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Sample records for freshwater sediment succession

  1. A marine to freshwater sediment succession from Kowhai Beach wetland, Northland : implications for Holocene sea level

    International Nuclear Information System (INIS)

    Hicks, H.; Nichol, S.L.

    2007-01-01

    An infilled wetland located behind coastal dunes in north-east Northland is used to reconstruct a local history of environmental change spanning early Holocene (c. 7000 yr BP) to modern time. Proxy indicators (sediment texture, diatoms and pollen) provide evidence for a transition from marginal marine- to brackish- to freshwater-conditions in the wetland. Radiocarbon ages constrain the chronology of this succession to 7880-7430 cal. yr BP for the early period of marine conditions, 3570-3210 cal. yr BP for the latter brackish phase and 1060-800 cal. yr BP for the change to freshwater conditions. Within this succession, the diatom record preserves a strong brackish signal at core depths above the limit of the modern tidal range. This is presented as preliminary evidence for a mid-Holocene sea level highstand for northern New Zealand of approximately 1.2 m above present mean sea level. (author). 40 refs., 7 figs., 1 tab

  2. Cable Bacteria in Freshwater Sediments

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus

    2015-01-01

    In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable...... bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the freshwater stream Giber Å, Denmark, was incubated in the laboratory. After 2 weeks, pH signatures...... marine cable bacteria, with the genus Desulfobulbus as the closest cultured lineage. The results of the present study indicate that electric currents mediated by cable bacteria could be important for the biogeochemistry in many more environments than anticipated thus far and suggest a common evolutionary...

  3. Escherichia coli and fecal coliforms in freshwater and estuarine sediments

    Science.gov (United States)

    It has been known for some time that substantial populations of fecal coliforms and E. coli are harbored in freshwater bottom sediments, bank soils, and beach sands. However, the relative importance of sediments as bacterial habitats and as a source of water-borne fecal coliforms and E. coli has not...

  4. Sediment quality in freshwater impoundments at Savannah National Wildlife Refuge

    Science.gov (United States)

    Winger, P.V.; Lasier, P.J.

    2004-01-01

    Freshwater impoundments at Savannah National Wildlife Refuge (NWR), South Carolina, provide an important habitat for wildlife species, but degraded sediment quality in the Savannah River downstream of the discharge from two impoundments have caused concern about potential contaminant problems within the impoundments. The quality of sediments from five impoundments (impoundments no. 1, 2, 6, 7, and 17) on the NWR was evaluated using physical and chemical characterization, contaminant concentrations (metals, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons), and toxicity testing. Survival of Hyalella azteca (freshwater amphipod) exposed for 28 days to solid-phase sediments was not significantly different from controls, but growth was significantly decreased at several sites. Survival in 96-hour exposures to sediment pore water was significantly decreased at most sites. Factors contributing to the toxic responses were low pH (3.7 to 4.1), ammonia (20 mg/L), and increased concentrations of cations in the pore water. The excess of simultaneously extracted metals over the acid volatile sulfides in the sediments was also typical of sites displaying decreased sediment quality. Elemental concentrations in pore water were negatively correlated with pH, and the highest concentrations were observed in impoundment no. 7. The acidic nature of the sediment in this impoundment was exacerbated by recent draining, burning, and disking, which allowed oxidation of the previously anoxic wetland sediment. Sediment disturbance and mixing of vegetation into the sediments by disking may also have contributed to the formation of ammonia caused by microbial decomposition of the fragmented organic matter. Contaminants were not detected in sediments from the impoundments, but releases of acidic water with increased levels of sediment cations from the impoundments may have contributed to the degraded sediment conditions previously observed in the river

  5. Mercury transfer from bed sediments to freshwater fish (guppies)

    Energy Technology Data Exchange (ETDEWEB)

    Kudo, A.

    1976-01-01

    Mercury transfer from river sediments (treated with labelled mercuric chloride) to freshwater fish (Lebistes reticulata) (wet weight, 29 to 869 mg) was observed for 150 days. Release rate from the sediment indicates a half-life of 12 to 20 years. The amount taken up by the fish varied widely (up to 600 percent differences), but half-lives for clearance were all between 38 and 75 days. No correlation was found between mercury uptake rate and either size or sex of fish.

  6. Tributyltin-resistant bacteria from estuarine and freshwater sediments.

    OpenAIRE

    Wuertz, S; Miller, C E; Pfister, R M; Cooney, J J

    1991-01-01

    Resistance to tributyltin (TBT) was examined in populations from TBT-polluted sediments and nonpolluted sediments from an estuary and from fresh water as well as in pure cultures isolated from those sediments. The 50% effective concentrations (EC50s) for populations were higher at a TBT-polluted freshwater site than at a site without TBT, suggesting that TBT selected for a TBT-resistant population. In contrast, EC50s were significantly lower for populations from a TBT-contaminated estuarine s...

  7. Remobilisation of uranium from contaminated freshwater sediments by bioturbation

    Energy Technology Data Exchange (ETDEWEB)

    Lagauzere, S.; Bonzom, J.M. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Saint-Paul-Lez-Durance (France). Lab. d' Ecotoxicologie des Radionucleides; Motelica-Heino, M. [Orleans Univ. (France). ISTO; Viollier, E. [Paris Diderot Univ., Paris (France). Inst. de Physique du Globe de Paris; Stora, G. [Aix-Marseille Univ., Marseille (France). Mediterranean Inst. of Oceanography (MIO)

    2014-07-01

    Benthic macro-invertebrate bioturbation can influence the remobilisation of uranium (U) initially associated with freshwater sediments, resulting in a high release of this pollutant through the overlying water column. Given the potential negative effects on aquatic biocenosis and the global ecological risk, it appears crucial to improve our current knowledge concerning the biogeochemical behaviour of U in sediments. The present study aimed to assess the biogeochemical modifications induced by Tubifex tubifex (Annelida, Clitellata, Tubificidae) bioturbation within the sediment in order to explain such a release of U. To reach this goal, U distribution between solid and solute phases of a reconstructed benthic system (i.e. in mesocosms) inhabited or not by T. tubifex worms was assessed in a 12-day laboratory experiment. Thanks notably to fine-resolution (mm-scale) measurements (e.g. ''diffusive equilibrium in thin-films'' DET gel probes for porewater, bioaccumulation in worms) of U and main chemical species (iron, sulfate, nitrate and nitrite), this work (i) confirmed that the removal of bottom sediment particles to the surface through the digestive tract of worms greatly favoured oxidative loss of U in the water column, and (ii) demonstrated that both U contamination and bioturbation of T. tubifex substantially influenced major microbial-driven biogeochemical reactions in sediments (e.g. stimulation of denitrification, sulfate reduction and iron dissolutive reduction). This study provides the first demonstration of biogeochemical modifications induced by bioturbation in freshwater U-contaminated sediments.

  8. A study of arsenic and chromium contamination in freshwater sediments

    International Nuclear Information System (INIS)

    Nazaratul Ashifa Abdullah Salim; Abdul Khalik Wood; Alias Mohd Yusof; Mohd Suhaimi Hamzah; Md Suhaimi Elias; Shamsiah Abdul Rahman

    2008-08-01

    Arsenic (As) is generally known for its toxicity while chromium (Cr) at the appropriate amount is an essential element to man and becomes quite toxic in excessive amount. Anthropogenic activities such as industrialization, agricultural and urbanization have led to the contamination of toxic elements into aquatic that finally end up in the sediment system. Environmental process like diagenetic process causes the toxic metals to migrate from the bedrock materials into the sediment surface and lastly into the water column. This process has been recognized to be the factor of arsenic contamination in well water in several countries such as Bangladesh, Taiwan, USA and Canada. A number of samples of freshwater sediments from identified rivers and lakes at Johor Bharu area had been analyzed to determine the concentration level of As and Cr using neutron activation analysis (NAA) technique. Certified Reference Material (CRM) namely BCSS-1 and IAEA Soil-7 were applied to provide good quality assurance control. The results obtained show that the concentrations of As in the rivers and lakes are 10-33 mg/g and 18-62 mg/g, respectively. The concentrations of Cr in the rivers range between 25 mg/g to125 mg/g, while in the lake sediments the concentrations range between 173 mg/g to 301 mg/g. The lakes sediments have higher As and Cr contents than the river sediment. The results of the As and Cr concentrations were then compared to the background value proposed by National Oceanic and Atmospheric Administration (NOAA), USA and interim freshwater sediment quality guidelines value established by Canadian Sediment Quality Guidelines for The Protection of Aquatic Life. (Author)

  9. Biogenic silica in tidal freshwater marsh sediments and vegetation (Schelde estuary, Belgium)

    NARCIS (Netherlands)

    Struyf, E.; van Damme, S.; Gribsholt, B.; Middelburg, J.J.; Meire, P.

    2005-01-01

    To date, estuarine ecosystem research has mostly neglected silica cycling in freshwater intertidal marshes. However, tidal marshes can store large amounts of biogenic silica (BSi) in vegetation and sediment. BSi content of the typical freshwater marsh plants Phragmites australis, Impatiens

  10. Microbiological reduction of Sb(V) in anoxic freshwater sediments

    Science.gov (United States)

    Oremland, Ronald S.; Kulp, Thomas R.; Miller, Laurence G.; Braiotta, Franco; Webb, Samuel M.; Kocar, Benjamin D; Blum, Jodi S.

    2014-01-01

    Microbiological reduction of millimolar concentrations of Sb(V) to Sb(III) was observed in anoxic sediments from two freshwater settings: (1) a Sb- and As-contaminated mine site (Stibnite Mine) in central Idaho and 2) an uncontaminated suburban lake (Searsville Lake) in the San Francisco Bay Area. Rates of Sb(V) reduction in anoxic sediment microcosms and enrichment cultures were enhanced by amendment with lactate or acetate as electron donors but not by H2, and no reduction occurred in sterilized controls. Addition of 2-14C-acetate to Stibnite Mine microcosms resulted in the production of 14CO2 coupled to Sb(V) reduction, suggesting that this process proceeds by a dissimilatory respiratory pathway in those sediments. Antimony(V) reduction in Searsville Lake sediments was not coupled to acetate mineralization and may be associated with Sb-resistance. The microcosms and enrichment cultures also reduced sulfate, and the precipitation of insoluble Sb(III)-sulfide complexes was a major sink for reduced Sb. The reduction of Sb(V) by Stibnite Mine sediments was inhibited by As(V), suggesting that As(V) is a preferred electron acceptor for the indigenous community. These findings indicate a novel pathway for anaerobic microbiological respiration and suggest that communities capable of reducing high concentrations of Sb(V) commonly occur naturally in the environment.

  11. Ultrasound-assisted extraction method for the simultaneous determination of emerging contaminants in freshwater sediments.

    Science.gov (United States)

    de Sousa, Diana Nara Ribeiro; Grosseli, Guilherme Martins; Mozeto, Antonio Aparecido; Carneiro, Renato Lajarim; Fadini, Pedro Sergio

    2015-10-01

    Sediments are the fate of several emerging organic contaminants, such as pharmaceuticals, personal care products and hormones, and therefore an important subject in environmental monitoring studies. In the present work, a simple and sensitive method was developed, validated and applied for the simultaneous extraction of atenolol, caffeine, carbamazepine, diclofenac, ibuprofen, naproxen, propranolol, triclosan, estrone, 17-β-estradiol and 17-α-ethinylestradiol using ultrasound-assisted extraction from freshwater sediment samples followed by solid-phase extraction clean-up and liquid chromatography with tandem mass spectrometry detection. The solvent type and extraction pH were evaluated to obtain the highest recoveries of the compounds. The best method shows absolute recoveries between 54.0 and 94.4% at 50 ng/g concentration. The method exhibits good precision with relative standard deviation ranging from 1.0-16%. The detection and quantification limits ranged from 0.006-0.067 and 0.016-0.336 ng/g, respectively. The developed method was successfully applied to freshwater sediment samples collected from different sites in Jundiaí River basin of São Paulo State, Brazil. The compounds atenolol, caffeine, propranolol and triclosan were detected in all the sampling sites with concentrations of 13.8, 41.0, 28.5 and 176 ng/g, respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures

    Science.gov (United States)

    Besser, J.M.; Ingersoll, C.G.; Leonard, E.N.; Mount, D.R.

    1998-01-01

    Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. We investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by ???70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

  13. Taxonomy and palaeoecology of dinoflagellate cysts from Upper Oligocene freshwater sediments of Lake Enspel, Westerwald area, Germany.

    Science.gov (United States)

    Köhler; Clausing

    2000-10-01

    Freshwater dinoflagellates play an important role as primary producers in the lacustrine environment. A new species of dinoflagellates, Cleistosphaeridium lacustre, is described from Upper Oligocene sediments of palaeo-lake Enspel. They are associated with other phytoplankton, such as diatoms, chrysophytes, green algae and benthic cyanobacteria. Mass occurrences of this species are interpreted as algal blooms and may partly reflect seasonal successions. This phenomenon was controlled by volcanic activities in the depositional area, which led to an increase in nutrient supply.

  14. Assessment of contaminated sediments with an indoor freshwater/sediment microcosm assay.

    Science.gov (United States)

    Triffault-Bouchet, Gaëlle; Clément, Bernard; Blake, Gérard

    2005-09-01

    This study was conducted to assess the feasibility of using a 2-L, indoor microcosm assay to evaluate five contaminated sediments (A, B, C, D, and E). Toxic potential was deduced in the light of general contamination of sediments, pollutant partitioning in microcosms, and biological responses of species (Pseudokirchneriella subcapitata, Lemna minor, Daphnia magna, Hyalella azteca, Chironomus riparius): E > A > B > C > D. Sediments mainly were contaminated by metals (lead and zinc). Organic pollutant contents varied among the sediments. The major polycyclic aromatic hydrocarbon (PAH) compounds were pyrene, fluoranthene, and phenanthrene. Sediments A, B, and C highly stimulated duckweed growth (> 700%) and impaired daphnid (effect on pelagic and benthic organisms. Finally, sediment E, the most toxic, limited duckweed growth (inhibition of 82%) and impaired daphnid survival (0% of survival). Amphipods were impaired dramatically by this sediment (0% of survival), in contrast with chironomids, for which no toxic effect was measured. The 2-L, indoor microcosm assay successfully was applied to the assessment of those five contaminated sediments. Sediments A, B, C, and E should not be deposited in gravel quarries, and new, more sensitive endpoint measurements should be developed.

  15. Defining the ecogeomorphic succession of land building for freshwater, intertidal wetlands in Wax Lake Delta, Louisiana

    Science.gov (United States)

    Olliver, Elizabeth A.; Edmonds, Douglas A.

    2017-09-01

    Land building in deltaic environments occurs when sediment discharged from a river mouth is deposited subaqueously and transitions to subaerial land. The transition from subaqueous deposition to subaerial land is a critical process that marks the creation of relatively stable land, yet it is unclear what controls the speed and style of this transition. We define how this transition, herein termed the land building succession, varies in time and space for the freshwater, intertidal wetlands in Wax Lake Delta, LA. Using remote sensing and field data we classify land cover into sediment, water, or vegetation classes at maximum and minimum biomass. We see two succession patterns within Wax Lake Delta. Deltaic islands near the apex are initially covered by sediment and open water. Through time, open water and sediment coverage decreases as vegetation coverage increases. On the other hand, distal islands show little sediment exposure through time. In both cases, all deltaic islands become covered with vegetation by 2015. As vegetation colonizes the island, the topography organizes into two platforms vertically separated by ∼0.35 m. The lower, intertidal platform occurs in the island interiors and is commonly inundated by water and dominated by subaqueous or floating vegetation. The upper, subaerial platform occurs along island edges and is dominated by a variety of vegetation species including Salix nigra, Colocasia esculenta, and Polygonum punctatum. It takes an average of ∼10 years for the intertidal platform to transition to the subaerial platform. These two platforms are separated by the tidal range measured in Atchafalaya Bay, and the different vegetation communities occupying each platform suggest they are a manifestation of multiple stable states and arise due to vegetation and sedimentation feedbacks.

  16. IMPACTS OF IRON, NUTRIENTS, AND MINERAL FINES ON ANAEROBIC BIODEGRADATION OF CANOLA OIL IN FRESHWATER SEDIMENTS

    Science.gov (United States)

    Factors affecting anaerobic biodegradation kinetics of canola oil in freshwater sediments were investigated. An optimum dose of ferric hydroxide (10.5 g Fe(III)·kg-1 sediment) was found to stimulate anaerobic biodegradation of canola oil (18.6 g oil kg-1). ...

  17. Effects of discharge, wind, and tide on sedimentation in a recently restored tidal freshwater wetland

    NARCIS (Netherlands)

    Verschelling, Eelco; van der Deijl, Eveline; van der Perk, Marcel; Sloff, C.J.; Middelkoop, Hans

    2017-01-01

    Sediment deposition is one of the key mechanisms to counteract the impact of sea level rise in tidal freshwater wetlands (TFWs). However, information about sediment deposition rates in TFWs is limited, especially for those located in the transition zone between the fluvially dominated and tidally

  18. Effect of salinity on temporal and spatial dynamics of ammonia-oxidising bacteria from intertidal freshwater sediment

    NARCIS (Netherlands)

    Coci, M.; Riechmann, D.; Bodelier, P.L.E.; Stefani, S.; Zwart, G.; Laanbroek, H.J.

    2005-01-01

    Temporal and spatial dynamics within an ammonia-oxidising community from intertidal, freshwater sediments were studied in microcosms simulating flooding twice a day with fresh, brackish and marine waters. The microcosms had been filled with the upper 5 cm of intertidal freshwater sediment from the

  19. Macrofaunal Impact on the Denitrifying Bacterial Community in Freshwater Sediment

    DEFF Research Database (Denmark)

    Poulsen, Morten; Stief, Peter; Schramm, Andreas

    phylotype richness of narG increased from 68 in sediment without larvae to 170 in sediment with larvae. Part of this increase in narG diversity could be explained by metabolic activation of certain nitrate-reducing bacteria in the gut of C. plumosus, since 18.3 % of the additional phylotypes were found...

  20. Anaerobic oxidation of methane in an iron-rich Danish freshwater lake sediment

    DEFF Research Database (Denmark)

    Nordi, Katrin á; Thamdrup, Bo; Schubert, Carsten J.

    2013-01-01

    Freshwater systems are identified as one of the main natural methane sources, but little is known about the importance of anaerobic oxidation of methane (AOM) in these systems. We investigated AOM in a lake sediment characterized by a high reactive iron content, normal sulfate concentrations in t...

  1. The impact of storms and stratification on sediment transport in the Rhine region of freshwater influence

    NARCIS (Netherlands)

    Flores, Raúl P.; Rijnsburger, S.; Horner-Devine, Alexander R.; Souza, Alejandro J.; Pietrzak, J.D.

    2017-01-01

    We present measurements of along and across-shore sediment transport in a region of the Dutch coast 10 km north of the Rhine River mouth. This section of the coast is characterized by strong vertical density stratification because it is within the midfield region of the Rhine region of freshwater

  2. Isolation and characterization of acetate-utilizing anaerobes from a freshwater sediment

    NARCIS (Netherlands)

    Scholten, J.C.M.; Stams, A.J.M.

    2000-01-01

    Acetate-degrading anaerobic microorganisms in freshwater sediment were quantified by the most probable number technique. From the highest dilutions a methanogenic, a sulfate-reducing, and a nitrate-reducing microorganism were isolated with acetate as substrate. The methanogen (culture AMPB-Zg) was

  3. Identifying the controlling factors of sedimentation in a recently restored tidal freshwater wetland

    Science.gov (United States)

    van der Perk, Marcel; Verschelling, Eelco; van der Deijl, Eveline; Sloff, Kees; Middelkoop, Hans

    2017-04-01

    Sediment deposition is one of the key mechanisms to counteract the impact of sea level rise in tidal freshwater wetlands (TFWs). In a study to identify the factors controlling sedimentation in a recently restored tidal freshwater wetland in the Biesbosch National Park in the Rhine-Meuse delta - The Netherlands, we adopted both a modelling and a field measurement approach. This approximately 700 ha large tidal freshwater wetland is characterised by two openings with the main inlet connected to the Nieuwe Merwede river, a distributary of the River Rhine, two artificial channels connecting the in- and outlet of the area, and tidal flats. We quantified the sediment budgets of the TFW using 10-minute interval measurement of water level, discharge and suspended sediment concentration at the in- and outlet of the area for several events including a river discharge event and several windstorm events, and for different tidal ranges. In addition, we conducted 14 numerical experiments using a combined hydrodynamic and sediment transport model to simulate sedimentation rates and patterns for different river discharges, windstorm magnitudes, and tidal conditions. Both the results from the field measurements and the modelling results show that the overall sediment budget is positive in the area and increases with river discharge due to the associated higher water inflow and suspended sediment concentrations at the main inlet of the study area. The short-term sediment budget is generally positive during flood and negative during ebb, but the net sediment budget during a tidal cycle is not influenced by the tidal range. The sedimentation rates decrease with increasing windstorm magnitude, as wind waves cause sediment resuspension on the tidal flats and transport of the resuspended sediment towards the channels. Sediment trapping efficiencies are in the order of 45% of the incoming sediment load, but decrease with increasing river discharge and wind magnitude. The effect of wind on

  4. Review and Synthesis of Bioassessment Methodologies for Freshwater Contaminated Sediments

    Science.gov (United States)

    1990-01-01

    Sediments," Seventh Symposium on Aquatic Toxicology and Hazard Assessment: ASTM STP 854, R. D. Cardwell, R. Purdy, and R. C. Bahner, eds., American Society...Laboratory and Field Methods for Testing the Toxicity of Chemi- cals Sorbed to Sediments," Aquatic Toxicology and Environmental Fate, Vol 9, ASTM STP 921...34 Aquatic Toxicology , Vol 11, pp 303-311. Chapman, P. M. 1983. "Do Organisms in Laboratory Tests Respond Like Organ- isms in Nature?," Sixth Symposium on

  5. Nontarget analysis of polar contaminants in freshwater sediments influenced by pharmaceutical industry using ultra-high-pressure liquid chromatography-quadrupole time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Terzic, Senka, E-mail: terzic@irb.h [Division of Marine and Environmental Research, Rudjer Boskovic Institute, 10000 Zagreb (Croatia); Ahel, Marijan [Division of Marine and Environmental Research, Rudjer Boskovic Institute, 10000 Zagreb (Croatia)

    2011-02-15

    A comprehensive analytical procedure for a reliable identification of nontarget polar contaminants in aquatic sediments was developed, based on the application of ultra-high-pressure liquid chromatography (UHPLC) coupled to hybrid quadrupole time-of-flight mass spectrometry (QTOFMS). The procedure was applied for the analysis of freshwater sediment that was highly impacted by wastewater discharges from the pharmaceutical industry. A number of different contaminants were successfully identified owing to the high mass accuracy of the QTOFMS system, used in combination with high chromatographic resolution of UHPLC. The major compounds, identified in investigated sediment, included a series of polypropylene glycols (n = 3-16), alkylbenzene sulfonate and benzalkonium surfactants as well as a number of various pharmaceuticals (chlorthalidone, warfarin, terbinafine, torsemide, zolpidem and macrolide antibiotics). The particular advantage of the applied technique is its capability to detect less known pharmaceutical intermediates and/or transformation products, which have not been previously reported in freshwater sediments. - Research highlights: UHPLC-QTOFMS coupling was applied for nontarget analysis of polar contaminants. Wide spectrum of polar contaminants was identified in polluted sediments. Pharmaceuticals and their intermediates were present in high concentrations. - Comprehensive analysis of freshwater sediments by UPLC/QTOF indicated importance of pharmaceutically-derived polar contaminants.

  6. Sediment processes and mercury transport in a frozen freshwater fluvial lake (Lake St. Louis, QC, Canada).

    Science.gov (United States)

    Canário, João; Poissant, Laurier; O'Driscoll, Nelson; Vale, Carlos; Pilote, Martin; Lean, David

    2009-04-01

    An open-bottom and a closed-bottom mesocosm were developed to investigate the release of mercury from sediments to the water column in a frozen freshwater lake. The mesoscosms were deployed in a hole in the ice and particulate mercury (Hg(P)) and total dissolved mercury (TDHg) were measured in sediments and in water column vertical profiles. In addition, dissolved gaseous mercury (DGM) in water and mercury water/airflux were quantified. Concentrations of TDHg, DGM, and mercury flux were all higher in the open-bottom mesocosm than in the closed-bottom mesocosm. In this paper we focus on the molecular diffusion of mercury from the sediment in comparison with the TDHg accumulation in the water column. We conclude that the molecular diffusion and sediment resuspension play a minor role in mercury release from sediments suggesting that solute release during ebullition is an important transport process for mercury in the lake.

  7. Spatial distribution of ammonia-oxidizing archaea and bacteria across eight freshwater lakes in sediments from Jiangsu of China

    Directory of Open Access Journals (Sweden)

    Xu Sun

    2014-03-01

    Full Text Available Ammonia-oxidizingarchaea (AOA and ammonia-oxidizing bacteria (AOB play an important role innitrogen transformation in freshwater sediments. However, it is still unclear towhat extent the distribution patterns of these microorganisms are affected bythe freshwater sediment across a large geographical scale. This study wasdesigned to gain insight into the heterogeneity distribution of AOA and AOB in32 freshwater sediments from a wide range of ecologic types. Real-time quantitative polymerasechain reaction PCR(qPCR combined with the terminal restrictionfragment length polymorphism(T-RFLP were employed to characterize the abundance, diversity, and communitystructure of the AOA and AOB in 32 freshwater sediments. AOA and AOB wereubiquitous in all sediments, and archaeal amoA far outnumbered bacterial amoA inmost sediments with lower organic matters. The abundance of AOA and AOB did notvary with the freshwater ecological type (macrophyte dominated region and algaedominated region. Based on  the T-RFLP of an amoA gene, this research found that organicmatters in pore water rather than other factors affect the AOA communitystructure in sediments, while the AOB were not significantly different in thefreshwater sediments. Phylogenetic analysis showed that all archaeal amoAsequences fell within either the Crenarchaeotal Group (CG I.1b or the CGI.1asubgroup, and all AOB clustered with genus Nitrosomonas or Nitrosospira. The data obtained inthis study elucidates the role of ammonia-oxidizing archaea andammonia-oxidizing bacteria in the nitrogen cycle of freshwater ecosystems.

  8. Muddied waters: suspended sediment impacts on gill structure and aerobic scope in an endangered native and an invasive freshwater crayfish

    DEFF Research Database (Denmark)

    Rosewarne, P.J.; Svendsen, Jon Christian; Mortimer, R.J.G.

    2014-01-01

    Suspended sediment (SS) loadings in freshwater habitats have increased over the past century and SS is now a significant environmental stressor. Greater tolerance to environmental stressors has been proposed as a factor in the success of aquatic invasive species. Further, parasites may interact...... with environmental stressors to increase host susceptibility to loss of fitness and mortality. We compared the effects of SS exposure on the gill structure and aerobic scope of the endangered white-clawed crayfish (Austropotamobius pallipes), and the invasive signal crayfish (Pacifastacus leniusculus), and assessed...... impacts in relation to parasite burden. SS caused gill fouling and reduction in aerobic scope in both species, though A. pallipes was more susceptible than invasive P. leniusculus. The parasite Branchiobdella astaci, a crayfish worm that infests the gills, interacted with the sediment to affect gill...

  9. Long-term 15N-nitrogen retention in tidal freshwater marsh sediment: Elucidating the microbial contribution

    NARCIS (Netherlands)

    Gribsholt, B.; Veuger, B.; Tramper, A.; Middelburg, J.J.; Boschker, H.T.S.

    2009-01-01

    The long-term retention of nitrogen in sediment of a tidal freshwater marsh in the Scheldt estuary (Belgium) was investigated by an in situ 15N-labeling experiment. Sediment of an unvegetated creek bank and sediment vegetated by common reed (Phragmites australis) were labeled with 15NN-enriched NH4+

  10. Mangrove succession enriches the sediment microbial community in South China.

    Science.gov (United States)

    Chen, Quan; Zhao, Qian; Li, Jing; Jian, Shuguang; Ren, Hai

    2016-06-06

    Sediment microorganisms help create and maintain mangrove ecosystems. Although the changes in vegetation during mangrove forest succession have been well studied, the changes in the sediment microbial community during mangrove succession are poorly understood. To investigate the changes in the sediment microbial community during succession of mangroves at Zhanjiang, South China, we used phospholipid fatty acid (PLFA) analysis and the following chronosequence from primary to climax community: unvegetated shoal; Avicennia marina community; Aegiceras corniculatum community; and Bruguiera gymnorrhiza + Rhizophora stylosa community. The PLFA concentrations of all sediment microbial groups (total microorganisms, fungi, gram-positive bacteria, gram-negative bacteria, and actinomycetes) increased significantly with each stage of mangrove succession. Microbial PLFA concentrations in the sediment were significantly lower in the wet season than in the dry season. Regression and ordination analyses indicated that the changes in the microbial community with mangrove succession were mainly associated with properties of the aboveground vegetation (mainly plant height) and the sediment (mainly sediment organic matter and total nitrogen). The changes in the sediment microbial community can probably be explained by increases in nutrients and microhabitat heterogeneity during mangrove succession.

  11. Evaluation of multixenobiotic resistance in dreissenid mussels as a screening tool for toxicity in freshwater sediments.

    Science.gov (United States)

    Ács, A; Imre, K; Kiss, Gy; Csaba, J; Győri, J; Vehovszky, Á; Farkas, A

    2015-05-01

    The multixenobiotic defense mechanism (MXR) in aquatic organisms was recognized as a first-line defense system, and its potential use as an early biomarker of exposure to environmental stress has raised attention in the last two decades. To evaluate the relevance of this biomarker in the freshwater mussel Dreissena polymorpha, we studied its responsiveness within laboratory exposures to contaminants sequestered in freshwater sediments affected by moderate anthropogenic impact. The effectiveness of this biomarker was assessed by comparing the MXR-transporter activities determined in bivalves first with toxicity scores recorded with the D. rerio embryo developmental assay. Both bioassays were applied in the sediment contact test format. As a second evaluation approach, MXR activities determined in exposed mussels were compared with sediment-contamination data integrated into toxic units on the basis of acute toxicity to Daphnia magna. In D. polymorpha subjected to acute exposure with moderately polluted sediments, we detected limited (22-33 %) but statistically significant induction of MXR activity. Mean MXR activities significantly correlated with TU values computed for test sediments. MXR activities in mussels showed strong positive correlation with the metal load of sediments and proved to be unrelated to the contamination with polycyclic aromatic compounds. MXR activity in laboratory-exposed mussels showed low variability within treatments and thus reliably reflected even low contaminant differences between the negative reference and moderately polluted harbor sediments. The strong correlation found in this study between the MXR-transporter activity in exposed mussels and environmentally realistic sediment contamination underscores the fairly good sensitivity of this biomarker in laboratory testing conditions to signal the bioavailability of sediment bound contaminants, and it may also anticipate even the incidence of toxicity to biota.

  12. Seasonal Changes in Microbial Community Structure in Freshwater Stream Sediment in a North Carolina River Basin

    Directory of Open Access Journals (Sweden)

    John P. Bucci

    2014-01-01

    Full Text Available This study examined seasonal differences in microbial community structure in the sediment of three streams in North Carolina’s Neuse River Basin. Microbes that reside in sediment are at the base of the food chain and have a profound influence on the health of freshwater stream environments. Terminal-Restriction Fragment Length Polymorphism (T-RFLP, molecular fingerprint analysis of 16S rRNA genes was used to examine the diversity of bacterial species in stream sediment. Sediment was sampled in both wet and dry seasons from an agricultural (Bear, mixed urban (Crabtree and forested (Marks Creek, and the microbiota examined. Gamma, Alpha and Beta proteobacteria were prevalent species of microbial taxa represented among all sites. Actinobacteria was the next most prevalent species observed, with greater occurrence in dry compared to the wet season. Discernable clustering was observed of Marks and Bear Creek samples collected during the wetter period (September–April, which corresponded with a period of higher precipitation and cooler surface water temperatures. Although not statistically significant, microbial community structure appeared different between season (ANOSIM, R = 0.60; p < 0.10. Principal components analysis confirmed this pattern and showed that the bacterial groups were separated by wet and dry seasonal periods. These results suggest seasonal differences among the microbial community structure in sediment of freshwater streams and that these communities may respond to changes in precipitation during wetter periods.

  13. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides

    Science.gov (United States)

    Nowell, Lisa H.; Norman, Julia E.; Ingersoll, Christopher G.; Moran, Patrick W.

    2016-01-01

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n = 3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical

  14. Ideal vegetation height maximizes sedimentation in freshwater deltaic marshes during flood

    Science.gov (United States)

    Nardin, W.; Edmonds, D. A.

    2013-12-01

    River deltas are complex environments affected by the morphodynamic interaction between flow and sediment transport. This morphodynamic interaction is potentially affected by the freshwater marsh vegetation (e.g. sagittaria and typha) on the exposed surfaces of emergent deltaic islands. As a first step, we present modeling results and remote sensing data on how vegetation affects sedimentation within deltaic islands. Our modeling starts from a pre-formed river delta configuration and then we populate it with different vegetation with different height characteristics. We then subject the delta to floods of varying magnitudes to evaluate how vegetation affects sedimentation during a flood. In our numerical experiments vegetation height affects sedimentation in two key ways. Increase in vegetation height causes a non-linear decrease in sediment flux on to the islands (up to 80% when compared to the case without vegetation). On the other hand vegetation slows water velocity and lengthens the residence time of a water particle up to 50%. Even though vegetation reduces the sediment flux onto the islands, the increase in residence time traps more sediment resulting in higher island sedimentation rates when vegetation is present. Interestingly, we find that an intermediate vegetation height that maximizes island sedimentation rate. This occurs because sediment flux exiting the islands decreases faster (due to increase in residence time) than the sediment flux entering the islands. Finally we analyzed the spatial and seasonal evolution of the vegetation on Wax lake delta, Louisiana through the normalized difference vegetation index (NDVI). We find that NDVI varies seasonally as vegetation grows and dies, suggesting that the timing of the arrival flood wave relative to vegetation height is a critical parameter that for predicting sedimentation of deltaic islands.

  15. Freshwater discharge and sediment transport to Kangerlussuaq Fjord, West Greenland

    DEFF Research Database (Denmark)

    Mikkelsen, Andreas Peter Bech

    surface albedo that amplified surface melt. This unprecedented amount of proglacial discharge would only be possible if the runoff was generated from the lower accumulation zone, where runoff is usually buffered by the air-filled pore space in the firn. This means that the water melted in the lower...... called firn zone are studied. Geomorphological processes studied are: Mass transfer from the glacial system and into the nearby fjord and delta systems. As a part of this glacial erosion rates are deduced. Extensive discharge and sediment transport measurements provided the basis for gaining insight...... accumulation zone of the GrIS is able to runoff directly and contribute to sea-level rise....

  16. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides

    International Nuclear Information System (INIS)

    Nowell, Lisa H.; th Avenue, Portland, OR 97201 (United States))" data-affiliation=" (U.S. Geological Survey, Oregon Water Science Center, 2130 SW 5th Avenue, Portland, OR 97201 (United States))" >Norman, Julia E.; Ingersoll, Christopher G.; Moran, Patrick W.

    2016-01-01

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n = 3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical/chemical characteristics

  17. Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides

    Energy Technology Data Exchange (ETDEWEB)

    Nowell, Lisa H., E-mail: lhnowell@usgs.gov [U.S. Geological Survey, California Water Science Center, Placer Hall, 6000 J Street, Sacramento, CA 95819 (United States); Norman, Julia E., E-mail: jnorman@usgs.gov [U.S. Geological Survey, Oregon Water Science Center, 2130 SW 5" t" h Avenue, Portland, OR 97201 (United States); Ingersoll, Christopher G., E-mail: cingersoll@usgs.gov [U.S. Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO 65021 (United States); Moran, Patrick W., E-mail: pwmoran@usgs.gov [U.S. Geological Survey, Washington Water Science Center, 934 Broadway, Suite 300, Tacoma, WA 98402 (United States)

    2016-04-15

    Sediment-toxicity benchmarks are needed to interpret the biological significance of currently used pesticides detected in whole sediments. Two types of freshwater sediment benchmarks for pesticides were developed using spiked-sediment bioassay (SSB) data from the literature. These benchmarks can be used to interpret sediment-toxicity data or to assess the potential toxicity of pesticides in whole sediment. The Likely Effect Benchmark (LEB) defines a pesticide concentration in whole sediment above which there is a high probability of adverse effects on benthic invertebrates, and the Threshold Effect Benchmark (TEB) defines a concentration below which adverse effects are unlikely. For compounds without available SSBs, benchmarks were estimated using equilibrium partitioning (EqP). When a sediment sample contains a pesticide mixture, benchmark quotients can be summed for all detected pesticides to produce an indicator of potential toxicity for that mixture. Benchmarks were developed for 48 pesticide compounds using SSB data and 81 compounds using the EqP approach. In an example application, data for pesticides measured in sediment from 197 streams across the United States were evaluated using these benchmarks, and compared to measured toxicity from whole-sediment toxicity tests conducted with the amphipod Hyalella azteca (28-d exposures) and the midge Chironomus dilutus (10-d exposures). Amphipod survival, weight, and biomass were significantly and inversely related to summed benchmark quotients, whereas midge survival, weight, and biomass showed no relationship to benchmarks. Samples with LEB exceedances were rare (n = 3), but all were toxic to amphipods (i.e., significantly different from control). Significant toxicity to amphipods was observed for 72% of samples exceeding one or more TEBs, compared to 18% of samples below all TEBs. Factors affecting toxicity below TEBs may include the presence of contaminants other than pesticides, physical/chemical characteristics

  18. Toxicity of nickel-spiked freshwater sediments to benthic invertebrates-Spiking methodology, species sensitivity, and nickel bioavailability

    Science.gov (United States)

    Besser, John M.; Brumbaugh, William G.; Kemble, Nile E.; Ivey, Chris D.; Kunz, James L.; Ingersoll, Christopher G.; Rudel, David

    2011-01-01

    This report summarizes data from studies of the toxicity and bioavailability of nickel in nickel-spiked freshwater sediments. The goal of these studies was to generate toxicity and chemistry data to support development of broadly applicable sediment quality guidelines for nickel. The studies were conducted as three tasks, which are presented here as three chapters: Task 1, Development of methods for preparation and toxicity testing of nickel-spiked freshwater sediments; Task 2, Sensitivity of benthic invertebrates to toxicity of nickel-spiked freshwater sediments; and Task 3, Effect of sediment characteristics on nickel bioavailability. Appendices with additional methodological details and raw chemistry and toxicity data for the three tasks are available online at http://pubs.usgs.gov/sir/2011/5225/downloads/.

  19. Mobility of heavy metals within freshwater sediments affected by motorway stormwater

    Energy Technology Data Exchange (ETDEWEB)

    Stead-Dexter, K.; Ward, N.I

    2004-12-01

    The assessment of the mobility and bioavailability of heavy metals in sediment samples requires the use of sequential extraction procedures. Results for sediments taken from an unmanaged motorway detention pond showed heavy metals to be associated with the carbonate and residual fractions. In particular, nickel and cadmium showed a high percentage association, compared with other geochemical fractions, such as carbonates and residual fractions. Copper and zinc were shown to be associated with carbonates and iron-manganese oxides, whereas lead showed the strongest association (72%) with the Fe-Mn oxides. When compared to a groundwater-fed lake on the same site, all heavy metals contained within this sediment were found to be at much lower concentrations and strongly associated with the residual fraction (>50%) and are therefore strongly bound within the sediment. Following discharge via a wet detention pond, stormwater then flows through a series of interconnecting lake systems. Heavy metal fractionation of these interconnecting lakes is discussed and shows changes in fractionation through the lake system for copper, nickel, lead and zinc. The main concern in these lakes is the continued use of calcium carbonate to maintain freshwater pH for coarse fishing. This practice, used until 1999, may present an enhanced risk to the freshwater environment, causing greater mobility of these metals.

  20. Variability of sediment-contact tests in freshwater sediments with low-level anthropogenic contamination - Determination of toxicity thresholds

    Energy Technology Data Exchange (ETDEWEB)

    Hoess, S., E-mail: hoess@ecossa.d [Ecossa, Giselastr. 6, 82319 Starnberg (Germany); Institute of Biodiversity - Network (IBN), Dreikronengasse 2, 93047 Regensburg (Germany); Ahlf, W., E-mail: ahlf@tu-harburg.d [Institute of Environmental Technology and Energy Economics, Technical University Hamburg-Harburg, Eissendorfer Str. 40, 21071 Hamburg (Germany); Fahnenstich, C. [Institute of Environmental Technology and Energy Economics, Technical University Hamburg-Harburg, Eissendorfer Str. 40, 21071 Hamburg (Germany); Gilberg, D., E-mail: d-gilberg@ect.d [ECT Oekotoxikologie, Boettgerstr. 2-14, 65439 Floersheim (Germany); Hollert, H., E-mail: henner.hollert@bio5.rwth-aachen.d [Department of Ecosystem Analysis, Institute for Environmental Research (Biology 5), RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Melbye, K. [Dr. Fintelmann and Dr. Meyer, Mendelssohnstr. 15D, 22761 Hamburg (Germany); Meller, M., E-mail: m-meller@ecotox-consult.d [ECT Oekotoxikologie, Boettgerstr. 2-14, 65439 Floersheim (Germany); Hammers-Wirtz, M., E-mail: hammers-wirtz@gaiac.rwth-aachen.d [Research Institute for Ecosystem Analysis and Assessment (gaiac), RWTH Aachen University, Worringerweg 1, 52056 Aachen (Germany); Heininger, P., E-mail: heininger@bafg.d [Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56070 Koblenz (Germany); Neumann-Hensel, H., E-mail: hensel@fintelmann-meyer.d [Dr. Fintelmann and Dr. Meyer, Mendelssohnstr. 15D, 22761 Hamburg (Germany); Ottermanns, R., E-mail: ottermanns@bio5.rwth-aachen.d [Chair for Environmental Biology and Chemodynamics, Institute for Environmental Research (Biology 5), RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Ratte, H.-T., E-mail: toni.ratte@bio5.rwth-aachen.d [Chair for Environmental Biology and Chemodynamics, Institute for Environmental Research (Biology 5), RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany)

    2010-09-15

    Freshwater sediments with low levels of anthropogenic contamination and a broad range of geochemical properties were investigated using various sediment-contact tests in order to study the natural variability and to define toxicity thresholds for the various toxicity endpoints. Tests were performed with bacteria (Arthrobacter globiformis), yeast (Saccharomyces cerevisiae), nematodes (Caenorhabditis elegans), oligochaetes (Lumbriculus variegatus), higher plants (Myriophyllum aquaticum), and the eggs of zebrafish (Danio rerio). The variability in the response of some of the contact tests could be explained by particle size distribution and organic content. Only for two native sediments could a pollution effect not be excluded. Based on the minimal detectable difference (MDD) and the maximal tolerable inhibition (MTI), toxicity thresholds (% inhibition compared to the control) were derived for each toxicity parameter: >20% for plant growth and fish-egg survival, >25% for nematode growth and oligochaete reproduction, >50% for nematode reproduction and >60% for bacterial enzyme activity. - Sediment-contact tests require toxicity thresholds based on their variability in native sediments with low-level contamination.

  1. Accumulation and toxicokinetics of fluoranthene in sediment bioassays with freshwater amphipods

    Energy Technology Data Exchange (ETDEWEB)

    Driscoll, S.K.; Harkey, G.A.; Landrum, P.F. [National Oceanic and Atmospheric Administration, Ann Arbor, MI (United States). Great Lakes Environmental Research Lab.

    1997-04-01

    Two freshwater amphipods, Hyalella azteca and Diporeia sp., were exposed to sediment spiked with radiolabeled fluoranthene at nominal concentrations of 0.1 (trace) to 1,270 nmol fluoranthene/g dry weight. In two experiments, uptake kinetics and mortality were determined over 30-d exposures. Concentrations of fluoranthene in sediment and pore water were also measured. Mean survival of H. azteca was generally high, greater than 90% after 10 or 16 d, and greater than 74% after 30 d. Mean survival was lower for Diporeia, 14% after a 30-d exposure to the highest sediment concentration in experiment 1, and 53% in experiment 2. Tissue concentrations in Diporeia were as high as 2 to 4 {micro}mol/g wet weight, a body burden that could be expected to result in death by narcosis. Hyalella azteca did not typically accumulate more than 1 {micro}mol/g wet weight, which is consistent with the lower observed mortality. Apparent steady-state biota-sediment accumulation factors (BSAFs, lipid- and organic-carbon-normalized) for sediment concentrations other than trace level tended to be higher for Diporeia than for H. azteca. The BSAFs for trace levels tended to be lower for both species in comparison to higher sediment concentrations. For both organisms, the internal concentration based on body residue was a more reliable indicator of toxicity than were equilibrium partitioning predictions.

  2. The Distribution Pattern of Sediment Archaea Community of the Poyang Lake, the Largest Freshwater Lake in China

    Directory of Open Access Journals (Sweden)

    Yantian Ma

    2016-01-01

    Full Text Available Archaea plays an important role in the global geobiochemical circulation of various environments. However, much less is known about the ecological role of archaea in freshwater lake sediments. Thus, investigating the structure and diversity of archaea community is vital to understand the metabolic processes in freshwater lake ecosystems. In this study, sediment physicochemical properties were combined with the results from 16S rRNA clone library-sequencing to examine the sediment archaea diversity and the environmental factors driving the sediment archaea community structures. Seven sites were chosen from Poyang Lake, including two sites from the main lake body and five sites from the inflow river estuaries. Our results revealed high diverse archaea community in the sediment of Poyang Lake, including Bathyarchaeota (45.5%, Euryarchaeota (43.1%, Woesearchaeota (3.6%, Pacearchaeota (1.7%, Thaumarchaeota (1.4%, suspended Lokiarchaeota (0.7%, Aigarchaeota (0.2%, and Unclassified Archaea (3.8%. The archaea community compositions differed among sites, and sediment property had considerable influence on archaea community structures and distribution, especially total organic carbon (TOC and metal lead (Pb (p<0.05. This study provides primary profile of sediment archaea distribution in freshwater lakes and helps to deepen our understanding of lake sediment microbes.

  3. Influence of benthic macro-invertebrate bioturbation on the biogeochemical behaviour of uranium within freshwater sediments

    International Nuclear Information System (INIS)

    Lagauzere, S.

    2008-06-01

    In freshwater ecosystems, sediments act as an accumulation compartment for metallic pollutants as uranium. Secondary, there can also represent endogenous sources of contamination by resuspension (e.g. flood, bioturbation) or changes of metal speciation that acts upon their bioavailability. Indeed, metallic compounds can be transformed in more or less toxic or inert compounds through physico-chemical (e.g. pH, redox conditions, ionic force) and microbiological variations. These conditions are themselves under the effects of benthic macro-invertebrate activities via bioturbation processes. The main objective of this PhD was to determinate the influence of two benthic macro-invertebrate species (Chironomus riparius and Tubifex tubifex) on the distribution and the transfers of uranium within freshwater sediments. To reach this goal, laboratory experiments were performed in order to (i) assess the effects of uranium on benthic macro-invertebrates, more particularly on their bioturbation activity, (ii) determine the influence of these organisms on uranium behaviour through high resolution physico-chemical measurements (e.g. oxygen optodes, DET gel probes), and (iii) estimate the consequences of these interactions on pelagic organisms via genotoxicity measurements (micronuclei assay and molecular bio-markers analysis on Xenopus laevis). The results demonstrate that bioturbation intensity of macro-invertebrates can be affected in uranium-contaminated sediments, but the two species studied in this work show a relative tolerance. For high uranium concentrations (>100 times the geochemical background level), corresponding however to realistic concentrations in highly contaminated sites, T. tubifex worms are able to maintain a sufficient bioturbation activity that induces a high remobilization of uranium initially associated with sediments to the overlying water (factor 2 to 10). That represents therefore a potential risk for the remaining aquatic biocenose. However, by

  4. Freshwater sediments and sludges: two important terrestrial sinks for emissions from damaged NPPs

    Science.gov (United States)

    Fischer, Helmut W.; Evangelia Souti, Maria; Ulbrich, Susanne; Hormann, Volker

    2013-04-01

    Surface deposition of radionuclides released from the damaged Fukushima NPPs is well documented and emissions to the Pacific Ocean and their distribution with time and space are also subject to monitoring and research. In both cases, solid matter (soil and sea sediment, respectively) acts as a sink for radioisotopes after their transport through air and water. The possible hazards from direct irradiation of workers and public and from entry of radionuclides into food chains are well recognized. Apart from direct deposition onto soil, plants, building roofs etc., aerosols and contaminated rainwater will reach surface waters, leading to long-term deposition in freshwater sediments (and possibly to interim contamination of drinking water). In populated and industrial areas, drained rainwater will enter the wastewater collection and treatment chain if a combined rain and wastewater sewer is used. Depending on the processes in the wastewater treatment plant and chemical element and speciation, the isotopes will either concentrate in treatment sludge or be released with the effluent to rivers and lakes and their sediments. The mentioned media may act as long-term storage for radioisotopes when disposed of properly, but can also contribute to direct irradiation of workers or public, lead to continuous releases to the environment and possibly enter the food chain in the same way as soil and sea sediments. It appears therefore essential to monitor these environmental compartments as well. However, very few data on Fukushima-related radioisotope concentration in sludges and freshwater sediments have been published to date. We will therefore compare data for regional surface deposition and related concentrations in surface water, river sediments and sewage sludge obtained in Europe during 1986 to published data from Japan in 2011 for the most important common short-lived (I-131, half-life = 8.02 d) and long-lived (Cs-137, half-life = 30.17 yr) isotopes. As in central Europe

  5. A comparison of the response of Simocephalus mixtus (Cladocera) and Daphnia magna to contaminated freshwater sediments.

    Science.gov (United States)

    Martínez-Jerónimo, Fernando; Cruz-Cisneros, Jade Lizette; García-Hernández, Leonardo

    2008-09-01

    The southeast region of Mexico is characterized by intensive oil industry activities carried out by the national public enterprise Petróleos Mexicanos (PEMEX). The freshwater lagoon "El Limón", located in the municipality of Macuspana, state of Tabasco, Mexico, has received over 40 years discharges of untreated waste waters from the Petrochemical Complex "Ciudad PEMEX", located on the border of the lagoon. To assess the toxicity of the sediments and, hence, to obtain information on the biological effects of these contaminating discharges, the cladoceran Simocephalus mixtus was used as a test organism in acute (48h) and chronic (12d) toxicity assays. For comparison purposes, bioassays were also conducted with the reference cladoceran Daphnia magna. The sediments of this lagoon contain important amounts of metals and hydrocarbons that have been accumulated over time; however, the acute tests only registered reduced lethal effects on the test organisms (maxima of 10% and 17% mortality for D. magna and S. mixtus, respectively). This may be due to low bioavailability of the pollutants present in the sediments. On the other hand, partial or total inhibition and delay in the start of reproduction, reduction in clutch sizes, reduced survival, as well as reduction in the size of adults and offspring were recorded in the chronic assays. The most evident chronic effects were found in S. mixtus; in this species, reproduction was inhibited up to 72%, whereas D. magna was only affected by 24%. We determined that S. mixtus is a more sensitive test organism than D. magna to assess whole-sediment toxicity in tropical environments, and that chronic exposure bioassays are required for an integrated sediment evaluation. The sediments from "El Limón" lagoon induced chronic intoxication responses and, therefore, remediation measures are urgently needed to recover environmental conditions suitable for the development of its aquatic biota.

  6. Diversity of sulfur-cycle prokaryotes in freshwater lake sediments investigated using aprA as the functional marker gene.

    Science.gov (United States)

    Watanabe, Tomohiro; Kojima, Hisaya; Takano, Yoshinori; Fukui, Manabu

    2013-09-01

    The diversity of sulfate-reducing prokaryotes (SRPs) and sulfur-oxidizing prokaryotes (SOPs) in freshwater lake ecosystems was investigated by cloning and sequencing of the aprA gene, which encodes for a key enzyme in dissimilatory sulfate reduction and sulfur oxidation. To understand their diversity better, the spatial distribution of aprA genes was investigated in sediments collected from six geographically distant lakes in Antarctica and Japan, including a hypersaline lake for comparison. The microbial community compositions of freshwater sediments and a hypersaline sediment showed notable differences. The clones affiliated with Desulfobacteraceae and Desulfobulbaceae were frequently detected in all freshwater lake sediments. The SOP community was mainly composed of four major phylogenetic groups. One of them formed a monophyletic cluster with a sulfur-oxidizing betaproteobacterium, Sulfuricella denitrificans, but the others were not assigned to specific genera. In addition, the AprA sequences, which were not clearly affiliated to either SRP or SOP lineages, dominated the libraries from four freshwater lake sediments. The results showed the wide distribution of some sulfur-cycle prokaryotes across geographical distances and supported the idea that metabolic flexibility is an important feature for SRP survival in low-sulfate environments. Copyright © 2013 Elsevier GmbH. All rights reserved.

  7. Higher trophic level affects nutrient, silicon, metal(loid), and radionuclide mobilization from freshwater sediments

    Science.gov (United States)

    Schaller, Jörg; Planer-Friedrich, Britta

    2017-04-01

    Organic sediments in aquatic ecosystems are well known sinks for nutrients, silicon, and metal(loid)s. Organic matter-decomposing organisms like invertebrate shredders, grazers, bioturbators, and filter feeder are key-species for the carbon and energy turnover within the decomposer community. We could show that invertebrate shredders and grazer affect element fixation or remobilization by changing binding properties of organic sediments and the attached biofilm. Bioturbators affect element fixation or remobilization by changing redox conditions within the uppermost sediment layer. Last but not least filter feeders, like the zebra mussel Dreissena polymorpha, an invasive organism in North American and European freshwater ecosystems significantly contributed to element mobilization of silicon, iron, phosphorus, arsenic, and copper and to immobilization of uranium (phomeostasis. Except of the filter feeder D. polymorpha, the invertebrates are able to minimize the accumulation of non-nutrient elements due to specific strategies, which is an important strategy for species living in systems tending to element accumulation. However, D. polymorpha revealed a significant uptake and accumulation of arsenic, copper, iron, and especially uranium both into the soft body tissues and the seashell. This accumulation by D. polymorpha is in line with previous observations of metal(loid) accumulation from biomonitoring studies. In summary, higher trophic level strongly contributes to element fixation or remobilization in aquatic systems.

  8. Vertical segregation and phylogenetic characterization of ammonia-oxidizing bacteria and archaea in the sediment of a freshwater aquaculture pond

    Directory of Open Access Journals (Sweden)

    Shimin eLu

    2016-01-01

    Full Text Available Pond aquaculture is the major freshwater aquaculture method in China. Ammonia-oxidizing communities inhabiting pond sediments play an important role in controlling culture water quality. However, the distribution and activities of ammonia-oxidizing microbial communities along sediment profiles are poorly understood in this specific environment. Vertical variations in the abundance, transcription, potential ammonia oxidizing rate, and community composition of ammonia-oxidizing bacteria (AOB and ammonia-oxidizing archaea (AOA in sediment samples (0–50 cm depth collected from a freshwater aquaculture pond were investigated. The concentrations of the AOA amoA gene were higher than those of the AOB by an order of magnitude, which suggested that AOA, as opposed to AOB, were the numerically predominant ammonia-oxidizing organisms in the surface sediment. This could be attributed to the fact that AOA are more resistant to low levels of dissolved oxygen. However, the concentrations of the AOB amoA mRNA were higher than those of the AOA by 2.5–39.9-fold in surface sediments (0–10 cm depth, which suggests that the oxidation of ammonia was mainly performed by AOB in the surface sediments, and by AOA in the deeper sediments, where only AOA could be detected. Clone libraries of AOA and AOB amoA sequences indicated that the diversity of AOA and AOB decreased with increasing depth. The AOB community consisted of two groups: the Nitrosospira and Nitrosomonas clusters, and Nitrosomonas were predominant in the freshwater pond sediment. All AOA amoA gene sequences in the 0–2 cm deep sediment were grouped into the Nitrososphaera cluster, while other AOA sequences in deeper sediments (10–15 and 20–25 cm depths were grouped into the Nitrosopumilus cluster.

  9. Seasonal and spatial variations in heterotrophic nanoflagellate and bacteria abundances in sediments of a freshwater littoral zone

    NARCIS (Netherlands)

    Starink, Mathieu; Bär-Gilissen, M.J.; Cappenberg, T.E.

    1996-01-01

    We studied seasonal variation in heterotrophic nanoflagellates (HNAN) and bacterial, densities at different depths in the sediment of two freshwater littoral stations. Station 1 was in a reed bed of Phragmites australis; station 2 was outside the reed zone in open water. Benthic HNAN abundances

  10. Exposure dose response relationships of the freshwater bivalve Hyridella australis to cadmium spiked sediments

    International Nuclear Information System (INIS)

    Marasinghe Wadige, Chamani P.M.; Maher, William A.; Taylor, Anne M.; Krikowa, Frank

    2014-01-01

    Highlights: • The exposure–dose–response approach was used to assess cadmium exposure and toxicity. • Accumulated cadmium in H. australis reflected the sediment cadmium exposure. • Spill over of cadmium into the biologically active pool was observed. • Increased cadmium resulted in measurable biological effects. • H. australis has the potential to be a cadmium biomonitor in freshwater environments. - Abstract: To understand how benthic biota may respond to the additive or antagonistic effects of metal mixtures in the environment it is first necessary to examine their responses to the individual metals. In this context, laboratory controlled single metal-spiked sediment toxicity tests are useful to assess this. The exposure–dose–response relationships of Hyridella australis to cadmium-spiked sediments were, therefore, investigated in laboratory microcosms. H. australis was exposed to individual cadmium spiked sediments (<0.05 (control), 4 ± 0.3 (low) and 15 ± 1 (high) μg/g dry mass) for 28 days. Dose was measured as cadmium accumulation in whole soft body and individual tissues at weekly intervals over the exposure period. Dose was further examined as sub-cellular localisation of cadmium in hepatopancreas tissues. The biological responses in terms of enzymatic and cellular biomarkers were measured in hepatopancreas tissues at day 28. H. australis accumulated cadmium from spiked sediments with an 8-fold (low exposure organisms) and 16-fold (high exposure organisms) increase at day 28 compared to control organisms. The accumulated tissue cadmium concentrations reflected the sediment cadmium exposure at day 28. Cadmium accumulation in high exposure organisms was inversely related to the tissue calcium concentrations. Gills of H. australis showed significantly higher cadmium accumulation than the other tissues. Accumulated cadmium in biologically active and biologically detoxified metal pools was not significantly different in cadmium exposed

  11. Exposure dose response relationships of the freshwater bivalve Hyridella australis to cadmium spiked sediments

    Energy Technology Data Exchange (ETDEWEB)

    Marasinghe Wadige, Chamani P.M., E-mail: chamani.marasinghe.wadige@canberra.edu.au; Maher, William A.; Taylor, Anne M.; Krikowa, Frank

    2014-07-01

    Highlights: • The exposure–dose–response approach was used to assess cadmium exposure and toxicity. • Accumulated cadmium in H. australis reflected the sediment cadmium exposure. • Spill over of cadmium into the biologically active pool was observed. • Increased cadmium resulted in measurable biological effects. • H. australis has the potential to be a cadmium biomonitor in freshwater environments. - Abstract: To understand how benthic biota may respond to the additive or antagonistic effects of metal mixtures in the environment it is first necessary to examine their responses to the individual metals. In this context, laboratory controlled single metal-spiked sediment toxicity tests are useful to assess this. The exposure–dose–response relationships of Hyridella australis to cadmium-spiked sediments were, therefore, investigated in laboratory microcosms. H. australis was exposed to individual cadmium spiked sediments (<0.05 (control), 4 ± 0.3 (low) and 15 ± 1 (high) μg/g dry mass) for 28 days. Dose was measured as cadmium accumulation in whole soft body and individual tissues at weekly intervals over the exposure period. Dose was further examined as sub-cellular localisation of cadmium in hepatopancreas tissues. The biological responses in terms of enzymatic and cellular biomarkers were measured in hepatopancreas tissues at day 28. H. australis accumulated cadmium from spiked sediments with an 8-fold (low exposure organisms) and 16-fold (high exposure organisms) increase at day 28 compared to control organisms. The accumulated tissue cadmium concentrations reflected the sediment cadmium exposure at day 28. Cadmium accumulation in high exposure organisms was inversely related to the tissue calcium concentrations. Gills of H. australis showed significantly higher cadmium accumulation than the other tissues. Accumulated cadmium in biologically active and biologically detoxified metal pools was not significantly different in cadmium exposed

  12. Cytotoxicity of TiO{sub 2} nanoparticles towards freshwater sediment microorganisms at low exposure concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, Jyoti; Kumar, Deepak; Mathur, Ankita; Naseer, Arif; Kumar, Ravi Ranjan [Centre for Nanobiotechnology, VIT University, Vellore 632014 (India); Thanjavur Chandrasekaran, Prathna [Department of Materials Engineering, Indian Institute of Science, Bangalore (India); Chaudhuri, Gouri; Pulimi, Mrudula [Centre for Nanobiotechnology, VIT University, Vellore 632014 (India); Raichur, Ashok M. [Department of Materials Engineering, Indian Institute of Science, Bangalore (India); Department of Chemical Technology, University of Johannesburg (South Africa); Babu, S. [School of Bio Sciences and Technology, VIT University, Vellore (India); Chandrasekaran, Natarajan [Centre for Nanobiotechnology, VIT University, Vellore 632014 (India); Nagarajan, R. [Department of Chemical Engineering, IIT Madras, Chennai (India); Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com [Centre for Nanobiotechnology, VIT University, Vellore 632014 (India)

    2014-11-15

    There is a persistent need to assess the effects of TiO{sub 2} nanoparticles on the aquatic ecosystem owing to their increasing usage in consumer products and risk of environmental release. The current study is focused on TiO{sub 2} nanoparticle-induced acute toxicity at sub-ppm level (≤1 ppm) on the three different freshwater sediment bacterial isolates and their consortium under two different irradiation (visible light and dark) conditions. The consortium of the bacterial isolates was found to be less affected by the exposure to the nanoparticles compared to the individual cells. The oxidative stress contributed considerably towards the cytotoxicity under both light and dark conditions. A statistically significant increase in membrane permeability was noted under the dark conditions as compared to the light conditions. The optical and fluorescence microscopic images showed aggregation and chain formation of the bacterial cells, when exposed to the nanoparticles. The electron microscopic (SEM, TEM) observations suggested considerable damage of cells and bio-uptake of nanoparticles. The exopolysaccrides (EPS) production and biofilm formation were noted to increase in the presence of the nanoparticles, and expression of the key genes involved in biofilm formation was studied by RT-PCR. - Highlights: • Toxicity of NPs towards freshwater sediment bacteria at sub-ppm concentrations. • Decreased toxicity of the nanoparticles in the consortium of microorganisms. • Enhanced bacterial resistance through EPS and biofilm formation in the presence of NPs. • Considerable surface damage of cells and internalization of NPs. • Gene expression analyses related to biofilm formation in the presence of NPs.

  13. Anthropogenic pollutants affect ecosystem services of freshwater sediments. The need for a 'triad plus x' approach

    Energy Technology Data Exchange (ETDEWEB)

    Gerbersdorf, Sabine Ulrike; Wieprecht, Silke [Stuttgart Univ. (Germany). Dept. of Hydraulic Engineering and Water Resources Management; Hollert, Henner; Brinkmann, Markus [RWTH Aachen Univ. (Germany). Dept. of Ecosystem Analysis; Schuettrumpf, Holger [RWTH Aachen Univ. (Germany). Inst. of Hydraulic Engineering and Water Resources Management; Manz, Werner [Koblenz-Landau Univ., Koblenz (Germany). Inst. for Integrated Natural Sciences

    2011-09-15

    Purpose: Freshwater sediments and their attached microbial communities (biofilms) are essential features of rivers and lakes, providing valuable ecosystem services such as nutrient recycling or self-purification which extend beyond the aquatic environment. Anthropogenic pollutants, whether from the industrial era or as a result of our contemporary lifestyles, can negatively affect these functions with hitherto unknown consequences on ecology, the economy and human health. Thus far, the singular view of the involved disciplines such as ecotoxicology, environmental microbiology, hydrology and geomorphology has prevented a deeper understanding of this emerging issue. Main features: This paper discusses briefly the progressions and the state-of-the-art methods within the disciplines of concern related to contaminated sediments, ranging from ecotoxicological test systems, microbiological/molecular approaches to unravel changes of microbial ecosystems, up to the modelling of sediment transport and sorption/desorption of associated pollutants. The first bilateral research efforts on contaminated sediments include efforts to assess ecotoxicological sediment risk including sediment mobility (i.e. ecotoxicology and engineering), enhance bioremediation potential (i.e. microbiology and ecotoxicology) or to understand biostabilisation processes of sediments by microbial assemblages (i.e. microbiology and engineering). Conclusions and perspectives: In freshwater habitats, acute, chronic and mechanism-specific toxic effects on organisms, shifts in composition, structure and functionality of benthic microbial communities, as well as the obstruction of important ecosystem services by continuously discharged and long-deposited pollutants, should be related to the in situ sediment dynamics. To achieve an improved understanding of the ecology of freshwater sediments and the impairment of their important ecosystem functions by human-derived pollutants, we suggest a 'triad plus x

  14. Factors influencing successful collaboration for freshwater management in Aotearoa, New Zealand

    Directory of Open Access Journals (Sweden)

    Nicholas A. Cradock-Henry

    2017-06-01

    Full Text Available Public participation in freshwater management has been widely advocated as an effective way to resolve the tensions between contested values and objectives while maintaining ecological integrity. However, questions remain regarding which processes and factors contribute to successful processes and outcomes for freshwater. Using a comparative case-study methodology, we unravel the "noise of participation" to assess the factors that influence the success of participatory decision making in collaborative processes currently underway in Hawke's Bay and Northland, Aotearoa, New Zealand. In Hawke's Bay, participants have been periodically surveyed to solicit their perceptions of how the process is working and the likelihood of achieving desirable outcomes. In Northland, five identical processes are currently underway, one per catchment, providing the basis for an intraregional assessment of collaboration. Our results suggest that participants' perceptions change within the process, and that those changes may involve complex, dynamic, and reciprocal interactions within the collaborative group. Results also show the strong influence of external conditions. The choice of stakeholder participants is also critical to ensuring the viability of collaboration. Key factors include participants' previous interactions and relationships, which may help to prime them for collaboration. These factors are dynamic and evolve through different cycles. Although both collaborative processes are still underway, these insights may help focus greater attention to process design and stakeholder selection from the outset to ensure successful outcomes. Ultimately, a successful collaborative process is one that is able to incorporate feedback and adapt to changing the dynamic and often complex external environment.

  15. The trace element analysis in freshwater fish species, water and sediment in Iyidere stream (Rize-Turkey).

    Science.gov (United States)

    Verep, Bulent; Mutlu, Cengiz; Apaydin, Gokhan; Cevik, Ugur

    2012-07-15

    Many environmental problems like dam construction, agricultural debris, flooding and industrial establishments threaten Iyidere stream (Rize, Turkey) on the southeastern coast of the Black Sea (Turkey). The trace element concentrations in water, fish and sediments in lyidere stream (Rize, Turkey) were investigated in this study. The concentration of six different elements in ten freshwater fish species and sediment was determined using energy dispersive X-ray fluorescence method. A radioisotope excited X-ray fluorescence analysis using the method of multiple standard addition is applied for the elemental analysis of fish and sediments. Water samples for trace metals were analyzed using standard spectrophotometry methods. A qualitative analysis of spectral peaks showed that ten different freshwater fish samples (Chondrostoma colchicum, Chalcalburnus chalcoides, Salmo trutta labrax, Alburnoides bipunctatus, Leuciscus cephalus, Barbus taurus escherichia, Capoeta tinca, Neogobius kessleri, Rutilus frisii, Lampetra lanceolata) and sediment contained phosphorus (P), sulphur (S), chlorine (Cl), potassium (K), calcium (Ca) and titanium (Ti). Heavy metals as toxic elements for biota (Pb, Cd, Hg, Zn and Mn etc.) were not detected in fish, water and sediments. Thus, It can be declared that freshwater fish of Iyidere does not contains health risks for consumers in terms of metal pollution.

  16. Occurrence of triclosan, triclocarban, and its lesser chlorinated congeners in Minnesota freshwater sediments collected near wastewater treatment plants

    Science.gov (United States)

    Venkatesan, Arjun K.; Pycke, Benny F.G.; Barber, Larry B.; Lee, Kathy E.; Halden, Rolf U.

    2012-01-01

    The antimicrobial agents triclosan (TCS), triclocarban (TCC) and their associated transformation products are of increasing concern as environmental pollutants due to their potential adverse effects on humans and wildlife, including bioaccumulation and endocrine-disrupting activity. Analysis by tandem mass spectrometry of 24 paired freshwater bed sediment samples (top 10 cm) collected by the U.S. Geological Survey near 12 wastewater treatment plants (WWTPs) in Minnesota revealed TCS and TCC concentrations of up to 85 and 822 ng/g dry weight (dw), respectively. Concentrations of TCS and TCC in bed sediments collected downstream of WWTPs were significantly greater than upstream concentrations in 58% and 42% of the sites, respectively. Dichloro- and non-chlorinated carbanilides (DCC and NCC) were detected in sediments collected at all sites at concentrations of up to 160 and 1.1 ng/g dw, respectively. Overall, antimicrobial concentrations were significantly higher in lakes than in rivers and creeks, with relative abundances decreasing from TCC > TCS > DCC > NCC. This is the first statewide report on the occurrence of TCS, TCC and TCC transformation products in freshwater sediments. Moreover, the results suggest biological or chemical TCC dechlorination products to be ubiquitous in freshwater environments of Minnesota, but whether this transformation occurs in the WWTP or bed sediment remains to be determined.

  17. Preparation and characterization of nickel-spiked freshwater sediments for toxicity tests: toward more environmentally realistic nickel partitioning.

    Science.gov (United States)

    Brumbaugh, William G; Besser, John M; Ingersoll, Christopher G; May, Thomas W; Ivey, Chris D; Schlekat, Christian E; Garman, Emily Rogevich

    2013-11-01

    Two spiking methods were compared and nickel (Ni) partitioning was evaluated during a series of toxicity tests with 8 different freshwater sediments having a range of physicochemical characteristics. A 2-step spiking approach with immediate pH adjustment by addition of NaOH at a 2:1 molar ratio to the spiked Ni was effective in producing consistent pH and other chemical characteristics across a range of Ni spiking levels. When Ni was spiked into sediment having a high acid-volatile sulfide and organic matter content, a total equilibration period of at least 10 wk was needed to stabilize Ni partitioning. However, highest spiking levels evidently exceeded sediment binding capacities; therefore, a 7-d equilibration in toxicity test chambers and 8 volume-additions/d of aerobic overlying water were used to avoid unrealistic Ni partitioning during toxicity testing. The 7-d pretest equilibration allowed excess spiked Ni and other ions from pH adjustment to diffuse from sediment porewater and promoted development of an environmentally relevant, 0.5- to 1-cm oxic/suboxic sediment layer in the test chambers. Among the 8 different spiked sediments, the logarithm of sediment/porewater distribution coefficient values (log Kd ) for Ni during the toxicity tests ranged from 3.5 to 4.5. These Kd values closely match the range of values reported for various field Ni-contaminated sediments, indicating that testing conditions with our spiked sediments were environmentally realistic. © 2013 SETAC.

  18. Bioaccumulation of polychlorinated biphenyls and metals from contaminated sediment by freshwater prawns, Macrobrachium rosenbergii and clams, Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Tatem, H.E.

    1986-02-01

    Freshwater prawns, Macrobrachium rosenbergii, and clams, Corbicula Fluminea, were exposed for 48 or 50 days to three concentrations of a river sediment that contained environmental contaminants such as polychlorinated biphenyls (PCBs) and metals. The PCB sediment bioaccumulation factors (BAF) for prawns ranged from 0.11 to 0.90 for 1242 and 0.20 to 2.40 for 1254, and were highest for animals exposed to 10% sediment. Exposed clams also accumulated PCBs (1242 + 1254) from the sediment. Sediment BAFs for clams were 0.54 to 12.52 and were highest for animals exposed to 10% sediment. Analyses of clams for metals showed lead (Pb) in exposed animals at higher concentrations compared with controls. Bioaccumulation of Pb differed from PCB in that the Pb concentrations did not increase over time and concentrations were higher among animals exposed to 10% sediment compared to animals exposed to 100% sediment. Sediment 11-80 contained 99 mg/kg of Pb while exposed animals, at 48 days, contained approximately 2.2 mg/kg Pb. Analysis of clams for cadmium (Cd) showed exposed animals contained less Cd than controls.

  19. Assimilation of remote sensing observations into a sediment transport model of China's largest freshwater lake: spatial and temporal effects.

    Science.gov (United States)

    Zhang, Peng; Chen, Xiaoling; Lu, Jianzhong; Zhang, Wei

    2015-12-01

    Numerical models are important tools that are used in studies of sediment dynamics in inland and coastal waters, and these models can now benefit from the use of integrated remote sensing observations. This study explores a scheme for assimilating remotely sensed suspended sediment (from charge-coupled device (CCD) images obtained from the Huanjing (HJ) satellite) into a two-dimensional sediment transport model of Poyang Lake, the largest freshwater lake in China. Optimal interpolation is used as the assimilation method, and model predictions are obtained by combining four remote sensing images. The parameters for optimal interpolation are determined through a series of assimilation experiments evaluating the sediment predictions based on field measurements. The model with assimilation of remotely sensed sediment reduces the root-mean-square error of the predicted sediment concentrations by 39.4% relative to the model without assimilation, demonstrating the effectiveness of the assimilation scheme. The spatial effect of assimilation is explored by comparing model predictions with remotely sensed sediment, revealing that the model with assimilation generates reasonable spatial distribution patterns of suspended sediment. The temporal effect of assimilation on the model's predictive capabilities varies spatially, with an average temporal effect of approximately 10.8 days. The current velocities which dominate the rate and direction of sediment transport most likely result in spatial differences in the temporal effect of assimilation on model predictions.

  20. Occurrence of triclosan, triclocarban, and Its Lesser Chlorinated Congeners in Minnesota Freshwater Sediments Collected Near Wastewater Treatment Plants

    OpenAIRE

    Venkatesan, Arjun K.; Pycke, Benny F.G.; Barber, Larry B.; Lee, Kathy E.; Halden, Rolf U.

    2012-01-01

    The antimicrobial agents triclosan (TCS), triclocarban (TCC) and their associated transformation products are of increasing concern as environmental pollutants due to their potential adverse effects on humans and wildlife, including bioaccumulation and endocrine-disrupting activity. Analysis by tandem mass spectrometry of 24 paired freshwater bed sediment samples (top 10 cm) collected by the U.S. Geological Survey near 12 wastewater treatment plants (WWTPs) in Minnesota revealed TCS and TCC c...

  1. Toxicity of sediments from lead-zinc mining areas to juvenile freshwater mussels (Lampsilis siliquoidea) compared to standard test organisms

    Science.gov (United States)

    Besser, John M.; Ingersoll, Christopher G.; Brumbaugh, William G.; Kemble, Nile E.; May, Thomas W.; Wang, Ning; MacDonald, Donald D.; Roberts, Andrew D.

    2015-01-01

    Sediment toxicity tests compared chronic effects on survival, growth, and biomass of juvenile freshwater mussels (28-d exposures with Lampsilis siliquoidea) to the responses of standard test organisms—amphipods (28-d exposures with Hyalella azteca) and midges (10-d exposures with Chironomus dilutus)—in sediments from 2 lead–zinc mining areas: the Tri-State Mining District and Southeast Missouri Mining District. Mussel tests were conducted in sediments sieved to <0.25 mm to facilitate recovery of juvenile mussels (2–4 mo old). Sediments were contaminated primarily with lead, zinc, and cadmium, with greater zinc and cadmium concentrations in Tri-State sediments and greater lead concentrations in southeast Missouri sediments. The frequency of highly toxic responses (reduced 10% or more relative to reference sites) in Tri-State sediments was greatest for amphipod survival (25% of samples), midge biomass (20%), and mussel survival (14%). In southeast Missouri sediments, the frequency of highly toxic samples was greatest for mussel biomass (25%) and amphipod biomass (13%). Thresholds for metal toxicity to mussels, expressed as hazard quotients based on probable effect concentrations, were lower for southeast Missouri sediments than for Tri-State sediments. Southeast Missouri sites with toxic sediments had 2 or fewer live mussel taxa in a concurrent mussel population survey, compared with 7 to 26 taxa at reference sites. These results demonstrate that sediment toxicity tests with juvenile mussels can be conducted reliably by modifying existing standard methods; that the sensitivity of mussels to metals can be similar to or greater than standard test organisms; and that responses of mussels in laboratory toxicity tests are consistent with effects on wild mussel populations.

  2. Bioavailability and toxicity of metals from a contaminated sediment by acid mine drainage: linking exposure-response relationships of the freshwater bivalve Corbicula fluminea to contaminated sediment.

    Science.gov (United States)

    Sarmiento, Aguasanta M; Bonnail, Estefanía; Nieto, José Miguel; DelValls, Ángel

    2016-11-01

    Streams and rivers strongly affected by acid mine drainage (AMD) have legal vacuum in terms of assessing the water toxicity, since the use of conventional environmental quality biomarkers is not possible due to the absence of macroinvertebrate organisms. The Asian clam Corbicula fluminea has been widely used as a biomonitor of metal contamination by AMD in freshwater systems. However, these clams are considered an invasive species in Spain and the transplantation in the field study is not allowed by the Environmental Protection Agency. To evaluate the use of the freshwater bivalve C. fluminea as a potential biomonitor for sediments contaminated by AMD, the metal bioavailability and toxicity were investigated in laboratory by exposure of clams to polluted sediments for 14 days. The studied sediments were classified as slightly contaminated with As, Cr, and Ni; moderately contaminated with Co; considerably contaminated with Pb; and heavily contaminated with Cd, Zn, and specially Cu, being reported as very toxic to Microtox. On the fourth day of the exposure, the clams exhibited an increase in concentration of Ga, Ba, Sb, and Bi (more than 100 %), followed by Co, Ni, and Pb (more than 60 %). After the fourth day, a decrease in concentration was observed for almost all metals studied except Ni. An allometric function was used to determine the relationship between the increases in metal concentration in soft tissue and the increasing bioavailable metal concentrations in sediments.

  3. Single-walled carbon nanotubes toxicity to the freshwater amphipod Hyalella azteca: influence of sediment and exposure duration

    Directory of Open Access Journals (Sweden)

    Messika Revel

    2015-04-01

    Full Text Available Carbon nanomaterials are present in various industrial applications and therefore their release into the environment including freshwater ecosystem is expected to increase. The aim of the present study was to investigate the influence of several parameters on the toxicity of single-walled carbon nanotubes (SWCNT to the freshwater amphipod, Hyalella azteca. The effect of period of exposure, sediment presence and possible impurities released during SWCNT preparation on survival and/or growth of such organism was evaluated. We measured a reduction of survival at concentrations ranging from 10 to 40 mg/L after 96-h exposure, while no mortality was observed with the same concentrations and in the presence of artificial sediment after 14 days of exposure. It is possible that SWCNT are adsorbed on the organic matter from the artificial sediment leading to a decrease of SWCNT bioavailability. The survival and growth toxicity tests revealed a stronger effect at 28 days compared to the 14 days of exposure, and full mortality of organisms at 1000 mg/L for both exposure times. The presence of SWCNT in the gut of survived organisms was observed. The present study demonstrates that the interaction with sediment should be considered when carbon nanotubes toxicity through water exposure is investigated.

  4. Influence of allochtonous carbon input and food-web structure on freshwater biotic communities and sedimentation process

    Science.gov (United States)

    Harrault, Loïc; Allard, Béatrice; Mériguet, Jacques; Carmignac, David; Perret, Samuel; Huon, Sylvain; Edeline, Eric; Lacroix, Gérard

    2013-04-01

    Soil erosion in freshwaters induces important changes in lake metabolism. The organic matter and the nutrients supplied by soil inputs can change internal biogeochemical cycles and subsidize the whole food web from basal organisms to top-predators. Since the last two decades, the role of allochthonous organic matter as a basal resource for aquatic food webs in natural and controlled conditions has received a growing attention. We studied the impact of soil on the functioning of pond ecosystems by performing monthly additions of soil in freshwater mesocosms. In addition, the food-web structure was manipulated by addition of omnivorous fish to study interactions between the bottom-up effect of soil addition and the top-down effect of fish. The effects of soil and fish addition on the, the elemental and the biochemical compositions of pelagic compartments and recent sediment, on the biomass of seston and zooplankton and on the sediment rates were studied. Soil inputs had no effect on biomass, stoichiometry and lipid composition of seston and zooplankton but fish growth was enhanced by soil addition. Soil treatment had several (but idiosyncratic) effects on the stoichiometry and on the lipid composition of recent sediment. However, the sedimentation rates and the potential biodegradability of recent sediment were not affected by soil inputs. Fish addition affected chlorophyll-a concentration of the water column, seston biomass, sedimentation rates and stoichiometry of seston, zooplankton and short-term sediment. The lipid composition of recent sediment was also influenced by fish addition. However, fish addition did not change the biodegradability of recent sediment. Finally, we did not observe any significant interaction between soil and fish treatments. Our results suggest that the addition of soil as allochthonous inputs to aquatic ecosystem induced a subsidize of the food web only on fish, probably due to direct foraging on bottom sediment. Nevertheless, this

  5. The fate of nitrogen is linked to iron(II) availability in a freshwater lake sediment

    Science.gov (United States)

    Robertson, Elizabeth K.; Thamdrup, Bo

    2017-05-01

    The fate of nitrogen in natural environments is controlled by anaerobic nitrate-reducing processes by which nitrogen is removed as N2 or retained as NH4+. These processes can potentially be driven by oxidation of reduced inorganic compounds at oxic-anoxic interfaces. Several studies have investigated the use of Fe2+ as an electron donor in nitrate reduction in bacterial cultures, however current information on this process in the environment is sparse. We aimed to determine whether nitrate-reducing processes in the freshwater Lake Almind (Silkeborg, Denmark) were linked to Fe2+ oxidation. Anaerobic sediment slurries were supplemented with 15N-substrates and electron donors (Fe2+ and/or acetate) to characterize nitrate-reducing processes under environmentally relevant substrate concentrations and at higher concentrations traditionally used in microbial enrichment studies. Dissimilatory nitrate reduction to ammonium, DNRA, was stimulated by Fe2+ addition in 7 of 10 slurry experiments and in some cases, denitrification was concomitantly reduced. The determined kinetic parameters (Vmax and Km) for Fe2+-driven DNRA were 4.7 μmol N L-1 d-1 and 33.8 μmol Fe2+ L-1, respectively and reaction stoichiometry for Fe2+:NH4+ (8.2:1) was consistent with that of predicted stoichiometry (8:1). Conversely, under enrichment conditions, denitrification was greatly increased while DNRA rates remained unchanged. Increased Fe2+ concentrations may be exploited by DNRA organisms and have an inhibitory effect on denitrification, thus Fe2+ may play a role in regulating N transformations in Lake Almind. Furthermore, we suggest enrichment conditions may promote the adaptation or change of microbial communities to optimally utilize the available high substrate concentrations; misrepresenting metabolisms occurring in situ.

  6. GC-MS method for determining faecal sterols as biomarkers of human and pastoral animal presence in freshwater sediments.

    Science.gov (United States)

    Battistel, Dario; Piazza, Rossano; Argiriadis, Elena; Marchiori, Enrico; Radaelli, Marta; Barbante, Carlo

    2015-11-01

    In order to determine sterols and stanols in freshwater sediments to reconstruct the past presence of humans and pastoral animals, we developed an analytical method based on pressurised liquid extraction (PLE), clean-up performed using solid phase extraction (SPE) and sterol determination using gas chromatography-mass spectrometry (GC-MS) analysis. PLE extraction conditions were optimised using dichloromethane (DCM) and DCM/methanol mixtures. Clean-up was performed with 2 g silica SPE cartridges, and the concentrated extracts were eluted with 70 mL DCM. Extraction yield was evaluated using an in-house reference material spiked with (13)C-labelled cholesterol and aged for 10 days. In comparison with pre-extraction, where the sediment is extracted and then spiked with a known analyte concentration, this approach preserves the original composition of the sediment. DCM and DCM/methanol mixtures resulted in high extraction yields ranging from 86 to 92 % with good reproducibility (relative standard deviation (RSD) 5-8 %). PLE extraction yields obtained with DCM as the extracting solvent were about 1.5 times higher than extractions using an ultrasonic bath. The solvent extraction mixture and matrix composition strongly affected the solvent extraction composition where higher overall recoveries (70-80 %) for each compound were obtained with DCM. The extraction mixture and matrix composition also affected the analyte concentrations, resulting in a method precision ranging from 1 to 18 %. Diatomaceous earth spiked with 10 to 100 ng of sterols, and environmental samples fortified with suitable amounts of sterols provided apparent recovery values ranging from 90 to 110 %. We applied the method to environmental samples both close to and upstream from sewage discharge zones, resulting in substantially higher faecal sterol (FeSt) concentrations near the sewage. In addition, we also applied the method to a 37-cm freshwater sediment core in order to evaluate its applicability for

  7. Phytoplankton succession in a tropical freshwater lake, Bhoj Wetland (Bhopal, India): spatial and temporal perspective

    Digital Repository Service at National Institute of Oceanography (India)

    Ahmed, A.; Wangane, A.

    Bhoj Wetland is tropical freshwater system in central India �Bhopal� serving the citizens as one of the major source of water since its inception Understanding the process of phytoplankton variation can be particularly useful in water quality...

  8. Microbiome succession during ammonification in eelgrass bed sediments

    Directory of Open Access Journals (Sweden)

    Cassandra L. Ettinger

    2017-08-01

    Full Text Available Background Eelgrass (Zostera marina is a marine angiosperm and foundation species that plays an important ecological role in primary production, food web support, and elemental cycling in coastal ecosystems. As with other plants, the microbial communities living in, on, and near eelgrass are thought to be intimately connected to the ecology and biology of eelgrass. Here we characterized the microbial communities in eelgrass sediments throughout an experiment to quantify the rate of ammonification, the first step in early remineralization of organic matter, also known as diagenesis, from plots at a field site in Bodega Bay, CA. Methods Sediment was collected from 72 plots from a 15 month long field experiment in which eelgrass genotypic richness and relatedness were manipulated. In the laboratory, we placed sediment samples (n = 4 per plot under a N2 atmosphere, incubated them at in situ temperatures (15 °C and sampled them initially and after 4, 7, 13, and 19 days to determine the ammonification rate. Comparative microbiome analysis using high throughput sequencing of 16S rRNA genes was performed on sediment samples taken initially and at seven, 13 and 19 days to characterize changes in the relative abundances of microbial taxa throughout ammonification. Results Within-sample diversity of the sediment microbial communities across all plots decreased after the initial timepoint using both richness based (observed number of OTUs, Chao1 and richness and evenness based diversity metrics (Shannon, Inverse Simpson. Additionally, microbial community composition changed across the different timepoints. Many of the observed changes in relative abundance of taxonomic groups between timepoints appeared driven by sulfur cycling with observed decreases in predicted sulfur reducers (Desulfobacterales and corresponding increases in predicted sulfide oxidizers (Thiotrichales. None of these changes in composition or richness were associated with variation in

  9. Microbial diversity and community respiration in freshwater sediments influenced by artificial light at night

    Science.gov (United States)

    Hölker, Franz; Wurzbacher, Christian; Weißenborn, Carsten; Monaghan, Michael T.; Holzhauer, Stephanie I. J.; Premke, Katrin

    2015-01-01

    An increasing proportion of the Earth's surface is illuminated at night. In aquatic ecosystems, artificial light at night (ALAN) may influence microbial communities living in the sediments. These communities are highly diverse and play an important role in the global carbon cycle. We combined field and laboratory experiments using sediments from an agricultural drainage system to examine how ALAN affects communities and alters carbon mineralization. Two identical light infrastructures were installed parallel to a drainage ditch before the start of the experiment. DNA metabarcoding indicated that both sediment communities were similar. After one was lit for five months (July–December 2012) we observed an increase in photoautotroph abundance (diatoms, Cyanobacteria) in ALAN-exposed sediments. In laboratory incubations mimicking summer and winter (six weeks each), communities in sediments that were exposed to ALAN for 1 year (July 2012–June 2013) showed less overall seasonal change compared with ALAN-naive sediments. Nocturnal community respiration was reduced in ALAN-exposed sediments. In long-term exposed summer-sediments, we observed a shift from negative to positive net ecosystem production. Our results indicate ALAN may alter sediment microbial communities over time, with implications for ecosystem-level functions. It may thus have the potential to transform inland waters to nocturnal carbon sinks. PMID:25780242

  10. Long-term distribution of Cs-137 in freshwater ecosystem and the effect of bioturbation on leakage of Cs-137 from the sediments

    International Nuclear Information System (INIS)

    Aquilonius, K.

    1995-06-01

    The first aim of the project was to make a literature compilation regarding Cs-137 in freshwater systems. Secondly, in order to follow up the long-term behaviour of Cs-137 in Lake Hillesjoen, sediment and water was sampled with respect to Cs-137. Finally, an experiment was done with chironomids, with the aim to assess the impact of bioturbation on the leakage of Cs-137 from the sediment, since this is one of the factors contributing to the uncertainties in radioecological models. Some aspects of long-term distribution of Cs-137 in freshwater lakes is discussed. In lake Hillesjoen the pool of Cs-137 in sediments (225 kBq/m 2 , 1993) has gradually increased since the Chernobyl accident, and now exceeds the initial deposition (100 kBq/m 2 ). The effect of bioturbation on the leakage from the sediment to the water could not be clarified in this experiment, but is discussed. 40 refs

  11. Succession of cable bacteria and electric currents in marine sediment

    DEFF Research Database (Denmark)

    Schauer, Regina; Risgaard-Petersen, Nils; Kjeldsen, Kasper Urup

    2014-01-01

    Filamentous Desulfobulbaceae have been reported to conduct electrons over centimetre-long distances, thereby coupling oxygen reduction at the surface of marine sediment to sulphide oxidation in sub-surface layers. To understand how these /`cable bacteria/' establish and sustain electric...... conductivity, we followed a population for 53 days after exposing sulphidic sediment with initially no detectable filaments to oxygen. After 10 days, cable bacteria and electric currents were established throughout the top 15[thinsp]mm of the sediment, and after 21 days the filament density peaked with a total...... length of 2[thinsp]km[thinsp]cm-2. Cells elongated and divided at all depths with doubling times over the first 10 days of

  12. 14C dating of freshwater carbonate sediments with special reference to calcareous tufas and laminated lake sediments

    International Nuclear Information System (INIS)

    Pazdur, M.F.

    1992-09-01

    The sequence of laminated sediment of the lake Gosciaz, Poland, covers more than 13,000 years and is actually the longest sequence known so far. Besides of reconstructing past environmental changes, this sequence offers an excellent possibility for studying natural C-14 variations and calibrating the C-14 time scale in a range beyond 6,000 years B.P. The floating varve chronology based on previously taken sediment cores which cover a period of 9,682 years, has been improved by this study. Relative water level changes of the lake during the past 11,500 years have been reconstructed by means of C-14 and C-13 measurements carried out on carbonate fractions of the lake sediments. Periodical variations in the width of annual layers were found. The periods identified are 11 years and 22 years (solar cycle), 35 years (Bruckner cycle), and 200 years. The ratio of summer layer width and the total width of the annual layer shows secular changes which correlate with paleotemperature records. The duration of the Younger Dryas period was determined by combining the floating varve chronology with isotope and pollen analyses of the sediment material. A value of 1,500 years was found. The study also included radiocarbon dating of calcareous tufa taken from different study areas. 26 refs, 26 figs, 6 tabs

  13. Effect Of Iron On The Sensitivity Of Hydrogen, Acetate, And Butyrate Metabolism To Inhibition By Long-Chain Fatty Acids In Vegetable-Oil-Enriched Freshwater Sediments

    Science.gov (United States)

    Freshwater sediment microbial communities enriched by growth on vegetable oil in the presence of a substoichiometric amount of ferric hydroxide (sufficient to accept about 12% of the vegetable-oil-derived electrons) degrade vegetable oil to methane faster than similar microbial c...

  14. Bioavailability and effect of pirimicarb on Daphnia magna in a laboratory freshwater/sediment system

    DEFF Research Database (Denmark)

    Kusk, K.O.

    1996-01-01

    In tests with newborn and one-week-old Daphnia magna, 48-h EC(50) values of 21-24 mu g/L and 16 mu g/L pirimicarb, respectively, were found. Older animals thus were as sensitive to pirimicarb as newborn animals. In an experiment with sediment included in the test system, all mother animals survived...... not reduced significantly during the experiment, due to the small amount of sediment used. Accumulation in the sediment was found independent of the water concentration used. This was also the case with bioaccumulation in Daphnia magna, where a bioaccumulation factor of 31-37 was found on a dry weight basis...

  15. Phosphorus transformations at the sediment-water interface in shallow freshwater ecosystems caused by decomposition of plant debris.

    Science.gov (United States)

    Zhang, Wenqiang; Jin, Xin; Meng, Xin; Tang, Wenzhong; Shan, Baoqing

    2018-03-03

    We studied the processes and mechanisms that drove phosphorus (P) release and transformations at the sediment-water interface (SWI) because of the decomposition of plant debris. The results showed that, as the simulation time increased, the pH, dissolved oxygen (DO), and oxidation reduction potential (ORP) in Duckweed+Sediment+Water (DWS) and Duckweed+Water (DW) initially decreased and then increased before stabilizing. Changes in the physicochemical characteristics affect the microhabitat and the release and transformations of P at the SWI. The initial flux of total P (TP), total dissolved phosphorus (TDP), and soluble reactive phosphorus (SRP) was 886, 515, and 441 mg m -2 d -1 in DWS and 626, 376, and 330 mg m -2 d -1 in DW, respectively. As the plant debris decomposed, the fluxes of TP, TDP, and SRP decreased, and after 11 days, the fluxes remained at around 0 mg m -2 d -1 . The dissolved organic phosphorus (DOP) flux followed different trends in DWS and DW, and increased first to a maximum of 285 and 109 mg m -2 d -1 , respectively, by day 6. The results of this study indicate that plant debris decomposition drive P transformations at the SWI in shallow freshwater ecosystems. Therefore, to control internal sources and transformations of P, plant debris should be removed and harvested. This study also indicates that intervention is needed to ensure the health of freshwater ecosystems, and we cannot hope to get satisfactory results from only improving the national wastewater discharge standards. Copyright © 2018. Published by Elsevier Ltd.

  16. Interlaboratory study of precision: Hyalella azteca and Chironomus tentans freshwater sediment toxicity assays

    Science.gov (United States)

    Burton, G.A.; Norberg-King, T. J.; Ingersoll, C.G.; Benoit, D.A.; Ankley, G.T.; Winger, P.V.; Kubitz, J.; Lazorchak, J.M.; Smith, M.E.; Greer, E.; Dwyer, F.J.; Call, D.J.; Day, K.E.; Kennedy, P.; Stinson, M.

    1996-01-01

    Standard 10-d whole-sediment toxicity test methods have recently been developed by the U.S. Environmental Protection Agency (EPA) for the amphipod Hyalella azteca and the midge Chironomus tentans. An interlaboratory evaluation of method precision was performed using a group of seven to 10 laboratories, representing government, academia, and environmental consulting firms. The test methods followed the EPA protocols for 4-d water-only reference toxicant (KCl) testing (static exposure) and for 10-d whole-sediment testing. Test sediments included control sediment, two copper-containing sediments, and a sediment contaminated primarily with polycyclic aromatic hydrocarbons. Reference toxicant tests resulted in H. azteca and C. tentans median lethal concentration (LC50) values with coefficents of variation (CVs) of 15.8 and 19.6%, respectively. Whole sediments which were moderately contaminated provided the best estimates of precision using CVs. Hyalella azteca and C. tentans tests in moderately contaminated sediments exhibited LC50 CVs of 38.9 and 13.5%, respectively. The CV for C. tentans growth was 31.9%. Only 3% (1 of 28) of samples exceeded acceptable interlaboratory precision limits for the H. azteca survival tests. No samples exceeded the intralaboratory precision limit for H. azteca or C. tentans survival tests. However, intralaboratory variability limits for C. tentans growth were exceeded by 80 and 100% of the laboratories for a moderately toxic and control sample, respectively. Interlaboratory variability limits for C. tentans survival were not exceeded by any laboratory. The results showed these test methods to have relatively low variance and acceptable levels of precision in interlaboratory comparisons.

  17. Different partition of polycyclic aromatic hydrocarbon on environmental particulates in freshwater: Microplastics in comparison to natural sediment.

    Science.gov (United States)

    Wang, Wenfeng; Wang, Jun

    2018-01-01

    Microplastics pollution in the aquatic ecosystems has aroused increasing concerns in recent years. Though microplastics are known to sorb organic contaminants from water, the interaction mechanisms between microplastics and organic chemicals are not yet well understood. Here we investigated the partition characteristics of phenanthrene (Phe) in three mass-produced plastic particles, including polyethylene (PE), polystyrene (PS) and polyvinylchloride (PVC), and one natural sediment, as a comparison. The sorption kinetics of Phe onto microplastics and natural sediment were successfully described by the pseudo-second-order model (R 2 > 0.992), while the equilibrium data were best-fitted to the Langmuir isotherm (R 2 > 0.995). Compared with natural sediment, microplastics exhibited higher capacities for Phe which followed an order of PE > PS > PVC. As the aqueous concentration of pyrene (Pyr) increased, both uptakes and distribution coefficients (K d ) of Phe within the solids decreased, with natural sediment giving the largest decline. Although proportions of Phe desorbed from the contaminated microplastics were low, due to the high Phe uptake, microplastics released larger amounts of the sorbed Phe to water than the natural sediment during the desorption process. Given their minimal abundance relative to natural sediment, microplastics may play a less important role in the transport of organic pollutants in a natural aquatic environment. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. The influence of six pharmaceuticals on freshwater sediment microbial growth incubated at different temperatures and UV exposures.

    Science.gov (United States)

    Veach, Allison; Bernot, Melody J; Mitchell, James K

    2012-07-01

    Pharmaceutical compounds have been detected in freshwater for several decades. Once they enter the aquatic ecosystem, they may be transformed abiotically (i.e., photolysis) or biotically (i.e., microbial activity). To assess the influence of pharmaceuticals on microbial growth, basal salt media amended with seven pharmaceutical treatments (acetaminophen, caffeine, carbamazepine, cotinine, ibuprofen, sulfamethoxazole, and a no pharmaceutical control) were inoculated with stream sediment. The seven pharmaceutical treatments were then placed in five different culture environments that included both temperature treatments of 4, 25, 37°C and light treatments of continuous UV-A or UV-B exposure. Microbial growth in the basal salt media was quantified as absorbance (OD(550)) at 7, 14, 21, 31, and 48d following inoculation. Microbial growth was significantly influenced by pharmaceutical treatments (P < 0.01) and incubation treatments (P < 0.01). Colonial morphology of the microbial communities post-incubation identified selection of microbial and fungal species with exposure to caffeine, cotinine, and ibuprofen at 37°C; acetaminophen, caffeine, and cotinine at 25°C; and carbamazepine exposed to continuous UV-A. Bacillus and coccus cellular arrangements (1000X magnification) were consistently observed across incubation treatments for each pharmaceutical treatment although carbamazepine and ibuprofen exposures incubated at 25°C also selected spiral-shaped bacteria. These data indicate stream sediment microbial communities are influenced by pharmaceuticals though physiochemical characteristics of the environment may dictate microbial response.

  19. Coupling geochemical and biological approaches to assess the availability of cadmium in freshwater sediment

    Energy Technology Data Exchange (ETDEWEB)

    Dabrin, Aymeric, E-mail: aymeric.dabrin@cemagref.fr; Durand, Cyrielle L.; Garric, Jeanne; Geffard, Olivier; Ferrari, Benoit J.D.; Coquery, Marina

    2012-05-01

    Sediments are considered as a sink for metals, and the assessment of metal bioavailability for benthic organisms represents a great challenge. Diffusive Gradient in Thin films (DGT), developed to measure labile metals in aquatic media, have more recently been applied to sediment. Nevertheless, few studies have determined the relation between measurements from DGT and bioaccumulation in different benthic organisms. The aim of our work was to determine if labile metal measured by DGT in sediment is representative of bioavailable metal for benthic organisms. We focused our work on Cd and chose to use the diversity of ecological traits from different organisms to better understand the measurement given by DGT. We exposed simultaneously DGT and 3 macroinvertebrates species (the chironomid, Chironomus riparius; the amphipod, Gammarus fossarum; the mudsnail, Potamopyrgus antipodarum) to a natural sediment Cd-spiked at environmental relevant concentrations. The nature of sediment-bound Cd was also determined by means of sequential extractions in order to better interpret DGT measurements. Cadmium concentrations were determined in DGT and in the 3 organisms after one week of exposure. Results provided by DGT indicated that Cd was poorly released from particulate phase to pore water, suggesting that Cd measured by DGT was representative of the pore water labile fraction. Sequential extractions showed that the percentage of Cd bound to carbonate fraction increased simultaneously with Cd-spiking level; hence, this Cd fraction was poorly reactive to supply DGT demand. Cadmium accumulation rates were similar between DGT measurements and P. antipodarum, suggesting that labile Cd in pore waters was representative of bioavailable Cd for this species. Cadmium accumulation rates in C. riparius were higher than in DGT, demonstrating that C. riparius can mobilize Cd bound to carbonate phase. G. fossarum showed the lowest Cd accumulation rates, suggesting that they were mainly exposed

  20. Contamination of Omnivorous Freshwater Fish Species and Sediments by Chlorinated Hydrocarbons in Poland

    Directory of Open Access Journals (Sweden)

    Niewiadowska Alicja

    2014-10-01

    Full Text Available The occurrence and concentrations of organochlorine pesticides and polychlorinated biphenyls (PCBs were determined in 158 muscle samples of bream (Abramis brama and roach (Rutilus rutilus, and 84 samples of sediments collected from 10 river and lake sampling sites in 2011 and 2012. The concentrations of DDTs (p,p’-DDT, o,p’-DDT, p,p’-DDE, and p,p’-DDD, HCH isomers (a-, ß-, and y-HCH, HCB, and PCBs (six indicator PCB congeners 28, 52, 101, 138, 153 and 180 were determined using the capillary gas chromatography. The mean concentrations of DDTs in bream and roach were in the range of 11.2-654 and 4.5-121 ug/kg wet weight respectively, and PCBs were in the range of 1.3-75.9 and 1.1-112 ug/kg wet weight, respectively. Mean concentrations of DDTs and PCBs in sediments were 0.5-270 ug/kg dry weight and ⋋0.1-2.2 ug/kg dry weight respectively. The study showed clear spatial differences in the levels of organochlorine pesticides and PCBs in fish and sediments from different aquatic ecosystems. The highest levels of contaminants were detected in fish and sediments from the Vistula River in vicinity of Cracow. The possible risk to the fish meat consumers and ecological risk were evaluated.

  1. Functional Repertoire of Antibiotic Resistance Genes in Antibiotic Manufacturing Effluents and Receiving Freshwater Sediments

    Science.gov (United States)

    González-Plaza, Juan J.; Šimatović, Ana; Milaković, Milena; Bielen, Ana; Wichmann, Fabienne; Udiković-Kolić, Nikolina

    2018-01-01

    Environments polluted by direct discharges of effluents from antibiotic manufacturing are important reservoirs for antibiotic resistance genes (ARGs), which could potentially be transferred to human pathogens. However, our knowledge about the identity and diversity of ARGs in such polluted environments remains limited. We applied functional metagenomics to explore the resistome of two Croatian antibiotic manufacturing effluents and sediments collected upstream of and at the effluent discharge sites. Metagenomic libraries built from an azithromycin-production site were screened for resistance to macrolide antibiotics, whereas the libraries from a site producing veterinary antibiotics were screened for resistance to sulfonamides, tetracyclines, trimethoprim, and beta-lactams. Functional analysis of eight libraries identified a total of 82 unique, often clinically relevant ARGs, which were frequently found in clusters and flanked by mobile genetic elements. The majority of macrolide resistance genes identified from matrices exposed to high levels of macrolides were similar to known genes encoding ribosomal protection proteins, macrolide phosphotransferases, and transporters. Potentially novel macrolide resistance genes included one most similar to a 23S rRNA methyltransferase from Clostridium and another, derived from upstream unpolluted sediment, to a GTPase HflX from Emergencia. In libraries deriving from sediments exposed to lower levels of veterinary antibiotics, we found 8 potentially novel ARGs, including dihydrofolate reductases and beta-lactamases from classes A, B, and D. In addition, we detected 7 potentially novel ARGs in upstream sediment, including thymidylate synthases, dihydrofolate reductases, and class D beta-lactamase. Taken together, in addition to finding known gene types, we report the discovery of novel and diverse ARGs in antibiotic-polluted industrial effluents and sediments, providing a qualitative basis for monitoring the dispersal of ARGs

  2. Development of whole-sediment toxicity identification and evaluation (TIE) techniques for two Australian freshwater species: Chironomus tepperi and Austrochiltonia subtenuis.

    Science.gov (United States)

    Mehler, W Tyler; Keough, Michael J; Pettigrove, Vincent

    2017-09-01

    Most of the public literature and available guidance documents on the conduct of freshwater whole-sediment toxicity identification and evaluations (TIEs) detail the use of test organisms and amending agents that are readily available in North America. These commonly used test organisms and the supported amending agents, however, are not available and largely inappropriate (i.e., not native species) for conducting whole-sediment TIEs outside of North America. The overall objective of the present study was to build foundational methods for performing freshwater whole-sediment TIEs in Australia. We examined the capability of 3 amending agents: ANZ38 Zeolite (for ammonia; Castle Mountain Zeolites), Oxpure 325B-9 Activated Carbon (for nonpolar organics; Oxbow Activated Carbon), and Lewatit MonoPlus TP 207 (for cationic metals; Lanxess Deutschland) on 2 Australian native freshwater species: the midge Chironomus tepperi and the amphipod Austrochiltonia subtenuis. To evaluate the effectiveness of each amendment, bioassays were conducted with spiked sediments of ammonia, permethrin (as part of a commercial formulation), and copper using acute median lethal concentrations (LC50s) for both species and growth median effect concentration (EC50) of midges as the endpoints of interest. Environ Toxicol Chem 2017;36:2476-2484. © 2017 SETAC. © 2017 SETAC.

  3. Microcosm and Experimental Pond Evaluation of Microbial Community Response to Synthetic Oil Contamination in Freshwater Sediments

    OpenAIRE

    Sayler, G. S.; Perkins, R. E.; Sherrill, T. W.; Perkins, B. K.; Reid, M. C.; Shields, M. S.; Kong, H. L.; Davis, J. W.

    1983-01-01

    A multivariate approach was used to evaluate the significance of synthetic oil-induced perturbations in the functional activity of sediment microbial communities. Total viable cell densities, ATP-biomass, alkaline phosphatase and dehydrogenase activity, and mineralization rates of glucose, protein, oleic acid, starch, naphthalene, and phenanthrene were monitored on a periodic basis in microcosms and experimental ponds for 11 months, both before and after exposure to synthetic oil. All variabl...

  4. Toxicity assessment of reference and natural freshwater sediments with the luminotox assay

    CSIR Research Space (South Africa)

    Dellamatrice, PM

    2006-08-01

    Full Text Available reading tube. The light output of all tubes (sediment-exposed and controls) is measured with a photo- meter, after which inhibition percentages can be calculated. 396 DELLAMATRICE ET AL. Environmental Toxicology DOI 10.1002/tox The determined endpoint... photosynthetic enzyme complexes (PECs), iso- lated from spinach plant extracts. When PECs are chal- lenged with chemicals or complex samples that can inter- fere with transmission of chlorophyll fluorescence linked to Photosystems I and II reaction sites, a...

  5. Contemporary deposition and long-term accumulation of sediment and nutrients by tidal freshwater forested wetlands impacted by sea level rise

    Science.gov (United States)

    Noe, Gregory; Hupp, Cliff R.; Bernhardt, Christopher E.; Krauss, Ken W.

    2016-01-01

    Contemporary deposition (artificial marker horizon, 3.5 years) and long-term accumulation rates (210Pb profiles, ~150 years) of sediment and associated carbon (C), nitrogen (N), and phosphorus (P) were measured in wetlands along the tidal Savannah and Waccamaw rivers in the southeastern USA. Four sites along each river spanned an upstream-to-downstream salinification gradient, from upriver tidal freshwater forested wetland (TFFW), through moderately and highly salt-impacted forested wetlands, to oligohaline marsh downriver. Contemporary deposition rates (sediment, C, N, and P) were greatest in oligohaline marsh and lowest in TFFW along both rivers. Greater rates of deposition in oligohaline and salt-stressed forested wetlands were associated with a shift to greater clay and metal content that is likely associated with a change from low availability of watershed-derived sediment to TFFW and to greater availability of a coastal sediment source to oligohaline wetlands. Long-term accumulation rates along the Waccamaw River had the opposite spatial pattern compared to contemporary deposition, with greater rates in TFFW that declined to oligohaline marsh. Long-term sediment and elemental mass accumulation rates also were 3–9× lower than contemporary deposition rates. In comparison to other studies, sediment and associated nutrient accumulation in TFFW are lower than downriver/estuarine freshwater, oligohaline, and salt marshes, suggesting a reduced capacity for surface sedimentation (short-term) as well as shallow soil processes (long-term sedimentation) to offset sea level rise in TFFW. Nonetheless, their potentially large spatial extent suggests that TFFW have a large impact on the transport and fate of sediment and nutrients in tidal rivers and estuaries.

  6. Heavy metal profile of water, sediment and freshwater cat fish, Chrysichthys nigrodigitatus (Siluriformes: Bagridae, of Cross River, Nigeria

    Directory of Open Access Journals (Sweden)

    Ezekiel Olatunji Ayotunde

    2012-09-01

    Full Text Available Cross River serves as a major source of drinking water, transportation, agricultural activities and fishing in Cross River State, Nigeria. Since there is no formal control of effluents discharged into the river, it is important to monitor the levels of metals contaminants in it, thus assessing its suitability for domestic and agricultural use. In order to determine this, three sampling stations designated as Ikom (Station I, Obubra Ogada (Station II and Calabar (Station III were randomly selected to study. For this, ten samples of the freshwater Silver Catfish (Chryshchythys nigrogitatus (29.4-39.5cm SL, 310-510g, sediment and water were collected from each sampling Station from June 2009-June 2010. The heavy metals profiles of Zn, Cu, Fe, Co, Pb, Cd and Cr, in water, sediments and fish muscle were analyzed by atomic absorption spectrophotometry (AAS. In fish, the heavy metals concentration was found to be Cu>Fe>Zn>Cu>Pb>Cd>Co; the highest mean concentration of Copper (0.297±0.022 μg/g, Cadmium (0.011±0.007μg/g, Iron (0.371±0.489μg/g, Lead (0.008±0.008μg/g, were determined for the fish. In water, the order was found to be Fe>Pb>Zn>Cu>Cr>Cd>Co; the highest mean concentration of Iron (0.009±0.00μg/g, Copper (0.015±0.01 μg/g, Lead (0.0002±0.00μg/g Cadmium (0.0006±0.001μg/g, Zinc (0.0036±0.003μg/g, were observed in the surface water, respectively. The highest mean concentration of Copper (0.037±0.03μg/g, Iron (0.053±0.04μg/g, Lead (0.0002±0.00μg/g, Cobalt (0.0002±0.00μg/g, Cadmium (0.0006±0.001μg/g and Zinc (.009±0.0015μg/g was observed in the bottom water. In sediments, the concentration order found was Zn>Fe>Cu>Pb>Co>Cd; the highest mean concentration of 0.057±0.04μg/g, 0.043±0.03μg/g, 0.0006±0.00μg/g, 0.0002±0.00μg/g, 0.0009±0.00μg/g, 0.099±0.00404μg/g in Iron, Copper, Lead, Cobalt, Cadmium and Zinc were observed in the sediment, respectively; Chromium was not detected in the sediment for the whole

  7. Ecotoxicological assessment of the pharmaceutical compound Triclosan to freshwater invertebrates with emphasis to spiked sediment tests

    International Nuclear Information System (INIS)

    Pusceddu, Fabio Hermes

    2009-01-01

    The increasing of Pharmaceutical and Personal Care Products (PPCPs) occurrence in the aquatic environment cause adverse effects on the human health and aquatic communities. The environmental risk of the PPCPs associated with the possibility of synergic effects between PCPPs and the increase of the use of synthetic organic compounds, unchained a great concern on the toxic potential to biota aquatic. Triclosan (5-chloro-2-(2,4-dichlorophenoxy)-phenol) is a pharmaceutical compound widely used due your antibacterial mechanism effect, found in at least 932 products such as shampoos, toilet soaps, deodorants, lotions, toothpaste, detergents, socks and underwear, among others. Currently, studies about the Triclosan toxicity in the water and, mainly in the sediment, are poorly. We have the knowledge that the photodegradation of this product results into dichlorodibenzo-p-dioxin, and now it has great discussion on environmental agencies, like EPA, about the release or restriction of this product. The aim of this work is to assess the effects of Triclosan on mortality of insect larvae Chironomus xanthus and mortality and reproduction inhibition of microcrustacea Ceriodaphnia dubia exposed to Triclosan spiked sediments based on standard methods EPA and OECD. The EC50;96H obtained on acute toxicity tests with C. xanthus was 45,26 mg.Kg -1 . The chronic toxicity tests with C. dubia using spiked sediments were performed following the procedure in Burton and MacPherson (1995). A no-observed-effect concentrations and lowest-observed-effect concentration were 5,78 e 6,94 mg.Kg -1 , respectively. (author)

  8. Sedimentation Patterns of Toxin-Producing Microcystis Morphospecies in Freshwater Reservoirs

    Directory of Open Access Journals (Sweden)

    Antonio Quesada

    2013-05-01

    Full Text Available Understanding the annual cycle of Microcystis is essential for managing the blooms of this toxic cyanobacterium. The current work investigated the sedimentation of microcystin-producing Microcystis spp. in three reservoirs from Central Spain during the summer and autumn of 2006 and 2007. We confirmed remarkable settling fluxes during and after blooms ranging 106–109 cells m−2 d−1, which might represent 0.1%–7.6% of the organic matter settled. A comprehensive analysis of the Valmayor reservoir showed average Microcystis settling rates (0.04 d−1 and velocities (0.7 m d−1 that resembled toxin settling in the same reservoir and were above most reported elsewhere. M. aeruginosa settling rate was significantly higher than that of M. novacekii and M. flos-aquae. Despite the fact that colony sizes did not differ significantly in their average settling rates, we observed extremely high and low rates in large colonies (>5000 cells and a greater influence of a drop in temperature on small colonies (<1000 cells. We found a 4–14 fold decrease in microcystin cell quota in settling Microcystis of the Cogotas and Valmayor reservoirs compared with pelagic populations, and the hypothetical causes of this are discussed. Our study provides novel data on Microcystis settling patterns in Mediterranean Europe and highlights the need for including morphological, chemotypical and physiological criteria to address the sedimentation of complex Microcystis populations.

  9. Batch Sedimentation Studies for Freshwater Green Alga Scenedesmus abundans Using Combination of Flocculants

    Directory of Open Access Journals (Sweden)

    Raghu K. Moorthy

    2017-06-01

    Full Text Available Microalga is the only feedstock that has the theoretical potential to completely replace the energy requirements derived from fossil fuels. However, commercialization of this potential source for fuel applications is hampered due to many technical challenges with harvesting of biomass being the most energy intensive process among them. The fresh water microalgal species, Scenedesmus abundans, has been widely recognized as a potential feedstock for production of biodiesel (Mandotra et al., 2014. The present work deals with sedimentation of algal biomass using extracted chitosan and natural bentonite clay powder as flocculant. The effect of flocculant combination and different factors such as temperature, pH, and concentration of algal biomass on sedimentation rates has been analyzed. A high flocculation efficiency of 76.22 ± 7.81% was obtained at an algal biomass concentration of 1 ± 0.05 g/L for a settling time of 1 h at 50 ± 5°C with a settling velocity of 103.2 ± 0.6 cm/h and a maximum surface conductivity of 2,260 ± 2 μS/cm using an optimal design in response surface methodology (RSM. Biopolymer flocculant such as chitosan exhibited better adsorption property along with bentonite clay powder that reduced the settling time significantly.

  10. Batch sedimentation studies for freshwater green alga Scenedesmus abundans using combination of flocculants

    Science.gov (United States)

    Moorthy, Raghu K.; Premalatha, M.; Arumugam, Muthu

    2017-06-01

    Microalga is the only feedstock that has the theoretical potential to completely replace the energy requirements derived from fossil fuels. However, commercialization of this potential source for fuel applications is hampered due to many technical challenges with harvesting of biomass being the most energy intensive process among them. The fresh water microalgal species, Scenedesmus abundans, has been widely recognized as a potential feedstock for production of biodiesel (Mandotra et al., 2014). The present work deals with sedimentation of algal biomass using extracted chitosan and natural bentonite clay powder as flocculant. The effect of flocculant combination and different factors such as temperature, pH and concentration of algal biomass on sedimentation rates has been analyzed. A high flocculation efficiency of 76.22 + 7.81% was obtained at an algal biomass concentration of 1 + 0.05 g/L for a settling time of 1 hour at 50 + 5oC with a settling velocity of 103.2 + 0.6 cm/h and a maximum surface conductivity of 2260 + 2 µS/cm using an optimal design in response surface methodology (RSM). Biopolymer flocculant such as chitosan exhibited better adsorption property along with bentonite clay powder that reduced the settling time significantly.

  11. Effect of Lake Trophic Status and Rooted Macrophytes on Community Composition and Abundance of Ammonia-oxidizing Prokaryotes in Freshwater Sediments

    DEFF Research Database (Denmark)

    Herrmann, Martina; Saunders, Aaron Marc; Schramm, Andreas

    2009-01-01

    /N ratios. AOA communities could be grouped according to lake trophic status and pH; plant species-specific communities were not detected, and no grouping was apparent for AOB communities. Relative abundance, determined by quantitative PCR targeting amoA, was always low for AOB (...) and slightly higher for AOA in unvegetated sediment and AOA in association with M. alterniflorum (0.01 to 2%), while AOA accounted for up to 5% in the rhizospheres of L. uniflora and J. bulbosus. These results indicate that (i) AOA are at least as numerous as AOB in freshwater sediments, (ii) aquatic...

  12. Effect of submerged, freshwater aquatic macrophytes and littoral sediments on pan evaporation in the Lake Balaton region, Hungary

    Science.gov (United States)

    Anda, A.; Simon, B.; Soos, G.; Teixeira da Silva, J. A.; Kucserka, T.

    2016-11-01

    The evaporation (Ep) of a US Class A pan (C) with submerged, freshwater aquatic macrophytes (Potamogeton perfoliatus, Myriophyllum spicatum and Najas marina), hereafter macrophytes (Ps) and a sediment-covered bottom (S) was measured in Hungary during 2014-2015 using reference E of Shuttleworth (Eo) and Penman-Monteith crop reference evapotranspiration (crop ETo). There were two main climatic controls affecting variation in E: direct (air and water temperature) and indirect (wind-mediated change affecting the penetration of sunlight; precipitation inflow, impacting plant emergence). Lower seasonal mean Ep rates of 2.75 ± 0.89, 2.83 ± 0.91 and 3.06 ± 1.14 mm day-1 were observed in C, S and Ps, respectively, during the wet 2014. In the 2015 season, higher overall daily mean Ep rates for C, S and Ps were 3.76 ± 1.3, 4.19 ± 1.34 and 4.65 ± 1.52 mm day-1, respectively. A comparison of US Class A pan Ep containing macrophytes/sediments with that of a standard US Class A pan showed that pan coefficients (Kap and Kas) might allow for more accurate on-site lake E estimates. In 2014, seasonal mean Kas and Kap were 1.04 ± 0.14 and 1.09 ± 0.18, respectively. Slightly higher Ka values were observed during the warm and dry 2015 (Kas: 1.15 ± 0.22; Kap: 1.26 ± 0.23). A Ka value greater than 1 indicates that the Ep of a US Class A pan containing macrophytes and sediment is always higher than that of C. The calculated Eo overestimated measured Ep of Ps during the course of this study. During the warm-dry growing season, crop ETo was closest to Ep of Ps. Empirical coefficients can be useful for estimating E of lakes with submerged macrophytes more precisely. The accuracy of the estimate of Keszthely Bay's E improved by 9.85% when Ka was determined on site.

  13. Phytoplankton succession in a tropical freshwater lake, Bhoj Wetland (Bhopal, India): spatial and temporal perspective.

    Science.gov (United States)

    Ahmed, Ayaz; Wanganeo, Ashwani

    2015-04-01

    Bhoj Wetland is tropical freshwater system in central India "Bhopal" serving the citizens as one of the major source of water since its inception. Understanding the process of phytoplankton variation can be particularly useful in water quality improvement and management decision. In this study, phytoplankton taxonomic composition, temporal and spatial distribution, and diversity along with limnological abiotic characteristics were studied based on monthly sampling from four sampling stations (between May 2005 and April 2006). A total of 4 classes, 68 genera, and 98 species which belong to Chlorophyceae (52 species), Cyanobacteria (24 species), Bacillariophyceae (19 species), and Euglenophyceae (3 species), respectively, were identified. Phytoplankton assemblages were dominated by Cyanobacteria during summer months and were the most abundant. On an annual average scale, the phytoplankton density varied between 0.24×10(4) units/l at station 4 to 0.46×10(4) units/l at station 2, and station 2 represented highest population density. The predominant indices of the most predominant species varied between 0.03 and 0.26. Among physicochemical variables, temperature and total dissolved solids played a key role in phytoplankton growth as represented by statistical linear regression drawn between temperature, total dissolved solids, nitrate, and phytoplankton with R2 values of 0.6, 0.46, and 0.5, respectively.

  14. Microbial communities in marine sediments modify success of an invasive macrophyte.

    Science.gov (United States)

    Gribben, Paul E; Nielsen, Shaun; Seymour, Justin R; Bradley, Daniel J; West, Matthew N; Thomas, Torsten

    2017-08-29

    Invasive plants have extensive impacts on ecosystem function and biodiversity globally. Our inability to manage invasive species stems in part from a lack of understanding of the processes that control their successful establishment and spread. To date, studies have largely considered how above-ground processes control native/invasive plant interactions. Emerging research from terrestrial and wetland ecosystems demonstrates that below-ground processes under microbial control can determine the outcome of interactions between native and invasive plants. Whether sediment microbes modify the success of invasive macrophytes in marine ecosystems is untested, despite marine sediment microbes controlling many ecological processes (e.g. nutrient cycling) comparable to those in terrestrial ecosystems. We first show that sediment bacterial communities differ between the native seagrass Zostera capricorni and the invasive alga Caulerpa taxifolia and that those differences relate to functional changes in sulfur cycling between the macrophytes. Second, by experimentally manipulating the microbial communities we show that intact microbial communities in Z. capricorni sediments provide biotic resistance by reducing C. taxifolia fragment growth 119% compared to when they are inactive, and intact microbial communities in C. taxifolia sediments have positive feedbacks by increasing fragment growth 200%. Thus, similar to terrestrial ecosystems, microorganisms appear to indirectly control the success of invasive macrophytes in marine ecosystems.

  15. Development of a Long-term Sampling Network to Monitor Restoration Success in the Southwest Coastal Everglades: Vegetation, Hydrology, and Sediments

    Science.gov (United States)

    Smith, Thomas J.

    2004-01-01

    Fig. 3) allow us to track the interaction of hydrology, sediment, and vegetation over time, and will provide the opportunity to monitor the progress of the Everglades restoration and to gauge its success. Our earlier research questions have been modified over time to place a major emphasis on CERP needs, while still recognizing the importance of other processes, including disturbance and sea-level rise. Our research addresses processes relevant to the following restoration and related questions: * How will increasing freshwater flow affect wetland primary production? * Will increasing freshwater inflow alter nutrient availability? * Does recovery following disturbance in mangroves depend on freshwater inflow? * Will the position of vegetation ecotones change in response to upstream water management? * What will be the influence of global climate change, such as sea-level rise, on the Everglades restoration? * Will processes of wetlands soil formation be altered by sea-level rise and changed freshwater inflow?

  16. Avoidance of polycyclic aromatic hydrocarbon-contaminated sediments by the freshwater invertebrates Gammarus pulex and Asellus aquaticus

    NARCIS (Netherlands)

    Lange, de H.J.; Sperber, V.; Peeters, E.T.H.M.

    2006-01-01

    Contamination of sediments is a serious problem in most industrialized areas. Sediments are often contaminated with trace metals and organic contaminants like polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Bioassays are often used to determine the effect of

  17. Methymercury Formation in Marine and Freshwater Systems: Sediment Characteristics, Microbial Activity and SRB Phylogeny Control Formation Rates and Food-Chain Exposure

    Science.gov (United States)

    King, J. K.; Saunders, F. M.

    2004-05-01

    Mercury research in freshwater and marine systems suggests that sediment characteristics such as organic substrate, mercury speciation, and sulfate/sulfide concentrations influence availability of inorganic mercury for methylation. Similarly, sediment characteristics also influence sulfate-reducing bacterial (SRB) respiration as well as the presence/distribution of phylogenetic groups responsible for mercury methylation. Our work illustrates that the process of methylmercury formation in freshwater and marine systems are not dissimilar. Rather, the same geochemical parameters and SRB phylogenetic groups determine the propensity for methylmercury formation and are applicable in both fresh- and marine-water systems. The presentation will include our integration of sediment geochemical and microbial parameters affecting mercury methylation in specific freshwater and marine systems. Constructed wetlands planted with Schoenoplectus californicus and amended with gypsum (CaSO4) have demonstrated a capacity to remove inorganic mercury from industrial outfalls. However, bioaccumulation studies of periphyton, eastern mosquitofish (Gambusia holbrooki) and lake chubsucker (Erimyzon sucetta) were conducted in order to ascertain the availability of wetland-generated methylmercury to biota. Total mercury concentrations in mosquitofish from non-sulfate treated controls and the reference location were significantly lower than those from the low and high sulfate treatments while mean total mercury concentrations in lake chubsuckers were also significantly elevated in the high sulfate treatment compared to the low sulfate, control and reference populations. Methylmercury concentrations in periphyton also corresponded with mercury levels found in the tissue of the lake chubsuckers, and these findings fit well given the trophic levels identified for both species of fish. Overall, data from this study suggest that the initial use of gypsum to accelerate the maturity of a constructed

  18. Initial study of arthropods succession and pig carrion decomposition in two freshwater ecosystems in the Colombian Andes.

    Science.gov (United States)

    Barrios, Maria; Wolff, Marta

    2011-10-10

    Entomological succession and trophic roles of arthropods associated with different stages of carcass decomposition were studied to estimate the post-mortem submersion interval in two freshwater ecosystems in the Colombian Andes, at an altitude of 2614 m. Pig carcasses were employed as models placed 68 m apart, one in a stream (lotic) and another in an artificial lake (lentic). Decomposition time to skeletal remains was 74 days in the lake and 80 days in the stream. Six phases of decomposition were established: submerged fresh, early floating, floating decay, bloated deterioration, floating remains and sunken remains. A total of 18,832 organisms associated with the carcasses were collected: 11,487 in the lake (four orders, 19 families and 33 species) and 7345 in the stream (eight orders, 15 families and 25 species). Organisms were classified in the following ecological categories: shredders, collectors, predators, necrophagous, sarcosaprophagous and opportunists. Physical and chemical properties of the habitats, such as water temperature, CO(2) and conductivity, varied according to rainfall. In the lake, shredders (Coleoptera: Tropisternus sp. and Berosus sp.) and collectors (Diptera: Chironomus sp.) were found to be associated with submerged phases. Predators (Odonata) were only present during the first phases. Coleoptera (Dytiscidae) were found during floating decay and bloated deterioration stages. In the stream, shredders (Hyalella sp.) and collectors (Simulium sp.) were found during all stages, whereas the predator Oxelytrum discicolle was found exclusively during the floating stages, during which body temperature increased in a fashion similar to active decay in terrestrial environments. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  19. Heavy metal profile of water, sediment and freshwater cat fish, Chrysichthys nigrodigitatus (Siluriformes: Bagridae, of Cross River, Nigeria

    Directory of Open Access Journals (Sweden)

    Ezekiel Olatunji Ayotunde

    2012-09-01

    Full Text Available Cross River serves as a major source of drinking water, transportation, agricultural activities and fishing in Cross River State, Nigeria. Since there is no formal control of effluents discharged into the river, it is important to monitor the levels of metals contaminants in it, thus assessing its suitability for domestic and agricultural use. In order to determine this, three sampling stations designated as Ikom (Station I, Obubra Ogada (Station II and Calabar (Station III were randomly selected to study. For this, ten samples of the freshwater Silver Catfish (Chryshchythys nigrogitatus (29.4-39.5cm SL, 310-510g, sediment and water were collected from each sampling Station from June 2009-June 2010. The heavy metals profiles of Zn, Cu, Fe, Co, Pb, Cd and Cr, in water, sediments and fish muscle were analyzed by atomic absorption spectrophotometry (AAS. In fish, the heavy metals concentration was found to be Cu>Fe>Zn>Cu>Pb>Cd>Co; the highest mean concentration of Copper (0.297±0.022 μg/g, Cadmium (0.011±0.007μg/g, Iron (0.371±0.489μg/g, Lead (0.008±0.008μg/g, were determined for the fish. In water, the order was found to be Fe>Pb>Zn>Cu>Cr>Cd>Co; the highest mean concentration of Iron (0.009±0.00μg/g, Copper (0.015±0.01 μg/g, Lead (0.0002±0.00μg/g Cadmium (0.0006±0.001μg/g, Zinc (0.0036±0.003μg/g, were observed in the surface water, respectively. The highest mean concentration of Copper (0.037±0.03μg/g, Iron (0.053±0.04μg/g, Lead (0.0002±0.00μg/g, Cobalt (0.0002±0.00μg/g, Cadmium (0.0006±0.001μg/g and Zinc (.009±0.0015μg/g was observed in the bottom water. In sediments, the concentration order found was Zn>Fe>Cu>Pb>Co>Cd; the highest mean concentration of 0.057±0.04μg/g, 0.043±0.03μg/g, 0.0006±0.00μg/g, 0.0002±0.00μg/g, 0.0009±0.00μg/g, 0.099±0.00404μg/g in Iron, Copper, Lead, Cobalt, Cadmium and Zinc were observed in the sediment, respectively; Chromium was not detected in the sediment for the whole

  20. Lead accumulation (adsorption and absorption) by the freshwater bivalve Corbicula fluminea in sediments contaminated by TiO2nanoparticles.

    Science.gov (United States)

    Fan, Xiulei; Wang, Peifang; Wang, Chao; Hu, Bin; Wang, Xun

    2017-12-01

    With the increasing production and applications of TiO 2 nanoparticles (NPs), their presence in aquatic environments, especially in sediments, will inevitably increase over time. Most studies investigating the influence of TiO 2 NPs on the bioaccumulation of co-existing contaminants have focused on the aqueous phase; however, few have examined the sediment phase, which contains more TiO 2 NPs and contaminants. We investigated the effects of TiO 2 NPs on Pb accumulation by Corbicula fluminea in sediments, and explored extracellular and intracellular Pb concentrations in the various soft tissues of the bivalve. Pb was spiked with 50 mg/kg in sediment and TiO 2 NPs/sediments ratios were within the range 0.2-3.0%. The results showed that TiO 2 NPs presented larger adsorption capacity and affinity to Pb ions than the sediments. In addition, the large adsorption capacity of TiO 2 NPs and the strong adsorption affinity to Pb ions caused part of the Pb ions released from sediments to aqueous phase were re-adsorbed by TiO 2 NPs in sediments. The concentration of TiO 2 NPs in C. fluminea tissues significantly increased with increasing TiO 2 NP content in sediments, following the order: gill > mantle > foot > visceral mass, which differed from the results found in the aqueous phase. In addition, the proportions of extracellular and intracellular Pb concentrations changed significantly in all the tissues as a result of TiO 2 NP contamination of sediments. TiO 2 NPs promote increased extracellular Pb in foot, mantle, and gill tissues, and increased intracellular Pb in the visceral mass. These results may be beneficial to more scientifically evaluate and predict the environmental risks of TiO 2 NPs to benthic organisms in sediments contaminated by heavy metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. A comparison of equilibrium partitioning and critical body residue approaches for predicting toxicity of sediment-associated fluoranthene to freshwater amphipods

    Energy Technology Data Exchange (ETDEWEB)

    Driscoll, S.K. [Univ. of Michigan, Ann Arbor, MI (United States). Cooperative Inst. for Limnology and Ecosystem Research; Landrum, P.F. [National Oceanic and Atmospheric Administration, Ann Arbor, MI (United States). Great Lakes Environmental Research Lab.

    1997-10-01

    Equilibrium partitioning (EqP) theory predicts that the effects of organic compounds in sediments can be assessed by comparison of organic carbon-normalized sediment concentrations and estimated pore-water concentrations to effects determined in water-only exposures. A complementary approach, the critical body residue (CBR) theory, examines actual body burdens in relation to toxic effects. Critical body residue theory predicts that the narcotic effects of nonpolar compounds should be essentially constant for similar organisms, and narcosis should be observed at body burdens of 2 to 8 {micro}mol/g tissue. This study compares these two approaches for predicting toxicity of the polycyclic aromatic hydrocarbon (PAH) fluoranthene. The freshwater amphipods Hyalella azteca and Diporeia spp. were exposed for up to 30 d to sediment spiked with radiolabeled fluoranthene at concentrations of 0.1 (trace) to 3.940 nmol/g dry weight (= 346 {micro}mol/g organic carbon). Mean survival of Diporeia was generally high (>70%) and not significantly different from that of control animals. This result agrees with EqP predictions, because little mortality was observed for Diporeia in 10-d water-only exposures to fluoranthene in previous studies. After 10-d exposures, mortality of H. azteca was not significantly different from that of controls, even though measured interstitial water concentrations exceeded the previously determined 10-d water-only median lethal concentration (LC50). Equilibrium partitioning overpredicted fluoranthene sediment toxicity in this species. More mortality was observed for H. azteca at later time points, and a 16-d LC50 of 3.550 nmol/g dry weight sediment (291 {micro}mol/g organic carbon) was determined. A body burden of 1.10 {micro}mol fluoranthene-equivalents/g wet weight in H. azteca was associated with 50% mortality after 16-d exposures. Body burdens as high as 5.9 {micro}mol/g wet weight resulted in little mortality in Diporeia.

  2. TiO2nanoparticles in sediments: Effect on the bioavailability of heavy metals in the freshwater bivalve Corbicula fluminea.

    Science.gov (United States)

    Fan, Xiulei; Wang, Chao; Wang, Peifang; Hu, Bin; Wang, Xun

    2018-01-15

    Most studies investigating the influence of TiO 2 NPs on heavy metal bioavailability have focused on the aqueous phase; however, few have examined the sediments containing more nanoparticles. Here, we investigated the effects of TiO 2 NPs on heavy metal bioavailability in C. fluminea in sediments. The interactions between the TiO 2 NPs and metals in sediments, the influence of TiO 2 NPs on metals levels in aqueous phase and geochemical speciation were also explored. The results indicated the large adsorption capacity of TiO 2 NPs and the strong adsorption affinity to metals caused the metals adsorbed on nanoparticles, which decreased the metals concentrations in water phase. Changes in metal speciation caused by metals in EXC, CAR, and IMO partly transported from sediments to TiO 2 NPs during the aging of sediments. Heavy metals contents in C. fluminea tissues were in the order of gill>visceral mass>mantle>foot and increased with the increasing TiO 2 NPs contents in sediments. TiO 2 NPs enhanced the bioavailability of metals in the speciation of EXC, CAR, and IMO in sediments by the Trojan horse effects. The results can facilitate a more realistic evaluation of the environmental risks of TiO 2 NPs to benthic organisms in heavy metal-contaminated sediments. Copyright © 2017. Published by Elsevier B.V.

  3. Bioaccumulation of PAHs from creosote-contaminated sediment in a laboratory-exposed freshwater oligochaete, Lumbriculus variegatus.

    Science.gov (United States)

    Hyötyläinen, Tarja; Oikari, Aimo

    2004-10-01

    The oligochaete, Lumbriculus variegatus, was used for a bioaccumulation assay in the creosote-contaminated sediment of Lake Jämsänvesi in a 28-day experiment. The PAH concentrations of the whole body tissue of worms, sediments and water samples were determinated by GC-MS. Chemical analyses showed that benzo(k)fluoranthene, anthracene and fluorene were the main PAH compounds present in the tissue of oligochaetes, just as in the sediment. The biota-sediment accumulation factors (BSAFs) of the individual PAHs varied from 1.2 to 5.7. It is concluded that oligochaetes have a marked ability to accumulate and retain PAHs from creosote-contaminated sediment.

  4. Transfer of PCBs from bottom sediment to freshwater river fish: a food-web modelling approach in the Rhône River (France) in support of sediment management.

    Science.gov (United States)

    Lopes, C; Persat, H; Babut, M

    2012-07-01

    Since 2005, restrictions have been because of fish consumption along the Rhone River because of high polychlorobiphenyl (PCB) concentrations, which have resulted inadverse economic consequences for professional fisheries in affected areas. French environmental authorities have expended considerable efforts to research sediment remediation strategies and development of sediment quality guidelines designed to protect the health of humans consuming Rhône River fish. Here we: (1) develop a bioaccumulation food-web model that describes PCB concentrations in three common freshwater fish species of the Rhône River, using Bayesian inference to estimate the input parameters; (2) test the predictive power of the model in terms of risk assessment for fish consumption; and (3) discuss the use of this approach to develop sediment quality guidelines that protect the health of humans consuming Rhône River fish. The bioaccumulation model predictions are protective for human consumer of fish and are efficient for use in risk assessment. For example, 85% of the predicted values were within a factor of 5 of measured CB153 concentrations in fish. Using sensitivity analyses, the major role played by sediment and diet behaviors on bioaccumulation process is illustrated: the parameters involved in the respiratory process (contamination from water) have little impact on model outputs, whereas the parameters related to diet and digestion processes are the most sensitive. The bioaccumulation model was applied to derive sediment concentrations compatible with safe fish consumption. The resulting PCB sediment thresholds (expressed as the sum of seven PCB indicator congeners) that are protective for the consumption of the fish species ranged from 0.7 to 3 ng/g (dw). Copyright © 2012 Elsevier Inc. All rights reserved.

  5. The adsorption/desorption of phosphorus in freshwater sediments from buffer zones: the effects of sediment concentration and pH.

    Science.gov (United States)

    Zhang, Liang; Du, Yun; Du, Chao; Xu, Meng; Loáiciga, Hugo A

    2016-01-01

    Riparian buffer zones adjacent to reservoirs and lakes protect aquatic ecosystems from polluted surface runoff. Sediments, collected from the buffer zones of Danjiangkou Reservoir (SR) and Honghu Lake (SL) in an ecologically fragile region in central China, were evaluated to reveal their phosphorus-adsorbing/desorbing properties and storage capacities. A nonlinear regression method was used to fit the pseudo-second-order kinetic and the modified crossover-type Langmuir isotherm models to the experimental data. It is shown that the adsorption of phosphorus onto the studied sediments followed the pseudo-second-order kinetic expression. The modified crossover-type Langmuir isotherm model was found to be a suitable method for describing adsorption/desorption processes in the experimental sediments. The maximum adsorption capacities (Q m), partitioning coefficients (K p), native adsorbed exchangeable phosphorus (NAP), and equilibrium phosphorus concentration (EPC0) were subsequently obtained for the experimental sediments. The effects of sediment concentration and pH were also investigated by batch experiments and Fourier transformation infrared and scanning electron microscopy analyses. The adsorption/desorption characteristics of different phosphate species on the sediments from reservoir and lake buffer zones were identified.

  6. Effect of freshwater mussels on the vertical distribution of anaerobic ammonia oxidizers and other nitrogen-transforming microorganisms in upper Mississippi river sediment

    Directory of Open Access Journals (Sweden)

    Ellen M. Black

    2017-07-01

    Full Text Available Targeted qPCR and non-targeted amplicon sequencing of 16S rRNA genes within sediment layers identified the anaerobic ammonium oxidation (anammox niche and characterized microbial community changes attributable to freshwater mussels. Anammox bacteria were normally distributed (Shapiro-Wilk normality test, W-statistic =0.954, p = 0.773 between 1 and 15 cm depth and were increased by a factor of 2.2 (p < 0.001 at 3 cm below the water-sediment interface when mussels were present. Amplicon sequencing of sediment at depths relevant to mussel burrowing (3 and 5 cm showed that mussel presence reduced observed species richness (p = 0.005, Chao1 diversity (p = 0.005, and Shannon diversity (p < 0.001, with more pronounced decreases at 5 cm depth. A non-metric, multidimensional scaling model showed that intersample microbial species diversity varied as a function of mussel presence, indicating that sediment below mussels harbored distinct microbial communities. Mussel presence corresponded with a 4-fold decrease in a majority of operational taxonomic units (OTUs classified in the phyla Gemmatimonadetes, Actinobacteria, Acidobacteria, Plantomycetes, Chloroflexi, Firmicutes, Crenarcheota, and Verrucomicrobia. 38 OTUs in the phylum Nitrospirae were differentially abundant (p < 0.001 with mussels, resulting in an overall increase from 25% to 35%. Nitrogen (N-cycle OTUs significantly impacted by mussels belonged to anammmox genus Candidatus Brocadia, ammonium oxidizing bacteria family Nitrosomonadaceae, ammonium oxidizing archaea genus Candidatus Nitrososphaera, nitrite oxidizing bacteria in genus Nitrospira, and nitrate- and nitrite-dependent anaerobic methane oxidizing organisms in the archaeal family “ANME-2d” and bacterial phylum “NC10”, respectively. Nitrosomonadaceae (0.9-fold (p < 0.001 increased with mussels, while NC10 (2.1-fold (p < 0.001, ANME-2d (1.8-fold (p < 0.001, and Candidatus Nitrososphaera (1.5-fold (p < 0

  7. Pharmaceutical chemicals, steroids and xenoestrogens in water, sediments and fish from the tidal freshwater Potomac River (Virginia, USA).

    Science.gov (United States)

    Arya, Golala; Tadayon, Sara; Sadighian, James; Jones, Jennifer; de Mutsert, Kim; Huff, Thomas B; Foster, Gregory D

    2017-06-07

    Selected pharmaceutical chemicals, steroids and xenoestrogens (PCSXs) consisting of 29 endocrine modulators, therapeutic drugs, pesticides, detergents, plastics, and active ingredients in household products were measured in water, riverbed sediments and fish collected in a tributary embayment of the Potomac River (Hunting Creek, Alexandria, VA, USA) in the vicinity of wastewater discharge. A total of 17 PCSXs were found in the Hunting Creek samples, with steroid hormones (e.g., progesterone and 17α-ethinylestradiol), triclosan, dextromethorphan and bisphenol A being the most prominent micropollutants detected.The geospatial distribution of the PCSXs in Hunting Creek indicated that the steroids correlated with wastewater treatment plant discharge in all matrices, but such an association is tentative in Hunting Creek given the complex nature of urban sources of PCSXs and hydrodynamics in an urban tidal river. The sediment PCSX concentrations correlated with sediment total organic carbon content at all sampling sites. For the most part, the PCSXs showed an enrichment in fish tissue relative to sediments when concentrations were normalized to lipids and sediment organic carbon contents, but the influence of endogenous steroids is also an important consideration for these chemicals.

  8. Saltwater Intrusion and Freshwater Storage in Sand Sediments along the Coastline: Hydrogeological Investigations and Groundwater Modeling of Nauru Island

    Directory of Open Access Journals (Sweden)

    Luca Alberti

    2017-10-01

    Full Text Available Water resources sustainable management is a vital issue for small islands where groundwater is often the only available water resource. Nauru is an isolated and uplifted limestone atoll island located in the Pacific Ocean. Politecnico di Milano performed a feasibility study for the development of sustainable use of groundwater on the island. This paper focuses on the first phase of the study that concerns the conceptual site model development, the hydrogeological characterization and the 2D model implementation. During the project, different activities were performed such as GNSS topographic survey of monitoring wells and groundwater level surveys taking into account tidal fluctuation. This data collection and the analysis of previous studies made it possible to identify the most suitable areas for groundwater sustainable extraction. The characterization findings suggested, unlike previous studies and surveys, the presence of only few drought resilient thin freshwater lenses, taking place in low conductivity sandy deposits, unexpectedly next to the seashore. Thanks to the 2D modeling results, it has been possible to clarify the mechanism that allows the storage of freshwater so close to the sea.

  9. Endocrine effects of contaminated sediments on the freshwater snail Potamopyrgus antipodarum in vivo and in the cell bioassays in vitro

    Czech Academy of Sciences Publication Activity Database

    Mazurová, E.; Hilscherová, Klára; Jálová, Z.; Kohler, H.R.; Triebskorn, R.; Giesy, J.P.; Bláha, Luděk

    2008-01-01

    Roč. 89, č. 3 (2008), s. 172-179 ISSN 0166-445X Grant - others:GA ČR(CZ) GP525/05/P160 Institutional research plan: CEZ:AV0Z60050516 Keywords : Sediment toxicity * AhR -mediated toxicity * ER-mediated toxicity Subject RIV: EF - Botanics Impact factor: 3.517, year: 2008

  10. Microplastics in freshwater river sediments in Shanghai, China: A case study of risk assessment in mega-cities.

    Science.gov (United States)

    Peng, Guyu; Xu, Pei; Zhu, Bangshang; Bai, Mengyu; Li, Daoji

    2018-03-01

    Microplastics, which are plastic debris with a particle diameter of less than 5 mm, have attracted growing attention in recent years. Its widespread distributions in a variety of habitats have urged scientists to understand deeper regarding their potential impact on the marine living resources. Most studies on microplastics hitherto are focused on the marine environment, and research on risk assessment methodology is still limited. To understand the distribution of microplastics in urban rivers, this study investigated river sediments in Shanghai, the largest urban area in China. Seven sites were sampled to ensure maximum coverage of the city's central districts, and a tidal flat was also included to compare with river samples. Density separation, microscopic inspection and μ-FT-IR analysis were conducted to analyze the characteristics of microplastics and the type of polymers. The average abundance of microplastics in six river sediment samples was 802 items per kilogram of dry weight. The abundance in rivers was one to two orders of magnitude higher than in the tidal flat. White microplastic spheres were most commonly distributed in river sediments. Seven types of microplastics were identified, of which polypropylene was the most prevailing polymers presented. The study then conducted risk assessment of microplastics in sediments based on the observed results, and proposed a framework of environmental risk assessment. After reviewing waste disposal related legislation and regulations in China, this study conclude that in situ data and legitimate estimations should be incorporated as part of the practice when developing environmental policies aiming to tackle microplastic pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Local to regional scale industrial heavy metal pollution recorded in sediments of large freshwater lakes in central Europe (lakes Geneva and Lucerne) over the last centuries

    International Nuclear Information System (INIS)

    Thevenon, Florian; Graham, Neil D.; Chiaradia, Massimo; Arpagaus, Philippe; Wildi, Walter; Poté, John

    2011-01-01

    This research first focuses on the spatial and temporal patterns of heavy metals from contrasting environments (highly polluted to deepwater sites) of Lake Geneva. The mercury (Hg) and lead (Pb) records from two deepwater sites show that the heavy metal variations before the industrial period are primarily linked to natural weathering input of trace elements. By opposition, the discharge of industrial treated wastewaters into Vidy Bay of Lake Geneva during the second part of the 20th century, involved the sedimentation of highly metal-contaminated sediments in the area surrounding the WWTP outlet pipe discharge. Eventually, a new Pb isotope record of sediments from Lake Lucerne identifies the long-term increasing anthropogenic lead pollution after ca. 1500, probably due to the development of metallurgical activities during the High Middle Ages. These data furthermore allows to compare the recent anthropogenic sources of water pollution from three of the largest freshwater lakes of Western Europe (lakes Geneva, Lucerne, and Constance). High increases in Pb and Hg highlight the regional impact of industrial pollution after ca. 1750–1850, and the decrease of metal pollution in the 1980s due to the effects of remediation strategies such as the implementation of wastewater treatment plants (WWTPs). However, at all the studied sites, the recent metal concentrations remain higher than pre-industrial levels. Moreover, the local scale pollution data reveal two highly contaminated sites (> 100 μg Pb/g dry weight sediment) by industrial activities, during the late-19th and early-20th centuries (Lake Lucerne) and during the second part of the 20th century (Vidy Bay of Lake Geneva). Overall, the regional scale pollution history inferred from the three large and deep perialpine lakes points out at the pollution of water systems by heavy metals during the last two centuries due to the discharge of industrial effluents. Highlights: ► Natural sources dominated trace element

  12. Sedimentation

    Science.gov (United States)

    Cliff R. Hupp; Michael R. Schening

    2000-01-01

    Sedimentation is arguably the most important water-quality concern in the United States. Sediment trapping is cited frequently as a major function of riverine-forested wetlands, yet little is known about sedimcntation rates at the landscape scale in relation to site parameters, including woody vegetation type, elevation, velocity, and hydraulic connection to the river...

  13. Bacillus stamsii sp. nov., a facultatively anaerobic sugar degrader that is numerically dominant in freshwater lake sediment.

    Science.gov (United States)

    Müller, Nicolai; Scherag, Frank D; Pester, Michael; Schink, Bernhard

    2015-09-01

    A novel type of anaerobic bacteria was previously isolated from profundal lake sediment by direct dilution of the sediment in mineral agar medium containing glucose and a background lawn of Methanospirillum hungatei as a syntrophic partner. The isolated bacteria grouped with aerobic Bacillus spp. according to their 16S rRNA gene sequence, and the most closely related species is Bacillus thioparans. Fermentative growth of the novel strain with glucose was possible only in the presence of syntrophic partners, and cocultures produced acetate and methane, in some cases also lactate and traces of succinate as fermentation products. In contrast, the closely related strains Bacillus jeotgali and Bacillus sp. strain PeC11 are able to grow with glucose axenically by mixed acid fermentation yielding lactate, acetate, formate, succinate, and ethanol as fermentation products. Alternatively, the isolated strain grew anaerobically in pure culture if pyruvate was added to glucose-containing media, and lactate, acetate and formate were the major fermentation products, but the strain never produced ethanol. Aerobic growth was found with a variety of organic substrates in the presence of partly reduced sulfur compounds. In the absence of sulfide and oxygen, nitrate served as an electron acceptor. Strain BoGlc83 was characterized as the type strain of a new species for which the name Bacillus stamsii sp. nov. (DSM 19598=JCM 30025) is proposed. Copyright © 2015 Elsevier GmbH. All rights reserved.

  14. Effects of sediment-associated CuO nanoparticles on Cu bioaccumulation and oxidative stress responses in freshwater snail Bellamya aeruginosa.

    Science.gov (United States)

    Ma, Taowu; Gong, Shuangjiao; Tian, Bin

    2017-02-15

    Copper oxide nanoparticles (CuO-NPs) may pose high ecological risks to aquatic ecosystems. While sediments are the final destinations for CuO-NPs, little is known about the potential ecotoxicity of sediment-associated CuO-NPs on freshwater deposit-feeding macroinvertebrates. The gastropod Bellamya aeruginosa was chosen as an ecotoxicological test species. Adult snails were exposed to Cu (180μg/g dry weight (DW)) added to sediments in the form of CuO-NPs, CuO microparticles (CuO-MPs, size control), and CuSO 4 (solubility control) for 7, 14, and 28days, Cu burdens in different tissues and biomarkers of oxidative stress were determined to understand Cu accumulation differences among tissues, potential mechanisms of Cu uptake, time-effect relationships, particle size effects, and the relative contribution of toxicity from CuO-NPs and its soluble Cu ions. There was no difference in Cu ion concentrations in porewaters between the CuO-NPs and CuO-MPs treatments. In addition, relatively low Cu ion concentrations in porewater might indicate their remarkably low solubility. The hepatopancreas and gonad of B. aeruginosa are the primary target tissues for Cu accumulation. Cu accumulation in the hepatopancreas and gonad from CuSO 4 treatments was consistently higher than that from the CuO-NPs and CuO-MPs treatments. After long-term exposure, Cu accumulation was higher from CuO-NPs than from CuO-MPs, especially, the Cu accumulation rate from CuO-NPs was greater than that from CuSO 4 . Short-term exposure to the three Cu forms caused oxidative stress to the hepatopancreas. CuO-MPs did not cause oxidative damage. Long-term exposure to CuO-NPs and CuSO 4 resulted in oxidative damage. Overall, prolonged exposure to CuO-NPs will increase the ecotoxicity risk to B. aeruginosa. Although there was no difference in Cu accumulation between the CuO-NPs and CuO-MPs treatments after 14days of exposure, pronounced oxidative damage was caused by exposure to CuO-NPs but not to Cu

  15. Turtles: Freshwater

    Science.gov (United States)

    Gibbons, J. Whitfield; Lovich, Jeffrey E.; Bowden, R.M.

    2017-01-01

    With their iconic shells, turtles are morphologically distinct in being the only extant or extinct vertebrate animals to have their shoulders and hips inside their rib cages. By the time an asteroid hit the earth 65.5 million years ago, causing the extinction of dinosaurs, turtles were already an ancient lineage that was 70% through their evolutionary history to date. The remarkable evolutionary success of turtles over 220 million years is due to a combination of both conservative and effective life history traits and an essentially unchanging morphology that withstood the test of time. However, the life history traits of many species make them particularly susceptible to overharvest and habitat destruction in the modern world, and a majority of the world’s species face serious conservation challenges with several extinctions documented in modern times. The global plight of turtles is underscored by the fact that the percentage of imperiled species exceeds that of even the critically endangered primates.Freshwater turtles, with over 260 recognized species, have become a focus on a worldwide scale for many conservation issues. This article is a synthesis of a diverse body of information on the general biology of freshwater turtles, with particular emphasis on the extensive research on ecology, life history, and behavior that has been accomplished in the last half century. Much of the research has been applicable to the aforementioned conservation challenges. The studies presented include a combination of laboratory and field experiments and observational studies on this intriguing group of animals.

  16. The effect of lake sediment on the hatching success of Daphnia ephippial eggs

    Directory of Open Access Journals (Sweden)

    Jacek Radzikowski

    2016-07-01

    Full Text Available A large proportion of lake-Daphnia ephippia which are shed by females in the water column sink to the bottom, where they form an assemblage of dormant stages known as an egg bank. Although the quantity of zooplankton eggs in such assemblages may exceed tens of thousands per square meter, the annual hatch from this bank is usually extremely low (from zero to a few dozens animals per square meter per year. This low-hatching phenomenon may be caused by isolation from hatching stimuli by water or sediment layers, a mechanical barrier formed by sediment that does not allow hatchlings to reach the water, or by a bet-hedging strategy of the resting eggs. The aim of our study was to determine the extent to which coverage by lake sediment may affect the hatching of Daphnia dormant eggs. The ephippia of lake-Daphnia (longispina species complex, covered by sterilized lake sediment of different thicknesses (0, 0.25, 0.5, 1, 2 and 4 cm; 4 replicates per treatment, were incubated for 8 weeks in lab controlled conditions. The results indicate that even the thinnest tested layer (0.25 cm may completely inhibit hatching of ephippial eggs. A few Daphnia neonates were observed in two (of five sediment treatments, while dozens of animals hatched in the control one. In the second experiment we determined that the sediment sterilization process did not affect the hatching proportion of ephippial eggs (when compared to the treatment with unsterilized sediments. We hypothesize that the observed inhibition of Daphnia hatching in the main experiment, which may cause a serious problem for Cladoceran populations in lakes where no sediment mixing occurs, may be caused by low light intensity, anoxic conditions or a physical barrier created by the sediment.

  17. Freshwater Macroinvertebrates.

    Science.gov (United States)

    Nalepa, T. F.

    1978-01-01

    Presents a literature review of freshwater biology particularly freshwater macroinvertebrates and their effect on water pollution, covering publications of 1976-77. A list of 158 references is also presented. (HM)

  18. Insect succession on a decomposing piglet carcass placed in a man-made freshwater pond in Malaysia.

    Science.gov (United States)

    Heo, C C; Mohamad, A M; John, J; Baharudin, O

    2008-04-01

    This entomological study was conducted in a man-made freshwater pond in a palm oil plantation in Tanjung Sepat, Selangor from 23 July 2007 by using pig (Sus scrofa) as a carcass model. A 1.5 month old piglet (5 kg), which died of asphyxia after being accidentally crushed by its mother, was thrown into a pond. Observation was made for ten days; one visit per day and climatological data were recorded. On the first two days, the piglet carcass sunk to the bottom of the pond. The carcass floated to the surface on the third day but no fly activities were seen. The blow fly, Chrysomya megacephala and Chrysomya rufifacies started to oviposit on the fourth day. Other than adult flies, a spider (Arachnida) was also observed on the carcass. Bubbles accumulated at the mouthpart, and the abdomen was greenish black. A lot of blow fly eggs were seen on the body surface on the fifth day (floating decay), along with first and second instars C. megacephala crawling under the piglet's skin. On the sixth day, adult blow fly, C. megacephala,and C. rufifacies,and muscid flies, Ophyra spinigera and Musca domestica were observed on to the carcass. High numbers of first and second instars of flies were observed wandering around the body surface with C. megacephala larvae being the predominant species. Two prominent maggot masses occurred on seventh and eighth days. Bloated deterioration stage began on day eighth exposing rib bones, humerus bones and intestines. Carcass was partially sinking and the maggot masses were at the water level. On day ninth, the carcass was partially sinking and three maggot masses were observed on the exposed surface. There were very few adult flies, including a scarab beetle was sighted on the carcass at this stage. The carcass along with the maggots sunk on day tenth, leaving an oily layer on the water surface.

  19. The success of the cyanobacterium Cylindrospermopsis raciborskii in freshwaters is enhanced by the combined effects of light intensity and temperature

    Directory of Open Access Journals (Sweden)

    Sylvia Bonilla

    2016-06-01

    Full Text Available Toxic cyanobacterial blooms in freshwaters are thought to be a consequence of the combined effects of anthropogenic eutrophication and climate change. It is expected that climate change will affect water mixing regimes that alter the water transparency and ultimately the light environment for phytoplankton. Blooms of the potentially toxic cyanobacterium Cylindrospermopsis raciborskii are expanding from tropical towards temperate regions. Several hypotheses have been proposed to explain this expansion, including an increase in water temperature due to climate change and the high phenotypic plasticity of the species that allows it to exploit different light environments. We performed an analysis based on eight lakes in tropical, subtropical and temperate regions to examine the distribution and abundance of C. raciborskii in relation to water temperature and transparency. We then conducted a series of short-term factorial experiments that combined three temperatures and two light intensity levels using C. raciborskii cultures alone and in interaction with another cyanobacterium to identify its growth capacity. Our results from the field, in contrast to predictions, showed no differences in dominance (>40% to the total biovolume of C. raciborskii between climate regions. C. raciborskii was able to dominate the phytoplankton in a wide range of light environments (euphotic zone = 1.5 to 5 m, euphotic zone/mixing zone ratio <0.5 to >1.5. Moreover, C. raciborskii was capable of dominating the phytoplankton at low temperatures (<15°C. Our experimental results showed that C. raciborskii growing in interaction was enhanced by the increase of the temperature and light intensity. C. raciborskii growth in high light intensities and at a wide range of temperatures, suggests that any advantage that this species may derive from climate change that favors its dominance in the phytoplankton is likely due to changes in the light environment rather than changes in

  20. Role of morphometry in determining the feeding success of small freshwater fish species: Multivariate analysis of Amblypharyngodon mola, Puntius ticto, and Esomus danricus

    Directory of Open Access Journals (Sweden)

    Nandi Sudarshana

    2015-06-01

    Full Text Available Factor and multiple regression analysis were used to extract the morphometric variables that contributed to feeding success in three small freshwater fishes. Of the first two factors, factor 1, showed high loading of gut weight (GW, length of the upper (UJ, and lower jaws (LJ in mola, Amblypharyngodon mola (Hamilton, and GW and vertical mouth opening (VMO in punti, Puntius ticto (Hamilton. In darikana, Esomus danricus (Hamilton, GW, horizontal mouth opening (HMO, and VMO were highly loaded on factor 2. Gut length (GL was closely associated withGWof all three species. Subsequently, variables with high loading on factors 1 or 2 were subjected to multiple regression analysis to observe their effect on feeding success, consideringGWas the dependent variable and the extracted variables as the independent variable. In A. mola, HMO and GL influenced GW, whereas in P. ticto, only GL determined GW in the fish. In E. danricus, GL, VMO, and HMO exerted a low effect on GW. Exceptionally, the present study suggested that feeding success in small fishes is largely determined by UJ, LJ, and GL or mouth openings.

  1. Sedimentation

    Digital Repository Service at National Institute of Oceanography (India)

    Rixen, T.; Guptha, M.V.S.; Ittekkot, V.

    through the water column but their trapping efficiency, and thus, their accuracy can be biased by hydrodynamic and biological effects (Lee et al., 1988; Gust et al., 1992; 1994). Scholten et al. (2001) showed that the 230 Thorium trapping efficiency... of sediment traps moored at different sites and water depths in eastern North Atlantic Ocean varies between 9 and 143%. In general, these trapping efficiencies increase with increasing water-depth (Scholten et al., 2001). By comparing data from various ocean...

  2. Petrophysical characterization of the lacustrine sediment succession drilled in Lake El'gygytgyn, Far East Russian Arctic

    Directory of Open Access Journals (Sweden)

    A. C. Gebhardt

    2013-08-01

    Full Text Available Seismic profiles of Far East Russian Lake El'gygytgyn, formed by a meteorite impact some 3.6 million years ago, show a stratified sediment succession that can be separated into subunits Ia and Ib at approximately 167 m below lake floor (=~3.17 Ma. The upper (Ia is well-stratified, while the lower is acoustically more massive and discontinuous. The sediments are intercalated with frequent mass movement deposits mainly in the proximal areas, while the distal region is almost free of such deposits at least in the upper part. In spring 2009, a long core drilled in the lake center within the framework of the International Continental Scientific Drilling Program (ICDP penetrated the entire lacustrine sediment succession down to ~320 m below lake floor and about 200 m farther into the meteorite-impact-related bedrock. Downhole logging data down to 390 m below lake floor show that the bedrock and the lacustrine part differ significantly in their petrophysical characteristics. The contact between the bedrock and the lacustrine sediments is not abrupt, but rather transitional with a variable mixture of impact-altered bedrock clasts in a lacustrine matrix. Physical and chemical proxies measured on the cores can be used to divide the lacustrine part into five different statistical clusters. These can be plotted in a redox-condition vs. input-type diagram, with total organic carbon content and magnetic susceptibility values indicating anoxic or oxic conditions and with the Si / Ti ratio representing more clastic or more biogenic input. Plotting the clusters in this diagram allows identifying clusters that represent glacial phases (cluster I, super interglacials (cluster II, and interglacial phases (clusters III and IV.

  3. Persistent organochlorine pesticide residues in freshwater systems ...

    African Journals Online (AJOL)

    , heptachlor and endosulfan were determined in water and sediment samples of freshwater systems in the Eastern Cape Province of South Africa that receive runoff from agricultural lands and effluents from industries. The organochlorine ...

  4. Evaluating order in vertical successions of deltaic Holocene sediments on the Ganges-Brahmaputra-Meghna delta

    Science.gov (United States)

    Sincavage, R.; Goodbred, S. L., Jr.

    2017-12-01

    Most stratigraphic models are predicated on the presence of cyclicity or some form of order in vertical successions of strata. In spite of this a priori assumption of ordered stratigraphy, rarely are statistical metrics employed to quantify cyclicity in sedimentary packages. The presence or absence of preserved order in vertical sedimentary successions has important implications for the nature of environmental signals that are transmitted into the rock record. We interrogate the Holocene sedimentary archive of the Ganges-Brahmaputra-Meghna delta (GBMD) in an effort to explore to what extent fluvio-deltaic deposits exhibit recognizable order. Specifically, we focus on grain size data to evaluate 1.) if stratigraphic order in vertical sedimentary successions can be identified and quantified, and 2.) if there are spatial patterns of stratigraphic order across the GBMD. A runs order metric r is used to identify sequences of coarsening and fining within an extensive borehole network. Observed grain size data are shuffled enough times to generate synthetic "random" stratigraphy, and a Monte Carlo simulation generates 5000 realizations. The distribution of r values from the Monte Carlo are compared to the r metric calculated from observed data to determine how likely the observed metric could be generated by chance. The spatial distribution of order metrics indicates a relationship between areas of enhanced mass extraction and preservation of fluvial successions that scale with modern bar deposits on the Jamuna River. Similarly, probability metrics indicate that vertical successions of grain size data unlikely to have been generated by chance are more likely to be found on distal areas of the delta where 60% of the input mass has been extracted. Combining a mass balance framework with simple statistical metrics has the potential of improving predictions of the stratigraphic architecture and the preservation of ordered vs. disordered signals in the sedimentary record.

  5. Remediating Contaminated Sediments in the Ashtabula Harbor as Part of the Ashtabula River Area of Concern: A Collaboration Success Story

    International Nuclear Information System (INIS)

    Diggs, I.W.; Case, J.L.; Rule, R.W.; Snyder, M.

    2009-01-01

    The U.S. Army Corps of Engineers, Buffalo District (USACE), in close collaboration with the USEPA and members of an Ashtabula, Ohio, stakeholder advocacy group, were able to achieve major success in mitigating ecological impacts from contaminated sediments deposited in the lower Ashtabula River and Ashtabula Harbor after years of effort to obtain the federal funding needed to do so. The river and harbor were subject to unregulated discharges of hazardous chemicals, heavy metals, and low-level radiological contaminants from decades of operations by a variety of industrial, manufacturing, processing and production activities located near or adjacent to the river and harbor areas. Conditions in the ecosystem in and around the lower portion of the river deteriorated to the point that it was designated a Great Lakes Area of Concern (AOC) in 1983. The advocacy group known as the Ashtabula River Partnership (ARP), facilitated through efforts by both USACE and USEPA, developed an innovative plan to remediate the Ashtabula River AOC by conducting a two-phase project, completed with combined funding authorized under the Great Lakes Legacy Act (GLLA) of 2002, and Section 312(a) of the Water Resources Development Act (WRDA) of 1990. Removal of nearly 527,000 m 3 of contaminated sediments from the AOC would significantly reduce the contaminant source term and produce favorable conditions for re-establishing ecosystem balance. This would also be the first project in the nation completed by USACE under its authority to perform environmental dredging covered by WRDA Section 312(a). (authors)

  6. Chloride, bromide and iodide distributions in Loch Lomond sediment interstitial water

    International Nuclear Information System (INIS)

    MacKenzie, A.B.; Shimmield, T.M.; Scott, R.D.; Davidson, C.M.; Hooker, P.J.

    1991-01-01

    The post glacial sediments of Loch Lomond contain a well defined band of marine deposited material which is overlain and underlain by freshwater deposited sediment. The chronology of the sedimentary sequence has been well established by radiocarbon dating and, in the southern basin of the Loch, the marine sediment band is of the order of 1 m thick and typically occurs at a depth of about 3 to 4 m beneath the sediment surface. Previous work has established that the marine deposited sediment contains enhanced concentrations of iodine and bromine relative to the contiguous freshwater sediments and that dissolution of halogen elements from the marine sediments generates a concentration gradient, with consequent diffusive transport, of these elements in the sediment interstitial water. This environment is thus highly suitable for investigation of the rate of transport of halogen elements through the sediment a topic of direct relevance to radioactive waste disposal in the context of far field migration of 129 I. Previous studies resulted in successful modelling of the diffusive transport of bromine in the interstitial water of the sediment on the basis of the observed concentration profile for total bromine in the water. This work was, however, of restricted value since (1) speciation was not determined (2) archived sediment was used and (3) samples were processed and analyzed under ambient laboratory conditions. The objective of the work described in this report was to collect a new core of Loch Lomond sediment and to carry out appropriate analyses to overcome the above limitations

  7. Turnover Rates of Intermediate Sulfur Species ([Formula: see text], S0, S2[Formula: see text], S4[Formula: see text], [Formula: see text]) in Anoxic Freshwater and Sediments.

    Science.gov (United States)

    Findlay, Alyssa J; Kamyshny, Alexey

    2017-01-01

    The microbial reduction of sulfate to sulfide coupled to organic matter oxidation followed by the transformation of sulfide back to sulfate drives a dynamic sulfur cycle in a variety of environments. The oxidative part of the sulfur cycle in particular is difficult to constrain because the eight electron oxidation of sulfide to sulfate occurs stepwise via a suite of biological and chemical pathways and produces a wide variety of intermediates ([Formula: see text], S 0 , S 2 [Formula: see text], S 4 [Formula: see text], and [Formula: see text]), which may in turn be oxidized, reduced or disproportionated. Although the potential processes affecting these intermediates are well-known from microbial culture and geochemical studies, their significance and rates in the environment are not well constrained. In the study presented here, time-course concentration measurements of intermediate sulfur species were made in amended freshwater water column and sediment incubation experiments in order to constrain consumption rates and processes. In sediment incubations, consumption rates were [Formula: see text] [Formula: see text] [Formula: see text] S 4 [Formula: see text] S 2 [Formula: see text], which is consistent with previous measurements of [Formula: see text], S 4 [Formula: see text], and S 2 [Formula: see text] consumption rates in marine sediments. In water column incubations, however, the relative reactivity was [Formula: see text] [Formula: see text] [Formula: see text] S 2 [Formula: see text] S 4 [Formula: see text]. Consumption of thiosulfate, tetrathionate and sulfite was primarily biological, whereas it was not possible to distinguish between abiotic and biological polysulfide consumption in either aqueous or sediment incubations. [Formula: see text] consumption in water column experiments was biologically mediated, however, rapid sedimentary consumption was likely due to reactions with iron minerals. These experiments provide important constraints on the

  8. Mapping localised freshwater anomalies in the brackish paleo-lake sediments of the Machile–Zambezi Basin with transient electromagnetic sounding, geoelectrical imaging and induced polarisation

    DEFF Research Database (Denmark)

    Chongo, Mkhuzo; Christiansen, Anders Vest; Fiandaca, Gianluca

    2015-01-01

    A recent airborne TEM survey in the Machile–Zambezi Basin of south western Zambia revealed high electrical resistivity anomalies (around 100 Ωm) in a low electrical resistivity (below 13 Ωm) background. The near surface (0–40 m depth range) electrical resistivity distribution of these anomalies...... appeared to be coincident with superficial features related to surface water such as alluvial fans and flood plains. This paper describes the application of transient electromagnetic soundings (TEM) and continuous vertical electrical sounding (CVES) using geo-electrics and time domain induced polarisation...... thins out and deteriorates in water quality further inland. It is postulated that the freshwater lens originated as a result of interaction between the Zambezi River and the salty aquifer in a setting in which evapotranspiration is the net climatic stress. Similar high electrical resistivity bodies were...

  9. In-situ subaqueous capping of mercury-contaminated sediments in a fresh-water aquatic system, Part I—Bench-scale microcosm study to assess methylmercury production

    Energy Technology Data Exchange (ETDEWEB)

    Randall, Paul M., E-mail: randall.paul@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 W. Martin Luther King Drive, Cincinnati, OH 45268 (United States); Fimmen, Ryan [Geosyntec Consultants, 150 E. Wilson Bridge Road, Suite 232, Worthington, OH 43085 (United States); Lal, Vivek; Darlington, Ramona [Battelle, 505 King Ave., Columbus, OH 43201 (United States)

    2013-08-15

    Bench-scale microcosm experiments were designed to provide a better understanding of the potential for Hg methylation in sediments from an aquatic environment. Experiments were conducted to examine the function of sulfate concentration, lactate concentration, the presence/absence of an aqueous inorganic Hg spike, and the presence/absence of inoculums of Desulfovibrio desulfuricans, a strain of sulfate-reducing bacteria (SRB) commonly found in the natural sediments of aquatic environments. Incubations were analyzed for both the rate and extent of (methylmercury) MeHg production. Methylation rates were estimated by analyzing MeHg and Hg after 2, 7, 14, 28, and 42 days. The production of metabolic byproducts, including dissolved gases as a proxy for metabolic utilization of carbon substrate, was also monitored. In all treatments amended with lactate, sulfate, Hg, and SRB, MeHg was produced (37 ng/g-sediment dry weight) after only 48 h of incubation and reached a maximum sediment concentration of 127 ng/g-sediment dry weight after the 42 day incubation period. Aqueous phase production of MeHg was observed to be 10 ng/L after 2 day, reaching a maximum observed concentration of 32.8 ng/L after 14 days, and declining to 10.8 ng/L at the end of the incubation period (42 day). The results of this study further demonstrates that, in the presence of an organic carbon substrate, sulfate, and the appropriate consortia of microorganisms, sedimentary Hg will be transformed into MeHg through bacterial metabolism. Further, this study provided the basis for evaluation of an in-situ subaqueous capping strategy that may limit (or potentially enhance) MeHg production. -- Highlights: • Hg methylation by SRB is limited by the depletion of sulfate and carbon. • Hg methylation is sensitive to competition by methanogens for carbon substrate. • In high lactate environment, all lactate was utilized in the microcosms within seven days. • In the absence of adequate metabolic fuel, Me

  10. In-situ subaqueous capping of mercury-contaminated sediments in a fresh-water aquatic system, Part I—Bench-scale microcosm study to assess methylmercury production

    International Nuclear Information System (INIS)

    Randall, Paul M.; Fimmen, Ryan; Lal, Vivek; Darlington, Ramona

    2013-01-01

    Bench-scale microcosm experiments were designed to provide a better understanding of the potential for Hg methylation in sediments from an aquatic environment. Experiments were conducted to examine the function of sulfate concentration, lactate concentration, the presence/absence of an aqueous inorganic Hg spike, and the presence/absence of inoculums of Desulfovibrio desulfuricans, a strain of sulfate-reducing bacteria (SRB) commonly found in the natural sediments of aquatic environments. Incubations were analyzed for both the rate and extent of (methylmercury) MeHg production. Methylation rates were estimated by analyzing MeHg and Hg after 2, 7, 14, 28, and 42 days. The production of metabolic byproducts, including dissolved gases as a proxy for metabolic utilization of carbon substrate, was also monitored. In all treatments amended with lactate, sulfate, Hg, and SRB, MeHg was produced (37 ng/g-sediment dry weight) after only 48 h of incubation and reached a maximum sediment concentration of 127 ng/g-sediment dry weight after the 42 day incubation period. Aqueous phase production of MeHg was observed to be 10 ng/L after 2 day, reaching a maximum observed concentration of 32.8 ng/L after 14 days, and declining to 10.8 ng/L at the end of the incubation period (42 day). The results of this study further demonstrates that, in the presence of an organic carbon substrate, sulfate, and the appropriate consortia of microorganisms, sedimentary Hg will be transformed into MeHg through bacterial metabolism. Further, this study provided the basis for evaluation of an in-situ subaqueous capping strategy that may limit (or potentially enhance) MeHg production. -- Highlights: • Hg methylation by SRB is limited by the depletion of sulfate and carbon. • Hg methylation is sensitive to competition by methanogens for carbon substrate. • In high lactate environment, all lactate was utilized in the microcosms within seven days. • In the absence of adequate metabolic fuel, Me

  11. Toxicity of sediment-associated substituted phenylamine antioxidants on the early life stages of Pimephales promelas and a characterization of effects on freshwater organisms.

    Science.gov (United States)

    Prosser, Ryan S; Parrott, Joanne L; Galicia, Melissa; Shires, Kallie; Sullivan, Cheryl; Toito, John; Bartlett, Adrienne J; Milani, Danielle; Gillis, Patty L; Balakrishnan, Vimal K

    2017-10-01

    Substituted phenylamine antioxidants (SPAs) are high production volume chemicals that are incorporated into a variety of commercial products (e.g., polymers, dyes, lubricants). There are few data on chronic toxicity of SPAs to fish and no data on the toxicity of SPAs to the early life stages of fish. The physicochemical properties of SPAs would suggest that if they were to enter an aquatic ecosystem they would partition into sediment. Therefore, the present study focused on investigating the chronic effect of sediment-associated SPAs to the early life stages of the fathead minnow (Pimephales promelas). Eggs and larvae were exposed to sediment spiked with diphenylamine (DPA), N-phenyl-1-napthylamine (PNA), N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (DPPDA), or 4,4'-methylene-bis[N-sec-butylaniline] (MBA). The most sensitive endpoint for DPA, PNA, and DPPDA was total survival with 21-d median lethal concentrations (LC50s) based on concentration in overlying water of 1920, 74, and 35 μg/L, respectively. The most sensitive endpoint for MBA was growth with a 21-d median effective concentration (EC50) of 71 μg/L. The same endpoints were the most sensitive in terms of concentrations of DPA, PNA, DPPDA, and MBA in sediment (101, 54, 111, and 76 μg/g dry wt, respectively). Species sensitivity distributions (SSDs) were constructed for each SPA based on acute and chronic toxicity data generated in the present study and found in the literature. Overall, P. promelas was in the midrange of chronic sensitivity, with the most sensitive species being Tubifex tubifex. The SSDs indicate that DPA based on concentration in water is the least toxic to aquatic biota of the 4 SPAs investigated. The constructed SSDs indicate that a concentration in water and sediment of 1 μg/L and 1 μg/g dry weight, respectively, would be protective of >95% of the aquatic species tested. Environ Toxicol Chem 2017;36:2730-2738. © 2017 SETAC. © 2017 SETAC.

  12. Uptake of Cadmium, Copper, Lead, and Zinc from Sediments by an Aquatic Macrophyte and by Terrestrial Arthropods in a Freshwater Wetland Ecosystem.

    Science.gov (United States)

    Kim, Heung-Tae; Kim, Jae Geun

    2016-08-01

    The objective of this study was to investigate trace-metal [cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn)] biotransference and biomagnification in terrestrial biota at different trophic levels (primary producer-top predator) of a wetland ecosystem. We investigated whether metal concentrations in the sediment are reflected in terrestrial arthropods and aquatic plants. We sampled the floating-leaved plant Trapa japonica; its species-specific primary consumer, the leaf beetle Galerucella nipponensis; and two predatory arthropods (the water strider Gerris sp. and the wolf spider Arctosa sp.) from three wetlands with different sedimentary metal concentrations. The δ(13)C and δ(15)N signatures in the trophic link between the plants and the leaf beetles supported the specificity of their feeding relationship. The stable isotope signatures indicate that the leaf beetle could be an important link in the trophic transfer of the metals. Transference factors (TFs) were 1 for all biota, and the concentrations were positively correlated with the trophic levels. Thus, there may be Cu and Zn biomagnification in the arthropods. We noted TF 1 among the arthropods. Therefore, Cd is probably not biomagnified between T. japonica and G. nipponensis, but it might be biomagnified in the arthropods. The metal burden in terrestrial arthropods may also be influenced by uptake from the sediment by aquatic plants.

  13. Toxicology of freshwater cyanobacteria.

    Science.gov (United States)

    Liyanage, H M; Arachchi, D N Magana; Abeysekara, T; Guneratne, L

    2016-07-02

    Many chemical contaminants in drinking water have been shown to cause adverse health effects in humans after prolonged exposure. Cyanobacteria are one of the most potent and diverse groups of photosynthetic prokaryotes. One key component of cyanobacterial success in the environment is the production of potent toxins as secondary metabolites, which have been responsible for numerous adverse health impacts in humans. Anthropogenic activities have led to the increase of eutrophication in freshwater bodies' worldwide, causing cyanobacterial blooms to become more frequent. The present article will discuss about harmful cyanobacteria and their toxicology with special references to microcystin, nodularin, and cylindrospermopsin.

  14. Ecotoxicological assessment of the pharmaceutical compound Triclosan to freshwater invertebrates with emphasis to spiked sediment tests; Avaliacao ecotoxicologica do farmaco Triclosan para invertebrados de agua doce com enfase em ensaios com sedimento marcado ('spiked sediment')

    Energy Technology Data Exchange (ETDEWEB)

    Pusceddu, Fabio Hermes

    2009-07-01

    The increasing of Pharmaceutical and Personal Care Products (PPCPs) occurrence in the aquatic environment cause adverse effects on the human health and aquatic communities. The environmental risk of the PPCPs associated with the possibility of synergic effects between PCPPs and the increase of the use of synthetic organic compounds, unchained a great concern on the toxic potential to biota aquatic. Triclosan (5-chloro-2-(2,4-dichlorophenoxy)-phenol) is a pharmaceutical compound widely used due your antibacterial mechanism effect, found in at least 932 products such as shampoos, toilet soaps, deodorants, lotions, toothpaste, detergents, socks and underwear, among others. Currently, studies about the Triclosan toxicity in the water and, mainly in the sediment, are poorly. We have the knowledge that the photodegradation of this product results into dichlorodibenzo-p-dioxin, and now it has great discussion on environmental agencies, like EPA, about the release or restriction of this product. The aim of this work is to assess the effects of Triclosan on mortality of insect larvae Chironomus xanthus and mortality and reproduction inhibition of microcrustacea Ceriodaphnia dubia exposed to Triclosan spiked sediments based on standard methods EPA and OECD. The EC50;96H obtained on acute toxicity tests with C. xanthus was 45,26 mg.Kg{sup -1}. The chronic toxicity tests with C. dubia using spiked sediments were performed following the procedure in Burton and MacPherson (1995). A no-observed-effect concentrations and lowest-observed-effect concentration were 5,78 e 6,94 mg.Kg{sup -1}, respectively. (author)

  15. Freshwater Fish Communities

    Science.gov (United States)

    Freshwater fish are ecologically important in stream ecosystems, and they provide people with significant food, recreation, and conservation value as biological indicator of freshwater streams. Historically, the streams and rivers of southern New England supported moderately dive...

  16. Sediment-palaeosol successions in Calabria and Sardinia suggest spatially differentiated palaeo-vegetation patterns in southern Italy during the Last Glacial period

    Science.gov (United States)

    Sauer, Daniela; Zucca, Claudio; Al-Sharif, Riyad; Zwanzig, Lisa; Madrau, Salvatore; Andreucci, Stefano; Pascucci, Vincenzo; Kadereit, Annette; Scarciglia, Fabio; Brückner, Helmut

    2016-04-01

    Several lakes on the southern Italian peninsula provide valuable palaeoenvironmental archives of the Last Glacial period. These archives include, e.g., the long high-resolution record from varved lake sediments of Lago Grande di Monticchio, the bigger one of two maar lakes situated on top of Mt. Vulture. Its pollen record indicates (1) temperate deciduous forest during MIS5.2-MIS5.1 (St. Germain 2); (2) frequent vegetation fluctuations, then Artemisia steppe during MIS5.1-MIS4; (3) alternations between open steppe (stadials) and wooded steppe (interstadials) during MIS3; and (4) open steppe during MIS2 (Last Glacial Maximum). However, only few palaeosol records of this period have been reported from southern Italy in the literature so far. Such records would allow for gaining insight also into spatial patterns of the vegetation cover during this period that should have formed, e.g., according to relief, elevation, and continentality gradient (related to the much lower coastline during the last glacial period). So far, we have studied three sediment-palaeosol successions in southern Italy, two in the Calabria region, and one in north-western Sardinia. All of them have developed in alluvial fan deposits resting on littoral sediments of the Last Interglacial period (MIS 5). The southernmost succession studied is located near Lazzaro (south of Reggio di Calabria). It is exposed in an alluvial fan overlying the MIS5.5 terrace. Due to strong tectonic uplift (1.3 m ka-1) the alluvial fan has been dissected by the same creek which previously had built it up. Therefore, its internal structure is exposed, exhibiting a detailed sediment-palaeosol sequence. The palaeosols are mainly characterized by accumulation of soil organic matter (SOM), bioturbation and secondary carbonates. They represent Chernozem- and Phaeozem-like soils that most likely formed under steppe to forest steppe. SOM of the two uppermost Lazzaro palaeosols was 14C-dated to 26.8-28.8 ka cal BP and 28

  17. Exploring Freshwater Science

    Indian Academy of Sciences (India)

    hydrological modifications on freshwater fish communities ... transformation on eco-hydrology. Freshwater ecosystems and associated habitats harbor incred- ible biodiversity. They offer various ecosystem services and sustain human livelihoods. However, due to ... complete their life cycle exclusively in the freshwater ...

  18. Tropical Freshwater Biology

    African Journals Online (AJOL)

    Tropical Freshwater Biology promotes the publication of scientific contributions in the field of freshwater biology in the tropical and subtropical regions of the world. One issue is published annually but this number may be increased. Original research papers and short communications on any aspect of tropical freshwater ...

  19. Final Verification Success Story Using the Triad Approach at the Oak Ridge National Laboratory's Melton Valley Soils and Sediment Project

    International Nuclear Information System (INIS)

    King, D.A.; Haas, D.A.; Cange, J.B.

    2006-01-01

    The United States Environmental Protection Agency recently published guidance on the Triad approach, which supports the use of smarter, faster, and better technologies and work strategies during environmental site assessment, characterization, and cleanup. The Melton Valley Soils and Sediment Project (Project) at the Oak Ridge National Laboratory embraced this three-pronged approach to characterize contaminants in soil/sediment across the 1000-acre Melton Valley Watershed. Systematic Project Planning is the first of three prongs in the Triad approach. Management initiated Project activities by identifying key technical personnel, included regulators early in the planning phase, researched technologies, and identified available resources necessary to meet Project objectives. Dynamic Work Strategies is the second prong of the Triad approach. Core Team members, including State and Federal regulators, helped develop a Sampling and Analysis Plan that allowed experienced field managers to make real-time, in-the-field decisions and, thus, to adjust to conditions unanticipated during the planning phase. Real-time Measurement Technologies is the third and last prong of the Triad approach. To expedite decision-making, the Project incorporated multiple in-field technologies, including global positioning system equipment integrated with field screening instrumentation, magnetometers for utility clearance, and an on-site gamma spectrometer (spec) for rapid contaminant speciation and quantification. As a result of a relatively complex but highly efficient program, a Project field staff of eight collected approximately 1900 soil samples for on-site gamma spec analysis (twenty percent were also shipped for off-site analyses), 4.7 million gamma radiation measurements, 1000 systematic beta radiation measurements, and 3600 systematic dose rate measurements between July 1, 2004, and October 31, 2005. The site database previously contained results for less than 500 soil samples dating

  20. Modeling Aeolian Transport of Contaminated Sediments at Los Alamos National Laboratory, Technical Area 54, Area G: Sensitivities to Succession, Disturbance, and Future Climate

    International Nuclear Information System (INIS)

    Whicker, Jeffrey J.; Kirchner, Thomas B.; Breshears, David D.; Field, Jason P.

    2012-01-01

    succession and environmental disturbance. Aeolian, or wind-driven, sediment transport drives soil erosion, affects biogeochemical cycles, and can lead to the transport of contaminants. Rates of aeolian sediment transport depend in large part on the type, amount, and spatial pattern of vegetation. In particular, the amount of cover from trees and shrubs, which act as roughness elements, alters rates of aeolian sediment transport. The degree to which the understory is disturbed and the associated spacing of bare soil gaps further influence sediment transport rates. Changes in vegetation structure and patterns over periods of years to centuries may have profound impacts on rates of wind-driven transport. For recently disturbed areas, succession is likely to occur through a series of vegetation communities. Area G currently exhibits a mosaic of vegetation cover, with patches of grass and forbs over closed disposal units, and bare ground in heavily used portions of the site. These areas are surrounded by less disturbed regions of shrubland and pinon-juniper woodland; some ponderosa pine forest is also visible in the canyon along the road. The successional trajectory for the disturbed portions of Area G is expected to proceed from grasses and forbs (which would be established during site closure), to shrubs such as chamisa, to a climax community of pinon-juniper woodland. Although unlikely under current conditions, a ponderosa pine forest could develop over the site if the future climate is wetter. In many ecosystems, substantial and often periodic disturbances such as fire or severe drought can rapidly alter vegetation patterns. Such disturbances are likely to increase in the southwestern US where projections call for a warmer and drier climate. With respect to Area G, the 3 most likely disturbance types are surface fire, crown fire, and drought-induced tree mortality. Each type of disturbance has a different frequency or likelihood of occurrence, but all 3 tend to reset the

  1. Modeling Aeolian Transport of Contaminated Sediments at Los Alamos National Laboratory, Technical Area 54, Area G: Sensitivities to Succession, Disturbance, and Future Climate

    Energy Technology Data Exchange (ETDEWEB)

    Whicker, Jeffrey J. [Los Alamos National Laboratory; Kirchner, Thomas B. [New Mexico State University; Breshears, David D. [University of Arizona; Field, Jason P. [University of Arizona

    2012-03-27

    succession and environmental disturbance. Aeolian, or wind-driven, sediment transport drives soil erosion, affects biogeochemical cycles, and can lead to the transport of contaminants. Rates of aeolian sediment transport depend in large part on the type, amount, and spatial pattern of vegetation. In particular, the amount of cover from trees and shrubs, which act as roughness elements, alters rates of aeolian sediment transport. The degree to which the understory is disturbed and the associated spacing of bare soil gaps further influence sediment transport rates. Changes in vegetation structure and patterns over periods of years to centuries may have profound impacts on rates of wind-driven transport. For recently disturbed areas, succession is likely to occur through a series of vegetation communities. Area G currently exhibits a mosaic of vegetation cover, with patches of grass and forbs over closed disposal units, and bare ground in heavily used portions of the site. These areas are surrounded by less disturbed regions of shrubland and pinon-juniper woodland; some ponderosa pine forest is also visible in the canyon along the road. The successional trajectory for the disturbed portions of Area G is expected to proceed from grasses and forbs (which would be established during site closure), to shrubs such as chamisa, to a climax community of pinon-juniper woodland. Although unlikely under current conditions, a ponderosa pine forest could develop over the site if the future climate is wetter. In many ecosystems, substantial and often periodic disturbances such as fire or severe drought can rapidly alter vegetation patterns. Such disturbances are likely to increase in the southwestern US where projections call for a warmer and drier climate. With respect to Area G, the 3 most likely disturbance types are surface fire, crown fire, and drought-induced tree mortality. Each type of disturbance has a different frequency or likelihood of occurrence, but all 3 tend to reset the

  2. Tectonic control on turbiditic sedimentation: The Late Cretaceous-Eocene successions in the Sinop-Boyabat Basin of north-central Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Janbu, Nils Erik

    2004-07-01

    The aim of this study: Tectonics is widely recognized by geologists as the single most important factor controlling the development, filling and deformation of sedimentary basins. In general terms, the role of tectonics seems rather ''obvious'' to most geologists, because we know reasonably well as what tectonics ''can do'' as the agent of structural deformation. Therefore, the role of tectonics is often invoked as a kind of ballpark variable - as the obvious cause of ''subsidence'' or ''uplift'' - and seems to some authors even too obvious to mention. Relatively little attempt has been in sedimentological and stratigraphic studies to recognize as to what effects exactly the tectonic activity had on sedimentation in a particular basin. The principal aim of the present study has been to improve our understanding of how tectonic activity can affect deep-water turbiditic sedimentation in a particular basin, including its ''external'' influences (basin geometry, basin-margin configuration, sediment source/supply and relative sea-level change) and ''internal'' effects (basin-floor subsidence, seafloor deformation). Foreland basins are some of the most active tectonically, and the Sinop- Boyabat Basin is a fascinating case of a rift converted into a foreland basin and increasingly deformed. Summary of papers: The main part of the field study, concerned with the sedimentology and facies analysis of the turbiditic succession, is summarized in Papers 1-3, which put special emphasis on the physical character and morphodynamic evolution of the depositional systems and on the tectonic control on their development. Paper 4 focuses on the frequency distribution of bed thickness data collected by detailed logging of various turbiditic assemblages: siliciclastic deposits of nonchannelized currents (lobe and overbank facies); siliciclastic deposits of poorly

  3. Davis Pond freshwater prediversion biomonitoring study: freshwater fisheries and eagles

    Science.gov (United States)

    Jenkins, Jill A.; Bourgeois, E. Beth; Jeske, Clint W.

    2008-01-01

    In January 2001, the construction of the Davis Pond freshwater diversion structure was completed by the U.S. Army Corps of Engineers. The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. In addition to the freshwater inflow, Barataria Bay basin would receive nutrients, increased flows of sediments, and water-borne and sediment-bound compounds. The purpose of this biomonitoring study was, therefore, to serve as a baseline for prediversion concentrations of selected contaminants in bald eagle (Haliaeetus leucocephalus) nestlings (hereafter referred to as eaglets), representative freshwater fish, and bivalves. Samples were collected from January through June 2001. Two similarly designed postdiversion studies, as described in the biological monitoring program, are planned. Active bald eagle nests targeted for sampling eaglet blood (n = 6) were generally located southwest and south of the diversion structure. The designated sites for aquatic animal sampling were at Lake Salvador, at Lake Cataouatche, at Bayou Couba, and along the Mississippi River. Aquatic animals representative of eagle prey were collected. Fish were from three different trophic levels and have varying feeding strategies and life histories. These included herbivorous striped mullet (Mugil cephalus), omnivorous blue catfish (Ictalurus furcatus), and carnivorous largemouth bass (Micropterus salmoides). Three individuals per species were collected at each of the four sampling sites. Freshwater Atlantic rangia clams (Rangia cuneata) were collected at the downstream marsh sites, and zebra mussels (Dreissena spp.) were collected on the Mississippi River. The U.S. Geological Survey (USGS) Biomonitoring of Environmental Status and Trends (BEST) protocols served as guides for fish sampling and health assessments. Fish are useful for monitoring aquatic ecosystems because they accumulate

  4. Novel Synechococcus Genomes Reconstructed from Freshwater Reservoirs

    Directory of Open Access Journals (Sweden)

    Pedro J. Cabello-Yeves

    2017-06-01

    Full Text Available Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb and average intergenic spacer length (20 bp of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems. Fluorescent in situ hybridization confirmed that Synechococcus sp. Tous comprises small cells (0.987 ± 0.139 μm length, 0.723 ± 0.119 μm width that amount to 90% of the picocyanobacteria in Tous. They appear together in a phylogenomic tree with Synechococcus sp. RCC307 strain, the main representative of sub-cluster 5.3 that has itself one of the smallest marine Synechococcus genomes. We detected a type II phycobilisome (PBS gene cluster in both genomes, which suggests that they belong to a phycoerythrin-rich pink low-light ecotype. The decrease of acidic proteins and the higher content of basic transporters and membrane proteins in the novel Synechococcus genomes, compared to marine representatives, support their freshwater specialization. A sulfate Cys transporter which is absent in marine but has been identified in many freshwater cyanobacteria was also detected in Synechococcus sp. Tous. The RuBisCo subunits from this microbe are phylogenetically close to the freshwater amoeba Paulinella chromatophora symbiont, hinting to a freshwater origin of the carboxysome operon of this protist. The novel genomes enlarge the known diversity of freshwater Synechococcus and improve the overall knowledge of the relationships among members of this genus at large.

  5. Novel Synechococcus Genomes Reconstructed from Freshwater Reservoirs

    Science.gov (United States)

    Cabello-Yeves, Pedro J.; Haro-Moreno, Jose M.; Martin-Cuadrado, Ana-Belen; Ghai, Rohit; Picazo, Antonio; Camacho, Antonio; Rodriguez-Valera, Francisco

    2017-01-01

    Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb) and average intergenic spacer length (20 bp) of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems. Fluorescent in situ hybridization confirmed that Synechococcus sp. Tous comprises small cells (0.987 ± 0.139 μm length, 0.723 ± 0.119 μm width) that amount to 90% of the picocyanobacteria in Tous. They appear together in a phylogenomic tree with Synechococcus sp. RCC307 strain, the main representative of sub-cluster 5.3 that has itself one of the smallest marine Synechococcus genomes. We detected a type II phycobilisome (PBS) gene cluster in both genomes, which suggests that they belong to a phycoerythrin-rich pink low-light ecotype. The decrease of acidic proteins and the higher content of basic transporters and membrane proteins in the novel Synechococcus genomes, compared to marine representatives, support their freshwater specialization. A sulfate Cys transporter which is absent in marine but has been identified in many freshwater cyanobacteria was also detected in Synechococcus sp. Tous. The RuBisCo subunits from this microbe are phylogenetically close to the freshwater amoeba Paulinella chromatophora symbiont, hinting to a freshwater origin of the carboxysome operon of this protist. The novel genomes enlarge the known diversity of freshwater Synechococcus and improve the overall knowledge of the relationships among members of this genus at large. PMID:28680419

  6. Archives: Tropical Freshwater Biology

    African Journals Online (AJOL)

    Items 1 - 23 of 23 ... Archives: Tropical Freshwater Biology. Journal Home > Archives: Tropical Freshwater Biology. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 23 of 23 Items ...

  7. The freshwater biodiversity crisis

    African Journals Online (AJOL)

    group of native fishes, the cyprinids, still persist in many of the country's freshwaters. This paper combines review of ... Key words/phrases: Deforestation, Ethiopia, fish diversity, freshwater ecosystems, introduced species ...... Stomach pH, feeding rhythm and ingestion rate in Oreo- chromis niloticus L. (Pisces: Cichlidae) in ...

  8. Meeting ecological and societal needs for freshwater

    Science.gov (United States)

    Baron, Jill S.; Poff, N.L.; Angermeier, P.L.; Dahm, Clifford N.; Gleick, P.H.; Hairston, N.G.; Jackson, R.B.; Johnston, C.A.; Richter, B.D.; Steinman, A.D.

    2002-01-01

    sinks” into which landscapes drain, they are greatly influenced by terrestrial processes, including many human uses or modifications of land and water. Freshwater ecosystems, whether lakes, wetlands, or rivers, have specific requirements in terms of quantity, quality, and seasonality of their water supplies. Sustainability normally requires these systems to fluctuate within a natural range of variation. Flow regime, sediment and organic matter inputs, thermal and light characteristics, chemical and nutrient characteristics, and biotic assemblages are fundamental defining attributes of freshwater ecosystems. These attributes impart relatively unique characteristics of productivity and biodiversity to each ecosystem. The natural range of variation in each of these attributes is critical to maintaining the integrity and dynamic potential of aquatic ecosystems; therefore, management should allow for dynamic change. Piecemeal approaches cannot solve the problems confronting freshwater ecosystems.Scientific definitions of the requirements to protect and maintain aquatic ecosystems are necessary but insufficient for establishing the appropriate distribution between societal and ecosystem water needs. For scientific knowledge to be implemented science must be connected to a political agenda for sustainable development. We offer these recommendations as a beginning to redress how water is viewed and managed in the United States: (1) Frame national and regional water management policies to explicitly incorporate freshwater ecosystem needs, particularly those related to naturally variable flow regimes and to the linking of water quality with water quantity; (2) Define water resources to include watersheds, so that freshwaters are viewed within a landscape, or systems context; (3) Increase communication and education across disciplines, especially among engineers, hydrologists, economists, and ecologists to facilitate an integrated view of freshwater resources; (4) Increase restoration

  9. Sedimentary architecture of the distal lower freshwater molasse and its relation to the diagenesis and petrophysical properties demonstrated by the example of the Langenthal boreholes

    International Nuclear Information System (INIS)

    Keller, B.; Blaesi, H.R.; Platt, N.H.; Mozley, P.S.; Matter, A.

    1990-08-01

    Sedimentary study at outcrop and quarry exposures of distal alluvial deposits in the upper part of the Lower Freshwater Molasse ('Aquitan') has revealed four principal facies. The same facies may also be recognised in boreholes (Langenthal, Weiach, Schafisheim) penetrating the continental succession. These facies make up distinct sediment bodies or 'architectural elements'. Each architectural element may be assigned to a particular depositional setting: Meander Belt RG (MB); Crevasse Splays and Crevasse Channels DFR (CS), Levees and Distal Splays UW (LS), Overbank, Paleosols and Swamps UPS (OPS) and Lacustrine LAK (LAC). Meander belt sandstones in the distal Lower Freshwater Molasse reflect the occurrence of two types of mixed load channels. Architectural modelling permits consideration of the distal Lower Freshwater Molasse in terms of a sandy framework, comprising the channel sandstone bodies, each in contact with their associated crevasse splay and crevasse channel sandstones, and a muddy-silty matrix consisting of interbedded floodplain sediments. Comparison with the morphologies of modern alluvial systems suggests that channel sandstone bodies in the Lower Freshwater Molasse are likely to show greater longitudinal continuity, greater width and a higher degree of interconnectedness in an upstream direction. Conversely, primary depositional porosities and permeabilities of the sandstone units are likely to decrease downstream towards more distal areas in the east and at the northern margin of the basin, although regional differences in tectonic style and diagenesis will also exert a major control on the petrophysical and hydrological properties in any given area. (author) figs., tabs., 54 refs

  10. Freshwater Fungal Infections

    Directory of Open Access Journals (Sweden)

    Dennis J. Baumgardner

    2017-01-01

    Full Text Available Fungal infections as a result of freshwater exposure or trauma are fortunately rare. Etiologic agents are varied, but commonly include filamentous fungi and Candida. This narrative review describes various sources of potential freshwater fungal exposure and the diseases that may result, including fungal keratitis, acute otitis externa and tinea pedis, as well as rare deep soft tissue or bone infections and pulmonary or central nervous system infections following traumatic freshwater exposure during natural disasters or near-drowning episodes. Fungal etiology should be suspected in appropriate scenarios when bacterial cultures or molecular tests are normal or when the infection worsens or fails to resolve with appropriate antibacterial therapy.

  11. Exploring Freshwater Science

    Indian Academy of Sciences (India)

    Freshwater ecosystems and associated habitats harbor incrediblebiodiversity. They offer various ecosystem services andsustain human livelihoods. However, due to increasing developmentalpressure and rising water demand, these systemsare under huge threat. As a result, many aquatic species arefeared to become ...

  12. Ancient DNA from lake sediments: Bridging the gap between paleoecology and genetics

    Directory of Open Access Journals (Sweden)

    Lumibao Candice Y

    2011-01-01

    Full Text Available Abstract Background Quaternary plant ecology in much of the world has historically relied on morphological identification of macro- and microfossils from sediments of small freshwater lakes. Here, we report new protocols that reliably yield DNA sequence data from Holocene plant macrofossils and bulk lake sediment used to infer ecological change. This will allow changes in census populations, estimated from fossils and associated sediment, to be directly associated with population genetic changes. Results We successfully sequenced DNA from 64 samples (out of 126 comprised of bulk sediment and seeds, leaf fragments, budscales, and samaras extracted from Holocene lake sediments in the western Great Lakes region of North America. Overall, DNA yields were low. However, we were able to reliably amplify samples with as few as 10 copies of a short cpDNA fragment with little detectable PCR inhibition. Our success rate was highest for sediments Conclusions An ability to extract ancient DNA from Holocene sediments potentially allows exciting new insights into the genetic consequences of long-term environmental change. The low DNA copy numbers we found in fossil material and the discovery of multiple sequence variants from single macrofossil extractions highlight the need for careful experimental and laboratory protocols. Further application of these protocols should lead to better understanding of the ecological and evolutionary consequences of environmental change.

  13. Re-Os geochronology of a Mesoproterozoic sedimentary succession, Taoudeni basin, Mauritania: Implications for basin-wide correlations and Re-Os organic-rich sediments systematics

    Science.gov (United States)

    Rooney, Alan D.; Selby, David; Houzay, Jean-Pierre; Renne, Paul R.

    2010-01-01

    The exceptionally well-preserved sedimentary rocks of the Taoudeni basin, NW Africa represent one of the world's most widespread (> 1 M km 2) Proterozoic successions. Hitherto, the sedimentary rocks were considered to be Mid Tonian based on Rb-Sr illite and glauconite geochronology of the Atar Group. However, new Re-Os organic-rich sediment (ORS) geochronology from two drill cores indicates that the Proterozoic Atar Group is ˜ 200 Ma older (1107 ± 12 Ma, 1109 ± 22 Ma and 1105 ± 37 Ma). The Re-Os geochronology suggests that the Rb-Sr geochronology records the age of diagenetic events possibly associated with the Pan African collision. The new Re-Os geochronology data provide absolute age constraints for recent carbon isotope chemostratigraphy which suggests that the Atar Group is Mesoproterozoic and not Neoproterozoic. The new Re-Os ORS geochronology supports previous studies that suggest that rapid hydrocarbon generation (flash pyrolysis) from contact metamorphism of a dolerite sill does not significantly disturb the Re-Os ORS systematics. Modelled contact conditions suggest that the Re-Os ORS systematics remain undisturbed at ˜ 650 °C at the sill/shale contact and ≥ 280 °C 20 m from the sill/shale contact. Moreover, the Re-Os geochronology indicates that the West African craton has a depositional history that predates 1100 Ma and that ORS can be correlated on a basin-wide scale. In addition, the Re-Os depositional ages for the ORS of the Taoudeni basin are comparable to those of ORS from the São Francisco craton, suggesting that these cratons are correlatable. This postulate is further supported by identical Os i values for the Atar Group and the Vazante Group of the São Francisco craton.

  14. Biological processes influencing contaminant release from sediments

    International Nuclear Information System (INIS)

    Reible, D.D.

    1996-01-01

    The influence of biological processes, including bioturbation, on the mobility of contaminants in freshwater sediments is described. Effective mass coefficients are estimated for tubificid oligochaetes as a function of worm behavior and biomass density. The mass transfer coefficients were observed to be inversely proportional to water oxygen content and proportional to the square root of biomass density. The sediment reworking and contaminant release are contrasted with those of freshwater amphipods. The implications of these and other biological processes for contaminant release and i n-situ remediation of soils and sediments are summarized. 4 figs., 1 tab

  15. Preliminary Studies on the Occurrence of Freshwater Epipelic Algae ...

    African Journals Online (AJOL)

    The occurrence and composition of the freshwater algae in the epipelon were determined at three sites, namely Machigeni, Manhean and Weija, located in the coastal savanna thicket and grassland vegetation zone of the River Densu basin in southern Ghana. Samples of sediments from the water-substratum interface ...

  16. Fern spore longevity in saline water: can sea bottom sediments maintain a viable spore bank?

    NARCIS (Netherlands)

    Groot, de G.A.; During, H.

    2013-01-01

    Freshwater and marine sediments often harbor reservoirs of plant diaspores, from which germination and establishment may occur whenever the sediment falls dry. Therewith, they form valuable records of historical interand intraspecific diversity, and are increasingly exploited to facilitate diversity

  17. Ex situ treatment of sediments with granular activated carbon : a novel remediation technology

    NARCIS (Netherlands)

    Rakowska, M.I.

    2014-01-01

    Over the last decades, industrial and urban development and emisions of many hazardous organic compounds have threatened the ecological quality of marine and freshwater sediments. Sediments accumulate hydrophobic organic compounds (HOCs) such as polycyclic aromatic hydrocarbons (PAHs),

  18. Freshwater and fish

    International Nuclear Information System (INIS)

    Saxen, R.

    1997-01-01

    Severe radioactive contamination of the freshwater environment could have serious consequences for both drinking water and fish. Most of the Nordic countries have an abundance of freshwater lakes and rivers. Finland alone has about 56,000 lakes, each with a surface area of 1 hectare or more. Nearly 10% of Finland's surface is covered with lakes and rivers. In Sweden, about 9% of the surface area is freshwater, in Norway about 5%, and in Denmark only about 2%. Freshwater plays a minor role in Iceland, but even there numerous rivers discharge from the volcanic soils to the Ocean. Cs-137 and 90 Sr are likely to be the most important radionuclides with respect to long term radioactive contamination of freshwater. If radioactive deposition occurs in the absence of snow and ice radionuclides will contaminate the surface water directly and may rapidly enter the aquatic food chain. Fish which eat contaminated plankton become contaminated almost immediately. Deposition during summer increases the transfer for radionuclides to fish since fish metabolism is faster during the warm season. During the cold period, fish metabolism is slow and thus uptake and excretion of radiocaesium are also slow. (EG)

  19. Freshwater Megafauna: Flagships for Freshwater Biodiversity under Threat.

    Science.gov (United States)

    Carrizo, Savrina F; Jähnig, Sonja C; Bremerich, Vanessa; Freyhof, Jörg; Harrison, Ian; He, Fengzhi; Langhans, Simone D; Tockner, Klement; Zarfl, Christiane; Darwall, William

    2017-10-01

    Freshwater biodiversity is highly threatened and is decreasing more rapidly than its terrestrial or marine counterparts; however, freshwaters receive less attention and conservation investment than other ecosystems do. The diverse group of freshwater megafauna, including iconic species such as sturgeons, river dolphins, and turtles, could, if promoted, provide a valuable tool to raise awareness and funding for conservation. We found that freshwater megafauna inhabit every continent except Antarctica, with South America, Central Africa, and South and Southeast Asia being particularly species rich. Freshwater megafauna co-occur with up to 93% of mapped overall freshwater biodiversity. Fifty-eight percent of the 132 megafauna species included in the study are threatened, with 84% of their collective range falling outside of protected areas. Of all threatened freshwater species, 83% are found within the megafauna range, revealing the megafauna's capacity as flagship and umbrella species for fostering freshwater conservation.

  20. Escape Burrowing of Modern Freshwater Bivalves as a Paradigm for Escape Behavior in the Devonian Bivalve Archanodon catskillensis

    Directory of Open Access Journals (Sweden)

    Katja Knoll

    2017-10-01

    Full Text Available Many freshwater bivalves restore themselves to the sediment water interface after burial by upward escape burrowing. We studied the escape burrowing capacity of two modern unionoids, Elliptio complanata and Pyganodon cataracta and the invasive freshwater venerid Corbicula fluminea, in a controlled laboratory setting varying sediment grain size and burial depth. We found that the relatively streamlined E. complanata is a better escape burrower than the more obese P. cataracta. E. complanata is more likely to escape burial in both fine and coarse sand, and at faster rates than P. cataracta. However, successful escape from 10 cm burial, especially in fine sand, is unlikely for both unionoids. The comparatively small and obese C. fluminea outperforms both unionoids in terms of escape probability and escape time, especially when body size is taken into consideration. C. fluminea can escape burial depths many times its own size, while the two unionoids rarely escape from burial equivalent to the length of their shells. E. complanata, and particularly P. cataracta, are morphological paradigms for the extinct Devonian unionoid bivalve Archanodon catskillensis, common in riverine facies of the Devonian Catskill Delta Complex of the eastern United States. Our observations suggest that the escape burrowing capability of A. catskillensis was no better than that of P. cataracta. Archanodon catskillensis was likely unable to escape burial of more than a few centimeters of anastrophically deposited sediment. The long (up to 1 meter, vertical burrows that are associated with A. catskillensis, and interpreted to be its escape burrows, represent a response to episodic, small-scale sedimentation events due to patterns of repetitive hydrologic or weather-related phenomena. They are not a response to a single anastrophic event involving the influx of massive volumes of sediment.

  1. Effects of pollution on freshwater fish

    International Nuclear Information System (INIS)

    McKim, J.M.; Benoit, D.A.; Biesinger, K.E.; Brungs, W.A.; Siefert, R.E.

    1975-01-01

    A review is presented on the effects of pollutants (metal, pesticides, detergents, and industrial and domestic wastes) and water quality parameters (oxygen and pH) on freshwater fish. Methods for the quantitation of PCB, DDT and various elements in fish samples are reviewed. A discussion is given on the response of fish to whole body irradiation with fast neutrons or x radiation, tritium and 14 C uptake rates, and effects of ionizing radiation on embryos and larval stages of fish. Other pollutants, such as ground motions from nuclear detonations, increase in five sediments (due to logging and road construction) and aflatoxins are discussed

  2. Freshwater autotrophic picoplankton: a review

    Directory of Open Access Journals (Sweden)

    John G. STOCKNER

    2002-02-01

    Full Text Available Autotrophic picoplankton (APP are distributed worldwide and are ubiquitous in all types of lakes of varying trophic state. APP are major players in carbon production in all aquatic ecosystems, including extreme environments such as cold ice-covered and/or warm tropical lakes and thermal springs. They often form the base of complex microbial food webs, becoming prey for a multitude of protozoan and micro-invertebrate grazers, that effectively channel APP carbon to higher trophic levels including fish. In this review we examine the existing literature on freshwater autotrophic picoplankton, setting recent findings and current ecological issues within an historic framework, and include a description of the occurrence and distribution of both single-cell and colonial APP (picocyanobacteria in different types of lakes. In this review we place considerable emphasis on methodology and ecology, including sampling, counting, preservation, molecular techniques, measurement of photosynthesis, and include extensive comment on their important role in microbial food webs. The model outlined by Stockner of an increase of APP abundance and biomass and a decrease of its relative importance with the increase of phosphorus concentration in lakes has been widely accepted, and only recently confirmed in marine and freshwater ecosystems. Nevertheless the relationship which drives the APP presence and importance in lakes of differing trophic status appears with considerable variation so we must conclude that the success of APP in oligotrophic lakes worldwide is not a certainty but highly probable.

  3. Palynostratigraphy, palynofacies and depositional environment of a lignite-bearing succession at Surkha Mine, Cambay Basin, north-western India

    Directory of Open Access Journals (Sweden)

    Monga Priyanka

    2015-12-01

    Full Text Available The paper reports palynology and palynofacies studies of lignite-bearing sediments exposed in an opencast mine succession at Surkha, Bhavnagar District, in the coastal region of Gujarat, India. The study examined the relationships between the palynoflora, sedimentary organic matter and environment at the time of deposition of lignite and associated sediments. Based on dinoflagellate cyst biostratigraphy, the sedimentary succession is dated as early Eocene (Ypresian. Palynofacies studies helped reveal the palaeoenvironmental fluctuations. The dominance of angiosperm pollen grains, freshwater algae, microthyraceous fungi and a large share of land debris in the lower part of the succession suggests a freshwater swamp environment of deposition for the basal lignite facies. Two cenozones - Matanomadiasulcites maximus and Lakiapollis ovatus - were identified in the lower lignite facies, determined from the dominance of these pollen grains in the palynological assemblages. The presence of angiosperm pollen grains and pteridophyte spores in the carbonaceous shale horizon above the lignite facies indicates a change in the depositional regime from freshwater swamp to lagoonal. This was identified as the Arecipites wodehousei cenozone due to its numerical abundance in the assemblage. Dinoflagellate cyst abundance and diversity, and microforaminiferal test linings along with well-sorted terrestrial debris in the mudstone in the upper part of the succession suggest a more open marine estuarine type of depositional environment. The Homotryblium complex along with Cordospheridium fibrospinosum, Kenleyia sp., and Thalassiphora pelagica dinoflagellate cysts are the main representatives of this zone, determined as the Homotryblium tenuispinosum cenozone. The changing depositional settings (freshwater swamp-lagoonal-estuarine along the vertical succession indicate a marine transgression in this region. Results from palynological studies of early Palaeogene

  4. Distribution and diversity of gallionella-like neutrophilic iron oxidizers in a tidal freshwater marsh

    NARCIS (Netherlands)

    Wang, J.; Vollrath, S.; Behrends, T.; Bodelier, P.L.E.; Muyzer, G.; Den Oudsten, F.; Meima-Franke, M.; Cappellen, P.; Laanbroek, H.J.

    2011-01-01

    Microbial iron oxidation is an integral part of the iron redox cycle in wetlands. Nonetheless, relatively little is known about the composition and ecology of iron-oxidizing communities in the soils and sediments of wetlands. In this study, sediment cores were collected across a freshwater tidal

  5. Distribution and diversity of Gallionella-like neutrophilic iron oxidizers in a tidal freshwater marsh

    NARCIS (Netherlands)

    Wang, J.; Vollrath, S.; Behrends, T.; Bodelier, P.L.E.; Muyzer, G.; Meima-Franke, M.; den Oudsten, F.; van Cappellen, P.; Laanbroek, H.J.

    2011-01-01

    Microbial iron oxidation is an integral part of the iron redox cycle in wetlands. Nonetheless, relatively little is known about the composition and ecology of iron-oxidizing communities in the soils and sediments of wetlands. In this study, sediment cores were collected across a freshwater tidal

  6. Contrasting oxygen dynamics in the freshwater isoetid Lobelia dortmanna and the marine seagrass Zostera marina

    DEFF Research Database (Denmark)

    Sand-Jensen, Kaj; Pedersen, Ole; Binzer, Thomas

    2005-01-01

    of the sediment, and aquatic plants differ in aerenchymal volume and resistance to O2 diffusion through the plant and across leaf and root surfaces. The hypothesis that the freshwater isoetid Lobelia dortmanna and the marine seagrass Zostera marina should display pronounced contrasts in intra-plant O2 dynamics....... marina appear to represent a general difference between the isoetid species mainly inhabiting sediments of low reducing capacity of oligotrophic lakes and the elodeid freshwater species and marine seagrasses mainly inhabiting sediments of higher reducing capacity in more nutrient-rich habitats....

  7. CROATIAN FRESHWATER FISHERY

    Directory of Open Access Journals (Sweden)

    Višnja Knjaz

    2007-07-01

    Full Text Available The basic characteristics of freshwater fishery in Croatia are predominantly negative trend in the past twenty years. Even though the total fish pond area covers more than 12,000 hectares, only 6,200 hectares of carp ponds and 58,700 m2 of trout ponds have been exploited. In 2006 the production of total freshwater fish reached 6,547 tons, out of which the production of consumable fish amounted to 5,067 tons and the juveniles 1,480 tons. The export of freshwater fish to EU countries, Macedonia, Bosnia and Herzegovina, Serbia and Monte Negro shows the positive trend and the Republic of Croatia continuously records a foreign trade surplus (987,000 US$. It must be pointed out, though, that the import of trout from Bosnia and Herzegovina significantly increased in the past three years which resulted in the decrease of the foreign trade surplus in that sector. The freshwater fishery in Croatia has been overly burdened by many problems

  8. Reclaiming freshwater sustainability in the Cadillac Desert

    Science.gov (United States)

    Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H.W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

    2010-01-01

    Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%.

  9. Biomonitoring aquatic pollution with feral eel (Anguilla anguilla): I. Bioaccumulation: biota-sediment ratios of PCBs, OCPs, PCDDs and PCDFs.

    NARCIS (Netherlands)

    van der Oost, R.; Opperhuizen, A.; Satumalay, K.; Heida, H.; Vermeulen, N.P.E.

    1996-01-01

    Samples of sediments and eel taken from six Amsterdam freshwater sites were analyzed for polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs). Biota-sediment accumulation factors (BSAFs) were

  10. Microplastic Effect Thresholds for Freshwater Benthic Macroinvertebrates

    Science.gov (United States)

    2018-01-01

    Now that microplastics have been detected in lakes, rivers, and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates with different species traits, using a wide range of microplastic concentrations. Standardized 28 days single species bioassays were performed under environmentally relevant exposure conditions using polystyrene microplastics (20–500 μm) mixed with sediment at concentrations ranging from 0 to 40% sediment dry weight (dw). Microplastics caused no effects on the survival of Gammarus pulex, Hyalella azteca, Asellus aquaticus, Sphaerium corneum, and Tubifex spp. and no effects were found on the reproduction of Lumbriculus variegatus. No significant differences in growth were found for H. azteca, A. aquaticus, S. corneum, L. variegatus, and Tubifex spp. However, G. pulex showed a significant reduction in growth (EC10 = 1.07% sediment dw) and microplastic uptake was proportional with microplastic concentrations in sediment. These results indicate that although the risks of environmentally realistic concentrations of microplastics may be low, they still may affect the biodiversity and the functioning of aquatic communities which after all also depend on the sensitive species. PMID:29337537

  11. The biological transport of radionuclides in grassland and freshwater ecosystems

    International Nuclear Information System (INIS)

    Rudge, S.A.

    1989-12-01

    This thesis examines the biological transport of radionuclides through terrestrial and aquatic ecosystems, with particular reference to radiocaesium. The semi-natural grassland habitat was located at Drigg, W. Cumbria, contaminated primarily by radioactive fallout, from several sources over the past decade. Advantage was made of the deposition of radionuclides from the Chernobyl reactor incident, which occurred during the early stages of the investigation. The study examined the distribution of radiocaesium for the major components of the grassland ecosystem, within the soil-plant-invertebrate-small mammal food chain. Data concerning temporal fluctuation of radionuclide transfer factors between food chain components are presented. The final section examines the spatial distribution of radiocaesium in sediment and the freshwater eel (Anguilla anguilla) in a small stream contaminated by radioactive effluent. The relationship between activity levels in eels and the sediments in which they rest and forage was investigated. Factors influencing uptake of radiocaesium in freshwater fish were also examined. (author)

  12. DISTRIBUTION OF HEAVY METALS AMONG THE COMPONENTS OF FRESHWATER ECOSYSTEMS (REVIEW)

    OpenAIRE

    N. Kolesnyk

    2014-01-01

    Purpose. To review scientific sources on the distribution of heavy metals among the components of freshwater ecosystems. Findings. The review of the works of many scientists showed that heavy metals are widespread in the biotic and abiotic components of freshwater ecosystems. The article highlights the distribution of heavy metals in water, bottom sediments, natural food base, fish organs and tissues. It has been shown that as a result of global pollution of the ecosystem, the majority of...

  13. Designing Observation and Modeling Systems to Inform Decisions and Policies on Freshwater Objectives in New Zealand

    Science.gov (United States)

    Baisden, W. T.; Ellis, T.; Rissman, C.; Moore, C.; Matthews, A.

    2016-12-01

    Declines in New Zealand's freshwater quality have led to legislation - the 2014 National Policy Statement on Freshwater Management (NPS-FM) - which requires regional governments to set "objectives" and design policies accordingly. In most regions, increases in freshwater contaminants are derived largely from intensifying agriculture and come as nitrogen, phosphorous or sediment, or a combination thereof. Here, the development and application of N and O isotopes as natural tracers for nitrate is examined as a case study, in the context of a wider hierarchy of observations such as N concentrations, flow and broader hydrochemistry used for NPS-FM implementation. The analysis of N and O isotopes in nitrate provides specific information on sources and removal processes that cannot be obtained by other measurements. Yet, despite considerable development of the technical methodology and environment-specific interpretation, application of measurements has faced barriers. Many may be typical of science in a small advanced nation with a population of 4.5 million, but others are unique due to New Zealand's limited rural population base and large diversity in physical geography, as well as a unique economic reliance on highly productive pastoral agricultural systems. Seventeen different regional governments are empowered to regulate in ways consistent with local consultation and democracy within their catchment boundaries, but with limited resources to align highly technical observational data to policies and decisions, as well as supporting models. The resulting gaps in communication and technical capability combine with a diversity of approaches to pose both challenges and opportunities for development and application of hierarchical observation systems. Success appears to lie in ensuring decision frameworks can be `mapped', so that different frameworks can be compared, and the benefits of sophisticated observations understood directly in relation to influence on regional

  14. Adjustment of the San Francisco estuary and watershed to decreasing sediment supply in the 20th century

    Science.gov (United States)

    Schoellhamer, David H.; Wright, Scott A.; Drexler, Judith Z.

    2013-01-01

    The general progression of human land use is an initial disturbance (e.g., deforestation, mining, agricultural expansion, overgrazing, and urbanization) that creates a sediment pulse to an estuary followed by dams that reduce sediment supply. We present a conceptual model of the effects of increasing followed by decreasing sediment supply that includes four sequential regimes, which propagate downstream: a stationary natural regime, transient increasing sediment supply, transient decreasing sediment supply, and a stationary altered regime. The model features characteristic lines that separate the four regimes. Previous studies of the San Francisco Estuary and watershed are synthesized in the context of this conceptual model. Hydraulic mining for gold in the watershed increased sediment supply to the estuary in the late 1800s. Adjustment to decreasing sediment supply began in the watershed and upper estuary around 1900 and in the lower estuary in the 1950s. Large freshwater flow in the late 1990s caused a step adjustment throughout the estuary and watershed. It is likely that the estuary and watershed are still capable of adjusting but further adjustment will be as steps that occur only during greater floods than previously experienced during the adjustment period. Humans are actively managing the system to try to prevent greater floods. If this hypothesis of step changes occurring for larger flows is true, then the return interval of step changes will increase or, if humans successfully control floods in perpetuity, there will be no more step changes.

  15. Core sediment biogeochemistry in specific zones of Cochin ...

    Indian Academy of Sciences (India)

    land and ocean, where seawater is measurably diluted by the inflow of freshwater (Hobbie 2000). .... lignin were batch-extracted from the sediments with 0.05 M NaOH solution for 90 minutes and fil- tered. ...... metal accumulation in the sediments of the Cochin Estu- ary – Southwest coast of India; Environ. Monit. Assess.,.

  16. Mangroves and sediment dynamics along the coasts of southern Thailand

    NARCIS (Netherlands)

    Thampanya, U.

    2006-01-01

    Mangroves inhabit tropical coastlines and are particularly abundant along deltas and bays where rivers bring freshwater and sediment to the sea. This habitat witnesses great variability in sedimentation and erosion rates, partly governed by variation in hydrodynamics of rivers as well as the sea.

  17. The Zoogeography of North American freshwater fishes

    National Research Council Canada - National Science Library

    Hocutt, Charles H; Wiley, E. O

    1986-01-01

    ..., and Pleistoscene glaciation. The Zoogeography of North American Freshwater Fishes is a comprehensive treatment of the freshwater biogeography of North America, with implications for other disciplines...

  18. Metal bioavailability in ecological risk assessment of freshwater ecosystems: From science to environmental management.

    Science.gov (United States)

    Väänänen, Kristiina; Leppänen, Matti T; Chen, XuePing; Akkanen, Jarkko

    2018-01-01

    Metal contamination in freshwater ecosystems is a global issue and metal discharges to aquatic environments are monitored in order to protect aquatic life and human health. Bioavailability is an important factor determining metal toxicity. In aquatic systems, metal bioavailability depends on local water and sediment characteristics, and therefore, the risks are site-specific. Environmental quality standards (EQS) are used to manage the risks of metals in aquatic environments. In the simplest form of EQSs, total concentrations of metals in water or sediment are compared against pre-set acceptable threshold levels. Now, however, the environmental administration bodies have stated the need to incorporate metal bioavailability assessment tools into environmental regulation. Scientific advances have been made in metal bioavailability assessment, including passive samplers and computational models, such as biotic ligand models (BLM). However, the cutting-edge methods tend to be too elaborate or laborious for standard environmental monitoring. We review the commonly used metal bioavailability assessment methods and introduce the latest scientific advances that might be applied to environmental management in the future. We present the current practices in environmental management in North America, Europe and China, highlighting the good practices and the needs for improvement. Environmental management has met these new challenges with varying degrees of success: the USA has implemented site-specific environmental risk assessment for water and sediment phases, and they have already implemented metal mixture toxicity evaluation. The European Union is promoting the use of bioavailability and BLMs in ecological risk assessment (ERA), but metal mixture toxicity and sediment phase are still mostly neglected. China has regulation only for total concentrations of metals in surface water. We conclude that there is a need for (1) Advanced and up-to-date guidelines and legislation

  19. PROCEDURES FOR THE DERIVATION OF EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: COMPENDIUM OF TIER 2 VALUES FOR NONIONIC ORGANICS

    Science.gov (United States)

    This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations for 32 nonionic organic chemicals in sediment which are protective of the presence of freshwater and marine benthic organisms. The equilibrium partitioning (EqP) approach...

  20. Petrology and provenance of the Neogene fluvial succession in Pishin Belt (Katawaz Basin) western Pakistan: Implications for sedimentation in peripheral forelands basins

    DEFF Research Database (Denmark)

    Kasi, Aimal Khan; Kassi, Aktar Muhammad; Friis, Henrik

    2017-01-01

    Sandstones and conglomerates of the Neogene fluvial succession in Pishin Belt (Katawaz Basin), Pakistan were studied for the first time to understand the composition, provenance and tectonic settings of the source areas. Sandstones of the Miocene Dasht Murgha Group and Pliocene Malthanai Formation...

  1. Ecotoxicity of engineered nanoparticles to freshwater organisms

    DEFF Research Database (Denmark)

    Hartmann, Nanna Isabella Bloch

    A large variety of societal benefits are expected from the development and use of engineered nanoparticles. At present, the majority of ‘nano-products’ put on the market can be classified as consumer products, whereas future applications are expected to have more widespread and societal benefits...... in relation to appropriate test methods for identifying potential adverse effects of nanoparticles; this is of great relevance from both a scientific and regulatory point of view. An important aspect of this project was the acquisition of experience in testing nanoparticles in aqueous test systems – both...... with freshwater filter feeder Daphnia magna, sediment feeder Lumbriculus variegatus and green alga Pseudokirchneriella subcapitata. The results made it possible to identify major scientific and methodological challenges in the testing of nanoparticles compared to ‘conventional’ chemicals. It has been highlighted...

  2. COMMUNITY DEVELOPMENT IN FRESHWATER MICROCOSMS

    Energy Technology Data Exchange (ETDEWEB)

    Rees, John T.

    1978-01-01

    Two cylindrical freshwater microcosms with a volume of 700 {ell} were maintained under controlled laboratory conditions for 190 days. The two microcosms were identical with regard to initial chemical composition and biological inocula, with the exceptions that in one microcosm (designated Tank 2) mosquitofish (Gambusia) and herbivorous catfish (Placostomas) were added. Three distinct communities developed in the tanks: (1) a phytoplankton-zooplankton assemblage and (2) two periphyton-zoobenthos communities associated with the sides and bottom of the tank, respectively. Community development and successional patterns were similar in both tanks. Major differences between the tanks involved timing of succession of the zooplankton and zoobenthos, attributable to predation by fish, principally Gambusia. A major drawback for these microcosms as use for experimental analogs such as lakes was a luxuriant periphyton growth which eventually overwhelmed the biomass of the system. The tanks displayed a degree of successional replicability, a large number of species, and a diversity of community development. Microcosms of this size could find use as experimental systems for higher level trophic manipulation and observation of life cycles not amenable to field studies.

  3. Design of a marine sediment trap and accessories

    Digital Repository Service at National Institute of Oceanography (India)

    Janakiraman, G.; Fernando, V.; Venkatesan, R.; Rajaraman, V.S.

    The marine sediment trap and the mooring accessories were developed indigenously and were used successfully for the collection of settling sediments in the Arabian Sea The experience gained in using sediment trap and further improvements...

  4. Biodiversity of streptomycetes isolated from a succession sequence at a post-mining site and their evidence in Miocene lacustrine sediment

    Czech Academy of Sciences Publication Activity Database

    Chroňáková, Alica; Krištůfek, Václav; Tichý, Martin; Elhottová, Dana

    2010-01-01

    Roč. 165, č. 7 (2010), s. 594-608 ISSN 0944-5013 R&D Projects: GA AV ČR IAA600660607; GA ČR GA526/03/1259; GA MŠk LC06066; GA MŠk 2B06154 Grant - others:GAJU(CZ) 54/2004/P-BF Institutional research plan: CEZ:AV0Z60660521; CEZ:AV0Z50200510 Keywords : actinomycetes * antibiotics * primary succession Subject RIV: EH - Ecology, Behaviour Impact factor: 1.958, year: 2010

  5. Sediment Biogeochemistry After the Entrance of Cable Bacteria

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils

    , sulfide-rich coastal sediments, salt marshes seasonally hypoxic basins, subtidal coastal mud plains, as well as freshwater sediments and waterlogged soils. In this talk I will review our current knowledge on how cable bacteria influence the biogeochemistry of sediments. The cable bacteria form electric...... fields which may strongly modify ionic transports. They form pH extremes, and accelerate the dissolution of iron sulfides, and carbonates in subsurface sediment. They further promote the formation of iron oxides and carbonates at the sediment surface and stimulate the removal of sulfides...

  6. Contaminants in the Greenland terrestrial and freshwater environment. National assessment

    International Nuclear Information System (INIS)

    Riget, F.; Aastrup, P.; Dietz, R.

    1997-01-01

    The present report reviews the available information on heavy metals, persistent organic pollutants and radioactivity in the Greenland freshwater and terrestrial environments. Levels in lake sediments, soil, humus and organisms are presented, spatial and temporal trends are discussed and where possible also biological effects. Many of the contaminants that occur in the Greenland environment originate from distant sources outside of the region, and are transported to the Arctic via three major pathways - atmospheric, terrestrial/freshwater and marine. The main sources of pollution in Greenland is considered to be the industrialization of Eurasia. Pollutants are mainly. The organochlorine levels in Greenland char are typically in the low range compared to values reported from Canada. The Greenland sediment samples showed all organochlorine values below the detection limits of 0.1 μg/kg dry weight, thus being among the lowest contaminated sediments within the Arctic. The total content of PAH in the Greenland sediment samples ranged between 78-635 μ3 g/kg dry wight, with a geometric mean of 178 μg/kg, comparable to or lower than reported values from other arctic countries. The lowest concentrations of anthropogenic radionuclides in the Greenland terrestrial and freshwater environment are found in the northern parts of Greenland and the highest in the south western parts. The main source of anthropogenic radioactivity is nuclear weapons testing in the atmosphere and the fallout from this activity is closely related to the amounts of precipitation. The predominant foodchain in the Arctic with regard to transport of radiocaesium to man is: Lichen-reindeer-man. Although the doses from the terrestrial foodchain are 20 times higher than those received from the marine foodchain, they are not considered to be of any relevance for the human health in Greenland. 4 appendices contain experimental results. (EG)

  7. Freshwater Treatment and Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Freshwater Treatment and Test Facility, located at SANGB, has direct year-round access to water from Lake St. Clair and has a State of Michigan approved National...

  8. Freshwater mussel response to bedform movement: experimental stream studies

    Science.gov (United States)

    Kozarek, J. L.; MacGregor, K. R.; Hornbach, D.; Hove, M.

    2017-12-01

    Freshwater mussels are intrinsically linked to near-bed sediment dynamics, but it remains unclear how mussels respond to changing sediment loads across spatial and temporal scales. The interactions between mussels and sediment transport are complex and often involve feedback loops. Mussels are filter feeders removing suspended particles from the water column and the physical presence of mussels can have significant impacts on the structure of riverbed habitat. We investigated the feedbacks between mussels, flow, and migrating bedforms during flood experiments in the St. Anthony Falls Laboratory Outdoor StreamLab (OSL) at the University of Minnesota. The OSL is a field-scale sand-bed meandering stream channel with independent control over sediment feed (recirculated) and water flow (diverted from the Mississippi River). Mussel location, orientation to flow, and protrusion from sediment was surveyed immediately before, after, and one and two days after each flood event. Flow fields, bed shear stress, bedform migration, and bar topography were measured during each flooding event with and without mussels present (density = 4/m2 and 8/m2) to quantify the influence of mussels on channel morphology and bedform migration. Mobile bedforms (up to 14 cm high) were present for all flood events with quasi-equilibrium, aggrading, and degrading bed conditions. Mussels moved little horizontally during all flood events, but were shown to move quickly to deeper water after the flood receded. However, mussels moved vertically, burrowing or being buried under mobile bedforms, during each flood event. The research presented here will focus on feedbacks between three mussel species with different shell sculptures, flow conditions, and migrating bedforms during flooding events. These results reveal how freshwater mussels respond to and affect flow and sediment transport during flood events that are difficult to observe in the field.

  9. Salting our freshwater lakes

    Science.gov (United States)

    Bartlett, Sarah L.; Burke, Samantha M.; Doubek, Jonathan P.; Krivak-Tetley, Flora E.; Skaff, Nicholas K.; Summers, Jamie C.; Farrell, Kaitlin J.; McCullough, Ian M.; Morales-Williams, Ana M.; Roberts, Derek C.; Ouyang, Zutao; Scordo, Facundo; Hanson, Paul C.; Weathers, Kathleen C.

    2017-01-01

    The highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide. However, the extent to which lake salinity may be changing at broad spatial scales remains unknown, leading us to first identify spatial patterns and then investigate the drivers of these patterns. Significant decadal trends in lake salinization were identified using a dataset of long-term chloride concentrations from 371 North American lakes. Landscape and climate metrics calculated for each site demonstrated that impervious land cover was a strong predictor of chloride trends in Northeast and Midwest North American lakes. As little as 1% impervious land cover surrounding a lake increased the likelihood of long-term salinization. Considering that 27% of large lakes in the United States have >1% impervious land cover around their perimeters, the potential for steady and long-term salinization of these aquatic systems is high. This study predicts that many lakes will exceed the aquatic life threshold criterion for chronic chloride exposure (230 mg L−1), stipulated by the US Environmental Protection Agency (EPA), in the next 50 y if current trends continue. PMID:28396392

  10. Ammonia-oxidizing Bacteria and Archaea in the Rhizosphere of Freshwater Macrophytes

    DEFF Research Database (Denmark)

    Herrmann, Martina; Schramm, Andreas

    2007-01-01

    AMMONIA-OXIDIZING ARCHAEA AND BACTERIA IN THE RHIZOSPHERE OF FRESHWATER MACROPHYTES Martina Herrmann and Andreas Schramm Department of Biological Sciences, Microbiology, University of Aarhus, Denmark Aquatic macrophytes such as Littorella uniflora and Lobelia dortmanna release oxygen from...... their roots and thereby stimulate nitrification and coupled nitrification-denitrification in their rhizosphere. However, oxygen release and inorganic nitrogen concentrations differ markedly between macrophyte species. We therefore propose (i) that the rhizosphere of freshwater macrophytes harbours a species......-specific microbial community distinct from that of unvegetated sediment and (ii) that aquatic macrophytes have an impact on abundance and activity of nitrifying and denitrifying bacteria in freshwater sediment. The goal of this study was to test these hypotheses for the key functional group for coupled nitrification-denitrification...

  11. Resting cysts of freshwater dinoflagellates in southeastern Georgian Bay (Lake Huron) as proxies of cultural eutrophication

    DEFF Research Database (Denmark)

    McCarthy, Francine M.G.; Mertens, Kenneth Neil; Ellegaard, Marianne

    2011-01-01

    Resting cysts attributed to the freshwater dinoflagellate genus Peridinium were found in surface sediments from Severn Sound, southeastern Georgian Bay (Lake Huron, Laurentian Great Lakes of North America). Two distinct cyst morphotypes were present and they were assigned to Peridinium wisconsine...

  12. Reconstruction of Anacostia wetlands: success?

    Science.gov (United States)

    Hammerschlag, R.S.; Perry, M.C.

    2002-01-01

    Historically, the tidal Anacostia River in Washington, D.C. had been an extensive system of freshwater tidal marshes replete with a full array of wetland vegetation dominated by wild rice. The local Nacochtank Indians had found the abundant fish and wildlife sufficient to sustain their daily lives. White man's intrusion upon the landscape gradually brought about deterioration of the natural (and associated cultural) system. Total demise followed mid-20th century dredge and fill channelization, which was conducted from the confluence of the Anacostia with the Potomac near the heart of Washington, D.C. to the terminus of the tidal regime at Bladensburg, Maryland. The National Park Service (NPS) became the manager for much of the land along the Anacostia, particularly the eastern bank. As part of its planning effort, the NPS envisioned returning portions of the Anacostia under its control to a natural system as a vignette. The concept was based on bringing back as comprehensive a collection of vegetation and wildlife as possible through the reestablishment of tidal marshes at Kenilworth and Kingman. The resultant wetlands were to be made accessible to the public both logistically and through a well designed interpretative program. In fact, this vision has been realized due to an impressive cooperative effort among a number of Federal and local agencies and organizations. In 1993, 32 acres of freshwater tidal marsh were reconstructed at Kenilworth. Based upon the 5-year monitoring program that has been in place since reconstruction, several generalizations may be made concerning the degree of success of the marsh reconstruction. Water quality in the marsh system and nearby tidal waters has not been noticeably improved. The poor quality may be clue to the overwhelmingly high loads (e.g., sediment, nutrients, etc.) brought in on the twice daily tidal cycle from the Anacostia and to the relatively small volume of water which actually interacts with the emergent marsh

  13. [Geographic variations in freshwater molluscs].

    Science.gov (United States)

    Vinarskiĭ, M V

    2012-01-01

    The phenomenon of geographic variation is known in practically all taxa of living beings. However, the reality of this phenomenon in freshwater molluscs (snails and bivalves) has many times been questioned in the past. It was accepted that these animals do not demonstrate spatially-oriented variation, where specific "local race" is arisen in each specific habitat. Till the beginning of 1970s, there was no statistical evidence that geographic clines in freshwater molluscs really exist. However, a few species of freshwater molluscs has been studied in this respect so far, therefore it is almost impossible to draw any general patterns of geographical variation in this group of animals. Most species of freshwater molluscs studied to the date exhibit statistically significant decrease of their body size in the south-north direction. Perhaps, it may be explained by decrease of the duration of the growth season in high latitudes. Some species of freshwater snails demonstrate clinal changes in shell proportions. This allows to reject subspecies separation within these species since diagnostic characters of such "subspecies" may blur when geographic variation is taken into consideration. The data on geographic variation in anatomical traits in freshwater molluscs is much more scarce. At least one species of pond snails (Lymnaea terebra) demonstrates clinal variation in proportions of the copulative apparatus in the south-north direction. Further studies of geographic variation in freshwater molluscs should reveal whether it is truly adaptive, i.e. whether geographical clines have underlying genetic basis. Otherwise, the clines may arise as a result of direct modifying effect of a habitat.

  14. Desalination - an alternative freshwater resource

    International Nuclear Information System (INIS)

    Shakaib, M.

    2005-01-01

    Global water constitutes 94 percent salt water that is from the oceans and 6% is in the form of freshwater. Out of this 6% freshwater approximately 27% is trapped in glaciers and 72% is underground. The sea water is important for transportation, fisheries. Oceans regulate climate through air sea interaction. However direct consumption of sea water is too salty to sustain human life. Water with a dissolved solids (salt) content generally below about 1000 milligrams per liter (mg/L) is considered acceptable for human consumption. The application of desalting technologies over the past 50 years have been in many of the arid zone where freshwater is available. Pakistan lies in the Sun Belt. It is considered a wide margin coastal belt (990 km), having an Exclusive Economic Zone of 240,000 km/sup 2/, that strokes trillion cubic meters of sea water that can be made available as freshwater source to meet the shortfall in the supply of domestic water through desalination along the coastal belt of Pakistan. The freshwater obtained from the other desalination processes is slightly expensive, but the cost of desalination can be considerably reduced provided that the available inexpensive or free waste energy is utilized mainly. (author)

  15. Practical aids for freshwater spill response

    International Nuclear Information System (INIS)

    Steen, A.E.; Walker, A.H.

    1993-01-01

    The current research program at API is focused on the environmental and human health effects from oil spills in freshwater habitats. Components of the program include lessons learned from spill response, development of decision-making protocols for the use of chemicals during initial response operations, preparation of a manual for spill response and contingency planning, and a review of the literature on environmental and human health effects from inland spills. API has reviewed past inland spill responses to identify lessons learned. A survey questionnaire has been developed to collect information from freshwater spill responders on their successes and difficulties in response operations. The questionnaire is tailored to focus on the impact to the operations from the absence of technical/scientific data on environmental effects or operation effectiveness/efficiency as well as to identify situations in which the use of particular response or cleanup options is likely to be effective. The questionnaires will be available at the Conference. Published case studies also will be examined for lessons-learned information. The results will be used to identify and prioritize API research needs in freshwater spill response. General concerns about the effectiveness of the toxicity associated with chemicals in spill response has prevented their use in fresh water. API has begun a detailed survey and interview process with state and federal regulatory personnel to identify their concerns and decision criteria to evaluate the use of chemicals in initial spill response. Ten classes of chemicals were identified for consideration: dispersants, shoreline cleaners, shoreline protection agents, herding agents, solidifiers, demulsifiers, emulsion inhibitors, foaming agents, oxidizing agents, and burning agents

  16. Freshwater discharge and sediment transport to Kangerlussuaq Fjord, West Greenland

    DEFF Research Database (Denmark)

    Mikkelsen, Andreas Peter Bech

    The main objectives of this PhD study have been to quantify the large-scale hydrological and geomorphological processes and implications related to three large proglacial rivers draining into Kangerlussuaq Fjord from the Greenland Ice Sheet (GrIS). These rivers are Watson, Umivit and Sarfartoq...... River. Hydrological processes studied are: proglacial discharge volumes and timing of this, creation of runoff (i.e. melt), storage and release features such as ice dammed lakes (jökulhlaups lakes), the role of supraglacial lakes, storage and release inside or beneath the ice and the role of the so...... surface albedo that amplified surface melt. This unprecedented amount of proglacial discharge would only be possible if the runoff was generated from the lower accumulation zone, where runoff is usually buffered by the air-filled pore space in the firn. This means that the water melted in the lower...

  17. Sediment Transport

    DEFF Research Database (Denmark)

    Liu, Zhou

    Flow and sediment transport are important in relation to several engineering topics, e.g. erosion around structures, backfilling of dredged channels and nearshore morphological change. The purpose of the present book is to describe both the basic hydrodynamics and the basic sediment transport...... mechanics. Chapter 1 deals with fundamentals in fluid mechanics with emphasis on bed shear stress by currents, while chapter 3 discusses wave boundary layer theory. They are both written with a view to sediment transport. Sediment transport in rivers, cross-shore and longshore are dealt with in chapters 2...

  18. Trophic transfer of metal nanoparticles in freshwater ecosystems

    DEFF Research Database (Denmark)

    Tangaa, Stine Rosendal

    Metal-containing engineered nanoparticles (Me-ENPs) are used in a wide range of products, such as inks, plastics, consumer products, lubricants, electronics and bioactive coatings. Silver (Ag) ENPs are one of the most used Me-ENPs to date, primarily due to its antibacterial effects. When entering...... was examined. The biodynamic modelling approach was used to characterize Ag uptake from the two different uptake routes as well as to describe the elimination of Ag after waterborne exposures to the two Ag-forms. Thirdly, trophic transfer of silver Ag ENPs in a simple freshwater food web, including sediment...

  19. Distribution of transuranic elements in a freshwater pond ecosystem

    International Nuclear Information System (INIS)

    Emery, R.M.; Klopfer, D.C.

    1975-05-01

    Preliminary results are reported from a study initiated on the Hanford Reservation concerning the ecological behavior of 238 Pu, 239 Pu, 240 Pu, and 241 Am in a freshwater environment. This study involves a waste pond which has been receiving Pu processing wastes for about 30 years. The pond has a sufficiently established ecosystem to provide an excellent location for limnological characterization. In addition, the ecological distribution of Pu and Am was investigated. The pond is also highly enriched with nutrients, thus supporting a high level of algal and macrophyte production. Seston (30 percent diatoms) appears to be the principal concentrators of Pu transuranics in the pond system. The major sink for Pu and Am in this system is the sediments. Organic floc, overlaying the pond sediments, is also a major concentrator of transuranics in this system []Aside from the seston and floc, no other ecological components of the pond appear to have concentrations significantly greater than those of the sediment. Dragonfly, larvae, watercress, and snails show concentrations which approximate those of the sediments but nearly all other food web components have levels of Pu and Am which are lower than those of the sediments, thus, Pu and Am seem to be relatively immobile in the aquatic ecosystem. (CH)

  20. Nucleopolyhedrovirus detection and distribution in terrestrial, freshwater, and marine habitats of Appledore Island, Gulf of Maine.

    Science.gov (United States)

    Hewson, Ian; Brown, Julia M; Gitlin, Shari A; Doud, Devin F

    2011-07-01

    Viruses in aquatic ecosystems comprise those produced by both autochthonous and allochthonous host taxa. However, there is little information on the diversity and abundance of viruses of allochthonous origin, particularly from non-anthropogenic sources, in freshwater and marine ecosystems. We investigated the presence of nucleopolyhedroviruses (NPV) (Baculovirus), which commonly infect terrestrial lepidopteran taxa, across the landscape of Appledore Island, Gulf of Maine. PCR and qPCR primers were developed around a 294-bp fragment of the polyhedrin (polH) gene, which is the major constituent protein of NPV multivirion polyhedral occlusion bodies. polH was successfully amplified from several aquatic habitats, and recovered polH sequences were most similar to known lepidopteran NPV. Using quantitative PCR designed around a cluster of detected sequences, we detected polH in Appledore Island soils, supratidal freshwater ponds, nearshore sediments, near- and offshore plankton, and in floatsam. This diverse set of locations suggests that NPVs are widely dispersed along the terrestrial--marine continuum and that free polyhedra may be washed into ponds and eventually to sea. The putative hosts of detected NPVs were webworms (Hyphantria sp.) which form dense nests in late summer on the dominant Appledore Island vegetation (Prunus virginiana). Our data indicate that viruses of terrestrial origin (i.e., allochthonous viruses) may be dispersed widely in coastal marine habitats. The dispersal of NPV polH and detection within offshore net plankton (>64 μm) demonstrates that terrestrial viruses may interact with larger particles and plankton of coastal marine ecosystem, which further suggests that viral genomic information may be transported between biomes.

  1. Native Freshwater Fish and Mussel Species Richness

    Data.gov (United States)

    U.S. Environmental Protection Agency — These data represent predicted current distributions of all native freshwater fish and freshwater mussels in the Middle-Atlantic region. The data are available for...

  2. Aquatic sediments

    International Nuclear Information System (INIS)

    Bonner, J.S.; Autenrieth, R.L.; Schreiber, L.

    1990-01-01

    The authors present a literature review concerning sediment properties, interactions, and conditions. Topics of discussion include the following: biological activity and toxicity; nutrients; metals; organic compounds; dredging; radionuclides; oxygen demand and organic carbon; mathematical modeling; sediment transport and suspension; and paleolimnology

  3. Fish and mussels: importance of fish for freshwater mussel conservation

    Directory of Open Access Journals (Sweden)

    Ronaldo Sousa

    2015-12-01

    Full Text Available Co-extinctions have received trivial consideration in discussions about the global conservation crisis, even though recent studies have emphasised their importance. This situation is even more pronounced in freshwater ecosystems where this phenomenon is largely unrecognized. In this presentation we explore the role of fish for freshwater mussels’ conservation. Freshwater mussels’ need fish as a host to complete their life cycle and given this premise is expected that changes in the fish community due to species extinctions or additions may have great effects. We reviewed the published information and we found: 1 that most of the studies were published in the last few years; 2 that most of the studies were performed in North America (69%, which is probably due to the high number of endemic threatened species in this continent; 3 that most of the mussel species that are specialists in fish hosting are listed as vulnerable or endangered (55%; 4 most studies were performed in laboratory (83% and 5 that the majority of studies were focused on life cycle or on identifying suitable fish hosts of freshwater mussel species with few studies focusing on threats. Since the interaction between fish and freshwater mussels can be easily disrupted and serious threats to this interaction have arisen (e.g. loss and fragmentation of habitat, changes in river flow, climate change, introduction of invasive species, pollution a more holistic approach is needed to find the best management strategies to conserve these animals. In addition, more field studies are required and more information on African, South American and Asian species is essential. Neglect the possible fundamental role of fish in the decline or extinction of freshwater mussels may impair the success of any measure devoted to their conservation; therefore, this issue cannot be ignored.

  4. 2H and 18O Freshwater Isoscapes of Scotland

    Science.gov (United States)

    Meier-Augenstein, Wolfram; Hoogewerff, Jurian; Kemp, Helen; Frew, Danny

    2013-04-01

    Scotland's freshwater lochs and reservoirs provide a vital resource for sustaining biodiversity, agriculture, food production as well as for human consumption. Regular monitoring of freshwaters by the Scottish Environment Protection Agency (SEPA) fulfils legislative requirements with regards to water quality but new scientific methods involving stable isotope analysis present an opportunity combining these mandatory monitoring schemes with fundamental research to inform and deliver on current and nascent government policies [1] through gaining a greater understanding of Scottish waters and their importance in the context of climate change, environmental sustainability and food security. For example, 2H and 18O isoscapes of Scottish freshwater could be used to underpin research and its applications in: • Climate change - Using longitudinal changes in the characteristic isotope composition of freshwater lochs and reservoirs as proxy, isoscapes will provide a means to assess if and how changes in temperature and weather patterns might impact on precipitation patterns and amount. • Scottish branding - Location specific stable isotope signatures of Scottish freshwater have the potential to be used as a tool for provenancing and thus protecting premium Scottish produce such as Scottish beef, Scottish soft fruit and Scottish Whisky. During 2011 and 2012, with the support of SEPA more than 110 samples from freshwater lochs and reservoirs were collected from 127 different locations across Scotland including the Highlands and Islands. Here we present the results of this sampling and analysis exercise isotope analyses in form of 2H and 18O isoscapes with an unprecedented grid resolution of 26.5 × 26.5 km (or 16.4 × 16.4 miles). [1] Adaptation Framework - Adapting Our Ways: Managing Scotland's Climate Risk (2009): Scotland's Biodiversity: It's in Your Hands - A strategy for the conservation and enhancement of biodiversity in Scotland (2005); Recipe For Success - Scotland

  5. Arctic freshwater export: Status, mechanisms, and prospects

    NARCIS (Netherlands)

    Haine, T.W.N.; Curry, B.; Gerdes, R.; Hansen, E.; Karcher, M.; Lee, C.; Rudels, B.; Spreen, G.; de Steur, L.; Stewart, K.D.; Woodgate, R.

    2015-01-01

    Large freshwater anomalies clearly exist in the Arctic Ocean. For example, liquid freshwater has accumulated in the Beaufort Gyre in the decade of the 2000s compared to 1980–2000, with an extra ˜ 5000 km3 — about 25% — being stored. The sources of freshwater to the Arctic from precipitation and

  6. 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.

  7. Freshwater sculpins: phylogenetics to ecology

    Science.gov (United States)

    Susan B. Adams; David A. Schmetterling

    2007-01-01

    Freshwater sculpins (Cottidae) are a diverse and ecologically important component of cool- and coldwater ecosystems throughout the northern hemisphere. More than 60 sculpin species occur in a variety of habitats, and sculpin distributions range from highly localized to widespread. Despite the frequently high biomass of sculpins and their numerous ecosystem functions,...

  8. Methods for preparing synthetic freshwaters.

    Science.gov (United States)

    Smith, E J; Davison, W; Hamilton-Taylor, J

    2002-03-01

    Synthetic solutions that emulate the major ion compositions of natural waters are useful in experiments aimed at understanding biogeochemical processes. Standard recipes exist for preparing synthetic analogues of seawater, with its relatively constant composition, but, due to the diversity of freshwaters, a range of compositions and recipes is required. Generic protocols are developed for preparing synthetic freshwaters of any desired composition. The major problems encountered in preparing hard and soft waters include dissolving sparingly soluble calcium carbonate, ensuring that the ionic components of each concentrated stock solution cannot form an insoluble salt and dealing with the supersaturation of calcium carbonate in many hard waters. For acidic waters the poor solubility of aluminium salts requires attention. These problems are overcome by preparing concentrated stock solutions according to carefully designed reaction paths that were tested using a combination of experiment and equilibrium modeling. These stock solutions must then be added in a prescribed order to prepare a final solution that is brought into equilibrium with the atmosphere. The example calculations for preparing hard, soft and acidic freshwater surrogates with major ion compositions the same as published analyses, are presented in a generalized fashion that should allow preparation of any synthetic freshwater according to its known analysis.

  9. Trait-based modelling of bioaccumulation by freshwater benthic invertebrates.

    Science.gov (United States)

    Sidney, Livia Alvarenga; Diepens, Noël J; Guo, Xiaoying; Koelmans, Albert A

    2016-07-01

    Understanding the role of species traits in chemical exposure is crucial for bioaccumulation and toxicity assessment of chemicals. We measured and modelled bioaccumulation of polychlorinated biphenyls (PCBs) in Chironomus riparius, Hyalella azteca, Lumbriculus variegatus and Sphaerium corneum. We used a battery test procedure with multiple enclosures in one aquarium, which maximized uniformity of exposure for the different species, such that the remaining variability was due mostly to species traits. The relative importance of uptake from either pore water or sediment ingestion was manipulated by using 28 d aged standard OECD sediment with low (1%) and medium (5%) OM content and 13 months aged sediment with medium OM (5%) content. Survival was ≥76% and wet weight increased for all species. Reproduction of H. azteca and weight gain of H. azteca and S. corneum were significantly higher in the medium OM aged sediments than in other sediments, perhaps due to a more developed microbial community (i.e., increase in food resources). Biota-sediment accumulation factors (BSAF) ranged from 3 to 114, depending on species and PCB congener, with C. riparius (3-10)freshwater taxonomic groups were compared with their marine counterparts and showed overlapping values. The dynamic bioaccumulation model with species-specific bioaccumulation parameters fitted well to the experimental data and showed that bioaccumulation parameters were depended on species traits. Enclosure-based battery tests and mechanistic BSAF models are expected to improve the quality of the exposure assessment in whole sediment toxicity tests. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Monitoring endangered freshwater biodiversity using environmental DNA

    DEFF Research Database (Denmark)

    Thomsen, Philip Francis; Kielgast, Jos; Iversen, Lars Lønsmann

    2012-01-01

    Freshwater ecosystems are among the most endangered habitats on Earth, with thousands of animal species known to be threatened or already extinct. Reliable monitoring of threatened organisms is crucial for data-driven conservation actions but remains a challenge owing to nonstandardized methods......, ponds and streams. We successfully validate our findings in a controlled mesocosm experiment and show that DNA becomes undetectable within 2 weeks after removal of animals, indicating that DNA traces are near contemporary with presence of the species. We further demonstrate that entire faunas...... of amphibians and fish can be detected by high-throughput sequencing of DNA extracted from pond water. Our findings underpin the ubiquitous nature of DNA traces in the environment and establish environmental DNA as a tool for monitoring rare and threatened species across a wide range of taxonomic groups....

  11. Vannellid Species Isolated from Freshwater Source in a Park in Jamaica, West Indies

    Directory of Open Access Journals (Sweden)

    Cheridah D. Todd

    2015-01-01

    Full Text Available Free-living amoebae (FLA occupy a wide range of freshwater, marine, and soil habitats, and are opportunistic pathogens in human beings. While Acanthamoeba spp., Naegleria fowleri , and Balamuthia mandrillaris are well-known opportunistic organisms, Vannella epipetala is nonpathogenic. Sediments were collected from a freshwater source from a park in Jamaica to investigate the presence of FLA. Acanthamoeba and Naegleria spp. were not recovered; however, a Vannellid species identified by microscopy and PCR analysis as V. epipetala was isolated. These nonpathogens pose a threat to human beings as they may act as Trojan horses for microsporidian parasites and other pathogens, thereby facilitating their transmission to human beings.

  12. High-resolution imaging of labile phosphorus and its relationship with iron redox state in lake sediments

    DEFF Research Database (Denmark)

    Gao, Yulu; Liang, Tao; Tian, Shuhan

    2016-01-01

    in freshwater lakes. In this study, two in-situ high-resolution diffusive gradients in thin films (DGT) techniques, Zr-Oxide DGT and ZrO-Chelex DGT, were used to investigate the release characteristics of P from sediments in a large freshwater lake (Dongting Lake, China; area of 2691 km(2)) experiencing...

  13. Toxic Effects of Pollutants on the Mineralization of Acetate in Methanogenic River Sediment

    NARCIS (Netherlands)

    van Vlaardingen PLA; van Beelen P

    1993-01-01

    The functioning of anaerobic bacteria in river sediments is vital for the stability of freshwater ecosystems. The sensitivity of these organisms for pollutants is therefore important for the establishment of valid sediment quality criteria. Acetate is a key intermediate in the carbon cycle and was

  14. Sediment Acoustics

    National Research Council Canada - National Science Library

    Stoll, R

    2001-01-01

    ... variables such as porosity and grain-size distribution. The model is based on the classical Biot theory extended to take into account various mechanisms of energy loss that are known to be important in marine sediments...

  15. Sediment fingerprinting in Northern Jordan - approaching sediment comparability

    Science.gov (United States)

    Kraushaar, Sabine; Schumann, Thomas; Ollesch, Gregor; Siebert, Christian; Vogel, Hans-Joerg

    2014-05-01

    Jordan has a quantitative and qualitative water problem in combination with a growing demand by population increase. Around 65% of the freshwater used in Jordan is reported to originate from surface waters and reservoirs. Sediment loads harm the quality of these water bodies and fill up dams. A sediment fingerprint pilot study was implemented in an exemplary catchment in the NW of Jordan to investigate the possibility of geochemical differentiation between 6 sediment sources and calculate their relative contribution to the sink, the Wadi Al-Arab reservoir. The sediment fingerprint method relies on the comparability of sediment properties of the sources and the sink. However, selection processes during transport, preferential adsorption of elements on fine particles, and differences in inorganic carbonate content prevent a direct comparison. In previous studies this has been solved through selective sampling and analyzing certain grain size fractions or the mathematical derivation of correction factors. As no pre-knowledge existed in the Wadi Al-Arab catchment, selective grain size sampling would have implied the risk of neglecting important information already during the sampling process. Hence, a method was established that includes several steps to identify influential parameters (IPs), eliminate their impact and take account of their interrelations. It is based on a stepwise multiple regression analysis model (SMRAM) and generates element specific correction factors that take account for possible interdependencies between influential parameters as clay percentage and total organic and inorganic carbonates. In the further selection process of suitable elements for the fingerprint, we complemented the common used methods by a solubility analysis. Therefore, water profiles were physicochemical investigated in the dam lake. Differences in the chemical milieus during transport and sedimentation that affect the conservativeness of the chosen elements could be detected

  16. Mangroves and sediment dynamics along the coasts of southern Thailand

    NARCIS (Netherlands)

    Thampanya, U.

    2006-01-01

    Mangroves are a specific type of evergreen forest that is found along the coastlines of tropical and subtropical regions, particularly along deltas and bays where rivers discharge freshwater and sediment to the sea. These mangroves provide important ecological and socio-economic functions to coastal

  17. Multiscale physical processes of fine sediment in an estuary

    NARCIS (Netherlands)

    Wan, Y.

    2015-01-01

    This study presented in this book investigates micro- and macro- scale physical processes of a large-scale fine sediment estuarine system with a moderate tidal range as well as a highly seasonal-varying freshwater inflow. Based on a series measured, experimented and modeled results, the research

  18. Changing Arctic Ocean freshwater pathways.

    Science.gov (United States)

    Morison, James; Kwok, Ron; Peralta-Ferriz, Cecilia; Alkire, Matt; Rigor, Ignatius; Andersen, Roger; Steele, Mike

    2012-01-04

    Freshening in the Canada basin of the Arctic Ocean began in the 1990s and continued to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly of the 1970s, raising the spectre of slowing global ocean circulation. Freshening has been attributed to increased sea ice melting and contributions from runoff, but a leading explanation has been a strengthening of the Beaufort High--a characteristic peak in sea level atmospheric pressure--which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation.

  19. The earliest post-paleozoic freshwater bivalves preserved in coprolites from the karoo basin, South Africa.

    Science.gov (United States)

    Yates, Adam M; Neumann, Frank H; Hancox, P John

    2012-01-01

    Several clades of bivalve molluscs have invaded freshwaters at various times throughout Phanerozoic history. The most successful freshwater clade in the modern world is the Unionoida. Unionoids arose in the Triassic Period, sometime after the major extinction event at the End-Permian boundary and are now widely distributed across all continents except Antarctica. Until now, no freshwater bivalves of any kind were known to exist in the Early Triassic. Here we report on a faunule of two small freshwater bivalve species preserved in vertebrate coprolites from the Olenekian (Lower Triassic) of the Burgersdorp Formation of the Karoo Basin, South Africa. Positive identification of these bivalves is not possible due to the limited material. Nevertheless they do show similarities with Unionoida although they fall below the size range of extant unionoids. Phylogenetic analysis is not possible with such limited material and consequently the assignment remains somewhat speculative. Bivalve molluscs re-invaded freshwaters soon after the End-Permian extinction event, during the earliest part of the recovery phase during the Olenekian Stage of the Early Triassic. If the specimens do represent unionoids then these Early Triassic examples may be an example of the Lilliput effect. Since the oldest incontrovertible freshwater unionoids are also from sub-Saharan Africa, it is possible that this subcontinent hosted the initial freshwater radiation of the Unionoida. This find also demonstrates the importance of coprolites as microenvironments of exceptional preservation that contain fossils of organisms that would otherwise have left no trace.

  20. The earliest post-paleozoic freshwater bivalves preserved in coprolites from the karoo basin, South Africa.

    Directory of Open Access Journals (Sweden)

    Adam M Yates

    Full Text Available BACKGROUND: Several clades of bivalve molluscs have invaded freshwaters at various times throughout Phanerozoic history. The most successful freshwater clade in the modern world is the Unionoida. Unionoids arose in the Triassic Period, sometime after the major extinction event at the End-Permian boundary and are now widely distributed across all continents except Antarctica. Until now, no freshwater bivalves of any kind were known to exist in the Early Triassic. PRINCIPAL FINDINGS: Here we report on a faunule of two small freshwater bivalve species preserved in vertebrate coprolites from the Olenekian (Lower Triassic of the Burgersdorp Formation of the Karoo Basin, South Africa. Positive identification of these bivalves is not possible due to the limited material. Nevertheless they do show similarities with Unionoida although they fall below the size range of extant unionoids. Phylogenetic analysis is not possible with such limited material and consequently the assignment remains somewhat speculative. CONCLUSIONS: Bivalve molluscs re-invaded freshwaters soon after the End-Permian extinction event, during the earliest part of the recovery phase during the Olenekian Stage of the Early Triassic. If the specimens do represent unionoids then these Early Triassic examples may be an example of the Lilliput effect. Since the oldest incontrovertible freshwater unionoids are also from sub-Saharan Africa, it is possible that this subcontinent hosted the initial freshwater radiation of the Unionoida. This find also demonstrates the importance of coprolites as microenvironments of exceptional preservation that contain fossils of organisms that would otherwise have left no trace.

  1. The Freshwater Information Platform - an online network supporting freshwater biodiversity research and policy

    Science.gov (United States)

    Schmidt-Kloiber, Astrid; De Wever, Aaike; Bremerich, Vanessa; Strackbein, Jörg; Hering, Daniel; Jähnig, Sonja; Kiesel, Jens; Martens, Koen; Tockner, Klement

    2017-04-01

    Species distribution data is crucial for improving our understanding of biodiversity and its threats. This is especially the case for freshwater environments, which are heavily affected by the global biodiversity crisis. Currently, a huge body of freshwater biodiversity data is often difficult to access, because systematic data publishing practices have not yet been adopted by the freshwater research community. The Freshwater Information Platform (FIP; www.freshwaterplatform.eu) - initiated through the BioFresh project - aims at pooling freshwater related research information from a variety of projects and initiatives to make it easily accessible for scientists, water managers and conservationists as well as the interested public. It consists of several major components, three of which we want to specifically address: (1) The Freshwater Biodiversity Data Portal aims at mobilising freshwater biodiversity data, making them online available Datasets in the portal are described and documented in the (2) Freshwater Metadatabase and published as open access articles in the Freshwater Metadata Journal. The use of collected datasets for large-scale analyses and models is demonstrated in the (3) Global Freshwater Biodiversity Atlas that publishes interactive online maps featuring research results on freshwater biodiversity, resources, threats and conservation priorities. Here we present the main components of the FIP as tools to streamline open access freshwater data publication arguing this will improve the capacity to protect and manage freshwater biodiversity in the face of global change.

  2. High quality draft genome sequence of Janthinobacterium psychrotolerans sp. nov., isolated from a frozen freshwater pond

    DEFF Research Database (Denmark)

    Gong, Xianzhe; Skrivergaard, Stig; Korsgaard, Benjamin

    2017-01-01

    Strain S3-2T, isolated from sediment of a frozen freshwater pond, shares 99% 16S rRNA gene sequence identity with strains of the genus Janthinobacterium. Strain S3-2T is a facultative anaerobe that lacks the ability to produce violacein but shows antibiotic resistance, psychrotolerance, incomplete...

  3. Residual levels of rare earth elements in freshwater and marine fish and their health risk assessment from Shandong, China.

    Science.gov (United States)

    Yang, Luping; Wang, Xining; Nie, Hongqian; Shao, Lijun; Wang, Guoling; Liu, Yongjun

    2016-06-15

    The total concentrations of rare earth elements (ΣREE) were quantified in 251 samples from 10 common species of freshwater and marine fish in seventeen cities of Shandong, China. ΣREE obtained from the freshwater fish ranged from 34.0 to 37.9ngg(-1) (wet weight) and marine fish from 12.7 to 37.6ngg(-1). The ratio of LREE to HREE was 13.7:1 and 10:1 for freshwater and marine fish, respectively. This suggests that freshwater fish exhibit greater REE concentrations than marine fish and the biological effects of LREE are higher than HREE. Results revealed a similar REE distribution pattern between those fish and coastal sediments, abiding the "abundance law". The health risk assessment demonstrated the EDIs of REEs in fish were significantly lower than the ADI, indicating that the consumption of these fish presents little risk to human health. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Sediment flux measurements at the oceanic boundary of a large estuary

    Science.gov (United States)

    Downing-Kunz, M.; Work, P. A.; Schoellhamer, D. H.

    2016-12-01

    Sediment is an important resource for San Francisco Bay (SFB), in the context of wetland restoration projects, dredging operations, ecosystem health, and contaminant transport and fate. One way to help manage sediment (and sediment-associated contaminants) in SFB is by developing a quantitative sediment budget to account for sources, sinks, and storage of sediment. Previously developed sediment budgets have shown that sediment exchange at the oceanic boundary of SFB (Golden Gate) is the most poorly understood element of the SFB sediment budget, owing to logistical challenges that inhibit routine field observations. In this study, field observations of suspended-sediment flux at the Golden Gate were conducted on ebb and flood tides during two distinct periods of the 2016 hydrograph: peak (4,000 m3/s) and low (200 m3/s) rates of freshwater inflow to SFB. Suspended-sediment flux was estimated from a boat-mounted acoustic Doppler current profiler that provided measurements of discharge and acoustic backscatter (ABS) at a cross-section near the oceanic boundary. Discrete water samples were analyzed for suspended-sediment concentration (SSC) and related to ABS. During the period of peak freshwater inflow, maximum discharge observed at Golden Gate reached 130,000 m3/s during ebb tide; observed SSC (20-40 mg/L) were lower than expected compared to upstream conditions. A network of five SSC monitoring stations extending 5-80 km upstream demonstrated a watershed-sourced sediment pulse (SSC reaching 200 mg/L) moved downstream to within 20 km of the oceanic boundary, an observation corroborated by concurrent satellite imagery. This finding, combined with lower SSC near the Golden Gate, suggests the sediment pulse was trapped within SFB, indicating a freshwater inflow threshold exceeding 4,000 m3/s for sediment export at the oceanic boundary. Such trapping could provide additional sediment to benefit wetland restoration efforts.

  5. Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh

    DEFF Research Database (Denmark)

    Gribsholt, B.; Struyf, E.; Tramper, A.

    2007-01-01

    An intact tidal freshwater marsh system (3477m2) was labelled by adding 15N-ammonium as a tracer to the flood water inundating the ecosystem. The appearance and retention of 15N-label in different marsh components (leaves, roots, sediment, leaf litter and invertebrate fauna) was followed over 15......, the results clearly revealed that the less conspicuous compartments such as leaf litter and ruderal vegetations are more important in nitrogen uptake and retention than the prominent reed (Phragmites australis) meadows. Moreover, short-term nitrogen retention in these nutrient rich marshes occurs mainly via...... microbial pathways associated with the litter and sediment. Rather than direct uptake by macrophytes, it is the large reactive surface area provided by the tidal freshwater marsh vegetation that is most crucial for nitrogen transformation, assimilation and short term retention in nutrient rich tidal...

  6. Factors affecting assemblage attributes of freshwater Oligochaeta in Neotropical shallow floodplain lakes

    Directory of Open Access Journals (Sweden)

    Vanessa Ernandes de Amo

    2017-12-01

    Full Text Available Abstract Aim: Identify the effects of sediment composition and water conditions on diversity, richness, evenness, density and composition of freshwater Oligochaeta in shallow floodplain lakes. Methods We sampled 13 shallow floodplain lakes quarterly during the year 2010 in the Upper Paraná River floodplain. In each lake, four sediment samples were taken from the shore and central regions, three of them were used for biological analysis, and one for granulometric analysis. Concomitantly, temperature, dissolved oxygen, pH, conductivity, alkalinity, turbidity and chlorophyll-a were also measured. Initially, the biological samples were analyzed by a stereoscopic microscope. Oligochaeta individuals were identified under optical microscope at the lowest possible taxonomic level. For data analysis, we quantified density, richness, evenness and diversity index of freshwater Oligochaeta. In order to show differences between the months and the analyzed lakes, in relation to the percentages of coarse and fine organic material, the nonparametric Kruskal Wallis test was used. We also calculated the sediment granulometric diversity using the Shannon-Wienner index, using a simple regression analysis. We correlated assemblage attributes of Oligochaeta with sediment diversity and the assemblage species with the limnological variables using the Spearman correlation. Results A total of 2,090 individuals were found distributed among 27 species. From the total individuals number, 57% were Pristina americana, followed by Dero (Dero righii with 13%. Assemblage attributes were not significantly correlated with sediment diversity, and 7 of the 27 species recorded showed significant correlations with at least some of the abiotic variables. Conclusions We verified that the abiotic variables of the water present greater influence on the attributes of the assemblage of freshwater Oligochaeta, when compared with sediment influences. Although we found low local diversity of

  7. Occurrence, activity and contribution of anammox in some freshwater extreme environments.

    Science.gov (United States)

    Zhu, Guibing; Xia, Chao; Shanyun, Wang; Zhou, Leiliu; Liu, Lu; Zhao, Siyan

    2015-12-01

    Anaerobic ammonium oxidation (anammox) widely occurs in marine ecosystems, and it plays an important role in the global nitrogen cycle. But in freshwater ecosystems its occurrence, distribution and contribution, especially in extreme environments, are still not well known. In this study, anammox process was investigated in some extreme environments of freshwater ecosystems, such as those with high (above 75°C) and low (below -35°C) temperature, high (pH > 8) and low (pH  300 mg kg(-1) ). The polymerase chain reaction (PCR) screening results showed that anammox bacteria were widespread in the examined sediments from freshwater extreme environments. Quantitative PCR showed that the abundance of anammox bacteria ranged from 6.94 × 10(4) to 8.05 × 10(6) hydrazine synthase (hzsB) gene copies g(-1) dry soil. (15) N-labelled incubation experiments indicated the occurrence of anammox in all examined sediments and the potential anammox rates ranged from 0.02 to 6.24 nmol N g(-1)  h(-1) , with a contribution of 3.45-58.74% of the total N2 production. In summary, these results demonstrate the occurrence of anammox in these extreme environments, inferring that anammox may harbour a wide ecological niche in the freshwater ecosystems. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  8. A microbial arsenic cycle in sediments of an acidic mine impoundment: Herman Pit, Clear Lake, California

    Science.gov (United States)

    Blum, Jodi S.; McCann, Shelley; Bennett, S.; Miller, Laurence G.; Stolz, J. R.; Stoneburner, B.; Saltikov, C.; Oremland, Ronald S.

    2015-01-01

    The involvement of prokaryotes in the redox reactions of arsenic occurring between its +5 [arsenate; As(V)] and +3 [arsenite; As(III)] oxidation states has been well established. Most research to date has focused upon circum-neutral pH environments (e.g., freshwater or estuarine sediments) or arsenic-rich “extreme” environments like hot springs and soda lakes. In contrast, relatively little work has been conducted in acidic environments. With this in mind we conducted experiments with sediments taken from the Herman Pit, an acid mine drainage impoundment of a former mercury (cinnabar) mine. Due to the large adsorptive capacity of the abundant Fe(III)-rich minerals, we were unable to initially detect in solution either As(V) or As(III) added to the aqueous phase of live sediment slurries or autoclaved controls, although the former consumed added electron donors (i.e., lactate, acetate, hydrogen), while the latter did not. This prompted us to conduct further experiments with diluted slurries using the live materials from the first incubation as inoculum. In these experiments we observed reduction of As(V) to As(III) under anoxic conditions and reduction rates were enhanced by addition of electron donors. We also observed oxidation of As(III) to As(V) in oxic slurries as well as in anoxic slurries amended with nitrate. We noted an acid-tolerant trend for sediment slurries in the cases of As(III) oxidation (aerobic and anaerobic) as well as for anaerobic As(V) reduction. These observations indicate the presence of a viable microbial arsenic redox cycle in the sediments of this extreme environment, a result reinforced by the successful amplification of arsenic functional genes (aioA, and arrA) from these materials.

  9. Using the Asian clam as an indicator of microplastic pollution in freshwater ecosystems.

    Science.gov (United States)

    Su, Lei; Cai, Huiwen; Kolandhasamy, Prabhu; Wu, Chenxi; Rochman, Chelsea M; Shi, Huahong

    2018-03-01

    Bioindicators play an important role in understanding pollution levels, bioavailability and the ecological risks of contaminants. Several bioindicators have been suggested for understanding microplastic in the marine environment. A bioindicator for microplastics in the freshwater environment does not exist. In our previous studies, we found a high frequency of microplastic pollution in the Asian clam (Corbicula fluminea) in Taihu Lake, China. In the present study, we conducted a large-scale survey of microplastic pollution in Asian clams, water and sediment from 21 sites in the Middle-Lower Yangtze River Basin from August to October of 2016. The Asian clam was available in all sites, which included diverse freshwater systems such as lakes, rivers and estuaries. Microplastics were found at concentrations ranging from 0.3-4.9 items/g (or 0.4-5.0 items/individual) in clams, 0.5-3.1 items/L in water and 15-160 items/kg in sediment. Microfibers were the most dominant types of microplastics found, accounting for 60-100% in clams across all sampling sites. The size of microplastics ranged from 0.021-4.83 mm, and microplastics in the range of 0.25-1 mm were dominant. The abundance, size distribution and color patterns of microplastics in clams more closely resembled those in sediment than in water. Because microplastic pollution in the Asian clam reflected the variability of microplastic pollution in the freshwater environments, we demonstrated the Asian clam as an bioindicator of microplastic pollution in freshwater systems, particularly for sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. A Search for Freshwater in the Saline Aquifers of Coastal Bangladesh

    Science.gov (United States)

    Peters, C.; Hornberger, G. M.

    2017-12-01

    Can we locate pockets of freshwater amidst brackish groundwater in remote villages in Bangladesh? This study explores what we can infer about local groundwater-surface water (GW-SW) interactions in the polders of coastal Bangladesh. In this underdeveloped region, the shallow groundwater is primarily brackish with unpredictable apportioning of freshwater pockets. We use transects of piezometers, cores, electromagnetic induction, and water chemistry surveys to explore two sources of potential fresh groundwater: (1) tidal channel-aquifer exchange and (2) meteoric recharge. Freshwater is difficult to find due to disparate subsurface lithology, asymmetrical tidal dynamics, extreme seasonal fluctuations in rainfall, and limited field data. Observations suggest substantial lateral variability in shallow subsurface conductivity profiles as well as tidal pressure signals in piezometers. Nevertheless, active exchange of freshwater may be limited due to low permeability of banks and surface sediments limits. Small scale heterogeneity in delta formation likely caused much of the groundwater salinity variation. Without adequate ground truthing of groundwater quality, the ability to deduce the exact location of freshwater pockets may be restricted.

  11. Tentacle structure in freshwater bryozoans.

    Science.gov (United States)

    Tamberg, Yuta; Shunatova, Natalia

    2017-05-01

    Tentacles are the main food-gathering organs of bryozoans. The most common design is a hollow tube of extracellular matrix (ECM), covered with ten columns of epithelial cells on the outside, and a coelothelium on the inside. Nerves follow the ECM, going between the bases of some epidermal cells. The tentacle musculature includes two bundles formed by myoepithelial cells of the coelothelium. The tentacles of freshwater (phylactolaemate) bryozoans, however, differ somewhat in structure from those of marine bryozoans. Here, we describe the tentacles of three species of phylactolaemates, comparing them to gymnolaemates and stenolaemates. Phylactolaemate tentacles tend to be longer, and with more voluminous coeloms. The composition of the frontal cell row and the number of frontal nerves is variable in freshwater bryozoans, but constant in marine groups. Abfrontal cells form a continuous row in Phylactolaemata, but occur intermittently in other two classes. Phylactolaemata lack the microvillar cuticle reported in Gymnolaemata. Abfrontal sensory tufts are always composed of pairs of mono- and/or biciliated cells. This arrangement differs from individual abfrontal ciliary cells of other bryozoans: monociliated in Stenolaemata and monociliated and multiciliated ones in Gymnolaemata. In all three groups, however, ciliated abfrontal cells probably serve as mechanoreceptors. We confirm previously described phylactolemate traits: an unusual arrangement of two-layered coelothelium lining the lateral sides of the tentacle and oral slits in the intertentacular membrane. As previously reported, tentacle movements involved in feeding differ between bryozoan groups, with phylactolaemates tending to have slower movements than both gymnolaemates and stenolaemates, and a narrower behavioral repertoire than gymnolaemates. The morphological and ultrastructural differences between the freshwater species we studied and marine bryozoans may be related to these functional differences. Muscle

  12. Dating of sediments and determination of sedimentation rate. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Illus, E. [ed.

    1998-08-01

    The Second NKS (Nordic Nuclear Safety Research)/EKO-1 Seminar was held at the Finnish Centre for Radiation and Nuclear Safety (STUK) on April 2-3, 1997. The work of the NKS is based on 4-year programmes; the current programme having been planned for the years 1994-1997. The programme comprises 3 major fields, one of them being environmental effects (EKO). Under this umbrella there are 4 main projects. The EKO-1 project deals with marine radioecology, in particular bottom sediments and sediment processes. The programme of the second seminar consisted of 8 invited lecturers and 6 other scientific presentations. Dating of sediments and determination of sedimentation rate are important in all types of sedimentological study and model calculations of fluxes of substances in the aquatic environment. In many cases these tasks have been closely related to radioecological studies undertaken in marine and fresh water environments, because they are often based on measured depth profiles of certain natural or artificial radionuclides present in the sediments. During recent decades Pb-210 has proved to be very useful in dating of sediments, but some other radionuclides have also been successfully used, e.g. Pu-239,240, Am-241 and Cs-137. The difficulties existing and problems involved in dating of sediments, as well as solutions for resolving these problems are discussed in the presentations

  13. Characterization of a Freshwater Crab Sudanonautes aubryi ...

    African Journals Online (AJOL)

    SARAH

    2014-01-31

    Jan 31, 2014 ... Recently, Cumberlidge and. Reed (2004) described the freshwater crab genus. Erimetopus of Congo basin. Sudanonautes aubryi, like all others edible crabs are also poorly understood. This preliminary study was undertaken to collect and realize a biometric characterization of this common freshwater crab ...

  14. Freshwater Ecology. LC Science Tracer Bullet.

    Science.gov (United States)

    Niskern, Diana, Comp.

    Freshwater ecosystems include lakes, ponds, streams, rivers, and certain types of wetlands. This literature and resources guide is not intended to be a comprehensive bibliography on freshwater ecology; the guide is designed--as the name of the series implies--to put the reader or student "on target." Other literature guides related to…

  15. How Will Climate Change Affect Freshwater Fishing?

    OpenAIRE

    Gilbert, Lael; Smith, Jordan W.

    2016-01-01

    This fact sheet reviews how climate change can affect freshwater fishing in the United States. Climate change can affect the availability and diversity of target species, the environmental and aesthetic quality of fishing sites, as well as the policies used to manage freshwater fishing.

  16. Effects of Pollution on Freshwater Fish.

    Science.gov (United States)

    Brungs, W. A.; And Others

    1978-01-01

    Presents a literature review of the effects of pollution on freshwater fish, covering publications of 1976-77. This review includes: (1) water quality; (2) pesticide pollutants; (3) chemical pollutants; (4) miscellaneous pollutants; and (5) physical factors of pollution on freshwater fish. A list of 338 references is also presented. (HM)

  17. Farming of Freshwater Rainbow Trout in Denmark

    DEFF Research Database (Denmark)

    Jokumsen, Alfred; Svendsen, Lars Moeslund

    Textbook on Farming of Freshwater Rainbow Trout in Denmark. Danish edition with the title: Opdræt af regnbueørred i Danmark......Textbook on Farming of Freshwater Rainbow Trout in Denmark. Danish edition with the title: Opdræt af regnbueørred i Danmark...

  18. Tidal Freshwater Wetlands: Variation and Changes

    NARCIS (Netherlands)

    Barendregt, A.; Swarth, C.W.

    2013-01-01

    Tidal freshwater wetlands (TFW) are situated in the upper estuary in a zone bordered upstream by the nontidal river and downstream by the oligohaline region. Here, discharge of freshwater from the river and the daily tidal pulse from the sea combine to create conditions where TFW develop. TFW

  19. Integrating the social, hydrological and ecological dimensions of freshwater health: The Freshwater Health Index.

    Science.gov (United States)

    Vollmer, Derek; Shaad, Kashif; Souter, Nicholas J; Farrell, Tracy; Dudgeon, David; Sullivan, Caroline A; Fauconnier, Isabelle; MacDonald, Glen M; McCartney, Matthew P; Power, Alison G; McNally, Amy; Andelman, Sandy J; Capon, Timothy; Devineni, Naresh; Apirumanekul, Chusit; Ng, Cho Nam; Rebecca Shaw, M; Wang, Raymond Yu; Lai, Chengguang; Wang, Zhaoli; Regan, Helen M

    2018-06-15

    Degradation of freshwater ecosystems and the services they provide is a primary cause of increasing water insecurity, raising the need for integrated solutions to freshwater management. While methods for characterizing the multi-faceted challenges of managing freshwater ecosystems abound, they tend to emphasize either social or ecological dimensions and fall short of being truly integrative. This paper suggests that management for sustainability of freshwater systems needs to consider the linkages between human water uses, freshwater ecosystems and governance. We present a conceptualization of freshwater resources as part of an integrated social-ecological system and propose a set of corresponding indicators to monitor freshwater ecosystem health and to highlight priorities for management. We demonstrate an application of this new framework -the Freshwater Health Index (FHI) - in the Dongjiang River Basin in southern China, where stakeholders are addressing multiple and conflicting freshwater demands. By combining empirical and modeled datasets with surveys to gauge stakeholders' preferences and elicit expert information about governance mechanisms, the FHI helps stakeholders understand the status of freshwater ecosystems in their basin, how ecosystems are being manipulated to enhance or decrease water-related services, and how well the existing water resource management regime is equipped to govern these dynamics over time. This framework helps to operationalize a truly integrated approach to water resource management by recognizing the interplay between governance, stakeholders, freshwater ecosystems and the services they provide. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  20. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

    effect on radiocarbon dating in an estuarine environment is examined. Here, freshwater influence causes reservoir ages to vary between 250 and 700 14C years during the period 5400 BC - AD 700. The examples in this study show clearly that the freshwater reservoir effect can seriously corrupt radiocarbon......The freshwater reservoir effect can result in anomalously old radiocarbon ages of samples from lakes and rivers. This includes the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. Water rich in dissolved ancient calcium carbonates, commonly known...... as hard water, is the most common reason for the freshwater reservoir effect. It is therefore also called hardwater effect. Although it has been known for more than 60 years, it is still less well-recognized by archaeologists than the marine reservoir effect. The aim of this study is to examine the order...

  1. Freshwater to seawater transitions in migratory fishes

    Science.gov (United States)

    Zydlewski, Joseph D.; Michael P. Wilkie,

    2012-01-01

    The transition from freshwater to seawater is integral to the life history of many fishes. Diverse migratory fishes express anadromous, catadromous, and amphidromous life histories, while others make incomplete transits between freshwater and seawater. The physiological mechanisms of osmoregulation are widely conserved among phylogenetically diverse species. Diadromous fishes moving between freshwater and seawater develop osmoregulatory mechanisms for different environmental salinities. Freshwater to seawater transition involves hormonally mediated changes in gill ionocytes and the transport proteins associated with hypoosmoregulation, increased seawater ingestion and water absorption in the intestine, and reduced urinary water losses. Fishes attain salinity tolerance through early development, gradual acclimation, or environmentally or developmentally cued adaptations. This chapter describes adaptations in diverse taxa and the effects of salinity on growth. Identifying common strategies in diadromous fishes moving between freshwater and seawater will reveal the ecological and physiological basis for maintaining homeostasis in different salinities, and inform efforts to conserve and manage migratory euryhaline fishes.

  2. Estimation of Freshwater Flow to Joe Bay, South Florida.

    Science.gov (United States)

    Zucker, M. A.; Hittle, C. D.

    2002-05-01

    During the last century, drainage canals were constructed as part of the Central and Southern Flood Control (C&SF) project. Flood control was achieved but degradation to the Everglades ecosystem was evident. Problems related to Florida Bay include sea grass die off, algae blooms, and extreme salinity conditions. Modifications to the C&SF project are proposed as part of the Comprehensive Everglades Restoration Plan (CERP). One objective of CERP is to improve the timing and distribution of freshwater flow within the Everglades ecosystem and to Florida Bay. Several CERP projects propose changes to the existing canal network that borders Everglades National Park (ENP) in southern Miami-Dade County. An examination of flows to Joe Bay, a small embayment on the northeastern shores of Florida Bay, has provided baseline information on current spatial and temporal water deliveries prior to CERP modifications. Understanding the existing complex water delivery system and the effects the system has on Everglades hydrology will provide a necessary benchmark against which to measure restoration success. The study was initiated by the U.S. Geological Survey (USGS) in May 1999 to estimate creek flows to Joe Bay and determine the relative amounts derived from Taylor Slough and overflow from the C-111 Canal. It is important to understand the source of freshwater to Joe Bay before it enters Florida Bay. Taylor Slough transports freshwater to northeastern Florida Bay from the northwest while overflow from the C-111 Canal provides freshwater to northeastern Florida Bay from the northeast. Joe Bay, receives part of the freshwater from each of these sources via sheet flow and small estuarine creeks, and subsequently discharges southward to northeastern Florida Bay via Trout Creek. Trout Creek contributes approximately 50 percent of the total freshwater flow to northeastern Florida Bay (Hittle 2001). Eight non-gaged creeks entering Joe Bay were selected for acoustic Doppler current

  3. Visual sedimentation.

    Science.gov (United States)

    Huron, Samuel; Vuillemot, Romain; Fekete, Jean-Daniel

    2013-12-01

    We introduce Visual Sedimentation, a novel design metaphor for visualizing data streams directly inspired by the physical process of sedimentation. Visualizing data streams (e. g., Tweets, RSS, Emails) is challenging as incoming data arrive at unpredictable rates and have to remain readable. For data streams, clearly expressing chronological order while avoiding clutter, and keeping aging data visible, are important. The metaphor is drawn from the real-world sedimentation processes: objects fall due to gravity, and aggregate into strata over time. Inspired by this metaphor, data is visually depicted as falling objects using a force model to land on a surface, aggregating into strata over time. In this paper, we discuss how this metaphor addresses the specific challenge of smoothing the transition between incoming and aging data. We describe the metaphor's design space, a toolkit developed to facilitate its implementation, and example applications to a range of case studies. We then explore the generative capabilities of the design space through our toolkit. We finally illustrate creative extensions of the metaphor when applied to real streams of data.

  4. Sources, variability and fate of freshwater in the Bellingshausen Sea, Antarctica

    Science.gov (United States)

    Regan, Heather C.; Holland, Paul R.; Meredith, Michael P.; Pike, Jennifer

    2018-03-01

    During the second half of the twentieth century, the Antarctic Peninsula was subjected to a rapid increase in air temperatures. This was accompanied by a reduction in sea ice extent, increased precipitation and a dramatic retreat of glaciers associated with an increase in heat flux from deep ocean water masses. Isotopic tracers have been used previously to investigate the relative importance of the different freshwater sources to the adjacent Bellingshausen Sea (BS), but the data coverage is strongly biased toward summer. Here we use a regional model to investigate the ocean's response to the observed changes in its different freshwater inputs (sea ice melt/freeze, precipitation, evaporation, iceberg/glacier melt, and ice shelf melt). The model successfully recreates BS water masses and performs well against available freshwater data. By tracing the sources and pathways of the individual components of the freshwater budget, we find that sea ice dominates seasonal changes in the total freshwater content and flux, but all sources make a comparable contribution to the annual-mean. Interannual variability is dominated by sea ice and precipitation. Decadal trends in the salinity and stratification of the ocean are investigated, and a 20-year surface freshening from 1992 to 2011 is found to be predominantly driven by decreasing autumn sea ice growth. These findings will help to elucidate the role of freshwater in driving circulation and water column structure changes in this climatically-sensitive region.

  5. The potential of freshwater macroalgae as a biofuels feedstock and the influence of nutrient availability on freshwater macroalgal biomass production

    Science.gov (United States)

    Yun, Jin-Ho

    Extensive efforts have been made to evaluate the potential of microalgae as a biofuel feedstock during the past 4-5 decades. However, filamentous freshwater macroalgae have numerous characteristics that favor their potential use as an alternative algal feedstock for biofuels production. Freshwater macroalgae exhibit high rates of areal productivity, and their tendency to form dense floating mats on the water surface imply significant reductions in harvesting and dewater costs compared to microalgae. In Chapter 1, I reviewed the published literature on the elemental composition and energy content of five genera of freshwater macroalgae. This review suggested that freshwater macroalgae compare favorably with traditional bio-based energy sources, including terrestrial residues, wood, and coal. In addition, I performed a semi-continuous culture experiment using the common Chlorophyte genus Oedogonium to investigate whether nutrient availability can influence its higher heating value (HHV), productivity, and proximate analysis. The experimental study suggested that the most nutrient-limited growth conditions resulted in a significant increase in the HHV of the Oedogonium biomass (14.4 MJ/kg to 16.1 MJ/kg). Although there was no significant difference in productivity between the treatments, the average dry weight productivity of Oedogonium (3.37 g/m2/day) was found to be much higher than is achievable with common terrestrial plant crops. Although filamentous freshwater macroalgae, therefore, have significant potential as a renewable source of bioenergy, the ultimate success of freshwater macroalgae as a biofuel feedstock will depend upon the ability to produce biomass at the commercial-scale in a cost-effective and sustainable manner. Aquatic ecology can play an important role to achieve the scale-up of algal crop production by informing the supply rates of nutrients to the cultivation systems, and by helping to create adaptive production systems that are resilient to

  6. Impact of macrozoobenthic bioturbation and wind fluctuation interactions on net methylmercury in freshwater lakes.

    Science.gov (United States)

    Wang, Peifang; Yao, Yu; Wang, Chao; Hou, Jun; Qian, Jin; Miao, Lingzhan

    2017-11-01

    The methylmercury (MeHg) as the toxic fractions has presented significant threats to biota in freshwater ecosystems. Hg methylation process is demonstrated to be manipulated by biota process (benthic disturbance and algae bloom existence) as well as the abiotic influence (wind fluctuation and illumination intensity) in freshwater ecosystems. However, the mechanisms influencing Hg methylation are still unclear, and the coupled influences of the biotic and abiotic process with the shifts in variation on methylmercury remain unexplored. Accordingly, an annular flume experiment which simulated the freshwater ecosystem, was conducted for 108 days to examine the influences of typical disturbance by chironomid larvae and wind fluctuations on MeHg variation in sediment profiles. The in-situ, passive sampler technique of revealing diffusive gradients in thin films (DGT) encompassed the special resin, based on referenced extraction and coloration-computer imaging densitometry, were employed to obtain labile MeHg, Fe, and S concentrations at high resolution. The results indicate that larval bioturbation during the initial period of the experiment could diminish bioavailable MeHg concentrations and change the diffusion direction of MeHg fluxes. However, this inhibitive effect on MeHg concentrations ceased with larvae eclosion. Compared to bioturbation, wind fluctuation exerted slow but sustained inhibition on MeHg release. Furthermore, the eight parameters (dissolved organic carbon (DOC), DO, labile Fe and S concentrations, pH, sulfate-reducing bacteria (SRB) abundance in sediment, oxidation-reduction potential (ORP) and EC) could explain more of variation in MeHg concentrations which indicated by the canonical correspondence analysis. And these eight parameters manifest higher explanatory power for MeHg distributed in newly formed sediment. More notably, the comparison results of the multiple and simple regression directly demonstrated the DOC was the fundamental and robust

  7. Status and Impacts of Arctic Freshwater Export

    Science.gov (United States)

    Haine, T. W. N.

    2017-12-01

    Large freshwater anomalies clearly exist in the Arctic Ocean. For example, liquid freshwater has accumulated in the Beaufort Gyre in the decade of the 2000s compared to 1980-2000, with an extra ≈5000 km3—about 25%—being stored. The sources of freshwater to the Arctic from precipitation and runoff have increased between these periods (most of the evidence comes from models). Despite flux increases from 2001 to 2011, it is uncertain if the marine freshwater source through Bering Strait for the 2000s has changed, as observations in the 1980s and 1990s are incomplete. The marine freshwater fluxes draining the Arctic through Fram and Davis straits are also insignificantly different. In this way, the balance of sources and sinks of freshwater to the Arctic, Canadian Arctic Archipelago (CAA), and Baffin Bay shifted to about 1200±730 km3yr-1 freshening the region, on average, during the 2000s. The observed accumulation of liquid freshwater is consistent with this increased supply and the loss of freshwater from sea ice (Figure, right). Evidence exists that such discharges can impact the Atlantic meridional overturning circulation, and hence Atlantic sector climate. Nevertheless, it appears that the observed AMOC variability since 2004, when high quality measurements began, is not attributable to anthropogenic influence. This work is based on, and updated from, Haine et al. (2015), Carmack et al. (2016), and Haine (2016). Haine, T. W. N. Ocean science: Vagaries of Atlantic overturning. Nature Geoscience, 9, 479-480, 10.1038/ngeo2748, 2016. T. W. N. Haine et al., Arctic Freshwater Export: Status, Mechanisms, and Prospects, Global Planetary Change, 125, 13-35, 10.1016/j.glopacha.2014.11.013, 2015. E. Carmack et al., Fresh water and its role in the Arctic Marine System: sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans. J. G. Res. Biogeosciences, 10.1002/2015JG003140, 2016.

  8. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    case studies will show the degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants and animals, shows that age differences of up to 2000 years can occur within one river. In the Limfjord, freshwater influence...... caused reservoir ages to vary between 250 and 700 years during the period 5400 BC - AD 700. Finally, I will discuss the implications of the freshwater reservoir effect for radiocarbon dating of Mesolithic pottery from inland sites of the Ertebølle culture in Northern Germany....

  9. Effect of salt treatments on survival and consumer acceptance of freshwater prawn, Macrobrachium rosenbergii

    Science.gov (United States)

    Post harvest acclimation of live freshwater prawns to a mixture of water and marine salt increases the consumer acceptability of the finished product. However, the high cost of marine salts prohibits their use in commercial practice. Therefore, the identification of successful, cost effective salt a...

  10. Catchment source contributions to the sediment-bound organic matter degrading salmonid spawning gravels in a lowland river, southern England

    Energy Technology Data Exchange (ETDEWEB)

    Collins, A.L., E-mail: adrian.collins@adas.co.uk [ADAS, Pendeford House, Wobaston Road, Wolverhampton WV9 5AP (United Kingdom); Geography and Environment, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Williams, L.J.; Zhang, Y.S. [ADAS, Pendeford House, Wobaston Road, Wolverhampton WV9 5AP (United Kingdom); Marius, M. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Dungait, J.A.J. [Department of Sustainable Systems and Grassland Science, Rothamsted Research—North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Smallman, D.J. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Dixon, E.R. [Department of Sustainable Systems and Grassland Science, Rothamsted Research—North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Stringfellow, A. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Sear, D.A. [Geography and Environment, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Jones, J.I. [School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom); Naden, P.S. [CEH Wallingford, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB (United Kingdom)

    2013-07-01

    The ingress of particulate material into freshwater spawning substrates is thought to be contributing to the declining success of salmonids reported over recent years for many rivers. Accordingly, the need for reliable information on the key sources of the sediment problem has progressed up the management agenda. Whilst previous work has focussed on apportioning the sources of minerogenic fine sediment degrading spawning habitats, there remains a need to develop procedures for generating corresponding information for the potentially harmful sediment-bound organic matter that represents an overlooked component of interstitial sediment. A source tracing procedure based on composite signatures combining bulk stable {sup 13}C and {sup 15}N isotope values with organic molecular structures detected using near infrared (NIR) reflectance spectroscopy was therefore used to assess the primary sources of sediment-bound organic matter sampled from artificial spawning redds. Composite signatures were selected using a combination of the Kruskal–Wallis H-test, principal component analysis and GA-driven discriminant function analysis. Interstitial sediment samples were collected using time-integrating basket traps which were inserted at the start of the salmonid spawning season and extracted in conjunction with critical phases of fish development (eyeing, hatch, emergence, late spawning). Over the duration of these four basket extractions, the overall relative frequency-weighted average median (± 95% confidence limits) source contributions to the interstitial sediment-bound organic matter were estimated to be in the order: instream decaying vegetation (39 ± < 1%; full range 0–77%); damaged road verges (28 ± < 1%; full range 0–77%); septic tanks (22 ± < 1%; full range 0–50%), and; farm yard manures/slurries (11 ± < 1%; full range 0–61%). The reported procedure provides a promising basis for understanding the key sources of interstitial sediment-bound organic matter

  11. Increasing salinity drastically reduces hatching success of crustaceans from depression wetlands of the semi-arid Eastern Cape Karoo region, South Africa.

    Science.gov (United States)

    Mabidi, Annah; Bird, Matthew S; Perissinotto, Renzo

    2018-04-13

    Salinity is an important factor affecting freshwater aquatic species distribution and diversity. The semi-arid Eastern Cape Karoo region of South Africa has been earmarked for shale gas development through hydraulic fracturing. The process uses large amounts of water and produces briny wastewater. When not managed properly, these wastewaters may lead to salinisation of surface freshwater bodies in the region. Therefore, the effect of salinity on the hatching success of crustacean resting eggs was examined using sediments from four depression wetlands found in the region. The sediments were exposed for 28 days to salinity levels of 0.5 g L -1 , 2.5 g L -1 , 5 g L -1 and 10 g L -1 . Control aquaria in which no salt was added were also set up. There was a significant decrease in the emerged taxa richness and abundances at salinities of 2.5 g L -1 and above. Anostraca, Notostraca and Spinicaudata hatchlings were abundant at salinities of 0.5 g L -1 and below, while Copepoda, Daphniidae (Cladocera) and Ostracoda were observed in the highest salinity, but their densities were still lower with increased salinities. Given the importance of large branchiopods in the trophic balance of depression wetlands, their loss may alter the ecological balance and function of these ecosystems.

  12. Declining metal levels at Foundry Cove (Hudson River, New York): Response to localized dredging of contaminated sediments

    International Nuclear Information System (INIS)

    Mackie, Joshua A.; Natali, Susan M.; Levinton, Jeffrey S.; Sanudo-Wilhelmy, Sergio A.

    2007-01-01

    This study examines the effectiveness of remediating a well-recognized case of heavy metal pollution at Foundry Cove (FC), Hudson River, New York. This tidal freshwater marsh was polluted with battery-factory wastes (1953-1979) and dredged in 1994-1995. Eight years after remediation, dissolved and particulate metals (Cd, Co, Cu, Pb, Ni, and Ag) were found to be lower than levels in the lower Hudson near New York City. Levels of metals (Co, Ni, Cd) on suspended particles were comparatively high. Concentrations of surface sediment Cd throughout the marsh system remain high, but have decreased both in the dredged and undredged areas: Cd was 2.4-230 mg/kg dw of sediment in 2005 vs. 109-1500 mg/kg in the same area in 1983. The rate of tidal export of Cd from FC has decreased by >300-fold, suggesting that dredging successfully stemmed a major source of Cd to the Hudson River. - Dredging of a hotspot of metal-contaminated sediment is associated with a recognizable local and river-wide decline in cadmium in the Hudson River, New York

  13. On luminescence bleaching of tidal channel sediments

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Pejrup, Morten; Murray, Andrew S.

    2015-01-01

    We investigate the processes responsible for bleaching of the quartz OSL signal from tidal channel sediment. Tidal dynamics are expected to play an important role for complete bleaching of tidal sediments. However, no studies have examined the amount of reworking occurring in tidal channels...... and on tidal flats due to the mixing caused by currents and waves. We apply bed level data to evaluate the amount of vertical sediment reworking in modern tidal channels and at a tidal flat. Cycles of deposition and erosion are measured with a bed level sensor, and the results show that gross sedimentation...... was several times higher than net sedimentation. We propose that tidal channel sediment is bleached either on the tidal flat before it is transported to the tidal channels and incorporated in channel-fill successions or, alternatively, on the shallow intertidal part of the channel banks. Based...

  14. Nitric oxide turnover in permeable river sediment

    DEFF Research Database (Denmark)

    Schreiber, Frank; Stief, Peter; Kuypers, Marcel M M

    2014-01-01

    We measured nitric oxide (NO) microprofiles in relation to oxygen (O2) and all major dissolved N-species (ammonium, nitrate, nitrite, and nitrous oxide [N2O]) in a permeable, freshwater sediment (River Weser, Germany). NO reaches peak concentrations of 0.13 μmol L-1 in the oxic zone and is consumed......-nitroso-N-acetylpenicillamine (SNAP) (1) confirmed denitrification as the main NO consumption pathway, with N2O as its major product, (2) showed that denitrification combines one free NO molecule with one NO molecule formed from nitrite to produce N2O, and (3) suggested that NO inhibits N2O reduction....

  15. Plastic pollution in freshwater ecosystems: macro-, meso-, and microplastic debris in a floodplain lake.

    Science.gov (United States)

    Blettler, Martin C M; Ulla, Maria Alicia; Rabuffetti, Ana Pia; Garello, Nicolás

    2017-10-23

    Plastic pollution is considered an important environmental problem by the United Nations Environment Programme, and it is identified, alongside climate change, as an emerging issue that might affect biological diversity and human health. However, despite research efforts investigating plastics in oceans, relatively little studies have focused on freshwater systems. The aim of this study was to estimate the spatial distribution, types, and characteristics of macro-, meso-, and microplastic fragments in shoreline sediments of a freshwater lake. Food wrappers (mainly polypropylene and polystyrene), bags (high- and low-density polyethylene), bottles (polyethylene terephthalate), and disposable Styrofoam food containers (expanded polystyrene) were the dominant macroplastics recorded in this study. Contrary to other studies, herein macroplastic item surveys would not serve as surrogates for microplastic items. This is disadvantageous since macroplastic surveys are relatively easier to conduct. Otherwise, an average of 25 mesoplastics (mainly expanded polystyrene) and 704 microplastic particles (diverse resins) were recorded per square meter in sandy sediments. Comparisons with other studies from freshwater and marine beaches indicated similar relevance of plastic contamination, demonstrating for the first time that plastic pollution is a serious problem in the Paraná floodplain lakes. This study is also valuable from a social/educational point of view, since plastic waste has been ignored in the Paraná catchment as a pollutant problem, and therefore, the outcome of the current study is a relevant contribution for decision makers.

  16. Exotic freshwater planarians currently known from Japan

    NARCIS (Netherlands)

    Sluys, R.; Kawakatsu, M.; Yamamoto, K.

    2010-01-01

    Biogeographical and taxonomic information on the four non-indigenous freshwater planarians of Japan is reviewed, viz. Dugesia austroasiatica Kawakatsu, 1985, Girardia tigrina (Girard, 1850), G. dorotocephala (Woodworth, 1897), and Rhodax evelinae? Marcus, 1947. The occurrence of Girardia

  17. Progress and challenges in freshwater conservation planning

    CSIR Research Space (South Africa)

    Nel, JL

    2009-06-01

    Full Text Available . Challenges relating to both improvement of scientific rigour and implementation of freshwater conservation plans are identified. High demand for water from multiple stakeholders requires planning for implementation from the outset. Three guidelines...

  18. DOMESTICATION OF FRESHWATER PUFFER FISH OR BUNTAL (Tetraodon palembangensis

    Directory of Open Access Journals (Sweden)

    I Wayan Subamia

    2008-12-01

    Full Text Available The Research Institute for Freshwater Ornamental Fish Culture has been conducting domestication research since 2004 on adult freshwater puffer fish or buntal broodstock in which the fish were reared in aquaria and fed with small feed fish teri (anchovy and earthworm (Lumbricus sp.. The domestication of freshwater puffer fish or buntal has resulted in successful environmental adaptation and reproductive ability of the fish and further rearing of its fry. The adaptive ability was indicated by its high survival rate, good growth and development, and the reproductive success in spawning, egg production, hatching as well as growing of the larvae to fry stages. The mature gonad stage of the fish was reached at an average body weight of 150 g with a reproductive period of 5 months. The spawning occurred naturally and the eggs were gradually released at interval periods of 14—18 days with egg production rates of 1,000—1,900 eggs per spawning. The highest egg fertilization rate was 96%, with the highest egg hatching rate of 78.6%. Hatching process took place on the 6th to 13th days after spawning process. The surviving larvae began feeding filtered natural foods Moina sp. on the 3rd day up to the 6th day, whereas unfiltered Moina sp. was given from the 7th to 14th days. The fish were fed the live feed Culex sp. from the 15th to 30th days. In the following period the fish was fed earthworm and small feed fish teri (anchovy.

  19. Sediment retention in a bottomland hardwood wetland in Eastern Arkansas

    Science.gov (United States)

    Kleiss, B.A.

    1996-01-01

    One of the often-stated functions of wetlands is their ability to remove sediments and other particulates from water, thus improving water quality in the adjacent aquatic system. However, actual rates of suspended sediment removal have rarely been measured in freshwater wetland systems. To address this issue, suspended sediment dynamics were measured in a 85-km2 bottomland hardwood (BLH) wetland adjacent to the highly turbid Cache River in eastern Arkansas during the 1988-1990 water years. A suspended sediment mass balance was calculated using depth-integrated, flow-weighted daily measurements at wetland inflow and outflow points. Over the three-year period, suspended sediment load decreased an average of 14% between upstream and downstream sampling points. To test the idea that the suspended sediments were retained by the adjacent wetland and to determine what portion of the BLH forest was most responsible for retaining the suspended sediments, concurrent measurements of sediment accretion were made at 30 sites in the wetland using feldspar clay marker horizons, sedimentation disks, the 137cesium method, and dendrogeomorphic techniques. Sedimentation rates exceeding 1 cm/yr were measured in frequently flooded areas dominated by Nyssa aquatica and Taxodium distichum. Maximum sedimentation rates did not occur on the natural levee, as would be predicted by classical fluvial geomorphology, but in the "first bottom," where retention time of the water reached a maximum. Multiple regression was used to relate sedimentation rates with several physical and biological factors. A combination of distance from the river, flood duration, and tree basal area accounted for nearly 90% of the variation in sedimentation rates.

  20. Field studies of estuarine turbidity under different freshwater flow conditions, Kaipara River, New Zealand

    Science.gov (United States)

    Mitchell, Steven B.; Green, Malcolm O.; MacDonald, Iain T.; Pritchard, Mark

    2017-11-01

    We present a first interpretation of three days of measurements made in 2013 from the tidal reaches of the Kaipara River (New Zealand) under both low and high freshwater inputs and a neap tidal cycle. During the first day, we occupied two stations that were approximately 6 km apart in a tidal reach that runs for 25 km from the river mouth to the upstream limit of tidal influence. During the second day, longitudinal surveys were conducted over a distance of 6 km centred on the upstream station. The data reveal a turbidity maximum in the form of a high-concentration 'plug' of suspended mud that was advected downstream on the ebbing tide past the upper (HB) measurement station and which exchanged sediment with the seabed by settling at low slack water and by resuspension in the early flooding tide. The data suggest that fine sediment is transported landwards and trapped in the upper part of the tidal reach under these low-flow conditions. On the third day of measurements we repeated the experiments of the first day but later in the year, for a much higher freshwater flow. This interpretation of our data set highlights the potential contribution of a range of processes to the generation of the observed suspended-sediment signals, including resuspension of local bed sediment, advection by the tidal current, settling of suspended sediment over a long timescale compared to the advection timescale, advection of longitudinal gradients in suspended sediment, and suppression of vertical mixing by density stratification of the water column. The level of temporal and spatial detail afforded by these measurements allows a much clearer understanding of the timing and importance of vertical stratification on the transport of suspended particulate matter than is generally possible using fixed-point sensors.

  1. Freshwater monsoon related inputs in the Japan Sea: a diatom record from IODP core U1427

    Science.gov (United States)

    Ventura, C. P. L.; Lopes, C.

    2016-12-01

    Monsoon rainfall is the life-blood of more than half the world's population. Extensive research is being conducted in order to refine projections regarding the impact of anthropogenic climate change on these systems. The East Asian monsoon (EAM) plays a significant role in large-scale climate variability. Due to its importance to global climate and world's population, there is an urgent need for greater understanding of this system, especially during past climate changes. The input of freshwater from the monsoon precipitation brings specific markers, such as freshwater diatoms and specific diatom ecological assemblages that are preserved in marine sediments. Freshwater diatoms are easily identifiable and have been used in the North Pacific to reconstruct environmental conditions (Lopes et al 2006) and flooding episodes (Lopes and Mix, 2009). Here we show preliminary results of freshwater diatoms records that are linked with river discharge due to increase land rainfall that can be derived from Monsoon rainfall. We extend our preliminary study to the past 400ky.

  2. Sediment Flux, East Greenland Margin

    Science.gov (United States)

    1991-09-17

    of radiolarians and silicoflagellates, except in the top 40 cm in core 5A and the top 10 cm in core 10 A, where layers of sponge spicules are...However, to understand several issues of importance in marine geology, such information is vital. Issues such as ice sheet to deep- 2 sea sediment...properties of the uppermost 10-20 m of sediment is analagous to the upper "postglacial" unit that is typical of the late Quaternary marine succession along

  3. When and how? Freshwater mussel recolonization in Lake Orta

    Directory of Open Access Journals (Sweden)

    Nicoletta Riccardi

    2016-04-01

    Full Text Available Thanks to a video posted on a social network, live mussels of Unio elongatulus, have been recorded from Lake Orta (Italy over one century after the last (and only report. With its long and well documented history of pollution, Lake Orta offers the opportunity to document the post-extirpation recovery of freshwater unionid mussels. This case evidences that recovery/recolonization is possible despite a high devastation in the past, and permits to evaluate how fast recolonization may occur, in which way, and in what conditions.  The answer to the 'how fast' was sought by estimating the age of the larger and seemingly older individuals of the population. To address the 'in which way' we compared the haplotypes of Lake Orta specimens of Unio elongatulus (the only species present with those of surrounding populations. We concluded that, since Lake Orta lacks a direct connection with the putative source populations, colonizing mussels were almost certainly transported by fish carrying glochidia that were used for lake restocking after liming. Data from the long-term monitoring of water chemistry and sediments have allowed defining what conditions proved to be suitable for survival making possible the start of mussels recovery. But not only water and sediment quality matters for mussels recovery, which was delayed by nearly ten years after the reappearance of fish. This delay reflects the need of the whole trophic chain to be reestablished to allow the survival of the suitable and healthy host-fish populations necessary for mussels reproduction.

  4. Toxicity of silicon carbide nanowires to sediment-dwelling invertebrates in water or sediment exposures

    Science.gov (United States)

    Mwangi, Joseph N.; Wang, Ning; Ritts, Andrew; Kunz, James L.; Ingersoll, Christopher G.; Li, Hao; Deng, Baolin

    2011-01-01

    Silicon carbide nanowires (SiCNW) are insoluble in water. When released into an aquatic environment, SiCNW would likely accumulate in sediment. The objective of this study was to assess the toxicity of SiCNW to four freshwater sediment-dwelling organisms: amphipods (Hyalella azteca), midges (Chironomus dilutus), oligochaetes (Lumbriculus variegatus), and mussels (Lampsilis siliquoidea). Amphipods were exposed to either sonicated or nonsonicated SiCNW in water (1.0 g/L) for 48 h. Midges, mussels, and oligochaetes were exposed only to sonicated SiCNW in water for 96 h. In addition, amphipods were exposed to sonicated SiCNW in whole sediment for 10 d (44% SiCNW on dry wt basis). Mean 48-h survival of amphipods exposed to nonsonicated SiCNW in water was not significantly different from the control, whereas mean survival of amphipods exposed to sonicated SiCNW in two 48-h exposures (0 or 15% survival) was significantly different from the control (90 or 98% survival). In contrast, no effect of sonicated SiCNW was observed on survival of midges, mussels, or oligochaetes. Survival of amphipods was not significantly reduced in 10-d exposures to sonicated SiCNW either mixed in the sediment or layered on the sediment surface. However, significant reduction in amphipod biomass was observed with the SiCNW either mixed in sediment or layered on the sediment surface, and the reduction was more pronounced for SiCNW layered on the sediment. These results indicated that, under the experimental conditions, nonsonicated SiCNW in water were not acutely toxic to amphipods, sonicated SiCNW in water were acutely toxic to the amphipods, but not to other organisms tested, and sonicated SiCNW in sediment affected the growth but not the survival of amphipods.

  5. Freshwater Commercial Bycatch: an Understated Conservation Problem

    Energy Technology Data Exchange (ETDEWEB)

    Raby, Graham D.; Colotelo, Alison HA; Blouin-Demers, Gabriel; Cooke, Steven J.

    2011-04-01

    Commercial fisheries bycatch in marine systems has been regarded as a global conservation concern by environmental groups, scientists, government, and the public for decades. Fortunately, some headway has been made to mitigate the negative impacts of bycatch in marine environments. In a survey of the literature, we found that despite freshwater commercial fisheries yields comprising 11% of the global commercial catch, bycatch research focusing on freshwater commercial fisheries represented only {approx}3% of the total bycatch literature. This paucity of research is particularly alarming given that freshwater animals and habitats are some of the world's most imperiled. The limited inland bycatch literature that does exist includes examples of population declines attributed to commercial bycatch (e.g., freshwater dolphins in the Yangtze River in China) and illustrates that in some systems bycatch can be substantial (e.g., lake trout bycatch in the Laurentian Great Lakes). Encouraging results from the marine realm can serve as models for bycatch research in freshwater, and lead to measurable gains in conservation of freshwater ecosystems. We summarize existing work on inland bycatch in an effort to draw attention to this understated and understudied conservation problem.

  6. Chemistry of marine sediments

    International Nuclear Information System (INIS)

    Yen, T.F.

    1977-01-01

    Some topics considered are as follows: characterization of sediments in the vicinity of offshore petroleum production; thermal alteration experiments on organic matter in recent marine sediments as a model for petroleum genesis; composition of polluted bottom sediments in Great Lakes harbors; distribution of heavy metals in sediment fractions; recent deposition of lead off the coast of southern California; release of trace constituents from sediments resuspended during dredging operations; and migration of chemical constituents in sediment-seawater interfaces

  7. Sediment exchange between groin fields and main-stream

    Science.gov (United States)

    Qin, Jie; Zhong, Deyu; Wu, Teng; Wu, Lingli

    2017-10-01

    Sediment exchange between groin fields and the main-stream influences the transport and distribution of polluted sediment that represents a hazard for rivers and neighboring floodplains. Despite its practical significance, little research has been done on the sediment exchange process itself, and existing studies used to estimate the sediment exchange by morphological change. The sediment exchange process, however, differs from morphological variation and includes two behaviors: the entrance of main-stream sediment into groin fields and the movement of groin field sediment out of groin fields. Therefore, this study aims at examining this exchange process and exploring the mechanisms of different exchange phenomena. Experiments were conducted in a mobile-bed laboratory flume by using a novel experimental method that successfully separates the movement of groin fields sediment from that of main-stream sediment. In addition to traditional measurements, such as measurements of morphological changes, surface flow velocities, and bed-form propagation, the deposition of main-stream sediment in groin fields is measured in detail. The results demonstrate that morphological change cannot reflect the sediment exchange process. The deposition of main-stream sediment in groin fields is determined by the dynamics of sediment movement, in which bedload- and suspended-sediment-dominated processes exhibit different deposition patterns. The movement of groin field sediment out of groin fields is determined mainly by local scouring around groins.

  8. Why are there so few freshwater fish species in most estuaries?

    Science.gov (United States)

    Whitfield, A K

    2015-04-01

    The freshwater fish assemblage in most estuaries is not as species rich as the marine assemblage in the same systems. Coupled with this differential richness is an apparent inability by most freshwater fish species to penetrate estuarine zones that are mesohaline (salinity: 5·0-17·9), polyhaline (salinity: 18·0-29·9) or euhaline (salinity: 30·0-39·9). The reason why mesohaline waters are avoided by most freshwater fishes is difficult to explain from a physiological perspective as many of these species would be isosmotic within this salinity range. Perhaps, a key to the poor penetration of estuarine waters by freshwater taxa is an inability to develop chloride cells in gill filament epithelia, as well as a lack of other osmoregulatory adaptations present in euryhaline fishes. Only a few freshwater fish species, especially some of those belonging to the family Cichlidae, have become fully euryhaline and have successfully occupied a wide range of estuaries, sometimes even dominating in hyperhaline systems (salinity 40+). Indeed, this review found that there are few fish species that can be termed holohaline (i.e. capable of occupying waters with a salinity range of 0-100+) and, of these taxa, there is a disproportionally high number of freshwater species (e.g. Cyprinodon variegatus, Oreochromis mossambicus and Sarotherodon melanotheron). Factors such as increased competition for food and higher predation rates by piscivorous fishes and birds may also play an important role in the low species richness and abundance of freshwater taxa in estuaries. Added to this is the relatively low species richness of freshwater fishes in river catchments when compared with the normally higher diversity of marine fish species for potential estuarine colonization from the adjacent coastal waters. The almost complete absence of freshwater fish larvae from the estuarine ichthyoplankton further reinforces the poor representation of this guild within these systems. An explanation as

  9. Microbial Response to Experimentally Controlled Redox Transitions at the Sediment Water Interface

    Science.gov (United States)

    Frindte, Katharina; Allgaier, Martin; Grossart, Hans-Peter; Eckert, Werner

    2015-01-01

    The sediment–water interface of freshwater lakes is characterized by sharp chemical gradients, shaped by the interplay between physical, chemical and microbial processes. As dissolved oxygen is depleted in the uppermost sediment, the availability of alternative electron acceptors, e.g. nitrate and sulfate, becomes the limiting factor. We performed a time series experiment in a mesocosm to simulate the transition from aerobic to anaerobic conditions at the sediment–water interface. Our goal was to identify changes in the microbial activity due to redox transitions induced by successive depletion of available electron acceptors. Monitoring critical hydrochemical parameters in the overlying water in conjunction with a new sampling strategy for sediment bacteria enabled us to correlate redox changes in the water to shifts in the active microbial community and the expression of functional genes representing specific redox-dependent microbial processes. Our results show that during several transitions from oxic-heterotrophic condition to sulfate-reducing condition, nitrate-availability and the on-set of sulfate reduction strongly affected the corresponding functional gene expression. There was evidence of anaerobic methane oxidation with NOx. DGGE analysis revealed redox-related changes in microbial activity and expression of functional genes involved in sulfate and nitrite reduction, whereas methanogenesis and methanotrophy showed only minor changes during redox transitions. The combination of high-frequency chemical measurements and molecular methods provide new insights into the temporal dynamics of the interplay between microbial activity and specific redox transitions at the sediment–water interface. PMID:26599000

  10. The First Detailed 2H and 18O Isoscapes of Freshwater in Scotland

    Science.gov (United States)

    Meier-Augenstein, W.; Hoogewerff, J.; Kemp, H. F.; Frew, D.

    2012-04-01

    Scotland's freshwater lochs and reservoirs provide a vital resource for sustaining biodiversity, agriculture, food production as well as for human consumption. Regular monitoring of freshwater quality by the Scottish Environmental Protection Agency (SEPA) fulfils the legislative requirements but new scientific methods involving stable isotope analysis present an opportunity for delivering on current and nascent government policies [1] and gaining a greater understanding of Scottish waters and their importance in the context of climate change, environmental sustainability and the aforementioned functions. In brief, 2H and 18O isoscapes of Scottish freshwater could be used to support fundamental and applied research in: • Climate change - These first ever isoscapes will provide a baseline against which future environmental impact can be assessed due to changes in the characteristic isotope composition of freshwater lochs and reservoirs. • Scottish branding - Location specific stable isotope signatures of Scottish freshwater have the potential to be used as a tool for provenancing and thus protecting premium Scottish produce such as Scottish beef, Scottish berries and Scottish Whisky. During 2011, freshwater samples were collected with the support of SEPA from more than 80 freshwater lochs and reservoirs across Scotland. Here we present the result of the 2H and 18O stable isotope analyses of these water samples together with the first isoscapes generated based on these data. [1] Adaptation Framework - Adapting Our Ways: Managing Scotland's Climate Risk (2009): Scotland's Biodiversity: It's in Your Hands - A strategy for the conservation and enhancement of biodiversity in Scotland (2005); Recipe For Success - Scotland's National Food and Drink Policy (2009); Scottish Planning Policy Environmental Report (2009); Scottish Planning Policy (SPP) 15 Planning for Rural Development (2005); National Planning Policy Guideline (NPPG) 14: Natural Heritage (1999).

  11. Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh - a whole ecosystem 15N enrichment study

    NARCIS (Netherlands)

    Gribsholt, B.; Struyf, E.; Tramper, A.; de Brabandere, L.; Brion, N.; van Damme, S.; Meire, P.; Dehairs, F.; Middelburg, J.J.; Boschker, H.T.S.

    2007-01-01

    An intact tidal freshwater marsh system (3477 m2) was labelled by adding 15N-ammonium as a tracer to the flood water inundating the ecosystem. The appearance and retention of 15N-label in different marsh components (leaves, roots, sediment, leaf litter and invertebrate fauna) was followed over 15

  12. Diversity and distribution of freshwater testate amoebae (protozoa) along latitudinal and trophic gradients in China.

    Science.gov (United States)

    Ju, Lihua; Yang, Jun; Liu, Lemian; Wilkinson, David M

    2014-11-01

    Freshwater microbial diversity is subject to multiple stressors in the Anthropocene epoch. However, the effects of climate changes and human activities on freshwater protozoa remain poorly understood. In this study, the diversity and distribution of testate amoebae from the surface sediments were investigated in 51 Chinese lakes and reservoirs along two gradients, latitude and trophic status. A total of 169 taxa belonging to 24 genera were identified, and the most diverse and dominant genera were Difflugia (78 taxa), Centropyxis (26 taxa) and Arcella (12 taxa). Our analysis revealed that biomass of testate amoebae decreased significantly along the latitudinal gradient, while Shannon-Wiener indices and species richness presented an opposite trend (P trophic status (P trophic status on diversity and distribution of testate amoebae in China. Therefore, our results provide valuable baseline data on testate amoebae and contribute to lake management and our understanding of the large-scale global patterns in microorganism diversity.

  13. Toxicity of sediment collected upriver and downriver of major cities along the lower Mississippi River

    Science.gov (United States)

    Winger, P.V.; Lasier, P.J.

    1998-01-01

    The Lower Mississippi River contributes significantly to the biodiversity and ecological stability of the alluvial valley. Agricultural, industrial and municipal developments have historically impacted environmental quality of the river. Toxicity of sediment and sediment pore water was used to assess the current effects of major cities on sediment quality along the Lower Mississippi River. Composite sediment samples were collected from four sites upriver and four sites downriver of five major cities: Cairo, IL; Memphis, TN; Vicksburg, MS; Baton Rouge, LA; and New Orleans, LA. Following EPA's standard methods for acute toxicity testing of freshwater solid-phase sediment, Hyalella azteca were exposed to the sediments for 10 d with two water renewals per day. Hyalella azteca were also exposed for 96 h to pore water extracted from the sediments. After the initial tests, the animals were exposed to ultraviolet light for 12 h. Sediments were analyzed for organics (organochlorine pesticides, PCBs, organophosphate insecticides, and PAHs) and metals (Cr, Cu, Pb, Mn, Ni, Zn). With the exception of upriver from Memphis, solid-phase sediments were not toxic to H. azteca. Pore water from sediments collected upriver of Memphis showed slight toxicity. Exposure of H. azteca to ultraviolet light did not increase the toxicity of the sediment or pore-water samples, indicating a lack of PAH toxicity. Chemical analyses did not reveal any contaminant levels of concern in the sediments. Based on toxicity testing and chemical analyses, quality of sediments collected from the Lower Mississippi was good, with the exception of sites sampled upriver of Memphis.

  14. Levels and distribution of polybrominated diphenyl ethers (PBDEs) in the freshwater environment surrounding a PBDE manufacturing plant in China

    International Nuclear Information System (INIS)

    Xu Jie; Gao Zishen; Xian Qiming; Yu Hongxia; Feng Jianfang

    2009-01-01

    Polybrominated diphenyl ethers (PBDEs) were determined in muscle, liver and eggs of freshwater fishes and surface sediments from the Nongkang River in Jinhu, Jiangsu Province, China. The present study is the first to report PBDE concentrations in the freshwater environment surrounding a PBDE manufacturing plant in China. The concentrations of 13 PBDE congeners in muscle, liver and eggs of freshwater fishes ranged from < LOD to 130, < LOD to 252 and < LOD to 33.3 ng/g lipid wt, respectively, while the concentrations of 13 PBDE congeners in surface sediments from sewage outfall, upstream and downstream of the river were 52, 9.2, 7.1 ng/g organic carbon wt, respectively. Contamination by PBDEs in this area was not serious when compared with other regions of the world. A relatively high proportion of BDE-183 was found, consistent with the octa-BDE technical mixtures from the manufacturing plant by the side of the river. - The first study to report concentrations of PBDEs in the freshwater environment surrounding a PBDE manufacturing plant in China.

  15. Higher diversity of ammonia/ammonium-oxidizing prokaryotes in constructed freshwater wetland than natural coastal marine wetland

    OpenAIRE

    Wang, Yong-Feng; Gu, Ji-Dong

    2012-01-01

    Anaerobic ammonium-oxidizing (anammox) bacteria, aerobic ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) are three groups of ammonium/ammonia-oxidizing prokaryotes (AOPs) that are involved in the nitrogen cycle. This research compared the AOP communities in a constructed freshwater wetland with a natural coastal marine wetland in the subtropical Hong Kong. Both vegetated/rhizosphere and nonvegetated sediments were investigated to identify the effects of different macroph...

  16. Comparison of acetate turnover in methanogenic and sulfate- reducing sediments by radiolabeling and stable isotope labeling and by use of specific inhibitors: Evidence for isotopic exchange

    NARCIS (Netherlands)

    De Graaf, W.; Wellsbury, P.; Parkes, R.J.; Cappenberg, T.E.

    1996-01-01

    Acetate turnover in the methanogenic freshwater anoxic sediments of Lake Vechten, The Netherlands, and in anoxic sediments from the Tamar Estuary, United Kingdom, and the Grosser Jasmunder Bodden, Germany, the latter two dominated by sulfate reduction, was determined, Stable isotopes and

  17. Successful ageing

    DEFF Research Database (Denmark)

    Kusumastuti, Sasmita; Derks, Marloes G. M.; Tellier, Siri

    2016-01-01

    . METHODS: We performed a novel, hypothesis-free and quantitative analysis of citation networks exploring the literature on successful ageing that exists in the Web of Science Core Collection Database using the CitNetExplorer software. Outcomes were visualized using timeline-based citation patterns...... himself or an outsider judges the situation. These different points of view help to explain the disability paradox, as successful ageing lies in the eyes of the beholder....

  18. In-depth tanscriptomic analysis on giant freshwater prawns.

    Directory of Open Access Journals (Sweden)

    Maizatul Izzah Mohd-Shamsudin

    Full Text Available Gene discovery in the Malaysian giant freshwater prawn (Macrobrachium rosenbergii has been limited to small scale data collection, despite great interest in various research fields related to the commercial significance of this species. Next generation sequencing technologies that have been developed recently and enabled whole transcriptome sequencing (RNA-seq, have allowed generation of large scale functional genomics data sets in a shorter time than was previously possible. Using this technology, transcriptome sequencing of three tissue types: hepatopancreas, gill and muscle, has been undertaken to generate functional genomics data for M. rosenbergii at a massive scale. De novo assembly of 75-bp paired end Ilumina reads has generated 102,230 unigenes. Sequence homology search and in silico prediction have identified known and novel protein coding candidate genes (∼24%, non-coding RNA, and repetitive elements in the transcriptome. Potential markers consisting of simple sequence repeats associated with known protein coding genes have been successfully identified. Using KEGG pathway enrichment, differentially expressed genes in different tissues were systematically represented. The functions of gill and hepatopancreas in the context of neuroactive regulation, metabolism, reproduction, environmental stress and disease responses are described and support relevant experimental studies conducted previously in M. rosenbergii and other crustaceans. This large scale gene discovery represents the most extensive transcriptome data for freshwater prawn. Comparison with model organisms has paved the path to address the possible conserved biological entities shared between vertebrates and crustaceans. The functional genomics resources generated from this study provide the basis for constructing hypotheses for future molecular research in the freshwater shrimp.

  19. Hydrogeochemistry and sustainability of freshwater lenses in the Samborombón Bay wetland, Argentina

    Science.gov (United States)

    Carol, Eleonora; García, Leandro; Borzi, Guido

    2015-07-01

    Freshwater lenses constitute one of the most vulnerable aquifer systems in the world, especially in coastal wetland areas. The objectives of this work are to determine the hydrogeochemical processes that regulate the quality of the freshwater lenses in a sector of the Samborombón Bay wetland, and to assess their sustainability as regards the development of mining activities. A hydrochemical evaluation of groundwater was undertaken on the basis of major ion, trace and environmental isotope data. The deterioration in time of the freshwater lenses in relation to mining was studied on the basis of the analysis of topographic charts, aerial photography and satellite imaging. The results obtained show that the CO2(g) that dissolves in the rainwater infiltrating and recharging the lenses is converted to HCO3-, which dissolves the carbonate facies of the sediment. The exchange of Ca2+ for Na+, the incongruent dissolution of basic plagioclase and the reprecipitation of carbonate produce a change of the Ca-HCO3 facies to Na-HCO3. In depth, the pH increases with the groundwater flow, and the volcanic glassis dissolved, releasing F-and As. Besides, the evapotranspiration processes cause the saline content to increase slightly. As the only sources of drinking water in the region are the freshwater lenses occurring in the shell ridges, mining operations have deteriorated this resource and decreased the freshwater reserves in the lenses. The study undertaken made it possible to develop some preservation, remediation and management guidelines aimed at the sustainability of the water resources in the region.

  20. PROFILE: Management of Sedimentation in Tropical Watersheds.

    Science.gov (United States)

    NAGLE; FAHEY; LASSOIE

    1999-05-01

    / The sedimentation of reservoirs is a serious problem throughout the tropics, yet most attempts to control sedimentation in large river basins have not been very successful. Reliable information on erosion rates and sources of sediments has been lacking. In regions where geologically unstable terrain combines with high rainfall, natural erosion rates might be so high that the effects of human activity are limited. Estimates of natural erosion in these situations often have been poor because of the episodic nature of most erosion during large storms and because mass-wasting may supply much of the sediment. The predominance of mass-wasting in some watersheds can result in an unexpectedly high ratio of bedload to suspended load, shifting sedimentation to "live" rather than "dead" storage within reservoirs. Furthermore, the inappropriate use of the Universal Soil Loss Equation to assess the effectiveness of erosion control measures has led to inaccurate estimates of the sediment reduction benefits that could accrue to watershed treatment efforts. Although reducing erosion from cultivated areas is desirable for other reasons, efforts aimed at reducing reservoir sedimentation by controlling agricultural sources of erosion may have limited benefits if the principal sources are of natural origin or are associated with construction of the dams and reservoirs and with rural roads and trails. Finally, the most appropriate locations for watershed rehabilitation depend on the magnitude of temporary storage of colluvium and alluvium within the river basin: Where storage volume is large and residence time of sediment very long, reducing agricultural erosion may have limited impacts on sedimentation within the expected life of a reservoir. Systematic development and analysis of sediment budgets for representative watersheds is needed to address these limitations and thereby improve both the planning of river basin development schemes and the allocation of resources towards

  1. Sulfate reduction in freshwater peatlands

    International Nuclear Information System (INIS)

    Oequist, M.

    1996-01-01

    This text consist of two parts: Part A is a literature review on microbial sulfate reduction with emphasis on freshwater peatlands, and part B presents the results from a study of the relative importance of sulfate reduction and methane formation for the anaerobic decomposition in a boreal peatland. The relative importance of sulfate reduction and methane production for the anaerobic decomposition was studied in a small raised bog situated in the boreal zone of southern Sweden. Depth distribution of sulfate reduction- and methane production rates were measured in peat sampled from three sites (A, B, and C) forming an minerotrophic-ombrotrophic gradient. SO 4 2- concentrations in the three profiles were of equal magnitude and ranged from 50 to 150 μM. In contrast, rates of sulfate reduction were vastly different: Maximum rates in the three profiles were obtained at a depth of ca. 20 cm below the water table. In A it was 8 μM h -1 while in B and C they were 1 and 0.05 μM h -1 , respectively. Methane production rates, however, were more uniform across the three nutrient regimes. Maximum rates in A (ca. 1.5 μg d -1 g -1 ) were found 10 cm below the water table, in B (ca. 1.0 μg d -1 g -1 ) in the vicinity of the water table, and in C (0.75 μg d -1 g -1 ) 20 cm below the water table. In all profiles both sulfate reduction and methane production rates were negligible above the water table. The areal estimates of methane production for the profiles were 22.4, 9.0 and 6.4 mmol m -2 d -1 , while the estimates for sulfate reduction were 26.4, 2.5, and 0.1 mmol m -2 d -1 , respectively. The calculated turnover times at the sites were 1.2, 14.2, and 198.7 days, respectively. The study shows that sulfate reducing bacteria are important for the anaerobic degradation in the studied peatland, especially in the minerotrophic sites, while methanogenic bacteria dominate in ombrotrophic sites Examination paper. 67 refs, 6 figs, 3 tabs

  2. Persistence and fate of some organophosphorus pesticides in sea sediments along east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sarkar, A.; SenGupta, R.

    and fate of these pesticides Rate of hydrolysis of these pesticides in freshwater, brackish water and sea-sediments followed the path of pseudo first order reaction The rate constants (K1) and the half life periods (T2) of these pesticides were determined...

  3. Post-depositional formation of vivianite-type minerals alters sediment phosphorus records

    NARCIS (Netherlands)

    DIjkstra, Nikki; Hagens, Mathilde; Egger, Matthias; Slomp, Caroline P.

    2018-01-01

    Phosphorus (P) concentrations in sediments are frequently used to reconstruct past environmental conditions in freshwater and marine systems, with high values thought to be indicative of a high biological productivity. Recent studies suggest that the post-depositional formation of vivianite, an

  4. A method for measuring effects of bioturbation and consolidation on erosion resistance of aquatic sediments

    NARCIS (Netherlands)

    Zambrano, L.; Beijer, J.A.J.; Roozen, F.C.J.M.; Scheffer, M.

    2005-01-01

    Sediment erosion by water movement affects turbidity and thus benthic communities in numerous aquatic systems. This aspect has been widely studied in coastal habitats and estuaries, but less studied in freshwater systems such as shallow lakes. Here we present a simple device to study the effects of

  5. Ecosystem Services : In Nordic Freshwater Management

    DEFF Research Database (Denmark)

    Magnussen, Kristin; Hasler, Berit; Zandersen, Marianne

    Human wellbeing is dependent upon and benefit from ecosystem services which are delivered by well-functioning ecosystems. Ecosystem services can be mapped and assessed consistently within an ecosystem service framework. This project aims to explore the use and usefulness of the ecosystem service...... framework in freshwater management, particularly water management according to the Water Framework Directive (WFD). There are several examples of how ecosystem services have been used in WFD related studies in all the Nordic countries. Most of them involve listing, describing and categorizing freshwater...... ecosystem services, while there are few comprehensive Cost Benefit Analyses and analyses of disproportionate costs that apply this framework. More knowledge about ecosystem services and the value of ecosystem services for freshwater systems is needed....

  6. Sulfate reduction and methanogenesis at a freshwater

    DEFF Research Database (Denmark)

    Iversen, Vibeke Margrethe Nyvang; Andersen, Martin Søgaard; Jakobsen, Rasmus

    The freshwater-seawater interface was studied in a ~9-m thick anaerobic aquifer located in marine sand and gravel with thin peat lenses. Very limited amounts of iron-oxides are present. Consequently, the dominating redox processes are sulfate reduction and methanogenesis, and the groundwater...... is enriched in dissolved sulfide, methane and bicarbonate. Under normal conditions the seawater-freshwater interface is found at a depth of 4 m at the coastline and reaches the bottom of the aquifer 40 m inland. However, occasional flooding of the area occurs, introducing sulfate to the aquifer. Groundwater...... chemistry was studied in a 120 m transect perpendicular to the coast. Cores were taken for radiotracer rate measurements of sulfate reduction and methanogenesis. In the saline part of the aquifer 35 m inland, sulfate reduction was the dominant process with rates of 0.1-10 mM/year. In the freshwater part 100...

  7. Successful ageing

    DEFF Research Database (Denmark)

    Bülow, Morten Hillgaard; Söderqvist, Thomas

    2014-01-01

    Since the late 1980s, the concept of ‘ successful ageing’ has set the frame for discourse about contemporary ageing research. Through an analysis of the reception to John W. Rowe and Robert L. Kahn's launch of the concept of ‘ successful ageing’ in 1987, this article maps out the important themes...... strategies; and the importance of individual, societal and scientific conceptualisations and understandings of ageing. By presenting an account of the recent historical uses, interpretations and critiques of the concept, the article unfolds the practical and normative complexities of ‘ successful ageing’....... and discussions that have emerged from the interdisciplinary field of ageing research. These include an emphasis on interdisciplinarity; the interaction between biology, psycho-social contexts and lifestyle choices; the experiences of elderly people; life-course perspectives; optimisation and prevention...

  8. Citation Success

    DEFF Research Database (Denmark)

    Vaio, Gianfranco Di; Waldenström, Daniel; Weisdorf, Jacob Louis

    2012-01-01

    This study examines the determinants of citation success among authors who have recently published their work in economic history journals. Besides offering clues about how to improve one's scientific impact, our citation analysis also sheds light on the state of the field of economic history....... Consistent with our expectations, we find that full professors, authors appointed at economics and history departments, and authors working in Anglo-Saxon and German countries are more likely to receive citations than other scholars. Long and co-authored articles are also a factor for citation success. We...... find similar patterns when assessing the same authors' citation success in economics journals. As a novel feature, we demonstrate that the diffusion of research — publication of working papers, as well as conference and workshop presentations — has a first-order positive impact on the citation rate....

  9. Freshwater exposure pathways in the Nordic countries

    International Nuclear Information System (INIS)

    Tveten, U.

    1984-06-01

    The report relates to a subproject under a Nordic project called ''Large reactor accidents - consequences and mitigating actions''. The report summarizes information available, primarily in the Nordic countries, on freshwater exposure pathways. Experimental and theoretical data concerning the deposition and run-off of the nuclides *sp90*Sr and*Sp137*Cs is presented. Internal exposure via drinking water and freshwater fish is dealt with, as well as external exposure due to swimming, boating, contact with fishing utensils and use of beach areas. In addition is exposure via irrigated agricultural products considered. (RF)

  10. Emergent macrophytes modify the abundance and community composition of ammonia oxidizers in their rhizosphere sediments.

    Science.gov (United States)

    Zhao, Dayong; He, Xiaowei; Huang, Rui; Yan, Wenming; Yu, Zhongbo

    2017-07-01

    Ammonia oxidation is a crucial process in global nitrogen cycling, which is catalyzed by the ammonia oxidizers. Emergent plants play important roles in the freshwater ecosystem. Therefore, it is meaningful to investigate the effects of emergent macrophytes on the abundance and community composition of ammonia oxidizers. In the present study, two commonly found emergent macrophytes (Zizania caduciflora and Phragmitas communis) were obtained from freshwater lakes and the abundance and community composition of the ammonia-oxidizing prokaryotes in the rhizosphere sediments of these emergent macrophytes were investigated. The abundance of the bacterial amoA gene was higher in the rhizosphere sediments of the emergent macrophytes than those of bulk sediments. Significant positive correlation was found between the potential nitrification rates (PNRs) and the abundance of bacterial amoA gene, suggesting that ammonia-oxidizing bacteria (AOB) might play an important role in the nitrification process of the rhizosphere sediments of emergent macrophytes. The Nitrosotalea cluster is the dominant ammonia-oxidizing archaea (AOA) group in all the sediment samples. Analysis of AOB group showed that the N. europaeal cluster dominated the rhizosphere sediments of Z. caduciflora and the bulk sediments, whereas the Nitrosospira cluster was the dominant AOB group in the rhizosphere sediments of P. communis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. HESS Opinions: A planetary boundary on freshwater use is misleading

    Science.gov (United States)

    Heistermann, Maik

    2017-07-01

    In 2009, a group of prominent Earth scientists introduced the planetary boundaries (PB) framework: they suggested nine global control variables, and defined corresponding thresholds which, if crossed, could generate unacceptable environmental change. The concept builds on systems theory, and views Earth as a complex adaptive system in which anthropogenic disturbances may trigger non-linear, abrupt, and irreversible changes at the global scale, and push the Earth system outside the stable environmental state of the Holocene. While the idea has been remarkably successful in both science and policy circles, it has also raised fundamental concerns, as the majority of suggested processes and their corresponding planetary boundaries do not operate at the global scale, and thus apparently lack the potential to trigger abrupt planetary changes. This paper picks up the debate with specific regard to the planetary boundary on global freshwater use. While the bio-physical impacts of excessive water consumption are typically confined to the river basin scale, the PB proponents argue that water-induced environmental disasters could build up to planetary-scale feedbacks and system failures. So far, however, no evidence has been presented to corroborate that hypothesis. Furthermore, no coherent approach has been presented to what extent a planetary threshold value could reflect the risk of regional environmental disaster. To be sure, the PB framework was revised in 2015, extending the planetary freshwater boundary with a set of basin-level boundaries inferred from environmental water flow assumptions. Yet, no new evidence was presented, either with respect to the ability of those basin-level boundaries to reflect the risk of regional regime shifts or with respect to a potential mechanism linking river basins to the planetary scale. So while the idea of a planetary boundary on freshwater use appears intriguing, the line of arguments presented so far remains speculative and

  12. HESS Opinions: A planetary boundary on freshwater use is misleading

    Directory of Open Access Journals (Sweden)

    M. Heistermann

    2017-07-01

    Full Text Available In 2009, a group of prominent Earth scientists introduced the planetary boundaries (PB framework: they suggested nine global control variables, and defined corresponding thresholds which, if crossed, could generate unacceptable environmental change. The concept builds on systems theory, and views Earth as a complex adaptive system in which anthropogenic disturbances may trigger non-linear, abrupt, and irreversible changes at the global scale, and push the Earth system outside the stable environmental state of the Holocene. While the idea has been remarkably successful in both science and policy circles, it has also raised fundamental concerns, as the majority of suggested processes and their corresponding planetary boundaries do not operate at the global scale, and thus apparently lack the potential to trigger abrupt planetary changes.This paper picks up the debate with specific regard to the planetary boundary on global freshwater use. While the bio-physical impacts of excessive water consumption are typically confined to the river basin scale, the PB proponents argue that water-induced environmental disasters could build up to planetary-scale feedbacks and system failures. So far, however, no evidence has been presented to corroborate that hypothesis. Furthermore, no coherent approach has been presented to what extent a planetary threshold value could reflect the risk of regional environmental disaster. To be sure, the PB framework was revised in 2015, extending the planetary freshwater boundary with a set of basin-level boundaries inferred from environmental water flow assumptions. Yet, no new evidence was presented, either with respect to the ability of those basin-level boundaries to reflect the risk of regional regime shifts or with respect to a potential mechanism linking river basins to the planetary scale.So while the idea of a planetary boundary on freshwater use appears intriguing, the line of arguments presented so far remains

  13. Threatened and Endangered Freshwater Fish and Mussel Species Richness

    Data.gov (United States)

    U.S. Environmental Protection Agency — These data represent predicted current distributions of all US listed Threatened and Endangered freshwater fish and freshwater mussels in the Middle-Atlantic region....

  14. Indicators: Sediment Diatoms

    Science.gov (United States)

    Diatoms are a type of algae that are typically abundant in marine and freshwater ecosystems. They have inorganic cell walls made up of silica (glass). Diatoms most commonly grow suspended in water, although they can also attach to substrates.

  15. Successful modeling?

    Science.gov (United States)

    Lomnitz, Cinna

    Tichelaar and Ruff [1989] propose to “estimate model variance in complicated geophysical problems,” including the determination of focal depth in earthquakes, by means of unconventional statistical methods such as bootstrapping. They are successful insofar as they are able to duplicate the results from more conventional procedures.

  16. Citation Success

    DEFF Research Database (Denmark)

    Di Vaio, Gianfranco; Waldenström, Daniel; Weisdorf, Jacob Louis

    This study analyses determinants of citation success among authors publishing in economic history journals. Bibliometric features, like article length and number of authors, are positively correlated with the citation rate up to a certain point. Remarkably, publishing in top-ranked journals hardl...

  17. Project Success.

    Science.gov (United States)

    Baehr, Rufus F.

    This report reviews the remedial education program--Project Success--at the Urban Education Center, City Colleges of Chicago (Illinois). The major features of the program are outlined and its operation and evaluation are discussed. Student performance and characteristics are then tabularly compared, based on their groupings as…

  18. The model marine diatom Thalassiosira pseudonana likely descended from a freshwater ancestor in the genus Cyclotella

    Directory of Open Access Journals (Sweden)

    Julius Matthew L

    2011-05-01

    Full Text Available Abstract Background Publication of the first diatom genome, that of Thalassiosira pseudonana, established it as a model species for experimental and genomic studies of diatoms. Virtually every ensuing study has treated T. pseudonana as a marine diatom, with genomic and experimental data valued for their insights into the ecology and evolution of diatoms in the world's oceans. Results The natural distribution of T. pseudonana spans both marine and fresh waters, and phylogenetic analyses of morphological and molecular datasets show that, 1 T. pseudonana marks an early divergence in a major freshwater radiation by diatoms, and 2 as a species, T. pseudonana is likely ancestrally freshwater. Marine strains therefore represent recent recolonizations of higher salinity habitats. In addition, the combination of a relatively nondescript form and a convoluted taxonomic history has introduced some confusion about the identity of T. pseudonana and, by extension, its phylogeny and ecology. We resolve these issues and use phylogenetic criteria to show that T. pseudonana is more appropriately classified by its original name, Cyclotella nana. Cyclotella contains a mix of marine and freshwater species and so more accurately conveys the complexities of the phylogenetic and natural histories of T. pseudonana. Conclusions The multitude of physical barriers that likely must be overcome for diatoms to successfully colonize freshwaters suggests that the physiological traits of T. pseudonana, and the genes underlying those traits, might differ from those of strictly marine diatoms. The freshwater ancestry of T. pseudonana might therefore confound generalizations about the physiological and metabolic properties of marine diatoms. The freshwater component of T. pseudonana's history merits careful consideration in the interpretation of experimental data collected for this important model species.

  19. Determining the sources of fine-grained sediment using the Sediment Source Assessment Tool (Sed_SAT)

    Science.gov (United States)

    Gorman Sanisaca, Lillian E.; Gellis, Allen C.; Lorenz, David L.

    2017-07-27

    A sound understanding of sources contributing to instream sediment flux in a watershed is important when developing total maximum daily load (TMDL) management strategies designed to reduce suspended sediment in streams. Sediment fingerprinting and sediment budget approaches are two techniques that, when used jointly, can qualify and quantify the major sources of sediment in a given watershed. The sediment fingerprinting approach uses trace element concentrations from samples in known potential source areas to determine a clear signature of each potential source. A mixing model is then used to determine the relative source contribution to the target suspended sediment samples.The computational steps required to apportion sediment for each target sample are quite involved and time intensive, a problem the Sediment Source Assessment Tool (Sed_SAT) addresses. Sed_SAT is a user-friendly statistical model that guides the user through the necessary steps in order to quantify the relative contributions of sediment sources in a given watershed. The model is written using the statistical software R (R Core Team, 2016b) and utilizes Microsoft Access® as a user interface but requires no prior knowledge of R or Microsoft Access® to successfully run the model successfully. Sed_SAT identifies outliers, corrects for differences in size and organic content in the source samples relative to the target samples, evaluates the conservative behavior of tracers used in fingerprinting by applying a “Bracket Test,” identifies tracers with the highest discriminatory power, and provides robust error analysis through a Monte Carlo simulation following the mixing model. Quantifying sediment source contributions using the sediment fingerprinting approach provides local, State, and Federal land management agencies with important information needed to implement effective strategies to reduce sediment. Sed_SAT is designed to assist these agencies in applying the sediment fingerprinting

  20. Freshwater crayfish invasions in South Africa: past, present and ...

    African Journals Online (AJOL)

    Freshwater crayfish invasions have been studied around the world, but less so in Africa, a continent devoid of native freshwater crayfish. The present study reviews historical and current information on alien freshwater crayfish species introduced into South Africa and aims to indicate which areas are at risk from invasion.

  1. Field and model investigations of freshwater lenses in coastal aquifers

    NARCIS (Netherlands)

    Pauw, P.S.

    2015-01-01

    A major problem of sustaining freshwater supply from freshwater lens is the invasion of saline groundwater into a fresh groundwater body. In many coastal areas saltwater intrusion has led to well closure and reduced freshwater supply. Furthermore, in the future saltwater intrusion is expected to

  2. Assessment, modelization and analysis of 106 Ru experimental transfers through a freshwater trophic system

    International Nuclear Information System (INIS)

    Vray, F.

    1994-01-01

    Experiments are carried out in order to study 106 RU transfers through a freshwater ecosystem including 2 abiotic compartments (water and sediment) and 3 trophic levels (10 species). Experimental results are expressed mathematically so as they can be included into a global model which is then tested in two different situations. The comparison of the available data concerning the in situ measured concentrations to the corresponding calculated ones validates the whole procedure. Analysis of the so validated results lightens ruthenium distribution process in the environment. The rare detection of this radionuclide in organisms living in areas contaminated by known meaningful releases can be explained by a relativity high detection limit and by a slight role of the sediment as a secondary contamination source. (author). 78 figs., 18 tabs

  3. Platinum uptake by the freshwater isopod Asellus Aquaticus in urban rivers

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, S.; Morrison, G.M. [Department of Sanitary Engineering, Chalmers University of Technology, S-412 96 Goeteborg (Sweden)

    1999-09-01

    Platinum has been increasing in the environment as a result of emissions from catalytic converters. The platinum emitted is principally located in the vicinity of roads but might be transported to urban rivers through highway and urban run-off water. Platinum concentrations in the freshwater isopod Asellus aquaticus were measured for two urban rivers and a stormwater detention pond. Concentrations ranged from 0.04 to 12.4 {mu}g g{sup -1} for direct analysis and from 0.16 to 4.5 {mu}g g{sup -1} after depuration. Analyses of water, pore water and sediments indicate that platinum in urban rivers is mostly found in the sediments and these provide the major contribution of platinum to Asellus aquaticus. Exposure experiments showed the importance of platinum speciation for uptake.

  4. Dominance and population structure of freshwater crabs ...

    African Journals Online (AJOL)

    1997-02-06

    Feb 6, 1997 ... CHASE, l.D. 1974. Models of hierarchy formation in animal societies. Behav. Sct. 19: 374-382. DU PREEZ, H.H., STEENKAMP, V.E. & SCHOONBEE, HJ. 1993. Bioaccumulation of zinc and lead in selected tissues and organs of the freshwater crab. PotamonQutes warreni. Sci. Tot. Environ. Suppl.: 469-478.

  5. Petroleum hydrocarbon degrading capability of freshwater ...

    African Journals Online (AJOL)

    Petroleum hydrocarbon degrading capability and growth profile of indigenous filamentous freshwater fungi from four (4) different streams were determined in vitro. The result indicated that the streams under investigation contained an average heterotrophic fungal count of 5.55 0.25x105 cfu ml-1 while the mean count of ...

  6. Wnt signaling and polarity in freshwater sponges.

    Science.gov (United States)

    Windsor Reid, Pamela J; Matveev, Eugueni; McClymont, Alexandra; Posfai, Dora; Hill, April L; Leys, Sally P

    2018-02-02

    The Wnt signaling pathway is uniquely metazoan and used in many processes during development, including the formation of polarity and body axes. In sponges, one of the earliest diverging animal groups, Wnt pathway genes have diverse expression patterns in different groups including along the anterior-posterior axis of two sponge larvae, and in the osculum and ostia of others. We studied the function of Wnt signaling and body polarity formation through expression, knockdown, and larval manipulation in several freshwater sponge species. Sponge Wnts fall into sponge-specific and sponge-class specific subfamilies of Wnt proteins. Notably Wnt genes were not found in transcriptomes of the glass sponge Aphrocallistes vastus. Wnt and its signaling genes were expressed in archaeocytes of the mesohyl throughout developing freshwater sponges. Osculum formation was enhanced by GSK3 knockdown, and Wnt antagonists inhibited both osculum development and regeneration. Using dye tracking we found that the posterior poles of freshwater sponge larvae give rise to tissue that will form the osculum following metamorphosis. Together the data indicate that while components of canonical Wnt signaling may be used in development and maintenance of osculum tissue, it is likely that Wnt signaling itself occurs between individual cells rather than whole tissues or structures in freshwater sponges.

  7. Freshwater savings from marine protein consumption

    Science.gov (United States)

    Gephart, Jessica A.; Pace, Michael L.; D'Odorico, Paolo

    2014-01-01

    Marine fisheries provide an essential source of protein for many people around the world. Unlike alternative terrestrial sources of protein, marine fish production requires little to no freshwater inputs. Consuming marine fish protein instead of terrestrial protein therefore represents freshwater savings (equivalent to an avoided water cost) and contributes to a low water footprint diet. These water savings are realized by the producers of alternative protein sources, rather than the consumers of marine protein. This study quantifies freshwater savings from marine fish consumption around the world by estimating the water footprint of replacing marine fish with terrestrial protein based on current consumption patterns. An estimated 7 600 km3 yr-1 of water is used for human food production. Replacing marine protein with terrestrial protein would require an additional 350 km3 yr-1 of water, meaning that marine protein provides current water savings of 4.6%. The importance of these freshwater savings is highly uneven around the globe, with savings ranging from as little as 0 to as much as 50%. The largest savings as a per cent of current water footprints occur in Asia, Oceania, and several coastal African nations. The greatest national water savings from marine fish protein occur in Southeast Asia and the United States. As the human population increases, future water savings from marine fish consumption will be increasingly important to food and water security and depend on sustainable harvest of capture fisheries and low water footprint growth of marine aquaculture.

  8. Herbivory on freshwater and marine macrophytes

    NARCIS (Netherlands)

    Bakker, Elisabeth S.; Wood, Kevin A.; Pagès, Jordi F.; Veen, G.F.; Christianen, Marjolijn J.A.; Santamaría, Luis; Nolet, Bart A.; Hilt, Sabine

    2016-01-01

    Until the 1990s, herbivory on aquatic vascular plants was considered to be of minor importance, and the predominant view was that freshwater and marine macrophytes did not take part in the food web: their primary fate was the detritivorous pathway. In the last 25 years, a substantial body of

  9. Dactylobiotus luci , a new freshwater tardigrade (Eutardigrada ...

    African Journals Online (AJOL)

    A new freshwater eutardigrade, Dactylobiotus luci sp. nov., is described from a permanent marsh pool (Zaphania's Pool) at 4225 m elevation in the Alpine zone of the Rwenzori Mountains, Uganda. The new species is most similar to D. dervizi Biserov, 1998 in the shape of the egg processes, absence of papillae and ...

  10. Heliozoa from Nigeria | Wujek | Tropical Freshwater Biology

    African Journals Online (AJOL)

    A total of seven scaled protistans were observed from four freshwater sites in Nigeria. They include the holiozoan genera Acanthocystis, Polyplacocystis, Pterocystis, and Raphidiophrys. All are new records for Africa. KEY WORDS: Heliozoa, Protozoa, Acanthocystis, Polyplacocystis, Pterocystis, Raphidiophrys Tropical ...

  11. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    2000-01-01

    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had

  12. Effects of Pollution on Freshwater Invertebrates.

    Science.gov (United States)

    Buikema, A. L., Jr.; Herricks, E. E.

    1978-01-01

    Presents a literature review of the effects of pollution on freshwater invertebrates, covering publications of 1976-77. Some of the areas covered are: (1) toxicant effects on invertebrates; (2) microcosm and community effects, and (3) biological control of aquatic life. A list of 123 references is also presented. (HM)

  13. Quantal Response Of Freshwater Shrimp ( Desmocaris trispinosa ...

    African Journals Online (AJOL)

    The quantal-response of freshwater shrimp (Desmocaris trispinosa) to the toxicity of five azo dyes was studied. Generally, increase in percentage mortality of the organisms was obtained with increases in concentration of the toxicants and exposure time. The median lethal concentration50 (LC50) and median lethal ...

  14. Microplastic effect thresholds for freshwater benthic macroinvertebrates

    NARCIS (Netherlands)

    Redondo Hasselerharm, P.E.; Dede Falahudin, Dede; Peeters, E.T.H.M.; Koelmans, A.A.

    2018-01-01

    Now that microplastics have been detected in lakes, rivers and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates

  15. 2008 NWFSC Tidal Freshwater Genetics Results

    Energy Technology Data Exchange (ETDEWEB)

    David Teel

    2009-05-01

    Genetic Analysis of Juvenile Chinook Salmon for inclusion in 'Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008. Annual Report to Bonneville Power Administration, Contract DE-AC05-76RL01830.'

  16. Review: Freshwater conservation planning in South Africa ...

    African Journals Online (AJOL)

    Review: Freshwater conservation planning in South Africa: Milestones to date and catalysts for implementation. ... To this end we highlight 4 potential catalysts for effective implementation in the receiving environment, namely, absorptive capacity, multi-party cooperation, science extension and adaptive management.

  17. Benthic freshwater nematode community dynamics under conditions ...

    African Journals Online (AJOL)

    Studies of the influence of fish aquaculture on benthic freshwater nematode assemblages are scarce, but could provide a way of gauging environmental effects. The abundance and diversity of nematode assemblages in response to Oreochromis niloticus aquaculture were investigated in Kafr El-Sheikh Governorate, Egypt, ...

  18. Novel Synechococcus genomes reconstructed from freshwater reservoirs

    Czech Academy of Sciences Publication Activity Database

    Cabello-Yeves, P.J.; Haro-Moreno, J.M.; Martin-Cuadrado, A.B.; Ghai, Rohit; Picazo, A.; Camacho, A.; Rodriguez-Valera, F.

    2017-01-01

    Roč. 8, June (2017), č. článku 1151. ISSN 1664-302X R&D Projects: GA ČR(CZ) GA17-04828S Institutional support: RVO:60077344 Keywords : Synechococcus * picocyanobacteria * freshwater reservoirs * metagenomics * abundance Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.076, year: 2016

  19. Project Lifescape – Freshwater Fishes: Catfishes

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 4. Project Lifescape – Freshwater Fishes: Catfishes. R J Ranjit Daniels. Classroom Volume 5 Issue 4 April 2000 pp 97-107. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/005/04/0097-0107 ...

  20. What Controls Sediment Retention in an Emerging Delta?

    Science.gov (United States)

    Keogh, M.; Kolker, A.

    2016-12-01

    What controls sediment retention in an emerging delta? Here, we examine the effects of river discharge and flow velocity on sediment retention rate, using a developing crevasse splay in the Lower Mississippi Delta as a study location. With a controlled discharge that ranges from 28 to 280 m3/s, Davis Pond Freshwater Diversion connects the Mississippi River to the adjacent wetland, allowing river water, sediment, and nutrients to flow into the marsh. Although Davis Pond was primarily designed to regulate salinity within Barataria Basin rather than to build land, a new crevasse splay has recently emerged at the mouth of the diversion's outfall channel. Short (5 cm) sediment cores were collected at 22 locations around the Davis Pond receiving basin in spring 2015, fall 2015, and spring 2016. All cores were analyzed for sediment geotechnical parameters including organic content, bulk density, and grain size. Sediment input into the receiving basin was calculated using a ratings curve. Activity of the radioisotope beryllium-7 was used to calculate rates of sediment accumulation and retention. We find that while sediment input is greater during high flow, rate of retention is greater during low flow. This is likely due to the increase in flow velocity that accompanies high discharge, which retains sediment in suspension and leads to more throughput of material. Furthermore, the diversion operation regime of sustained low flow punctuated by short-duration high discharge events has increased soil bulk density, mineral sediment accumulation, and marsh platform elevation. River diversions such as Davis Pond mimic the land-building processes of natural crevasse splays and provide a promising method to restore deltaic wetlands worldwide.

  1. Agrobacterium-mediated transformation of three freshwater microalgal strains.

    Science.gov (United States)

    Sanitha, Mary; Radha, Sudhakar; Fatima, Anwar Aliya; Devi, Selvaraju Gayathri; Ramya, Mohandass

    2014-01-01

    Microalgal transformation has gained interest in recent years. Agrobacterium-mediated transformation remains as the most efficient method for the development of transgenic plants and microalgae due to its wide host range, inexpensive procedure and transfer of large segments of DNA. In the present study, three different microalgal species were isolated from freshwater environment and identified based on the morphological characteristics and ITS-2 region amplification. Agrobacterium-mediated transformation was successful for the isolates Chlorella sp., Ankistrodesmus sp and Scenedesmus bajacalifornicus. Gene integration and expression was confirmed by PCR amplification of hptII and GUS histochemical assay. A. tumifaciens contamination was checked by amplification of npt II gene (kanamycin resistant) which lies outside the T-border. Based on GUS assay, transformation efficiencies were found to be 12.25% for Chlorella sp. 2.96% for Scenedesmus bajacalifornicus and 3.5% for Ankistrodesmus sp.

  2. Successful aging.

    Science.gov (United States)

    Vaillant, G E; Mukamal, K

    2001-06-01

    Until now, prospective studies of aging have begun with 50-60-year-olds, not adolescents. Premature death, childhood variables, and alcohol abuse have been often ignored, as has successful aging. The authors reviewed the existing literature on health in late life in order to highlight that, increasingly, successful aging is not an oxymoron. The present study followed two cohorts of adolescent boys (237 college students and 332 core-city youth) for 60 years or until death. Complete physical examinations were obtained every 5 years and psychosocial data every 2 years. Predictor variables assessed before age 50 included six variables reflecting uncontrollable factors: parental social class, family cohesion, major depression, ancestral longevity, childhood temperament, and physical health at age 50 and seven variables reflecting (at least some) personal control: alcohol abuse, smoking, marital stability, exercise, body mass index, coping mechanisms, and education. The six outcome variables chosen to assess successful aging at age 70-80 included four objectively assessed variables (physical health, death and disability before age 80, social supports, and mental health) and two self-rated variables (instrumental activities of daily living and life enjoyment). Multivariate analysis suggested that "good" and "bad" aging from age 70-80 could be predicted by variables assessed before age 50. More hopeful still, if the seven variables under some personal control were controlled, depression was the only uncontrollable predictor variable that affected the quality of subjective and objective aging. One may have greater personal control over one's biopsychosocial health after retirement than previously recognized.

  3. Characterization and radionuclides sorption of suspended particulate matters in freshwater according to their settling kinetics

    International Nuclear Information System (INIS)

    Brach-Papa, C.; Boyer, P.; Amielh, M.; Anselmet, F.

    2004-01-01

    In freshwater, the transfers of radionuclides depend both on exchanges between liquid and solid phases and on mass transfers between suspended matter and bottom sediment. Whereas the former ones depend on chemical processes (such as sorption/desorption, complexation, the latter ones are regulated by hydrological and sedimentary considerations (dispersion, erosion, deposit closely related to the interactions between flow, suspended matter and bed sediment. Some of our previous studies highlight the need to consider the matter heterogeneity and its specific sediment dynamics to correctly report the inhomogeneity of fluxes in time and in space. These considerations lead us to develop experimental methods to distinguish the different matter classes, present in natural water, mainly according to their erosion threshold and settling kinetics. In this context, this paper presents the experimental protocol TALISMEN to characterize a natural bulk suspension according the identification of its main settling kinetics groups. In a first step, this identification is achieved by the use of a settling tank, that allows the monitoring of the suspended solid concentration at various depths, combined to a vertical mono-dimensional settling model applying a multi-class approach. In a second step, the particle groups are isolated and their physico-chemical properties are determined ( i.e mineral composition, specific surface area, particulate organic carbon, in order to fully characterized them. In a last one, the sorption property of each group toward radionuclides is determined by the measurements of its distribution coefficients (Kd). The results confirm the interest to consider these heterogeneities for the modelling of the radionuclides transfer in freshwater. From one group to other, these heterogeneities appear at two levels: 1) their sediment dynamics and 2) their radionuclides sorption properties. These conclusions can be equally applying to others xenobiotics as heavy metals

  4. Freshwater flux to Sermilik Fjord, SE Greenland

    Directory of Open Access Journals (Sweden)

    S. H. Mernild

    2010-10-01

    Full Text Available Terrestrial inputs of freshwater flux to Sermilik Fjord, SE Greenland, were estimated, indicating ice discharge to be the dominant source of freshwater. A freshwater flux of 40.4 ± 4.9×109 m3 y−1 was found (1999–2008, with an 85% contribution originated from ice discharge (65% alone from Helheim Glacier, 11% from terrestrial surface runoff (from melt water and rain, 3% from precipitation at the fjord surface area, and 1% from subglacial geothermal and frictional melting due to basal ice motion. The results demonstrate the dominance of ice discharge as a primary mechanism for delivering freshwater to Sermilik Fjord. Time series of ice discharge for Helheim Glacier, Midgård Glacier, and Fenris Glacier were calculated from satellite-derived average surface velocity, glacier width, and estimated ice thickness, and fluctuations in terrestrial surface freshwater runoff were simulated based on observed meteorological data. These simulations were compared and bias corrected against independent glacier catchment runoff observations. Modeled runoff to Sermilik Fjord was variable, ranging from 2.9 ± 0.4×109 m3 y−1 in 1999 to 5.9 ± 0.9×109 m3 y−1 in 2005. The sub-catchment runoff of the Helheim Glacier region accounted for 25% of the total runoff to Sermilik Fjord. The runoff distribution from the different sub-catchments suggested a strong influence from the spatial variation in glacier coverage, indicating high runoff volumes, where glacier cover was present at low elevations.

  5. Phylogenetic Diversity of T4-Type Phages in Sediments from the Subtropical Pearl River Estuary.

    Science.gov (United States)

    He, Maoqiu; Cai, Lanlan; Zhang, Chuanlun; Jiao, Nianzhi; Zhang, Rui

    2017-01-01

    Viruses are an abundant and active component of marine sediments and play a significant role in microbial ecology and biogeochemical cycling at local and global scales. To obtain a better understanding of the ecological characteristics of the viriobenthos, the abundance and morphology of viruses and the diversity and community structure of T4-type phages were systematically investigated in the surface sediments of the subtropical Pearl River Estuary (PRE). Viral abundances ranged from 4.49 × 10 8 to 11.7 × 10 8 viruses/g and prokaryotic abundances ranged from 2.63 × 10 8 to 9.55 × 10 8 cells/g, and both decreased from freshwater to saltwater. Diverse viral morphotypes, including tailed, spherical, filamentous, and rod-shaped viruses, were observed using transmission electron microscopy. Analysis of the major capsid gene ( g23 ) indicated that the sediment T4-type phages were highly diverse and, similar to the trend in viral abundances, their diversity decreased as the salinity increased. Phylogenetic analysis suggested that most of the g23 operational taxonomic units were affiliated with marine, paddy soil, and lake groups. The T4-type phage communities in freshwater and saltwater sediments showed obvious differences, which were related to changes in the Pearl River discharge. The results of this study demonstrated both allochthonous and autochthonous sources of the viral community in the PRE sediments and the movement of certain T4-type viral groups between the freshwater and saline water biomes.

  6. Phylogenetic Diversity of T4-Type Phages in Sediments from the Subtropical Pearl River Estuary

    Directory of Open Access Journals (Sweden)

    Maoqiu He

    2017-05-01

    Full Text Available Viruses are an abundant and active component of marine sediments and play a significant role in microbial ecology and biogeochemical cycling at local and global scales. To obtain a better understanding of the ecological characteristics of the viriobenthos, the abundance and morphology of viruses and the diversity and community structure of T4-type phages were systematically investigated in the surface sediments of the subtropical Pearl River Estuary (PRE. Viral abundances ranged from 4.49 × 108 to 11.7 × 108 viruses/g and prokaryotic abundances ranged from 2.63 × 108 to 9.55 × 108 cells/g, and both decreased from freshwater to saltwater. Diverse viral morphotypes, including tailed, spherical, filamentous, and rod-shaped viruses, were observed using transmission electron microscopy. Analysis of the major capsid gene (g23 indicated that the sediment T4-type phages were highly diverse and, similar to the trend in viral abundances, their diversity decreased as the salinity increased. Phylogenetic analysis suggested that most of the g23 operational taxonomic units were affiliated with marine, paddy soil, and lake groups. The T4-type phage communities in freshwater and saltwater sediments showed obvious differences, which were related to changes in the Pearl River discharge. The results of this study demonstrated both allochthonous and autochthonous sources of the viral community in the PRE sediments and the movement of certain T4-type viral groups between the freshwater and saline water biomes.

  7. People, pollution and pathogens - Global change impacts in mountain freshwater ecosystems.

    Science.gov (United States)

    Schmeller, Dirk S; Loyau, Adeline; Bao, Kunshan; Brack, Werner; Chatzinotas, Antonis; De Vleeschouwer, Francois; Friesen, Jan; Gandois, Laure; Hansson, Sophia V; Haver, Marilen; Le Roux, Gaël; Shen, Ji; Teisserenc, Roman; Vredenburg, Vance T

    2018-05-01

    Mountain catchments provide for the livelihood of more than half of humankind, and have become a key destination for tourist and recreation activities globally. Mountain ecosystems are generally considered to be less complex and less species diverse due to the harsh environmental conditions. As such, they are also more sensitive to the various impacts of the Anthropocene. For this reason, mountain regions may serve as sentinels of change and provide ideal ecosystems for studying climate and global change impacts on biodiversity. We here review different facets of anthropogenic impacts on mountain freshwater ecosystems. We put particular focus on micropollutants and their distribution and redistribution due to hydrological extremes, their direct influence on water quality and their indirect influence on ecosystem health via changes of freshwater species and their interactions. We show that those changes may drive pathogen establishment in new environments with harmful consequences for freshwater species, but also for the human population. Based on the reviewed literature, we recommend reconstructing the recent past of anthropogenic impact through sediment analyses, to focus efforts on small, but highly productive waterbodies, and to collect data on the occurrence and variability of microorganisms, biofilms, plankton species and key species, such as amphibians due to their bioindicator value for ecosystem health and water quality. The newly gained knowledge can then be used to develop a comprehensive framework of indicators to robustly inform policy and decision making on current and future risks for ecosystem health and human well-being. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Conservation of the endangered freshwater mussel Solenaia carinata (Bivalvia, Unionidae in China

    Directory of Open Access Journals (Sweden)

    Yan-Ling Cao

    2018-04-01

    Full Text Available Despite the diversity and economic and ecological value of freshwater mussels, relatively little is known about their biology (especially for species outside of Europe and North America. Solenaia carinata is an endangered freshwater mussel, is endemic to China and is now only distributed in Poyang Lake basin. However, its conservation status is not clear. Thus, for this study, surveys were conducted at 41 sites along the lower reaches of the Ganjiang River to study the conservation status of S. carinatus. The results showed that S. carinata had a restricted distribution and extremely low density. In addition, the habitat sediments where S. carinata was located were mainly composed of silt (particle size <0.0625 mm. RDA analysis showed that the density of S. carinata was correlated to dissolved oxygen, temperature, turbidity and chlorophyll-a. Microsatellite analysis showed that S. carinata had a low genetic diversity (mean HO: 0.419; mean HE: 0.484; mean PIC: 0.430. At the same time, we firstly report the glochidia of S. carinata and describe its morphological characteristic. Surprisingly, its reproduction period and morphological characteristics were different from that of others freshwater mussels. Therefore, this study clarified the resource conditions, endangered status and threat factors for S. carinata and it provided a theoretical basis for the conservation and management of its resources.

  9. Sampling method, storage and pretreatment of sediment affect AVS concentrations with consequences for bioassay responses

    Energy Technology Data Exchange (ETDEWEB)

    Lange, H.J. de [Aquatic Ecology and Water Quality Management Group, Wageningen University, Wageningen University and Research Centre, P.O. Box 8080, 6700 DD, Wageningen (Netherlands); Centre for Ecosystem Studies, Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA, Wageningen (Netherlands)], E-mail: marieke.delange@wur.nl; Griethuysen, C. van; Koelmans, A.A. [Aquatic Ecology and Water Quality Management Group, Wageningen University, Wageningen University and Research Centre, P.O. Box 8080, 6700 DD, Wageningen (Netherlands)

    2008-01-15

    Sediment treatment and sediment storage may alter sediment toxicity, and consequently biotic response. Purpose of our study was to combine these three aspects (treatment-toxicity-biotic response) in one integrated approach. We used Acid Volatile Sulfide (AVS) concentrations as a proxy of the disturbance of the sediment. AVS and Simultaneously Extracted Metal (SEM) concentrations were compared to bioassay responses with the freshwater benthic macroinvertebrate Asellus aquaticus. Storage conditions and sediment treatment affected AVS but not SEM levels. AVS can be used as a proxy for sediment disturbance. The best way to pretreat the sediment for use in a bioassay in order to maintain initial AVS conditions was to sample the sediment with an Ekman grab, immediately store it in a jar without headspace, and freeze it as soon as possible. In a survey using seven different sediments, bioassay responses of A. aquaticus were correlated with SEM and AVS characteristics. - Change in AVS is a good proxy for sediment disturbance and combined with SEM it can be used as a suitable predictor for biotic effects of sediment contamination.

  10. Indicators: Sediment Enzymes

    Science.gov (United States)

    Sediment enzymes are proteins that are produced by microorganisms living in the sediment or soil. They are indicators of key ecosystem processes and can help determine which nutrients are affecting the biological community of a waterbody.

  11. Center for Contaminated Sediments

    Data.gov (United States)

    Federal Laboratory Consortium — The U.S. Army Corps of Engineers Center for Contaminated Sediments serves as a clearinghouse for technology and expertise concerned with contaminated sediments. The...

  12. Freshwater treatment of amoebic gill disease and sea-lice in seawater salmon production: considerations of water chemistry and fish welfare

    OpenAIRE

    Powell, Mark Darryn; Kristensen, Torstein

    2014-01-01

    Amoebic gill disease (AGD) and sea lice are two of the most significant disease issues facing the Norwegian Atlantic salmon aquaculture industry. Although both diseases respond to various extents, to freshwater treatment, the chemistry, interactions and efficacy of treatment can be variable. These variations can have significant impacts upon the success and failure of treatment and costs to the production cycle. Although it is known that soft freshwater is most effective in bathing of Atlan...

  13. Technical Note: Comparison between a direct and the standard, indirect method for dissolved organic nitrogen determination in freshwater environments with high dissolved inorganic nitrogen concentrations

    DEFF Research Database (Denmark)

    Graeber, Daniel; Gelbrecht, Jörg; Kronvang, Brian

    2012-01-01

    was successfully applied to a range of samples from waste water treatment plants to forest and agricultural streams. With 2.5 h of measurement time per sample, SEC is slower, but more accurate than the standard approach for determination of DON concentrations in freshwaters with DIN : TDN ratios >0.6. To sum up......, the direct DON measurement by SEC enables better understanding of the nitrogen cycle of urban and agricultural freshwater systems....

  14. Strontium and barium incorporation into freshwater bivalve shells

    Science.gov (United States)

    Zhao, Liqiang; Schöne, Bernd R.

    2015-04-01

    Despite strong vital control, trace elements of bivalve shells can potentially serve as proxies of environmental change. However, to reconstruct past environments with the geochemical properties of the shells and determine the degree to which the element levels are biologically influenced, it is essential to experimentally determine the relationship between environmental variables and the element composition of the shells. In particular, the trace element geochemistry of freshwater bivalve shells has so far received little attention. Here, we present a controlled laboratory experiment that aimed at providing a better understanding of the influence of changing environmental variables on the incorporation of trace elements into freshwater bivalve shells. Under controlled conditions, Asian clams Corbicula fluminea were reared for 5 weeks in three sets of experiments: (1) different water temperature (10, 16, and 22° C) and different food levels (an equally mixed Scenedesmu quadricanda and Chlorella vulgaris at rations of 0.4, 2, 4, and 8 × 104 cells ml-1 d-1); (2) different water temperature (10, 16, and 22° C) and different element levels (Sr, Ba); (3) five sediment types (sand, slightly muddy sand, muddy sand, slightly sandy mud and mud). In the first set of experiments, shell Sr/Ca showed a significantly negative correlation with temperature, where Sr/Ca decreased linearly by about 1.6 to 2.1% per 1° C, but responded far more weakly to food availability. On the other hand, temperature and food availability affected shell Ba/Ca ratios, which potentially confounds the interpretation of Ba/Ca variations. Moreover, shell Sr/Ca and Ba/Ca exhibited a clearly negative dependence on shells growth rate that varied significantly among combinations of temperature and food availability. In the second set of experiments, shell Sr/Ca and Ba/Ca were positively and linearly related to water Sr/Ca and Ba/Ca for all temperatures. However, significantly negative effects of

  15. Inbreeding depression of mating behavior and its reproductive consequences in a freshwater snail

    OpenAIRE

    Janicke Tim; Vellnow Nikolas; Lamy Thomas; Chapuis Elodie; David Patrice

    2014-01-01

    Inbreeding is expected to impair male and female reproductive performance, but little is known on how inbreeding depression varies between sexes and different levels of competition. We studied inbreeding depression in mating behavior and its reproductive consequences in a hermaphroditic freshwater snail and demonstrate that inbreeding depresses mating success in both sex functions. However, the magnitude of inbreeding depression does not differ between sex functions and is not affected by the...

  16. Making fate and exposure models for freshwater ecotoxicity in life cycle assessment suitable for organic acids and bases.

    Science.gov (United States)

    van Zelm, Rosalie; Stam, Gea; Huijbregts, Mark A J; van de Meent, Dik

    2013-01-01

    Freshwater fate and exposure factors were determined for organic acids and bases, making use of the knowledge on electrical interaction of ionizing chemicals and their sorption to particles. The fate factor represents the residence time in the environment whereas exposure factors equal the dissolved fraction of a chemical. Multimedia fate, exposure, and effect model USES-LCA was updated to take into account the influence of ionization, based upon the acid dissociation constant (pK(a)) of a chemical, and the environmental pH. Freshwater fate (FF) and exposure (XF) factors were determined for 415 acids and 496 bases emitted to freshwater, air, and soil. The relevance of taking account of the degree of ionization of chemicals was tested by determining the ratio (R) of the new vs. fate and exposure factors determined with USES-LCA suitable for neutral chemicals only. Our results show that the majority of freshwater fate and exposure factors of chemicals that are largely ionized in the environment are larger with the ionics model compared to the factors determined with the neutrals model version. R(FF) ranged from 2.4×10(-1) to 1.6×10(1) for freshwater emissions, from 1.2×10(-2) to 2.0×10(4) for soil emissions and from 5.8×10(-2) to 6.0×10(3) for air emissions, and R(XF) from 5.3×10(-1) to 2.2×10(1). Prediction of changed solid-water partitioning, implying a change in runoff and in removal via sedimentation, and prediction of negligible air-water partition coefficient, leading to negligible volatilization were the main contributors to the changes in freshwater fate factors. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Conceptual Site Model for Newark Bay—Hydrodynamics and Sediment Transport

    Directory of Open Access Journals (Sweden)

    Parmeshwar L. Shrestha

    2014-02-01

    Full Text Available A conceptual site model (CSM has been developed for the Newark Bay Study Area (NBSA as part of the Remedial Investigation/Feasibility Study (RI/FS for this New Jersey site. The CSM is an evolving document that describes the influence of physical, chemical and biological processes on contaminant fate and transport. The CSM is initiated at the start of a project, updated during site activities, and used to inform sampling and remediation planning. This paper describes the hydrodynamic and sediment transport components of the CSM for the NBSA. Hydrodynamic processes are influenced by freshwater inflows, astronomical forcing through two tidal straits, meteorological conditions, and anthropogenic activities such as navigational dredging. Sediment dynamics are driven by hydrodynamics, waves, sediment loading from freshwater sources and the tidal straits, sediment size gradation, sediment bed properties, and particle-to-particle interactions. Cohesive sediment transport is governed by advection, dispersion, aggregation, settling, consolidation, and erosion. Noncohesive sediment transport is governed by advection, dispersion, settling, armoring, and transport in suspension and along the bed. The CSM will inform the development and application of a numerical model that accounts for all key variables to adequately describe the NBSA’s historical, current, and future physical conditions.

  18. Spatial hydrological flow processes, water quality, sediment and vegetation community distributions in a natural floodplain fen - implication for the Flood Pulse Concept

    Science.gov (United States)

    Keizer, Floris; Schot, Paul; Wassen, Martin; Kardel, Ignacy; Okruszko, Tomasz

    2017-04-01

    We studied spatial patterns in inundation water quality, sediment and vegetation distribution in a floodplain fen in Poland to map interacting peatland hydrological processes. Using PCA and K-means cluster analysis, we identified four water types, related to river water inundation, discharge of clean and polluted groundwater, and precipitation and snowmelt dilution. Spatially, these hydrochemical water types are related to known water sources in the floodplain and occupy distinctive zones. River water is found along the river, clean and polluted groundwater at the valley margins and groundwater diluted with precipitation and snowmelt water in the central part of the floodplain. This implies that, despite the floodplain being completely inundated, nutrient input from river flooding occurs only in a relatively narrow zone next to the river. Our findings question the relevance of the edge of inundation, as presented in the Flood Pulse Concept, as delineating the zone of input and turnover of nutrients. Secondly, we studied rich-fen and freshwater vegetation community distributions in relation to the presented inundation water quality types. We successfully determined inundation water quality preference for 14 out of 17 studied rich-fen and freshwater communities in the floodplain. Spatial patterns in preference show vegetation with attributed river water preference to occur close to the river channel, with increasing distance to the river followed by communities with no preference, diluted groundwater preference in the central part, and clean and polluted groundwater preference at the valley margins. In inundation water, nutrients are known to be transported mainly as attached to sediment, besides in dissolved state. This means that in the zone where sediment deposition occurs, nutrient input can be a relevant contribution to the nutrient input of the floodplain. We found a significant decrease in sediment-attached nutrient deposition with distance from the river

  19. Effects of sediment quality on macroinvertebrates in the Sunraysia region of the Murray-Darling Rivers, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Sharley, David J. [Centre for Environmental Stress and Adaptation Research-Hoffmann Laboratory, Zoology Department, University of Melbourne, Level 2, Bio 21 Institute, 30 Flemington Road, Parkville, Victoria 3010 (Australia)], E-mail: sharleyd@unimelb.edu.au; Hoffmann, Ary A. [Centre for Environmental Stress and Adaptation Research-Hoffmann Laboratory, Zoology Department, University of Melbourne, Level 2, Bio 21 Institute, 30 Flemington Road, Parkville, Victoria 3010 (Australia); Pettigrove, Vincent [Research and Technology, Melbourne Water, PO Box 4342, Melbourne, Victoria 3001 (Australia)

    2008-12-15

    A field-based microcosm approach was tested to identify deterioration of sediment quality in waterways using freshwater macroinvertebrates. The method can potentially identify the nature of contaminants based on species-specific responses. Sediments were collected from the Murray and Darling Rivers and irrigation drains within the Sunraysia region of south-eastern Australia and compared to non-polluted reference sediment. Clean sediments were also spiked with fertiliser to test whether nutrients affected the aquatic fauna. Seven of the eight sediments from the Sunraysia region had a negative impact on the macroinvertebrates, in particular sediment from the Darling River, which supported an impoverished fauna. Three species of chironomid showed varied responses to sediment quality and, although it was hypothesised that nutrients may have impacted on the macroinvertebrate fauna, the results suggest that other pollutants are also involved. The field-based microcosm method proved effective for determining the impact of sediment quality on indigenous macroinvertebrates. - Sediment quality effects on freshwater macroinvertebrates are isolated.

  20. Effects of sediment quality on macroinvertebrates in the Sunraysia region of the Murray-Darling Rivers, Australia

    International Nuclear Information System (INIS)

    Sharley, David J.; Hoffmann, Ary A.; Pettigrove, Vincent

    2008-01-01

    A field-based microcosm approach was tested to identify deterioration of sediment quality in waterways using freshwater macroinvertebrates. The method can potentially identify the nature of contaminants based on species-specific responses. Sediments were collected from the Murray and Darling Rivers and irrigation drains within the Sunraysia region of south-eastern Australia and compared to non-polluted reference sediment. Clean sediments were also spiked with fertiliser to test whether nutrients affected the aquatic fauna. Seven of the eight sediments from the Sunraysia region had a negative impact on the macroinvertebrates, in particular sediment from the Darling River, which supported an impoverished fauna. Three species of chironomid showed varied responses to sediment quality and, although it was hypothesised that nutrients may have impacted on the macroinvertebrate fauna, the results suggest that other pollutants are also involved. The field-based microcosm method proved effective for determining the impact of sediment quality on indigenous macroinvertebrates. - Sediment quality effects on freshwater macroinvertebrates are isolated

  1. Interactive effects of climate change with nutrients, mercury, and freshwater acidification on key taxa in the North Atlantic Landscape Conservation Cooperative region

    Science.gov (United States)

    Pinkney, Alfred E.; Driscoll, Charles T.; Evers, David C.; Hooper, Michael J.; Horan, Jeffrey; Jones, Jess W.; Lazarus, Rebecca S.; Marshall, Harold G.; Milliken, Andrew; Rattner, Barnett A.; Schmerfeld, John J.; Sparling, Donald W.

    2015-01-01

    The North Atlantic Landscape Conservation Cooperative LCC (NA LCC) is a public–private partnership that provides information to support conservation decisions that may be affected by global climate change (GCC) and other threats. The NA LCC region extends from southeast Virginia to the Canadian Maritime Provinces. Within this region, the US National Climate Assessment documented increases in air temperature, total precipitation, frequency of heavy precipitation events, and rising sea level, and predicted more drastic changes. Here, we synthesize literature on the effects of GCC interacting with selected contaminant, nutrient, and environmental processes to adversely affect natural resources within this region. Using a case study approach, we focused on 3 stressors with sufficient NA LCC region-specific information for an informed discussion. We describe GCC interactions with a contaminant (Hg) and 2 complex environmental phenomena—freshwater acidification and eutrophication. We also prepared taxa case studies on GCC- and GCC-contaminant/nutrient/process effects on amphibians and freshwater mussels. Several avian species of high conservation concern have blood Hg concentrations that have been associated with reduced nesting success. Freshwater acidification has adversely affected terrestrial and aquatic ecosystems in the Adirondacks and other areas of the region that are slowly recovering due to decreased emissions of N and sulfur oxides. Eutrophication in many estuaries within the region is projected to increase from greater storm runoff and less denitrification in riparian wetlands. Estuarine hypoxia may be exacerbated by increased stratification. Elevated water temperature favors algal species that produce harmful algal blooms (HABs). In several of the region's estuaries, HABs have been associated with bird die-offs. In the NA LCC region, amphibian populations appear to be declining. Some species may be adversely affected by GCC through higher temperatures

  2. A freshwater species wintering in a brackish environment: Habitat selection and diet of Slavonian grebes in the southern Baltic Sea

    Science.gov (United States)

    Sonntag, Nicole; Garthe, Stefan; Adler, Sven

    2009-09-01

    After the breeding season, Slavonian grebes ( Podiceps auritus) leave their freshwater breeding habitats and migrate to wintering grounds in marine or brackish waters. The most important wintering area in northwestern Europe is located in the southern Baltic Sea, with the largest concentrations in the offshore area of the Pommeranian Bight. Analysis of ship-based surveys revealed that the habitat selection of Slavonian grebes in this brackish area is significantly influenced by water depth and bottom sediment type. The grebes prefer shallow waters of 4-14 m depth and occur only over sandy sediments. While the diving depths of endothermic animals is limited due to energetic constraints and thermoregulation, sediment type is regarded to be a proxy for food choice. The diet of Slavonian grebes in the Pomeranian Bight consists mainly of demersal gobies (Gobiidae) that frequently occur over sandy bottom substrates.

  3. Diversity and composition of sulfate- and sulfite-reducing prokaryotes as affected by marine-freshwater gradient and sulfate availability.

    Science.gov (United States)

    Fan, Lan-Feng; Tang, Sen-Lin; Chen, Chang-Po; Hsieh, Hwey-Lian

    2012-01-01

    Sulfate- and sulfite-reducing prokaryotes (SSRP) communities play a key role in both sulfur and carbon cycles. In estuarine ecosystems, sulfate concentrations change with tides and could be limited in tidal freshwater reach or deep sediments. In a subtropical estuary of northern Taiwan in December 2007, we examined the compositional changes of SSRP communities. We examined three sites: from the lower estuarine brackish-water reach (site GR and mangrove vegetation site, GM) to the upper estuarine tidal freshwater reach (site HR), as well as from surface to a 50-cm depth. The partial sequence of sulfite reductase (dsrB) genes was used as a molecular marker of SSRP, linked to polymerase chain reaction and denaturing gradient gel electrophoresis (DGGE) techniques. SSRP communities of the DGGE profiles varied with sites according to one-way analyses of similarities (Global R = 0.69, P = 0.001). Using cluster analysis, the DGGE profile was found to show site-specific clusters and a distinct depth zonation (five, six, and two SSRP communities at the GM, GR, and HR sites, respectively). SSRP composition was highly correlated to the combination of salinity, reduced sulfur, and total organic carbon contents (BIO-ENV analysis, r ( s ) = 0.56). After analyzing a total of 35 dsrB sequences in the DGGE gel, six groups with 15 phylotypes were found, which were closely related to marine-freshwater gradient. Moreover, sequences neighboring sulfite-reducing prokaryotes were observed, in addition to those affiliated to sulfate-reducing prokaryotes. Four phylotypes harvested in HR resembled the genus Desulfitobacterium, a sulfite-reducing prokaryote, which failed to use sulfate as an electron acceptor and were active in freshwater and sulfate-limited habitat. The other five phylotypes in the HR reach belonged to the sulfate-reducing prokaryotes of the genera Desulfatiferula, Desulfosarcina, Desulfovibrio, and Desulfotomaculum, which appeared to tolerate low salinity and

  4. Comparison of bioaccumulation and biomarker responses in Dreissena polymorpha and D. bugensis after exposure to resuspended sediments.

    Science.gov (United States)

    Schäfer, S; Hamer, B; Treursić, B; Möhlenkamp, C; Spira, D; Korlević, M; Reifferscheid, G; Claus, E

    2012-05-01

    The zebra mussel Dreissena polymorpha is widely used as sentinel organism for the assessment of environmental contamination in freshwater environments. However, in the River Rhine (Germany), the D. polymorpha population is declining, whereas the closely related quagga mussel D. bugensis is found in high numbers at some sites. In the present laboratory study, D. polymorpha and D. bugensis were exposed to resuspended native sediments for ≤2 weeks. Wet sediments (quagga mussel can be used as alternative test organism for the zebra mussel.

  5. Geophysical characterization of contaminated muddy sediments

    International Nuclear Information System (INIS)

    McDermott, I. R.; English, G. E.

    1997-01-01

    A non-intrusive, seismic subbottom profile survey of pond sediments was conducted on a former U.S.Naval Facility at Argentia, Newfoundland, to characterize the nature and extent of contamination. An IKB Seistec boomer was used in conjunction with C-CORE's HI-DAPT digital data acquisition and processing system and differential GPS system. The survey was successful in locating regions of soft muddy sediments and in determining the thickness of these deposits. Subsurface buried objects, which are potential sources of pollution, were also identified. Intrusive profiling of the sediment was done with a new tool, the Soil Stiffness Probe, which combines two geophysical measurement systems to determine bulk density and shear stiffness. The muddy sediments were found to be highly 'fluidized', indicating that they could be easily removed with a suction dredge. 4 refs., 5 figs

  6. Luminescence properties of a nanoporous freshwater diatom.

    Science.gov (United States)

    Goswami, Bondita; Choudhury, Amarjyoti; Buragohain, Alak K

    2012-01-01

    Freshwater diatom frustules show special optical properties. In this paper we observed luminescence properties of the freshwater diatom Cyclotella meneghiniana. To confirm the morphological properties we present scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies were carried out to visualize the structural properties of the frustules, confirming that silica present in diatom frustules crystallizes in an α-quartz structure. Study of the optical properties of the silica frustules of diatoms using ultra-violet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy confirmed that the diatom C. meneghiniana shows luminescence in the blue region of the electromagnetic spectrum when irradiated with UV light. This property of diatoms can be exploited to obtain many applications in day-to-day life. Also, using time-resolved photoluminescence spectroscopy (TRPL) it was confirmed that this species of diatom shows bi-exponential decay. Copyright © 2011 John Wiley & Sons, Ltd.

  7. Freshwater fishes of Tsitsikamma National Park

    Directory of Open Access Journals (Sweden)

    I.A. Russell

    2002-12-01

    Full Text Available This study aimed to determine the distribution and relative abundance of freshwater fishes in the Tsitsikamma National Park. Fish assemblages in six river systems were sampled in 2001, with a total of 323 fish from eight species recorded. Indigenous fish collected included four freshwater species (Pseudobarbus afer, Pseudobarbus tenuis, Sandelia capensis, Anguilla mossambica, three estuarine species (Monodactylus falciformis, Caffrogobius gilchristi, Myxus capensis, and one alien (Micropterus salmoides. One additional indigenous species (Galaxias zebratus and two aliens (Salmo trutta, Oncorhynchus mykiss could potentially occur within the park. The topography and locality of the park presents a unique opportunity to meaningfully conserve the endangered P. tenuis as well as other fish characteristic of the eastern reaches of the Cape Floristic Region. Management action is required to minimise opportunities for further establishment and spread of alien fish species and to conserve indigenous fish assemblages within the park.

  8. Assessing the freshwater distribution of yellow eel

    Directory of Open Access Journals (Sweden)

    Lasne É.

    2009-04-01

    Full Text Available In the global context of the decline in wild species, modeling the distribution of populations is a crucial aspect of ecological management. This can be a major challenge, especially for species, such as the European eel, that have complex life cycles, exhibit cryptic behavior, or migrate over long distances. A review of the literature suggests that eel size data could be used to assess and analyze freshwater distribution of eel. We argue that analyses based on small yellow eels (≤ 300 mm along the longitudinal course of rivers could provide a valuable tool for population monitoring. We propose a standardized catchment recruitment index and a colonization index based on the probability of occurrence (presence/absence data using logistic models for different size classes. The model developed here provides a convenient guide for assessing yellow eel stages in freshwater areas, and should have concrete applications for management of the species.

  9. Evidence of lacustrine sedimentation in the Upper Permian Bijori ...

    Indian Academy of Sciences (India)

    Development of the large Bijori lake body implies generation of accom- modation space exceeding the rate of sediment supplied and thus represents locus of high tectonic subsidence. Transition of fluvial sediments with red mudstone and calcareous soil profile in the lower part of the succession to carbonaceous shale and ...

  10. A simple control for sediment-toxicity exposures using the amphipod, Hyalella azteca

    Science.gov (United States)

    Lasier, Pete; Urich, Matthew L.

    2014-01-01

    Sediment-toxicity exposures comparing survival and growth of the freshwater amphipod, Hyalella azteca, are often components of aquatic-habitat assessments. Standardized exposure methods have been established and require evaluations for quality assurance. Test acceptability using performance-based criteria can be determined from exposures to control sediments, which are collected from the environment or formulated from commercially available components. Amending sand with leached alfalfa solids provided a simple formulated sediment that elicited consistently acceptable survival and growth in 28-day exposures with and without a daily feeding regime. A procedure is described for preparing the sediment along with results from comparisons among sand, amended sand, and field-collected sediments that incorporated three feeding regimes.

  11. Substantial export of suspended sediment to the global oceans from glacial erosion in Greenland

    Science.gov (United States)

    Overeem, I.; Hudson, B. D.; Syvitski, J. P. M.; Mikkelsen, A. B.; Hasholt, B.; van den Broeke, M. R.; Noël, B. P. Y.; Morlighem, M.

    2017-11-01

    Limited measurements along Greenland's remote coastline hamper quantification of the sediment and associated nutrients draining the Greenland ice sheet, despite the potential influence of river-transported suspended sediment on phytoplankton blooms and carbon sequestration. Here we calibrate satellite imagery to estimate suspended sediment concentration for 160 proglacial rivers across Greenland. Combining these suspended sediment reconstructions with numerical calculations of meltwater runoff, we quantify the amount and spatial pattern of sediment export from the ice sheet. We find that, although runoff from Greenland represents only 1.1% of the Earth's freshwater flux, the Greenland ice sheet produces approximately 8% of the modern fluvial export of suspended sediment to the global ocean. Sediment loads are highly variable between rivers, consistent with observed differences in ice dynamics and thus with control by glacial erosion. Rivers that originate from deeply incised, fast-moving glacial tongues form distinct sediment-export hotspots: just 15% of Greenland's rivers transport 80% of the total sediment load of the ice sheet. We conclude that future acceleration of melt and ice sheet flow may increase sediment delivery from Greenland to its fjords and the nearby ocean.

  12. Urban growth, climate change, and freshwater availability.

    Science.gov (United States)

    McDonald, Robert I; Green, Pamela; Balk, Deborah; Fekete, Balazs M; Revenga, Carmen; Todd, Megan; Montgomery, Mark

    2011-04-12

    Nearly 3 billion additional urban dwellers are forecasted by 2050, an unprecedented wave of urban growth. While cities struggle to provide water to these new residents, they will also face equally unprecedented hydrologic changes due to global climate change. Here we use a detailed hydrologic model, demographic projections, and climate change scenarios to estimate per-capita water availability for major cities in the developing world, where urban growth is the fastest. We estimate the amount of water physically available near cities and do not account for problems with adequate water delivery or quality. Modeled results show that currently 150 million people live in cities with perennial water shortage, defined as having less than 100 L per person per day of sustainable surface and groundwater flow within their urban extent. By 2050, demographic growth will increase this figure to almost 1 billion people. Climate change will cause water shortage for an additional 100 million urbanites. Freshwater ecosystems in river basins with large populations of urbanites with insufficient water will likely experience flows insufficient to maintain ecological process. Freshwater fish populations will likely be impacted, an issue of special importance in regions such as India's Western Ghats, where there is both rapid urbanization and high levels of fish endemism. Cities in certain regions will struggle to find enough water for the needs of their residents and will need significant investment if they are to secure adequate water supplies and safeguard functioning freshwater ecosystems for future generations.

  13. Why are freshwater fish so threatened?

    Science.gov (United States)

    Closs, Gerard P.; Angermeier, Paul; Darwall, William R.T.; Balcombe, Stephen R.

    2015-01-01

    The huge diversity of freshwater fishes is concentrated into an area of habitat that covers only about 1% of the Earth's surface, and much of this limited area has already been extensively impacted and intensively managed to meet human needs (Dudgeon et al., 2006). As outlined in Chapter 1, the number and proportions of threatened species tend to rise wherever fish diversity coincides with dense human populations, intensive resource use and development pressure. Of particular concern is the substantial proportion of the global diversity of freshwater fishes concentrated within the Mekong and Amazon Basins and west-central Africa (Berra, 2001; Abell et al., 2008; Dudgeon, 2011; Chapter 1) with extensive exploitation of water resources planned to accelerate in future years (Dudgeon, 2011; Chapter 1). If current trends continue, and the social, political and economic models that have been used to develop industrialised regions of the world over the past two centuries prevail, then the future of a significant proportion of global diversity of freshwater fish species is clearly uncertain.

  14. Distribution of genetic markers of fecal pollution on a freshwater sandy shoreline in proximity to wastewater effluent.

    Science.gov (United States)

    Eichmiller, Jessica J; Hicks, Randall E; Sadowsky, Michael J

    2013-04-02

    Water, sand, and sediment from a Lake Superior harbor site continuously receiving wastewater effluent was sampled monthly for June to October 2010 and from May to September 2011. Understanding the dynamics of genetic markers of fecal bacteria in these matrices is essential to accurately characterizing health risks. Genetic markers for enterococci, total Bacteroides, and human-associated Bacteroides were measured in site-water, sand, and sediment and in final effluent by quantitative PCR. The similarity between the quantity of molecular markers in the water column and effluent indicated that the abundance of genetic markers in the water column was likely controlled by effluent inputs. Effluent turbidity was positively correlated (p ≤ 0.05) with AllBac and HF183 in final effluent and AllBac in the water column. In sand and sediment, Entero1 and AllBac were most abundant in the upper 1-3 cm depths, whereas HF183 was most abundant in the upper 1 cm of sand and at 7 cm in sediment. The AllBac and Entero1 markers were 1- and 2-orders of magnitude more abundant in sand and sediment relative to the water column per unit mass. These results indicate that sand and sediment may act as reservoirs for genetic markers of fecal pollution at some freshwater sites.

  15. Managing Fine Sediment in Regulated Rivers

    Science.gov (United States)

    Schmidt, J. C.

    2015-12-01

    A paradigm useful in managing dams and diversions is that the combined effects of changing flow regime and sediment supply perturb regulated rivers into sediment deficit or sediment surplus. In the U.S. Southwest, large dams constructed on interregional rivers typically create sediment deficit segments >100 km long. Further downstream, sediment surplus may occur if desert tributaries deliver sufficient amounts of fine sediment, such as parts of the Rio Grande, lower Green River, and Colorado River delta. Sediment surplus also occurs on most smaller regional rivers. The protocols for managing rivers perturbed into sediment deficit have been refined for the Colorado River downstream from Glen Canyon Dam but are nonetheless challenged by externally determined water-supply agreements that require annual water deliveries that sometimes occur when there has been little tributary resupply. Virtually all of the naturally supplied sand to the depleted, 100-km long Marble Canyon comes from the Paria River. The sand delivery rate since 2012 was sufficiently large to trigger short-duration controlled floods under the High Flow Experiment (HFE) Protocol. The sand mass balance of Marble Canyon since 2012 when the HFE Protocol was adopted was positive due to the combination of relatively large sand delivery from the Paria River and average total annual flows. Large total annual flows have the potential to export large amounts of sand and create a negative sand mass balance. Despite the challenge of managing a scarce and highly variable sand supply and occasional years of large reservoir releases, the long-term (2006-2015) sand mass balance for the upstream half of Marble Canyon is indeterminant and is positive for the downstream half of Marble Canyon. The apparent success of managing sand in Grand Canyon under deficit conditions suggests that fine sediment management protocols might be developed for other regulated rivers. Implementation would require establishment of networks of

  16. Characterizing toxicity of metal-contaminated sediments from mining areas

    Science.gov (United States)

    Besser, John M.; Brumbaugh, William G.; Ingersoll, Christopher G.

    2015-01-01

    This paper reviews methods for testing the toxicity of metals associated with freshwater sediments, linking toxic effects with metal exposure and bioavailability, and developing sediment quality guidelines. The most broadly applicable approach for characterizing metal toxicity is whole-sediment toxicity testing, which attempts to simulate natural exposure conditions in the laboratory. Standard methods for whole-sediment testing can be adapted to test a wide variety of taxa. Chronic sediment tests that characterize effects on multiple endpoints (e.g., survival, growth, and reproduction) can be highly sensitive indicators of adverse effects on resident invertebrate taxa. Methods for testing of aqueous phases (pore water, overlying water, or elutriates) are used less frequently. Analysis of sediment toxicity data focuses on statistical comparisons between responses in sediments from the study area and responses in one or more uncontaminated reference sediments. For large or complex study areas, a greater number of reference sediments is recommended to reliably define the normal range of responses in uncontaminated sediments – the ‘reference envelope’. Data on metal concentrations and effects on test organisms across a gradient of contamination may allow development of concentration-response models, which estimate metal concentrations associated with specified levels of toxic effects (e.g. 20% effect concentration or EC20). Comparisons of toxic effects in laboratory tests with measures of impacts on resident benthic invertebrate communities can help document causal relationships between metal contamination and biological effects. Total or total-recoverable metal concentrations in sediments are the most common measure of metal contamination in sediments, but metal concentrations in labile sediment fractions (e.g., determined as part of selective sediment extraction protocols) may better represent metal bioavailability. Metals released by the weak-acid extraction

  17. Transitions between marine and freshwater environments provide new clues about the origins of multicellular plants and algae.

    Science.gov (United States)

    Dittami, Simon M; Heesch, Svenja; Olsen, Jeanine L; Collén, Jonas

    2017-08-01

    Marine-freshwater and freshwater-marine transitions have been key events in the evolution of life, and most major groups of organisms have independently undergone such events at least once in their history. Here, we first compile an inventory of bidirectional freshwater and marine transitions in multicellular photosynthetic eukaryotes. While green and red algae have mastered multiple transitions in both directions, brown algae have colonized freshwater on a maximum of six known occasions, and angiosperms have made the transition to marine environments only two or three times. Next, we review the early evolutionary events leading to the colonization of current habitats. It is commonly assumed that the conquest of land proceeded in a sequence from marine to freshwater habitats. However, recent evidence suggests that early photosynthetic eukaryotes may have arisen in subaerial or freshwater environments and only later colonized marine environments as hypersaline oceans were diluted to the contemporary level. Although this hypothesis remains speculative, it is important to keep these alternative scenarios in mind when interpreting the current habitat distribution of plants and algae. Finally, we discuss the roles of structural and functional adaptations of the cell wall, reactive oxygen species scavengers, osmoregulation, and reproduction. These are central for acclimatization to freshwater or to marine environments. We observe that successful transitions appear to have occurred more frequently in morphologically simple forms and conclude that, in addition to physiological studies of euryhaline species, comparative studies of closely related species fully adapted to one or the other environment are necessary to better understand the adaptive processes. © 2017 Phycological Society of America.

  18. Eocene habitat shift from saline to freshwater promoted Tethyan amphipod diversification

    Science.gov (United States)

    Hou, Zhonge; Sket, Boris; Fišer, Cene; Li, Shuqiang

    2011-01-01

    Current theory predicts that a shift to a new habitat would increase the rate of diversification, while as lineages evolve into multiple species, intensified competition would decrease the rate of diversification. We used Holarctic amphipods of the genus Gammarus to test this hypothesis. We sequenced four genes (5,088 bp) for 289 samples representing 115 Gammarus species. A phylogenetic analysis showed that Gammarus originated from the Tethyan region with a saline ancestry in the Paleocene, and later colonized the freshwater habitat in the Middle Eocene. Ancestral range reconstruction and diversification mode analysis combined with paleogeological and paleoclimatic evidence suggested that the habitat shift from saline to freshwater led to an increased diversification rate. The saline lineage of Gammarus dispersed to both sides of the Atlantic at 55 million years ago (Ma), because of the few barriers between the Tethys and the Atlantic, and diversified throughout its evolutionary history with a constant diversification rate [0.04 species per million years (sp/My)]. The freshwater Gammarus, however, underwent a rapid diversification phase (0.11 sp/My) until the Middle Miocene, and lineages successively diversified across Eurasia via vicariance process likely driven by changes of the Tethys and landmass. In particular, the freshwater Gammarus lacustris and Gammarus balcanicus lineages had a relatively high diversification shift, corresponding to the regression of the Paratethys Sea and the continentalization of Eurasian lands during the Miocene period. Subsequently (14 Ma), the diversification rate of the freshwater Gammarus decreased to 0.05 and again to 0.01 sp/My. The genus Gammarus provides an excellent aquatic case supporting the hypothesis that ecological opportunities promote diversification. PMID:21844362

  19. Design of a gravity corer for near shore sediment sampling

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.T.; Sonawane, A.V.; Nayak, B.U.

    For the purpose of geotechnical investigation a gravity corer has been designed and fabricated to obtain undisturbed sediment core samples from near shore waters. The corer was successfully operated at 75 stations up to water depth 30 m. Simplicity...

  20. The effect of human settlement on the abundance and community structure of ammonia oxidizers in tropical stream sediments

    NARCIS (Netherlands)

    Reis, Mariana De Paula; Ávila, Marcelo; Keijzer, Rosalinde Margriet; Barbosa, Francisco Antônio Rodrigues; Chartone-Souza, Edmar; Nascimento, Andréa; Laanbroek, (Riks) H.J.

    2015-01-01

    BACKGROUND: Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) are a diverse and functionally important group in the nitrogen cycle. Nevertheless, AOA and AOB communities driving this process remain uncharacterized in tropical freshwater sediment. Here, the effect of human

  1. Climate model performance and change projection for freshwater fluxes: Comparison for irrigated areas in Central and South Asia

    Directory of Open Access Journals (Sweden)

    Shilpa M. Asokan

    2016-03-01

    New hydrological insights for the region: For precipitation in both regions, model accuracy relative to observations has remained the same or decreased in successive climate model generations until and including CMIP5. No single climate model out-performs other models across all key freshwater variables in any of the investigated basins. Scale effects are not evident from global model application directly to freshwater assessment for the two basins of widely different size. Overall, model results are less accurate and more uncertain for freshwater fluxes than for temperature, and particularly so for model-implied water storage changes. Also, the monsoon-driven runoff seasonality in MRB is not accurately reproduced. Model projections agree on evapotranspiration increase in both regions until the climatic period 2070–2099. This increase is fed by precipitation increase in MRB and by runoff water (thereby decreasing runoff in the Aral Region.

  2. Successful Aging

    Directory of Open Access Journals (Sweden)

    Taufiqurrahman Nasihun

    2015-06-01

    Full Text Available The emerging concept of successful aging is based on evidence that in healthy individual when they get aged, there are  considerable variations in physiological functions alteration. Some people exhibiting greater, but others very few or no age related alteration. The first is called poor aging and the later is called successful pattern of aging (Lambert SW, 2008. Thus, in the simple words the successful aging concept is define as an opportunity of old people to stay  active and productive condition despite they get aged chronologically. Aging itself might be defined as the progressive accumulation of changes with time associated with or responsible for the ever-increasing susceptibility to disease and death which accompanies advancing age (Harman D, 1981. The time needed to accumulate changes is attributable to aging process. The marked emerging questions are how does aging happen and where does aging start? To answer these questions and because of the complexity of aging process, there are more than 300 aging theories have been proposed to explain how and where aging occured and started respectively. There are too many to enumerate theories and classification of aging process. In summary, all of these aging theories can be grouped into three clusters: 1. Genetics program theory, this theory suggests that aging is resulted from program directed by the genes; 2. Epigenetic theory, in these theory aging is resulted from environmental random events not determined by the genes; 3. Evolutionary theory, which propose that aging is a medium for disposal mortal soma in order to avoid competition between organism and their progeny for food and space, did not try to explain how aging occur, but possibly answer why aging occur (De la Fuente. 2009. Among the three groups of aging theories, the epigenetic theory is useful to explain and try to solve the enigma of aging which is prominently caused by internal and external environmental influences

  3. Use of wild trout for PBDE assessment in freshwater environments: Review and summary of critical factors

    Directory of Open Access Journals (Sweden)

    Juan M. Ríos

    2015-11-01

    Full Text Available Certain wild animals represent sentinels to address issues related to environmental pollution, since they can provide integrative data on both pollutant exposure and biological effects. Despite their technological benefits, PBDEs are considered a threat to environmental health due to their persistence, toxicity, and capacity to be accumulated. These pollutants have been found geographically widespread in fish, particularly in predator species such as trout. The aim of this work is to critically review the applicability and usefulness of wild trout for assessing PBDEs in freshwater environments. Reviewed reports include data from highly industrialized areas as well as areas from remote regions with relatively low human activity, including European and North American great lakes and freshwater environments in Europe, Greenland, subarctic areas and Patagonia, respectively. A summary of relevant factors were grouped into organism-specific factors (food habits, age, size, lipid content, sex and reproduction, tissue type, mechanism of contaminant uptake and metabolism, and PBDE levels in the surrounding environment (sediment. Five wild trout species [rainbow trout (Oncorhynchus mykiss, brown trout (Salmo trutta, lake trout (Salvelinus namaycush, arctic char (Salvelinus alpinus, and brook trout (Salvelinus fontinalis], collected worldwide within the 1994 to present time frame, were considered. Multivariate techniques (principal component analysis-PCA and mapping approach, showed clear differences in geographic distribution patterns of PBDE levels in trout depending on the region studied: wild trout from European and North American great lakes have the highest PBDE loads. This pattern could be due to high industrial activity at these locations. A correlational approach used to explore intraspecific relationships between PBDE levels and morphometry, showed positive relationships only for brown trout. Further, brown trout showed the highest trout-to-sediment

  4. Storm Event Suspended Sediment-Discharge Hysteresis and Controls in Agricultural Watersheds: Implications for Watershed Scale Sediment Management.

    Science.gov (United States)

    Sherriff, Sophie C; Rowan, John S; Fenton, Owen; Jordan, Philip; Melland, Alice R; Mellander, Per-Erik; hUallacháin, Daire Ó

    2016-02-16

    Within agricultural watersheds suspended sediment-discharge hysteresis during storm events is commonly used to indicate dominant sediment sources and pathways. However, availability of high-resolution data, qualitative metrics, longevity of records, and simultaneous multiwatershed analyses has limited the efficacy of hysteresis as a sediment management tool. This two year study utilizes a quantitative hysteresis index from high-resolution suspended sediment and discharge data to assess fluctuations in sediment source location, delivery mechanisms and export efficiency in three intensively farmed watersheds during events over time. Flow-weighted event sediment export was further considered using multivariate techniques to delineate rainfall, stream hydrology, and antecedent moisture controls on sediment origins. Watersheds with low permeability (moderately- or poorly drained soils) with good surface hydrological connectivity, therefore, had contrasting hysteresis due to source location (hillslope versus channel bank). The well-drained watershed with reduced connectivity exported less sediment but, when watershed connectivity was established, the largest event sediment load of all watersheds occurred. Event sediment export was elevated in arable watersheds when low groundcover was coupled with high connectivity, whereas in the grassland watershed, export was attributed to wetter weather only. Hysteresis analysis successfully indicated contrasting seasonality, connectivity and source availability and is a useful tool to identify watershed specific sediment management practices.

  5. Bacteria in ancient sediments

    International Nuclear Information System (INIS)

    Izzo, G.

    1986-01-01

    In order to ascertain the role of biological activity in ancient sediments, two microbiological studies were carried out. The first was on pleistocenic clay sediments on land, the second on deep oceanic sediments. In the present paper by direct counting the samples is demonstrated the presence of bacteria in a range of 10 5 to 10 7 . Further studies must be carried out to ascertain the activities by in situ incubation methods

  6. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments.DESCRIPTION: The multisensor core logger measures...

  7. Reconstruction of glacier variability from lake sediments reveals dynamic Holocene climate in Svalbard

    Science.gov (United States)

    van der Bilt, Willem G. M.; Bakke, Jostein; Vasskog, Kristian; D'Andrea, William J.; Bradley, Raymond S.; Ólafsdóttir, Sædis

    2015-10-01

    The Arctic is warming faster than anywhere else on Earth. Holocene proxy time-series are increasingly used to put this amplified response in perspective by understanding Arctic climate processes beyond the instrumental period. However, available datasets are scarce, unevenly distributed and often of coarse resolution. Glaciers are sensitive recorders of climate shifts and variations in rock-flour production transfer this signal to the lacustrine sediment archives of downstream lakes. Here, we present the first full Holocene record of continuous glacier variability on Svalbard from glacier-fed Lake Hajeren. This reconstruction is based on an undisturbed lake sediment core that covers the entire Holocene and resolves variability on centennial scales owing to 26 dating points. A toolbox of physical, geochemical (XRF) and magnetic proxies in combination with multivariate statistics has allowed us to fingerprint glacier activity in addition to other processes affecting the sediment record. Evidence from variations in sediment density, validated by changes in Ti concentrations, reveal glaciers remained present in the catchment following deglaciation prior to 11,300 cal BP, culminating in a Holocene maximum between 9.6 and 9.5 ka cal BP. Correspondence with freshwater pulses from Hudson Strait suggests that Early Holocene glacier advances were driven by the melting Laurentide Ice Sheet (LIS). We find that glaciers disappeared from the catchment between 7.4 and 6.7 ka cal BP, following a late Hypsithermal. Glacier reformation around 4250 cal BP marks the onset of the Neoglacial, supporting previous findings. Between 3380 and 3230 cal BP, we find evidence for a previously unreported centennial-scale glacier advance. Both events are concurrent with well-documented episodes of North Atlantic cooling. We argue that this brief forcing created suitable conditions for glaciers to reform in the catchment against a background of gradual orbital cooling. These findings highlight the

  8. Phytoplankton Assemblages in Selected Freshwaters of New Jersey

    Science.gov (United States)

    Caraballo, Y. A.; Wu, M. S.

    2017-12-01

    Characterizing phytoplankton assemblages in freshwaters is crucial for future management and monitoring of drinking and recreational freshwaters of New Jersey. New Jersey freshwater phytoplankton assemblages are poorly known and there is no list of freshwater phytoplankton taxa in New Jersey. This study seeks to describe phytoplankton assemblages of freshwaters in New Jersey. Results will help address public health, economic and environmental threats related to harmful algal blooms in New Jersey. A total of 49 freshwater sites, including ponds, rivers and reservoirs, were used for this study. Overall results showed 66 taxa of freshwater phytoplankton in 6 major groups and 29 different orders. Green algae had the highest number of taxa, followed by diatoms and blue-greens (cyanobacteria). The most common freshwater taxa in NJ are Synedra spp., Fragilaria spp., Selenastrum capricornutum, Scenedesmus spp., and Anabaena spp. Cyanobacteria species are present in more than half of the sites examined in this study. All ten cyanobacteria taxa present in New Jersey freshwaters are capable of producing the endotoxin lipopolysaccharides (LPS), eight can produce the hepatotoxins and six can produce neutoroxins. In addition, some taxa such as Anabaena spp. are capable of simultaneously producing endotoxins, hepatotoxins, neurotoxins and taste and odor compounds. The presence of taxa capable of producing multiple toxins infers the difficulty of management and treatment as well as increased public health effects.

  9. Sediment Characteristics of Tennessee Streams and Reservoirs

    National Research Council Canada - National Science Library

    Trimble, Stanley W; Carey, William P

    1984-01-01

    Suspended-sediment and reservoir sedimentation data have been analyzed to determine sediment yields and transport characteristics of Tennessee streams Data from 31 reservoirs plus suspended-sediment...

  10. Identifying fine sediment sources to alleviate flood risk caused by fine sediments through catchment connectivity analysis

    Science.gov (United States)

    Twohig, Sarah; Pattison, Ian; Sander, Graham

    2017-04-01

    Fine sediment poses a significant threat to UK river systems in terms of vegetation, aquatic habitats and morphology. Deposition of fine sediment onto the river bed reduces channel capacity resulting in decreased volume to contain high flow events. Once the in channel problem has been identified managers are under pressure to sustainably mitigate flood risk. With climate change and land use adaptations increasing future pressures on river catchments it is important to consider the connectivity of fine sediment throughout the river catchment and its influence on channel capacity, particularly in systems experiencing long term aggradation. Fine sediment erosion is a continuing concern in the River Eye, Leicestershire. The predominately rural catchment has a history of flooding within the town of Melton Mowbray. Fine sediment from agricultural fields has been identified as a major contributor of sediment delivery into the channel. Current mitigation measures are not sustainable or successful in preventing the continuum of sediment throughout the catchment. Identifying the potential sources and connections of fine sediment would provide insight into targeted catchment management. 'Sensitive Catchment Integrated Modelling Analysis Platforms' (SCIMAP) is a tool often used by UK catchment managers to identify potential sources and routes of sediment within a catchment. SCIMAP is a risk based model that combines hydrological (rainfall) and geomorphic controls (slope, land cover) to identify the risk of fine sediment being transported from source into the channel. A desktop version of SCIMAP was run for the River Eye at a catchment scale using 5m terrain, rainfall and land cover data. A series of SCIMAP model runs were conducted changing individual parameters to determine the sensitivity of the model. Climate Change prediction data for the catchment was used to identify potential areas of future connectivity and erosion risk for catchment managers. The results have been

  11. Sediment enzyme activities and microbial community diversity in an oligotrophic drinking water reservoir, eastern China.

    Directory of Open Access Journals (Sweden)

    Haihan Zhang

    Full Text Available Drinking water reservoir plays a vital role in the security of urban water supply, yet little is known about microbial community diversity harbored in the sediment of this oligotrophic freshwater environmental ecosystem. In the present study, integrating community level physiological profiles (CLPPs, nested polymerase chain reaction (PCR-denaturing gradient gel electrophoresis (DGGE and clone sequence technologies, we examined the sediment urease and protease activities, bacterial community functional diversity, genetic diversity of bacterial and fungal communities in sediments from six sampling sites of Zhou cun drinking water reservoir, eastern China. The results showed that sediment urease activity was markedly distinct along the sites, ranged from 2.48 to 11.81 mg NH₃-N/(g·24 h. The highest average well color development (AWCD was found in site C, indicating the highest metabolic activity of heterotrophic bacterial community. Principal component analysis (PCA revealed tremendous differences in the functional (metabolic diversity patterns of the sediment bacterial communities from different sites. Meanwhile, DGGE fingerprints also indicated spatial changes of genetic diversity of sediment bacterial and fungal communities. The sequence BLAST analysis of all the sediment samples found that Comamonas sp. was the dominant bacterial species harbored in site A. Alternaria alternate, Allomyces macrogynus and Rhizophydium sp. were most commonly detected fungal species in sediments of the Zhou cun drinking water reservoir. The results from this work provide new insights about the heterogeneity of sediment microbial community metabolic activity and genetic diversity in the oligotrophic drinking water reservoir.

  12. Cadmium Accumulation and Metallothionein Response in the Freshwater Bivalve Corbicula fluminea Under Hydrodynamic Conditions.

    Science.gov (United States)

    Geng, Nan; Wang, Chao; Wang, Peifang; Qi, Ning; Ren, Lingxiao

    2015-06-01

    Freshwater bivalves such as Corbicula fluminea (Müller) are useful biomonitors for cadmium pollution because they absorb heavy metals and accumulate them in their tissues. We exposed C. fluminea in the laboratory to natural and cadmium (Cd)-spiked sediments below flowing water in order to evaluate the organisms' Cd accumulation and metallothionein (MT) response under hydrodynamic conditions. The accumulation of Cd and the induction of MT in C. fluminea were determined at 0, 1, 3, 6, 10, 16, and 23 days. Hydrodynamic conditions, represented by a water flow rate of 14 or 3.2 cm/s, increased Cd accumulation in the visceral mass, gill, foot, and mantle of C. fluminea in the first 3 or 6 days in the natural sediment. Cd concentrations in the C. fluminea tissues kept increasing over time in the three treatments, and significant differences were observed in Cd accumulation after 6 (visceral mass), 10 (foot) and 16 (gill and mantle) days among the three groups. The MT concentrations were barely affected by hydrodynamic conditions and were significantly linearly related to the Cd concentration in the visceral mass in the natural sediment and binomially related to it in the Cd-spiked sediment. Hydrodynamic conditions enhanced the accumulation of Cd in the soft tissues of C. fluminea, especially in the Cd-spiked sediment, but stronger hydrodynamic forces did not increase Cd accumulation. MT may be considered an indicator for Cd accumulation in C. fluminea under hydrodynamic conditions, but only when the Cd concentrations in the tissue remain below the toxic threshold values.

  13. Actinorhodopsin genes discovered in diverse freshwater habitats and among cultivated freshwater .i.Actinobacteria./i

    Czech Academy of Sciences Publication Activity Database

    Sharma, A. K.; Sommerfeld, K.; Bullerjahn, G. S.; Matteson, A. R.; Wilhelm, S. W.; Jezbera, Jan; Brandt, U.; Doolittle, W.F.; Hahn, M.W.

    2009-01-01

    Roč. 3, č. 6 (2009), s. 726-737 ISSN 1751-7362 Institutional research plan: CEZ:AV0Z60170517 Keywords : rhodopsins * actinorhodopsin * freshwater * Actinobacteria * Superior * Erie Subject RIV: EE - Microbiology, Virology Impact factor: 6.397, year: 2009

  14. Freshwater reservoir effect variability in Northern Germany

    DEFF Research Database (Denmark)

    Philippsen, B.; Heinemeier, J.

    2013-01-01

    The freshwater reservoir effect is a potential problem when radiocarbon dating fish bones, shells, human bones, or food crusts on pottery from sites near rivers or lakes. The reservoir age in hardwater rivers can be up to several thousand years and may be highly variable. Accurate 14C dating of f...... that can also be expected for the past. This knowledge will be applied to the dating of food crusts on pottery from the Mesolithic sites Kayhude at the Alster River and Schlamersdorf at the Trave River, both in Schleswig-Holstein, northern Germany....

  15. MOLLUSKS IN RADIOECOLOGICAL STUDIES OF FRESHWATER ECOSYSTEMS

    Directory of Open Access Journals (Sweden)

    Д. Гудков

    2012-04-01

    Full Text Available Species-specificity and dynamics of 90Sr, 137Cs and some transuraniс elements accumulation in bivalveand gastropod freshwater molluscs of the Chernobyl exclusion zone during 1998–2010 was analyzed. Theresults of radiation dose as well as chromosome aberration rate estimation and analysis of hemolymphcomposition of molluscs was produced. The radiation absorbed dose rate was registered in the range of 0.3–85.0 μGy h–1. In closed water bodies the heightened chromosome aberration rate (up to 27 % in embryotissues, and also change of haematological indexes for the adult individuals of snails was registered

  16. Comparative food-chain behavior and distribution of actinide elements in and around a contaminated fresh-water pond

    Energy Technology Data Exchange (ETDEWEB)

    Garten, C.T. Jr.; Trabalka, J.R.; Bogle, M.A.

    1981-01-01

    The bioaccumulation of /sup 233/ /sup 234/U, /sup 238/U, /sup 238/Pu, /sup 239/ /sup 240/Pu, /sup 241/Am, and /sup 244/Cm in both native and introduced biota was studied at Pond 3513, a former low-level radioactive waste settling basin at Oak Ridge National Laboratory. This system, which was decommissioned in 1976 after more than 30 years use, contains approximately 5 Ci of /sup 239/ /sup 240/Pu; inventories of other actinide isotopes are considerably less. Significantly higher concentrations of actinides in fish that were allowed access to sediments indicated that sedimentary particulates may be the primary source of transuranics to biota in shallow fresh-water ecosystems. Our study determined habitat, in particular the degree of association of an organism with the sediment-water interface, to be the primary factor in controlling transuranic concentrations in aquatic biota. In most of the biological samples analyzed, excluding samples suspected of being contaminated by sediment, /sup 241/Am//sup 239/Pu, /sup 244/Cm//sup 239/Pu, and /sup 238/U//sup 239/Pu ratios were greater than the respective ratio in sediment while /sup 233/ /sup 234/U//sup 238/U, and /sup 239/ /sup 240/Pu//sup 238/Pu ratios were not different from the respective ratios in sediment. The relative uptake of actinides from contaminated sediment by aquatic and terrestrial biota at this site was U > Cm greater than or equal to Am > Pu. The relative extractability of actinides from shoreline sediment was U > Cm approx. = Am > Pu; we also observed the same relative ranking for sediment-water exchange in situ. Concentrations of transuranics in water, terrestrial vegetation, and vertebrate carcasses were less than 10% of the recommended public exposure maximum permissible concentration (MPC) of the ICRP.

  17. Comparative food-chain behavior and distribution of actinide elements in and around a contaminated fresh-water pond

    International Nuclear Information System (INIS)

    Garten, C.T. Jr.; Trabalka, J.R.; Bogle, M.A.

    1981-01-01

    The bioaccumulation of 233 234 U, 238 U, 238 Pu, 239 240 Pu, 241 Am, and 244 Cm in both native and introduced biota was studied at Pond 3513, a former low-level radioactive waste settling basin at Oak Ridge National Laboratory. This system, which was decommissioned in 1976 after more than 30 years use, contains approximately 5 Ci of 239 240 Pu; inventories of other actinide isotopes are considerably less. Significantly higher concentrations of actinides in fish that were allowed access to sediments indicated that sedimentary particulates may be the primary source of transuranics to biota in shallow fresh-water ecosystems. Our study determined habitat, in particular the degree of association of an organism with the sediment-water interface, to be the primary factor in controlling transuranic concentrations in aquatic biota. In most of the biological samples analyzed, excluding samples suspected of being contaminated by sediment, 241 Am/ 239 Pu, 244 Cm/ 239 Pu, and 238 U/ 239 Pu ratios were greater than the respective ratio in sediment while 233 234 U/ 238 U, and 239 240 Pu/ 238 Pu ratios were not different from the respective ratios in sediment. The relative uptake of actinides from contaminated sediment by aquatic and terrestrial biota at this site was U > Cm greater than or equal to Am > Pu. The relative extractability of actinides from shoreline sediment was U > Cm approx. = Am > Pu; we also observed the same relative ranking for sediment-water exchange in situ. Concentrations of transuranics in water, terrestrial vegetation, and vertebrate carcasses were less than 10% of the recommended public exposure maximum permissible concentration (MPC) of the ICRP

  18. Harvesting of freshwater microalgae biomass by Scenedesmus sp. as bioflocculant

    Science.gov (United States)

    Rinanti, A.; Purwadi, R.

    2018-01-01

    This study is particularly expected to provide information on the diversity of microalgae as the flocculant agent that gives the highest biomass yield. Bioflocculation was done by using one of the flocculating microalgae i.e. Scenedesmus obliquus to concentrate on non-flocculating microalgae Chlorella vulgaris. The freshwater microalgae S. obliquus tested it ability to harvest other non-flocculating microalgae, increased sedimentation rate in the flocculation process and increased biomass yield. The flocculation of biomass microalgae with chemical flocculant as comparison was done by adding alum (K2SO4·Al2 (SO4)3·24H2O). The addition of alum (K2SO4·Al2 (SO4)3·24H2O) as flocculant at pH 11 and S. obliquus sp. as bioflocculant caused significant alteration of nutrition of microalgae. Overall, the essential content produced by flocculation method with addition of alum or with bioflocculation (%, mg/100 mg dry weight) are lipid 31,64; 38,69, protein 30,79; 38.50%, and chlorophyll 0.6253; 0.8420). Harvesting with bioflocculation methods conducted at the end of the cultivation period increase the amount of biomass significantly and can accelerate the settling time of biomass. Harvesting microalgae cells by bioflocculation method becomes an economically competitive harvesting method compared to alum as a chemical flocculant because of the cheaper cost of flocculant, not toxic so it does not require further water treatment after harvesting due to the use of alum as chemical flocculants.

  19. The maintenance of hybrids by parasitism in a freshwater snail.

    Science.gov (United States)

    Guttel, Yonathan; Ben-Ami, Frida

    2014-11-01

    Hybrids have often been labelled evolutionary dead-ends due to their lower fertility and viability. However, there is growing awareness that hybridisation between different species may play a constructive role in animal evolution as a means to create variability. Thus, hybridisation and introgression may contribute to adaptive evolution, for example with regards to natural antagonists (parasites, predators, competitors) and adaptation to local environmental conditions. Here we investigated whether parasite intensity contributes to the continuous recreation of hybrids in 74 natural populations of Melanopsis, a complex of freshwater snails with three species. We also examined, under laboratory conditions, whether hybrids and their parental taxa differ in their tolerance of low and high temperatures and salinity levels. Infections were consistently less prevalent in males than in females, and lower in snails from deeper habitats. Infection prevalence in hybrids was significantly lower than in the parental taxa. Low hybrid infection rates could not be explained by sediment type, snail density or geographic distribution of the sampling sites. Interestingly, infected hybrid snails did not show signs of parasite-induced gigantism, whereas all parental taxa did. We found that hybrids mostly coped with extreme temperatures and salinity levels as well as their parental taxa did. Taken together, our results suggest that Melanopsis hybrids perform better in the presence of parasites and environmental stress. This may explain the widespread and long-term occurrence of Melanopsis hybrids as evidenced by paleontological and biogeographic data. Hybridisation may be an adaptive host strategy, reducing infection rates and resisting gigantism. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  20. Nutrient budgets and effluent characteristics in giant freshwater prawn (Macrobrachium rosenbergii) culture ponds.

    Science.gov (United States)

    Adhikari, Subhendu; Sahu, Bharat Chandra; Mahapatra, Abhijit S; Dey, Lambodar

    2014-05-01

    It is important to understand nutrient budgets of aquaculture practices for efficiency of input resources and to utilize all output nutrient sources. The aim of the present study was to develop a nutrient budget for giant freshwater prawn (Macrobrachium rosenbergii) culture ponds. The study was conducted in farmer's ponds (0.25-0.5 ha) of Odisha, India, and the results showed that feed accounted 97% total nitrogen (N), 98.7% total phosphorus (P) and 90% total organic carbon (OC), respectively. The harvested prawn accounted for recovery of 37% N, 10% P and 15% OC, respectively. The N, P and OC accumulated in sediment were 52%, 76%, and 65%, respectively. Nutrient loads in the effluents were 2.22 ± 0.66 kg inorganic N, 0.40 ± 0.15 kg P, and 21.01 ± 6.4 kg OC per ton of prawn production. The present study implicated that high nutrient values observed in both water and sediment provide important opportunities for nutrient reuse through pond sediment applications to croplands as an organic manure, as well as pond water irrigation to crops as a "liquid fertilizer".

  1. Sediment supply to beaches

    DEFF Research Database (Denmark)

    Aagaard, Troels

    2014-01-01

    and this reduces confidence in predictions of long-term shoreline change. In this paper, field measurements of suspended sediment load and cross-shore transport on the lower shoreface are used to derive a model for sediment supply from the lower to the upper shoreface at large spatial and temporal scales. Data...

  2. Radurization of commercial freshwater fish species

    International Nuclear Information System (INIS)

    Chuaqui-Offermanns, N.; McDougall, T.E.; Sprung, W.; Sullivan, V.

    1988-01-01

    The effect of radurization on the shelf life of fresh Whitefish obtained through ordinary commercial channels has been determined. Whitefish fillets irradiated at 1.2 kGy and stored at 3 0 C have a shelf life three times longer than the unirradiated fish. When the fish was irradiated at 0.82 kGy a two fold shelf-life extension was obtained. The shelf life was estimated by sensory, chemical and microbiological evaluations. Sensory evaluation involved organoleptic assessment of raw and cooked samples. Since freshwater fish do not contain trimethylamine oxide (TMAO), alternate tests for freshness were required. It was found the determination of hypoxanthine and total volatile acid number (VAN) are excellent tests for freshness and quality of freshwater fish; thus, these analyses were adopted. The degree of radiation-induced lipid oxidation was measured by the thiobarbituric acid test (TBA). It was found at doses of 0.82 and 1.2 kGy the TBA number remained within acceptable limits in all samples. Microbiological analyses consisted of the total microbial load assessment in the sample, as well as Pseudomonas and total psychrotrophic counts. The estimated shelf lives as determined by the three separate evaluations were in very good agreement. (author)

  3. Ammonium transformation in a nitrogen-rich tidal freshwater marsh

    DEFF Research Database (Denmark)

    Gribsholt, B.; Andersson, M.; Boschker, H.T.S.

    2006-01-01

    The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River, Belgium, was quantified in a whole ecosystem 15N labeling experiment. In late summer (September) we added 15N-NH4+ to the flood water entering a 3477 m2 tidal freshwater marsh...

  4. Culture of the freshwater rotifer, Brachionus calyciflorus , and its ...

    African Journals Online (AJOL)

    This paper attempts to review the principles and procedures involved in the culture of the freshwater rotifer, Brachionus calyciflorus as starter food for most freshwater fish fry. There are several strains of different sizes of this rotifer, thus making them suitable for fry of a variety of sizes. This rotifer can be isolated, continuously ...

  5. Survival and growth of Clarias gariepinus larvae fed with freshwater ...

    African Journals Online (AJOL)

    respectively 9.74 ± 0.20 mg and 15.49 ± 0.26%.day-1) were significantly different (p ˂ 0.05) from those raised with freshwater zooplankton (respectively 8.93 ± 0.31 mg and 14.40 ± 0.43%.day-1). Freshwater local zooplankton produced with pig ...

  6. Potential impacts of alien freshwater crayfish in South Africa | de ...

    African Journals Online (AJOL)

    The habitat preferences and life history characteristics of four alien species of freshwater crayfish (Cherax tenuimanus, C. destructor, C. quadricarinatus and Procambarus clarkii) are reviewed. The potential impact of these species on South African freshwater ecosystems is assessed and the desirability of allowing their ...

  7. Snail abundance in freshwater canals in the eastern province of ...

    African Journals Online (AJOL)

    Ksu-network

    2012-07-19

    Jul 19, 2012 ... Recent Advances in Freshwater Biology. New Delhi. Anmol. Publication. Vol. 2. pp. 187-202. Al-Akel and Suliman. 12261. Supian Z, Ikhwanuddin AM (2002). Population dynamics of freshwater mollusks (Gastropod: Melanoides Tuberculatus) in crocker range park, Sabah. ASEAN Rev. Biodiv. Environ.

  8. Recent changes in the freshwater composition east of Greenland

    NARCIS (Netherlands)

    de Steur, L.; Pickart, R.S.; Torres, D.J.; Valdimarsson, H.

    2015-01-01

    Results from three hydrographic surveys across the East Greenland Current between 2011 and 2013 are presented with focus on the freshwater sources. End-member analysis using salinity, d18O, and nutrient data shows that while meteoric water dominated the freshwater content, a significant amount of

  9. DNA barcoding of South Africa's ornamental freshwater fish – are ...

    African Journals Online (AJOL)

    DNA barcoding of South Africa's ornamental freshwater fish – are the names reliable? ... African Journal of Aquatic Science ... Because its effective implementation requires accurate identification, the aim of the present study was to test whether DNA barcoding is a useful tool to identify freshwater fishes in the South African ...

  10. Occurrence of digenean larvae in freshwater snails in the Ruvu ...

    African Journals Online (AJOL)

    Occurrence of digenean larvae in freshwater snails in the Ruvu basin, Tanzania. G Nkwengulila, ESP Kigadye. Abstract. A survey was carried out on digenean larvae infecting freshwater snails in five habitats in Dar es Salaam, Ruvu and Morogoro. 9424 snails belonging to 12 species from five families were examined for ...

  11. Book Review A Complete Guide to the Freshwater Fishes of ...

    African Journals Online (AJOL)

    A Complete Guide to the Freshwater. Fishes of Southern Africa. P.H. Skelton. Illustrated by Dave Voorvelt and Elizabeth Tarr. Southern Book Publishers, November 1993. 388 pages. Price: Hardback R90, Paperback R80. Those of us interested in freshwater fishes and related environmental issues have waited several ...

  12. Freshwater nematodes from South Africa. 4. The genus Monhystera ...

    African Journals Online (AJOL)

    Freshwater nematodes from South Africa. 4. The genus Monhystera Bastian, 1865. A.P. Joubert and J. Heyns. Department of Zoology. Rand Afrikaans University. During a survey of freshwater nematodes in South Africa, five species of Monhystera Bastian, 1865, were encountered. The five species, three of which are new to ...

  13. Groundwater seeps as potentially important refugia for freshwater ...

    African Journals Online (AJOL)

    The freshwater wetlands on the Eastern Shores of Lake St Lucia provide an important habitat for freshwater fishes, including a number of IUCN Red Listed species. The ecology of these wetlands is influenced greatly by water flowing from the large sand aquifers along the lake's eastern shoreline. Of the various aquatic ...

  14. Freshwater clams as bioconcentrators of avian influenza virus in water.

    Science.gov (United States)

    Huyvaert, Kathryn P; Carlson, Jenny S; Bentler, Kevin T; Cobble, Kacy R; Nolte, Dale L; Franklin, Alan B

    2012-10-01

    We report experimental evidence for bioconcentration of a low-pathogenicity avian influenza virus (H6N8) in the tissue of freshwater clams. Our results support the concept that freshwater clams may provide an effective tool for use in the early detection of influenza A viruses in aquatic environments.

  15. The rediscovery of the freshwater shrimp Macrobrachium crenulatum in Jamaica

    NARCIS (Netherlands)

    Hunte, Waine

    1979-01-01

    A record of the freshwater shrimps of Jamaica has been provided by Hart (1961b). His study includes taxonomical comments and notes on the locations at which the various species were caught. Since then Holthuis (1963a) has described a new subterranean freshwater shrimp, Troglocubanus jamaicensis,

  16. Invasive alien freshwater fishes in the Wilderness Lakes System, a ...

    African Journals Online (AJOL)

    Invasive alien freshwater fishes in the Wilderness Lakes System, a wetland of international importance in the Western Cape Province, South Africa. ... A total of 87 893 fish comprising 16 species were caught. In addition to confirming the ... Key words: freshwater fish, invasive alien fishes, estuary, RAMSAR site, diversity.

  17. Short Communications: First record of freshwater fish on the Cape ...

    African Journals Online (AJOL)

    During a non-exhaustive survey of freshwater bodies on five islands of the archipelago, the first presence of a freshwater fish was recorded. Using barcoding sequences, the species was identified as the guppy (Poecilia reticulata), a highly invasive species alien to the Cape Verdean Islands. Key words: Cape Verde, guppy, ...

  18. North American freshwater mussels: natural history, ecology, and conservation

    Science.gov (United States)

    Wendell R. Haag

    2012-01-01

    Interest in freshwater mussels is growing for two important reasons. First, freshwater mussels are among the most endangered organisms on Earth, and many species are already extinct or face imminent extinction. Their desperate conservation plight has gained intense interest from natural resource agencies, nongovernmental conservation organizations, academia, and...

  19. Tracking salinity intrusions in a coastal forested freshwater wetland system

    Science.gov (United States)

    Anand D. Jayakaran; Thomas M. Williams; William H. Conner

    2016-01-01

    Coastal forested freshwater wetlands are sentinel sites for salinity intrusions associated with large, tidally influenced, storm-driven or drought-induced incursions of estuarine waters into freshwater ecosystems. These incursions may also be exacerbated by rising sea levels associated with climate change.

  20. Distribution patterns of fishes in a freshwater deprived Eastern Cape ...

    African Journals Online (AJOL)

    The reduced riverine flow into the Kariega Estuary resulted in an extremely restricted river-estuary interface (REI) zone being made available to resident and migrant fish species. Despite the low freshwater input recorded, the catadromous freshwater mullet Myxus capensis was abundant within the REI zone and headwater ...

  1. Organic matter degradation in Lake Baikal - a sediment trap study

    DEFF Research Database (Denmark)

    Schubert, Carsten J.; Niggemann, Jutta; Lomstein, Bente Aagaard

    Lake Baikal offers a unique opportunity to study water column processes in a freshwater system with conditions similar to oceanic systems, e. g. great water depth and oxygenated water column. Investigations on sediment trap material provide information on the early stages of organic matter...... degradation in the water column. Sediment trap material from 18 different water depths has been analysed for bulk organic matter parameters, including organic carbon and nitrogen isotopic compositions, chlorin concentrations, and Chlorin Indices [1]. Detailed studies focused on the concentration...... and composition of amino acids and fatty acids. The extent of organic matter degradation in the water column of Lake Baikal is reflected in the fluxes of total organic carbon, chlorins, amino acids, and fatty acids at different water depths. In line with earlier studies in marine systems, the labile compounds...

  2. Monitoring of heavy metals in marine and freshwater fishes and nutritional evaluation of fish consumption

    International Nuclear Information System (INIS)

    Rina Mulyaningsih

    2014-01-01

    Fish is a food source of minerals. Uptake of heavy metals in fish could come from water, sediment and fish feed. Monitoring of minerals content and contaminants in fish has been carried out to evaluate nutrition and food safety, using neutron activation analysis techniques. Marine fish species that being analyzed are Kembung (Rastrelliger faughni), mackerel (Acanthocybium solandri), Tuna (Authis thazard) and freshwater fishes are Bawal (Colossoma macropomum), Nila (Oreochromis niloticus), Mas (Cyprinus carpio), sampled from 6 markets in North Jakarta. Monitoring results indicate that the essential minerals contained in fish are Fe, K, Na, Zn, Ca, Mg, and Se. Se and Ca concentrations in marine fish are higher than in freshwater fish. The concentration of other essential elements varies depending on the type of fish. The concentration of arsenic in marine fish is 3 times higher than that of freshwater fish; Hg and Cr content in all fish species were observed. From the evaluation of the adequacy of nutrition, with assuming a consumption of 86.68 g fish/day, for men aged 19 - 30 years, and referring to data from the Institute of Medicine USA, the Ca intake : 2.5 - 6.3; Cl : 1.5 - 3.3; Fe : 11.5 - 26.9; Na : 1.5 - 4.1; K : 3.4 - 6.7 and Zn 3.9 - 7.2% of the recommended value. Cr intake exceeds the recommended value, while As and Hg is not recommended in the food. In fact these metals contained in the studied fish, but the concentration is still below the value of standards issued by BPOM. (author)

  3. Mercury in freshwater ecosystems of the Canadian Arctic: recent advances on its cycling and fate.

    Science.gov (United States)

    Chételat, John; Amyot, Marc; Arp, Paul; Blais, Jules M; Depew, David; Emmerton, Craig A; Evans, Marlene; Gamberg, Mary; Gantner, Nikolaus; Girard, Catherine; Graydon, Jennifer; Kirk, Jane; Lean, David; Lehnherr, Igor; Muir, Derek; Nasr, Mina; Poulain, Alexandre J; Power, Michael; Roach, Pat; Stern, Gary; Swanson, Heidi; van der Velden, Shannon

    2015-03-15

    The Canadian Arctic has vast freshwater resources, and fish are important in the diet of many Northerners. Mercury is a contaminant of concern because of its potential toxicity and elevated bioaccumulation in some fish populations. Over the last decade, significant advances have been made in characterizing the cycling and fate of mercury in these freshwater environments. Large amounts of new data on concentrations, speciation and fluxes of Hg are provided and summarized for water and sediment, which were virtually absent for the Canadian Arctic a decade ago. The biogeochemical processes that control the speciation of mercury remain poorly resolved, including the sites and controls of methylmercury production. Food web studies have examined the roles of Hg uptake, trophic transfer, and diet for Hg bioaccumulation in fish, and, in particular, advances have been made in identifying determinants of mercury levels in lake-dwelling and sea-run forms of Arctic char. In a comparison of common freshwater fish species that were sampled across the Canadian Arctic between 2002 and 2009, no geographic patterns or regional hotspots were evident. Over the last two to four decades, Hg concentrations have increased in some monitored populations of fish in the Mackenzie River Basin while other populations from the Yukon and Nunavut showed no change or a slight decline. The different Hg trends indicate that the drivers of temporal change may be regional or habitat-specific. The Canadian Arctic is undergoing profound environmental change, and preliminary evidence suggests that it may be impacting the cycling and bioaccumulation of mercury. Further research is needed to investigate climate change impacts on the Hg cycle as well as biogeochemical controls of methylmercury production and the processes leading to increasing Hg levels in some fish populations in the Canadian Arctic. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  4. Fluvial sedimentation in Kentucky

    Science.gov (United States)

    Flint, R.F.

    1983-01-01

    Covering periods 1942-45 and 1951-81, this report documents the characteristics of sediments being transported from 79 drainage areas within the Commonwealth of Kentucky, and from eight stations on the main stem of the Ohio River. The drainage areas range in size from 0.67 square mile at Cane Branch near Parkers Lake to 40,330 square miles at Tennessee River near Paducah. Sediment yields and particle size of suspended and bed sediments are discussed by physiographic province. The Blue Grass had the highest average annual suspended-sediment yield for selected stations of 741 tons per square mile, and the Western Coal Field had the lowest with 197. The Eastern Coal Field had the broadest range of annual suspended-sediment yields. The range was from 25 tons per square mile at Helton Branch near Greenwood to 21,000 tons per square mile at Millers Creek near Phyllis. For selected stations bedload discharge was estimated to be 5 to 10 percent as much as the suspended-sediment discharge. Only three drainage areas had sediment yields that exceeded the average annual erosion rates for cultivated land in Kentucky of 9.93 tons per acre (6,355 tons per square mile). These three were in the Eastern Coal Field. (USGS)

  5. Numerical modeling of cohesive sediment transport and bed morphology in estuaries

    OpenAIRE

    Leupi, Célestin; Deville, Michel; Altinakar, Mustafa S.

    2007-01-01

    Two major lines of investigation have been pursued in this thesis: (1) More efficient, robust and realistic numerical techniques are designed for the simulation of complex turbulent fluid flows; (2) A new algorithm and its analysis is performed in the context of multiphasic fluid flow, for a cohesive fine-grained sediment (fluid mud) transport in estuaries. Estuaries exist between marine and freshwater system where waters of different physical, chemical and biological composition meet, combin...

  6. Pattern recognition on X-ray fluorescence records from Copenhagen lake sediments using principal component analysis

    DEFF Research Database (Denmark)

    Schreiber, Norman; Garcia, Emanuel; Kroon, Aart

    2014-01-01

    Principle Component Analysis (PCA) was performed on chemical data of two sediment cores from an urban fresh-water lake in Copenhagen, Denmark. X-ray fluorescence (XRF) core scanning provided the underlying datasets on 13 variables (Si, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Cd, Pb). Principle...... Component Analysis helped to trace geochemical patterns and temporal trends in lake sedimentation. The PCA models explained more than 80 % of the original variation in the datasets using only 2 or 3 principle components. The first principle component (PC1) was mostly associated with geogenic elements (Si, K...

  7. Sediment dispersal pattern in the Bay of Bengal - evidence for commencement of Bengal Fan sedimentation

    Science.gov (United States)

    Krishna, K. S.; Ismaiel, M.; Karlapati, S.; Gopala Rao, D.; Mishra, J.; D, S.

    2015-12-01

    The sediment succession in the Bay of Bengal records signatures corresponding to India-Asia collision, regional climate, and erosional processes of the Himalayan orogeny and the Indian subcontinent. The Bengal Fan - world's largest submarine fan - has been long studied to understand the link between the Himalayan tectonics and Asian monsoon climate, but early phase information of the Himalaya erosion is not retrieved from the Indian Ocean due to lack of deep-core samples. Therefore, the missing corresponding signals hampered the understanding of coupled processes between tectonics, climate and erosion. Seismic reflection profiles and industrial drill wells from the western Bay of Bengal show two different modes of sediment deposition: initially Indian peninsular rivers discharged sediments to the ocean at a rate ~20 m/m.y. until Oligocene-Miocene time (~23 Ma) with the exception of two fairly-enhanced sediment pulses from 65 to 54 and again from 34 to 23 Ma; since 23 Ma the Ganges and Brahmaputra rivers added huge volumes of sediments to the bay with variable rates range from 40 to >1000 m/m.y. Using seismic stratigraphic technique we found a distinct increase in sediment discharge (~140 m/m.y.) at 23 Ma is an important age marker for the onset of Bengal Fan sedimentation as a coupled connection between the Himalayan tectonics and Asian climate. Further rise in sedimentation rate during the period 6.8 - 0.8 Ma is surprisingly not in agreement with the decrease in sediment rate reported at ODP Leg 116 sites in the distal Bengal Fan, but coincident with the change in monsoon intensity. Here we provide well constrained ages for the growth of the Bengal Fan, which can serve as benchmark for interactions between the Himalayan exhumation and Asian climate.

  8. Lognormal distribution of natural radionuclides in freshwater ecosystems and coal-ash repositories

    International Nuclear Information System (INIS)

    Drndarski, N.; Lavi, N.

    1997-01-01

    This study summarizes and analyses data for natural radionuclides, 40 K, 226 Ra and 'Th, measured by gamma spectrometry in water samples, sediments and coal-ash samples collected from regional freshwater ecosystems and near-by coal-ash repositories during the last decade, 1986-1996, respectively. The frequency plots of natural radionuclide data, for which the hypothesis of the regional scale log normality was accepted, exhibited single population groups with exception of 226 Ra and 232 Th data for waters. Thus the presence of break points in the frequency distribution plots indicated that 226 Ra and 232 Th data for waters do not come from a single statistical population. Thereafter the hypothesis of log normality was accepted for the separate population groups of 226 Ra and '-32 Th in waters. (authors)

  9. Methane emissions from oceans, coasts, and freshwater habitats: New perspectives and feedbacks on climate

    Science.gov (United States)

    Hamdan, Leila J.; Wickland, Kimberly P.

    2016-01-01

    Methane is a powerful greenhouse gas, and atmospheric concentrations have risen 2.5 times since the beginning of the Industrial age. While much of this increase is attributed to anthropogenic sources, natural sources, which contribute between 35% and 50% of global methane emissions, are thought to have a role in the atmospheric methane increase, in part due to human influences. Methane emissions from many natural sources are sensitive to climate, and positive feedbacks from climate change and cultural eutrophication may promote increased emissions to the atmosphere. These natural sources include aquatic environments such as wetlands, freshwater lakes, streams and rivers, and estuarine, coastal, and marine systems. Furthermore, there are significant marine sediment stores of methane in the form of clathrates that are vulnerable to mobilization and release to the atmosphere from climate feedbacks, and subsurface thermogenic gas which in exceptional cases may be released following accidents and disasters (North Sea blowout and Deepwater Horizon Spill respectively). Understanding of natural sources, key processes, and controls on emission is continually evolving as new measurement and modeling capabilities develop, and different sources and processes are revealed. This special issue of Limnology and Oceanography gathers together diverse studies on methane production, consumption, and emissions from freshwater, estuarine, and marine systems, and provides a broad view of the current science on methane dynamics of aquatic ecosystems. Here, we provide a general overview of aquatic methane sources, their contribution to the global methane budget, and key uncertainties. We then briefly summarize the contributions to and highlights of this special issue.

  10. The contribution of bank and surface sediments to fluvial sediment ...

    African Journals Online (AJOL)

    Sediment source studies involving a simple mixing model was undertaken in the Pra River Basin in Ghana using a single tracer 210Pb to determine the relative contribution of surface and bank sediments to the fluvial sediment transport. Sediment source tracing was performed on the basis of sub-basins by comparing the ...

  11. History, applications, methodological issues and perspectives for the use of environmental DNA (eDNA) in marine and freshwater environments.

    Science.gov (United States)

    Díaz-Ferguson, Edgardo E; Moyer, Gregory R

    2014-12-01

    Genetic material (short DNA fragments) left behind by species in nonliving components of the environment (e.g. soil, sediment, or water) is defined as environmental DNA (eDNA). This DNA has been previously described as particulate DNA and has been used to detect and describe microbial communities in marine sediments since the mid-1980's and phytoplankton communities in the water column since the early-1990's. More recently, eDNA has been used to monitor invasive or endangered vertebrate and invertebrate species. While there is a steady increase in the applicability of eDNA as a monitoring tool, a variety of eDNA applications are emerging in fields such as forensics, population and community ecology, and taxonomy. This review provides scientist with an understanding of the methods underlying eDNA detection as well as applications, key methodological considerations, and emerging areas of interest for its use in ecology and conservation of freshwater and marine environments.

  12. Bioinvasion Triggers Rapid Evolution of Life Histories in Freshwater Snails.

    Science.gov (United States)

    Chapuis, Elodie; Lamy, Thomas; Pointier, Jean-Pierre; Juillet, Nicolas; Ségard, Adeline; Jarne, Philippe; David, Patrice

    2017-11-01

    Biological invasions offer interesting situations for observing how novel interactions between closely related, formerly allopatric species may trigger phenotypic evolution in situ. Assuming that successful invaders are usually filtered to be competitively dominant, invasive and native species may follow different trajectories. Natives may evolve traits that minimize the negative impact of competition, while trait shifts in invasives should mostly reflect expansion dynamics, through selection for colonization ability and transiently enhanced mutation load at the colonization front. These ideas were tested through a large-scale common-garden experiment measuring life-history traits in two closely related snail species, one invasive and one native, co-occurring in a network of freshwater ponds in Guadeloupe. We looked for evidence of recent evolution by comparing uninvaded or recently invaded sites with long-invaded ones. The native species adopted a life history favoring rapid population growth (i.e., increased fecundity, earlier reproduction, and increased juvenile survival) that may increase its prospects of coexistence with the more competitive invader. We discuss why these effects are more likely to result from genetic change than from maternal effects. The invader exhibited slightly decreased overall performances in recently colonized sites, consistent with a moderate expansion load resulting from local founder effects. Our study highlights a rare example of rapid life-history evolution following invasion.

  13. How are macroinvertebrates of slow flowing lotic systems directly affected by suspended and deposited sediments?

    Energy Technology Data Exchange (ETDEWEB)

    Kefford, Ben J., E-mail: ben.kefford@rmit.edu.a [Biotechnology and Environmental Biology, School of Applied Sciences, RMIT University, PO Box 71, Bundoora, Victoria 3083 (Australia); Zalizniak, Liliana [Biotechnology and Environmental Biology, School of Applied Sciences, RMIT University, PO Box 71, Bundoora, Victoria 3083 (Australia); Dunlop, Jason E. [Department of Environment and Resource Management (DERM), 120 Meiers Rd, Indooroopilly, Queensland 4068 (Australia); Smart Water Research Facility, Griffith University, Queensland (Australia); Nugegoda, Dayanthi [Biotechnology and Environmental Biology, School of Applied Sciences, RMIT University, PO Box 71, Bundoora, Victoria 3083 (Australia); Choy, Satish C. [Department of Environment and Resource Management (DERM), 120 Meiers Rd, Indooroopilly, Queensland 4068 (Australia)

    2010-02-15

    The effects of suspended and deposited sediments on the macroinvertebrates are well documented in upland streams but not in slower flowing lowland rivers. Using species found in lowland lotic environments, we experimentally evaluate mechanisms for sediments to affect macroinvertebrates, and in one experiment whether salinity alters the effect of suspended sediments. Suspended kaolin clay reduced feeding of Ischnura heterosticta (Odonata: Coenagrionidae) at high turbidity (1000-1500 NTU) but had no effects on feeding of Hemianax papuensis (Odonata: Aeshnidae) and Micronecta australiensis (Hemiptera: Corixidae). In freshwater (0.1 mS/cm), survival of Ischnura aurora was poor in clear water, but improved with suspended kaolin. Growth and feeding of I. aurora were unaffected by suspended sediments and salinity. Burial (1-5 mm) of eggs with kaolin or sand reduced hatching in Physa acuta (Gastropoda: Physidae), Gyraulus tasmanica (Gastropoda: Planorbidae) and Chironomus cloacalis (Diptera: Chironomidae). Settling sediments may pose greater risk to lowland lotic invertebrates than suspended sediments. - Sediment deposition may be more directly detrimental to macroinvertebrates of lowland rivers than suspended sediments.

  14. Influence of vegetation on spatial patterns of sediment deposition in deltaic islands during flood

    Science.gov (United States)

    Nardin, W.; Edmonds, D. A.; Fagherazzi, S.

    2016-07-01

    River deltas are shaped by the interaction between flow and sediment transport. This morphodynamic interaction is potentially affected by freshwater marsh vegetation (e.g. Sagittaria spp.and Typha spp. in the Mississippi delta, USA) on the exposed surfaces of emergent deltaic islands. The vulnerability of deltaic islands is a result of external forces like large storms, sea level rise, and trapping of sediment in upstream reservoirs. These factors can strongly determine the evolution of the deltaic system by influencing the coupling between vegetation dynamics and morphology. In the last few years, models have been developed to describe the dynamics of salt marsh geomorphology coupled with vegetation growth while the effect of freshwater vegetation on deltaic islands and marshes remains unexplored. Here we use a numerical flow and sediment transport model to determine how vegetation affects the spatial distribution of sediment transport and deposition on deltaic surfaces during flood. Our modeling results show that, for an intermediate value of relative vegetation height and density, sedimentation rate increases at the head of the delta. On the other hand, large values of relative vegetation height and density promote more sedimentation at the delta shoreline. A logical extension of our results is that over time intermediate values of relative vegetation height and density will create a steeper-sloped delta due to sediment trapping at the delta head, whereas relatively taller vegetation will create a larger, but flatter delta due to sediment deposition at the shoreline. This suggests intermediate relative vegetation height and density may create more resilient deltas with higher average elevations.

  15. Bioaccumulation and distribution of sup(95m)Tc in an experimental freshwater pond

    International Nuclear Information System (INIS)

    Blaylock, B.G.; Frank, M.L.

    1982-01-01

    The objectives of the study were (1) to determine the distribution of sup(95m)C in the components of the ecosystem and (2) to determine the concentration in freshwater biota. Prior to the release of sup(95m)Tc, the pond was stocked with aquatic macrophytes, fish, and invertebrates. All components of the pond were sampled for a period of 37 days. Analyses of filtered and unfiltered water samples showed that sup(95m)Tc did not sorb significantly to particulates suspended in the water but remained dissolved. Sediments accumulated sup(95m)Tc slowly as the experiment progressed. In the biota, periphyton accumulated sup(95m)Tc rapidly, reaching the highest concentration (3482 dis/min per g dry wt) 4 hours after the release and maintaining a relatively high concentration throughout the experiment. Fish and invertebrates accumulated sup(95m)Tc gradually. Elimination studies and tissue analyses showed that a large percentage of the body burden was in the digestive system of all fish, suggesting that fish were accumulating sup(95m)Tc through the food chain. Biological half-lives determined from elimination studies for carp (Cyprinus carpio), mosquitofish (Gambusia affinis), and snails (Helisoma sp.) were 2.5, 4.3, and 21.3 days, respectively. Calculated concentration factors for the same species were 11 for carp, 75 for mosquitofish, and 121 for snails. The estimated sizes of the biomass components in the ecosystem in descending order were: periphyton, macrophytes, invertebrates, fish, and algae. Based on biomass estimates and concentrations of the sup(95m)Tc in the aquatic biota, approximately 1% of the sup(95m)Tc accumulated in the biota. Thus, most of the technetium released into a freshwater pond ecosystem remained dissolved in the water with only a small percentage accumulating in the biota and sediments

  16. Fate of nano- and microplastic in freshwater systems: A modeling study.

    Science.gov (United States)

    Besseling, Ellen; Quik, Joris T K; Sun, Muzhi; Koelmans, Albert A

    2017-01-01

    Riverine transport to the marine environment is an important pathway for microplastic. However, information on fate and transport of nano- and microplastic in freshwater systems is lacking. Here we present scenario studies on the fate and transport of nano-to millimetre sized spherical particles like microbeads (100 nm-10 mm) with a state of the art spatiotemporally resolved hydrological model. The model accounts for advective transport, homo- and heteroaggregation, sedimentation-resuspension, polymer degradation, presence of biofilm and burial. Literature data were used to parameterize the model and additionally the attachment efficiency for heteroaggregation was determined experimentally. The attachment efficiency ranged from 0.004 to 0.2 for 70 nm and 1050 nm polystyrene particles aggregating with kaolin or bentonite clays in natural freshwater. Modeled effects of polymer density (1-1.5 kg/L) and biofilm formation were not large, due to the fact that variations in polymer density are largely overwhelmed by excess mass of suspended solids that form heteroaggregates with microplastic. Particle size had a dramatic effect on the modeled fate and retention of microplastic and on the positioning of the accumulation hot spots in the sediment along the river. Remarkably, retention was lowest (18-25%) for intermediate sized particles of about 5 μm, which implies that the smaller submicron particles as well as larger micro- and millimetre sized plastic are preferentially retained. Our results suggest that river hydrodynamics affect microplastic size distributions with profound implications for emissions to marine systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Spatiotemporal assessment (quarter century) of pulp mill metal(loid) contaminated sediment to inform remediation decisions.

    Science.gov (United States)

    Hoffman, Emma; Lyons, James; Boxall, James; Robertson, Cam; Lake, Craig B; Walker, Tony R

    2017-06-01

    A bleached kraft pulp mill in Nova Scotia has discharged effluent wastewater into Boat Harbour, a former tidal estuary within Pictou Landing First Nation since 1967. Fifty years of effluent discharge into Boat Harbour has created >170,000 m 3 of unconsolidated sediment, impacted by inorganic and organic contaminants, including metal[loid]s, polycyclic aromatic hydrocarbons (PAHs), dioxins, and furans. This study aimed to characterize metal(loid)-impacted sediments to inform decisions for a $89 million CAD sediment remediation program. The remediation goals are to return this impacted aquatic site to pre-mill tidal conditions. To understand historical sediment characteristics, spatiotemporal variation covering ~quarter century, of metal(loid) sediment concentrations across 103 Boat Harbour samples from 81 stations and four reference locations, were assessed by reviewing secondary data from 1992 to 2015. Metal(loid) sediment concentrations were compared to current Canadian freshwater and marine sediment quality guidelines (SQGs). Seven metal(loid)s, As, Cd, Cr, Cu, Pb, Hg, and Zn, exceeded low effect freshwater and marine SQGs; six, As, Cd, Cr, Pb, Hg, and Zn, exceeded severe effect freshwater SQGs; and four, Cd, Cu, Hg, and Zn, exceeded severe effect marine SQGs. Metal(loid) concentrations varied widely across three distinct temporal periods. Significantly higher Cd, Cu, Pb, Hg, and Zn concentrations were measured between 1998 and 2000, compared to earlier, 1992-1996 and more recent 2003-2015 data. Most samples, 69%, were shallow (0-15 cm), leaving deeper horizons under-characterized. Geographic information system (GIS) techniques also revealed inadequate spatial coverage, presenting challenges for remedy decisions regarding vertical and horizontal delineation of contaminants. Review of historical monitoring data revealed that gaps still exist in our understanding of sediment characteristics in Boat Harbour, including spatial, vertical and horizontal, and temporal

  18. Meeting the challenge of interacting threats in freshwater ecosystems: A call to scientists and managers

    Directory of Open Access Journals (Sweden)

    Laura S. Craig

    2017-12-01

    Full Text Available Human activities create threats that have consequences for freshwater ecosystems and, in most watersheds, observed ecological responses are the result of complex interactions among multiple threats and their associated ecological alterations. Here we discuss the value of considering multiple threats in research and management, offer suggestions for filling knowledge gaps, and provide guidance for addressing the urgent management challenges posed by multiple threats in freshwater ecosystems. There is a growing literature assessing responses to multiple alterations, and we build off this background to identify three areas that require greater attention: linking observed alterations to threats, understanding when and where threats overlap, and choosing metrics that best quantify the effects of multiple threats. Advancing science in these areas will help us understand existing ecosystem conditions and predict future risk from multiple threats. Because addressing the complex issues and novel ecosystems that arise from the interaction of multiple threats in freshwater ecosystems represents a significant management challenge, and the risks of management failure include loss of biodiversity, ecological goods, and ecosystem services, we also identify actions that could improve decision-making and management outcomes. These actions include drawing insights from management of individual threats, using threat attributes (e.g., causes and spatio-temporal dynamics to identify suitable management approaches, testing management strategies that are likely to be successful despite uncertainties about the nature of interactions among threats, avoiding unintended consequences, and maximizing conservation benefits. We also acknowledge the broadly applicable challenges of decision-making within a socio-political and economic framework, and suggest that multidisciplinary teams will be needed to innovate solutions to meet the current and future challenge of interacting

  19. A new sampler design for measuring sedimentation in streams

    Science.gov (United States)

    Hedrick, Lara B.; Welsh, S.A.; Hedrick, J.D.

    2005-01-01

    Sedimentation alters aquatic habitats and negatively affects fish and invertebrate communities but is difficult to quantify. To monitor bed load sedimentation, we designed a sampler with a 10.16-cm polyvinyl chloride coupling and removable sediment trap. We conducted a trial study of our samplers in riffle and pool habitats upstream and downstream of highway construction on a first-order Appalachian stream. Sediment samples were collected over three 6-week intervals, dried, and separated into five size-classes by means of nested sieves (U.S. standard sieve numbers 4, 8, 14, and 20). Downstream sediment accumulated in size-classes 1 and 2, and the total amount accumulated was significantly greater during all three sampling periods. Size-classes 3 and 4 had significantly greater amounts of sediment for the first two sampling periods at the downstream site. Differences between upstream and downstream sites narrowed during the 5-month sampling period. This probably reflects changes in site conditions, including the addition of more effective sediment control measures after the first 6-week period of the study. The sediment sampler design allowed for long-term placement of traps without continual disturbance of the streambed and was successful at providing repeat measures of sediment at paired sites. ?? Copyright by the American Fisheries Society 2005.

  20. Freshwater algae of the Nevada Test Site

    International Nuclear Information System (INIS)

    Taylor, W.D.; Giles, K.R.

    1979-06-01

    Fifty-two species of freshwater algae were identified in samples collected from the eight known natural springs of the Nevada Test Site. Although several species were widespread, 29 species were site specific. Diatoms provided the greatest variety of species at each spring. Three-fifths of all algal species encountered were diatoms. Well-developed mats of filamentous green algae (Chlorophyta) were common in many of the water tanks associated with the springs and accounted for most of the algal biomass. Major nutrients were adequate, if not abundant, in most spring waters - growth being limited primarily by light and physical habitat. There was some evidence of cesium-137 bioconcentration by algae at several of the springs

  1. Freshwater algae of the Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, W.D.; Giles, K.R.

    1979-06-01

    Fifty-two species of freshwater algae were identified in samples collected from the eight known natural springs of the Nevada Test Site. Although several species were widespread, 29 species were site specific. Diatoms provided the greatest variety of species at each spring. Three-fifths of all algal species encountered were diatoms. Well-developed mats of filamentous green algae (Chlorophyta) were common in many of the water tanks associated with the springs and accounted for most of the algal biomass. Major nutrients were adequate, if not abundant, in most spring waters - growth being limited primarily by light and physical habitat. There was some evidence of cesium-137 bioconcentration by algae at several of the springs.

  2. Freshwater bryozoa of Tonle Sap, Cambodia.

    Science.gov (United States)

    Hirose, Masato; Mawatari, Shunsuke F

    2007-06-01

    We identified a collection of freshwater bryozoans from Tonle Sap (meaning Tonle Lake), Cambodia, a body of water fed by the Mekong River and characterized by extreme fluctuations in water level between the wet and dry seasons. The collection also included specimens from the moat of Angkor Wat, located at the north end of the lake. We found four phylactolaemate species (Plumatella bombayensis, Plumatella casmiana, Plumatella vorstmani, Hyalinella lendenfeldi) and one ctenostome species (Hislopia cambodgiensis) from the lake, and only a single, additional phylactolaemate species (Plumatella javanica) from the moat. We provide brief descriptions of these species, photographs of colonies for some, and photomicrographs by light and scanning electron microscopy (SEM) of statoblasts. None of the species encountered in this study is endemic to Cambodia, and the wide distributions of the species are possibly related to the dispersability of floatoblasts by birds. We briefly discuss some of the taxonomic problems surrounding Hislopia cambodgiensis.

  3. Toxicities of selected substances to freshwater biota

    Energy Technology Data Exchange (ETDEWEB)

    Hohreiter, D.W.

    1980-05-01

    The amount of data available concerning the toxicity of various substances to freshwater biota is so large that it is difficult to use in a practical situation, such as environmental impact assessment. In this document, summary tables are presented showing acute and/or chronic toxicity of selected substances for various groups of aquatic biota. Each entry is referenced to its original source so that details concerning experimental conditions may be consulted. In addition, general information concerning factors modifying toxicity, synergisms, evidence of bioaccumulation, and water quality standards and criteria for the selected substances is given. The final table is a general toxicity table designed to provide an easily accessible and general indication of toxicity of selected substances in aquatic systems.

  4. Offshore Surficial Sediment

    Data.gov (United States)

    California Natural Resource Agency — This data layer (PAC_EXT.txt and PAC_PRS.txt) represents two of five point coverages of known sediment samples, inspections, and probes from the usSEABED data...

  5. Offshore Surficial Sediment

    Data.gov (United States)

    California Department of Resources — This data layer (PAC_EXT.txt and PAC_PRS.txt) represents two of five point coverages of known sediment samples, inspections, and probes from the usSEABED data...

  6. Sediment Resuspension Data

    Data.gov (United States)

    U.S. Environmental Protection Agency — The full report on sediment resuspension in drinking water storage tanks and a link to an animation of results. This dataset is associated with the following...

  7. Sediments and aquatic indicators

    International Nuclear Information System (INIS)

    1987-01-01

    Determinations of 90 Sr, certain gamma emitting nuclides and 239,240 Pu in bottom sediment in the Baltic Sea area and in sedimenting material and biota near the Loviisa and Olkiluoto nuclear power stations were continued in 1984 and 1985. In the bottom sediments of the deep Baltic basins, the total amounts of 90 Sr, 137 Cs and Pu were 8.5-80 Bq m -2 , 83-3200 Bq m -2 and 4.7-190 Bq m -2 , respectively. The ranges were about the same as in the earlier reports 1,2 . In sedimenting material and biota the conentrations of 90 Sr and 239,240 Pu were roughly the same as in 1983. The amounts and selection of reactor originated activation products were not changed in the vicinity of the two nuclear power stations. Small amounts of 137 Cs and 134 Cs released from the Loviisa nuclear power station were detected in 1985

  8. Bioaccumulation and retention kinetics of cadmium in the freshwater decapod Macrobrachium australiense

    Energy Technology Data Exchange (ETDEWEB)

    Cresswell, Tom, E-mail: tom.cresswell@ansto.gov.au [Centre for Environmental Contaminants Research, CSIRO Land and Water, Locked Bag 2007, Kirrawee, NSW 2232 (Australia); School of Applied Sciences, RMIT University, Plenty Road, Bundoora, VIC 3083 (Australia); Simpson, Stuart L. [School of Applied Sciences, RMIT University, Plenty Road, Bundoora, VIC 3083 (Australia); Smith, Ross E.W. [Hydrobiology, Lang Parade, Auchenflower, QLD 4066 (Australia); Nugegoda, Dayanthi [School of Applied Sciences, RMIT University, Plenty Road, Bundoora, VIC 3083 (Australia); Mazumder, Debashish [Institute for Environmental Research, ANSTO, Locked Bag 2001, Kirrawee, NSW 2232 (Australia); Twining, John [Austral Radioecology, Oyster Bay, NSW, 2225 (Australia)

    2014-03-01

    Highlights: • Sources and mechanisms of Cd bioaccumulation were examined using radiotracers. • Macrobrachium australiense readily accumulated cadmium from the dissolved phase. • Assimilation efficiencies were comparable for sediment and algae. • A biokinetic model predicted ingestion accounted for majority of bioaccumulated Cd. - Abstract: The potential sources and mechanisms of cadmium bioaccumulation by the native freshwater decapods Macrobrachium species in the waters of the highly turbid Strickland River in Papua New Guinea were examined using {sup 109}Cd-labelled water and food sources and the Australian species Macrobrachium australiense as a surrogate. Synthetic river water was spiked with environmentally relevant concentrations of cadmium and animals were exposed for 7 days with daily renewal of test solutions. Dietary assimilation of cadmium was assessed through pulse-chase experiments where prawns were fed separately {sup 109}Cd-labelled fine sediment, filamentous algae and carrion (represented by cephalothorax tissue of water-exposed prawns). M. australiense readily accumulated cadmium from the dissolved phase and the uptake rate increased linearly with increasing exposure concentration. A cadmium uptake rate constant of 0.10 ± 0.05 L/g/d was determined in synthetic river water. During depuration following exposure to dissolved cadmium, efflux rates were low (0.9 ± 5%/d) and were not dependent on exposure concentration. Assimilation efficiencies of dietary sources were comparable for sediment and algae (48–51%), but lower for carrion (28 ± 5%) and efflux rates were low (0.2–2.6%/d) demonstrating that cadmium was well retained by M. australiense. A biokinetic model of cadmium accumulation by M. australiense predicted that for exposures to environmentally relevant cadmium concentrations in the Strickland River, uptake from ingestion of fine sediment and carrion would be the predominant sources of cadmium to the organism. The model predicted

  9. Bioaccumulation and retention kinetics of cadmium in the freshwater decapod Macrobrachium australiense

    International Nuclear Information System (INIS)

    Cresswell, Tom; Simpson, Stuart L.; Smith, Ross E.W.; Nugegoda, Dayanthi; Mazumder, Debashish; Twining, John

    2014-01-01

    Highlights: • Sources and mechanisms of Cd bioaccumulation were examined using radiotracers. • Macrobrachium australiense readily accumulated cadmium from the dissolved phase. • Assimilation efficiencies were comparable for sediment and algae. • A biokinetic model predicted ingestion accounted for majority of bioaccumulated Cd. - Abstract: The potential sources and mechanisms of cadmium bioaccumulation by the native freshwater decapods Macrobrachium species in the waters of the highly turbid Strickland River in Papua New Guinea were examined using 109 Cd-labelled water and food sources and the Australian species Macrobrachium australiense as a surrogate. Synthetic river water was spiked with environmentally relevant concentrations of cadmium and animals were exposed for 7 days with daily renewal of test solutions. Dietary assimilation of cadmium was assessed through pulse-chase experiments where prawns were fed separately 109 Cd-labelled fine sediment, filamentous algae and carrion (represented by cephalothorax tissue of water-exposed prawns). M. australiense readily accumulated cadmium from the dissolved phase and the uptake rate increased linearly with increasing exposure concentration. A cadmium uptake rate constant of 0.10 ± 0.05 L/g/d was determined in synthetic river water. During depuration following exposure to dissolved cadmium, efflux rates were low (0.9 ± 5%/d) and were not dependent on exposure concentration. Assimilation efficiencies of dietary sources were comparable for sediment and algae (48–51%), but lower for carrion (28 ± 5%) and efflux rates were low (0.2–2.6%/d) demonstrating that cadmium was well retained by M. australiense. A biokinetic model of cadmium accumulation by M. australiense predicted that for exposures to environmentally relevant cadmium concentrations in the Strickland River, uptake from ingestion of fine sediment and carrion would be the predominant sources of cadmium to the organism. The model predicted the total

  10. Increased Amazon freshwater discharge during late Heinrich Stadial 1

    Science.gov (United States)

    Crivellari, Stefano; Chiessi, Cristiano Mazur; Kuhnert, Henning; Häggi, Christoph; da Costa Portilho-Ramos, Rodrigo; Zeng, Jing-Ying; Zhang, Yancheng; Schefuß, Enno; Mollenhauer, Gesine; Hefter, Jens; Alexandre, Felipe; Sampaio, Gilvan; Mulitza, Stefan

    2018-02-01

    The temporal succession of changes in Amazonian hydroclimate during Heinrich Stadial 1 (HS1) (ca. 18-14.7 cal ka BP) is currently poorly resolved. Here we present HS1 records based on isotope, inorganic and organic geochemistry from a marine sediment core influenced by the Amazon River discharge. Our records offer a detailed reconstruction of the changes in Amazonian hydroclimate during HS1, integrated over the basin. We reconstructed surface water hydrography using stable oxygen isotopes (δ18O) and Mg/Ca-derived paleotemperatures from the planktonic foraminifera Globigerinoides ruber, as well as salinity changes based on stable hydrogen isotope (δD) of palmitic acid. We also analyzed branched and isoprenoid tetraether concentrations, and compared them to existing bulk sediment ln(Fe/Ca) data and vegetation reconstruction based on stable carbon isotopes from n-alkanes, in order to understand the relationship between continental precipitation, vegetation and sediment production. Our results indicate a two-phased HS1 (HS1a and HS1b). During HS1a (18-16.9 cal ka BP), a first sudden increase of sea surface temperatures (SST) in the western equatorial Atlantic correlated with the slowdown of the Atlantic Meridional Overturning Circulation (AMOC) and the associated southern hemisphere warming phase of the bipolar seesaw. This phase was also characterized by an increased delivery of terrestrial material. During HS1b (16.9-14.8 cal ka BP), a decrease in terrestrial input was, however, associated with a marked decline of seawater δ18O and palmitic acid δD. Both isotopic proxies independently indicate a drop in sea surface salinity (SSS). A number of records under the influence of the North Brazil Current, in contrast, indicate increases in SST and SSS resulting from a weakened AMOC during HS1. Our records thus suggest that the expected increase in SSS due to the AMOC slowdown was overridden by a two-phased positive precipitation anomaly in Amazonian hydroclimate.

  11. Freshwater salinization syndrome on a continental scale.

    Science.gov (United States)

    Kaushal, Sujay S; Likens, Gene E; Pace, Michael L; Utz, Ryan M; Haq, Shahan; Gorman, Julia; Grese, Melissa

    2018-01-23

    Salt pollution and human-accelerated weathering are shifting the chemical composition of major ions in fresh water and increasing salinization and alkalinization across North America. We propose a concept, the freshwater salinization syndrome, which links salinization and alkalinization processes. This syndrome manifests as concurrent trends in specific conductance, pH, alkalinity, and base cations. Although individual trends can vary in strength, changes in salinization and alkalinization have affected 37% and 90%, respectively, of the drainage area of the contiguous United States over the past century. Across 232 United States Geological Survey (USGS) monitoring sites, 66% of stream and river sites showed a statistical increase in pH, which often began decades before acid rain regulations. The syndrome is most prominent in the densely populated eastern and midwestern United States, where salinity and alkalinity have increased most rapidly. The syndrome is caused by salt pollution (e.g., road deicers, irrigation runoff, sewage, potash), accelerated weathering and soil cation exchange, mining and resource extraction, and the presence of easily weathered minerals used in agriculture (lime) and urbanization (concrete). Increasing salts with strong bases and carbonates elevate acid neutralizing capacity and pH, and increasing sodium from salt pollution eventually displaces base cations on soil exchange sites, which further increases pH and alkalinization. Symptoms of the syndrome can include: infrastructure corrosion, contaminant mobilization, and variations in coastal ocean acidification caused by increasingly alkaline river inputs. Unless regulated and managed, the freshwater salinization syndrome can have significant impacts on ecosystem services such as safe drinking water, contaminant retention, and biodiversity. Copyright © 2018 the Author(s). Published by PNAS.

  12. Freshwater salinization syndrome on a continental scale

    Science.gov (United States)

    Likens, Gene E.; Pace, Michael L.; Utz, Ryan M.; Haq, Shahan; Gorman, Julia; Grese, Melissa

    2018-01-01

    Salt pollution and human-accelerated weathering are shifting the chemical composition of major ions in fresh water and increasing salinization and alkalinization across North America. We propose a concept, the freshwater salinization syndrome, which links salinization and alkalinization processes. This syndrome manifests as concurrent trends in specific conductance, pH, alkalinity, and base cations. Although individual trends can vary in strength, changes in salinization and alkalinization have affected 37% and 90%, respectively, of the drainage area of the contiguous United States over the past century. Across 232 United States Geological Survey (USGS) monitoring sites, 66% of stream and river sites showed a statistical increase in pH, which often began decades before acid rain regulations. The syndrome is most prominent in the densely populated eastern and midwestern United States, where salinity and alkalinity have increased most rapidly. The syndrome is caused by salt pollution (e.g., road deicers, irrigation runoff, sewage, potash), accelerated weathering and soil cation exchange, mining and resource extraction, and the presence of easily weathered minerals used in agriculture (lime) and urbanization (concrete). Increasing salts with strong bases and carbonates elevate acid neutralizing capacity and pH, and increasing sodium from salt pollution eventually displaces base cations on soil exchange sites, which further increases pH and alkalinization. Symptoms of the syndrome can include: infrastructure corrosion, contaminant mobilization, and variations in coastal ocean acidification caused by increasingly alkaline river inputs. Unless regulated and managed, the freshwater salinization syndrome can have significant impacts on ecosystem services such as safe drinking water, contaminant retention, and biodiversity. PMID:29311318

  13. Aeolian Sediment Availability and Transport

    NARCIS (Netherlands)

    Hoonhout, B.M.

    2017-01-01

    This thesis explores the nature of aeolian sediment availability and its influence on aeolian sediment transport. The aim is to improve large scale and long term aeolian sediment transport estimates in (nourished) coastal environments. The generally poor performance of aeolian sediment transport

  14. Modeling of extreme freshwater outflow from the north-eastern Japanese river basins to western Pacific Ocean

    Science.gov (United States)

    Troselj, Josko; Sayama, Takahiro; Varlamov, Sergey M.; Sasaki, Toshiharu; Racault, Marie-Fanny; Takara, Kaoru; Miyazawa, Yasumasa; Kuroki, Ryusuke; Yamagata, Toshio; Yamashiki, Yosuke

    2017-12-01

    This study demonstrates the importance of accurate extreme discharge input in hydrological and oceanographic combined modeling by introducing two extreme typhoon events. We investigated the effects of extreme freshwater outflow events from river mouths on sea surface salinity distribution (SSS) in the coastal zone of the north-eastern Japan. Previous studies have used observed discharge at the river mouth, as well as seasonally averaged inter-annual, annual, monthly or daily simulated data. Here, we reproduced the hourly peak discharge during two typhoon events for a targeted set of nine rivers and compared their impact on SSS in the coastal zone based on observed, climatological and simulated freshwater outflows in conjunction with verification of the results using satellite remote-sensing data. We created a set of hourly simulated freshwater outflow data from nine first-class Japanese river basins flowing to the western Pacific Ocean for the two targeted typhoon events (Chataan and Roke) and used it with the integrated hydrological (CDRMV3.1.1) and oceanographic (JCOPE-T) model, to compare the case using climatological mean monthly discharges as freshwater input from rivers with the case using our hydrological model simulated discharges. By using the CDRMV model optimized with the SCE-UA method, we successfully reproduced hindcasts for peak discharges of extreme typhoon events at the river mouths and could consider multiple river basin locations. Modeled SSS results were verified by comparison with Chlorophyll-a distribution, observed by satellite remote sensing. The projection of SSS in the coastal zone became more realistic than without including extreme freshwater outflow. These results suggest that our hydrological models with optimized model parameters calibrated to the Typhoon Roke and Chataan cases can be successfully used to predict runoff values from other extreme precipitation events with similar physical characteristics. Proper simulation of extreme

  15. Sensitivity of the regional ocean acidification and carbonate system in Puget Sound to ocean and freshwater inputs

    Directory of Open Access Journals (Sweden)

    Laura Bianucci

    2018-03-01

    Full Text Available While ocean acidification was first investigated as a global phenomenon, coastal acidification has received significant attention in recent years, as its impacts have been felt by different socio-economic sectors (e.g., high mortality of shellfish larvae in aquaculture farms. As a region that connects land and ocean, the Salish Sea (consisting of Puget Sound and the Straits of Juan de Fuca and Georgia receives inputs from many different sources (rivers, wastewater treatment plants, industrial waste treatment facilities, etc., making these coastal waters vulnerable to acidification. Moreover, the lowering of pH in the Northeast Pacific Ocean also affects the Salish Sea, as more acidic waters get transported into the bottom waters of the straits and estuaries. Here, we use a numerical ocean model of the Salish Sea to improve our understanding of the carbonate system in Puget Sound; in particular, we studied the sensitivity of carbonate variables (e.g., dissolved inorganic carbon, total alkalinity, pH, saturation state of aragonite to ocean and freshwater inputs. The model is an updated version of our FVCOM-ICM framework, with new carbonate-system and sediment modules. Sensitivity experiments altering concentrations at the open boundaries and freshwater sources indicate that not only ocean conditions entering the Strait of Juan de Fuca, but also the dilution of carbonate variables by freshwater sources, are key drivers of the carbonate system in Puget Sound.

  16. How northern freshwater input can stabilise thermohaline circulation

    Directory of Open Access Journals (Sweden)

    Erwin Lambert

    2016-11-01

    Full Text Available The North Atlantic thermohaline circulation (THC carries heat and salt towards the Arctic. This circulation is partly sustained by buoyancy loss and is generally believed to be inhibited by northern freshwater input as indicated by the ‘box-model’ of Stommel (1961. The inferred freshwater-sensitivity of the THC, however, varies considerably between studies, both quantitatively and qualitatively. The northernmost branch of the Atlantic THC, which forms a double estuarine circulation in the Arctic Mediterranean, is one example where both buoyancy loss and buoyancy gain facilitate circulation. We have built on Stommel's original concept to examine the freshwater-sensitivity of a double estuarine circulation. The net inflow into the double estuary is found to be more sensitive to a change in the distribution of freshwater than to a change in the total freshwater input. A double estuarine circulation is more stable than a single overturning, requiring a larger amount and more localised freshwater input into regions of buoyancy loss to induce a thermohaline ‘collapse’. For the Arctic Mediterranean, these findings imply that the Atlantic inflow may be relatively insensitive to increased freshwater input. Complementing Stommel's thermal and haline flow regimes, the double estuarine circulation allows for a third: the throughflow regime. In this regime, a THC with warm poleward surface flow can be sustained without production of dense water; a decrease in high-latitude dense water formation does therefore not necessarily affect regional surface conditions as strongly as generally thought.

  17. Aquatic Plant Control Research Program. Effects of Organic Amendments to Sediment on Freshwater Macrophyte Growth.

    Science.gov (United States)

    1983-10-01

    function. Annual Review of Phytopathology , 18, 37-66. Gambrell, R. P., and Patrick, W. H. 1978. Chemical and microbiological properties of anaerobic soils...products on plant roots. Annual Review of Phytopathology , 2, 267-292. Patterson, K. J., and Brown, J. M. A. 1979. Growth and elemental composition of the...analysis, respectively. Critical review comments, pro- vided by S. R. Carpenter, University of Notre Dame, and B. Moss, Univer- sity of East Anglia, were

  18. Effects of fluidized gas desulfurization (FGD) gypsum on non-target freshwater and sediment dwelling organims

    Science.gov (United States)

    Fluidized gas desulfurization gypsum is a popular agricultural soil amendment used to increase calcium and sulfur contents, and reduce aluminum toxicity. Due to its surface application in conservation tillage systems and high solubility, the soluble components of gypsum may be transferred with agri...

  19. Effect of Temperature on Oxygen Profiles and Denitrification Rates in Freshwater Sediments

    NARCIS (Netherlands)

    de Klein, Jeroen J.M.; Overbeek, Ciska C.; Juncher Jørgensen, Christian; Veraart, Annelies J.

    2017-01-01

    Vegetated ditches and wetlands are important sites for nutrient removal in agricultural catchments. About half of the influx of inorganic nitrogen can be removed from these ecosystems by denitrification. Previous studies have shown that denitrification in aquatic ecosystems is strongly temperature

  20. Effects of two common macrophytes on methane dynamics in freshwater sediments

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    1998-01-01

    The methane cycle in constructed wetlands without plants and with Phragmites australis (reed) and Scirpus lacustris (bulrush) was investigated. Variations in CH4 production largely determined variations in CH4 emission among the systems: rather than variations in CH4 storage and oxidation. Twofold

  1. The Sulfur Cycle of Fresh-Water Sediments - Role of Thiosulfate

    DEFF Research Database (Denmark)

    JØRGENSEN, BB

    1990-01-01

    of the oxidized sulfide was ultimately converte into SO4(2-) and half was recycled back to sulfide via S2O3(2-). Two-thirds of the S in the sulfide-thiosulfate "minicycle" remained at an oxidation state of -2. S2O3(2-) is thus a key intermediate in the S cycle, both as a main product of anoxic sulfide oxidation...

  2. DISTRIBUTION OF HEAVY METALS AMONG THE COMPONENTS OF FRESHWATER ECOSYSTEMS (REVIEW

    Directory of Open Access Journals (Sweden)

    N. Kolesnyk

    2014-09-01

    Full Text Available Purpose. To review scientific sources on the distribution of heavy metals among the components of freshwater ecosystems. Findings. The review of the works of many scientists showed that heavy metals are widespread in the biotic and abiotic components of freshwater ecosystems. The article highlights the distribution of heavy metals in water, bottom sediments, natural food base, fish organs and tissues. It has been shown that as a result of global pollution of the ecosystem, the majority of Ukrainian rivers belong to polluted and very polluted. Of special interest are the studies of the distribution of heavy metals in phytoplankton, zooplankton, and zoobenthos because these components occupy a certain position in fish food chain. The presence of heavy metals in the natural food base showed that, on one hand, it could accumulate heavy metals in large amounts in such a way cleaning the water; and on the other hand, the heavy metals could migrate in the food web and contaminate fish. Ones of objects, which should be given attention when assessing toxicologic pollution, are aquatic plants, in particular phytoplankton. Studies showed that the accumulation of heavy metals in plants occurred first of all by their adsorption on the cellular wall. It explains the maximum adsorption of heavy metals by plants immediately after introduction of heavy metals into their culture. Fish as a rule occupy in the food web of water bodies one of the last places. They actively move in the aquatic environment and accumulating heavy metals at the same time they provide the most integrated and precise estimate of environmental pollution. By analyzing the distribution of heavy metals in fish organs and tissues, depending on their ability to accumulate them, it can be noted that the accumulation is the most intensive in such organs as gills, liver, and kidneys. Usually, their lowest content is observed in muscles that is important for human life because they are the main

  3. Distribution and sources of organic carbon, nitrogen and their isotopic signatures in sediments from the Ayeyarwady (Irrawaddy) continental shelf, northern Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; Gaye, B.; Shirodkar, P.V.; Rao, P.S.; Chivas, A.R.; Wheeler, D.; Thwin, S.

    of freshwater and terrigenous sediment discharge. A simple two end-member carbon mixing model applied to the Ayeyarwady shelf region indicates that terrigenous sources contribute more than 70 % of the organic carbon in the modern mud belt in the inner shelf...

  4. Suspended particles only marginally reduce pyrethroid toxicity to the freshwater invertebrate Gammarus pulex (L.) during pulse exposure.

    Science.gov (United States)

    Rasmussen, Jes Jessen; Cedergreen, Nina; Kronvang, Brian; Andersen, Maj-Britt Bjergager; Nørum, Ulrik; Kretschmann, Andreas; Strobel, Bjarne Westergaard; Hansen, Hans Christian Bruun

    2016-04-01

    Current ecotoxicological research on particle-associated pyrethroids in freshwater systems focuses almost exclusively on sediment-exposure scenarios and sediment-dwelling macroinvertebrates. We studied how suspended particles influence acute effects of lambda-cyhalothrin and bifenthrin on the epibenthic freshwater amphipod Gammarus pulex (L.) using brief pulse exposures followed by a 144 h post exposure recovery phase. Humic acid (HA) and the clay mineral montmorillonite (MM) were used as model sorbents in environmentally realistic concentrations (5, 25 and 125 mg L(-1)). Mortality of G. pulex was recorded during the post exposure recovery phase and locomotor behavior was measured during exposure to lambda-cyhalothrin. We found that HA in concentrations ≥25 mg L(-1) adsorbed the majority of pyrethroids but only reduced mortality of G. pulex up to a factor of four compared to pyrethroid-only treatments. MM suspensions adsorbed a variable fraction of pyrethroids (10% for bifenthrin and 70% for lambda-cyhalothrin) but did not significantly change the concentration-response relationship compared to pure pyrethroid treatments. Behavioral responses and immobilisation rate of G. pulex were reduced in the presence of HA, whereas behavioral responses and immobilisation rate were increased in the presence of MM. This indicates that G. pulex was capable of sensing the bioavailable fraction of lambda-cyhalothrin. Our results imply that suspended particles reduce to only a limited extent the toxicity of pyrethroids to G. pulex and that passive uptake of pyrethroids can be significant even when pyrethroids are adsorbed to suspended particles.

  5. Sediment Lofting From Melt-Water Generated Turbidity Currents During Heinrich Events as a Tool to Assess Main Sediment Delivery Phases to Small Subpolar Ocean Basins

    Science.gov (United States)

    Hesse, R.

    2009-05-01

    Small subpolar ocean basins such as the Labrador Sea received a major portion (25%) of their sediment fill during the Pleistocene glaciations (less than 5% of the basin's lifetime), but the detailed timing of sediment supply to the basin remained essentially unknown until recently. The main sediment input into the basin was probably not coupled to major glacial cycles and associated sea-level changes but was related to Heinrich events. Discovery of the depositional facies of fine-grained lofted sediment provides a tool which suggests that the parent-currents from which lofting took place may have been sandy-gravelly turbidity currents that built a huge braided abyssal plain in the Labrador Sea (700 by 120 km underlain by 150 m on average of coarse- grained sediment) which is one of the largest sand accumulations (104 km3) on Earth. The facies of lofted sediment consists of stacked layers of graded muds that contain ice-rafted debris (IRD) which impart a bimodal grain-size distribution to the graded muds. The texturally incompatible grain populations of the muds (median size between 4 and 8 micrometers) and the randomly distributed coarse silt and sand-sized IRD require the combination of two transport processes that delivered the populations independently and allowed mixing at the depositional site: (i) sediment rafting by icebergs (dropstones) and (ii) the rise of turbid freshwater plumes out of fresh-water generated turbidity currents. Sediment lofting from turbidity currents is a process that occurs in density currents generated from sediment-laden fresh-water discharges into the sea that can produce reversed buoyancy, as is well known from experiments. When the flows have traveled long enough, their tops will have lost enough sediment by settling so that they become hypopycnal (their density decreasing below that of the ambient seawater) causing the current tops to lift up. The turbid fresh-water clouds buoyantly rise out of the turbidity current to a level of

  6. Can control of soil erosion mitigate water pollution by sediments?

    Science.gov (United States)

    Rickson, R J

    2014-01-15

    The detrimental impact of sediment and associated pollutants on water quality is widely acknowledged, with many watercourses in the UK failing to meet the standard of 'good ecological status'. Catchment sediment budgets show that hill slope erosion processes can be significant sources of waterborne sediment, with rates of erosion likely to increase given predicted future weather patterns. However, linking on-site erosion rates with off-site impacts is complicated because of the limited data on soil erosion rates in the UK and the dynamic nature of the source-pathway-receptor continuum over space and time. Even so, soil erosion control measures are designed to reduce sediment production (source) and mobilisation/transport (pathway) on hill slopes, with consequent mitigation of pollution incidents in watercourses (receptors). The purpose of this paper is to review the scientific evidence of the effectiveness of erosion control measures used in the UK to reduce sediment loads of hill slope origin in watercourses. Although over 73 soil erosion mitigation measures have been identified from the literature, empirical data on erosion control effectiveness are limited. Baseline comparisons for the 18 measures where data do exist reveal erosion control effectiveness is highly variable over time and between study locations. Given the limitations of the evidence base in terms of geographical coverage and duration of monitoring, performance of the different measures cannot be extrapolated to other areas. This uncertainty in effectiveness has implications for implementing erosion/sediment risk reduction policies, where quantified targets are stipulated, as is the case in the EU Freshwater Fish and draft Soil Framework Directives. Also, demonstrating technical effectiveness of erosion control measures alone will not encourage uptake by land managers: quantifying the costs and benefits of adopting erosion mitigation is equally important, but these are uncertain and difficult to

  7. Salinity Affects the Composition of the Aerobic Methanotroph Community in Alkaline Lake Sediments from the Tibetan Plateau.

    Science.gov (United States)

    Deng, Yongcui; Liu, Yongqin; Dumont, Marc; Conrad, Ralf

    2017-01-01

    Lakes are widely distributed on the Tibetan Plateau, which plays an important role in natural methane emission. Aerobic methanotrophs in lake sediments reduce the amount of methane released into the atmosphere. However, no study to date has analyzed the methanotroph community composition and their driving factors in sediments of these high-altitude lakes (>4000 m). To provide new insights on this aspect, the abundance and composition in the sediments of six high-altitude alkaline lakes (including both freshwater and saline lakes) on the Tibetan Plateau were studied. The quantitative PCR, terminal restriction fragment length polymorphism, and 454-pyrosequencing methods were used to target the pmoA genes. The pmoA gene copies ranged 10 4 -10 6 per gram fresh sediment. Type I methanotrophs predominated in Tibetan lake sediments, with Methylobacter and uncultivated type Ib methanotrophs being dominant in freshwater lakes and Methylomicrobium in saline lakes. Combining the pmoA-pyrosequencing data from Tibetan lakes with other published pmoA-sequencing data from lake sediments of other regions, a significant salinity and alkalinity effect (P = 0.001) was detected, especially salinity, which explained ∼25% of methanotroph community variability. The main effect was Methylomicrobium being dominant (up to 100%) in saline lakes only. In freshwater lakes, however, methanotroph composition was relatively diverse, including Methylobacter, Methylocystis, and uncultured type Ib clusters. This study provides the first methanotroph data for high-altitude lake sediments (>4000 m) and shows that salinity is a driving factor for the community composition of aerobic methanotrophs.

  8. Development of river sediment monitoring in Croatia

    Science.gov (United States)

    Frančišković-Bilinski, Stanislav; Bilinski, Halka; Mlakar, Marina; Maldini, Krešimir

    2017-04-01

    Establishment of regular river sediment monitoring, in addition to water monitoring, is very important. Unlike water, which represents the current state of a particular watercourse, sediment represents a sort of record of the state of pollution in the long run. Sediment monitoring is crucial to gain a real insight into the status of pollution of particular watercourses and to determine trends over a longer period of time. First scientific investigations of river sediment geochemistry in Croatia started 1989 in the Krka River estuary [1], while first systematic research of a river basin in Croatia was performed 2005 in Kupa River drainage basin [2]. Up to now, several detailed studies of both toxic metals and organic pollutants have been conducted in this drainage basin and some other rivers, also Croatian scientists participated in river sediment research in other countries. In 2008 Croatian water authorities (Hrvatske Vode) started preliminary sediment monitoring program, what was successfully conducted. In the first year of preliminary program only 14 stations existed, while in 2014 number of stations increased to 21. Number of monitored watercourses and of analysed parameters also increased. Current plan is to establish permanent monitoring network of river sediments throughout the state. The goal is to set up about 80 stations, which will cover all most important and most contaminated watercourses in all parts of the country [3]. Until the end of the year 2016, regular monitoring was conducted at 31 stations throughout the country. Currently the second phase of sediment monitoring program is in progress. At the moment parameters being determined on particular stations are not uniform. From inorganic compounds it is aimed to determine Cd, Pb, Ni, Hg, Cu, Cr, Zn and As on all stations. The ratio of natural concentrations of those elements vs. anthropogenic influence is being evaluated on all stations. It was found that worse situation is with Ni, Hg and Cr, who

  9. Hydrodynamics of sediment threshold

    Science.gov (United States)

    Ali, Sk Zeeshan; Dey, Subhasish

    2016-07-01

    A novel hydrodynamic model for the threshold of cohesionless sediment particle motion under a steady unidirectional streamflow is presented. The hydrodynamic forces (drag and lift) acting on a solitary sediment particle resting over a closely packed bed formed by the identical sediment particles are the primary motivating forces. The drag force comprises of the form drag and form induced drag. The lift force includes the Saffman lift, Magnus lift, centrifugal lift, and turbulent lift. The points of action of the force system are appropriately obtained, for the first time, from the basics of micro-mechanics. The sediment threshold is envisioned as the rolling mode, which is the plausible mode to initiate a particle motion on the bed. The moment balance of the force system on the solitary particle about the pivoting point of rolling yields the governing equation. The conditions of sediment threshold under the hydraulically smooth, transitional, and rough flow regimes are examined. The effects of velocity fluctuations are addressed by applying the statistical theory of turbulence. This study shows that for a hindrance coefficient of 0.3, the threshold curve (threshold Shields parameter versus shear Reynolds number) has an excellent agreement with the experimental data of uniform sediments. However, most of the experimental data are bounded by the upper and lower limiting threshold curves, corresponding to the hindrance coefficients of 0.2 and 0.4, respectively. The threshold curve of this study is compared with those of previous researchers. The present model also agrees satisfactorily with the experimental data of nonuniform sediments.

  10. FRESHWATER FISHERY OF THE REPUBLIC OF CROATIA

    Directory of Open Access Journals (Sweden)

    Zlatko Homen

    1999-09-01

    Full Text Available As fishery, including freshwater, is very important for economy of the Republic of Croatia, the aim of this paper is to show its condition from 1995 to 1998. and also to draw a plan for fish production in 1999. The period from 1998-1999. is more stressed in order to have a total and detailed view into the present condition of the freshwater fishery and into the direction in wish that production is going. Data about carp ponds and also about trout ponds is presented. Twentynine fish-ponds are processed out of which 20 are carp ponds and 9 trout ponds. Data was delivered to the Ministry of Agriculture and Forestry Fisheries Directorate. An assessment of the condition is made for 3 fish-ponds as the desired data was not provided. As to the number of employees on fish-ponds, a slight decline could be percived in the period from 1995 to 1997. In 1998 a number of employees considerably increased for 10.07% in relation to 1997. qualification of the employees in 1998. show that the most of them are unqualified what is in accord with the requirements of a job on a fish-pond. Overall surface of the carp ponds in 1998 was 12,708 and the production surface was 9,782 ha. The most of the fish-ponds have up to 500 ha of total surface (45.45%, while 50% of the fish-ponds have production surface from 500-100 ha. The production in the trout ponds is made on 165,905 m 2 of the overall surface of the ponds, and only 40,538 m 2 are the production surface of the ponds. The production of fish in that period was in constant increase and that increasing trend in expected in 1999, and it will be an 28.30 % increase in relation to 1998. The increase is expected for all kids of fish except for big head carps, silver carps and tinch fishs. As a part of the production of tinch fishs an increase in production of consumption tinch fish is expected, but a decrease in production of one-year and two-year old fishs and two-year old fish. Out of all kinds of fish, the most produced

  11. Endosulfan and its metabolite, endosulfan sulfate, in freshwater ecosystems of South Florida: a probabilistic aquatic ecological risk assessment.

    Science.gov (United States)

    Rand, Gary M; Carriger, John F; Gardinali, Piero R; Castro, Joffre

    2010-06-01

    Endosulfan is an insecticide-acaricide used in South Florida and is one of the remaining organochlorine insecticides registered under the Federal Insecticide Fungicide and Rodenticide Act by the U.S.EPA. The technical grade material consists of two isomers (alpha-, beta-) and the main environmental metabolite in water, sediment and tissue is endosulfan sulfate through oxidation. A comprehensive probabilistic aquatic ecological risk assessment was conducted to determine the potential risks of existing exposures to endosulfan and endosulfan sulfate in freshwaters of South Florida based on historical data (1992-2007). The assessment included hazard assessment (Tier 1) followed by probabilistic risk assessment (Tier 2). Tier 1 compared actual measured concentrations in surface freshwaters of 47 sites in South Florida from historical data to U.S.EPA numerical water quality criteria. Based on results of Tier 1, Tier 2 focused on the acute and chronic risks of endosulfan at nine sites by comparing distributions of surface water exposure concentrations of endosulfan [i.e., for total endosulfan (summation of concentrations of alpha- and beta-isomers plus the sulfate), alpha- plus beta-endosulfan, and endosulfan sulfate (alone)] with distributions of species effects from laboratory toxicity data. In Tier 2 the distribution of total endosulfan in fish tissue (whole body) from South Florida freshwaters was also used to determine the probability of exceeding a distribution of whole body residues of endosulfan producing mortality (critical lethal residues). Tier 1 showed the majority of endosulfan water quality violations in South Florida were at locations S-178 followed by S-177 in the C-111 system (southeastern boundary of Everglades National Park (ENP)). Nine surface water sampling sites were chosen for Tier 2. Tier 2 showed the highest potentially affected fraction of toxicity values (>10%) by the estimated 90th centile exposure concentration (total endosulfan) was at S-178

  12. Ecotoxicological Assessment of Sediment Leachates of Small Watercourses in the Brno City Suburban Area (South Moravia, Czech Republic

    Directory of Open Access Journals (Sweden)

    Miroslava Beklová

    2010-01-01

    Full Text Available Sediments of two small watercourses Leskava and Troubsky Brook in the Brno city suburban area were examined for their ecotoxicity. Using a standard procedure, extracts of the sediments were prepared for diagnostic tests. These extracts were tested for acute toxicity to fresh-water organisms. The ecotoxicological tests were performed on the fresh-water alga Pseudokirchneriella subcapitata, the vascular water plant Lemna minor, on a representative of invertebrates – the water flea Daphnia magna and on the Xenopus laevis frog embryo and luminiscent Vibrio fischeri bacteria. Possible toxic effects were evaluated using the test determining the inhibition of the growth of white mustard root Sinapis alba. Results of ecotoxicological assessment of sediment leachates showed that their quality varied significantly during the year. Differences were found between results of sediment evaluations from different collection profiles, which may indicate effects of point source pollution. Of the ecotoxicological tests used, the most sensitive organisms included the green algae Pseudokirchneriella subcapitata, bioluminiscent bacteria Vibrio fischeri and the African clawed frog Xenopus laevis. The highest concentrations of arsenic were found by chemical analysis in both spring and autumn sediment leachate samples collected at Site L1 (Leskava. The highest organic pollutant concentrations were found in autumn sediment leachate samples from Site L1. In total PAH sums, phenanthrene was the dominant pollutant at all the sites investigated.

  13. The effects of freshwater inflow, inlet conveyance and sea level rise on the salinity regime in the Loxahatchee Estuary

    International Nuclear Information System (INIS)

    Hu, G.

    2002-01-01

    The upstream migration of salt water into the historic freshwater reaches of the Loxahatchee River is the likely cause of the altered floodplain cypress forest community along the Northwest Fork and some of its tributaries. Mangroves are replacing cypress forest and areas of mixed swamp hardwoods have reacted to different degrees to the saltwater stress. A hydrodynamic/salinity model was developed to study the influence of freshwater input, tidal inlet deepening and sea level rise on the salinity regime in the estuary. Field data analysis and model simulations indicate that the salinity condition in the estuary is sensitive to the amount of freshwater input from the watershed. During dry seasons the salt front advances into areas that were historically freshwater habitats. Historic evidence indicates that the Loxahatchee estuary was periodically closed and opened to the sea. Due to the active long shore sediment transport, the tidal inlet was probably characterized by shifting sandbars through which ran a narrow and unstable channel. Inlet dredging in the past several decades has increased the hydraulic conveyance of the inlet and the tidal influence into the estuary. The sea level record from a site in south Florida indicates that the sea level has been rising at a rate of approximately 2.3-mm per year. The rise of sea level in the past century has probably raised the mean tide level by about 23 centimeters. If the sea level rise continues as predicted, it is foreseeable that the salt front will move further upstream along with the sea level rise. Field data analysis and the preliminary model output led us to believe that the advance of seawater up the estuary is the combined effect of watershed hydrological changes, inlet deepening and sea level rise. (author)

  14. Sedimentology and paleoenvironments of a new fossiliferous late Miocene-Pliocene sedimentary succession in the Rukwa Rift Basin, Tanzania

    Science.gov (United States)

    Mtelela, Cassy; Roberts, Eric M.; Hilbert-Wolf, Hannah L.; Downie, Robert; Hendrix, Marc S.; O'Connor, Patrick M.; Stevens, Nancy J.

    2017-05-01

    This paper presents a detailed sedimentologic investigation of a newly identified, fossiliferous Late Neogene sedimentary succession in the Rukwa Rift Basin, southwestern Tanzania. This synrift deposit is a rare and significant new example of a fossiliferous succession of this age in the Western Branch of East Africa Rift System. The unit, informally termed the lower Lake Beds succession, is late Miocene to Pliocene in age based on cross-cutting relationships, preliminary biostratigraphy, and U-Pb geochronology. An angular unconformity separates the lower Lake Beds from underlying Cretaceous and Oligocene strata. Deposition was controlled by rapid generation of accommodation space and increased sediment supply associated with late Cenozoic tectonic reactivation of the Rukwa Rift and synchronous initiation of the Rungwe Volcanic Centre. The lower Lake Beds, which have thus far only been identified in three localities throughout the Rukwa Rift Basin, are characterized by two discrete lithologic members (herein A and B). The lower Member A is a volcanic-rich succession composed mostly of devitrified volcanic tuffs, and volcaniclastic mudstones and sandstones with minor conglomerates. The upper Member B is a siliciclastic-dominated succession of conglomerates, sandstones, mudstones and minor volcanic tuffs. Detailed facies analysis of the lower Lake Beds reveals various distinctive depositional environments that can be grouped into three categories: 1) alluvial fan; 2) fluvial channel; and 3) flood basin environments, characterized by volcanoclastic-filled lakes and ponds, abandoned channel-fills and pedogenically modified floodplains. Member A represents a shallow lacustrine setting filled by tuffaceous sediments, which grade up into a system of alluvial fans and high-energy, proximal gravel-bed braided rivers. An unconformity marks the contact between the two members. Member B shows an upward transition from a high-energy, gravel-bed braided river system to a sandy

  15. Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh – a whole ecosystem 15N enrichment study

    Directory of Open Access Journals (Sweden)

    B. Gribsholt

    2007-01-01

    Full Text Available An intact tidal freshwater marsh system (3477 m2 was labelled by adding 15N-ammonium as a tracer to the flood water inundating the ecosystem. The appearance and retention of 15N-label in different marsh components (leaves, roots, sediment, leaf litter and invertebrate fauna was followed over 15 days. This allowed us to elucidate the direct assimilation and dependence on creek-water nitrogen on a relatively short term and provided an unbiased assessment of the relative importance of the various compartments within the ecosystem. Two separate experiments were conducted, one in spring/early summer (May 2002 when plants were young and building up biomass; the other in late summer (September 2003 when macrophytes were in a flowering or early senescent state. Nitrogen assimilation rate (per hour inundated was >3 times faster in May compared to September. On both occasions, however, the results clearly revealed that the less conspicuous compartments such as leaf litter and ruderal vegetations are more important in nitrogen uptake and retention than the prominent reed (Phragmites australis meadows. Moreover, short-term nitrogen retention in these nutrient rich marshes occurs mainly via microbial pathways associated with the litter and sediment. Rather than direct uptake by macrophytes, it is the large reactive surface area provided by the tidal freshwater marsh vegetation that is most crucial for nitrogen transformation, assimilation and short term retention in nutrient rich tidal freshwater marshes. Our results clearly revealed the dominant role of microbes in initial nitrogen retention in marsh ecosystems.

  16. Extinction rates in North American freshwater fishes, 1900-2010

    Science.gov (United States)

    Burkhead, Noel M.

    2012-01-01

    Widespread evidence shows that the modern rates of extinction in many plants and animals exceed background rates in the fossil record. In the present article, I investigate this issue with regard to North American freshwater fishes. From 1898 to 2006, 57 taxa became extinct, and three distinct populations were extirpated from the continent. Since 1989, the numbers of extinct North American fishes have increased by 25%. From the end of the nineteenth century to the present, modern extinctions varied by decade but significantly increased after 1950 (post-1950s mean = 7.5 extinct taxa per decade). In the twentieth century, freshwater fishes had the highest extinction rate worldwide among vertebrates. The modern extinction rate for North American freshwater fishes is conservatively estimated to be 877 times greater than the background extinction rate for freshwater fishes (one extinction every 3 million years). Reasonable estimates project that future increases in extinctions will range from 53 to 86 species by 2050.

  17. Epigean freshwater Gammaridae (Crustacea, Amphipoda) from La Gomera (Canary Islands)

    NARCIS (Netherlands)

    Beyer, Gabriele; Stock, Jan H.

    1994-01-01

    Description of two new species of freshwater amphipods from La Gomera (Canary Islands), both found in the higher parts of the island: Chaetogammarus chaetocerus n. sp. and Rhipidogammarus gomeranus n. sp. Both species have distinct Afro- Iberian relationships.

  18. New and interesting records of freshwater Verrucaria in Central Poland

    Directory of Open Access Journals (Sweden)

    Beata Krzewicka

    2013-12-01

    Full Text Available Verrucaria madida is reported as new to Poland. Three other associated species, V. aquatilis, V. hydrela and V. rheitrophila, are compared. The known distribution in Poland and the ecology of these freshwater species are presented.

  19. Book Review Guides to the Freshwater Invertebrates of Southern ...

    African Journals Online (AJOL)

    Book Review Guides to the Freshwater Invertebrates of Southern Africa. Volume 8: Insecta II. Hemiptera, Megaloptera, Neuroptera, Trichoptera and Lepidoptera By IJ de Moor, JA Day and FC de Moor (editors) 2003.

  20. Book Review Guides to the freshwater invertebrates of southern ...

    African Journals Online (AJOL)

    Book Review Guides to the freshwater invertebrates of southern Africa. Volume 2: Crustacea I. Notostraca, Anostraca, Conchostraca and Cladocera by JA Day, BA Stewart, IJ de Moor and AE Louw (Editors), December 1999.

  1. A NEW FRESHWATER GOBY (TELEOSTEI: GOBIIDAE) FROM THE ...

    African Journals Online (AJOL)

    497. JUDB, R. A. 1967. Freshwater fishes of southern Africa. Cape Town: Balkema. KOUMANS, F. P. 1931. A preliminary revision of the genera of the gobioidfishes with united ventral fins. N. V. Lisse. (Netherlands) 1-174: Drukkerij, Imperator. R.

  2. The freshwater biodegradation potential of nine Alaskan oils

    International Nuclear Information System (INIS)

    Blenkinsopp, S.; Segy, G.

    1997-01-01

    Nine Alaskan representative crude oils and oil products with freshwater spill potential were collected, aged, and incubated in the presence of the standard freshwater inoculum for 28 days at 10 degrees C. Detailed analytical chemistry was performed on all samples to quantify compositional changes. All of the samples tested exhibited measurable hydrocarbon loss as a result of incubation with the freshwater inoculum. Total saturate and total n-alkane biodegradation were greatly enhanced when nutrients were present. The oil products Jet B Fuel and Diesel No. 2 appear to be more biodegradable than the Alaska North Slope and Cook Inlet crude oils tested, while the Bunker C/Diesel mixture appears to be less biodegradable than these crude oils. These results suggest that the screening procedures described here can provide useful information when applying bioremediation technology to the cleanup of selected oiled freshwater environments. 10 refs., 5 tabs., 13 figs

  3. Bibliography on cycling of trace metals in freshwater ecosystems

    International Nuclear Information System (INIS)

    LaRiviere, M.G.; Scott, A.J.; Woodfield, W.G.; Cushing, C.E.

    1978-07-01

    This bibliography is a listing of pertinent literature directly addressing the cycling of trace metals in freshwater ecosystems. Data on cycling, including the influences of environmental mediators, are included. 151 references

  4. Bibliography on cycling of trace metals in freshwater ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    LaRiviere, M.G.; Scott, A.J.; Woodfield, W.G.; Cushing, C.E.

    1978-07-01

    This bibliography is a listing of pertinent literature directly addressing the cycling of trace metals in freshwater ecosystems. Data on cycling, including the influences of environmental mediators, are included. 151 references.

  5. Particle interactions during sedimentation

    Science.gov (United States)

    Michaelides, Efstathios; Xu, Zu-Jia

    2002-11-01

    The confined sedimentation process of two-dimensional particles with several initial configurations is numerically investigated at very low to moderate particle Reynolds numbers. The Lattice Boltzmann Method is used to simulate the hydrodynamic interactions between fluid and particles. We have found that, during the sedimentation process the displacement dispersion of particles in the horizontal direction fluctuates around zero, while the dispersion in the vertical direction increases monotonically and almost linearly. We also found that the increasing dispersion rate heavily depends on the initial layout and any symmetry of the suspension. The simulations for non-cohesive particles show that the process of sedimentation encompasses three stages: In the first stage, the initial particle configuration plays a major role on the average velocity of the particles. A V-shape or W-shape front may be formed by the particles close to that front. During the second stage, the concentration is lower, strong particle interactions dominate and the formation and destruction of particle clusters play a major role in the process. The sedimentation velocity depends to a large extend on the number of clusters formed and the velocity field developed. During the third stage, the suspension stretches, concentration becomes lower and particle clusters appear to be more stable. The wakes generated by individual particles and clusters, especially the wake of the leading cluster becomes very important in the process. Simulations were also performed with cohesive particles and we found out that the sedimentation process is essentially governed by the formation and size of flocs.

  6. Sedimentation problems and solutions

    International Nuclear Information System (INIS)

    Williams, D.T.

    1991-01-01

    Roseires Dam and reservoir are located in Sudan, Africa on the Blue Nile River. The hydropower from the reservoir provides approximately 80% of the power used in Sudan, thus having a tremendous economic impact on the country. The reservoir was first impounded in 1966 and has been filled annually since then. The Blue Nile has historically been known to carry heavy sediment loads which is associated with erosion from overgrazing in Ethiopia, the Blue Nile's headwaters. During the flood season, the dam's turbine intakes become blocked with debris and sediment. After a severe blockage in 1981, which prevented hydropower generation for several days, consultants from USAID were asked to make recommendations on reducing the sediment and debris impacts on reservoir operations. This led to debris clearing and dredging equipment acquisitions in 1982. In 1988, blockage occurred again during the flood season. This writer was asked by the World Bank to travel to Sudan, investigate the sediment and debris problems, examine the USAID recommendations, comment on potential sediment and debris problems associated with a proposed plan to raise the dam, make additional recommendations, and return to Sudan several times to determine the effectiveness of there recommendations. This paper discussed the results of the aforementioned activities and describes the new recommendations made by this writer

  7. The oceanic sediment barrier

    International Nuclear Information System (INIS)

    Francis, T.J.G.; Searle, R.C.; Wilson, T.R.S.

    1986-01-01

    Burial within the sediments of the deep ocean floor is one of the options that have been proposed for the disposal of high-level radioactive waste. An international research programme is in progress to determine whether oceanic sediments have the requisite properties for this purpose. After summarizing the salient features of this programme, the paper focuses on the Great Meteor East study area in the Northeast Atlantic, where most oceanographic effort has been concentrated. The geological geochemical and geotechnical properties of the sediments in the area are discussed. Measurements designed to determine the rate of pore water movement through the sediment column are described. Our understanding of the chemistry of both the solid and pore-water phases of the sediment are outlined, emphasizing the control that redox conditions have on the mobility of, for example, naturally occurring manganese and uranium. The burial of instrumented free-fall penetrators to depths of 30 m beneath the ocean floor is described, modelling one of the methods by which waste might be emplaced. Finally, the nature of this oceanic environment is compared with geological environments on land and attention is drawn to the gaps in our knowledge that must be filled before oceanic burial can be regarded as an acceptable disposal option. (author)

  8. Sedimentation, sediment quality, and upstream channel stability, John Redmond Reservoir, east-central Kansas, 1964-2009

    Science.gov (United States)

    Juracek, Kyle E.

    2010-01-01

    A combination of available bathymetric-survey information, bottom-sediment coring, and historical streamgage information was used to investigate sedimentation, sediment quality, and upstream channel stability for John Redmond Reservoir, east-central Kansas. Ongoing sedimentation is reducing the ability of the reservoir to serve several purposes including flood control, water supply, and recreation. The total estimated volume and mass of bottom sediment deposited between 1964 and 2009 in the conservation pool of the reservoir was 1.46 billion cubic feet and 55.8 billion pounds, respectively. The estimated sediment volume occupied about 41 percent of the conservation-pool, water-storage capacity of the reservoir. Water-storage capacity in the conservation pool has been lost to sedimentation at a rate of about 1 percent annually. Mean annual net sediment deposition since 1964 in the conservation pool of the reservoir was estimated to be 1.24 billion pounds per year. Mean annual net sediment yield from the reservoir basin was estimated to be 411,000 pounds per square mile per year Information from sediment cores shows that throughout the history of John Redmond Reservoir, total nitrogen concentrations in the deposited sediment generally were uniform indicating consistent nitrogen inputs to the reservoir. Total phosphorus concentrations in the deposited sediment were more variable than total nitrogen indicating the possibility of changing phosphorus inputs to the reservoir. As the principal limiting factor for primary production in most freshwater environments, phosphorus is of particular importance because increased inputs can contribute to accelerated reservoir eutrophication and the production of algal toxins and taste-and-odor compounds. The mean annual net loads of total nitrogen and total phosphorus deposited in the bottom sediment of the reservoir were estimated to be 2,350,000 pounds per year and 1,030,000 pounds per year, respectively. The estimated mean annual

  9. [Latin American malacology. Freshwater mollusks from Argentina].

    Science.gov (United States)

    Rumi, Alejandra; Gregoric, Diego E Gutiérrez; Núñez, Verónica; Darrigran, Gustavo A

    2008-03-01

    A report and an updated list with comments on the species of freshwater molluscs of Argentina which covers an area of 2 777 815 km2 is presented. Distributions of Gastropoda and Bivalvia families, endemic, exotic, invasive as well as entities of sanitary importance are also studied and recommendations on their conservation are provided. Molluscs related to the Del Plata Basin have been thoroughly studied in comparison to others areas of the country. This fauna exhibits relatively the biggest specific richness and keeps its affinity with the fauna of other regions of the basin in areas of Paraguay and Brasil. The 4 500 records of molluscs considered in this paper arise from the study of the collections of Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires; Museo de La Plata, La Plata and Fundación "Miguel Lillo", Tucumán. These institutions keep very important collections of molluscs in southern South America. Field information has recently been obtained and localities cited by other authors are also included in the data base. Until today, 166 species have been described, 101 belonging to 10 families of Gastropoda and 65 to 7 of Bivalvia. Families with highest specific richness are Lithoglyphidae (22) and Sphaeriidae (25), respectively. The number of endemic species (those present only in Argentina) by family is: Gastropoda: Ampullariidae (1), Cochliopidae (10), Lithoglyphidae (11), Thiariidae (3), Chilinidae (11), Lymnaeidae (2) and Physidae (2?); Bivalvia: Hyriidae (1?); Etheriidae (1?) and Sphaeriidae (10). Families with a distribution that comprise almost the whole country are: the Sphaeriidae and the gastropods Cochliopidae, Chilinidae and Lymnaeidae. Families Erodonidae and Solecurtidae (Bivalvia) were registered in mixohaline environments from Buenos Aires province. Gastropod families Thiaridae and Glacidorbiidae show a very restricted distribution. The rest of the families are present mainly in the center and north of the country

  10. Institutional development of freshwater fish stocking in Mexico.

    Science.gov (United States)

    Ibáñez, A L; Pérez-Ramírez, M; García-Calderón, J L

    2014-12-01

    By using freshwater fish stocking information from the Mexican government, this work described the current situation of the national stocking and its associated fishery policy. There is a lack of effective freshwater stocking programmes as a result of limited fisheries management, unharmonized fisheries regulations and institutional performance. The fry production has decreased from 140 to 20 million in the past 11 years. © 2014 The Fisheries Society of the British Isles.

  11. Rapid screening of operational freshwater availability using global models

    OpenAIRE

    Straatsma, M.W.; Vermeulen, P.; Kuijper, Marijn; Bonte, Matthijs; Niele, Frank; Bierkens, M.F.P.

    2016-01-01

    Freshwater shortage already affects large parts of the world, and is expected to increase rapidly over the coming decades as a result of increased water demands and the impacts of climate change. Global-scale water risk or stress maps are available online, but these lack quantitative information on local freshwater availability, rendering them unsuitable for water risk assessment from an operational perspective, i.e. when comparing water availability to a specific quantified water demand (in ...

  12. Biodiversity and distribution of polar freshwater DNA viruses

    OpenAIRE

    Aguirre de C?rcer, Daniel; L?pez-Bueno, Alberto; Pearce, David A.; Alcam?, Antonio

    2015-01-01

    Viruses constitute the most abundant biological entities and a large reservoir of genetic diversity on Earth. Despite the recent surge in their study, our knowledge on their actual biodiversity and distribution remains sparse. We report the first metagenomic analysis of Arctic freshwater viral DNA communities and a comparative analysis with other freshwater environments. Arctic viromes are dominated by unknown and single-stranded DNA viruses with no close relatives in the database. These uniq...

  13. Restricted-range fishes and the conservation of Brazilian freshwaters.

    Directory of Open Access Journals (Sweden)

    Cristiano Nogueira

    Full Text Available BACKGROUND: Freshwaters are the most threatened ecosystems on earth. Although recent assessments provide data on global priority regions for freshwater conservation, local scale priorities remain unknown. Refining the scale of global biodiversity assessments (both at terrestrial and freshwater realms and translating these into conservation priorities on the ground remains a major challenge to biodiversity science, and depends directly on species occurrence data of high taxonomic and geographic resolution. Brazil harbors the richest freshwater ichthyofauna in the world, but knowledge on endemic areas and conservation in Brazilian rivers is still scarce. METHODOLOGY/PRINCIPAL FINDINGS: Using data on environmental threats and revised species distribution data we detect and delineate 540 small watershed areas harboring 819 restricted-range fishes in Brazil. Many of these areas are already highly threatened, as 159 (29% watersheds have lost more than 70% of their original vegetation cover, and only 141 (26% show significant overlap with formally protected areas or indigenous lands. We detected 220 (40% critical watersheds overlapping hydroelectric dams or showing both poor formal protection and widespread habitat loss; these sites harbor 344 endemic fish species that may face extinction if no conservation action is in place in the near future. CONCLUSIONS/SIGNIFICANCE: We provide the first analysis of site-scale conservation priorities in the richest freshwater ecosystems of the globe. Our results corroborate the hypothesis that freshwater biodiversity has been neglected in former conservation assessments. The study provides a simple and straightforward method for detecting freshwater priority areas based on endemism and threat, and represents a starting point for integrating freshwater and terrestrial conservation in representative and biogeographically consistent site-scale conservation strategies, that may be scaled-up following naturally linked

  14. Acute toxicity of vanadium to two species of freshwater fish

    Energy Technology Data Exchange (ETDEWEB)

    Knudtson, B.K.

    1979-09-01

    Goldfish (Carassius auratus) and guppies (Lebistes reticulatus) were the two freshwater, thermophilous fishes chosen for use in this study. These species were selected for the following reasons: (1) low cost/individual, (2) ready availability, (3) ease of care and handling, (4) suspected differences between the two species in their responses to this metal, and (5) the usefulness of both as generalized models for the response of freshwater and marine fishes to vanadium.

  15. Metal impacts on microbial biomass in the anoxic sediments of a contaminated lake

    Energy Technology Data Exchange (ETDEWEB)

    Gough, Heidi L.; Dahl, Amy L.; Nolan, Melissa A.; Gaillard, Jean-Francois; Stahl, David A.

    2008-04-26

    Little is known about the long-term impacts of metal contamination on the microbiota of anoxic lake sediments. In this study, we examined microbial biomass and metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sediments of Lake DePue, a backwater lake located near a former zinc smelter. Sediment core samples were examined using two independent measures for microbial biomass (total microscopic counts and total phospholipid-phosphate concentrations), and for various fractions of each metal (pore water extracts, sequential extractions, and total extracts of all studied metals and zinc speciation by X-ray absorption fine structure (XAFS). Zinc concentrations were up to 1000 times higher than reported for sediments in the adjacent Illinois River, and ranged from 21,400 mg/kg near the source to 1,680 mg/kg near the river. However, solid metal fractions were not well correlated with pore water concentrations, and were not good predictors of biomass concentrations. Instead, biomass, which varied among sites by as much as two-times, was inversely correlated with concentrations of pore water zinc and arsenic as established by multiple linear regression. Monitoring of other parameters known to naturally influence biomass in sediments (e.g., organic carbon concentrations, nitrogen concentrations, pH, sediment texture, and macrophytes) revealed no differences that could explain observed biomass trends. This study provides strong support for control of microbial abundance by pore water metal concentrations in contaminated freshwater sediments.

  16. Reactive silica fractions in coastal lagoon sediments from the northern Gulf of Mexico

    Science.gov (United States)

    Krause, Jeffrey W.; Darrow, Elizabeth S.; Pickering, Rebecca A.; Carmichael, Ruth H.; Larson, Ashley M.; Basaldua, Jose L.

    2017-12-01

    Continental-margin sediments account for 50% of the oceanic biogenic silica burial despite covering < 10% of its area. In Mississippi Sound, a coastal lagoon in the northern Gulf of Mexico (nGoM), we measured sediment biogenic silica at sites removed from major freshwater discharge sources using the traditional method and a method that has been modified for deltaic systems to quantify other reactive silica pools, specifically those involved in the process of reverse weathering. The magnitude of authigenically-altered biogenic silica during our study was significant and represented, on average, 33% of the total sediment biogenic silica among core depths and sites. Additionally, there was a significant relationship between the degree to which the biogenic silica pool was authigenically altered and the source of the sediment organic matter, with lower modification in sediments corresponding with higher terrestrial organic matter. We observed no positive correlation between the magnitude of authigenic modification and sediment clay content. Thus, our findings suggest that these processes may occur within a variety of sediment compositions and add to a growing body of evidence suggesting that reverse weathering of silica in coastal systems is a significant pathway in the global silica budget.

  17. Hydrology and Ecology of Freshwater Wetlands in Central Florida - A Primer

    Science.gov (United States)

    Haag, Kim H.; Lee, Terrie M.

    2010-01-01

    how wetlands are affected by human activities. Freshwater wetlands are unique and complex ecosystems defined by characteristic properties. Wetlands usually have standing water during at least part of the year, although water depths can vary from a few inches to as much as several feet from one wetland to another. The hydrologic behavior of wetlands is influenced by drainage basin characteristics, as well as by natural variations in climate. Wetlands in central Florida (especially forested wetlands) often have acidic waters that are darkly stained from organic substances released by decomposing leaves and other plant material. Wetlands are characterized by biogeochemical cycles in which vital elements such as carbon, nitrogen, phosphorus, and others are transformed as they move between wetland soils and sediments, the open water, and the atmosphere. Wetlands are populated with plants that can thrive under conditions of saturated soils and low dissolved-oxygen concentrations. The bottoms of many wetlands, especially marshes, are covered with decayed plant material that can accumulate over time to form brown peat or black muck soils. Wetlands are inhabited by animals that need standing water to complete some or all of their life cycles, and they also provide periodic food, water, and shelter for many other animals that spend most of their lives on dry land. The complex and interrelated components of wetlands directly affect one another and there are numerous feedback mechanisms.

  18. Determination of trace elements in freshwater diatoms by neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nagatsuka, S.; Tanizaki, Y.; Yamazaki, M. (Tokyo Metropolitan Isotope Research Center (Japan))

    1982-02-01

    The instrumental neutron activation analysis was applied to the multielemental analysis of the freshwater diatoms taken from the head and the lower areas of Tama river. Dry samples of the diatoms were irradiated for 1 minute (for the measurement of short lived nuclides) by pneumatic tube of TRIGA-II reactor of Musashi Institute of Technology, and 12 hours (for the measurement of long lives nuclides) in F ring of TRIGA-II reactor of Rikkyo University. The analytical results of 20 elements in the samples were obtained, and the concentration of Ti showed high values in all the sample. Since it is considered that Ti is absent in algae, these high values indicate that appreciable amounts of river sediment were contained in the samples. Therefore, the analytical results were corrected for Ti contents in the samples. The concentrations of Mg, K, Zn, Mn and Co in the diatoms showed no difference between the two sampling points. The concentrations of Cr, V, As and Sb in the diatoms, however, showed difference between the two sampling points, depending on the river water quality. In Stenopsyche grisepennis, on the other hand, the concentrations of Mn and Co depend on the river water quality, and the concentrations of Cr depend on the amount of diatoms staying in the body. The concentrations of V, As and Sb in the Stenopsyche griseipennis are considered to depend both on the amount of diatoms and river sediment staying in the body.

  19. Contrasts between the marine and freshwater biological interactions of plutonium and americium

    International Nuclear Information System (INIS)

    Livingston, H.D.; Bowen, V.T.

    1975-01-01

    Whether in lakes or the oceans the transuranic elements plutonium and americium are taken up by marine organisms, with concentration factors that would class them as nice, typical heavy metals. There is no evidence for strong, widespread discrimination against the transuranics by either plant or animal absorptive surfaces. In both freshwater and marine situations the major reservoir of Pu and Am soon becomes the sediments, and organisms are more exposed to uptake of these nuclides the closer is their ecological involvement with the sediments. Although there is little evidence that this can be an ionic strength effect, it does appear that Pu may be somewhat more available, biologically, in marine environments, and Am, conversely, in fresh water. We incline to the belief that details of these behaviors are usually controlled by local availability of organic complexers. No compelling evidence exists of increase in Pu concentration at higher levels of food chains; in marine situations this appears true of Am as well, but a few data suggest that in fresh water fish there is a progressive increase, in higher trophic levels, in the ratio Am to Pu. Although marine and fresh water biogeochemistries of transuranics are much more similar than we had expected, it will generally be dangerous to extrapolate from one to the other. In both systems there appears to us no question that we are observing real element biogeochemistry, not the redistribution of inert, labelled, fallout fragments

  20. Complementary nontargeted and targeted mass spectrometry techniques to determine bioaccumulation of halogenated contaminants in freshwater species.

    Science.gov (United States)

    Myers, Anne L; Watson-Leung, Trudy; Jobst, Karl J; Shen, Li; Besevic, Sladjana; Organtini, Kari; Dorman, Frank L; Mabury, Scott A; Reiner, Eric J

    2014-12-02

    Assessing the toxicological significance of complex environmental mixtures is challenging due to the large number of unidentified contaminants. Nontargeted analytical techniques may serve to identify bioaccumulative contaminants within complex contaminant mixtures without the use of analytical standards. This study exposed three freshwater organisms (Lumbriculus variegatus, Hexagenia spp., and Pimephales promelas) to a highly contaminated soil collected from a recycling plant fire site. Biota extracts were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and mass defect filtering to identify bioaccumulative halogenated contaminants. Specific bioaccumulative isomers were identified by comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry (GCxGC-HRToF). Targeted analysis of mixed brominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PXDD/PXDFs, X = Br and Cl) was performed by atmospheric pressure gas chromatography tandem mass spectrometry (APGC-MS/MS). Relative sediment and biota instrument responses were used to estimate biota-sediment accumulation factors (BSAFs). Bioaccumulating contaminants varied among species and included polychlorinated naphthalenes (PCNs), polychlorinated dibenzofurans (PCDFs), chlorinated and mixed brominated/chlorinated anthracenes/phenanthrenes, and pyrenes/fluoranthenes (Cl-PAHs and X-PAHs, X = Br and Cl), as well as PXDD/PXDFs. Bioaccumulation potential among isomers also varied. This study demonstrates how complementary high-resolution mass spectrometry techniques identify persistent and bioaccumulative contaminants (and specific isomers) of environmental concern.

  1. Restoration and Management of a Degraded Baldcypress Swamp and Freshwater Marsh in Coastal Louisiana

    Directory of Open Access Journals (Sweden)

    Rachael G. Hunter

    2016-02-01

    Full Text Available The Central Wetlands Unit (CWU, covering 12,000 hectares in St. Bernard and Orleans Parishes, Louisiana, was once a healthy baldcypress–water tupelo swamp and fresh and low salinity marsh before construction of levees isolated the region from Mississippi River floodwaters. Construction of the Mississippi River Gulf Outlet (MRGO, which funneled saltwater inland from the Gulf of Mexico, resulted in a drastic ecosystem change and caused mortality of almost all trees and low salinity marsh, but closure of the MRGO has led to decreases in soil and surface water salinity. Currently, the area is open water, brackish marsh, and remnant baldcypress stands. We measured hydrology, soils, water and sediment chemistry, vegetation composition and productivity, accretion, and soil strength to determine relative health of the wetlands. Vegetation species richness is low and above- and belowground biomass is up to 50% lower than a healthy marsh. Soil strength and bulk density are low over much of the area. A baldcypress wetland remains near a stormwater pumping station that also has received treated municipal effluent for about four decades. Based on the current health of the CWU, three restoration approaches are recommended, including: (1 mineral sediment input to increase elevation and soil strength; (2 nutrient-rich fresh water to increase productivity and buffer salinity; and (3 planting of freshwater forests, along with fresh and low salinity herbaceous vegetation.

  2. Electromagnetic methods for mapping freshwater lenses on Micronesian atoll islands

    Science.gov (United States)

    Anthony, S.S.

    1992-01-01

    The overall shape of freshwater lenses can be determined by applying electromagnetic methods and inverse layered-earth modeling to the mapping of atoll island freshwater lenses. Conductivity profiles were run across the width of the inhabited islands at Mwoakilloa, Pingelap, and Sapwuahfik atolls of the Pohnpei State, Federated States of Micronesia using a dual-loop, frequency-domain, electromagnetic profiling system. Six values of apparent conductivity were recorded at each sounding station and were used to interpret layer conductivities and/or thicknesses. A three-layer model that includes the unsaturated, freshwater, and saltwater zones was used to simulate apparent-conductivity data measured in the field. Interpreted results were compared with chloride-concentration data from monitoring wells and indicate that the interface between freshwater and saltwater layers, defined from electromagnetic data, is located in the upper part of the transition zone, where the chloride-concentration profile shows a rapid increase with depth. The electromagnetic method can be used to interpret the thickness of the freshwater between monitoring wells, but can not be used to interpret the thickness of freshwater from monitoring wells to the margin of an island. ?? 1992.

  3. Bioaccumulation factors for radionuclides in freshwater biota

    International Nuclear Information System (INIS)

    Vanderploeg, H.A.; Parzyck, D.C.; Wilcox, W.H.; Kercher, J.R.; Kaye, S.V.

    1975-11-01

    This report analyzes over 200 carefully selected papers to provide concise data sets and methodology for estimation of bioaccumulation factors for tritium and isotopes of strontium, cesium, iodine, manganese, and cobalt in major biotic components of freshwater environments. Bioaccumulation factors of different tissues are distinguished where significant differences occur. Since conditions in the laboratory are often unnatural in terms of chemical and ecological relationships, this review was restricted as far as possible to bioaccumulation factors determined for natural systems. Because bioaccumulation factors were not available for some shorter-lived radionuclides, a methodology for converting bioaccumulation factors of stable isotopes to those of shorter-lived radionuclides was derived and utilized. The bioaccumulation factor for a radionuclide in a given organism or tissue may exhibit wide variations among bodies of water that are related to differences in ambient concentrations of stable-element and carrier-element analogues. To account for these variations, simple models are presented that relate bioaccumulation factors to stable-element and carrier-element concentrations in water. The effects of physicochemical form and other factors in causing deviations from these models are discussed. Bioaccumulation factor data are examined in the context of these models, and bioaccumulation factor relations for the selected radionuclides are presented

  4. Title: Freshwater phytoplankton responses to global warming.

    Science.gov (United States)

    Wagner, Heiko; Fanesi, Andrea; Wilhelm, Christian

    2016-09-20

    Global warming alters species composition and function of freshwater ecosystems. However, the impact of temperature on primary productivity is not sufficiently understood and water quality models need to be improved in order to assess the quantitative and qualitative changes of aquatic communities. On the basis of experimental data, we demonstrate that the commonly used photosynthetic and water chemistry parameters alone are not sufficient for modeling phytoplankton growth under changing temperature regimes. We present some new aspects of the acclimation process with respect to temperature and how contrasting responses may be explained by a more complete physiological knowledge of the energy flow from photons to new biomass. We further suggest including additional bio-markers/traits for algal growth such as carbon allocation patterns to increase the explanatory power of such models. Although carbon allocation patterns are promising and functional cellular traits for growth prediction under different nutrient and light conditions, their predictive power still waits to be tested with respect to temperature. A great challenge for the near future will be the prediction of primary production efficiencies under the global change scenario using a uniform model for phytoplankton assemblages. Copyright © 2016 Elsevier GmbH. All rights reserved.

  5. Photosynthetic carbon metabolism in freshwater phytoplankton

    International Nuclear Information System (INIS)

    Groeger, A.W.

    1986-01-01

    Photosynthetic carbon metabolism of natural assemblages of freshwater phytoplankton was measured by following the flow of inorganic 14 C into the photosynthetic end products polysaccharide protein, lipid, and soluble metabolites. Data were collected from a wide range of physical, chemical, and trophic conditions in six southern United States reservoirs, with the primary environmental variables of interest being light intensity and nutrient supply. Polysaccharide and protein were consistently the primary products of photosynthetic carbon metabolism, comprising an average of 70% of the total carbon fixation over a wide range of light intensities. Polysaccharide was quantitatively more important at higher light intensities, and protein at lower light intensities, as light intensity varied both with depth within the water column and over diurnal cycles. Polysaccharide synthesis was more variable over the diurnal period than was protein synthesis. Phytoplankton in the downlake epilimnion of Normandy Lake, a central Tennessee reservoir, responded to summer nitrogen (N) deficiency by increasing relative rates of lipid synthesis from 10-15% to 20-25% of the total photosynthetic carbon fixation. Phytoplankton in more nitrogen-sufficient areas of the reservoir maintained lower rates of lipid synthesis throughout the summer. These results document the occurrence in nature of a relationship between N-deficiency and increased lipid synthesis previously observed only in laboratory algal culture studies

  6. Some nematodes of freshwater fishes in Venezuela.

    Science.gov (United States)

    Moravec, F; Prouza, A; Royero, R

    1997-01-01

    The present paper comprises a systematic survey of nematodes found in 88 specimens of 24 species of freshwater fishes in Venezuela in 1992 and 1994. The following 13 species of nematodes were recorded: Adults; Guyanema longispiculum Moravec, Prouza et Royero, 1996, Guyanema sp., Procamallanus (Spirocamallanus) inopinatus Travassos, Artigas et Pereira, 1928, P. (S.) krameri (Petter, 1974) comb. n., P.(S.) pintoi (Kohn et Fernandes, 1988) comb, n., Procamallanus (Spirocamallanus) sp., Raphidascaris (Sprentascaris) mahnerti (Petter et Cassone, 1984). Larvae: Anisakidae gen. sp., Brevimulticaecum sp., Contracaecum sp. Type 1, Contracaecum sp. Type 2, Contracaecum sp. Type 3, Eustrongylides sp. All these parasites are reported from Venezuela for the first time and all findings represent new host records. Brevimulticaecum larvae are reported from fishes for the first time. Almost all parasites are briefly described and illustrated and problems concerning their morphology, taxonomy, hosts and geographical distribution are discussed. A new name, Terranova diazungriai nom.nov. is proposed for T. caballeroi Díaz-Ungría, 1968 (a junior homonym of T. caballeroi Barus et Coy Otero, 1966).

  7. Cyanobacteria and cyanotoxins in freshwaters of Uruguay

    Directory of Open Access Journals (Sweden)

    Sylvia Bonilla

    2015-12-01

    Full Text Available Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associated with eutrophication (nutrient enrichment and changes in hydrology. In this study we analysed the distribution of planktonic cyanobacteria in Uruguay and their toxins (microcystin, saxitoxin and cylindrospermopsin, working with an interagency team (OSE, DINAMA, IM, University of the Republic and IIBCE. An historical data base (n = 3061 for 64 ecosystems, years 1980-2014 was generated. Differences between lotic and lentic ecosystems were found in terms of chlorophyll a and nutrient concentrations, usually indicating eutrophication. Two geo-referenced maps for the country were generated with cyanobacteria biomass indicators and the most relevant toxin (microcystin, according to risk levels suggested by the World Health Organization for recreational waters. The areas of greatest risk of exposure were the reservoirs of large rivers (Uruguay and Río Negro and Río de la Plata beaches. In the second part of the study, up to 20 mg L-1of microcystin was quantified in bloom (scum samples, as well as the presence of genes that suggest more microcystin varieties, potentially with greater toxicity. This study provides basic information about the distribution of cyanobacteria in Uruguayan freshwaters that will be useful for national monitoring programs and scientific research.

  8. Investigation of strength properties of freshwater ice

    Directory of Open Access Journals (Sweden)

    Bragov A.

    2015-01-01

    Full Text Available A study of the strength and deformation properties of freshwater ice under compression, tension and shear in a wide range of strain rates (10−4 − 3 ⋅ 103 s−1 and temperatures of − 5∘ C, − 20∘ C, − 40∘ C and − 60∘ C was performed. Static stress-strain curves of ice under compression were obtained on which the identified strength properties of ice as well as compressive modulus. To determine the mechanical properties of ice at high-speed loading the Kolsky method was used with various embodiments of split Hopkinson bar. The deformation curves were obtained at various loading conditions. Thereon breaking points were defined as well as their dependence on the strain rate and temperature. Also static and dynamic strength properties of ice at splitting and circular shear were defined. Increase in the dynamic strength properties upon the static ones for all loading conditions was marked.

  9. Sediment transport mechanics

    Science.gov (United States)

    Ballio, Francesco; Tait, Simon

    2012-12-01

    The Editor of Acta Geophysica and the Guest Editors wish to dedicate this Topical Issue on Sediment Transport Mechanics to the memory of Stephen Coleman, who died recently. During his career, Stephen had made an outstanding scientific contribution to the topic of Sediment Transport. The level of his contribution is demonstrated in the paper by Aberle, Coleman, and Nikora included in this issue, on which he started working before becoming aware of the illness that led to his untimely death. For scholars and colleagues Stephen remains an example of intellectual honesty and scientific insight.

  10. Ascorbic Acid Biosynthesis and Brackish Water Acclimation in the Euryhaline Freshwater White-Rimmed Stingray, Himantura signifer.

    Directory of Open Access Journals (Sweden)

    Samuel Z H Wong

    Full Text Available L-gulono-γ-lactone oxidase (Gulo catalyzes the last step of ascorbic acid biosynthesis, which occurs in the kidney of elasmobranchs. This study aimed to clone and sequence gulonolactone oxidase (gulo from the kidney of the euryhaline freshwater stingray, Himantura signifer, and to determine the effects of acclimation from freshwater to brackish water (salinity 20 on its renal gulo mRNA expression and Gulo activity. We also examined the effects of brackish water acclimation on concentrations of ascorbate, dehydroascorbate and ascorbate + dehydroascorbate in the kidney, brain and gill. The complete cDNA coding sequence of gulo from the kidney of H. signifer contained 1323 bp coding for 440 amino acids. The expression of gulo was kidney-specific, and renal gulo expression decreased significantly by 67% and 50% in fish acclimated to brackish water for 1 day and 6 days, respectively. There was also a significant decrease in renal Gulo activity after 6 days of acclimation to brackish water. Hence, brackish water acclimation led to a decrease in the ascorbic acid synthetic capacity in the kidney of H. signifer. However, there were significant increases in concentrations of ascorbate and ascorbate + dehydroascorbate in the gills (after 1 or 6 days, and a significant increase in the concentration of ascorbate and a significant decrease in the concentration of dehydroascorbate in the brain (after 1 day of fish acclimated to brackish water. Taken together, our results indicate that H. signifer might experience greater salinity-induced oxidative stress in freshwater than in brackish water, possibly related to its short history of freshwater invasion. These results also suggest for the first time a possible relationship between the successful invasion of the freshwater environment by some euryhaline marine elasmobranchs and the ability of these elasmobranchs to increase the capacity of ascorbic acid synthesis in response to hyposalinity stress.

  11. Soft-sediment mullions

    Science.gov (United States)

    Ortner, Hugo

    2015-04-01

    In this contribution I describe the appearance, formation and significance of soft-sediment mullions. I use several examples from synorogenic turbidites of the Alps and the Pyrenees to show their appearance in the field. Soft-sediment mullions are elongate, slightly irregular bulges at the base of coarse-grained clastic beds (sand to conglomerate), separated by narrow, elongate flames of fine-grained material (mud) protruding into the coarse-grained bed. Various processes may lead to the formation of such structures: (1) longitudinal furrows parallel to the sediment transport direction may form by spiral motion in flow rolls during sediment transport (Dzulinski, 1966; Dzulinski & Simpson, 1966). (2) Loading combined with downslope movement can produce elongate structures parallelling the dowslope direction (Anketell et al., 1970). (3) Soft-sediment mullions are oriented perpendicular or oblique to the downslope direction, and show evidence of bedding-parallel shortening. Thus, they resemble cuspate-lobate folds or mullions, which are well-known in ductile structural geology (e.g. Urai et al., 2001). Soft-sediment mullions have been observed in two cases: Either bedding-parallel shortening can be achieved by slump processes, or by active tectonic shortening. Slumping is characterized by an alternation of stretching and shortening (e.g. Ortner, 2007; Alsop & Marco 2014), and therefore mullions do overprint or are overprinted by normal faults. In active depositional systems that are subject to tectonic shortening growth strata will form, but sediments already deposited will be shortened during lithification. In some cases, the formation of soft-sediment mullions predates folding, but the most widespread expression of syn-lithification shortening seems to be soft-sediment mullions, that form in the inner arcs of fold hinges. In the examples documented so far, the size of soft-sediment mullions is dependent on the grain-size of the coarse-grained layer, in which the

  12. Limnology of freshwater lakes of Schirmacher Oasis, East Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Parulekar, A.H.

    taxonomic groups with minimum and maximum faunal density of 43 and 823 individuals in 10 cm/2 respectively was recorded from covered and uncovered sediments. Faunal density showed a strong correlation with organic carbon content and the sediment texture...

  13. Benthic Bacterial Community Composition in the Oligohaline-Marine Transition of Surface Sediments in the Baltic Sea Based on rRNA Analysis

    Directory of Open Access Journals (Sweden)

    Julia Klier

    2018-02-01

    Full Text Available Salinity has a strong impact on bacterial community composition such that freshwater bacterial communities are very different from those in seawater. By contrast, little is known about the composition and diversity of the bacterial community in the sediments (bacteriobenthos at the freshwater-seawater transition (mesohaline conditions. In this study, partial 16S-rRNA sequences were used to investigate the bacterial community at five stations, representing almost freshwater (oligohaline to marine conditions, in the Baltic Sea. Samples were obtained from the silty, top-layer (0–2.5 cm sediments with mostly oxygenated conditions. The long water residence time characteristic of the Baltic Sea, was predicted to enable the development of autochthonous bacteriobenthos at mesohaline conditions. Our results showed that, similar to the water column, salinity is a major factor in structuring the bacteriobenthos and that there is no loss of bacterial richness at intermediate salinities. The bacterial communities of marine, mesohaline, and oligohaline sediments differed in terms of the relative rRNA abundances of the major bacterial phyla/classes. At mesohaline conditions typical marine and oligohaline operational taxonomic units (OTUs were abundant. Putative unique OTUs in mesohaline sediments were present only at low abundances, suggesting that the mesohaline environment consists mainly of marine and oligohaline bacteria with a broad salinity tolerance. Our study provides a first overview of the diversity patterns and composition of bacteria in the sediments along the Baltic Sea salinity gradient as well as new insights into the bacteriobenthos at mesohaline conditions.

  14. Sediments of a retting yard

    Digital Repository Service at National Institute of Oceanography (India)

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

    Sediments of a coconut husk retting yard and a reference station in Cochin backwaters, Kerala, India were studied for 1 yr. Effects of monsoon were found significant Organic carbon and organic matter showed enrichment in the retting ground sediments...

  15. Electrodialytic remediation of sediments

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland

    , in many cases, prohibit this due to contamination by primarily heavy metals and TBT. Similarly, sediments of fresh waters could potentially be used as soil amendment material for poor agricultural soils utilizing their often high content of phosphate and nitrogen. However, again, heavy metal contamination...

  16. Soils and organic sediments

    Energy Technology Data Exchange (ETDEWEB)

    Head, M.J. [University of Wollongong, Wollongong, NSW (Australia). School of Geosciences

    1999-11-01

    The organic component of soils is basically made up of substances of an individual nature (fats, waxes, resins, proteins, tannic substances, and many others), and humic substances (Kononova, 1966). These are complex polymers formed from breakdown products of the chemical and biological degradation of plant and animal residues. They are dark coloured, acidic, predominantly aromatic compounds ranging in molecular weight from less than one thousand to tens of thousands (Schnitzer, 1977). They can be partitioned into three main fractions:(i) Humic acid, which is soluble in dilute alkaline solution, but can be precipitated by acidification of the alkaline extract.(ii) Fulvic acid, which is soluble in alkaline solution, but is also soluble on acidification.(iii) Humin that cannot be extracted from the soil or sediment by dilute acid or alkaline solutions. It has mostly been assumed that the humic and fulvic acid components of the soil are part of the mobile, or `active` component, and the humin component is part of the `passive` component. Other types of organic sediments are likely to contain chemical breakdown products of plant material, plant fragments and material brought in from outside sources. The outside material can be contemporaneous with sediment deposition, can be older material, or younger material incorporated into the sediment long after deposition. Recognition of `foreign` material is essential for dating, but is not an easy task. Examples of separation techniques for humic and non humic components are evaluated for their efficiency 18 refs.

  17. Dynamics of Cohesive Sediments

    DEFF Research Database (Denmark)

    Johansen, Claus

    to the erosion, deposition, settling velocity and consolidation of cohesive sediments. All experiments were evaluated considering the reproducibility of the individual experiments. The erosion and deposition experiments were conducted in a circular flume. The measurements of the settling velocity were carried...

  18. Mercury Content of Sediments in East Fork Poplar Creek: Current Assessment and Past Trends

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Scott C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eller, Virginia A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dickson, Johnbull O. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Earles, Jennifer E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lowe, Kenneth Alan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mehlhorn, Tonia L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Olsen, Todd A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); DeRolph, Christopher R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Watson, David J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Phillips, Debra H. [Queen' s Univ., Belfast (United Kingdom); Peterson, Mark J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-01-01

    This study provided new information on sediment mercury (Hg) and monomethylmercury (MMHg) content and chemistry. The current inventory of Hg in East Fork Poplar Creek (EFPC) bed sediments was estimated to be 334 kg, which represents a ~67% decrease relative to the initial investigations in 1984. MMHg sediment inventory was estimated to be 44.1 g, lower but roughly similar to past estimates. The results support the relevance and potential impacts of other active and planned investigations within the Mercury Remediation Technology Development for Lower East Fork Poplar Creek project (e.g., assessment and control of bank soil inputs, sorbents for Hg and MMHg removal, re-introduction of freshwater clams to EFPC), and identify gaps in current understanding that represent opportunities to understand controlling variables that may inform future technology development studies.

  19. Distribution and assessment of heavy metal toxicity in sediment cores from Bizerte Lagoon, Tunisia.

    Science.gov (United States)

    Mna, Haïfa Ben; Oueslati, Walid; Helali, Mohamed Amine; Zaaboub, Noureddine; Added, Ayed; Aleya, Lotfi

    2017-07-01

    To examine the state of pollution of Bizerte Lagoon which is exposed to intense anthropogenic pressure, two sediment cores were taken at two sites, one undergoes the dual effects of both marine waters arriving from the Mediterranean Sea through the Channel, and also of freshwater from the Tinja River; the other core is located at the center of the lagoon where water depth is maximal (12 m). Heavy metal concentrations in the two cores were assessed, with calculated enrichment factors and geo-accumulation indexes. Core sediments were also studied for chemical speciation and their monosulfide contents were measured. Results from enrichment factors and geo-accumulation indexes show an accumulation of Cd, Zn, Cr, and Pb, while chemical speciation revealed a risk only from Cd and Mn. Comparison of sequential extraction values with those of acid volatile sulfides revealed that non-toxic effects may be caused by any of the studied metals in the sediment.

  20. Trace element concentrations in freshwater mussels and macrophytes as related to those in their environment

    Directory of Open Access Journals (Sweden)

    Gian Maria BEONE

    2003-02-01

    Full Text Available This study was primarily designed to contribute to the debate "Do accumulator species reflect the element contamination level of their environment?" This research was carried out: 1 to know the distribution of 15 trace elements and calcium in shell and soft tissues of three species of freshwater mussels and macrophytes; 2 to compare the accumulation capacity of each trace element by mussels and by eight species of macrophytes and 3 to test the relationships between the metal concentrations in the mussels and macrophytes and those in water and sediments. The variability of element residues in the mussels is the major limit to accumulator monitoring. The most important causes are: seasonal cycle, physical environment and biological factors such as the size, age and growth rate. This research was designed to eliminate the consequence of variability deriving from the season and the environment. To this end the mussels and macrophytes were collected at the same time from the same habitat: Ranco Bay, Lago Maggiore, Northern Italy. In addition, the element concentrations in more size-classes of the most abundant mussel species (Unio pictorum and Dreissena polymorpha were measured. Trace elements were analyzed by Inductive Coupled Plasma-Mass Spectrometry (ICP-MS. By arranging the data in sequences of decreasing element concentrations in the organisms as well as in water and sediments, we were able to compare the accumulating ability of the tested species and evaluate their capacity to reflect environmental availability. Neither the sequences in the shell nor those in the tissues were similar to the sequence in the water. The differences between the sequences of the mussel tissues and those of the sediments were less striking than those between shells and sediments. Similar results were obtained by macrophytes. In conclusion, the results of this study (which mimics the monitoring practice prove that bioaccumulators cannot be used to evaluate the