstream of the estuary into mesohaline waters while 26% selected habitat in the freshwater/oligohaline part of the estuary based on their linearity and residency indices. We focused on individual habitat use of these fish. The home range size (HR) was calculated using two methods: the kernel utilization distribution (KUD) which is driven by the maximum detection location density, and the Brownian Bridge (BB) approach which allows the time component of the trajectory path to be taken into account. The average 50% HR KUD was 5.6 ± 2.7 km2 (range 1.1-10.3 km2) and it was estimated to be 6 times larger using the 50% HR BB method (average reaching 31.9 ± 20.7 km2, range 5.2-77.8 km2). Habitat characterization (available prey, substrate and depth) in the studied area was described and the Ivlev electivity index was calculated using the habitat within the 50% HR BB for each individual. Despite the spatial use of different core areas among the fish tagged, we observed a convergence in habitat preference. For substrates, sturgeons showed avoidance of gravel and large rocks as well as fine and medium gravel. There was a significant preference for sand, silts and clay. For depth, they exhibited a preference firstly for the 5-8 m depth range and secondly for the 2-5 m range, a strong avoidance of depth range 8-20 m and a slight avoidance of shallow (0-2 m) and intertidal areas. For prey, individual variability was high. The most homogenous results were found for annelid polychaeta, with a slight preference for areas with this group of preys which are abundant in the saline estuary. For some individuals, a preference

  14. Inputs, dynamics and potential impacts of silver (Ag) from urban wastewater to a highly turbid estuary (SW France).

    Science.gov (United States)

    Deycard, Victoria N; Schäfer, Jörg; Petit, Jérôme C J; Coynel, Alexandra; Lanceleur, Laurent; Dutruch, Lionel; Bossy, Cécile; Ventura, Alexandre; Blanc, Gérard

    2017-01-01

    Although silver (Ag) has been listed as a priority pollutant for the aquatic environment by the European Union (Directive 2006/11/EC), the use of Ag-based products with antimicrobial effects is increasing in Europe, as well as North America and Asia. This study investigates personal care products (PCP) as a potential source of Ag in wastewater, as well as the dynamics and fate of Ag in the influent and effluent of a major urban wastewater treatment plant (WWTP) located on the fluvial part of the Gironde Estuary. Typical household PCPs marked as using Ag contained concentrations of up to 0.4 mg kg -1 making them likely contributors to urban Ag released into the aquatic environment. Silver concentrations in influent wastewater generally occurred during mid-week working hours and decreased during the night and on weekends clearly indicating the dominance of urban sources. Up to 90% of the total Ag in wastewater was bound to particles and efficiently (>80%) removed by the treatment process, whereas 20% of Ag was released into the fluvial estuary. Silver concentrations in wastewater effluents clearly exceeded estuarine concentrations and may strongly amplify the local Ag concentrations and fluxes, especially during summer rainstorms in low river discharge conditions. Further work should focus on environmental effects and fate of urban Ag release due to immediate localized outfall and/or the adsorption on estuarine particles and subsequent release as dissolved Ag chloro-complexes within the estuarine salinity gradient. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Tidal variations of flow convergence, shear, and stratification at the Rio de la Plata estuary turbidity front

    Science.gov (United States)

    FramiñAn, Mariana B.; Valle-Levinson, Arnoldo; Sepúlveda, HéCtor H.; Brown, Otis B.

    2008-08-01

    Intratidal variability of density and velocity fields is investigated at the turbidity front of the Río de la Plata Estuary, South America. Current velocity and temperature-salinity profiles collected in August 1999 along a repeated transect crossing the front are analyzed. Horizontal and vertical gradients, stability of the front, convergence zones, and transverse flow associated to the frontal boundary are described. Strong horizontal convergence of the across-front velocity and build up of along-front velocity shear were observed at the front. In the proximity of the front, enhanced transverse (or along-front) flow created jet-like structures at the surface and near the bottom flowing in opposite directions. These structures persisted throughout the tidal cycle and were advected upstream (downstream) by the flood (ebb) current through a distance of ˜10 km. During peak flood, the upper layer flow reversed from its predominant downstream direction and upstreamflow occupied the entire water column; outside the peak flood, two-layer estuarine circulation dominated. Changes in density field were observed in response to tidal straining, tidal advection, and wind-induced mixing, but stratification remained throughout the tidal cycle. This work demonstrates the large spatial variability of the velocity field at the turbidity front; it provides evidence of enhanced transverse circulation along the frontal boundary; and reveals the importance of advective and frictional intratidal processes in the dynamics of the central part of the estuary.

  16. Cycling of 7Be and 210Pb in a high DOC, shallow, turbid estuary of south-east Texas

    International Nuclear Information System (INIS)

    Baskaran, M.; Ravichandran, M.; Bianchi, T.S.

    1997-01-01

    The Sabine-Neches estuary is a shallow, turbid estuary in south-east Texas with high concentrations of dissolved organic carbon (DOC). The sediment inventory of 210 Pb and 239 , 240 Pu indicates that only a fraction of the particle-associated nuclides that reach the estuary were retained in the sediment. To better understand the cause for this low-sediment inventory of particle-reactive nuclides, 7 Be and 210 Pb concentrations have been measured in the dissolved and particulate phases, in addition to the DOC and suspended particle concentrations. The ratios of dissolved to particulate concentrations of 7 Be and 210 Pb were generally higher than in most other coastal waters. The dissolved residence times of 7 Be and 210 Pb (accounting for riverine input) varied between 0.6 and 9.6 days and 1.7 and 9.8 days, respectively. Distribution coefficients (Kd) ranged between 1500 and 87 100 cm 3 g -1 for 7 Be and 2600 and 37 000 cm 3 g -1 for 210 Pb. These K d s are lower than those reported for most coastal waters. There was no significant correlation between suspended particle concentration and K d of either 7 Be and 210 Pb; this has been observed for many other particle-reactive nuclides, suggesting that particle is not the primary controlling variable for the removal of particle-reactive nuclides in these high DOC waters. The average particle residence time in this estuary is ∼ 2 days. The relatively low K d values, longer dissolved residence times of 7 Be and 210 Pb, longer particle residence times and shorter hydraulic residence times compared to other coastal areas, result in only a partial removal of particle-reactive radionuclides in this estuary. (author)

  17. Comparison of nitrifier activity versus growth in the scheldt estuary - a turbid, tidal estuary in northern Europe

    NARCIS (Netherlands)

    Andersson, M.G.I.; Brion, N.; Middelburg, J.J.

    2006-01-01

    Nitrifier activity and growth were measured in the Scheldt estuary over a salinity gradient. Measurements were made during all 4 seasons using 15N enriched ammonium and 14C labeled carbon incorporation. Established conversion ratios are often used to convert the growth of nitrifiers (measured as the

  18. Turbidity-induced changes in feeding strategies of fish in estuaries

    African Journals Online (AJOL)

    1991-11-12

    Nov 12, 1991 ... in hatching success (Rosenthal & Alderdice 1976), egg sur- .... ther turbidity reduces feeding rate and thirdly whether turbi- dity reduces the reactive ...... composition and suspended sediment on insect predation by the torrent ...

  19. Sediment source, turbidity maximum, and implications for mud exchange between channel and mangroves in an Amazonian estuary

    Science.gov (United States)

    Asp, Nils Edvin; Gomes, Vando José Costa; Ogston, Andrea; Borges, José Carlos Corrêa; Nittrouer, Charles Albert

    2016-02-01

    The tide-dominated eastern sector of the Brazilian Amazonian coast includes large mangrove areas and several estuaries, including the estuary associated with the Urumajó River. There, the dynamics of suspended sediments and delivery mechanisms for mud to the tidal flats and mangroves are complex and were investigated in this study. Four longitudinal measuring campaigns were carried out, encompassing spring/neap tides and dry/rainy seasons. During spring tides, water levels were measured simultaneously at 5 points along the estuary. Currents, salinity, and suspended sediment concentrations (SSCs) were measured over the tidal cycle in a cross section at the middle sector of the estuary. Results show a marked turbidity maximum zone (TMZ) during the rainy season, with a 4-km upstream displacement from neap to spring tide. During dry season, the TMZ was conspicuous only during neap tide and dislocated about 5 km upstream and was substantially less apparent in comparison to that observed during rainy season. The results show that mud is being concentrated in the channel associated with the TMZ especially during the rainy season. At this time, a substantial amount of the mud is washed out from mangroves to the estuarine channel and hydrodynamic/salinity conditions for TMZ formation are optimal. As expected, transport to the mangrove flats is most effective during spring tide and substantially reduced at neap tide, when mangroves are not being flooded. During the dry season, mud is resuspended from the bed in the TMZ sector and is a source of sediment delivered to the tidal flats and mangroves. The seasonal variation of the sediments on the seabed is in agreement with the variation of suspended sediments as well.

  20. Turbidity maximum formation in a well-mixed macrotidal estuary : The role of tidal pumping

    NARCIS (Netherlands)

    Yu, Q.; Wang, Y.; Gao, J.; Gao, S.; Flemming, B.

    2014-01-01

    Traditionally, vertical circulation (induced by gravity circulation and tidal straining), tidal pumping, and resuspension are suggested as the major processes for the formation and maintenance of the estuarine turbidity maximum (ETM). Due to strong mixing, tidal pumping is considered as the

  1. Wind-driven estuarine turbidity maxima in Mandovi Estuary, central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Kessarkar, P.M.; Rao, V.P.; Shynu, R.; Ahmad, I.M.; Mehra, P.; Michael, G.S.; Sundar, D.

    Systematic studies on the suspended particulate matter (SPM) measured on a seasonal cycle in the Mandovi Estuary, Goa indicate that the average concentrations of SPM at the regular station are approx. 20mg/l, 5mg/l, 19mg/l and 5mg/l for June...

  2. Towards a long-term chlorophyll-a data record in a turbid estuary using MODIS observations

    Science.gov (United States)

    Le, Chengfeng; Hu, Chuanmin; English, David; Cannizzaro, Jennifer; Chen, Zhiqiang; Feng, Lian; Boler, Richard; Kovach, Charles

    2013-02-01

    Despite recent advances in using satellite data for continuous monitoring of estuarine water quality parameters such as turbidity and water clarity, estimating chlorophyll-a concentrations (Chla) has remained problematic due to the optical complexity of estuarine waters and imperfect atmospheric correction. This poses a significant challenge to the community as synoptic and frequent Chla “measurements” from satellites are in high demand by various government agencies and environmental groups to help make management decisions. Here, using 10 years of in situ and Moderate Resolution Imaging Spectroradiometer (MODIS) measurements from a moderately sized, turbid estuary, Tampa Bay (Florida, USA), we developed and validated a new algorithm specifically designed for retrieving Chla from MODIS data. The algorithm takes the red-to-green remote-sensing reflectance (Rrs(λ)) band ratio of [Rrs(667) + Rrs(678)]/[Rrs(531) + Rrs(547)] as the independent variable, and estimates Chla through the non-linear regression function: Ln(Chla) = 1.91Ln(x) + 3.40 (R2 = 0.87, N = 97, p < 0.01, 1.5 < Chla < 80 mg m-3) where ‘x' is the band ratio. Validation of the algorithm using two independent datasets collected by different groups and near-concurrent MODIS measurements showed robust algorithm performance for Chla within this range, with mean relative errors of 25.8% and 41.7% for the two datasets. Time-series analyses at representative stations using both in situ and MODIS Chla also showed general agreement, with instances of noticeable discrepancy attributed to different measurement frequencies. The algorithm was implemented to establish a 10-year Chla data record for Tampa Bay in order to serve as a baseline for monitoring future phytoplankton bloom events. The 10-year Chla data record showed substantial variability in both space and time, with generally higher Chla observed during the wet season and in upper bay segments, and Chla minima observed in all bay segments during May

  3. MERIS Retrieval of Water Quality Components in the Turbid Albemarle-Pamlico Sound Estuary, USA

    Directory of Open Access Journals (Sweden)

    Hans W. Paerl

    2011-04-01

    Full Text Available Two remote-sensing optical algorithms for the retrieval of the water quality components (WQCs in the Albemarle-Pamlico Estuarine System (APES were developed and validated for chlorophyll a (Chl. Both algorithms were semi-empirical because they incorporated some elements of optical processes in the atmosphere, water, and air/water interface. One incorporated a very simple atmospheric correction and modified quasi-single-scattering approximation (QSSA for estimating the spectral Gordon’s parameter, and the second estimated WQCs directly from the top of atmosphere satellite radiance without atmospheric corrections. A modified version of the Global Meteorological Database for Solar Energy and Applied Meteorology (METEONORM was used to estimate directional atmospheric transmittances. The study incorporated in situ Chl data from the Ferry-Based Monitoring (FerryMon program collected in the Neuse River Estuary (n = 633 and Pamlico Sound (n = 362, along with Medium Resolution Imaging Spectrometer (MERIS satellite imagery collected (2006–2009 across the APES; providing quasi-coinciding samples for Chl algorithm development and validation. Results indicated a coefficient of determination (R2 of 0.70 and mean-normalized root-mean-squares errors (NRMSE of 52% in the Neuse River Estuary and R2 = 0.44 (NRMSE = 75 % in the Pamlico Sound—without atmospheric corrections. The simple atmospheric correction tested provided on performance improvements. Algorithm performance demonstrated the potential for supporting long-term operational WQCs satellite monitoring in the APES.

  4. Compréhension de l’impact de l’argent comme contaminant émergent dans les estuaires d’Ibaizabal et de la Gironde

    OpenAIRE

    Rementeria Ugalde , Ane

    2016-01-01

    Estuaries have been subjected to a high human pressure which has led to the presence of pollutants in their waters and sediments including trace metals. The estuaries in the Bay of Biscay do not constitute an exception of this situation and the Ibaizabal and Gironde Estuaries are both very well known for having high metal concentrations in different compartments. In this context, environmental health monitoring programmes have relied on the use of mussels and oysters as sentinel organisms bec...

  5. Multi-temporal dynamics of suspended particulate matter in a macro-tidal river Plume (the Gironde) as observed by satellite data

    Science.gov (United States)

    Constantin, Sorin; Doxaran, David; Derkacheva, Anna; Novoa, Stéfani; Lavigne, Héloïse

    2018-03-01

    The Gironde River plume area is unique in terms of Suspended Particulate Matter (SPM) dynamics. Multiple factors contribute to the variations of SPM at multiple time scales, from river outputs to wind stress, currents and tidal cycles. The formation and evolution of the Maximum Turbidity Zone (MTZ) inside the estuary also plays a significant role. Thus, detailed analyses and monitoring of the region is important for better understanding the mechanisms governing the turbid plume dynamics, for proper future management and monitoring of SPM export from the estuary to the coastal ocean. In this study we use an unprecedented volume of satellite data to capture and better understand the dynamics of the river plume. We combine two types of satellite information in order to achieve these goals: data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Spinning Enhanced Visible and Infrared Imager (SEVIRI) sensors. The integrated information allows accounting for multiple time scales, i.e. from seasonal to diurnal cycles. We show and parameterize the overall effects of river discharge rates over the plume extension. Seasonal variations are also analyzed and an overall relationship between river discharge rates and plume magnitude is computed. For the first time, we clearly observe and explain the diurnal cycle of SPM dynamics in the river plume. Despite the limited capabilities of the SEVIRI sensor, geostationary data was successfully used to derive such information and results similar to in-situ datasets were obtained. The same patterns are observed, with significant increase in SPM plume during spring/ebb tide periods. Results from our study can be further used to refine sediment transport models and to gain a better perspective on the ecological implications of the sediment output in the continental shelf area.

  6. The Impact of High-Turbidity Water's Seasonal and Decadal Variations on Offshore Phytoplankton and Nutrients Dynamics around The Changjiang Estuary

    Science.gov (United States)

    Ge, J.; Torres, R.; Chen, C.; Bellerby, R. G. J.

    2017-12-01

    The Changjiang Estuary is characterized as strong river discharge into the inner shelf of the East China Sea with abundant sediment load, producing significant high-turbidity water coverage from river mouth to deep region. The growth of offshore phytoplankton is dynamically controlled by river flushed low-salinity and high-turbidity water, and salter water from inner shelf of East China Sea. During last decade, the sediment and nutrients from the Changjiang River has significantly changed, which lead to the variation of offshore phytoplankton dynamics. The variations of sediment, nutrients, and their influenced phytoplankton has been simulated through a comprehensive modeling system, which integrated a multi-scale current-wave-sediment FVCOM model and generic marine biogeochemistry and ecosystem ERSEM model through The Framework for Aquatic Biogeochemical Models (FABM). This model system has successfully revealed the seasonal and decadal variations of sediment, nutrients transport around the inner shelf of the East China Sea. The spring and autumn peaks of phytoplankton growth were correctly captured by simulation. The modeling results, as well as MODIS and GOCI remote sensing, shows a strong sediment decreasing from northern to southern region, which creates different patterns of Chlorophyll-a distribution and seasonal variations. These results indicate the high-turbidity water in northern region strongly influenced the light attenuation in the water column and limits the phytoplankton growth in this relatively higher-nutrient area, especially in the wintertime. The relatively low-turbidity southern region has significant productivity of phytoplankton, even during low-temperature winter. The phytoplankton growth increased in the northern region from 2005 to 2010, with the increase of the nutrient load during this period. Then it became a decreasing trend after 2010.

  7. Tidal effects on short-term mesozooplankton distribution in small channels of a temperate-turbid estuary, Southwestern Atlantic

    Directory of Open Access Journals (Sweden)

    Javier Chazarreta

    2015-06-01

    Full Text Available Abstract The short-term variability of mesozooplankton distribution and physicochemical variables was examined in two different channels of the Bahía Blanca Estuary, Argentina, during two tidal cycles. All the physicochemical measurements and mesozooplankton sampling were performed at a fixed site during approximately 22-23 h at 3-h intervals. Pumps were used to obtain surface and bottom mesozooplankton samples and the water speed of each stratum was measured with an Acoustic Doppler Current Profiler (ADCP. In all, 23 mesozooplanktonic taxa belonging to four phyla (Arthropoda, Annelida, Echinodermata and Chordata were identified. The most abundant taxa during the two tidal cycles were Balanus glandula larvae, Eurytemora americana and Acartia tonsa. A discernible variability in the water conditions and vertical mesozooplankton distribution (VMD different from that known for the estuary's main channel, was found in the other two selected channels. VMD varied during the tidal cycle in both channels in accordance with the channel's geomorphology and water dynamic characteristics of each of them. The variation of the abundance of the different taxa during ebb and flood currents might indicate the existence of a tidal vertical migration of the mesozooplankton as a response to particular dynamic water conditions.

  8. Estuarine Turbidity Maxima and Variations of Aggregate Parameters in the Cam-Nam Trieu Estuary, North Vietnam, in Early Wet Season

    Directory of Open Access Journals (Sweden)

    Vu Duy Vinh

    2018-01-01

    Full Text Available This study aims at exploring the characteristic parameters of the Estuarine Turbidity Maxima (ETM and at investigating their tidal variations within the Cam-Nam Trieu estuary (North Vietnam during the early wet season. Six longitudinal river transects were performed at spring tide. Two types of ETM were observed: an upper well mixed ETM with high Suspended Particulate Matter (SPM concentrations up to the surface at low salinity (0.11 to <1 psu, and a lower ETM confined in a bottom layer over stratified waters at salinities between ~1 psu and 15 psu. Their length depended on the longitudinal salinity gradient and was highest at low tide than at high tide. D50 of the flocs varied between 35 and 90 μm, their excess of density between 60 and 300 kg m−3 and their settling velocity ranged from 0.07 to 0.55 mm s−1 with values between 0.12 and 0.40 mm s−1 in the core of ETMs. The average fractal dimension of flocs was estimated to vary between 1.93 (at high tide to 2.04 (at low tide.

  9. Atmospheric Corrections and Multi-Conditional Algorithm for Multi-Sensor Remote Sensing of Suspended Particulate Matter in Low-to-High Turbidity Levels Coastal Waters

    Directory of Open Access Journals (Sweden)

    Stéfani Novoa

    2017-01-01

    Full Text Available The accurate measurement of suspended particulate matter (SPM concentrations in coastal waters is of crucial importance for ecosystem studies, sediment transport monitoring, and assessment of anthropogenic impacts in the coastal ocean. Ocean color remote sensing is an efficient tool to monitor SPM spatio-temporal variability in coastal waters. However, near-shore satellite images are complex to correct for atmospheric effects due to the proximity of land and to the high level of reflectance caused by high SPM concentrations in the visible and near-infrared spectral regions. The water reflectance signal (ρw tends to saturate at short visible wavelengths when the SPM concentration increases. Using a comprehensive dataset of high-resolution satellite imagery and in situ SPM and water reflectance data, this study presents (i an assessment of existing atmospheric correction (AC algorithms developed for turbid coastal waters; and (ii a switching method that automatically selects the most sensitive SPM vs. ρw relationship, to avoid saturation effects when computing the SPM concentration. The approach is applied to satellite data acquired by three medium-high spatial resolution sensors (Landsat-8/Operational Land Imager, National Polar-Orbiting Partnership/Visible Infrared Imaging Radiometer Suite and Aqua/Moderate Resolution Imaging Spectrometer to map the SPM concentration in some of the most turbid areas of the European coastal ocean, namely the Gironde and Loire estuaries as well as Bourgneuf Bay on the French Atlantic coast. For all three sensors, AC methods based on the use of short-wave infrared (SWIR spectral bands were tested, and the consistency of the retrieved water reflectance was examined along transects from low- to high-turbidity waters. For OLI data, we also compared a SWIR-based AC (ACOLITE with a method based on multi-temporal analyses of atmospheric constituents (MACCS. For the selected scenes, the ACOLITE-MACCS difference was

  10. REE in suspended particulate matter and sediment of the Zuari estuary and adjacent shelf, western India: Influence of mining and estuarine turbidity

    Digital Repository Service at National Institute of Oceanography (India)

    Shynu, R.; Rao, V.P.; Parthiban, G.; Balakrishnan, S.; Narvekar, T.; Kessarkar, P.M.

    in the development of ETM in the lower estuary (Rao et al., 2011). As a consequence bottom sediment may have been re-suspended, thereby increasing SPM and REE in the water column and mixed up with the sediment brought by the river. In other words, the REE.... Seminar Volume on Earth Resources for Goa’s Development. Geological Survey of India, pp. 1-13. Goldstein, S.J., Jacobsen, S.B., 1988. Rare earth elements in river waters. Earth Planetary Science Letters 89, 35-47. Govindaraju, K., 1994. Compilation...

  11. Sediment-water oxygen, ammonium and soluble reactive phosphorus fluxes in a turbid freshwater estuary (Curonian lagoon, Lithuania: evidences of benthic microalgal activity

    Directory of Open Access Journals (Sweden)

    Marco Bartoli

    2012-07-01

    Full Text Available Seasonal measurements of total and diffusive benthic fluxes were performed during the ice-free period in the Curonian Lagoon (Lithuania. This mostly freshwater hypertrophic basin exhibits wide seasonal variations of water temperature (1-22°C and inorganic nitrogen availability and it is subjected to dramatic blooms of diatoms and cyanobacteria (>100 μg chl a l-1. In this shallow lagoon, nutrient exchanges at the sediment-water interface and the regulating factors have been poorly explored. Overall aim of the present work is to demonstrate that the activity of benthic microalgae, generally neglected in turbid systems, can be a relevant regulator of sedimentary processes. To this purpose, light and dark fluxes of oxygen, ammonium and soluble reactive phosphorus were measured seasonally by intact core laboratory incubation and diffusive fluxes were calculated from sediment profiles. We investigated sandy sediments that were collected from the central area lagoon, that is representative of the most of the shallower lagoon area. Oxygen and ammonium fluxes were significantly different under light and dark incubations, suggesting an active role of benthic microalgae at the sediment-water interface. In the light net oxygen production was measured in three out of four samplings, with July as only exception, and ammonium was retained within sediments. In the dark sediment respiration displayed a temperature-dependent pattern while ammonium efflux increased from March to October. Fluxes of reactive phosphorus varied significantly with sampling seasons but were less affected by the incubation condition. Diffusive fluxes peaked in July, where highest concentration gradients at the interface and theoretical efflux of ammonium and reactive phosphorous were calculated. The marked differences between diffusive and total nutrient fluxes are probably due to photosynthetic activity by benthic microalgae, and thus oxygen production, enhancement of aerobic

  12. Long-term records of cadmium and silver contamination in sediments and oysters from the Gironde fluvial-estuarine continuum - evidence of changing silver sources.

    Science.gov (United States)

    Lanceleur, Laurent; Schäfer, Jörg; Chiffoleau, Jean-François; Blanc, Gérard; Auger, Dominique; Renault, Sophie; Baudrimont, Magalie; Audry, Stéphane

    2011-11-01

    The Gironde fluvial estuarine system is impacted by historic metal pollution (e.g. Cd, Zn, Hg) and oysters (Crassostrea gigas) from the estuary mouth have shown extremely high Cd concentrations for decades. Based on recent work (Chiffoleau et al., 2005) revealing anomalously high Ag concentrations (up to 65 mg kg(-1); dry weight) in Gironde oysters, we compared long-term (~1955-2001) records of Ag and Cd concentrations in reservoir sediment with the respective concentrations in oysters collected between 1979 and 2010 to identify the origin and historical trend of the recently discovered Ag anomaly. Sediment cores from two reservoirs upstream and downstream from the main metal pollution source provided information on (i) geochemical background (upstream; Ag: ~0.3 mg kg(-1); Cd: ~0.8 mg kg(-1)) and (ii) historical trends in Ag and Cd pollution. The results showed parallel concentration-depth profiles of Ag and Cd supporting a common source and transport. Decreasing concentrations since 1986 (Cd: from 300 to 11 mg kg(-1); Ag: from 6.7 to 0.43 mg kg(-1)) reflected the termination of Zn ore treatment in the Decazeville basin followed by remediation actions. Accordingly, Cd concentrations in oysters decreased after 1988 (from 109 to 26 mg kg(-1), dry weight (dw)), while Ag bioaccumulation increased from 38 up to 116 mg kg(-1), dw after 1993. Based on the Cd/Ag ratio (Cd/Ag~2) in oysters sampled before the termination of zinc ore treatment (1981-1985) and assuming that nearly all Cd in oysters originated from the metal point source, we estimated the respective contribution of Ag from this source to Ag concentrations in oysters. The evolution over the past 30 years clearly suggested that the recent, unexplained Ag concentrations in oysters are due to increasing contributions (>70% after 1999) by other sources, such as photography, electronics and emerging Ag applications/materials. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Nitrogen cycling in a turbid, tidal estuary

    NARCIS (Netherlands)

    Andersson, M.G.I.

    2007-01-01

    In this thesis I investigated nitrification, dissolved inorganic and organic nitrogen uptake, and the relative importance of nitrification and ammonium assimilation. I have also investigated exchange with marshes and sediments. Nitrification, oxidation of ammonium to nitrate is the first step for

  14. The Swift Turbidity Marker

    Science.gov (United States)

    Omar, Ahmad Fairuz; MatJafri, Mohd Zubir

    2011-01-01

    The Swift Turbidity Marker is an optical instrument developed to measure the level of water turbidity. The components and configuration selected for the system are based on common turbidity meter design concepts but use a simplified methodology to produce rapid turbidity measurements. This work is aimed at high school physics students and is the…

  15. Solar radiation and its penetration in a tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Qasim, S.Z.; Bhattathiri, P.M.A.; Abidi, S.A.H.

    The Cochin Backwater which is an estuarine area on the west coast of India receives maximum solar radiation from December to March and minimum from June to September. During the monsoon months the estuary becomes highly turbid as a result...

  16. Using the Surface Reflectance MODIS Terra Product to Estimate Turbidity in Tampa Bay, Florida

    OpenAIRE

    Douglas L. Rickman; Frank E. Muller-Karger; Max J. Moreno-Madrinan; Mohammad Z. Al-Hamdan

    2010-01-01

    Turbidity is a commonly-used index of the factors that determine light penetration in the water column. Consistent estimation of turbidity is crucial to design environmental and restoration management plans, to predict fate of possible pollutants, and to estimate sedimentary fluxes into the ocean. Traditional methods monitoring fixed geographical locations at fixed intervals may not be representative of the mean water turbidity in estuaries between intervals, and can be expensive and time con...

  17. Water Quality Drivers in 11 Gulf of Mexico Estuaries

    Directory of Open Access Journals (Sweden)

    Matthew J. McCarthy

    2018-02-01

    Full Text Available Coastal water-quality is both a primary driver and also a consequence of coastal ecosystem health. Turbidity, a measure of dissolved and particulate water-quality matter, is a proxy for water quality, and varies on daily to interannual periods. Turbidity is influenced by a variety of factors, including algal particles, colored dissolved organic matter, and suspended sediments. Identifying which factors drive trends and extreme events in turbidity in an estuary helps environmental managers and decision makers plan for and mitigate against water-quality issues. Efforts to do so on large spatial scales have been hampered due to limitations of turbidity data, including coarse and irregular temporal resolution and poor spatial coverage. We addressed these issues by deriving a proxy for turbidity using ocean color satellite products for 11 Gulf of Mexico estuaries from 2000 to 2014 on weekly, monthly, seasonal, and annual time-steps. Drivers were identified using Akaike’s Information Criterion and multiple regressions to model turbidity against precipitation, wind speed, U and V wind vectors, river discharge, water level, and El Nino Southern Oscillation and North Atlantic Oscillation climate indices. Turbidity variability was best explained by wind speed across estuaries for both time-series and extreme turbidity events, although more dynamic patterns were found between estuaries over various time steps.

  18. Water Quality Drivers in 11 Gulf of Mexico Estuaries

    OpenAIRE

    Matthew J. McCarthy; Daniel B. Otis; Pablo Méndez-Lázaro; Frank E. Muller-Karger

    2018-01-01

    Coastal water-quality is both a primary driver and also a consequence of coastal ecosystem health. Turbidity, a measure of dissolved and particulate water-quality matter, is a proxy for water quality, and varies on daily to interannual periods. Turbidity is influenced by a variety of factors, including algal particles, colored dissolved organic matter, and suspended sediments. Identifying which factors drive trends and extreme events in turbidity in an estuary helps environmental managers and...

  19. Conditions for tidal bore formation in convergent alluvial estuaries

    Science.gov (United States)

    Bonneton, Philippe; Filippini, Andrea Gilberto; Arpaia, Luca; Bonneton, Natalie; Ricchiuto, Mario

    2016-04-01

    Over the last decade there has been an increasing interest in tidal bore dynamics. However most studies have been focused on small-scale bore processes. The present paper describes the first quantitative study, at the estuary scale, of the conditions for tidal bore formation in convergent alluvial estuaries. When freshwater discharge and large-scale spatial variations of the estuary water depth can be neglected, tide propagation in such estuaries is controlled by three main dimensionless parameters: the nonlinearity parameter ε0 , the convergence ratio δ0 and the friction parameter ϕ0. In this paper we explore this dimensionless parameter space, in terms of tidal bore occurrence, from a database of 21 estuaries (8 tidal-bore estuaries and 13 non tidal-bore estuaries). The field data point out that tidal bores occur for convergence ratios close to the critical convergence δc. A new proposed definition of the friction parameter highlights a clear separation on the parameter plane (ϕ0,ε0) between tidal-bore estuaries and non tidal-bore estuaries. More specifically, we have established that tidal bores occur in convergent estuaries when the nonlinearity parameter is greater than a critical value, εc , which is an increasing function of the friction parameter ϕ0. This result has been confirmed by numerical simulations of the two-dimensional Saint Venant equations. The real-estuary observations and the numerical simulations also show that, contrary to what is generally assumed, tide amplification is not a necessary condition for tidal bore formation. The effect of freshwater discharge on tidal bore occurrence has been analyzed from the database acquired during three long-term campaigns carried out on the Gironde/Garonne estuary. We have shown that in the upper estuary the tidal bore intensity is mainly governed by the local dimensionless tide amplitude ε. The bore intensity is an increasing function of ε and this relationship does not depend on freshwater

  20. Turbidity Current Bedforms

    NARCIS (Netherlands)

    Cartigny, Matthieu; Postma, G.

    2017-01-01

    Turbidity currents in the submarine seascape are what river flows are in terrestrial landscapes. While rivers transport sediment from the mountains through valleys towards the sea, turbidity currents transport sediment from the shallow marine realms through canyons towards the deeper abyssal plains.

  1. Sediment Trapping in Estuaries

    Science.gov (United States)

    Burchard, Hans; Schuttelaars, Henk M.; Ralston, David K.

    2018-01-01

    Estuarine turbidity maxima (ETMs) are generated by a large suite of hydrodynamic and sediment dynamic processes, leading to longitudinal convergence of cross-sectionally integrated and tidally averaged transport of cohesive and noncohesive suspended particulate matter (SPM). The relative importance of these processes for SPM trapping varies substantially among estuaries depending on topography, fluvial and tidal forcing, and SPM composition. The high-frequency dynamics of ETMs are constrained by interactions with the low-frequency dynamics of the bottom pool of easily erodible sediments. Here, we use a transport decomposition to present processes that lead to convergent SPM transport, and review trapping mechanisms that lead to ETMs at the landward limit of the salt intrusion, in the freshwater zone, at topographic transitions, and by lateral processes within the cross section. We use model simulations of example estuaries to demonstrate the complex concurrence of ETM formation mechanisms. We also discuss how changes in SPM trapping mechanisms, often caused by direct human interference, can lead to the generation of hyperturbid estuaries.

  2. Compact turbidity meter

    Science.gov (United States)

    Hirschberg, J. G.

    1979-01-01

    Proposed monitor that detects back-reflected infrared radiation makes in situ turbidity measurements of lakes, streams, and other bodies of water. Monitor is compact, works well in daylight as at night, and is easily operated in rough seas.

  3. Multiple scales of suspendend sediment dynamics in a complex geometry estuary

    NARCIS (Netherlands)

    Achete,F.M.

    2016-01-01

    Many estuaries are located in urbanized, highly engineered environments. Cohesive sediment plays an important role because of its affect on estuarine health and ecology. An important ecological parameter is the suspended sediment concentration (SSC) translated into turbidity levels and sediment

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

    International Nuclear Information System (INIS)

    Jeandel, C.P.

    1981-10-01

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

  5. Research of Intelligent Turbidity Sensor

    OpenAIRE

    Licai Zhang; Yaoguang Wei; Yingyi Chen; Daoliang Li; Lihua Zeng

    2014-01-01

    Turbidity is an important index to evaluate the water quality. Turbidity can reflect the effects of insoluble substances that contain bait and seston on water. Traditional methods of turbidity detection are complicated, they have low efficiency and poor reliability. To solve the turbidity detection problem in aquaculture, an intelligent optical turbidity sensor which is based on scattering theory has been proposed in this paper. After analyzing the quality characteristics of aquaculture water...

  6. Local heritage to singularize a wine terroir: the example of pays Foyen (Gironde, France

    Directory of Open Access Journals (Sweden)

    Chantal Crenn

    2007-04-01

    Full Text Available Le vin, enjeu culturel et économique, se trouve aujourd’hui au cœur de dynamiques locales œuvrant à produire de la différence : souvent sous l’impulsion de néoruraux, des éléments naturels et d’histoire locale sont sélectionnés et mobilisés pour recomposer un patrimoine fondateur d’identité, fabriquer une authenticité, et donc légitimer des pratiques. Cet article propose d’observer le phénomène de patrimonialisation afin de comprendre comment les frontières se sont progressivement resserrées autour d’un vin régional devenu un vin local, à travers l’exemple d’un espace viti-vinicole, le Pays Foyen (Gironde, France. Après avoir éclairé les tensions théoriques entre global et local, nous nous intéressons particulièrement au processus de territorialisation et de construction identitaire lié à la mise en valeur du « local » dans le produit.Wine, as a cultural and economic product, is today at the heart of local dynamics working towards producing singularity: often under the impulse of neorurals, elements from the local environment and history are selected and used to recompose a heritage which creates an identity, to make up authenticity, therefore to legitimize specific practices. This paper aims at highlighting the current phenomenon of patrimonialization in order to understand how a regional wine turned into a local wine through the observation of a wine terroir, the Pays Foyen (Gironde, France. After theoretic considerations on global/local tensions, we’ll concentrate on spatial definitions and identity construction linked to the promotion of “locality” in the product.

  7. Comparison of the different methods for the recovery of suspended matter from estuarine waters: deposition, filtration and centrifugation

    Energy Technology Data Exchange (ETDEWEB)

    Etcheber, H; Jouanneau, J M

    1980-12-01

    The advantages and disadvantages of three methods used to recover heavy metals from estuarine waters are compared. Deposition, filtration, and centrifugation were used on samples from the Gironde estuary of France. Recovery by deposition is satisfactory in cases of flocculation and high turbidity. Centrifugation is reliable for the determination of several elements in zones of low turbidity. (12 references, 4 tables)

  8. A review on substances and processes relevant for optical remote sensing of extremely turbid marine areas, with a focus on the Wadden Sea

    NARCIS (Netherlands)

    Hommersom, A.; Wernand, M.R.; Peters, S.W.M.; de Boer, J.

    2010-01-01

    The interpretation of optical remote sensing data of estuaries and tidal flat areas is hampered by optical complexity and often extreme turbidity. Extremely high concentrations of suspended matter, chlorophyll and dissolved organic matter, local differences, seasonal and tidal variations and

  9. Aluminum Corrosion and Turbidity

    International Nuclear Information System (INIS)

    Longtin, F.B.

    2003-01-01

    Aluminum corrosion and turbidity formation in reactors correlate with fuel sheath temperature. To further substantiate this correlation, discharged fuel elements from R-3, P-2 and K-2 cycles were examined for extent of corrosion and evidence of breaking off of the oxide film. This report discusses this study

  10. Optics of turbid slabs

    International Nuclear Information System (INIS)

    Kokhanovsky, A.A.

    2002-01-01

    This paper is devoted to an alternative derivation of the asymptotic equations for the reflection and transmission functions of turbid slabs. The derivation is based on the reciprocity principle and the law of conservation of energy. Thus it is very general. This allows us to apply the obtained equations even in cases where the foundations of the radiative transfer theory are in question (e.g. for highly concentrated suspensions and pastes). (author)

  11. The effect of submerged aquatic vegetation expansion on a declining turbidity trend in the Sacramento-San Joaquin River Delta

    Science.gov (United States)

    Hestir, E.L.; Schoellhamer, David H.; Jonathan Greenberg,; Morgan-King, Tara L.; Ustin, S.L.

    2016-01-01

    Submerged aquatic vegetation (SAV) has well-documented effects on water clarity. SAV beds can slow water movement and reduce bed shear stress, promoting sedimentation and reducing suspension. However, estuaries have multiple controls on turbidity that make it difficult to determine the effect of SAV on water clarity. In this study, we investigated the effect of primarily invasive SAV expansion on a concomitant decline in turbidity in the Sacramento-San Joaquin River Delta. The objective of this study was to separate the effects of decreasing sediment supply from the watershed from increasing SAV cover to determine the effect of SAV on the declining turbidity trend. SAV cover was determined by airborne hyperspectral remote sensing and turbidity data from long-term monitoring records. The turbidity trends were corrected for the declining sediment supply using suspended-sediment concentration data from a station immediately upstream of the Delta. We found a significant negative trend in turbidity from 1975 to 2008, and when we removed the sediment supply signal from the trend it was still significant and negative, indicating that a factor other than sediment supply was responsible for part of the turbidity decline. Turbidity monitoring stations with high rates of SAV expansion had steeper and more significant turbidity trends than those with low SAV cover. Our findings suggest that SAV is an important (but not sole) factor in the turbidity decline, and we estimate that 21–70 % of the total declining turbidity trend is due to SAV expansion.

  12. Suspended sediment dynamics in Cochin estuary, West coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Vinita, J.; Revichandran, C.; Manoj, N.T.

    concentration (SSC) were conducted at spring and neap periods of wet and dry seasons. These data were complemented by measurements of tides, currents, vertical profiling of hydrography and turbidity at the main inlet of the estuary. The results showed that SSC...

  13. Some results of turbidity networks

    OpenAIRE

    Volz, F. E.

    2011-01-01

    Turbidity networks to obtain daily values of haze attenuation from measurements of solar radiation, mostly by means of sun photometers, were established in 1961 in the USA by the National Center for Air Pollution Control, Cincinnati, Ohio, and in Western Europe from 1963 to 1967 by the author. The course of turbidity in the two networks during interesting periods is presented. Discussion of synoptic variations of turbidity is rather difficult, when referring to periods of rapid change of air ...

  14. Turbidity Current Head Mixing

    Science.gov (United States)

    Hernandez, David; Sanchez, Miguel Angel; Medina, Pablo

    2010-05-01

    A laboratory experimental set - up for studying the behaviour of sediment in presence of a turbulent field with zero mean flow is compared with the behaviour of turbidity currents [1] . Particular interest is shown on the initiation of sediment motion and in the sediment lift - off. The behaviour of the turbidity current in a flat ground is compared with the zero mean flow oscilating grid generated turbulence as when wave flow lifts off suspended sediments [2,3]. Some examples of the results obtained with this set-up relating the height of the head of the turbidity current to the equilibrium level of stirred lutoclines are shown. A turbulent velocity u' lower than that estimated by the Shield diagram is required to start sediment motion. The minimum u' required to start sediment lift - off, is a function of sediment size, cohesivity and resting time. The lutocline height depends on u', and the vorticity at the lutocline seems constant for a fixed sediment size [1,3]. Combining grid stirring and turbidty current head shapes analyzed by means of advanced image analysis, sediment vertical fluxes and settling speeds can be measured [4,5]. [1] D. Hernandez Turbulent structure of turbidity currents and sediment transport Ms Thesis ETSECCPB, UPC. Barcelona 2009. [2] A. Sánchez-Arcilla; A. Rodríguez; J.C. Santás; J.M. Redondo; V. Gracia; R. K'Osyan; S. Kuznetsov; C. Mösso. Delta'96 Surf-zone and nearshore measurements at the Ebro Delta. A: International Conference on Coastal Research through large Scale Experiments (Coastal Dynamics '97). University of Plymouth, 1997, p. 186-187. [3] P. Medina, M. A. Sánchez and J. M. Redondo. Grid stirred turbulence: applications to the initiation of sediment motion and lift-off studies Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere. 26, Issue 4, 2001, Pages 299-304 [4] M.O. Bezerra, M. Diez, C. Medeiros, A. Rodriguez, E. Bahia., A. Sanchez-Arcilla and J.M. Redondo. Study on the influence of waves on

  15. Turbidity interferes with foraging success of visual but not chemosensory predators.

    Science.gov (United States)

    Lunt, Jessica; Smee, Delbert L

    2015-01-01

    Predation can significantly affect prey populations and communities, but predator effects can be attenuated when abiotic conditions interfere with foraging activities. In estuarine communities, turbidity can affect species richness and abundance and is changing in many areas because of coastal development. Many fish species are less efficient foragers in turbid waters, and previous research revealed that in elevated turbidity, fish are less abundant whereas crabs and shrimp are more abundant. We hypothesized that turbidity altered predatory interactions in estuaries by interfering with visually-foraging predators and prey but not with organisms relying on chemoreception. We measured the effects of turbidity on the predation rates of two model predators: a visual predator (pinfish, Lagodon rhomboides) and a chemosensory predator (blue crabs, Callinectes sapidus) in clear and turbid water (0 and ∼100 nephelometric turbidity units). Feeding assays were conducted with two prey items, mud crabs (Panopeus spp.) that rely heavily on chemoreception to detect predators, and brown shrimp (Farfantepenaus aztecus) that use both chemical and visual cues for predator detection. Because turbidity reduced pinfish foraging on both mud crabs and shrimp, the changes in predation rates are likely driven by turbidity attenuating fish foraging ability and not by affecting prey vulnerability to fish consumers. Blue crab foraging was unaffected by turbidity, and blue crabs were able to successfully consume nearly all mud crab and shrimp prey. Turbidity can influence predator-prey interactions by reducing the feeding efficiency of visual predators, providing a competitive advantage to chemosensory predators, and altering top-down control in food webs.

  16. Analysis of Suspended-Sediment Dynamics in Gulf of Mexico Estuaries Using MODIS/Terra 250-m Imagery

    Science.gov (United States)

    McCarthy, M. J.; Otis, D. B.; Muller-Karger, F. E.; Mendez-Lazaro, P.; Chen, F. R.

    2016-02-01

    Suspended sediments in coastal ecosystems reduce light penetration, degrade water quality, and inhibit primary production. In this study, a 15-year Moderate Resolution Imaging Spectroradiometer (MODIS/Terra) turbidity time-series was developed for use in the estuaries of the Gulf of Mexico (GOM). Remote-sensing reflectance (Rrs) at 645 nm and 250-m resolution was validated with in-situ turbidity measurements in these estuaries: Coastal Bend Bays (TX), Galveston Bay (TX), Barataria and Terrebonne Bays (LA), Mobile Bay (AL), Tampa Bay (FL), Sarasota Bay (FL), and Charlotte Harbor (FL). Mean values of turbidity over the time-series ranged from 2.5 NTU to over 10 NTU. Turbidity patterns exhibited seasonal cycles with peak values generally found during spring months, although there is considerable variability in the timing of peak turbidity. Episodes of elevated turbidity ranged from 6 episodes in Galveston Bay to 15 in Mobile Bay. The spatial extent of elevated turbidity within estuaries, frequency and duration of turbidity events, and potential driving factors behind episodes of elevated turbidity were also examined.

  17. Differential turbidity measurements at Hanford

    International Nuclear Information System (INIS)

    Laulainen, N.S.; Bates, J.A.; Kleckner, E.W.; Michalsky, J.J.; Schrotke, P.M.; Thorp, J.M.

    1978-01-01

    An experiment to exmine differential turbidity effects on measured insolation between the Rattlesnake Observatory and the Hanford Meteorological Station was conducted during summer 1977. Several types of solar radiation instruments were used, including pyranometers, multiwavelength sunphotometers, and an active cavity radiometer. Preliminary results show dramatic temporal variability of aerosol loading at HMS and significant insolation and turbidity differences between the Observatory and HMS

  18. Karakteristik Total Padatan Tersuspensi (Total Suspended Solid Dan Kekeruhan (Turbidity Secara Vertikal Di Perairan Teluk Benoa, Bali

    Directory of Open Access Journals (Sweden)

    I Gede Hendrawan

    2016-06-01

    Full Text Available Benoa bay is one of estuary that located in the Southern part of Bali Island, and as a strategic tourism destination. The increased of the human activity has an important role to give an ecological pressure for the seawater ecosystem in the Benoa bay. Total suspended solid (TSS and turbidity is one of the important indicators that could be determining the quality of the seawater. As the estuary, Benoa bay received fresh water from the river discharge that also potentially carries any material to the bay. In addition, port activity is also has an important role in contributing a various material to the Benoa bay. From this research, we found that the TSS concentration and the turbidity are higher in the surface water and also in the bottom layer. TSS concentration and the turbidity also varied from the bay mouth trough the line of vessel onto the inner of bay. TSS concentration and turbidity in the bay mouth has a smaller concentration rather than in the inner part of bay. TSS concentration and turbidity in the inner of bay could be caused by the port activity. In addition, seawater circulation is also has an importan factor to contributing the TSS concentration and the turbidity. Sea current would be erroted the seabottom and with the different shape of the topography could be increased the TSS and turbidity.

  19. Differential turbidity at Hanford

    International Nuclear Information System (INIS)

    Laulainen, N.S.; Kleckner, E.W.; Michalsky, J.J.; Stokes, G.M.

    1980-01-01

    Experiments continued in FY 1979 to examine differential turbidity effects on insolation as measured at the earth's surface. These experiments are primarily intended to provide means for interpreting insolation-data assessment studies. These data are also valuable for inferring aerosol radiative or optical effects, which is an important consideration in evaluating inadvertent climate modification and visibility degradation as a result of aerosols. The experiments are characterized by frequent, nearly simultaneous observations at the Rattlesnake Mountain Observatory (RMO) and the Hanford Meteorological Station (HMS) and take advantage of the nearly 1-km altitude difference between these two observing sites. This study indicated that nearly simultaneous measurements of the direct solar beam from stationary sites that are separated in altitude can be used to monitor the incremental optical depth arising from aerosols in the intervening layer. Once appropriate calbiration procedures have been established for the MASP unit, the direct solar data can be used to document on a routine basis aerosol variations in the first kilometer between HMS and RMO

  20. Application of a colorimeter for turbidity measurement

    Science.gov (United States)

    Wen, Yizhang; Hu, Yingtian; Wang, Xiaoping

    2016-02-01

    This paper describes a new turbidity transducer based on color measurement. The absorbance of solutions reflects the absorption and scattering of suspended particle for incident light which could determine the turbidity of solutions. The experimental results indicate that there are good linear relationships between chromaticity and turbidity. The new way is suitable for continuous monitoring of water turbidity in the wide range.

  1. Application of a colorimeter for turbidity measurement

    International Nuclear Information System (INIS)

    Wen, Yizhang; Hu, Yingtian; Wang, Xiaoping

    2016-01-01

    This paper describes a new turbidity transducer based on color measurement. The absorbance of solutions reflects the absorption and scattering of suspended particle for incident light which could determine the turbidity of solutions. The experimental results indicate that there are good linear relationships between chromaticity and turbidity. The new way is suitable for continuous monitoring of water turbidity in the wide range. (paper)

  2. Estuary Data Mapper (EDM)

    Science.gov (United States)

    Estuary Data Mapper is a tool for geospatial data discovery, visualization, and data download for any of the approximately 2,000 estuaries and associated watersheds in along the five US coastal regions

  3. Climate Ready Estuaries

    Science.gov (United States)

    Information on climate change impacts to different estuary regions, tools and resources to monitor changes, and information to help managers develop adaptation plans for risk management of estuaries and coastal communities.

  4. Carbon Flows in the Westerschelde Estuary (the Netherlands) Evaluated by Means of an Ecosystem Model (Moses)

    NARCIS (Netherlands)

    Soetaert, K.E.R.; Herman, P.M.J.

    1995-01-01

    The autotrophic production and heterotrophic consumption of organic matter in the Westerschelde, a highly turbid and eutrophic estuary in the Southwest Netherlands is examined by means of a dynamic simulation model. The model describes the ecologically relevant processes in thirteen spatial

  5. DOCUMENTING THE INTERTIDAL COMPONENT OF EELGRASS DISTRIBUTIONS IN PACIFIC NORTHWEST ESTUARIES USING COLOR INFRARED AERIAL PHOTOGRAPHY

    Science.gov (United States)

    The objective of this study was to develop and test a rapid, cost-effective method of mapping the intertidal (and surface-visible subtidal) distribution of eelgrass (Zostera marina L.) meadows and patches in the turbid coastal estuaries of the Pacific Northwest (PNW). Initial co...

  6. Seasonal and inter-annual turbidity variability in the Rio de la Plata from 15 years of MODIS: El Niño dilution effect

    OpenAIRE

    Dogliotti, A.I.; Ruddick, K.; Guerrero, R.

    2016-01-01

    Spatio-temporal variability of turbidity in the Río de la Plata (RdP) estuary (Argentina) at seasonal and inter-annual timescales is analyzed from 15 years (2000–2014) of MODIS data and explained in terms of river discharges and the El Niño Southern Oscillation (ENSO). Satellite estimates were first validated using in situ turbidity measurements and then the time series of monthly averages were analyzed to assess the seasonal and inter-annual variability of turbidity. A strong seasonal variab...

  7. Local Estuary Programs

    Science.gov (United States)

    This page provides information about Local Individual Estuary Programs including links to their NEP homepages, social media, Comprehensive Conservation and Management Plans, and state of the bay reports.

  8. Milwaukee Estuary AOC

    Science.gov (United States)

    The rivers in the Milwaukee estuary in Wisconsin drain into Lake Michigan. Wastewater treatment plants and combined sewer overflows contribute pollution which affects fish and wildlife and recreation.

  9. Influence of main forcing affecting the Tagus turbid plume under high river discharges using MODIS imagery.

    Science.gov (United States)

    Fernández-Nóvoa, D; Gómez-Gesteira, M; Mendes, R; deCastro, M; Vaz, N; Dias, J M

    2017-01-01

    The role of river discharge, wind and tide on the extension and variability of the Tagus River plume was analyzed from 2003 to 2015. This study was performed combining daily images obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor located onboard the Aqua and Terra satellites. Composites were generated by averaging pixels with the same forcing conditions. River discharge shows a strong relation with the extension of the Tagus plume. The plume grows with the increasing river discharge and express a two day lag caused by the long residence time of water within the estuary. The Tagus turbid plume was found to be smaller under northerly and easterly winds, than under southerly and westerly winds. It is suggested that upwelling favoring winds provoke the offshore movement of the plume material with a rapidly decrease in turbidity values whereas downwelling favoring winds retain plume material in the north coast close to the Tagus mouth. Eastern cross-shore (oceanward) winds spread the plume seaward and to the north following the coast geometry, whereas western cross-shore (landward) winds keep the plume material in both alongshore directions occupying a large part of the area enclosed by the bay. Low tides produce larger and more turbid plumes than high tides. In terms of fortnightly periodicity, the maximum plume extension corresponding to the highest turbidity is observed during and after spring tides. Minimum plume extension associated with the lowest turbidity occurs during and after neap tides.

  10. Influence of main forcing affecting the Tagus turbid plume under high river discharges using MODIS imagery.

    Directory of Open Access Journals (Sweden)

    D Fernández-Nóvoa

    Full Text Available The role of river discharge, wind and tide on the extension and variability of the Tagus River plume was analyzed from 2003 to 2015. This study was performed combining daily images obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS sensor located onboard the Aqua and Terra satellites. Composites were generated by averaging pixels with the same forcing conditions. River discharge shows a strong relation with the extension of the Tagus plume. The plume grows with the increasing river discharge and express a two day lag caused by the long residence time of water within the estuary. The Tagus turbid plume was found to be smaller under northerly and easterly winds, than under southerly and westerly winds. It is suggested that upwelling favoring winds provoke the offshore movement of the plume material with a rapidly decrease in turbidity values whereas downwelling favoring winds retain plume material in the north coast close to the Tagus mouth. Eastern cross-shore (oceanward winds spread the plume seaward and to the north following the coast geometry, whereas western cross-shore (landward winds keep the plume material in both alongshore directions occupying a large part of the area enclosed by the bay. Low tides produce larger and more turbid plumes than high tides. In terms of fortnightly periodicity, the maximum plume extension corresponding to the highest turbidity is observed during and after spring tides. Minimum plume extension associated with the lowest turbidity occurs during and after neap tides.

  11. Using the Surface Reflectance MODIS Terra Product to Estimate Turbidity in Tampa Bay, Florida

    Directory of Open Access Journals (Sweden)

    Douglas L. Rickman

    2010-12-01

    Full Text Available Turbidity is a commonly-used index of the factors that determine light penetration in the water column. Consistent estimation of turbidity is crucial to design environmental and restoration management plans, to predict fate of possible pollutants, and to estimate sedimentary fluxes into the ocean. Traditional methods monitoring fixed geographical locations at fixed intervals may not be representative of the mean water turbidity in estuaries between intervals, and can be expensive and time consuming. Although remote sensing offers a good solution to this limitation, it is still not widely used due in part to required complex processing of imagery. There are satellite-derived products, including the Moderate Resolution Imaging Spectroradiometer (MODIS Terra surface reflectance daily product (MOD09GQ Band 1 (620–670 nm which are now routinely available at 250 m spatial resolution and corrected for atmospheric effect. This study shows this product to be useful to estimate turbidity in Tampa Bay, Florida, after rainfall events (R2 = 0.76, n = 34. Within Tampa Bay, Hillsborough Bay (HB and Old Tampa Bay (OTB presented higher turbidity compared to Middle Tampa Bay (MTB and Lower Tampa Bay (LTB.

  12. Riverbed Micromorphology of the Yangtze River Estuary, China

    Directory of Open Access Journals (Sweden)

    Shuaihu Wu

    2016-05-01

    Full Text Available Dunes are present in nearly all fluvial channels and are vital in understanding sediment transport, deposition, and flow conditions during floods of rivers and estuaries. This information is pertinent for helping developing management practices to reduce risks in river transportation and engineering. Although a few recent studies have investigated the micromorphology of a portion of the Yangtze River estuary in China, our understanding of dune development in this large estuary is incomplete. It is also poorly understood how the development and characteristics of these dunes have been associated with human activities in the upper reach of the Yangtze River and two large-scale engineering projects in the estuarine zone. This study analyzed the feature in micromorphology of the entire Yangtze River estuary bed over the past three years and assessed the morphological response of the dunes to recent human activities. In 2012, 2014, and 2015, multi-beam bathymetric measurements were conducted on the channel surface of the Yangtze River estuary. The images were analyzed to characterize the subaqueous dunes and detect their changes over time. Bottom sediment samples were collected for grain size analysis to assess the physical properties of the dunes. We found that dunes in the Yangtze River estuary can be classified in four major classes: very large dunes, large dunes, medium dunes, and small dunes. Large dunes were predominant, amounting to 51.5%. There was a large area of dunes developed in the middle and upper reaches of the Yangtze River estuary and in the Hengsha Passage. A small area of dunes was observed for the first time in the turbidity maximum zone of the Yangtze River estuary. These dunes varied from 0.12 to 3.12 m in height with a wide range of wavelength from 2.83 to 127.89 m, yielding a range in height to wavelength of 0.003–0.136. Sharp leeside slope angles suggest that the steep slopes of asymmetrical dunes in the middle and upper

  13. Dynamics of intertidal flats in the Loire estuary

    Science.gov (United States)

    Kervella, Stephane; Sottolichio, Aldo; Bertier, Christine

    2014-05-01

    Tidal flats form at the edges of many tidal estuaries, and are found in broad climatic regions. Their evolution plays a fundamental role in maintaining the morphodynamic equilibrium of an estuary. The Loire estuary is one of the largest macrotidal systems of the french atlantic coast. Since 200 years, its geometry has been drastically modified through channeling, deepening, embanking, infilling of secondary channels, etc. These works altered many intertidal areas. In the recent years, efforts for the rectification of the morphology have been made in order to restore the ecology of the estuary. In this context, it is crucial to better understand the dynamics of intertidal flats, still poorly understood in this estuary. The aim of this work is to analyse a series of original observations conducted for the first time in two intertidal flats of the central Lore estuary between 2008 and 2010. The tidal flats are situated in the northern bank, at 12 and 17 km upstream from the mouth respectively. Six Altus altimeters were deployed at two cross shore transects, measuring continuously and at a high-frequency bed altimetry and water level, providing information on tide and waves. At the semi-diurnal tidal scale, the surficial sediment of intertidal flats is permanently mobilized. Altimetry variations are low, and their amplitude varies as a function of tides and river flow. At the scale of several months, the sedimentation is controlled by the position of the turbidity maximum (and therefore by the river flow) and also by the tidal amplitude. During low river flow periods, altimetry variations are only due to tidal cycles. During decaying tides, suspended sediment settle mainly on the lower part of the tidal flats, forming fluid mud layers of several cm thick, which can consolidate rapidly; under rising tides, the increasing of tidal currents promotes erosion. During periods of high river flow, the turbidity maximum shifts to the lower estuary. The higher suspended sediment

  14. Suspended matter and heavy metal content of the Elbe Estuary

    International Nuclear Information System (INIS)

    Vollbrecht, K.

    1980-01-01

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

  15. Turbidity and salinity affect feeding performance and physiological stress in the endangered delta smelt.

    Science.gov (United States)

    Hasenbein, Matthias; Komoroske, Lisa M; Connon, Richard E; Geist, Juergen; Fangue, Nann A

    2013-10-01

    Coastal estuaries are among the most heavily impacted ecosystems worldwide with many keystone fauna critically endangered. The delta smelt (Hypomesus transpacificus) is an endangered pelagic fish species endemic to the Sacramento-San Joaquin Estuary in northern California, and is considered as an indicator species for ecosystem health. This ecosystem is characterized by tidal and seasonal gradients in water parameters (e.g., salinity, temperature, and turbidity), but is also subject to altered water-flow regimes due to water extraction. In this study, we evaluated the effects of turbidity and salinity on feeding performance and the stress response of delta smelt because both of these parameters are influenced by water flows through the San Francisco Bay Delta (SFBD) and are known to be of critical importance to the completion of the delta smelt's life cycle. Juvenile delta smelt were exposed to a matrix of turbidities and salinities ranging from 5 to 250 nephelometric turbidity units (NTUs) and 0.2 to 15 parts per thousand (ppt), respectively, for 2 h. Best statistical models using Akaike's Information Criterion supported that increasing turbidities resulted in reduced feeding rates, especially at 250 NTU. In contrast, best explanatory models for gene transcription of sodium-potassium-ATPase (Na/K-ATPase)-an indicator of osmoregulatory stress, hypothalamic pro-opiomelanocortin-a precursor protein to adrenocorticotropic hormone (expressed in response to biological stress), and whole-body cortisol were affected by salinity alone. Only transcription of glutathione-S-transferase, a phase II detoxification enzyme that protects cells against reactive oxygen species, was affected by both salinity and turbidity. Taken together, these data suggest that turbidity is an important determinant of feeding, whereas salinity is an important abiotic factor influencing the cellular stress response in delta smelt. Our data support habitat association studies that have shown greater

  16. Metabarcoding of benthic eukaryote communities predicts the ecological condition of estuaries

    International Nuclear Information System (INIS)

    Chariton, Anthony A.; Stephenson, Sarah; Morgan, Matthew J.; Steven, Andrew D.L.; Colloff, Matthew J.; Court, Leon N.; Hardy, Christopher M.

    2015-01-01

    DNA-derived measurements of biological composition have the potential to produce data covering all of life, and provide a tantalizing proposition for researchers and managers. We used metabarcoding to compare benthic eukaryote composition from five estuaries of varying condition. In contrast to traditional studies, we found biotic richness was greatest in the most disturbed estuary, with this being due to the large volume of extraneous material (i.e. run-off from aquaculture, agriculture and other catchment activities) being deposited in the system. In addition, we found strong correlations between composition and a number of environmental variables, including nutrients, pH and turbidity. A wide range of taxa responded to these environmental gradients, providing new insights into their sensitivities to natural and anthropogenic stressors. Metabarcoding has the capacity to bolster current monitoring techniques, enabling the decisions regarding ecological condition to be based on a more holistic view of biodiversity. - Highlights: • We used metabarcoding to examine the benthic eukaryote composition of five estuaries. • Biotic richness (based on MOTUs) was greater in the most impacted estuary. • Similarities among estuaries reflected their environmental condition. • Composition was strongly correlated with nutrients, turbidity and pH. • Metabarcoding can provide fast, comprehensive and ecologically informative data. - Using metabarcoding we were able discriminate benthos from five estuaries, and identify those taxa which responded negatively and positivity to the key environmental stressors

  17. L'argent (Ag, nanoAg) comme contaminant émergeant dans l'Estuaire de la Gironde : évaluations scientifiques et gouvernance des risques

    OpenAIRE

    Salles, Denis; Roumezi, Alexis; Lanceleur, Laurent; Schafer, Jörg; Petit, Jerome; Blanc, Gerard; Coynel, Alexandra; Chiffoleau, Jean-francois; Auger, Dominique

    2013-01-01

    Cet article présente les résultats d'une recherche pluridisciplinaire (géochimie, sociologie) portant sur l'accroissement observé des concentrations d'argent sous la forme particulaire et nanoparticulaire (Ag et nanoAg) dans les milieux aquatiques de l'estuaire de la Gironde. Il propose conjointement d'analyser les risques d'une contamination des milieux aquatiques par l'argent et d'observer le processus de construction sociale et politique de ce risque par les gestionnaires de l'eau, les aut...

  18. Evolution of mid-Atlantic coastal and back-barrier estuary environments in response to a hurricane: Implications for barrier-estuary connectivity

    Science.gov (United States)

    Miselis, Jennifer L.; Andrews, Brian D.; Nicholson, Robert S.; Defne, Zafer; Ganju, Neil K.; Navoy, Anthony S.

    2016-01-01

    Assessments of coupled barrier island-estuary storm response are rare. Hurricane Sandy made landfall during an investigation in Barnegat Bay-Little Egg Harbor estuary that included water quality monitoring, geomorphologic characterization, and numerical modeling; this provided an opportunity to characterize the storm response of the barrier island-estuary system. Barrier island morphologic response was characterized by significant changes in shoreline position, dune elevation, and beach volume; morphologic changes within the estuary were less dramatic with a net gain of only 200,000 m3 of sediment. When observed, estuarine deposition was adjacent to the back-barrier shoreline or collocated with maximum estuary depths. Estuarine sedimentologic changes correlated well with bed shear stresses derived from numerically simulated storm conditions, suggesting that change is linked to winnowing from elevated storm-related wave-current interactions rather than deposition. Rapid storm-related changes in estuarine water level, turbidity, and salinity were coincident with minima in island and estuarine widths, which may have influenced the location of two barrier island breaches. Barrier-estuary connectivity, or the transport of sediment from barrier island to estuary, was influenced by barrier island land use and width. Coupled assessments like this one provide critical information about storm-related coastal and estuarine sediment transport that may not be evident from investigations that consider only one component of the coastal system.

  19. Historical changes in the Columbia River Estuary

    Science.gov (United States)

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

    salinity intrusion length and the transport of salt into the estuary. The overall effects of human intervention in the physical processes of the Columbia River Estuary (i.e. decrease in freshwater inflow, tidal prism, and mixing; increase in flushing time and fine sediment deposition, and net accumulation of sediment) are qualitatively similar to those observed in less energetic and more obviously altered estuarine systems. A concurrent reduction in wetland habitats has resulted in an estimated 82% reduction in emergent plant production and a 15% reduction in benthic macroalgae production, a combined production loss of 51,675 metric tons of organic carbon per year. This has been at least partially compensated by a large increase in the supply of riverine detritus derived from freshwater phytoplankton primary production. Comparison of modern and estimated preregulation organic carbon budgets for the estuary indicates a shift from a food web based on comparatively refractory macrodetritus derived from emergent vegetation to one involving more labile microdetritus derived from allochthonous phytoplankton. The shift has been driven by human-induced changes to the physical environment of the estuary. While this is a relatively comprehensive study of historical physical changes, it is incomplete in that the sediment budget is still uncertain. More precise quantification of the modern estuarine sediment budget will require both a better understanding of the fluvial input and dredging export terms and a sediment tranport model designed to explain historical changes in the sediment budget. Oceanographic studies to better determine the mechanisms leading to the formation of the turbidity maximum are also needed. The combination of cartography and modelling used in this study should be applicable in other systems where large changes in morphology have occurred in historical time.

  20. Penobscot Estuary (Maine) Monitoring

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's NEFSC collects fisheries data from the Penobscot Estuary using several types of fishing gear. The data is used to determine species presence, relative...

  1. Assessments at multiple levels of biological organization allow for an integrative determination of physiological tolerances to turbidity in an endangered fish species.

    Science.gov (United States)

    Hasenbein, Matthias; Fangue, Nann A; Geist, Juergen; Komoroske, Lisa M; Truong, Jennifer; McPherson, Rina; Connon, Richard E

    2016-01-01

    Turbidity can influence trophic levels by altering species composition and can potentially affect fish feeding strategies and predator-prey interactions. The estuarine turbidity maximum, described as an area of increased suspended particles, phytoplankton and zooplankton, generally represents a zone with higher turbidity and enhanced food sources important for successful feeding and growth in many fish species. The delta smelt (Hypomesus transpacificus) is an endangered, pelagic fish species endemic to the San Francisco Estuary and Sacramento-San Joaquin River Delta, USA, where it is associated with turbid waters. Turbidity is known to play an important role for the completion of the species' life cycle; however, turbidity ranges in the Delta are broad, and specific requirements for this fish species are still unknown. To evaluate turbidity requirements for early life stages, late-larval delta smelt were maintained at environmentally relevant turbidity levels ranging from 5 to 250 nephelometric turbidity units (NTU) for 24 h, after which a combination of physiological endpoints (molecular biomarkers and cortisol), behavioural indices (feeding) and whole-organism measures (survival) were determined. All endpoints delivered consistent results and identified turbidities between 25 and 80 NTU as preferential. Delta smelt survival rates were highest between 12 and 80 NTU and feeding rates were highest between 25 and 80 NTU. Cortisol levels indicated minimal stress between 35 and 80 NTU and were elevated at low turbidities (5, 12 and 25 NTU). Expression of stress-related genes indicated significant responses for gst, hsp70 and glut2 in high turbidities (250 NTU), and principal component analysis on all measured genes revealed a clustering of 25, 35, 50 and 80 NTU separating the medium-turbidity treatments from low- and high-turbidity treatments. Taken together, these data demonstrate that turbidity levels that are either too low or too high affect delta

  2. Some physico-chemical aspects of pollution in the Karnafully river estuary

    International Nuclear Information System (INIS)

    Islam, M.N.; Zamal, H.; Anwar, M.N.; Saha, S.B.

    2003-01-01

    An investigation was carried out to determine the characteristics of low tide water of Karnafully river estuary during January to December 1997. The study reveals that low tide water of the estuary is highly turbid which inhibits penetration of incident light (K t =16.66) and limits the euphotic zone within a narrow depth of 0.19 m. The estuarine water is oligohaline and neutral in nature and remains under-saturated with dissolved oxygen throughout the year. The load of different nutrients is higher than that of the world average of river water. (author)

  3. Can analysis of Platichthys flesus otoliths provide relevant data on historical metal pollution in estuaries? Experimental and in situ approaches

    International Nuclear Information System (INIS)

    Selleslagh, Jonathan; Echard, Aurélie; Pécheyran, Christophe; Baudrimont, Magalie; Lobry, Jérémy; Daverat, Françoise

    2016-01-01

    otoliths were complex, the concentrations were correlated with those in the water. Analysis of flounder specimens collected from 2007 to 2014 in the Gironde estuary (SW France) showed interannual variability in Pb concentrations, with higher values for fish otoliths from 2007 to 2010 than those from 2012 to 2014. This trend indicated a decrease in Pb in the Gironde estuary over the last decade, which is consistent with the results of other surveys on bivalves. Our study demonstrates that it is possible to use otolith microchemistry as a tool in assessing and retracing long-term metal pollution in estuarine systems. - Highlights: • Platichthys flesus was exposed to a cocktail of metals at realistic environmental concentrations. • Bioaccumulation of metals in tissue and otolith was linked to exposure level. • Cartography of metal in fish otolith was realized for the first time. • Otolith microchemistry of P. flesus was suggested as relevant tool to assess and retrace metal pollution. • Otoliths of P. flesus specimens collected from 2007 to 2014 in the Gironde estuary were analyzed

  4. Can analysis of Platichthys flesus otoliths provide relevant data on historical metal pollution in estuaries? Experimental and in situ approaches

    Energy Technology Data Exchange (ETDEWEB)

    Selleslagh, Jonathan, E-mail: Jonathan.Selleslagh@u-bordeaux.fr [Université de Bordeaux, CNRS, UMR EPOC 5805, Station Marine d' Arcachon, place du docteur Peyneau, 33120 Arcachon (France); Echard, Aurélie [IRSTEA Centre de Bordeaux, unité EABX, 50 avenue de Verdun, 33612 Cestas (France); Pécheyran, Christophe [Université de Pau et des pays de l' Adour, CNRS, LCABIE-IPREM UMR 5254, 64053 Pau (France); Baudrimont, Magalie [Université de Bordeaux, CNRS, UMR EPOC 5805, Station Marine d' Arcachon, place du docteur Peyneau, 33120 Arcachon (France); Lobry, Jérémy; Daverat, Françoise [IRSTEA Centre de Bordeaux, unité EABX, 50 avenue de Verdun, 33612 Cestas (France)

    2016-07-01

    otoliths were complex, the concentrations were correlated with those in the water. Analysis of flounder specimens collected from 2007 to 2014 in the Gironde estuary (SW France) showed interannual variability in Pb concentrations, with higher values for fish otoliths from 2007 to 2010 than those from 2012 to 2014. This trend indicated a decrease in Pb in the Gironde estuary over the last decade, which is consistent with the results of other surveys on bivalves. Our study demonstrates that it is possible to use otolith microchemistry as a tool in assessing and retracing long-term metal pollution in estuarine systems. - Highlights: • Platichthys flesus was exposed to a cocktail of metals at realistic environmental concentrations. • Bioaccumulation of metals in tissue and otolith was linked to exposure level. • Cartography of metal in fish otolith was realized for the first time. • Otolith microchemistry of P. flesus was suggested as relevant tool to assess and retrace metal pollution. • Otoliths of P. flesus specimens collected from 2007 to 2014 in the Gironde estuary were analyzed.

  5. Water and suspended sediment dynamics in the Sungai Selangor estuary

    International Nuclear Information System (INIS)

    Abdul Kadir Ishak; Kamarudin Samuding; Nazrul Hizam Yusoff

    2000-01-01

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

  6. About Estuary Data Mapper (EDM)

    Science.gov (United States)

    Estuary Data Mapper is a tool for geospatial data discovery, visualization, and data download for any of the approximately 2,000 estuaries and associated watersheds in along the five US coastal regions.

  7. Turbidity distribution in the Atlantic Ocean

    Science.gov (United States)

    Eittreim, S.; Thorndike, E.M.; Sullivan, L.

    1976-01-01

    The regional coverage of Lamont nephelometer data in the North and South Atlantic can be used to map seawater turbidity at all depths. At the level of the clearest water, in the mid-depth regions, the turbidity distribution primarily reflects the pattern of productivity in the surface waters. This suggests that the 'background' turbidity level in the oceans is largely a function of biogenic fallout. The bottom waters of the western Atlantic generally exhibit large increases in turbidity. The most intense benthic nepheloid layers are in the southwestern Argentine basin and northern North American basin; the lowest bottom water turbidity in the western Atlantic is in the equatorial regions. Both the Argentine and North American basin bottom waters appear to derive their high turbidity largely from local resuspension of terrigenous input in these basins. In contrast to the west, the eastern Atlantic basins show very low turbidities with the exception of three regions: the Mediterranean outflow area, the Cape basin, and the West European basin. ?? 1976.

  8. Turbidity monitoring at select MDOT construction sites.

    Science.gov (United States)

    2012-06-01

    The objective of this project was to establish baseline turbidity conditions at select construction : sites by establishing a water quality monitoring program and documenting MDOT approved : BMPs on site. In 2009 the United States Environmental Prote...

  9. Natural forcings on a transformed territory overshoot thresholds of primary productivity in the Guadalquivir estuary

    Science.gov (United States)

    Ruiz, J.; Macías, D.; Navarro, G.

    2017-09-01

    A three year-long quasi continuum sampling dataset on the Guadalquivir estuary water quality was used to assess the role of light availability on its biological production. We found that inorganic nutrients within the estuary are very high (with mean values for inorganic nitrogen and phosphorous of 285 and 2.4 μM respectively) while phytoplankton biomass remains low most of the time (with a mean value of 2.6 mg/m3). A strong relationship between phytoplankton biomass and water turbidity was found indicating that, indeed, light availability is the major constraint of primary production in this system. Most of the time this limitation of primary production is not associated to enhanced turbidity connected to fresh water inputs. Instead, our data indicate that, independently of freshwater inputs, the photosynthesis is restricted by tidal forcings enhancing turbidity in an estuary that has been highly modified. Our results match with classical theories on the functioning of well-mixed, estuarine ecosystems as well as with recent modeling exercises. We also discuss the potential impacts of this particular characteristic of some estuarine systems for their management and regulatory control.

  10. 40 CFR 141.13 - Maximum contaminant levels for turbidity.

    Science.gov (United States)

    2010-07-01

    ... turbidity. 141.13 Section 141.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER... Maximum contaminant levels for turbidity. The maximum contaminant levels for turbidity are applicable to... part. The maximum contaminant levels for turbidity in drinking water, measured at a representative...

  11. Insolation and turbidity measurements at Hanford

    International Nuclear Information System (INIS)

    Laulainen, N.S.; Kleckner, E.W.; Michalsky, J.J.; Thorp, J.M.

    1979-01-01

    From observations obtained at the Rattlesnake Observatory and the Hanford Meteorological Station, the redistribution of solar radiation as a result of aerosols in the lowest 1 km of the earth's atmosphere has been examined using several types of solar radiation measuring instruments. Large turbidity excursions are observed with high values associated with stagnant air masses and low values associated with frontal passage. Turbidities show variations in color dependence that arise because of changes in particle size distribution

  12. Riders on the storm: selective tidal movements facilitate the spawning migration of threatened delta smelt in the San Francisco Estuary

    Science.gov (United States)

    Bennett, W.A.; Burau, Jon R.

    2015-01-01

    Migration strategies in estuarine fishes typically include behavioral adaptations for reducing energetic costs and mortality during travel to optimize reproductive success. The influence of tidal currents and water turbidity on individual movement behavior were investigated during the spawning migration of the threatened delta smelt, Hypomesus transpacificus, in the northern San Francisco Estuary, California, USA. Water current velocities and turbidity levels were measured concurrently with delta smelt occurrence at sites in the lower Sacramento River and San Joaquin River as turbidity increased due to first-flush winter rainstorms in January and December 2010. The presence/absence of fish at the shoal-channel interface and near the shoreline was quantified hourly over complete tidal cycles. Delta smelt were caught consistently at the shoal-channel interface during flood tides and near the shoreline during ebb tides in the turbid Sacramento River, but were rare in the clearer San Joaquin River. The apparent selective tidal movements by delta smelt would facilitate either maintaining position or moving upriver on flood tides, and minimizing advection down-estuary on ebb tides. These movements also may reflect responses to lateral gradients in water turbidity created by temporal lags in tidal velocities between the near-shore and mid-channel habitats. This migration strategy can minimize the energy spent swimming against strong river and tidal currents, as well as predation risks by remaining in turbid water. Selection pressure on individuals to remain in turbid water may underlie population-level observations suggesting that turbidity is a key habitat feature and cue initiating the delta smelt spawning migration.

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

    Science.gov (United States)

    Ganju, Neil K.; Miselis, Jennifer L.; Aretxabaleta, Alfredo L.

    2014-01-01

    Light attenuation is a critical parameter governing the ecological function of shallow estuaries. In these systems primary production is often dominated by benthic macroalgae and seagrass; thus light penetration to the bed is of primary importance. We quantified light attenuation in three seagrass meadows in Barnegat Bay, New Jersey, a shallow eutrophic back-barrier estuary; two of the sites were located within designated Ecologically Sensitive Areas (ESAs). We sequentially deployed instrumentation measuring photosynthetically active radiation, chlorophyll-a (chl-a) fluorescence, dissolved organic matter fluorescence (fDOM; a proxy for colored DOM absorbance), turbidity, pressure, and water velocity at 10 min intervals over three week periods at each site. At the southernmost site, where sediment availability was highest, light attenuation was highest and dominated by turbidity and to a lesser extent chl-a and CDOM. At the central site, chl-a dominated followed by turbidity and CDOM, and at the northernmost site turbidity and CDOM contributed equally to light attenuation. At a given site, the temporal variability of light attenuation exceeded the difference in median light attenuation at the three sites, indicating the need for continuous high-temporal resolution measurements. Vessel wakes, anecdotally implicated in increasing sediment resuspension, did not contribute to local resuspension within the seagrass beds, though frequent vessel wakes were observed in the channels. With regards to light attenuation and water clarity, physical and biogeochemical variables appear to outweigh any regulation of boat traffic within the ESAs.

  14. Estimation of atmospheric turbidity over Ghardaïa city

    OpenAIRE

    Djafer, Djelloul; Irbah, Abdanour

    2013-01-01

    International audience; The atmospheric turbidity expresses the attenuation of the solar radiation that reaches the Earth's surface under cloudless sky and describes the optical thickness of the atmosphere. We investigate the atmospheric turbidity over Gharda¨ıa city using two turbidity parameters, the Linke turbidity factor and the Angstr ¨om turbidity coefficient. Their values and temporal variation are obtained from data recorded between 2004 and 2008 at Gharda¨ıa. The results show that bo...

  15. Use of a Real-Time Remote Monitoring Network (RTRM to Characterize the Guadalquivir Estuary (Spain

    Directory of Open Access Journals (Sweden)

    Isabel Caballero

    2012-02-01

    Full Text Available The temporal variability of hydrological variables in the Guadalquivir estuary was examined during three years through a real-time remote monitoring network (RTRM. The network was developed with the aim of studying the influence of hydrodynamical and hydrological features within the estuary on the functioning of the pelagic ecosystem. Completing this data-gathering network, monthly cruises were performed in order to measure biogeochemical variables that are indicative of the trophic status of the aquatic environment. The results showed that several sources of physical forcing, such as wind, tide-associated currents and river discharge were responsible for the spatio-temporal patterns of dissolved oxygen, salinity and turbidity in the estuary. The analysis was conducted under tidal and flood regime, which allowed us to identify river discharge as the main forcing agent of the hydrology inside the estuary. In particular, episodes of elevated turbidity detected by the network, together with episodes of low salinity and dissolved oxygen were closely related to the increase in water supply from a dam located upstream. The network installed provided accurate data that can be rapidly used for research or educational applications and by policy-makers or agencies in charge of the management of the coastal area.

  16. The Mandovi and Zuari estuaries

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.; DileepKumar, M.; Shankar, D.

    of their extensive use for fisheries, agriculture, transportation, dumping of waste, etc. The two estuaries have since continued to attract scientific curiosity over the years, thanks in large measure to support from national and local funding agencies. As a... made so far to simulate them in numerical models, and characteristics of stratification and mixing. These are followed by chapters that examine the fun- damentals of biology and chemistry of the estuaries. A distinct characteristic of the estuaries...

  17. Ecology of estuaries

    International Nuclear Information System (INIS)

    Kennish, M.J.

    1992-01-01

    Ecology of Estuaries: Anthropogenic Effects represents the most definitive and comprehensive source of reference information available on the human impact on estuarine ecosystems. The book discusses both acute and insidious pollution problems plaguing these coastal ecotones. It also provides a detailed examination of the deleterious and pervasive effects of human activities on biotic communities and sensitive habitat areas in estuaries. Specific areas covered include organic loading, oil pollution, polynuclear aromatic hydrocarbons, chlorinated hydrocarbons, heavy metals, dredging and dredge-spoil disposal, radionuclides, as well as other contaminants and processes. The diverse components of these anthropogenic influences are assembled in an organized framework and presented in a clear and concise style that will facilitate their understanding

  18. Effect of Canister Movement on Water Turbidity

    International Nuclear Information System (INIS)

    TRIMBLE, D.J.

    2000-01-01

    Requirements for evaluating the adherence characteristics of sludge on the fuel stored in the K East Basin and the effect of canister movement on basin water turbidity are documented in Briggs (1996). The results of the sludge adherence testing have been documented (Bergmann 1996). This report documents the results of the canister movement tests. The purpose of the canister movement tests was to characterize water turbidity under controlled canister movements (Briggs 1996). The tests were designed to evaluate methods for minimizing the plumes and controlling water turbidity during fuel movements leading to multi-canister overpack (MCO) loading. It was expected that the test data would provide qualitative visual information for use in the design of the fuel retrieval and water treatment systems. Video recordings of the tests were to be the only information collected

  19. Atmospheric turbidity parameters in the high polluted site of egypt

    International Nuclear Information System (INIS)

    Shaltout, M.A.M.; Rahoma, U.A.

    1996-01-01

    Monthly variations of Linke, angstrom and Schuepp turbidity coefficients and gamma exponent as well as the influence of climatic factor on them are analysed. For each of these turbidity coefficients; calculated from measurements of broad band filters at Helwan, egypt, desert climate, are reported. A linear regression model fitted to Angstrom's turbidity turbidity coefficient beta and Linke turbidity L for Helwan. The calculation showed that, it is higher values of atmospheric turbidity coefficients due to, both the effect of air pollutants in the Helwan atmosphere from the four cement companies and some of heavy industrial factories, and the effect of the former's desert climate. 6 figs., 2 tabs

  20. The relative importance of oceanic nutrient inputs for Bass Harbor Marsh Estuary at Acadia National Park, Maine

    Science.gov (United States)

    Huntington, Thomas G.; Culbertson, Charles W.; Fuller, Christopher; Glibert, Patricia; Sturtevant, Luke

    2014-01-01

    The U.S. Geological Survey and Acadia National Park (ANP) collaborated on a study of nutrient inputs into Bass Harbor Marsh Estuary on Mount Desert Island, Maine, to better understand ongoing eutrophication, oceanic nutrient inputs, and potential management solutions. This report includes the estimation of loads of nitrate, ammonia, total dissolved nitrogen, and total dissolved phosphorus to the estuary derived from runoff within the watershed and oceanic inputs during summers 2011 and 2012. Nutrient outputs from the estuary were also monitored, and nutrient inputs in direct precipitation to the estuary were calculated. Specific conductance, water temperature, and turbidity were monitored at the estuary outlet. This report presents a first-order analysis of the potential effects of projected sea-level rise on the inundated area and estuary volume. Historical aerial photographs were used to investigate the possibility of widening of the estuary channel over time. The scope of this report also includes analysis of sediment cores collected from the estuary and fringing marsh surfaces to assess the sediment mass accumulation rate. Median concentrations of nitrate, ammonium, and total dissolved phosphorus on the flood tide were approximately 25 percent higher than on the ebb tide during the 2011 and 2012 summer seasons. Higher concentrations on the flood tide suggest net assimilation of these nutrients in biota within the estuary. The dissolved organic nitrogen fraction dominated the dissolved nitrogen fraction in all tributaries. The median concentration of dissolved organic nitrogen was about twice as high on the on the ebb tide than the flood tide, indicating net export of dissolved organic nitrogen from the estuary. The weekly total oceanic inputs of nitrate, ammonium, and total dissolved phosphorus to the estuary were usually much larger than inputs from runoff or direct precipitation. The estuary was a net sink for nitrate and ammonium in most weeks during both

  1. Comparison of metallothionein concentrations and tissue distribution of trace metals in crabs (Pachygrapsus marmoratus) from a metal-rich estuary, in and out of the reproductive season.

    Science.gov (United States)

    Mouneyrac, C; Amiard-Triquet, C; Amiard, J C; Rainbow, P S

    2001-07-01

    Crabs, Pachygrapsus marmoratus, were sampled in June 1997 and February 1998 from two sites (at the mouth and 25 km upstream) in the metal-rich Gironde estuary, France. Gills and hepatopancreas were analysed for metal (Cd, Cu, Zn) and metallothionein (MT) contents, in order to examine the influence of both biological and environmental factors on the physico-chemical forms of detoxified metal storage in the crabs. The concentrations of MT and both cytosolic and insoluble metals were not greatly different between males and females, and the influence of organ weights was also minimal. Intersite differences were observed, probably resulting from the gradient of salinity in the estuary, which interacts with both the chemical speciation and bioavailability of metals, and the general protein metabolism of the crabs. Seasonal changes were also important, probably in interaction with the moult and reproductive cycles. In February, concentrations of insoluble metals were generally higher than in June, in both organs, suggesting that essential metals, particularly Zn, are stored during winter then remobilised during the breeding season. The natural variability in the concentrations of MT often concealed any relationship with accumulated metal concentrations. Thus MT in crabs cannot be considered as a useful biomarker of metal pollution.

  2. Monitoring of well-controlled turbidity currents using the latest technology and a dredger

    Science.gov (United States)

    Vellinga, A. J.; Cartigny, M.; Clare, M. A.; Mastbergen, D. R.; Van den Ham, G.; Koelewijn, A. R.; de Kleine, M.; Hizzett, J. L.; Azpiroz, M.; Simmons, S.; Parsons, D. R.

    2017-12-01

    Recent advances in technology enable monitoring of turbidity currents at field scale. This now allows us to test models developed at small-scale in the laboratory. However, interpretation of field measurements is complicated, as the instruments used are not bespoke for monitoring turbidity currents. For example, Acoustic Doppler Current Profiles (ADCPs) are developed to measure clear water flows, and 3D multimode multibeam echosounders (M3s) are made to find shoals of fish. Calibration of field-scale measurements is complicated, as we often do not know fundamental information about the measured flows, such as grain size and initial sediment volume. We present field-scale measurements of two turbidity currents for which the pre- and post-flow bathymetry, grain size and initial sediment volume is known precisely. A dredger created two turbidity currents by twice discharging 500m3 of sediment on a slope in the Western Scheldt Estuary, the Netherlands. Flow velocity and echo intensity were directly measured using three frequencies of ADCPs, and two M3 sonars imaged the flow morphology in 3D. This experiment was part of the IJkdijk research program. The turbidity currents formed upstream-migrating crescentic shaped bedforms. The ADCPs measured peak flow velocities of 1-1.5 m/s. The M3s however suggest head velocities are 2-4 m/s. The two measured turbidity currents have thicknesses of about 3m, are up to 50m in width and travel downslope for about 150m. Flow dimensions, duration, and sediment discharge indicate a mean sediment concentration of 1-5 vol. %. Flow morphology evolves from a fast but thin, snout-like head, to a thicker body, and a dilute tail. The initial flow dynamics contrast with many laboratory experiments, but are coherent with direct measurements of much larger flows in the Congo Canyon. Well-constrained field studies, like this one, thus help to understand the validity of scaling from the laboratory to the deep sea.

  3. PPCPs in Jiulong River estuary (China): Spatiotemporal distributions, fate, and their use as chemical markers of wastewater.

    Science.gov (United States)

    Sun, Qian; Li, Yan; Li, Mingyue; Ashfaq, Muhammad; Lv, Min; Wang, Hongjie; Hu, Anyi; Yu, Chang-Ping

    2016-05-01

    The occurrence and fate of 50 pharmaceuticals and personal care products (PPCPs) were investigated in the surface water of Jiulong River estuary in the southeast of China in spring, wet season, summer, autumn and winter. Results demonstrated a wide distribution of PPCPs in Jiulong River estuary, where 34 PPCPs were detected at least once and 5 PPCPs were detected in all the samples, including caffeine, diclofenac, metoprolol, methyl paraben, and propyl paraben. Spatial and seasonal variations were observed. Special emphasis was placed on the PPCP fate in the estuary. Most PPCPs showed a non-conservative behavior in the estuary, while the non-steroidal anti-inflammatory drugs and bisphenol A showed a pseudo-conservative behavior. The non-conservative and pseudo-conservative behavior was attributed to the combination of the seawater dilution, the introduction of PPCPs via the sewage water, and the physical, chemical, or biological removal processes. Furthermore, PPCP concentrations showed drastic variations in the turbidity maximum zones. To our best knowledge, this is the first work to indicate the pseudo-conservative behavior of PPCPs in the estuary, and to show the drastic variations of PPCPs in the turbidity maximum zone. In addition, the ratio of labile to conservative PPCPs was calculated to track the source of untreated sewage contamination. Results showed a significantly higher ratio compared to the average value in WWTP effluents, indicating the ubiquitous discharge of untreated domestic wastewater in Jiulong River estuary. In addition, the high ratio of bisphenol A to conservative PPCPs implied the potential input of untreated industrial wastewater in Jiulong River estuary. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Using turbidity for designing water networks.

    Science.gov (United States)

    Castaño, J A; Higuita, J C

    2016-05-01

    Some methods to design water networks with minimum fresh water consumption are based on the selection of a key contaminant. In most of these "single contaminant methods", a maximum allowable concentration of contaminants must be established in water demands and water sources. Turbidity is not a contaminant concentration but is a property that represents the "sum" of other contaminants, with the advantage that it can be cheaper and easily measured than biological oxygen demand, chemical oxygen demand, suspended solids, dissolved solids, among others. The objective of this paper is to demonstrate that turbidity can be used directly in the design of water networks just like any other contaminant concentration. A mathematical demonstration is presented and in order to validate the mathematical results, the design of a water network for a guava fudge production process is performed. The material recovery pinch diagram and nearest neighbors algorithm were used for the design of the water network. Nevertheless, this water network could be designed using other single contaminant methodologies. The maximum error between the expected and the real turbidity values in the water network was 3.3%. These results corroborate the usefulness of turbidity in the design of water networks. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Implementation guide for turbidity threshold sampling: principles, procedures, and analysis

    Science.gov (United States)

    Jack Lewis; Rand Eads

    2009-01-01

    Turbidity Threshold Sampling uses real-time turbidity and river stage information to automatically collect water quality samples for estimating suspended sediment loads. The system uses a programmable data logger in conjunction with a stage measurement device, a turbidity sensor, and a pumping sampler. Specialized software enables the user to control the sampling...

  6. 40 CFR 141.22 - Turbidity sampling and analytical requirements.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Turbidity sampling and analytical... § 141.22 Turbidity sampling and analytical requirements. The requirements in this section apply to... the water distribution system at least once per day, for the purposes of making turbidity measurements...

  7. Alkaline Phosphatase Activity : an overlooked player on the phosphate behavior in macrotidal estuaries

    Science.gov (United States)

    Delmas, Daniel; Labry, Claire; Youenou, Agnes; Quere, Julien; Auguet, Jean Christophe; Montanie, Helene

    2014-05-01

    The non-conservative behavior of phosphate within the estuarine salinity gradient is essentially assigned to physico-chemical processes, such as desorption at low salinity and to benthic exchanges. Microbial phosphatase activity (APA), generally related to phosphate deficiency, is seldom studied in phosphate rich estuarine waters. In order to address the impact of microbial activity (bacterial abundance, production BSP, APA) on phosphate behavior, we studied these activities on a seasonal basis within the salinity gradient of two macrotidal estuaries presenting different levels of suspended solids. Whatever the season the Charente estuary is characterized by high levels of Suspended Particulate Matter (SPM > 1g.L-1), particularly in the Maximum Turbidity Zone (MTZ) located at the 5-10 psu. In this area characterized by high BSP and APA there is a significant increase of PO4 levels especially during summer. In the Aulne estuary the particle load is significantly lower (1/10) but high BSP and APA are equally recorded. In the highly turbid waters of the Charente estuary, active phytoplankton is virtually absent as pheopigments constitute up to 80% of the total pigments, particularly in the MTZ, therefore APA may essentially have a bacterial origin. In the Aulne estuary attached bacteria are dominant, both in numbers and production, and their distribution along the haline gradient perfectly follows those of APA and phosphate levels. These observations, associated with the very close relationships observed between APA, SPM and BSP, suggest that APA derive mainly from bacterial (attached) origin and operate at the expense of particulate phosphorus and hence contribute to PO4 regeneration, especially in spring and summer. Finally, as APA increased as PO4, whereas the reverse is observed in both fresh and marine waters, an original scheme for APA regulation, related to the large dominance of attached bacteria can be described for the estuarine waters.

  8. Changes in a temperate estuary during the filling of the biggest European dam.

    Science.gov (United States)

    Morais, Pedro; Chícharo, Maria Alexandra; Chícharo, Luís

    2009-03-15

    This study aimed to determine whether and how the disruption of river flow, during the filling of the Alqueva dam, influenced the variability of abiotic and biotic factors in the Guadiana estuary, particularly the abundance and distribution of anchovy eggs. River inflow was found to be the most important factor in determining abiotic and biotic variability in the Guadiana estuary. Seasonal patterns were obscured by long periods of low inflow (mid April to early December 2002), which caused marked changes in the estuary. The estuarine turbidity maximum zone was displaced towards the upper estuary, to at least 38 km from the river mouth, 8 to 16 km upstream from previous records. The dynamics of nutrient stoichiometry was also affected. In the upper and middle estuary, P was more potential limiting than N and potential Si limitation was only frequent on the coast, with direct and/or indirect influence in changing phytoplankton dynamics and composition. Previously, the upper estuary alternated between potential P limitation during winter, Si limitation during spring and mid summer and N limitation during mid summer and autumn. The flooding of vast areas in the catchment of the dam probably caused the increase of DSi concentrations, as well as maximal N and P loadings. The abundance of larval stages of anchovy decreased, putatively because estuarine productivity has also decreased. In April 2002 there was an uncontrolled discharge from the Alqueva dam, which reduced the abundance of anchovy eggs by 99.99%. It is suggested that dam managers should mimic, as much as possible, the natural river flow, in order to minimize the impact on downstream ecosystems. Management efforts should not be restricted to the areas upstream of the dam, but should also encompass the estuary and adjacent coastal area.

  9. Turbidity and microbes removal from water using an electrochemical filter

    International Nuclear Information System (INIS)

    Venkateswaran, G.; Gokhale, B.K.; Belapurkar, A.D.; Kumbhar, A.G.; Balaji, V.

    2004-01-01

    An in-house designed and fabricated Electrochemical fibrous graphite filter (ECF) was used to remove turbidity and microbes. The filter was found to be effective in removing sub micron size indium turbidity from RAPS-1 moderator water, iron turbidity from Active Process Cooling Water (APCW) of Kaiga Generating Station and microbial reduction from process cooling water RAPS-2. Unlike conventional turbidity removal by addition of coagulants and biocide chemical additions for purification, ECF is a clean way to remove the turbidity without contaminating the system and is best suited for close loop systems

  10. Physicochemical and biological factors controlling water column metabolism in Sundarbans estuary, India

    Science.gov (United States)

    2012-01-01

    Background Sundarbans is the single largest deltaic mangrove forest in the world, formed at estuarine phase of the Ganges - Brahmaputra river system. Primary productivity of marine and coastal phytoplankton contributes to 15% of global oceanic production. But unfortunately estuarine dynamics of tropical and subtropical estuaries have not yet received proper attention in spite of the fact that they experience considerable anthropogenic interventions and a baseline data is required for any future comparison. This study is an endeavor to this end to estimate the primary productivity (gross and net), community respiration and nitrification rates in different rivers and tidal creeks around Jharkhali island, a part of Sundarbans estuary surrounded by the mangrove forest during a period of three years starting from November’08 to October’11. Results Various physical and chemical parameters of water column like pH, temperature, conductivity, dissolved oxygen, turbidity, suspended particulate matter, secchi disc index, tidal fluctuation and tidal current velocity, standing crop and nutrients were measured along with water column productivity. Relationship of net water column productivity with algal biomass (standing crop), nutrient loading and turbidity were determined experimentally. Correlations of bacterial abundance with community respiration and nitrification rates were also explored. Annual integrated phytoplankton production rate of this tidal estuary was estimated to be 151.07 gC m-2 y-1. Gross primary productivity showed marked inter annual variation being lowest in monsoon and highest in postmonsoon period. Conclusion Average primary production was a function of nutrient loading and light penetration in the water column. High aquatic turbidity, conductivity and suspended particulate matter were the limiting factors to attenuate light penetration with negative influence on primary production. Community respiration and nitrification rates of the estuary were

  11. Physicochemical and biological factors controlling water column metabolism in Sundarbans estuary, India.

    Science.gov (United States)

    Chaudhuri, Kaberi; Manna, Suman; Sarma, Kakoli Sen; Naskar, Pankaj; Bhattacharyya, Somenath; Bhattacharyya, Maitree

    2012-10-19

    Sundarbans is the single largest deltaic mangrove forest in the world, formed at estuarine phase of the Ganges - Brahmaputra river system. Primary productivity of marine and coastal phytoplankton contributes to 15% of global oceanic production. But unfortunately estuarine dynamics of tropical and subtropical estuaries have not yet received proper attention in spite of the fact that they experience considerable anthropogenic interventions and a baseline data is required for any future comparison. This study is an endeavor to this end to estimate the primary productivity (gross and net), community respiration and nitrification rates in different rivers and tidal creeks around Jharkhali island, a part of Sundarbans estuary surrounded by the mangrove forest during a period of three years starting from November'08 to October'11. Various physical and chemical parameters of water column like pH, temperature, conductivity, dissolved oxygen, turbidity, suspended particulate matter, secchi disc index, tidal fluctuation and tidal current velocity, standing crop and nutrients were measured along with water column productivity. Relationship of net water column productivity with algal biomass (standing crop), nutrient loading and turbidity were determined experimentally. Correlations of bacterial abundance with community respiration and nitrification rates were also explored. Annual integrated phytoplankton production rate of this tidal estuary was estimated to be 151.07 gC m-2 y-1. Gross primary productivity showed marked inter annual variation being lowest in monsoon and highest in postmonsoon period. Average primary production was a function of nutrient loading and light penetration in the water column. High aquatic turbidity, conductivity and suspended particulate matter were the limiting factors to attenuate light penetration with negative influence on primary production. Community respiration and nitrification rates of the estuary were influenced by the bacterial abundance

  12. Variations in some environmental characteristics including C and N stable isotopic composition of suspended organic matter in the Mandovi estuary.

    Science.gov (United States)

    Maya, M V; Soares, Melena A; Agnihotri, Rajesh; Pratihary, A K; Karapurkar, Supriya; Naik, Hema; Naqvi, S W A

    2011-04-01

    Chemical and isotopic (δ13C and δ15N) investigation of the Mandovi estuary along the Indian west coast affected strongly by the seasonal monsoon cycle was carried out. The Mandovi estuary is a major waterway for Goa and extensively used for transportation of iron and manganese ore. In addition, with large population centers as well as agricultural fields located on its shores, the estuary is assumed to have been influenced by human activities. Measurements of chemical and isotopic parameters made in the lower part of the estuary during the southwest (SW) monsoon and post-monsoon seasons reveal distinct changes, and it is observed that despite considerable enrichment of macronutrients during the SW monsoon, productivity of the estuary (phytoplankton biomass), as inferred from the chlorophyll-a content, is not as high as expected. This is due to occurrences of high turbidity and cloud cover that limits photosynthetic productivity. The isotopic characterization (C and N isotopes) of suspended organic matter produced/transported during the monsoon and post-monsoon seasons of year 2007 provides a baseline dataset for future isotopic studies in such type of tropical estuaries.

  13. Bifocal optical coherenc refractometry of turbid media.

    Science.gov (United States)

    Alexandrov, Sergey A; Zvyagin, Andrei V; Silva, K K M B Dilusha; Sampson, David D

    2003-01-15

    We propose and demonstrate a novel technique, which we term bifocal optical coherence refractometry, for the rapid determination of the refractive index of a turbid medium. The technique is based on the simultaneous creation of two closely spaced confocal gates in a sample. The optical path-length difference between the gates is measured by means of low-coherence interferometry and used to determine the refractive index. We present experimental results for the refractive indices of milk solutions and of human skin in vivo. As the axial scan rate determines the acquisition time, which is potentially of the order of tens of milliseconds, the technique has potential for in vivo refractive-index measurements of turbid biological media under dynamic conditions.

  14. Nitrogen cycling in a turbid, tidal estuary - de stikstofkringloop in een troebel getijden estuarium

    NARCIS (Netherlands)

    Andersson, M.G.I.

    2007-01-01

    In this thesis I investigated nitrification, dissolved inorganic and organic nitrogen uptake, and the relative importance of nitrification and ammonium assimilation. I have also investigated exchange with marshes and sediments. Nitrification, oxidation of ammonium to nitrate is the first step for

  15. Estuarine turbidity, flushing, salinity, and circulation

    Science.gov (United States)

    Pritchard, D. W.

    1972-01-01

    The effects of estuarine turbidity, flushing, salinity, and circulation on the ecology of the Chesapeake Bay are discussed. The sources of fresh water, the variations in salinity, and the circulation patterns created by temperature and salinity changes are analyzed. The application of remote sensors for long term observation of water temperatures is described. The sources of sediment and the biological effects resulting from increased sediments and siltation are identified.

  16. Methylmercury bioaccumulation in an urban estuary: Delaware River USA.

    Science.gov (United States)

    Buckman, Kate; Taylor, Vivien; Broadley, Hannah; Hocking, Daniel; Balcom, Prentiss; Mason, Rob; Nislow, Keith; Chen, Celia

    2017-09-01

    Spatial variation in mercury (Hg) and methylmercury (MeHg) bioaccumulation in urban coastal watersheds reflects complex interactions between Hg sources, land use, and environmental gradients. We examined MeHg concentrations in fauna from the Delaware River estuary, and related these measurements to environmental parameters and human impacts on the waterway. The sampling sites followed a north to south gradient of increasing salinity, decreasing urban influence, and increasing marsh cover. Although mean total Hg in surface sediments (top 4cm) peaked in the urban estuarine turbidity maximum and generally decreased downstream, surface sediment MeHg concentrations showed no spatial patterns consistent with the examined environmental gradients, indicating urban influence on Hg loading to the sediment but not subsequent methylation. Surface water particulate MeHg concentration showed a positive correlation with marsh cover whereas dissolved MeHg concentrations were slightly elevated in the estuarine turbidity maximum region. Spatial patterns of MeHg bioaccumulation in resident fauna varied across taxa. Small fish showed increased MeHg concentrations in the more urban/industrial sites upstream, with concentrations generally decreasing farther downstream. Invertebrates either showed no clear spatial patterns in MeHg concentrations (blue crabs, fiddler crabs) or increasing concentrations further downstream (grass shrimp). Best-supported linear mixed models relating tissue concentration to environmental variables reflected these complex patterns, with species specific model results dominated by random site effects with a combination of particulate MeHg and landscape variables influencing bioaccumulation in some species. The data strengthen accumulating evidence that bioaccumulation in estuaries can be decoupled from sediment MeHg concentration, and that drivers of MeHg production and fate may vary within a small region.

  17. Innovative GOCI algorithm to derive turbidity in highly turbid waters: a case study in the Zhejiang coastal area.

    Science.gov (United States)

    Qiu, Zhongfeng; Zheng, Lufei; Zhou, Yan; Sun, Deyong; Wang, Shengqiang; Wu, Wei

    2015-09-21

    An innovative algorithm is developed and validated to estimate the turbidity in Zhejiang coastal area (highly turbid waters) using data from the Geostationary Ocean Color Imager (GOCI). First, satellite-ground synchronous data (n = 850) was collected from 2014 to 2015 using 11 buoys equipped with a Yellow Spring Instrument (YSI) multi-parameter sonde capable of taking hourly turbidity measurements. The GOCI data-derived Rayleigh-corrected reflectance (R(rc)) was used in place of the widely used remote sensing reflectance (R(rs)) to model turbidity. Various band characteristics, including single band, band ratio, band subtraction, and selected band combinations, were analyzed to identify correlations with turbidity. The results indicated that band 6 had the closest relationship to turbidity; however, the combined bands 3 and 6 model simulated turbidity most accurately (R(2) = 0.821, pcoastal waters is feasible. As an example, the developed model was applied to 8 hourly GOCI images on 30 December 2014. Three cross sections were selected to identify the spatiotemporal variation of turbidity in the study area. Turbidity generally decreased from near-shore to offshore and from morning to afternoon. Overall, the findings of this study provide a simple and practical method, based on GOCI data, to estimate turbidity in highly turbid coastal waters at high temporal resolutions.

  18. Multi-platform assessment of turbidity plumes during dredging operations in a major estuarine system

    Science.gov (United States)

    Caballero, Isabel; Navarro, Gabriel; Ruiz, Javier

    2018-06-01

    Dredging activities in estuaries frequently cause deleterious environmental effects on the water quality which can impact flora, fauna, and hydrodynamics, among others. A medium- and high-resolution satellite-based procedure is used in this study to monitor turbidity plumes generated during the dredging operations in the Guadalquivir estuary, a major estuarine system providing important ecosystem services in southwest Europe. A multi-sensor scheme is evaluated using a combination of five public and commercial medium- and high-resolution satellites, including Landsat-8, Sentinel-2A, WorldView-2, WorldView-3, and GeoEye-1, with pixel sizes ranging from 30 m to 0.3 m. Applying a multi-conditional algorithm after the atmospheric correction of the optical imagery with ACOLITE, Sen2Cor and QUAC processors, it is demonstrated the feasibility to monitoring suspended solids during dredging operations at a spatial resolution unachievable with traditional satellite-based ocean color sensors (>300 m). The frame work can be used to map on-going, post and pre-dredging activities and asses Total Suspended Solids (TSS) anomalies caused by natural and anthropogenic processes in coastal and inland waters. These promising results are suitable to effectively improve the assessment of features relevant to environmental policies for the challenging coastal management and might serve as a notable contribution to the Earth Observation Program.

  19. Long time-series of turbid coastal water using AVHRR: an example from Florida Bay, USA

    Science.gov (United States)

    Stumpf, Richard P.; Frayer, M. L.

    1997-02-01

    The AVHRR can provide information on the reflectance of turbid case II water, permitting examination of large estuaries and plumes from major rivers. The AVHRR has been onboard several NOAA satellites, with afternoon overpasses since 1981, offering a long time-series to examine changes in coastal water. We are using AVHRR data starting in December 1989, to examine water clarity in Florida Bay, which has undergone a decline since the late 1980's. The processing involves obtaining a nominal reflectance for red light with standard corrections including those for Rayleigh and aerosol path radiances. Established relationships between reflectance and the water properties being measured in the Bay provide estimates of diffuse attenuation and light limitation for phytoplankton and seagrass productivity studies. Processing also includes monthly averages of reflectance and attenuation. The AVHRR data set describes spatial and temporal patterns, including resuspension of bottom sediments in the winter, and changes in water clarity. The AVHRR also indicates that Florida Bay has much higher reflectivity relative to attenuation than other southeastern US estuaries.

  20. FLORA OF MOLOCHNYI ESTUARY COASTS

    Directory of Open Access Journals (Sweden)

    Kolomiychuk V.P.

    2013-09-01

    Full Text Available Present-day characteristic of the coastal flora of Molochnyi eastury is given, that is one of the largest estuaries in Ukraine, the shores and waters of which in 2009 became a part of the Pryazov’ya National Nature Park. The analysis of the main parameters of the flora is made. Rare component of the estuary coastal flora is characterized, further steps to conserve the nature of Pryazov’ya are proposed.

  1. Protein aggregate turbidity: Simulation of turbidity profiles for mixed-aggregation reactions.

    Science.gov (United States)

    Hall, Damien; Zhao, Ran; Dehlsen, Ian; Bloomfield, Nathaniel; Williams, Steven R; Arisaka, Fumio; Goto, Yuji; Carver, John A

    2016-04-01

    Due to their colloidal nature, all protein aggregates scatter light in the visible wavelength region when formed in aqueous solution. This phenomenon makes solution turbidity, a quantity proportional to the relative loss in forward intensity of scattered light, a convenient method for monitoring protein aggregation in biochemical assays. Although turbidity is often taken to be a linear descriptor of the progress of aggregation reactions, this assumption is usually made without performing the necessary checks to provide it with a firm underlying basis. In this article, we outline utilitarian methods for simulating the turbidity generated by homogeneous and mixed-protein aggregation reactions containing fibrous, amorphous, and crystalline structures. The approach is based on a combination of Rayleigh-Gans-Debye theory and approximate forms of the Mie scattering equations. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  2. Investigation of turbidity effect on exergetic performance of solar ponds

    International Nuclear Information System (INIS)

    Atiz, Ayhan; Bozkurt, Ismail; Karakilcik, Mehmet; Dincer, Ibrahim

    2014-01-01

    Highlights: • A comprehensive experimental work on a turbidity of the solar pond. • Percentage transmission evaluation of the turbid and clean salty water of the zones. • Exergy analysis of the inner zones for turbid and clean salty water. • Turbidity effect on exergy efficiencies of the solar pond. • The thermal performance assessment by comparing the exergetic efficiencies of the solar pond. - Abstract: The present paper undertakes a study on the exergetic performance assessment of a solar pond and experimental investigation of turbidity effect on the system performance. There are various types of solar energy applications including solar ponds. One of significant parameters to consider in the assessment of solar pond performance is turbidity which is caused by dirty over time (e.g., insects, leaf, dust and wind bringing parts fall down). Thus, the turbidity in the salty water decreases solar energy transmission through the zones. In this study, the samples are taken from the three zones of the solar pond and analyzed using a spectrometer for three months. The transmission aspects of the solar pond are investigated under calm and turbidity currents to help distinguish the efficiencies. Furthermore, the maximum exergy efficiencies are found to be 28.40% for the calm case and 22.27% with turbidity effects for the month of August, respectively. As a result, it is confirmed that the solar pond performance is greatly affected by the turbidity effect

  3. Decadal-scale Evolution of Sediment Flux in the Aulne Estuary

    Science.gov (United States)

    Moskalski, S. M.; Deschamps, A.; Floc'h, F.; Verney, R.; Piete, H.; Fromant, G.; Delacourt, C.

    2013-12-01

    Estuarine sediment transport processes have the potential to evolve over time in response to alterations in various factors both internal and external to the estuary, such as sediment supply, river discharge, tidal forcing, or changes to bathymetry. Changes in sediment transport can affect many estuarine processes (e.g. budgets of sediment-adsorbed contaminants or nutrients) and ecosystem services, such as aquaculture, primary production and the need to dredge shipping channels. Most studies of decadal-scale changes in estuaries focus on geomorphology or bathymetry, or are performed using models calibrated by a limited set of observational studies. Because of the potential for sediment flux to both affect and be affected by geomorphology and bathymetry, observational studies oriented to sediment flux evolution are needed. This study focuses on two intensive observational studies separated by 30 years to quantify change in suspended sediment concentration (SSC) in the Aulne river, a shallow macrotidal estuary in western Brittany. Moored and vessel-mounted acoustic Doppler current profilers and YSIs were deployed over a three-week period in the winter of 2013 to examine hydrodynamic and sediment transport processes. The results of the modern study were compared to a 1977 investigation of currents, suspended sediment concentration, and erosion/deposition. The 1977 study found that SSC during spring tide and average river discharge was less than 30 mg/L near the mouth and above 300 mg/L landward, with near-bottom concentrations in the turbidity maximum zone occasionally greater than 1000 mg/L. SSC was highest during low tide and remained elevated throughout, in the upstream part of the estuary. Sediment deposition was stronger after flood tide due to a longer slack period, which implies landward sediment transport in the estuary. In the 2013 study, near-bottom SSC during spring tide and average river discharge was also highest during low tide, but SSC was above 1000 mg

  4. Factors affecting the bacterial community composition and heterotrophic production of Columbia River estuarine turbidity maxima.

    Science.gov (United States)

    Herfort, Lydie; Crump, Byron C; Fortunato, Caroline S; McCue, Lee Ann; Campbell, Victoria; Simon, Holly M; Baptista, António M; Zuber, Peter

    2017-12-01

    Estuarine turbidity maxima (ETM) function as hotspots of microbial activity and diversity in estuaries, yet, little is known about the temporal and spatial variability in ETM bacterial community composition. To determine which environmental factors affect ETM bacterial populations in the Columbia River estuary, we analyzed ETM bacterial community composition (Sanger sequencing and amplicon pyrosequencing of 16S rRNA gene) and bulk heterotrophic production ( 3 H-leucine incorporation rates). We collected water 20 times to cover five ETM events and obtained 42 samples characterized by different salinities, turbidities, seasons, coastal regimes (upwelling vs. downwelling), locations, and particle size. Spring and summer populations were distinct. All May samples had similar bacterial community composition despite having different salinities (1-24 PSU), but summer non-ETM bacteria separated into marine, freshwater, and brackish assemblages. Summer ETM bacterial communities varied depending on coastal upwelling or downwelling conditions and on the sampling site location with respect to tidal intrusion during the previous neap tide. In contrast to ETM, whole (>0.2 μm) and free-living (0.2-3 μm) assemblages of non-ETM waters were similar to each other, indicating that particle-attached (>3 μm) non-ETM bacteria do not develop a distinct community. Brackish water type (ETM or non-ETM) is thus a major factor affecting particle-attached bacterial communities. Heterotrophic production was higher in particle-attached than free-living fractions in all brackish waters collected throughout the water column during the rise to decline of turbidity through an ETM event (i.e., ETM-impacted waters). However, free-living communities showed higher productivity prior to or after an ETM event (i.e., non-ETM-impacted waters). This study has thus found that Columbia River ETM bacterial communities vary based on seasons, salinity, sampling location, and particle size, with the

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

    International Nuclear Information System (INIS)

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

    1989-01-01

    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

  6. Distribution of some radionuclides in the St. Lawrence estuary, Quebec, Canada

    International Nuclear Information System (INIS)

    Serodes, J.B.; Roy, J.C.

    1983-01-01

    The distribution of γ-emitting radionuclides in the St. Lawrence estuary was studied in 1978 and 1979, by means of double sampling and the flocculation and centrifugation of very large volumes of water. Eleven radionuclides were detected, originating from a variety of sources, including soil erosion and nuclear weapons testing. The concentrations measured in 1979 were higher than those of 1978; the 21st Chinese nuclear test could be responsible for the increase of some radionuclides. Concentrations decrease markedly from the freshwater part to the marine region of the estuary. Dilution by oceanic waters, relative affinity with suspended matter and radioactive decay are the principal mechanisms involved in the distribution patterns. Cesium-137, 144 Ce, 226 Ra, 228 Ra and 228 Th are strongly associated with suspended matter, while about two thirds of 7 Be, 106 Ru and 235 U are present in the liquid phase. Results suggest that 235 U is released from sediments in the maximum turbidity zone

  7. The diet and consumption of dominant fish species in the upper Scheldt estuary, Belgium

    DEFF Research Database (Denmark)

    Maes, J.; De Brabandere, Loreto; Ollevier, F.

    2003-01-01

    Seasonal changes in the diet composition and trophic niche overlap were examined for the dominant members of the fish assemblage of the turbid low-salinity zone of the Scheldt estuary (Belgium). Samples of fish were taken in the cooling water of a power plant. Juveniles of eight species dominated...... of trophic niche overlap showed that, in general, niche overlap between individuals of the same species was significantly higher than overlap between individuals from different species, suggesting that the available food resources were partitioned. The total annual prey consumption by the dominant fish...

  8. Seasonal signatures in the physical properties of a tropical estuary in the central america pacific

    OpenAIRE

    Brenes, C. L.; Benavides, R.; Ballestero, D.

    2013-01-01

    A hydrographic survey was carried out in the Jaltepeque estuary in the Pacific coast of El Salvador. From September 2005 to March 2006, 10 sampling stations were occupied to measure temperature, salinity, dissolved oxygen and turbidity. Surface temperatures between 27 and 30.6 °C were observed during the survey, with extreme temporal variations close to 3°C. Minimum temperatures occur in October and February. Surface salinity shows a clear seasonal cycle, with values greater than 30 o/oo duri...

  9. Distribution of Epilithic Diatoms in Estuaries of the Korean Peninsula in Relation to Environmental Variables

    Directory of Open Access Journals (Sweden)

    Ha-Kyung Kim

    2015-11-01

    Full Text Available This study explores the relationships between environmental factors and the distribution of epilithic diatoms in 161 estuaries of three coastal areas on the Korean peninsula. We investigated epilithic diatoms, water quality, and land use in the vicinities of the estuaries during the months of May 2012, 2013 and 2014, because Korea is relatively free from the influences of rainfall at that time of year. We recorded 327 diatom taxa from the study sites, and the assemblage was dominated by members of the Naviculaceae. Bacillariaceae accounted for the largest proportion of diatoms, and Nitzschia inconspicua (18% and N. frustulum (9.6% were the most dominant species. A cluster analysis based on epilithic diatom abundance suggested that the epilithic diatom communities of Korean estuaries can be classified into four large groups (G according to geography, as follows: Ia—the East Sea watershed, Ib—the eastern watershed of the South Sea, IIa—the West Sea watershed, and IIb—the western watershed of the South Sea. The former two groups, Ia and Ib, showed higher proportions of forest land cover and use, higher species occurrence, lower salinity, lower turbidity, and lower concentrations of nutrients than the latter two groups, while the latter groups, IIa and IIb, had higher proportions of agricultural land cover and use, higher electrical conductivity, higher turbidity, higher concentrations of nutrients, and lower species occurrence. The environmental factors underlying the distribution of epilithic diatoms, representative of each region, are as follows: dissolved oxygen and forest land cover and use for Reimeria sinuate and Rhoicosphenia abbreviate of the East Sea (ES, salinity and turbidity for Tabularia fasciculate of the West Sea (WS, and biochemical oxygen demand (BOD and nutrients for Cyclotella meneghiniana of the WS. On the other hand, the most influential environmental factors affecting the occurrence of indicator species showing the

  10. Particulate organic matter predicts bacterial productivity in a river dominated estuary

    Science.gov (United States)

    Crump, B. C.

    2015-12-01

    Estuaries act as coastal filters for organic and inorganic fluvial materials in which microbial, biogeochemical, and ecological processes combine to transform organic matter and nutrients prior to export to the coastal ocean. The function of this estuarine 'bioreactor' is linked to the residence times of those materials and to rates of microbial heterotrophic activity. Our ability to forecast the impact of global change on estuarine bioreactor function requires an understanding of the basic controls on microbial community activity and diversity. In the Columbia River estuary, the microbial community undergoes a dramatic seasonal shift in species composition during which a spring bacterioplankton community, dominated by Flavobacteriaceae and Oceanospirillales, is replaced by a summer community, dominated by Rhodobacteraceae and several common marine taxa. This annual shift occurs in July, following the spring freshet, when river flow and river chlorophyll concentration decrease and when estuarine water residence time increases. Analysis of a large dataset from 17 research cruises (1990-2014) showed that the composition of particulate organic matter in the estuary changes after the freshet with decreasing organic carbon and nitrogen content, and increasing contribution of marine and autochthonous estuarine organic matter (based on PO13C and pigment ratios). Bacterial production rates (measured as leucine or thymidine incorporation rates) in the estuary respond to this change, and correlate strongly with labile particulate nitrogen concentration and temperature during individual sampling campaigns, and with the concentration of chlorophyll in the Columbia River across all seasons. Regression models suggest that the concentration of labile particulate nitrogen and the rate of bacterial production can be predicted from sensor measurements of turbidity, salinity, and temperature in the estuary and chlorophyll in the river. These results suggest that the quality of

  11. Estuary-wide genetic stock distribution and salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  12. Absorption and fluorescence characteristics of chromophoric dissolved organic matter in the Yangtze Estuary.

    Science.gov (United States)

    Sun, Qiyuan; Wang, Chao; Wang, Peifang; Hou, Jun; Ao, Yanhui

    2014-03-01

    The Yangtze Estuary is heavily influenced by coast-continent geochemical processes and anthropogenic activity; thus, the source and distribution of chromophoric dissolved organic matter (CDOM) in the estuary are strongly impacted by these processes. Here, a series of samples were collected from across the Yangtze Estuary to investigate the source and spatial dynamics of CDOM and its components throughout the system. Three indices (a(355), spectral slope, and fluorescence) were then calculated and interpreted. The results indicated that the distribution of CDOM was dominated by allochthonous input, conservative mixing, and phase transfer. The contribution of biogenic CDOM to total CDOM increased with salinity, and three individual CDOM components were identified upon fluorescence excitation emission matrix spectroscopy and parallel factor analysis of the water samples: C1, corresponding to humic substance-like CDOM, C2, corresponding to tryptophan-like CDOM, and C3, corresponding to tyrosine-like CDOM. C1 primarily originated from a terrestrial source, C2 had widespread origins, none of which played a dominant role, and C3 mainly originated from allochthonous input in the medium salinity area. Unexpectedly, no marine humic-like component was found in the surface water of the Yangtze Estuary, possibly because turbidity decreased the depth of sunlight penetration, limiting production of this component.

  13. The hyperturbid state of the water column in estuaries and rivers: the importance of hindered settling

    Science.gov (United States)

    Dijkstra, Yoeri M.; Schuttelaars, Henk M.; Winterwerp, Johan C.

    2018-03-01

    Over the last few decades, some estuaries have undergone a transition to a hyperturbid state, characterised by suspended sediment concentrations of several grammes per litre averaged over the water column. To improve our understanding of this transition and of naturally hyperturbid estuaries, we systematically identify the processes allowing for high suspended sediment concentrations using a water column (1DV) model. Under a range of realistic forcing conditions, the state of the water column can be characterised by one of two equilibrium states. The first is an erosion-limited state, in which there still is sediment available for erosion at the bed. We find that this state only occurs with relatively low concentrations. The second is a supply-limited state, in which all erodable sediment is in suspension. The concentration in this state depends entirely on the amount of sediment in the system and can potentially be very high. We identify the conditions under which the state of the water column can jump from a low to a high concentration and identify hysteresis in the transition between the two states. The mechanism responsible for this hysteresis is hindered settling. It thus follows that hyperturbidity is only possible in a supply-limited state. From this observation we derive a necessary condition for an estuarine system to make the transition from low turbidity to hyperturbidity in a 1DV context. This is an important step towards understanding why some estuaries are hyperturbid and assessing the risk that particular estuaries may become hyperturbid in the future.

  14. Microscopic imaging through turbid media Monte Carlo modeling and applications

    CERN Document Server

    Gu, Min; Deng, Xiaoyuan

    2015-01-01

    This book provides a systematic introduction to the principles of microscopic imaging through tissue-like turbid media in terms of Monte-Carlo simulation. It describes various gating mechanisms based on the physical differences between the unscattered and scattered photons and method for microscopic image reconstruction, using the concept of the effective point spread function. Imaging an object embedded in a turbid medium is a challenging problem in physics as well as in biophotonics. A turbid medium surrounding an object under inspection causes multiple scattering, which degrades the contrast, resolution and signal-to-noise ratio. Biological tissues are typically turbid media. Microscopic imaging through a tissue-like turbid medium can provide higher resolution than transillumination imaging in which no objective is used. This book serves as a valuable reference for engineers and scientists working on microscopy of tissue turbid media.

  15. 75 FR 34975 - Notice of Estuary Habitat Restoration Council's Intent to Revise its Estuary Habitat Restoration...

    Science.gov (United States)

    2010-06-21

    ... Estuary Habitat Restoration Council's Intent to Revise its Estuary Habitat Restoration Strategy; Request... interagency Estuary Habitat Restoration Council, is providing notice of the Council's intent to revise the ''Estuary Habitat Restoration Strategy'' and requesting public comments to guide its revision. DATES...

  16. A multilayer approach for turbidity currents

    Science.gov (United States)

    Fernandez-Nieto, Enrique; Castro Díaz, Manuel J.; Morales de Luna, Tomás

    2017-04-01

    When a river that carries sediment in suspension enters into a lake or the ocean it can form a plume that can be classified as hyperpycnal or hypopycnal. Hypopycnal plumes occurs if the combined density of the sediment and interstitial fluid is lower than that of the ambient. Hyperpycnal plumes are a class of sediment-laden gravity current commonly referred to as turbidity currents [7,9]. Some layer-averaged models have been previously developed (see [3, 4, 8] among others). Although this layer-averaged approach gives a fast and valuable information, it has the disadvantage that the vertical distribution of the sediment in suspension is lost. A recent technique based on a multilayer approach [1, 2, 6] has shown to be specially useful to generalize shallow water type models in order to keep track of the vertical components of the averaged variables in the classical shallow water equations. In [5] multilayer model is obtained using a vertical discontinuous Galerkin approach for which the vertical velocity is supposed to be piecewise linear and the horizontal velocity is supposed to be piecewise constant. In this work the technique introduced in [5] is generalized to derive a model for turbidity currents. This model allows to simulate hyperpycnal as well as hypopycnal plumes. Several numerical tests will be presented. References [1] E. Audusse, M. Bristeau, B. Perthame, and J. Sainte-Marie. A multilayer Saint-Venant system with mass exchanges for shallow water flows. derivation and numerical validation. ESAIM: Mathematical Modelling and Numerical Analysis, 45(1):169-200, (2010). [2] E. Audusse, M.-O. Bristeau, M. Pelanti, and J. Sainte-Marie. Approximation of the hydrostatic Navier–Stokes system for density stratified flows by a multilayer model: Kinetic interpretation and numerical solution. Journal of Computational Physics, 230(9):3453-3478, (2011). [3] S. F. Bradford and N. D. Katopodes. Hydrodynamics of turbid underflows. i: Formulation and numerical

  17. Turbidity data: Hollywood Beach, Florida, January 1990 to April 1992

    OpenAIRE

    Dompe, Philip E.; Hanes, D. M.

    1993-01-01

    This data report contains measurements of turbidity obtained near Hollywood, Florida, during the period of January 1990 to April 1992. Data were obtained within one meter of the seabed in depths of 5 m and 10 m. Turbidity was found to vary significantly under natural conditions, with values during storms sometimes exceeding 29 NTU. Tables and plots of turbidity data are presented. (Document contains 77 pages.)

  18. Atmospheric turbidity and the diffuse irradiance in Lagos, Nigeria

    International Nuclear Information System (INIS)

    Maduekwe, A.A.L.; Chendo, M.A.C.

    1994-06-01

    The relationships between the total hemispherical irradiance reaching the earth surface in Lagos, Nigeria and the turbidity coefficients at two wavelengths namely λ(500) and λ(880) measured with a Volz sun photometer have been investigated. Using simple piecewise linear regression relationships between the atmospheric turbidity using Angstrom turbidity coefficients and the diffuse components of solar radiation are presented. (author). 18 refs, 11 figs, 3 tabs

  19. Absorption coefficient instrument for turbid natural waters

    Science.gov (United States)

    Friedman, E.; Cherdak, A.; Poole, L.; Houghton, W.

    1980-01-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  20. Frequent Questions about Estuary Data Mapper (EDM)

    Science.gov (United States)

    Estuary Data Mapper is a tool for geospatial data discovery, visualization, and data download for any of the approximately 2,000 estuaries and associated watersheds in along the five US coastal regions

  1. Downloading and Installing Estuary Data Mapper (EDM)

    Science.gov (United States)

    Estuary Data Mapper is a tool for geospatial data discovery, visualization, and data download for any of the approximately 2,000 estuaries and associated watersheds in along the five US coastal regions

  2. Influence of estuaries on shelf foraminiferal species

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    Dabhol-bhatkal stretch of the west coast of India is marked by a number of estuaries. Cavarotalia annectens is selected to monitor the influence of these estuaries on the inner shelf foraminiferal fauna. The percentage distribution of this species...

  3. SANCOR estuaries programme 1982-1986

    CSIR Research Space (South Africa)

    SANCOR

    1983-02-01

    Full Text Available , such research will also aid in the rational management of estuaries. Estuaries on which research should be concentrated are identified and guidelines are given for project proposals and reporting....

  4. Nutrients in some estuaries of Kerala

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, K.S.; Venugopal, P.; Remani, K.N.; Zacharias, D.; Unnithan, R.V.

    phosphate and ammonia were high at Kallai compared to other three estuaries. All the estuaries showed an increase in nitrate content during monsoon. Nitrite values were high in postmonsoon. Ammonia levels were generally high except at Korapuzha. Nutrient...

  5. Reduction of Turbidity of Water Using Locally Available Natural Coagulants

    Science.gov (United States)

    Asrafuzzaman, Md.; Fakhruddin, A. N. M.; Hossain, Md. Alamgir

    2011-01-01

    Turbidity imparts a great problem in water treatment. Moringa oleifera, Cicer arietinum, and Dolichos lablab were used as locally available natural coagulants in this study to reduce turbidity of synthetic water. The tests were carried out, using artificial turbid water with conventional jar test apparatus. Optimum mixing intensity and duration were determined. After dosing water-soluble extracts of Moringa oleifera, Cicer arietinum, and Dolichos lablab reduced turbidity to 5.9, 3.9, and 11.1 nephelometric turbidity unit (NTU), respectively, from 100 NTU and 5, 3.3, and 9.5, NTU, respectively, after dosing and filtration. Natural coagulants worked better with high, turbid, water compare to medium, or low, turbid, water. Highest turbidity reduction efficiency (95.89%) was found with Cicer arietinum. About 89 to 96% total coliform reduction were also found with natural coagulant treatment of turbid water. Using locally available natural coagulants, suitable, easier, and environment friendly options for water treatment were observed. PMID:23724307

  6. Unusual behaviour of phototrophic picoplankton in turbid waters.

    Science.gov (United States)

    Somogyi, Boglárka; Pálffy, Károly; V-Balogh, Katalin; Botta-Dukát, Zoltán; Vörös, Lajos

    2017-01-01

    Autotrophic picoplankton (APP) abundance and contribution to phytoplankton biomass was studied in Hungarian shallow lakes to test the effect of inorganic turbidity determining the size distribution of the phytoplankton. The studied lakes displayed wide turbidity (TSS: 4-2250 mg l-1) and phytoplankton biomass (chlorophyll a: 1-460 μg l-1) range, as well as APP abundance (0 and 100 million cells ml-1) and contribution (0-100%) to total phytoplankton biomass. Inorganic turbidity had a significant effect on the abundance and contribution of APP, resulting in higher values compared to other freshwater lakes with the same phytoplankton biomass. Our analysis has provided empirical evidence for a switching point (50 mg l-1 inorganic turbidity), above which turbidity is the key factor causing APP predominance regardless of phytoplankton biomass in shallow turbid lakes. Our results have shown that turbid shallow lakes are unique waters, where the formerly and widely accepted model (decreasing APP contribution with increasing phytoplankton biomass) is not applicable. We hypothesize that this unusual behaviour of APP in turbid waters is a result of either diminished underwater light intensity or a reduced grazing pressure due to high inorganic turbidity.

  7. Unusual behaviour of phototrophic picoplankton in turbid waters.

    Directory of Open Access Journals (Sweden)

    Boglárka Somogyi

    Full Text Available Autotrophic picoplankton (APP abundance and contribution to phytoplankton biomass was studied in Hungarian shallow lakes to test the effect of inorganic turbidity determining the size distribution of the phytoplankton. The studied lakes displayed wide turbidity (TSS: 4-2250 mg l-1 and phytoplankton biomass (chlorophyll a: 1-460 μg l-1 range, as well as APP abundance (0 and 100 million cells ml-1 and contribution (0-100% to total phytoplankton biomass. Inorganic turbidity had a significant effect on the abundance and contribution of APP, resulting in higher values compared to other freshwater lakes with the same phytoplankton biomass. Our analysis has provided empirical evidence for a switching point (50 mg l-1 inorganic turbidity, above which turbidity is the key factor causing APP predominance regardless of phytoplankton biomass in shallow turbid lakes. Our results have shown that turbid shallow lakes are unique waters, where the formerly and widely accepted model (decreasing APP contribution with increasing phytoplankton biomass is not applicable. We hypothesize that this unusual behaviour of APP in turbid waters is a result of either diminished underwater light intensity or a reduced grazing pressure due to high inorganic turbidity.

  8. Leven estuary project. Fisheries Department final report

    OpenAIRE

    Bayliss, B.D.

    1997-01-01

    This is the report on the Leven estuary project: Fisheries Department final report produced by the Environment Agency North West in 1997. This report contains information about Leven estuary, river Leven catchment, river Crake catchment and the Ulverston Discharges. The Leven estuary is characterised by being very shallow, and shares the extremely variable tides and currents that characterize the whole of Morecambe Bay. There was little detailed knowledge of the impact on the Leven estuary, a...

  9. Indian estuaries: Dynamics, ecosystems, and threats

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.

    the tide pulls the mixed water out of the estuary through its mouth. Different processes within an estuary contribute to mixing of the two waters, the important among these in the Mandovi estuary are: influence of the tide on the advective field within...

  10. Application of MODIS Products to Infer Possible Relationships Between Basin Land Cover and Coastal Waters Turbidity Using the Magdalena River, Colombia, as a Case Study

    Science.gov (United States)

    Madrinan, Max Jacobo Moreno; Cordova, Africa Flores; Olivares, Francisco Delgado; Irwin, Dan

    2012-01-01

    Basin development and consequent change in basin land cover have been often associated with an increased turbidity in coastal waters because of sediment yield and nutrients loading. The later leads to phytoplankton abundance further exacerbating water turbidity. This subsequently affects biological and physical processes in coastal estuaries by interfering with sun light penetration to coral reefs and sea grass, and even affecting public health. Therefore, consistent estimation of land cover changes and turbidity trend lines is crucial to design environmental and restoration management plans, to predict fate of possible pollutants, and to estimate sedimentary fluxes into the ocean. Ground solely methods to estimate land cover change would be unpractical and traditional methods of monitoring in situ water turbidity can be very expensive and time consuming. Accurate monitoring on the status and trends of basin land cover as well as the water quality of the receiving water bodies are required for analysis of relationships between the two variables. Use of remote sensing (RS) technology provides a great benefit for both fields of study, facilitating monitoring of changes in a timely and cost effective manner and covering wide areas with long term measurements. In this study, the Magdalena River basin and fixed geographical locations in the estuarine waters of its delta are used as a case to study the temporal trend lines of both, land cover change and the reflectance of the water turbidity using satellite technology. Land cover data from a combined product between sensors Terra and Aqua (MCD12Q1) from MODIS will be adapted to the conditions in the Magdalena basin to estimate changes in land cover since year 2000 to 2009. Surface reflectance data from a MODIS, Terra (MOD09GQ), band 1, will be used in lieu of in situ water turbidity for the time period between 2000 and present. Results will be compared with available existing data.

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

    Science.gov (United States)

    Juhl, Andrew R.; Anderson, O. Roger

    2014-12-01

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

  12. Turbidity-controlled sampling for suspended sediment load estimation

    Science.gov (United States)

    Jack Lewis

    2003-01-01

    Abstract - Automated data collection is essential to effectively measure suspended sediment loads in storm events, particularly in small basins. Continuous turbidity measurements can be used, along with discharge, in an automated system that makes real-time sampling decisions to facilitate sediment load estimation. The Turbidity Threshold Sampling method distributes...

  13. Turbidity affects foraging success of drift-feeding rosyide dace

    Science.gov (United States)

    Richard M. Zamor; Gary D. Grossman

    2007-01-01

    The effects of suspended sediment on nongame fishes are not well understood. We examined the effects of suspended sediment (i.e., turbidity) on reactive distance and prey capture success at springautumn (12°C) and summer (18°C) temperatures for royside dace Clinostomus funduloides in an artificial stream. Experimental turbidities ranged from 0 to 56...

  14. Turbidity threshold sampling for suspended sediment load estimation

    Science.gov (United States)

    Jack Lewis; Rand Eads

    2001-01-01

    Abstract - The paper discusses an automated procedure for measuring turbidity and sampling suspended sediment. The basic equipment consists of a programmable data logger, an in situ turbidimeter, a pumping sampler, and a stage-measuring device. The data logger program employs turbidity to govern sample collection during each transport event. Mounting configurations and...

  15. Suspended Sediment Dynamics in the Macrotidal Seine Estuary (France): 2. Numerical Modeling of Sediment Fluxes and Budgets Under Typical Hydrological and Meteorological Conditions

    Science.gov (United States)

    Schulz, E.; Grasso, F.; Le Hir, P.; Verney, R.; Thouvenin, B.

    2018-01-01

    Understanding the sediment dynamics in an estuary is important for its morphodynamic and ecological assessment as well as, in case of an anthropogenically controlled system, for its maintenance. However, the quantification of sediment fluxes and budgets is extremely difficult from in-situ data and requires thoroughly validated numerical models. In the study presented here, sediment fluxes and budgets in the lower Seine Estuary were quantified and investigated from seasonal to annual time scales with respect to realistic hydro- and meteorological conditions. A realistic three-dimensional process-based hydro- and sediment-dynamic model was used to quantify mud and sand fluxes through characteristic estuarine cross-sections. In addition to a reference experiment with typical forcing, three experiments were carried out and analyzed, each differing from the reference experiment in either river discharge or wind and waves so that the effects of these forcings could be separated. Hydro- and meteorological conditions affect the sediment fluxes and budgets in different ways and at different locations. Single storm events induce strong erosion in the lower estuary and can have a significant effect on the sediment fluxes offshore of the Seine Estuary mouth, with the flux direction depending on the wind direction. Spring tides cause significant up-estuary fluxes at the mouth. A high river discharge drives barotropic down-estuary fluxes at the upper cross-sections, but baroclinic up-estuary fluxes at the mouth and offshore so that the lower estuary gains sediment during wet years. This behavior is likely to be observed worldwide in estuaries affected by density gradients and turbidity maximum dynamics.

  16. Polymeric turbidity sensor fabricated by laser direct writing

    International Nuclear Information System (INIS)

    Li, Shu; Lin, Qiao; Wu, George; Chen, Liuhua; Wu, X

    2011-01-01

    The design of a miniature-sized turbidity sensor fabricated by laser direct writing was proposed and tested. A dual-beam dual-detector sensing structure was written by a 488 nm laser from UV curable optical polymer to form a 4 mm diameter turbidity sensing probe, with the fabrication process being shortened to a few seconds. Experimental tests on prototypes were conducted by using standard turbidity solutions, and the data were processed with a self-adapting neural network based on a single input single output algorithm. The scattering coefficient for normalized turbidity of the standards was obtained, and system accuracy was validated by an error analysis. Experimental results indicated that in the testing situation presented in this paper, the sensor was capable of responding to turbidity with a relative error of about 3%

  17. Hydrologic data summary for the St. Lucie River Estuary, Martin and St. Lucie Counties, Florida, 1998-2001

    Science.gov (United States)

    Byrne, Michael J.; Patino, Eduardo

    2004-01-01

    A hydrologic analysis was made at three canal sites and four tidal sites along the St. Lucie River Estuary in southeastern Florida from 1998 to 2001. The data included for analysis are stage, 15-minute flow, salinity, water temperature, turbidity, and suspended-solids concentration. During the period of record, the estuary experienced a drought, major storm events, and high-water discharge from Lake Okeechobee. Flow mainly occurred through the South Fork of the St. Lucie River; however, when flow increased through control structures along the C-23 and C-24 Canals, the North Fork was a larger than usual contributor of total freshwater inflow to the estuary. At one tidal site (Steele Point), the majority of flow was southward toward the St. Lucie Inlet; at a second tidal site (Indian River Bridge), the majority of flow was northward into the Indian River Lagoon. Large-volume stormwater discharge events greatly affected the St. Lucie River Estuary. Increased discharge typically was accompanied by salinity decreases that resulted in water becoming and remaining fresh throughout the estuary until the discharge events ended. Salinity in the estuary usually returned to prestorm levels within a few days after the events. Turbidity decreased and salinity began to increase almost immediately when the gates at the control structures closed. Salinity ranged from less than 1 to greater than 35 parts per thousand during the period of record (1998-2001), and typically varied by several parts per thousand during a tidal cycle. Suspended-solids concentrations were observed at one canal site (S-80) and two tidal sites (Speedy Point and Steele Point) during a discharge event in April and May 2000. Results suggest that most deposition of suspended-solids concentration occurs between S-80 and Speedy Point. The turbidity data collected also support this interpretation. The ratio of inorganic to organic suspended-solids concentration observed at S-80, Speedy Point, and Steele Point

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-12

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

  19. Using a dual isotopic approach to trace sources and mixing of sulphate in Changjiang Estuary, China

    International Nuclear Information System (INIS)

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

    2011-01-01

    Highlights: → Changjiang Estuary plays an important role in transportation of the water and solute. → The dual isotopic method could be used to understand sulfate biogeochemistry in estuaries. → Mixing processes should be a major factor involved in the distribution of water and sulphate. → Sulphate in the Changjiang River mainly derived from atmospheric deposition, evaporite dissolution and sulphide oxidation. - Abstract: The dual isotopic compositions of dissolved SO 4 2- in aquatic systems are commonly used to ascertain SO 4 2- sources and possible biogeochemical processes. In this study, the physical parameters, major anions and isotopic compositions of SO 4 2- in water samples from Changjiang River (Nanjin) to the East Sea in Changjiang Estuary were determined. The salinity ranged from 0 per mille to 32.3 per mille in the estuary water samples. The Cl - ,SO 4 2- concentrations and δ 18 O-H 2 O values followed the salinity variations from freshwater to seawater, which indicated that mixing processes might be a major factor involved in the distribution of water and solutes. The contents and isotopic compositions of SO 4 2- suggested that atmospheric deposition, evaporite dissolution and sulphide oxidation were the major sources of dissolved SO 4 2- in the freshwater of Changjiang River. In addition, the mixing model calculated by contents and isotopic compositions of SO 4 2- indicated that the mixing of freshwater and sea water was the major factor involved in SO 4 2- distribution in Changjiang Estuary. However, slightly elevated δ 18 O-SO 4 values were observed in the turbidity maximum zone, which suggested that biological processes might affect the O isotopic compositions of SO 4 2- there.

  20. Modelling Macroalgae Productivity In An Estuary. A Biorremediation To Nutrient Discharges In The Ecosystems.

    Science.gov (United States)

    Alvera-Azcárate, A.; Ferreira, J. G.; Nunes, J. P.

    Enhanced nutrient load to estuaries and coastal waters due to anthropogenic activities is damaging aquatic ecosystems, resulting in water pollution and eutrophication prob- lems. It is important to quantify the production of photosynthetic organisms, as they play an important role in controlling nitrogen removal and nitrogen fluxes between the sediments and the water column. In turbid estuaries, such as those on the NE Atlantic coast of Europe, benthic primary producers such as macroalgae may play an important part in carbon fixation and nutrient removal, since pelagic production is often strongly light-limited. Estuarine seaweeds are primarily located in intertidal areas, which are characterised by shallow waters and strong tidal currents. Due to high concentrations of suspended particulate matter in the water column, light is rapidly attenuated, limiting macroal- gae production during part of the tidal cycle. An accurate representation of sediment dynamics is essential for the determination of the light energy available for the algae, which is a key factor in reliable primary production estimates. In tidal flats, the sedi- ment dynamics is made more complex by the formation of tidal pools during low tide, where water quickly becomes clear, allowing more light to penetrate through the water column. In the present work a model is developed to calculate macroalgae production in the intertidal areas of estuaries, considering the factors mentioned above. The model is tested for the Tagus estuary (Portugal), and a Gross Primary Production of 3300 g m-2 y-1 was obtained. That results in a total nitrogen removal of 440 gN m-2 y-1. The results show that the macroalgae community plays an impor- tant role in the nitrogen cycle in estuaries and nutrient export to the open sea, acting as a biorremediation for the increased nutrient loading problem.

  1. Environmental drivers of the benthic macroinvertebrates community in a hypersaline estuary (Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Carlinda Railly Ferreira Medeiros

    Full Text Available Abstract Introduction The estuarine community of benthic macroinvertebrates spatially varies in response to changes in environmental variables in these ecosystems. Understanding this variability helps our understanding the mechanisms structuring these communities. Aim Assess the structural aspects of the benthic macroinvertebrate community in a hypersaline estuary, and to relate to environmental variables that influence the community structure along the estuary. Methods The study was conducted at Tubarão river estuary in May 2015. We sampled two estuarine areas (upper and lower, and in each zone were sampled six points composed of two replicas, one sampled in sandy bottom and the other in muddy bottom. Samples of benthic macroinvertebrates and estuarine environmental variables were collected. Environmental drivers of the benthic macroinvertebrate community were determined by Distance-based Linear Models analysis. The contribution of individual species to the dissimilarity between the areas and substrate types were determined by analysis of the percentage of similarity. Results The composition of benthic macroinvertebrate community differed between the upper and lower areas, although it was similar between the muddy and sandy bottoms. The variation in the benthic community between areas was mainly related to the influence of salinity in the upper area. In the lower area, the variation of the macroinvertebrates was related to salinity, associated with other variables in the sandy (temperature, turbidity and dissolved oxygen and muddy (temperature, total dissolved solids and dissolved oxygen substrates. Taxa which contributed most to the dissimilarity between the upper and lower areas were Nereididae (17.89%, Anomalocardia brasiliana (15% and Cirratulidae (10.43%. Conclusions Salinity was the main driver of the structural aspects of the benthic macroinvertebrate community in the upper area of the estuary, although in the lower area a set of

  2. Source identification, geochemical normalization and influence factors of heavy metals in Yangtze River Estuary sediment.

    Science.gov (United States)

    Sun, Xueshi; Fan, Dejiang; Liu, Ming; Tian, Yuan; Pang, Yue; Liao, Huijie

    2018-06-18

    Sediment samples, including 40 surface samples and 12 sediment cores, were collected from 52 stations of the Yangtze River Estuary (YRE) in 2015 and 2016. The 95% linear prediction intervals (LPI) and principal components analysis (PCA), were conducted to evaluate the metal sources and grain-size effect (GSE). The in situ physico-chemical properties of pH, Eh, DO, salinity, temperature and turbidity were combined to elucidate the relationships between environmental factors and the fate of heavy metals in the river-estuary-shelf system. This study indicates a decreasing trend of metals in sediments from the estuary towards the adjacent shelf and the river channel and that Zn, Cu and Cr are mainly derived from natural processes throughout the catchment, whereas Pb appears to have anthropogenic inputs via atmospheric deposition. Furthermore, considering the best fit regression lines between the concentrations of Al and heavy metals as well as the deficiencies of the conventional C elements /C Al method, we introduce an approach (Al-SN: Al-scope normalization) that can eliminate the GSE on heavy metals and be applied to other estuaries. After Al-scope normalization, the relatively constant levels of Zn, Cu and Cr that remain in sediments from the river channel to the estuary and shelf confirmed that the variation of grain size in sediments almost entirely explained the distribution patterns of sediment toxicity in the YRE, while the enrichment of Pb in estuarine sediments could be attributed to its chemical species and physico-chemical properties. The results further suggest that the relationship between grain size and spatial behavior of sediment pollutants should be given priority over the contamination assessment and provenance discrimination in estuarine or similar environments with complex sediment compositions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Biogeochemical budgets for Tapi Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Bapardekar, M.V.; DeSousa, S.N.; Zingde, M.D.

    sup(-1) comes from the wastes. Chemical fertilizers are used in the basin at the rate of 113 kg.ha sup(-1). During the dry season the salinity in the estuary decreases progressively in the upstream direction form an average 32.53 psu at the mouth to 0...

  4. Food Webs in an Estuary.

    Science.gov (United States)

    Dunne, Barbara B.

    The Maryland Marine Science Education Project has produced a series of mini-units in marine science education for the junior high/middle school classroom. This unit focuses on food chains in an estuary. Although the unit specifically treats the Chesapeake Bay, it may be adapted for use with similar estuarine systems. In addition, the unit may be…

  5. Simulated Sampling of Estuary Plankton

    Science.gov (United States)

    Fortner, Rosanne W.; Jenkins, Deborah Bainer

    2009-01-01

    To find out about the microscopic life in the valuable estuary environment, it is usually necessary to be near the water. This dry lab offers an alternative, using authentic data and a simulation of plankton sampling. From the types of organisms found in the sample, middle school students can infer relationships in the biological and physical…

  6. Performance Evaluation of Five Turbidity Sensors in Three Primary Standards

    Science.gov (United States)

    Snazelle, Teri T.

    2015-10-28

    Open-File Report 2015-1172 is temporarily unavailable.Five commercially available turbidity sensors were evaluated by the U.S. Geological Survey, Hydrologic Instrumentation Facility (HIF) for accuracy and precision in three types of turbidity standards; formazin, StablCal, and AMCO Clear (AMCO–AEPA). The U.S. Environmental Protection Agency (EPA) recognizes all three turbidity standards as primary standards, meaning they are acceptable for reporting purposes. The Forrest Technology Systems (FTS) DTS-12, the Hach SOLITAX sc, the Xylem EXO turbidity sensor, the Yellow Springs Instrument (YSI) 6136 turbidity sensor, and the Hydrolab Series 5 self-cleaning turbidity sensor were evaluated to determine if turbidity measurements in the three primary standards are comparable to each other, and to ascertain if the primary standards are truly interchangeable. A formazin 4000 nephelometric turbidity unit (NTU) stock was purchased and dilutions of 40, 100, 400, 800, and 1000 NTU were made fresh the day of testing. StablCal and AMCO Clear (for Hach 2100N) standards with corresponding concentrations were also purchased for the evaluation. Sensor performance was not evaluated in turbidity levels less than 40 NTU due to the unavailability of polymer-bead turbidity standards rated for general use. The percent error was calculated as the true (not absolute) difference between the measured turbidity and the standard value, divided by the standard value.The sensors that demonstrated the best overall performance in the evaluation were the Hach SOLITAX and the Hydrolab Series 5 turbidity sensor when the operating range (0.001–4000 NTU for the SOLITAX and 0.1–3000 NTU for the Hydrolab) was considered in addition to sensor accuracy and precision. The average percent error in the three standards was 3.80 percent for the SOLITAX and -4.46 percent for the Hydrolab. The DTS-12 also demonstrated good accuracy with an average percent error of 2.02 percent and a maximum relative standard

  7. Study of the behaviour of trace elements in estuaries: experimental approaches and modeling

    International Nuclear Information System (INIS)

    Dange, Catherine

    2002-01-01

    Most of trace elements have a non conservative behavior in estuarine environments. It is the case of cadmium, cobalt and caesium for which the fate in estuarine and coastal zones is largely controlled by their distribution between water and suspended particles, which generally have high residence times or can be definitely deposited in these areas. Metallic contaminants and radionuclides can be present under various species: dissolved (mineral and organic complexes), colloidal and particulate forms (adsorbed, precipitated) or integrated by various mechanisms in the organisms. Such distributions are the result of processes (physical, chemical, biological) which are controlled by many factors (ionic strength, pH, E_h, major cations concentration, nature and concentration of suspended matter, primary production,...). Geochemical modeling is a very useful approach to understand the dynamics of this type of contaminant, especially in the complex systems which are the estuaries. A speciation model was used to simulate the measurements of dissolved and particulate Cd, Co and Cs, taken during various cruises carried out in the Seine, Loire, Gironde and Rhone estuaries. The model is able to reproduce the distribution of metals between the dissolved and particulate phases, and also to evaluate the concentrations of various chemical species (especially those which are most bio-available). The approach presented treats adsorption processes as a formation of inner sphere complexes with functional surface groups (surface complexation model) or as an cationic exchange reaction. The calculation of chemical species takes into account the presence of dissolved ligands or major cations of seawater, which compete with the metal for the surface sites. The model can consider the various natural particle components (metal oxy-hydroxides, organic matter) as individual adsorbent phases or treat natural particles in a 'global manner'. The choice of modeled processes is based on studies of

  8. Treatment of Highly Turbid Water by Polyaluminum Ferric Chloride (PAFCL

    Directory of Open Access Journals (Sweden)

    Fazel Fazel Mohammadi-Moghaddam

    2015-10-01

    Full Text Available Background & Aims of the Study: In some situation like rainfall seasons raw water become very turbid so it affected the water treatment plant processes and quality of produced water. Treatment of very high turbid water has some concerns like precursors for disinfection by-products and very loading rate of particle on filter's media and consequently increases in water consumption for filter backwash. This paper investigates the performance of a composite inorganic polymer of aluminium and ferric salt, Polyaluminium ferric chloride (PAFCl, for the removal of turbidity, color and natural organic matter (NOM from high turbid water. Materials and Methods: Experiments were carried out by Jar test experiment by synthetic water samples with 250 and 500 NTU turbidity that prepared in laboratory. Results: The results of conventional jar test showed that the optimum pH for coagulation of water sample was 7.5 to 8 and optimum dosage of the coagulant was 10 mg/L. Removal efficiency of turbidity, color and UV adsorbent at 254 nm at optimum dose and pH without filtration was 99.92%, 100% and 80.6% respectively for first sample (250 NTU and 99.95%, 99.49% and 84.77 for second sample (500 NTU respectively. Conclusion: It concluded that polyaluminium ferric chloride has a very good efficiency for the removal of turbidity, color and organic matter in high turbid water. Also it can be select as a coagulant for high turbid water and some waste water from water treatment plant like filter backwash water.

  9. Mercury dynamics in a San Francisco estuary tidal wetland: assessing dynamics using in situ measurements

    Science.gov (United States)

    Bergamaschi, Brian A.; Fleck, Jacob A.; Downing, Bryan D.; Boss, Emmanuel; Pellerin, Brian A.; Ganju, Neil K.; Schoellhamer, David H.; Byington, Amy A.; Heim, Wesley A.; Stephenson, Mark; Fujii, Roger

    2012-01-01

    We used high-resolution in situ measurements of turbidity and fluorescent dissolved organic matter (FDOM) to quantitatively estimate the tidally driven exchange of mercury (Hg) between the waters of the San Francisco estuary and Browns Island, a tidal wetland. Turbidity and FDOM—representative of particle-associated and filter-passing Hg, respectively—together predicted 94 % of the observed variability in measured total mercury concentration in unfiltered water samples (UTHg) collected during a single tidal cycle in spring, fall, and winter, 2005–2006. Continuous in situ turbidity and FDOM data spanning at least a full spring-neap period were used to generate UTHg concentration time series using this relationship, and then combined with water discharge measurements to calculate Hg fluxes in each season. Wetlands are generally considered to be sinks for sediment and associated mercury. However, during the three periods of monitoring, Browns Island wetland did not appreciably accumulate Hg. Instead, gradual tidally driven export of UTHg from the wetland offset the large episodic on-island fluxes associated with high wind events. Exports were highest during large spring tides, when ebbing waters relatively enriched in FDOM, dissolved organic carbon (DOC), and filter-passing mercury drained from the marsh into the open waters of the estuary. On-island flux of UTHg, which was largely particle-associated, was highest during strong winds coincident with flood tides. Our results demonstrate that processes driving UTHg fluxes in tidal wetlands encompass both the dissolved and particulate phases and multiple timescales, necessitating longer term monitoring to adequately quantify fluxes.

  10. In-stream PIT detection, estuary wetlands - Columbia River Estuary Tidal Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  11. Salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  12. Diel variation in the catch of fishes and penaeid shrimps in a tropical estuary

    Science.gov (United States)

    Stoner, Allan W.

    1991-07-01

    In Laguna Joyuda, Puerto Rico, 24-h trawl surveys were conducted to test the hypothesis that there is no diel variation in the catch rate of fishes and penaeid shrimps in a turbid, microtidal estuary relatively free of visual predation. The null hypothesis was not rejected for the two most abundant fishes in the lagoon, Eucinostomus gula (Gerreidae) and Achirus lineatus (Bothidae). Conversely, the total number of fishes, Diapterus rhombeus (Gerreidae), and the engraulids Anchoa cubana and A. hepsetus were collected in significantly higher numbers during hours of darkness. Total penaeid catch was significantly higher in night than in day collections. The most abundant species were Penaeus notialis and P. subtilis, both of which appeared to be strong daytime burrowers. Small penaeids demonstrated greater diel variation in trawl capture rate than larger (subadult) shrimps. Diel variation in capture rate was related to habitat associations of individual species. Fauna resident in the very turbid lagoon demonstrated no diel variation in activity patterns and trawl susceptibility. Those species which spend only the early part of their lives in the lagoon, or live in both turbid and clear water, had significant diel variation in activity and trawl catchability.

  13. Bioprospektif Perairan Berdasarkan Produktivitas : Studi Kasus Estuari Sungai Serayu Cilacap, Indonesia

    Directory of Open Access Journals (Sweden)

    Nur Laila Rahayu

    2017-08-01

    Full Text Available The high changes of Serayu River land use is resulting the high of load particle sedimentation into the body of water. Turbidity will accumulate in the downstream or estuaries which would have an impact on biota, especially plankton as primary productivity and secondary productivity. This research is conducted with a survey method and purposive sampling technique. Estuary Serayu River is divided into 5 stations, starts from the nearest to the sea (1 with 26 ‰ salinity and the furthest stations from the sea (5 with 8 ‰ salinity. Samples of water and plankton are taken at the time of high tide and low tide every month, for 4 months (August, September, October, and November 2016. The obtained data is analyzed by PCA to study the environmental factors towards primary productivity and secondary productivity. Based on the research result environmental factors has relation waters estuary productivity of Serayu river on the highest and lowest tide those are lightness, level TSS and pH.

  14. [Optical characteristics of colored dissolved organic material (CDOM) in Yangtze Estuary].

    Science.gov (United States)

    Zhu, Wei-Jian; Shen, Fang; Hong, Guan-Lin

    2010-10-01

    Absorption property of colored dissolved organic material (CDOM) is one of the most important contents to remote sensing of ocean color in estuarine and coastal areas. In this study, the optical properties and mixing behavior of CDOM in surface water of Yangtze Estuary were discussed according to the two surveys in August of 2008 and May of 2009. Based on the research, the absorption coefficient and spectral slope were discussed. It was found that in summer of 2008 CDOM absorption coefficients at 440 nm [a(g) (440)], ranged from 0.20 m(-1) to 0.73 m(-1), while the coefficients in 2009 varied between 0.20 m(-1) and 0.77 m(-1). Statistics showed that the power function model fitted the best in the regression analysis of CDOM absorption spectral. The spectral slopes (S(g2)) of CDOM calculated by the power function model ranged from 5.10 to 7.90 in Summer of 2008 and from 2.95 to 6.11 in Spring of 2009. The highest absorption coefficients of two cruises appeared both in the south passage of the Yangtze Estuary. The absorption coefficient in surfer water was observed varied tremendously in the estuary and the offshore area. And the main reason is affected by the turbidity maximum zone. It is observed that the absorption coefficients of CDOM tended to a homogeneous distribution whilst the layers of water mixed tempestuously, but otherwise it always showed a conservative mixing behavior. Because of the frequent mixture, there is not assured correlativity between S(g2) and a(g) (440). In the offshore area of Yangtze Estuary, the effecting of local production cannot be negligent, which differed from the estuary area. Yet when the hydrological environment was relatively stable, the negative relationship between them was very clear. In conclusion, the optical properties and mixing behavior of CDOM had showed tremendous different characteristics from inside the estuary to outside the estuary because of the influence of complex physical, chemical and hydrology conditions.

  15. On the modelling of shallow turbidity flows

    Science.gov (United States)

    Liapidevskii, Valery Yu.; Dutykh, Denys; Gisclon, Marguerite

    2018-03-01

    In this study we investigate shallow turbidity density currents and underflows from mechanical point of view. We propose a simple hyperbolic model for such flows. On one hand, our model is based on very basic conservation principles. On the other hand, the turbulent nature of the flow is also taken into account through the energy dissipation mechanism. Moreover, the mixing with the pure water along with sediments entrainment and deposition processes are considered, which makes the problem dynamically interesting. One of the main advantages of our model is that it requires the specification of only two modeling parameters - the rate of turbulent dissipation and the rate of the pure water entrainment. Consequently, the resulting model turns out to be very simple and self-consistent. This model is validated against several experimental data and several special classes of solutions (such as travelling, self-similar and steady) are constructed. Unsteady simulations show that some special solutions are realized as asymptotic long time states of dynamic trajectories.

  16. Performance testing of coagulants to reduce stormwater runoff turbidity.

    Science.gov (United States)

    2014-05-01

    On December 1, 2009, the US Environmental Protection Agency (EPA) published a rule in the Federal : Register establishing non-numeric and, for the first time, numeric effluent limitation guidelines (ELGs). The : numeric ELGs included a turbidity limi...

  17. Improved Methods for Correlating Turbidity and Suspended Solids for Monitoring

    National Research Council Canada - National Science Library

    2000-01-01

    This technical note describes techniques normally used to measure turbidity and suspended solids in waters, how the two parameters relate to each other and to various environmental impacts, and why...

  18. 14C assimilation in a turbid man-made lake

    International Nuclear Information System (INIS)

    Stegmann, P.

    1978-01-01

    This article discusses the phytoplankton primary production in a turbid impoundment. The use of radioactive carbon to estimate the amount of plankton is described. The results are compared to those received from a clear-water environment

  19. Turbidity monitoring equipment and methodology evaluation at MDOT construction sites.

    Science.gov (United States)

    2014-12-01

    State Study 261 is a continuation of State study 225, "Turbidity Monitoring at Select : MDOT Construction Sites", which was successful in establishing baseline stream data : at several active construction sites. State Study 261 focused on the equipme...

  20. Observation technology for remote operation in contaminated turbid water

    International Nuclear Information System (INIS)

    Kishimoto, Manabu; Mitsui, Takashi

    2016-01-01

    Remote underwater work in contaminated tanks and pools is one of major decontamination and decommissioning works under high-dose radiation environment. Generally in this kind of work, visual information is limited due to turbid water caused by suspended sludge particles in the water and it makes remote underwater work difficult to be performed safely and efficiently. Therefore, some alternative observation methods to optical cameras have been required. In order to satisfy this requirement, the alternative observation technology which can obtain visual information in contaminated turbid water has been developed since 2014. It is a technology using an acoustic imaging system in a designated airtight container. It provides the visual information in real time regardless of turbidity without significant contamination of any parts of the system. This paper will present development details of this innovative observation technology and its effectiveness to various remote works in contaminated turbid water. (author)

  1. Dynamic imaging through turbid media based on digital holography.

    Science.gov (United States)

    Li, Shiping; Zhong, Jingang

    2014-03-01

    Imaging through turbid media using visible or IR light instead of harmful x ray is still a challenging problem, especially in dynamic imaging. A method of dynamic imaging through turbid media using digital holography is presented. In order to match the coherence length between the dynamic object wave and the reference wave, a cw laser is used. To solve the problem of difficult focusing in imaging through turbid media, an autofocus technology is applied. To further enhance the image contrast, a spatial filtering technique is used. A description of digital holography and experiments of imaging the objects hidden in turbid media are presented. The experimental result shows that dynamic images of the objects can be achieved by the use of digital holography.

  2. Bacterioplankton Community Dynamics and Nutrient Availability in a Shallow Well Mixed Estuary of the Northern Gulf of Mexico.

    Science.gov (United States)

    Hoch, M. P.

    2016-02-01

    Sabine Lake Estuary is a shallow, well mixed, tidal lagoon of the Northern Gulf of Mexico. This study defines the bacterioplankton community composition and factors that may influence its variation in Sabine Lake Estuary. Twenty physicochemical parameters, phytoplankton photopigments, and bacterial 16SrDNA sequences were analyzed seasonally from twelve sites ranging from the inflows of Sabine and Neches Rivers to the Sabine Pass outflow. Photopigments were used to estimate phytoplankton groups via CHEMTAX, and bacterioplankton 16SrDNA sequences of 97% similarity were quantified and taxa identified. Nutrient availability experiments were conducted on bacterioplankton. Notable seasonal differences were seen in six of the ten most common (>3% of total sequences) classes of bacterioplankton. Canonical correspondence analysis (CCA) of common classes was used to explore physiochemical parameters and phytoplankton groups influencing variation in the bacterioplankton. Alphaproteobacteria were most abundant throughout the year. Opitutae, Actinobacteria, Sphingobacteria, and Beta-proteobacteria were strongly influenced by conditions with higher TDN, DOC, turbidity, and Chlorophytes during winter when high river discharges reduced salinity. Planctomycetacia were most prevalent during spring and coincide with predominance of Cryptophytes. In summer and fall the aforementioned classes decline, and there is an increase in Synechococcophycideae. Nitrogen was least available to bacterioplankton during summer and fall. Clearer, warmer and more saline conditions with lower DOC reflect tidal movement of seawater into the estuary when river discharges were low, conditions favorable for Synechococcophycidea. Seasonal fluctuations in physicochemical conditions and certain phytoplankton groups influence the variation in the bacterioplankton community in Sabine Lake Estuary.

  3. Distribution, vertical position and ecological implications of shallow gas in Bahía Blanca estuary (Argentina)

    Science.gov (United States)

    Bravo, M. E.; Aliotta, S.; Fiori, S.; Ginsberg, S.

    2018-03-01

    There has been a growing interest in the study of shallow gas due its importance in relation to the marine environment, climate change and human activities. In Bahía Blanca estuary, Argentina, shallow gas has a wide distribution. Acoustic turbidity and blanking are the main seismic evidence for the presence of shallow gas in the estuary. The former prevails in the inner sector of the estuary where gas is either near or in contact with the seabed. Gas deposits are generally associated with paleochannels corresponding to the Holocene paleodeltaic environment. Distribution studies of shallow gas in this estuary are necessary because its presence implies not only a geological risk for harbor activities but also because it may have noxious effects on the marine ecosystem, mainly on benthic communities. The comparison of benthic communities at a gas site (GS) with those at a control site (CS) indicated that gas could generate impoverishment in terms of individuals' abundance (GS: N = 357; CS: N = 724). Also, diversity indices showed great differences in the community structure at each site. This indicates that methane gas may act as a natural disturbance agent in estuarine ecosystems. The presence of gas in seabed sediments must therefore be taken into account when distribution studies are conducted of estuarine benthic communities.

  4. Sources and distribution of aromatic hydrocarbons in a tropical marine protected area estuary under influence of sugarcane cultivation.

    Science.gov (United States)

    Arruda-Santos, Roxanny Helen de; Schettini, Carlos Augusto França; Yogui, Gilvan Takeshi; Maciel, Daniele Claudino; Zanardi-Lamardo, Eliete

    2018-05-15

    Goiana estuary is a well preserved marine protected area (MPA) located on the northeastern coast of Brazil. Despite its current state, human activities in the watershed represent a potential threat to long term local preservation. Dissolved/dispersed aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were investigated in water and sediments across the estuarine salt gradient. Concentration of aromatic hydrocarbons was low in all samples. According to results, aromatic hydrocarbons are associated to suspended particulate matter (SPM) carried to the estuary by river waters. An estuarine turbidity maximum (ETM) was identified in the upper estuary, indicating that both sediments and contaminants are trapped prior to an occasional export to the adjacent sea. PAHs distribution in sediments were associated with organic matter and mud content. Diagnostic ratios indicated pyrolytic processes as the main local source of PAHs that are probably associated with sugarcane burning and combustion engines. Low PAH concentrations probably do not cause adverse biological effects to the local biota although their presence indicate anthropogenic contamination and pressure on the Goiana estuary MPA. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Establishment of turbidity forecasting model and early-warning system for source water turbidity management using back-propagation artificial neural network algorithm and probability analysis.

    Science.gov (United States)

    Yang, Tsung-Ming; Fan, Shu-Kai; Fan, Chihhao; Hsu, Nien-Sheng

    2014-08-01

    The purpose of this study is to establish a turbidity forecasting model as well as an early-warning system for turbidity management using rainfall records as the input variables. The Taipei Water Source Domain was employed as the study area, and ANOVA analysis showed that the accumulative rainfall records of 1-day Ping-lin, 2-day Ping-lin, 2-day Fei-tsui, 2-day Shi-san-gu, 2-day Tai-pin and 2-day Tong-hou were the six most significant parameters for downstream turbidity development. The artificial neural network model was developed and proven capable of predicting the turbidity concentration in the investigated catchment downstream area. The observed and model-calculated turbidity data were applied to developing the turbidity early-warning system. Using a previously determined turbidity as the threshold, the rainfall criterion, above which the downstream turbidity would possibly exceed this respective threshold turbidity, for the investigated rain gauge stations was determined. An exemplary illustration demonstrated the effectiveness of the proposed turbidity early-warning system as a precautionary alarm of possible significant increase of downstream turbidity. This study is the first report of the establishment of the turbidity early-warning system. Hopefully, this system can be applied to source water turbidity forecasting during storm events and provide a useful reference for subsequent adjustment of drinking water treatment operation.

  6. Effects of turbidity, sediment, and polyacrylamide on native freshwater mussels

    Science.gov (United States)

    Buczek, Sean B.; Cope, W. Gregory; McLaughlin, Richard A.; Kwak, Thomas J.

    2018-01-01

    Turbidity is a ubiquitous pollutant adversely affecting water quality and aquatic life in waterways globally. Anionic polyacrylamide (PAM) is widely used as an effective chemical flocculent to reduce suspended sediment (SS) and turbidity. However, no information exists on the toxicity of PAM‐flocculated sediments to imperiled, but ecologically important, freshwater mussels (Unionidae). Thus, we conducted acute (96 h) and chronic (24 day) laboratory tests with juvenile fatmucket (Lampsilis siliquoidea) and three exposure conditions (nonflocculated settled sediment, SS, and PAM‐flocculated settled sediment) over a range of turbidity levels (50, 250, 1,250, and 3,500 nephelometric turbidity units). Survival and sublethal endpoints of protein oxidation, adenosine triphosphate (ATP) production, and protein concentration were used as measures of toxicity. We found no effect of turbidity levels or exposure condition on mussel survival in acute or chronic tests. However, we found significant reductions in protein concentration, ATP production, and oxidized proteins in mussels acutely exposed to the SS condition, which required water movement to maintain sediment in suspension, indicating responses that are symptoms of physiological stress. Our results suggest anionic PAM applied to reduce SS may minimize adverse effects of short‐term turbidity exposure on juvenile freshwater mussels without eliciting additional lethal or sublethal toxicity.

  7. Optical imaging of objects in turbid medium with ultrashort pulses

    Science.gov (United States)

    Wang, Chih-Yu; Sun, Chia-Wei; Yang, Chih Chung; Kiang, Yean-Woei; Lin, Chii-Wann

    2000-07-01

    Photons are seriously scattered when entering turbid medium; this the images of objects hidden in turbid medium can not be obtained by just collecting the transmitted photons. Early-arriving photons, which are also called ballistic or snake protons, are much less scattered when passing through turbid medium, and contains more image information than the late-arriving ones. Therefore, objects embedded in turbid medium can be imaged by gathering the ballistic and snake photons. In the present research we try to recover images of objects in turbid medium by simultaneously time-gate and polarization-gate to obtain the snake photons. An Argon-pumped Ti-Sapphire laser with 100fs pulses was employed as a light source. A streak camera with a 2ps temporal resolution was used to extract the ballistic and snake photons. Two pieces of lean swine meat, measured 4mmX3mm and 5xxX4mm, respectively, were placed in a 10cmX10cmX3cm acrylic tank, which was full of diluted milk. A pair of polarizer and an analyzer was used to extract the light that keeps polarization unchanged. The combination of time gating and polarization gating resulted in good images of objects hidden in turbid medium.

  8. Oyster Aquaculture Site Selection Using Landsat 8-Derived Sea Surface Temperature, Turbidity, and Chlorophyll a

    Directory of Open Access Journals (Sweden)

    Jordan Snyder

    2017-06-01

    Full Text Available Remote sensing data is useful for selection of aquaculture sites because it can provide water-quality products mapped over large regions at low cost to users. However, the spatial resolution of most ocean color satellites is too coarse to provide usable data within many estuaries. The Landsat 8 satellite, launched February 11, 2013, has both the spatial resolution and the necessary signal to noise ratio to provide temperature, as well as ocean color derived products along complex coastlines. The state of Maine (USA has an abundance of estuarine indentations (~3,500 miles of tidal shoreline within 220 miles of coast, and an expanding aquaculture industry, which makes it a prime case-study for using Landsat 8 data to provide products suitable for aquaculture site selection. We collected the Landsat 8 scenes over coastal Maine, flagged clouds, atmospherically corrected the top-of-the-atmosphere radiances, and derived time varying fields (repeat time of Landsat 8 is 16 days of temperature (100 m resolution, turbidity (30 m resolution, and chlorophyll a (30 m resolution. We validated the remote-sensing-based products at several in situ locations along the Maine coast where monitoring buoys and programs are in place. Initial analysis of the validated fields revealed promising new areas for oyster aquaculture. The approach used is applicable to other coastal regions and the data collected to date show potential for other applications in marine coastal environments, including water quality monitoring and ecosystem management.

  9. Carbon dioxide emissions from Indian monsoonal estuaries

    Science.gov (United States)

    Sarma Vedula, VSS

    2012-07-01

    The oceans act as a net sink for atmospheric CO2, however, the role of coastal bodies on global CO2 fluxes remains unclear due to lack of data. The estimated absorption of CO2 from the continental shelves, with limited data, is 0.22 to 1.0 PgC/y, and of CO2 emission by estuaries to the atmosphere is 0.27 PgC/y. The estimates from the estuaries suffer from large uncertainties due to large variability and lack of systematic data collection. It is especially true for Southeast Asian estuaries as the biogeochemical cycling of material are different due to high atmospheric temperature, seasonality driven by monsoons, seasonal discharge etc. In order to quantify CO2 emissions from the Indian estuaries, samples were collected at 27 estuaries all along the Indian coast during discharge wet and dry periods. The emissions of CO2 to the atmosphere from Indian estuaries were 4-5 times higher during wet than dry period. The pCO2 ranged between ~300 and 18492 microatm which were within the range of world estuaries. The mean pCO2 and particulate organic carbon (POC) showed positive relation with rate of discharge suggesting availability of high quantities of organic matter that led to enhanced microbial decomposition. The annual CO2 fluxes from the Indian estuaries, together with dry period data available in the literature, amounts to 1.92 TgC which is >10 times less than that from the European estuaries. The low CO2 fluxes from the Indian estuaries are attributed to low flushing rates and less human settlements along the banks of the Indian estuaries.

  10. Hydro- and sediment dynamics in the estuary zone of the Mekong Delta: case study Dinh An estuary.

    Science.gov (United States)

    Tran, Anh Tuan; Thoss, Heiko; Gratiot, Nicolas; Dussouillez, Philippe; Brunier, Guillaume; Apel, Heiko

    2017-04-01

    The Mekong River is the tenth largest river in the world, covers an area of 795,000 km2, 4400km in length, the main river flows over the six countries including: China, Myanmar, Thailand, Laos, Cambodia and Vietnam. Its water discharge is 470 km3year-1 and the sediment discharge is estimated about 160 million ton year-1. The sediment transported by the Mekong River is the key factor in the formation and development of the delta. It is a vital factor for the stability of the coastline and river banks. Furthermore it compensates land subsidence by floodplain deposition, and is the major natural nutrient source for agriculture and aquaculture. However, only a few studies were conducted to characterize and quantify sediment properties and process in the Delta. Also the morphodynamic processes were hardly studied systematically. Hence, this study targets to fill some important and open knowledge gaps with extensive field works that provide important information about the sediment properties and hydrodynamic processes in different seasons Firstly three field survey campaigns are carried out along a 30 km section of the Bassac River from the beginning of Cu Lao Dung Island to Dinh An estuary in 2015 and 2016. During the field campaign, the movement of the salt wedge and the turbidity were monitored by vertical profiles along the river, as well as discharge measurements by ADCP were carried out at three cross sections continuously for 72 hours. The extension of the salt wedge in the river was determined, along with mixing processes. The movement and dynamics observed under different flow conditions indicate that sediment was pumped during low flow upwards the river, while during high flow net transport towards the sea dominated. Also a distinct difference in the sediment properties in the different seasons was observed, with a general tendency towards a higher proportion of coarser particles in the high flow season. These quantitative results give insights into the

  11. Trapping of sediment in tidal estuaries

    NARCIS (Netherlands)

    Chernetsky, A.

    2012-01-01

    An estuary is an ideal habitat for various aquatic species. At the same time, estuaries and adjacent rivers are used as fast navigation routes between the coastal and inland territories. The fast industrial development and the subsequent growth of cities and trade have led to large-scale

  12. Microplastic in three urban estuaries, China

    International Nuclear Information System (INIS)

    Zhao, Shiye; Zhu, Lixin; Li, Daoji

    2015-01-01

    Estuarine Microplastics (MPs) are limited to know globally. By filtering subsurface water through 330 μm nets, MPs in Jiaojiang, Oujiang Estuaries were quantified, as well as that in Minjiang Estuary responding to Typhoon Soulik. Polymer matrix was analyzed by Raman spectroscopy. MP (<5 mm) comprised more than 90% of total number plastics. The highest MPs density was found in Minjiang, following Jiaojiang and Oujiang. Fibers and granules were the primary shapes, with no pellets found. Colored MPs were the majority. The concentrations of suspended microplastics determine their bioavailability to low trophic organisms, and then possibly promoting the transfer of microplastic to higher trophic levels. Polypropylene and polyethylene were the prevalent types of MPs analyzed. Economic structures in urban estuaries influenced on MPs contamination levels. Typhoon didn't influence the suspended MP densities significantly. Our results provide basic information for better understanding suspended microplastics within urban estuaries and for managerial actions. - Highlights: • Suspended microplastic were investigated within three densely populated/developed urban estuaries, China. • Economical structures may contribute to the abundances of microplastic particles within the studied estuaries. • Typhoon Soulik didn't influence microplastic densities in the water column of Minjiang Estuary. • Microplastics (<5 mm in diameter) dominated more than 90% of the total plastic by number. - Suspended microplastics (MPs) levels were quantified within three urban estuaries, China. MPs densities were consistent with the urban economical structure, and that in Minjiang were unaffected by Typhoon.

  13. The Mntafufu and Mzamba River estuaries

    African Journals Online (AJOL)

    1989-03-14

    Mar 14, 1989 ... A survey of the fish fauna of Transkei estuaries. Part Four: The Mntafufu and Mzamba River estuaries. E.E. Plumstead • and J.F. Prinsloo. Department of Zoology, University of Transkei, Private Bag X1, Unitra, Umtata, Republic of Transkei. H.J. Schoonbee. Department of Zoology, Rand Afrikaans University, ...

  14. The Effect of Low Energy Turbulence in Estuary Margins on Fine Sediment Settling

    Science.gov (United States)

    Allen, R. M.; MacVean, L. J.; Tse, I.; Mazzaro, L. J.; Stacey, M. T.; Variano, E. A.

    2014-12-01

    Sediment dynamics in estuaries and near shore regions control the growth or erosion of the bed and fringing wetlands, determine the spread of sediment-associated contaminants, and limit the light availability for primary productivity through turbidity. In estuaries such as San Francisco Bay, this sediment is often cohesive, and can flocculate. Changes to the composition of the sediment and waters, the suspended sediment concentration, and the turbulence can all affect the flocculation of suspended sediment. In turn, flocculation controls the particle diameter, settling velocity, density, and particle inertia. These sediment properties drive the turbulent diffusivity, which balances with the settling velocity to impact the vertical distribution of sediment in the water column. The vertical profile strongly affects how sediment is transported through the estuary by lateral flow. Turbulence may also impact settling velocity in non-cohesive particles. In turbulence, dense particles may get trapped in convergent flow regions, thus particles are more likely to get swept along the downward side of a turbulent eddy than the upward side, resulting in enhanced settling velocities. We isolated the impacts of turbulence level, particle size and type, and suspended sediment concentration on particle settling velocities using uniform grain size particles in homogeneous isotropic turbulence. Controlling the turbulence in a well-defined turbulence tank, we used Two Acoustic Doppler Velocimeters, separated vertically, to measure turbulent velocities (w') and suspended sediment concentrations (C), which yield condition dependent settling velocities (ws), via equation 1. Lab characterization of particle settling velocities help to validate the method for measuring settling velocities in the field, and will serve as a foundation for an extensive field experiment in San Francisco Bay. Characterizing the velocity enhancement relative to the Stokes number, the Rouse number, and the

  15. Natural 222Rn and 220Rn indicate the impact of the Water–Sediment Regulation Scheme (WSRS) on submarine groundwater discharge in the Yellow River estuary, China

    International Nuclear Information System (INIS)

    Xu, Bochao; Xia, Dong; Burnett, William C.; Dimova, Natasha T.; Wang, Houjie; Zhang, Longjun; Gao, Maosheng; Jiang, Xueyan; Yu, Zhigang

    2014-01-01

    Highlights: • 220 Rn and 222 Rn were combined to locate intensive SGD sites. • Influence of WSRS to SGD was found for the first time. • SGD was a dominant nutrient pathway in the Yellow River estuary. - Abstract: Submarine groundwater discharge (SGD) in estuaries brings important influences to coastal ecosystems. In this study, we observed significant SGD in the Yellow River estuary, including a fresh component, during the Water–Sediment Regulation Scheme (WSRS) period. We used the 222 Rn and 220 Rn isotope pair to locate sites of significant SGD within the study area. Three apparent SGD locations were found during a non-WSRS period, one of which became much more pronounced, according to the remarkably elevated radon levels, during the WSRS. Increased river discharge (from 245 m 3 s −1 to 3560 m 3 s −1 ) and the elevated river water level (from 11 m to 13 m) during the WSRS led to a higher hydraulic head, enhancing groundwater discharge in the estuary. Our results suggest that high river discharge (>3000 m 3 s −1 ) might be necessary for elevated fresh submarine groundwater discharging (FSGD). Vertical profiles of salinity, DO and turbidity anomalies along the benthic boundary layer also indicated significant FSGD in the estuary during the WSRS. Nutrient concentrations had positive correlations with 222 Rn during a 24-h observation, which indicates that SGD is a dominant nutrient pathway in this area

  16. Climate-change refugia: shading reef corals by turbidity.

    Science.gov (United States)

    Cacciapaglia, Chris; van Woesik, Robert

    2016-03-01

    Coral reefs have recently experienced an unprecedented decline as the world's oceans continue to warm. Yet global climate models reveal a heterogeneously warming ocean, which has initiated a search for refuges, where corals may survive in the near future. We hypothesized that some turbid nearshore environments may act as climate-change refuges, shading corals from the harmful interaction between high sea-surface temperatures and high irradiance. We took a hierarchical Bayesian approach to determine the expected distribution of 12 coral species in the Indian and Pacific Oceans, between the latitudes 37°N and 37°S, under representative concentration pathway 8.5 (W m(-2) ) by 2100. The turbid nearshore refuges identified in this study were located between latitudes 20-30°N and 15-25°S, where there was a strong coupling between turbidity and tidal fluctuations. Our model predicts that turbidity will mitigate high temperature bleaching for 9% of shallow reef habitat (to 30 m depth) - habitat that was previously considered inhospitable under ocean warming. Our model also predicted that turbidity will protect some coral species more than others from climate-change-associated thermal stress. We also identified locations where consistently high turbidity will likely reduce irradiance to turbid nearshore refuges identified in this study, particularly in the northwestern Hawaiian Islands, the northern Philippines, the Ryukyu Islands (Japan), eastern Vietnam, western and eastern Australia, New Caledonia, the northern Red Sea, and the Arabian Gulf, should become part of a judicious global strategy for reef-coral persistence under climate change. © 2015 John Wiley & Sons Ltd.

  17. Hyperspectral sensing for turbid water quality monitoring in freshwater rivers: Empirical relationship between reflectance and turbidity and total solids.

    Science.gov (United States)

    Wu, Jiunn-Lin; Ho, Chung-Ru; Huang, Chia-Ching; Srivastav, Arun Lal; Tzeng, Jing-Hua; Lin, Yao-Tung

    2014-11-28

    Total suspended solid (TSS) is an important water quality parameter. This study was conducted to test the feasibility of the band combination of hyperspectral sensing for inland turbid water monitoring in Taiwan. The field spectral reflectance in the Wu river basin of Taiwan was measured with a spectroradiometer; the water samples were collected from the different sites of the Wu river basin and some water quality parameters were analyzed on the sites (in situ) as well as brought to the laboratory for further analysis. To obtain the data set for this study, 160 in situ sample observations were carried out during campaigns from August to December, 2005. The water quality results were correlated with the reflectivity to determine the spectral characteristics and their relationship with turbidity and TSS. Furthermore, multiple-regression (MR) and artificial neural network (ANN) were used to model the transformation function between TSS concentration and turbidity levels of stream water, and the radiance measured by the spectroradiometer. The value of the turbidity and TSS correlation coefficient was 0.766, which implies that turbidity is significantly related to TSS in the Wu river basin. The results indicated that TSS and turbidity are positively correlated in a significant way across the entire spectrum, when TSS concentration and turbidity levels were under 800 mg·L(-1) and 600 NTU, respectively. Optimal wavelengths for the measurements of TSS and turbidity are found in the 700 and 900 nm range, respectively. Based on the results, better accuracy was obtained only when the ranges of turbidity and TSS concentration were less than 800 mg·L(-1) and less than 600 NTU, respectively and used rather than using whole dataset (R(2) = 0.93 versus 0.88 for turbidity and R(2) = 0.83 versus 0.58 for TSS). On the other hand, the ANN approach can improve the TSS retrieval using MR. The accuracy of TSS estimation applying ANN (R(2) = 0.66) was better than with the MR approach (R

  18. Hyperspectral Sensing for Turbid Water Quality Monitoring in Freshwater Rivers: Empirical Relationship between Reflectance and Turbidity and Total Solids

    Directory of Open Access Journals (Sweden)

    Jiunn-Lin Wu

    2014-11-01

    Full Text Available Total suspended solid (TSS is an important water quality parameter. This study was conducted to test the feasibility of the band combination of hyperspectral sensing for inland turbid water monitoring in Taiwan. The field spectral reflectance in the Wu river basin of Taiwan was measured with a spectroradiometer; the water samples were collected from the different sites of the Wu river basin and some water quality parameters were analyzed on the sites (in situ as well as brought to the laboratory for further analysis. To obtain the data set for this study, 160 in situ sample observations were carried out during campaigns from August to December, 2005. The water quality results were correlated with the reflectivity to determine the spectral characteristics and their relationship with turbidity and TSS. Furthermore, multiple-regression (MR and artificial neural network (ANN were used to model the transformation function between TSS concentration and turbidity levels of stream water, and the radiance measured by the spectroradiometer. The value of the turbidity and TSS correlation coefficient was 0.766, which implies that turbidity is significantly related to TSS in the Wu river basin. The results indicated that TSS and turbidity are positively correlated in a significant way across the entire spectrum, when TSS concentration and turbidity levels were under 800 mg·L−1 and 600 NTU, respectively. Optimal wavelengths for the measurements of TSS and turbidity are found in the 700 and 900 nm range, respectively. Based on the results, better accuracy was obtained only when the ranges of turbidity and TSS concentration were less than 800 mg·L−1 and less than 600 NTU, respectively and used rather than using whole dataset (R2 = 0.93 versus 0.88 for turbidity and R2 = 0.83 versus 0.58 for TSS. On the other hand, the ANN approach can improve the TSS retrieval using MR. The accuracy of TSS estimation applying ANN (R2 = 0.66 was better than with the MR

  19. Monitoring suspended sediments and turbidity in Sahelian basins

    Science.gov (United States)

    Robert, Elodie; Grippa, Manuela; Kergoat, Laurent; Martinez, Jean-Michel; Pinet, Sylvain; Nogmana, Soumaguel

    2017-04-01

    Suspended matter can carry viruses and bacteria that are pathogenic to humans and can foster their development. Therefore, turbidity can be considered a vector of microbiological contaminants, which cause diarrheal diseases, and it can be used as a proxy for fecal bacteria. Few studies have focused on water turbidity in rural Africa, where many cases of intestinal parasitic infections are due to the consumption of unsafe water from ponds, reservoirs, lakes and rivers. Diarrheal diseases are indeed the second cause of infant mortality in sub-Saharan Africa. Furthermore, in this region, environment survey is minimal or inexistent. Monitoring water turbidity therefore represents a challenge for health improvement. Turbidity refers to the optical properties of water and it is well suited to monitoring by remote sensing. Because it varies in space and time and because the small water bodies (Africa challenges the use of remote sensing and questions the methods developed for less turbid waters. In addition, high aerosol loadings (mineral dust and biomass burning) may be detrimental to turbidity retrieval in this region because of inaccurate atmospheric corrections. We propose a method to monitor water quality of Sahelian ponds, lakes and rivers using in-situ and remote sensing data, which is tested at different sites for which in-situ water turbidity and suspended sediments concentration (SSSC) measurements are acquired. Water sample are routinely collected at two sites within the AMMA-CATCH observatory part of the Réseau de Bassin Versants (RBV) French network: the Agoufou pond in northern Mali (starting September 2014), and the Niger River at Niamey in Niger (starting June 2015). These data are used to evaluate different indexes to derive water turbidity from the reflectance in the visible and infrared bands of high resolution optical sensors (LANDSAT, SENTINEL2). The temporal evolution of the turbidity of ponds, lakes and rivers is well captured at the seasonal and

  20. Impact of boat generated waves over an estuarine intertidal zone of the Seine estuary (France)

    Science.gov (United States)

    Deloffre, Julien; Lafite, Robert

    2015-04-01

    Water movements in macrotidal estuaries are controlled by the tidal regime modulated seasonally by the fluvial discharge. Wind effect on hydrodynamics and sediment transport is also reported at the mouth. Besides estuaries are frequently man altered our knowledge on the human impact on hydrodynamics and sediment transport is less extended. As an example on the Seine estuary (France) port authorities have put emphasis on facilitating economic exchanges by means of embankment building and increased dredging activity over the last century. These developments led to secure sea vessel traffic in the Seine estuary but they also resulted in a change of estuarine hydrodynamics and sediment transport features. Consequences of boat generated waves are varied: increased water turbidity and sediment transfer, release of nutrient and contaminants in the water column, harmful to users, ecosystems and infrastructures generating important maintenance spending. The aim of this study is to analyse the impact of boat generated waves on sediment transport over an intertidal area. The studied site is located on the left bank in the fluvial part of the Seine estuary. On this site the maximum tidal range ranges between 1.25 and 3.5m respectively during neap and spring tide. The sampling strategy is based on continuous ADV acquisition at 4Hz coupled with turbidimeter and altimeter measurements (1 measurement every minute) in order to decipher sediment dynamics during one year. Our results indicate that sediment dynamics are controlled by river flow while medium term scale evolution is dependent on tidal range and short term dynamics on sea-vessels waves. 64% of boat passages generated significant sediment reworking (from few mm.min-1 to 3cm.min-1). This reworking rate is mainly controlled by two parameters: (i) water height on the site and (ii) vessels characteristics; in particular the distance between seabed and keel that generate a Bernoulli wave (with maximum amplitude of 0.6m

  1. Spatial and temporal distribution of metals in suspended particulate matter of the Kali estuary, India

    Science.gov (United States)

    Suja, S.; Kessarkar, Pratima M.; Fernandes, Lina L.; Kurian, Siby; Tomer, Arti

    2017-09-01

    Major (Al, Fe, Mn, Ti, Mg) and trace (Cu, Zn, Pb, Cr, Ni, Co, Zr, Rb, Sr, Ba, Li, Be, Sc, V, Ga, Nb, Mo, Sn, Sb, Cs, Hf, Ta, Bi, Th, U) elements and particulate organic carbon (POC) concentrations in surface suspended particulate matter (SPM) of the Kali estuary, (central west coast of India) were studied during the pre-monsoon, monsoon and post monsoon seasons to infer estuarine processes, source of SPM and Geoaccumulation Index (Igeo) assigned pollutionIgeo levels. Distribution of SPM indicates the presence of the estuarine turbidity maximum (ETM) during all three seasons near the river mouth and a second ETM during the post monsoon time in the upstream associated with salinities gradient. The SPM during the monsoon is finer grained (avg. 53 μm), characterized by uniformly low normalized elemental concentration, whereas the post and pre monsoon are characterized by high normalized elemental concentration with coarser grain size (avg. 202 μm and 173 μm respectively) with highest ratios in the upstream estuary. The elemental composition and principal component analysis for the upstream estuary SPM support more contribution from the upstream catchment area rocks during the monsoon season; there is additional contribution from the downstream catchment area during the pre and post monsoon period due to the tidal effect. The Kali estuarine SPM has higher Al, Fe, Mn, Ti, Mg, Ni, Co, Ba, Li and V with respect to Average World River SPM (WRSPM). Igeo values for the SPM indicate Kali Estuary to be severely enriched with Mn and moderately enriched with Cu, Zn, Ni, Co, U and Mo in the upstream estuary during pre and post monsoon seasons. Seasonal changes in salinity gradient (reduced freshwater flow due to closing of the dam gates), reduced velocity at meandering region of the estuary and POC of 1.6-2.3% resulted in co-precipitation of trace elements that were further fortified by flocculation and coagulation throughout the water column resulting in metal trapping in the

  2. [Exploration of the Essence of "Endogenous Turbidity" in Chinese Medicine].

    Science.gov (United States)

    Fan, Xin-rong; Tang, Nong; Ji, Yun-xi; Zhang, Yao-zhong; Jiang, Li; Huang, Gui-hua; Xie, Sheng; Li, Liu-mei; Song, Chun-hui; Ling, Jiang-hong

    2015-08-01

    The essence of endogenous turbidity in Chinese medicine (CM) is different from cream, fat, phlegm, retention, damp, toxicity, and stasis. Along with the development of modern scientific technologies and biology, researches on the essence of endogenous turbidity should keep pace with the time. Its material bases should be defined and new connotation endowed at the microscopic level. The essence of turbidity lies in abnormal functions of zang-fu organs. Sugar, fat, protein, and other nutrient substances cannot be properly decomposed, but into semi-finished products or intermediate metabolites. They are inactive and cannot participate in normal material syntheses and decomposition. They cannot be transformed to energy metabolism, but also cannot be synthesized as executive functioning of active proteins. If they cannot be degraded by autophagy-lysosome or ubiquitin-prosome into glucose, fatty acids, amino acids, and other basic nutrients to be used again, they will accumulate inside the human body and become endogenous turbidity. Therefore, endogenous turbidity is different from final metabolites such as urea, carbon dioxide, etc., which can transform vital qi. How to improve the function of zang-fu organs, enhance its degradation by autophagy-lysosome or ubiquitin-prosome is of great significance in normal operating of zang-fu organs and preventing the emergence and progress of related diseases.

  3. Short-term forecasting of turbidity in trunk main networks.

    Science.gov (United States)

    Meyers, Gregory; Kapelan, Zoran; Keedwell, Edward

    2017-11-01

    Water discolouration is an increasingly important and expensive issue due to rising customer expectations, tighter regulatory demands and ageing Water Distribution Systems (WDSs) in the UK and abroad. This paper presents a new turbidity forecasting methodology capable of aiding operational staff and enabling proactive management strategies. The turbidity forecasting methodology developed here is completely data-driven and does not require hydraulic or water quality network model that is expensive to build and maintain. The methodology is tested and verified on a real trunk main network with observed turbidity measurement data. Results obtained show that the methodology can detect if discolouration material is mobilised, estimate if sufficient turbidity will be generated to exceed a preselected threshold and approximate how long the material will take to reach the downstream meter. Classification based forecasts of turbidity can be reliably made up to 5 h ahead although at the expense of increased false alarm rates. The methodology presented here could be used as an early warning system that can enable a multitude of cost beneficial proactive management strategies to be implemented as an alternative to expensive trunk mains cleaning programs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. High Turbidity Solis Clear Sky Model: Development and Validation

    Directory of Open Access Journals (Sweden)

    Pierre Ineichen

    2018-03-01

    Full Text Available The Solis clear sky model is a spectral scheme based on radiative transfer calculations and the Lambert–Beer relation. Its broadband version is a simplified fast analytical version; it is limited to broadband aerosol optical depths lower than 0.45, which is a weakness when applied in countries with very high turbidity such as China or India. In order to extend the use of the original simplified version of the model for high turbidity values, we developed a new version of the broadband Solis model based on radiative transfer calculations, valid for turbidity values up to 7, for the three components, global, beam, and diffuse, and for the four aerosol types defined by Shettle and Fenn. A validation of low turbidity data acquired in Geneva shows slightly better results than the previous version. On data acquired at sites presenting higher turbidity data, the bias stays within ±4% for the beam and the global irradiances, and the standard deviation around 5% for clean and stable condition data and around 12% for questionable data and variable sky conditions.

  5. ANALYSE DE LA TENDANCE DE L’ABONDANCE DE L’ALOSE ALOSA ALOSA EN GIRONDE À PARTIR DE L’ESTIMATION D’INDICATEURS HALIEUTIQUES SUR LA PÉRIODE 1977-1998.

    Directory of Open Access Journals (Sweden)

    CASTELNAUD G.

    2001-07-01

    Full Text Available Au cours des deux dernières décennies, la population d’alose vraie Alosa alosa a été considérée par différents auteurs en diminution, même vouée à la disparition, puis en progression, ou se maintenant à un haut niveau d’effectif dans le bassin de la Garonne. L’objectif de ce travail est de produire les indicateurs halieutiques les plus aptes à rendre compte de la tendance de l’abondance de l’alose vraie en Gironde sur la période 1977-1998. Ces indicateurs saisonniers sont d’une part la CPUE et d’autre part la production totale et l’effort total qui doivent permettre d’expliciter et de conforter le diagnostic sur la tendance de l’abondance. L’échantillon non-aléatoire de données de capture et d’effort provenant d’un réseau de pêcheurs coopératifs, a été stratifié selon les métiers de pêche, les zones de pêche et les quinzaines de pêche. L’estimation des captures totales et des efforts totaux fait appel à la théorie classique de l’échantillonnage avec stratification. Afin d’obtenir un indice qui reflète le mieux possible les variations d’abondance inter-annuelles et qui limite l’incidence des variations de capturabilité dans l’espace et dans le temps, nous avons utilisé la théorie du Modèle Linéaire Général pour construire un modèle log-linéaire qui donne le même poids aux zones et aux quinzaines de pêche sur toute la période d’étude. Le modèle explique la CPUE comme l’addition des effets principaux des facteurs zone, année et quinzaine. Une évolution en paliers des indices d’abondance est testée grâce à un modèle à erreur auto-régressive. On constate que les paliers sont très hautement significatifs pour la Gironde et les trois compartiments Estuaire, Garonne, Dordogne. L’analyse des trois indicateurs halieutique et la confrontation de leur évolution nous amènent à conclure que l’abondance d’A. alosa est au minimum stable en Gironde et qu

  6. Estimating sediment and caesium-137 fluxes in the Ribble Estuary through time-series airborne remote sensing

    International Nuclear Information System (INIS)

    Wakefield, R.; Tyler, A.N.; McDonald, P.; Atkin, P.A.; Gleizon, P.; Gilvear, D.

    2011-01-01

    High spatial and temporal resolution airborne imagery were acquired for the Ribble Estuary, North West England in 1997 and 2003, to assess the application of time-series airborne remote sensing to quantify total suspended sediment and radionuclide fluxes during a flood and ebb tide sequence. Concomitant measurements of suspended particulate matter (SPM) and water column turbidity were obtained during the time-series image acquisition for the flood and ebb tide sequence on the 17th July 2003 to verify the assumption of a vertically well mixed estuary and thus justifying the vertical extrapolation of spatially integrated estimate of surface SPM. The 137 Cs activity concentrations were calculated from a relatively stable relationship between SPM and 137 Cs for the Ribble Estuary. Total estuary wide budgets of sediment and 137 Cs were obtained by combining the image-derived estimates of surface SPM and 137 Cs with estimates of water volume from a two-dimensional hydrodynamic model (VERSE) developed for the Ribble Estuary. These indicate that around 10,000 tonnes of sediment and 2.72 GBq of 137 Cs were deposited over the tidal sequence monitored in July 2003. This compared favourably with bed height elevation change estimated from field work. An uncertainty analysis on the total sediment and 137 Cs flux yielded a total budget of the order of 40% on the final estimate. The results represent a novel approach to providing a spatially integrated estimate of the total net sediment and radionuclide flux in an intertidal environment over a flood and ebb tide sequence. - Research highlights: → This paper provides a rare insight into the next flux of sediment and associated radionuclide loading into an estuary over and ebb and flood tide sequence. → The paper uses high temporal resolution airborne imagery coupled with concomitant sampling to convert total suspended sediment flux to 137 Cs loading. → For the estuary and date studied, it is estimate that an 10,000 tonnes of

  7. Concurrent monitoring of vessels and water turbidity enhances the strength of evidence in remotely sensed dredging impact assessment

    NARCIS (Netherlands)

    Wu, G.; Leeuw, de J.; Skidmore, A.K.; Prins, H.H.T.; Liu, Y.

    2007-01-01

    Remotely sensed assessment of dredging impacts on water turbidity is straightforward when turbidity plumes show up in clear water. However, it is more complicated in turbid waters as the spatial or temporal changes in turbidity might be of natural origin. The plausibility of attributing turbidity

  8. Foraminifera, Thecamoebians and Palynomorphs as Hydrodynamic Indicators in Araguari Estuary, Amazonian Coast, Amapá State – Brazil

    Directory of Open Access Journals (Sweden)

    Odete Fátima Machado

    2010-01-01

    Full Text Available The Araguari estuarine dynamics is singular among traditional models of estuaries under tidal regime due to influence of macrotidal and tidal bore. In order to establish estuarine zones in Araguari according foraminifera, thecamoebians, paliynomorphs and physical-chemistry parameters, sixteen sample stations were established along the estuary. Turbidity and temperature were the environmental parameters which allowed determination of the estuarine gradient. Eighteen species of foraminifera, ten of thecamoebians and fourteen of particulate organic matter types were identified. Cluster analysis in R-mode showed three microorganism assemblages and four palynomorph ones. The CCA analyze shows turbidity and total organic matter with the most influence over foraminiferal and thecamoebians distribution at Araguari. Clustering analysis in Q-mode using all data formed four groups suggesting three estuarine zones in Araguari: Zone I composed of thecamoebian species and continental palynomorphs; Zone II - composed by mangrove foraminifera, thecamoebians and all palynomorph assemblages; and Zone III – composed by mangrove and estuarine foraminifera and all palynomorph assemblages.

  9. Collaborative Potential between National Estuary Programs ...

    Science.gov (United States)

    Estuaries are among the most productive ecosystems in the world, providing unique habitat for freshwater and marine species as well as valuable social and economic benefits. The wealth of ecosystem goods and services from estuaries has led to growth and development of human communities in adjacent areas and an increase in human activities that can adversely affect water quality and critical habitat. Managing for sustainable estuaries requires a balance of environmental concerns with community social and economic values. This has created an opportunity to leverage Environmental Protection Agency (EPA) scientific knowledge and tools with National Estuary Program (NEP) planning and management expertise to address environmental challenges in important estuarine ecosystems. The non-regulatory National Estuary Program (NEP) was outlined in the Clean Water Act to provide stakeholders an opportunity to monitor and manage ‘nationally significant’ estuaries. Currently there are 28 estuaries in the NEP, broadly distributed across the Atlantic, Pacific and Gulf Coasts, and in Puerto Rico. The local NEP management conferences must address a variety of environmental issues, from water quality and natural resources to coastal and watershed development. While the underlying objectives of each NEP are quite similar, each has unique landscapes, land uses, waterbodies, habitats, biological resources, economies and social culture. Consequently, the effects and severity of anthr

  10. Characterizing seston in the Penobscot River Estuary.

    Science.gov (United States)

    Meseck, Shannon L; Li, Yaqin; Sunila, Inke; Dixon, Mark; Clark, Paul; Lipsky, Christine; Stevens, Justin R; Music, Paul; Wikfors, Gary H

    2017-10-01

    The Penobscot River Estuary is an important system for diadromous fish in the Northeast United States of American (USA), in part because it is home to the largest remnant population of Atlantic salmon, Salmo salar, in the country. Little is known about the chemical and biological characteristics of seston in the Penobscot River Estuary. This study used estuarine transects to characterize the seston during the spring when river discharge is high and diadromous fish migration peaks in the Penobscot River Estuary. To characterize the seston, samples were taken in spring 2015 for phytoplankton identification, total suspended matter (TSM), percent organic TSM, chlorophyll a, particle size (2 μm-180 μm), particulate carbon and nitrogen concentrations, and stable carbon and nitrogen isotopes. The estuarine profiles indicate that TSM behaved non-conservatively with a net gain in the estuary. As phytoplankton constituted only 1/1000 of the particles, the non-conservative behavior of TSM observed in the estuary was most likely not attributable to phytoplankton. Particulate carbon and nitrogen ratios and stable isotope signals indicate a strong terrestrial, allochthonous signal. The seston in the Penobscot River Estuary was dominated by non-detrital particles. During a short, two-week time period, Heterosigma akashiwo, a phytoplankton species toxic to finfish, also was detected in the estuary. A limited number of fish samples, taken after the 2015 Penobscot River Estuary bloom of H. akashiwo, indicated frequent pathological gill damage. The composition of seston, along with ichthyotoxic algae, suggest the need for further research into possible effects upon resident and migratory fish in the Penobscot River Estuary. Published by Elsevier Ltd.

  11. Extending the range of turbidity measurement using polarimetry

    Science.gov (United States)

    Baba, Justin S.

    2017-11-21

    Turbidity measurements are obtained by directing a polarized optical beam to a scattering sample. Scattered portions of the beam are measured in orthogonal polarization states to determine a scattering minimum and a scattering maximum. These values are used to determine a degree of polarization of the scattered portions of the beam, and concentrations of scattering materials or turbidity can be estimated using the degree of polarization. Typically, linear polarizations are used, and scattering is measured along an axis that orthogonal to the direction of propagation of the polarized optical beam.

  12. A feasibility study for a remote laser water turbidity meter

    Science.gov (United States)

    Hickman, G. D.; Ghovanlou, A. H.; Friedman, E. J.; Gault, C. S.; Hogg, J. E.

    1974-01-01

    A technique to remotely determine the attenuation coefficient (alpha) of the water was investigated. The backscatter energy (theta = 180 deg) of a pulse laser (lambda = 440 - 660 nm) was found directly related to the water turbidity. The greatest sensitivity was found to exist at 440 nm. For waters whose turbidity was adjusted using Chesapeake Bay sediment, the sensitivity in determining alpha at 440 nm was found to be approximately 5 - 10%. A correlation was also found to exist between the water depth (time) at which the peak backscatter occurs and alpha.

  13. Significance of multiple scattering in imaging through turbid media

    International Nuclear Information System (INIS)

    Zardecki, A.; Gerstl, S.A.W.

    1986-01-01

    The degradation of image quality in a turbid medium is analyzed within the framework of the small-angle approximation, the diffusion approximation, and a rigorous two-dimensional radiative transfer equation. These three approaches allow us to emphasize different aspects of the imaging problem when multiple scattering effects are important. For a medium with a forward-peaked phase function, the separation of multiple scattering into a series of scatterings of various order provides a fruitful technique. The use of the diffusion approximation and transport theory extends the determination of the modulation transfer function to a turbid medium with an arbitrary degree of anisotropy

  14. Environmental Influences on the Fish Assemblage of the Humber Estuary, U.K.

    Science.gov (United States)

    Marshall, S.; Elliott, M.

    1998-02-01

    Salinity, temperature, turbidity and dissolved oxygen were measured in conjunction with a series of fish samples taken by a 2 m beam trawl from 14 sites throughout the Humber estuary, U.K., over the period April 1992 to November 1994. Sediment type was not measured as the literature indicates that the area is homogeneous. The influences of environmental factors and the characteristics of the fish assemblage were analysed using a range of multivariate techniques, including two-way indicator species analysis, canonical correspondence analysis, principal components analysis and Spearman rank correlation. The analyses indicate that salinity is the dominant factor influencing the distribution of the species, with temperature also having a major influence. Of the species examined, whiting (Merlangius merlangus), sole (Solea solea), flounder (Pleuronectes flesus), sprat (Sprattus sprattus) and herring (Clupea harengus) showed a correlation in distribution to temperature, sole, plaice (Pleuronectes platessa), pogge (Agonus cataphractus) and stickleback (Gasterosteus aculeatus) to salinity, and whiting, flounder, pogge and stickleback to dissolved oxygen. Only cod (Gadus morhua) showed a correlation with tidal state, while whiting, pogge and stickleback were correlated to depth. Unlike in some other estuaries, turbidity did not influence the composition of the fish assemblage. Temperature and salinity fluctuations appear to influence different aspects of the community, with temperature proving to be the best predictor of total abundance, while salinity influenced the species richness and total biomass. The analyses demonstrate the most important variables with regard to environmental-biotic interactions, although they also indicate that the variables measured do not account for all of the observed variation in fish biomass and abundance.

  15. Birds of Mahi River estuary, Gujarat, India

    Directory of Open Access Journals (Sweden)

    P.J. Pandya

    2010-06-01

    Full Text Available The Mahi river estuary is one of the major estuaries of Gujarat. This paper presents a comprehensive list of birds of the Mahi river estuary (nearly 50 km stretch and the adjacent banks/ravines and defines the avian diversity at three major estuarine gradations with a brief check of similarity and diversity within the three. The present observation is the outcome of a 3 year period from August 2006 to July 2009. A sum total of 118 species belonging to 42 families were reported and listed as on Upstream, Midstream, and Downstream of estuary. No significant difference was seen in the species richness at the three zones; a change in avian composition at upstream and downstream was notable.

  16. Climate Ready Estuaries Partner Projects Map

    Science.gov (United States)

    CRE partners with the National Estuary Program to develop climate change projects in coastal U.S. areas, such as bays and harbors; to develop adaptation action plans, identify climate impacts and indicators, and more. This map shows project locations.

  17. National Estuary Program Study Area Boundaries

    Data.gov (United States)

    U.S. Environmental Protection Agency — There are 28 National Estuary Programs (NEPs) in the U.S.that implement habitat protection and restoration projects with their partners. This work takes place within...

  18. Mercury enrichment in sediments of Amba estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Ram, A.; Rokade, M.A.; Zingde, M.D.

    of anthropogenic metal to the estuary. Geoaccumulation index and enrichment factor support Hg contamination of the estuarine sediment to a varying degree. Hg is not significantly correlated with TOC, Al, Fe and Mn in these sediments...

  19. Heavy metals in Mindhola river estuary, India

    Digital Repository Service at National Institute of Oceanography (India)

    Zingde, M.D.; Rokade, M.A; Mandalia, A

    The heavy metal concentrations are studied along the Mindhola river estuary. Surface and bottom water samples were collected using Niskin Sampler. The sediment samples were collected using a Van Veen grab. The heavy metal concentration is estimated...

  20. Mercury in sediments of Ulhas estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Ram, A.; Rokade, M.A.; Borole, D.V.; Zingde, M.D.

    Hg levels in water, suspended particulate matter and sediment of the Ulhas estuary are under considerable environmental stress due to the indiscriminate release of effluents from a variety of industries including chlor-alkali plants. Concentration...

  1. Benthic studies in south Gujarat estuaries

    Digital Repository Service at National Institute of Oceanography (India)

    Govindan, K.; Varshney, P.K.; Desai, B.N.

    Benthic biomass and faunal composition in relation to various environmental conditions of the four South Gujarat estuaries namely the Auranga, Ambika, Purna and Mindola were studied and compared. Mean population density of benthos in Auranga, Ambika...

  2. USING TURBIDITY DATA TO PREDICT SUSPENDED SEDIMENT CONCENTRATIONS: POSSIBILITIES, LIMITATIONS, AND PITFALLS

    Science.gov (United States)

    This talk will look at the relationships between turbidity and suspended sediment concentrations in a variety of geographic areas, geomorphic river types, and river sizes; and attempt to give guidance on using existing turbidity data to predict suspended sediment concentrations.

  3. Environmental conditions and biological community of the Penzhina and Talovka hypertidal estuary (northwest Kamchatka) in the ice-free season

    Science.gov (United States)

    Koval, M. V.; Gorin, S. L.; Romanenko, F. A.; Lepskaya, E. V.; Polyakova, A. A.; Galyamov, R. A.; Esin, E. V.

    2017-07-01

    New data on the abiotic conditions; species composition; abundance, distribution, and migrations of fauna; and feeding interactions in an estuary ecosystem were obtained during expeditions in the mouths of Penzhina and Talovka rivers (northwest Kamchatka). It is revealed that in the ice-free season, the hydrological regime of the estuary is determined by seasonal fluctuations of river runoff, as well as fortnightly and daily variation of tides. The estuary is characterized by hypertidal fluctuations (up to 10-12 m); strong reverse flows (up to 1.0-1.5 m/s), considerable tidal variations in salinity (from 0 to 6-9‰ at the river boundary and from 6-8 to 14-16‰ at the offshore boundary), and high water turbidity (up to 1 000 NTU or more). Based on the spatial structure of the community, three ecological zones with mobile boundaries are distinguished: freshwater (salinity 0-0.1‰), estuarine (0-12.3‰), and neritic (11.2-18.9‰). High turbidity prevents the development of phytoplankton in the estuarine zone (EZ), and the local benthic community is significantly depleted due to the desalination and wide spread of aleuritic silts. Neritic copepods and nektobenthic brackish- water crustaceans generate the maximum abundance and biomass here. The species that have adapted to the local extreme hydrologic conditions dominate and form the basis of the estuarine food chain. Dominant among the EZ vertebrates are such groups as anadromous fishes (smelts, pacific salmons, charrs, and sticklebacks); waterfowl (terns, kittiwakes, cormorants, fulmars, puffins, guillemots, auklets, and wadepipers); and predatory marine mammals (larga, ringed seal, bearded seal, and white whale). The total abundance and biomass of these animals are much higher in the pelagic EZ in comparison to neighboring zones.

  4. Laser measure of sea salinity, temperature and turbidity in depth

    Science.gov (United States)

    Hirschberg, J. G.; Wouters, A. W.; Byrne, J. D.

    1974-01-01

    A method is described in which a pulsed laser is used to probe the sea. Backscattered light is analyzed in time, intensity and wavelength. Tyndall, Raman and Brillouin scattering are used to obtain the backscatter turbidity, sound velocity, salinity, and the temperature as a function of depth.

  5. Continuous turbidity monitoring in streams of northwestern California

    Science.gov (United States)

    Rand Eads; Jack Lewis

    2002-01-01

    Abstract - Redwood Sciences Laboratory, a field office of the USDA Forest Service, Pacific Southwest Research Station has developed and refined methods and instrumentation to monitor turbidity and suspended sediment in streams of northern California since 1996. Currently we operate 21 stations and have provided assistance in the installation of 6 gaging stations for...

  6. 40 CFR 230.21 - Suspended particulates/turbidity.

    Science.gov (United States)

    2010-07-01

    ... Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.21 Suspended particulates/turbidity. (a) Suspended particulates in the aquatic ecosystem consist of fine-grained mineral particles..., and man's activities including dredging and filling. Particulates may remain suspended in the water...

  7. Turbidity. Training Module 5.240.2.77.

    Science.gov (United States)

    Bonte, John L.; Davidson, Arnold C.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with candle turbidimeter and the nephelometric method of turbidity analysis. Included are objectives, an instructor guide, student handout, and transparency masters. A video tape is also available from the author. This module considers use…

  8. Morphodynamics of supercritical high-density turbidity currents

    NARCIS (Netherlands)

    Cartigny, M.

    2012-01-01

    Seafloor and outcrop observations combined with numerical and physical experiments show that turbidity currents are likely 1) to be in a supercritical flow state and 2) to carry high sediment concentrations (being of high-density). The thesis starts with an experimental study of bedforms

  9. In situ visualization and data analysis for turbidity currents simulation

    Science.gov (United States)

    Camata, Jose J.; Silva, Vítor; Valduriez, Patrick; Mattoso, Marta; Coutinho, Alvaro L. G. A.

    2018-01-01

    Turbidity currents are underflows responsible for sediment deposits that generate geological formations of interest for the oil and gas industry. LibMesh-sedimentation is an application built upon the libMesh library to simulate turbidity currents. In this work, we present the integration of libMesh-sedimentation with in situ visualization and in transit data analysis tools. DfAnalyzer is a solution based on provenance data to extract and relate strategic simulation data in transit from multiple data for online queries. We integrate libMesh-sedimentation and ParaView Catalyst to perform in situ data analysis and visualization. We present a parallel performance analysis for two turbidity currents simulations showing that the overhead for both in situ visualization and in transit data analysis is negligible. We show that our tools enable monitoring the sediments appearance at runtime and steer the simulation based on the solver convergence and visual information on the sediment deposits, thus enhancing the analytical power of turbidity currents simulations.

  10. Sedimentological regimes for turbidity currents: Depth-averaged theory

    Science.gov (United States)

    Halsey, Thomas C.; Kumar, Amit; Perillo, Mauricio M.

    2017-07-01

    Turbidity currents are one of the most significant means by which sediment is moved from the continents into the deep ocean; their properties are interesting both as elements of the global sediment cycle and due to their role in contributing to the formation of deep water oil and gas reservoirs. One of the simplest models of the dynamics of turbidity current flow was introduced three decades ago, and is based on depth-averaging of the fluid mechanical equations governing the turbulent gravity-driven flow of relatively dilute turbidity currents. We examine the sedimentological regimes of a simplified version of this model, focusing on the role of the Richardson number Ri [dimensionless inertia] and Rouse number Ro [dimensionless sedimentation velocity] in determining whether a current is net depositional or net erosional. We find that for large Rouse numbers, the currents are strongly net depositional due to the disappearance of local equilibria between erosion and deposition. At lower Rouse numbers, the Richardson number also plays a role in determining the degree of erosion versus deposition. The currents become more erosive at lower values of the product Ro × Ri, due to the effect of clear water entrainment. At higher values of this product, the turbulence becomes insufficient to maintain the sediment in suspension, as first pointed out by Knapp and Bagnold. We speculate on the potential for two-layer solutions in this insufficiently turbulent regime, which would comprise substantial bedload flow with an overlying turbidity current.

  11. Turbidity removal from surface water using Tamarindus indica crude ...

    African Journals Online (AJOL)

    Plant-based coagulants are potential alternatives to chemical coagulants used in drinking water treatment. This paper examined the turbidity removal efficiency of Tamarindus indica fruit crude pulp extract (CPE) towards evaluating a low-cost option for drinking-water treatment. Laboratory analysis was carried out on high ...

  12. Estuaries.

    Science.gov (United States)

    Awkerman, Gary L.

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

  13. Suspended-sediment flux and retention in a backwater tidal slough complex near the landward boundary of an estuary

    Science.gov (United States)

    Morgan-King, Tara L.; Schoellhamer, David H.

    2013-01-01

    Backwater tidal sloughs are commonly found at the landward boundary of estuaries. The Cache Slough complex is a backwater tidal region within the Upper Sacramento–San Joaquin Delta that includes two features that are relevant for resource managers: (1) relatively high abundance of the endangered fish, delta smelt (Hypomesus transpacificus), which prefers turbid water and (2) a recently flooded shallow island, Liberty Island, that is a prototype for habitat restoration. We characterized the turbidity around Liberty Island by measuring suspended-sediment flux at four locations from July 2008 through December 2010. An estuarine turbidity maximum in the backwater Cache Slough complex is created by tidal asymmetry, a limited tidal excursion, and wind-wave resuspension. During the study, there was a net export of sediment, though sediment accumulates within the region from landward tidal transport during the dry season. Sediment is continually resuspended by both wind waves and flood tide currents. The suspended-sediment mass oscillates within the region until winter freshwater flow pulses flush it seaward. The hydrodynamic characteristics within the backwater region such as low freshwater flow during the dry season, flood tide dominance, and a limited tidal excursion favor sediment retention.

  14. Keurbooms Estuary floods and sedimentation

    Directory of Open Access Journals (Sweden)

    Eckart H. Schumann

    2015-11-01

    Full Text Available The Keurbooms Estuary at Plettenberg Bay lies on a wave-dominated, microtidal coast. It has a dune-topped sandy barrier, or barrier dune, almost 4 km long, with a narrow back-barrier lagoon connected to its source rivers, the Keurbooms and Bitou. The estuary exits to the sea through this barrier dune, and it is the geomorphology and mouth position in relation to floods, which is the subject of this paper. Measurements of rainfall, water level, waves and high- and low-tide water lines were used to analyse the mouth variability over the years 2006–2012. Two major floods occurred during this time, with the first in November 2007 eroding away more than 500 000 m3 of sediment. The new mouth was established at the Lookout Rocks limit – the first time since 1915. The second flood occurred in July 2012 and opened up a new mouth about 1 km to the north-east; high waves also affected the position of the breach. The mouth has a tendency to migrate southwards against the longshore drift, but at any stage this movement can be augmented or reversed. The effectiveness of floods in breaching a new mouth through the barrier dune depends on the flood size and the nature of the exit channel in the back-barrier lagoon. Other factors such as ocean waves, sea level, vegetative state of the dune and duration of the flood are also important and can determine where the breach occurs, and if the new mouth will dominate the old mouth.

  15. Bar dimensions and bar shapes in estuaries

    Science.gov (United States)

    Leuven, Jasper; Kleinhans, Maarten; Weisscher, Steven; van der Vegt, Maarten

    2016-04-01

    Estuaries cause fascinating patterns of dynamic channels and shoals. Intertidal sandbars are valuable habitats, whilst channels provide access to harbors. We still lack a full explanation and classification scheme for the shapes and dimensions of bar patterns in natural estuaries, in contrast with bars in rivers. Analytical physics-based models suggest that bar length in estuaries increases with flow velocity, tidal excursion length or estuary width, depending on which model. However, these hypotheses were never validated for lack of data and experiments. We present a large dataset and determine the controls on bar shape and dimensions in estuaries, spanning bar lengths from centimeters (experiments) to 10s of kilometers length. First, we visually identified and classified 190 bars, measured their dimensions (width, length, height) and local braiding index. Data on estuarine geometry and tidal characteristics were obtained from governmental databases and literature on case studies. We found that many complex bars can be seen as simple elongated bars partly cut by mutually evasive ebb- and flood-dominated channels. Data analysis shows that bar dimensions scale with estuary dimensions, in particular estuary width. Breaking up the complex bars in simple bars greatly reduced scatter. Analytical bar theory overpredicts bar dimensions by an order of magnitude in case of small estuarine systems. Likewise, braiding index depends on local width-to-depth ratio, as was previously found for river systems. Our results suggest that estuary dimensions determine the order of magnitude of bar dimensions, while tidal characteristics modify this. We will continue to model bars numerically and experimentally. Our dataset on tidal bars enables future studies on the sedimentary architecture of geologically complex tidal deposits and enables studying effects of man-induced perturbations such as dredging and dumping on bar and channel patterns and habitats.

  16. Operational monitoring of turbidity in rivers: how satellites can contribute

    Science.gov (United States)

    Hucke, Dorothee; Hillebrand, Gudrun; Winterscheid, Axel; Kranz, Susanne; Baschek, Björn

    2016-10-01

    The applications of remote sensing in hydrology are diverse and offer significant benefits for water monitoring. Up to now, operational river monitoring and sediment management in Germany mainly rely on in-situ measurements and on results obtained from numerical modelling. Remote sensing by satellites has a great potential to supplement existing data with two-dimensional information on near-surface turbidity distributions at greater spatial scales than in-situ measurements can offer. Within the project WasMon-CT (WaterMonitoring-Chlorophyll/Turbidity), the Federal Institute of Hydrology (BfG) aims at the implementation of an operational monitoring of turbidity distributions based on satellite images (esp. Sentinel-2, Landsat7 and 8). Initially, selected federal inland and estuarine waterways will be addressed: Rhine, Elbe, Ems, Weser. WasMon-CT is funded within the German Copernicus activities. Within the project, a database of atmospherically corrected, geo-referenced turbidity data will be assembled. The collected corresponding meta-data will include aspects of satellite data as well as hydrological data, e.g. cloud cover and river run-off. Based on this catalogue of spatially linked meta-data, the satellite data will be selected by e.g. cloud cover or run-off. The permanently updated database will include past as well as recent satellite images. It is designed with a long-term perspective to optimize the existing in-situ measurement network, which will serve partly for calibration and partly as validation data set. The aim is to extend, but not to substitute, the existing frequent point measurements with spatially extensive, satellite-derived data from the near surface part of the water column. Here, turbidity is used as proxy for corresponding suspended sediment concentrations. For this, the relationship between turbidity and suspended sediment concentrations will be investigated. Products as e.g. longitudinal profiles or virtual measurement stations will be

  17. Importance of atmospheric turbidity and associated uncertainties in solar radiation and luminous efficacy modelling

    International Nuclear Information System (INIS)

    Gueymard, Christian A.

    2005-01-01

    For many solar-related applications, it is important to separately predict the direct and diffuse components of irradiance or illuminance. Under clear skies, turbidity plays a determinant role in quantitatively affecting these components. In this paper, various aspects of the effect of turbidity on both spectral and broadband radiation are addressed, as well as the uncertainty in irradiance predictions due to inaccurate turbidity data, and the current improvements in obtaining the necessary turbidity data

  18. A contribution to understanding the turbidity behaviour in an Amazon floodplain

    OpenAIRE

    Alcântara, E.; Novo, E.; Stech, J.; Lorenzzetti, J.; Barbosa, C.; Assireu, A.; Souza, A.

    2010-01-01

    Observations of turbidity provide quantitative information about water quality. However, the number of available in situ measurements for water quality determination is usually limited in time and space. Here, we present an analysis of the temporal and spatial variability of the turbidity of an Amazon floodplain lake using two approaches: (1) wavelet analysis of a turbidity time series measured by an automatic monitoring system, which should be improved/simplified, and (2) turbidity samples m...

  19. Potential of turbidity monitoring for real time control of pollutant discharge in sewers during rainfall events

    OpenAIRE

    LACOUR, Céline; JOANNIS, Claude; GROMAIRE, MC; CHEBBO, Ghassan

    2009-01-01

    Turbidity sensors can be used to continuously monitor the evolution of pollutant mass discharge. For two sites within the Paris combined sewer system, continuous turbidity, conductivity and flow data were recorded at one-minute time intervals over a one-year period. This paper is intended to highlight the variability in turbidity dynamics during wet weather. For each storm event, turbidity response aspects were analysed through different classifications. The correlation between classification...

  20. Utility of mesohabitat features for determining habitat associations of subadult sharks in Georgia’s estuaries

    Science.gov (United States)

    Belcher, C.N.; Jennings, Cecil A.

    2010-01-01

    We examined the affects of selected water quality variables on the presence of subadult sharks in six of nine Georgia estuaries. During 231 longline sets, we captured 415 individuals representing nine species. Atlantic sharpnose shark (Rhizoprionodon terranovae), bonnethead (Sphyrna tiburo), blacktip shark (Carcharhinus limbatus) and sandbar shark (C. plumbeus) comprised 96.1% of the catch. Canonical correlation analysis (CCA) was used to assess environmental influences on the assemblage of the four common species. Results of the CCA indicated Bonnethead Shark and Sandbar Shark were correlated with each other and with a subset of environmental variables. When the species occurred singly, depth was the defining environmental variable; whereas, when the two co-occurred, dissolved oxygen and salinity were the defining variables. Discriminant analyses (DA) were used to assess environmental influences on individual species. Results of the discriminant analyses supported the general CCA findings that the presence of bonnethead and sandbar shark were the only two species that correlated with environmental variables. In addition to depth and dissolved oxygen, turbidity influenced the presence of sandbar shark. The presence of bonnethead shark was influenced primarily by salinity and turbidity. Significant relationships existed for both the CCA and DA analyses; however, environmental variables accounted for shark species among sites.

  1. Fishes and fisheries in tropical estuaries: The last 10 years

    Science.gov (United States)

    Blaber, S. J. M.

    2013-12-01

    Since 2002 there has been an increase in knowledge of many aspects of the biology and ecology of tropical estuarine fishes, as well as significant changes to many estuarine fisheries. Analyses of literature databases (2002-2012) show that: of the c. 600 relevant papers, 52% are primarily related to ecology, 11% to conservation, 11% to anthropogenic and pollution effects on fishes, 9% to fisheries, 7% to aquaculture, 4% to study techniques, and 1% each to fish larvae, effects of fishing, taxonomy, climate change, evolution and genetics. In terms of geographic spread 17% are from North America, 15% from south Asia, 14% from the Caribbean, 13% from Australasia, 12% from Africa and 9% each from South America and SE Asia. Research papers came from 50 countries of which the dominant were USA (15%), India (12%), Australia (11%) and Brazil (7%). Increasing numbers of studies in West Africa, SE and South Asia and South America have increased basic knowledge of the ecology of estuarine fish faunas. Increases in understanding relate to: roles of salinity, turbidity and habitat diversity; connectivity between habitats; water flow; ecological drivers of spatial variability; scale dependent variation; thermal tolerances; movement patterns; food webs; larval adaptations; and the viability of areas heavily impacted by human activities. New reviews both challenge and support different aspects of the estuarine dependence paradigm - still perhaps one of the main research issues - and the protective function of estuaries and mangroves for juvenile fishes has received attention in relation to e.g. predation risks and fisheries. There have also been significant advances in the use of guilds and biodiversity models. Fishing pressures have continued unabated in most tropical estuaries and are summarised and management issues discussed. Understanding of the relationships between fisheries production and mangroves has advanced and significant differences have emerged between Indo

  2. Radio elements transfer from water to atmosphere through degassing processes in the Loire estuary: the Flore project

    International Nuclear Information System (INIS)

    Fontugne, M.; Hatte, C.; Paterne, M.; Maro, D.; Germain, P.; Hebert, D.; Rozet, M.; Voiseux, C.; Solier, L.; Tenailleau, L.; Abril, G.

    2004-01-01

    The behaviour of the toxic substances in the environment covers various fields of investigations like contamination by the radioelements, heavy metals and organic compounds. The knowledge of the biogeochemical cycles of the radioelements basically their temporal and spatial distributions is essential to a better understanding of their biological effects. Estuarine environments present a major interest since they constitute accumulation areas of wastes and rejections of the majority of the anthropogenic activities. These transition zones between fresh waters and ocean, characterised by the change of the physico- chemical properties (pH, salinity, turbidity) allows a redistribution of the radioelements by their speciation or phase change thus modifying their bio-availability. The Loire River estuary receives the rejections of radioelements being able to come from various sources like the nuclear thermal power stations (fourteen engines with discharges of carbon-14, tritium), the hospital complexes (rejections of iodine 131). The aims of FLORE program is to study the distribution of these radioelements and processes of phase transfer in this estuary especially in the mud plug area where the biochemical activity is intense. If most of the processes of transfer are now well established, fluxes of radioelements between water and the atmosphere are not quantified. Two oceanographic cruises carried out in February and September 2003 on board N/O 'Cotes de La Manche' allow to present distribution Iodine 131 within the estuary and the first estimation of radiocarbon and tritium fluxes from the river water to the atmosphere. (author)

  3. Turbidity-controlled suspended sediment sampling for runoff-event load estimation

    Science.gov (United States)

    Jack Lewis

    1996-01-01

    Abstract - For estimating suspended sediment concentration (SSC) in rivers, turbidity is generally a much better predictor than water discharge. Although it is now possible to collect continuous turbidity data even at remote sites, sediment sampling and load estimation are still conventionally based on discharge. With frequent calibration the relation of turbidity to...

  4. 40 CFR 141.551 - What strengthened combined filter effluent turbidity limits must my system meet?

    Science.gov (United States)

    2010-07-01

    ... effluent turbidity limits must my system meet? 141.551 Section 141.551 Protection of Environment... Effluent Requirements § 141.551 What strengthened combined filter effluent turbidity limits must my system meet? Your system must meet two strengthened combined filter effluent turbidity limits. (a) The first...

  5. 40 CFR 141.560 - Is my system subject to individual filter turbidity requirements?

    Science.gov (United States)

    2010-07-01

    ... filter turbidity requirements? 141.560 Section 141.560 Protection of Environment ENVIRONMENTAL PROTECTION... Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Individual Filter Turbidity Requirements § 141.560 Is my system subject to individual filter turbidity requirements? If your system is a subpart...

  6. Centrifuge experiments for removal of aluminium turbidity from Dhruva heavy water

    International Nuclear Information System (INIS)

    Shetiya, R.S.; Unny, V.K.P.; Nayak, A.P.

    1989-01-01

    Aluminium turbidity and associated radioactivity was observed in the moderator cum coolant system of Dhruva during initial power operation. Ion exchange resin beds of the purification system were not able to remove aluminium turbidity and radioactivity of system heavy water. Centrifuge technique was used as a convenient alternative method to remove the turbidity and radioactivity. (author)

  7. 40 CFR 141.561 - What happens if my system's turbidity monitoring equipment fails?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false What happens if my system's turbidity... Disinfection-Systems Serving Fewer Than 10,000 People Individual Filter Turbidity Requirements § 141.561 What happens if my system's turbidity monitoring equipment fails? If there is a failure in the continuous...

  8. Suspended sediment diffusion mechanisms in the Yangtze Estuary influenced by wind fields

    Science.gov (United States)

    Wang, Lihua; Zhou, Yunxuan; Shen, Fang

    2018-01-01

    The complexity of suspended sediment concentration (SSC) distribution and diffusion has been widely recognized because it is influenced by sediment supply and various hydrodynamic forcing conditions that vary over space and over time. Sediment suspended by waves and transported by currents are the dominant sediment transport mechanisms in estuarine and coastal areas. However, it is unclear to what extent the SSC distribution is impacted by each hydrodynamic factor. Research on the quantitative influence of wind fields on the SSC diffusion range will contribute to a better understanding of the characteristics of sediment transport change and sedimentary geomorphic evolution. This study determined SSC from three Envisat Medium-Resolution Imaging Spectrometer acquisitions, covering the Yangtze Estuary and adjacent water area under the same season and tidal conditions but with varying wind conditions. SSC was examined based on the Semi-Empirical Radiative Transfer model, which has been well validated with the observation data. Integrating the corresponding wind field information from European Centre for Medium-Range Weather Forecasts further facilitated the discussion of wind fields affecting SSC, and in turn the influence of water and suspended sediment transportation and diffusion in the Yangtze estuarine and coastal area. The results demonstrated that the SSC present much more distinctive fluvial features in the inner estuary and wind fields are one of the major factors controlling the range of turbid water diffusion.

  9. Environmental consequences of tidal power in a hyper-tidal muddy regime: the Severn estuary

    International Nuclear Information System (INIS)

    Kirby, R.

    1997-01-01

    Muddy hyper-tidal regimes, such as the Severn Estuary in the UK, are especially difficult for plants and animals. The difficulties stem from the semi-diurnal and semi-lunar energy fluctuations. On spring tides entrained fine sediment induces elevated suspended sediment concentrations such that photosynthesis is inhibited. On neap tides much of the entrained fine sediment is deposited on the sub-tidal bed over periods of several days to form ephemeral dense layers, which reach in excess of 100 G/l and rapidly become anaerobic on stagnation. Such occasional bed faunas as develop are characterised by very large numbers of immature individuals of a few species. One of the few organisms able to cope with the extreme conditions is the siliceous reef-building worn Sabellaria. Arising from the long term suppression in its calcareous fauna, erosion and winnowing of these Holocene clays fails to give rise to lag shell deposits, called chenier ridges, found elsewhere in eroding muddy inter-tidal systems. A tidal power barrage would shift the regime from hyper-tidal to macro-tidal decrease in turbidity would permit photosynthesis and phytoplankton growth, so stimulating the higher food chain. Ironically, perhaps, cleaning up the sewage discharges in the estuary, in the absence of barrage construction would lead to a wading bird crash whereas barrage construction would lead to an improved carrying capacity. (author)

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

    Science.gov (United States)

    Ruffing, Jenny

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

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

    Digital Repository Service at National Institute of Oceanography (India)

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

    immune from extended hypoxia/anoxia and maintaining the health of the Cochin estuary. For the seasonally varying river flow in the estuary, salt intrusion receded with increasing river flow in monsoon and rebounded with decreasing river flow in dry season...

  12. Spatial distribution of suspended particulate matter in the Mandovi and Zuari estuaries: inferences on the estuarine turbidity maximum

    Digital Repository Service at National Institute of Oceanography (India)

    Suja, S.; Kessarkar, P.M.; Shynu, R.; Rao, V.P.; Fernandes, L.L.

    to tidal and wind-driven waves and currents. Our results corroborate the findings of Kes- sarkar et al.10,16 that high ETM is associ- ated with high salinity at the sea end. The vertical profiles of SPM suggest ex- tension of this ETM up to 2 m depth... instantaneously forming a high-temperature mineral phase (fayalite) along with a quenched glassy matrix. Studies on ancient slags worldwide7–10 have shown that the proportions of phos- phorus are in the range 0.05–0.5 wt%, with levels up to 1.0 wt...

  13. Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries

    NARCIS (Netherlands)

    Schramkowski, G.P.; de Swart, H.E.; Schuttelaars, H.

    2010-01-01

    A three-dimensional numerical model with a prognostic salinity field is used to investigate the effect of a partial slip bottom boundary condition on lateral flow and sediment distribution in a transect of a tidally dominated channel. The transect has a symmetrical Gaussian cross-channel bottom

  14. Flocculation and floc break-up related to tidally induced turbulent shear in a low-turbidity, microtidal estuary

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Andersen, Thorbjørn Joest

    2014-01-01

    flocculation and floc break-up dynamics in the lower part of the water column in the period around slack water. These dynamics were confirmed in the Eulerian deployments and were reoccurring in every tidal cycle. The dynamics were mostly governed by changes in turbulent shear. Strong microflocs with a lower...... mean threshold diameter of 50–60 μm present at high turbulent shear flocculated to form fragile macroflocs with sizes of several hundred microns and mean diameters above 80 μm around slack water periods. A hysteresis in floc break-up and flocculation was found at high water slack (HWS), as flocs formed...

  15. Suspended Matter, Chl-a, CDOM, Grain Sizes, and Optical Properties in the Arctic Fjord-Type Estuary, Kangerlussuaq, West Greenland During Summer

    DEFF Research Database (Denmark)

    Lund-Hansen, L. C.; Andersen, T. J.; Nielsen, Morten Holtegaard

    2010-01-01

    Optical constituents as suspended particulate matter (SPM), chlorophyll (Chl-a), colored dissolved organic matter (CDOM), and grain sizes were obtained on a transect in the arctic fjord-type estuary Kangerlussuaq (66A degrees) in August 2007 along with optical properties. These comprised diffuse...... water outlet. Values of optical constituents and properties decreased with distance from the melt water outlet to a more or less constant level in central and outer part of the estuary. There was a strong correlation between inorganic suspended matter (SPMI) and diffuse attenuation coefficient K (d...... from the very high turbid melt water outlet to clear marine waters. Results showed a strong spatial variation with high values as for suspended matter concentrations, CDOM, diffuse attenuation coefficient K (d)(PAR), particle beam attenuation coefficients (c (p)), and reflectance R(-0, PAR) at the melt...

  16. Relationship of photosynthetic carbon fixation with environmental changes in the Jiulong River estuary of the South China Sea, with special reference to the effects of solar UV radiation

    International Nuclear Information System (INIS)

    Li Gang; Gao Kunshan; Yuan Dongxing; Zheng Ying; Yang Guiyuan

    2011-01-01

    Highlights: → C-fixation is the highest in turbidity front, though UV resulted in higher inhibition. → Increased availability of CO 2 appeared to stimulate photosynthetic machinery. → Osmotic stress made phytoplankton more sensitive to UV. - Abstract: Phytoplankton cells in estuary waters usually experience drastic changes in chemical and physical environments due to mixing of fresh and seawaters. In order to see their photosynthetic performance in such dynamic waters, we measured the photosynthetic carbon fixation by natural phytoplankton assemblages in the Jiulong River estuary of the South China Sea during April 24-26 and July 24-26 of 2008, and investigated its relationship with environmental changes in the presence or the absence of UV radiation. Phytoplankton biomass (Chl a) decreased sharply from the river-mouth to seawards (17.3-2.1 μg L -1 ), with the dominant species changed from chlorophytes to diatoms. The photosynthetic rate based on Chl a at noon time under PAR-alone increased from 1.9 μg C (μg Chl a) -1 L -1 in low salinity zone (SSS -1 L -1 in turbidity front (SSS within 10-20), and then decreased to 2.1 μg C (μg Chl a) -1 L -1 in mixohaline zone (SSS > 20); accordingly, the carbon fixation per volume of seawater increased from 12.8 to 149 μg C L -1 h -1 , and decreased to 14.3 μg C L -1 h -1 . Solar UVR caused the inhibition of carbon fixation in surface water of all the investigated zones, by 39% in turbidity area and 7-10% in freshwater or mixohaline zones. In the turbidity zone, higher availability of CO 2 could have enhanced the photosynthetic performance; while osmotic stress might be responsible for the higher sensitivity of phytoplankton assemblages to solar UV radiation.

  17. Relationships between aquatic vegetation and water turbidity: A field survey across seasons and spatial scales.

    Science.gov (United States)

    Austin, Åsa N; Hansen, Joakim P; Donadi, Serena; Eklöf, Johan S

    2017-01-01

    Field surveys often show that high water turbidity limits cover of aquatic vegetation, while many small-scale experiments show that vegetation can reduce turbidity by decreasing water flow, stabilizing sediments, and competing with phytoplankton for nutrients. Here we bridged these two views by exploring the direction and strength of causal relationships between aquatic vegetation and turbidity across seasons (spring and late summer) and spatial scales (local and regional), using causal modeling based on data from a field survey along the central Swedish Baltic Sea coast. The two best-fitting regional-scale models both suggested that in spring, high cover of vegetation reduces water turbidity. In summer, the relationships differed between the two models; in the first model high vegetation cover reduced turbidity; while in the second model reduction of summer turbidity by high vegetation cover in spring had a positive effect on summer vegetation which suggests a positive feedback of vegetation on itself. Nitrogen load had a positive effect on turbidity in both seasons, which was comparable in strength to the effect of vegetation on turbidity. To assess whether the effect of vegetation was primarily caused by sediment stabilization or a reduction of phytoplankton, we also tested models where turbidity was replaced by phytoplankton fluorescence or sediment-driven turbidity. The best-fitting regional-scale models suggested that high sediment-driven turbidity in spring reduces vegetation cover in summer, which in turn has a negative effect on sediment-driven turbidity in summer, indicating a potential positive feedback of sediment-driven turbidity on itself. Using data at the local scale, few relationships were significant, likely due to the influence of unmeasured variables and/or spatial heterogeneity. In summary, causal modeling based on data from a large-scale field survey suggested that aquatic vegetation can reduce turbidity at regional scales, and that high

  18. Relationships between aquatic vegetation and water turbidity: A field survey across seasons and spatial scales.

    Directory of Open Access Journals (Sweden)

    Åsa N Austin

    Full Text Available Field surveys often show that high water turbidity limits cover of aquatic vegetation, while many small-scale experiments show that vegetation can reduce turbidity by decreasing water flow, stabilizing sediments, and competing with phytoplankton for nutrients. Here we bridged these two views by exploring the direction and strength of causal relationships between aquatic vegetation and turbidity across seasons (spring and late summer and spatial scales (local and regional, using causal modeling based on data from a field survey along the central Swedish Baltic Sea coast. The two best-fitting regional-scale models both suggested that in spring, high cover of vegetation reduces water turbidity. In summer, the relationships differed between the two models; in the first model high vegetation cover reduced turbidity; while in the second model reduction of summer turbidity by high vegetation cover in spring had a positive effect on summer vegetation which suggests a positive feedback of vegetation on itself. Nitrogen load had a positive effect on turbidity in both seasons, which was comparable in strength to the effect of vegetation on turbidity. To assess whether the effect of vegetation was primarily caused by sediment stabilization or a reduction of phytoplankton, we also tested models where turbidity was replaced by phytoplankton fluorescence or sediment-driven turbidity. The best-fitting regional-scale models suggested that high sediment-driven turbidity in spring reduces vegetation cover in summer, which in turn has a negative effect on sediment-driven turbidity in summer, indicating a potential positive feedback of sediment-driven turbidity on itself. Using data at the local scale, few relationships were significant, likely due to the influence of unmeasured variables and/or spatial heterogeneity. In summary, causal modeling based on data from a large-scale field survey suggested that aquatic vegetation can reduce turbidity at regional scales

  19. Technical note: False low turbidity readings from optical probes during high suspended-sediment concentrations

    Science.gov (United States)

    Voichick, Nicholas; Topping, David J.; Griffiths, Ronald E.

    2018-03-01

    Turbidity, a measure of water clarity, is monitored for a variety of purposes including (1) to help determine whether water is safe to drink, (2) to establish background conditions of lakes and rivers and detect pollution caused by construction projects and stormwater discharge, (3) to study sediment transport in rivers and erosion in catchments, (4) to manage siltation of water reservoirs, and (5) to establish connections with aquatic biological properties, such as primary production and predator-prey interactions. Turbidity is typically measured with an optical probe that detects light scattered from particles in the water. Probes have defined upper limits of the range of turbidity that they can measure. The general assumption is that when turbidity exceeds this upper limit, the values of turbidity will be constant, i.e., the probe is pegged; however, this assumption is not necessarily valid. In rivers with limited variation in the physical properties of the suspended sediment, at lower suspended-sediment concentrations, an increase in suspended-sediment concentration will cause a linear increase in turbidity. When the suspended-sediment concentration in these rivers is high, turbidity levels can exceed the upper measurement limit of an optical probe and record a constant pegged value. However, at extremely high suspended-sediment concentrations, optical turbidity probes do not necessarily stay pegged at a constant value. Data from the Colorado River in Grand Canyon, Arizona, USA, and a laboratory experiment both demonstrate that when turbidity exceeds instrument-pegged conditions, increasing suspended-sediment concentration (and thus increasing turbidity) may cause optical probes to record decreasing false turbidity values that appear to be within the valid measurement range of the probe. Therefore, under high-turbidity conditions, other surrogate measurements of turbidity (e.g., acoustic-attenuation measurements or suspended-sediment samples) are necessary to

  20. Environmental modulation of the plankton community composition and size-structure along the eutrophic intertidal coast of the Río de la Plata estuary, Argentina

    Directory of Open Access Journals (Sweden)

    Maximiliano D. Garcia

    2014-05-01

    Full Text Available In this study we investigated the spatial distribution of the plankton community, bacterio-, phyto- and zooplankton, in relation with environmental conditions along the intertidal coast of the Río de la Plata estuary, Argentina. Plankton was analyzed in terms of species composition, abundance, biomass (carbon content and size-structure. We aim to evaluate the potential effects of anthropogenic impacts (e.g., nutrient enrichment and physicochemical gradients alongshore (e.g., salinity, turbidity on the composition and functioning of the plankton. We asked whether the natural structuring of the plankton by salinity and turbidity, known to be true of estuaries, is modified by eutrophication along the studied shoreline. We found that the density and biomass of bacteria and phytoplankton were strikingly enhanced by high eutrophication levels along the intertidal southwest coast of the Río de la Plata estuary. We also found that the highest zooplankton density in the most polluted area but the biomass showed a different distribution pattern. Nevertheless, when zooplankton was analyzed by means of its size fraction, we accordingly found that the microzooplankton biomass was positively associated with smaller-size phytoplankton groups and the most polluted study sites. Copepods were the major taxonomic groups that best represented the mesozooplankton biomass. We therefore expected that its distribution was modulated by the presence of its food items (i.e., large cells which, in turn, were more abundant in the middle-outer zone. In contrast, we found that the highest biomass of copepods occurred at the innermost site of the estuary and we found no significant association with other planktonic groups. Overall, this study highlights the noteworthy impacts of human activities modifying the functioning of this coastal ecosystem. The differences found in the taxonomic composition and size structure of the planktonic community assemblage between the most

  1. Performance of alum and assorted coagulants in turbidity removal of muddy water

    Science.gov (United States)

    Malik, Qasim H.

    2018-03-01

    Coagulation is a primary and cost effective process in water treatment plants. Under optimum conditions, not only it effectively removes turbidity but also results in reduced sludge volume and subsequently minimizes sludge management costs. Highly turbid water from streams, canals, rivers and rain run offs was run through jar test for turbidity removal. The brown water with 250NTU turbidity when coagulated with alum and assorted coagulants proved that maximum turbidity removal was witnessed using alum dose of 0.25 g/l at ph 6 with a sedimentation time of 30 min.

  2. Towards the classification of eutrophic condition in estuaries

    CSIR Research Space (South Africa)

    Lemley, DA

    2015-10-01

    Full Text Available Water quality and ecological integrity of estuaries closely reflect activities within the entire upstream catchment. Much emphasis has been placed on the response of estuaries to anthropogenic stressors through the use of monitoring programmes. Key...

  3. Pollution induced tidal variability in water quality of Mahim Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Zingde, M.D.; Sabnis, M.M.

    Variability of water quality due to release of wastewater in Mahim Estuary (Maharashtra, India) and associated nearshore waters is discussed. The mixing of low salinity contaminated estuary water with high salinity bay water was considerably...

  4. Benthos of Beypore and Korapuzha estuaries of North Kerala

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, K.S.; Sankaranarayanan, V.N.; Venugopal, P.

    The benthos from Beypore and Korapuzha estuaries were studied for one year. Environmental features, sediment characteristics and organic carbon content were estimated. Benthic density was high during monsoon and postmonsoon in both the estuaries...

  5. Variations of dissolved oxygen in Mandovi and Zuari estuaries

    Digital Repository Service at National Institute of Oceanography (India)

    DeSousa, S.N.; SenGupta, R.

    During non-monsoon months the estuaries were well mixed showing uniform oxygen concentrations from surface to bottom. However, during monsoon months both the estuaries showed stratified conditions with surface water showing high oxygen concentration...

  6. Nutrient characterisation of river inflow into the estuaries of the ...

    African Journals Online (AJOL)

    Nutrient characterisation of river inflow into the estuaries of the Gouritz Water ... into the estuaries within the Gouritz Water Management Area (WMA) of South Africa. ... Long-term water quality monitoring data (dissolved inorganic nitrogen, i.e. ...

  7. Skagit IMW - Skagit River Estuary Intensively Monitored Watershed Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study evaluates system-level effects of several estuary restoration projects on juvenile Chinook salmon production in the Skagit River estuary. The monitoring...

  8. Turbidity in oil-in-water-emulsions - Key factors and visual perception.

    Science.gov (United States)

    Linke, C; Drusch, S

    2016-11-01

    The aim of the present study is to systematically describe the factors affecting turbidity in beverage emulsions and to get a better understanding of visual perception of turbidity. The sensory evaluation of the human visual perception of turbidity showed that humans are most sensitive to turbidity differences between two samples in the range between 1000 and 1500 NTU (ratio) (nephelometric turbidity units). At very high turbidity values >2000 TU in NTU (ratio) were needed to distinguish between samples that they were perceived significantly different. Particle size was the most important factor affecting turbidity. It was shown that a maximum turbidity occurs at a mean volume - surface diameter of 0.2μm for the oil droplet size. Additional parameters were the refractive index, the composition of the aqueous phase and the presence of excess emulsifier. In a concentration typical for a beverage emulsion a change in the refractive index of the oil phase may allow the alteration of turbidity by up to 30%. With the knowledge on visual perception of turbidity and the determining factors, turbidity can be tailored in product development according to the customer requirements and in quality control to define acceptable variations in optical appearance. Copyright © 2016. Published by Elsevier Ltd.

  9. Environmental conditions and intraspecific interference: unexpected effects of turbidity on pike (Esox lucius) foraging

    DEFF Research Database (Denmark)

    Nilsson, P.A.; Jacobsen, Lene; Berg, Søren

    2009-01-01

    on pike foraging alone or among conspecifics in different levels of water turbidity, we expected high turbidity to decrease the perceived risk of intraspecific interactions among pike, and thereby decrease the strength of interference, as turbidity would decrease the visual contact between individuals...... and act as a refuge from behavioural interactions. The results show that this is not the case, but suggest that interference is induced instead of reduced in high turbidity. Per capita foraging rates do not differ between pike foraging alone or in groups in our clear and moderately turbid treatments......, indicating no effect of interference. As high turbidity enhances prey consumption for pike individuals foraging alone, but does not have this effect for pike in groups, high turbidity induces the relative interference effect. We suggest that future evaluations of the stabilizing effects of interference...

  10. Turbidity of a Binary Fluid Mixture: Determining Eta

    Science.gov (United States)

    Jacobs, Donald T.

    1996-01-01

    A ground based (1-g) experiment is in progress that will measure the turbidity of a density-matched, binary fluid mixture extremely close to its liquid-liquid critical point. By covering the range of reduced temperatures t equivalent to (T-T(sub c)) / T(sub c) from 10(exp -8) to 10(exp -2), the turbidity measurements will allow the critical exponent eta to be determined. No experiment has precisely determined a value of the critical exponent eta, yet its value is significant to theorists in critical phenomena. Relatively simple critical phenomena, as in the liquid-liquid system studied here, serve as model systems for more complex systems near a critical point.

  11. Measurement of in vitro microtubule polymerization by turbidity and fluorescence.

    Science.gov (United States)

    Mirigian, Matthew; Mukherjee, Kamalika; Bane, Susan L; Sackett, Dan L

    2013-01-01

    Tubulin polymerization may be conveniently monitored by the increase in turbidity (optical density, or OD) or by the increase in fluorescence intensity of diamidino-phenylindole. The resulting data can be a quantitative measure of microtubule (MT) assembly, but some care is needed in interpretation, especially of OD data. Buffer formulations used for the assembly reaction significantly influence the polymerization, both by altering the critical concentration for polymerization and by altering the exact polymer produced-for example, by increasing the production of sheet polymers in addition to MT. Both the turbidity and the fluorescence methods are useful for demonstrating the effect of MT-stabilizing or -destabilizing additives. 2013 Published by Elsevier Inc.

  12. Holographic characterization of colloidal particles in turbid media

    Science.gov (United States)

    Cheong, Fook Chiong; Kasimbeg, Priya; Ruffner, David B.; Hlaing, Ei Hnin; Blusewicz, Jaroslaw M.; Philips, Laura A.; Grier, David G.

    2017-10-01

    Holographic particle characterization uses in-line holographic microscopy and the Lorenz-Mie theory of light scattering to measure the diameter and the refractive index of individual colloidal particles in their native dispersions. This wealth of information has proved invaluable in fields as diverse as soft-matter physics, biopharmaceuticals, wastewater management, and food science but so far has been available only for dispersions in transparent media. Here, we demonstrate that holographic characterization can yield precise and accurate results even when the particles of interest are dispersed in turbid media. By elucidating how multiple light scattering contributes to image formation in holographic microscopy, we establish the range conditions under which holographic characterization can reliably probe turbid samples. We validate the technique with measurements on model colloidal spheres dispersed in commercial nanoparticle slurries.

  13. Environmental flow assessments for transformed estuaries

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

    Patino, Eduardo; Byrne, Michael J.

    2004-01-01

    Acoustic and optic methods were applied to estimate suspended-solids concentrations in the St. Lucie River Estuary, southeastern Florida. Acoustic Doppler velocity meters were installed at the North Fork, Speedy Point, and Steele Point sites within the estuary. These sites provide varying flow, salinity, water-quality, and channel cross-sectional characteristics. The monitoring site at Steele Point was not used in the analyses because repeated instrument relocations (due to bridge construction) prevented a sufficient number of samples from being collected at the various locations. Acoustic and optic instruments were installed to collect water velocity, acoustic backscatter strength (ABS), and turbidity data that were used to assess the feasibility of estimating suspended-solids concentrations in the estuary. Other data collected at the monitoring sites include tidal stage, salinity, temperature, and periodic discharge measurements. Regression analyses were used to determine the relations of suspended-solids concentration to ABS and suspended-solids concentration to turbidity at the North Fork and Speedy Point sites. For samples used in regression analyses, measured suspended-solids concentrations at the North Fork and Speedy Point sites ranged from 3 to 37 milligrams per liter, and organic content ranged from 50 to 83 percent. Corresponding salinity for these samples ranged from 0.12 to 22.7 parts per thousand, and corresponding temperature ranged from 19.4 to 31.8 ?C. Relations determined using this technique are site specific and only describe suspended-solids concentrations at locations where data were collected. The suspended-solids concentration to ABS relation resulted in correlation coefficients of 0.78 and 0.63 at the North Fork and Speedy Point sites, respectively. The suspended-solids concentration to turbidity relation resulted in correlation coefficients of 0.73 and 0.89 at the North Fork and Speedy Point sites, respectively. The adequacy of the

  15. Effect of Fresnel Reflectivity in a Spherical Turbid Medium

    CERN Document Server

    Elghazaly, A

    2003-01-01

    Radiative transfer problem for anisotropic scattering in a spherical homogeneous, turbid medium with angular dependent (specular) reflecting boundary is solved using the pomraning-Eddington approximation method. The angular dependent reflectivity of the boundary is considered as Fresnel's reflection probability function. The partial heat flux is calculated with anisotropic scattering through a homogeneous solid sphere. our results are compared with the available data and give an excellent agreement.

  16. Effect of Fresnel Reflectivity in a Spherical Turbid Medium

    International Nuclear Information System (INIS)

    Elghazaly, A.; Attia, M.T.

    2003-01-01

    Radiative transfer problem for anisotropic scattering in a spherical homogeneous, turbid medium with angular dependent (specular) reflecting boundary is solved using the pomraning-Eddington approximation method. The angular dependent reflectivity of the boundary is considered as Fresnel's reflection probability function. The partial heat flux is calculated with anisotropic scattering through a homogeneous solid sphere. our results are compared with the available data and give an excellent agreement

  17. Riverbank filtration for the treatment of highly turbid Colombian rivers

    Science.gov (United States)

    Gutiérrez, Juan Pablo; van Halem, Doris; Rietveld, Luuk

    2017-05-01

    The poor quality of many Colombian surface waters forces us to seek alternative, sustainable treatment solutions with the ability to manage peak pollution events and to guarantee the uninterrupted provision of safe drinking water to the population. This review assesses the potential of using riverbank filtration (RBF) for the highly turbid and contaminated waters in Colombia, emphasizing water quality improvement and the influence of clogging by suspended solids. The suspended sediments may be favorable for the improvement of the water quality, but they may also reduce the production yield capacity. The cake layer must be balanced by scouring in order for an RBF system to be sustainable. The infiltration rate must remain high enough throughout the river-aquifer interface to provide the water quantity needed, and the residence time of the contaminants must be sufficient to ensure adequate water quality. In general, RBF seems to be a technology appropriate for use in highly turbid and contaminated surface rivers in Colombia, where improvements are expected due to the removal of turbidity, pathogens and to a lesser extent inorganics, organic matter and micro-pollutants. RBF has the potential to mitigate shock loads, thus leading to the prevention of shutdowns of surface water treatment plants. In addition, RBF, as an alternative pretreatment step, may provide an important reduction in chemical consumption, considerably simplifying the operation of the existing treatment processes. However, clogging and self-cleansing issues must be studied deeper in the context of these highly turbid waters to evaluate the potential loss of abstraction capacity yield as well as the development of different redox zones for efficient contaminant removal.

  18. MODIS Retrieval of Aerosol Optical Depth over Turbid Coastal Water

    Directory of Open Access Journals (Sweden)

    Yi Wang

    2017-06-01

    Full Text Available We present a new approach to retrieve Aerosol Optical Depth (AOD using the Moderate Resolution Imaging Spectroradiometer (MODIS over the turbid coastal water. This approach supplements the operational Dark Target (DT aerosol retrieval algorithm that currently does not conduct AOD retrieval in shallow waters that have visible sediments or sea-floor (i.e., Class 2 waters. Over the global coastal water regions in cloud-free conditions, coastal screening leads to ~20% unavailability of AOD retrievals. Here, we refine the MODIS DT algorithm by considering that water-leaving radiance at 2.1 μm to be negligible regardless of water turbidity, and therefore the 2.1 μm reflectance at the top of the atmosphere is sensitive to both change of fine-mode and coarse-mode AODs. By assuming that the aerosol single scattering properties over coastal turbid water are similar to those over the adjacent open-ocean pixels, the new algorithm can derive AOD over these shallow waters. The test algorithm yields ~18% more MODIS-AERONET collocated pairs for six AERONET stations in the coastal water regions. Furthermore, comparison of the new retrieval with these AERONET observations show that the new AOD retrievals have equivalent or better accuracy than those retrieved by the MODIS operational algorithm’s over coastal land and non-turbid coastal water product. Combining the new retrievals with the existing MODIS operational retrievals yields an overall improvement of AOD over those coastal water regions. Most importantly, this refinement extends the spatial and temporal coverage of MODIS AOD retrievals over the coastal regions where 60% of human population resides. This expanded coverage is crucial for better understanding of impact of anthropogenic aerosol particles on coastal air quality and climate.

  19. The Estuary Guide. Level 3: High School. Draft.

    Science.gov (United States)

    Alexander, Glen; And Others

    Estuaries are marine systems that serve as nurseries for animals, links in the migratory pathways, and habitat for a complex community of organisms. This curriculum guide intended for use at the high school level seeks to teach what estuaries are; provide opportunities to practice decision-making that affects estuaries; and encourage students to…

  20. Improving navigability on the Kromme River Estuary: A choice ...

    African Journals Online (AJOL)

    Navigation of estuaries is a vitally important aspect of boating recreation in South Africa and elsewhere. This paper uses a choice experiment to estimate recreation values of the Kromme River Estuary, a popular estuary along South Africa's east coast. This valuation methodology allows for the identification of preferred ...

  1. Recovering low-turbidity cutting liquid from silicon slurry waste.

    Science.gov (United States)

    Tsai, Tzu-Hsuan; Shih, Yu-Pei

    2014-04-30

    In order to recover a low-turbidity polyalkylene glycol (PAG) liquid from silicon slurry waste by sedimentation, temperatures were adjusted, and acetone, ethanol or water was used as a diluent. The experimental results show that the particles in the waste would aggregate and settle readily by using water as a diluent. This is because particle surfaces had lower surface potential value and weaker steric stabilization in PAG-water than in PAG-ethanol or PAG-acetone solutions. Therefore, water is the suggested diluent for recovering a low-turbidity PAG (sedimentation. After 50 wt.% water-assisted sedimentation for 21 days, the solid content of the upper liquid reduced to 0.122 g/L, and the turbidity decreased to 44 NTU. The obtained upper liquid was then vacuum-distillated to remove water. The final recovered PAG with 0.37 NTU had similar viscosity and density to the unused PAG and could be reused in the cutting process. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Turbidity removal: Gravel and charcoal as roughing filtration media

    Directory of Open Access Journals (Sweden)

    Josiah A. Adeyemo

    2010-10-01

    Full Text Available Roughing filtration is an important pre-treatment process for wastewater, because it efficiently separates fine solid particles over prolonged periods, without the addition of chemicals. For this study, a pilot plant was designed at Delmas Coal Mine in the Mpumalanga province of South Africa. The design and sizing of the pilot plant was guided by Wegelin’s design criteria. Gravel was used as a control medium because it is one of the most commonly used roughing filter media and because it was used in developing the criteria. We compared the performance of gravel as a filter medium to that of another locally available material, charcoal, for the removal of turbidity in wastewater. The pilot plant was monitored continuously for 90 days from commissioning until the end of the project. The overall performance of the roughing filter in turbidity removal, using gravel or charcoal, was considered efficient for the pre-treatment of waste water. Charcoal performed slightly better than gravel as a filter medium for the removal of turbidity, possibly because charcoal has a slightly higher specific surface area and porosity than gravel, which could enhance sedimentation and other filtration processes, such as adsorption, respectively.

  3. Clearing muddied waters: Capture of environmental DNA from turbid waters.

    Directory of Open Access Journals (Sweden)

    Kelly E Williams

    Full Text Available Understanding the differences in efficiencies of various methods to concentrate, extract, and amplify environmental DNA (eDNA is vital for best performance of eDNA detection. Aquatic systems vary in characteristics such as turbidity, eDNA concentration, and inhibitor load, thus affecting eDNA capture efficiency. Application of eDNA techniques to the detection of terrestrial invasive or endangered species may require sampling at intermittent water sources that are used for drinking and cooling; these water bodies may often be stagnant and turbid. We present our best practices technique for the detection of wild pig eDNA in water samples, a protocol that will have wide applicability to the detection of elusive vertebrate species. We determined the best practice for eDNA capture in a turbid water system was to concentrate DNA from a 15 mL water sample via centrifugation, purify DNA with the DNeasy mericon Food kit, and remove inhibitors with Zymo Inhibitor Removal Technology columns. Further, we compared the sensitivity of conventional PCR to quantitative PCR and found that quantitative PCR was more sensitive in detecting lower concentrations of eDNA. We show significant differences in efficiencies among methods in each step of eDNA capture, emphasizing the importance of optimizing best practices for the system of interest.

  4. Fingerprinting Persistent Turbidity in Sheep Creek Reservoir, Owhyee, Nevada

    Science.gov (United States)

    Ransom, R. N.; Hooper, R. L.; Kerner, D.; Nicols, S.

    2007-12-01

    Sheep Creek Reservoir near Owyhee, NV is historically a quality rainbow trout fishery. Persistent high-turbidity has been an issue since a major storm event in 2005 resulted in surface water runoff into the Reservoir. The high turbidity is adversely impacting the quality of the fishery. Initial turbidity measurements in 2005 were upwards of 80NTU and these numbers have only decreased to 30NTU over the past two summers. Field parameters indicate the turbidity is associated with high total suspended solids (TSS) and not algae. Five water samples collected from around the reservoir during June, 2007 indicated uniform TSS values in the range of 5 to 12mg/L and oriented powder x-ray diffraction(XRD) and transmission electron microscopy(TEM) analyses of suspended sediment shows very uniform suspended particulate mineralogy including smectite, mixed layer illite/smectite (I/S), discrete illite, lesser amounts of kaolin, sub-micron quartz and feldspar. Diatoms represent a ubiquitous but minor component of the suspended solids. Six soil samples collected from possible source areas around the reservoir were analyzed using both XRD and TEM to see if a source area for the suspended solids could be unambiguously identified. Soils on the east side of the reservoir contain smectite and mixed layer I/S but very little of the other clays. The less than 2 micron size fraction from soils collected from a playa on the topographic bench immediately to the west of the reservoir show a mineralogic finger-print essentially identical to the current suspended sediment. The suspended sediment probably originates on the bench to the west of the reservoir and cascades into the reservoir over the topographic break during extreme storm events. The topographic relief, short travel distance and lack of a suitable vegetated buffer zone to the west are all consistent with a primary persistent suspended sediment source from the west. Identification of the sediment source allows for design of a cost

  5. INTEGRATED WATER MONITORING TO SUPPORT THE MANAGEMENT OF HEALTHY SEGARA ANAKAN ESTUARY

    Directory of Open Access Journals (Sweden)

    Sri Noegrahati

    2007-03-01

    Full Text Available ABSTRACT Estuaries provide vital nesting and feeding habitats for many aquatic plants and animals, therefore suitable methods are needed for monitoring the changes in estuarine waters to keep the health of coastal habitats. Limitations in understanding the relationship between discrete physicochemical measurements and cause of the alteration in the quality and functioning of an ecosystem, has lead to the integration of physicochemical and biological monitoring. In this work, spatial time series integrated monitoring of Southern part of Segara Anakan Estuary, Central Java, Indonesia, was carried out from August 2003 to May 2004. The parameters were measured at the lowest water depth. Dramatic changes in physicochemical parameters of salinity, total suspended solids, turbidity and biological parameters of phytoplankton diversity, density was observed during dry season (August-September 2003 and wet season (December 2003-March 2004, while the changes in parameters of organics (DO, BOD and COD and nutrients (N-NH3 N-NO and P were not significant. The difference of freshwater influx into the estuary caused higher salinity in dry season (25 to 2 ppt and faster water velocity in wet season (0,4 to 0,2 m/detik. The higher rainfall and faster water velocity in wet season caused more re-aeration via the water surface, therefore, photosynthetic production, measured as increase rate of DO in day time, could be assessed only in dry season. Limitation of phytoplankton ability to carry out photosynthesis in wet season, as observed by the decrease of the daytime CO consumption rate, were due to the drastic increase of turbidity (0,8 to 14,1 NTU caused by total suspended solids transported with the freshwater influx. In other turn, this limitation caused the decrease of phytoplankton diversity and density. Considering that healthy estuaries are critical for the continued survival of many species of fish and other aquatic life, and phytoplankton forms the base of

  6. Estuary wader capacity following severe weather mortality

    International Nuclear Information System (INIS)

    Clark, J.A.; Baillie, S.R.; Clark, N.A.; Langston, R.H.W.

    1993-01-01

    The building of a tidal power barrage across an estuary may lead to substantial changes in its ecology. Many of Britain's estuaries hold internationally important numbers of waders. Careful consideration, therefore, needs to be given to the likely effects of tidal power barrages on wader populations. The opportunity for increased understanding of the mechanisms which govern wader populations was provided by a period of severe winter weather in 1991, which resulted in a substantial mortality of waders in eastern England. Such conditions are known to be stressful to birds and the study objectives were to investigate both the effects of and recovery from severe weather. (author)

  7. Towards environmental management of water turbidity within open coastal waters of the Great Barrier Reef.

    Science.gov (United States)

    Macdonald, Rachael K; Ridd, Peter V; Whinney, James C; Larcombe, Piers; Neil, David T

    2013-09-15

    Water turbidity and suspended sediment concentration (SSC) are commonly used as part of marine monitoring and water quality plans. Current management plans utilise threshold SSC values derived from mean-annual turbidity concentrations. Little published work documents typical ranges of turbidity for reefs within open coastal waters. Here, time-series turbidity measurements from 61 sites in the Great Barrier Reef (GBR) and Moreton Bay, Australia, are presented as turbidity exceedance curves and derivatives. This contributes to the understanding of turbidity and SSC in the context of environmental management in open-coastal reef environments. Exceedance results indicate strong spatial and temporal variability in water turbidity across inter/intraregional scales. The highest turbidity across 61 sites, at 50% exceedance (T50) is 15.3 NTU and at 90% exceedance (T90) 4.1 NTU. Mean/median turbidity comparisons show strong differences between the two, consistent with a strongly skewed turbidity regime. Results may contribute towards promoting refinement of water quality management protocols. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Turbid releases from Glen Canyon Dam, Arizona, following rainfall-runoff events of September 2013

    Science.gov (United States)

    Wildman, Richard A.; Vernieu, William

    2017-01-01

    Glen Canyon Dam is a large dam on the Colorado River in Arizona. In September 2013, it released turbid water following intense thunderstorms in the surrounding area. Turbidity was >15 nephelometric turbidity units (NTU) for multiple days and >30 NTU at its peak. These unprecedented turbid releases impaired downstream fishing activity and motivated a rapid-response field excursion. At 5 locations upstream from the dam, temperature, specific conductance, dissolved oxygen, chlorophyll a, and turbidity were measured in vertical profiles. Local streamflow and rainfall records were retrieved, and turbidity and specific conductance data in dam releases were evaluated. Profiling was conducted to determine possible sources of turbidity from 3 tributaries nearest the dam, Navajo, Antelope, and Wahweap creeks, which entered Lake Powell as interflows during this study. We discuss 4 key conditions that must have been met for tributaries to influence turbidity of dam releases: tributary flows must have reached the dam, tributary flows must have been laden with sediment, inflow currents must have been near the depth of dam withdrawals, and the settling velocity of particles must have been slow. We isolate 2 key uncertainties that reservoir managers should resolve in future similar studies: the reach of tributary water into the reservoir thalweg and the distribution of particle size of suspended sediment. These uncertainties leave the source of the turbidity ambiguous, although an important role for Wahweap Creek is possible. The unique combination of limnological factors we describe implies that turbid releases at Glen Canyon Dam will continue to be rare.

  9. Use of Moringa oleifera seeds for the removal of turbidity of water supply

    Directory of Open Access Journals (Sweden)

    Gustavo Lopes Muniz

    2015-04-01

    Full Text Available Water used for human consumption may contain various impurities and solid particles in suspension that increase its turbidity level. Moringa oleifera Lam is a plant that has the potential to be used as coagulating agent in removing turbidity. The objective of this work was to evaluate the efficiency of Moringa oleifera seeds used in shells and without shells in the removal of turbidity from waters with different degrees of turbidity. Waters were used with 70, 250 and 400 initial NTU obtained synthetically. The extract of moringa seeds was prepared using unshelled and shelled seeds, seeking a simplified procedure and practice. The sedimentation times and dose of coagulant solution used were based on existing recommendations in the literature. All treatments were performed with three replicates and the averages depicted in graphs. The results showed that the use of extract of moringa seeds in shells was more efficient than with unshelled seeds in the removal of turbidity of all treatments and that the shelled seeds removed more than 99% of the initial turbidity of the water samples. Furthermore, there was a direct relationship between turbidity removal efficiency and the level of initial turbidity of the samples. The seeds were more efficient in removing turbidity of the water with a higher level of initial turbidity.

  10. The relationship between sediment and plutonium budgets in a small macrotidal estuary: Esk Estuary, Cumbria, UK

    International Nuclear Information System (INIS)

    Kelly, M.; Emptage, M.; Mudge, S.; Bradshaw, K.; Hamilton-Taylor, J.

    1991-01-01

    During a spring tide, measurements were made of sediment and 239,240 Pu discharges through a cross-section of the Esk estuary. These indicated that over the full tidal cycle, the inner estuary had a net gain of ca. 18 t of sediment and ca. 85 MBq of particulate phase 239,240 Pu, and a probable net loss of ca. 1 to 2 MBq of solution phase 239,240 Pu. Each of these was the net result of large gross discharges of sediment and plutonium into and out of the estuary for which the sea was the main source, with eroded estuarine sediment providing an additional minor source of sediment, of particulate phase plutonium and, via desorption, of solution phase plutonium. A net input with each tide, of sediment and its associated radionuclides, is considered to be typical for the Esk estuary under the normal conditions of low river flows. (author)

  11. Establishing nursery estuary otolith geochemical tags for Sea Bass (Dicentrarchus labrax): Is temporal stability estuary dependent?

    Science.gov (United States)

    Ryan, Diarmuid; Wögerbauer, Ciara; Roche, William

    2016-12-01

    The ability to determine connectivity between juveniles in nursery estuaries and adult populations is an important tool for fisheries management. Otoliths of juvenile fish contain geochemical tags, which reflect the variation in estuarine elemental chemistry, and allow discrimination of their natal and/or nursery estuaries. These tags can be used to investigate connectivity patterns between juveniles and adults. However, inter-annual variability of geochemical tags may limit the accuracy of nursery origin determinations. Otolith elemental composition was used to assign a single cohort of 0-group sea bass Dicentrarchus labrax to their nursery estuary thus establishing an initial baseline for stocks in waters around Ireland. Using a standard LDFA model, high classification accuracies to nursery sites (80-88%) were obtained. Temporal stability of otolith geochemical tags was also investigated to assess if annual sampling is required for connectivity studies. Geochemical tag stability was found to be strongly estuary dependent.

  12. Estuary fish data - Juvenile salmon in migratory corridors of lower Columbia River estuary

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sampling juvenile salmon and associated fishes in open waters of the lower Columbia River estuary. Field work includes bi-weekly sampling during the spring...

  13. Hyperspectral remote sensing and long term monitoring reveal watershed-estuary ecosystem interactions

    Science.gov (United States)

    Hestir, E. L.; Schoellhamer, D. H.; Santos, M. J.; Greenberg, J. A.; Morgan-King, T.; Khanna, S.; Ustin, S.

    2016-02-01

    Estuarine ecosystems and their biogeochemical processes are extremely vulnerable to climate and environmental changes, and are threatened by sea level rise and upstream activities such as land use/land cover and hydrological changes. Despite the recognized threat to estuaries, most aspects of how change will affect estuaries are not well understood due to the poorly resolved understanding of the complex physical, chemical and biological processes and their interactions in estuarine systems. Remote sensing technologies such as high spectral resolution optical systems enable measurements of key environmental parameters needed to establish baseline conditions and improve modeling efforts. The San Francisco Bay-Delta is a highly modified estuary system in a state of ecological crisis due to the numerous threats to its sustainability. In this study, we used a combination of hyperspectral remote sensing and long-term in situ monitoring records to investigate how water clarity has been responding to extreme climatic events, anthropogenic watershed disturbances, and submerged aquatic vegetation (SAV) invasions. From the long-term turbidity monitoring record, we found that water clarity underwent significant increasing step changes associated with sediment depletion and El Nino-extreme run-off events. Hyperspectral remote sensing data revealed that invasive submerged aquatic pant species have facultative C3 and C4-like photosynthetic pathways that give them a competitive advantage under the changing water clarity conditions of the Bay-Delta system. We postulate that this adaptation facilitated the rapid expansion of SAV following the significant step changes in increasing water clarity caused by watershed disturbances and the 1982-1983 El Nino events. Using SAV maps from hyperspectral remote sensing, we estimate that SAV-water clarity feedbacks were responsible for 20-70% of the increasing water clarity trend in the Bay-Delta. Ongoing and future developments in airborne and

  14. Turbidity of mouthrinsed water as a screening index for oral malodor.

    Science.gov (United States)

    Ueno, Masayuki; Takeuchi, Susumu; Samnieng, Patcharaphol; Morishima, Seiji; Shinada, Kayoko; Kawaguchi, Yoko

    2013-08-01

    The objectives of this research were to examine the relationship between turbidity of mouthrinsed water and oral malodor, and to evaluate whether the turbidity could be used to screen oral malodor. The subjects were 165 oral malodor patients. Gas chromatography and organoleptic test (OT) were used for oral malodor measurement. Oral examination along with collection of saliva and quantification of bacteria was conducted. Turbidity of mouthrinsed water was measured with turbidimeter. Logistic regression with oral malodor status by OT as the dependent variable and receiver operating characteristic (ROC) analysis were performed. Turbidity had a significant association with oral malodor status. In addition, ROC analysis showed that the turbidity had an ability to screen for presence or absence of oral malodor. Turbidity could reflect or represent other influential variables of oral malodor and may be useful as a screening method for oral malodor. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Three-Dimensional Sediment Dynamics in Well-Mixed Estuaries: Importance of the Internally Generated Overtide, Spatial Settling Lag, and Gravitational Circulation

    Science.gov (United States)

    Wei, Xiaoyan; Kumar, Mohit; Schuttelaars, Henk M.

    2018-02-01

    To investigate the dominant sediment transport and trapping mechanisms, a semi-analytical three-dimensional model is developed resolving the dynamic effects of salt intrusion on sediment in well-mixed estuaries in morphodynamic equilibrium. As a study case, a schematized estuary with a converging width and a channel-shoal structure representative for the Delaware estuary is considered. When neglecting Coriolis effects, sediment downstream of the estuarine turbidity maximum (ETM) is imported into the estuary through the deeper channel and exported over the shoals. Within the ETM region, sediment is transported seaward through the deeper channel and transported landward over the shoals. The largest contribution to the cross-sectionally integrated seaward residual sediment transport is attributed to the advection of tidally averaged sediment concentrations by river-induced flow and tidal return flow. This contribution is mainly balanced by the residual landward sediment transport due to temporal correlations between the suspended sediment concentrations and velocities at the M2 tidal frequency. The M2 sediment concentration mainly results from spatial settling lag effects and asymmetric bed shear stresses due to interactions of M2 bottom velocities and the internally generated M4 tidal velocities, as well as the salinity-induced residual currents. Residual advection of tidally averaged sediment concentrations also plays an important role in the landward sediment transport. Including Coriolis effects hardly changes the cross-sectionally integrated sediment balance, but results in a landward (seaward) sediment transport on the right (left) side of the estuary looking seaward, consistent with observations from literature. The sediment transport/trapping mechanisms change significantly when varying the settling velocity and river discharge.

  16. Features at some significant estuaries of India

    Digital Repository Service at National Institute of Oceanography (India)

    Bhattathiri, P.M.A.

    in the second and 162 in the third. Most of the studies on various aspects have been confined to very few of these, and that too, mostly to minor ones. Very little work has been carried out from many of the estuaries of the major rivers. An overview...

  17. Radiological assessment of the Esk Estuary

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  18. Padilla Bay: The Estuary Guide. Level 2.

    Science.gov (United States)

    Friesem, Judy; Lynn, Valerie, Ed.

    Estuaries are marine systems that serve as nurseries for animals, links in the migratory pathways, and habitat for a complex community of organisms. This curriculum guide intended for use at the middle school level is designed for use with the on-site program developed by the Padilla Bay National Esturine Research Reserve (Washington). The guide…

  19. The environmental characteristics of the Ganga estuary

    Digital Repository Service at National Institute of Oceanography (India)

    SenGupta, R.; Murty, C.S.; Bhattathiri, P.M.A.

    This report presents physical, chemical and biological observations in the last 160 km stretch of river Ganga for period of 3 years. In the one-layer estuary the mixing is brought about by the horizontal gradient of the flow field closely associated...

  20. Restoration of the Golden Horn Estuary (Halic).

    Science.gov (United States)

    Coleman, Heather M; Kanat, Gurdal; Aydinol Turkdogan, F Ilter

    2009-12-01

    Restoration of the iconic Golden Horn Estuary in Istanbul, Turkey was a substantial political, logistical, ecological, and social challenge. Forty years of uncontrolled industrial and urban growth resulted in thick layers of anoxic sediment, toxic bacteria, strong hydrogen sulfide odor, and ecologically unlivable conditions. The major components of restoration, spanning two decades, have included (1) demolition and relocation of industries and homes along the shore, (2) creation of wastewater infrastructure, (3) removal of anoxic sludge from the estuary, (4) removal of a floating bridge that impeded circulation, and (5) creation of cultural and social facilities. Although Turkey is not known as an environmental leader in pollution control, the sum of these efforts was largely successful in revitalizing the area through dramatic water quality improvement. Consequently, the estuary is once again inhabitable for aquatic life as well as amenable to local resource users and foreign visitors, and Istanbul has regained a lost sense of cultural identity. This paper focuses on literature review and personal interviews to discuss the causes of degradation, solutions employed to rehabilitate the estuary, and subsequent physicochemical, ecological, and social changes.

  1. Estuaries and Tidal Marshes. Habitat Pac.

    Science.gov (United States)

    Fish and Wildlife Service (Dept. of Interior), Washington, DC.

    This educational packet consists of an overview, three lesson plans, student data sheets, and a poster. The overview examines estuaries and tidal or salt marshes by discussing the plants and animals in these habitats, marsh productivity, benefits and management of the habitats, historical aspects, and development and pollution. A glossary and list…

  2. Geochemical studies in the Godavari Estuary, India

    Digital Repository Service at National Institute of Oceanography (India)

    Somayajulu, B.L.K.; Martin, J.M.; Eisma, D.; Thomas, A.J.; Borole, D.V.; Rao, K.S.

    are reported. The DOC and Fe concentrations are lower compared with those in other estuaries of the world and are below the average value reported for world rivers. Silicon behaves non-conservatively; its depletion which is most likely due to biological...

  3. Flushing characteristics of Mahim river estuary (Bombay)

    Digital Repository Service at National Institute of Oceanography (India)

    Sabnis, M.M; Zingde, M

    to the influence of wastewater. Flushing time of 19 tidal cycles was estimated by applying modified tidal prism method. After a large number of tidal cycles the estuary would retain 9.3x10 super(4) m super(3) of wastewater which was over 15% of the spring high tide...

  4. Influence of estuaries on shelf sediment texture

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, R.R.; Hashimi, N.H.

    on the coast. Offshore from regions where there are a large number of estuaries, the inner shelf sediments are fine grained (average mean size 5.02 phi, 0.03 mm), rich in organic matter ( 2%) and low in calcium carbonate ( 25%). In contrast, in regions...

  5. Carbon dioxide emissions from Indian monsoonal estuaries

    Digital Repository Service at National Institute of Oceanography (India)

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

    estuaries. The mean pCO sub(2) and particulate organic carbon (POC) showed positive relation with rate of discharge suggesting availability of high quantities of organic matter that led to enhanced microbial decomposition. The annual CO sub(2) fluxes from...

  6. Hydrodynamics of the Bot river estuary revisited

    CSIR Research Space (South Africa)

    Van Niekerk, L

    2005-01-01

    Full Text Available For the past 20 years management of the Bot/Kleinmond estuarine system in the south-western Cape has been based on the premise that, barring intervention, the estuary was naturally evolving into a freshwater coastal lake. This paper presents...

  7. Sedimentation in a river dominated estuary

    CSIR Research Space (South Africa)

    Cooper, JAG

    1993-10-01

    Full Text Available The Mgeni Estuary on the wave dominated cast coast of South Africa occupies a narrow, bedrock confined, alluvial valley and is partially blocked at the coast by an elongate sandy barrier. Fluvial sediment extends to the barrier and marine depositon...

  8. Mouth Bar Formation in Yangtze River Estuary

    NARCIS (Netherlands)

    Wei, C.

    2002-01-01

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

  9. 76 FR 8345 - Endangered and Threatened Species; Recovery Plan Module for Columbia River Estuary Salmon and...

    Science.gov (United States)

    2011-02-14

    ... and Threatened Species; Recovery Plan Module for Columbia River Estuary Salmon and Steelhead AGENCY.... ACTION: Notice of availability; recovery plan module for Columbia River estuary salmon and steelhead... Plan Module for Salmon and Steelhead (Estuary Module). The Estuary Module addresses the estuary...

  10. Relationships between aquatic vegetation and water turbidity: A field survey across seasons and spatial scales

    OpenAIRE

    Austin, ?sa N.; Hansen, Joakim P.; Donadi, Serena; Ekl?f, Johan S.

    2017-01-01

    Field surveys often show that high water turbidity limits cover of aquatic vegetation, while many small-scale experiments show that vegetation can reduce turbidity by decreasing water flow, stabilizing sediments, and competing with phytoplankton for nutrients. Here we bridged these two views by exploring the direction and strength of causal relationships between aquatic vegetation and turbidity across seasons (spring and late summer) and spatial scales (local and regional), using causal model...

  11. Natural fluctuations in nearshore turbidity and the relative influences of beach renourishment

    OpenAIRE

    Dompe, Philip E.

    1993-01-01

    Turbidity is a measure of the clarity of water. Turbidity depends upon the scattering and absorption of light by suspended particles. The focus of this study was to obtain quantitative measurements of turbidity in the nearshore zone, along with measurements of associated wave parameters and currents occurring naturally and during a beach nourishment project. The objectives were to make quantitative and qualitative comparisons between natural events and those induced by the dred...

  12. [Experimental research of turbidity influence on water quality monitoring of COD in UV-visible spectroscopy].

    Science.gov (United States)

    Tang, Bin; Wei, Biao; Wu, De-Cao; Mi, De-Ling; Zhao, Jing-Xiao; Feng, Peng; Jiang, Shang-Hai; Mao, Ben-Jiang

    2014-11-01

    Eliminating turbidity is a direct effect spectroscopy detection of COD key technical problems. This stems from the UV-visible spectroscopy detected key quality parameters depend on an accurate and effective analysis of water quality parameters analytical model, and turbidity is an important parameter that affects the modeling. In this paper, we selected formazine turbidity solution and standard solution of potassium hydrogen phthalate to study the turbidity affect of UV--visible absorption spectroscopy detection of COD, at the characteristics wavelength of 245, 300, 360 and 560 nm wavelength point several characteristics with the turbidity change in absorbance method of least squares curve fitting, thus analyzes the variation of absorbance with turbidity. The results show, In the ultraviolet range of 240 to 380 nm, as the turbidity caused by particle produces compounds to the organics, it is relatively complicated to test the turbidity affections on the water Ultraviolet spectra; in the visible region of 380 to 780 nm, the turbidity of the spectrum weakens with wavelength increases. Based on this, this paper we study the multiplicative scatter correction method affected by the turbidity of the water sample spectra calibration test, this method can correct water samples spectral affected by turbidity. After treatment, by comparing the spectra before, the results showed that the turbidity caused by wavelength baseline shift points have been effectively corrected, and features in the ultraviolet region has not diminished. Then we make multiplicative scatter correction for the three selected UV liquid-visible absorption spectroscopy, experimental results shows that on the premise of saving the characteristic of the Ultraviolet-Visible absorption spectrum of water samples, which not only improve the quality of COD spectroscopy detection SNR, but also for providing an efficient data conditioning regimen for establishing an accurate of the chemical measurement methods.

  13. Oceanic turbidity and chlorophyll as inferred from ERTS-1 observations

    Science.gov (United States)

    Curran, R. J.

    1973-01-01

    Spectral signatures of phytoplankton and other obscuring effects are considered in order to determine how to best use satellite data. The results of this study were then used to analyze the spectral data obtained from the ERTS-1 multispectral scanner (MSS). The analyzed satellite data were finally compared with surface ship measurements of chlorophyll concentration. It was found that the effects of water turbidity on the multispectral imagery can be discriminated by rationing the two shortest wavelength channels so that the effect of phytoplankton is enhanced.

  14. Landsat Thematic Mapper monitoring of turbid inland water quality

    Science.gov (United States)

    Lathrop, Richard G., Jr.

    1992-01-01

    This study reports on an investigation of water quality calibration algorithms under turbid inland water conditions using Landsat Thematic Mapper (TM) multispectral digital data. TM data and water quality observations (total suspended solids and Secchi disk depth) were obtained near-simultaneously and related using linear regression techniques. The relationships between reflectance and water quality for Green Bay and Lake Michigan were compared with results for Yellowstone and Jackson Lakes, Wyoming. Results show similarities in the water quality-reflectance relationships, however, the algorithms derived for Green Bay - Lake Michigan cannot be extrapolated to Yellowstone and Jackson Lake conditions.

  15. Nutrient budgets for large Chinese estuaries

    Directory of Open Access Journals (Sweden)

    S. M. Liu

    2009-10-01

    Full Text Available Chinese rivers deliver about 5–10% of global freshwater input and 15–20% of the global continental sediment to the world ocean. We report the riverine fluxes and concentrations of major nutrients (nitrogen, phosphorus, and silicon in the rivers of the contiguous landmass of China and Korea in the northeast Asia. The rivers are generally enriched with dissolved inorganic nitrogen (DIN and depleted in dissolved inorganic phosphate (PO43− with very high DIN: PO43− concentration ratios. DIN, phosphorus, and silicon levels and loads in rivers are mainly affected by agriculture activities and urbanization, anthropogenic activities and adsorption on particulates, and rock types, climate and physical denudation intensity, respectively. Nutrient transports by rivers in the summer are 3–4 times higher than those in the winter with the exception of NH4+. The flux of NH4+ is rather constant throughout the year due to the anthropogenic sources such as the sewer discharge. As nutrient composition has changed in the rivers, ecosystems in estuaries and coastal sea have also changed in recent decades. Among the changes, a shift of limiting nutrients from phosphorus to nitrogen for phytoplankton production with urbanization is noticeable and in some areas silicon becomes the limiting nutrient for diatom productivity. A simple steady-state mass-balance box model was employed to assess nutrient budgets in the estuaries. The major Chinese estuaries export <15% of nitrogen, <6% of phosphorus required for phytoplankton production and ~4% of silicon required for diatom growth in the Chinese Seas (Bohai, Yellow Sea, East China Sea, South China Sea. This suggests that land-derived nutrients are largely confined to the immediate estuaries, and ecosystem in the coastal sea beyond the estuaries is mainly supported by other nutrient sources such as regeneration, open ocean and

  16. Assessing the risk posed by high-turbidity water to water supplies.

    Science.gov (United States)

    Chang, Chia-Ling; Liao, Chung-Sheng

    2012-05-01

    The objective of this study is to assess the risk of insufficient water supply posed by high-turbidity water. Several phenomena can pose risks to the sufficiency of a water supply; this study concerns risks to water treatment plants from particular properties of rainfall and raw water turbidity. High-turbidity water can impede water treatment plant operations; rainfall properties can influence the degree of soil erosion. Thus, water turbidity relates to rainfall characteristics. Exceedance probabilities are presented for different rainfall intensities and turbidities of water. When the turbidity of raw water is higher than 5,000 NTU, it can cause operational problems for a water treatment plant. Calculations show that the turbidity of raw water at the Ban-Sin water treatment plant will be higher than 5,000 NTU if the rainfall intensity is larger than 165 mm/day. The exceedance probability of high turbidity (turbidity >5,000 NTU) in the Ban-Sin water treatment plant is larger than 10%. When any water treatment plant cannot work regularly, its ability to supply water to its customers is at risk.

  17. Developmental plasticity in vision and behavior may help guppies overcome increased turbidity.

    Science.gov (United States)

    Ehlman, Sean M; Sandkam, Benjamin A; Breden, Felix; Sih, Andrew

    2015-12-01

    Increasing turbidity in streams and rivers near human activity is cause for environmental concern, as the ability of aquatic organisms to use visual information declines. To investigate how some organisms might be able to developmentally compensate for increasing turbidity, we reared guppies (Poecilia reticulata) in either clear or turbid water. We assessed the effects of developmental treatments on adult behavior and aspects of the visual system by testing fish from both developmental treatments in turbid and clear water. We found a strong interactive effect of rearing and assay conditions: fish reared in clear water tended to decrease activity in turbid water, whereas fish reared in turbid water tended to increase activity in turbid water. Guppies from all treatments decreased activity when exposed to a predator. To measure plasticity in the visual system, we quantified treatment differences in opsin gene expression of individuals. We detected a shift from mid-wave-sensitive opsins to long wave-sensitive opsins for guppies reared in turbid water. Since long-wavelength sensitivity is important in motion detection, this shift likely allows guppies to salvage motion-detecting abilities when visual information is obscured in turbid water. Our results demonstrate the importance of developmental plasticity in responses of organisms to rapidly changing environments.

  18. Comparison of Water Turbidity Removal Efficiencies of Descurainia Sophia Seed Extract and Ferric chloride

    Directory of Open Access Journals (Sweden)

    Mazyar Peyda

    2016-03-01

    Full Text Available Background Turbidity removal using inorganic coagulants such as iron and aluminum salts in water treatment processes causes environmental and human health concern. Historically, the use of natural coagulant to purify turbid water has been practiced for a long time. Recent research indicates that Descurainia Sophia seed can be effectively used as a natural coagulant to remove water turbidity. Method: In this work, turbidity removal efficiency of Descurainia Sophia seed extract was compared with Ferric chloride. Experiments were performed in laboratory scale. The coagulation experiments were done with kaolin as a model soil to produce turbidity in distilled water. The turbidity removal efficiency of Descurainia Sophia seed extract and Ferric chloride were conducted with jar test apparatus. In all experiments, initial turbidity was kept constant 100(NTU. Optimum combination of independent variables was used to compare two different types of coagulants. Result: The obtained results showed that Ferric chloride could remove 89.75% of the initial turbidity, while in case of Descurainia Sophia this value was 43.13%. The total organic carbon (TOC analysis of the treated water using seed extract showed an increased concentration of TOC equal to 0.99 mg/L. Conclusions: This research has shown that Descurainia Sophia seed extract has an acceptable potential in the coagulation/flocculation process to treat turbid water.

  19. Interrelation of surface tension, optical turbidity, and color of operational transformer oils

    International Nuclear Information System (INIS)

    L’vov, S. Yu.; Lyut’ko, E. O.; Lankau, Ya. V.; Komarov, V. B.; Seliverstov, A. F.; Bondareva, V. N.; L’vov, Yu. N.; L’vov, M. Yu.; Ershov, B. G.

    2011-01-01

    Measurements of the acidity, optical turbidity, surface tension, and color of transformer oil from 54 power transformers, autotransformers, and shunt reactors are reported. Changes in surface tension, optical turbidity, and color are found to obey adequate linear correlations, while the acidity has no correlation with any of these properties. Numerical criteria for the maximum permissible state (quality) of the oil with respect to optical turbidity and color are obtained. Recommendations to operating staff are provided for cases in which the criteria for optical turbidity and color are exceeded.

  20. Detection limits for nanoparticles in solution with classical turbidity spectra

    Science.gov (United States)

    Le Blevennec, G.

    2013-09-01

    Detection of nanoparticles in solution is required to manage safety and environmental problems. Spectral transmission turbidity method has now been known for a long time. It is derived from the Mie Theory and can be applied to any number of spheres, randomly distributed and separated by large distance compared to wavelength. Here, we describe a method for determination of size, distribution and concentration of nanoparticles in solution using UV-Vis transmission measurements. The method combines Mie and Beer Lambert computation integrated in a best fit approximation. In a first step, a validation of the approach is completed on silver nanoparticles solution. Verification of results is realized with Transmission Electronic Microscopy measurements for size distribution and an Inductively Coupled Plasma Mass Spectrometry for concentration. In view of the good agreement obtained, a second step of work focuses on how to manage the concentration to be the most accurate on the size distribution. Those efficient conditions are determined by simple computation. As we are dealing with nanoparticles, one of the key points is to know what the size limits reachable are with that kind of approach based on classical electromagnetism. In taking into account the transmission spectrometer accuracy limit we determine for several types of materials, metals, dielectrics, semiconductors the particle size limit detectable by such a turbidity method. These surprising results are situated at the quantum physics frontier.

  1. A Reflectance Model for Relatively Clear and Turbid Waters

    Directory of Open Access Journals (Sweden)

    S. P. Tiwari

    2013-02-01

    Full Text Available Accurate modeling of spectral remote sensing reflectance (Rrs is of great interest for ocean colour studies in highly turbid and relatively clear waters. In this work a semianalytical model that simulates the spectral curves of remote sensing reflectance of these waters is developed based on the inherent optical properties (IOPs and f and Q factors. For accommodating differences in the optical properties of the water and accounting for their directional variations, IOPs and f and Q factors are derived as a function of phytoplankton pigments, suspended sediments and solar zenith angle. Results of this model are compared with in-situ bio-optical data collected at 83 stations encompassing highly turbid/relatively cleared waters of the South Sea of Korea. Measured and modeled remote sensing reflectances agree favorably in both magnitude and spectral shape, with considerably low errors (mean relative error MRE -0.0327; root mean square error RMSE 0.205, bias -0.0727 and slope 1.15 and correlation coefficient R2 0.74. These results suggest that the new model has the ability to reproduce measured reflectance values and has potentially profound implications for remote sensing of complex waters in this region.

  2. Quantitative polarized Raman spectroscopy in highly turbid bone tissue.

    Science.gov (United States)

    Raghavan, Mekhala; Sahar, Nadder D; Wilson, Robert H; Mycek, Mary-Ann; Pleshko, Nancy; Kohn, David H; Morris, Michael D

    2010-01-01

    Polarized Raman spectroscopy allows measurement of molecular orientation and composition and is widely used in the study of polymer systems. Here, we extend the technique to the extraction of quantitative orientation information from bone tissue, which is optically thick and highly turbid. We discuss multiple scattering effects in tissue and show that repeated measurements using a series of objectives of differing numerical apertures can be employed to assess the contributions of sample turbidity and depth of field on polarized Raman measurements. A high numerical aperture objective minimizes the systematic errors introduced by multiple scattering. We test and validate the use of polarized Raman spectroscopy using wild-type and genetically modified (oim/oim model of osteogenesis imperfecta) murine bones. Mineral orientation distribution functions show that mineral crystallites are not as well aligned (pbones (28+/-3 deg) compared to wild-type bones (22+/-3 deg), in agreement with small-angle X-ray scattering results. In wild-type mice, backbone carbonyl orientation is 76+/-2 deg and in oim/oim mice, it is 72+/-4 deg (p>0.05). We provide evidence that simultaneous quantitative measurements of mineral and collagen orientations on intact bone specimens are possible using polarized Raman spectroscopy.

  3. Turbid Media Extinction Coefficient for Near-Infrared Laser Radiation

    International Nuclear Information System (INIS)

    Dreischuh, T; Gurdev, L; Vankov, O; Stoyanov, D; Avramov, L

    2015-01-01

    In this work, extended investigations are performed of the extinction coefficient of Intralipid-20% dilutions in distilled water depending on the Intralipid concentration, for laser radiation wavelengths in the red and near-infrared regions covering the so-called tissue optical window. The extinction is measured by using an approach we have developed recently based on the features of the spatial intensity distribution of laser-radiation beams propagating through semi-infinite turbid media. The measurements are conducted using separately two dilution- containing plexiglass boxes of different sizes and volumes, in order to prove the appropriateness of the assumption of semi-infinite turbid medium. The experimental results for the extinction are in agreement with our previous results and with empiric formulae found by other authors concerning the wavelength dependence of the scattering coefficient of Intralipid – 10% and Intralipid – 20%. They are also in agreement with known data of the water absorptance. It is estimated as well that the wavelengths around 1320 nm would be advantageous for deep harmless sensing and diagnostics of tissues

  4. Dynamics of circulation and salt balance in the upper reaches of Periyar river estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Varma, P.U.; Pylee, A.; Sankaranarayanan, V.N.

    The Eulerian residual currents of the upper reaches of Periyar estuary (Kerala, India) were directed down the estuary throughout the water column during the monsoon season. During the summer months the residual flow was directed up the estuary...

  5. Plankton composition in two estuaries of the Konkan coast during premonsoon season

    Digital Repository Service at National Institute of Oceanography (India)

    Achuthankutty, C.T.; Nair, S.R.S.; Devassy, V.P.; Nair, V.R.

    abundant at the mouth region. Zooplankton biomass was relatively high in the Kajvi Estuary and all the major groups occurred in high density throughout this estuary. In the Shastri Estuary, the zooplankton biomass was relatively lower and all the major...

  6. Technical note: False low turbidity readings from optical probes during high suspended-sediment concentrations

    Science.gov (United States)

    Voichick, Nicholas; Topping, David; Griffiths, Ronald

    2018-01-01

    Turbidity, a measure of water clarity, is monitored for a variety of purposes including (1) to help determine whether water is safe to drink, (2) to establish background conditions of lakes and rivers and detect pollution caused by construction projects and stormwater discharge, (3) to study sediment transport in rivers and erosion in catchments, (4) to manage siltation of water reservoirs, and (5) to establish connections with aquatic biological properties, such as primary production and predator–prey interactions. Turbidity is typically measured with an optical probe that detects light scattered from particles in the water. Probes have defined upper limits of the range of turbidity that they can measure. The general assumption is that when turbidity exceeds this upper limit, the values of turbidity will be constant, i.e., the probe is pegged; however, this assumption is not necessarily valid. In rivers with limited variation in the physical properties of the suspended sediment, at lower suspended-sediment concentrations, an increase in suspended-sediment concentration will cause a linear increase in turbidity. When the suspended-sediment concentration in these rivers is high, turbidity levels can exceed the upper measurement limit of an optical probe and record a constant pegged value. However, at extremely high suspended-sediment concentrations, optical turbidity probes do not necessarily stay pegged at a constant value. Data from the Colorado River in Grand Canyon, Arizona, USA, and a laboratory experiment both demonstrate that when turbidity exceeds instrument-pegged conditions, increasing suspended-sediment concentration (and thus increasing turbidity) may cause optical probes to record decreasing false turbidity values that appear to be within the valid measurement range of the probe. Therefore, under high-turbidity conditions, other surrogate measurements of turbidity (e.g., acoustic-attenuation measurements or suspended-sediment samples

  7. Effects of water turbidity and different temperatures on oxidative stress in caddisfly (Stenopsyche marmorata) larvae.

    Science.gov (United States)

    Suzuki, Jumpei; Imamura, Masahiro; Nakano, Daisuke; Yamamoto, Ryosuke; Fujita, Masafumi

    2018-07-15

    Anthropogenic water turbidity derived from suspended solids (SS) is caused by reservoir sediment management practices such as drawdown flushing. Turbid water induces stress in many aquatic organisms, but the effects of turbidity on oxidative stress responses in aquatic insects have not yet been demonstrated. Here, we examined antioxidant responses, oxidative damage, and energy reserves in caddisfly (Stenopsyche marmorata) larvae exposed to turbid water (0 mg SS L -1 , 500 mg SS L -1 , and 2000 mg SS L -1 ) at different temperatures. We evaluated the combined effects of turbid water and temperature by measuring oxidative stress and using metabolic biomarkers. No turbidity level was significantly lethal to S. marmorata larvae. Moreover, there were no significant differences in antioxidant response or oxidative damage between the control and turbid water treatments at a low temperature (10 °C). However, at a high temperature (25 °C), turbid water modulated the activity of the antioxidant enzymes superoxide dismutase and catalase and the oxygen radical absorbance capacity as an indicator of the redox state of the insect larvae. Antioxidant defenses require energy, and high temperature was associated with low energy reserves, which might limit the capability of organisms to counteract reactive oxygen species. Moreover, co-exposure to turbid water and high temperature caused fluctuation of antioxidant defenses and increased the oxidative damage caused by the production of reactive oxygen species. Furthermore, the combined effect of high temperature and turbid water on antioxidant defenses and oxidative damage was larger than the individual effects. Therefore, our results demonstrate that exposure to both turbid water and high temperature generates additive and synergistic interactions causing oxidative stress in this aquatic insect species. Copyright © 2018. Published by Elsevier B.V.

  8. Suspended particulate matter flocculation in a natural tidal wetland located in the San Francisco Estuary

    Science.gov (United States)

    Saraceno, J.; Bergamaschi, B. A.; Wright, S. A.; Boss, E.; Downing, B. D.; Fleck, J.; Ganju, N. K.

    2011-12-01

    Suspended mineral and algal particles together comprise suspended particulate matter (SPM). The SPM size distribution influences the quantity and color of light penetration and the adsorption and transport of contaminants such as pesticides and metals. It is widely known that interaction with wetlands alters the size distribution and quality of particles through local primary production, differential settling and particle aggregation, however, our understanding of how tidal wetland processes affect SPM quantity and size spectra has been hampered by the difficulty of directly observing these parameters at tidal time scales. To evaluate how SPM concentration and size varied over tidal time scales and to better understand the relationship between organic matter and sediment characteristics, simultaneous measurements of dissolved organic matter, SPM concentration and organic content as well as in situ surrogates of particle concentration (turbidity, particulate attenuation, volume concentration) and particle size (laser diffraction) were carried out with measurements of current velocity (acoustic Doppler velocity meter) in the main channel of Brown's Island located in the western San Joaquin/Sacramento River Delta, CA. The study period coincided with high estuary sediment levels following a significant precipitation runoff event. In the Brown Island wetland, particle concentration and size dynamics were tied to variations in water level and velocity. Turbidity and attenuation covaried with the volume concentration of particles smaller than 33 um, which on average represented greater than 50% of particle population by volume. On average, these SPM concentration surrogates were three times higher in flood water than in ebb water; consistent with a loss of fine particles on the island. Following the highest flood tide, the decrease in fine particles was coincident with an increase in the concentration of particles larger than 130 um; a finding consistent with particle

  9. Environmental management of a highly impacted, urbanized tropical estuary: rehabilitation and restoration

    Science.gov (United States)

    Thorhaug, A.

    1980-03-01

    The principles of the dynamics and interrelationships within the dominant subtropical and tropical Caribbean seagrass community have been studied previously before, during, and after impact. From these and scores of observations of damage and recovery patterns in Thalassia ecosystems, a sense of management recovery strategy has emerged. Artificial restoring of Thalassia testudinum seeds into areas cut off from stock (fruit, seeds) appeared feasible on a large scale after the Turkey Point (Biscayne Bay, Miami, Florida) restoration and test sampling throughout North Biscayne Bay. Two large-scale seeding attempts were made; after 11 months they compared favorably with Turkey Point specimens with regard to growth parameters, despite the turbidity and other persistent pollution. Thus, the possible areas in which Thalassia seed restoration can be used has increased to include estuaries of multiple impact still in various stages of recovery after physical and sewage pollution. This technique should be especially useful to “developing” nations where important nearshore fisheries nurseries based on Thalassia ecosystems have been heavily damaged and now lie barren. Man's impact on the estuary where seed restoration was attempted includes the following activities: 50% of the bay bottom directly dredged or filled (leaving much unconsolidated sediment); 50 million gallons of domestic waste dumped directly into a low flushing part of the bay for 20 years; seven major causeways transecting the bay, restricting circulation and flushing; two artificial inlets made into navigational channels; freshwater sheet flow drastically changed due to channelization by flood-control canals; urban runoff from a million people entering the bay. Most of the impacts have now abated; however, their long-term effects remain.

  10. Short-term to seasonal variability in factors driving primary productivity in a shallow estuary: Implications for modeling production

    Science.gov (United States)

    Canion, Andy; MacIntyre, Hugh L.; Phipps, Scott

    2013-10-01

    The inputs of primary productivity models may be highly variable on short timescales (hourly to daily) in turbid estuaries, but modeling of productivity in these environments is often implemented with data collected over longer timescales. Daily, seasonal, and spatial variability in primary productivity model parameters: chlorophyll a concentration (Chla), the downwelling light attenuation coefficient (kd), and photosynthesis-irradiance response parameters (Pmchl, αChl) were characterized in Weeks Bay, a nitrogen-impacted shallow estuary in the northern Gulf of Mexico. Variability in primary productivity model parameters in response to environmental forcing, nutrients, and microalgal taxonomic marker pigments were analysed in monthly and short-term datasets. Microalgal biomass (as Chla) was strongly related to total phosphorus concentration on seasonal scales. Hourly data support wind-driven resuspension as a major source of short-term variability in Chla and light attenuation (kd). The empirical relationship between areal primary productivity and a combined variable of biomass and light attenuation showed that variability in the photosynthesis-irradiance response contributed little to the overall variability in primary productivity, and Chla alone could account for 53-86% of the variability in primary productivity. Efforts to model productivity in similar shallow systems with highly variable microalgal biomass may benefit the most by investing resources in improving spatial and temporal resolution of chlorophyll a measurements before increasing the complexity of models used in productivity modeling.

  11. Marine geology of the St. Lawrence Estuary

    Energy Technology Data Exchange (ETDEWEB)

    St-Onge, Guillaume [Canada Research Chair in Marine Geology, Institut des sciences de la mer de Rimouski (ISMER) and GEOTOP Research Center, 310 allee des Ursulines, Rimouski, Quebec, G5L 3A1 (Canada); Duchesne, Mathieu J [Geological Survey of Canada, Quebec Division, 490 de la Couronne, Quebec City, Quebec, G1K 9A9 (Canada); Lajeunesse, Patrick, E-mail: guillaume_st-onge@uqar.qc.ca [Departement de geographie and Centre d' etudes nordiques, Universite Laval, Quebec City, Quebec, G1V 0A6 (Canada)

    2011-05-15

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

  12. Marine geology of the St. Lawrence Estuary

    International Nuclear Information System (INIS)

    St-Onge, Guillaume; Duchesne, Mathieu J; Lajeunesse, Patrick

    2011-01-01

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

  13. Turbidity and total suspended solid concentration dynamics in streamflow from California oak woodland watersheds

    Science.gov (United States)

    David J. Lewis; Kenneth W. Tate; Randy A. Dahlgren; Jacob Newell

    2002-01-01

    Resource agencies, private landowners, and citizen monitoring programs utilize turbidity (water clarity) measurements as a water quality indicator for total suspended solids (TSS – mass of solids per unit volume) and other constituents in streams and rivers. The dynamics and relationships between turbidity and TSS are functions of watershed-specific factors and...

  14. Determination of Residual Chlorine and Turbidity in Drinking Water. Instructor's Manual.

    Science.gov (United States)

    Office of Water Program Operations (EPA), Cincinnati, OH. National Training and Operational Technology Center.

    This instructor's guide presents analytical methods for residual chlorine and turbidity. Topics include sample handling, permissable concentration levels, substitution of residual chlorine for bacteriological work, public notification, and the required analytical techniques to determine residual chlorine and turbidity. This publication is intended…

  15. Coagulation effectiveness of graphene oxide for the removal of turbidity from raw surface water.

    Science.gov (United States)

    Aboubaraka, Abdelmeguid E; Aboelfetoh, Eman F; Ebeid, El-Zeiny M

    2017-08-01

    This study presents the performance of graphene oxide (GO) as a coagulant in turbidity removal from naturally and artificially turbid raw surface water. GO is considered an excellent alternative to alum, the more common coagulant used in water treatment processes, to reduce the environmental release of aluminum. Effects of GO dosage, pH, and temperature on its coagulation ability were studied to determine the ideal turbidity removal conditions. The turbidity removal was ≥95% for all levels of turbid raw surface water (20, 100, and 200 NTU) at optimum conditions. The role of alkalinity in inducing turbidity removal by GO coagulation was much more pronounced upon using raw surface water samples compared with that using artificially turbid deionized water samples. Moreover, GO demonstrated high-performance removal of biological contaminants such as algae, heterotrophic bacteria, and fecal coliform bacteria by 99.0%, 98.8% and 96.0%, respectively, at a dosage of 40 mg/L. Concerning the possible environmental release of GO into the treated water following filtration process, there was no residual GO in a wide range of pH values. The outcomes of the study highlight the excellent coagulation performance of GO for the removal of turbidity and biological contaminants from raw surface water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Determination of Residual Chlorine and Turbidity in Drinking Water. Student Manual.

    Science.gov (United States)

    Office of Water Program Operations (EPA), Cincinnati, OH. National Training and Operational Technology Center.

    This student's manual covers analytical methods for residual chlorine and turbidity. Topics include sample handling, permissable concentration levels, substitution of residual chlorine for bacteriological work, public notification, and the required analytical techniques to determine residual chlorine and turbidity. The publication is intended for…

  17. Removal of Cu2+ and turbidity from wastewater by mercaptoacetyl chitosan.

    Science.gov (United States)

    Chang, Qing; Zhang, Min; Wang, Jinxi

    2009-09-30

    A macromolecule heavy metal flocculant mercaptoacetyl chitosan (MAC) was prepared by reacting chitosan with mercaptoacetic acid. In preliminary experiments, the flocculation performance of MAC was evaluated by using wastewater containing Cu(2+) or/and turbidity. Some factors which affect the removal of Cu(2+) and turbidity were also studied. The experimental results showed that: (1) MAC can remove both Cu(2+) and turbidity from wastewater. The removal efficiency of Cu(2+) by using MAC combined with hydrolyzed polyacrylamide is higher than that by only using MAC, the removal efficiency of Cu(2+) reaches above 98%; (2) when water sample containing not only Cu(2+) but also turbidity-causing substance, the removal efficiency of both Cu(2+) and turbidity will be promoted by the cooperation effect of each other, the residual concentration of Cu(2+) reaches below 0.5 mg L(-1) and the turbidity reaches below 3NTU, Cu(2+) is more easily removed by MAC when turbidity is higher; (3) the removal efficiency of Cu(2+) increases with the increase in pH value, contrarily removal efficiency of turbidity decreases with the increase in pH value.

  18. MassFLOW-3D as a simulation tool for turbidity currents

    NARCIS (Netherlands)

    Basani, Riccardo; Janocko, Michal; Cartigny, Matthieu J.B.; Hansen, Ernst W.M.; Eggenhuisen, Joris T.

    2014-01-01

    Turbidity currents are the most important mechanism for the dispersal and deposition of sand in the deep-sea setting and thus the main phenomenon leading to the formation of oil and gas reservoirs in deep water deposits. The flow characteristics of turbidity currents are difficult to observe and

  19. Potential of turbidity monitoring for real time control of pollutant discharge in sewers during rainfall events.

    Science.gov (United States)

    Lacour, C; Joannis, C; Gromaire, M-C; Chebbo, G

    2009-01-01

    Turbidity sensors can be used to continuously monitor the evolution of pollutant mass discharge. For two sites within the Paris combined sewer system, continuous turbidity, conductivity and flow data were recorded at one-minute time intervals over a one-year period. This paper is intended to highlight the variability in turbidity dynamics during wet weather. For each storm event, turbidity response aspects were analysed through different classifications. The correlation between classification and common parameters, such as the antecedent dry weather period, total event volume per impervious hectare and both the mean and maximum hydraulic flow for each event, was also studied. Moreover, the dynamics of flow and turbidity signals were compared at the event scale. No simple relation between turbidity responses, hydraulic flow dynamics and the chosen parameters was derived from this effort. Knowledge of turbidity dynamics could therefore potentially improve wet weather management, especially when using pollution-based real-time control (P-RTC) since turbidity contains information not included in hydraulic flow dynamics and not readily predictable from such dynamics.

  20. Abrupt state change of river water quality (turbidity): Effect of extreme rainfalls and typhoons.

    Science.gov (United States)

    Lee, Chih-Sheng; Lee, Yi-Chao; Chiang, Hui-Min

    2016-07-01

    River turbidity is of dynamic nature, and its stable state is significantly changed during the period of heavy rainfall events. The frequent occurrence of typhoons in Taiwan has caused serious problems in drinking water treatment due to extremely high turbidity. The aim of the present study is to evaluate impact of typhoons on river turbidity. The statistical methods used included analyses of paired annual mean and standard deviation, frequency distribution, and moving standard deviation, skewness, and autocorrelation; all clearly indicating significant state changes of river turbidity. Typhoon Morakot of 2009 (recorded high rainfall over 2000mm in three days, responsible for significant disaster in southern Taiwan) is assumed as a major initiated event leading to critical state change. In addition, increasing rate of turbidity in rainfall events is highly and positively correlated with rainfall intensity both for pre- and post-Morakot periods. Daily turbidity is also well correlated with daily flow rate for all the eleven events evaluated. That implies potential prediction of river turbidity by river flow rate during rainfall and typhoon events. Based on analysis of stable state changes, more effective regulations for better basin management including soil-water conservation in watershed are necessary. Furthermore, municipal and industrial water treatment plants need to prepare and ensure the adequate operation of water treatment with high raw water turbidity (e.g., >2000NTU). Finally, methodology used in the present of this study can be applied to other environmental problems with abrupt state changes. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Effects of sedimentation and turbidity on lotic food webs: a concise review for natural resource managers

    Science.gov (United States)

    W.F. Henley; M.A. Patterson; R.J. Neves; A. Dennis Lemly

    2000-01-01

    Sedimentation and turbidity are significant contributors to declines in populations of North American aquatic organisms. Impacts to lotic fauna may be expressed through pervasive alterations in local food chains beginning at the primary trophic level. Decreases in primary production are associated with increases in sedimentation and turbidity and produce negative...

  2. Deschutes estuary feasibility study: hydrodynamics and sediment transport modeling

    Science.gov (United States)

    George, Douglas A.; Gelfenbaum, Guy; Lesser, Giles; Stevens, Andrew W.

    2006-01-01

    Continual sediment accumulation in Capitol Lake since the damming of the Deschutes River in 1951 has altered the initial morphology of the basin. As part of the Deschutes River Estuary Feasibility Study (DEFS), the United States Geological Survey (USGS) was tasked to model how tidal and storm processes will influence the river, lake and lower Budd Inlet should estuary restoration occur. Understanding these mechanisms will assist in developing a scientifically sound assessment on the feasibility of restoring the estuary. The goals of the DEFS are as follows. - Increase understanding of the estuary alternative to the same level as managing the lake environment.

  3. Differences in the structure of copepod assemblages in four tropical estuaries: Importance of pollution and the estuary hydrodynamics.

    Science.gov (United States)

    Araujo, Adriana V; Dias, Cristina O; Bonecker, Sérgio L C

    2017-02-15

    We examined the relationship between pollution and structure of copepod assemblages in estuaries, using sampling standardization of salinity range to reduce the effects of "Estuarine Quality Paradox". Copepod assemblages were analyzed in four Southeast Brazilian estuaries with different water quality levels and different hydrodynamic characteristics. The pollution negatively impacted the descriptors of the assemblage structure. The distribution of structure of copepod assemblages also showed a main separation trend between the most polluted estuaries and those less polluted. Temperature was the main factor affecting the assemblage structuring in the four estuaries. This factor acted in synergism with the effects of pollution impact and physical characteristics of the estuaries on the structure of copepod assemblages, supporting the potential vulnerability of coastal environments due to nutrient enrichment associated with climate change. Our study demonstrated the importance of sampling standardization of the salinity range in estuaries for reliable analysis of pollution effects on biota. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Anthropogenic Carbon Pump in an Urbanized Estuary

    Science.gov (United States)

    Park, J. H.; Yoon, T. K.; Jin, H.; Begum, M. S.

    2015-12-01

    The importance of estuaries as a carbon source has been increasingly recognized over the recent decades. However, constraining sources of CO2 evasion from urbanized estuaries remains incomplete, particularly in densely populated river systems receiving high loads of organic carbon from anthropogenic sources. To account for major factors regulating carbon fluxes the tidal reach of the Han River estuary along the metropolitan Seoul, characterization of organic carbon in the main stem and major urban tributaries were combined with continuous, submersible sensor measurements of pCO2 at a mid-channel location over a year and continuous underway measurements using a submersible sensor and two equilibrator sytems across the estuarine section receiving urban streams. Single-site continuous measurements exhibited large seasonal and diurnal variations in pCO2, ranging from sub-ambient air levels to exceptionally high values approaching 10,000 ppm. Diurnal variations of pCO2 were pronounced in summer and had an inverse relationship with dissolved oxygen, pointing to a potential role of day-time algal consumption of CO2. Cruise measurements displayed sharp pCO2 pulses along the confluences of urban streams as compared with relatively low values along the upper estuary receiving low-CO2 outflows from upstream dams. Large downstream increases in pCO2, concurrent with increases in DOC concentrations and fluorescence intensities indicative of microbially processed organic components, imply a translocation and subsequent dilution of CO2 carried by urban streams and/or fast transformations of labile C during transit along downstream reaches. The unique combination of spatial and temporal continuous measurements of pCO2 provide insights on estuarine CO2 pulses that might have resulted from the interplay between high loads of CO2 and organic C of anthropogenic origin and their priming effects on estuarine microbial processing of terrigenous and algal organic matter.

  5. Sediment-induced turbidity impairs foraging performance and prey choice of planktivorous coral reef fishes.

    Science.gov (United States)

    Johansen, J L; Jones, G P

    2013-09-01

    Sedimentation is a substantial threat to aquatic ecosystems and a primary cause of habitat degradation on near-shore coral reefs. Although numerous studies have demonstrated major impacts of sedimentation and turbidity on corals, virtually nothing is known of the sensitivity of reef fishes. Planktivorous fishes are an important trophic group that funnels pelagic energy sources into reef ecosystems. These fishes are visual predators whose foraging is likely to be impaired by turbidity, but the threshold for such effects and their magnitude are unknown. This study examined the effect of sediment-induced turbidity on foraging in four species of planktivorous damselfishes (Pomacentridae) of the Great Barrier Reef, including inshore and offshore species that potentially differ in tolerance for turbidity. An experimental flow tunnel was used to quantify their ability to catch mobile and immobile planktonic prey under different levels of turbidity and velocity in the range encountered on natural and disturbed reefs. Turbidity of just 4 NTU (nephelometric turbidity units) reduced average attack success by up to 56%, with higher effect sizes for species with offshore distributions. Only the inshore species (Neopomacentrus bankieri), which frequently encounters this turbidity on coastal reefs, could maintain high prey capture success. At elevated turbidity similar to that found on disturbed reefs (8 NTU), attack success was reduced in all species examined by up to 69%. These reductions in attack success led to a 21-24% decrease in foraging rates for all mid to outer-shelf species, in spite of increasing attack rates at high turbidity. Although effects of turbidity varied among species, it always depended heavily on prey mobility and ambient velocity. Attack success was up to 14 times lower on mobile prey, leaving species relatively incapable of foraging on anything but immobile prey at high turbidity. Effects of turbidity were particularly prominent at higher velocities, as

  6. Generalized weighted ratio method for accurate turbidity measurement over a wide range.

    Science.gov (United States)

    Liu, Hongbo; Yang, Ping; Song, Hong; Guo, Yilu; Zhan, Shuyue; Huang, Hui; Wang, Hangzhou; Tao, Bangyi; Mu, Quanquan; Xu, Jing; Li, Dejun; Chen, Ying

    2015-12-14

    Turbidity measurement is important for water quality assessment, food safety, medicine, ocean monitoring, etc. In this paper, a method that accurately estimates the turbidity over a wide range is proposed, where the turbidity of the sample is represented as a weighted ratio of the scattered light intensities at a series of angles. An improvement in the accuracy is achieved by expanding the structure of the ratio function, thus adding more flexibility to the turbidity-intensity fitting. Experiments have been carried out with an 850 nm laser and a power meter fixed on a turntable to measure the light intensity at different angles. The results show that the relative estimation error of the proposed method is 0.58% on average for a four-angle intensity combination for all test samples with a turbidity ranging from 160 NTU to 4000 NTU.

  7. A drifter for measuring water turbidity in rivers and coastal oceans.

    Science.gov (United States)

    Marchant, Ross; Reading, Dean; Ridd, James; Campbell, Sean; Ridd, Peter

    2015-02-15

    A disposable instrument for measuring water turbidity in rivers and coastal oceans is described. It transmits turbidity measurements and position data via a satellite uplink to a processing server. The primary purpose of the instrument is to help document changes in sediment runoff from river catchments in North Queensland, Australia. The 'river drifter' is released into a flooded river and drifts downstream to the ocean, measuring turbidity at regular intervals. Deployment in the Herbert River showed a downstream increase in turbidity, and thus suspended sediment concentration, while for the Johnstone River there was a rapid reduction in turbidity where the river entered the sea. Potential stranding along river banks is a limitation of the instrument. However, it has proved possible for drifters to routinely collect data along 80 km of the Herbert River. One drifter deployed in the Fly River, Papua New Guinea, travelled almost 200 km before stranding. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Robust sensor for turbidity measurement from light scattering and absorbing liquids.

    Science.gov (United States)

    Kontturi, Ville; Turunen, Petri; Uozumi, Jun; Peiponen, Kai-Erik

    2009-12-01

    Internationally standardized turbidity measurements for probing solid particles in liquid are problematic in the case of simultaneous light scattering and absorption. A method and a sensor to determine the turbidity in the presence of light absorption are presented. The developed sensor makes use of the total internal reflection of a laser beam at the liquid-prism interface, and the turbidity is assessed using the concept of laser speckle pattern. Using average filtering in speckle data analyzing the observed dynamic speckle pattern, which is due to light scattering from particles and the static speckle due to stray light of the sensor, can be separated from each other. Good correlation between the standard deviation of dynamic speckle and turbidity value for nonabsorbing and for absorbing liquids was observed. The sensor is suggested, for instance, for the measurement of ill-behaved as well as small-volume turbid liquids in both medicine and process industry.

  9. Effects of turbidity and prey density on the foraging success of age 0 year yellow perch Perca flavescens.

    Science.gov (United States)

    Wellington, C G; Mayer, C M; Bossenbroek, J M; Stroh, N A

    2010-05-01

    Laboratory experiments were conducted to determine how larval and juvenile yellow perch Perca flavescens respond to changes in prey density when exposed to different levels and types of turbidity (phytoplanktonic or sedimentary). Across prey densities, consumption by P. flavescens tended to be less in phytoplanktonic turbidity compared with sedimentary turbidity. For larvae, this effect was dependent on turbidity level (consumption differed between turbidity types only at high turbidity), while for juveniles the difference with turbidity type was equal across turbidity levels. These results suggest that phytoplankton blooms are detrimental to the ability of late season age 0 year P. flavescens to forage and support the need to control factors leading to excessive phytoplankton growth in lakes.

  10. Markov chain solution of photon multiple scattering through turbid slabs.

    Science.gov (United States)

    Lin, Ying; Northrop, William F; Li, Xuesong

    2016-11-14

    This work introduces a Markov Chain solution to model photon multiple scattering through turbid slabs via anisotropic scattering process, i.e., Mie scattering. Results show that the proposed Markov Chain model agree with commonly used Monte Carlo simulation for various mediums such as medium with non-uniform phase functions and absorbing medium. The proposed Markov Chain solution method successfully converts the complex multiple scattering problem with practical phase functions into a matrix form and solves transmitted/reflected photon angular distributions by matrix multiplications. Such characteristics would potentially allow practical inversions by matrix manipulation or stochastic algorithms where widely applied stochastic methods such as Monte Carlo simulations usually fail, and thus enable practical diagnostics reconstructions such as medical diagnosis, spray analysis, and atmosphere sciences.

  11. Use of Moringa oleifera seed extracts to reduce helminth egg numbers and turbidity in irrigation water.

    Science.gov (United States)

    Sengupta, Mita E; Keraita, Bernard; Olsen, Annette; Boateng, Osei K; Thamsborg, Stig M; Pálsdóttir, Guðný R; Dalsgaard, Anders

    2012-07-01

    Water from wastewater-polluted streams and dug-outs is the most commonly used water source for irrigation in urban farming in Ghana, but helminth parasite eggs in the water represent health risks when used for crop production. Conventional water treatment is expensive, requires advanced technology and often breaks down in less developed countries so low cost interventions are needed. Field and laboratory based trials were carried out in order to investigate the effect of the natural coagulant Moringa oleifera (MO) seed extracts in reducing helminh eggs and turbidity in irrigation water, turbid water, wastewater and tap water. In medium to high turbid water MO extracts were effective in reducing the number of helminth eggs by 94-99.5% to 1-2 eggs per litre and the turbidity to 7-11 NTU which is an 85-96% reduction. MO is readily available in many tropical countries and can be used by farmers to treat high turbid water for irrigation, however, additional improvements of water quality, e.g. by sand filtration, is suggested to meet the guideline value of ≤ 1 helminth egg per litre and a turbidity of ≤ 2 NTU as recommended by the World Health Organization and the U.S. Environmental Protection Agency for water intended for irrigation. A positive correlation was established between reduction in turbidity and helminth eggs in irrigation water, turbid water and wastewater treated with MO. This indicates that helminth eggs attach to suspended particles and/or flocs facilitated by MO in the water, and that turbidity and helminth eggs are reduced with the settling flocs. However, more experiments with water samples containing naturally occurring helminth eggs are needed to establish whether turbidity can be used as a proxy for helminth eggs. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Modeling of Turbidity Variation in Two Reservoirs Connected by a Water Transfer Tunnel in South Korea

    Directory of Open Access Journals (Sweden)

    Jae Chung Park

    2017-06-01

    Full Text Available The Andong and Imha reservoirs in South Korea are connected by a water transfer tunnel. The turbidity of the Imha reservoir is much higher than that of the Andong reservoir. Thus, it is necessary to examine the movement of turbidity between the two reservoirs via the water transfer tunnel. The aim of this study was to investigate the effect of the water transfer tunnel on the turbidity behavior of the two connecting reservoirs and to further understand the effect of reservoir turbidity distribution as a function of the selective withdrawal depth. This study applied the CE-QUAL-W2, a water quality and 2-dimensional hydrodynamic model, for simulating the hydrodynamic processes of the two reservoirs. Results indicate that, in the Andong reservoir, the turbidity of the released water with the water transfer tunnel was similar to that without the tunnel. However, in the Imha reservoir, the turbidity of the released water with the water transfer tunnel was lower than that without the tunnel. This can be attributed to the higher capacity of the Andong reservoir, which has double the storage of the Imha reservoir. Withdrawal turbidity in the Imha reservoir was investigated using the water transfer tunnel. This study applied three withdrawal selections as elevation (EL. 141.0 m, 146.5 m, and 152.0 m. The highest withdrawal turbidity resulted in EL. 141.0 m, which indicates that the high turbidity current is located at a vertical depth of about 20–30 m because of the density difference. These results will be helpful for understanding the release and selective withdrawal turbidity behaviors for a water transfer tunnel between two reservoirs.

  13. Automatic real-time control of suspended sediment based upon high frequency in situ measurements of nephelometric turbidity

    Science.gov (United States)

    Jack Lewis; Rand Eads

    1998-01-01

    Abstract - For estimating suspended sediment concentration (SSC) in rivers, turbidity is potentially a much better predictor than water discharge. Since about 1990, it has been feasible to automatically collect high frequency turbidity data at remote sites using battery-powered turbidity probes that are properly mounted in the river or stream. With sensors calibrated...

  14. Nutrient input through submarine groundwater discharge in two major Chinese estuaries: the Pearl River Estuary and the Changjiang River Estuary

    Science.gov (United States)

    Liu, Jianan; Du, Jinzhou; Wu, Ying; Liu, Sumei

    2018-04-01

    In this study, we used a 224Ra mass balance model to evaluate the importance of submarine groundwater discharge (SGD) for the budgets of biogenic elements in two major Chinese estuaries: the Pearl River Estuary (PRE) and the Changjiang River Estuary (CRE). The apparent water age in the PRE was estimated to be 4.8 ± 1.1 days in the dry season and 1.8 ± 0.6 days in the wet season using a physical model based on the tidal prism. In the dry season, the water age in the CRE was estimated to be 11.7 ± 3.0 days using the 224Ra/223Ra activities ratios apparent age model. By applying the 224Ra mass balance model, we obtained calculations of the SGD flow in the PRE of (4.5-10) × 108 m3 d-1 (0.23-0.50 m3 m-2 d-1) and (1.2-2.7) × 108 m3 d-1 (0.06-0.14 m3 m-2 d-1) in the dry season and wet season, respectively, and the estimated SGD flux was (4.6-11) × 109 m3 d-1 (0.18-0.45 m3 m-2 d-1) in the dry season of the CRE. In comparison with the nutrient fluxes from the rivers, the SGD-derived nutrient fluxes may play a vital role in controlling the nutrient budgets and stoichiometry in the study areas. The large amount of dissolved inorganic nitrogen and phosphorus fluxes together with high N: P ratios into the PRE and CRE would potentially contribute to eutrophication and the occurrence of red tides along the adjacent waters.

  15. Nutritional condition of fish larvae in South African estuaries: an ...

    African Journals Online (AJOL)

    Nutritional condition of fish larvae in South African estuaries: an appraisal of three biochemical methods. D Costalago, N Strydom, C Frost. Abstract. Estuaries are exposed to a number of threats and many South African estuarine systems are functionally and structurally altered. The extent to which fish are affected by these ...

  16. Columbia Estuary Ecosystem Restoration Program. 2012 Synthesis Memorandum

    Science.gov (United States)

    2013-01-01

    LCFRB Lower Columbia Fish Recovery Board LCRE lower Columbia River and estuary LCREP Lower Columbia River Estuary Partnership LWD large woody debris...hydraulic reconnections, channel creation, large woody debris [ LWD ] placement) have restored a total of 3152 acres since 2001. If land acquisition...fencing, invasive plant removal, native replanting. Mirror Lake 208 Culvert replaced with a bridge, riparian restoration, LWD enhancement, culvert

  17. Tillamook Estuary Case Study: Local Drivers Influencing Coastal Acidification

    Science.gov (United States)

    US EPA initiated a study in the Tillamook estuary and watershed focused on the impact of changes in watershed land use, ocean conditions, and weather on estuarine water quality and ecosystem goods and services production within the estuary. This project is a collaboration betwee...

  18. Management of Fishery Resources in Yangtze River Estuary

    OpenAIRE

    Li, Meiling; Huang, Shuolin

    2009-01-01

    We introduce the fish fauna composition and main commercial fishes in Yangtze River estuary. We also analyze the current situation of resources and environment in Yangtze River estuary as well as the influential factors. Finally, related countermeasures are put forward on how to protect and use the fishery resources in Yangtze River.

  19. Fish abundance and distribution in the Gamtoos estuary with notes ...

    African Journals Online (AJOL)

    favourably with other larger systems like the Sundays, Bashee and Kei estuaries. .... as well as the use of pesticides undoubtedly affects water quality in the ... Methods. Catch per unit effort (CPUE) of fish in the Gamtoos estuary was obtained ...

  20. Relation between tidal damping and wave celerity in estuaries

    NARCIS (Netherlands)

    Savenije, H.H.G.; Veling, E.J.M.

    2005-01-01

    Observations in estuaries indicate that an amplified tidal wave moves considerably faster than is indicated by the classical equation for wave propagation. Similarly, the celerity of propagation is lower if the tidal wave is damped. This phenomenon is clearly observed in the Schelde estuary (located

  1. Zooplankton community changes in Nhlabane estuary, South Africa ...

    African Journals Online (AJOL)

    made impacts since 1977, when the lake and estuary were separated by the construction of a barrage. More recent man-made events included the construction of temporary sand walls, mid-way along the estuary, to allow crossing of a mining ...

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

    Science.gov (United States)

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

    2014-12-01

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

  3. Spatiotemporal distribution of the benthic macrofauna in an urbanized subtropical estuary: environmental variations and anthropogenic impacts

    Directory of Open Access Journals (Sweden)

    Pedro Rocha Mattos

    Full Text Available Abstract This study was conducted in the Itajaí-Açu river lower estuary in Southern Brazil, in which we aimed to: (1 analyze spatiotemporal variations on the macrofauna; (2 search for relationships between environmental variables and the assembly and (3 evaluate the influence of capital dredging upon the assembly. Two hundred twenty eight samples were performed in four stations, two of which affected by dredging. Sediment (sand, silt and clay, organic matter and carbonate and water column´s variables (temperature, salinity, pH, dissolved oxygen, and turbidity were also assessed. We applied Principal Component Analysis for environmental variables and Hierarchical Clustering for biotic data. Correlations between environmental and biotic matrices were tested by Canonical Analysis of Principal Coordinates. Spatiotemporal variations in the assembly were tested by Permutational Multivariate Analysis of Variance. From the 21.839 organisms sampled, 97% was represented by the gastropod Heleobia australis. Despite the influence of the river discharge on the ecosystem, dredging was deleterious to the assembly, favoring opportunistic organisms such as H. australis.

  4. Phytoplankton community indicators of changes associated with dredging in the Tagus estuary (Portugal)

    International Nuclear Information System (INIS)

    Cabrita, Maria Teresa

    2014-01-01

    This work reports changes in suspended particulate matter, turbidity, dissolved Cr, Ni, Cu, Cd, Hg and Pb concentrations, and phytoplankton biomass and composition during a 5-month period dredging operation, in a trace element contaminated area of the Tagus estuary (Portugal). Phytoplankton biomass, diatom:other groups ratio, benthic:pelagic diatom ratio, Margalef's, Simpson's diversity, Shannon–Wiever's, and Warwick and Clarke's taxonomic diversity and distinctness indices, and individual taxa were investigated as indicators of dredging induced changes. Significant rise in sediment resuspension and trace element mobilisation caused by dredging influenced the community structure but not the overall biomass. Benthic diatom displacement into the water column maintained species diversity, and therefore, none of the indices highlighted community changes. Contrastingly, diatom:other groups ratio and benthic:pelagic diatom ratio were reliable indicators for the assessment of dredging induced changes. A shift in composition towards species less susceptible to trace elements was observed, disclosing some individual taxa as potential indicators. - Highlights: • Phytoplankton community indicators of dredging induced changes were investigated. • Increased resuspension and trace element mobilisation changed community structure. • Diversity indices unsuitable to detect changes because species richness was maintained. • Diatom:other groups and benthic:pelagic diatom ratios were efficient indicators. • Individual taxa may be potential indicators but require site-specific validation. - Diatom:other groups ratio, benthic:pelagic diatom ratio and individual taxa were identified as efficient indicators for the assessment of water quality changes associated with dredging

  5. Correlations between Microbial Indicators, Pathogens, and Environmental Factors in a Subtropical Estuary

    Science.gov (United States)

    Ortega, Cristina; Solo-Gabriele, Helena M.; Abdelzaher, Amir; Wright, Mary; Deng, Yang; Stark, Lillian M.

    2009-01-01

    The objective of this study was to evaluate whether indicator microbes and physical-chemical parameters were correlated with pathogens within a tidally influenced estuary. Measurements included the analysis of physical-chemical parameters (pH, salinity, temperature, and turbidity), measurements of bacterial indicators (enterococci, fecal coliform, E. coli, and total coliform), viral indicators (somatic and MS2 coliphage), viral pathogens (enterovirus by culture), and protozoan pathogens (Cryptosporidium and Giardia). All pathogen results were negative with the exception of one sample which tested positive for culturable reovirus (8.5 MPN/100 L).. Notable physical-chemical parameters for this sample included low salinity (<1 ppt) and high water temperature (31 °C). Indicator bacteria and indicator virus levels for this sample were within average values typically measured within the study site and were low in comparison with levels observed in other freshwater environments. Overall results suggest that high levels of bacterial and viral indicators were associated with low salinity sites. PMID:19464704

  6. Determination of Linke turbidity factor from solar radiation measurement in northern Tunisia

    International Nuclear Information System (INIS)

    Chaabane, M.; Masmoudi, M.; Medhioub, K.

    2004-01-01

    The attenuation of solar radiation through a real atmosphere versus that through a clean dry atmosphere gives an indication of the atmospheric turbidity. Study of atmospheric turbidity is important in meteorology, climatology and for monitoring of atmospheric pollution. The Linke turbidity factor refers to the whole spectrum, that is, overall spectrally integrated attenuation, which includes presence of gaseous water vapour and aerosols. In this work, a procedure for calculation of Linke turbidity factor is adopted using pyrheliometric measurements in a coastal tourist location in Tunisia (Sidi Bou Said), during three summer months (June, July and August 1999). Real diurnal and monthly variations of the T L turbidity factor are found in the three studied months, with a maximum in August afternoon and a minimum in July morning. The increase of T L is an indication for increasing atmospheric turbidity level (pollution). The correlation between atmospheric turbidity and the local weather conditions shows that this increase is essentially due to the heavy water vapour content of maritime air masses, carried by the north-eastern winds prevalent during the afternoon. A second pollution source is the dust content of the continental air masses carried by western and southern winds prevalent in the morning. Next to this can be added the influence of traffic at rush hours and during the afternoon of summer holidays. (Author)

  7. Newly recognized turbidity current structure can explain prolonged flushing of submarine canyons.

    Science.gov (United States)

    Azpiroz-Zabala, Maria; Cartigny, Matthieu J B; Talling, Peter J; Parsons, Daniel R; Sumner, Esther J; Clare, Michael A; Simmons, Stephen M; Cooper, Cortis; Pope, Ed L

    2017-10-01

    Seabed-hugging flows called turbidity currents are the volumetrically most important process transporting sediment across our planet and form its largest sediment accumulations. We seek to understand the internal structure and behavior of turbidity currents by reanalyzing the most detailed direct measurements yet of velocities and densities within oceanic turbidity currents, obtained from weeklong flows in the Congo Canyon. We provide a new model for turbidity current structure that can explain why these are far more prolonged than all previously monitored oceanic turbidity currents, which lasted for only hours or minutes at other locations. The observed Congo Canyon flows consist of a short-lived zone of fast and dense fluid at their front, which outruns the slower moving body of the flow. We propose that the sustained duration of these turbidity currents results from flow stretching and that this stretching is characteristic of mud-rich turbidity current systems. The lack of stretching in previously monitored flows is attributed to coarser sediment that settles out from the body more rapidly. These prolonged seafloor flows rival the discharge of the Congo River and carry ~2% of the terrestrial organic carbon buried globally in the oceans each year through a single submarine canyon. Thus, this new structure explains sustained flushing of globally important amounts of sediment, organic carbon, nutrients, and fresh water into the deep ocean.

  8. A polychromatic turbidity microplate assay to distinguish discovery stage drug molecules with beneficial precipitation properties.

    Science.gov (United States)

    Morrison, John; Nophsker, Michelle; Elzinga, Paul; Donoso, Maria; Park, Hyunsoo; Haskell, Roy

    2017-10-05

    A material sparing microplate screening assay was developed to evaluate and compare the precipitation of discovery stage drug molecules as a function of time, concentration and media composition. Polychromatic turbidity time course profiles were collected for cinnarizine, probucol, dipyridamole as well as BMS-932481, and compared with turbidity profiles of monodisperse particle size standards. Precipitation for select sample conditions were further characterized at several time points by size, morphology, amount and form via laser diffraction, microscopy, size based particle counting and X-ray diffraction respectively. Wavelength dependent turbidity was found indicative of nanoprecipitate, while wavelength independent turbidity was consistent with larger microprecipitate formation. A transition from wavelength dependent to wavelength independent turbidity occurred for nanoparticle to microparticle growth, and a decrease in wavelength independent turbidity correlated with continued growth in size of microparticles. Other sudden changes in turbidity signal over time such as rapid fluctuation, a decrease in slope or a sharp inversion were correlated with very large or aggregated macro-precipitates exceeding 100μm in diameter, a change in the rate of precipitate formation or an amorphous to crystalline form conversion respectively. The assay provides an effective method to efficiently monitor and screen the precipitation fates of drug molecules, even during the early stages of discovery with limited amounts of available material. This capability highlights molecules with beneficial precipitation properties that are able to generate and maintain solubility enabling amorphous or nanoparticle precipitates. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Recovery of diverse microbes in high turbidity surface water samples using dead-end ultrafiltration.

    Science.gov (United States)

    Mull, Bonnie; Hill, Vincent R

    2012-12-01

    Dead-end ultrafiltration (DEUF) has been reported to be a simple, field-deployable technique for recovering bacteria, viruses, and parasites from large-volume water samples for water quality testing and waterborne disease investigations. While DEUF has been reported for application to water samples having relatively low turbidity, little information is available regarding recovery efficiencies for this technique when applied to sampling turbid water samples such as those commonly found in lakes and rivers. This study evaluated the effectiveness of a DEUF technique for recovering MS2 bacteriophage, enterococci, Escherichia coli, Clostridium perfringens, and Cryptosporidium parvum oocysts in surface water samples having elevated turbidity. Average recovery efficiencies for each study microbe across all turbidity ranges were: MS2 (66%), C. parvum (49%), enterococci (85%), E. coli (81%), and C. perfringens (63%). The recovery efficiencies for MS2 and C. perfringens exhibited an inversely proportional relationship with turbidity, however no significant differences in recovery were observed for C. parvum, enterococci, or E. coli. Although ultrafilter clogging was observed, the DEUF method was able to process 100-L surface water samples at each turbidity level within 60 min. This study supports the use of the DEUF method for recovering a wide array of microbes in large-volume surface water samples having medium to high turbidity. Published by Elsevier B.V.

  10. Turbidity and suspended sediment in the upper Esopus Creek watershed, Ulster County, New York

    Science.gov (United States)

    McHale, Michael R.; Siemion, Jason

    2014-01-01

    Suspended-sediment concentrations (SSCs) and turbidity were measured for 2 to 3 years at 14 monitoring sites throughout the upper Esopus Creek watershed in the Catskill Mountains of New York State. The upper Esopus Creek watershed is part of the New York City water-supply system that supplies water to more than 9 million people every day. Turbidity, caused primarily by high concentrations of inorganic suspended particles, is a potential water-quality concern because it colors the water and can reduce the effectiveness of drinking-water disinfection. The purposes of this study were to quantify concentrations of suspended sediment and turbidity levels, to estimate suspended-sediment loads within the upper Esopus Creek watershed, and to investigate the relations between SSC and turbidity. Samples were collected at four locations along the main channel of Esopus Creek and at all of the principal tributaries. Samples were collected monthly and during storms and were analyzed for SSC and turbidity in the laboratory. Turbidity was also measured every 15 minutes at six of the sampling stations with in situ turbidity probes.

  11. Treatment of water turbidity and bacteria by using a coagulant extracted from Plantago ovata

    Directory of Open Access Journals (Sweden)

    Bahman Ramavandi

    2014-08-01

    Full Text Available A biocoagulant was successfully extracted from Plantago ovata by using an FeCl3-induced crude extract (FCE. The potential of FCE to act as a natural coagulant was tested for clarification using the turbid water of a river. Experimental tests were performed to evaluate the effects of turbidity concentration, coagulant quantity, water pH, and humic acid concentration on the coagulation of water turbidity by FCE. The maximum turbidity removal was occurred at water pH<8. At the optimum dosage of FCE, only 0.8 mg/L of dissolved organic carbon was released to the treated water. An increase in the humic acid led to the promotion of the water turbidity removal. Results demonstrated that the FCE removed more than 95.6% of all initial turbidity concentrations (50–300 NTU. High bacteriological quality was achieved in the treated water. FCE as an eco-friendly biocoagulant was revealed to be a very efficient coagulant for removing turbidity from waters.

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

    NARCIS (Netherlands)

    van Damme, S.; Dehairs, F.; Tackx, M.; Beauchard, O.; Struyf, E.; Gribsholt, B.; van Cleemput, O.; Meire, P.

    2009-01-01

    Tidal marsh exchange studies are relatively simple tools to investigate the interaction between tidal marshes and estuaries. They have mostly been confined to only a few elements and to saltwater or brackish systems. This study presents mass-balance results of an integrated one year campaign in a

  13. The importance of the river-estuary interface (REI) zone in estuaries

    African Journals Online (AJOL)

    drinie

    2002-07-03

    Jul 3, 2002 ... A multidisciplinary and multi-institutional research programme studied the influence of river flow rate on salinity distribution and response of the ... alia, the state of the mouth influences the extent of water exchange with the sea, vertical and ... The Kariega Estuary is a marine dominated system with very little.

  14. Drinking water turbidity and emergency department visits for gastrointestinal illness in Atlanta, 1993-2004.

    Science.gov (United States)

    Tinker, Sarah C; Moe, Christine L; Klein, Mitchel; Flanders, W Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E

    2010-01-01

    The extent to which drinking water turbidity measurements indicate the risk of gastrointestinal illness is not well understood. Despite major advances in drinking water treatment and delivery, infectious disease can still be transmitted through drinking water in the United States, and it is important to have reliable indicators of microbial water quality to inform public health decisions. The objective of our study was to assess the relationship between gastrointestinal illness, quantified through emergency department visits, and drinking water quality, quantified as raw water and filtered water turbidity measured at the treatment plant. We examined the relationship between turbidity levels of raw and filtered surface water measured at eight major drinking water treatment plants in the metropolitan area of Atlanta, Georgia, and over 240,000 emergency department visits for gastrointestinal illness during 1993-2004 among the population served by these plants. We fit Poisson time-series statistical regression models that included turbidity in a 21-day distributed lag and that controlled for meteorological factors and long-term time trends. For filtered water turbidity, the results were consistent with no association with emergency department visits for gastrointestinal illness. We observed a modest association between raw water turbidity and emergency department visits for gastrointestinal illness. Our results suggest that source water quality may contribute modestly to endemic gastrointestinal illness in the study area. The association between turbidity and emergency department visits for gastrointestinal illness was only observed when raw water turbidity was considered; filtered water turbidity may not serve as a reliable indicator of modest pathogen risk at all treatment plants.

  15. Collagen I self-assembly: revealing the developing structures that generate turbidity.

    Science.gov (United States)

    Zhu, Jieling; Kaufman, Laura J

    2014-04-15

    Type I collagen gels are routinely used in biophysical studies and bioengineering applications. The structural and mechanical properties of these fibrillar matrices depend on the conditions under which collagen fibrillogenesis proceeds, and developing a fuller understanding of this process will enhance control over gel properties. Turbidity measurements have long been the method of choice for monitoring developing gels, whereas imaging methods are regularly used to visualize fully developed gels. In this study, turbidity and confocal reflectance microscopy (CRM) were simultaneously employed to track collagen fibrillogenesis and reconcile the information reported by the two techniques, with confocal fluorescence microscopy (CFM) used to supplement information about early events in fibrillogenesis. Time-lapse images of 0.5 mg/ml, 1.0 mg/ml, and 2.0 mg/ml acid-solubilized collagen I gels forming at 27°C, 32°C, and 37°C were collected. It was found that in situ turbidity measured in a scanning transmittance configuration was interchangeable with traditional turbidity measurements using a spectrophotometer. CRM and CFM were employed to reveal the structures responsible for the turbidity that develops during collagen self-assembly. Information from CRM and transmittance images was collapsed into straightforward single variables; total intensity in CRM images tracked turbidity development closely for all collagen gels investigated, and the two techniques were similarly sensitive to fibril number and dimension. Complementary CRM, CFM, and in situ turbidity measurements revealed that fibril and network formation occurred before substantial turbidity was present, and the majority of increasing turbidity during collagen self-assembly was due to increasing fibril thickness. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  16. DRINKING WATER TURBIDITY AND EMERGENCY DEPARTMENT VISITS FOR GASTROINTESTINAL ILLNESS IN ATLANTA, 1993 – 2004

    Science.gov (United States)

    Tinker, Sarah C.; Moe, Christine L.; Klein, Mitchel; Flanders, W. Dana; Uber, Jim; Amirtharajah, Appiah; Singer, Philip; Tolbert, Paige E.

    2013-01-01

    Background The extent to which drinking water turbidity measurements indicate the risk of gastrointestinal illness is not well-understood. Despite major advances in drinking water treatment and delivery, infectious disease can still be transmitted through drinking water in the U.S., and it is important to have reliable indicators of microbial water quality to inform public health decisions. The objective of our study was to assess the relationship between gastrointestinal illness, quantified through emergency department visits, and drinking water quality, quantified as raw water and filtered water turbidity measured at the treatment plant. Methods We examined the relationship between turbidity levels of raw and filtered surface water measured at eight major drinking water treatment plants in the metropolitan area of Atlanta, Georgia, and over 240 000 emergency department visits for gastrointestinal illness during 1993–2004 among the population served by these plants. We fit Poisson time-series statistical regression models that included turbidity in a 21-day distributed lag and that controlled for meteorological factors and long-term time trends. Results For filtered water turbidity, the results were consistent with no association with emergency department visits for gastrointestinal illness. We observed a modest association between raw water turbidity and emergency department visits for gastrointestinal illness. This association was not observed for all treatment plants in plant-specific analyses. Conclusions Our results suggest that source water quality may contribute modestly to endemic gastrointestinal illness in the study area. The association between turbidity and emergency department visits for gastrointestinal illness was only observed when raw water turbidity was considered; filtered water turbidity may not serve as a reliable indicator of modest pathogen risk at all treatment plants. PMID:18941478

  17. Increasing precision of turbidity-based suspended sediment concentration and load estimates.

    Science.gov (United States)

    Jastram, John D; Zipper, Carl E; Zelazny, Lucian W; Hyer, Kenneth E

    2010-01-01

    Turbidity is an effective tool for estimating and monitoring suspended sediments in aquatic systems. Turbidity can be measured in situ remotely and at fine temporal scales as a surrogate for suspended sediment concentration (SSC), providing opportunity for a more complete record of SSC than is possible with physical sampling approaches. However, there is variability in turbidity-based SSC estimates and in sediment loadings calculated from those estimates. This study investigated the potential to improve turbidity-based SSC, and by extension the resulting sediment loading estimates, by incorporating hydrologic variables that can be monitored remotely and continuously (typically 15-min intervals) into the SSC estimation procedure. On the Roanoke River in southwestern Virginia, hydrologic stage, turbidity, and other water-quality parameters were monitored with in situ instrumentation; suspended sediments were sampled manually during elevated turbidity events; samples were analyzed for SSC and physical properties including particle-size distribution and organic C content; and rainfall was quantified by geologic source area. The study identified physical properties of the suspended-sediment samples that contribute to SSC estimation variance and hydrologic variables that explained variability of those physical properties. Results indicated that the inclusion of any of the measured physical properties in turbidity-based SSC estimation models reduces unexplained variance. Further, the use of hydrologic variables to represent these physical properties, along with turbidity, resulted in a model, relying solely on data collected remotely and continuously, that estimated SSC with less variance than a conventional turbidity-based univariate model, allowing a more precise estimate of sediment loading, Modeling results are consistent with known mechanisms governing sediment transport in hydrologic systems.

  18. Changes in metallothionein concentrations in response to variation in natural factors (salinity, sex, weight) and metal contamination in crabs from a metal-rich estuary.

    Science.gov (United States)

    Legras; Mouneyrac; Amiard; Amiard-Triquet; Rainbow

    2000-04-05

    Intermoult male and female crabs Pachygrapsus marmoratus and Carcinus maenas were sampled from three sites between the mouth and 25 km upstream in the Gironde, the most Cd-contaminated estuary in France, in order to study the relative importance of natural factors (salinity, sex, weight) and accumulated metal concentrations on metallothionein (MT) concentrations. In the two species studied, higher metal, total protein and MT concentrations were observed in the hepatopancreas than in the gills. In P. marmoratus, MT concentrations were mainly related to changes in the natural factors even if MT and Zn concentrations were positively correlated in the hepatopancreas whereas in C. maenas, the main relationships were with accumulated metal levels. In the case of the natural factors, the most important ones were weight in gills of both crab species, and salinity changes in both hepatopancreas and gills of P. marmoratus. Cd and Cu concentrations in both organs of the two species were inversely related to salinity. The same observation was found for Zn concentrations in C. maenas but not in P. marmoratus. In the hepatopancreas of both species, the highest total protein concentrations were found in crabs from the site with the highest salinity, whereas there were no such differences in the gills. It seems that changes in MT concentrations are linked more to changes in general protein metabolism than to changes in metal accumulation. Thus it was important to examine the storage of metals in other tissue compartments, particularly the insoluble fraction which includes mineral granules which is known to also contribute to trace metal detoxification in invertebrates. In the gills of the crabs, Zn was present mainly in the insoluble fraction, whereas Cd was nearly equally distributed between soluble and insoluble fractions. In contrast, Cu in the gills and all three metals in the hepatopancreas of both species were mainly cytosolic, but this does not necessarily imply a

  19. Greenhouse gas (N2O emission from Portuguese estuaries

    Directory of Open Access Journals (Sweden)

    Célia Gonçalves

    2014-07-01

    Tagus, Minho and Lima estuaries are source of N2O to the atmosphere. Particularly, in Lima estuary anthropogenic N input seems to play an important role on N2O emission. However, in a global perspective N2O attained emissions represent a reduced fraction (2O yr-1, Barnes and Upstill-Goddard, 2011. Values are comparable with those registered in some Portuguese estuaries and other European less eutrophic estuaries. However, it is known that higher N2O emissions in estuaries may occur during winter and spring (Sun et al., 2014. Thus, these systems may represent on an annual basis a larger source of N2O, which can only be clarified in future studies. Only a full comprehension of the global estuarine nitrogen cycle will provide an efficient basis of scientific knowledge for sustainably management of such ecosystems and ultimately reduce N2O emissions.

  20. Impact of different metal turbidities on radiolytic hydrogen generation in nuclear power plants

    International Nuclear Information System (INIS)

    Kumbhar, A.G.; Belapurkar, A.D.; Venkateswaran, G.; Kishore, K.

    2005-01-01

    Radiolytic hydrogen generation on γ irradiation of turbid solutions containing metal turbidities such as titanium, nickel, iron, chromium, copper, indium, and aluminium was studied. It is suggested that the chemical reactivity of the metal in the turbid solution with e aq -/H/OH produced by radiolysis of water interferes with the recombination reactions which destroy H 2 and H 2 O 2 , thus leading to higher yield of hydrogen. The rate of generation of hydrogen and the G(H 2 ) value is related to the reactivity of the metal ion/hydroxylated species with the free radicals. (orig.)

  1. Turbidity as an Indicator of Water Quality in Diverse Watersheds of the Upper Pecos River Basin

    Directory of Open Access Journals (Sweden)

    Gregory M. Huey

    2010-06-01

    Full Text Available Microbial concentrations, total suspended solids (TSS and turbidity vary with stream hydrology and land use. Turbidity, TSS, and microbial concentrations, loads and yields from four watersheds were assessed: an unburned montane forest, a catastrophically burned montane forest, urban land use and rangeland prairie. Concentrations and loads for most water quality variables were greatest during storm events. Turbidity was an effective indicator of TSS, E. coli and Enterococci spp. The greatest threat to public health from microbial contamination occurs during storm runoff events. Efforts to manage surface runoff and erosion would likely improve water quality of the upper Pecos River basin in New Mexico, USA.

  2. Bioremediation of Turbid Surface Water Using Seed Extract from the Moringa oleifera Lam. (Drumstick) Tree.

    Science.gov (United States)

    Lea, Michael

    2014-05-01

    An indigenous water treatment method uses Moringa oleifera seeds in the form of a crude water-soluble extract in suspension, resulting in an effective natural clarification agent for highly turbid and untreated pathogenic surface water. Efficient reduction (80.0% to 99.5%) of high turbidity produces an aesthetically clear supernatant, concurrently accompanied by 90.00% to 99.99% (1 to 4 log) bacterial reduction. Application of this low-cost Moringa oleifera protocol is recommended for water treatment where rural and peri-urban people living in extreme poverty are presently drinking highly turbid and microbiologically contaminated water. Copyright © 2014 John Wiley & Sons, Inc.

  3. Beyond Rating Curves: Time Series Models for in-Stream Turbidity Prediction

    Science.gov (United States)

    Wang, L.; Mukundan, R.; Zion, M.; Pierson, D. C.

    2012-12-01

    The New York City Department of Environmental Protection (DEP) manages New York City's water supply, which is comprised of over 20 reservoirs and supplies over 1 billion gallons of water per day to more than 9 million customers. DEP's "West of Hudson" reservoirs located in the Catskill Mountains are unfiltered per a renewable filtration avoidance determination granted by the EPA. While water quality is usually pristine, high volume storm events occasionally cause the reservoirs to become highly turbid. A logical strategy for turbidity control is to temporarily remove the turbid reservoirs from service. While effective in limiting delivery of turbid water and reducing the need for in-reservoir alum flocculation, this strategy runs the risk of negatively impacting water supply reliability. Thus, it is advantageous for DEP to understand how long a particular turbidity event will affect their system. In order to understand the duration, intensity and total load of a turbidity event, predictions of future in-stream turbidity values are important. Traditionally, turbidity predictions have been carried out by applying streamflow observations/forecasts to a flow-turbidity rating curve. However, predictions from rating curves are often inaccurate due to inter- and intra-event variability in flow-turbidity relationships. Predictions can be improved by applying an autoregressive moving average (ARMA) time series model in combination with a traditional rating curve. Since 2003, DEP and the Upstate Freshwater Institute have compiled a relatively consistent set of 15-minute turbidity observations at various locations on Esopus Creek above Ashokan Reservoir. Using daily averages of this data and streamflow observations at nearby USGS gauges, flow-turbidity rating curves were developed via linear regression. Time series analysis revealed that the linear regression residuals may be represented using an ARMA(1,2) process. Based on this information, flow-turbidity regressions with

  4. Acoustic tag detections of green sturgeon in the Columbia River and Coos Bay estuaries, Washington and Oregon, 2010–11

    Science.gov (United States)

    Hansel, Hal C.; Romine, Jason G.; Perry, Russell W.

    2017-11-08

    The Columbia River, in Washington and Oregon, and Coos Bay, in Oregon, are economically important shipping channels that are inhabited by several fishes protected under the Endangered Species Act (ESA). Maintenance of shipping channels involves dredge operations to maintain sufficient in-channel depths to allow large ships to navigate the waterways safely. Fishes entrained by dredge equipment often die or experience delayed mortality. Other potential negative effects of dredging include increased turbidity, reductions in prey resources, and the release of harmful contaminants from the dredged sediments. One species of concern is the ESA-listed green sturgeon (Acipenser medirostris; Southern Distinct Population Segment). In this study, we used acoustic telemetry to identify habitat use, arrival and departure timing, and the extent of upstream migration of green sturgeon in the Columbia River and Coos Bay to help inform dredge operations to minimize potential take of green sturgeon. Autonomous acoustic receivers were deployed in Coos Bay from the mouth to river kilometer (rkm) 21.6 from October 2009 through October 2010. In the Columbia River Estuary, receivers were deployed between the mouth and rkm 37.8 from April to November in 2010 and 2011. A total of 29 subadult and adult green sturgeon were tagged with temperature and pressure sensor tags and released during the study, primarily in Willapa Bay and Grays Harbor, Washington, and the Klamath River, Oregon. Green sturgeon detected during the study but released by other researchers also were included in the study.The number of tagged green sturgeon detected in the two estuaries differed markedly. In Coos Bay, only one green sturgeon was detected for about 2 hours near the estuary mouth. In the Columbia River Estuary, 9 green sturgeon were detected in 2010 and 10 fish were detected in 2011. Green sturgeon entered the Columbia River from May through October during both years, with the greatest numbers of fish being

  5. Spatial and temporal variation in suspended sediment, organic matter, and turbidity in a Minnesota prairie river: implications for TMDLs.

    Science.gov (United States)

    Lenhart, Christian F; Brooks, Kenneth N; Heneley, Daniel; Magner, Joseph A

    2010-06-01

    The Minnesota River Basin (MRB), situated in the prairie pothole region of the Upper Midwest, contributes excessive sediment and nutrient loads to the Upper Mississippi River. Over 330 stream channels in the MRB are listed as impaired by the Minnesota Pollution Control Agency, with turbidity levels exceeding water quality standards in much of the basin. Addressing turbidity impairment requires an understanding of pollutant sources that drive turbidity, which was the focus of this study. Suspended volatile solids (SVS), total suspended solids (TSS), and turbidity were measured over two sampling seasons at ten monitoring stations in Elm Creek, a turbidity impaired tributary in the MRB. Turbidity levels exceeded the Minnesota standard of 25 nephelometric units in 73% of Elm Creek samples. Turbidity and TSS were correlated (r (2) = 0.76), yet they varied with discharge and season. High levels of turbidity occurred during periods of high stream flow (May-June) because of excessive suspended inorganic sediment from watershed runoff, stream bank, and channel contributions. Both turbidity and TSS increased exponentially downstream with increasing stream power, bank height, and bluff erosion. However, organic matter discharged from wetlands and eutrophic lakes elevated SVS levels and stream turbidity in late summer when flows were low. SVS concentrations reached maxima at lake outlets (50 mg/l) in August. Relying on turbidity measurements alone fails to identify the cause of water quality impairment whether from suspended inorganic sediment or organic matter. Therefore, developing mitigation measures requires monitoring of both TSS and SVS from upstream to downstream reaches.

  6. [Distributions and air-sea fluxes of dissolved nitrous oxide in the Yangtze River estuary and its adjacent marine area in spring and summer].

    Science.gov (United States)

    Wang, Lan; Zhang, Gui-ling; Sun, Ming-shuang; Ren, Jing-ling

    2014-12-01

    Distributions and air-sea fluxes of nitrous oxide (N2O) in the seawaters of the Yangtze River estuary and its adjacent marine area were investigated during two cruises in March and July 2012. Dissolved N2O concentrations in surface waters ranged from 9.34 to 49.08 nmol x L(-1) with an average of (13.27 ± 6.40) nmol x L(-1) in spring and ranged from 7.27 to 27.81 nmol x L(-1) with an average of (10.62 ± 5.03) nmol x L(-1) in summer. There was no obvious difference between surface and bottom N2O concentrations. N2O concentrations in both surface and bottom waters decreased along the freshwater plume from the river mouth to the open sea. High values of dissolved N2O were found in turbidity maximum zone, which suggests that maximal turbidity enhances nitrification. Temperature had dual effects on dissolved N2O concentrations. N2O saturations in surface waters ranged from 86.9% to 351.3% with an average of (111.5 ± 41.4)% in spring and ranged from 111.7% to 396.0% with an average of (155.9 ± 68.4)% in summer. N2O were over-saturated at most stations. The sea-to-air fluxes of N2O were estimated to be (3.2 ± 10.9), (5.5 ± 19.3) and (12.2 ±52.3) μmol x (m2 x d)(-1) in spring and (7.3 ± 12.4), (12.7 ± 20.4) and (20.4 ± 35.9) μmol x (m2 x d)(-1) in summer using the LM86, W92 and RC01 relationships, respectively. The annual emissions of N2O from the Yangtze River estuary and its adjacent marine area were estimated to be 0.6 x 10(-2) Tg x a(-1) (LM86), 1.1 x 10(-2) Tg x a(-1) (W92) and 2.0 x 10(-2) Tg x a(-1) (RC01). Although the area of the Yangtze River estuary and its adjacent marine area only accounts for 0.02% of the total area of the world's oceans, their emission of N2O accounts for 0.06% of global oceanic N2O emission, indicating that the Yangtze River estuary and its adjacent marine area is an active area to produce and emit N2O.

  7. Navigation by light polarization in clear and turbid waters

    Science.gov (United States)

    Lerner, Amit; Sabbah, Shai; Erlick, Carynelisa; Shashar, Nadav

    2011-01-01

    Certain terrestrial animals use sky polarization for navigation. Certain aquatic species have also been shown to orient according to a polarization stimulus, but the correlation between underwater polarization and Sun position and hence the ability to use underwater polarization as a compass for navigation is still under debate. To examine this issue, we use theoretical equations for per cent polarization and electric vector (e-vector) orientation that account for the position of the Sun, refraction at the air–water interface and Rayleigh single scattering. The polarization patterns predicted by these theoretical equations are compared with measurements conducted in clear and semi-turbid coastal sea waters at 2 m and 5 m depth over sea floors of 6 m and 28 m depth. We find that the per cent polarization is correlated with the Sun's elevation only in clear waters. We furthermore find that the maximum value of the e-vector orientation angle equals the angle of refraction only in clear waters, in the horizontal viewing direction, over the deeper sea floor. We conclude that navigation by use of underwater polarization is possible under restricted conditions, i.e. in clear waters, primarily near the horizontal viewing direction, and in locations where the sea floor has limited effects on the light's polarization. PMID:21282170

  8. Physicochemical and biological cycles in a tide dominated, nitrogen-polluted temperate estuary

    OpenAIRE

    Wafar, M.V.M.; Le Corre, P.; Birrien, J.L.

    1988-01-01

    Spatio-temporal variations in the physicochemical and biological parameters in the Morlaix estuary on the Brittany coast of France were studied. Hydrographically, the estuary can be classified into 3 segments: the upper estuary where stratification always persists, the lower estuary where vertical homogeneity is permanent, and a middle estuary where there is a regular oscillation of stratification and homogeneity during every tidal cycle, stratification being associated with slack waters and ...

  9. Enhancing the numerical aperture of lenses using ZnO nanostructure-based turbid media

    International Nuclear Information System (INIS)

    Khokhra, Richa; Barman, Partha Bir; Kumar, Rajesh; Kumar, Manoj; Rawat, Nitin; Jang, Hwanchol; Lee, Heung-No

    2013-01-01

    Nanosheets, nanoparticles, and microstructures of ZnO were synthesized via a wet chemical method. ZnO films with a thickness of 44–46 μm were fabricated by spray coating, and these have been investigated for their potential use in turbid lens applications. A morphology-dependent comparative study of the transmittance of ZnO turbid films was conducted. Furthermore, these ZnO turbid films were used to enhance the numerical aperture (NA) of a Nikon objective lens. The variation in NA with different morphologies was explained using size-dependent scattering by the fabricated films. A maximum NA of around 1.971 of the objective lens with a turbid film of ZnO nanosheets was achieved. (paper)

  10. Determination atmospheric conditions by evaluating clearness index, turbidity and brightness of the sky

    International Nuclear Information System (INIS)

    Kandilli, C.

    2005-01-01

    There are fifteen different sky types which range from totally overcast sky to low turbidity clear sky have been defined by CIE (International Commission on Illumination). For the applications of solar energy engineering and day lighting purposes, it has a great importance to determine the physical characteristics of atmosphere and the sky type. The most important parameters which define the sky type are clearness index, turbidity and brightness. In this study, the parameters of clearness index, turbidity and brightness of the sky belong to Izmir was calculated and their relations with solar radiation and its components were represented according to 10 years data (1994-2004) of meteorology station of Ege University Solar Energy Institute. In this study, clearness index, turbidity, sky clearness and brightness were evaluated to put forward the effects of the these parameters on the atmospheric condition for designing and engineering purposes

  11. Survival of Poliovirus in Flowing Turbid Seawater Treated with Ultraviolet Light

    Science.gov (United States)

    Hill, W. F.; Hamblet, F. E.; Akin, E. W.

    1967-01-01

    The effectiveness of a model ultraviolet (UV) radiation unit for treating flowing turbid seawater contaminated with poliovirus was determined. At a turbidity of 70 ppm, the observed survival ratios ranged from 1.9 × 10-3 (99.81% reduction) to 1.5 × 10-4 (99.98% reduction) at flow rates ranging from 25 to 15 liters/min; no virus was recovered at flow rates of 10 and 5 liters/min. At a turbidity of 240 ppm, the observed survival ratios ranged from 3.2 × 10-2 (96.80% reduction) to 2.1 × 10-4 (99.98% reduction) at flow rates ranging from 25 to 5 liters/min. As expected, turbidity had an adverse influence on the effectiveness of UV radiation; however, by adjusting the flow rate of the seawater through the treatment unit, adequate disinfection was shown to be predictable. Images Fig. 1 PMID:4291955

  12. IMPACT OF TURBIDITY ON TCE AND DEGRADATION PRODUCTS IN GROUND WATER

    Science.gov (United States)

    Elevated particulate concentrations in ground water samples can bias contaminant concentration data. This has been particularly problematic for metal analyses where artificially increased turbidity levels can affect metals concentrations and confound interpretation of the data. H...

  13. Experimental determination of the boundary condition for diffuse photons in a homogeneous turbid medium

    International Nuclear Information System (INIS)

    Everitt, David L.; Zhu, Tuo; Zhu, H.-M.; Zhu, X. D.

    2000-01-01

    We present a simple experimental method that permits an empirical determination of the effective boundary condition and the extrapolated end point for the diffuse photon density in a homogeneous turbid medium. (c) 2000 Optical Society of America

  14. Turbidity of the atmospheric and water at the major ports of India

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Rodrigues, A.; Ramdasan, K.

    The atmospheric and water turbidity observed at nine major ports of India, namely Cochin, Mangalore, Mormugao, Mumbai, Jawaharlal Nehru (JNP), Kandla on the west coast and Tuticorin, Chennai and Visakhapatnam on the east coast, using the parameters...

  15. Light diffusion in N-layered turbid media: steady-state domain.

    Science.gov (United States)

    Liemert, André; Kienle, Alwin

    2010-01-01

    We deal with light diffusion in N-layered turbid media. The steady-state diffusion equation is solved for N-layered turbid media having a finite or an infinitely thick N'th layer. Different refractive indices are considered in the layers. The Fourier transform formalism is applied to derive analytical solutions of the fluence rate in Fourier space. The inverse Fourier transform is calculated using four different methods to test their performance and accuracy. Further, to avoid numerical errors, approximate formulas in Fourier space are derived. Fast solutions for calculation of the spatially resolved reflectance and transmittance from the N-layered turbid media ( approximately 10 ms) with small relative differences (<10(-7)) are found. Additionally, the solutions of the diffusion equation are compared to Monte Carlo simulations for turbid media having up to 20 layers.

  16. Grand Composite Raster Images of Turbidity in the Gulf of Maine for Stellwagen Bank NMS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This personal geodatabase contains raster images of turbidity in the Gulf of Maine. These raster images are a composite of several years (1997-2005) binned by season...

  17. Which Triggers Produce the Most Erosive, Frequent, and Longest Runout Turbidity Currents on Deltas?

    Science.gov (United States)

    Hizzett, J. L.; Hughes Clarke, J. E.; Sumner, E. J.; Cartigny, M. J. B.; Talling, P. J.; Clare, M. A.

    2018-01-01

    Subaerial rivers and turbidity currents are the two most voluminous sediment transport processes on our planet, and it is important to understand how they are linked offshore from river mouths. Previously, it was thought that slope failures or direct plunging of river floodwater (hyperpycnal flow) dominated the triggering of turbidity currents on delta fronts. Here we reanalyze the most detailed time-lapse monitoring yet of a submerged delta; comprising 93 surveys of the Squamish Delta in British Columbia, Canada. We show that most turbidity currents are triggered by settling of sediment from dilute surface river plumes, rather than landslides or hyperpycnal flows. Turbidity currents triggered by settling plumes occur frequently, run out as far as landslide-triggered events, and cause the greatest changes to delta and lobe morphology. For the first time, we show that settling from surface plumes can dominate the triggering of hazardous submarine flows and offshore sediment fluxes.

  18. Quantitative fluorescence spectroscopy in turbid media using fluorescence differential path length spectroscopy

    NARCIS (Netherlands)

    Amelink, Arjen; Kruijt, Bastiaan; Robinson, Dominic J.; Sterenborg, Henricus J. C. M.

    2008-01-01

    We have developed a new technique, fluorescence differential path length spectroscopy (FDPS), that enables the quantitative investigation of fluorophores in turbid media. FDPS measurements are made with the same probe geometry as differential path length spectroscopy (DPS) measurements. Phantom

  19. Experimental evidence of an effective medium seen by diffuse light in turbid colloids

    International Nuclear Information System (INIS)

    Contreras-Tello, H; Garcia-Valenzuela, A

    2011-01-01

    The propagation of diffuse light in turbid media is usually modeled with radiative transfer theory. When diffuse light travelling in a turbid colloid is reflected and transmitted at a flat interface where there is a refractive index mismatch, it is not clear whether one should assume the incident diffuse-light is travelling in a medium with a refractive index equal to that of the background medium (usually referred to as the matrix) or if one should assume it travels in an effective medium. Most authors simply avoid this issue and most often use the refractive index of the matrix. While this might be a good approximation for dilute turbid media one may suspect that for highly scattering materials it may not be the case. In this work we investigate experimentally this issue. Our experimental results provide clear evidence that diffuse light inside the turbid colloid travels in an effective medium and not in the matrix.

  20. Context-dependent planktivory: interacting effects of turbidity and predation risk on adaptive foraging

    Science.gov (United States)

    Pangle, Kevin L.; Malinich, Timothy D.; Bunnell, David B.; DeVries, Dennis R.; Ludsin, Stuart A.

    2012-01-01

    By shaping species interactions, adaptive phenotypic plasticity can profoundly influence ecosystems. Predicting such outcomes has proven difficult, however, owing in part to the dependence of plasticity on the environmental context. Of particular relevance are environmental factors that affect sensory performance in organisms in ways that alter the tradeoffs associated with adaptive phenotypic responses. We explored the influence of turbidity, which simultaneously and differentially affects the sensory performance of consumers at multiple trophic levels, on the indirect effect of a top predator (piscivorous fish) on a basal prey resource (zooplankton) that is mediated through changes in the plastic foraging behavior of an intermediate consumer (zooplanktivorous fish). We first generated theoretical predictions of the adaptive foraging response of a zooplanktivore across wide gradients of turbidity and predation risk by a piscivore. Our model predicted that predation risk can change the negative relationship between intermediate consumer foraging and turbidity into a humped-shaped (unimodal) one in which foraging is low in both clear and highly turbid conditions due to foraging-related risk and visual constraints, respectively. Consequently, the positive trait-mediated indirect effect (TMIE) of the top predator on the basal resource is predicted to peak at low turbidity and decline thereafter until it reaches an asymptote of zero at intermediate turbidity levels (when foraging equals that which is predicted when the top predator is absent). We used field observations and a laboratory experiment to test our model predictions. In support, we found humped-shaped relationships between planktivory and turbidity for several zooplanktivorous fishes from diverse freshwater ecosystems with predation risk. Further, our experiment demonstrated that predation risk reduced zooplanktivory by yellow perch (Perca flavescens) at a low turbidity, but had no effect on consumption at

  1. Environmental Flow for Sungai Johor Estuary

    Science.gov (United States)

    Adilah, A. Kadir; Zulkifli, Yusop; Zainura, Z. Noor; Bakhiah, Baharim N.

    2018-03-01

    Sungai Johor estuary is a vital water body in the south of Johor and greatly affects the water quality in the Johor Straits. In the development of the hydrodynamic and water quality models for Sungai Johor estuary, the Environmental Fluid Dynamics Code (EFDC) model was selected. In this application, the EFDC hydrodynamic model was configured to simulate time varying surface elevation, velocity, salinity, and water temperature. The EFDC water quality model was configured to simulate dissolved oxygen (DO), dissolved organic carbon (DOC), chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N), nitrate nitrogen (NO3-N), phosphate (PO4), and Chlorophyll a. The hydrodynamic and water quality model calibration was performed utilizing a set of site specific data acquired in January 2008. The simulated water temperature, salinity and DO showed good and fairly good agreement with observations. The calculated correlation coefficients between computed and observed temperature and salinity were lower compared with the water level. Sensitivity analysis was performed on hydrodynamic and water quality models input parameters to quantify their impact on modeling results such as water surface elevation, salinity and dissolved oxygen concentration. It is anticipated and recommended that the development of this model be continued to synthesize additional field data into the modeling process.

  2. Mercury distribution in Douro estuary (Portugal)

    Energy Technology Data Exchange (ETDEWEB)

    Ramalhosa, E. [Department of Chemistry, University of Aveiro, 3810-193 Aveiro (Portugal); Pereira, E. [Department of Chemistry, University of Aveiro, 3810-193 Aveiro (Portugal)]. E-mail: eduper@dq.ua.pt; Vale, C. [National Institute for Agronomy and Fishery Research, IPIMAR, Avenida Brasilia, 1449-006 Lisboa (Portugal); Valega, M. [Department of Chemistry, University of Aveiro, 3810-193 Aveiro (Portugal); Monterroso, P. [Department of Chemistry, University of Aveiro, 3810-193 Aveiro (Portugal); Duarte, A.C. [Department of Chemistry, University of Aveiro, 3810-193 Aveiro (Portugal)

    2005-11-15

    Determinations of dissolved reactive and total dissolved mercury, particulate and sedimentary mercury, dissolved organic carbon (DOC), particulate organic carbon (POC) and suspended particulate matter (SPM) have been made in the estuary of river Douro, in northern Portugal. The estuary was stratified by salinity along most of its length, it had low concentrations of SPM, typically <20 mg dm{sup -3}, and concentrations of DOC in the range <1.0-1.8 mg dm{sup -3}. The surface waters had a maximum dissolved concentration of reactive mercury of about 10 ng dm{sup -3}, whereas for the more saline bottom waters it was about 65 ng dm{sup -3}. The surface waters had maximum concentrations of total suspended particulate mercury of {approx}7 {mu}g g{sup -1} and the bottom waters were always <1 {mu}g g{sup -1}. Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 {mu}g g{sup -1}. The transport of mercury in surface waters was mainly associated with organic-rich particulate matter, while in bottom waters the dissolved phase transport of mercury is more important. Lower particulate organic matter, formation of chlorocomplexes in more saline waters and eventually the presence of colloids appear to explain the difference of mercury partitioning in Douro estuarine waters.

  3. Scavenging rate ecoassay: a potential indicator of estuary condition.

    Science.gov (United States)

    Porter, Augustine G; Scanes, Peter R

    2015-01-01

    Monitoring of estuary condition is essential due to the highly productive and often intensely impacted nature of these ecosystems. Assessment of the physico-chemical condition of estuaries is expensive and difficult due to naturally fluctuating water quality and biota. Assessing the vigour of ecosystem processes is an alternative method with potential to overcome much of the variability associated with physico-chemical measures. Indicators of estuary condition should have small spatial and temporal variability, have a predictable response to perturbation and be ecologically relevant. Here, we present tests of the first criterion, the spatio-temporal variability of a potential ecoassay measuring the rate of scavenging in estuaries. We hypothesised that the proposed scavenging ecoassay would not vary significantly among A) sites in an estuary, B) trips separated by weeks, or C) days in a trip. Because not all habitats are present in all estuaries, this test was undertaken in two habitats. When conducted over bare substrate there were occasional significant differences, but no discernible patterns, within levels of the experiment. When conducted over vegetated substrate, days within a trip did not vary significantly, but later trips experienced greater scavenging. This scavenging ecoassay shows potential as a tool for assessing the condition of estuarine ecosystems, and further exploration of this protocol is warranted by implementation in estuaries across a gradient of anthropogenic stress.

  4. Cyanobacteria and macroalgae in ecosystem of the Neva estuary

    Directory of Open Access Journals (Sweden)

    Nikulina V. N.

    2011-07-01

    Full Text Available The Baltic Sea and Neva estuary are plagued by coastal eutrophication. In order to estimate the scale of the problem, quantitative estimates of phytoplankton and macroalgal mats were determined in the Neva estuary. Long-term monitoring (1982–2009 of phytoplankton showed changes in its species composition and abundance. Summer phytoplankton biomass increased significantly in the 1990s, with concomitant changes in species composition, despite a decline of nutrients in the Neva estuary. The cyanobacteria Planktothrix agardhii became a dominant species. The summer biomass of phytoplankton reached a maximum of 5.2 ± 0.4 mg·L-1 in 2002–2004. Monitoring of macroalgal community in the coastal area of the Neva estuary from 2002 to 2009 showed the dominance of the filamentous green alga Cladophora glomerata in the phytobenthos. Average biomass of macroalgae in inner and outer estuary differed significantly at 132 ± 29 and 310 ± 67 g DW·m-2, respectively. This study showed, that fluctuations in macroalgal biomass reflected human influence on estuary, although it was less sensitive to human impact than the phytoplankton community. Thus qualitative and quantitative characteristics of phytoplankton and macroalgal blooms can indicate anthropogenic influence on the ecosystem, and help to better manage the Neva estuary.

  5. Surging Versus Continuous Turbidity Currents: Flow Dynamics and Deposits in an Experimental Intraslope Minibasin

    OpenAIRE

    Lamb, Michael P.; Hickson, Thomas; Marr, Jeffrey G.; Sheets, Ben; Paola, Chris; Parker, Gary

    2004-01-01

    Small intraslope basins (~100 km^2), or "minibasins," such as those found on the continental slope of the Gulf of Mexico, have been filled predominantly by turbidity currents. Each minibasin is the result of local subsidence and is partially or completely isolated from neighboring basins by ridges formed from compensational uplift. We undertook a series of experiments to investigate the relationship between the flow dynamics of turbidity currents entering a minibasin and the stratal architect...

  6. Historical land-use influences the long-term stream turbidity response to a wildfire.

    Science.gov (United States)

    Harrison, Evan T; Dyer, Fiona; Wright, Daniel W; Levings, Chris

    2014-02-01

    Wildfires commonly result in an increase in stream turbidity. However, the influence of pre-fire land-use practices on post-fire stream turbidity is not well understood. The Lower Cotter Catchment (LCC) in south-eastern Australia is part of the main water supply catchment for Canberra with land in the catchment historically managed for a mix of conservation (native eucalypt forest) and pine (Pinus radiata) plantation. In January 2003, wildfires burned almost all of the native and pine forests in the LCC. A study was established in 2005 to determine stream post-fire turbidity recovery within the native and pine forest areas of the catchment. Turbidity data loggers were deployed in two creeks within burned native forest and burned pine forest areas to determine turbidity response to fire in these areas. As a part of the study, we also determined changes in bare soil in the native and pine forest areas since the fire. The results suggest that the time, it takes turbidity levels to decrease following wildfire, is dependent upon the preceding land-use. In the LCC, turbidity levels decreased more rapidly in areas previously with native vegetation compared to areas which were previously used for pine forestry. This is likely because of a higher percentage of bare soil areas for a longer period of time in the ex-pine forest estate and instream stores of fine sediment from catchment erosion during post-fire storm events. The results of our study show that the previous land-use may exert considerable control over on-going turbidity levels following a wildfire.

  7. The association between drinking water turbidity and gastrointestinal illness: a systematic review.

    OpenAIRE

    Mann, AG; Tam, CC; Higgins, CD; Rodrigues, LC

    2007-01-01

    Abstract Background Studies suggest that routine variations in public drinking water turbidity may be associated with endemic gastrointestinal illness. We systematically reviewed the literature on this topic. Methods We searched databases and websites for relevant studies in industrialized countries. Studies investigating the association between temporal variations in drinking water turbidity and incidence of acute gastrointestinal illness were assessed for quality. We reviewed good quality s...

  8. Diel turbidity cycles in a headwater stream: evidence of nocturnal bioturbation?

    OpenAIRE

    Cooper, Richard J.; Outram, Faye; Hiscock, Kevin M.

    2016-01-01

    Purpose: A small number of recent studies have linked daily cycles in stream turbidity to nocturnal bioturbation by aquatic fauna, principally crayfish, and demonstrated this process can significantly impact upon water quality under baseflow conditions. Adding to this limited body of research, we use high-resolution water quality monitoring data to investigate evidence of diel turbidity cycles in a lowland, headwater stream with a known signal crayfish (Pacifastacus leniusculus) population an...

  9. Report Task 2.3: Particulate waste and turbidity in (marine) RAS

    OpenAIRE

    Kals, J.; Schram, E.; Brummelhuis, E.B.M.; Bakel, van, B.

    2006-01-01

    Particulate waste management and removal is one of the most problematic parts of recirculation aquaculture systems (RAS). Particulate waste and thereby turbidity originates from three major sources: fish (faeces), feed and biofilm (heterotrophic bacteria and fungi). Based on size and density there are roughly four categories of particulate waste: settable, suspended, floatable and fine or dissolved solids. Specific problems related to high turbidity are a decreasing feed intake by fish, causi...

  10. Removal of colour, turbidity, oil and grease for slaughterhouse wastewater using electrocoagulation method

    Science.gov (United States)

    Yusoff, Mohd Suffian; Azwan, Azlyza Mohd; Zamri, Mohd Faiz Muaz Ahmad; Aziz, Hamidi Abdul

    2017-10-01

    In this study electrocoagulation method is used to treat slaughterhouse wastewaters. The aim of this study is to determine the efficiency of electrocoagulation method for the removal of colour, turbidity, oil and grease of slaughterhouse wastewaters. The factors of electrode types, and voltage applied during treatment are the study parameters. The types of electrode used are Aluminium (Al) grade 6082 and Iron (Fe) grade 1050. Meanwhile, the ranges of voltage applied are 2, 4, 6, 8 volts at a time interval of 10, 20 and 30 minutes respectively. The effect of these factors on the removal of fat oil and grease (FOG), colour and turbidity are analyzed. The results show maximum removal of FOG, colour and turbidity are recorded using Fe electrode at 8 V of applied voltage with 30 minutes of treatment time. The increase in treatment time of the cell will also increase the amount of hydrogen bubbles at the cathode which results in a greater upwards flux and a faster removal of FOG,, turbidity and colour. The removal of FOG, colour and turbidity are 98%, 92% and 91 % respectively. Meanwhile, by using Al electrodes in the same condition, the removal of FOG, colour and turbidity are 91%, 85% and 87 % respectively. Whereas by using Fe-Al as electrodes pairs, the removal of FOG, colour and turbidity are found to be at 90%, 87% and 76 % respectively. In this case, the Fe-Fe pair electrodes have been proven to provide better performance for FOG, colour and turbidity removals of slaughterhouse wastewaters. Therefore, it is feasible to be considered as an alternative method for wastewater treatment.

  11. Post-lens tear turbidity and visual quality after scleral lens wear.

    Science.gov (United States)

    Carracedo, Gonzalo; Serramito-Blanco, Maria; Martin-Gil, Alba; Wang, Zicheng; Rodriguez-Pomar, Candela; Pintor, Jesús

    2017-11-01

    The aim was to evaluate the turbidity and thickness of the post-lens tear layer and its effect on visual quality in patients with keratoconus after the beginning of lens wear and before lens removal at the end of eight hours. Twenty-six patients with keratoconus (aged 36.95 ± 8.95 years) participated voluntarily in the study. The sample was divided into two groups: patients with intrastromal corneal ring (ICRS group) and patients without ICRS (KC group). Distance visual acuity (VA), contrast sensitivity, pachymetry, post-lens tear layer height and post-lens tear layer turbidity (percentage area occupied and number of particles per mm 2 ) were evaluated with optical coherence tomography before and after wearing a scleral lens. A significant increase of turbidity was found in all groups assessed (p turbidity parameters with distance VA but no correlation between turbidity and post-lens tear layer thickness at the beginning was found (p > 0.05). A strong correlation in all groups between the post-lens tear layer at the beginning and differences of tear layer thickness between two measures was also found (p turbidity. © 2017 Optometry Australia.

  12. The relationship between turbidity of mouth-rinsed water and oral health status.

    Science.gov (United States)

    Takeuchi, Susumu; Ueno, Masayuki; Takehara, Sachiko; Pham, Thuy Anh Vu; Hakuta, Chiyoko; Morishima, Seiji; Shinada, Kayoko; Kawaguchi, Yoko

    2013-01-01

    The purpose of this study was to examine the relationship between turbidity of mouth rinsed water and oral health status such as dental and periodontal conditions, oral hygiene status, flow rate of saliva and oral bacteria. Subjects were 165 patients who visited the Dental Hospital, Tokyo Medical and Dental University. Oral health status, including dental and periodontal conditions, oral hygiene status and flow rate of saliva, was clinically examined. The turbidity was measured with a turbidimeter. Quantification of Fusobacterium spp, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and total bacteria levels was performed using real-time PCR. The Pearson correlation and multiple regression analysis were used to explore the associations between the turbidity and oral health parameters. The turbidity showed significant correlations with the number of decayed teeth and deep pockets, the plaque index, extent of tongue coating and Fusobacterium spp, P. gingivalis, T. forsythia, T. denticola and total bacteria levels. In a multiple regression model, the turbidity was negatively associated with the flow rate of saliva and positively associated with the total number of bacteria (p turbidity of mouth rinsed water could be used as an indicator to evaluate oral health condition and the amount of bacteria in the oral cavity. In addition, the turbiditimeter appeared as a simple and objective device for screening abnormality of oral health condition at chair side as well as community-based research.

  13. Relationship of a turbidity of an oral rinse with oral health and malodor in Vietnamese patients.

    Science.gov (United States)

    Pham, Thuy A V

    2014-05-01

    In the present study, the relationship between the turbidity of mouth-rinse water and oral health conditions, including oral malodor, in patients with (n = 148) and without (n = 231) periodontitis was examined. The turbidity of 20 mL distilled water that the patients rinsed in their mouths 10 times was measured using a turbidimeter. Oral malodor was evaluated using an organoleptic test and Oral Chroma. Oral health conditions, including decayed teeth, periodontal status, oral hygiene status, proteolytic activity of the N-benzoyl-dl-arginine-2-napthilamide (BANA) test on the tongue coating, and salivary flow rate, were assessed. Turbidity showed significant correlations with oral malodor and all oral health parameters in the periodontitis group. In the non-periodontitis group, turbidity showed significant correlations with oral malodor and oral health parameters, including dental plaque, tongue coating, BANA test, and salivary flow rate. The regression analysis indicated that turbidity was significantly associated with methyl mercaptan and the BANA test in the periodontitis group, and with hydrogen sulfide, dental plaque, tongue coating, and salivary flow rate in the non-periodontitis group. The findings of the present study indicate that the turbidity of mouth-rinse water could be used as an indicator of oral health conditions, including oral malodor. © 2013 Wiley Publishing Asia Pty Ltd.

  14. Triggering of frequent turbidity currents in Monterey Canyon and the role of antecedent conditioning

    Science.gov (United States)

    Clare, M. A.; Rosenberger, K. J.; Talling, P.; Barry, J.; Maier, K. L.; Parsons, D. R.; Simmons, S.; Gales, J. A.; Gwiazda, R.; McGann, M.; Paull, C. K.

    2017-12-01

    Turbidity currents pose a hazard to seafloor infrastructure, deliver organic carbon and nutrients to deep-sea communities, and form economically important deposits. Thus, determining the tempo of turbidity current activity and whether different triggers result in different flow modes is important. Identification of specific triggers is challenging, however, because most studies of turbidity currents are based on their deposits. New direct monitoring of flows and environmental conditions provides the necessary temporal constraints to identify triggering mechanisms. The Coordinated Canyon Experiment (CCE) in Monterey Canyon, offshore California is the most ambitious attempt yet to measure turbidity flows and their triggers. The CCE provides precise constraint on flow timing, initiation, and potential triggers based on measurements at 7 different instrumented moorings and 2 metocean buoys. Fifteen turbidity flows were measured in 18 months; with recorded velocities >8 m/s and run-outs of up to 50 km. Presence of live estuarine foraminifera within moored sediment traps suggests that that flows originated in water depths of Turbidity currents are thought to be triggered by processes including earthquakes, river floods and storm waves. Here we analyse seismicity, local river discharge, internal tides, wave height, direction and period data. We identify no clear control of any of these individual variables on flow timing. None of the recorded earthquakes (

  15. Characterization and modeling of turbidity density plume induced into stratified reservoir by flood runoffs.

    Science.gov (United States)

    Chung, S W; Lee, H S

    2009-01-01

    In monsoon climate area, turbidity flows typically induced by flood runoffs cause numerous environmental impacts such as impairment of fish habitat and river attraction, and degradation of water supply efficiency. This study was aimed to characterize the physical dynamics of turbidity plume induced into a stratified reservoir using field monitoring and numerical simulations, and to assess the effect of different withdrawal scenarios on the control of downstream water quality. Three different turbidity models (RUN1, RUN2, RUN3) were developed based on a two-dimensional laterally averaged hydrodynamic and transport model, and validated against field data. RUN1 assumed constant settling velocity of suspended sediment, while RUN2 estimated the settling velocity as a function of particle size, density, and water temperature to consider vertical stratification. RUN3 included a lumped first-order turbidity attenuation rate taking into account the effects of particles aggregation and degradable organic particles. RUN3 showed best performance in replicating the observed variations of in-reservoir and release turbidity. Numerical experiments implemented to assess the effectiveness of different withdrawal depths showed that the alterations of withdrawal depth can modify the pathway and flow regimes of the turbidity plume, but its effect on the control of release water quality could be trivial.

  16. The design of rapid turbidity measurement system based on single photon detection techniques

    Science.gov (United States)

    Yang, Yixin; Wang, Huanqin; Cao, Yangyang; Gui, Huaqiao; Liu, Jianguo; Lu, Liang; Cao, Huibin; Yu, Tongzhu; You, Hui

    2015-10-01

    A new rapid turbidity measurement system has been developed to measure the turbidity of drinking water. To determinate the turbidity quantitatively, the total intensity of scattering light has been measured and quantified as number of photons by adopting the single photon detection techniques (SPDT) which has the advantage of high sensitivity. On the basis of SPDT, the measurement system has been built and series of experiments have been carried out. Combining then the 90° Mie scattering theory with the principle of SPDT, a turbidity measurement model has been proposed to explain the experimental results. The experimental results show that a turbidity, which is as low as 0.1 NTU (Nephelometric Turbidity Units), can be measured steadily within 100 ms. It also shows a good linearity and stability over the range of 0.1-400 NTU and the precision can be controlled within 5% full scale. In order to improve its precision and stability, some key parameters, including the sampling time and incident light intensity, have been discussed. It has been proved that, to guarantee an excellent system performance, a good compromise between the measurement speed and the low power consumption should be considered adequately depending on the practical applications.

  17. Fabrication of an inexpensive photosensitive flow through device for turbidity measurement

    International Nuclear Information System (INIS)

    Morco, Ryan P.; Dawal, Micah S.; Sucgang, Raymond J.

    2014-01-01

    The aim of this study is the construction of a portable, simple to use, on-line photosensitive device which measures turbidity in water. The turbidity measuring device uses a light emitting diode, LED, light source shining on a light dependent resistor, LDR, which is connected in series to a circuit supplying a constant voltage and a digital voltmeter, DVM. Light shine through a tube containing the sample, and onto a photosensitive circuit. A clear tube of water is the BLANK and has zero absorbance. A fraction of the incident light that i obstructed by the turbidity of the sample can be used for calculable determination of turbidity in water. The turbidity is related to the absorbance reading, following Beer's law. The amount of incident and transmitted light are expressed in voltage units, by a voltmeter. The sample is delivered into the sampling chamber by a rubber tubing attached to a power head submersible pump which is immersed in the pool of water to be sampled. The instrument shows excellent response over the range o turbidity values (5NTU to 180 NTU). Linearity (R 2= 0.95) has been achieved using the device, working with 6 trials per particular NTU value. The NTU readings of the urbidity meter were calibrated against solutions of varying NTU's measured using a HORIBA multi-parameter probe. The other features of the device include: simplicity of operation, low-cost, rugged, handy and can be used in on-line and flow mode applications. (author)

  18. Estimate of the atmospheric turbidity from three broad-band solar radiation algorithms. A comparative study

    Directory of Open Access Journals (Sweden)

    G. López

    2004-09-01

    Full Text Available Atmospheric turbidity is an important parameter for assessing the air pollution in local areas, as well as being the main parameter controlling the attenuation of solar radiation reaching the Earth's surface under cloudless sky conditions. Among the different turbidity indices, the Ångström turbidity coefficient β is frequently used. In this work, we analyse the performance of three methods based on broad-band solar irradiance measurements in the estimation of β. The evaluation of the performance of the models was undertaken by graphical and statistical (root mean square errors and mean bias errors means. The data sets used in this study comprise measurements of broad-band solar irradiance obtained at eight radiometric stations and aerosol optical thickness measurements obtained at one co-located radiometric station. Since all three methods require estimates of precipitable water content, three common methods for calculating atmospheric precipitable water content from surface air temperature and relative humidity are evaluated. Results show that these methods exhibit significant differences for low values of precipitable water. The effect of these differences in precipitable water estimates on turbidity algorithms is discussed. Differences in hourly turbidity estimates are later examined. The effects of random errors in pyranometer measurements and cloud interferences on the performance of the models are also presented. Examination of the annual cycle of monthly mean values of β for each location has shown that all three turbidity algorithms are suitable for analysing long-term trends and seasonal patterns.

  19. Estimate of the atmospheric turbidity from three broad-band solar radiation algorithms. A comparative study

    Directory of Open Access Journals (Sweden)

    G. López

    2004-09-01

    Full Text Available Atmospheric turbidity is an important parameter for assessing the air pollution in local areas, as well as being the main parameter controlling the attenuation of solar radiation reaching the Earth's surface under cloudless sky conditions. Among the different turbidity indices, the Ångström turbidity coefficient β is frequently used. In this work, we analyse the performance of three methods based on broad-band solar irradiance measurements in the estimation of β. The evaluation of the performance of the models was undertaken by graphical and statistical (root mean square errors and mean bias errors means. The data sets used in this study comprise measurements of broad-band solar irradiance obtained at eight radiometric stations and aerosol optical thickness measurements obtained at one co-located radiometric station. Since all three methods require estimates of precipitable water content, three common methods for calculating atmospheric precipitable water content from surface air temperature and relative humidity are evaluated. Results show that these methods exhibit significant differences for low values of precipitable water. The effect of these differences in precipitable water estimates on turbidity algorithms is discussed. Differences in hourly turbidity estimates are later examined. The effects of random errors in pyranometer measurements and cloud interferences on the performance of the models are also presented. Examination of the annual cycle of monthly mean values of β for each location has shown that all three turbidity algorithms are suitable for analysing long-term trends and seasonal patterns.

  20. Estimate of the atmospheric turbidity from three broad-band solar radiation algorithms. A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, G.; Batlles, F.J. [Dept. de Ingenieria Electrica y Termica, EPS La Rabida, Univ. de Huelva, Huelva (Spain)

    2004-07-01

    Atmospheric turbidity is an important parameter for assessing the air pollution in local areas, as well as being the main parameter controlling the attenuation of solar radiation reaching the Earth's surface under cloudless sky conditions. Among the different turbidity indices, the Aangstroem turbidity coefficient {beta} is frequently used. In this work, we analyse the performance of three methods based on broadband solar irradiance measurements in the estimation of {beta}. The evaluation of the performance of the models was undertaken by graphical and statistical (root mean square errors and mean bias errors) means. The data sets used in this study comprise measurements of broad-band solar irradiance obtained at eight radiometric stations and aerosol optical thickness measurements obtained at one co-located radiometric station. Since all three methods require estimates of precipitable water content, three common methods for calculating atmospheric precipitable water content from surface air temperature and relative humidity are evaluated. Results show that these methods exhibit significant differences for low values of precipitable water. The effect of these differences in precipitable water estimates on turbidity algorithms is discussed. Differences in hourly turbidity estimates are later examined. The effects of random errors in pyranometer measurements and cloud interferences on the performance of the models are also presented. Examination of the annual cycle of monthly mean values of {beta} for each location has shown that all three turbidity algorithms are suitable for analysing long-term trends and seasonal patterns. (orig.)

  1. Waterfowl migration and distribution in North West estuaries. V. 1

    International Nuclear Information System (INIS)

    Clark, N.A.; Kirby, J.S.; Langston, R.H.W.; Donald, P.; Mawdesley, T.; Evans, J.

    1990-12-01

    Waterfowl populations may be affected by proposed tidal barrage across the Mersey. This study had three objectives:-(1) to evaluate the patterns of usage of the intertidal flats of the Mersey estuary by waders and wildfowl and to establish which are the preferred areas; (2) to identify the places of origin and movement patterns of the populations of waders and wildfowl that visit the Mersey Estuary; and (3) to evaluate evidence regarding the capacity of British estuaries to absorb waders and wildfowl populations which might be displaced by a Mersey Barrage. The text and tables and results only are presented in Volume 1. (author)

  2. Fluorescence correlation spectroscopy: Ultrasensitive detection in clear and turbid media

    Science.gov (United States)

    Tahari, Abdel Kader

    In this work, I describe the development of a simple, inexpensive, and powerful alternative technique to detect and analyze, without enrichment, extremely low concentrations of cells, bacteria, viruses, and protein aggregates in turbid fluids for clinical and biotechnological applications. The anticipated applications of this technique are many. They range from the determination of the somatic cell count in milk for the dairy industry, to the enumeration and characterization of microorganisms in environmental microbiology and the food industry, and to the fast and ultrasensitive detection of protein aggregates for the diagnosis of Alzheimer's and other neurodegenerative diseases in clinical medicine. A prototype instrument has been built and allowed the detection and quantification of particles down to a few per milliliter in short scanning times. It consists of a small microscope that has a horizontal geometry and a mechanical instrument that holds a cylindrical cuvette (1 cm in diameter) with two motors that provide a rotational and a slower vertical inversion motions. The illumination focus is centered about 200 mum from the wall of the cuvette inside the sample. The total volume that is explored is large (˜1ml/min for bright particles). The data is analyzed with a correlation filter program based on particle passage pattern recognition. I will also describe further work on improving the sensitivity of the technique, expanding it for multiple-species discrimination and enumeration, and testing the prototype device in actual clinical and biotechnological applications. The main clinical application of this project seeks to establish conditions and use this new technique to quantify and size-analyze oligomeric complexes of the Alzheimer's disease beta-peptide in cerebrospinal fluid and other body fluids as a molecular biomarker for persons at risk of Alzheimer's disease dementia. The technology could potentially be extended to the diagnosis and therapeutic

  3. Acoustic Imaging of a Turbidity Current Flowing along a Channel

    Science.gov (United States)

    Hughes Clarke, J. E.; Hiroji, A.; Cahill, L.; Fedele, J. J.

    2017-12-01

    As part of a 3 month sequence of repetitive surveys and ADCP monitoring, more than 30 turbidity currents have been identified modifying a lobe channel in 130 to 190m of water on the Squamish prodelta. For a 6 day period, daily surveys at low tide tried to capture the change resulting from a single flow. On the 8thof June three flows occurred within a half hour. Along channel multibeam images of the seabed and water column were obtained from a moving vessel immediately before, during and after the passage of the third flow. In this manner the spatial extent of the in-channel and overbank flow could be constrained. By following the flow, the spatial pattern of scattering from the flow upper surface could be examined over a 2 km length of the channel. Along channel bands of high scattering appear related to enhanced release of gas along the channel flanks. Notably, no signature of the underlying across-channel bedform modulations were evident, suggesting that the upper surface of the flow does not feel the influence of the channel floor. Overbank spillage of the flow could be detected by perturbation of a plankton scattering layer just above the seabed. Additionally, evidence of enhanced overbank deposition due to flow stripping on the outer corner of a bend was identified from backscatter changes. The specific seabed alteration due to this flow could be identified and compared with the cumulative change over three months in the channel and adjacent channel-lobe transition zone. As the flow passed under the ADCP, it had a peak velocity of over 2 m/s, a thickness of 4-5m and duration of 35 minutes. Based on the timing of the flow head when in view of the surface vessel, it was decelerating as it exited the mouth of the channel.

  4. Salt Intrusion in the Tweed Estuary

    Science.gov (United States)

    Uncles, R. J.; Stephens, J. A.

    1996-09-01

    Results are presented from a 2-week field programme in the Tweed Estuary, U.K. Maximum values of the empirically based Estuarine Richardson Number, Ri E, occurred during neap tides, and minimum values occurred during spring tides. Estimated values of Ri Evaried between 0·3 and 2·3, suggesting the occurrence of partially mixed to stratified conditions, depending on tidal state and freshwater inflow. These relatively large values of Ri Ewere consistent with both observed strong salinity stratification and large salt fluxes due to vertical shear transport. Low values (0·5) values in the halocline. A velocity maximum occurred within the halocline during the early flood. Wave-like spatial oscillations of the halocline occurred on the ebb. The oscillation troughs were situated above deep holes located just down-estuary of the rail and old road bridges. There was an indication that the constricted flow between the bridges' arches resulted in enhanced mixing of near-surface waters and a thickening of the halocline. It is also possible that these wave-like structures were stationary, near-critical internal lee waves, triggered by the deep holes. Trapping of high-salinity waters occurred on the ebb. Saline pools were isolated within a deep hole or deeper section of bed by the falling halocline. When the salt wedge moved further down-estuary, the ' trapped ' waters were subjected to strongly ebbing, overlying freshwater, and were subsequently entrained and flushed. The salinity intrusion was a strong function of spring-neap tidal state and a weaker function of freshwater inflow. The estimated salinity intrusion varied from about 4·7 to 7·6 km during the fieldwork period. The strong dependence on tidal range followed from the comparable lengths of the tidal excursion and salinity intrusion. Long excursion lengths were also partly responsible for the short residence (or flushing) times and their strong dependence on spring-neap tidal state. For typical summer freshwater

  5. How well do basic models describe the turbidity currents coming down Monterey and Congo Canyon?

    Science.gov (United States)

    Cartigny, M.; Simmons, S.; Heerema, C.; Xu, J. P.; Azpiroz, M.; Clare, M. A.; Cooper, C.; Gales, J. A.; Maier, K. L.; Parsons, D. R.; Paull, C. K.; Sumner, E. J.; Talling, P.

    2017-12-01

    Turbidity currents rival rivers in their global capacity to transport sediment and organic carbon. Furthermore, turbidity currents break submarine cables that now transport >95% of our global data traffic. Accurate turbidity current models are thus needed to quantify their transport capacity and to predict the forces exerted on seafloor structures. Despite this need, existing numerical models are typically only calibrated with scaled-down laboratory measurements due to the paucity of direct measurements of field-scale turbidity currents. This lack of calibration thus leaves much uncertainty in the validity of existing models. Here we use the most detailed observations of turbidity currents yet acquired to validate one of the most fundamental models proposed for turbidity currents, the modified Chézy model. Direct measurements on which the validation is based come from two sites that feature distinctly different flow modes and grain sizes. The first are from the multi-institution Coordinated Canyon Experiment (CCE) in Monterey Canyon, California. An array of six moorings along the canyon axis captured at least 15 flow events that lasted up to hours. The second is the deep-sea Congo Canyon, where 10 finer grained flows were measured by a single mooring, each lasting several days. Moorings captured depth-resolved velocity and suspended sediment concentration at high resolution (turbidity currents; the modified Chézy model. This basic model has been very useful for river studies over the past 200 years, as it provides a rapid estimate of how flow velocity varies with changes in river level and energy slope. Chézy-type models assume that the gravitational force of the flow equals the friction of the river-bed. Modified Chézy models have been proposed for turbidity currents. However, the absence of detailed measurements of friction and sediment concentration within full-scale turbidity currents has forced modellers to make rough assumptions for these parameters. Here

  6. Turbidity forecasting at a karst spring using combined machine learning and wavelet multiresolution analysis.

    Science.gov (United States)

    Savary, M.; Massei, N.; Johannet, A.; Dupont, J. P.; Hauchard, E.

    2016-12-01

    25% of the world populations drink water extracted from karst aquifer. The comprehension and the protection of these aquifers appear as crucial due to an increase of drinking water needs. In Normandie(North-West of France), the principal exploited aquifer is the chalk aquifer. The chalk aquifer highly karstified is an important water resource, regionally speaking. Connections between surface and underground waters thanks to karstification imply turbidity that decreases water quality. Both numerous parameters and phenomenons, and the non-linearity of the rainfall/turbidity relation influence the turbidity causing difficulties to model and forecast turbidity peaks. In this context, the Yport pumping well provides half of Le Havreconurbation drinking water supply (236 000 inhabitants). The aim of this work is thus to perform prediction of the turbidity peaks in order to help pumping well managers to decrease the impact of turbidity on water treatment. Database consists in hourly rainfalls coming from six rain gauges located on the alimentation basin since 2009 and hourly turbidity since 1993. Because of the lack of accurate physical description of the karst system and its surface basin, the systemic paradigm is chosen and a black box model: a neural network model is chosen. In a first step, correlation analyses are used to design the original model architecture by identifying the relation between output and input. The following optimization phases bring us four different architectures. These models were experimented to forecast 12h ahead turbidity and threshold surpassing. The first model is a simple multilayer perceptron. The second is a two-branches model designed to better represent the fast (rainfall) and low (evapotranspiration) dynamics. Each kind of model is developed using both a recurrent and feed-forward architecture. This work highlights that feed-forward multilayer perceptron is better to predict turbidity peaks when feed-forward two-branches model is

  7. Evaluating Causes of Ecological Impairments in the Estuaries of Ukraine

    Science.gov (United States)

    Ukrainian estuaries have not undergone a systematic evaluation of the causes of ecological impairments caused by anthropogenic contamination. The objective of this evaluation is to use recently developed diagnostic tools to determine the causes of benthic ecological impairments. ...

  8. Fish and Salinity in the San Francisco Estuary

    Science.gov (United States)

    This page provides access to a set of time-series maps for six fishes that live in the SF Estuary. Maps were produced to strengthen best available science that inform actions needed to improve protection for aquatic life.

  9. Estuary 2100 Project, Phase 2: Building Partnerships for Resilient Watersheds

    Science.gov (United States)

    Information about the SFBWQP Estuary 2100 Project, Phase 2: Building Partnerships for Resilient Watersheds, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquat

  10. an ecophysiological study of the meiofauna of the swartkops estuary ...

    African Journals Online (AJOL)

    fauna in two exposed beaches in the Swartkops Estuary, near Port Elizabeth, were elucidated. PopUlation ... Variations of temperature and oxygen were found to be responsible for this pattern. ..... Apart from very low numbers of hermit crabs.

  11. Plutonium in Atlantic coastal estuaries in the southeastern United States

    International Nuclear Information System (INIS)

    Hayes, D.W.; LeRoy, J.H.; Cross, F.A.

    1975-01-01

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

  12. St. Louis River Estuary 2011 - 2013 Faucet snail location data

    Data.gov (United States)

    U.S. Environmental Protection Agency — The dataset consists of GPS coordinates for benthic invertebrate collections made in the St. Louis River Estuary in 2011 through 2013, and information on whether and...

  13. Heavy metal accumulation in a flow restricted, tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Balachandran, K.K.; Laluraj, C.M.; Nair, M.; Joseph, T.; Sheeba, P.; Venugopal, P.

    Levels of heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn), organic carbon content and textural characteristics in the surficial sediments of Cochin estuary (SW coast of India) and adjacent coast are presented. Anthropogenic inputs from...

  14. Comparative assessment of two agriculturally-influenced estuaries

    CSIR Research Space (South Africa)

    Lemley, DA

    2017-04-01

    Full Text Available This study compared the spatio-temporal dynamics in two agriculturally-influenced South African estuaries - Gamtoos and Sundays - to investigate how contrasting hydrological alterations influence physical, chemical and biological responses...

  15. Bacterial contamination of mussels at Mahe estuary, Malabar coast

    Digital Repository Service at National Institute of Oceanography (India)

    Gore, P.S.; Raveendran, O.; Iyer, T.S.G.; Varma, P.R.G.; Sankaranarayanan, V.N.

    Mussel samples from the mussel bed and near-by market, beach sand, sediment and water from the Mahe Estuary, Kerala, India were analysed for the bacterial quality. Indicator bacteria such as Escherichia coli and faecal streptococci were isolated...

  16. Habitat Scale Mapping of Fisheries Ecosystem Service Values in Estuaries

    Directory of Open Access Journals (Sweden)

    Timothy G. O'Higgins

    2010-12-01

    Full Text Available Little is known about the variability of ecosystem service values at spatial scales most relevant to local decision makers. Competing definitions of ecosystem services, the paucity of ecological and economic information, and the lack of standardization in methodology are major obstacles to applying the ecosystem-services approach at the estuary scale. We present a standardized method that combines habitat maps and habitat-faunal associations to estimate ecosystem service values for recreational and commercial fisheries in estuaries. Three case studies in estuaries on the U.S. west coast (Yaquina Bay, Oregon, east coast (Lagoon Pond, Massachusetts, and the Gulf of Mexico (Weeks Bay, Alabama are presented to illustrate our method's rigor and limitations using available data. The resulting spatially explicit maps of fisheries ecosystem service values show within and between estuary variations in the value of estuarine habitat types that can be used to make better informed resource-management decisions.

  17. How the National Estuary Programs Address Environmental Issues

    Science.gov (United States)

    Estuaries face many challenges including, alteration of natural hydrologic flows, aquatic nuisance species, climate change, declines in fish and wildlife populations, habitat loss and degradation, nutrient loads, pathogens, stormwater and toxics.

  18. Short term variations in particulate matter in Mahi river estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Rokade, M.A.; Zingde, M.D.

    The particulate matter (PM) collected from Mahi River Estuary was analysed for organic carbon (POC), nitrogen (PON), and chlorophyll a (Chl a). The concentration of PM, POC, PON and Chl a showed short term variations. Average surface concentration...

  19. Time-dependence of salinity in monsoonal estuaries

    Digital Repository Service at National Institute of Oceanography (India)

    Vijith, V.; Sundar, D.; Shetye, S.R.

    processes (diffusion, gravity current formation, impact of tidal asymmetries, etc.) is balanced by salinity-egress induced by runoff. Here we point out that the salinity field of the estuaries that are located on the coasts of the Indian subcontinent...

  20. Phytoplankton Diversity in the Cross River Estuary of Nigeria ...

    African Journals Online (AJOL)

    DR. MIKE HORSFALL

    This study was carried out to provide a concise set of structural based .... further growth of diatom in this zone due to rapid uptake of ... Table 1: Taxonomic listing and spatial distribution of phytoplankton species in Cross Rivers estuary. (+ =.

  1. Commercially important penaeid shrimp larvae in the estuaries of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Achuthankutty, C.T.

    Larval stages of the penaeid shrimps, Metapenaeus dobsoni (Miers), M. affinis (Milne - Edwards) and Penaeus merguiensis De Man were mostly distributed at the lower reaches of Mandovi and Zuari estuaries. While larvae of M. dobsoni and M. affinis...

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

    Energy Technology Data Exchange (ETDEWEB)

    Musenze, Ronald S.; Werner, Ursula [Advanced Water Management Centre (AWMC), the University of Queensland, Brisbane, Qld 4072 (Australia); Grinham, Alistair [Advanced Water Management Centre (AWMC), the University of Queensland, Brisbane, Qld 4072 (Australia); School of Civil Engineering, the University of Queensland, Brisbane, Qld 4072 (Australia); Udy, James [Healthy Waterways Ltd, P.O. Box 13086, George Street, Brisbane, Qld 4003 (Australia); Yuan, Zhiguo, E-mail: z.yuan@awmc.uq.edu.au [Advanced Water Management Centre (AWMC), the University of Queensland, Brisbane, Qld 4072 (Australia)

    2014-02-01

    Methane (CH{sub 4}) and nitrous oxide (N{sub 2}O) are two key greenhouse gases. Their global atmospheric budgeting is, however, flout with challenges partly due to lack of adequate field studies determining the source strengths. Knowledge and data limitations exist for subtropical and tropical regions especially in the southern latitudes. Surface water methane and nitrous oxide concentrations were measured in a subtropical estuarine system in the southern latitudes in an extensive field study from 2010 to 2012 and water–air fluxes estimated using models considering the effects of both wind and flow induced turbulence. The estuary was found to be a strong net source of both CH{sub 4} and N{sub 2}O all-year-round. Dissolved N{sub 2}O concentrations ranged between 9.1 ± 0.4 to 45.3 ± 1.3 nM or 135 to 435% of atmospheric saturation level, while CH{sub 4} concentrations varied between 31.1 ± 3.7 to 578.4 ± 58.8 nM or 1210 to 26,430% of atmospheric saturation level. These results compare well with measurements from tropical estuarine systems. There was strong spatial variability with both CH{sub 4} and N{sub 2}O concentrations increasing upstream the estuary. Strong temporal variability was also observed but there were no clear seasonal patterns. The degree of N{sub 2}O saturation significantly increased with NO{sub x} concentrations (r{sup 2} = 0.55). The estimated water–air fluxes varied between 0.1 and 3.4 mg N{sub 2}O m{sup −2} d{sup −1} and 0.3 to 27.9 mg CH{sub 4} m{sup −2} d{sup −1}. Total emissions (CO{sub 2}-e) were N{sub 2}O (64%) dominated, highlighting the need for reduced nitrogen inputs into the estuary. Choice of the model(s) for estimation of the gas transfer velocity had a big bearing on the estimated total emissions. - Highlights: • The estuary is a strong source of atmospheric methane and nitrous oxide. • Emissions had strong spatial-temporal variability with unclear seasonal patterns. • Dissolved gas saturation comparable to that

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    Methane (CH 4 ) and nitrous oxide (N 2 O) are two key greenhouse gases. Their global atmospheric budgeting is, however, flout with challenges partly due to lack of adequate field studies determining the source strengths. Knowledge and data limitations exist for subtropical and tropical regions especially in the southern latitudes. Surface water methane and nitrous oxide concentrations were measured in a subtropical estuarine system in the southern latitudes in an extensive field study from 2010 to 2012 and water–air fluxes estimated using models considering the effects of both wind and flow induced turbulence. The estuary was found to be a strong net source of both CH 4 and N 2 O all-year-round. Dissolved N 2 O concentrations ranged between 9.1 ± 0.4 to 45.3 ± 1.3 nM or 135 to 435% of atmospheric saturation level, while CH 4 concentrations varied between 31.1 ± 3.7 to 578.4 ± 58.8 nM or 1210 to 26,430% of atmospheric saturation level. These results compare well with measurements from tropical estuarine systems. There was strong spatial variability with both CH 4 and N 2 O concentrations increasing upstream the estuary. Strong temporal variability was also observed but there were no clear seasonal patterns. The degree of N 2 O saturation significantly increased with NO x concentrations (r 2 = 0.55). The estimated water–air fluxes varied between 0.1 and 3.4 mg N 2 O m −2 d −1 and 0.3 to 27.9 mg CH 4 m −2 d −1 . Total emissions (CO 2 -e) were N 2 O (64%) dominated, highlighting the need for reduced nitrogen inputs into the estuary. Choice of the model(s) for estimation of the gas transfer velocity had a big bearing on the estimated total emissions. - Highlights: • The estuary is a strong source of atmospheric methane and nitrous oxide. • Emissions had strong spatial-temporal variability with unclear seasonal patterns. • Dissolved gas saturation comparable to that in tropical rivers and polluted estuaries. • Emissions are dominated by N2O, which

  4. Review of Epidemiological Studies of Drinking-Water Turbidity in Relation to Acute Gastrointestinal Illness.

    Science.gov (United States)

    De Roos, Anneclaire J; Gurian, Patrick L; Robinson, Lucy F; Rai, Arjita; Zakeri, Issa; Kondo, Michelle C

    2017-08-17

    Turbidity has been used as an indicator of microbiological contamination of drinking water in time-series studies attempting to discern the presence of waterborne gastrointestinal illness; however, the utility of turbidity as a proxy exposure measure has been questioned. We conducted a review of epidemiological studies of the association between turbidity of drinking-water supplies and incidence of acute gastrointestinal illness (AGI), including a synthesis of the overall weight of evidence. Our goal was to evaluate the potential for causal inference from the studies. We identified 14 studies on the topic (distinct by region, time period and/or population). We evaluated each study with regard to modeling approaches, potential biases, and the strength of evidence. We also considered consistencies and differences in the collective results. Positive associations between drinking-water turbidity and AGI incidence were found in different cities and time periods, and with both unfiltered and filtered supplies. There was some evidence for a stronger association at higher turbidity levels. The studies appeared to adequately adjust for confounding. There was fair consistency in the notable lags between turbidity measurement and AGI identification, which fell between 6 and 10 d in many studies. The observed associations suggest a detectable incidence of waterborne AGI from drinking water in the systems and time periods studied. However, some discrepant results indicate that the association may be context specific. Combining turbidity with seasonal and climatic factors, additional water quality measures, and treatment data may enhance predictive modeling in future studies. https://doi.org/10.1289/EHP1090.

  5. Changes of turbidity during the phenol oxidation by photo-Fenton treatment.

    Science.gov (United States)

    Villota, Natalia; Camarero, Luis M; Lomas, Jose M; Perez, Jonatan

    2014-11-01

    Turbidity presented by phenol solutions oxidized with Fenton reagent shows the tendency of a first order intermediate kinetics. Thus, turbidity can be considered a representative parameter of the presence of intermediate oxidation species, which are generated along the decomposition of toxic and reluctant contaminants, such as phenol. Moreover, that parameter presents a linear dependence with the catalyst dosage, but is also determined by the initial contaminant load. When analyzing the oxidation mechanism of phenol, it is found that the maximum turbidity occurs when the treatment is carried out at oxidant to phenol molar ratios R = 4.0. These oxidation conditions correspond to the presence of a reaction mixture mainly composed of dihydroxylated rings, precursors of the muconic acid formation. The oxidation via "para" comprises the formation reactions of charge transfer complexes (quinhydrone), between the para-dihydroxylated intermediates (hydroquinone) and the para-substituted quinones (p-benzoquinone), which are quite unstable and reactive species, quickly decomposed into hydroxyhydroquinones. Working with oxidant ratios up to R = 6.0, the maximum observed value of turbidity in the oxidized solutions is kept almost constant. It is found that, in these conditions, the pyrogallol formation is maximal, what is generated through the degradation of ortho-species (catechol and ortho-benzoquinone) and meta-substituted (resorcinol). Operating with ratios over R = 6.0, these intermediates are decomposed into biodegradable acids, generating lower turbidity in the solution. Then, the residual turbidity is a function of the molar ratio of the ferrous ions vs. moles of oxidant utilized in the essays, that lets to estimate the stoichiometric dosage of catalyst as 20 mg/L at pH = 3.0, whereas operating in stoichiometric conditions, R = 14.0, the residual turbidity of water results almost null.

  6. Sex in murky waters: algal-induced turbidity increases sexual selection in pipefish.

    Science.gov (United States)

    Sundin, Josefin; Aronsen, Tonje; Rosenqvist, Gunilla; Berglund, Anders

    2017-01-01

    Algal-induced turbidity has been shown to alter several important aspects of reproduction and sexual selection. However, while turbidity has been shown to negatively affect reproduction and sexually selected traits in some species, it may instead enhance reproductive success in others, implying that the impact of eutrophication is far more complex than originally believed. In this study, we aimed to provide more insight into these inconsistent findings. We used molecular tools to investigate the impact of algal turbidity on reproductive success and sexual selection on males in controlled laboratory experiments, allowing mate choice, mating competition, and mate encounter rates to affect reproduction. As study species, we used the broad-nosed pipefish, Syngnathus typhle , a species practicing male pregnancy and where we have previously shown that male mate choice is impaired by turbidity. Here, turbidity instead enhanced sexual selection on male size and mating success as well as reproductive success. Effects from mating competition and mate encounter rates may thus override effects from mate choice based on visual cues, producing an overall stronger sexual selection in turbid waters. Hence, seemingly inconsistent effects of turbidity on sexual selection may depend on which mechanisms of sexual selection that have been under study. Algal blooms are becoming increasingly more common due to eutrophication of freshwater and marine environments. The high density of algae lowers water transparency and reduces the possibility for fish and other aquatic animals to perform behaviors dependent on vision. We have previously shown that pipefish are unable to select the best partner in mate choice trials when water transparency was reduced. However, fish might use other senses than vision to compensate for the reduction in water transparency. In this study, we found that when fish were allowed to freely interact, thereby allowing competition between partners and direct contact

  7. Removal of turbidity and suspended solids backwash water from rapid sand filter by using electrocoagulation

    Directory of Open Access Journals (Sweden)

    AR Yari

    2016-07-01

    Full Text Available Introduction: By appropriate method can be recycled more than 95 percent effluent backwashing the filter. This study aimed to examine the efficiency of the electrocoagulation process on turbidity and suspended solids removal from backwash effluent of rapid sand filter of water treatment plants No 1 in Karaj. Methods: This bench-scale experimental study was carried out on the samples of backwash effluent in a batch system. The Plexiglas tank with a volume of 4 liters, containing of 4 plate electrodes made of aluminum and iron was connected to a direct current power supply. Samples every 15 minutes to measure turbidity and suspended solids collected in the middle of the reactor and examined. Effect of several parameters such as current density, reaction time and voltage were studied. The total number of samples tested were 48. Turbidity and total suspended solids was measured by nephlometry and gravimetric method, respectively. Results: The highest removal efficiency of turbidity and suspended solids in reaction time of 60 minutes, current density of 2 mA and a voltage of 45 mV was observed. The highest removal efficiency of turbidity in aluminum and iron electrodes were 96.83 and 83.77 %, respectively. Also The highest removal efficiency of suspended solids were 96.73 and 86.22 %, respectively. Conclusion: The results showed that electro- coagulation process can be a good choice to remove turbidity and suspended from backwash of rapid sand filter. Aluminum electrode efficiency in the removal of turbidity and suspended solids was greater than the iron electrode.

  8. Cladocerans (Branchiopoda) of a tropical estuary in Brazil

    OpenAIRE

    Paranaguá, M. N; Neumann-Leitão, S; Nogueira-Paranhos, J. D; Silva, T. A.; Matsumura-Tundisi, T.

    2005-01-01

    The study was conducted in the Capibaribe river estuary in Recife (Brazil) to assess the role played by cladocerans in a eutrophic environment. Samplings were carried out monthly at 4 fixed stations along the estuary from July 1987 to June 1988. Collections were made with a plankton net of 65 micrometers mesh size. Six cladocerans species were registered: Penilia avirostris, Diaphanosoma spinulosum, Chydorus barroisi, Ceriodaphnia rigaudi, Ilyocryptus spinifer, and Moina micrura. The most fre...

  9. Contamination and restoration of an estuary affected by phosphogypsum releases

    International Nuclear Information System (INIS)

    Villa, M.; Mosqueda, F.; Hurtado, S.; Mantero, J.; Manjon, G.; Perianez, R.; Vaca, F.; Garcia-Tenorio, R.

    2009-01-01

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

  10. Juvenile salmon usage of the Skeena River estuary.

    Science.gov (United States)

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

    2015-01-01

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

  11. Contamination and restoration of an estuary affected by phosphogypsum releases

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-12-15

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

  12. Continuous resistivity profiling data from the Corsica River Estuary, Maryland

    Science.gov (United States)

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

    2011-01-01

    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

  13. Hydro-morphological modelling of small, wave-dominated estuaries

    Science.gov (United States)

    Slinger, Jill H.

    2017-11-01

    Small, intermittently open or closed estuaries are characteristic of the coasts of South Africa, Australia, California, Mexico and many other areas of the world. However, modelling attention has tended to focus on big estuaries that drain large catchments and serve a wide diversity of interests e.g. agriculture, urban settlement, recreation, commercial fishing. In this study, the development of a simple, parametric, system dynamics model to simulate the opening and closure of the mouths of small, wave-dominated estuaries is reported. In the model, the estuary is conceived as a basin with a specific water volume to water level relationship, connected to the sea by a channel of fixed width, but variable sill height. Changes in the form of the basin are not treated in the model, while the dynamics of the mouth channel are central to the model. The magnitude and direction of the flow through the mouth determines whether erosion or deposition of sediment occurs in the mouth channel, influencing the sill height. The model is implemented on the Great Brak Estuary in South Africa and simulations reveal that the raised low water levels in the estuary during spring tide relative to neap tide, are occasioned by the constriction of the tidal flow through the shallow mouth. Freshwater inflows to the estuary are shown to be significant in determining the behaviour of the inlet mouth, a factor often ignored in studies on tidal inlets. Further it is the balance between freshwater inflows and wave events that determines the opening or closure of the mouth of a particular estuary.

  14. Functional diversity of fish in estuaries at a global extent

    OpenAIRE

    Rita P Vasconcelos; Sébastien Villéger; François Guilhaumon

    2015-01-01

    Biodiversity is currently viewed as a framework encompassing multiple facets of the variety of life, including taxonomic and functional aspects. Species richness and composition of fish assemblages in estuaries is defined by global to local processes acting on community colonization. The present study further investigates how biodiversity of fish assemblages varies among estuaries globally, by simultaneously analysing taxonomic and functional richness and diversity of assemblages. A comprehen...

  15. Parallel structure among environmental gradients and three trophic levels in a subarctic estuary

    Science.gov (United States)

    Speckman, Suzann G.; Piatt, John F.; Minte-Vera, Carolina V.; Parrish, Julia K.

    2005-07-01

    We assessed spatial and temporal variability in the physical environment of a subarctic estuary, and examined concurrent patterns of chlorophyll α abundance (fluorescence), and zooplankton and forage fish community structure. Surveys were conducted in lower Cook Inlet, Alaska, during late July and early August from 1997 through 1999. Principle components analysis (PCA) revealed that spatial heterogeneity in the physical oceanographic environment of lower Cook Inlet could be modeled as three marine-estuarine gradients characterized by temperature, salinity, bottom depth, and turbidity. The gradients persisted from 1997 through 1999, and PCA explained 68% to 92% of the variance in physical oceanography for each gradient-year combination. Correlations between chlorophyll α abundance and distribution and the PCA axes were weak. Chlorophyll was reduced by turbidity, and low levels occurred in areas with high levels of suspended sediments. Detrended correspondence analysis (DCA) was used to order the sample sites based on species composition and to order the zooplankton and forage fish taxa based on similarities among sample sites for each gradient-year. Correlations between the structure of the physical environment (PCA axis 1) and zooplankton community structure (DCA axis 1) were strong ( r = 0.43-0.86) in all years for the three marine-estuarine gradients, suggesting that zooplankton community composition was structured by the physical environment. The physical environment (PCA) and forage fish community structure (DCA) were weakly correlated in all years along Gradient 2, defined by halocline intensity and surface temperature and salinity, even though these physical variables were more important for defining zooplankton habitats. However, the physical environment (PCA) and forage fish community structure (DCA) were strongly correlated along the primary marine-estuarine gradient (#1) in 1997 ( r = 0.87) and 1998 ( r = 0.82). The correlation was poor ( r = 0.32) in

  16. Sources, Ages, and Alteration of Organic Matter in Estuaries.

    Science.gov (United States)

    Canuel, Elizabeth A; Hardison, Amber K

    2016-01-01

    Understanding the processes influencing the sources and fate of organic matter (OM) in estuaries is important for quantifying the contributions of carbon from land and rivers to the global carbon budget of the coastal ocean. Estuaries are sites of high OM production and processing, and understanding biogeochemical processes within these regions is key to quantifying organic carbon (Corg) budgets at the land-ocean margin. These regions provide vital ecological services, including nutrient filtration and protection from floods and storm surge, and provide habitat and nursery areas for numerous commercially important species. Human activities have modified estuarine systems over time, resulting in changes in the production, respiration, burial, and export of Corg. Corg in estuaries is derived from aquatic, terrigenous, and anthropogenic sources, with each source exhibiting a spectrum of ages and lability. The complex source and age characteristics of Corg in estuaries complicate our ability to trace OM along the river-estuary-coastal ocean continuum. This review focuses on the application of organic biomarkers and compound-specific isotope analyses to estuarine environments and on how these tools have enhanced our ability to discern natural sources of OM, trace their incorporation into food webs, and enhance understanding of the fate of Corg within estuaries and their adjacent waters.

  17. Wind Wave Behavior in Fetch and Depth Limited Estuaries

    Science.gov (United States)

    Karimpour, Arash; Chen, Qin; Twilley, Robert R.

    2017-01-01

    Wetland dominated estuaries serve as one of the most productive natural ecosystems through their ecological, economic and cultural services, such as nursery grounds for fisheries, nutrient sequestration, and ecotourism. The ongoing deterioration of wetland ecosystems in many shallow estuaries raises concerns about the contributing erosive processes and their roles in restraining coastal restoration efforts. Given the combination of wetlands and shallow bays as landscape components that determine the function of estuaries, successful restoration strategies require knowledge of wind wave behavior in fetch and depth limited water as a critical design feature. We experimentally evaluate physics of wind wave growth in fetch and depth limited estuaries. We demonstrate that wave growth rate in shallow estuaries is a function of wind fetch to water depth ratio, which helps to develop a new set of parametric wave growth equations. We find that the final stage of wave growth in shallow estuaries can be presented by a product of water depth and wave number, whereby their product approaches 1.363 as either depth or wave energy increases. Suggested wave growth equations and their asymptotic constraints establish the magnitude of wave forces acting on wetland erosion that must be included in ecosystem restoration design.

  18. Probable movement and mixing of contaminants in tidal estuaries - A field study in Kundalika Estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    DineshKumar, P.K.; Sarma, R.V.; Zingde, M.D.

    The probable movement and mixing of contaminants within and through the Kundalika river estuary along the west coast of India are studied Neutrally buoyant biplane drogues, floats and dye were tracked at different stages of the tide to assess...

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

    International Nuclear Information System (INIS)

    Zhang Yuanzhi; Lin Hui; Chen, Chuqun; Chen Liding; Zhang Bing; Gitelson, Anatoly A

    2011-01-01

    The objective of this work is to estimate chlorophyll-a (chl-a) concentration in the Pearl River estuary in China. To test the performance of algorithms for the estimation of the chl-a concentration in these productive turbid waters, the maximum band ratio (MBR) and near-infrared-red (NIR-red) models are used in this study. Specific focus is placed on (a) comparing the ability of the models to estimate chl-a in the range 1-12 mg m -3 , which is typical for coastal and estuarine waters, and (b) assessing the potential of the Moderate Resolution Imaging Spectrometer (MODIS) and Medium Resolution Imaging Spectrometer (MERIS) to estimate chl-a concentrations. Reflectance spectra and water samples were collected at 13 stations with chl-a ranging from 0.83 to 11.8 mg m -3 and total suspended matter from 9.9 to 21.5 g m -3 . A close relationship was found between chl-a concentration and total suspended matter concentration with the determining coefficient (R 2 ) above 0.89. The MBR calculated in the spectral bands of MODIS proved to be a good proxy for chl-a concentration (R 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 -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.

  20. A Tree-Ring Reconstruction of the Salinity Gradient in the Northern Estuary of San Francisco Bay

    Directory of Open Access Journals (Sweden)

    David W. Stahle

    2011-04-01

    Full Text Available Blue oak tree-ring chronologies correlate highly with winter–spring precipitation totals over California, with Sacramento and San Joaquin river stream flow, and with seasonal variations in the salinity gradient in San Francisco Bay. The convergence of fresh and saline currents can influence turbidity, sediment accumulation, and biological productivity in the estuary. Three selected blue oak chronologies were used to develop a 625-year-long reconstruction of the seasonal salinity gradient, or low salinity zone (LSZ, which provides a unique perspective on the interannual-to-decadal variability of this important estuarine habitat indicator. The reconstruction was calibrated with instrumental LSZ data for the winter–spring season, and explains 73% of the variance in the February–June position of the LSZ from 1956 to 2003. Because this calibration period post-dates the sweeping changes that have occurred to land cover, channel morphology, and natural streamflow regimes in California, the reconstruction provides an idealized estimate for how the LSZ might have fluctuated under the seasonal precipitation variations of the past 625 years, given the modern geometry and bathymetry of the estuary and land cover across the drainage basin. The February–June season integrates precipitation and runoff variability during the cool season, and does not extend into the late-summer dry season when LSZ extremes can negatively affect Sacramento–San Joaquin Delta (Delta agriculture and some aquatic organisms. However, there is such strong inter-seasonal persistence in the instrumental LSZ data that precipitation totals during the cool season can strongly pre-condition LSZ position in late summer. The 625-year-long reconstruction indicates strong interannual and decadal variability, the frequent recurrence of consecutive 2-year LSZ maxima and minima, large-scale ocean atmospheric forcing, and an interesting asymmetrical influence of warm El Ni

  1. Electrochemical filtration for turbidity removal in industrial cooling/process water systems

    International Nuclear Information System (INIS)

    Kumbhar, A.G.; Venkateswaran, G.

    2008-01-01

    Water samples of large cooling water reservoirs may look visibly clear and transparent, but still may contain sub-micron size particles at sub-parts-per-million levels. Deposition of these particles on heat exchanger surfaces, reduces the heat transfer efficiency in power industry. In nuclear power plants, additionally it creates radiation exposure problems due to activation of fine metallic turbidity in the reactor core and its subsequent transfer to out-of-core surfaces. Sub-micron filtration creates back high-pressure problem. Zeta filters available commercially are prescribed for separating either positively or negatively charged particles. They are of once-use and throw-type. Precipitation surface modified ion exchangers impart chemical impurities to the system. Thus, sub-micron size and dilute turbidity removal from large volumes of waters such as heat exchanger cooling water in nuclear and power industry poses a problem. Electro deposition of the turbidity causing particles, on porous carbon/graphite felt electrodes, is one of the best suited methods for turbidity removal from large volumes of water due to the filter's high permeability, inertness to the system and regenerability resulting in low waste generation. Initially, active indium turbidity removal from RAPS-1 heavy water moderator system, and microbes removal from heat exchanger cooling lake water of RAPS 1 and 2 were demonstrated with in-house designed and fabricated prototype electrochemical filter (ECF). Subsequently, a larger size, high flow filter was fabricated and deployed for iron turbidity removal from active process waters system of Kaiga Generation Station unit 1 and silica and iron turbidity removal from cooling water pond used for heat exchanger of a high temperature high pressure (HTHP) loop at WSCD, Kalpakkam. The ECF proved its exclusive utility for sub-micron size turbidity removal and microbes removal. ECF maneuverability with potential and current for both positively and

  2. Turbidity and chlorine demand reduction using alum and moringa flocculation before household chlorination in developing countries.

    Science.gov (United States)

    Preston, Kelsey; Lantagne, Daniele; Kotlarz, Nadine; Jellison, Kristen

    2010-03-01

    Over 1.1 billion people in the world lack access to improved drinking water. Diarrhoeal and other waterborne diseases cause an estimated 1.87 million deaths per year. The Safe Water System (SWS) is a household water treatment intervention that reduces diarrhoeal disease incidence among users in developing countries. Turbid waters pose a particular challenge to implementation of SWS programmes; although research shows that a 3.75 mg l(-1) sodium hypochlorite dose effectively treats turbid waters, users sometimes object to the strong chlorine taste and prefer to drink water that is more aesthetically pleasing. This study investigated the efficacy of two locally available chemical water treatments-alum and Moringa oleifera flocculation-to reduce turbidity and chlorine demand at turbidities of 10, 30, 70, 100 and 300 NTU. Both treatments effectively reduced turbidity (alum flocculation 23.0-91.4%; moringa flocculation 14.2-96.2%). Alum flocculation effectively reduced chlorine demand compared with controls at 30, 70, 100 and 300 NTU (p=0.01-0.06). Moringa flocculation increased chlorine demand to the point where adequate free chlorine residual was not maintained for 24 hours after treatment. Alum pretreatment is recommended in waters>or=30 NTU for optimum water disinfection. Moringa flocculation is not recommended before chlorination.

  3. Single shot imaging through turbid medium and around corner using coherent light

    Science.gov (United States)

    Li, Guowei; Li, Dayan; Situ, Guohai

    2018-01-01

    Optical imaging through turbid media and around corner is a difficult challenge. Even a very thin layer of a turbid media, which randomly scatters the probe light, can appear opaque and hide any objects behind it. Despite many recent advances, no current method can image the object behind turbid media with single record using coherent laser illumination. Here we report a method that allows non-invasive single-shot optical imaging through turbid media and around corner via speckle correlation. Instead of being as an obstacle in forming diffractionlimited images, speckle actually can be a carrier that encodes sufficient information to imaging through visually opaque layers. Optical imaging through turbid media and around corner is experimentally demonstrated using traditional imaging system with the aid of iterative phase retrieval algorithm. Our method require neither scan of illumination nor two-arm interferometry or long-time exposure in acquisition, which has new implications in optical sensing through common obscurants such as fog, smoke and haze.

  4. Extraction of natural coagulant from peanut seeds for treatment of turbid water

    International Nuclear Information System (INIS)

    Birima, A H; Desa, M N M; Muda, Z C; Hammad, H A

    2013-01-01

    This study investigates the potential of peanut seeds as an environmental friendly and natural coagulant for the treatment of high turbid water. The peanut seeds have been used after oil extraction; and the active coagulation component was extracted by distilled water and salt solution of different salt concentrations. The salts used were NaCl, KNO 3 , KCl, NH 4 Cl and NaNO 3 . Synthetic water with 200 NTU turbidity was used. Peanut extracted with NaCl (PC-NaCl) could effectively remove 92% of the 200 NTU turbidity using only 20 mg/l, while peanut seeds extracted with distilled water (PC-DW) could remove only 31.5% of the same turbidity with the same dosage. The coagulant dosage did not affected by the concentration of the salt solution, however, residual turbidity decreased with increasing the concentration of the salt; and the relationship was found to be a second order polynomial curve with R 2 of 0.9312. The other salts tested were also found to be good solvents to extract the active coagulation component with no much difference from NaCl solution in terms of efficiency.

  5. Limitations of turbidity process probes and formazine as their calibration standard.

    Science.gov (United States)

    Münzberg, Marvin; Hass, Roland; Dinh Duc Khanh, Ninh; Reich, Oliver

    2017-01-01

    Turbidity measurements are frequently implemented for the monitoring of heterogeneous chemical, physical, or biotechnological processes. However, for quantitative measurements, turbidity probes need calibration, as is requested and regulated by the ISO 7027:1999. Accordingly, a formazine suspension has to be produced. Despite this regulatory demand, no scientific publication on the stability and reproducibility of this polymerization process is available. In addition, no characterization of the optical properties of this calibration material with other optical methods had been achieved so far. Thus, in this contribution, process conditions such as temperature and concentration have been systematically investigated by turbidity probe measurements and Photon Density Wave (PDW) spectroscopy, revealing an influence on the temporal formazine formation onset. In contrast, different reaction temperatures do not lead to different scattering properties for the final formazine suspensions, but give an access to the activation energy for this condensation reaction. Based on PDW spectroscopy data, the synthesis of formazine is reproducible. However, very strong influences of the ambient conditions on the measurements of the turbidity probe have been observed, limiting its applicability. The restrictions of the turbidity probe with respect to scatterer concentration are examined on the basis of formazine and polystyrene suspensions. Compared to PDW spectroscopy data, signal saturation is observed at already low reduced scattering coefficients.

  6. A time series study of drug sales and turbidity of tap water in Le Havre, France.

    Science.gov (United States)

    Beaudeau, Pascal; Le Tertre, Alain; Zeghnoun, Abdelkrim; Zanobetti, Antonella; Schwartz, Joel

    2012-06-01

    The 80,000 inhabitants of the lower part of Le Havre obtain their water supply from two karstic springs, Radicatel and Saint-Laurent. Until 2000, the Radicatel water was settled when turbidity exceeded 3 NTU, then filtered and chlorinated, whereas the Saint-Laurent water was simply chlorinated. Our study aimed to characterize the link between water turbidity and the incidence of acute gastroenteritis (AGE). Records on drug sales used for the treatment of AGE were collected from January 1994 to June 1996 (period 1) and from March 1997 to July 2000 (period 2). Daily counts of drug sales were modeled using a Poisson Regression. We used data set 2 as a discovery set, identifying relevant (i.e. both significant and plausible) exposure covariates and lags. We then tested this model on period 1 as a replication dataset. In period 2, the daily drug sales correlated with finished water turbidity at both resources. Settling substantially modified the risk related to turbidity of both raw and finished waters at Radicatel. Correlations were reproducible in period 1 for water from the Radicatel spring. Timeliness of treatment adaptation to turbidity conditions appears to be crucial for reducing the infectious risk due to karstic waters.

  7. Using Coagulation Process in Optimizing Natural Organic Matter Removal from Low Turbidity Waters

    Directory of Open Access Journals (Sweden)

    Alireza Mesdaghinia

    2006-03-01

    Full Text Available Optimization of coagulation process  for efficient removal of Natural Organic Matters (NOM has gained a lot of focus over the last years to meet the requirements of enhanced coagulation. NOM comprises both particulate and soluble components which the latter usually comprises the main portion. Removal of soluble NOM from low turbidity waters by coagulation is not a successful process unless enough attention is paid to stages of formation and development of both micro and macro-flocs. This study, which presents experimental results from pilot scale research studies aimed at optimizing coagulation process applied to synthetic raw waters supplemented by adding commercial humic acid with low turbidity levels, explains how pH and turbidity can be controlled to maximize soluble NOM removal. The removal of NOM at various coagulant doses and coagulation pHs has been assessed through raw and treated (coagulated-settled water measurements of total organic carbon (TOC. For low turbidity waters, essential floc nucleation sites can be provided by creating synthetic turbidities, for example by adding clay. Adjusting the initial pH at 5.5 or adding clay before coagulant addition allows the formation of micro-flocs as well as formation of the insoluble flocs at low coagulant doses.

  8. Sediment concentrations, flow conditions, and downstream evolution of two turbidity currents, Monterey Canyon, USA

    Science.gov (United States)

    Xu, Jingping; Octavio E. Sequeiros,; Noble, Marlene A.

    2014-01-01

    The capacity of turbidity currents to carry sand and coarser sediment from shallow to deep regions in the submarine environment has attracted the attention of researchers from different disciplines. Yet not only are field measurements of oceanic turbidity currents a rare achievement, but also the data that have been collected consist mostly of velocity records with very limited or no suspended sediment concentration or grain size distribution data. This work focuses on two turbidity currents measured in Monterey Canyon in 2002 with emphasis on suspended sediment from unique samples collected within the body of these currents. It is shown that concentration and grain size of the suspended material, primarily controlled by the source of the gravity flows and their interaction with bed material, play a significant role in shaping the characteristics of the turbidity currents as they travel down the canyon. Before the flows reach their normal or quasi-steady state, which is defined by bed slope, bed roughness, and suspended grain size, they might pass through a preliminary adjustment stage where they are subject to capacity-driven deposition, and release heavy material in excess. Flows composed of fine (silt/clay) sediments tend to be thicker than those with sands. The measured velocity and concentration data confirm that flow patterns differ between the front and body of turbidity currents and that, even after reaching normal state, the flow regime can be radically disrupted by abrupt changes in canyon morphology.

  9. NEW DATA ABOUT MACROZOOBENTHOS OF BEYSUGSKY ESTUARY (SEA OF AZOV

    Directory of Open Access Journals (Sweden)

    N. I. Bulysheva

    2013-01-01

    Full Text Available Abstract. Aim. Beysugsky Estuary is one of the biggest estuaries of the Azov-Kuban’ lowland. Like the other water bodies in the South of Russia, this one is subject to strong anthropogenic load: detachment of the freshwater part for establishing the Beysug spawning area; regulation of the flow of the rivers feeding the estuary; destruction of the Yasenskaya spit and narrowing of the Bugaz mouth; disorganized tourism. The ongoing reformation of the ecosystem makes it necessary to carry out the analyses of the modern state of the biota of this water body and uncover reasons and regularities of its change.Location. Beysug Estuary of the Sea of Azov.Methods. Quantitative zoobenthos samples were taken with the Petersen dredger (sampling area 0,034 m2 from board of the inflatable “Zodiac” boat. Qualitative samples were taken in the coastal zone by hand and with the dredge. All the samples taken were washed through the bag made of mill sieve with mesh size 0,5 mm, and then were fixed in a plastic bucket by 4 % formaldehyde (quantitative samples or 70 % ethyl alcohol (qualitative samples. Taking and processing of samples were carried out in field and laboratory environment using common methods. 22 samples at 7 stations were taken in total.Results. Macrozoobenthos was presented by 14 invertebrate species. Estuarine fauna is the depleted version of the euryhaline one of the Sea of Azov with Holocene relic macrophyte-dwelling elements. Biodiversity and quantitative characters of the estuarine communities decrease from west to east. Pelophylic detritophages predominated in the benthic communities of the estuary. The results of this research are meant to be used for uncovering historical ways of forming of benthic fauna and clearing up the dependence of community structure on the seawater influence, freshwater flow, regulation of freshwater and seawater sources, nature of changing of faunas at salinization of estuaries connected with the sea and the

  10. Distribution and assessment of sediment toxicity in Tamaki Estuary, Auckland, New Zealand

    Science.gov (United States)

    Abrahim, G. M. S.; Parker, R. J.; Nichol, S. L.

    2007-07-01

    Heavy metal levels in surface sediments from Tamaki Estuary demonstrate significant up estuary increases in Cu, Pb, Zn, Cd and mud concentrations. Increased metal levels towards the head of the estuary are linked to local catchment sources reflecting the historical development, industrialisation and urbanisation of catchment areas surrounding the upper estuary. The relatively narrow constriction in the middle estuary (Panmure area), makes it susceptible to accumulation of upper estuary pollutants, since the constriction reduces circulation and extends the time required for fine waterborne sediments in the upper estuary to exchange with fresh coastal water. As a result fine fraction sediments trapped in the upper estuary facilitate capture and retention of pollutants at the head of the estuary. The increase in sandy mud poor sediments towards the mouth of the estuary is associated with generally low metal concentrations. The estuary’s geomorphic shape with a mid estuary constriction, sediment texture and mineralogy and catchment history are significant factors in understanding the overall spatial distribution of contaminants in the estuary. Bulk concentration values for Cu, Pb, Zn, and Cd in all the studied surface samples occur below ANZECC ISQG-H toxicity values. Cd and Cu concentrations are also below the ISQG-L toxicity levels for these elements. However, Pb and Zn concentrations do exceed the ISQG-L values in some of the surface bulk samples in the upper estuary proximal to long established sources of catchment pollution.

  11. Spatial and temporal variation in seagrass coverage in Southwest Florida: assessing the relative effects of anthropogenic nutrient load reductions and rainfall in four contiguous estuaries.

    Science.gov (United States)

    Tomasko, D A; Corbett, C A; Greening, H S; Raulerson, G E

    2005-08-01

    The estuaries of Tampa Bay, Sarasota Bay, Lemon Bay, and Upper Charlotte Harbor are contiguous waterbodies located within the subtropical environment of Southwest Florida. Based on an examination of rainfall data over the period of record (1916-2001) within the watersheds of these estuaries, there is no evidence for spatial differences (at the watershed level) or monotonic trends in annual rainfall. During the 1980s, nitrogen loads into Tampa Bay and Sarasota Bay (generated primarily by domestic wastewater treatment facilities) were reduced by 57% and 46%, respectively. In response, both Tampa Bay and Sarasota Bay have lower phytoplankton concentrations, greater water clarity and more extensive seagrass coverage in 2002 than in the early 1980s. As there is no evidence of a concurrent trend in rainfall during the period of 1982-2001, it is unlikely that variation in rainfall can account for the observed increase in seagrass coverage in these two bays. In contrast, seagrass coverage has remained relatively constant since the mid 1980s in Lemon Bay and Charlotte Harbor. Domestic wastewater treatment facilities are minor sources of nitrogen to Lemon Bay, and water clarity in Charlotte Harbor varies mostly as a function of dissolved organic matter and non-chlorophyll associated turbidity, not phytoplankton levels. Even in estuaries that share boundaries and are within 100 km of each other, varied responses to anthropogenic changes and natural phenomena were observed in water quality and associated seagrass extent. Resource management strategies must take into account system-specific factors-not all strategies will result in similar results in different systems.

  12. Spatiotemporal Distribution, Sources, and Photobleaching Imprint of Dissolved Organic Matter in the Yangtze Estuary and Its Adjacent Sea Using Fluorescence and Parallel Factor Analysis

    Science.gov (United States)

    Li, Penghui; Chen, Ling; Zhang, Wen; Huang, Qinghui

    2015-01-01

    To investigate the seasonal and interannual dynamics of dissolved organic matter (DOM) in the Yangtze Estuary, surface and bottom water samples in the Yangtze Estuary and its adjacent sea were collected and characterized using fluorescence excitation-emission matrices (EEMs) and parallel factor analysis (PARAFAC) in both dry and wet seasons in 2012 and 2013. Two protein-like components and three humic-like components were identified. Three humic-like components decreased linearly with increasing salinity (r>0.90, p<0.001), suggesting their distribution could primarily be controlled by physical mixing. By contrast, two protein-like components fell below the theoretical mixing line, largely due to microbial degradation and removal during mixing. Higher concentrations of humic-like components found in 2012 could be attributed to higher freshwater discharge relative to 2013. There was a lack of systematic patterns for three humic-like components between seasons and years, probably due to variations of other factors such as sources and characteristics. Highest concentrations of fluorescent components, observed in estuarine turbidity maximum (ETM) region, could be attributed to sediment resuspension and subsequent release of DOM, supported by higher concentrations of fluorescent components in bottom water than in surface water at two stations where sediments probably resuspended. Meanwhile, photobleaching could be reflected from the changes in the ratios between fluorescence intensity (Fmax) of humic-like components and chromophoric DOM (CDOM) absorption coefficient (a355) along the salinity gradient. This study demonstrates the abundance and composition of DOM in estuaries are controlled not only by hydrological conditions, but also by its sources, characteristics and related estuarine biogeochemical processes. PMID:26107640

  13. Spatiotemporal Distribution, Sources, and Photobleaching Imprint of Dissolved Organic Matter in the Yangtze Estuary and Its Adjacent Sea Using Fluorescence and Parallel Factor Analysis.

    Directory of Open Access Journals (Sweden)

    Penghui Li

    Full Text Available To investigate the seasonal and interannual dynamics of dissolved organic matter (DOM in the Yangtze Estuary, surface and bottom water samples in the Yangtze Estuary and its adjacent sea were collected and characterized using fluorescence excitation-emission matrices (EEMs and parallel factor analysis (PARAFAC in both dry and wet seasons in 2012 and 2013. Two protein-like components and three humic-like components were identified. Three humic-like components decreased linearly with increasing salinity (r>0.90, p<0.001, suggesting their distribution could primarily be controlled by physical mixing. By contrast, two protein-like components fell below the theoretical mixing line, largely due to microbial degradation and removal during mixing. Higher concentrations of humic-like components found in 2012 could be attributed to higher freshwater discharge relative to 2013. There was a lack of systematic patterns for three humic-like components between seasons and years, probably due to variations of other factors such as sources and characteristics. Highest concentrations of fluorescent components, observed in estuarine turbidity maximum (ETM region, could be attributed to sediment resuspension and subsequent release of DOM, supported by higher concentrations of fluorescent components in bottom water than in surface water at two stations where sediments probably resuspended. Meanwhile, photobleaching could be reflected from the changes in the ratios between fluorescence intensity (Fmax of humic-like components and chromophoric DOM (CDOM absorption coefficient (a355 along the salinity gradient. This study demonstrates the abundance and composition of DOM in estuaries are controlled not only by hydrological conditions, but also by its sources, characteristics and related estuarine biogeochemical processes.

  14. Impact of the tidal power dam in the Rance estuary: geomorphological changes, hydrosedimentary processes and reconstructions plans

    Science.gov (United States)

    Susperregui, A.

    2010-12-01

    The Rance basin (France) offers potential to make a full-scale assessment of the environmental impact of a tidal power station after 50 years of operation. Consequences on biology, hydrodynamics and sedimentology were observed and nowadays, some of these changes are still acting on the natural system. The tidal dynamic was completely artificialised by the dam construction. The two main consequences are the reduction of exundation area and the extension of slack duration. Sedimentary dynamic depending on hydrodynamics conditions, changes in sediment distribution were also observed. Before the tidal power station construction, sands lined the gravel bed channel, recovered the bottom and formed beaches and banks. Coves and the upstream part of the estuary were dominated by a fine sedimentation, forming mudflats in a classical configuration slikke/schorre. Nowadays, mudflats extended to the center of the basin and all coves are occupied. The important inertia induced by the slack extension caused a slowing down on currents velocities, making easier the fine suspension deposit. The siltation is most important upstream, were the turbidity maximum was shifted, generating problems for navigation and banks access. A solution of sediment management was envisaged from 2001, by the digging of a sediments trap of 91 000 m3, near the Châtelier Lock. Sedimentation monitoring in this trap shows an intense filling over the first two years of functioning, then a slowing down leading to a complete filling from 2005. This trap also showed a beneficial interest on the sedimentation rates of the mudflats closed to it, which decreased. To understand how fine sediment is eroded and transported into this maritime area, an optical backscatter sensor was installed 1.5 km upstream of the tidal power station. During spring tides, the tidal power station functions in a “double-acting” cycle. This particular working leads to an important increase of turbidity during the artificial tidal

  15. Performance test of filtering system for controlling the turbidity of secondary cooling water in HANARO

    International Nuclear Information System (INIS)

    Park, Y. C.; Woo, J. S.; Jo, Y. K.; Loo, J. S.; Lim, N. Y.

    2001-01-01

    There is about 80 m 3 /h loss of the secondary cooling water by evaporation, windage and blowdown during the operation of HANARO, 30 MW research reactor. When the secondary cooling water is treated by high Ca-hardness treatment program for minimizing the blowdown loss, only the trubidity exceeds the limit. By adding filtering system it was confirned, through the relation of turbidity and filtering rate of secondary cooling water, that the turbidity is reduced below the limit (5 deg.) by 2 % of filtering rate without blowdown. And it was verified, through the field performace test of filtering system under normal operation condition, that the circulation pumps get proper capacity and that filter units reduce the turbidity below the limit. Therefore, the secondary cooling water can be treated by the high Ca-hardness program and filter system without blowdown

  16. Atmospheric turbidity parameters affecting the incident solar solar radiation for two different areas in (Eg))

    International Nuclear Information System (INIS)

    Tadros, M.T.Y.; Mosalam, M.A.; El-metwally, M.

    1999-01-01

    Atmospheric turbidity parameters such as Linke turbidity (L-0) and true Angstrom parameters (Bita o , Alpha 0 ) have been determined from the measurements of direct solar radiation for entire spectrum and for specified spectral bands during one year starting from june 1992 to may 1993. Comparison between the industrial area in Helwan (south Cairo) with that of the agricultural area in Mansoura, in (Eg), was done. Analysis of data revealed that the atmospheric turbidity parameters (L Beta) in Helwan is higher than that in Mansoura, except for hot wet months. The increase of L in Mansoura, in summer, is due to the increase of water vapor content. The wavelength exponent Alpha shows that the size the size of particles in Helwan is larger than that in Mansoura

  17. Speckle suppression via sparse representation for wide-field imaging through turbid media.

    Science.gov (United States)

    Jang, Hwanchol; Yoon, Changhyeong; Chung, Euiheon; Choi, Wonshik; Lee, Heung-No

    2014-06-30

    Speckle suppression is one of the most important tasks in the image transmission through turbid media. Insufficient speckle suppression requires an additional procedure such as temporal ensemble averaging over multiple exposures. In this paper, we consider the image recovery process based on the so-called transmission matrix (TM) of turbid media for the image transmission through the media. We show that the speckle left unremoved in the TM-based image recovery can be suppressed effectively via sparse representation (SR). SR is a relatively new signal reconstruction framework which works well even for ill-conditioned problems. This is the first study to show the benefit of using the SR as compared to the phase conjugation (PC) a de facto standard method to date for TM-based imaging through turbid media including a live cell through tissue slice.

  18. Negative consequences of glacial turbidity for the survival of freshwater planktonic heterotrophic flagellates.

    Science.gov (United States)

    Sommaruga, Ruben; Kandolf, Georg

    2014-02-17

    Heterotrophic (phagotrophic) flagellates are key components of planktonic food webs in freshwater and marine ecosystems because they are the main consumers of bacteria. Although they are ubiquitous in aquatic ecosystems, they were numerically undetectable in turbid glacier-fed lakes. Here we show that glacial particles had negative effects on the survival and growth of heterotrophic flagellates. The effect of glacial particles was concentration-dependent and was caused by their interference with bacterial uptake rather than by physical damage. These results are the first to reveal why establishment of heterotrophic flagellates populations is hindered in very turbid glacial lakes. Because glaciers are vanishing around the world, recently formed turbid meltwater lakes represent an excellent opportunity to understand the environmental conditions that probably shaped the establishment of lake communities at the end of the last glaciation.

  19. Pyrheliometric determination of atmospheric turbidity in harmattan over Ile-Ife, Nigeria

    International Nuclear Information System (INIS)

    Adeyefa, Z.D.; Adedokun, J.A.

    1990-02-01

    Measurements of direct solar radiation intensity, using an Angstrom compensation pyrheliometer carried out over three harmattan seasons (1985-1987) at Ile-Ife (7.29N, 4.34E) Nigeria, have been used to determine atmospheric turbidity based on five different models of turbidity, viz: Schuepp (B), Angstrom (β), Kastrov (C), Unsworth (τ a ) and Linke (T). The five parameters indicate high aerosol loading of the atmosphere during the period and high correlation is established between them: (0.919 ≤ τ ≤ 0.999). An inverse relationship has been noticed between horizontal visibility and atmospheric turbidity: (-0.80 ≤ τ ≤ -0.76). (author). 35 refs, 15 figs, 4 tabs

  20. Removal of COD and turbidity to improve wastewater quality using electrocoagulation technique

    International Nuclear Information System (INIS)

    Mohd Faiqun Niam; Fadil Othman; Johan Sohaili; Zulfa Fauzia

    2007-01-01

    Electrocoagulation (EC) is becoming a popular process to be used for wastewater treatment. The removal of COD and turbidity from wastewater by EC using iron (Fe) electrode material was investigated in this paper. Several working parameters, such as pH, current density, and operating time were studied in an attempt to achieve a higher removal capacity. Wastewater sample was made from milk powder with initial COD of 1140 mgL -1 and turbidity of 491 NTU. Current density was varied from 3.51 to 5.62 mA cm -2 , and operating time of between 30 and 50 minutes. The results show that the effluent wastewater was very clear and its quality exceeded the direct discharge standard. The removal efficiencies of COD and turbidity were high, being more than 65 % and 95 %. In addition, the experimental results also show that the electrocoagulation can neutralize pH of wastewater. (author)