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Sample records for shallow freshwater system

  1. Complex communities of small protists and unexpected occurrence of typical marine lineages in shallow freshwater systems.

    Science.gov (United States)

    Simon, Marianne; Jardillier, Ludwig; Deschamps, Philippe; Moreira, David; Restoux, Gwendal; Bertolino, Paola; López-García, Purificación

    2015-10-01

    Although inland water bodies are more heterogeneous and sensitive to environmental variation than oceans, the diversity of small protists in these ecosystems is much less well known. Some molecular surveys of lakes exist, but little information is available from smaller, shallower and often ephemeral freshwater systems, despite their global distribution and ecological importance. We carried out a comparative study based on massive pyrosequencing of amplified 18S rRNA gene fragments of protists in the 0.2-5 μm size range in one brook and four shallow ponds located in the Natural Regional Park of the Chevreuse Valley, France. Our study revealed a wide diversity of small protists, with 812 stringently defined operational taxonomic units (OTUs) belonging to the recognized eukaryotic supergroups (SAR--Stramenopiles, Alveolata, Rhizaria--Archaeplastida, Excavata, Amoebozoa, Opisthokonta) and to groups of unresolved phylogenetic position (Cryptophyta, Haptophyta, Centrohelida, Katablepharida, Telonemida, Apusozoa). Some OTUs represented deep-branching lineages (Cryptomycota, Aphelida, Colpodellida, Tremulida, clade-10 Cercozoa, HAP-1 Haptophyta). We identified several lineages previously thought to be marine including, in addition to MAST-2 and MAST-12, already detected in freshwater, MAST-3 and possibly MAST-6. Protist community structures were different in the five ecosystems. These differences did not correlate with geographical distances, but seemed to be influenced by environmental parameters. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  2. Interactions between nutrients and toxicants in shallow freshwater model ecosystems

    NARCIS (Netherlands)

    Roessink, I.

    2008-01-01

    This thesis investigates the influence of the trophic status of a shallow freshwater system and/or the presence of persistent pollutants in the sediment on the fate and ecological effects of an insecticide and a fungicide/biocide. Additionally, this thesis aims to shed light on the influence of

  3. TiO2 nanoparticles for the remediation of eutrophic shallow freshwater systems: Efficiency and impacts on aquatic biota under a microcosm experiment.

    Science.gov (United States)

    Bessa da Silva, Márcia; Abrantes, Nelson; Nogueira, Verónica; Gonçalves, Fernando; Pereira, Ruth

    2016-09-01

    The application of nanomaterials (NMs) in the remediation of eutrophic waters, particularly in the control of internal loading of nutrients, has been started, but limited investigations evaluated the effectiveness of these new treatment approaches and of their potential impacts on species from shallow freshwater lakes. The present work investigated, under a microcosm experiment, the application of a TiO2 nanomaterial both for reducing nutrient (mainly phosphorus and nitrogen forms) desorption and release from sediments (preventive treatment-PT) and for eliminating algal blooms (remediation treatment-RT). Furthermore, we also intended to assess the potential impacts of nano-TiO2 application on key freshwater species. The results showed the effectiveness of nano-TiO2 in controlling the release of phosphates from surface sediment and the subsequent reduction of total phosphorus in the water column. A reduction in total nitrogen was also observed. Such changes in nutrient dynamics contributed to a progressive inhibition of development of algae after the application of the NM in PT microcosms. Concerning the ability of nano-TiO2 to interact with algal cells, this interaction has likely occurred, mainly in RT, enhancing the formation of aggregates and their rapid settlement, thus reducing the algal bloom. Both treatments caused deleterious effects on freshwater species. In PT, Daphnia magna and Lemna minor showed a significant inhibition of several endpoints. Conversely, no inhibitory effect on the growth of Chironomus riparius was recorded. In opposite, C. riparius was the most affected species in RT microcosms. Such difference was probably caused by the formation of larger TiO2-algae aggregates in RT, under a high algal density, that rapidly settled in the sediment, becoming less available for pelagic species. In summary, despite the effectiveness of both treatments in controlling internal nutrient loading and in the mitigating algal bloom episodes, their negative

  4. Macrophyte Species Drive the Variation of Bacterioplankton Community Composition in a Shallow Freshwater Lake

    Science.gov (United States)

    Zeng, Jin; Bian, Yuanqi; Xing, Peng

    2012-01-01

    Macrophytes play an important role in structuring aquatic ecosystems. In this study, we explored whether macrophyte species are involved in determining the bacterioplankton community composition (BCC) in shallow freshwater lakes. The BCC in field areas dominated by different macrophyte species in Taihu Lake, a large, shallow freshwater lake, was investigated over a 1-year period. Subsequently, microcosm experiments were conducted to determine if single species of different types of macrophytes in an isolated environment would alter the BCC. Denaturing gradient gel electrophoresis (DGGE), followed by cloning and sequence analysis of selected samples, was employed to analyze the BCC. The DGGE results of the field investigations indicated that the BCC changed significantly from season to season and that the presence of different macrophyte species resulted in lower BCC similarities in the summer and fall. LIBSHUFF analysis of selected clone libraries from the summer demonstrated different BCCs in the water column surrounding different macrophytes. Relative to the field observations, the microcosm studies indicated that the BCC differed more pronouncedly when associated with different species of macrophytes, which was also supported by LIBSHUFF analysis of the selected clone libraries. Overall, this study suggested that macrophyte species might be an important factor in determining the composition of bacterial communities in this shallow freshwater lake and that the species-specific influence of macrophytes on BCC is variable with the season and distance. PMID:22038598

  5. 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

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

    African Journals Online (AJOL)

    DRINIE

    determined in water and sediment samples of freshwater systems in the Eastern Cape Province of South Africa that ... The organochlorine pesticides (OCPs) in water and sediments ...... Test Methods For Evaluating Solid Waste (3rd edn.) ...

  7. Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats of the Lower Columbia River, 2007–2010

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Gary E.; Storch, Adam; Skalski, J. R.; Bryson, Amanda J.; Mallette, Christine; Borde, Amy B.; Van Dyke, E.; Sobocinski, Kathryn L.; Sather, Nichole K.; Teel, David; Dawley, Earl M.; Ploskey, Gene R.; Jones, Tucker A.; Zimmerman, Shon A.; Kuligowski, D. R.

    2011-03-01

    The TFM study was designed to investigate the ecology and early life history of juvenile salmonids within shallow (<5 m) tidal freshwater habitats of the LCRE. We started collecting field data in June 2007. Since then, monthly sampling has occurred in the vicinity of the Sandy River delta (rkm 192–208) and at other sites and times in lower river reaches of tidal freshwater (rkm 110 to 141). This report provides a comprehensive synthesis of data covering the field period from June 2007 through April 2010.

  8. Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007

    Energy Technology Data Exchange (ETDEWEB)

    Sobocinski, Kathryn L.; Johnson, Gary E.; Sather, Nichole K.; Storch, Adam; Jones, Tucker A.; Mallette, Christine; Dawley, Earl M.; Skalski, John R.; Teel, David; Moran, Paul

    2008-03-18

    This document is the first annual report for the study titled “Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River.” Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council’s Columbia Basin Fish and Wildlife Program.

  9. The International Editorship of Freshwater Systems

    OpenAIRE

    Karl E. Havens

    2001-01-01

    It is my pleasure to announce that two distinguished internationalscientists have joined the editorship of the FreshwaterSystems domain of TheScientificWorldJOURNAL — Professor BrijGopal of Jawaharlal Nehru University (India) and Dr. Manual Gra柠of the Universityof Coimbra (Portugal). Professor Gopal is the Secretary General of the NationalInstitute of Ecology, Editor of the InternationalJournal of Ecology & Environmental Science,and Chairman of the SIL (International Association of Theoretica...

  10. Computational modeling of shallow geothermal systems

    CERN Document Server

    Al-Khoury, Rafid

    2011-01-01

    A Step-by-step Guide to Developing Innovative Computational Tools for Shallow Geothermal Systems Geothermal heat is a viable source of energy and its environmental impact in terms of CO2 emissions is significantly lower than conventional fossil fuels. Shallow geothermal systems are increasingly utilized for heating and cooling of buildings and greenhouses. However, their utilization is inconsistent with the enormous amount of energy available underneath the surface of the earth. Projects of this nature are not getting the public support they deserve because of the uncertainties associated with

  11. Determination of organotin compounds in the foodweb of a shallow freshwater lake in the Netherlands

    NARCIS (Netherlands)

    Stäb, J.A.; Traas, T.P.; Stroomberg, G.; van Kesteren, J.; Leonards, P.E.G.; van Hattum, A.G.M.; Brinkman, U.A.T.; Cofino, W.P.

    1996-01-01

    An extensive study on the presence of nine organotin compounds (OT) in a freshwater foodweb was made, using newly developed analytical procedures in order to obtain insight in accumulation and degradation processes. Tributyltin (TBT), Triphenyltin (TPT) and their degradation products were detected.

  12. Quantification of methane bubbles in shallow freshwaters using horizontal hydroacoustical observations

    Czech Academy of Sciences Publication Activity Database

    Frouzová, Jaroslava; Tušer, Michal; Stanovský, Petr

    2015-01-01

    Roč. 13, č. 11 (2015), s. 609-616 ISSN 1541-5856 R&D Projects: GA ČR(CZ) GAP504/12/1186 Institutional support: RVO:60077344 ; RVO:67985858 Keywords : methane ebullition * freshwaters * sonar Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.008, year: 2015

  13. Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Sobocinski, Kathryn; Johnson, Gary; Sather, Nichole [Pacific Northwest National Laboratory

    2008-03-17

    This document is the first annual report for the study titled 'Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River'. Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program. The goal of the 2007-2009 Tidal Freshwater Monitoring Study is to answer the following questions: In what types of habitats within the tidal freshwater area of the lower Columbia River and estuary (LCRE; Figure 1) are yearling and subyearling salmonids found, when are they present, and under what environmental conditions?1 And, what is the ecological importance2 of shallow (0-5 m) tidal freshwater habitats to the recovery of Upper Columbia River spring Chinook salmon and steelhead and Snake River fall Chinook salmon? Research in 2007 focused mainly on the first question, with fish stock identification data providing some indication of Chinook salmon presence at the variety of habitat types sampled. The objectives and sub-objectives for the 2007 study were as follows: (1) Habitat and Fish Community Characteristics-Provide basic data on habitat and fish community characteristics for yearling and subyearling salmonids at selected sites in the tidal freshwater reach in the vicinity of the Sandy River delta. (1a) Characterize vegetation assemblage percent cover, conventional water quality, substrate composition, and beach slope at each of six sampling sites in various tidal freshwater habitat types. (1b

  14. 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.

  15. Biofouling problems in freshwater cooling systems

    International Nuclear Information System (INIS)

    Rao, T.S.

    2007-01-01

    In aqueous environments, microorganisms (bacteria, algae, fungi etc.,) are attracted towards surfaces, which they readily colonise resulting in the formation of biofilms. The implications of biofouling are energy losses due to increased fluid frictional resistance and increased heat transfer resistance. The temperatures prevalent inside the condenser system provide a favorable environment for the rapid growth of microorganisms. This results in thick slime deposit, which is responsible for heat transfer losses, thereby enhancing aggregation of deposits on the material surface and induces localised corrosion. There have been instances of increased capital costs due to premature replacement of equipment caused by severe under deposit corrosion due to biofouling. Moreover, fouling of service water systems of nuclear power plants is of concern, because it reduces the heat transfer capacity during an emergency or an accident. The growth of microbial films (slimes) a few tens of microns thick, in a condenser tube is sufficient to induce microbiologically influenced corrosion and cause irreparable damage to the condenser tubes and other structural materials. The down time costs to power plant due to condenser fouling and corrosion are quite large. This paper presents the author's experience in biofouling and corrosion problems in various power plants cooled by freshwater. (author)

  16. The International Editorship of Freshwater Systems

    Directory of Open Access Journals (Sweden)

    Karl E. Havens

    2001-01-01

    Full Text Available It is my pleasure to announce that two distinguished internationalscientists have joined the editorship of the FreshwaterSystems domain of TheScientificWorldJOURNAL — Professor BrijGopal of Jawaharlal Nehru University (India and Dr. Manual Gra柠of the Universityof Coimbra (Portugal. Professor Gopal is the Secretary General of the NationalInstitute of Ecology, Editor of the InternationalJournal of Ecology & Environmental Science,and Chairman of the SIL (International Association of Theoretical and AppliedLimnology Committee on Limnology in Developing Countries. His research interestsinclude the ecology, biogeochemistry and biodiversity of wetland ecosystems,the management of wetlands as an integral part of the watershed, and wetlandwater policy–related issues. Dr. Gra柠is a stream ecologist whose researchinterests include the two general areas of organic matter decomposition andbiological monitoring. His specific areas of research focus include quantificationof organic matter and other chemical changes in decomposing leaves, the ecologyof aquatic hyphomycetes, and the ecology of animals feeding on detritus. Hisresearch dealing with biological monitoring is carried out in close cooperationwith the paper and mining industries, facilitating the practical applicationof his work.

  17. Submerged macrophytes modify bacterial community composition in sediments in a large, shallow, freshwater lake.

    Science.gov (United States)

    Zhao, Da-Yong; Liu, Peng; Fang, Chao; Sun, Yi-Meng; Zeng, Jin; Wang, Jian-Qun; Ma, Ting; Xiao, Yi-Hong; Wu, Qinglong L

    2013-04-01

    Submerged aquatic macrophytes are an important part of the lacustrine ecosystem. In this study, the bacterial community compositions in the rhizosphere sediments from three kinds of submerged macrophytes (Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans) were investigated to determine whether submerged macrophytes could drive the variation of bacterial community in the eutrophic Taihu Lake, China. Molecular techniques, including terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene and clone libraries, were employed to analyze the bacterial community compositions. Remarkable differences of the T-RFLP patterns were observed among the different samples, and the results of LIBSHUFF analysis also confirmed that the bacterial community compositions in the rhizosphere sediments of three kinds of submerged macrophytes were statistically different from that of the unvegetated sediment. Acidobacteria, Deltaproteobacteria, and Betaproteobacteria were the dominant bacterial groups in the rhizosphere sediments of Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans, respectively, accounting for 15.38%, 29.03%, and 18.00% of the total bacterial abundances. Our study demonstrated that submerged macrophytes could influence the bacterial community compositions in their rhizosphere sediments, suggesting that macrophytes have an effect on the cycling and transportation of nutrients in the freshwater lake ecosystem.

  18. Biota: Providing often-overlooked connections among freshwater systems

    Science.gov (United States)

    Mushet, David M.; Christensen, Jay R.; Bennett, Michah; Alexander, Laurie C.

    2017-01-01

    When we think about connections in and among aquatic systems, we typically envision clear headwater streams flowing into downstream rivers, river floodwaters spilling out onto adjacent floodplains, or groundwater connecting wetlands to lakes and streams. However, there is another layer of connectivity moving materials among freshwater systems, one with connections that are not always tied to downgradient flows of surface waters and groundwater. These movements are those of organisms, key components of virtually every freshwater system on the planet. In their movements across the landscape, biota connect aquatic systems in often-overlooked ways.

  19. Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Sather, NK; Johnson, GE; Storch, AJ [Pacific Northwest National Laboratory

    2009-07-06

    The tidal freshwater monitoring (TFM) project reported herein is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, the U.S. Army Corps of Engineers [USACE], and the U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act (ESA) as a result of operation of the Federal Columbia River Power System. The project is being performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program (Project No. 2005-001-00). The research is a collaborative effort among the Pacific Northwest National Laboratory, the Oregon Department of Fish and Wildlife, the National Marine Fisheries Service, and the University of Washington. The overarching goal of the TFM project is to bridge the gap in knowledge between tidal freshwater habitats and the early life history attributes of migrating salmon. The research questions include: In what types of habitats within the tidal freshwater area of the Columbia River are juvenile salmon found, when are they present, and under what environmental conditions? What is the ecological contribution of shallow (0-5 m) tidal freshwater habitats to the recovery of ESA-listed salmon in the Columbia River basin? Field data collection for the TFM project commenced in June 2007 and since then has continued monthly at six to nine sites in the vicinity of the Sandy River delta (river kilometer 192-208). While this report includes summary data spanning the 19-month period of study from June 2007 through December 2008, it highlights sampling conducted during calendar year 2008. Detailed data for calendar year 2007 were reported previously. The 2008 research objectives were as follows: (1) Characterize the vegetation composition and percent cover, conventional water quality, water surface elevation, substrate composition, bathymetry, and beach slope at the study sites within the vicinity of the Sandy

  20. How to prevent legionella infestation. Pt. 1. Central freshwater heating systems; Wie man Legionellen vermeiden. T. 1. Zentrale Trinkwassererwaermungsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, Robert [DVGW-Fachausschuss Trinkwasserhygiene in Gebaeuden, Leverkusen (Germany)

    2009-01-15

    The contribution focuses on hygienically safe freshwater heating. Legionella prophylaxis is discussed, as are new findings concerning practical implementation of new requirements on modern freshwater supply systems. (orig.)

  1. Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms

    International Nuclear Information System (INIS)

    Gonzalez-Barreiro, O.; Rioboo, C.; Herrero, C.; Cid, A.

    2006-01-01

    The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides

  2. Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Barreiro, O. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Rioboo, C. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Herrero, C. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Cid, A. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain)]. E-mail: cid@udc.es

    2006-11-15

    The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides.

  3. Yield response and economics of shallow subsurface drip irrigation systems

    Science.gov (United States)

    Field tests were conducted using shallow subsurface drip irrigation (S3DI) on cotton (Gossypium hirsutum, L.), corn (Zea mays, L.), and peanut (Arachis hypogeae, L.) in rotation to investigate yield potential and economic sustainability of this irrigation system technique over a six year period. Dri...

  4. Shallow land disposal, the french system

    International Nuclear Information System (INIS)

    Barthoux, A.; Marque, Y.

    1986-01-01

    Since 1969, low and medium activity waste are disposed of in France at the Centre Manche. The management system set up covers the whole of the operations, from the sorting of the wastes and their conditioning to the final disposal. Safety standards and technical issues were found satisfactory by the National Safety Authority and they are the basis of the program for the realization of two new disposal sites which should take over from the Centre Manche loaded towards 1990. ANDRA, a National Agency, is responsible for the long term management of radioactive waste, in France [fr

  5. Effect of water chemistry on zooplanktonic and microbial communities across freshwater ecotones in different macrophyte-dominated shallow lakes

    Directory of Open Access Journals (Sweden)

    Tomasz Mieczan

    2015-12-01

    Full Text Available Complex interactions between zooplankton and microbial food webs are vital to the ecosystem ecology of shallow lakes. However, little is known about how horizontal changes in environmental conditions may influence microbial and metazoan communities in shallow lakes. The specific goals of the study were i to describe environmental variables responsible for the distribution of bacteria, flagellates, ciliates and crustaceans in an adjacent canal, ecotone and reservoir (littoral-pelagic zone in two different types of lakes (Ceratophyllum-dominated and Potamogeton-dominated lakes; ii to determine whether the contact zone waters differ in hydrochemical and biological terms from the waters of the canal and the open water zone; iii and to evaluate the influence of particular macro-habitats (canal, canal/reservoir, littoral and pelagic zone on the interactions between components of the planktonic food web. We studied four shallow, eutrophic lakes in Polesie Lubelskie (eastern Poland. The highest diversity and abundance of microorganisms and crustaceans were observed in the canal-reservoir contact zone, while the lowest values were noted in the pelagic zone. Hence, the contact zone in the investigated lakes could fulfil the function of an ecotone, distinguished by a significant increase in biodiversity, abundance, and species specificity of micro- and macroorganisms. Weak relations between food web components were found in the Ceratophyllum-dominated lakes, where environmental variables explained the bulk of the total variance in plankton abundance, whereas in the Potamogeton-dominated lakes, where environmental variables had a minor role in the total variance in plankton abundance, strong predator-prey relations were noted. Spatial structure of habitats proved to be another important factor for relationships between food web components, as our study indicated that habitat complexity can reduce negative correlations between food web components. Our study

  6. Microbial Geochemistry in Shallow-Sea Hydrothermal Systems

    Science.gov (United States)

    Amend, J. P.; Pichler, T.

    2006-12-01

    Shallow-sea hydrothermal systems are far more ubiquitous than generally recognized. Approximately 50-60 systems are currently known, occurring world-wide in areas of high heat flow, such as, volcanic island arcs, near-surface mid-ocean ridges, and intraplate oceanic volcanoes. In contrast to deep-sea systems, shallow- sea vent fluids generally include a meteoric component, they experience phase separation near the sediment- water interface, and they discharge into the photic zone (thermophilic bacteria and archaea. Perhaps because deep-sea smokers and continental hot springs are visually more stunning, shallow-sea systems are often overlooked study sites. We will discuss their particular features that afford unique opportunities in microbial geochemistry. Two of the better studied examples are at Vulcano Island (Italy) and Ambitle Island (Papua New Guinea). The vents and sediment seeps at Vulcano are the "type locality" for numerous cultured hyperthermophiles, including the bacteria Aquifex and Thermotoga, the crenarchaeon Pyrodictium, and the Euryarchaeota Archaeoglobus and Pyrococcus. Isotope-labeled incubation experiments of heated sediments and an array of culturing studies have shown that simple organic compounds are predominantly fermented or anaerobically respired with sulfate. 16S rRNA gene surveys, together with fluorescent in situ hybridization studies, demonstrated the dominance of key thermophilic bacteria and archaea (e.g., Aquificales, Thermotogales, Thermococcales, Archaeoglobales) in the sediments and the presence of a broad spectrum of mostly uncultured crenarchaeota in several vent waters, sediment samples, and geothermal wells. Thermodynamic modeling quantified potential energy yields from aerobic and anaerobic respiration reactions and fermentation reactions. In contrast to their deep-sea counterparts, shallow-sea hydrothermal systems are often characterized by high arsenic concentrations of more than 500-times seawater levels. The arsenic

  7. Ground-water flow and saline water in the shallow aquifer system of the southern watersheds of Virginia Beach, Virginia

    Science.gov (United States)

    Smith, Barry S.

    2003-01-01

    Population and tourism continues to grow in Virginia Beach, Virginia, but the supply of freshwater is limited. A pipeline from Lake Gaston supplies water for northern Virginia Beach, but ground water is widely used to water lawns in the north, and most southern areas of the city rely solely on ground water. Water from depths greater than 60 meters generally is too saline to drink. Concentrations of chloride, iron, and manganese exceed drinking-water standards in some areas. The U.S. Geological Survey, in cooperation with the city of Virginia Beach, Department of Public Utilities, investigated the shallow aquifer system of the southern watersheds to determine the distribution of fresh ground water, its potential uses, and its susceptibility to contamination. Aquifers and confining units of the southern watersheds were delineated and chloride concentrations in the aquifers and confining units were contoured. A ground-water-flow and solute-transport model of the shallow aquifer system reached steady state with regard to measured chloride concentrations after 31,550 years of freshwater recharge. Model simulations indicate that if freshwater is found in permeable sediments of the Yorktown-Eastover aquifer, such a well field could supply freshwater, possibly for decades, but eventually the water would become more saline. The rate of saline-water intrusion toward the well field would depend on the rate of pumping, aquifer properties, and on the proximity of the well field to saline water sources. The steady-state, ground-water-flow model also was used to simulate drawdowns around two hypothetical well fields and drawdowns around two hypothetical open-pit mines. The chloride concentrations simulated in the model did not approximate the measured concentrations for some wells, indicating sites where local hydrogeologic units or unit properties do not conform to the simple hydrogeology of the model. The Columbia aquifer, the Yorktown confining unit, and the Yorktown

  8. Bisphenol analogues in surface water and sediment from the shallow Chinese freshwater lakes: Occurrence, distribution, source apportionment, and ecological and human health risk.

    Science.gov (United States)

    Yan, Zhengyu; Liu, Yanhua; Yan, Kun; Wu, Shengmin; Han, Zhihua; Guo, Ruixin; Chen, Meihong; Yang, Qiulian; Zhang, Shenghu; Chen, Jianqiu

    2017-10-01

    Compared to Bisphenol A (BPA), current knowledge on the spatial distribution, potential sources and environmental risk assessment of other bisphenol analogues (BPs) remains limited. The occurrence, distribution and sources of seven BPs were investigated in the surface water and sediment from Taihu Lake and Luoma Lake, which are the Chinese shallow freshwater lakes. Because there are many industries and living areas around Taihu Lake, the total concentrations of ∑BPs were much higher than that in Luoma Lake, which is away from the industry-intensive areas. For the two lakes, BPA was still the dominant BPs in both surface water and sediment, followed by BPF and BPS. The spatial distribution and principal component analysis showed that BPs in Luoma Lake was relatively homogeneous and the potential sources were relatively simple than that in Taihu Lake. The spatial distribution of BPs in sediment of Taihu Lake indicated that ∑BPs positively correlated with the TOC content. For both Taihu Lake and Luoma Lake, the risk assessment at the sampling sites showed that no high risk in surface water and sediment (RQ t  < 1.0, and EEQ t  < 1.0 ng E 2 /L). Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Distribution and bioaccumulation of endocrine disrupting chemicals in water, sediment and fishes in a shallow Chinese freshwater lake: Implications for ecological and human health risks.

    Science.gov (United States)

    Dan Liu; Wu, Shengmin; Xu, Huaizhou; Zhang, Qin; Zhang, Shenghu; Shi, Lili; Yao, Cheng; Liu, Yanhua; Cheng, Jie

    2017-06-01

    The occurrence, distribution and bioaccumulation of six endocrine disrupting compounds (EDCs) were investigated in water, sediment and biota samples from Luoma Lake, a shallow Chinese freshwater lake. Total concentrations of ∑phenolic EDCs were much higher than ∑estrogens EDCs in both waters and sediments. There were not obvious differences on the concentrations of target compounds [except nonylphenol (NP)] in upstream, lake and downstream locations, these may be suggested that they were mainly affected by non-point discharges in this area. However, the high concentration of NP in water may be associated with the discharge of rural domestic wastewater without thorough treatment. Furthermore, concentrations of NP were about 2-3 order magnitude higher than those of OP in both water and sediment compartments. Relatively higher bioaccumulation factors (BAF) were obtained for DES and EE2. Ecological risk assessment revealed greater risk of NP in surface water, which may pose a serious threat to aquatic ecosystems. The estrogen equivalent concentration (EEQ) of male were higher than those in female, and occurred in the order of city >rural-urban>countryside. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Emulation of recharge and evapotranspiration processes in shallow groundwater systems

    Science.gov (United States)

    Doble, Rebecca C.; Pickett, Trevor; Crosbie, Russell S.; Morgan, Leanne K.; Turnadge, Chris; Davies, Phil J.

    2017-12-01

    In shallow groundwater systems, recharge and evapotranspiration are highly sensitive to changes in the depth to water table. To effectively model these fluxes, complex functions that include soil and vegetation properties are often required. Model emulation (surrogate modelling or meta-modelling) can provide a means of incorporating detailed conceptualisation of recharge and evapotranspiration processes, while maintaining the numerical tractability and computational performance required for regional scale groundwater models and uncertainty analysis. A method for emulating recharge and evapotranspiration processes in groundwater flow models was developed, and applied to the South East region of South Australia and western Victoria, which is characterised by shallow groundwater, wetlands and coastal lakes. The soil-vegetation-atmosphere transfer (SVAT) model WAVES was used to generate relationships between net recharge (diffuse recharge minus evapotranspiration from groundwater) and depth to water table for different combinations of climate, soil and land cover types. These relationships, which mimicked previously described soil, vegetation and groundwater behaviour, were combined into a net recharge lookup table. The segmented evapotranspiration package in MODFLOW was adapted to select values of net recharge from the lookup table depending on groundwater depth, and the climate, soil and land use characteristics of each cell. The model was found to be numerically robust in steady state testing, had no major increase in run time, and would be more efficient than tightly-coupled modelling approaches. It made reasonable predictions of net recharge and groundwater head compared with remotely sensed estimates of net recharge and a standard MODFLOW comparison model. In particular, the method was better able to predict net recharge and groundwater head in areas with steep hydraulic gradients.

  11. The role of macroinvertebrates for conservation of freshwater systems.

    Science.gov (United States)

    Nieto, Carolina; Ovando, Ximena M C; Loyola, Rafael; Izquierdo, Andrea; Romero, Fátima; Molineri, Carlos; Rodríguez, José; Rueda Martín, Paola; Fernández, Hugo; Manzo, Verónica; Miranda, María José

    2017-07-01

    Freshwater ecosystems are the most threatened ecosystems worldwide. Argentinian-protected areas have been established mainly to protect vertebrates and plants in terrestrial ecosystems. In order to create a comprehensive biodiverse conservation plan, it is crucial to integrate both aquatic and terrestrial systems and to include macroinvertebrates. Here, we address this topic by proposing priority areas of conservation including invertebrates, aquatic ecosystems, and their connectivity and land uses. Northwest of Argentina. We modeled the ecological niches of different taxa of macroinvertebrates such as Coleoptera, Ephemeroptera, Hemiptera, Megaloptera, Lepidoptera, Odonata, Plecoptera, Trichoptera, Acari, and Mollusca. Based on these models, we analyzed the contribution of currently established protected areas in the conservation of the aquatic biodiversity and we propose a spatial prioritization taking into account possible conflict regarding different land uses. Our analysis units were the real watersheds, to which were added longitudinal connectivity up and down the rivers. A total of 132 species were modeled in the priority area analyses. The analysis 1 showed that only an insignificant percentage of the macroinvertebrates distribution is within the protected areas in the North West of Argentina. The analyses 2 and 3 recovered similar values of protection for the macroinvertebrate species. The upper part of Bermejo, Salí-Dulce, San Francisco, and the Upper part of Juramento basins were identified as priority areas of conservation. The aquatic ecosystems need special protection and 10% or even as much as 17% of land conservation is insufficient for species of macroinvertebrates. In turn the protected areas need to combine the aquatic and terrestrial systems and need to include macroinvertebrates as a key group to sustain the biodiversity. In many cases, the land uses are in conflict with the conservation of biodiversity; however, it is possible to apply the

  12. Measuring benefits of protected area management: trends across realms and research gaps for freshwater systems.

    Science.gov (United States)

    Adams, Vanessa M; Setterfield, Samantha A; Douglas, Michael M; Kennard, Mark J; Ferdinands, Keith

    2015-11-05

    Protected areas remain a cornerstone for global conservation. However, their effectiveness at halting biodiversity decline is not fully understood. Studies of protected area benefits have largely focused on measuring their impact on halting deforestation and have neglected to measure the impacts of protected areas on other threats. Evaluations that measure the impact of protected area management require more complex evaluation designs and datasets. This is the case across realms (terrestrial, freshwater, marine), but measuring the impact of protected area management in freshwater systems may be even more difficult owing to the high level of connectivity and potential for threat propagation within systems (e.g. downstream flow of pollution). We review the potential barriers to conducting impact evaluation for protected area management in freshwater systems. We contrast the barriers identified for freshwater systems to terrestrial systems and discuss potential measurable outcomes and confounders associated with protected area management across the two realms. We identify key research gaps in conducting impact evaluation in freshwater systems that relate to three of their major characteristics: variability, connectivity and time lags in outcomes. Lastly, we use Kakadu National Park world heritage area, the largest national park in Australia, as a case study to illustrate the challenges of measuring impacts of protected area management programmes for environmental outcomes in freshwater systems. © 2015 The Author(s).

  13. Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008

    Energy Technology Data Exchange (ETDEWEB)

    Sather, Nichole K.; Johnson, Gary E.; Storch, Adam; Teel, David; Skalski, John R.; Jones, Tucker A.; Dawley, Earl M.; Zimmerman, Shon A.; Borde, Amy B.; Mallette, Christine; Farr, R.

    2009-05-29

    The tidal freshwater monitoring (TFM) project reported herein is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, the U.S. Army Corps of Engineers [USACE], and the U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act (ESA) as a result of operation of the Federal Columbia River Power System. The project is being performed under the auspices of the Northwest Power and Conservation Council’s Columbia Basin Fish and Wildlife Program (Project No. 2005-001-00). The research is a collaborative effort among the Pacific Northwest National Laboratory, the Oregon Department of Fish and Wildlife, the National Marine Fisheries Service, and the University of Washington.

  14. Physics of coral reef systems in a shallow tidal embayment

    NARCIS (Netherlands)

    Hoitink, Antonius Johannes Franciscus

    2003-01-01

    Ongoing deforestation in the tropics involves higher river discharges and an increase of runoff, which has consequences to coastal ecosystems. The dispersal of fluvial sediment and freshwater by marine processes affects the environmental determinants of coral reefs near the coast, which include

  15. Concentration and distribution of dissolved amino acids in a shallow hydrothermal system, Vulcano Island (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, E.; Skoog, A. [University of Connecticut, Groton, CT (United States). Dept. of Marine Sciences; Amend, J.P. [Washington University, St. Louis, MO (United States). Dept. of Earth and Planetary Sciences

    2004-09-01

    Hydrothermal systems are known to harbour a large number of microorganisms, but the organic chemical composition of the solution that comprises their potential substrate is largely unknown. Concentrations and distributions of dissolved free amino acids (DFAA) and dissolved combined amino acids (DCAA) were determined in fluids from the moderate-temperature (42-89{sup o}C), shallow hydrothermal system on the volcanically active island of Vulcano, Italy. The seven samples represent three different geological settings on the island; shallow ({approx} 1 m) submarine vents, geothermal wells, and seeps in heated beach sediments, in addition to ambient local seawater from the bay, Baia di Levante. All hydrothermal sites, with one exception, had TDAA concentrations that were 3-114 times higher than local seawater in Baia di Levante. There were large similarities in amino acid concentration and composition among samples from the same geological setting. The highest amino acid concentrations were found at sites with acidic and reducing conditions, which also had the largest freshwater component. An unusually high fraction of the TDAA pool was represented by DFAA (33-87%), possibly due to in situ acid hydrolysis of DCAA to DFAA. Both DFAA and DCAA concentrations were correlated to DOC, indicating similar source and sink functions for these pools. The yield of TDAA (TDAA-carbon as fraction of organic carbon) ranged from 2% to 25%, which is high compared with non-hydrothermal settings, and indicates high biological lability. The mole fraction of {beta}-alanine plus {gamma}-aminobutyric acid (% BALA + GABA) was 2-2.7% of TDAA, also indicating high biological lability. Owing to the high over-all amino acid concentrations, the high fraction of DFAAs, and the high biological lability of the organic matter, organic matter in general and amino acids specifically could represent significant carbon and energy sources for archaea and bacteria in this hydrothermal system. The clear

  16. Multimedia fate modeling of perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS) in the shallow lake Chaohu, China

    NARCIS (Netherlands)

    Kong, X.; Liu, W.; He, W.; Xu, F.; Koelmans, Albert A; Mooij, W.M.

    2018-01-01

    Freshwater shallow lake ecosystems provide valuable ecological services to human beings. However, these systems are subject to severe contamination from anthropogenic sources. Per- and polyfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS),

  17. Experimental study of a sustainable hybrid system for thermoelectric generation and freshwater production

    Science.gov (United States)

    de Souza, Gabriel Fernandes; Tan, Lippong; Singh, Baljit; Ding, Lai Chet; Date, Abhijit

    2017-04-01

    The paper presents a sustainable hybrid system, which is capable of generating electricity and producing freshwater from seawater using low grade heat source. This proposed system uses low grade heat that can be supplied from solar radiation, industrial waste heat or any other waste heat sources where the temperature is less than 150°C. The concept behind this system uses the Seebeck effect for thermoelectricity generation via incorporating the low boiling point of seawater under sub-atmospheric ambient pressure. A lab-test prototype of the proposed system was built and experimentally tested in RMIT University. The prototype utilised four commercial available thermoelectric generators (Bi2Te3) and a vacuum vessel to achieve the simultaneous production of electricity and freshwater. The temperature profiles, thermoelectric powers and freshwater productions were determined at several levels of salinity to study the influence of different salt concentrations. The theoretical description of system design and experimental results were analysed and discussed in detailed. The experiment results showed that 0.75W of thermoelectricity and 404g of freshwater were produced using inputs of 150W of simulated waste heat and 500g of 3% saline water. The proposed hybrid concept has demonstrated the potential to become the future sustainable system for electricity and freshwater productions.

  18. Analysis of the Arctic system for freshwater cycle intensification: Observations and expectations

    Science.gov (United States)

    Rawlins, M.A.; Steele, M.; Holland, M.M.; Adam, J.C.; Cherry, J.E.; Francis, J.A.; Groisman, P.Y.; Hinzman, L.D.; Huntington, T.G.; Kane, D.L.; Kimball, J.S.; Kwok, R.; Lammers, R.B.; Lee, C.M.; Lettenmaier, D.P.; McDonald, K.C.; Podest, E.; Pundsack, J.W.; Rudels, B.; Serreze, Mark C.; Shiklomanov, A.; Skagseth, O.; Troy, T.J.; Vorosmarty, C.J.; Wensnahan, M.; Wood, E.F.; Woodgate, R.; Yang, D.; Zhang, K.; Zhang, T.

    2010-01-01

    Hydrologic cycle intensification is an expected manifestation of a warming climate. Although positive trends in several global average quantities have been reported, no previous studies have documented broad intensification across elements of the Arctic freshwater cycle (FWC). In this study, the authors examine the character and quantitative significance of changes in annual precipitation, evapotranspiration, and river discharge across the terrestrial pan-Arctic over the past several decades from observations and a suite of coupled general circulation models (GCMs). Trends in freshwater flux and storage derived from observations across the Arctic Ocean and surrounding seas are also described. With few exceptions, precipitation, evapotranspiration, and river discharge fluxes from observations and the GCMs exhibit positive trends. Significant positive trends above the 90% confidence level, however, are not present for all of the observations. Greater confidence in the GCM trends arises through lower interannual variability relative to trend magnitude. Put another way, intrinsic variability in the observations tends to limit confidence in trend robustness. Ocean fluxes are less certain, primarily because of the lack of long-term observations. Where available, salinity and volume flux data suggest some decrease in saltwater inflow to the Barents Sea (i.e., a decrease in freshwater outflow) in recent decades. A decline in freshwater storage across the central Arctic Ocean and suggestions that large-scale circulation plays a dominant role in freshwater trends raise questions as to whether Arctic Ocean freshwater flows are intensifying. Although oceanic fluxes of freshwater are highly variable and consistent trends are difficult to verify, the other components of the Arctic FWC do show consistent positive trends over recent decades. The broad-scale increases provide evidence that the Arctic FWC is experiencing intensification. Efforts that aim to develop an adequate

  19. Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in a freshwater snail (Bellamya aeruginosa) from a large shallow, eutrophic lake of the subtropical China

    International Nuclear Information System (INIS)

    Chen Jun; Xie Ping; Guo Longgen; Zheng Li; Ni Leyi

    2005-01-01

    Tissue distributions and seasonal dynamics of the hepatotoxic microcystins-LR and -RR in a freshwater snail (Bellamya aeruginosa) were studied monthly in a large shallow, eutrophic lake of the subtropical China during June-November, 2003. Microcystins (MCs) were quantitatively determined by High-Performance Liquid Chromatography (HPLC) with a qualitative analysis by a Finnigan LC-MS system. On the average of the study period, hepatopancreas was the highest in MC contents (mean 4.14 and range 1.06-7.42 μg g -1 DW), followed by digestive tracts (mean 1.69 and range 0.8-4.54 μg g -1 DW) and gonad (mean 0.715 and range 0-2.62 μg g -1 DW), whereas foot was the least (mean 0.01 and range 0-0.06 μg g -1 DW). There was a positive correlation in MC contents between digestive tracts and hepatopancreas. A constantly higher MC content in hepatopancreas than in digestive tracts indicates a substantial bioaccumulation of MCs in the hepatopancreas of the snail. The average ratio of MC-LR/MC-RR showed a steady increase from digestive tracts (0.44) to hepatopancreas (0.63) and to gonad (0.96), suggesting that MC-LR was more resistant to degradation in the snail. Since most MCs were present in the hepatopancreas, digestive tracts and gonad with only a very small amount in the edible foot, the risk to human health may not be significant if these toxic parts are removed prior to snail consumption. However, the possible transference of toxins along food chains should not be a negligible concern. - Snails bioaccumulate microcystins in their hepatopancreas, gut and gonad, posing a risk to human consumers

  20. Environmental influences on the composition and structure of the freshwater mussels in shallow lakes in the Cuiabá River floodplain

    Directory of Open Access Journals (Sweden)

    AC. Colle

    Full Text Available The maintenance of the freshwater mussels' community in lakes is determined by abiotic factors at the local scale and at regional scale by interspecific relations between the larvae of bivalves and fish host. Whereas the distribution pattern at local scale, our goal was to understand the abundance and community composition of bivalves and relate the environmental agents structuring this community. We sampled 20 lakes in the floodplain of the Cuiabá River using a standardized method of sampling. To evaluate the effect of environment on the community we applied multivariate inferential analyses. We found 1.143 individuals alive belonging into six species distributed at the family Hyriidae, Mycetopodidae, Sphaeridae and Corbiculidae. The results showed that in the Pantanal the bivalve assemblage structure is influenced locally by organic matter and particle size, variables that reflect the intense interactions between water-sediment. However it is important to emphasize that these environmental characteristics are the result of the dynamics of this system which is dependent on the flood pulse, a regional factor.

  1. Shallow magmatic degassing into the hydrothermal system of Copahue, Argentina

    Science.gov (United States)

    Varekamp, J.; Ouimette, A.; Kreulen, R.; Delpino, D.; Bermudez, A.

    2001-05-01

    Copahue volcano has a crater lake and acid hot springs that discharge into the Rio Agrio river system. These fluids are very concentrated (up to 6 percent sulfate), rich in rock-forming elements (up to 2000 ppm Mg) and small spheres of native sulfur float in the crater lake. The stable isotope composition of the waters (delta 18O =-2.1 to + 3.6 per mille; delta D = -49 to -26 per mille) indicates that the hot spring waters are at their most concentrated about 70 percent volcanic brine and 30 percent glacial meltwater. The crater lake waters have similar mixing proportions but added isotope effects from intense evaporation. Further dilution of the waters in the Rio Agrio gives values closer to local meteoric waters (delta 18O = -11 per mille; delta D = -77 per mille), whereas evaporation in closed ponds led to very heavy water (up to delta 18O = +12 per mille). The delta 34S value of dissolved sulfate is +14.2 per mille, whereas the native sulfur has values of -8.2 to -10.5 per mille. The heavy sulfate probably formed when SO2 disproportionated into bisulfate and native sulfur. We measured the sulfate fluxes in the Rio Agrio, and from these flux values and the stoichiometry of the disproportionation reaction we calculated the rate of liquid sulfur storage inside the volcano (6000 m3/year). During the eruptions of 1995/2000, large amounts of that stored liquid sulfur were ejected as pyroclastic sulfur. The calculated rate of rock dissolution (from rock- forming element fluxes in the Rio Agrio) suggests that the void space generated by rock dissolution is largely filled by native sulfur. The isotopic signature of the magmatic sulfur can be reconstituted at about +7 per mille, which is a source signature with superposed effects of shallow degassing. Lead isotope and 129Iodine data from the fluids indicate that subducted components may have played a role in the Copahue magma formation. Primary glass inclusions in plagioclase and olivine have 1110-1670 ppm Cl, 90-400 ppm

  2. Assessment of human-natural system characteristics influencing global freshwater supply vulnerability

    Science.gov (United States)

    Padowski, Julie C.; Gorelick, Steven M.; Thompson, Barton H.; Rozelle, Scott; Fendorf, Scott

    2015-10-01

    Global freshwater vulnerability is a product of environmental and human dimensions, however, it is rarely assessed as such. Our approach identifies freshwater vulnerability using four broad categories: endowment, demand, infrastructure, and institutions, to capture impacts on natural and managed water systems within the coupled human-hydrologic environment. These categories are represented by 19 different endogenous and exogenous characteristics affecting water supply vulnerability. By evaluating 119 lower per capita income countries (Yemen and Djibouti nearly as vulnerable. Surprising similarities in vulnerability were also found among geographically disparate nations such as Vietnam, Sri Lanka, and Guatemala. Determining shared patterns of freshwater vulnerability provides insights into why water supply vulnerabilities are manifested in human-water systems at the national scale.

  3. Exploring Freshwater Science

    Indian Academy of Sciences (India)

    and long term studies on mapping freshwater biodiversity1. 1. R J Ranjit Daniels ... The hierarchical nature of stream organization offers opportunity to ecologists to ask .... threats, freshwater systems are losing their aesthetic value (Fig- ure 4).

  4. Fate of nano- and microplastic in freshwater systems: A modeling study

    NARCIS (Netherlands)

    Besseling, Ellen; Quik, Joris T.K.; Sun, Muzhi; Koelmans, Bart

    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

  5. Hygiene problems in practice. Pt. 2. Central freshwater heating systems; Hygieneprobleme in der Praxis. T. 2. Zentrale Trinkwassererwaermungsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, Robert [DVGW-Fachausschuss Trinkwasserhygiene in Gebaeuden, Leverkusen (Germany)

    2009-02-15

    Hygienically safe freshwater heating is the subject of this two-installment article series. Relevant standards and regulations are discussed, and the legionella problem in central freshwater heating systems is gone into. The second part of the series describes dimensioning errors which result in overdimensioning, which in turn may quickly cause hygiene problems. (orig.)

  6. Global freshwater thermal emissions from steam-electric power plants with once-through cooling systems

    International Nuclear Information System (INIS)

    Raptis, Catherine E.; Pfister, Stephan

    2016-01-01

    Large quantities of heat are rejected into freshwater bodies from power plants employing once-through cooling systems, often leading to temperature increases that disturb aquatic ecosystems. The objective of this work was to produce a high resolution global picture of power-related freshwater thermal emissions and to analyse the technological, geographical and chronological patterns behind them. The Rankine cycle was systematically solved for ∼2400 generating units with once-through cooling systems, distinguishing between simple and cogenerative cycles, giving the rejected heat as a direct output. With large unit sizes, low efficiencies, and high capacity factors, nuclear power plants reject 3.7 GW heat into freshwater on average, contrasting with 480 MW rejected from coal and gas power plants. Together, nuclear and coal-fuelled power plants from the 1970s and 1980s account for almost 50% of the rejected heat worldwide, offering motivation for their phasing out in the future. Globally, 56% of the emissions are rejected into rivers, pointing to potential areas of high thermal pollution, with the rest entering lakes and reservoirs. The outcome of this work can be used to further investigate the identified thermal emission hotspots, and to calculate regionalized water temperature increase and related impacts in environmental, energy-water nexus studies and beyond. - Highlights: • The thermodynamic cycles of ∼2400 power units with once-through cooling were solved. • Global freshwater heat emissions depend on technology, geography & chronology. • Half the global emissions come from nuclear and coal plants from the 70s & 80s. • Hotspots of freshwater thermal emissions were identified globally. • Global georeferenced emissions are available for use in water temperature models.

  7. Isolation and characterization of the microbial community of a freshwater distribution system

    International Nuclear Information System (INIS)

    Balamurugan, P.; Subba Rao, T.

    2015-01-01

    This investigation provides generic information on culturable and non-culturable microbial community of a freshwater distribution system. Culture based and culture independent (16S rRNA gene sequencing) techniques were used to identify the resident microbial community of the system. Selective isolation of the fouling bacteria such as biofilm formers and corrosion causing bacteria was also attempted. Denaturing gradient gel electrophoresis (DGGE) was carried out and the bands were sequenced to obtain the diversity of the total bacterial types. Pseudomonas aeruginosa was predominantly observed in most of the samples. A variety of bacteria, related to groups such as Cyanobacteria, Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes were identified. The study highlights the relevance of the observed microbial diversity with respect to material deterioration in a freshwater distribution system, which can aid in designing effective control methods. (author)

  8. Systemic granuloma observed in Atlantic salmon Salmo salar raised to market size in a freshwater recirculation aquaculture system

    Science.gov (United States)

    Systemic granuloma was observed in sampled adult Atlantic salmon Salmo salar raised to harvest size in a freshwater recirculation aquaculture system. The prevalence of this condition was estimated at 10-20% of the population, with affected individuals grossly demonstrating pathology in varying degre...

  9. MOIRA: a computerised decision support system for the management of radionuclide contaminated freshwater ecosystems

    International Nuclear Information System (INIS)

    Gallego, Eduardo; Brittain, John E.; Hakanson, Lars; Heling, Rudie; Hofman, Dmitry; Monte, Luigi

    2004-01-01

    The radiation dose resulting from contamination of freshwater ecosystems due to the release of radioactive substances into the environment may be reduced by applying suitable countermeasures. Despite their benefits, intervention strategies may have detrimental effects of economic, ecological and social nature. Thus, it is of paramount importance to assess, by objective criteria, the global cost-benefit balance of different options. The MOIRA project (A MOdel based computerised system for management support to Identify optimal remedial strategies for Restoring radionuclide contaminated Aquatic ecosystems) has developed a user-friendly, computerised tool that will allow decision makers to choose optimal intervention strategies for freshwater ecosystems with different contamination scenarios. The aim of the paper is to briefly describe the main components of the MOIRA system and to demonstrate its application using real case based scenarios. (author)

  10. Microplastics in freshwater systems: a review of the emerging threats, identification of knowledge gaps and prioritisation of research needs.

    Science.gov (United States)

    Eerkes-Medrano, Dafne; Thompson, Richard C; Aldridge, David C

    2015-05-15

    Plastic contamination is an increasing environmental problem in marine systems where it has spread globally to even the most remote habitats. Plastic pieces in smaller size scales, microplastics (particles microplastic presence and interactions are equally as far reaching as are being observed in marine systems. Microplastics are being detected in freshwaters of Europe, North America, and Asia, and the first organismal studies are finding that freshwater fauna across a range of feeding guilds ingest microplastics. Drawing from the marine literature and these initial freshwater studies, we review the issue of microplastics in freshwater systems to summarise current understanding, identify knowledge gaps and suggest future research priorities. Evidence suggests that freshwater systems may share similarities to marine systems in the types of forces that transport microplastics (e.g. surface currents); the prevalence of microplastics (e.g. numerically abundant and ubiquitous); the approaches used for detection, identification and quantification (e.g. density separation, filtration, sieving and infrared spectroscopy); and the potential impacts (e.g. physical damage to organisms that ingest them, chemical transfer of toxicants). Differences between freshwater and marine systems include the closer proximity to point sources in freshwaters, the typically smaller sizes of freshwater systems, and spatial and temporal differences in the mixing/transport of particles by physical forces. These differences between marine and freshwater systems may lead to differences in the type of microplastics present. For example, rivers may show a predictable pattern in microplastic characteristics (size, shape, relative abundance) based on waste sources (e.g. household vs. industrial) adjacent to the river, and distance downstream from a point source. Given that the study of microplastics in freshwaters has only arisen in the last few years, we are still limited in our understanding of 1

  11. Modeling of Energy-saving System of Conditioning Mine Air for Shallow Underground Mines

    Science.gov (United States)

    Nikolaev, Alexandr; Miftakhov, Timur; Nikolaeva, Evgeniya

    2017-11-01

    Mines of Verkhnekamsk potassium-magnesium salt deposit in Perm Krai can be subsumed under shallow mines (depth less than 500 meters). At the present moment in shallow underground mines the are problem of condensate formation in large quantities, when ventilation warm seasons of the year. This problem is more actual for salt mine, where during contact between water and potassium-magnesium ore produced electrolyte, which give rise wear of equipment. For prevent/quantity reduction condensate formation in mine used system of conditioning (refrigerating and dehumidifying) mine air (ACS). However, application this system is limited by reason of tremendous costs of electric energy for their work.

  12. Freshwater Institute: Focused on improving recirculating aquaculture system technology

    Science.gov (United States)

    Recirculating aquaculture system (RAS) technologies help to overcome barriers to domestic aquaculture expansion and enhance the sustainability of the modern fish farming industry through reduction in environmental impacts. With RAS, fish farm expansion is no longer highly constrained by competition ...

  13. Integrating shallow and deep knowledge in the design of an on-line process monitoring system

    Energy Technology Data Exchange (ETDEWEB)

    Gallanti, M.; Gilardoni, L.; Guida, G.; Stefanini, A.; Tomada, L.

    1989-01-01

    Monitoring and malfunctions diagnosis of complex industrial plants involves, in addition to shallow empirical knowledge about plant operation, also deep knowledge about structure and function. This paper presents the results obtained in the design and experimentation of PROP and PROP-2 systems, devoted to on-line monitoring and diagnosis of pollution phenomena in the cycle water of a thermal power plant. In particular, it focuses on PROP-2 architecture, with encompasses a four-level hierarchical knowledge base including both empirical knowledge and a deep model of the plant. Shallow knowledge is represented by production rules and event-graphs (a formalism for expressing procedural knowledge), while deep knowledge is expressed using a representation language based on the concept of component. One major contribution of the proposed approach has been to show in a running experimental system that a suitable blend of shallow and deep knowledge can offer substantial advantages over a single paradigm.

  14. Peracetic acid degradation in freshwater aquaculture systems and possible practical implications

    DEFF Research Database (Denmark)

    Pedersen, Lars-Flemming; Meinelt, Thomas; Straus, David L.

    2013-01-01

    , and it decays rapidly when applied to freshwater in aquaculture systems. The rapid decay is beneficial in an environmental context but a challenge to aquaculturists. To assess the impact of organic matter content and temperature on PAA decay, twenty-four batch experiments were set up using PAA doses ranging...... from 0 to 2.0 mg/l. The results revealed that increasing organic matter content significantly facilitated PAA decay, and positive temperature-decay correlations were found. Instantaneous PAA consumption above 0.2 mg/l was observed, and PAA half-lives were found to be in the order of a few minutes....... The relative PAA recovery, calculated as measured PAA concentration over time compared to the PAA concentration applied, decreased with declining dose. Measurements of PAA residuals during water treatment scenarios at three different freshwater fish farms revealed moderate to substantial PAA consumption...

  15. Numerical Modeling of a Shallow Borehole Thermal Energy Storage System

    Science.gov (United States)

    Catolico, N.; Ge, S.; Lu, N.; McCartney, J. S.

    2014-12-01

    Borehole thermal energy storage (BTES) combined with solar thermal energy harvesting is an economic technological system to garner and store energy as well as an environmentally-sustainable alternative for the heating of buildings. The first community-scale BTES system in North America was installed in 2007 in the Drake Landing Solar Community (DLSC), about 35 miles south of Calgary, Canada. The BTES system involves direct circulation of water heated from solar thermal panels in the summer into a storage tank, after which it is circulate within an array of 144 closed-loop geothermal heat exchangers having a depth of 35 m and a spacing of 2.5 m. In the winter the circulation direction is reversed to supply heat to houses. Data collection over a six year period indicates that this system can supply more than 90% of the winter heating energy needs for 52 houses in the community. One major challenge facing the BTES system technology is the relatively low annual efficiency, i.e., the ratio of energy input and output is in the range of 15% to 40% for the system in Drake Landing. To better understand the working principles of BTES and to improve BTES performance for future applications at larger scales, a three-dimensional transient coupled fluid and heat transfer model is established using TOUGH2. The time-dependent injection temperatures and circulation rate measured over the six years of monitoring are used as model input. The simulations are calibrated using soil temperature data measured at different locations over time. The time-dependent temperature distributions within the borehole region agree well with the measured temperatures for soil with an intrinsic permeability of 10e-19 m2, an apparent thermal conductivity of 2.03 W/m°C, and a volumetric heat capacity of 2.31 MJ/m-3°C. The calibrated model serves as the basis for a sensitivity analysis of soil and operational parameters on BTES system efficiency preformed with TOUGH2. Preliminary results suggest 1) BTES

  16. The importance of shallow hydrothermal island arc systems in ocean biogeochemistry

    NARCIS (Netherlands)

    Hawkes, J.A.; Connelly, D.P.; Rijkenberg, M.J.A.; Achterberg, E.P.

    2014-01-01

    Hydrothermal venting often occurs at submarine volcanic calderas on island arc chains, typically at shallower depths than mid-ocean ridges. The effect of these systems on ocean biogeochemistry has been under-investigated to date. Here we show that hydrothermal effluent from an island arc caldera was

  17. Evidence of plutonium bioavailability in pristine freshwaters of a karst system of the Swiss Jura Mountains

    Science.gov (United States)

    Cusnir, Ruslan; Christl, Marcus; Steinmann, Philipp; Bochud, François; Froidevaux, Pascal

    2017-06-01

    The interaction of trace environmental plutonium with dissolved natural organic matter (NOM) plays an important role on its mobility and bioavailability in freshwater environments. Here we explore the speciation and biogeochemical behavior of Pu in freshwaters of the karst system in the Swiss Jura Mountains. Chemical extraction and ultrafiltration methods were complemented by diffusive gradients in thin films technique (DGT) to measure the dissolved and bioavailable Pu fraction in water. Accelerator mass spectrometry (AMS) was used to accurately determine Pu in this pristine environment. Selective adsorption of Pu (III, IV) on silica gel showed that 88% of Pu in the mineral water is found in +V oxidation state, possibly in a highly soluble [PuO2+(CO3)n]m- form. Ultrafiltration experiments at 10 kDa yielded a similar fraction of colloid-bound Pu in the organic-rich and in mineral water (18-25%). We also found that the concentrations of Pu measured by DGT in mineral water are similar to the bulk concentration, suggesting that dissolved Pu is readily available for biouptake. Sequential elution (SE) of Pu from aquatic plants revealed important co-precipitation of potentially labile Pu (60-75%) with calcite fraction within outer compartment of the plants. Hence, we suggest that plutonium is fully available for biological uptake in both mineral and organic-rich karstic freshwaters.

  18. POP bioaccumulation in macroinvertebrates of alpine freshwater systems

    International Nuclear Information System (INIS)

    Bizzotto, E.C.; Villa, S.; Vighi, M.

    2009-01-01

    This study serves to investigate the uptake of POPs in the different trophic levels (scrapers, collectors, predators, shredders) of macroinvertebrate communities sampled from a glacial and a non-glacial stream in the Italian Alps. The presented results show that the contaminant concentrations in glacial communities are generally higher compared to those from non-glacial catchments, highlighting the importance of glaciers as temporary sinks of atmospherically transported pollutants. Moreover, the data also suggests that in mountain systems snow plays an important role in influencing macroinvertebrate contamination. The main chemical uptake process to the macroinvertebrates is considered to be bioconcentration from water, as similar contaminant profiles were observed between the different trophic levels. The role of biomagnification/bioaccumulation is thought to be absent or negligible. The enrichment of chemicals observed in the predators is likely to be related to their greater lipid content compared to that of other feeding groups. - Influence of POP release in glacial-fed streams, enhanced by global warming, on pristine aquatic ecosystems.

  19. Inferring processes from spatial patterns: the role of directional and non-directional forces in shaping fish larvae distribution in a freshwater lake system.

    Directory of Open Access Journals (Sweden)

    Andrea Bertolo

    Full Text Available Larval dispersal is a crucial factor for fish recruitment. For fishes with relatively small-bodied larvae, drift has the potential to play a more important role than active habitat selection in determining larval dispersal; therefore, we expect small-bodied fish larvae to be poorly associated with habitat characteristics. To test this hypothesis, we used as model yellow perch (Perca flavescens, whose larvae are among the smallest among freshwater temperate fishes. Thus, we analysed the habitat association of yellow perch larvae at multiple spatial scales in a large shallow fluvial lake by explicitly modelling directional (e.g. due to water currents and non-directional (e.g. due to aggregation spatial patterns. This allowed us to indirectly assess the relative roles of drift (directional process and potential habitat choice on larval dispersal. Our results give weak support to the drift hypothesis, whereas yellow perch show a strong habitat association at unexpectedly small sizes, when compared to other systems. We found consistent non-directional patterns in larvae distributions at both broad and medium spatial scales but only few significant directional components. The environmental variables alone (e.g. vegetation generally explained a significant and biologically relevant fraction of the variation in fish larvae distribution data. These results suggest that (i drift plays a minor role in this shallow system, (ii larvae display spatial patterns that only partially covary with environmental variables, and (iii larvae are associated to specific habitats. By suggesting that habitat association potentially includes an active choice component for yellow perch larvae, our results shed new light on the ecology of freshwater fish larvae and should help in building more realistic recruitment models.

  20. Status, trends, and changes in freshwater inflows to bay systems in the Corpus Christi Bay National Estuary Program study area

    Science.gov (United States)

    Asquith, W.H.; Mosier, J. G.; Bush, P.W.

    1997-01-01

    This report presents the results of a study to quantify current (1983–93) mean freshwater inflows to the six bay systems (open water and wetlands) in the Corpus Christi Bay National Estuary Program study area, to test for historical temporal trends in inflows, and to quantify historical and projected changes in inflows. The report also addresses the adequacy of existing data to estimate freshwater inflows.

  1. Predictive capabilities of the specific activity hypothesis for Cs and Zn in freshwater systems

    International Nuclear Information System (INIS)

    Seelye, J.G.

    1975-01-01

    Predictions of radioisotope concentrations in components of aquatic systems have been attempted using the specific activity concept, an approach that seems theoretically sound. A comprehensive examination of the specific activities of 134 Cs and 65 Zn in the components of a freshwater system, over a 10 month period, was conducted to evaluate the specific activity hypothesis under applied conditions. This study was designed to provide comparisons of predicted and observed specific activities and to test the equivalence of specific activities between all components of the system. One dose of radioisotopes was added to the system in this study and even after 10 months these radioisotopes were not distributed similarly to the stable isotopes. This suggests that the time necessary to reach a specific activity equilibrium might be a matter of years rather than months. More importantly, in natural systems, where the radioisotope addition is continuous a specific activity equilibrium may never be achieved. These things plus the non-conservative nature of the 134 Cs and 65 Zn predicted concentrations indicates that the use of the specific activity concept for predicting radioisotope concentrations of Cs and Zn in freshwater systems is questionable. A more rigorous approach must be used, considering isotope transfer rates between components and the complexity of the system. Problems with statistical comparisons of derived variables, such as specific activities, are discussed and were considered in interpreting the results of this study

  2. System analysis of shallow land burial. Volume 2: technical background. Technical report, 26 November 1979-23 January 1981

    International Nuclear Information System (INIS)

    Lester, D.; Buckley, D.; Donelson, S.; Dura, V.; Hecht, M.

    1981-03-01

    This is volume two of a three volume set detailing the activities and results of the System Analysis of Shallow Land Burial Project. Activities under four project tasks are described: Task 1 - Identify Potential Radionuclide Release Pathways, Task 2 - Systems Model for Shallow Land Burial of Low-Level Waste, Task 3 - Sensitivity and Optimization Study and Task 4 - Reference Facility Dose Assessment

  3. Nonradiative recombination onto shallow bound states in confined systems in electric field

    International Nuclear Information System (INIS)

    Sinyavskij, Eh.P.; Rusanov, A.M.

    1999-01-01

    A study has been made of the one-phonon recombination of carriers onto shallow impurity states in parabolic quantum wells in the longitudinal electric field. It has been found that processes of the one-phonon recombination in confined systems occur in a more active way the in a bulk material.The possibility of electrically induced one-quantum transitions in confined systems is being discussed

  4. Freshwater gastropods of Neogene and Quaternary lake systems of Europe - state of the art and outlook

    Science.gov (United States)

    Neubauer, Thomas A.; Harzhauser, Mathias; Mandic, Oleg; Kroh, Andreas

    2013-04-01

    Globally, about 4000 extant species of freshwater gastropod species have been described. In contrast, only 225 species are listed by MollBase2012 for North- and Central Europe. Many of these are rare species, limited to certain springs and in fact the typical diversity of gastropods in lakes of North and Central Europe is much lower. The high number is boosted by several highly speciose endemic radiations in long-lived ancient lakes, which are hotspots for biodiversity. These long-lived ancient lakes provide key examples for understanding evolutionary processes and therefore are intensively studied. During the Neogene, Europe's geodynamic history gave rise to several such long-lived lakes with conspicuous endemic radiations. However, these lacustrine systems are rare today as well as in the past compared to the enormous numbers of "normal" lakes. Most extant European lakes are mainly results of the Ice Ages and are due to their geologically temporary nature largely confined to the Pleistocene-Holocene. Also deposits of streams, springs, and groundwater, which today are inhabited by species-rich gastropod assemblages, are rarely preserved. Thus, the pre-Quaternary lacustrine record is biased towards long-lived systems. Apart from few general overviews precise studies on the γ-diversities of the post-Oligocene European lake systems and the shifting biodiversity in European freshwater systems through space and time are entirely missing. Even for the modern faunas, literature on large-scale freshwater gastropod diversity in extant lakes is scarce and lacks a statistical approach. Building upon a great amount of existing literature, a new project will provide the first detailed assessment of the composition of European freshwater gastropods during the Neogene and Quaternary at species, genus and family levels, with emphasis on lake faunas. The γ-diversity of several hundred modern and fossil European lakes will be evaluated. Data will be made available permanently for

  5. Radioactivity in freshwater systems in Cumbria (UK) following the Chernobyl accident

    International Nuclear Information System (INIS)

    Camplin, W.C.; Leonard, D.R.P.; Tipple, J.R.; Duckett, L.

    1989-01-01

    Sampling of fish, water, sediments and plants was carried out in freshwater systems in Cumbria (UK) to study the effects of Chernobyl fallout. Radionuclide concentrations were determined by gamma spectrometry and potassium and calcium ion concentrations in water were measured using atomic absorption spectrometry. The results contained in this report cover the period May 1986-March 1988. Caesium-134 and -137 were readily detected in all materials but ruthenium-103 and -106 were also found in a few samples. Trends in caesium concentrations in fish are difficult to establish because of the wide variation between fish of the same species. (author)

  6. 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

  7. How biological (fish) noise affects the performance of shallow water passive array system

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, W.A.; Chakraborty, B.; Haris, K.; Vijayakumar, K.; Sundar, D.; Luis, R.A.A.; Mahanty, M.M.; Latha, G.

    =UTF-8 How biological (fish) noise affects the performance of shallow water passive array system William Fernandes, Bishwajit Chakraborty, K. Haris, K. Vijaykumar, D. Sundar, R.A.A. Luis CSIR-National Institute of Oceanography, Dona Paula... source distribution as well as the environmental parameters (i.e., water depth, sound speed profile, and seafloor properties). In a waveguide bounded by sea surface and seabed, multipath propagation prevails and the spatial structure of the noise...

  8. Performance of rocking systems on shallow improved sand: Shaking table testing

    Directory of Open Access Journals (Sweden)

    Angelos eTsatsis

    2015-07-01

    Full Text Available Recent studies have highlighted the potential benefits of inelastic foundation response during seismic shaking. According to an emerging seismic design scheme, termed rocking isolation, the foundation is intentionally under–designed to promote rocking and limit the inertia transmitted to the structure. Such reversal of capacity design may improve the seismic performance, drastically increasing the safety margins. However, the benefit comes at the expense of permanent settlement and rotation, which may threaten post-earthquake functionality. Such undesired deformation can be maintained within tolerable limits, provided that the safety factor against vertical loading FSV is adequately large. In such a case, the response is uplifting–dominated and the accumulation of settlement can be limited. However, this is not always feasible as the soil properties may not be ideal. Shallow soil improvement may offer a viable solution and is therefore worth investigating. Its efficiency is related to the nature of rocking, which tends to mobilize a shallow stress bulb. To this end, a series of shaking table tests are conducted, using an idealized slender bridge pier as conceptual prototype. Two systems are studied, both lying on a square foundation of width B. The first corresponds to a lightly-loaded and the second to a heavily-loaded structure. The two systems are first tested on poor and ideal soil conditions to demonstrate the necessity for soil improvement. Then, the efficiency of shallow soil improvement is studied by investigating their performance on soil crusts of depth z/B = 0.5 and 1. It is shown that a z/B = 1 dense sand crust is enough to achieve practically the same performance with the ideal case of dense sand. A shallower z/B = 0.5 improvement layer may also be considered, depending on design requirements. The efficiency of the soil improvement is ameliorated with the increase of rotation amplitude, and with the number of the cycles of the

  9. Reconciled freshwater flux into the Godthåbsfjord system from satellite and airborne remote sensing

    DEFF Research Database (Denmark)

    Simonsen, Sebastian Bjerregaard; Barletta, Valentina Roberta; Forsberg, René

    2015-01-01

    IS hamper in situ observations. Here, we evaluate available data from remote sensing and find a drainage basin in rapid change. An analysis of data from the Gravity Recovery and Climate Experiment (GRACE) satellites shows a mean seasonal freshwater flux into Godthåbsfjord of 18.2 ± 1.2 Gt, in addition......, from various remote-sensing data sets, estimate the freshwater flux from the GrIS into a specific fjord system, the Godthåbsfjord, in southwest Greenland. The area of the GrIS draining into Godthåbsfjord covers approximately 36,700 km2. The large areal extent and the multiple outlets from the Gr...... to an imbalance in the mass balance of the drainage basin from 2003 to 2013 of 14.4 ± 0.2 Gt year−1. Altimetry data from air and spaceborne missions also suggest rapid changes in the outlet glacier dynamics. We find that only applying data from the Ice, Cloud, and land Elevation Satellite (ICESat) mission...

  10. Goose-mediated nutrient enrichment and planktonic grazer control in arctic freshwater ponds

    NARCIS (Netherlands)

    Van Geest, G. J.; Hessen, D. O.; Spierenburg, P.; Dahl-Hansen, G. A. P.; Christensen, G.; Faerovig, P. J.; Brehm, M.; Loonen, M. J. J. E.; Van Donk, E.

    A dramatic increase in the breeding population of geese has occurred over the past few decades at Svalbard. This may strongly impact the fragile ecosystems of the Arctic tundra because many of the ultra-oligotrophic freshwater systems experience enrichment from goose feces. We surveyed 21 shallow

  11. A Complex System of Glacial Sub-Refugia Drives Endemic Freshwater Biodiversity on the Tibetan Plateau.

    Science.gov (United States)

    Clewing, Catharina; Albrecht, Christian; Wilke, Thomas

    2016-01-01

    Although only relatively few freshwater invertebrate families are reported from the Tibetan Plateau, the degree of endemism may be high. Many endemic lineages occur within permafrost areas, raising questions about the existence of isolated intra-plateau glacial refugia. Moreover, if such refugia existed, it might be instructive to learn whether they were associated with lakes or with more dynamic ecosystems such as ponds, wetlands, or springs. To study these hypotheses, we used pulmonate snails of the plateau-wide distributed genus Radix as model group and the Lake Donggi Cona drainage system, located in the north-eastern part of the plateau, as model site. First, we performed plateau-wide phylogenetic analyses using mtDNA data to assess the overall relationships of Radix populations inhabiting the Lake Donggi Cona system for revealing refugial lineages. We then conducted regional phylogeographical analyses applying a combination of mtDNA and nuclear AFLP markers to infer the local structure and demographic history of the most abundant endemic Radix clade for identifying location and type of (sub-)refugia within the drainage system. Our phylogenetic analysis showed a high diversity of Radix lineages in the Lake Donggi Cona system. Subsequent phylogeographical analyses of the most abundant endemic clade indicated a habitat-related clustering of genotypes and several Late Pleistocene spatial/demographic expansion events. The most parsimonious explanation for these patterns would be a scenario of an intra-plateau glacial refugium in the Lake Donggi Cona drainage system, which might have consisted of isolated sub-refugia. Though the underlying processes remain unknown, an initial separation of lake and watershed populations could have been triggered by lake-level fluctuations before and during the Last Glacial Maximum. This study inferred the first intra-plateau refugium for freshwater animals on the Tibetan Plateau. It thus sheds new light on the evolutionary history

  12. Some exact solutions to the potential Kadomtsev-Petviashvili equation and to a system of shallow water wave equations

    International Nuclear Information System (INIS)

    Inan, Ibrahim E.; Kaya, Dogan

    2006-01-01

    In this Letter by considering an improved tanh function method, we found some exact solutions of the potential Kadomtsev-Petviashvili equation. Some exact solutions of the system of the shallow water wave equation were also found

  13. Energy balance and economic feasibility of shallow geothermal systems for winery industry

    Science.gov (United States)

    Ruiz-Mazarrón, F.; Almoguera-Millán, J.; García-Llaneza, J.; Perdigones, A.

    2012-04-01

    The search of energy efficient solutions has not yet been accomplished in agro-food constructions, for which technical studies and orientations are needed to find energy efficient solutions adapted to the environment. The main objective of this investigation is to evaluate the effectiveness of using shallow geothermal energy for the winery industry. World wine production in 2009 stood at 27100 millions of litres [1]. World spends 320 billion Euros on wine a year, according to industry insiders. On average, it is estimated that producing 1 litre of wine sold in a 75 cl glass bottle costs around 0.5-1.2 Euros /litre [2]. The process of ageing the wine could substantially increase production costs. Considering the time required for the aging of wine (months or years) and the size of the constructions, the use of an air conditioning system implies a considerable increase in energy consumption. Underground wine cellars have been in use for centuries for making and ageing wine. Ground thermal inertia provides protection from outdoor temperature oscillation and maintains thermal stability without energy consumption [3]. Since the last century, production of wine has moved to buildings above ground that have several advantages: lower construction cost, more space, etc. Nevertheless, these constructions require a large energy consumption to maintain suitable conditions for the ageing and conservation of wine. This change of construction techniques is the cause of an increase in energy consumption in modern wineries. The use of shallow geothermal energy can be a good alternative to take advantage of the benefits of aboveground buildings and underground constructions simultaneously. Shallow geothermal systems can meet the needs of heating and cooling using a single installation, maintaining low energy consumption. Therefore, it could be a good alternative to conventional HVAC systems. The main disadvantage of geothermal systems is the high cost of investment required. This

  14. Channel Formation in Physical Experiments: Examples from Deep and Shallow Water Clastic Sedimentary Systems

    Science.gov (United States)

    Hoyal, D. C.; Sheets, B. A.

    2005-12-01

    The degree to which experimental sedimentary systems form channels has an important bearing on their applicability as analogs of large-scale natural systems, where channels and their associated landforms are ubiquitous. The internal geometry and properties (e.g., grain size, vertical succession and stacking) of many depositional landforms can be directly linked to the processes of channel initiation and evolution. Unfortunately, strong self-channelization, a prerequisite for certain natural phenomena (e.g. mouth lobe development, meandering, etc.), has been difficult to reproduce at laboratory scales. In shallow-water experiments (sub-aerial), although weak channelization develops relatively easily, as is commonly observed in gutters after a rain storm, strong channelization with well-developed banks has proved difficult to model. In deep water experiments the challenge is even greater. Despite considerable research effort experimental conditions for deep water channel initiation have only recently been identified. Experiments on the requisite conditions for channelization in shallow and deep water have been ongoing at the ExxonMobil Upstream Research Company (EMURC) for several years. By primarily manipulating the cohesiveness of the sediment supply we have developed models of distributive systems with well-defined channels in shallow water, reminiscent of fine grained river-dominated deltas like the Mississippi. In deep water we have developed models that demonstrate strong channelization and associated lobe behavior in a distributive setting, by scaling up an approach developed by another group using salt-water flows and low-density plastic sediment. The experiments highlight a number of important controls on experimental channel formation, including: (1) bed strength or cohesiveness; (2) bedform development; and (3) Reynolds number. Among these controls bed forms disrupt the channel forming instability, reducing the energy available for channelization. The

  15. Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

    Science.gov (United States)

    Zhang, Yao; Zhao, Zihao; Chen, Chen-Tung Arthur; Tang, Kai; Su, Jianqiang; Jiao, Nianzhi

    2012-01-01

    To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4)) concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4) was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH(4) concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan.

  16. Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

    Directory of Open Access Journals (Sweden)

    Yao Zhang

    Full Text Available To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4 concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4 was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH(4 concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan.

  17. Microplastics in freshwater systems: A review on occurrence, environmental effects, and methods for microplastics detection.

    Science.gov (United States)

    Li, Jingyi; Liu, Huihui; Paul Chen, J

    2018-06-15

    The continuous increase in synthetic plastic production and poor management in plastic waste have led to a tremendous increase in the dumping into our aqueous environment. Consequently, microplastics commonly defined as sizes less than 5 mm are produced and stay in both seawater and freshwater environment. The presence of microplastics as a new type of emerging contaminant has become a great issue of concerns from public and government authorities. The sources of microplastics to freshwater systems are many with the largest portion from wastewater treatment plants. The abundance of microplastics varies with the location, from above 1 million pieces per cubic meter to less than 1 piece in 100 cubic meters. Microplastics can cause several harmful physical effects on humans and living organisms through such mechanisms as entanglement and ingestion. The microplastics can act as carriers of various toxins such as additives from industrial production processes and persistent contaminants by the sorption in waters. Those toxins may cause great health problems to humans. A few studies on the fishes demonstrated that the microplastics and the associated toxins are bio-accumulated and cause such problems as intestinal damage and change in metabolic profiles. In studies of microplastics, fresh water is first sampled by the nets with typical mesh size of 330 μm for collection of microplastics. After the volume reducing process, the samples will then go through the purification process including density separation by such inorganic salts as sodium chloride and digestion process by oxidizing agents or enzymes. The sequence of these two processes (namely purification and digestion) is dependent on the sample type. The purified samples can be studied by several analytical methods. The commonly used methods for the qualification studies are FTIR spectroscopy, Raman spectroscopy, pyrolysis-GC/MS, and liquid chromatography. A tagging method can be used in the quantification

  18. Relative Importance of Chemoautotrophy for Primary Production in a Light Exposed Marine Shallow Hydrothermal System

    Directory of Open Access Journals (Sweden)

    Gonzalo V. Gomez-Saez

    2017-04-01

    Full Text Available The unique geochemistry of marine shallow-water hydrothermal systems promotes the establishment of diverse microbial communities with a range of metabolic pathways. In contrast to deep-sea vents, shallow-water vents not only support chemosynthesis, but also phototrophic primary production due to the availability of light. However, comprehensive studies targeting the predominant biogeochemical processes are rare, and consequently a holistic understanding of the functioning of these ecosystems is currently lacking. To this end, we combined stable isotope probing of lipid biomarkers with an analysis of the bacterial communities to investigate if chemoautotrophy, in parallel to photoautotrophy, plays an important role in autotrophic carbon fixation and to identify the key players. The study was carried out at a marine shallow-water hydrothermal system located at 5 m water depth off Dominica Island (Lesser Antilles, characterized by up to 55°C warm hydrothermal fluids that contain high amounts of dissolved Fe2+. Analysis of the bacterial diversity revealed Anaerolineae of the Chloroflexi as the most abundant bacterial class. Furthermore, the presence of key players involved in iron cycling generally known from deep-sea hydrothermal vents (e.g., Zetaproteobacteria and Geothermobacter, supported the importance of iron-driven redox processes in this hydrothermal system. Uptake of 13C-bicarbonate into bacterial fatty acids under light and dark conditions revealed active photo- and chemoautotrophic communities, with chemoautotrophy accounting for up to 65% of the observed autotrophic carbon fixation. Relatively increased 13C-incorporation in the dark allowed the classification of aiC15:0, C15:0, and iC16:0 as potential lipid biomarkers for bacterial chemoautotrophy in this ecosystem. Highest total 13C-incorporation into fatty acids took place at the sediment surface, but chemosynthesis was found to be active down to 8 cm sediment depth. In conclusion

  19. Radionuclide mobility in the shallow portion of an active high-temperature geothermal system

    International Nuclear Information System (INIS)

    Sturchio, N.C.; Seitz, M.G.

    1984-01-01

    Accurate knowledge of the behavior of radionuclides in natural rock-water systems is crucial for the prediction of the consequences of failure of a high-level nuclear waste repository. Work in progress at Argonne National Laboratory involves the detailed geochemical analysis of rock, mineral, and water samples from shallow drill holes in a thermal area of Yellowstone National Park. This study is designed to provide data that will increase our understanding of the behavior of a group of radionuclides in an environment similar to that of the near field of a high-level nuclear waste repository

  20. A nearly orthogonal 2D grid system in solving the shallow water equations in the head bay of Bengal

    International Nuclear Information System (INIS)

    Roy, G.D. . E.mail: roy_gd@hotmail.com; Hussain, Farzana . E.mail: farzana@sust.edu

    2001-11-01

    A typical nearly orthogonal grid system is considered to solve the shallow water equations along the head bay of Bengal. A pencil of straight lines at uniform angular distance through a suitable origin, O at the mean sea level (MSL), are considered as a system of grid lines. A system of concentric and uniformly distributed ellipses with center at O is considered as the other system of grid lines. In order to solve the shallow water equations numerically, a system of transformations is applied so that the grid system in the transformed domain becomes a rectangular one. Shallow water equations are solved using appropriate initial and boundary conditions to estimate the water level due to tide and surge. The typical grid system is found to be suitable in incorporating the bending of the coastline and the island boundaries accurately in the numerical scheme along the coast of Bangladesh. (author)

  1. Hydrogeology in the area of a freshwater lens in the Floridan aquifer system, northeast Seminole County, Florida

    Science.gov (United States)

    Phelps, G.G.; Rohrer, K.P.

    1987-01-01

    Northeast Seminole County, Florida, contains an isolated recharge area of the Floridan aquifer system that forms a freshwater lens completely surrounded by saline water. The freshwater lens covers an area of about 22 sq mi surrounding the town of Geneva, and generally is enclosed by the 25 ft land surface altitude contour. Thickness of the lens is about 350 ft in the center of the recharge area. The geohydrologic units in descending order consist of the post-Miocene sand and shell of the surficial aquifer; Miocene clay, sand, clay, and shell that form a leaky confining bed; and permeable Eocene limestones of the Floridan aquifer system. The freshwater lens is the result of local rainfall flushing ancient seawater from the Floridan aquifer system. Sufficient quantities of water for domestic and small public supply systems are available from the Floridan aquifer system in the Geneva area. The limiting factor for water supply in the area is the chemical quality of the water. Chloride concentrations range from recharge area to about 5,100 mg/L near the St. Johns River southeast of Geneva. Constituents analyzed included sulfate (range 1 to 800 mg/L), hardness (range 89 to 2,076 mg/L), and iron (range 34 to 6,600 mg/L). Because the freshwater lens results entirely from local recharge, the long-term sustained freshwater yield of the aquifer in the Geneva area depends on the local recharge rate. In 1982, recharge was about 13 inches (13.8 million gal/day). Average recharge for 1941 through 1970 was estimated to be about 11 inches (11.3 million gal/day). Freshwater that recharges the aquifer in the Geneva area is either pumped out or flows north and northeast to discharge near or in the St. Johns River. Average annual outflow from the lens is about 10 in/yr. No measurable change in the size or location of the freshwater lens has occurred since studies in the early 1950's. (Lantz-PTT)

  2. 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.

  3. Shallow freshwater ecosystems of the circumpolar Arctic

    DEFF Research Database (Denmark)

    Rautio, Milla; Dufresne, France; Laurion, Isabelle

    2011-01-01

    to large annual temperature fluctuations, a short growing season, and freeze-up and desiccation stress in winter, these ecosystems are strongly regulated by the supply of organic matter and its optical and biogeochemical properties. Dissolved organic carbon affects bacterial diversity and production......This review provides a synthesis of limnological data and conclusions from studies on ponds and small lakes at our research sites in Subarctic and Arctic Canada, Alaska, northern Scandinavia, and Greenland. Many of these water bodies contain large standing stocks of benthic microbial mats that grow...... in relatively nutrient-rich conditions, while the overlying water column is nutrient-poor and supports only low concentrations of phytoplankton. Zooplankton biomass can, however, be substantial and is supported by grazing on the microbial mats as well as detrital inputs, algae, and other plankton. In addition...

  4. Shallow water processes govern system-wide phytoplankton bloom dynamics: A modeling study

    Science.gov (United States)

    Lucas, L.V.; Koseff, Jeffrey R.; Monismith, Stephen G.; Thompson, J.K.

    2009-01-01

    A pseudo-two-dimensional numerical model of estuarine phytoplankton growth and consumption, vertical turbulent mixing, and idealized cross-estuary transport was developed and applied to South San Francisco Bay. This estuary has two bathymetrically distinct habitat types (deep channel, shallow shoal) and associated differences in local net rates of phytoplankton growth and consumption, as well as differences in the water column's tendency to stratify. Because many physical and biological time scales relevant to algal population dynamics decrease with decreasing depth, process rates can be especially fast in the shallow water. We used the model to explore the potential significance of hydrodynamic connectivity between a channel and shoal and whether lateral transport can allow physical or biological processes (e.g. stratification, benthic grazing, light attenuation) in one sub-region to control phytoplankton biomass and bloom development in the adjacent sub-region. Model results for South San Francisco Bay suggest that lateral transport from a productive shoal can result in phytoplankton biomass accumulation in an adjacent deep, unproductive channel. The model further suggests that turbidity and benthic grazing in the shoal can control the occurrence of a bloom system-wide; whereas, turbidity, benthic grazing, and vertical density stratification in the channel are likely to only control local bloom occurrence or modify system-wide bloom magnitude. Measurements from a related field program are generally consistent with model-derived conclusions. ?? 2008 Elsevier B.V.

  5. Septic Systems Contribution to Phosphorus in Shallow Groundwater: Field-Scale Studies Using Conventional Drainfield Designs

    Science.gov (United States)

    Mechtensimer, Sara

    2017-01-01

    Septic systems can be a potential source of phosphorus (P) in groundwater and contribute to eutrophication in aquatic systems. Our objective was to investigate P transport from two conventional septic systems (drip dispersal and gravel trench) to shallow groundwater. Two new in-situ drainfields (6.1 m long by 0.61 m wide) with a 3.72 m2 infiltrative surface were constructed. The drip dispersal drainfield was constructed by placing 30.5 cm commercial sand on top of natural soil and the gravel trench drainfield was constructed by placing 30.5 cm of gravel on top of 30.5 cm commercial sand and natural soil. Suction cup lysimeters were installed in the drainfields (at 30.5, 61, 106.7 cm below infiltrative surface) and piezometers were installed in the groundwater (>300 cm below infiltrative surface) to capture P dynamics from the continuum of unsaturated to saturated zones in the septic systems. Septic tank effluent (STE), soil-water, and groundwater samples were collected for 64 events (May 2012–Dec 2013) at 2 to 3 days (n = 13), weekly (n = 29), biweekly (n = 17), and monthly (n = 5) intervals. One piezometer was installed up-gradient of the drainfields to monitor background groundwater (n = 15). Samples were analyzed for total P (TP), orthophosphate-P (PO4–P), and other–P (TP—PO4-P). The gravel trench drainfield removed significantly (p300 cm in the groundwater, both systems had similar TP reductions of >97%. After 18 months of STE application, there was no significant increase in groundwater TP concentrations in both systems. We conclude that both drainfield designs are effective at reducing P transport to shallow groundwater. PMID:28107505

  6. Septic Systems Contribution to Phosphorus in Shallow Groundwater: Field-Scale Studies Using Conventional Drainfield Designs.

    Directory of Open Access Journals (Sweden)

    Sara Mechtensimer

    Full Text Available Septic systems can be a potential source of phosphorus (P in groundwater and contribute to eutrophication in aquatic systems. Our objective was to investigate P transport from two conventional septic systems (drip dispersal and gravel trench to shallow groundwater. Two new in-situ drainfields (6.1 m long by 0.61 m wide with a 3.72 m2 infiltrative surface were constructed. The drip dispersal drainfield was constructed by placing 30.5 cm commercial sand on top of natural soil and the gravel trench drainfield was constructed by placing 30.5 cm of gravel on top of 30.5 cm commercial sand and natural soil. Suction cup lysimeters were installed in the drainfields (at 30.5, 61, 106.7 cm below infiltrative surface and piezometers were installed in the groundwater (>300 cm below infiltrative surface to capture P dynamics from the continuum of unsaturated to saturated zones in the septic systems. Septic tank effluent (STE, soil-water, and groundwater samples were collected for 64 events (May 2012-Dec 2013 at 2 to 3 days (n = 13, weekly (n = 29, biweekly (n = 17, and monthly (n = 5 intervals. One piezometer was installed up-gradient of the drainfields to monitor background groundwater (n = 15. Samples were analyzed for total P (TP, orthophosphate-P (PO4-P, and other-P (TP-PO4-P. The gravel trench drainfield removed significantly (p300 cm in the groundwater, both systems had similar TP reductions of >97%. After 18 months of STE application, there was no significant increase in groundwater TP concentrations in both systems. We conclude that both drainfield designs are effective at reducing P transport to shallow groundwater.

  7. The role of freshwater habitats for the reproduction of common bream Abramis brama (L.) in a brackish water system

    Science.gov (United States)

    Kafemann, R.; Thiel, R.; Finn, J.E.; Neukamm, R.

    1998-01-01

    Abundance and biomass data for juveniles and adults, length frequency histograms and the electron microprobe analysis (EPMA) of otoliths were used to indicate density, migration and reproduction of common bream Abramis brama in the Kiel Canal drainage, Germany. The reproduction of common bream was primarily restricted to two types of spawning habitats: one in the Haaler Au, a freshwater tributary and another in shallow, oligohaline portion of the main Canal. Both spawning habitats were morphologically characterized as shallow with submerged vegetation. During April to June concentrations of spawners were observed, whereas age-0 common bream dominated from August through December. The distribution of age-0 common bream was primarily restricted to fresh and oligohaline waters. Outside the spawning season, the distribution of common bream was less obvious. Adult fish were more widely distributed within the Canal, indicating a tolerance for higher salinities. During the spawning season common bream seem to show an exceptional mobility between spawning and feeding habitats, which are denoted by different salinities.

  8. First report of the successful operation of a side stream supersaturation hypolimnetic oxygenation system in a eutrophic, shallow reservoir.

    Science.gov (United States)

    Gerling, Alexandra B; Browne, Richard G; Gantzer, Paul A; Mobley, Mark H; Little, John C; Carey, Cayelan C

    2014-12-15

    Controlling hypolimnetic hypoxia is a key goal of water quality management. Hypoxic conditions can trigger the release of reduced metals and nutrients from lake sediments, resulting in taste and odor problems as well as nuisance algal blooms. In deep lakes and reservoirs, hypolimnetic oxygenation has emerged as a viable solution for combating hypoxia. In shallow lakes, however, it is difficult to add oxygen into the hypolimnion efficiently, and a poorly designed hypolimnetic oxygenation system could potentially result in higher turbidity, weakened thermal stratification, and warming of the sediments. As a result, little is known about the viability of hypolimnetic oxygenation in shallow bodies of water. Here, we present the results from recent successful tests of side stream supersaturation (SSS), a type of hypolimnetic oxygenation system, in a shallow reservoir and compare it to previous side stream deployments. We investigated the sensitivity of Falling Creek Reservoir, a shallow (Zmax = 9.3 m) drinking water reservoir located in Vinton, Virginia, USA, to SSS operation. We found that the SSS system increased hypolimnetic dissolved oxygen concentrations at a rate of ∼1 mg/L/week without weakening stratification or warming the sediments. Moreover, the SSS system suppressed the release of reduced iron and manganese, and likely phosphorus, from the sediments. In summary, SSS systems hold great promise for controlling hypolimnetic oxygen conditions in shallow lakes and reservoirs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Cascade ultrafiltering of 210Pb and 210Po in freshwater using a tangential flow filtering system

    International Nuclear Information System (INIS)

    Ohtsuka, Y.; Takaku, Y.; Hisamatsu, S.; Inaba, J.; Yamamoto, M.

    2006-01-01

    A rapid method was developed using ultrafilters with a tangential flow filtering system for molecular size separation of naturally occurring 210 Pb and 210 Po in a freshwater sample. Generally, ultrafiltering of a large volume water sample for measuring the nuclides was too time consuming and not practical. The tangential flow filtering system made the filtering time short enough to adapt for in-situ ultrafiltering the large volume sample. In this method, a 20 liter water sample was at first passed through the 0.45 μm pore size membrane filter immediately after sample collection to obtain suspended particle matter [>0.45 μm particulate fraction (PRT)]. Two ultrafilters (Millipore Pellicon 2 R ) were used sequentially. The nuclides in the filtrate were separated into three fractions: high molecular mass (100 kDa-0.45μm; HMM), low molecular mass (10 k-100 kDa; LMM) and ionic ( 210 Pb and 210 Po in an oligotrophic lake, Lake Towada located in the northern area of Japan. (author)

  10. Gulf-Wide Information System, Environmental Sensitivity Index Freshwater Fish Database, Geographic NAD83, LDWF (2001) [esi_freshwater_fish_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains sensitive biological resource data for freshwater (inland) fish species in coastal Louisiana. Vector polygons represent water-bodies and other...

  11. Insight from Genomics on Biogeochemical Cycles in a Shallow-Sea Hydrothermal System

    Science.gov (United States)

    Lu, G. S.; Amend, J.

    2015-12-01

    Shallow-sea hydrothermal ecosystems are dynamic, high-energy systems influenced by sunlight and geothermal activity. They provide accessible opportunities for investigating thermophilic microbial biogeochemical cycles. In this study, we report biogeochemical data from a shallow-sea hydrothermal system offshore Paleochori Bay, Milos, Greece, which is characterized by a central vent covered by white microbial mats with hydrothermally influenced sediments extending into nearby sea grass area. Geochemical analysis and deep sequencing provide high-resolution information on the geochemical patterns, microbial diversity and metabolic potential in a two-meter transect. The venting fluid is elevated in temperature (~70oC), low in pH (~4), and enriched in reduced species. The geochemical pattern shows that the profile is affected by not only seawater dilution but also microbial regulation. The microbial community in the deepest section of vent core (10-12 cm) is largely dominated by thermophilic archaea, including a methanogen and a recently described Crenarcheon. Mid-core (6-8 cm), the microbial community in the venting area switches to the hydrogen utilizer Aquificae. Near the sediment-water interface, anaerobic Firmicutes and Actinobacteria dominate, both of which are commonly associated with subsurface and hydrothermal sites. All other samples are dominated by diverse Proteobacteria. The sulfate profile is strongly correlated with the population size of delta- and episilon-proteobactia. The dramatic decrease in concentrations of As and Mn in pore fluids as a function of distance from the vent suggests that in addition to seawater dilution, microorganisms are likely transforming these and other ions through a combination of detoxification and catabolism. In addition, high concentrations of dissolved Fe are only measurable in the shallow sea grass area, suggesting that iron-transforming microorganisms are controlling Fe mobility, and promoting biomineralization. Taken

  12. An optimized and simplified method for analysing urea and ammonia in freshwater aquaculture systems

    DEFF Research Database (Denmark)

    Larsen, Bodil Katrine; Dalsgaard, Anne Johanne Tang; Pedersen, Per Bovbjerg

    2015-01-01

    This study presents a simple urease method for analysis of ammonia and urea in freshwater aquaculture systems. Urea is hydrolysed into ammonia using urease followed by analysis of released ammonia using the salicylate-hypochlorite method. The hydrolysis of urea is performed at room temperature...... and without addition of a buffer. A number of tests were performed on water samples obtained from a commercial rainbow trout farm to determine the optimal urease concentration and time for complete hydrolysis. One mL of water sample was spiked with 1.3 mL urea at three different concentrations: 50 lg L 1, 100...... lg L 1 and 200 lg L 1 urea-N. In addition, five concentrations of urease were tested, ranging from 0.1 U mL 1 to 4 U mL 1. Samples were hydrolysed for various time periods ranging from 5 to 120 min. A urease concentration of 0.4 U mL 1 and a hydrolysis period of 120 min gave the best results, with 99...

  13. Evaluation of Dicentrarchus labrax meats and the vegetable quality of Beta vulgaris var. Cicla farmed in freshwater and saltwater aquaponic systems

    OpenAIRE

    Nozzi, Valentina; Parisi, Giuliana; Di Crescenzo, Davide; Giordano, Mario; Carnevali, Oliana

    2016-01-01

    The purpose of this study is to exploit the euryhaline nature of commercially attractive species for their cultivation in freshwater aquaponic systems. This approach may increase the profitability of aquaponic production in coastal countries where the consumption of marine fish is traditional and of commercial relevance. For this purpose, juvenile European sea bass (Dicentrarchus labrax) were reared in an aquaponic freshwater (AFW) system and an aquaponic saltwater (ASW) system (salinity 20 p...

  14. Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

    International Nuclear Information System (INIS)

    Chen, W.-Y.; Tsai, J.-W.; Ju, Y.-R.; Liao, C.-M.

    2010-01-01

    The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

  15. Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.-Y. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Tsai, J.-W. [Institute of Ecology and Evolutionary Ecology, China Medical University, Taichung 40402, Taiwan (China); Ju, Y.-R. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Liao, C.-M., E-mail: cmliao@ntu.edu.t [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2010-05-15

    The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

  16. MOIRA: a computerised decision support system for the restoration of radionuclide contaminated freshwater ecosystems

    International Nuclear Information System (INIS)

    Gallego, Eduardo; Brittain, J.E.; Hakanson, Lars; Heling, Rudie; Hofman, Dmitry; Monte, Luigi

    2000-01-01

    The radiation dose resulting from contamination of freshwater ecosystems due to the release of radioactive substances into the environment may be reduced by applying suitable countermeasures. The options for intervention are wide-ranging and can be broadly grouped into three main categories: chemical, physical and social countermeasures. In some cases, a combination of actions -or even the no action- may be the optimal strategy. Despite their benefits, intervention strategies may have detrimental effects of economic, ecological and social nature. Thus, it is of paramount importance to assess, by objective criteria, the global cost-benefit balance of different options. The MOIRA project (A MOdel based computerised system for management support to Identity optimal remedial strategies for Restoring radionuclide contaminated Aquatic ecosystems, European Commission contract FI4P-CT96-0036) has developed a user-friendly, computerised tool that will allow decision makers to choose optimal intervention strategies for freshwater ecosystems with different contamination scenarios. To achieve that goal, the MOIRA software system -apart from a user-friendly interface- incorporates several innovative aspects: - eographical information system (GIS) and databases to get to get the values of the model parameters at different locations in Europe. - redictive ecosystem models for the behaviour of radionuclides (namely Cs-137 and Sr-90) in catchments, lakes and rivers, complemented with models of the effect of the countermeasures on the environmental contamination levels. These models are based on an extensive use of aggregate parameters' that summarise, in single quantities, the effects of a variety of environmental processes. Methods for critical model testing, sensitivity and uncertainty analyses have been applied to them getting a high reliability. - cosystem index (EI) to handle the influence chemical remedial measures may have on the structure, reproduction and biomass of key

  17. 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.

  18. Impact of salinity and pH on phytoplankton communities in a tropical freshwater system: An investigation with pigment analysis by HPLC

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Acharyya, T.; Babu, P.V.R.; Bandyopadhyay, D.

    towards the fluctuating pH. These findings are environmentally relevant to understand the likely impact of salt water intrusion and pH variation on phytoplankton communities in a tropical freshwater system....

  19. ECONOMIC ANALYSIS OF FRESHWATER AQUACULTURE PRODUCTION: A COMPARATIVE ANALYSIS OF DIFFERENT PRODUCTION SYSTEMS

    Directory of Open Access Journals (Sweden)

    H. Kumar

    2013-01-01

    Full Text Available India produced 8.29 million tonnes of fish in 2010-2011. The industry contributes nearly INR 200 trillion to the national economy, forming 1.4 percent of national gross domestic product (GDP and 5.4 percent of Agricultural GDP. At present, almost 84 percent of the total inland fish production, in the country is contributed by freshwater aquaculture amounting to 3.9 million tonnes in 2008-09. Further, the potential of the vast freshwater resources covering 6.7 million hectare is yet to be fully realized. The freshwater aquaculture which began as small scale activity of stocking ponds with fish seed collected from riverine sources during early fifties in rural Bengal has now transformed into a major economic activity in almost all states. There is a further need to make the sector more vibrant so as to achieve the predicted target of 15 kg per capita fish availability in the country by 2030.

  20. Seasonal changes in optical properties of two contrasting tropical freshwater systems

    Directory of Open Access Journals (Sweden)

    Luciana P.M. Brandão

    2016-05-01

    Full Text Available We investigated how allochthonous and autochthonous sources of dissolved organic matter (DOM affected the optical conditions and chemical characteristics of two contrasting tropical freshwater systems (Dom Helvécio-DH and Pampulha reservoir in a dry and rainy period in 2013. We analyzed PAR (photosynthetically active radiation and UV (ultraviolet attenuation coefficients, nutrients, chlorophyll-a (Chl-a, dissolved organic matter (DOC and spectral characteristics of CDOM (colored dissolved organic matter. Significant differences in CDOM sources and quantity were observed, with a dominantly terrestrial input in DH during the rainy period with approximately 50% higher DOC and Chl-a levels, and a doubling in total nitrogen (TN and total phosphorus (TP compared to the dry winter period. The eutrophic Pampulha had several fold higher levels of DOC, Chl-a, TN and TP, with organic matter of mostly originating from phytoplankton in both seasons. Differences in source and quantity had strong implications on water transparency, DOC concentrations, CDOM quality and its susceptibility to photo- and biodegradation. DH was several fold clearer in both the UV and PAR spectrum. In DH transparency to both UV and PAR radiation was highest during the summer, suggesting elevated photo- and biodegradation during stratification. Pampulha was most transparent in the dry period even during period of algal bloom. In both systems we observed seasonal variations in concentrations of nutrients and Chl-a, and in DH differences were also found in DOC concentrations as well as the specific UV absorbance (SUVA254 and molecular size (M. Our results documents that different sources of DOM and seasonal inputs reflect in the seasonality of apparent and inherent optical properties and nutrients availability with implications for water quality and aquatic community. 

  1. Hydrologic assessment of the shallow groundwater flow system beneath the Shinnecock Nation tribal lands, Suffolk County, New York

    Science.gov (United States)

    Noll, Michael L.; Rivera, Simonette L.; Busciolano, Ronald J.

    2016-12-02

    Defining the distribution and flow of shallow groundwater beneath the Shinnecock Nation tribal lands in Suffolk County, New York, is a crucial first step in identifying sources of potential contamination to the surficial aquifer and coastal ecosystems. The surficial or water table aquifer beneath the tribal lands is the primary source of potable water supply for at least 6 percent of the households on the tribal lands. Oyster fisheries and other marine ecosystems are critical to the livelihood of many residents living on the tribal lands, but are susceptible to contamination from groundwater entering the embayment from the surficial aquifer. Contamination of the surficial aquifer from flooding during intense coastal storms, nutrient loading from fertilizers, and septic effluent have been identified as potential sources of human and ecological health concerns on tribal lands.The U.S. Geological Survey (USGS) facilitated the installation of 17 water table wells on and adjacent to the tribal lands during March 2014. These wells were combined with other existing wells to create a 32-well water table monitoring network that was used to assess local hydrologic conditions. Survey-grade, global-navigation-satellite systems provided centimeter-level accuracy for positioning wellhead surveys. Water levels were measured by the USGS during May (spring) and November (fall) 2014 to evaluate seasonal effects on the water table. Water level measurements were made at high and low tide during May 2014 to identify potential effects on the water table caused by changes in tidal stage (tidal flux) in Shinnecock Bay. Water level contour maps indicate that the surficial aquifer is recharged by precipitation and upgradient groundwater flow that moves from the recharge zone located generally beneath Sunrise Highway, to the discharge zone beneath the tribal lands, and eventually discharges into the embayment, tidal creeks, and estuaries that bound the tribal lands to the east, south, and

  2. Characterization of the shallow groundwater system in an alpine watershed: Handcart Gulch, Colorado, USA

    Science.gov (United States)

    Kahn, Katherine G.; Ge, Shemin; Caine, Jonathan S.; Manning, A.

    2008-01-01

    Water-table elevation measurements and aquifer parameter estimates are rare in alpine settings because few wells exist in these environments. Alpine groundwater systems may be a primary source of recharge to regional groundwater flow systems. Handcart Gulch is an alpine watershed in Colorado, USA comprised of highly fractured Proterozoic metamorphic and igneous rocks with wells completed to various depths. Primary study objectives include determining hydrologic properties of shallow bedrock and surficial materials, developing a watershed water budget, and testing the consistency of measured hydrologic properties and water budget by constructing a simple model incorporating groundwater and surface water for water year 2005. Water enters the study area as precipitation and exits as discharge in the trunk stream or potential recharge for the deeper aquifer. Surficial infiltration rates ranged from 0.1-6.2??0-5 m/s. Discharge was estimated at 1.28??10-3 km3. Numerical modeling analysis of single-well aquifer tests predicted lower specific storage in crystalline bedrock than in ferricrete and colluvial material (6.7??10-5-2.10??0-3 l/m). Hydraulic conductivity in crystalline bedrock was significantly lower than in colluvial and alluvial material (4.3??10-9 -2.0??10-4 m/s). Water budget results suggest that during normal precipitation and temperatures water is available to recharge the deeper groundwater flow system. ?? Springer-Verlag 2007.

  3. Shallow seismicity in volcanic system: what role does the edifice play?

    Science.gov (United States)

    Bean, Chris; Lokmer, Ivan

    2017-04-01

    Seismicity in the upper two kilometres in volcanic systems is complex and very diverse in nature. The origins lie in the multi-physics nature of source processes and in the often extreme heterogeneity in near surface structure, which introduces strong seismic wave propagation path effects that often 'hide' the source itself. Other complicating factors are that we are often in the seismic near-field so waveforms can be intrinsically more complex than in far-field earthquake seismology. The traditional focus for an explanation of the diverse nature of shallow seismic signals is to call on the direct action of fluids in the system. Fits to model data are then used to elucidate properties of the plumbing system. Here we show that solutions based on these conceptual models are not unique and that models based on a diverse range of quasi-brittle failure of low stiffness near surface structures are equally valid from a data fit perspective. These earthquake-like sources also explain aspects of edifice deformation that are as yet poorly quantified.

  4. Differences in the exploitation of bream in three shallow lake systems and their relation to water quality

    NARCIS (Netherlands)

    Lammens, E.H.R.R.; Nes, van E.H.; Mooij, W.M.

    2002-01-01

    1. The development of bream populations, water transparency, chlorophyll-a concentration, extent of submerged vegetation and densities of the zebra mussel, Dreissena polymorpha, were analysed in three shallow eutrophic lake systems subject to different fish management. 2. In Lake Veluwemeer, the

  5. Differences in the exploitation of bream in three shallow lake systems and their relation to water quality

    NARCIS (Netherlands)

    Lammens, E.H.R.R.; Van Nes, E.H.; Mooij, W.M.

    2002-01-01

    SUMMARY1. The development of bream populations, water transparency, chlorophyll-a concentration, extent of submerged vegetation and densities of the zebra mussel, Dreissena polymorpha, were analysed in three shallow eutrophic lake systems subject to different fish management. 2. In Lake Veluwemeer,

  6. Observations and analytical modeling of freshwater and rainwater lenses in coastal dune systems

    NARCIS (Netherlands)

    Stuijfzand, Pieter

    2016-01-01

    Observations are reported on (i) groundwater recharge rates under various types of vegetation as measured with megalysimeters in the dunes, (ii) freshwater lenses along the Dutch North Sea coast in the early 1900s, and (iii) rainwater lenses that develop on top of laterally migrating,

  7. Phylogenetic comparisons of a coastal bacterioplankton community with its counterparts in open ocean and freshwater systems.

    Science.gov (United States)

    Rappé; Vergin; Giovannoni

    2000-09-01

    In order to extend previous comparisons between coastal marine bacterioplankton communities and their open ocean and freshwater counterparts, here we summarize and provide new data on a clone library of 105 SSU rRNA genes recovered from seawater collected over the western continental shelf of the USA in the Pacific Ocean. Comparisons to previously published data revealed that this coastal bacterioplankton clone library was dominated by SSU rRNA gene phylotypes originally described from surface waters of the open ocean, but also revealed unique SSU rRNA gene lineages of beta Proteobacteria related to those found in clone libraries from freshwater habitats. beta Proteobacteria lineages common to coastal and freshwater samples included members of a clade of obligately methylotrophic bacteria, SSU rRNA genes affiliated with Xylophilus ampelinus, and a clade related to the genus Duganella. In addition, SSU rRNA genes were recovered from such previously recognized marine bacterioplankton SSU rRNA gene clone clusters as the SAR86, SAR11, and SAR116 clusters within the class Proteobacteria, the Roseobacter clade of the alpha subclass of the Proteobacteria, the marine group A/SAR406 cluster, and the marine Actinobacteria clade. Overall, these results support and extend previous observations concerning the global distribution of several marine planktonic prokaryote SSU rRNA gene phylotypes, but also show that coastal bacterioplankton communities contain SSU rRNA gene lineages (and presumably bacterioplankton) shown previously to be prevalent in freshwater habitats.

  8. Geophysical Methods for Monitoring Temperature Changes in Shallow Low Enthalpy Geothermal Systems

    Directory of Open Access Journals (Sweden)

    Thomas Hermans

    2014-08-01

    Full Text Available Low enthalpy geothermal systems exploited with ground source heat pumps or groundwater heat pumps present many advantages within the context of sustainable energy use. Designing, monitoring and controlling such systems requires the measurement of spatially distributed temperature fields and the knowledge of the parameters governing groundwater flow (permeability and specific storage and heat transport (thermal conductivity and volumetric thermal capacity. Such data are often scarce or not available. In recent years, the ability of electrical resistivity tomography (ERT, self-potential method (SP and distributed temperature sensing (DTS to monitor spatially and temporally temperature changes in the subsurface has been investigated. We review the recent advances in using these three methods for this type of shallow applications. A special focus is made regarding the petrophysical relationships and on underlying assumptions generally needed for a quantitative interpretation of these geophysical data. We show that those geophysical methods are mature to be used within the context of temperature monitoring and that a combination of them may be the best choice regarding control and validation issues.

  9. Modelling ground movements at Campi Flegrei caldera (Italy): the role of the shallow geothermal system

    Science.gov (United States)

    Troiano, Antonio; Giulia di Giuseppe, Maria; Petrillo, Zaccaria; Troise, Claudia; de Natale, Giuseppe

    2010-05-01

    Campi Flegrei caldera is characterized by large ground movements, well known since Roman times. Superimposed to a general secular subsidence occurring at a rate of 1.5-2.0 cm/year, an episode of sharp uplift is in progress since 1969, with peak rates up to 1 m/year (in 1982-1984), similar to another episode which culminated with the 1538 eruption. Peak uplift episodes are often followed by some amount of subsidence, which prevent a simple interpretation in terms of purely magmatic inflation phenomena. Such up and down episodes of ground deformations are rather common at large calderas, like in Yellowstone (USA), Long Valley (USA), etc. Here we propose an interpretation based on a mixed mechanical-fluid-dynamical model, in which part of the uplift is generated by increase of water pressure in the shallow geothermal system, as a response to rapid inflow of magmatic fluids exsolved from a deeper magma chamber. We use the program THOUGH2 to model the changes of temperature and pressure in the geothermal system due to the magmatic fluids inflow. Changes in pressure in the caldera volume are then used to compute ground deformations. This way, a theoretical time evolution of ground deformation has been obtained, which compares well with the observed one, if appropriate values of permeability are used. We discuss the implication of such a model for eruption forecast purposes, and the extent at which the required values of permeability can be really representative of the real medium.

  10. Seasonal thermal energy storage in shallow geothermal systems: thermal equilibrium stage

    Directory of Open Access Journals (Sweden)

    Nowamooz Hossein

    2016-01-01

    Full Text Available This paper is dedicated to the study of seasonal heat storage in shallow geothermal installations in unsaturated soils for which hydrothermal properties such as degree of saturation and thermal conductivity vary with time throughout the profile. In the model, a semi-analytical model which estimates time-spatial thermal conductivity is coupled with a 2D cylindrical heat transfer modeling using finite difference method. The variation of temperature was obtained after 3 heating and cooling cycles for the different types of loads with maximum thermal load of qmax = 15 W.m−1 with variable angular frequency (8 months of heating and 4 months of cooling.and constant angular frequency (6 months of heating and 6 months of cooling to estimate the necessary number of cycles to reach the thermal equilibrium stage. The results show that we approach a thermal equilibrium stage where the same variation of temperature can be observed in soils after several heating and cooling cycles. Based on these simulations, the necessary number of cycles can be related to the total applied energy on the system and the minimum number of cycles is for a system with the total applied energy of 1.9qmax.

  11. Balanced bilinguals favor lexical processing in their opaque language and conversion system in their shallow language

    OpenAIRE

    Buetler, Karin A.; Rodríguez, Diego de León; Laganaro, Marina; Müri, René; Nyffeler, Thomas; Spierer, Lucas; Annoni, Jean-Marie

    2016-01-01

    Referred to as orthographic depth, the degree of consistency of grapheme/phoneme correspondences varies across languages from high in shallow orthographies to low in deep orthographies. The present study investigates the impact of orthographic depth on reading route by analyzing evoked potentials to words in a deep (French) and shallow (German) language presented to highly proficient bilinguals. ERP analyses to German and French words revealed significant topographic modulations 240–280 ms po...

  12. Variation in stable isotopes of freshwater mussel shells in a Kentucky river system

    Science.gov (United States)

    Erhardt, A. M.; Haag, W.; Price, S.; Weisrock, D.

    2017-12-01

    Isotopic signatures in freshwater mussel shells can reflect environmental differences among streams and human impacts on river systems. In the southeastern United States, mussels exhibit extraordinary biodiversity, serve an important role as filter feeders, and are sensitive to environmental change. Additionally, their long life-span (up to 50 years) and seasonal shell deposition can permit high-resolution environmental reconstructions. We examined variation in shell stable isotope values among mussel species and locations throughout the Licking River system in Kentucky. We sampled 8 species at 11 locations. These species represented a range of life-history traits, and locations were distributed among tributaries and the main stem of the Licking River. Samples of the outer organic periostracum layer were analysed for organic δ13C and δ15N, while organic δ15N and inorganic δ13C and δ18O were measured in the inner carbonate portion of the shell. At the same location, preliminary results show variations 2‰ in δ13C and 1‰ in δ15N between different species. We suspect these relationships are due to variations in diet and/or body size. Some, though not all, specimens show variation along the growth axis. For the same species at different locations, preliminary results showed a range of 4‰ in δ13C and 10‰ in δ15N values. Isotope ratios of specimens from the main stem were distinct from those of specimens from the river's largest tributary. Overall, δ13C shows distinct values for each tributary, while δ15N shows a general decline downstream. These variations are likely the result of environmental factors such as the degree of karstification and the ratio of forest to pasture within the catchment. We hope to use this study to identify if any isotopically distinct sources, such as fertilizers or animal manure, contribute to the high nutrient load in these systems. These results represent an exploratory effort to describe watershed-scale and mussel

  13. Potential Application of Shallow Bed Wetland Roof systems for green urban cities

    Science.gov (United States)

    Bui, X. T.

    2016-12-01

    This study aims to investigate the growth, nutrient uptake, domestic wastewater treatment, green (leaf) area and heat reduction of four shallow subsurface flow wetland roof (WR) systems with four different new local plants. Selected species included Cyperus Javanicus Hot (WR1), Eleusine Indica (L.) Gaertn (WR2), Struchium Sparganophorum (L.) Kuntze (WR3) and Kyllinga Brevifolia Rottb (WR4). These systems were operated during 61 days at hydraulic loading rates of 353 - 403 m3/ha.day. The biomass growth of 4.9-73.7g fresh weight/day, and 0.8-11.4 g dry weight/day were observed. The nutrient accumulation according to dry biomass achieved 0.25-2.14% of total nitrogen (TN) and 0.13-1.07% of total phosphorus (TP). The average COD, TN and TP removal was 61-79%; 54-81% and 62-83%, which corresponding to 27-33 kg COD/ha.day, 10-14 kg TN/ha.day and 0.4-0.5 kg TP/ha.day, respectively. The WR4 system achieved the highest COD and TN removal among the WRs. The TP removal efficiency showed an insignificant difference for the systems. Consequently, the treated water quality complied with the Vietnam standard limits (QCVN 14:2008, level B). The green area of the four plants varied between 63-92 m2 green leaf/m2 WR. The WR4 was the highest green area. Moreover, the results also showed the temperature under the flat roof was 1-3°C lower than that of the ambient air. In summary, wetland roof is a promising technology, which not only owns the effective domestic wastewater treatment capacity, but also contributes to green urban with several above benefits.

  14. Inertia–gravity wave radiation from the elliptical vortex in the f -plane shallow water system

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, Norihiko, E-mail: nori@phys-h.keio.ac.jp [Research and Education Center for Natural Sciences, Department of Physics, Keio University, 4-1-1 Hiyoshi, Kouhoku-ku, Yokohama, Kanagawa 223-8521 (Japan)

    2017-04-15

    Inertia–gravity wave (IGW) radiation from the elliptical vortex is investigated in the f -plane shallow water system. The far field of IGW is analytically derived for the case of an almost circular Kirchhoff vortex with a small aspect ratio. Cyclone–anticyclone asymmetry appears at finite values of the Rossby number (Ro) caused by the source originating in the Coriolis acceleration. While the intensity of IGWs from the cyclone monotonically decreases as f increases, that from the anticyclone increases as f increases for relatively smaller f and has a local maximum at intermediate f . A numerical experiment is conducted on a model using a spectral method in an unbounded domain. The numerical results agree quite well with the analytical ones for elliptical vortices with small aspect ratios, implying that the derived analytical forms are useful for the verification of the numerical model. For elliptical vortices with larger aspect ratios, however, significant deviation from the analytical estimates appears. The intensity of IGWs radiated in the numerical simulation is larger than that estimated analytically. The reason is that the source of IGWs is amplified during the time evolution because the shape of the vortex changes from ideal ellipse to elongated with filaments. Nevertheless, cyclone–anticyclone asymmetry similar to the analytical estimate appears in all the range of aspect ratios, suggesting that this asymmetry is a robust feature. (paper)

  15. Natural and anthropogenic factors affecting freshwater lenses in coastal dunes of the Adriatic coast

    Science.gov (United States)

    Cozzolino, Davide; Greggio, Nicolas; Antonellini, Marco; Giambastiani, Beatrice Maria Sole

    2017-08-01

    This study characterizes the near-shore portion of the shallow coastal aquifer included in the Ravenna area (Northern Italy) with special attention to the roles of coastal dunes as freshwater reservoirs and their buffer on groundwater salinity. The paper focuses on the presence and evolution of freshwater lenses below coastal dunes and highlights the existing differences between preserved natural dunes and dunes strongly affected by human intervention. The influence that multiple natural and anthropogenic factors, such as land cover, local drainage network, and beach erosion have on the presence, size and evolution of the freshwater lenses in the aquifer is quantified and discussed. The methodology includes multiple seasonal monitoring and sampling campaigns of physical (water level, salinity, and temperature) and chemical (major cations and anions) groundwater parameters. Results indicate that freshwater lenses, where existing, are limited in thickness (about 1-2 m). Proximity to drainage ditches as well as limited dune elevation and size do not allow the formation and permanent storage of large freshwater lenses in the aquifer below the dunes. The pine forest land cover, that replaced the typical bush or sand cover, intensifies evapotranspiration reducing net infiltration and freshwater storage. The cation species distribution in the water shows that a freshening process is ongoing in preserved natural sites with stable or advancing beaches, whereas a salinization process is ongoing in anthropogenic-impacted areas with strongly-fragmented dune systems. Currently, the thin freshwater lenses in the shallow Ravenna coastal aquifer are limited in space and have no relevance for irrigation or any other human activity. The dune-beach system, however, is the recharge zone of the coastal aquifer and its protection is important to reduce water and soil salinization, which in turn control the health of the whole coastal ecosystem.

  16. Gas hydrate geohazards in shallow sediments and their impact on the design of subsea systems

    Energy Technology Data Exchange (ETDEWEB)

    Peters, D.; Hatton, G. [Shell Global Solutions Inc., Houston, TX (United States); Mehta, A. [Shell Malaysia Exploration and Production, Sarawak (Malaysia); Hadley, C. [Shell Exploration and Production Inc., Houston, TX (United States)

    2008-07-01

    This paper described the challenges that exist in producing gas hydrates in deepwater and Arctic environments as a potential source of methane gas. In order to safely produce hydrocarbon reservoirs far beneath near-mudline hydrates, it is important to understand and manage the geohazard risks associated with wells that pass through hydrate-bearing sediments. Since these wells may produce for decades, the temperature of near-mudline sediments may increase above the hydrate dissociation temperature for hundreds of meters from the well. This can result in the release of large quantities of gas causing a volume change that can impact the subsea system in many ways. As the fluids of an underlying reservoir flow to the mudline, heat carried by the fluids warms nearwell sediments and dissociates hydrates, which releases gas that can displace and fracture near well soil. This gas release may be calculated with numerical simulations that model heat and mass transfer in hydrate-bearing sediments. The model simulations require information on the nature and distribution of hydrates within the sediments, the melting behaviour of the hydrates, the thermal and mechanical properties of these shallow sediments, and the amount of hydrates contained in the sediments. However, this information is costly to acquire and characterize with certainty for an offshore development. Therefore, it is important to understand what information, processes, and calculations are needed in order to ensure safe, robust systems to produce the hydrocarbon reservoirs far below the hydrates. It was concluded that the relation between the quantity of gas released and dissociated gas quantities must be well understood. The hydrate concentration is a critical reservoir parameter for reservoirs with severe geohazard risk. 6 refs., 6 figs.

  17. Fine-scale heat flow, shallow heat sources, and decoupled circulation systems at two sea-floor hydrothermal sites, Middle Valley, northern Juan de Fuca Ridge

    Science.gov (United States)

    Stein, J. S.; Fisher, A. T.; Langseth, M.; Jin, W.; Iturrino, G.; Davis, E.

    1998-12-01

    Fine-scale heat-flow patterns at two areas of active venting in Middle Valley, a sedimented rift on the northern Juan de Fuca Ridge, provide thermal evidence of shallow hydrothermal reservoirs beneath the vent fields. The extreme variability of heat flow is explained by conductive heating immediately adjacent to vents and shallow circulation within sediments above the reservoir. This secondary circulation is hydrologically separated from the deeper system feeding the vents by a shallow conductive lid within the sediments. A similar separation of shallow and deep circulation may also occur at sediment-free ridge-crest hydrothermal environments.

  18. Hydrogeology and water quality of the shallow ground-water system in eastern York County, Virginia. Water resources investigation

    International Nuclear Information System (INIS)

    1993-01-01

    The report describes the hydrogeology and water quality of the shallow ground-water system in the eastern part of York County, Va. The report includes a discussion of (1) the aquifers and confining units, (2) the flow of ground water, and (3) the quality of ground water. The report is an evaluation of the shallow ground-water system and focuses on the first 200 ft of sediments below land surface. Historical water-level and water-quality data were not available for the study area; therefore, a network of observation wells was constructed for the study. Water levels were measured to provide an understanding of the flow of ground water through the multiaquifer system. Water samples were collected and analyzed for major inorganic constituents, nutrients, and metals. The report presents maps that show the regional distribution of chloride and iron concentrations. Summary statistics and graphical summaries of selected chemical constituents provide a general assessment of the ground-water quality

  19. ANALYTICAL MODELS OF EXOPLANETARY ATMOSPHERES. I. ATMOSPHERIC DYNAMICS VIA THE SHALLOW WATER SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Kevin [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Workman, Jared, E-mail: kevin.heng@csh.unibe.ch, E-mail: jworkman@coloradomesa.edu [Colorado Mesa University, 1260 Kennedy Avenue, Grand Junction, CO 81501 (United States)

    2014-08-01

    Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation.

  20. Capabilities of seismic and georadar 2D/3D imaging of shallow subsurface of transport route using the Seismobile system

    Science.gov (United States)

    Pilecki, Zenon; Isakow, Zbigniew; Czarny, Rafał; Pilecka, Elżbieta; Harba, Paulina; Barnaś, Maciej

    2017-08-01

    In this work, the capabilities of the Seismobile system for shallow subsurface imaging of transport routes, such as roads, railways, and airport runways, in different geological conditions were presented. The Seismobile system combines the advantages of seismic profiling using landstreamer and georadar (GPR) profiling. It consists of up to four seismic measuring lines and carriage with a suspended GPR antenna. Shallow subsurface recognition may be achieved to a maximum width of 10.5 m for a distance of 3.5 m between the measurement lines. GPR measurement is performed in the axis of the construction. Seismobile allows the measurement time, labour and costs to be reduced due to easy technique of its installation, remote data transmission from geophones to accompanying measuring modules, automated location of the system based on GPS and a highly automated method of seismic wave excitation. In this paper, the results of field tests carried out in different geological conditions were presented. The methodologies of acquisition, processing and interpretation of seismic and GPR measurements were broadly described. Seismograms and its spectrum registered by Seismobile system were compared to the ones registered by Geode seismograph of Geometrix. Seismic data processing and interpretation software allows for the obtaining of 2D/3D models of P- and S-wave velocities. Combined seismic and GPR results achieved sufficient imaging of shallow subsurface to a depth of over a dozen metres. The obtained geophysical information correlated with geological information from the boreholes with good quality. The results of performed tests proved the efficiency of the Seismobile system in seismic and GPR imaging of a shallow subsurface of transport routes under compound conditions.

  1. Evaluation of Dicentrarchus labrax Meats and the Vegetable Quality of Beta vulgaris var. cicla Farmed in Freshwater and Saltwater Aquaponic Systems

    Directory of Open Access Journals (Sweden)

    Valentina Nozzi

    2016-09-01

    Full Text Available The purpose of this study is to exploit the euryhaline nature of commercially attractive species for their cultivation in freshwater aquaponic systems. This approach may increase the profitability of aquaponic production in coastal countries where the consumption of marine fish is traditional and of commercial relevance. For this purpose, juvenile European sea bass (Dicentrarchus labrax were reared in an aquaponic freshwater (AFW system and an aquaponic saltwater (ASW system (salinity 20 ppt, in combination with chard (Beta vulgaris var. cicla seedlings, a salt tolerant plant. At the end of the trial, nitrate and phosphate concentration in water significantly increased in the ASW system, suggesting that the ability of B. vulgaris to absorb these substances was limited by salinity. Total reflection X-ray fluorescence spectrometry revealed that the concentration of some oligoelements such as Fe remained lower with respect to the concentration in the freshwater hydroponic solution, in both AFW and ASW. FTIR-Fourier transform infrared spectroscopy on plants showed that growth at high salinity affected their lipid content. In the case of fish, freshwater had no effects on mono- and poly-unsaturated fatty acid profiles, although saturated fatty acids were significantly decreased in D. labrax reared in AFW. Our results demonstrates that it is possible to increase aquaponic profitability by farming D. labrax juveniles in an aquaponic freshwater system together with Beta vulgaris, obtaining good quality products.

  2. SHALLOW HABITATS IN TWO RHODE ISLAND SYSTEMS: II. PATTERNS OF SIZE, STRUCTURE AND FUNCTIONAL GROUPS

    Science.gov (United States)

    We are examining habitats in small estuarine coves that may be important for the development of ecological indicators of integrity. We sampled nekton in Coggeshall Cove (shallow estuarine cove) in summer 1999 and 2000 and Ninigret Pond (coastal lagoon) in summer 2000. Coggeshall ...

  3. Balanced bilinguals favor lexical processing in their opaque language and conversion system in their shallow language.

    Science.gov (United States)

    Buetler, Karin A; de León Rodríguez, Diego; Laganaro, Marina; Müri, René; Nyffeler, Thomas; Spierer, Lucas; Annoni, Jean-Marie

    2015-11-01

    Referred to as orthographic depth, the degree of consistency of grapheme/phoneme correspondences varies across languages from high in shallow orthographies to low in deep orthographies. The present study investigates the impact of orthographic depth on reading route by analyzing evoked potentials to words in a deep (French) and shallow (German) language presented to highly proficient bilinguals. ERP analyses to German and French words revealed significant topographic modulations 240-280 ms post-stimulus onset, indicative of distinct brain networks engaged in reading over this time window. Source estimations revealed that these effects stemmed from modulations of left insular, inferior frontal and dorsolateral regions (German>French) previously associated to phonological processing. Our results show that reading in a shallow language was associated to a stronger engagement of phonological pathways than reading in a deep language. Thus, the lexical pathways favored in word reading are reinforced by phonological networks more strongly in the shallow than deep orthography. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Shallow system rejuvenation and magma discharge trends at Piton de la Fournaise volcano (La Réunion Island)

    Science.gov (United States)

    Coppola, D.; Di Muro, A.; Peltier, A.; Villeneuve, N.; Ferrazzini, V.; Favalli, M.; Bachèlery, P.; Gurioli, L.; Harris, A. J. L.; Moune, S.; Vlastélic, I.; Galle, B.; Arellano, S.; Aiuppa, A.

    2017-04-01

    Basaltic magma chambers are often characterized by emptying and refilling cycles that influence their evolution in space and time, and the associated eruptive activity. During April 2007, the largest historical eruption of Piton de la Fournaise (Île de La Réunion, France) drained the shallow plumbing system (> 240 ×106 m3) and resulted in collapse of the 1-km-wide summit crater. Following these major events, Piton de la Fournaise entered a seven-year long period of near-continuous deflation interrupted, in June 2014, by a new phase of significant inflation. By integrating multiple datasets (lava discharge rates, deformation, seismicity, gas flux, gas composition, and lava chemistry), we here show that the progressive migration of magma from a deeper (below sea level) storage zone gradually rejuvenated and pressurized the above-sea-level portion of the magmatic system consisting of a vertically-zoned network of relatively small-volume magma pockets. Continuous inflation provoked four small (CO2 enrichment of summit fumaroles, and involving emission of less differentiated lavas, to end with, (iii) three short-lived (∼2 day-long) pulses in lava and gas flux, coupled with arrival of cumulative olivine at the surface and deflation. The activity observed at Piton de la Fournaise in 2014 and 2015 points to a new model of shallow system rejuvenation and discharge, whereby continuous magma supply causes eruptions from increasingly deeper and larger magma storage zones. Downward depressurization continues until unloading of the deepest, least differentiated magma triggers pulses in lava and gas flux, accompanied by rapid contraction of the volcano edifice, that empties the main shallow reservoir and terminates the cycle. Such an unloading process may characterize the evolution of shallow magmatic systems at other persistently active effusive centers.

  5. Cytotoxicity of TiO{sub 2} nanoparticles and their detoxification in a freshwater system

    Energy Technology Data Exchange (ETDEWEB)

    Dalai, Swayamprava; Pakrashi, Sunandan; Joyce Nirmala, M.; Chaudhri, Apoorvi; Chandrasekaran, N. [Centre for Nanobiotechnology, VIT University, Vellore (India); Mandal, A.B. [Chemical Laboratory, Central Leather Research Institute, Chennai (India); Mukherjee, Amitava, E-mail: amitav@vit.ac.in [Centre for Nanobiotechnology, VIT University, Vellore (India)

    2013-08-15

    Highlights: •TiO{sub 2} NPs cytotoxicity at low exposure levels (≤1 μg/mL) to freshwater algae. •ROS generation, NP adsorption and internalization contributors to toxicity. •Observational evidence of genotoxicity by nanoparticles in an algal cell. •Reduced bioavailability thus detoxification of NPs by microalgae. •Possible role of EPS in detoxification. -- Abstract: In the current study, two aspects concerning (i) the cytotoxicity potential of TiO{sub 2} nanoparticles (NPs) toward freshwater algal isolate Scenedesmus obliquus and (ii) the potential detoxification of NPs by the microalgae were assessed under light (UV-illumination) and dark conditions at low exposure levels (≤1 μg/mL), using sterile freshwater as the test medium. The statistically significant reduction in cell viability, increase in reactive oxygen species production and membrane permeability (light vs. dark) suggested photo-induced toxicity of TiO{sub 2} NPs. The electron micrographs demonstrated adsorption of the NPs onto the cell surface and substantiated their internalization/uptake. The fluorescence micrographs and the confocal laser scanning (CLSM) images suggested the absence of a definite/intact nucleus in the light treated cells pointing toward the probable genotoxic effects of NPs. In a separate three cycle experiment, a continuous decrease in the cytotoxicity was observed, whereas, at the end of each cycle only fresh algae were added to the supernatant containing NPs from the previous cycle. The decreasing concentrations of the NPs in the subsequent cycles owing to agglomeration–sedimentation processes exacerbated by the algal interactions played a crucial role in the detoxification. In addition, the exo-polymeric substances produced by the cells could have rendered the available NPs less reactive, thereby, enhancing the detoxification effects.

  6. Cytotoxicity of TiO2 nanoparticles and their detoxification in a freshwater system

    International Nuclear Information System (INIS)

    Dalai, Swayamprava; Pakrashi, Sunandan; Joyce Nirmala, M.; Chaudhri, Apoorvi; Chandrasekaran, N.; Mandal, A.B.; Mukherjee, Amitava

    2013-01-01

    Highlights: •TiO 2 NPs cytotoxicity at low exposure levels (≤1 μg/mL) to freshwater algae. •ROS generation, NP adsorption and internalization contributors to toxicity. •Observational evidence of genotoxicity by nanoparticles in an algal cell. •Reduced bioavailability thus detoxification of NPs by microalgae. •Possible role of EPS in detoxification. -- Abstract: In the current study, two aspects concerning (i) the cytotoxicity potential of TiO 2 nanoparticles (NPs) toward freshwater algal isolate Scenedesmus obliquus and (ii) the potential detoxification of NPs by the microalgae were assessed under light (UV-illumination) and dark conditions at low exposure levels (≤1 μg/mL), using sterile freshwater as the test medium. The statistically significant reduction in cell viability, increase in reactive oxygen species production and membrane permeability (light vs. dark) suggested photo-induced toxicity of TiO 2 NPs. The electron micrographs demonstrated adsorption of the NPs onto the cell surface and substantiated their internalization/uptake. The fluorescence micrographs and the confocal laser scanning (CLSM) images suggested the absence of a definite/intact nucleus in the light treated cells pointing toward the probable genotoxic effects of NPs. In a separate three cycle experiment, a continuous decrease in the cytotoxicity was observed, whereas, at the end of each cycle only fresh algae were added to the supernatant containing NPs from the previous cycle. The decreasing concentrations of the NPs in the subsequent cycles owing to agglomeration–sedimentation processes exacerbated by the algal interactions played a crucial role in the detoxification. In addition, the exo-polymeric substances produced by the cells could have rendered the available NPs less reactive, thereby, enhancing the detoxification effects

  7. Cobalt Chloride Treatment Used to Ablate the Lateral Line System Also Impairs the Olfactory System in Three Freshwater Fishes.

    Directory of Open Access Journals (Sweden)

    Julie M Butler

    Full Text Available Fishes use multimodal signals during both inter- and intra-sexual displays to convey information about their sex, reproductive state, and social status. These complex behavioral displays can include visual, auditory, olfactory, tactile, and hydrodynamic signals, and the relative role of each sensory channel in these complex multi-sensory interactions is a common focus of neuroethology. The mechanosensory lateral line system of fishes detects near-body water movements and is implicated in a variety of behaviors including schooling, rheotaxis, social communication, and prey detection. Cobalt chloride is commonly used to chemically ablate lateral line neuromasts, thereby eliminating water-movement cues to test for mechanosensory-mediated behavioral functions. However, cobalt acts as a nonspecific calcium channel antagonist and could potentially disrupt function of all superficially located sensory receptor cells, including those for chemosensing. Here, we examined whether CoCl2 treatment used to ablate the lateral line system also impairs olfaction in three freshwater fishes, the African cichlid fish Astatotilapia burtoni, goldfish Carassius auratus, and the Mexican blind cavefish Astyanax mexicanus. To examine the impact of CoCl2 on the activity of peripheral receptors, we quantified DASPEI fluorescence intensity of the olfactory epithelium from fish exposed to control and CoCl2 solutions. In addition, we examined brain activation in olfactory processing regions of A. burtoni immersed in either control or cobalt solutions. All three species exposed to CoCl2 had decreased DASPEI staining of the olfactory epithelium, and in A. burtoni, cobalt treatment caused reduced neural activation in olfactory processing regions of the brain. To our knowledge this is the first empirical evidence demonstrating that the same CoCl2 treatment used to ablate the lateral line system also impairs olfactory function. These data have important implications for the use of

  8. 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.'

  9. Chemolithoautotrophy in a shallow-sea hydrothermal system, Milos Island, Greece

    Science.gov (United States)

    Lu, G. S.; LaRowe, D.; Gilhooly, W., III; Druschel, G. K.; Fike, D. A.; Amend, J.

    2017-12-01

    In recent decades, numerous (hyper)thermophilic microorganisms have been isolated from hydrothermal venting systems. Although they have been shown to have the capabilities to catalyze a wide variety of reactions to gain energy, few pure cultures have been isolated from these environments. In order to more fully understand the catabolic potential of organisms living in and near hydrothermal vents, we have calculated the Gibbs energies (ΔGr) of 730 redox reactions that could be supplying energy to organisms in the shallow-sea hydrothermal sediments of Paleochori Bay, Milos Island, Greece. This analysis required in-depth geochemical data on the pore fluids and minerals in these sediments near the vent site at several depths. The geochemical profiles of Saganaki vent show steep gradients in temperature, pH, and redox-sensitive compounds resulting from the mixing of hot ( 75oC), acidic ( pH 4), chemically reduced venting fluid with colder, slightly basic and oxidized seawater. We determined values of ΔGr for 47 sediment porewater samples along a 20cm x 2m transect for metabolic reactions involving 23 inorganic H-, O-, C-, N-, S-, Fe-, Mn-, and As- bearing compounds. 379 of the reactions considered were exergonic at one or more sampling locations. The most exergonic reactions were anaerobic CO oxidation with NO2- (136 - 162 kJ/mol e-), followed by the O2/CO, NO3-/CO, and NO2-/ H2S redox pairs. ΔGr values exhibit significant variation among sites as temperature, pH and chemical concentration vary, especially concentrations of Fe2+, Mn2+, and H2S. A great diversity of energy sources are available for microbial populations to exploit: in hotter sediments, sulfide oxidation coupled to nitrite reduction yields large amounts of energy per kg of sediment, whereas aerobic S0 oxidation is more energy-yielding in cooler areas. Our results show that at Saganaki there is a substantial amount of energy available from to microorganisms from sulfur-redox reactions. 16S rRNA pyrotag

  10. Arctic-HYCOS: a Large Sample observing system for estimating freshwater fluxes in the drainage basin of the Arctic Ocean

    Science.gov (United States)

    Pietroniro, Al; Korhonen, Johanna; Looser, Ulrich; Hardardóttir, Jórunn; Johnsrud, Morten; Vuglinsky, Valery; Gustafsson, David; Lins, Harry F.; Conaway, Jeffrey S.; Lammers, Richard; Stewart, Bruce; Abrate, Tommaso; Pilon, Paul; Sighomnou, Daniel; Arheimer, Berit

    2015-04-01

    The Arctic region is an important regulating component of the global climate system, and is also experiencing a considerable change during recent decades. More than 10% of world's river-runoff flows to the Arctic Ocean and there is evidence of changes in its fresh-water balance. However, about 30% of the Arctic basin is still ungauged, with differing monitoring practices and data availability from the countries in the region. A consistent system for monitoring and sharing of hydrological information throughout the Arctic region is thus of highest interest for further studies and monitoring of the freshwater flux to the Arctic Ocean. The purpose of the Arctic-HYCOS project is to allow for collection and sharing of hydrological data. Preliminary 616 stations were identified with long-term daily discharge data available, and around 250 of these already provide online available data in near real time. This large sample will be used in the following scientific analysis: 1) to evaluate freshwater flux to the Arctic Ocean and Seas, 2) to monitor changes and enhance understanding of the hydrological regime and 3) to estimate flows in ungauged regions and develop models for enhanced hydrological prediction in the Arctic region. The project is intended as a component of the WMO (World Meteorological Organization) WHYCOS (World Hydrological Cycle Observing System) initiative, covering the area of the expansive transnational Arctic basin with participation from Canada, Denmark, Finland, Iceland, Norway, Russian Federation, Sweden and United States of America. The overall objective is to regularly collect, manage and share high quality data from a defined basic network of hydrological stations in the Arctic basin. The project focus on collecting data on discharge and possibly sediment transport and temperature. Data should be provisional in near-real time if available, whereas time-series of historical data should be provided once quality assurance has been completed. The

  11. 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.

  12. 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

  13. Quantification of exploitable shallow geothermal energy by using Borehole Heat Exchanger coupled Ground Source Heat Pump systems

    International Nuclear Information System (INIS)

    Hein, Philipp; Zhu, Ke; Bucher, Anke; Kolditz, Olaf; Pang, Zhonghe; Shao, Haibing

    2016-01-01

    Highlights: • The amount of technically exploitable shallow geothermal energy was quantified. • Therefore, a comprehensive numerical borehole heat exchanger model was employed. • The concept of equivalent temperature drop is introduced. • For one BHE, an equivalent temperature drop of 1.8–2.8 °C over 30 years is realistic • The average extractable energy amount evaluates to be 3.5–5.4 kW h m"−"2 a"−"1. - Abstract: In previous studies, the amount of exploitable shallow geothermal energy was estimated by assuming a uniform temperature drop of 2–6 °C in the aquifer. In this work, a more comprehensive numerical model has been employed to evaluate the available amount of shallow geothermal energy by using Borehole Heat Exchanger coupled Ground Source Heat Pump systems. Numerical experiments have been performed by simulating the long-term evolution of the subsurface temperature field, which is subject to the operation of borehole heat exchangers and varying parameters like subsurface thermal conductivity and groundwater flow velocity. The concept of equivalent temperature drop is proposed as an auxiliary quantity for the subsurface. With the help of this parameter, a procedure has been established to quantify the amount of shallow geothermal potential. Following this approach, a realistic equivalent temperature reduction is found to be from −1.8 to −4.4 °C in the subsurface over a period of 30 years. This can be translated to an annual extractable geothermal energy value in a unit surface area, and it ranges from 3.5 to 8.6 kW h m"−"2 a"−"1. The exact value is site specific and heavily depends on the soil thermal conductivity, groundwater velocity, and borehole arrangement.

  14. Quantification of Hydroxylated Polybrominated Diphenyl Ethers (OH-BDEs), Triclosan, and Related Compounds in Freshwater and Coastal Systems.

    Science.gov (United States)

    Kerrigan, Jill F; Engstrom, Daniel R; Yee, Donald; Sueper, Charles; Erickson, Paul R; Grandbois, Matthew; McNeill, Kristopher; Arnold, William A

    2015-01-01

    Hydroxylated polybrominated diphenyl ethers (OH-BDEs) are a new class of contaminants of emerging concern, but the relative roles of natural and anthropogenic sources remain uncertain. Polybrominated diphenyl ethers (PBDEs) are used as brominated flame retardants, and they are a potential source of OH-BDEs via oxidative transformations. OH-BDEs are also natural products in marine systems. In this study, OH-BDEs were measured in water and sediment of freshwater and coastal systems along with the anthropogenic wastewater-marker compound triclosan and its photoproduct dioxin, 2,8-dichlorodibenzo-p-dioxin. The 6-OH-BDE 47 congener and its brominated dioxin (1,3,7-tribromodibenzo-p-dioxin) photoproduct were the only OH-BDE and brominated dioxin detected in surface sediments from San Francisco Bay, the anthropogenically impacted coastal site, where levels increased along a north-south gradient. Triclosan, 6-OH-BDE 47, 6-OH-BDE 90, 6-OH-BDE 99, and (only once) 6'-OH-BDE 100 were detected in two sediment cores from San Francisco Bay. The occurrence of 6-OH-BDE 47 and 1,3,7-tribromodibenzo-p-dioxin sediments in Point Reyes National Seashore, a marine system with limited anthropogenic impact, was generally lower than in San Francisco Bay surface sediments. OH-BDEs were not detected in freshwater lakes. The spatial and temporal trends of triclosan, 2,8-dichlorodibenzo-p-dioxin, OH-BDEs, and brominated dioxins observed in this study suggest that the dominant source of OH-BDEs in these systems is likely natural production, but their occurrence may be enhanced in San Francisco Bay by anthropogenic activities.

  15. Quantification of Hydroxylated Polybrominated Diphenyl Ethers (OH-BDEs, Triclosan, and Related Compounds in Freshwater and Coastal Systems.

    Directory of Open Access Journals (Sweden)

    Jill F Kerrigan

    Full Text Available Hydroxylated polybrominated diphenyl ethers (OH-BDEs are a new class of contaminants of emerging concern, but the relative roles of natural and anthropogenic sources remain uncertain. Polybrominated diphenyl ethers (PBDEs are used as brominated flame retardants, and they are a potential source of OH-BDEs via oxidative transformations. OH-BDEs are also natural products in marine systems. In this study, OH-BDEs were measured in water and sediment of freshwater and coastal systems along with the anthropogenic wastewater-marker compound triclosan and its photoproduct dioxin, 2,8-dichlorodibenzo-p-dioxin. The 6-OH-BDE 47 congener and its brominated dioxin (1,3,7-tribromodibenzo-p-dioxin photoproduct were the only OH-BDE and brominated dioxin detected in surface sediments from San Francisco Bay, the anthropogenically impacted coastal site, where levels increased along a north-south gradient. Triclosan, 6-OH-BDE 47, 6-OH-BDE 90, 6-OH-BDE 99, and (only once 6'-OH-BDE 100 were detected in two sediment cores from San Francisco Bay. The occurrence of 6-OH-BDE 47 and 1,3,7-tribromodibenzo-p-dioxin sediments in Point Reyes National Seashore, a marine system with limited anthropogenic impact, was generally lower than in San Francisco Bay surface sediments. OH-BDEs were not detected in freshwater lakes. The spatial and temporal trends of triclosan, 2,8-dichlorodibenzo-p-dioxin, OH-BDEs, and brominated dioxins observed in this study suggest that the dominant source of OH-BDEs in these systems is likely natural production, but their occurrence may be enhanced in San Francisco Bay by anthropogenic activities.

  16. Comparative analysis of technical efficiency for different production culture systems and species of freshwater aquaculture in Peninsular Malaysia

    Directory of Open Access Journals (Sweden)

    Abdullahi Iliyasu

    2016-05-01

    Full Text Available This study estimated the bias-corrected technical efficiency (BCTE of different culture systems and species of freshwater aquaculture in Malaysia using bootstrapping data envelopment analysis (DEA. Data were collected from 307 respondents from three states in Peninsular Malaysia using a well-structured questionnaire as well as oral interviews. The findings indicate that all technical efficiency scores for all culture systems and species are below the optimal level (i.e. one. In addition, the results show that farmers’ experience, contact with extension workers and household size have a positive and statistically significant impact on technical efficiency. This implies that farmers who have long tenure in fish farming and also the opportunity to meet with extension workers are operating close to the production frontier (technically efficient. On the other hand, the age of the farmers has a negative and statistically significant impact on technical efficiency. Although educational level and farm status have a positive impact on technical efficiency, they are statistically insignificant. Furthermore, all the inputs used in the production process of different culture systems and species contained slacks and need to be reduced accordingly. Feed, the major input in fish production and constituting over half of the production costs, is equally over-utilized. Thus, the government, in collaboration with research institutes and universities, should design a feeding formula for fish depending on species, culture systems and stages of growth. This could help to reduce production costs, increasing the farmers' income, as well as providing much needed animal protein to consumers at an affordable rate. Keywords: Bootstrapping data envelopment analysis (DEA, Technical efficiency, Technical inefficiency, Freshwater aquaculture, Malaysia

  17. A review and model assessment of 32P and 33P uptake to biota in freshwater systems

    International Nuclear Information System (INIS)

    Smith, J.T.; Bowes, M.J.; Cailes, C.R.

    2011-01-01

    Bioaccumulation of key short-lived radionuclides such as 131 I and 32,33 P may be over-estimated since concentration ratios (CRs) are often based on values for the corresponding stable isotope which do not account for radioactive decay during uptake via the food chain. This study presents estimates for bioaccumulation of radioactive phosphorus which account for both radioactive decay and varying ambient levels of stable P in the environment. Recommended interim CR values for radioactive forms of P as a function of bioavailable stable phosphorus in the water body are presented. Values of CR are presented for three different trophic levels of the aquatic food chain; foodstuffs from all three trophic levels may potentially be consumed by humans. It is concluded that current recommended values of the CR are likely to be significantly over-estimated for radioactive phosphorus in many freshwater systems, particularly lowland rivers. Further research is recommended to field-validate these models and assess their uncertainty. The relative importance of food-chain uptake and direct uptake from water are also assessed from a review of the literature. It can be concluded that food-chain uptake is the dominant accumulation pathway in fish and hence accumulation factors for radioactive phosphorus in farmed fish are likely to be significantly lower than those for wild fish. - Highlights: → A model is developed for radiophosphorus uptake to fish. → Concentration ratios for 32,33 P in fish may be over-estimated in freshwater systems. → New recommended values for 32,33 P concentration ratios are given. → Farmed fish are likely to have much lower 32,33 P uptake than wild fish.

  18. The potential of mixed culture of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) and freshwater giant prawn (Macrobrachium rosenbergii) in periphyton-based systems

    NARCIS (Netherlands)

    Uddin, S.; Azim, M.E.; Wahab, M.A.; Verdegem, M.C.J.

    2006-01-01

    The production performance of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) and freshwater prawn (Macrobrachium rosenbergii) in periphyton-based systems were studied in farmers' ponds at Mymensingh, Bangladesh. Fifteen ponds (200-300 m2 area and 1.0-1.5 m in depth) were used to

  19. Effects of stocking density of freshwater prawn Macrobrachium rosenbergii and addition of different levels of tilapia Oreochromis niloticus on production in C/N controlled periphyton based system

    NARCIS (Netherlands)

    Asaduzzaman, M.; Wahab, M.A.; Verdegem, M.C.J.; Mondal, M.N.; Azim, M.E.

    2009-01-01

    An on-station trial was conducted to evaluate the effect of stocking density of freshwater prawn and addition of different levels of tilapia on production in carbon/nitrogen (C/N) controlled periphyton based system. The experiment had a 2 × 3 factorial design, in which two levels of prawn stocking

  20. Effects of addition of tilapia Oreochromis niloticus and substrates for periphyton developments on pond ecology and production in C/N-controlled freshwater prawn Macrobrachium rosenbergii farming systems

    NARCIS (Netherlands)

    Asaduzzaman, M.; Wahab, M.A.; Verdegem, M.C.J.; Benerjee, S.; Akter, T.; Hasan, M.M.; Azim, M.E.

    2009-01-01

    The present research investigated the effect of addition of tilapia and substrates for periphyton development on pond ecology, production and economic performances in C/N controlled freshwater prawn farming system. The absence and presence (0 and 0.5 individual m- 2) of tilapia were investigated in

  1. Potential impacts of global climate change on the hydrology and ecology of ephemeral freshwater systems of the forests of the northeastern United States

    Science.gov (United States)

    Robert T. Brooks

    2009-01-01

    Global, national, and regional assessments of the potential effects of Global Climate Change (GCC) have been recently released, but not one of these assessments has specifically addressed the critical issue of the potential impacts of GCC on ephemeral freshwater systems (EFS). I suggest that this is a major oversight as EFS occur in various forms across the globe. In...

  2. Migration of sharks into freshwater systems during the Miocene and implications for Alpine paleoelevation

    Science.gov (United States)

    Kocsis, László; Vennemann, Torsten W.; Fontignie, Denis

    2007-05-01

    Trace-element and isotopic compositions of fossilized shark teeth sampled from Miocene marine sediments of the north Alpine Molasse Basin, the Vienna Basin, and the Pannonian Basin generally show evidence of formation in a marine environment under conditions geochemically equivalent to the open ocean. In contrast, two of eight shark teeth from the Swiss Upper Marine Molasse locality of La Molière have extremely low δ18O values (10.3‰ and 11.3‰) and low 87Sr/86Sr ratios (0.707840 and 0.707812) compared to other teeth from this locality (21.1‰ 22.4‰ and 0.708421 0.708630). The rare earth element (REE) abundances and patterns from La Molière not only differ between dentine and enameloid of the same tooth, but also between different teeth, supporting variable conditions of diagenesis at this site. However, the REE patterns of enameloid from the “exotic” teeth analyzed for O and Sr isotopic compositions are similar to those of teeth that have O and Sr isotopic compositions typical of a marine setting at this site. Collectively, this suggests that the two “exotic” teeth were formed while the sharks frequented a freshwater environment with very low 18O-content and Sr isotopic composition controlled by Mesozoic calcareous rocks. This is consistent with a paleogeography of high-elevation (˜2300 m) Miocene Alps adjacent to a marginal sea.

  3. Rapid shallow breathing

    Science.gov (United States)

    Tachypnea; Breathing - rapid and shallow; Fast shallow breathing; Respiratory rate - rapid and shallow ... Shallow, rapid breathing has many possible medical causes, including: Asthma Blood clot in an artery in the ...

  4. The Calibration and error analysis of Shallow water (less than 100m) Multibeam Echo-Sounding System

    Science.gov (United States)

    Lin, M.

    2016-12-01

    Multibeam echo-sounders(MBES) have been developed to gather bathymetric and acoustic data for more efficient and more exact mapping of the oceans. This gain in efficiency does not come without drawbacks. Indeed, the finer the resolution of remote sensing instruments, the harder they are to calibrate. This is the case for multibeam echo-sounding systems (MBES). We are no longer dealing with sounding lines where the bathymetry must be interpolated between them to engender consistent representations of the seafloor. We now need to match together strips (swaths) of totally ensonified seabed. As a consequence, misalignment and time lag problems emerge as artifacts in the bathymetry from adjacent or overlapping swaths, particularly when operating in shallow water. More importantly, one must still verify that bathymetric data meet the accuracy requirements. This paper aims to summarize the system integration involved with MBES and identify the various source of error pertaining to shallow water survey (100m and less). A systematic method for the calibration of shallow water MBES is proposed and presented as a set of field procedures. The procedures aim at detecting, quantifying and correcting systematic instrumental and installation errors. Hence, calibrating for variations of the speed of sound in the water column, which is natural in origin, is not addressed in this document. The data which used in calibration will reference International Hydrographic Organization(IHO) and other related standards to compare. This paper aims to set a model in the specific area which can calibrate the error due to instruments. We will construct a procedure in patch test and figure out all the possibilities may make sounding data with error then calculate the error value to compensate. In general, the problems which have to be solved is the patch test's 4 correction in the Hypack system 1.Roll 2.GPS Latency 3.Pitch 4.Yaw. Cause These 4 correction affect each others, we run each survey line

  5. River dolphins can act as population trend indicators in degraded freshwater systems.

    Directory of Open Access Journals (Sweden)

    Samuel T Turvey

    Full Text Available Conservation attention on charismatic large vertebrates such as dolphins is often supported by the suggestion that these species represent surrogates for wider biodiversity, or act as indicators of ecosystem health. However, their capacity to act as indicators of patterns or trends in regional biodiversity has rarely been tested. An extensive new dataset of >300 last-sighting records for the Yangtze River dolphin or baiji and two formerly economically important fishes, the Yangtze paddlefish and Reeves' shad, all of which are probably now extinct in the Yangtze, was collected during an interview survey of fishing communities across the middle-lower Yangtze drainage. Untransformed last-sighting date frequency distributions for these species show similar decline curves over time, and the linear gradients of transformed last-sighting date series are not significantly different from each other, demonstrating that these species experienced correlated population declines in both timing and rate of decline. Whereas species may be expected to respond differently at the population level even in highly degraded ecosystems, highly vulnerable (e.g. migratory species can therefore display very similar responses to extrinsic threats, even if they represent otherwise very different taxonomic, biological and ecological groupings. Monitoring the status of river dolphins or other megafauna therefore has the potential to provide wider information on the status of other threatened components of sympatric freshwater biotas, and so represents a potentially important monitoring tool for conservation management. We also show that interview surveys can provide robust quantitative data on relative population dynamics of different species.

  6. A multiobjective decision support/numerical modeling approach for design and evaluation of shallow landfill burial systems

    Energy Technology Data Exchange (ETDEWEB)

    Ascough, II, James Clifford [Purdue Univ., Lafayette, IN (United States)

    1992-05-01

    The capability to objectively evaluate design performance of shallow landfill burial (SLB) systems is of great interest to diverse scientific disciplines, including hydrologists, engineers, environmental scientists, and SLB regulators. The goal of this work was to develop and validate a procedure for the nonsubjective evaluation of SLB designs under actual or simulated environmental conditions. A multiobjective decision module (MDM) based on scoring functions (Wymore, 1988) was implemented to evaluate SLB design performance. Input values to the MDM are provided by hydrologic models. The MDM assigns a total score to each SLB design alternative, thereby allowing for rapid and repeatable design performance evaluation. The MDM was validated for a wide range of SLB designs under different climatic conditions. Rigorous assessment of SLB performance also requires incorporation of hydrologic probabilistic analysis and hydrologic risk into the overall design. This was accomplished through the development of a frequency analysis module. The frequency analysis module allows SLB design event magnitudes to be calculated based on the hydrologic return period. The multiobjective decision and freqeuncy anslysis modules were integrated in a decision support system (DSS) framework, SLEUTH (Shallow Landfill Evaluation Using Transport and Hydrology). SLEUTH is a Microsoft Windows {trademark} application, and is written in the Knowledge Pro Windows (Knowledge Garden, Inc., 1991) development language.

  7. A multiobjective decision support/numerical modeling approach for design and evaluation of shallow landfill burial systems

    International Nuclear Information System (INIS)

    Ascough, J.C. II

    1992-05-01

    The capability to objectively evaluate design performance of shallow landfill burial (SLB) systems is of great interest to diverse scientific disciplines, including hydrologists, engineers, environmental scientists, and SLB regulators. The goal of this work was to develop and validate a procedure for the nonsubjective evaluation of SLB designs under actual or simulated environmental conditions. A multiobjective decision module (MDM) based on scoring functions (Wymore, 1988) was implemented to evaluate SLB design performance. Input values to the MDM are provided by hydrologic models. The MDM assigns a total score to each SLB design alternative, thereby allowing for rapid and repeatable design performance evaluation. The MDM was validated for a wide range of SLB designs under different climatic conditions. Rigorous assessment of SLB performance also requires incorporation of hydrologic probabilistic analysis and hydrologic risk into the overall design. This was accomplished through the development of a frequency analysis module. The frequency analysis module allows SLB design event magnitudes to be calculated based on the hydrologic return period. The multiobjective decision and freqeuncy anslysis modules were integrated in a decision support system (DSS) framework, SLEUTH (Shallow Landfill Evaluation Using Transport and Hydrology). SLEUTH is a Microsoft Windows trademark application, and is written in the Knowledge Pro Windows (Knowledge Garden, Inc., 1991) development language

  8. Coupling hydrological and impact assessment models to explore nutrient cycling in freshwater systems

    Science.gov (United States)

    Bouwman, Lex; van Beek, Rens; Beusen, Arthur; Mogollón, José; Middelburg, Jack

    2016-04-01

    The IMAGE-Global Nutrient Model (GNM) is a new globally distributed, spatially explicit model in which the hydrology model PCR-GLOBWB is coupled to the integrated assessment model IMAGE to simulate nitrogen (N) and phosphorus (P) delivery, and then with a spiraling ecological approach to simulating instream biogeochemistry. Routing the water with dissolved and suspended N and P from upstream grid cells occurs simultaneous with N and P delivery to water bodies within grid cells from diffuse and point sources (wastewater). IMAGE-GNM describes the following diffuse sources associated with the water flow: surface runoff, shallow and deep groundwater, riparian zones. Depending on the landscape features, all these flows may be present within one grid cell. Furthermore, diffuse N and P inputs occur through allochtonous organic matter inputs via litterfall in (temporarily) inundated river floodplains, and atmospheric deposition. In the spiraling concept, the residence time of the water and nutrient uptake velocity determine N and P retention in water bodies. Validation of model results with observations yields acceptable agreement given the global scale of the uncalibrated model. Sensitivity analysis shows shifts in the importance of the different sources, with decreasing importance of natural sources and increasing influence of wastewater and agriculture. IMAGE-GNM can be employed to study the interaction between society and the environment over prolonged time periods. Here we show results for the full 20th century.

  9. Tracking of a Fluorescent Dye in a Freshwater Lake with an Unmanned Surface Vehicle and an Unmanned Aircraft System

    Directory of Open Access Journals (Sweden)

    Craig Powers

    2018-01-01

    Full Text Available Recent catastrophic events in our oceans, including the spill of toxic oil from the explosion of the Deepwater Horizon drilling rig and the rapid dispersion of radioactive particulates from the meltdown of the Fukushima Daiichi nuclear plant, underscore the need for new tools and technologies to rapidly respond to hazardous agents. Our understanding of the movement and aerosolization of hazardous agents from natural aquatic systems can be expanded upon and used in prevention and tracking. New technologies with coordinated unmanned robotic systems could lead to faster identification and mitigation of hazardous agents in lakes, rivers, and oceans. In this study, we released a fluorescent dye (fluorescein into a freshwater lake from an anchored floating platform. A fluorometer (fluorescence sensor was mounted underneath an unmanned surface vehicle (USV, unmanned boat and was used to detect and track the released dye in situ in real-time. An unmanned aircraft system (UAS was used to visualize the dye and direct the USV to sample different areas of the dye plume. Image processing tools were used to map concentration profiles of the dye plume from aerial images acquired from the UAS, and these were associated with concentration measurements collected from the sensors onboard the USV. The results of this project have the potential to transform monitoring strategies for hazardous agents, enabling timely and accurate exposure assessment and response in affected areas. Fast response is essential in reacting to the introduction of hazardous agents, in order to quickly predict and contain their spread.

  10. Shallow to intermediate resistivity features of the Colfiorito Fault System inferred by DC and MT survey

    Directory of Open Access Journals (Sweden)

    A. Siniscalchi

    2008-06-01

    Full Text Available Over the last decade electromagnetic (EM measurements have provided new constraints on the upper-crustal structure of the major fault zones in the world, both when they act as conduit and as a barrier, due to strong sensitivity of resistivity to fluids circulation and mineralization. On the track of a high impact magnetotelluric (MT study performed across the San Andreas Fault, high resolution EM data were collected in the Colfiorito epicentral area along profiles crossing some main fault lineaments. Being the study focussed both on shallow that on intermediate resistivity distribution in the brittle upper-crust, a MT profile was integrated by several electrical resistivity tomographies (ERT. The latter were successful in locating faults even where the structures are buried by a wide covering of Quaternary deposits and in the recognition of different electrical signatures of the faults. MT resistivity model crossing Mt. Prefoglio normal fault clearly imaged the typical thrust structures of the area and a high conductive zone spatially related to the fault. Seismicity seems to be located outside such conductive area, whose behaviour suggests a fluidised and altered zone incapable of supporting significant stress internally.

  11. Using growth measures in the freshwater shrimp Caridina nilotica as biomarkers of Roundup® pollution of South African freshwater systems

    Science.gov (United States)

    Mensah, P. K.; Muller, W. J.; Palmer, C. G.

    There has been global concern about the effect of toxic chemicals on aquatic biota due to the upsurge in contamination of aquatic ecosystems by these chemicals, which includes pesticides. Roundup® and other glyphosate-based herbicides are frequently used in the chemical control of weeds and invading alien plant species in South Africa. These bio-active chemicals ultimately get into water courses directly or indirectly through processes such as drifting, leaching, surface runoff and foliar spray of aquatic nuisance plants. However, there is no South African water quality guideline to protect indigenous freshwater non-target organisms from the toxic effects of glyphosate-based herbicides. This study evaluated the possible use of growth measures in Caridina nilotica as biomarkers of Roundup® pollution as part of developing glyphosate water quality guideline for the protection of aquatic life in South Africa. Using static-renewal methods in a 25-day growth toxicity test, 40 days post hatch shrimps were exposed to different sub-lethal Roundup® concentrations of 0.0 (control), 2.2, 2.8, 3.4, 4.3 and 5.4 mg/L. Shrimps were fed daily with TetraMin® flake food and test solutions changed every third day. Shrimp total lengths and wet weights were measured every fifth day. These data were used to determine the shrimp’s growth performance and feed utilization in terms of percent weight gain (PWG), percent length gain (PLG), specific growth rate (SGR), condition factor (CF), feed intake (FI), feed conversion ratio (FCR) and feed conversion efficiency (FCE). Moulting was observed for 14 days and the data used to determine the daily moult rate for each concentration. Results of growth performance and food utilization indices showed that growth was significantly impaired in all exposed groups compared to control (p < 0.05). Moulting frequency was also higher in all exposed groups than in control (p < 0.05). Although all the tested growth measures proved to be possible

  12. DNA barcoding discriminates freshwater fishes from southeastern Nigeria and provides river system-level phylogeographic resolution within some species.

    Science.gov (United States)

    Nwani, Christopher D; Becker, Sven; Braid, Heather E; Ude, Emmanuel F; Okogwu, Okechukwu I; Hanner, Robert

    2011-10-01

    Fishes are the main animal protein source for human beings and play a vital role in aquatic ecosystems and food webs. Fish identification can be challenging, especially in the tropics (due to high diversity), and this is particularly true for larval forms or fragmentary remains. DNA barcoding, which uses the 5' region of the mitochondrial cytochrome c oxidase subunit I (COI) as a target gene, is an efficient method for standardized species-level identification for biodiversity assessment and conservation, pending the establishment of reference sequence libraries. In this study, fishes were collected from three rivers in southeastern Nigeria, identified morphologically, and imaged digitally. DNA was extracted, PCR-amplified, and the standard barcode region was bidirectionally sequenced for 363 individuals belonging to 70 species in 38 genera. All specimen provenance data and associated sequence information were recorded in the barcode of life data systems (BOLD; www.barcodinglife.org ). Analytical tools on BOLD were used to assess the performance of barcoding to identify species. Using neighbor-joining distance comparison, the average genetic distance was 60-fold higher between species than within species, as pairwise genetic distance estimates averaged 10.29% among congeners and only 0.17% among conspecifics. Despite low levels of divergence within species, we observed river system-specific haplotype partitioning within eight species (11.4% of all species). Our preliminary results suggest that DNA barcoding is very effective for species identification of Nigerian freshwater fishes.

  13. Energy sources for chemolithotrophs in an arsenic- and iron-rich shallow-sea hydrothermal system.

    Science.gov (United States)

    Akerman, N H; Price, R E; Pichler, T; Amend, J P

    2011-09-01

    The hydrothermally influenced sediments of Tutum Bay, Ambitle Island, Papua New Guinea, are ideal for investigating the chemolithotrophic activities of micro-organisms involved in arsenic cycling because hydrothermal vents there expel fluids with arsenite (As(III)) concentrations as high as 950 μg L(-1) . These hot (99 °C), slightly acidic (pH ~6), chemically reduced, shallow-sea vent fluids mix with colder, oxidized seawater to create steep gradients in temperature, pH, and concentrations of As, N, Fe, and S redox species. Near the vents, iron oxyhydroxides precipitate with up to 6.2 wt% arsenate (As(V)). Here, chemical analyses of sediment porewaters from 10 sites along a 300-m transect were combined with standard Gibbs energies to evaluate the energy yields (-ΔG(r)) from 19 potential chemolithotrophic metabolisms, including As(V) reduction, As(III) oxidation, Fe(III) reduction, and Fe(II) oxidation reactions. The 19 reactions yielded 2-94 kJ mol(-1) e(-) , with aerobic oxidation of sulphide and arsenite the two most exergonic reactions. Although anaerobic As(V) reduction and Fe(III) reduction were among the least exergonic reactions investigated, they are still potential net metabolisms. Gibbs energies of the arsenic redox reactions generally correlate linearly with pH, increasing with increasing pH for As(III) oxidation and decreasing with increasing pH for As(V) reduction. The calculated exergonic energy yields suggest that micro-organisms could exploit diverse energy sources in Tutum Bay, and examples of micro-organisms known to use these chemolithotrophic metabolic strategies are discussed. Energy modeling of redox reactions can help target sampling sites for future microbial collection and cultivation studies. © 2011 Blackwell Publishing Ltd.

  14. Study of Hydrothermal Particulate Matter from a Shallow Venting System, offshore Nayarit, Mexico

    Science.gov (United States)

    Ortega-Osorio, A.; Prol-Ledesma, R. M.; Reyes, A. G.; Rubio-Ramos, M. A.; Torres-Vera, M. A.

    2001-12-01

    A shallow (30 ft) hydrothermal site named ``Cora'' (after the indigenous people thereby) was surveyed and sampled throughout direct observation with SCUBA diving during November 25 to December 4, 2000. A total of 10 dives were conducted in order to obtain representative samples from an 85oC fluid source of approximately 10 cm in diameter. Inherent difficulties to the sampling, such as poor visibility and strong bottom currents were overcome and samples of hydrothermal fluid, gas, rocks, and particulate matter were collected directly from the vent. Water samples and hydrothermal fluid were taken with a homemade 1 l cylindrical bottles of two lines by flushing in from the bottom for about ten minutes until total displacement of the seawater; similar procedure was carried out for gas samples. Particulate matter was collected with 0.4mm polycarbonate membrane filters and preserved in a desiccators at a fridge temperature until analysis onshore. Preliminary description of the rock samples suggest that pyritization is the main mineralisation process. Filters containing hydrothermal particulate matter were surveyed under the scanning electron microscope in order to identify the nature (inorganic and organic), as well as the chemistry of the particles. SEM examination revealed the presence of particles of different kind that suggests high degree of mixing and re-suspension: Planctonic organisms and organic matter appeared to be abundant; 25 micron particles of different carbonate faces and inorganic particles of silicates were also recognized. Distinctive euhedral colloidal grains were identified as the resulting process of precipitation from the solution. Microanalysis of iron and sulfur content of 10 micron particles indicate a very likely sulphide mineral face (greigite); 8 micron cinnabar particles are consistent with the mineralization conditions, observed as well in the inner walls of the vent. Analyses of dissolved and particulate trace metals are still ongoing at

  15. Appraising options to reduce shallow groundwater tables and enhance flow conditions over regional scales in an irrigated alluvial aquifer system

    Science.gov (United States)

    Morway, Eric D.; Gates, Timothy K.; Niswonger, Richard G.

    2013-01-01

    Some of the world’s key agricultural production systems face big challenges to both water quantity and quality due to shallow groundwater that results from long-term intensive irrigation, namely waterlogging and salinity, water losses, and environmental problems. This paper focuses on water quantity issues, presenting finite-difference groundwater models developed to describe shallow water table levels, non-beneficial groundwater consumptive use, and return flows to streams across two regions within an irrigated alluvial river valley in southeastern Colorado, USA. The models are calibrated and applied to simulate current baseline conditions in the alluvial aquifer system and to examine actions for potentially improving these conditions. The models provide a detailed description of regional-scale subsurface unsaturated and saturated flow processes, thereby enabling detailed spatiotemporal description of groundwater levels, recharge to infiltration ratios, partitioning of ET originating from the unsaturated and saturated zones, and groundwater flows, among other variables. Hybrid automated and manual calibration of the models is achieved using extensive observations of groundwater hydraulic head, groundwater return flow to streams, aquifer stratigraphy, canal seepage, total evapotranspiration, the portion of evapotranspiration supplied by upflux from the shallow water table, and irrigation flows. Baseline results from the two regional-scale models are compared to model predictions under variations of four alternative management schemes: (1) reduced seepage from earthen canals, (2) reduced irrigation applications, (3) rotational lease fallowing (irrigation water leased to municipalities, resulting in temporary dry-up of fields), and (4) combinations of these. The potential for increasing the average water table depth by up to 1.1 and 0.7 m in the two respective modeled regions, thereby reducing the threat of waterlogging and lowering non-beneficial consumptive use

  16. Spatial and temporal characterization of fish assemblages in a tropical coastal system influenced by freshwater inputs: northwestern Yucatan peninsula

    Directory of Open Access Journals (Sweden)

    Daniel Arceo-Carranza

    2009-06-01

    Full Text Available Coastal lagoons are important systems for freshwater, estuarine and marine organisms; they are considered important zones of reproduction, nursery and feeding for many fish species. The present study investigates the fish assemblages of the natural reserve of Dzilam and their relationship with the hydrologic variables. A total of 6 474 individuals (81 species were collected, contributing with more than 50% considering the Importance Value Index (IVI, Sphoeroides testudineus, Fundulus persimilis, Anchoa mitchilli, Eucinostomus gula, Eucinostomus argenteus and Mugil trichodon. Differences in species composition were found between seasons the highest during the cold fronts. Spatially, differences were related with the presence of freshwater seeps, the highest in the ecological characterized eastern part and the lowest with higher difference in specific composition located in the western part of the internal zone, due to a higher abundance and dominance of L. rhomboides. Salinity and temperature were the variables that presented a higher influence in the distribution of some pelagic species such as A. mitchilli and A. hepsetus. Because of the abundant freshwater seeps characteristic of the coastal lagoons of Yucatan Peninsula their community structure and fish assemblage display spatial and temporal differences in specific composition. Rev. Biol. Trop. 57 (1-2: 89-103. Epub 2009 June 30.Las lagunas costeras son sistemas importantes para muchas especies de organismos dulceacuícolas, estuarinos y marinos, ya que son consideradas zonas de reproducción, refugio y alimentación de muchas especies de peces. El presente estudio analizó los ensamblajes de la comunidad íctica de la reserva de Dzilam y su relación con las variables hidrológicas. Se capturaron un total de 6 474 individuos (81 especies, en donde Sphoeroides testudineus, Fundulus persimilis, Anchoa mitchilli, Eucinostomus gula, Eucinostomus argenteus and Mugil trichodon contribuyeron con m

  17. 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...

  18. Do shallow soil, low water availability, or their combination increase the competition between grasses with different root systems in karst soil?

    Science.gov (United States)

    Zhao, Yajie; Li, Zhou; Zhang, Jing; Song, Haiyan; Liang, Qianhui; Tao, Jianping; Cornelissen, Johannes H C; Liu, Jinchun

    2017-04-01

    Uneven soil depth and low water availability are the key limiting factors to vegetation restoration and reconstruction in limestone soils such as in vulnerable karst regions. Belowground competition will possibly increase under limited soil resources. Here, we investigate whether low resource availability (including shallow soil, low water availability, and shallow soil and low water availability combined) stimulates the competition between grasses with different root systems in karst soil, by assessing their growth response, biomass allocation, and morphological plasticity. In a full three-way factorial blocked design of soil depth by water availability by neighbor identity, we grew Festuca arundinacea (deep-rooted) and Lolium perenne (shallow-rooted) under normal versus shallow soil depth, high versus low water availability, and in monoculture (conspecific neighbor) versus mixture (neighbor of the other species). The key results were as follows: (1) total biomass and aboveground biomass in either of the species decreased with reduction of resources but were not affected by planting patterns (monoculture or mixture) even at low resource levels. (2) For F. arundinacea, root biomass, root mass fraction, total root length, and root volume were higher in mixture than in monoculture at high resource level (consistent with resource use complementarity), but lower in mixture than in monoculture at low resource levels (consistent with interspecific competition). In contrast for L. perenne, either at high or low resource level, these root traits had mostly similar values at both planting patterns. These results suggest that deep-rooted and shallow-rooted plant species can coexist in karst regions under current climatic regimes. Declining resources, due to shallow soil, a decrease in precipitation, or combined shallow soil and karst drought, increased the root competition between plants of deep-rooted and shallow-rooted species. The root systems of deep-rooted plants may be

  19. Technical report for a fluidless directional drilling system demonstrated at Solid Waste Storage Area 6 shallow buried waste sites

    International Nuclear Information System (INIS)

    1995-09-01

    The purpose of the research was to demonstrate a fluidless directional drilling and monitoring system (FDD) specifically tailored to address environmental drilling concerns for shallow buried wasted. The major concerns are related to worker exposure, minimizing waste generation, and confining the spread of contamination. The FDD is potentially applicable to Environmental Restoration (ER) activities for the Oak Ridge National Laboratory Waste Area Grouping 6 (WAG 6) shallow buried waste disposed in unlined trenches. Major ER activities for directional drilling are to develop a drilling system for leachate collection directly beneath trenches, and to provide localized control over leachate release to the environment. Other ER FDD activities could include vadose zone and groundwater monitoring of contaminant transport. The operational constraints pointed the research in the direction of purchasing a steerable impact hammer, or mole, manufactured by Steer-Rite Ltd. of Racine, Wisconsin. This drill was selected due to the very low cost ($25,000) associated with procuring the drill, steering module, instrumentation and service lines. The impact hammer is a self propelled drill which penetrates the soil by compacting cut material along the sidewalls of the borehole. Essentially, it forces its way through the subsurface. Although the pneumatic hammer exhausts compressed air which must be handled at the borehole collar, it does not generate soil cuttings or liquids. This is the basis for the term fluidless. A stub casing muffler was attached to the entrance hole for controlling exhaust gas and any airborne releases. Other environmental compliance modifications made to the equipment included operating the tool without lubrication, and using water instead of hydraulic fluid to actuate the steering fins on the tool

  20. Mitigating Groundwater Depletion in North China Plain with Cropping System that Alternate Deep and Shallow Rooted Crops

    Directory of Open Access Journals (Sweden)

    Xiao-Lin Yang

    2017-06-01

    Full Text Available In the North China Plain, groundwater tables have been dropping at unsustainable rates of 1 m per year due to irrigation of a double cropping system of winter wheat and summer maize. To reverse the trend, we examined whether alternative crop rotations could save water. Moisture contents were measured weekly at 20 cm intervals in the top 180 cm of soil as part of a 12-year field experiment with four crop rotations: sweet potato→ cotton→ sweet potato→ winter wheat-summer maize (SpCSpWS, 4-year cycle; peanuts → winter wheat-summer maize (PWS, 2-year cycle; ryegrass–cotton→ peanuts→ winter wheat-summer maize (RCPWS, 3-year cycle; and winter wheat-summer maize (WS, each year. We found that, compared to WS, the SpCSpWS annual evapotranspiration was 28% lower, PWS was 19% lower and RCPWS was 14% lower. The yield per unit of water evaporated improved for wheat within any alternative rotation compared to WS, increasing up to 19%. Average soil moisture contents at the sowing date of wheat in the SpCSpWS, PWS, and RCPWS rotations were 7, 4, and 10% higher than WS, respectively. The advantage of alternative rotations was that a deep rooted crop of winter wheat reaching down to 180 cm followed shallow rooted crops (sweet potato and peanut drawing soil moisture from 0 to 120 cm. They benefited from the sequencing and vertical complementarity of soil moisture extraction. Thus, replacing the traditional crop rotation with cropping system that involves rotating with annual shallow rooted crops is promising for reducing groundwater depletion in the North China Plain.

  1. An Improved GRACE Terrestrial Water Storage Assimilation System For Estimating Large-Scale Soil Moisture and Shallow Groundwater

    Science.gov (United States)

    Girotto, M.; De Lannoy, G. J. M.; Reichle, R. H.; Rodell, M.

    2015-12-01

    The Gravity Recovery And Climate Experiment (GRACE) mission is unique because it provides highly accurate column integrated estimates of terrestrial water storage (TWS) variations. Major limitations of GRACE-based TWS observations are related to their monthly temporal and coarse spatial resolution (around 330 km at the equator), and to the vertical integration of the water storage components. These challenges can be addressed through data assimilation. To date, it is still not obvious how best to assimilate GRACE-TWS observations into a land surface model, in order to improve hydrological variables, and many details have yet to be worked out. This presentation discusses specific recent features of the assimilation of gridded GRACE-TWS data into the NASA Goddard Earth Observing System (GEOS-5) Catchment land surface model to improve soil moisture and shallow groundwater estimates at the continental scale. The major recent advancements introduced by the presented work with respect to earlier systems include: 1) the assimilation of gridded GRACE-TWS data product with scaling factors that are specifically derived for data assimilation purposes only; 2) the assimilation is performed through a 3D assimilation scheme, in which reasonable spatial and temporal error standard deviations and correlations are exploited; 3) the analysis step uses an optimized calculation and application of the analysis increments; 4) a poor-man's adaptive estimation of a spatially variable measurement error. This work shows that even if they are characterized by a coarse spatial and temporal resolution, the observed column integrated GRACE-TWS data have potential for improving our understanding of soil moisture and shallow groundwater variations.

  2. Coupling of hydrogeological models with hydrogeophysical data to characterize seawater intrusion and shallow geothermal systems

    Science.gov (United States)

    Beaujean, J.; Kemna, A.; Engesgaard, P. K.; Hermans, T.; Vandenbohede, A.; Nguyen, F.

    2013-12-01

    case are tested. They consist in a thermal injection and storage of water in a shallow sandy aquifer. The use of a physically-based constraint accounting for the difference in conductivity between the formation and the tap injected water and based on the hydrogeological model calibrated first on temperatures is necessary to improve the parameter estimation. Results suggest that time-lapse ERT data may be limited but useful information for estimating groundwater flow and transport parameters for both the convection and conduction phases.

  3. Is it only CO{sub 2} that matters? A life cycle perspective on shallow geothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Saner, Dominik; Juraske, Ronnie; Hellweg, Stefanie [Group for Ecological Systems Design, Institute of Environmental Engineering, ETH Zurich, Schafmattstrasse 6, CH-8093 Zurich (Switzerland); Kuebert, Markus [Systherma GmbH, Am Haag 12, D-72181 Starzach-Felldorf (Germany); Blum, Philipp [Karlsruhe Institute of Technology (KIT), Institute for Applied Geosciences (AGW), Kaiserstrasse 12, D-76131 Karlsruhe (Germany); Bayer, Peter [Engineering Geology, Geological Institute, ETH Zurich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland)

    2010-09-15

    Shallow geothermal systems such as open and closed geothermal heat pump (GHP) systems are considered to be an efficient and renewable energy technology for cooling and heating of buildings and other facilities. The numbers of installed ground source heat pump (GSHP) systems, for example, is continuously increasing worldwide. The objective of the current study is not only to discuss the net energy consumption and greenhouse gas (GHG) emissions or savings by GHP operation, but also to fully examine environmental burdens and benefits related to applications of such shallow geothermal systems by employing a state-of the-art life cycle assessment (LCA). The latter enables us to assess the entire energy flows and resources use for any product or service that is involved in the life cycle of such a technology. The applied life cycle impact assessment methodology (ReCiPe 2008) shows the relative contributions of resources depletion (34%), human health (43%) and ecosystem quality (23%) of such GSHP systems to the overall environmental damage. Climate change, as one impact category among 18 others, contributes 55.4% to the total environmental impacts. The life cycle impact assessment also demonstrates that the supplied electricity for the operation of the heat pump is the primary contributor to the environmental impact of GSHP systems, followed by the heat pump refrigerant, production of the heat pump, transport, heat carrier liquid, borehole and borehole heat exchanger (BHE). GHG emissions related to the use of such GSHP systems are carefully reviewed; an average of 63 t CO{sub 2} equivalent emissions is calculated for a life cycle of 20 years using the Continental European electricity mix with 0.599 kg CO{sub 2} eq/kWh. However, resulting CO{sub 2} eq savings for Europe, which are between -31% and 88% in comparison to conventional heating systems such as oil fired boilers and gas furnaces, largely depend on the primary resource of the supplied electricity for the heat pump

  4. Metabolomics to Explore Imidacloprid-Induced Toxicity in the Central Nervous System of the Freshwater Snail Lymnaea stagnalis.

    Science.gov (United States)

    Tufi, Sara; Stel, Jente M; de Boer, Jacob; Lamoree, Marja H; Leonards, Pim E G

    2015-12-15

    Modern toxicology is seeking new testing methods to better understand toxicological effects. One of the most concerning chemicals is the neonicotinoid pesticide imidacloprid. Although imidacloprid is designed to target insects, recent studies have shown adverse effects on nontarget species. Metabolomics was applied to investigate imidacloprid-induced sublethal toxicity in the central nervous system of the freshwater snail Lymnaea stagnalis. The snails (n = 10 snails) were exposed for 10 days to increasing imidacloprid concentrations (0.1, 1, 10, and 100 μg/L). The comparison between control and exposure groups highlighted the involvement and perturbation of many biological pathways. The levels of several metabolites belonging to different metabolite classes were significantly changed by imidacloprid exposure. A change in the amino acids and nucleotide metabolites like tryptophan, proline, phenylalanine, uridine, and guanosine was found. Many fatty acids were down-regulated, and the levels of the polyamines, spermidine and putrescine, were found to be increased which is an indication of neuron cell injury. A turnover increase between choline and acetylcholine led us to hypothesize an increase in cholinergic gene expression to overcome imidacloprid binding to the nicotinic acetylcholine receptors. Metabolomics revealed imidacloprid induced metabolic changes at low and environmentally relevant concentration in a nontarget species and generated a novel mechanistic hypothesis.

  5. Cultivation-Independent and Cultivation-Dependent Analysis of Microbes in the Shallow-Sea Hydrothermal System Off Kueishantao Island, Taiwan: Unmasking Heterotrophic Bacterial Diversity and Functional Capacity.

    Science.gov (United States)

    Tang, Kai; Zhang, Yao; Lin, Dan; Han, Yu; Chen, Chen-Tung A; Wang, Deli; Lin, Yu-Shih; Sun, Jia; Zheng, Qiang; Jiao, Nianzhi

    2018-01-01

    Shallow-sea hydrothermal systems experience continuous fluctuations of physicochemical conditions due to seawater influx which generates variable habitats, affecting the phylogenetic composition and metabolic potential of microbial communities. Until recently, studies of submarine hydrothermal communities have focused primarily on chemolithoautotrophic organisms, however, there have been limited studies on heterotrophic bacteria. Here, fluorescence in situ hybridization, high throughput 16S rRNA gene amplicon sequencing, and functional metagenomes were used to assess microbial communities from the shallow-sea hydrothermal system off Kueishantao Island, Taiwan. The results showed that the shallow-sea hydrothermal system harbored not only autotrophic bacteria but abundant heterotrophic bacteria. The potential for marker genes sulfur oxidation and carbon fixation were detected in the metagenome datasets, suggesting a role for sulfur and carbon cycling in the shallow-sea hydrothermal system. Furthermore, the presence of diverse genes that encode transporters, glycoside hydrolases, and peptidase indicates the genetic potential for heterotrophic utilization of organic substrates. A total of 408 cultivable heterotrophic bacteria were isolated, in which the taxonomic families typically associated with oligotrophy, copiotrophy, and phototrophy were frequently found. The cultivation-independent and -dependent analyses performed herein show that Alphaproteobacteria and Gammaproteobacteria represent the dominant heterotrophs in the investigated shallow-sea hydrothermal system. Genomic and physiological characterization of a novel strain P5 obtained in this study, belonging to the genus Rhodovulum within Alphaproteobacteria, provides an example of heterotrophic bacteria with major functional capacity presented in the metagenome datasets. Collectively, in addition to autotrophic bacteria, the shallow-sea hydrothermal system also harbors many heterotrophic bacteria with versatile

  6. Scale-based freshwater conservation planning: towards protecting freshwater biodiversity in KwaZulu-Natal, South Africa

    CSIR Research Space (South Africa)

    Rivers-Moore, NA

    2011-01-01

    Full Text Available River systems have strong linear linkages and require innovative solutions to capture these linkages from aquatic conservation planners. The authors applied an approach to freshwater conservation planning to freshwater ecosystems of Kwa...

  7. 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 ...

  8. Geogenic arsenic and other trace elements in the shallow hydrogeologic system of Southern Poopó Basin, Bolivian Altiplano

    International Nuclear Information System (INIS)

    Ormachea Muñoz, Mauricio; Wern, Hannes; Johnsson, Fredrick; Bhattacharya, Prosun; Sracek, Ondra; Thunvik, Roger; Quintanilla, Jorge; Bundschuh, Jochen

    2013-01-01

    . Sequential extractions of the sediments together with the calculation of the mineral saturation indices indicate that iron oxides and hydroxides are the important secondary minerals phases which are important adsorbents for As. High pH values, and the competition of As with HCO 3 and dissolved silica for the adsorption sites probably seems to be an important process for the mobilisation of As in the shallow groundwaters of the region. Continuous monitoring and expansion of monitoring systems are necessary prerequisites for better understanding of the pattern of As mobilisation in the Southern Poopó Basin

  9. Geogenic arsenic and other trace elements in the shallow hydrogeologic system of Southern Poopó Basin, Bolivian Altiplano

    Energy Technology Data Exchange (ETDEWEB)

    Ormachea Muñoz, Mauricio, E-mail: ormachea@kth.se [KTH – International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm (Sweden); Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, 303, La Paz (Bolivia, Plurinational State of); Wern, Hannes; Johnsson, Fredrick; Bhattacharya, Prosun [KTH – International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm (Sweden); Sracek, Ondra [Department of Geology, Faculty of Science, Palacký University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Thunvik, Roger [KTH – International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm (Sweden); Quintanilla, Jorge [Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, 303, La Paz (Bolivia, Plurinational State of); Bundschuh, Jochen [KTH – International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm (Sweden); Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, Queensland 4350 (Australia)

    2013-11-15

    analysed. Sequential extractions of the sediments together with the calculation of the mineral saturation indices indicate that iron oxides and hydroxides are the important secondary minerals phases which are important adsorbents for As. High pH values, and the competition of As with HCO{sub 3} and dissolved silica for the adsorption sites probably seems to be an important process for the mobilisation of As in the shallow groundwaters of the region. Continuous monitoring and expansion of monitoring systems are necessary prerequisites for better understanding of the pattern of As mobilisation in the Southern Poopó Basin.

  10. Spatial and temporal distribution of microplastics in water and sediments of a freshwater system (Antuã River, Portugal).

    Science.gov (United States)

    Rodrigues, M O; Abrantes, N; Gonçalves, F J M; Nogueira, H; Marques, J C; Gonçalves, A M M

    2018-08-15

    Microplastics (particles with a sizemicroplastics in freshwater systems is less understood than in marine environment. Hence, the present study aims to provide new insights into microplastics abundances and distribution in Antuã River (Portugal) by applying the isolation method of wet peroxide oxidation with addition of zinc chloride to water and sediment samples collected in March and October 2016, in three sampling sites. The abundance of microplastics in water ranged from 5 to 8.3mgm -3 or 58-193itemsm -3 in March and from 5.8-51.7mgm -3 or 71-1265itemsm -3 in October. In sediments, the abundance ranged from 13.5-52.7mgkg -1 or 100-629itemskg -1 in March and from 2.6-71.4mgkg -1 or 18-514itemskg -1 in October. The water and sediment samples with the greatest abundances were from São João da Madeira and Aguincheira, respectively. Spatio-temporal distribution showed different pattern according to methodological approaches, seasonal and hydrodynamic conditions and the proximity to urban/industry areas. Analysis of plastics by Fourier transform infrared spectroscopy underline polyethylene and polypropylene as the most common polymer types identified in this work. The low medium high oxidation ratio was 56:22:22 (%) in March and 61:31:8 (%) in October. Foams and fibers were the most abundant type in São João da Madeira, while fibers and fragments were the most abundant in Aguincheira and Estarreja in water and sediment samples, respectively. This study emphasizes the importance of rivers as carriage systems of microplastics. Further studies should be performed to identify point sources in order to mitigate the microplastics contamination in aquatic systems. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Dual Pump Recovery (DPR System to Extract Freshwater in Coastal Aquifers

    Directory of Open Access Journals (Sweden)

    C. Otto

    2002-06-01

    Full Text Available The paper describes the hydraulic theory of recovering a dense plume using a newly devised dual pump recover system (DPR and its feasibility to half the remediation time of a contaminated unconfined aquifer in a coastal urban environment. Although the DPR system was successfully applied to clean up the polluted aquifer, the hydraulic principles and techniques are also applicable to extract fresh groundwater from coastal aquifers without the risk of saltwater incursion.

  12. First evidence of "paralytic shellfish toxins" and cylindrospermopsin in a Mexican freshwater system, Lago Catemaco, and apparent bioaccumulation of the toxins in "tegogolo" snails (Pomacea patula catemacensis).

    Science.gov (United States)

    Berry, John P; Lind, Owen

    2010-05-01

    Exposure to cyanobacterial toxins in freshwater systems, including both direct (e.g., drinking water) and indirect (e.g., bioaccumulation in food webs) routes, is emerging as a potentially significant threat to human health. We investigated cyanobacterial toxins, specifically cylindrospermopsin (CYN), the microcystins (MCYST) and the "paralytic shellfish toxins" (PST), in Lago Catemaco (Veracruz, Mexico). Lago Catemaco is a tropical lake dominated by Cylindrospermopsis, specifically identified as Cylindrospermopsis catemaco and Cylindrospermopsis philippinensis, and characterized by an abundant, endemic species of snail (Pomacea patula catemacensis), known as "tegogolos," that is both consumed locally and commercially important. Samples of water, including dissolved and particulate fractions, as well as extracts of tegogolos, were screened using highly specific and sensitive ELISA. ELISA identified CYN and PST at low concentrations in only one sample of seston; however, both toxins were detected at appreciable quantities in tegogolos. Calculated bioaccumulation factors (BAF) support bioaccumulation of both toxins in tegogolos. The presence of CYN in the phytoplankton was further confirmed by HPLC-UV and LC-MS, following concentration and extraction of algal cells, but the toxin could not be confirmed by these methods in tegogolos. These data represent the first published evidence for CYN and the PST in Lago Catemaco and, indeed, for any freshwater system in Mexico. Identification of the apparent bioaccumulation of these toxins in tegogolos may suggest the need to further our understanding of the transfer of cyanobacterial toxins in freshwater food webs as it relates to human health. Copyright 2009 Elsevier Ltd. All rights reserved.

  13. The potential of the fresh-water fern Azolla in aquatic farming systems

    Science.gov (United States)

    Bijl, Peter K.; Werf, vd, Adrie; Schluepmann, Henriette; Reichart, Gert-Jan; Brouwer, Paul; Nierop, Klaas G. J.; Hellgardt, Klaus; Brinkhuis, Henk

    2014-05-01

    With aquatic farming systems a new avenue in agriculture is explored, in which the competition with conventional arable land is avoided. The aquatic, ubiquitous, floating fern Azolla is not yet widely explored as potential crop in such farming systems, despite its high potential because it grows in many natural systems under low-light intensities, has an enormous annual yield, and has special biomass qualities for applications in food, feed and specialty chemical industries. But, what makes Azolla particularly interesting as cost-effective crop is its capability to take up atmospheric nitrogen through symbiosis with nitrogen-fixing bacteria Anabaena azollae. This makes Azolla independent of nitrogen fertilization. In order to explore the potential of Azolla as a crop for a suite of applications, we have assembled a team of expertise: AZOFAST, consisting of agricultural engineers, plant physiologists, chemical engineers and organic chemists. Our growth experiments reveal high annual production yields with constant harvest. We are developing a germination and spore collecting/preservation protocol as a first step to domestication. Finally we have explored the biomass quality of different species of extant Azolla. We performed organic chemical analyses on lipid and tannin extracts, and quantified yields of specific compounds within these fractions. In our presentation we will present some of our results to show the potential of Azolla as a new, sustainable aquatic crop serving all kinds of industrial streams from protein feed to platform chemicals.

  14. A conceptual approach to the biomonitoring of freshwater: the Ecological Ambience System

    Directory of Open Access Journals (Sweden)

    Michel LAFONT

    2001-09-01

    Full Text Available The concept of ecological ambience (Ecological Ambience System, EASY is based on the idea that biocenoses (BIO are not only related to the input of organic and mineral substances (IN but also to the way they are stored and processed by the ecosystem. Storage, assimilation and self-purification processes ("ecosystem defences": ED are likely to vary among the different functional units (FUs of the ecosystem. The functional units have been defined on the basis of a simple physical description of sites in an ecosystem, because the physical structure of these units is considered as being of prime importance in the ED processes. For example, mineral and organic substances may be preferentially stored in fine-sediment units, whereas the mineralization rate of organic matter is more likely to be highest in coarse permeable sediments. If the stream ecosystem is viewed as a mosaic, its overall ecological defences will depend upon: 1 the self-purification capacity of the different functional units; 2 their relative proportion within the ecosystem. The EASY concept is now used for ecological researches and also has several applications in the biomonitoring of running waters, illustrated by the study of the River Dore. Biological compartments, specific for each functional unit, are related to operational bio-indicators to build up a global harmonisation system for biomonitoring indices. Four main biological compartments were defined with their related bio-indicators: 1 general biological quality (IBGN biotic index, 2 biological sediment quality (IOBS oligochaete index, 3 biological water quality (diatom index IBD and 4 biological fish quality (study of fish communities. The selected bio-indicators were adjusted to an ecological classification model (Typic concept. A weighting system of the general ecological quality at a site based on the percentage cover of fine sediments is proposed. This approach can be developed using several other compartments. Major

  15. Application and analytical verification of peracetic acid use in different types of freshwater aquaculture systems

    DEFF Research Database (Denmark)

    Pedersen, Lars-Flemming

    2011-01-01

    of water sanitation with PAA application were used to analytically verify actual PAA concentration under real conditions at different kinds of aquaculture systems. A characteristic instant disinfection demand was found to be significantly positively related to water COD content, and PAA half-lives were...... found to be in the order of a few minutes. The study revealed that PAA degrades so rapidly that insufficient disinfection is a likely outcome. The observations have applications for optimizing water treatment strategies with PAA. The investigations also indicated that the rapid degradation and hence...

  16. 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...

  17. Fault-controlled development of shallow hydrothermal systems: Structural and mineralogical insights from the Southern Andes

    Science.gov (United States)

    Roquer, T.; Arancibia, G.; Rowland, J. V.; Iturrieta, P. C.; Morata, D.; Cembrano, J. M.

    2017-12-01

    Paleofluid-transporting systems can be recognized as meshes of fracture-filled veins in eroded zones of extinct hydrothermal systems. Here we conducted meso-microstructural analysis and mechanical modeling from two exhumed exposures of the faults governing regional tectonics of the Southern Andes: the Liquiñe-Ofqui Fault System (LOFS) and the Andean Transverse Faults (ATF). A total of 107 fractures in both exposures were analyzed. The ATF specific segment shows two tectonic solutions that can be modeled as Andersonian and non-Andersonian tectonic regimes: (1) shear (mode II/III) failure occurs at differential stresses > 28 MPa and fluid pressures 85-98% lithostatic in the non-Andersonian regime. Additionally, the LOFS exposure cyclically fails in extension (mode I) or extension + shear (modes I + II/III) in the Andersonian regime, at differential stresses 40-80% lithostatic. In areas of spatial interaction between ATF and LOFS, these conditions might favor: (1) the storage of overpressured fluids in hydrothermal systems associated with the ATF faults, and (2) continuous fluid flow through vertical conduits in the LOFS faults. These observations suggest that such intersections are highly probable locations for concentrated hydrothermal activity, which must be taken into consideration for further geothermal exploration. ACKNOWLEDGEMENTS. PhD CONICYT grants, Centro de Excelencia en Geotermia de los Andes (CEGA-FONDAP/CONICYT Project #15090013), FONDECYT Project #1130030 and Project CONICYT REDES #140036.

  18. Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: are benthic systems at risk?

    Science.gov (United States)

    This study investigated phototoxicity of TiO2 nanoparticles (nano-TiO2) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was p...

  19. Using environmental tracers in modeling flow in a complex shallow aquifer system

    DEFF Research Database (Denmark)

    Troldborg, Lars; Jensen, Karsten Høgh; Engesgaard, Peter Knudegaard

    2008-01-01

    shapes and sizes without being similar to the assumed age distributions used in the analytical approach. The shape of age distribution to some extent depends on sampling size and on whether the system is modeled in a transient or in a steady state, but shape and size were largely driven......Using environmental tracers in groundwater dating partly relies on the assumption that groundwater age distribution can be described analytically. To investigate the applicability of age dating in complex multiaquifer systems, a methodology for simulating well specific groundwater age distribution...... was developed. Using a groundwater model and particle tracking we modeled age distributions at screen locations. By enveloping modeled age distributions and estimated recharge concentrations, environmental tracer breakthroughs were simulated for specific screens. Simulated age distributions are of irregular...

  20. Automated pipe handling systems for new and retrofit applications in shallow drilling markets

    Energy Technology Data Exchange (ETDEWEB)

    McDougall, P.; Fikowski, L.M. [Blackbird Well Servicing Inc., Calgary, AB (Canada)

    2003-07-01

    This presentation discussed the importance of the human interface as the main element in the development of automated mechanical systems on drilling rigs. Improvements in drilling rig designs are meant to improve manpower efficiencies and performance. The goal for Blackbird Well Servicing is to design automated and integrated processes that can be controlled manually at any point during an operation. Although some drilling operations can be fully automated and fully integrated, certain steps in the process are intentionally left open ended for human intervention. It was concluded that the consistency of performance is the most significant feature of integrated systems and that all drilling contractors should strive for smooth, steady performance rather than brute labour. Speed and efficiency increases with consistent performance. Reliability results in better performance, thereby lowering operating costs and more work for drilling contractors.

  1. Transition Funding for the Shallow Water Integrated Mapping System SWIMS and Modular Microstructure Profiler MMP

    Science.gov (United States)

    2013-09-30

    the performance of operational and climate models, as well as for understanding local problems such as pollutant dispersal and biological...Mapping System (SWIMS) and Modular Microstructure Profiler (MMP) Matthew H. Alford Applied Physics Laboratory 1013 NE 40th Street Seattle, WA...in Juan de Fuca Submarine Canyon . Measurements were successful. In the next few weeks we will be testing MMP from our local work boat, the R/V Jack

  2. Acoustic mapping of shallow water gas releases using shipborne multibeam systems

    Science.gov (United States)

    Urban, Peter; Köser, Kevin; Weiß, Tim; Greinert, Jens

    2015-04-01

    Water column imaging (WCI) shipborne multibeam systems are effective tools for investigating marine free gas (bubble) release. Like single- and splitbeam systems they are very sensitive towards gas bubbles in the water column, and have the advantage of the wide swath opening angle, 120° or more allowing a better mapping and possible 3D investigations of targets in the water column. On the downside, WCI data are degraded by specific noise from side-lobe effects and are usually not calibrated for target backscattering strength analysis. Most approaches so far concentrated on manual investigations of bubbles in the water column data. Such investigations allow the detection of bubble streams (flares) and make it possible to get an impression about the strength of detected flares/the gas release. Because of the subjective character of these investigations it is difficult to understand how well an area has been investigated by a flare mapping survey and subjective impressions about flare strength can easily be fooled by the many acoustic effects multibeam systems create. Here we present a semi-automated approach that uses the behavior of bubble streams in varying water currents to detect and map their exact source positions. The focus of the method is application of objective rules for flare detection, which makes it possible to extract information about the quality of the seepage mapping survey, perform automated noise reduction and create acoustic maps with quality discriminators indicating how well an area has been mapped.

  3. Phylogeography, historical demography and distribution modelling of freshwater fishes inhabiting seasonally fluctuating Mediterranean river systems: a case study using the Iberian cyprinid Squalius valentinus

    Directory of Open Access Journals (Sweden)

    Silvia Perea

    2015-12-01

    freshwater species inhabiting seasonally fluctuating river systems.

  4. Shallow End Response from ATEM

    Science.gov (United States)

    Vetrov, A.

    2014-12-01

    Different geological, hydrological, environmental and engineering targets are located shallow underground. The information collected with ATEM systems might be very useful for their study; although there are many deeper targets that the ATEM systems are traditionally used for. The idea to raise magnetic moment output and get deeper penetration response was one of the goals of ATEM systems development during the last decade. The shallow geology response was a trade for such systems, which sometimes were almost blind in the first hundred meter under surface. The possibility to achieve shallow end response from ATEM systems has become significant subject in last years. Several airborne TDEM systems got second higher frequency and lower magnetic moment signal to pick up shallow response together with deep one. Having a potential advantage such implementation raises complication and cost of the system. There's no need to receive 500 meter deep response when exploring shallow geology. P-THEM system having a compact size transmitter and relatively light weight is working on one base frequency at a time, but this frequency can be preset before a flight considering survey goals. A study of shallow geology response of the P-THEM system working on different base frequency has been conducted in 2014 in Ontario. The Alliston test area located in Southern Ontario has been flown with the P-THEM system working on base frequencies 30Hz and 90Hz. Results of the observations will be discussed in the presentation. The shallow end data can be used for mineral exploration applications and also for hydrological and environmental studies.

  5. Shallow water effects on wave energy converters with hydraulic power take-off system

    Directory of Open Access Journals (Sweden)

    Ashank Sinha

    2016-12-01

    Full Text Available The effect of water depth on the power absorption by a single heaving point absorber wave energy converter, attached to a hydraulic power take-off system, is simulated and analysed. The wave energy flux for changing water depths is presented and the study is carried out at a location in the north-west Portuguese coast, favourable for wave power generation. This analysis is based on a procedure to modify the wave spectrum as the water depth reduces, namely, the TMA spectrum (Transformation spectrum. The present study deals with the effect of water depth on the spectral shape and significant wave heights. The reactive control strategy, which includes an external damping coefficient and a negative spring term, is used to maximize power absorption by the wave energy converter. The presented work can be used for making decisions regarding the best water depth for the installation of point absorber wave energy converters in the Portuguese nearshore.

  6. Design and analysis of a SVE system in a shallow water table application

    International Nuclear Information System (INIS)

    Swingle, T.P.; Leachman, W.D.

    1995-01-01

    Cummins Southeastern Power, Inc. (CSPI) operates a diesel engine repair facility in Hialeah Gardens, FL. Parsons Engineering Science, Inc. (Parsons ES) was retained to design a treatment system to remediate soil and hydrocarbons beneath the CSPI service building. Soil vapor extraction (SVE) followed by bioventing was selected as the most appropriate and cost effective approach. These activities were completed as part of CSPI's overall environmental program, which includes cleanup of any contamination that is encountered at their facilities and continual implementation of new measures to prevent future contamination from occurring. This paper presents a complete case history outlining the unique technical challenges associated with the CSPI site conditions. The methods utilized during completion and analysis of the pilot test are discussed and a description of how the pilot data was utilized for completion of the full-scale design is included. The paper presents the empirical analysis method which was developed during this design and shows how it can be applied to other SVE remediation applications

  7. Multivariate analysis of the heterogeneous geochemical processes controlling arsenic enrichment in a shallow groundwater system.

    Science.gov (United States)

    Huang, Shuangbing; Liu, Changrong; Wang, Yanxin; Zhan, Hongbin

    2014-01-01

    The effects of various geochemical processes on arsenic enrichment in a high-arsenic aquifer at Jianghan Plain in Central China were investigated using multivariate models developed from combined adaptive neuro-fuzzy inference system (ANFIS) and multiple linear regression (MLR). The results indicated that the optimum variable group for the AFNIS model consisted of bicarbonate, ammonium, phosphorus, iron, manganese, fluorescence index, pH, and siderite saturation. These data suggest that reductive dissolution of iron/manganese oxides, phosphate-competitive adsorption, pH-dependent desorption, and siderite precipitation could integrally affect arsenic concentration. Analysis of the MLR models indicated that reductive dissolution of iron(III) was primarily responsible for arsenic mobilization in groundwaters with low arsenic concentration. By contrast, for groundwaters with high arsenic concentration (i.e., > 170 μg/L), reductive dissolution of iron oxides approached a dynamic equilibrium. The desorption effects from phosphate-competitive adsorption and the increase in pH exhibited arsenic enrichment superior to that caused by iron(III) reductive dissolution as the groundwater chemistry evolved. The inhibition effect of siderite precipitation on arsenic mobilization was expected to exist in groundwater that was highly saturated with siderite. The results suggest an evolutionary dominance of specific geochemical process over other factors controlling arsenic concentration, which presented a heterogeneous distribution in aquifers. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file.

  8. Seafloor expression and shallow structure of a fold-and-thrust system, Isfjorden, west Spitsbergen

    Directory of Open Access Journals (Sweden)

    Maria Blinova

    2012-09-01

    Full Text Available A detailed map of the structure of the west Spitsbergen fold-and-thrust belt in the Isfjorden area, Spitsbergen, is presented. The map was constructed from a dense grid of two-dimensional multichannel reflection seismic and bathymetric data. Joint interpretation of two data sets allowed a comparison of tectonic structures detected along the uppermost parts of the seismic sections and those reflected in the morphology of the seafloor. Three major, predominantly north-west–south-east striking faults were identified. The westernmost fault (T1 is a hinterland-directed (most likely out of sequence thrust, while the central and easternmost faults (T2 and T3 are foreland-directed (in-sequence thrusts. The thrusts divide Isfjorden into three subareas. Subarea 1 is bounded by thrust faults T1 and T2 and comprises Tertiary rocks surrounded by Jurassic–Cretaceous strata. The structural signature of Subarea 1 is that of a system of hinterland- and foreland-directed thrust faults, resulting in a seafloor relief characterized by parallel ridges and troughs. Subarea 2 is limited by thrust faults T2 and T3 and shows Jurassic–Cretaceous outcrops on the seafloor. Subarea 3 is situated east of the main thrust fault T3 and mainly involves outcrops of Triassic–Jurassic rocks. Together, Subareas 2 and 3 are dominated by foreland-directed, north-west–south-east and NNW–SSE-striking thrusts that are hardly detectable in bathymetric data.

  9. Juvenile fish use of the shallow zone of beaches of the Cananéia-Iguape coastal system, southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Jana Menegassi del Favero

    2015-06-01

    Full Text Available Abstract The purpose of the present study is to describe the juvenile fish use of the shallow zone of beaches of the Cananéia-Iguape coastal system, São Paulo, Brazil, analyzing its occurrence period and the patterns of utilization for the most abundant species. Using a beach seine monthly for one year, we sampled 13861 individuals, of 57 species and 24 families. The fish species used the study area for different proposes: Atherinella brasiliensis was sampled in all phases of gonadal development and considered as resident, juveniles of Trachinotus goodei used the beaches for growth and juveniles of Mugil curema and Mugil liza used the beaches as a route from the ocean to the estuary. Our results showed the importance of the sandy beaches for juvenile fish, especially in spring and summer when most juveniles occur and recruit. Unfortunately, this is the period of the most intense tourist activity. As many of the species studied are commercially important, this study highlighted the necessity of coastal habitat preservation for better fishery management.

  10. Shallow conduit system at Kilauea Volcano, Hawaii, revealed by seismic signals associated with degassing bursts

    Science.gov (United States)

    Chouet, Bernard; Dawson, Phillip

    2011-01-01

    the model elaborated in the 10–50 s band. This dike provides connectivity between the east trending dike and the new vent within Halemaumau Pit Crater. Waveform inversions with a dual-dike model suggest dimensions of 0.7 × 0.7 km to 2.6 × 2.6 km for this segment. Further elaboration of the complex dike system under Halemaumau does not appear to be feasible with presently available data.

  11. Evaluation of butachlor for control of some submerged macrophytes along with its impact on biotic components of freshwater system

    Directory of Open Access Journals (Sweden)

    A. Chattopadhyay, S. Adhikari, S. P. Adhikary, S. Ayyappan

    2006-04-01

    Full Text Available In this investigation, the efficacy of the herbicide butachlor, (N-butoxymethyl-2 chloro-21, 61 diethyl acetanilide was tested against few common submerged macrophytes namely Hydrilla (Hydrilla verticillata (L. Royale, Najas (Najas minor All., Nechamandra (Nechamandra alternifolia (Roxb. Thwaites and Ottelia (Ottelia alismoides (L. Pers. of freshwater fish ponds. Almost complete decay of Hydrilla, Nechamandra and Ottelia was achieved at 7.5 L of active ingredient/ha/m butachlor within 15 days while the herbicide showed no negative effect on Najas. However at the same concentration of butachlor, total mortality of zooplankton and water fern Azolla (Azolla caroliniana Lamarck occurred within seven days. In case of few freshwater fish species like Rohu (Labeo rohita, Channa (Channa punctatus, Anabas (Anabas testitudineus and Heteropneustes (Heteropneustes fossilis, total mortality occurred upto 90 days after application of the same dose of butachlor but fish survived beyond 120 days of herbicide application indicating degradation of the herbicides.

  12. Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: Are benthic systems at risk?

    International Nuclear Information System (INIS)

    Li, Shibin; Wallis, Lindsay K.; Ma, Hongbo; Diamond, Stephen A.

    2014-01-01

    This study investigated phototoxicity of TiO 2 nanoparticles (nano-TiO 2 ) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was performed using dynamic light scattering, UV/Vis spectroscopy, and Scanning Electron Microscopy. Large agglomeration and sedimentation (> 77%) in LSW was observed after 0.5 h. A simulated solar radiation (SSR)-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with the increased attachment. A 96-h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4-h UV exposure of 2.2 W/m 2 . Phototoxicity of nano-TiO 2 under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5–23.3) Wh/m 2 when exposed to 20 mg/L nano-TiO 2 . Also, H. azteca exhibited negative phototaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO 2 to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors suggest further investigations are needed for future risk assessment of photoactive nanomaterials to benthic organisms. - Graphical abstract: Display Omitted - Highlights: •Large aggregation of TiO 2 nanoparticles in Lake Superior water was observed. •Phototoxicity was dependent on the dose of both solar radiation and nanoparticle. •A solar radiation favored surface attachment of nanoparticles was observed. •Hyalella azteca exhibited negative phototaxis in the presence of shelters. •Factors influencing phototoxicity in the real environment were

  13. A single Legionella pneumophila genotype in the freshwater system in a ship experiencing three separate outbreaks of legionellosis in 6 years

    Directory of Open Access Journals (Sweden)

    Catrine Ahlen

    2016-08-01

    Full Text Available Background: Recurrent legionella outbreaks at one and the same location are common. We have identified a single Legionella pneumophila genotype associated with recurrent Legionella outbreaks over 6 years. Methods: Field emergency surveys following Legionella outbreaks were performed on a vessel in 2008, 2009 and 2013. Water samples from both the distribution and technical parts of the potable water system were analyzed with respect to L. pneumophila [Real-Time PCR, cultivation, serotyping and genotyping (PFGE] and free-living amoebae, (FLA. Results: Legionella pneumophila serogroup 1 was present in the ship's potable water system during every outbreak. Genotyping of the 2008 survey material showed two separate PFGE genotypes while those in 2009 and 2013 demonstrated the presence of only one of the two genotypes. FLA with intracellular L. pneumophila of the same genotype were also detected. Analyses of the freshwater system on a ship following three separate Legionella outbreaks, for L. pneumophila and FLAs, revealed a single L. pneumophila genotype and FLA (Hartmanella. Conclusions: It is reasonable to assume that the L. pneumophila genotype detected in the freshwater system was the causal agent in the outbreaks onboard. Persistence of an apparently low-pathogenic L. pneumophila genotype and FLA in a potable water system represent a potential risk for recurrent outbreaks.

  14. Shallow rainwater lenses in deltaic areas with saline seepage

    NARCIS (Netherlands)

    Louw, de P.G.B.; Eeman, S.; Siemon, B.; `Voortman, B.R.; Gunnink, J.; Baaren, E.S.; Oude Essink, G.H.P.

    2011-01-01

    In deltaic areas with saline seepage, freshwater availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence and

  15. 40 CFR 230.43 - Vegetated shallows.

    Science.gov (United States)

    2010-07-01

    ... and eelgrass in estuarine or marine systems as well as a number of freshwater species in rivers and...) releasing chemicals that adversely affect plants and animals; (4) increasing turbidity levels, thereby...

  16. Simulation of the shallow groundwater-flow system in the Forest County Potawatomi Community, Forest County, Wisconsin

    Science.gov (United States)

    Fienen, Michael N.; Saad, David A.; Juckem, Paul F.

    2013-01-01

    The shallow groundwater system in the Forest County Potawatomi Comminity, Forest County, Wisconsin, was simulated by expanding and recalibrating a previously calibrated regional model. The existing model was updated using newly collected water-level measurements, inclusion of surface-water features beyond the previous near-field boundary, and refinements to surface-water features. The updated model then was used to calculate the area contributing recharge for seven existing and three proposed pumping locations on lands of the Forest County Potawatomi Community. The existing wells were the subject of a 2004 source-water evaluation in which areas contributing recharge were calculated using the fixed-radius method. The motivation for the present (2012) project was to improve the level of detail of areas contributing recharge for the existing wells and to provide similar analysis for the proposed wells. Delineated 5- and 10-year areas contributing recharge for existing and proposed wells extend from the areas of pumping to delineate the area at the surface contributing recharge to the wells. Steady-state pumping was simulated for two scenarios: a base-pumping scenario using pumping rates that reflect what the Community currently (2012) pumps (or plans to in the case of proposed wells), and a high-pumping scenario in which the rate was set to the maximum expected from wells installed in this area, according to the Forest County Potawatomi Community Natural Resources Department. In general, the 10-year areas contributing recharge did not intersect surface-water bodies. The 5- and 10-year areas contributing recharge simulated at the maximum pumping rate at Bug Lake Road may intersect Bug Lake. At the casino near the Town of Carter, Wisconsin, the 10-year areas contributing recharge intersect infiltration ponds. At the Devils Lake and Lois Crow Drive wells, areas contributing recharge are near cultural features, including residences.

  17. The efficiency of combined coagulant and ballast to remove harmful cyanobacterial blooms in a tropical shallow system

    NARCIS (Netherlands)

    Miranda, Marcela; Noyma, Natalia; Pacheco, Felipe S.; de Magalhaes, Leonardo; Pinto, Ernani; Santos, Suzan; Soares, Maria Fernanda A.; Huszar, Vera L.; Lürling, Miquel; Marinho, Marcelo M.

    We tested the hypothesis that a combination of coagulant and ballast could be efficient for removal of positively buoyant harmful cyanobacteria in shallow tropical waterbodies, and will not promote the release of cyanotoxins. This laboratory study examined the efficacy of coagulants [polyaluminium

  18. The efficiency of combined coagulant and ballast to remove harmful cyanobacterial blooms in a tropical shallow system

    NARCIS (Netherlands)

    Miranda, Marcela; Noyma, Natália; Pacheco, Felipe S.; Magalhães, de Leonardo; Pinto, Ernani; Santos, Suzan; Soares, Maria Fernanda A.; Huszar, Vera L.; Lurling, Miguel; Marinho, Marcelo M.

    2017-01-01

    We tested the hypothesis that a combination of coagulant and ballast could be efficient for removal of positively buoyant harmful cyanobacteria in shallow tropical waterbodies, and will not promote the release of cyanotoxins. This laboratory study examined the efficacy of coagulants

  19. Simulations of freshwater lens recharge and salt/freshwater interfaces using the HYDRUS and SWI2 packages for MODFLOW

    Directory of Open Access Journals (Sweden)

    Szymkiewicz Adam

    2018-06-01

    Full Text Available The paper presents an evaluation of the combined use of the HYDRUS and SWI2 packages for MODFLOW as a potential tool for modeling recharge in coastal aquifers subject to saltwater intrusion. The HYDRUS package for MODFLOW solves numerically the one-dimensional form of the Richards equation describing water flow in variablysaturated media. The code computes groundwater recharge to or capillary rise from the groundwater table while considering weather, vegetation, and soil hydraulic property data. The SWI2 package represents in a simplified way variable-density flow associated with saltwater intrusion in coastal aquifers. Combining these two packages within the MODFLOW framework provides a more accurate description of vadose zone processes in subsurface systems with shallow aquifers, which strongly depend upon infiltration. The two packages were applied to a two-dimensional problem of recharge of a freshwater lens in a sandy peninsula, which is a typical geomorphologic form along the Baltic and the North Sea coasts, among other places. Results highlighted the sensitivity of calculated recharge rates to the temporal resolution of weather data. Using daily values of precipitation and potential evapotranspiration produced average recharge rates more than 20% larger than those obtained with weekly or monthly averaged weather data, leading to different trends in the evolution of freshwater-saltwater interfaces. Root water uptake significantly influenced both the recharge rate and the position of the freshwater-saltwater interface. The results were less sensitive to changes in soil hydraulic parameters, which in our study were found to affect average yearly recharge rates by up to 13%.

  20. Bi-Hamiltonian systems on the dual of the Lie algebra of vector fields of the circle and periodic shallow water equations

    OpenAIRE

    Kolev, Boris

    2006-01-01

    23 pages; International audience; This paper is a survey article on bi-Hamiltonian systems on the dual of the Lie algebra of vector fields on the circle. We investigate the special case where one of the structures is the canonical Lie-Poisson structure and the second one is constant. These structures called affine or modified Lie-Poisson structures are involved in the integrability of certain Euler equations that arise as models of shallow water waves.

  1. Relative invasion risk for plankton across marine and freshwater systems: examining efficacy of proposed international ballast water discharge standards.

    Directory of Open Access Journals (Sweden)

    Oscar Casas-Monroy

    Full Text Available Understanding the implications of different management strategies is necessary to identify best conservation trajectories for ecosystems exposed to anthropogenic stressors. For example, science-based risk assessments at large scales are needed to understand efficacy of different vector management approaches aimed at preventing biological invasions associated with commercial shipping. We conducted a landscape-scale analysis to examine the relative invasion risk of ballast water discharges among different shipping pathways (e.g., Transoceanic, Coastal or Domestic, ecosystems (e.g., freshwater, brackish and marine, and timescales (annual and per discharge event under current and future management regimes. The arrival and survival potential of nonindigenous species (NIS was estimated based on directional shipping networks and their associated propagule pressure, environmental similarity between donor-recipient ecosystems (based on salinity and temperature, and effects of current and future management strategies (i.e., ballast water exchange and treatment to meet proposed international biological discharge standards. Our findings show that current requirements for ballast water exchange effectively reduce invasion risk to freshwater ecosystems but are less protective of marine ecosystems because of greater environmental mismatch between source (oceanic and recipient (freshwater ecoregions. Future requirements for ballast water treatment are expected to reduce risk of zooplankton NIS introductions across ecosystem types but are expected to be less effective in reducing risk of phytoplankton NIS. This large-scale risk assessment across heterogeneous ecosystems represents a major step towards understanding the likelihood of invasion in relation to shipping networks, the relative efficacy of different invasion management regimes and seizing opportunities to reduce the ecological and economic implications of biological invasions.

  2. Integration of micro-gravity and geodetic data to constrain shallow system mass changes at Krafla Volcano, N Iceland

    Science.gov (United States)

    de Zeeuw-van Dalfsen, Elske; Rymer, Hazel; Williams-Jones, Glyn; Sturkell, Erik; Sigmundsson, Freysteinn

    2006-04-01

    New and previously published micro-gravity data are combined with InSAR data, precise levelling and GPS measurements to produce a model for the processes operating at Krafla volcano, 20 years after its most recent eruption. The data have been divided into two periods: from 1990 to 1995 and from 1996 to 2003 and show that the rate of deflation at Krafla is decaying exponentially. The net micro-gravity change at the centre of the caldera is shown, using the measured free air gradient, to be -85 μGal for the first and -100 μGal for the second period. After consideration of the effects of water extraction by the geothermal power station within the caldera, the net gravity decreases are -73±17 μGal for the first and -65±17 μGal for the second period. These decreases are interpreted in terms of magma drainage. Following a Mogi point source model, we calculate the mass decrease to be ˜2×1010 kg/year reflecting a drainage rate of ˜0.23 m3/s, similar to the ˜0.13 m3/s drainage rate previously found at Askja volcano, N. Iceland. Based on the evidence for deeper magma reservoirs and the similarity between the two volcanic systems, we suggest a pressure-link between Askja and Krafla at deeper levels (at the lower crust or the crust-mantle boundary). After the Krafla fires, co-rifting pressure decrease of a deep source at Krafla stimulated the subsequent inflow of magma, eventually affecting conditions along the plate boundary in N. Iceland, as far away as Askja. We anticipate that the pressure of the deeper reservoir at Krafla will reach a critical value and eventually magma will rise from there to the shallow magma chamber, possibly initiating a new rifting episode. We have demonstrated that by examining micro-gravity and geodetic data, our knowledge of active volcanic systems can be significantly improved.

  3. 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.

  4. Geographical information systems as a tool in limnological studies An applied case study in a shallow .lake of a plain area, Buenos Aires province, Argentina

    International Nuclear Information System (INIS)

    Quiroz, Orlando; Romanelli, Asuncion; Martinez, Daniel

    2009-01-01

    The understanding of the hydrological functioning and the interaction among the different water bodies in an area is essential when a sustainable use of the hydric resources is considered. The aim of the present paper is to assess both hydrological-limnological methods and GIS as an integrated methodology applied to the study of shallow lakes, and the hydrological behavior of shallow wetlands in plain areas. La Salada is an areic permanent shallow lake with an area of 5,78 km 2 located near La Dulce town (SE of Buenos Aires Province, Argentina). In this paper we applied methods and tools of the Geographical information Systems in order to assess both, the evolution and state of the wetland. Topographic profiles, showing the relationship among the lake and the other aquatic systems, and also a multi temporal assessment of the morphometric parameters were performed by using a Digital Terrain Model of the area. A sample grid was designed to obtain bathymetric, hydrogeochemical and isotopic data. The chemical water composition is homogeneous in area and depth. changes in the conductivity values along depth, the isotopic contents and the Gibbs diagram showed that the evaporation is the main process controlling the water chemistry. Physical-chemical parameters established water quality and uses of the lake.

  5. 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 ...

  6. Marine Hydrokinetic (MHK) Systems: A Systems Engineering Approach to Select Locations for the Practical Harvest of Electricity from Shallow Water Tidal Currents

    Science.gov (United States)

    Domenech, John

    Due to increasing atmospheric CO2 concentration and its effect on global climates, the United States Environmental Protection Agency (EPA) proposes a Clean Power Plan (CPP) mandating CO2 reductions which will likely force the early retirement of inefficient, aging power plants. Consequentially, removing these plants equates to a shortfall of approximately 66 GW of electricity. These factors add to the looming resource problems of choosing whether to build large replacement power plants or consider alternative energy sources as a means to help close the gap between electricity supply and demand in a given region. One energy source, shallow water tidal currents, represents opportunities to convert kinetic energy to mechanical forms and provide electricity to homes and businesses. Nearly 2,000 National Oceanic Atmospheric Administration (NOAA) tidal current data points from Maine to Texas are considered. This paper, based on systems engineering thinking, provides key attributes (e.g. turbine efficiency, array size, transmission losses) for consideration as decision makers seek to identify where to site Marine Hydrokinetic (MHK) systems and the number of homes powered by the practical harvest of electricity from tidal currents at those locations with given attributes. A systems engineering process model is proposed for consideration as is a regression based equation to estimate MHK machine parameters needed for power a given number of homes.

  7. Memory-Based Shallow Parsing

    NARCIS (Netherlands)

    Tjong Kim Sang, E.F.

    2002-01-01

    We present memory-based learning approaches to shallow parsing and apply these to five tasks: base noun phrase identification, arbitrary base phrase recognition, clause detection, noun phrase parsing and full parsing. We use feature selection techniques and system combination methods for improving

  8. CDOM fluorescence as a proxy of DOC concentration in natural waters : a comparison of four contrasting tropical systems

    OpenAIRE

    Rochelle Newall, Emma; Hulot, F. D.; Janeau, Jean-Louis; Merroune, A.

    2014-01-01

    Chromophoric dissolved organic matter (CDOM) fluorescence or absorption is often proposed as a rapid alternative to chemical methods for the estimation of bulk dissolved organic carbon (DOC) concentration in natural waters. However, the robustness of this method across a wide range of systems remains to be shown. We measured CDOM fluorescence and DOC concentration in four tropical freshwater and coastal environments (estuary and coastal, tropical shallow lakes, water from the freshwater lens ...

  9. How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?

    Science.gov (United States)

    Watanabe, Kenta; Kuwae, Tomohiro

    2015-04-16

    Carbon captured by marine organisms helps sequester atmospheric CO 2 , especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air-sea CO 2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10-30. Phytoplankton-derived POC dominated the water column POC (65-95%) within this salinity range; however, it was minor in the sediments (3-29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49-78% and 19-36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15-30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO 2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters. They

  10. Numerical simulation of freshwater/seawater interaction in a dual-permeability karst system with conduits: the development of discrete-continuum VDFST-CFP model

    Science.gov (United States)

    Xu, Zexuan; Hu, Bill

    2016-04-01

    Dual-permeability karst aquifers of porous media and conduit networks with significant different hydrological characteristics are widely distributed in the world. Discrete-continuum numerical models, such as MODFLOW-CFP and CFPv2, have been verified as appropriate approaches to simulate groundwater flow and solute transport in numerical modeling of karst hydrogeology. On the other hand, seawater intrusion associated with fresh groundwater resources contamination has been observed and investigated in numbers of coastal aquifers, especially under conditions of sea level rise. Density-dependent numerical models including SEAWAT are able to quantitatively evaluate the seawater/freshwater interaction processes. A numerical model of variable-density flow and solute transport - conduit flow process (VDFST-CFP) is developed to provide a better description of seawater intrusion and submarine groundwater discharge in a coastal karst aquifer with conduits. The coupling discrete-continuum VDFST-CFP model applies Darcy-Weisbach equation to simulate non-laminar groundwater flow in the conduit system in which is conceptualized and discretized as pipes, while Darcy equation is still used in continuum porous media. Density-dependent groundwater flow and solute transport equations with appropriate density terms in both conduit and porous media systems are derived and numerically solved using standard finite difference method with an implicit iteration procedure. Synthetic horizontal and vertical benchmarks are created to validate the newly developed VDFST-CFP model by comparing with other numerical models such as variable density SEAWAT, couplings of constant density groundwater flow and solute transport MODFLOW/MT3DMS and discrete-continuum CFPv2/UMT3D models. VDFST-CFP model improves the simulation of density dependent seawater/freshwater mixing processes and exchanges between conduit and matrix. Continuum numerical models greatly overestimated the flow rate under turbulent flow

  11. 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

  12. Assessing The Ecosystem Service Freshwater Production From An Integrated Water Resources Management Perspective. Case Study: The Tormes Water Resources System (Spain)

    Science.gov (United States)

    Momblanch, Andrea; Paredes-Arquiola, Javier; Andreu, Joaquín; Solera, Abel

    2014-05-01

    The Ecosystem Services are defined as the conditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfil human life. A strongly related concept is the Integrated Water Resources Management. It is a process which promotes the coordinated development and management of water, land and related resources in order to maximise the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems. From these definitions, it is clear that in order to cover so many water management and ecosystems related aspects the use of integrative models is increasingly necessary. In this study, we propose to link a hydrologic model and a water allocation model in order to assess the Freshwater Production as an Ecosystem Service in anthropised river basins. First, the hydrological model allows determining the volume of water generated by each sub-catchment; that is, the biophysical quantification of the service. This result shows the relevance of each sub-catchment as a source of freshwater and how this could change if the land uses are modified. On the other hand, the water management model allocates the available water resources among the different water uses. Then, it is possible to provide an economic value to the water resources through the use of demand curves, or other economic concepts. With this second model, we are able to obtain the economical quantification of the Ecosystem Service. Besides, the influence of water management and infrastructures on the service provision can be analysed. The methodology is applied to the Tormes Water Resources System, in Spain. The software used are EVALHID and SIMGES, for hydrological and management aspects, respectively. Both models are included in the Decision Support System Shell AQUATOOL for water resources planning and management. A scenario approach is presented to illustrate the potential of the methodology, including the current

  13. 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)

  14. Late-stage anhydrite-gypsum-siderite-dolomite-calcite assemblages record the transition from a deep to a shallow hydrothermal system in the Schwarzwald mining district, SW Germany

    Science.gov (United States)

    Burisch, Mathias; Walter, Benjamin F.; Gerdes, Axel; Lanz, Maximilian; Markl, Gregor

    2018-02-01

    The majority of hydrothermal vein systems of economic interest occur at relatively shallow crustal levels, although many of them formed at significantly greater depths. Their present position is a consequence of uplift and erosion. Although, many aspects of their formation are well constrained, the temporal chemical evolution of such systems during uplift and erosion is still poorly understood. These vein minerals comprise calcite, dolomite-ankerite, siderite-magnesite, anhydrite and gypsum forming the last gangue assemblages in Jurassic and Tertiary sulphide-fluorite-quartz-barite veins of the Schwarzwald mining district, SW Germany. Mineral textures of samples from nine localities reveal that in these sequences, mineral precipitation follows a recurring pattern: early calcite is followed by anhydrite or gypsum, siderite and/or dolomite. This succession may repeat up to three times. In-situ (LA-ICP-MS) U-Pb age dating of 15 carbonates from three subsequent generations of the late-stage vein assemblage yield robust ages between 20 and 0.6 Ma. Each mineral sequence forms in a distinctive period of about 2-5 Ma. These ages clearly relate these late-stage mineral phases to the youngest geological episode of the Schwarzwald, which is associated with the Cenozoic Rhine Graben rifting and basement uplift. Based on thermodynamic modelling, the formation of the observed mineral assemblages required an deeply sourced Mg-, Fe- and SO4-rich fluid (b), which was episodically mixed with a shallow crustal HCO3-rich fluid (a). As a consequence of fluid mixing, concentrations of Mg, Fe and SO4 temporarily increased and initiated the formation of the observed sulphate-carbonate mineral sequences. This discontinuous large-scale vertical fluid mixing was presumably directly related to episodes of active tectonics associated with the Cenozoic strike-slip regime of the Upper Rhine Graben. Analogously, episodic fluid mixing is a major key in the formation of older (Jurassic to early

  15. 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.

  16. Multimedia fate modeling of perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS) in the shallow lake Chaohu, China.

    Science.gov (United States)

    Kong, Xiangzhen; Liu, Wenxiu; He, Wei; Xu, Fuliu; Koelmans, Albert A; Mooij, Wolf M

    2018-06-01

    Freshwater shallow lake ecosystems provide valuable ecological services to human beings. However, these systems are subject to severe contamination from anthropogenic sources. Per- and polyfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS), are among the contaminants that have received substantial attention, primarily due to abundant applications, environment persistence, and potential threats to ecological and human health. Understanding the environmental behavior of these contaminants in shallow freshwater lake environments using a modeling approach is therefore critical. Here, we characterize the fate, transport and transformation of both PFOA and PFOS in the fifth largest freshwater lake in China (Chaohu) during a two-year period (2013-2015) using a fugacity-based multimedia fate model. A reasonable agreement between the measured and modeled concentrations in various compartments confirms the model's reliability. The model successfully quantifies the environmental processes and identifies the major sources and input pathways of PFOA and PFOS to the Chaohu water body. Sensitivity analysis reveals the critical role of nonlinear Freundlich sorption, which contributes to a variable fraction of the model true uncertainty in different compartments (8.1%-93.6%). Through additional model scenario analyses, we further elucidate the importance of nonlinear Freundlich sorption that is essential for the reliable model performance. We also reveal the distinct composition of emission sources for the two contaminants, as the major sources are indirect soil volatilization and direct release from human activities for PFOA and PFOS, respectively. The present study is expected to provide implications for local management of PFASs pollution in Lake Chaohu and to contribute to developing a general model framework for the evaluation of PFASs in shallow lakes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Isotopes and Sustainability of the Shallow Groundwater System in Spring and Snake Valleys, Eastern White Pine County, Nevada

    Science.gov (United States)

    Acheampong, S. Y.

    2007-12-01

    A critical component to managing water resources is understanding the source of ground water that is extracted from a well. Detail information on the source of recharge and the age of groundwater is thus vital for the proper assessment, development, management, and monitoring of the groundwater resources in an area. Great differences in the isotopic composition of groundwater in a basin and the basin precipitation imply that the groundwater in the basin originates from a source outside the basin or is recharged under different climatic conditions. The stable isotopes of oxygen and hydrogen in precipitation were compared with the isotopic composition of water from wells, springs, and creeks to evaluate the source of the shallow groundwater recharge in Spring and Snake Valleys, Nevada, as part of an evaluation of the water resources in the area. Delta deuterium and delta oxygen-18 composition of springs, wells, creeks, and precipitation in Spring and Snake Valleys show that groundwater recharge occurs primarily from winter precipitation in the surrounding mountains. The carbon-14 content of the groundwater ranged from 30 to 95 percent modern carbon (pmc). Twenty two of the thirty samples had carbon-14 values of greater than 50 pmc. The relatively high carbon-14 values suggest that groundwater in the area is recharged by modern precipitation and the waters have rapid travel times. Total dissolved solids content of the samples outside the playa areas are generally low, and suggests that the water has a relatively short travel time between the recharge areas and sample sites. The presence of tritium in some of the springs and wells also indicate that groundwater mixes with post 1952 precipitation. Hydrogen bomb tests which began in 1952 in the northern hemisphere added large amounts of tritium to the atmosphere and reached a peak in 1963. The stable isotopic composition, the high carbon-14 activities, and the presence of tritium, show that the shallow groundwater in

  18. Memory-Based Shallow Parsing

    OpenAIRE

    Sang, Erik F. Tjong Kim

    2002-01-01

    We present memory-based learning approaches to shallow parsing and apply these to five tasks: base noun phrase identification, arbitrary base phrase recognition, clause detection, noun phrase parsing and full parsing. We use feature selection techniques and system combination methods for improving the performance of the memory-based learner. Our approach is evaluated on standard data sets and the results are compared with that of other systems. This reveals that our approach works well for ba...

  19. Comparative genomics reveals diversified CRISPR-Cas systems of globally distributed Microcystis aeruginosa, a freshwater bloom-forming cyanobacterium

    Directory of Open Access Journals (Sweden)

    Chen eYang

    2015-05-01

    Full Text Available Microcystis aeruginosa is one of the most common and dominant bloom-forming cyanobacteria in freshwater lakes around the world. Microcystis cells can produce toxic secondary metabolites, such as microcystins, which are harmful to human health. Two M. aeruginosa strains were isolated from two highly eutrophic lakes in China and their genomes were sequenced. Comparative genomic analysis was performed with the 12 other available M. aeruginosa genomes and closely related unicellular cyanobacterium. Each genome of M. aeruginosa containing at least one clustered regularly interspaced short palindromic repeat (CRISPR locus and total 71 loci were identified, suggesting it is ubiquitous in M. aeruginosa genomes. In addition to the previously reported subtype I-D cas gene sets, three CAS subtypes I-A, III-A and III-B were identified and characterized in this study. Seven types of CRISPR direct repeat have close association with CAS subtype, confirming that different and specific secondary structures of CRISPR repeats are important for the recognition, binding and process of corresponding cas gene sets. Homology search of the CRISPR spacer sequences provides a history of not only resistance to bacteriophages and plasmids known to be associated with M. aeruginosa, but also the ability to target much more exogenous genetic material in the natural environment. These adaptive and heritable defense mechanisms play a vital role in keeping genomic stability and self-maintenance by restriction of horizontal gene transfer. Maintaining genomic stability and modulating genomic plasticity are both important evolutionary strategies for M. aeruginosa in adaptation and survival in various habitats.

  20. Leptin-like immunoreactivity in the central nervous system, digestive organs, and gonads of the giant freshwater prawn, Macrobrachium rosenbergii.

    Science.gov (United States)

    Poljaroen, Jaruwan; Tinikul, Yotsawan; Tinikul, Ruchanok; Anurucpreeda, Panat; Sobhon, Prasert

    2017-06-01

    Leptin, a highly conserved adipocyte-derived hormone, plays important roles in a variety of physiological processes, including the control of fat storage and metabolic status which are linked to food intake, energy homeostasis, and reproduction in all vertebrates. In the present study, we hypothesize that leptin is also present in various organs of the fresh water prawns, Macrobrachium rosenbergii. The existence and distribution of a leptin-like peptide in prawn tissues were verified by using Western blotting (WB) and immunohistochemical detection (ID) using primary antibody against human leptin. With WB, a leptin-like peptide, having a molecular weight of 15kDa, was detected in the brain, thoracic ganglia, abdominal ganglia, parts of the gastro-intestinal tract, hepatopancreas, adipocytes and gonads. By ID, leptin immunoreactivity (leptin-ir) was detected in the brain, thoracic ganglia and intersegmental commissural nerve fibers of abdominal ganglia. In the gastrointestinal tract, there was intense leptin-ir in the apical part of the epithelial cells of the cardiac and pyloric parts of the stomach. In the midgut and hindgut, the leptin-ir was detected in epithelial cells and basal cells located near the basal lamina of the epithelium. In addition, there was leptin-ir in the Restzellen cells in the hepatopancreas which produce digestive enzymes. In the ovary, the strong intensity of a leptin-ir was detected in the cytoplasm of middle to late stage oocytes, whereas no positive staining was detected in follicular cells. An intense leptin-ir was detected in spermatocytes and sustentacular cells in the seminiferous tubules in the testes of small and orange claw males. Taken together, the detection of the leptin-ir in several organs implicates the existence of a leptin-like peptide in various organs of the freshwater prawn; and like in vertebrates this peptide may be an important hormonal factor in controlling feeding and reproductive process. Copyright © 2017 Elsevier

  1. Ecotoxicity of CdTe quantum dots to freshwater mussels: Impacts on immune system, oxidative stress and genotoxicity

    International Nuclear Information System (INIS)

    Gagne, F.; Auclair, J.; Turcotte, P.; Fournier, M.; Gagnon, C.; Sauve, S.; Blaise, C.

    2008-01-01

    The purpose of this study was to examine the toxic effects of cadmium-telluride (CdTe) quantum dots on freshwater mussels. Elliption complanata mussels were exposed to increasing concentrations of CdTe (0, 1.6, 4 and 8 mg/L) and cadmium sulfate (CdSO 4 , 0.5 mg/L) for 24 h at 15 o C. After the exposure period, they were removed for assessments of immunocompetence, oxidative stress (lipid peroxidation) and genotoxicity (DNA strand breaks). Preliminary experiments revealed that CdTe dissolved in aquarium water tended to aggregate in the particulate phase (85%) while 15% of CdTe was found in the dissolved phase. Immunotoxicity was characterized by a significant decrease in the number of hemocytes capable of ingesting fluorescent beads, and hemocyte viability. The cytotoxic capacity of hemocytes to lyse mammalian K-562 cells was significantly increased, but the number of circulating hemocytes remained unchanged. Lipid peroxidation was significantly increased at a threshold concentration of 5.6 mg/L in gills and significantly reduced in digestive glands at a threshold concentration <1.6 mg/L CdTe. The levels of DNA strand breaks were significantly reduced in gills at <1.6 mg/L CdTe. In digestive glands, a transient but marginal increase in DNA strand breaks occurred at the lowest concentration and dropped significantly at the higher concentrations. A multivariate analysis revealed that the various response patterns differed based on the concentration of CdTe, thus permitting the identification of biomarkers associated with the form (colloidal vs. molecular) of cadmium

  2. Ecotoxicity of CdTe quantum dots to freshwater mussels: Impacts on immune system, oxidative stress and genotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Gagne, F. [Fluvial Ecosystem Research, Environment Canada, 105 McGill Street, Montreal, Quebec, H2Y 2E7 (Canada)], E-mail: francois.gagne@ec.gc.ca; Auclair, J.; Turcotte, P. [Fluvial Ecosystem Research, Environment Canada, 105 McGill Street, Montreal, Quebec, H2Y 2E7 (Canada); Fournier, M. [INRS-Institut Armand-Frappier, 245 Hymus, Pointe-Claire, Quebec, H9R 3G6 (Canada); Gagnon, C. [Fluvial Ecosystem Research, Environment Canada, 105 McGill Street, Montreal, Quebec, H2Y 2E7 (Canada); Sauve, S. [Departement de Chimie, Universite de Montreal, C.P. 6128, Succursale Centre-ville, Montreal, Quebec, H3C 3J7 (Canada); Blaise, C. [Fluvial Ecosystem Research, Environment Canada, 105 McGill Street, Montreal, Quebec, H2Y 2E7 (Canada)

    2008-02-18

    The purpose of this study was to examine the toxic effects of cadmium-telluride (CdTe) quantum dots on freshwater mussels. Elliption complanata mussels were exposed to increasing concentrations of CdTe (0, 1.6, 4 and 8 mg/L) and cadmium sulfate (CdSO{sub 4}, 0.5 mg/L) for 24 h at 15 {sup o}C. After the exposure period, they were removed for assessments of immunocompetence, oxidative stress (lipid peroxidation) and genotoxicity (DNA strand breaks). Preliminary experiments revealed that CdTe dissolved in aquarium water tended to aggregate in the particulate phase (85%) while 15% of CdTe was found in the dissolved phase. Immunotoxicity was characterized by a significant decrease in the number of hemocytes capable of ingesting fluorescent beads, and hemocyte viability. The cytotoxic capacity of hemocytes to lyse mammalian K-562 cells was significantly increased, but the number of circulating hemocytes remained unchanged. Lipid peroxidation was significantly increased at a threshold concentration of 5.6 mg/L in gills and significantly reduced in digestive glands at a threshold concentration <1.6 mg/L CdTe. The levels of DNA strand breaks were significantly reduced in gills at <1.6 mg/L CdTe. In digestive glands, a transient but marginal increase in DNA strand breaks occurred at the lowest concentration and dropped significantly at the higher concentrations. A multivariate analysis revealed that the various response patterns differed based on the concentration of CdTe, thus permitting the identification of biomarkers associated with the form (colloidal vs. molecular) of cadmium.

  3. Numerical studies of CO2 and brine leakage into a shallow aquifer through an open wellbore

    Science.gov (United States)

    Wang, Jingrui; Hu, Litang; Pan, Lehua; Zhang, Keni

    2018-03-01

    Industrial-scale geological storage of CO2 in saline aquifers may cause CO2 and brine leakage from abandoned wells into shallow fresh aquifers. This leakage problem involves the flow dynamics in both the wellbore and the storage reservoir. T2Well/ECO2N, a coupled wellbore-reservoir flow simulator, was used to analyze CO2 and brine leakage under different conditions with a hypothetical simulation model in water-CO2-brine systems. Parametric studies on CO2 and brine leakage, including the salinity, excess pore pressure (EPP) and initially dissolved CO2 mass fraction, are conducted to understand the mechanism of CO2 migration. The results show that brine leakage rates increase proportionally with EPP and inversely with the salinity when EPP varies from 0.5 to 1.5 MPa; however, there is no CO2 leakage into the shallow freshwater aquifer if EPP is less than 0.5 MPa. The dissolved CO2 mass fraction shows an important influence on the CO2 plume, as part of the dissolved CO2 becomes a free phase. Scenario simulation shows that the gas lifting effect will significantly increase the brine leakage rate into the shallow freshwater aquifer under the scenario of 3.89% dissolved CO2 mass fraction. The equivalent porous media (EPM) approach used to model the wellbore flow has been evaluated and results show that the EPM approach could either under- or over-estimate brine leakage rates under most scenarios. The discrepancies become more significant if a free CO2 phase evolves. Therefore, a model that can correctly describe the complex flow dynamics in the wellbore is necessary for investigating the leakage problems.

  4. Nutrient Enrichment in Estuaries from Discharge of Shallow Ground Water, Mt. Desert Island, Maine

    Science.gov (United States)

    Culbertson, Charles W.; Huntington, Thomas G.; Caldwell, James M.

    2007-01-01

    identified from aerial thermal imagery during flights in May and December 2003 in both estuaries. The occurrence of ground-water seeps was confirmed using continuous and discrete measurements of temperature and specific conductance in selected seeps and in the adjacent estuaries that showed salinity anomalies reflecting the input of freshwater in these complex tidal systems. Analysis of water samples from shallow ground water in the hyporheic zone and from ground-water seeps indicated the presence of elevated concentrations of dissolved nitrogen, compared to concentrations in the adjacent estuaries and surface-water tributaries draining into the estuaries. These findings indicate that shallow ground water is a source of dissolved nitrogen to the estuaries. Orthophosphate levels were low in ground water in the hyporheic zone in Bass Harbor Marsh, but somewhat higher in one hyporheic-zone well in Northeast Creek compared with the concentrations in both estuaries that were at or below detection limits. Household wastewater-related compounds were not detected in ground water in the hyporheic zone. Analysis of water samples from domestic and bedrock monitoring wells developed in fractured bedrock indicated that concentrations of dissolved nitrogen, phosphorus, and household wastewater-related compounds were typically at or below detection, suggesting that the aquifers sampled had not been contaminated from septic sources.

  5. Limnological characterization of freshwater systems of the Thomas Point Oasis (Admiralty Bay, King George Island, West Antarctica)

    Science.gov (United States)

    Nędzarek, Arkadiusz; Pociecha, Agnieszka

    2010-12-01

    Hydrochemical research into the small, shallow water bodies and wetland areas around the Henryk Arctowski Polish Antarctic Station (King George Island) is presented. Concentrations of nitrite, nitrate, ammonium, and total nitrogen in these waters were determined, as were those of reactive and total phosphorous, inorganic carbon, organic carbon, total carbon, silicate, and chloride and sulfate ions. Conductivity and pH were also measured. Average concentrations ranged widely, e.g., total nitrogen 0.176-29.21 mg L -1, total phosphorus 0.022-18.35 mg L -1, total carbon 1.38-26.90 mg L -1, Cl - 30.17-850 mg L -1, and SO 42- 2.11-236 mg L -1. The trophic status was influenced by influxes of nitrogen and phosphorus from penguin rookeries. Selected water bodies supported 31 taxa of algae and 11 invertebrate taxa, with Euglenophyta dominating in waters with high concentrations of ammonium-nitrogen, whereas diatoms characterized Lake Wujka, with low ammonium concentrations. All water bodies studied had rotifers, but crustaceans were only represented in Lake Wujka.

  6. Caribbean shallow water Corallimorpharia

    NARCIS (Netherlands)

    Hartog, J.C.den

    1980-01-01

    The present paper comprises a review of the Caribbean shallow water Corallimorpharia. Six species, belonging to four genera and three families are treated, including Pseudocorynactis caribbeorum gen. nov. spec. nov., a species with tentacular acrospheres containing the largest spirocysts ever

  7. 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

  8. Evaluation of a recirculating pond system for rearing juvenile freshwater mussels at White Sulphur Springs National Fish Hatchery, West Virginia, U.S.A.

    Science.gov (United States)

    Mummert, A.; Newcomb, T.J.; Neves, R.J.; Parker, B.

    2006-01-01

    A recirculating double-pond system at White Sulphur Springs National Fish Hatchery in West Virginia, U.S.A., was evaluated for suitability for culturing juvenile freshwater mussels. Newly metamorphosed juveniles of Villosa iris and Lampsilis fasciola were placed in the system, and their growth and survival were evaluated for 94 days. Throughout the study, parameters of water quality remained within ranges suitable for mussel survival. Planktonic algal densities in the pond system ranged from 2850 to 6892 cells/ml. Thirty-seven algal taxa were identified, primarily green algae (Chlorophyta), diatoms (Bacillariophyceae), and blue-green algae (Cyanoprokaryota). Over the culture period, juveniles of L. fasciola experienced significantly lower (p fasciola may indicate a failure of the flow-through pond environment to meet its habitat requirements or that variable microhabitat conditions within culture containers existed. Growth did not differ significantly between the species (p = 0.13). Survival of V. iris and growth of both species were similar to previous trials to culture juvenile mussels. Survival rates as high as 66.4% at 93 days for V. iris suggest that juveniles of some riverine species can be successfully cultured in a recirculating pond environment.

  9. Episodic deflation-inflation events at Kīlauea Volcano and implications for the shallow magma system: Chapter 11

    Science.gov (United States)

    Anderson, Kyle R.; Poland, Michael; Johnson, Jessica H.; Miklius, Asta; Carey, Rebecca; Cayol, Valérie; Poland, Michael P.; Weis, Dominique

    2015-01-01

    Episodic variations in magma pressures and flow rates at Kīlauea Volcano, defined by a characteristic temporal evolution and termed deflation-inflation (DI) events, have been observed since at least the 1990s. DI events consist of transient, days-long deflations and subsequent reinflations of the summit region, accompanied since 2008 by fluctuations in the surface height of Kīlauea's summit lava lake. After a delay of minutes to hours, these events also often appear along the volcano's East Rift Zone in ground deformation data and as temporary reductions in eruption rate (sometimes followed by brief surges). Notable pauses in DI activity have preceded many eruptive events at Kīlauea. We analyzed more than 500 DI events recorded by borehole tiltmeters at the summit during 2000–2013. Inverse modeling suggests that DI-related ground deformation at the summit is generated by pressure transients in a shallow magma reservoir located beneath the east margin of Halema‘uma‘u Crater and that this reservoir has remained remarkably stable for more than a decade. Utilizing tilt data and variation in the level of the summit lava lake during a large DI event, we estimate a reservoir volume of approximately 1 km3 (0.2–5.5 km3 at 95% confidence).

  10. Testing of Models for Predicting the Behaviour of Radionuclides in Freshwater Systems and Coastal Areas. Report of the Aquatic Working Group of EMRAS Theme 1

    International Nuclear Information System (INIS)

    2012-01-01

    During last decades a number of projects have been launched to validate models for predicting the behaviour of radioactive substances in the environment. Such projects took advantage from the great deal of experimental data gathered, following the accidental introduction of radionuclides into the environment (the accident at the Chernobyl power plant was the most obvious example), to assess the contamination levels of components of the ecosystem and of the human food chain. These projects stimulated intensive efforts for improving the reliability of the models aimed at predicting the migration of 137 Cs in lakes and of 137 Cs and 90 Sr in rivers. However, there are few examples of similar extensive model validation studies for other aquatic systems, such as coastal waters, or for other long lived radionuclides of potential radiological importance for freshwater systems. The validation of models for predicting the behaviour of radionuclides in the freshwater environment and coastal areas was the object of the EMRAS working group on testing of models for predicting the behaviour of radionuclides in freshwater systems and coastal areas. Five scenarios have been considered: (1) Wash-off of 90 Sr and 137 Cs deposits from the Pripyat floodplain (Ukraine). Modellers were asked to predict the time dependent water contamination of Pripyat River following the inundation of the river floodplain heavily contaminated following the Chernobyl accident. Available input data were the deposits of radionuclides in the floodplain, the time dependent contamination of water in the river entering the floodplain, the water fluxes and several other morphological, meteorological and hydrological data. Concentrations of radionuclides in the water of the River Prypiat down-stream of the floodplain were supplied to assess the performances of the models. (2) Radionuclide discharge from the Dnieper River (Ukraine) into its estuary in the Black Sea. Modellers were asked to predict the time

  11. Mass development of monospecific submerged macrophyte vegetation after the restoration of shallow lakes: Roles of light, sediment nutrient levels, and propagule density

    NARCIS (Netherlands)

    Verhofstad, M.J.J.M.; Alirangues Núñez, M. M.; Reichman, E. P.; van Donk, E.; Lamers, L. P.M.; Bakker, E. S.

    2017-01-01

    After restoration, eutrophicated shallow freshwaters may show mass development of only one or two submerged macrophyte species, lowering biodiversity and hampering recreation. It is unclear which environmental factors govern this high percentage of the volume inhabited (PVI2) by submerged

  12. Clicking in shallow rivers: short-range echolocation of Irrawaddy and Ganges River dolphins in a shallow, acoustically complex habitat.

    Directory of Open Access Journals (Sweden)

    Frants H Jensen

    Full Text Available Toothed whales (Cetacea, odontoceti use biosonar to navigate their environment and to find and catch prey. All studied toothed whale species have evolved highly directional, high-amplitude ultrasonic clicks suited for long-range echolocation of prey in open water. Little is known about the biosonar signals of toothed whale species inhabiting freshwater habitats such as endangered river dolphins. To address the evolutionary pressures shaping the echolocation signal parameters of non-marine toothed whales, we investigated the biosonar source parameters of Ganges river dolphins (Platanista gangetica gangetica and Irrawaddy dolphins (Orcaella brevirostris within the river systems of the Sundarban mangrove forest. Both Ganges and Irrawaddy dolphins produced echolocation clicks with a high repetition rate and low source level compared to marine species. Irrawaddy dolphins, inhabiting coastal and riverine habitats, produced a mean source level of 195 dB (max 203 dB re 1 µPapp whereas Ganges river dolphins, living exclusively upriver, produced a mean source level of 184 dB (max 191 re 1 µPapp. These source levels are 1-2 orders of magnitude lower than those of similar sized marine delphinids and may reflect an adaptation to a shallow, acoustically complex freshwater habitat with high reverberation and acoustic clutter. The centroid frequency of Ganges river dolphin clicks are an octave lower than predicted from scaling, but with an estimated beamwidth comparable to that of porpoises. The unique bony maxillary crests found in the Platanista forehead may help achieve a higher directionality than expected using clicks nearly an octave lower than similar sized odontocetes.

  13. Melt extraction during heating and cooling of felsic crystal mushes in shallow volcanic systems: An experimental study

    Science.gov (United States)

    Pistone, M.; Baumgartner, L. P.; Sisson, T. W.; Bloch, E. M.

    2017-12-01

    The dynamics and kinetics of melt extraction in near-solidus, rheologically stalled, felsic crystal mushes (> 50 vol.% crystals) are essential to feeding many volcanic eruptions. At shallow depths (volatile-saturated and may be thermally stable for long time periods (104-107 years). In absence of deformation, residual melt can segregate from the mush's crystalline framework stimulated by: 1) gas injecting from hot mafic magmas into felsic mushes (heating / partial melting scenario), and 2) gas exsolving from the crystallizing mush (cooling / crystallizing scenario). The conditions and efficiency of melt extraction from a mush in the two scenarios are not well understood. Thus, we conducted high-temperature (700 to 850 °C) and -pressure (1.1 kbar) cold seal experiments (8-day duration) on synthetic felsic mushes, composed of water-saturated (4.2 wt.%) rhyodacite melt bearing different proportions of added quartz crystals (60, 70, and 80 vol%; 68 mm average particle size). High-spatial resolution X-ray tomography of run products show: 1) in the heating scenario (> 750 °C) melt has not segregated due to coalescence of vesicles (≤ 23 vol%) and large melt connectivity (> 7 vol% glass) / low pressure gradient for melt movement up to 80 vol% crystals; 2) in the cooling scenario (≤ 750 °C) vesicle (< 11 vol%) coalescence is limited or absent and limited amount of melt (3 to 11 vol%) segregated from sample center to its outer periphery (30 to 100 mm melt-rich lenses), testifying to the efficiency of melt extraction dictated by increasing crystallinity. These results suggest that silicic melt hosted within a crystal-rich mush can accumulate rapidly due to the buildup of modest gas pressures during crystallization at temperatures near the solidus.

  14. Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA

    Science.gov (United States)

    Mills, Taylor J.; Mast, M. Alisa; Thomas, Judith C.; Keith, Gabrielle L.

    2016-01-01

    Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO3 inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO3 application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential source of Se in the future as soluble salts are progressively depleted.

  15. Shallow disposal of radioactive waste

    International Nuclear Information System (INIS)

    1985-02-01

    A review and evaluation of computer codes capable of simulating the various processes that are instrumental in determining the dose rate to individuals resulting from the shallow disposal of radioactive waste was conducted. Possible pathways of contamination, as well as the mechanisms controlling radionuclide movement along these pathways have been identified. Potential transport pathways include the unsaturated and saturated ground water systems, surface water bodies, atmospheric transport and movement (and accumulation) in the food chain. Contributions to dose may occur as a result of ingestion of contaminated water and food, inhalation of contaminated air and immersion in contaminated air/water. Specific recommendations were developed regarding the selection and modification of a model to meet the needs associated with the prediction of dose rates to individuals as a consequence of shallow radioactive waste disposal. Specific technical requirements with regards to risk, sensitivity and uncertainty analyses have been addressed

  16. What is the impact on fish recruitment of anthropogenic physical and structural habitat change in shallow nearshore areas in temperate systems? A systematic review protocol

    DEFF Research Database (Denmark)

    MacUra, B.; Lönnstedt, O.M.; Byström, P.

    2016-01-01

    and spawning habitats of many fish and other aquatic species. Several coastal fish populations have seen marked declines in abundance and diversity during the past two decades. A systematic review on the topic would clarify if anthropogenic physical and structural changes of near-shore areas have effects...... on fish recruitment and which these effects are. Methods: The review will examine how various physical and structural anthropogenic changes of nearshore fish habitats affect fish recruitment. Relevant studies include small- and large-scale field studies in marine and brackish systems or large lakes......Background: Shallow nearshore marine ecosystems are changing at an increasing rate due to a range of human activities such as urbanisation and commercial development. The growing numbers of constructions and other physical and structural alterations of the shoreline often take place in nursery...

  17. System evaluation and microbial analysis of a sulfur cycle-based wastewater treatment process for Co-treatment of simple wet flue gas desulfurization wastes with freshwater sewage.

    Science.gov (United States)

    Qian, Jin; Liu, Rulong; Wei, Li; Lu, Hui; Chen, Guang-Hao

    2015-09-01

    A sulfur cycle-based wastewater treatment process, namely the Sulfate reduction, Autotrophic denitrification and Nitrification Integrated process (SANI(®) process) has been recently developed for organics and nitrogen removal with 90% sludge minimization and 35% energy reduction in the biological treatment of saline sewage from seawater toilet flushing practice in Hong Kong. In this study, sulfate- and sulfite-rich wastes from simple wet flue gas desulfurization (WFGD) were considered as a potential low-cost sulfur source to achieve beneficial co-treatment with non-saline (freshwater) sewage in continental areas, through a Mixed Denitrification (MD)-SANI process trialed with synthetic mixture of simple WFGD wastes and freshwater sewage. The system showed 80% COD removal efficiency (specific COD removal rate of 0.26 kg COD/kg VSS/d) at an optimal pH of 7.5 and complete denitrification through MD (specific nitrogen removal rate of 0.33 kg N/kg VSS/d). Among the electron donors in MD, organics and thiosulfate could induce a much higher denitrifying activity than sulfide in terms of both NO3(-) reduction and NO2(-) reduction, suggesting a much higher nitrogen removal rate in organics-, thiosulfate- and sulfide-based MD in MD-SANI compared to sulfide alone-based autotrophic denitrification in conventional SANI(®). Diverse sulfate/sulfite-reducing bacteria (SRB) genera dominated in the bacterial community of sulfate/sulfite-reducing up-flow sludge bed (SRUSB) sludge without methane producing bacteria detected. Desulfomicrobium-like species possibly for sulfite reduction and Desulfobulbus-like species possibly for sulfate reduction are the two dominant groups with respective abundance of 24.03 and 14.91% in the SRB genera. Diverse denitrifying genera were identified in the bacterial community of anoxic up-flow sludge bed (AnUSB) sludge and the Thauera- and Thiobacillus-like species were the major taxa. These results well explained the successful operation of the lab

  18. Develop guidelines for the design of pillar systems for shallow and intermediate depth, tabular, hard rock mines and provide a methodology for assessing hangingwall stability and support requirements for the panels between pillars

    CSIR Research Space (South Africa)

    York, G

    1998-12-01

    Full Text Available The design of hard rock pillars, in shallow to intermediate depth hard rock mines, has been redefined as the determination of the pillar system load bearing capacity. This entails the ability to design each of the components of the pillar system...

  19. Chemical characteristics of surface systems in the Forsmark area. Visualisation and statistical evaluation of data from surface water, precipitation, shallow groundwater, and regolith

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-02-15

    The Swedish Nuclear Fuel and Waste management Co (SKB) initiated site investigations for a deep repository for spent nuclear fuel at two different sites in Sweden, Forsmark and Oskarshamn, in 2002. This report evaluates the results from chemical investigations of the surface system in the Forsmark area during the period November 2002 - March 2005. The evaluation includes data from surface waters (lakes, streams and the sea), precipitation, shallow groundwater and regolith (till, soil, peat, sediments and biota) in the area. Results from surface waters are not presented in this report since these were treated in a recently published report. The main focus of the study is to visualize the vast amount of data collected hitherto in the site investigations, and to give a chemical characterisation of the investigated media at the site. The results will be used to support the site descriptive models, which in turn are used for safety assessment studies and for the environmental impact assessment. The data used consist of water chemical composition in lakes, streams, coastal sites, and in precipitation, predominantly sampled on a monthly basis, and in groundwater from soil tubes and wells, sampled up to four times per year. Moreover, regolith data includes information on the chemical composition of till, soil, sediment and vegetation samples from the area. The characterisations include all measured chemical parameters, i.e. major and minor constituents, trace elements, nutrients, isotopes and radio nuclides, as well as field measured parameters. The evaluation of data from each medium has been divided into the following parts: Characterisation of individual sampling sites, and comparisons within and among sampling sites as well as comparisons with local, regional and national reference data; Analysis of time trends and seasonal variation (for shallow groundwater); Exploration of relationships among the various chemical parameters. For all investigated parameters, the

  20. Chemical characteristics of surface systems in the Forsmark area. Visualisation and statistical evaluation of data from shallow groundwater, precipitation, and regolith

    International Nuclear Information System (INIS)

    Troejbom, Mats; Soederbaeck, Bjoern

    2006-02-01

    The Swedish Nuclear Fuel and Waste management Co (SKB) initiated site investigations for a deep repository for spent nuclear fuel at two different sites in Sweden, Forsmark and Oskarshamn, in 2002. This report evaluates the results from chemical investigations of the surface system in the Forsmark area during the period November 2002 - March 2005. The evaluation includes data from surface waters (lakes, streams and the sea), precipitation, shallow groundwater and regolith (till, soil, peat, sediments and biota) in the area. Results from surface waters are not presented in this report since these were treated in a recently published report. The main focus of the study is to visualize the vast amount of data collected hitherto in the site investigations, and to give a chemical characterisation of the investigated media at the site. The results will be used to support the site descriptive models, which in turn are used for safety assessment studies and for the environmental impact assessment. The data used consist of water chemical composition in lakes, streams, coastal sites, and in precipitation, predominantly sampled on a monthly basis, and in groundwater from soil tubes and wells, sampled up to four times per year. Moreover, regolith data includes information on the chemical composition of till, soil, sediment and vegetation samples from the area. The characterisations include all measured chemical parameters, i.e. major and minor constituents, trace elements, nutrients, isotopes and radio nuclides, as well as field measured parameters. The evaluation of data from each medium has been divided into the following parts: Characterisation of individual sampling sites, and comparisons within and among sampling sites as well as comparisons with local, regional and national reference data; Analysis of time trends and seasonal variation (for shallow groundwater); Exploration of relationships among the various chemical parameters. For all investigated parameters, the

  1. Changes of freshwater-lens thickness in basaltic island aquifers overlain by thick coastal sediments

    Science.gov (United States)

    Rotzoll, Kolja; Oki, Delwyn S.; El-Kadi, Aly I.

    2010-01-01

    Freshwater-lens thickness and long-term changes in freshwater volume in coastal aquifers are commonly assessed through repeated measurement of salinity profiles from monitor wells that penetrate into underlying salt water. In Hawaii, the thickest measured freshwater lens is currently 262 m in dike-free, volcanic-rock aquifers that are overlain by thick coastal sediments. The midpoint depth (depth where salinity is 50% salt water) between freshwater and salt water can serve as an indicator for freshwater thickness. Most measured midpoints have risen over the past 40 years, indicating a shrinking lens. The mean rate of rise of the midpoint from 1999–2009 varied locally, with faster rates in highly developed areas (1.0 m/year) and slower rates in less developed areas (0.5 m/year). The thinning of the freshwater lenses is the result of long-term groundwater withdrawal and reduced recharge. Freshwater/salt-water interface locations predicted from measured water levels and the Ghyben-Herzberg principle may be deeper than measured midpoints during some periods and shallower during other periods, although depths may differ up to 100 m in some cases. Moreover, changes in the midpoint are slower than changes in water level. Thus, water levels may not be a reliable indicator of the amount of freshwater in a coastal aquifer.

  2. Water quality and emergy evaluation of two freshwater aquacultural systems for eutrophic water in the Controlling by Biological Chains

    Science.gov (United States)

    Xi, L. M.; Liu, C. Q.; Liu, D. F.; Huang, W. L.; Sun, Y.

    2017-08-01

    According to the ecological restoration theory, this experiment establishes aquaculture systems controlled by biological chains in both Xiaoxidian area and Dujiadian area of Baiyangdian Lake separately in order to improve the environment and bring economic benefits. The appearance of Emergy Theory provides a new method for the quantitative analysis of ecological economic system. Based on the analysis of Emergy Theory, this thesis compares the eco-economic systems under different polyculture models between Xiaoxidian area and Dujiadian area. The result demonstrates that Xiaoxidian ecological system is of high Emergy Transformity with higher emergy output and economic income per unit area compared with Dujiadian area. While Dujiadian area has higher Emergy Yield Rate and lower Environment Load Rate. So Dujiadian area is more sustainable due to the overload non-renewable energy of Xiaoxidian area devoted by human. Therefore, it will be better if we adjust and optimize the management of aquaculture system in Xiaoxidian area in order to find a stable equilibrium point between environmental sustainability and economic benefits.

  3. Shallow land burial handbook

    International Nuclear Information System (INIS)

    Stinton, L.H.

    1983-01-01

    The facility development phases (preliminary analysis, site selection, facility design and construction, facility operation, and facility closure/post-closure) are systematically integrated into a logical plan for developing near surface disposal plans. The Shallow Land Burial Handbook provides initial guidance and concepts for understanding the magnitude and the complexity of developing new low-level radioactive waste disposal facilities

  4. Cation exchange in a temporally fluctuating thin freshwater lens on top of saline groundwater

    NARCIS (Netherlands)

    Eeman, S.; Louw, de P.G.B.; Zee, van der S.E.A.T.M.

    2017-01-01

    In coastal-zone fields with a high groundwater level and sufficient rainfall, freshwater lenses are formed on top of saline or brackish groundwater. The fresh and the saline water meet at shallow depth, where a transition zone is found. This study investigates the mixing zone that is characterized

  5. Bioaccumulation, morphological changes, and induction of metallothionein gene expression in the digestive system of the freshwater crab Sinopotamon henanense after exposure to cadmium.

    Science.gov (United States)

    Wu, Hao; Li, Yingjun; Lang, Xingping; Wang, Lan

    2015-08-01

    To study the responses of digestive system of the freshwater crab Sinopotamon henanense to the exposure with cadmium (Cd), crabs were acutely exposed to 7.25, 14.50, and 29.00 mg/l Cd for 96 h and subchronically exposed to 0.725, 1.450, and 2.900 mg/l for 21 days. Cd bioaccumulation in the hepatopancreas and digestive tract (esophagus and intestine) was examined. Furthermore, histopathological alterations of the esophagus, midgut, hindgut, and hepatopancreas were assessed in animals from the 29.0 and 2.90 mg/l Cd treatment groups, and expression of metallothionein messenger RNA (MT mRNA) in the hepatopancreas and intestine was measured in all treatment groups. The results showed difference in the middle and high concentrations between acute and subchronic treatment groups. Cd content in digestive tract after acute 14.5 and 29.0 mg/l Cd exposure was significantly higher than that at subchronic 1.45 and 2.90 mg/l exposure, but Cd levels in hepatopancreas were not significantly different under the same condition. Acute exposure to Cd induced greater morphological damage than subchronic exposure: large areas of epithelial cells were necrotic in hepatopancreas and midgut, which detached from the basal lamina. Vacuolated muscle cells were observed in the hindgut of animals from the acute exposure group, but the changes of esophageal morphology were not obvious after acute or subchronic treatments. The expression of MT mRNA increased with increasing Cd concentration, and MT mRNA level in acute exposure groups was significantly lower when compared to the subchronic exposure groups. Higher Cd content and lower MT mRNA expression in the acutely exposed groups may be responsible for more severe damage of digestive system in these exposure groups.

  6. Low-level multicounter {beta}/{gamma} systems with external guards in surface and shallow underground laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Theodorsson, P [Iceland Univ. (Iceland). Science Inst.

    1997-03-01

    When weak samples are measured it is important that they can be given ample counting time in order to obtain satisfactory accuracy and that the background count rate can be checked well. This calls for a high counting capacity, which multidetectors can bring us. I will discuss development possibilities of low-level {beta}/{gamma} multidetector systems with an external anticosmic shield that will in many cases be operated in underground laboratories. These simple and low-cost system can frequently help us in increasing the number of detectors. Three concepts are combined in these systems: (1) multidetectors, (2) an external anticosmic (or guard) detector arrangement and (3) overburden shielding. (orig.)

  7. Low-level multicounter β/γ systems with external guards in surface and shallow underground laboratories

    International Nuclear Information System (INIS)

    Theodorsson, P.

    1997-01-01

    When weak samples are measured it is important that they can be given ample counting time in order to obtain satisfactory accuracy and that the background count rate can be checked well. This calls for a high counting capacity, which multidetectors can bring us. I will discuss development possibilities of low-level β/γ multidetector systems with an external anticosmic shield that will in many cases be operated in underground laboratories. These simple and low-cost system can frequently help us in increasing the number of detectors. Three concepts are combined in these systems: (1) multidetectors, (2) an external anticosmic (or guard) detector arrangement and (3) overburden shielding. (orig.)

  8. A comparison of freshwater mussels and passive samplers as indicators of heavy metal pollution in aquatic systems

    DEFF Research Database (Denmark)

    Søberg, Laila C.; Vollertsen, Jes; Nielsen, Asbjørn Haaning

    2013-01-01

    under controlled conditions in order to determine whether either system was capable of functioning as a reliable source of data on aquatic pollution. The laboratory results indicated that mussels are useful in this context. However, passive samplers will require further development to be useful since...

  9. 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.

  10. Freshwater conservation planning in South Africa: Milestones to ...

    African Journals Online (AJOL)

    2012-03-01

    Mar 1, 2012 ... freshwaters, implemented through a water resource classifica- tion system ... piled for each of South Africa's 19 Water Management Areas, which are ..... et al., 2011) and integrated water and land-use prioritisation. (Nel et al.

  11. Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Taylor J.; Mast, M. Alisa; Thomas, Judith; Keith, Gabrielle

    2016-10-01

    Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (< 0.5 μg L{sup −1}) to 4070 μg L{sup −1}, and primarily are controlled by high groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO{sub 3} inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO{sub 3} application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential

  12. Septic systems as sources of organic wastewater compounds in domestic drinking water wells in a shallow sand and gravel aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Schaider, Laurel A., E-mail: schaider@silentspring.org; Ackerman, Janet M.; Rudel, Ruthann A.

    2016-03-15

    Domestic drinking water wells serve 44 million people in the US and are common globally. They are often located in areas served by onsite wastewater treatment systems, including septic systems, which can be sources of biological and chemical pollutants to groundwater. In this study we tested 20 domestic drinking water wells in a sand and gravel aquifer on Cape Cod, Massachusetts, USA, for 117 organic wastewater compounds (OWCs) and for inorganic markers of septic system impact. We detected 27 OWCs, including 12 pharmaceuticals, five per- and polyfluoroalkyl substances (PFASs), four organophosphate flame retardants, and an artificial sweetener (acesulfame). Maximum concentrations of several PFASs and pharmaceuticals were relatively high compared to public drinking water supplies in the US. The number of detected OWCs and total concentrations of pharmaceuticals and of PFASs were positively correlated with nitrate, boron, and acesulfame and negatively correlated with well depth. These wells were all located in areas served exclusively by onsite wastewater treatment systems, which are likely the main source of the OWCs in these wells, although landfill leachate may also be a source. Our results suggest that current regulations to protect domestic wells from pathogens in septic system discharges do not prevent OWCs from reaching domestic wells, and that nitrate, a commonly measured drinking water contaminant, is a useful screening tool for OWCs in domestic wells. Nitrate concentrations of 1 mg/L NO{sub 3}-N, which are tenfold higher than local background and tenfold lower than the US federal drinking water standard, were associated with wastewater impacts from OWCs in this study. - Highlights: • We tested 20 domestic drinking water wells for 117 organic wastewater compounds. • PFASs, pharmaceuticals, and an artificial sweetener were most frequently detected. • Nitrate, boron, and well depth were all correlated with PFASs and pharmaceuticals. • Acesulfame

  13. Septic systems as sources of organic wastewater compounds in domestic drinking water wells in a shallow sand and gravel aquifer

    International Nuclear Information System (INIS)

    Schaider, Laurel A.; Ackerman, Janet M.; Rudel, Ruthann A.

    2016-01-01

    Domestic drinking water wells serve 44 million people in the US and are common globally. They are often located in areas served by onsite wastewater treatment systems, including septic systems, which can be sources of biological and chemical pollutants to groundwater. In this study we tested 20 domestic drinking water wells in a sand and gravel aquifer on Cape Cod, Massachusetts, USA, for 117 organic wastewater compounds (OWCs) and for inorganic markers of septic system impact. We detected 27 OWCs, including 12 pharmaceuticals, five per- and polyfluoroalkyl substances (PFASs), four organophosphate flame retardants, and an artificial sweetener (acesulfame). Maximum concentrations of several PFASs and pharmaceuticals were relatively high compared to public drinking water supplies in the US. The number of detected OWCs and total concentrations of pharmaceuticals and of PFASs were positively correlated with nitrate, boron, and acesulfame and negatively correlated with well depth. These wells were all located in areas served exclusively by onsite wastewater treatment systems, which are likely the main source of the OWCs in these wells, although landfill leachate may also be a source. Our results suggest that current regulations to protect domestic wells from pathogens in septic system discharges do not prevent OWCs from reaching domestic wells, and that nitrate, a commonly measured drinking water contaminant, is a useful screening tool for OWCs in domestic wells. Nitrate concentrations of 1 mg/L NO_3-N, which are tenfold higher than local background and tenfold lower than the US federal drinking water standard, were associated with wastewater impacts from OWCs in this study. - Highlights: • We tested 20 domestic drinking water wells for 117 organic wastewater compounds. • PFASs, pharmaceuticals, and an artificial sweetener were most frequently detected. • Nitrate, boron, and well depth were all correlated with PFASs and pharmaceuticals. • Acesulfame (artificial

  14. Septic systems as sources of organic wastewater compounds in domestic drinking water wells in a shallow sand and gravel aquifer.

    Science.gov (United States)

    Schaider, Laurel A; Ackerman, Janet M; Rudel, Ruthann A

    2016-03-15

    Domestic drinking water wells serve 44 million people in the US and are common globally. They are often located in areas served by onsite wastewater treatment systems, including septic systems, which can be sources of biological and chemical pollutants to groundwater. In this study we tested 20 domestic drinking water wells in a sand and gravel aquifer on Cape Cod, Massachusetts, USA, for 117 organic wastewater compounds (OWCs) and for inorganic markers of septic system impact. We detected 27 OWCs, including 12 pharmaceuticals, five per- and polyfluoroalkyl substances (PFASs), four organophosphate flame retardants, and an artificial sweetener (acesulfame). Maximum concentrations of several PFASs and pharmaceuticals were relatively high compared to public drinking water supplies in the US. The number of detected OWCs and total concentrations of pharmaceuticals and of PFASs were positively correlated with nitrate, boron, and acesulfame and negatively correlated with well depth. These wells were all located in areas served exclusively by onsite wastewater treatment systems, which are likely the main source of the OWCs in these wells, although landfill leachate may also be a source. Our results suggest that current regulations to protect domestic wells from pathogens in septic system discharges do not prevent OWCs from reaching domestic wells, and that nitrate, a commonly measured drinking water contaminant, is a useful screening tool for OWCs in domestic wells. Nitrate concentrations of 1mg/L NO3-N, which are tenfold higher than local background and tenfold lower than the US federal drinking water standard, were associated with wastewater impacts from OWCs in this study. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  15. Marine and freshwater toxins.

    Science.gov (United States)

    Hungerford, James M

    2006-01-01

    In a very busy and exciting year, 2005 included First Action approval of a much needed official method for paralytic shellfish toxins and multiple international toxin symposia highlighted by groundbreaking research. These are the first-year milestones and activities of the Marine and Freshwater Toxins Task Force and Analytical Community. Inaugurated in 2004 and described in detail in last year's General Referee Report (1) this international toxins group has grown to 150 members from many regions and countries. Perhaps most important they are now making important and global contributions to food safety and to providing alternatives to animal-based assays. Official Method 2005.06 was first approved in late 2004 by the Task Force and subsequently Official First Action in 2005 (2) by the Methods Committee on Natural Toxins and Food Allergens and the Official Methods Board. This nonproprietary method (3) is a precolumn oxidation, liquid chromatographic method that makes good use of fluorescence detection to provide high sensitivity detection of the saxitoxins. It has also proven to be rugged enough for regulatory use and the highest level of validation. As pointed out in the report of method principle investigator and Study Director James Lawrence, approval of 2005.06 now provides the first official alternative to the mouse bioassay after many decades of shellfish monitoring. This past year in April 2005 the group also held their first international conference, "Marine and Freshwater Toxins Analysis: Ist Joint Symposium and AOAC Task Force Meeting," in Baiona, Spain. The 4-day conference consisted of research and stakeholder presentations and symposium-integrated subgroup sessions on ciguatoxins, saxitoxin assays and liquid chromatography (LC) methods for saxitoxins and domoic acids, okadaiates and azaspiracids, and yessotoxins. Many of these subgroups were recently formed in 2005 and are working towards their goals of producing officially validated analytical methods

  16. Susceptibility of ground water to surface and shallow sources of contamination in Mississippi

    Science.gov (United States)

    O'Hara, Charles G.

    1996-01-01

    Ground water, because of its extensive use in agriculture, industry, and public-water supply, is one of Mississippi's most important natural resources.  Ground water is the source for about 80 percent of the total freshwater used by the State's population (Solley and others, 1993).  About 2,600 Mgal/d of freshwater is withdrawn from aquifers in Mississippi (D.E. Burt, Jr., U.S. Geological Survey, oral commun., 1995).  Wells capable of yielding 200 gal/min of water with quality suitable for most uses can be developed nearly anywhere in the State (Bednar, 1988).  The U.S. Geological Survey (USGS), in cooperation with the Mississippi Department of Environmental Quality, Office of Pollution Control, and the Mississippi Department of Agriculture and Commerce, Bureau of Plant Industry, conducted an investigation to evaluate the susceptibility of ground water to contamination from surgace and shallow sources in Mississippi.  A geographic information system (GIS) was used to develop and analyze statewide spatial data layers that contain geologic, hydrologic, physiographic, and cultural information.

  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. Global lateral transfer and evasion of C in freshwater systems - a revised high-resolution budget analysis

    Science.gov (United States)

    Lauerwald, Ronny; Laruelle, Goulven; Hartmann, Jens; Ciais, Philippe; Regnier, Pierre

    2016-04-01

    The net CO2 evasion from rivers (FCO2) is an important component when quantifying the lateral displacement of biologically fixed carbon from terrestrial systems and wetlands through the river network. Here, we present global maps of FCO2 from stream orders 3 and higher at 0.5° resolution (Lauerwald et al., 2015 - GBC). This resolution is comparable to that of Earth System Model simulations of vegetation and soil C dynamics and is also compatible with GlobalNEWS simulations of fluvial DOC and POC exports to the sea (Mayorga et al., 2010 - Environmental Modeling and Software). A GIS based approach was used to derive an empirical pCO2 model trained on data from 1182 sampling locations. While only few sampling data are available for Asia and Africa, the sampling locations cover the full spectrum from high to low latitudes. The empirical model predicts pCO2 from terrestrial net primary production, population density, and slope gradient within the river catchment and mean air temperature at the sampling location (r² = 0.47). The predicted pCO2 map was combined with spatially explicit estimates of stream surface area and gas exchange velocity calculated from published empirical equations and data sets to derive the FCO2 map. We used Monte Carlo simulations to assess the uncertainties of our estimates. At the global scale, we estimate an average river pCO2 of 2400 (2019-2826) μatm and a FCO2 of 650 (483-846) Tg C yr-1 (5th and 95th percentiles of confidence interval). Our maps reveal strong latitudinal gradients in pCO2, stream surface area, and FCO2. The zone between 10°N and 10°S contributes about half of the global CO2 evasion. Combining riverine FCO2 with the estimated fluvial DOC and POC exports from GlobalNEWS and FCO2 from lakes (downscaled from Raymond et al. 2013 - Nature), the total lateral transfer of biologically fixed C on land and in wetlands adds up to 1.3 Pg C yr-1. This estimate is likely conservative because CO2 evasion from smaller streams is not

  19. Ecological Assessment of Two Species of Potamonautid Freshwater Crabs from the Eastern Highlands of Zimbabwe, with Implications for Their Conservation.

    Directory of Open Access Journals (Sweden)

    Tatenda Dalu

    Full Text Available The spatial ecology of freshwater crabs and their conservation status is largely understudied in Africa. An ecological assessment was conducted at 104 localities in 51 rivers and/or streams in the Eastern Highlands of Zimbabwe whereby the distribution and abundances of freshwater crab species were mapped and the possible drivers of the observed trends in population structure explored. In addition, information on crab utilisation as a food resource by local communities was assessed via face to face interviews across the region. Finally, the conservation status of each species was assessed using the IUCN Red List criteria. Only two crab species Potamonautes mutareensis and Potamonautes unispinus were recorded within the region of study. Potamonautes mutareensis was largely restricted to less impacted environments in the high mountainous river system, whereas P. unispinus was found in low laying areas. In stretches of river where both species were found to co-occur, the species were never sampled from the same site, with P. mutareensis occurring in shallower, faster flowing environments and P. unispinus in deeper, slow flowing sites. Interview results revealed that the local communities, particularly in the southern part of the Eastern Highlands around the Chipinge area, had a considerable level of utilisation (55% of households on the harvesting of crabs for household consumption during the non-agricultural season (May to September. Results from the IUCN Red List assessment indicate that both species should be considered as "Least Concern". Threats to freshwater crabs in the Eastern Highlands, however, include widespread anthropogenic impacts such as habitat destruction associated with gold and diamond mining, inorganic and organic pollution and possibly exploitation for human consumption. The current study provides important information and insight towards the possible development of a freshwater crab conservation action plan within the region.

  20. Facies architecture and high resolution sequence stratigraphy of an aeolian, fluvial and shallow marine system in the Pennsylvanian Piauí Formation, Parnaíba Basin, Brazil

    Science.gov (United States)

    Vieira, Lucas Valadares; Scherer, Claiton Marlon dos Santos

    2017-07-01

    The Pennsylvanian Piauí Formation records the deposition of aeolian, fluvial and shallow marine systems accumulated in the cratonic sag Parnaíba basin. Characterization of the facies associations and sequence stratigraphic framework was done by detailed description and logging of outcrops. Six facies associations were recognized: aeolian dunes and interdunes, aeolian sandsheets, fluvial channels, tidally-influenced fluvial channels, shoreface and shoreface-shelf transition. Through correlation of stratigraphic surfaces, the facies associations were organized in system tracts, which formed eight high frequency depositional sequences, bounded by subaerial unconformities. These sequences are composed of a lowstand system tract (LST), that is aeolian-dominated or fluvial-dominated, a transgressive system tract (TST) that is formed by tidally-influenced fluvial channels and/or shoreface and shoreface-shelf transition deposits with retrogradational stacking, and a highstand system tract (HST), which is formed by shoreface-shelf transition and shoreface deposits with progradational stacking. Two low frequency cycles were determined by observing the stacking of the high frequency cycles. The Lower Sequence is characterized by aeolian deposits of the LST and an aggradational base followed by a progressive transgression, defining a general TST. The Upper Sequence is characterized by fluvial deposits and interfluve pedogenesis concurring with the aeolian deposits of the LST and records a subtle regression followed by transgression. The main control on sedimentation in the Piauí Formation was glacioeustasy, which was responsible for the changes in relative sea level. Even though, climate changes were associated with glacioeustatic phases and influenced the aeolian and fluvial deposition.

  1. Investigation of a new passive sampler for the detection of munitions compounds in marine and freshwater systems.

    Science.gov (United States)

    Warren, Joseph K; Vlahos, Penny; Smith, Richard; Tobias, Craig

    2018-07-01

    Over the last century, unexploded ordnances have been disposed of in marine shelf systems because of a lack of cost-effective alternatives. Underwater unexploded ordnances have the potential to leak 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazine (RDX), commonly used chemical munitions, and contaminate local waters, biota, and sediments. The rate at which this contamination occurs in the environment is relatively unknown, and the cost- and time-prohibitive nature of sampling across sites makes mapping difficult. In the present study we assessed the efficacy of ethylene-vinyl acetate (EVA) for sampling relatively soluble munitions compounds over a range of environmental conditions (i.e., changes in temperature and salinity) and optimized the composition of the passive sampling polymer. The EVA sampler was able to successfully detect ambient concentrations of lingering munitions compounds from field sites containing unexploded ordnances. The sampler affinity for the munitions in terms of an EVA-water partition coefficient was greater than the standard octanol water values for each target compound. Partitioning of compounds onto EVA over the natural ranges of salinity did not change significantly, although uptake varied consistently and predictably with temperature. Increasing the vinyl acetate to ethylene ratio of the polymer corresponded to an increase in uptake capacity, consistent with enhanced dipole-dipole interactions between the munitions and the polymer. This sampler provides a cost-effective means to map and track leakage of unexploded ordnances both spatially and temporally. Environ Toxicol Chem 2018;37:1990-1997. © 2018 SETAC. © 2018 SETAC.

  2. Basic features of the predictive tools of early warning systems for water-related natural hazards: examples for shallow landslides

    Directory of Open Access Journals (Sweden)

    R. Greco

    2017-12-01

    Full Text Available To manage natural risks, an increasing effort is being put in the development of early warning systems (EWS, namely, approaches facing catastrophic phenomena by timely forecasting and alarm spreading throughout exposed population. Research efforts aimed at the development and implementation of effective EWS should especially concern the definition and calibration of the interpretative model. This paper analyses the main features characterizing predictive models working in EWS by discussing their aims and their features in terms of model accuracy, evolutionary stage of the phenomenon at which the prediction is carried out and model architecture. Original classification criteria based on these features are developed throughout the paper and shown in their practical implementation through examples of flow-like landslides and earth flows, both of which are characterized by rapid evolution and quite representative of many applications of EWS.

  3. Basic features of the predictive tools of early warning systems for water-related natural hazards: examples for shallow landslides

    Science.gov (United States)

    Greco, Roberto; Pagano, Luca

    2017-12-01

    To manage natural risks, an increasing effort is being put in the development of early warning systems (EWS), namely, approaches facing catastrophic phenomena by timely forecasting and alarm spreading throughout exposed population. Research efforts aimed at the development and implementation of effective EWS should especially concern the definition and calibration of the interpretative model. This paper analyses the main features characterizing predictive models working in EWS by discussing their aims and their features in terms of model accuracy, evolutionary stage of the phenomenon at which the prediction is carried out and model architecture. Original classification criteria based on these features are developed throughout the paper and shown in their practical implementation through examples of flow-like landslides and earth flows, both of which are characterized by rapid evolution and quite representative of many applications of EWS.

  4. Mining and urban impacts on semi-arid freshwater aquatic systems: the example of Mount Isa, Queensland.

    Science.gov (United States)

    Taylor, Mark P; Mackay, Alana; Kuypers, Tabitha; Hudson-Edwards, Karen

    2009-05-01

    This paper examines the environmental risk and impact of trace metals affecting river water and sediment in and around Mount Isa, Queensland, Australia. Bacterial indicator densities are also analysed throughout the catchment to assess the impacts and the potential hazards arising from agricultural activities, sewage treatment plant releases and urban runoff. The area is drained by the ephemeral Leichhardt River, which bisects Mount Isa City and the major Pb, Zn, Cu and Ag Mount Isa Mine. Runoff is captured downstream in Lake Moondarra, with the water being used following natural filtration via a lagoon-reed bed system for potable purposes by the residents of Mount Isa City. During the dry season, the channel is characterised by numerous pools that act as storage zones for sediment and water-soluble metals as well as urban and agriculturally derived nutrients and pathogens. Our results show that sediment and water quality within the Leichhardt River adjacent to and downstream of the mine frequently exceed Australian government sediment guidelines with average values of Cu, Pb and Zn found adjacent to the footprint of the mine being 1550, 510 and 470 mg kg(-1), respectively. Dry season analysis of water-soluble Cu, Pb and Zn concentrations within pools showed that Australian government low trigger guidelines are exceeded in 100, 46 and 100% cases, respectively. The densities of bacterial indicators in remnant pools throughout the Leichhardt River also exceeded acceptable guidelines. Maximum dry season faecal coliform densities of 2000 colony forming units (CFU) per 100 mL and Enterococcus counts of 900 organisms per 100 mL were recorded in dry season remnant pools compared to wet season maximum faecal coliform and Enterococcus densities of 119 000 CFU per 100 mL and 95 000 organisms per 100 mL, respectively. The impacts on biota were also examined by assessing the metal content of the tissue of seven fish from Lake Moondarra for their Cd, Cu, Hg, Pb and Zn

  5. Shallow Groundwater Temperatures and the Urban Heat Island Effect: the First U.K City-wide Geothermal Map to Support Development of Ground Source Heating Systems Strategy

    Science.gov (United States)

    Patton, Ashley M.; Farr, Gareth J.; Boon, David P.; James, David R.; Williams, Bernard; Newell, Andrew J.

    2015-04-01

    The first UK city-wide heat map is described based on measurements of groundwater from a shallow superficial aquifer in the coastal city of Cardiff, Wales, UK. The UK Government has a target of reducing greenhouse gas emissions by 80% by 2050 (Climate Change Act 2008) and low carbon technologies are key to achieving this. To support the use of ground source heating we characterised the shallow heat potential of an urban aquifer to produce a baseline dataset which is intended to be used as a tool to inform developers and to underpin planning and regulation. We exploited an existing network of 168 groundwater monitoring boreholes across the city, recording the water temperature in each borehole at 1m depth intervals up to a depth of 20m. We recorded groundwater temperatures during the coldest part of 2014, and repeat profiling of the boreholes in different seasons has added a fourth dimension to our results and allowed us to characterise the maximum depth of seasonal temperature fluctuation. The temperature profiles were used to create a 3D model of heat potential within the aquifer using GOCAD® and the average borehole temperatures were contoured using Surfer® 10 to generate a 2D thermal resource map to support future assessment of urban Ground Source Heat Pumps prospectively. The average groundwater temperature in Cardiff was found to be above the average for England and Wales (11.3°C) with 90% of boreholes in excess of this figure by up to 4°C. The subsurface temperature profiles were also found to be higher than forecast by the predicted geothermal gradient for the area. Potential sources for heat include: conduction from buildings, basements and sub-surface infrastructure; insulation effects of the urban area and of the geology, and convection from leaking sewers. Other factors include recharge inhibition by drains, localised confinement and rock-water interaction in specific geology. It is likely to be a combination of multiple factors which we are hoping

  6. Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

    International Nuclear Information System (INIS)

    Sugimoto, Norihiko

    2015-01-01

    Inertia-gravity wave radiation from the merging of two co-rotating vortices is investigated numerically in a rotating shallow water system in order to focus on cyclone–anticyclone asymmetry at different values of the Rossby number (Ro). A numerical study is conducted on a model using a spectral method in an unbounded domain to estimate the gravity wave flux with high accuracy. Continuous gravity wave radiation is observed in three stages of vortical flows: co-rotating of the vortices, merging of the vortices, and unsteady motion of the merged vortex. A cyclone–anticyclone asymmetry appears at all stages at smaller Ro (≤20). Gravity waves from anticyclones are always larger than those from cyclones and have a local maximum at smaller Ro (∼2) compared with that for an idealized case of a co-rotating vortex pair with a constant rotation rate. The source originating in the Coriolis acceleration has a key role in cyclone–anticyclone asymmetry in gravity waves. An additional important factor is that at later stages, the merged axisymmetric anticyclone rotates faster than the elliptical cyclone due to the effect of the Rossby deformation radius, since a rotation rate higher than the inertial cutoff frequency is required to radiate gravity waves

  7. Shallow methane hydrate system controls ongoing, downslope sediment transport in a low-velocity active submarine landslide complex, Hikurangi Margin, New Zealand

    Science.gov (United States)

    Mountjoy, Joshu J.; Pecher, Ingo; Henrys, Stuart; Crutchley, Gareth; Barnes, Philip M.; Plaza-Faverola, Andreia

    2014-11-01

    Morphological and seismic data from a submarine landslide complex east of New Zealand indicate flow-like deformation within gas hydrate-bearing sediment. This "creeping" deformation occurs immediately downslope of where the base of gas hydrate stability reaches the seafloor, suggesting involvement of gas hydrates. We present evidence that, contrary to conventional views, gas hydrates can directly destabilize the seafloor. Three mechanisms could explain how the shallow gas hydrate system could control these landslides. (1) Gas hydrate dissociation could result in excess pore pressure within the upper reaches of the landslide. (2) Overpressure below low-permeability gas hydrate-bearing sediments could cause hydrofracturing in the gas hydrate zone valving excess pore pressure into the landslide body. (3) Gas hydrate-bearing sediment could exhibit time-dependent plastic deformation enabling glacial-style deformation. We favor the final hypothesis that the landslides are actually creeping seafloor glaciers. The viability of rheologically controlled deformation of a hydrate sediment mix is supported by recent laboratory observations of time-dependent deformation behavior of gas hydrate-bearing sands. The controlling hydrate is likely to be strongly dependent on formation controls and intersediment hydrate morphology. Our results constitute a paradigm shift for evaluating the effect of gas hydrates on seafloor strength which, given the widespread occurrence of gas hydrates in the submarine environment, may require a reevaluation of slope stability following future climate-forced variation in bottom-water temperature.

  8. Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, Norihiko, E-mail: nori@phys-h.keio.ac.jp [Department of Physics, Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kouhoku-ku, Yokohama, Kanagawa 223-8521 (Japan)

    2015-12-15

    Inertia-gravity wave radiation from the merging of two co-rotating vortices is investigated numerically in a rotating shallow water system in order to focus on cyclone–anticyclone asymmetry at different values of the Rossby number (Ro). A numerical study is conducted on a model using a spectral method in an unbounded domain to estimate the gravity wave flux with high accuracy. Continuous gravity wave radiation is observed in three stages of vortical flows: co-rotating of the vortices, merging of the vortices, and unsteady motion of the merged vortex. A cyclone–anticyclone asymmetry appears at all stages at smaller Ro (≤20). Gravity waves from anticyclones are always larger than those from cyclones and have a local maximum at smaller Ro (∼2) compared with that for an idealized case of a co-rotating vortex pair with a constant rotation rate. The source originating in the Coriolis acceleration has a key role in cyclone–anticyclone asymmetry in gravity waves. An additional important factor is that at later stages, the merged axisymmetric anticyclone rotates faster than the elliptical cyclone due to the effect of the Rossby deformation radius, since a rotation rate higher than the inertial cutoff frequency is required to radiate gravity waves.

  9. Biological and physical modification of carbonate system parameters along the salinity gradient in shallow hypersaline solar salterns in Trapani, Italy

    Science.gov (United States)

    Isaji, Yuta; Kawahata, Hodaka; Kuroda, Junichiro; Yoshimura, Toshihiro; Ogawa, Nanako O.; Suzuki, Atsushi; Shibuya, Takazo; Jiménez-Espejo, Francisco J.; Lugli, Stefano; Santulli, Andrea; Manzi, Vinicio; Roveri, Marco; Ohkouchi, Naohiko

    2017-07-01

    We investigated changes in the chemical characteristics of evaporating seawater under the influence of microbial activity by conducting geochemical analyses of the brines and evaporite sediments collected from solar salterns in Trapani, Italy. The microbial activity had a substantial effect on the carbonate system parameters. Dissolved inorganic carbon (DIC) was substantially removed from the brine during the course of evaporation from the seawater to the point where calcium carbonate precipitates, with an accompanying decrease in its carbon isotopic composition (δ13CDIC) to as low as -10.6‰. Although the removal of DIC was due to calcium carbonate precipitation, photosynthesis, and the degassing of CO2(aq) induced by evaporation, the presence of 13C-depleted δ13CDIC in ponds where calcium carbonate precipitates can be attributed to the dissolution of atmospheric CO2 because of intensive CO2(aq) uptake by photosynthesis, and/or mineralization of organic matter by sulfate reduction. In contrast, δ13CDIC increased up to 7.2‰ in the salinity range where halite precipitates, which can be ascribed to the domination of the effect of degassing of CO2(aq) under conditions with reduced microbial activity. A gradual decrease in microbial activity was also reflected in compound-specific δ13C of photosynthetic pigments; isotopic fractionation associated with DIC assimilation increased linearly as the evaporation proceeded, indicating DIC-limited conditions within the microbial mats and gypsum crusts because of restricted DIC diffusion from the overlying brine and/or suppression of primary production at higher salinity.

  10. An integrated architecture for shallow and deep processing

    OpenAIRE

    Crysmann, Berthold; Frank, Anette; Kiefer, Bernd; Müller, Stefan; Neumann, Günter; Piskorski, Jakub; Schäfer, Ulrich; Siegel, Melanie; Uszkoreit, Hans; Xu, Feiyu; Becker, Markus; Krieger, Hans-Ulrich

    2011-01-01

    We present an architecture for the integration of shallow and deep NLP components which is aimed at flexible combination of different language technologies for a range of practical current and future applications. In particular, we describe the integration of a high-level HPSG parsing system with different high-performance shallow components, ranging from named entity recognition to chunk parsing and shallow clause recognition. The NLP components enrich a representation of natural language te...

  11. Remote sensing of macrophyte morphological traits: Implications for the management of shallow lakes

    Directory of Open Access Journals (Sweden)

    Paolo Villa

    2017-03-01

    Full Text Available Macrophytes are important elements of freshwater ecosystems, fulfilling a pivotal role in biogeochemical cycles. The synoptic capabilities provided by remote sensing make it a powerful tool for monitoring aquatic vegetation characteristics and the functional status of shallow lake systems in which they occur. The latest generation of airborne and spaceborne imaging sensors can be effectively exploited for mapping morphologically – and physiologically – relevant vegetation features based on their canopy spectral response. The objectives of this study were to calibrate semi-empirical models for mapping macrophyte morphological traits (i.e., fractional cover, leaf area index and above-water biomass from hyperspectral data, and to investigate the capabilities of remote sensing in supporting macrophyte monitoring and management. We calibrated spectral models using in situ reflectance and morphological trait measures and applied them to airborne hyperspectral imaging data, acquired over two shallow European water bodies (Lake Hídvégi, in Hungary, and Mantua lakes system, in Italy in two key phenological phases. Maps of morphological traits were produced covering a broad range of aquatic plant types (submerged, floating, and emergent, common to temperate and continental regions, with an error level of 5.4% for fractional cover, 0.10 m2 m-2 for leaf area index, and 0.06 kg m-2 for above-water biomass. Based on these maps, we discuss how remote sensing could support monitoring strategies and shallow lake management with reference to our two case studies: i.e., by providing insight into spatial and species-wise variability, by assessing nutrient uptake by aquatic plants, and by identifying hotspot areas where invasive species could become a threat to ecosystem functioning and service provision.

  12. Shallow Water Acoustics Studies

    Science.gov (United States)

    2017-11-19

    LE O CEAN RAPHIC I TITUTI Appli d Oc:ean Physics and E11gi1i,ering Depar1111,11t vember 9, 2017 Dr. Robert Headrick ffice of Naval Resear h, ode...UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT Applied Ocean Physics and Engineering Department...2015). [3] J.F. Lynch and A.E. Newhall, "Shallow water acoustics", book chapter in "Practical Underwater Acoustics," L. Bjorno, T. Neighbors, and D

  13. Geochemical and isotopic determination of deep groundwater contributions and salinity to the shallow groundwater and surface water systems, Mesilla Basin, New Mexico, Texas, and Mexico

    Science.gov (United States)

    Robertson, A.; Carroll, K. C.; Kubicki, C.; Purtshert, R.

    2017-12-01

    The Mesilla Basin/Conejos-Médanos aquifer system, extending from southern New Mexico to Chihuahua, Mexico, is a priority transboundary aquifer under the 2006 United States­-Mexico Transboundary Aquifer Assessment Act. Declining water levels, deteriorating water quality, and increasing groundwater use by municipal, industrial, and agricultural users on both sides of the international border raise concerns about long-term aquifer sustainability. Relative contributions of present-day and "paleo" recharge to sustainable fresh groundwater yields has not been determined and evidence suggests that a large source of salinity at the distal end of the Mesilla Basin is saline discharge from deep groundwater flow. The magnitude and distribution of those deep saline flow paths are not determined. The contribution of deep groundwater to discharge and salinity in the shallow groundwater and surface water of the Mesilla Basin will be determined by collecting discrete groundwater samples and analyzing for aqueous geochemical and isotopic tracers, as well as the radioisotopes of argon and krypton. Analytes include major ions, trace elements, the stable isotopes of water, strontium and boron isotopes, uranium isotopes, the carbon isotopes of dissolved inorganic carbon, noble gas concentrations and helium isotope ratios. Dissolved gases are extracted and captured from groundwater wells using membrane contactors in a process known as ultra-trace sampling. Gas samples are analyzed for radioisotope ratios of krypton by the ATTA method and argon by low-level counting. Effectiveness of the ultra-trace sampling device and method was evaluated by comparing results of tritium concentrations to the krypton-85 content. Good agreement between the analyses, especially in samples with undetectable tritium, indicates that the ultra-trace procedure is effective and confirms that introduction of atmospheric air has not occurred. The geochemistry data indicate a complex system of geochemical

  14. Development and application of an innovative expert decision support system to manage sediments and to assess environmental risk in freshwater ecosystems.

    Science.gov (United States)

    Dagnino, Alessandro; Bo, Tiziano; Copetta, Andrea; Fenoglio, Stefano; Oliveri, Caterina; Bencivenga, Mauro; Felli, Angelo; Viarengo, Aldo

    2013-10-01

    With the aim of supporting decision makers to manage contamination in freshwater environments, an innovative expert decision support system (EDSS) was developed. The EDSS was applied in a sediment quality assessment along the Bormida river (NW, Italy) which has been heavily contaminated by an upstream industrial site for more than a century. Sampling sites were classified by means of comparing chemical concentrations with effect-based target values (threshold and probable effect concentrations). The level of each contaminant and the combined toxic pressure were used to rank sites into three categories: (i) uncontaminated (8 sites), (ii) mildly contaminated (4) and (iii) heavily contaminated (19). In heavily contaminated sediments, an environmental risk index (EnvRI) was determined by means of integrating chemical data with ecotoxicological and ecological parameters (triad approach). In addition a sediment risk index (SedRI) was computed from combining chemical and ecotoxicological data. Eight sites exhibited EnvRI values ≥0.25, the safety threshold level (range of EnvRI values: 0.14-0.31) whereas SedRI exceeded the safety threshold level at 6 sites (range of SedRI values: 0.16-0.36). At sites classified as mildly contaminated, sublethal biomarkers were integrated with chemical data into a biological vulnerability index (BVI), which exceeded the safety threshold level at one site (BVI value: 0.28). Finally, potential human risk was assessed in selected stations (11 sites) by integrating genotoxicity biomarkers (GTI index falling in the range 0.00-0.53). General conclusions drawn from the EDSS data include: (i) in sites classified as heavily contaminated, only a few exhibited some significant, yet limited, effects on biodiversity; (ii) restrictions in re-using sediments from heavily contaminated sites found little support in ecotoxicological data; (iii) in the majority of the sites classified as mildly contaminated, tested organisms exhibited low response levels

  15. Highly tunable NEMS shallow arches

    KAUST Repository

    Kazmi, Syed N. R.

    2017-11-30

    We report highly tunable nanoelectromechanical systems NEMS shallow arches under dc excitation voltages. Silicon based in-plane doubly clamped bridges, slightly curved as shallow arches, are fabricated using standard electron beam lithography and surface nanomachining of a highly conductive device layer on a silicon-on-insulator wafer. By designing the structures to have gap to thickness ratio of more than four, the mid-plane stretching of the nano arches is maximized such that an increase in the dc bias voltage will result into continuous increase in the resonance frequency of the resonators to wide ranges. This is confirmed analytically based on a nonlinear beam model. The experimental results are found to be in good agreement with that of the results from developed analytical model. A maximum tunability of 108.14% for a 180 nm thick arch with an initially designed gap of 1 μm between the beam and the driving/sensing electrodes is achieved. Furthermore, a tunable narrow bandpass filter is demonstrated, which opens up opportunities for designing such structures as filtering elements in high frequency ranges.

  16. Supercritical-flow structures (backset-bedded sets and sediment waves) on high-gradient clinoform systems influenced by shallow-marine hydrodynamics

    Science.gov (United States)

    Massari, F.

    2017-10-01

    Inferred supercritical structures and bedforms, including sediment waves and backset-bedded sets, are identified as components of coarse-grained siliciclastic and bioclastic, high-gradient clinoform wedges (Plio-Pleistocene of southern Italy) and canyon head infills (Tortonian of Venetian pre-Alps), showing evidence of having been built out in a setting influenced by shallow-marine hydrodynamics. The facies identified are dominated by a range of traction carpets, formed after segregation of coarser particles in the lower part of bipartite density underflows. The generation of backset-bedded sets is thought to imply scouring due to impact of a submerged hydraulic jump on the bed, and upstream migration of the jump, concomitant with the deposition of backset beds on the stoss side of the developing bedform. Submerged hydraulic jumps apparently formed spontaneously and in any position on the foreset and toeset, without requiring any precursor bed defect. The mostly solitary, non-cyclical character of the bedforms prevents their attribution to cyclic steps. The sets of backset beds are locally underlain by chaotic infills of deep, steep-sided scours attributed to vigorous erosion at the hydraulic jump, accompanied by instantaneous loss in transport capacity which results in rapid plugging of the scour (hydraulic jump facies of Postma et al., 2014). Gravel waves have a distinct internal stratigraphy, and their length to amplitude ratios show lower mean values and higher variability when compared to sediment waves consisting of sand. The presence of supercritical bedforms on steep foreset slopes of the studied clinoform systems, even in proximity to the topset-foreset rollover, is believed to reflect high inefficiency of mud-poor and short run-out bipartite underflows episodically transporting relatively small volumes of coarse-grained sediment. This may also account for common solitary, non-cyclical bedforms. It is proposed that during intense oceanographic events, such

  17. 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...

  18. 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.

  19. Potential Risks of Freshwater Aquifer Contamination with Geosequestration

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Robert

    2013-09-30

    Substantial leakage of CO{sub 2} from deep geological strata to shallow potable aquifers is likely to be rare, but chemical detection of potential leakage nonetheless remains an integral component of any safe carbon capture and storage system. CO{sub 2} that infiltrates an unconfined freshwater aquifer will have an immediate impact on water chemistry by lowering pH in most cases and by altering the concentration of total dissolved solids. Chemical signatures in affected waters provide an important opportunity for early detection of leaks. In the presence of CO{sub 2}, trace elements such as Mn, Fe, and Ca can increase by an order of magnitude or more above control concentrations within 100 days. Therefore, these and other elements should be monitored along with pH as geochemical markers of potential CO{sub 2} leaks. Dissolved inorganic carbon and alkalinity can also be rapidly responsive to CO{sub 2} and are stable indicators of a leak. Importantly, such changes may be detectable long before direct changes in CO{sub 2} are observed. The experimental results also suggest that the relative severity of the impact of leaks on overlying drinking-water aquifers should be considered in the selection of CO{sub 2} sequestration sites. One primary selection criteria should be metal and metalloid availability, such as uranium and arsenic abundance, to carefully monitor chemical species that could trigger changes above maximum contaminant levels (MCLs). Overall, the risks of leakage from underground CO{sub 2} storage are real but appear to be manageable if systems are closely monitored.

  20. 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.

  1. Chemical characteristics of surface systems in the Simpevarp area. Visualisation and statistical evaluation of data from surface water, precipitation, shallow groundwater, and regolith

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-01-15

    The Swedish Nuclear Fuel and Waste management Co (SKB) initiated site investigations for a deep repository for spent nuclear fuel at two different sites in Sweden, Forsmark and Oskarshamn, in 2002. This report evaluates the results from chemical investigations of the surface system in the Simpevarp area in Oskarshamn, i.e. both the Laxemar subarea and the Simpevarp subarea, during the period Nov 2002 - Mar 2005. The evaluation includes data from surface waters (lakes, streams and the sea), precipitation, shallow groundwater and regolith (till, soil, peat, sediments and biota) in the area. The main focus of the study is to visualize the vast amount of data collected hitherto in the site investigations, and to give a chemical characterisation of the investigated media at the site. The results will be used to support the site descriptive models, which in turn are used for safety assessment studies and for the environmental impact assessment. The data used consist of water chemical composition in lakes, streams and coastal sites, and in precipitation, predominantly sampled on a monthly basis, and in groundwater from soil tubes and wells. Moreover, regolith data includes information on the chemical composition of till, soil, sediment and vegetation samples from the area. The characterisations include all measured chemical parameters, i.e. major and minor constituents, trace elements, nutrients, isotopes and radio nuclides, as well as field measured parameters. The evaluation of data from each medium has been divided into the following parts: Characterisation of individual sampling sites, and comparisons within and among sampling sites as well as comparisons with local, regional and national reference data. Analysis of time trends and seasonal variation (for surface waters). Exploration of relationships among the various chemical parameters. For all investigated parameters, the report presents selected statistics for each sampling site, as well as for available reference

  2. Chemical characteristics of surface systems in the Simpevarp area. Visualisation and statistical evaluation of data from surface water, precipitation, shallow groundwater, and regolith

    International Nuclear Information System (INIS)

    Troejbom, Mats; Soederbaeck, Bjoern

    2006-01-01

    The Swedish Nuclear Fuel and Waste management Co (SKB) initiated site investigations for a deep repository for spent nuclear fuel at two different sites in Sweden, Forsmark and Oskarshamn, in 2002. This report evaluates the results from chemical investigations of the surface system in the Simpevarp area in Oskarshamn, i.e. both the Laxemar subarea and the Simpevarp subarea, during the period Nov 2002 - Mar 2005. The evaluation includes data from surface waters (lakes, streams and the sea), precipitation, shallow groundwater and regolith (till, soil, peat, sediments and biota) in the area. The main focus of the study is to visualize the vast amount of data collected hitherto in the site investigations, and to give a chemical characterisation of the investigated media at the site. The results will be used to support the site descriptive models, which in turn are used for safety assessment studies and for the environmental impact assessment. The data used consist of water chemical composition in lakes, streams and coastal sites, and in precipitation, predominantly sampled on a monthly basis, and in groundwater from soil tubes and wells. Moreover, regolith data includes information on the chemical composition of till, soil, sediment and vegetation samples from the area. The characterisations include all measured chemical parameters, i.e. major and minor constituents, trace elements, nutrients, isotopes and radio nuclides, as well as field measured parameters. The evaluation of data from each medium has been divided into the following parts: Characterisation of individual sampling sites, and comparisons within and among sampling sites as well as comparisons with local, regional and national reference data. Analysis of time trends and seasonal variation (for surface waters). Exploration of relationships among the various chemical parameters. For all investigated parameters, the report presents selected statistics for each sampling site, as well as for available reference

  3. Shallow ground disposal - calculation of dose

    International Nuclear Information System (INIS)

    1987-02-01

    The ability of an existing shallow land burial systems model to meet AECB user requirements has been evaluated. The deficiencies of the program are identified and activities necessary to modify the code to fulfill the user requirements are outlined. Implementation plans for a number of likely scenarios have been constructed and possible cost-cutting measures have been recommended

  4. What is the impact on fish recruitment of anthropogenic physical and structural habitat change in shallow nearshore areas in temperate systems? : A systematic review protocol

    NARCIS (Netherlands)

    Macura, Biljana; Lönnstedt, Oona; Byström, Pär; Airoldi, Laura; Eriksson, Britas; Rudstam, Lars; Støttrup, Josianne

    2016-01-01

    Shallow nearshore marine ecosystems are changing at an increasing rate due to a range of human activities such as urbanisation and commercial development. The growing numbers of constructions and other physical and structural alterations of the shoreline often take place in nursery and spawning

  5. Limitations of shallow nets approximation.

    Science.gov (United States)

    Lin, Shao-Bo

    2017-10-01

    In this paper, we aim at analyzing the approximation abilities of shallow networks in reproducing kernel Hilbert spaces (RKHSs). We prove that there is a probability measure such that the achievable lower bound for approximating by shallow nets can be realized for all functions in balls of reproducing kernel Hilbert space with high probability, which is different with the classical minimax approximation error estimates. This result together with the existing approximation results for deep nets shows the limitations for shallow nets and provides a theoretical explanation on why deep nets perform better than shallow nets. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. New Jersey shallow shelf

    DEFF Research Database (Denmark)

    Expedition 313 Scientists; Bjerrum, Christian J.

    2009-01-01

    to key horizons in wells drilled into the adjacent coastal plain suggest the clinoform structures investigated during Expedition 313 were deposited during times of oscillations in global sea level; however, this needs to be determined with much greater certainty. The age, lithofacies, and core-log......Integrated Ocean Drilling Program (IODP) Expedition 313 to the New Jersey Shallow Shelf off the east coast of the United States is the third IODP expedition to use a mission-specific platform. It was conducted by the European Consortium for Ocean Research Drilling (ECORD) Science Operator (ESO......) between 30 April and 17 July 2009, with additional support from the International Continental Scientific Drilling Program (ICDP). There were three objectives: (1) date late Paleogene–Neogene depositional sequences and compare ages of unconformable surfaces that divide these sequences with times of sea...

  7. 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

  8. Restricted-range fishes and the conservation of Brazilian freshwaters.

    Science.gov (United States)

    Nogueira, Cristiano; Buckup, Paulo A; Menezes, Naercio A; Oyakawa, Osvaldo T; Kasecker, Thais P; Ramos Neto, Mario B; da Silva, José Maria C

    2010-06-30

    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. 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. 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 drainage systems. Proper management (e. g. forestry code enforcement, landscape

  9. 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.

  10. Stormwater runoff drives viral community composition changes in inland freshwaters

    Science.gov (United States)

    Williamson, Kurt E.; Harris, Jamie V.; Green, Jasmin C.; Rahman, Faraz; Chambers, Randolph M.

    2014-01-01

    Storm events impact freshwater microbial communities by transporting terrestrial viruses and other microbes to freshwater systems, and by potentially resuspending microbes from bottom sediments. The magnitude of these impacts on freshwater ecosystems is unknown and largely unexplored. Field studies carried out at two discrete sites in coastal Virginia (USA) were used to characterize the viral load carried by runoff and to test the hypothesis that terrestrial viruses introduced through stormwater runoff change the composition of freshwater microbial communities. Field data gathered from an agricultural watershed indicated that primary runoff can contain viral densities approximating those of receiving waters. Furthermore, viruses attached to suspended colloids made up a large fraction of the total load, particularly in early stages of the storm. At a second field site (stormwater retention pond), RAPD-PCR profiling showed that the viral community of the pond changed dramatically over the course of two intense storms while relatively little change was observed over similar time scales in the absence of disturbance. Comparisons of planktonic and particle-associated viral communities revealed two completely distinct communities, suggesting that particle-associated viruses represent a potentially large and overlooked portion of aquatic viral abundance and diversity. Our findings show that stormwater runoff can quickly change the composition of freshwater microbial communities. Based on these findings, increased storms in the coastal mid-Atlantic region predicted by most climate change models will likely have important impacts on the structure and function of local freshwater microbial communities. PMID:24672520

  11. 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)

  12. 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

  13. Fundamentals of Shallow Water Acoustics

    CERN Document Server

    Katsnelson, Boris; Lynch, James

    2012-01-01

    Shallow water acoustics (SWA), the study of how low and medium frequency sound propagates and scatters on the continental shelves of the world's oceans, has both technical interest and a large number of practical applications. Technically, shallow water poses an interesting medium for the study of acoustic scattering, inverse theory, and propagation physics in a complicated oceanic waveguide. Practically, shallow water acoustics has interest for geophysical exploration, marine mammal studies, and naval applications. Additionally, one notes the very interdisciplinary nature of shallow water acoustics, including acoustical physics, physical oceanography, marine geology, and marine biology. In this specialized volume, the authors, all of whom have extensive at-sea experience in U.S. and Russian research efforts, have tried to summarize the main experimental, theoretical, and computational results in shallow water acoustics, with an emphasis on providing physical insight into the topics presented.

  14. New Zealand Freshwater Management: Changing Policy for a Changing World

    Science.gov (United States)

    Rouse, H. L.; Norton, N.

    2014-12-01

    Fresh water is essential to New Zealand's economic, environmental, cultural and social well-being. In line with global trends, New Zealand's freshwater resources are under pressure from increased abstraction and changes in land-use which contribute contaminants to our freshwater systems. Recent central government policy reform introduces greater national direction and guidance, to bring about a step-change in freshwater management. An existing national policy for freshwater management introduced in 2011 requires regional authorities to produce freshwater management plans containing clear freshwater objectives (measurable statements about the desired environmental state for water bodies) and associated limits to resource use (such as environmental flows and quantity allocation limits, and loads of contaminants to be discharged). These plans must integrate water quantity and quality management, consider climate change, and incorporate tangata whenua (New Zealand māori) roles and interests. In recent (2014) national policy amendments, the regional authorities are also required to implement national 'bottom-line' standards for certain attributes of the system to be managed; undertake accounting for all water takes and all sources of contaminants; and to develop and implement their plans in a collaborative way with communities. This rapid change in national policy has necessitated a new way of working for authorities tasked with implementation; many obstacles lie in their path. The scientific methods required to help set water quantity limits are well established, but water quality methods are less so. Collaborative processes have well documented benefits but also raise many challenges, particularly for the communication of complex and often uncertain scientific information. This paper provides background on the national policy changes and offers some early lessons learned by the regional authorities implementing collaborative freshwater management in New Zealand.

  15. Seasonality of major redox constituents in a shallow subterranean estuary

    Science.gov (United States)

    O'Connor, Alison E.; Krask, Julie L.; Canuel, Elizabeth A.; Beck, Aaron J.

    2018-03-01

    The subterranean estuary (STE), the subsurface mixing zone of outflowing fresh groundwater and infiltrating seawater, is an area of extensive geochemical reactions that determine the composition of groundwater that flows into coastal environments. This study examined the porewater composition of a shallow STE (redox gradients on STE geochemistry. Two freshwater endmembers were identified, between which redox potential and composition varied with depth-a shallow freshwater endmember was oxidizing and high in DOC, whereas a deep freshwater endmember was reducing, lower in DOC, and high in sulfide. Results showed that dissolved Fe, Mn, and sulfide varied along a redox gradient distinct from the salinity gradient, and that three-endmember mixing was required to quantify non-conservative chemical addition/removal in the STE. In addition to salinity, humic carbon was used as a quasi-conservative tracer to quantify mixing according to a three-endmember model. The vertical distributions of DOC and reduced metabolites remained approximately constant over time, but concentrations varied with season. Dissolved organic carbon concentrations were greatest in the summer, and shallow meteoric groundwater supplied the majority of DOC to the STE. In summer, there was additional evidence for shallow non-conservative addition of DOC. Dissolved Fe and Mn were highest in a subsurface plume through the middle of the STE (100-140 cm below sediment surface at the high tide line) which was characterized by higher concentrations and greater non-conservative addition in the winter. In contrast, sulfide was higher in summer at depths within the Fe and Mn plume (100-140 cm). We attribute the contrasting seasonal patterns of dissolved Fe, Mn, and sulfide to differences in microbial response to temperature changes and organic matter availability, and to competition at the ferrous-sulfidic transition zone between dissimilatory metal reduction and sulfate reduction, leading to sulfate

  16. Risks for the global freshwater system at 1.5 °C and 2 °C global warming

    Science.gov (United States)

    Döll, Petra; Trautmann, Tim; Gerten, Dieter; Müller Schmied, Hannes; Ostberg, Sebastian; Saaed, Fahad; Schleussner, Carl-Friedrich

    2018-04-01

    To support implementation of the Paris Agreement, the new HAPPI ensemble of 20 bias-corrected simulations of four climate models was used to drive two global hydrological models, WaterGAP and LPJmL, for assessing freshwater-related hazards and risks in worlds approximately 1.5 °C and 2 °C warmer than pre-industrial. Quasi-stationary HAPPI simulations are better suited than transient CMIP-like simulations for assessing hazards at the two targeted long-term global warming (GW) levels. We analyzed seven hydrological hazard indicators that characterize freshwater-related hazards for humans, freshwater biota and vegetation. Using a strict definition for significant differences, we identified for all but one indicator that areas with either significantly wetter or drier conditions (calculated as percent changes from 2006–2015) are smaller in the 1.5 °C world. For example, 7 day high flow is projected to increase significantly on 11% and 21% of the global land area at 1.5 °C and 2 °C, respectively. However, differences between hydrological hazards at the two GW levels are significant on less than 12% of the area. GW affects a larger area and more people by increases—rather than by decreases—of mean annual and 1-in-10 dry year streamflow, 7 day high flow, and groundwater recharge. The opposite is true for 7 day low flow, maximum snow storage, and soil moisture in the driest month of the growing period. Mean annual streamflow shows the lowest projected percent changes of all indicators. Among country groups, low income countries and lower middle income countries are most affected by decreased low flows and increased high flows, respectively, while high income countries are least affected by such changes. The incremental impact between 1.5 °C and 2 °C on high flows would be felt most by low income and lower middle income countries, the effect on soil moisture and low flows most by high income countries.

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

    African Journals Online (AJOL)

    Review: Freshwater conservation planning in South Africa: Milestones to ... Water SA. Journal Home · ABOUT THIS JOURNAL · Advanced Search ... Since the 1970s, at approximately 10-year intervals, 4 national-scale freshwater conservation ...

  18. 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...

  19. Systems level insights into alternate methane cycling modes in a freshwater lake via community transcriptomics, metabolomics and nano-SIMS analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lidstrom, Mary E. [Univ. of Washington, Seattle, WA (United States); Chistoserdova, Ludmila [Univ. of Washington, Seattle, WA (United States); Kalyuzhnaya, Marina G. [Univ. of Washington, Seattle, WA (United States); Orphan, Victoria J. [California Inst. of Technology (CalTech), Pasadena, CA (United States); Beck, David A. [Univ. of Washington, Seattle, WA (United States)

    2014-08-07

    The research conducted as part of this project contributes significantly to the understanding of the microbes and their activities involved in methane metabolism in freshwater lake sediments and in the environment in a more global sense. Significant new insights have been gained into the identity of the species that are most active in methane oxidation. New concepts have been developed based on the new data on how these organisms metabolize methane, impacting not only environmental microbiology but also biotechnology, including biotechnology of next generation biofuels. Novel approaches have been developed for studying functional microbial communities, via holistic approaches, such as metagenomics, metatrancriptomics and metabolite analysis. As a result, a novel outlook has been obtained at how such communities operate in nature. Understanding methane-oxidizing communities in lakes and other environments is of significant benefit to the public, in terms of methane emission mitigation and in terms of potential biotechnological applications.

  20. From regionally predictable to locally complex population structure in a freshwater top predator: River systems are not always the unit of connectivity in Northern Pike Esox lucius

    DEFF Research Database (Denmark)

    Bekkevold, Dorte; Jacobsen, Lene; Hansen, Jakob Hemmer

    2015-01-01

    Contemporary genetic diversity is the product of both historical and contemporary forces, such as climatic and geological processes affecting range distribution and continuously moulded by evolutionary forces selection, gene flow and genetic drift. Predatory freshwater fishes, such as Northern Pike...... structure from local to regional scales is relatively poorly described, in spite of its significance to developing conservation measures. We analysed microsatellite variation in a total of 1185 North European pike from 46 samples collected across both local and regional scales, as well as over time......, to address two overarching questions: Is pike population structure associated with local and/or regional connectivity patterns, and which factors likely have the main influence on the contemporary distribution of genetic diversity? To answer this, we combined estimators of population diversity and structure...

  1. An exactly soluble model of a shallow double well

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz-Vega, R., E-mail: rodrigo.munoz@uacm.edu.mx [Universidad Autónoma de la Ciudad de México, Centro Histórico, Fray Servando Teresa de Mier 92, Col. Centro, Del. Cuauhtémoc, México DF, CP 06080 (Mexico); López-Chávez, E., E-mail: elopezc@hotmail.com [Universidad Autónoma de la Ciudad de México, Centro Histórico, Fray Servando Teresa de Mier 92, Col. Centro, Del. Cuauhtémoc, México DF, CP 06080 (Mexico); Salinas-Hernández, E., E-mail: esalinas@ipn.mx [ESCOM-IPN, Av Juan de Dios Bátiz s/n, Unidad Profesional Adolfo López Mateos, Col Lindavista, Del G A Madero, México DF, CP 07738 (Mexico); Flores-Godoy, J.-J., E-mail: job.flores@ibero.mx [Departamento de Física y Matemáticas, Universidad Iberoamericana, Prol. Paseo de la Reforma 880, Col Lomas de Santa Fe, Del A Obregón, México DF, CP 01219 (Mexico); Fernández-Anaya, G., E-mail: guillermo.fernandez@ibero.com [Departamento de Física y Matemáticas, Universidad Iberoamericana, Prol. Paseo de la Reforma 880, Col Lomas de Santa Fe, Del A Obregón, México DF, CP 01219 (Mexico)

    2014-06-13

    Shallow one-dimensional double-well potentials appear in atomic and molecular physics and other fields. Unlike the “deep” wells of macroscopic quantum coherent systems, shallow double wells need not present low-lying two-level systems. We argue that this feature, the absence of a low-lying two-level system in certain shallow double wells, may allow the finding of new test grounds for quantum mechanics in mesoscopic systems. We illustrate the above ideas with a family of shallow double wells obtained from reflectionless potentials through the Darboux–Bäcklund transform. - Highlights: • We present double wells not conforming to the low-lying two-state system model. • Models similar to ours appear in atomic and molecular physics. • Here there is no classically prohibited region between wells. • The ground probability is peaked at the position of classical unstable equilibrium in this models.

  2. Mechanical challenges to freshwater residency in sharks and rays.

    Science.gov (United States)

    Gleiss, Adrian C; Potvin, Jean; Keleher, James J; Whitty, Jeff M; Morgan, David L; Goldbogen, Jeremy A

    2015-04-01

    Major transitions between marine and freshwater habitats are relatively infrequent, primarily as a result of major physiological and ecological challenges. Few species of cartilaginous fish have evolved to occupy freshwater habitats. Current thought suggests that the metabolic physiology of sharks has remained a barrier to the diversification of this taxon in freshwater ecosystems. Here, we demonstrate that the physical properties of water provide an additional constraint for this species-rich group to occupy freshwater systems. Using hydromechanical modeling, we show that occurrence in fresh water results in a two- to three-fold increase in negative buoyancy for sharks and rays. This carries the energetic cost of lift production and results in increased buoyancy-dependent mechanical power requirements for swimming and increased optimal swim speeds. The primary source of buoyancy, the lipid-rich liver, offers only limited compensation for increased negative buoyancy as a result of decreasing water density; maintaining the same submerged weight would involve increasing the liver volume by very large amounts: 3- to 4-fold in scenarios where liver density is also reduced to currently observed minimal levels and 8-fold without any changes in liver density. The first data on body density from two species of elasmobranch occurring in freshwater (the bull shark Carcharhinus leucas, Müller and Henle 1839, and the largetooth sawfish Pristis pristis, Linnaeus 1758) support this hypothesis, showing similar liver sizes as marine forms but lower liver densities, but the greatest negative buoyancies of any elasmobranch studied to date. Our data suggest that the mechanical challenges associated with buoyancy control may have hampered the invasion of freshwater habitats in elasmobranchs, highlighting an additional key factor that may govern the predisposition of marine organisms to successfully establish in freshwater habitats. © 2015. Published by The Company of Biologists Ltd.

  3. Inhabitants of the Fresh-Water Community.

    Science.gov (United States)

    Jorgensen, Joseph; Schroeder, Marlene

    This learner's guide is designed to assist middle school students in studying freshwater organisms. Following a brief introduction to freshwater ecology, simple line drawings facilitate the identification of plants and animals common to Florida's freshwater ecosystems. Emphasis of the short text which accompanies each illustration is upon the…

  4. 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.

  5. Practical Soil-Shallow Foundation Model for Nonlinear Structural Analysis

    Directory of Open Access Journals (Sweden)

    Moussa Leblouba

    2016-01-01

    Full Text Available Soil-shallow foundation interaction models that are incorporated into most structural analysis programs generally lack accuracy and efficiency or neglect some aspects of foundation behavior. For instance, soil-shallow foundation systems have been observed to show both small and large loops under increasing amplitude load reversals. This paper presents a practical macroelement model for soil-shallow foundation system and its stability under simultaneous horizontal and vertical loads. The model comprises three spring elements: nonlinear horizontal, nonlinear rotational, and linear vertical springs. The proposed macroelement model was verified using experimental test results from large-scale model foundations subjected to small and large cyclic loading cases.

  6. The development of a GIS atlas of southern African freshwater fish ...

    African Journals Online (AJOL)

    The development of a GIS atlas of southern African freshwater fish. LEP Scott, PH Skelton, AJ Booth, L Verheust. Abstract. A geographic information systems (GIS) based atlas of southern African freshwater fish has been developed for the SADC countries. The JLB Smith Institute of Ichthyology, in collaboration with ALCOM, ...

  7. Exploration of shallow subsurface resistivity structure using a portable TEM system: TEM-FAST prosystem; Kan`igata TEM ho sochi TEM-FAST prosystem ni yoru senbu hiteiko chosa

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Y; Kumekawa, Y; Takasugi, S [GERD Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan)

    1997-05-27

    Discussions were given on effectiveness of the TEM-FAST ProSystem which is a portable TEM system developed recently for use in exploration of shallow subsurface resistivity. The system consists of a loop type antenna, the TEM-FAST as the main equipment, and a host computer, the host computer controlling the entire system. The system acquires transient response data in secondary induced magnetic fields lasting 4 {mu} sec to 1 m sec. The number of data is 5490 stacks in one measurement, and the data acquisition time is about three minutes. Measurements were carried out by using the TEM-FAST in the vicinity of a well, whose results were compared with those of electric logging, and discussions were given on them. Although the electric logging results had no data available for depths shallower than 35 m, the measurement results from the TEM-FAST were found highly harmonious with those of the electric logging. In addition, there were transmission and telephone lines in locations about 10 m away from the well during the measurement, but extremely high data quality was discovered. 6 refs., 7 figs., 1 tab.

  8. A Strategy to Conduct an Analysis of the Long-Term Performance of Low-Activity Waste Glass in a Shallow Subsurface Disposal System at Hanford

    Energy Technology Data Exchange (ETDEWEB)

    BP McGrail, WL Ebert, DH Bacon, DM Strachan

    1998-02-18

    Privatized services are being procured to vitrify low-activity tank wastes for eventual disposal in a shallow subsurface facility at the Hanford Site. Over 500,000 metric tons of low-activity waste glass will be generated, which is among the largest volumes of waste within the U.S. Department of Energy (DOE) complex and is one of the largest inventories of long-lived radionuclides planned for disposal in a low-level waste facility. Before immobilized waste can be disposed, DOE must approve a "performance assessment," which is a document that describes the impacts of the disposal facility on public health and environmental resources. Because the release rate of radionuclides from the glass waste form is a key factor determining these impacts, a sound scientific basis for determining their long-term release rates must be developed if this disposal action is to be accepted by regulatory agencies, stakeholders, and the public. In part, the scientific basis is determined from a sound testing strategy. The foundation of the proposed testing strategy is a well accepted mechanistic model that is being used to calculate the glass corrosion behavior over the geologic time scales required for performance assessment. This model requires that six parameters be determined, and the testing program is defined by an appropriate set of laboratory experiments to determine these parameters, and is combined with a set of field experiments to validate the model as a whole. Three general classes of laboratory tests are proposed in this strategy: 1) characterization, 2) accelerated, and 3) service condition. Characterization tests isolate and provide specific information about processes or parameters in theoretical models. Accelerated tests investigate corrosion behavior that will be important over the regulated service life of a disposal system within a laboratory time frame of a few years or less. Service condition tests verify that the techniques used in accelerated tests do not change

  9. The impacts of groundwater heat pumps on urban shallow ...

    African Journals Online (AJOL)

    DR TONUKARI NYEROVWO

    2011-07-25

    Jul 25, 2011 ... In order to assess the impacts of groundwater heat pumps on urban shallow groundwater ... thermal transfer systems that use the ground water as a ... Abbreviations: GWHPs, Groundwater heat pumps; GHGs, ... Areas (Mm2).

  10. Characterizing Groundwater Level and Flow Pattern in a Shallow ...

    African Journals Online (AJOL)

    Bheema

    This study characterize groundwater yield and flow pattern on a shallow ... simple process of weathering, fractured fissure systems, networks of joints and ..... lowest yield in wells that are deeper than the mean well depth in the study area.

  11. Shallow-Water Mud Acoustics

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Shallow-Water Mud Acoustics William L. Siegmann...models and methods that explain observed material and acoustic properties of different physical types of shallow-ocean mud sediments. Other goals...are to assess prior data relating to the acoustic properties of mud and to provide guidance in the development and interpretation of experiments. A

  12. Dynamics of a shallow fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Tsimring, Lev S. [Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093-0402 (United States); Ramaswamy, Ramakrishna [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067, (India); Sherman, Philip [Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093-0402 (United States)

    1999-12-01

    The results of the experimental study of the dynamics of a shallow fluidized bed are reported. The behavior of granular material is controlled by the interplay of two factors--levitation due to the upward airflow, and sliding back due to gravity. Near the threshold of instability, the system shows critical behavior with remarkably long transient dynamics. The experimental observations are compared with a simple cellular automata model. (c) 1999 The American Physical Society.

  13. A study of the effects of grid non-orthogonality on the solution of shallow water equations in boundary-fitted coordinate systems

    CERN Document Server

    Sankaranarayanan, S

    2003-01-01

    In the present study, an existing two-dimensional boundary-fitted model [J. Hydraul. Eng.-ASCE 122 (9) (1996) 512] is used to study the effect of grid non-orthogonality on the solution of shallow water equations using boundary-fitted grids. The linearized two-dimensional shallow water equations are expressed in terms of the grid angle and aspect ratio. The truncation errors of the finite difference approximations used in the solution of the governing equations are shown to be dependent on the grid angle and the aspect ratio. The coefficient of the truncation error was shown to increase, with the decrease in the grid angle. The RMS errors in model predicted surface elevations and velocities for the case of seiching in a rectangular basin are found to increase gradually, as the grid resolution decreases from 174 to 80 gridpoints per wavelength or as the grid angle decreases from 90 deg. to 50 deg. and increases rather sharply for a grid angle of 30 deg. at grid resolutions less than 80 gridpoints per wavelength...

  14. Assessing and managing freshwater ecosystems vulnerable to global change

    Science.gov (United States)

    Angeler, David G.; Allen, Craig R.; Birge, Hannah E.; Drakare, Stina; McKie, Brendan G.; Johnson, Richard K.

    2014-01-01

    Freshwater ecosystems are important for global biodiversity and provide essential ecosystem services. There is consensus in the scientific literature that freshwater ecosystems are vulnerable to the impacts of environmental change, which may trigger irreversible regime shifts upon which biodiversity and ecosystem services may be lost. There are profound uncertainties regarding the management and assessment of the vulnerability of freshwater ecosystems to environmental change. Quantitative approaches are needed to reduce this uncertainty. We describe available statistical and modeling approaches along with case studies that demonstrate how resilience theory can be applied to aid decision-making in natural resources management. We highlight especially how long-term monitoring efforts combined with ecological theory can provide a novel nexus between ecological impact assessment and management, and the quantification of systemic vulnerability and thus the resilience of ecosystems to environmental change.

  15. HF Radar Sea-echo from Shallow Water

    Directory of Open Access Journals (Sweden)

    Josh Kohut

    2008-08-01

    Full Text Available HF radar systems are widely and routinely used for the measurement of ocean surface currents and waves. Analysis methods presently in use are based on the assumption of infinite water depth, and may therefore be inadequate close to shore where the radar echo is strongest. In this paper, we treat the situation when the radar echo is returned from ocean waves that interact with the ocean floor. Simulations are described which demonstrate the effect of shallow water on radar sea-echo. These are used to investigate limits on the existing theory and to define water depths at which shallow-water effects become significant. The second-order spectral energy increases relative to the first-order as the water depth decreases, resulting in spectral saturation when the waveheight exceeds a limit defined by the radar transmit frequency. This effect is particularly marked for lower radar transmit frequencies. The saturation limit on waveheight is less for shallow water. Shallow water affects second-order spectra (which gives wave information far more than first-order (which gives information on current velocities, the latter being significantly affected only for the lowest radar transmit frequencies for extremely shallow water. We describe analysis of radar echo from shallow water measured by a Rutgers University HF radar system to give ocean wave spectral estimates. Radar-derived wave height, period and direction are compared with simultaneous shallow-water in-situ measurements.

  16. Guidance Index for Shallow Landslide Hazard Analysis

    Directory of Open Access Journals (Sweden)

    Cheila Avalon Cullen

    2016-10-01

    Full Text Available Rainfall-induced shallow landslides are one of the most frequent hazards on slanted terrains. Intense storms with high-intensity and long-duration rainfall have high potential to trigger rapidly moving soil masses due to changes in pore water pressure and seepage forces. Nevertheless, regardless of the intensity and/or duration of the rainfall, shallow landslides are influenced by antecedent soil moisture conditions. As of this day, no system exists that dynamically interrelates these two factors on large scales. This work introduces a Shallow Landslide Index (SLI as the first implementation of antecedent soil moisture conditions for the hazard analysis of shallow rainfall-induced landslides. The proposed mathematical algorithm is built using a logistic regression method that systematically learns from a comprehensive landslide inventory. Initially, root-soil moisture and rainfall measurements modeled from AMSR-E and TRMM respectively, are used as proxies to develop the index. The input dataset is randomly divided into training and verification sets using the Hold-Out method. Validation results indicate that the best-fit model predicts the highest number of cases correctly at 93.2% accuracy. Consecutively, as AMSR-E and TRMM stopped working in October 2011 and April 2015 respectively, root-soil moisture and rainfall measurements modeled by SMAP and GPM are used to develop models that calculate the SLI for 10, 7, and 3 days. The resulting models indicate a strong relationship (78.7%, 79.6%, and 76.8% respectively between the predictors and the predicted value. The results also highlight important remaining challenges such as adequate information for algorithm functionality and satellite based data reliability. Nevertheless, the experimental system can potentially be used as a dynamic indicator of the total amount of antecedent moisture and rainfall (for a given duration of time needed to trigger a shallow landslide in a susceptible area. It is

  17. Problems with the dating of sediment core using excess 210Pb in a freshwater system impacted by large scale watershed changes

    International Nuclear Information System (INIS)

    Baskaran, Mark; Nix, Joe; Kuyper, Clark; Karunakara, N.

    2014-01-01

    Pb-210 dating of freshwater and coastal sediments have been extensively conducted over the past 40 years for historical pollution reconstruction studies, sediment focusing, sediment accumulation and mixing rate determination. In areas where there is large scale disturbance of sediments and the watershed, the vertical profiles of excess 210 Pb ( 210 Pb xs ) could provide erroneous or less reliable information on sediment accumulation rates. We analyzed one sediment core from Hendrix Lake in southwestern Arkansas for excess 210 Pb and 137 Cs. There is no decrease in excess 210 Pb activity with depth while the 137 Cs profile indicates sharp peak corresponding to 1963 and the 137 Cs penetration depth of 137 Cs corresponds to 1952. The historical data on the accelerated mercury mining during 1931–1944 resulted in large-scale Hg input to this watershed. Using the peak Hg activity as a time marker, the obtained sediment accumulation rates agree well with the 137 Cs-based rates. Four independent evidences (two-marker events based on 137 Cs and two marker events based on Hg mining activity) result in about the same sedimentation rates and thus, we endorse earlier suggestion that 210 Pb profile always needs to be validated with at least one another independent method. We also present a concise discussion on what important factors that can affect the vertical profiles of 210 Pb xs in relatively smaller lakes

  18. Hydrochemical processes in a shallow coal seam gas aquifer and its overlying stream–alluvial system: implications for recharge and inter-aquifer connectivity

    International Nuclear Information System (INIS)

    Duvert, Clément; Raiber, Matthias; Owen, Daniel D.R.; Cendón, Dioni I.; Batiot-Guilhe, Christelle; Cox, Malcolm E.

    2015-01-01

    Highlights: • Major ions and isotopes used to study inter-aquifer mixing in a shallow CSG setting. • Considerable heterogeneity in the water composition of the coal-bearing aquifer. • Rapid recharge of the coal-bearing aquifer through highly fractured igneous rocks. • Potential mixing between the coal-bearing aquifer and downstream alluvial aquifer. • Need to consider the seasonal influences on inter-aquifer mixing in CSG settings. - Abstract: In areas of potential coal seam gas (CSG) development, understanding interactions between coal-bearing strata and adjacent aquifers and streams is of highest importance, particularly where CSG formations occur at shallow depth. This study tests a combination of hydrochemical and isotopic tracers to investigate the transient nature of hydrochemical processes, inter-aquifer mixing and recharge in a catchment where the coal-bearing aquifer is in direct contact with the alluvial aquifer and surface drainage network. A strong connection was observed between the main stream and underlying alluvium, marked by a similar evolution from fresh Ca–Mg–HCO 3 waters in the headwaters towards brackish Ca–Na–Cl composition near the outlet of the catchment, driven by evaporation and transpiration. In the coal-bearing aquifer, by contrast, considerable site-to-site variations were observed, although waters generally had a Na–HCO 3 –Cl facies and high residual alkalinity values. Increased salinity was controlled by several coexisting processes, including transpiration by plants, mineral weathering and possibly degradation of coal organic matter. Longer residence times and relatively enriched carbon isotopic signatures of the downstream alluvial waters were suggestive of potential interactions with the shallow coal-bearing aquifer. The examination of temporal variations in deuterium excess enabled detection of rapid recharge of the coal-bearing aquifer through highly fractured igneous rocks, particularly at the catchment

  19. Effects of UV radiation on freshwater metazooplankton

    International Nuclear Information System (INIS)

    Tartarotti, B.

    1999-06-01

    different life stages of Boeckella gracilipes, moreover, also the reproduction of B. gracilipes is not impaired by UV-B radiation. UV-tolerant or vulnerable zooplankton species can be detected by their lethal (survival) and sublethal (fecundity and development) responses after prolonged exposure to high levels of solar UV-B radiation. The effects of solar UV-B radiation on zooplankton in shallow, slightly humic lakes (Patagonia, Argentina, 41 0 S) were investigated by simulating vertical water mixing and simultanous static UV-exposure. Static incubations accurately predicted the survival of moving individuals for Boeckella gracilipes, a species without photorecovery, but failed to do so for the cladoceran Ceriodaphnia dubia capable of photorecovery. The fluctuations in dosage rate for high doses tended to increase the survival of the species with photorecovery. Neglecting the effects of vertical mixing may result in a biased perception of UV-radiation effects in shallow lakes. UV damage is strongly wavelength dependent. To quantify responses as function of irradiance and time, the biological weighting function of Boeckella gracilipes was obtained by exposing the organisms to progressively shorter wavelengths of UV radiation along with visible irradiance. Not only DNA is highly damaged, but other proteins or cell structures as well. This population is very sensitive to both UV-B and UV-A radiation (< 335 nm). In conclusion, UV radiation can have damaging effects on freshwater zooplankton with enormous inter- and intraspecific differences ranging from very UV-sensitive to very tolerant metazooplankton populations. (author)

  20. Secondary production in shallow marine environments

    International Nuclear Information System (INIS)

    Pomeroy, L.R.

    1976-01-01

    Recommendations are discussed with regard to population ecology, microbial food webs, marine ecosystems, improved instrumentation, and effects of land and sea on shallow marine systems. The control of secondary production is discussed with regard to present status of knowledge; research needs for studies on dominant secondary producers, food webs that lead to commercial species, and significant features of the trophic structure of shallow water marine communities. Secondary production at the land-water interface is discussed with regard to present status of knowledge; importance of macrophytes to secondary production; export to secondary consumers; utilization of macrophyte primary production; and correlations between secondary production and river discharge. The role of microorganisms in secondary production is also discussed

  1. 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...

  2. A faunistic survey of digenean larvae infecting freshwater snails ...

    African Journals Online (AJOL)

    Biomphalaria and Bulinus spp have been reported in Tanzania as vectors of Schistosoma mansoni and Schistosoma haematobium respectively. Thus most schistosomiasis control efforts have focussed on elimination of these molluscs in freshwater systems or deworming infected persons. In addition almost there is limited ...

  3. A hierarchical classification of freshwater mussel diversity in North America

    Science.gov (United States)

    Wendell R. Haag

    2010-01-01

    Aim North America harbours the most diverse freshwater mussel fauna on Earth. This fauna has high endemism at the continental scale and within individual river systems. Previous faunal classifications for North America were based on intuitive, subjective assessments of species distributions, primarily the occurrence of endemic species, and do not portray continent-wide...

  4. 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.

  5. Mapping potential freshwater services, and their representation within Protected Areas (PAs, under conditions of sparse data. Pilot implementation for Cambodia

    Directory of Open Access Journals (Sweden)

    Leonardo Sáenz

    2016-07-01

    Full Text Available Freshwater is arguably one of Earth’s most threatened natural resources, on which more than 7 billion people depend. Pressures on freshwater resources from infrastructure, resource development, agricultural pollution and deforestation are mounting, particularly in developing countries. To date, conservation responses such as Protected Areas (PAs have not typically targeted freshwater ecosystems and their services, and thus little is known about the effectiveness of these efforts in protecting them. This paper proposes and pilots an innovative freshwater services metrics framework to quantify the representation of potential freshwater services in PAs under conditions of scarce data, with a pilot application for Cambodia. Our results indicate that conservation actions have more effectively represented potential freshwater regulation services than potential freshwater provisioning services, with major rivers remaining generally unprotected. Results from the framework are then used to propose a series of context and region specific management options to improve the conservation of freshwater services in Cambodia. There is an acute need for such management options, as the country’s food security depends largely on important freshwater ecosystems such as the Tonle Sap Lake and the deep water pools systems of the Mekong River. The framework proposed can be applied in other countries or large river basins to explore the degree of representation of freshwater services within PAs systems, under conditions of sparse data.

  6. Quality of Shallow Groundwater and Drinking Water in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and the Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2004

    Science.gov (United States)

    Welch, Heather L.; Kingsbury, James A.; Tollett, Roland W.; Seanor, Ronald C.

    2009-01-01

    The Mississippi embayment-Texas coastal uplands aquifer system is an important source of drinking water, providing about 724 million gallons per day to about 8.9 million people in Texas, Louisiana, Mississippi, Arkansas, Missouri, Tennessee, Kentucky, Illinois, and Alabama. The Mississippi River Valley alluvial aquifer ranks third in the Nation for total withdrawals of which more than 98 percent is used for irrigation. From 1994 through 2004, water-quality samples were collected from 169 domestic, monitoring, irrigation, and public-supply wells in the Mississippi embayment-Texas coastal uplands aquifer system and the Mississippi River Valley alluvial aquifer in various land-use settings and of varying well capacities as part of the U.S. Geological Survey's National Water-Quality Assessment Program. Groundwater samples were analyzed for physical properties and about 200 water-quality constituents, including total dissolved solids, major inorganic ions, trace elements, radon, nutrients, dissolved organic carbon, pesticides, pesticide degradates, and volatile organic compounds. The occurrence of nutrients and pesticides differed among four groups of the 114 shallow wells (less than or equal to 200 feet deep) in the study area. Tritium concentrations in samples from the Holocene alluvium, Pleistocene valley trains, and shallow Tertiary wells indicated a smaller component of recent groundwater than samples from the Pleistocene terrace deposits. Although the amount of agricultural land overlying the Mississippi River Valley alluvial aquifer was considerably greater than areas overlying parts of the shallow Tertiary and Pleistocene terrace deposits wells, nitrate was rarely detected and the number of pesticides detected was lower than other shallow wells. Nearly all samples from the Holocene alluvium and Pleistocene valley trains were anoxic, and the reducing conditions in these aquifers likely result in denitrification of nitrate. In contrast, most samples from the

  7. Extensive behavioural divergence following colonisation of the freshwater environment in threespine sticklebacks.

    Directory of Open Access Journals (Sweden)

    Carole Di-Poi

    Full Text Available Colonisation of novel environments means facing new ecological challenges often resulting in the evolution of striking divergence in phenotypes. However, little is known about behavioural divergence following colonisation, despite the predicted importance of the role of behavioural phenotype-environment associations in adaptive divergence. We studied the threespine stickleback (Gasterosteus aculeatus, a model system for postglacial colonisation of freshwater habitats largely differing in ecological conditions from the ones faced by the descendants of the marine ancestor. We found that common-environment reared freshwater juveniles were less social, more active and more aggressive than their marine counterparts. This behavioural divergence could represent the result of natural selection that acted on individuals following freshwater colonisation, with predation as a key selection agent. Alternatively, the behavioural profile of freshwater juveniles could represent the characteristics of individuals that preferentially invaded freshwater after the glacial retreat, drawn from the standing variation present in the marine population.

  8. 3D mapping, hydrodynamics and modelling of the freshwater-brine mixing zone in salt flats similar to the Salar de Atacama (Chile)

    Science.gov (United States)

    Marazuela, M. A.; Vázquez-Suñé, E.; Custodio, E.; Palma, T.; García-Gil, A.; Ayora, C.

    2018-06-01

    Salt flat brines are a major source of minerals and especially lithium. Moreover, valuable wetlands with delicate ecologies are also commonly present at the margins of salt flats. Therefore, the efficient and sustainable exploitation of the brines they contain requires detailed knowledge about the hydrogeology of the system. A critical issue is the freshwater-brine mixing zone, which develops as a result of the mass balance between the recharged freshwater and the evaporating brine. The complex processes occurring in salt flats require a three-dimensional (3D) approach to assess the mixing zone geometry. In this study, a 3D map of the mixing zone in a salt flat is presented, using the Salar de Atacama as an example. This mapping procedure is proposed as the basis of computationally efficient three-dimensional numerical models, provided that the hydraulic heads of freshwater and mixed waters are corrected based on their density variations to convert them into brine heads. After this correction, the locations of lagoons and wetlands that are characteristic of the marginal zones of the salt flats coincide with the regional minimum water (brine) heads. The different morphologies of the mixing zone resulting from this 3D mapping have been interpreted using a two-dimensional (2D) flow and transport numerical model of an idealized cross-section of the mixing zone. The result of the model shows a slope of the mixing zone that is similar to that obtained by 3D mapping and lower than in previous models. To explain this geometry, the 2D model was used to evaluate the effects of heterogeneity in the mixing zone geometry. The higher the permeability of the upper aquifer is, the lower the slope and the shallower the mixing zone become. This occurs because most of the freshwater lateral recharge flows through the upper aquifer due to its much higher transmissivity, thus reducing the freshwater head. The presence of a few meters of highly permeable materials in the upper part of

  9. The origin of shallow lakes in the Khorezm Province, Uzbekistan, and the history of pesticide use around these lakes

    Science.gov (United States)

    Rosen, Michael R.; Crootof, Arica; Reidy, Liam; Saito, Laurel; Nishonov, Bakhriddin; Scott, Julian A.

    2018-01-01

    The economy of the Khorezm Province in Uzbekistan relies on the large-scale agricultural production of cotton. To sustain their staple crop, water from the Amu Darya is diverted for irrigation through canal systems constructed during the early to mid-twentieth century when this region was part of the Soviet Union. These diversions severely reduce river flow to the Aral Sea. The Province has >400 small shallow (data indicate that the majority of the lakes investigated are less than 150 years old, which supports a recent origin of the lakes. The thickness of lacustrine sediments in the cores analyzed ranged from 20 to 60 cm in all but two of the lakes, indicating a relatively slow sedimentation rate and a relatively short-term history for the lakes. Hydrologic changes in the lakes are evident from loss on ignition and pollen analyses of a subset of the lake cores. The data indicate that the lakes have transitioned from a dry, saline, arid landscape during pre-lake conditions (low organic carbon content) and low pollen concentrations (in the basal sediments) to the current freshwater lakes (high organic content), with abundant freshwater pollen taxa over the last 50–70 years. Sediments at the base of the cores contain pollen taxa dominated by Chenopodiaceae and Tamarix, indicating that the vegetation growing nearby was tolerant to arid saline conditions. The near surface sediments of the cores are dominated by Typha/Sparganium, which indicate freshwater conditions. Increases in pollen of weeds and crop plants indicate an intensification of agricultural activities since the 1950s in the watersheds of the lakes analyzed. Pesticide profiles of DDT (dichlorodiphenyltrichloroethane) and its degradates and γ-HCH (gamma-hexachlorocyclohexane), which were used during the Soviet era, show peak concentrations in the top 10 cm of some of the cores, where estimated ages of the sediments (1950–1990) are associated with peak pesticide use during the Soviet era. These data

  10. Shallow land disposal technology

    Energy Technology Data Exchange (ETDEWEB)

    Pillette-Cousin, L. [Nuclear Environment Technology Insitute, Taejon (Korea, Republic of Korea )

    1997-12-31

    This paper covers the radioactive waste management policy and regulatory framework, the characteristics of low and intermediate level radioactive waste, the characteristics of waste package, the waste acceptance criteria, the waste acceptance and related activities, the design of the disposal system, the organization of waste transportation, the operation feature, the safety assessment of the Centre de L`Aube, the post closure measures, the closure of the Centre de la Mache disposal facility, the licensing issues. 3 tabs., 7 figs.

  11. Shallow land disposal technology

    International Nuclear Information System (INIS)

    Pillette-Cousin, L.

    1997-01-01

    This paper covers the radioactive waste management policy and regulatory framework, the characteristics of low and intermediate level radioactive waste, the characteristics of waste package, the waste acceptance criteria, the waste acceptance and related activities, the design of the disposal system, the organization of waste transportation, the operation feature, the safety assessment of the Centre de L'Aube, the post closure measures, the closure of the Centre de la Mache disposal facility, the licensing issues. 3 tabs., 7 figs

  12. Freshwater and Saline Loads of Dissolved Inorganic Nitrogen to Hood Canal and Lynch Cove, Western Washington

    Science.gov (United States)

    Paulson, Anthony J.; Konrad, Christopher P.; Frans, Lonna M.; Noble, Marlene; Kendall, Carol; Josberger, Edward G.; Huffman, Raegan L.; Olsen, Theresa D.

    2006-01-01

    Hood Canal is a long (110 kilometers), deep (175 meters) and narrow (2 to 4 kilometers wide) fjord of Puget Sound in western Washington. The stratification of a less dense, fresh upper layer of the water column causes the cold, saltier lower layer of the water column to be isolated from the atmosphere in the late summer and autumn, which limits reaeration of the lower layer. In the upper layer of Hood Canal, the production of organic matter that settles and consumes dissolved oxygen in the lower layer appears to be limited by the load of dissolved inorganic nitrogen (DIN): nitrate, nitrite, and ammonia. Freshwater and saline loads of DIN to Hood Canal were estimated from available historical data. The freshwater load of DIN to the upper layer of Hood Canal, which could be taken up by phytoplankton, came mostly from surface and ground water from subbasins, which accounts for 92 percent of total load of DIN to the upper layer of Hood Canal. Although DIN in rain falling on land surfaces amounts to about one-half of the DIN entering Hood Canal from subbasins, rain falling directly on the surface of marine waters contributed only 4 percent of the load to the upper layer. Point-source discharges and subsurface flow from shallow shoreline septic systems contributed less than 4 percent of the DIN load to the upper layer. DIN in saline water flowing over the sill into Hood Canal from Admiralty Inlet was at least 17 times the total load to the upper layer of Hood Canal. In September and October 2004, field data were collected to estimate DIN loads to Lynch Cove - the most inland marine waters of Hood Canal that routinely contain low dissolved-oxygen waters. Based on measured streamflow and DIN concentrations, surface discharge was estimated to have contributed about one-fourth of DIN loads to the upper layer of Lynch Cove. Ground-water flow from subbasins was estimated to have contributed about one-half of total DIN loads to the upper layer. In autumn 2004, the relative

  13. Population Genetic Structure of Cnesterodon decemmaculatus (Poeciliidae): A Freshwater Look at the Pampa Biome in Southern South America.

    Science.gov (United States)

    Ramos-Fregonezi, Aline M C; Malabarba, Luiz R; Fagundes, Nelson J R

    2017-01-01

    The Pampas is a Neotropical biome formed primarily by low altitude grasslands and encompasses the southernmost portion of Brazil, Uruguay, and part of Argentina. Despite the high level of endemism, and its significant environmental heterogeneity, Pampean species are underrepresented in phylogeographic studies, especially aquatic organisms. The Pampean hydrological system resulted from a long history of tectonism, climate, and sea level changes since the Neogene. In this study, we examined the population genetic structure of Cnesterodon decemmaculatus , a freshwater fish species that occurs throughout most of the Pampa biome. We characterized mitochondrial and autosomal genetic lineages in populations sampled from Southern Brazil and Uruguay to investigate (1) the correspondence between current drainage systems and evolutionary lineages, (2) the demographic history for each genetic lineage, and (3) the temporal depth of these lineages. Overall, we found that the major evolutionary lineages in this species are strongly related to the main Pampean drainage systems, even though stream capture events may have affected the distribution of genetic lineages among drainages. There was evidence for recent population growth in the lineages occupying drainages closest to the shore, which may indicate the effect of quaternary sea-level changes. In general, divergence time estimates among evolutionary lineages were shallow, ranging from 20,000 to 800,000 years before present, indicating a geologically recent history for this group, as previously reported in other Pampean species. A Bayesian phylogeographical reconstruction suggested that an ancestral lineage probably colonized the Uruguay River Basin, and then expanded throughout the Pampas. This evolutionary scenario may represent useful starting models for other freshwater species having a similar distribution.

  14. Population Genetic Structure of Cnesterodon decemmaculatus (Poeciliidae: A Freshwater Look at the Pampa Biome in Southern South America

    Directory of Open Access Journals (Sweden)

    Aline M. C. Ramos-Fregonezi

    2017-12-01

    Full Text Available The Pampas is a Neotropical biome formed primarily by low altitude grasslands and encompasses the southernmost portion of Brazil, Uruguay, and part of Argentina. Despite the high level of endemism, and its significant environmental heterogeneity, Pampean species are underrepresented in phylogeographic studies, especially aquatic organisms. The Pampean hydrological system resulted from a long history of tectonism, climate, and sea level changes since the Neogene. In this study, we examined the population genetic structure of Cnesterodon decemmaculatus, a freshwater fish species that occurs throughout most of the Pampa biome. We characterized mitochondrial and autosomal genetic lineages in populations sampled from Southern Brazil and Uruguay to investigate (1 the correspondence between current drainage systems and evolutionary lineages, (2 the demographic history for each genetic lineage, and (3 the temporal depth of these lineages. Overall, we found that the major evolutionary lineages in this species are strongly related to the main Pampean drainage systems, even though stream capture events may have affected the distribution of genetic lineages among drainages. There was evidence for recent population growth in the lineages occupying drainages closest to the shore, which may indicate the effect of quaternary sea-level changes. In general, divergence time estimates among evolutionary lineages were shallow, ranging from 20,000 to 800,000 years before present, indicating a geologically recent history for this group, as previously reported in other Pampean species. A Bayesian phylogeographical reconstruction suggested that an ancestral lineage probably colonized the Uruguay River Basin, and then expanded throughout the Pampas. This evolutionary scenario may represent useful starting models for other freshwater species having a similar distribution.

  15. A Strategy to Conduct an Analysis of the Long-Term Performance of Low-Activity Waste Glass in a Shallow Subsurface Disposal System at Hanford

    Energy Technology Data Exchange (ETDEWEB)

    Neeway, James J.; Pierce, Eric M.; Freedman, Vicky L.; Ryan, Joseph V.; Qafoku, Nikolla

    2014-08-04

    The federal facilities located on the Hanford Site in southeastern Washington State have been used extensively by the U.S. government to produce nuclear materials for the U.S. strategic defense arsenal. Currently, the Hanford Site is under the stewardship of the U.S. Department of Energy (DOE) Office of Environmental Management (EM). A large inventory of radioactive and mixed waste resulting from the production of nuclear materials has accumulated, mainly in 177 underground single- and double-shell tanks located in the central plateau of the Hanford Site (Mann et al., 2001). The DOE-EM Office of River Protection (ORP) is proceeding with plans to immobilize and permanently dispose of the low-activity waste (LAW) fraction onsite in a shallow subsurface disposal facility (the Integrated Disposal Facility [IDF]). Pacific Northwest National Laboratory (PNNL) was contracted to provide the technical basis for estimating radionuclide release from the engineered portion of the IDF (the source term) as part of an immobilized low-activity waste (ILAW) glass testing program to support future IDF performance assessments (PAs).

  16. Shallow flows with bottom topography

    NARCIS (Netherlands)

    Heijst, van G.J.F.; Kamp, L.P.J.; Theunissen, R.; Rodi, W.; Uhlmann, M.

    2012-01-01

    This paper discusses laboratory experiments and numerical simulations of dipolar vortex flows in a shallow fluid layer with bottom topography. Two cases are considered: a step topography and a linearly sloping bottom. It is found that viscous effects – i.e., no-slip conditions at the non-horizontal

  17. Mass development of monospecific submerged macrophyte vegetation after the restoration of shallow lakes: roles of light, sediment nutrient levels, and propagule density

    NARCIS (Netherlands)

    Verhofstad, M.J.J.M.; Alirangues, Marta Maria; Reichman, Erik; van Donk, E.; Lamers, L.P.M.; Bakker, E.S.

    2017-01-01

    Abstract After restoration, eutrophicated shallow freshwaters may show mass development of only one or two submerged macrophyte species, lowering biodiversity and hampering recreation. It is unclear which environmental factors govern this high percentage of the volume inhabited (PVI11 PVI: The

  18. 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...

  19. 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.

  20. Computerised Decision Support Systems for the management of freshwater radioecological emergencies: assessment of the state-of-the-art with respect to the experiences and needs of end-users

    International Nuclear Information System (INIS)

    Hofman, D.; Monte, L.; Boyer, P.; Brittain, J.; Donchyts, G.; Gallego, E.; Gheorghiu, D.; Hakanson, L.; Heling, R.; Kerekes, A.; Kocsy, G.; Lepicard, S.; Slavik, O.; Slavnicu, D.; Smith, J.; Zheleznyak, M.

    2011-01-01

    Assessment of the environmental and radiological consequences of a nuclear accident requires the management of a great deal of data and information as well as the use of predictive models. Computerised Decision Support Systems (CDSS) are essential tools for this kind of complex assessment and for assisting experts with a rational decision process. The present work focuses on the assessment of the main features of selected state-of-the-art CDSS for off-site management of freshwater ecosystems contaminated by radionuclides. This study involved both developers and end-users of the assessed CDSS and was based on practical customisation exercises, installation and application of the decision systems. Potential end-users can benefit from the availability of several ready-to-use CDSS that allow one to run different kinds of models aimed at predicting the behaviour of radionuclides in aquatic ecosystems, evaluating doses to humans, assessing the effectiveness of different kinds of environmental management interventions and ranking these interventions, accounting for their social, economic and environmental impacts. As a result of the present assessment, the importance of CDSS 'integration' became apparent: in many circumstances, different CDSS can be used as complementary tools for the decision-making process. The results of this assessment can also be useful for the future development and improvement of the CDSS. - Research highlights: →The present work focuses on the assessment of the main features of selected state-of-the-art CDSS for the off-site management of freshwater ecosystems contaminated by radionuclides. →Potential end-users can benefit from a number of complementary open, freely-available and ready-to-use CDSS based on validated environmental models aimed at predicting the migration of radionuclides in the aquatic environment, evaluating the doses to man, assessing the effectiveness of different environmental feasible restoration strategies and

  1. Modelling Hydrological Processes in Created Freshwater Wetlands:an Integrated System Approach%人工淡水湿地的水文过程模拟:综合系统法(摘要)

    Institute of Scientific and Technical Information of China (English)

    张立; 威廉·杰·米奇

    2006-01-01

    This study investigates hydrologic processes of four different flow-through created freshwater wetlands in Ohio, USA, by use of several versions of a simple daily mass-balance water budget model.The model includes surface inflows and outflows, precipitation, evapotranspiration, and groundwater seepage. We calibrated the daily water budget for two experimental wetlands that had pumped inflow during 1999 and validated it during 2000 - 2002 on the same basins. The coefficient of prediction efficiency is 0.70 and the modelled hydroperiod followed observed water depths during the calibration period well. The average retention time in the calibration year 1999 was 4.4 - 4.6 days. The model was applied to a 3-ha created riparian wetland that receives river flooding. Results illustrated that this wetland has developed a hydroperiod with more than sufficient flooding to ensure that it will meet the hydrologic criteria of a formal jurisdictional wetland definition in the USA. Water budget predictions for a stormwater wetland provided useful design information for hydroperiod and hydrologic dynamics prior to the construction of that system. The model was simulated for average, dry, and wet years. An integrated systems approach was developed using a STELLA 7.0 with its capabilities of dynamicinterface level control (e. g. buttons and switches) features.

  2. Biota connect aquatic habitats throughout freshwater ecosystem mosaics

    Science.gov (United States)

    Schofield, Kate A.; Alexander, Laurie C.; Ridley, Caroline E.; Vanderhoof, Melanie; Fritz, Ken M.; Autrey, Bradley; DeMeester, Julie; Kepner, William G.; Lane, Charles R.; Leibowitz, Scott; Pollard, Amina I.

    2018-01-01

    Freshwater ecosystems are linked at various spatial and temporal scales by movements of biota adapted to life in water. We review the literature on movements of aquatic organisms that connect different types of freshwater habitats, focusing on linkages from streams and wetlands to downstream waters. Here, streams, wetlands, rivers, lakes, ponds, and other freshwater habitats are viewed as dynamic freshwater ecosystem mosaics (FEMs) that collectively provide the resources needed to sustain aquatic life. Based on existing evidence, it is clear that biotic linkages throughout FEMs have important consequences for biological integrity and biodiversity. All aquatic organisms move within and among FEM components, but differ in the mode, frequency, distance, and timing of their movements. These movements allow biota to recolonize habitats, avoid inbreeding, escape stressors, locate mates, and acquire resources. Cumulatively, these individual movements connect populations within and among FEMs and contribute to local and regional diversity, resilience to disturbance, and persistence of aquatic species in the face of environmental change. Thus, the biological connections established by movement of biota among streams, wetlands, and downstream waters are critical to the ecological integrity of these systems. Future research will help advance our understanding of the movements that link FEMs and their cumulative effects on downstream waters.

  3. Genetic calibration of species diversity among North America's freshwater fishes.

    Science.gov (United States)

    April, Julien; Mayden, Richard L; Hanner, Robert H; Bernatchez, Louis

    2011-06-28

    Freshwater ecosystems are being heavily exploited and degraded by human activities all over the world, including in North America, where fishes and fisheries are strongly affected. Despite centuries of taxonomic inquiry, problems inherent to species identification continue to hamper the conservation of North American freshwater fishes. Indeed, nearly 10% of species diversity is thought to remain undescribed. To provide an independent calibration of taxonomic uncertainty and to establish a more accessible molecular identification key for its application, we generated a standard reference library of mtDNA sequences (DNA barcodes) derived from expert-identified museum specimens for 752 North American freshwater fish species. This study demonstrates that 90% of known species can be delineated using barcodes. Moreover, it reveals numerous genetic discontinuities indicative of independently evolving lineages within described species, which points to the presence of morphologically cryptic diversity. From the 752 species analyzed, our survey flagged 138 named species that represent as many as 347 candidate species, which suggests a 28% increase in species diversity. In contrast, several species of parasitic and nonparasitic lampreys lack such discontinuity and may represent alternative life history strategies within single species. Therefore, it appears that the current North American freshwater fish taxonomy at the species level significantly conceals diversity in some groups, although artificially creating diversity in others. In addition to providing an easily accessible digital identification system, this study identifies 151 fish species for which taxonomic revision is required.

  4. Establishing a database of radionuclide transfer parameters for freshwater wildlife

    International Nuclear Information System (INIS)

    Yankovich, T.; Beresford, N.A.; Fesenko, S.; Fesenko, J.; Phaneuf, M.; Dagher, E.; Outola, I.; Andersson, P.; Thiessen, K.; Ryan, J.; Wood, M.D.; Bollhöfer, A.

    2013-01-01

    Environmental assessments to evaluate potentials risks to humans and wildlife often involve modelling to predict contaminant exposure through key pathways. Such models require input of parameter values, including concentration ratios, to estimate contaminant concentrations in biota based on measurements or estimates of concentrations in environmental media, such as water. Due to the diversity of species and the range in physicochemical conditions in natural ecosystems, concentration ratios can vary by orders of magnitude, even within similar species. Therefore, to improve model input parameter values for application in aquatic systems, freshwater concentration ratios were collated or calculated from national grey literature, Russian language publications, and refereed papers. Collated data were then input into an international database that is being established by the International Atomic Energy Agency. The freshwater database enables entry of information for all radionuclides listed in ICRP (1983), in addition to the corresponding stable elements, and comprises a total of more than 16,500 concentration ratio (CR wo-water ) values. Although data were available for all broad wildlife groups (with the exception of birds), data were sparse for many organism types. For example, zooplankton, crustaceans, insects and insect larvae, amphibians, and mammals, for which there were CR wo-water values for less than eight elements. Coverage was most comprehensive for fish, vascular plants, and molluscs. To our knowledge, the freshwater database that has now been established represents the most comprehensive set of CR wo-water values for freshwater species currently available for use in radiological environmental assessments

  5. Dolichospermum and Aphanizomenon as neurotoxins producers in some Russian freshwaters.

    Science.gov (United States)

    Chernova, Ekaterina; Sidelev, Sergey; Russkikh, Iana; Voyakina, Ekaterina; Babanazarova, Olga; Romanov, Roman; Kotovshchikov, Anton; Mazur-Marzec, Hanna

    2017-05-01

    Last decades, cyanobacterial blooms have been commonly reported in Russia. Among the boom-forming species, potential toxin producers have been identified. The aim of this paper was to study the presence of neurotoxic compounds - saxitoxins and anatoxin-a - in water bodies from different regions of Russia. We also made attempts to identify the neurotoxin-producing genera. The good convergence of the results obtained by light microscopy, PCR and LC-MS/MS analyses indicated the presence of active neurotoxin producing species in all investigated water bodies. Saxitoxin was detected in phytoplankton from 4 water bodies in Central European Russia and West Siberia, including lake and reservoirs used as a source for potable water. The water bodies differed with the respect of saxitoxin producers which belonged to Aphanizomenon and/or Dolichospermum genera. For the first time, we obtained quantitative data on the intracellular saxitoxin concentration in Russian freshwaters using LC-MS/MS. Anatoxin-a was detected only in lakes of Northwestern Russia. In the eutrophic shallow Lower Suzdal Lake, Aphanizomenon was the stated anatoxin-a-producing genus. In the large shallow artificial hypertrophic Sestroretskij Razliv Lake, it was very likely that both dominant species - Aphanizomenon flos-aquae and Dolichospermum planctonicum - were anatoxin-a producers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Evaluation of alternative macroinvertebrate sampling techniques for use in a new tropical freshwater bioassessment scheme

    OpenAIRE

    Isabel Eleanor Moore; Kevin Joseph Murphy

    2015-01-01

    Aim: The study aimed to determine the effectiveness of benthic macroinvertebrate dredge net sampling procedures as an alternative method to kick net sampling in tropical freshwater systems, specifically as an evaluation of sampling methods used in the Zambian Invertebrate Scoring System (ZISS) river bioassessment scheme. Tropical freshwater ecosystems are sometimes dangerous or inaccessible to sampling teams using traditional kick-sampling methods, so identifying an alternative procedure that...

  7. Fish community structure in freshwater karstic water bodies of the Sian Ka'an Reserve in the Yucatan peninsula, Mexico

    Science.gov (United States)

    Zambrano, L.; Vazquez-Dominguez, E.; Garcia-Bedoya, D.; Loftus, W.F.; Trexler, J.C.

    2006-01-01

    We evaluated the relationship between limnetic characteristics and fish community structure (based on species richness, abundance and individual size) in contrasting but interconnected inland aquatic habitats of freshwater karstic wetlands in the Yucatan peninsula, Mexico. In the western hemisphere, freshwater karstic wetlands are found in south-eastern Mexico, northern Belize, western Cuba, Andros Island, Bahamas and the Everglades of southern Florida. Only in the Everglades have fish communities been well described. Karstic wetlands are typically oligotrophic because calcium carbonate binds phosphorus, making it relatively unavailable for plants. Fourteen permanent and seasonally flooded water bodies were sampled in both wet and dry seasons in Sian Ka'an Biosphere Reserve, in the Mexican state of Quintana Roo. Water systems were divided by morphology in four groups: cenotes with vegetation (CWV), cenotes without vegetation (CNV), wetlands (WTL), and temporal cenotes (TPC). Discriminant analysis based on physical characteristics such as turbidity, temperature, depth and oxygen confirmed that these habitats differed in characteristics known to influence fish communities. A sample-based rarefaction test showed that species richness was significantly different between water systems groups, showing that WTL and CWV had higher richness values than CNV and TPC. The most abundant fish families, Poeciliidae, Cichlidae and Characidae, differed significantly in average size among habitats and seasons. Seasonal and inter-annual variation, reflecting temporal variation in rainfall, strongly influenced the environmental differences between shallow and deep habitats, which could be linked to fish size and life cycles. Five new records of species were found for the reserve, and one new record for Quintana Roo state. ?? 2006 by Verlag Dr. Friedrich Pfeil.

  8. 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.

  9. 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...

  10. 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)

  11. Interactions between nutrients and organic micro-pollutants in shallow freshwater ecosystems

    NARCIS (Netherlands)

    Roessink, I.; Koelmans, A.A.; Brock, T.C.M.

    2008-01-01

    Effects of nutrients and toxicants in aquatic ecosystems may interact in several ways. Here, we (a) present an overview of reported mechanisms that may play a role in these interactions, and (b) compare these reported mechanisms against the results of a suite of experiments performed with organic

  12. Temporal dynamics of AVS and SEM in sediment of shallow freshwater floodplain lakes

    NARCIS (Netherlands)

    Griethuysen, van C.; Lange, de H.J.; Heuij, van der M.; Bies, S.C.; Gillissen, F.; Koelmans, A.A.

    2006-01-01

    Acid volatile sulfide (AVS) is an operationally defined sulfide fraction, which is considered important for trace metal fate in reduced sediments. Understanding AVS formation rates is important for the management of metal polluted sediment. However, little lis known about the fate and dynamics of

  13. 2010 Hudson River Shallow Water Sediment Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Hudson River Shallow Water Mapping project characterizes the bottom of the Hudson River Estuary in shallow water (<3 m). The characterization includes...

  14. 3D seismic surveys for shallow targets

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, D.C.; Stewart, R.R.; Bertram, M.B. [Calgary Univ., AB (Canada). Dept. of Geoscience, Consortium for Research in Elastic Wave Exploration Seismology

    2008-07-01

    Although 3D seismic surveys are generally used to map deep hydrocarbon plays, this study demonstrated that they can be useful for characterizing shallow targets, such as oilsands deposits. A high-resolution 3D seismic survey was undertaken to map shallow stratigraphy near Calgary, Alberta. The project demonstrated the efficacy of reflection seismic surveys for shallow targets ranging from 100 to 500 metres. The purpose of the program was to map shallow stratigraphy and structure to depths of up to 500m, and to investigate shallow aquifers in the study area. The results of the survey illustrated the opportunity that 3D seismic surveys provide for mapping shallow reflectors and the acquisition geometry needed to image them. Applications include mapping the distribution of shallow aquifers, delineating shallow coals and investigating oilsands deposits. 2 refs., 5 figs.

  15. Shallow Aquifer Methane Gas Source Assessment

    Science.gov (United States)

    Coffin, R. B.; Murgulet, D.; Rose, P. S.; Hay, R.

    2014-12-01

    Shale gas can contribute significantly to the world's energy demand. Hydraulic fracturing (fracking) on horizontal drill lines developed over the last 15 years makes formerly inaccessible hydrocarbons economically available. From 2000 to 2035 shale gas is predicted to rise from 1% to 46% of the total natural gas for the US. A vast energy resource is available in the United States. While there is a strong financial advantage to the application of fracking there is emerging concern about environmental impacts to groundwater and air quality from improper shale fracking operations. Elevated methane (CH4) concentrations have been observed in drinking water throughout the United States where there is active horizontal drilling. Horizontal drilling and hydraulic-fracturing can increase CH4 transport to aquifers, soil and the vadose zone. Seepage can also result from casing failure in older wells. However, there is strong evidence that elevated CH4 concentrations can be associated with topographic and hydrogeologic features, rather than shale-gas extraction processes. Carbon isotope geochemistry can be applied to study CH4source(s) in shallow vadose zone and groundwater systems. A preliminary TAMU-CC isotope data set from samples taken at different locations in southern Texas shows a wide range of CH4 signatures suggesting multiple sources of methane and carbon dioxide. These data are interpreted to distinguish regions with methane contributions from deep-sourced horizontal drilling versus shallow system microbial production. Development of a thorough environmental assessment using light isotope analysis can provide understanding of shallow anthropogenic versus natural CH4sources and assist in identifying regions that require remedial actions.

  16. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

    of magnitude and 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 14C years can occur within one river. The freshwater reservoir effect has also implications......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...

  17. 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......The freshwater reservoir effect can result in too high radiocarbon ages of samples from lakes and rivers, including the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. In my talk, I will explain the causes and consequences of this effect. Two...... 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....

  18. Electrostatically Tunable Nanomechanical Shallow Arches

    KAUST Repository

    Kazmi, Syed N. R.

    2017-11-03

    We report an analytical and experimental study on the tunability of in-plane doubly-clamped nanomechanical arches under varied DC bias conditions at room temperature. For this purpose, silicon based shallow arches are fabricated using standard e-beam lithography and surface nanomachining of a highly conductive device layer on a silicon-on-insulator (SOI) wafer. The experimental results show good agreement with the analytical results with a maximum tunability of 108.14% for 180 nm thick arch with a transduction gap of 1 μm between the beam and the driving/sensing electrodes. The high tunability of shallow arches paves the ways for highly tunable band pass filtering applications in high frequency range.

  19. Comparison of population genetic patterns in two widespread freshwater mussels with contrasting life histories in western North America.

    Science.gov (United States)

    Mock, K E; Brim Box, J C; Chong, J P; Furnish, J; Howard, J K

    2013-12-01

    We investigate population genetic structuring in Margaritifera falcata, a freshwater mussel native to western North America, across the majority of its geographical range. We find shallow rangewide genetic structure, strong population-level structuring and very low population diversity in this species, using both mitochondrial sequence and nuclear microsatellite data. We contrast these patterns with previous findings in another freshwater mussel species group (Anodonta californiensis/A. nuttalliana) occupying the same continental region and many of the same watersheds. We conclude that differences are likely caused by contrasting life history attributes between genera, particularly host fish requirements and hermaphroditism. Further, we demonstrate the occurrence of a 'hotspot' for genetic diversity in both groups of mussels, occurring in the vicinity of the lower Columbia River drainage. We suggest that stream hierarchy may be responsible for this pattern and may produce similar patterns in other widespread freshwater species. © 2013 John Wiley & Sons Ltd.

  20. Angular dependence of shallow dose

    International Nuclear Information System (INIS)

    Alvarez, J.L.

    1986-01-01

    The theoretical response of a detector is discussed and compared to measurements of shallow dose with tissue and phantom response detectors. A definite energy dependent angular response of dose and measurement was observed which could not be explained by simple trigonometric arguments. The response is back scatter dependent and must be considered in detector design and dose measurements. It is not possible for standard detectors to follow this response

  1. The freshwater balance of polar regions in transient simulations from 1500 to 2100 AD using a comprehensive coupled climate model

    Energy Technology Data Exchange (ETDEWEB)

    Lehner, Flavio; Raible, Christoph C.; Hofer, Dominik; Stocker, Thomas F. [University of Bern, Climate and Environmental Physics, Physics Institute, and Oeschger Centre for Climate Change Research, Bern (Switzerland)

    2012-07-15

    The ocean and sea ice in both polar regions are important reservoirs of freshwater within the climate system. While the response of these reservoirs to future climate change has been studied intensively, the sensitivity of the polar freshwater balance to natural forcing variations during preindustrial times has received less attention. Using an ensemble of transient simulations from 1500 to 2100 AD we put present-day and future states of the polar freshwater balance in the context of low frequency variability of the past five centuries. This is done by focusing on different multi-decadal periods of characteristic external forcing. In the Arctic, freshwater is shifted from the ocean to sea ice during the Maunder Minimum while the total amount of freshwater within the Arctic domain remains unchanged. In contrast, the subsequent Dalton Minimum does not leave an imprint on the slow-reacting reservoirs of the ocean and sea ice, but triggers a drop in the import of freshwater through the atmosphere. During the twentieth and twenty-first century the build-up of freshwater in the Arctic Ocean leads to a strengthening of the liquid export. The Arctic freshwater balance is shifted towards being a large source of freshwater to the North Atlantic ocean. The Antarctic freshwater cycle, on the other hand, appears to be insensitive to preindustrial variations in external forcing. In line with the rising temperature during the industrial era the freshwater budget becomes increasingly unbalanced and strengthens the high latitude's Southern Ocean as a source of liquid freshwater to lower latitude oceans. (orig.)

  2. Availability, usage, and threats to freshwater resources on low carbonate islands in Micronesia

    Science.gov (United States)

    Taboroši, Danko; Jenson, John W.; Sánchez Collazo, Maricruz; Zega, Mojca

    2010-05-01

    Federated States of Micronesia (FSM) is an insular nation in the western Pacific. It consists of 4 high volcanic islands and 37 low carbonate units, mostly coral atolls. The high islands are relatively large, and are developing socioeconomic centers of the country, whereas low islands are small and remote outposts of traditional subsistence lifestyle. The latter are inhabited by a fifth of the nation's population of 107,000 people. Total land area of a typical low island is a fraction of a km2, yet may be home to hundreds of people, creating some of the highest population densities in the Pacific. The resultant extreme pressures on natural resources are exacerbated by severe weather hazards, especially typhoons and unusually high tides which have recently flooded some islands in entirety, damaging homes and food sources. Freshwater resources are particularly sensitive. Crowded low islands have some of the world's most unfavorable relationships between population density and freshwater availability. As there are no communal or municipal facilities and government operated infrastructure, people have only two sources of water available for consumption: rainwater and groundwater. Rain is captured by individual households' thatch or corrugated iron roofs and transferred by gutters to concrete or fiberglass tanks. It is used for drinking, cooking, and dishwashing, and depending on availability, for laundry and showering. Such arrangement are highly unreliable, because they depend on sufficient rainfall and islanders' ability to capture and store it. Some communities have actually run out of water in the past, as a result of prolonged droughts or typhoons' damage to the catchment systems. In addition, tropical climate and pervasive organic matter and microorganisms make the tanks' maintenance difficult, because even most conscientious cleaning cannot ensure that stored water remains potable. Stomach problems and more serious health complications are common. Groundwater

  3. Can environmental impact assessments alone conserve freshwater fish biota? Review of the Chilean experience

    Energy Technology Data Exchange (ETDEWEB)

    Lacy, Shaw Nozaki, E-mail: shaw.lacy@gmail.com [Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago (Chile); Departmento de Ecosistemas y Medio Ambiente, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Macul (Chile); Centro Interdisciplinario de Cambio Global, Vicuña Mackenna 4860, Macul (Chile); Meza, Francisco J. [Departmento de Ecosistemas y Medio Ambiente, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Macul (Chile); Centro Interdisciplinario de Cambio Global, Vicuña Mackenna 4860, Macul (Chile); Marquet, Pablo A. [Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago (Chile); Instituto de Ecología y Biodiversidad, Las Palmeras 345, Santiago (Chile); Centro Interdisciplinario de Cambio Global, Vicuña Mackenna 4860, Macul (Chile)

    2017-03-15

    Chile was one of many countries that initiated environmental impact assessments in the 1990s, and has relied on their use for species conservation and territorial planning without the use of larger-scale environmental and ecological planning. The capacity of Chile's environmental impact assessment system (SEIA) to evaluate resident freshwater fishes and the potential impacts of water projects and aquaculture activities – two categories of projects that create direct threats to freshwater fishes – are assessed. Of the 3997 such submissions to the SEIA, only 0.6% conducted any freshwater fish assessment, and only 0.1% conducted any quantitative assessment of expected impacts from the associated project. The small number of assessments was characterized by poor study design, inconsistent sampling methodology, and species misidentification. Traditional assessments failed to include freshwater fish ecology in the general assessment framework. The new strategic environmental evaluation system only underscores the need for vastly improved field sampling protocols and assessment methodologies.

  4. Can environmental impact assessments alone conserve freshwater fish biota? Review of the Chilean experience

    International Nuclear Information System (INIS)

    Lacy, Shaw Nozaki; Meza, Francisco J.; Marquet, Pablo A.

    2017-01-01

    Chile was one of many countries that initiated environmental impact assessments in the 1990s, and has relied on their use for species conservation and territorial planning without the use of larger-scale environmental and ecological planning. The capacity of Chile's environmental impact assessment system (SEIA) to evaluate resident freshwater fishes and the potential impacts of water projects and aquaculture activities – two categories of projects that create direct threats to freshwater fishes – are assessed. Of the 3997 such submissions to the SEIA, only 0.6% conducted any freshwater fish assessment, and only 0.1% conducted any quantitative assessment of expected impacts from the associated project. The small number of assessments was characterized by poor study design, inconsistent sampling methodology, and species misidentification. Traditional assessments failed to include freshwater fish ecology in the general assessment framework. The new strategic environmental evaluation system only underscores the need for vastly improved field sampling protocols and assessment methodologies.

  5. Small is beautiful: diversity of freshwater ostracods (Crustacea, Ostracoda in marginal habitats of the province of Parma (Northern Italy

    Directory of Open Access Journals (Sweden)

    Stefano TAVERNELLI

    2006-08-01

    Full Text Available A study on the distribution of ostracods in small freshwater habitats of the province of Parma was conducted from May 2004 to December 2005. Vernal pools, ponds, shallow lakes, fountains, springs, ditches, canals, and streams were among the most common types of aquatic systems included in this survey. Altogether, 90 sites located between 24 and 1557 m a.s.l. were visited, and 125 samples were collected. 41 samples did not contain ostracods, and 7 samples were not considered because only immature specimens or empty valves were found. Consequently, 77 samples from 58 sites were analysed. Whenever possible, ostracod identification was done at the species level based on the morphology of both valves and limbs. Thirty-eight taxa from 20 genera belonging to the families Candonidae, Ilyocyprididae, Cyprididae, and Notodromadidae were recorded. This roughly accounts for one-third of the estimated number of non-marine ostracod species in Italy. Scanning electron microscopy images of valves are provided. The maximum number of species per site was six. The most frequent species were Heterocypris incongruens, Eucypris virens, Pseudocandona pratensis, Cypria ophthalmica, and Tonnacypris lutaria. Of particular relevance is the occurrence of species with a limited known distribution in Italy, viz. Ilyocypris monstrifica, Potamocypris villosa, Candona cf. lindneri, Fabaeformiscandona breuili and Physocypria kraepelini. A putative new species of the genus Candona, here left in open nomenclature, is also reported. Our results highlight the importance of so-called "marginal" aquatic habitats as potential biodiversity hotspots, in spite of the general lack of interest shown by freshwater ecologists and taxonomists in undertaking scientific investigations in these environments.

  6. Assessment of the risk posed by the antifouling booster biocides Irgarol 1051 and diuron to freshwater macrophytes.

    Science.gov (United States)

    Lambert, S J; Thomas, K V; Davy, A J

    2006-05-01

    Antifouling paints are used to reduce the attachment of living organisms to the submerged surfaces of ships, boats and aquatic structures, usually by the release of a biocide. Two 'booster' biocides in common use are the triazine herbicide Irgarol 1051 (N-2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine), and diuron (1-(3,4-dichlorophenyl)-3,3-dimethylurea), which are designed to inhibit algal photosynthesis. Previous research has been directed at the effects of these compounds in marine and estuarine environments. In 2001 we sampled the main rivers and shallow freshwater lakes (Broads) of East Anglia UK for Irgarol 1051, its metabolite GS26575 (2-methylamino-4-tert-butylamino-6-amino-s-triazine) and diuron in order to establish the baseline environmental concentrations of these compounds in freshwater systems of eastern UK and to investigate their possible effects on aquatic plants. Irgarol 1051, GS26575 and diuron were found in water samples collected from 21 locations. The highest concentrations were found in the Norfolk and Suffolk Broads in May. The rivers Great Ouse, Wissey, Bure and Yare also contained all three compounds, as did the Great Ouse Cut-off Channel. The toxicity of these biocides to three macrophyte species (Apium nodiflorum, Chara vulgaris, and Myriophyllum spicatum) was investigated. Deleterious effects on relative growth rate, the maximum quantum efficiency (Fv/Fm) of photosystem II and, for Apium, root mass production were found. C. vulgaris was generally most sensitive; growth, especially of roots, was strongly affected in A. nodiflorum; growth rate of M. spicatum was sensitive to diuron. No observed effect concentrations (NOEC) were interpolated using standard toxicological analysis. These were compared with measured environmental concentrations (MEC) to determine the ranges of risk quotients (MEC/NOEC). Both Irgarol 1051 and diuron represented significant risks to A. nodiflorum and C. vulgaris in this area.

  7. 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

  8. Pathogenic agents in freshwater resources

    Science.gov (United States)

    Geldreich, Edwin E.

    1996-02-01

    Numerous pathogenic agents have been found in freshwaters used as sources for water supplies, recreational bathing and irrigation. These agents include bacterial pathogens, enteric viruses, several protozoans and parasitic worms more common to tropical waters. Although infected humans are a major source of pathogens, farm animals (cattle, sheep, pigs), animal pets (dogs, cats) and wildlife serve as significant reservoirs and should not be ignored. The range of infected individuals within a given warm-blooded animal group (humans included) may range from 1 to 25%. Survival times for pathogens in the water environment may range from a few days to as much as a year (Ascaris, Taenia eggs), with infective dose levels varying from one viable cell for several primary pathogenic agents to many thousands of cells for a given opportunistic pathogen.As pathogen detection in water is complex and not readily incorporated into routine monitoring, a surrogate is necessary. In general, indicators of faecal contamination provide a positive correlation with intestinal pathogen occurrences only when appropriate sample volumes are examined by sensitive methodology.Pathways by which pathogens reach susceptible water users include ingestion of contaminated water, body contact with polluted recreational waters and consumption of salad crops irrigated by polluted freshwaters. Major contributors to the spread of various water-borne pathogens are sewage, polluted surface waters and stormwater runoff. All of these contributions are intensified during periods of major floods. Several water-borne case histories are cited as examples of breakdowns in public health protection related to water supply, recreational waters and the consumption of contaminated salad crops. In the long term, water resource management must focus on pollution prevention from point sources of waste discharges and the spread of pathogens in watershed stormwater runoff.

  9. The application of surface electrical and shallow geothermic methods in monitoring network design.

    Science.gov (United States)

    Gilkeson, R.H.; Cartwright, K.

    1983-01-01

    There are a variety of surface geophysical methods that are routinely used in geologic investigations. The three broad applications of these methods to evaluate the impact of waste disposal on shallow groundwater flow systems are: 1) evaluation of proposed waste disposal sites; 2) monitoring of site performance; and 3) investigation of contaminant migration at existing sites. Electrical and shallow geothermic are two surface geophysical methods that have application to waste disposal investigations. Of the electrical methods, electrical resistivity has the greatest application with a variety of techniques available. The distribution of temperature in shallow geologic materials (shallow geothermics) may define characteristics of shallow groundwater flow systems including zones of recharge and discharge and lithologic variation in the shallow geologic materials.-from Authors

  10. Shallow ground-water conditions, Tom Green County, Texas

    Science.gov (United States)

    Lee, J.N.

    1986-01-01

    Most of the water needs of Tom Green County, Texas, are supplied by ground water; however, the city of San Angelo is supplied by surface water. Groundwater withdrawals during 1980 (latest year for which data are available) in Tom Green County totaled about 15,300 acre-feet, all derived from shallow aquifers. Shallow aquifers in this report refer to the ground-water system generally less than 400 feet deep that contains water with less than a 10,000 milligrams per liter concentration of dissolved solids; aquifers comprising this system include: The Leona, Comanche Peak, Trinity, Blaine, San Angelo, Choza, Bullwagon, Vale, Standpipe, and Arroyo aquifers.

  11. Spatial Heterogeneity of Water Quality in a Highly Degraded Tropical Freshwater Ecosystem

    Science.gov (United States)

    Zambrano, Luis; Contreras, Victoria; Mazari-Hiriart, Marisa; Zarco-Arista, Alba E.

    2009-02-01

    Awareness of environmental heterogeneity in ecosystems is critical for management and conservation. We used the Xochimilco freshwater system to describe the relationship between heterogeneity and human activities. This tropical aquatic ecosystem south of Mexico City is comprised of a network of interconnected canals and lakes that are influenced by agricultural and urban activities. Environmental heterogeneity was characterized by spatially extensive surveys within four regions of Xochimilco during rainy and dry seasons over 2 years. These surveys revealed a heterogeneous system that was shallow (1.1 m, SD = 0.4 ), warm (17°C, SD = 2.9), well oxygenated (5.0 mg l-1, SD = 3), turbid (45.7 NTU SD = 26.96), and extremely nutrient-rich (NO3-N = 15.9 mg l-1, SD=13.7; NH4-N = 2.88 mg l-1, SD = 4.24; and PO4-P = 8.3 mg l-1, SD = 2.4). Most of the variables were not significantly different between years, but did differ between seasons, suggesting a dynamic system within a span of a year but with a high resilience over longer periods of time. Maps were produced using interpolations to describe distributions of all variables. There was no correlation between individual variables and land use. Consequently, we searched for relationships using all variables together by generating a combined water quality index. Significant differences in the index were apparent among the four regions. Index values also differed within individual region and individual water bodies (e.g., within canals), indicating that Xochimilco has high local heterogeneity. Using this index on a map helped to relate water quality to human activities and provides a simple and clear tool for managers and policymakers.

  12. Safety analysis methodologies for radioactive waste repositories in shallow ground

    International Nuclear Information System (INIS)

    1984-01-01

    The report is part of the IAEA Safety Series and is addressed to authorities and specialists responsible for or involved in planning, performing and/or reviewing safety assessments of shallow ground radioactive waste repositories. It discusses approaches that are applicable for safety analysis of a shallow ground repository. The methodologies, analysis techniques and models described are pertinent to the task of predicting the long-term performance of a shallow ground disposal system. They may be used during the processes of selection, confirmation and licensing of new sites and disposal systems or to evaluate the long-term consequences in the post-sealing phase of existing operating or inactive sites. The analysis may point out need for remedial action, or provide information to be used in deciding on the duration of surveillance. Safety analysis both general in nature and specific to a certain repository, site or design concept, are discussed, with emphasis on deterministic and probabilistic studies

  13. The characteristic and influence factors of extinction depth of shallow groundwater on the high-latitude region: a case study on the Sanjiang Plain, northeast China.

    Science.gov (United States)

    Wang, Xihua

    2018-03-01

    Accurate estimation of extinction depth of shallow groundwater (EDSG) and identification of its influence factors are important for sustainable management of groundwater resources, ecological protection, and human health in intensively irrigated region. In this study, the ratio of actual groundwater depth and EDSG (RAE) method was used to understand the spatial variability of EDSG in the Sanjiang Plain, one of China's largest grain production bases and China's largest inland freshwater wetland region. The study showed a large spatial variation of EDSG in the region. Spatially, the sites, which were in the northeast and center had the deepest and the shallowest EDSG, whereby, indicate that it has higher and lower pumping potential capacity. Many factors including climate, soil parameters, vegetation and topography affected the EDSG. We also identified an area of 3.86 × 10 10  m 2 , which accounting for 35.3% of the entire Sanjiang Plain, has exceeded the ESGD by over exploited for years. Knowledge of the variation and influence factors of EDSG for a certain plant system and the current shallow groundwater condition in the higher latitude region can be a key to the development of preventive actions for large quantity pumping groundwater and protection regional and sustainable development of irrigated agriculture.

  14. Predator-induced reduction of freshwater carbon dioxide emissions

    Science.gov (United States)

    Atwood, Trisha B.; Hammill, Edd; Greig, Hamish S.; Kratina, Pavel; Shurin, Jonathan B.; Srivastava, Diane S.; Richardson, John S.

    2013-03-01

    Predators can influence the exchange of carbon dioxide between ecosystems and the atmosphere by altering ecosystem processes such as decomposition and primary production, according to food web theory. Empirical knowledge of such an effect in freshwater systems is limited, but it has been suggested that predators in odd-numbered food chains suppress freshwater carbon dioxide emissions, and predators in even-numbered food chains enhance emissions. Here, we report experiments in three-tier food chains in experimental ponds, streams and bromeliads in Canada and Costa Rica in the presence or absence of fish (Gasterosteus aculeatus) and invertebrate (Hesperoperla pacifica and Mecistogaster modesta) predators. We monitored carbon dioxide fluxes along with prey and primary producer biomass. We found substantially reduced carbon dioxide emissions in the presence of predators in all systems, despite differences in predator type, hydrology, climatic region, ecological zone and level of in situ primary production. We also observed lower amounts of prey biomass and higher amounts of algal and detrital biomass in the presence of predators. We conclude that predators have the potential to markedly influence carbon dioxide dynamics in freshwater systems.

  15. Seismic modelling of shallow coalfields

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, D.C. (University of Calgary, Calgary, Alberta (Canada). Dept. of Geology and Geophysics.)

    1987-01-01

    This study was undertaken in order to determine whether reflection seismic surveys can be used to map stratigraphic and structural detail of shallow Plains-type coal deposits. Two coalfields in central Alberta were used to examine and determine optimum acquisition parameters for reflection seismic surveys in such settings. The study was based on 1-D and 2-D numerical seismic modelling using sonic and density well logs to formulate a layered earth model. Additional objectives were to interpret the reflection seismic data in terms of geologic features in the study area, and to investigate the relationship between vertical resolution and field acquisition geometry. 27 refs., 41 figs.

  16. Evaluating the chronic effects of nitrate on the health and performance of post-smolt Atlantic salmon Salmo salar in freshwater recirculation aquaculture systems

    Science.gov (United States)

    Commercial production of Atlantic salmon smolts, post-smolts, and market-size fish using land-based recirculation aquaculture systems (RAS) is expanding. RAS generally provide a nutrient-rich environment in which nitrate accumulates as an end-product of nitrification. An 8-month study was conducted ...

  17. Fluid transfer and vein thickness distribution in high and low temperature hydrothermal systems at shallow crustal level in southern Tuscany (Italy

    Directory of Open Access Journals (Sweden)

    Francesco Mazzarini

    2014-06-01

    Full Text Available Geometric analysis of vein systems hosted in upper crustal rocks and developed in high and low temperature hydrothermal systems is presented. The high temperature hydrothermal system consists of tourmaline-rich veins hosted within the contact aureole of the upper Miocene Porto Azzurro pluton in the eastern Elba Island. The low temperature hydrothermal system consists of calcite-rich veins hosted within the Oligocene sandstones of the Tuscan Nappe, exposed along the coast in southern Tuscany. Vein thickness distribution is here used as proxy for inferring some hydraulic properties (transmissivity of the fluid circulation at the time of veins’ formation. We derive estimations of average thickness of veins by using the observed distributions. In the case of power law thickness distributions, the lower the scaling exponent of the distribution the higher the overall transmissivity. Indeed, power law distributions characterised by high scaling exponents have transmissivity three order of magnitude lower than negative exponential thickness distribution. Simple observations of vein thickness may thus provides some clues on the transmissivity in hydrothermal systems.

  18. The Implications of Ranaviruses to European farmed and wild freshwater fish

    DEFF Research Database (Denmark)

    Jensen, Ann Britt Bang

    The present thesis explores the implications of ranaviruses to European farmed and wild freshwater fish. The work presented was carried out as a part of the EU project “Risk assessment of new and emerging systemic iridoviral diseases for European fish and aquatic ecosystems” which was initiated...... in 2005 as a reaction to the speculation that ranaviruses might pose a serious threat to both farmed and wild-living freshwater fish and amphibians within the European community. In the present thesis, the purpose is to determine the implications of ranaviruses to European freshwater farmed and wild......-living fish. The following specific objectives are addressed: Objective 1: To determine the susceptibility of selected European freshwater fish to a panel of ranaviruses Objective 2: To determine whether ornamental fish are susceptible to or can be carriers of ranaviruses Objective 3: To develop a model...

  19. Rogue waves in shallow water

    Science.gov (United States)

    Soomere, T.

    2010-07-01

    Most of the processes resulting in the formation of unexpectedly high surface waves in deep water (such as dispersive and geometrical focusing, interactions with currents and internal waves, reflection from caustic areas, etc.) are active also in shallow areas. Only the mechanism of modulational instability is not active in finite depth conditions. Instead, wave amplification along certain coastal profiles and the drastic dependence of the run-up height on the incident wave shape may substantially contribute to the formation of rogue waves in the nearshore. A unique source of long-living rogue waves (that has no analogues in the deep ocean) is the nonlinear interaction of obliquely propagating solitary shallow-water waves and an equivalent mechanism of Mach reflection of waves from the coast. The characteristic features of these processes are (i) extreme amplification of the steepness of the wave fronts, (ii) change in the orientation of the largest wave crests compared with that of the counterparts and (iii) rapid displacement of the location of the extreme wave humps along the crests of the interacting waves. The presence of coasts raises a number of related questions such as the possibility of conversion of rogue waves into sneaker waves with extremely high run-up. Also, the reaction of bottom sediments and the entire coastal zone to the rogue waves may be drastic.

  20. 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

  1. Identifying national freshwater ecosystem priority areas

    CSIR Research Space (South Africa)

    Nel, JL

    2012-10-01

    Full Text Available This presentation highlights the use of systematic conservation planning to identify priority areas for managing the health of freshwater ecosystems and their associated biodiversity and ecosystem services....

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

    African Journals Online (AJOL)

    SARAH

    2014-01-31

    Jan 31, 2014 ... 2Faculty of Sciences and Techniques, University Marien Ngouabi - PoB 69 Congo Brazzaville ... to collect and realize a biometric characterization of this common freshwater ... information, which will be used by conservation.

  3. Effects of pollution on freshwater fish

    International Nuclear Information System (INIS)

    McKim, J.M.; Anderson, R.L.; Benoit, D.A.; Spehar, R.L.; Stokes, G.N.

    1976-01-01

    Studies of the effects of pollution on freshwater fish are reviewed. Subjects include: inorganic industrial pollutants, man-made disturbances and radioactive pollutants. Topics include uptake distribution, retention, mortality, and lethal doses

  4. Screening of freshwater fungi for decolorizing multiple synthetic dyes.

    Science.gov (United States)

    Yang, Panpan; Shi, Wenxiao; Wang, Hongkai; Liu, Hongmei

    The biodegradation of synthetic dyes by fungi is emerging as an effective and promising approach. In the present study, freshwater fungal strains isolated from submerged woods were screened for the decolorization of 7 synthetic dyes. Subsequently, 13 isolates with high decolorization capability were assessed in a liquid system; they belonged to 9 different fungal species. Several strains exhibited a highly effective decolorization of multiple types of dyes. New absorbance peaks appeared after the treatment with 3 fungal strains, which suggests that a biotransformation process occurred through fungal biodegradation. These results showed the unexploited and valuable capability of freshwater fungi for the treatment of dye-containing effluents. The ability of certain fungi to decolorize dyes is reported here for the first time. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  5. Radionuclide data bases available for bioaccumulation factors for freshwater biota

    International Nuclear Information System (INIS)

    Blaylock, B.G.

    1982-01-01

    Aquatic models currently in use for dose assessment simulate the transfer of radionuclides in aquatic environments and the transfer to man. In these models the assimilation of a radionuclide in aquatic biota is calculated by using a simple empirical relationship known as the bioaccumulation factor (BF) to represent the transfer of the radionuclide from water to organism. The purpose of this article is to review data bases that are available for BFs for freshwater biota and to identify the uncertainties associated with them. Data bases for raidoisotopes of Co, Cs, C, H, I, Pu, Ra, Ru, Sr, and U are reviewed. With the exception of ruthenium and carbon, the review is restricted to BFs determined for natural freshwater systems. Factors influencing the variability of BFs are identified, uncertainties associated with the validation of BFs are discussed, and some guidance is given for collecting data and measuring BFs

  6. Collating data for freshwater biodiversity planning in South Africa

    CSIR Research Space (South Africa)

    Petersen, C

    2010-03-01

    Full Text Available in the landscape on Level 3 according to the National Wetland Classification System 1 = Canyons 2 = Midslope drainages, shallow valleys 3 = Upland drainages, headwaters 4 = U-shaped valleys 5 = Plains 6 = Open slopes 7 = Upper slopes / mesas 8 = Local...

  7. Contribution to freshwater hydro systems multi pollution study: experimental study of metallic and organic micro-pollutants on radionuclides bioaccumulation by fish

    International Nuclear Information System (INIS)

    Ausseil, O.

    2001-07-01

    The influence of some metallic (cadmium, zinc) and organic (17 β-oestradiol, atrazine, polychlorinated biphenyls, polycyclic aromatic hydrocarbons) pollutants on artificial radionuclide ( 110m Ag, 134 Cs 57 Co) bioaccumulation characteristics by rainbow trout (Oncorhynchus mykiss) has been tested. The basic hypothesis of this work assume that the organisms' exposure to pollutants induces mechanisms of response which could modify radionuclides bioaccumulation characteristics. During the experiments, some biological and biochemical (bio-markers) analyses were performed in order to characterize the nature and the intensity of induced stress in the organisms. These experiments were performed in field and in laboratory. The results show that a cadmium and zinc exposure leads to the induction of systems against oxidative stress or systems implied in metal sequestration. It also leads to a strong reduction of 110m Ag (- 60 %) and 134 Cs (- 33 %) bioaccumulation. No effect has been observed on 57 Co bioaccumulation. For all tested organic compounds except for fluoranthene, exposure leads to an increase of radioactive caesium ( + 10 to 45 %) and cobalt (+ 30 to 60 %) quantities bio-accumulated by rainbow trout. Only 17 β-oestradiol exposure leads to an increase of 110m Ag uptake by rainbow trout. Some hypothesis concerning the involved mechanisms are proposed, and the main implications of this work in operational radioecology are discussed. (author)

  8. CAGE BREEDING OF WARM WATER FRESHWATER FISH SPECIES

    Directory of Open Access Journals (Sweden)

    Roman Safner

    2008-10-01

    Full Text Available In the 1970s, Croatia became actively involved in the contemporary trend of breeding fish in floating cages. In addition to various species of marine fishes, breeding was attempted with trout, carp, catfish, cisco and salmon. Of the above freshwater fish species, specific standards were established only for the cage breeding of rainbow trout. Cage breeding of the remaining species remained at the level of occasional attempts, with more of an experimental than a commercial character. The regular attempts to master this technique for cage breeding of warm water freshwater fish species were aimed at achieving the known benefits of such breeding, such as simplicity of implementing technological measures, easier establishment of the breeding system, simpler manipulation, the possibility of denser colonies per unit volume with a high level of production, easier adaptations to market conditions and fewer initial structural investments. Despite the many advantages, the main reasons for the lack of greater implementation of the cage breeding technology for warm water species of freshwater fish include problems in obtaining the appropriate category and quantity of healthy fry, the specificity and applicability of physical and chemical properties of the recipients and human error. In evaluating the advantages and disadvantages, the final decision on the justification of cage breeding for individual warm water freshwater species must be based on both biological and economic factors. Based on the knowledge of cage breeding acquired to date, the rule for virtually all intensive breeding systems is that it is only recommended for those species with high market demand and a high market price. The technology that demands nutrition with highly concentrated feed and other production expenditures is costly, and is therefore not profitable with less expensive fish species. Furthermore, production must be market oriented, i.e. the appropriate market research measures

  9. Flexible riser global analysis for very shallow water

    OpenAIRE

    Karegar, Sadjad

    2013-01-01

    Master's thesis in Offshore technology Flexible risers are widely used for a range of water depths and can accommodate large floater motions when using a buoyant system. A wide range of buoyancy solutions have been developed for very shallow water (e.g. 30-50 m), shallow water (e.g. 90-110 m) and semi-deep water (e.g. 300-400 m) and in the ranges between these depths. Flexible risers can have different configurations. These different solutions have different characteristics which influe...

  10. Short-term alteration of biotic and abiotic components of the pelagic system in a shallow bay produced by a strong natural hypoxia event

    Science.gov (United States)

    Veas, Rodrigo; Anabalón, Valeria; Quiñones, Renato A.

    2017-01-01

    In January 2008 there was an intensive and extensive upwelling event in the southern Humboldt Current System. This event produced an intrusion of water with low dissolved oxygen into Coliumo Bay, which caused massive mortality and the beaching of pelagic and benthic organisms, including zooplankton. During this event, which lasted 3 to 5 days, we studied and evaluated the effect of the hypoxic water in the bay on the abundance of macrozooplankton, nanoplankton and microphytoplankton, the concentration of several nutrients and hydrographic conditions. At the beginning of the hypoxia event the water column had very low dissolved oxygen concentrations (oxygen minimum zone from the Humboldt Current System. Redox, pH, nitrate, phosphate, silicate and chlorophyll-a values were the lowest, while nitrate and the phaeopigment values were the highest. The N:P ratio was below 16, and the abundance of nano- and microphytoplankton were at their lowest, the latter also with the lowest proportion of live organisms. Macrozooplankton had the greatest abundance during hypoxia, dominated mainly by crustacean, fish eggs and amphipods. The hypoxia event generated a strong short-term alteration of all biotic and abiotic components of the pelagic system in Coliumo Bay and the neighboring coastal zone. These negative effects associated with strong natural hypoxia events could have important consequences for the productivity and ecosystem functioning of the coastal zone of the Humboldt Current System if, as suggested by several models, winds favorable to upwelling should increase due to climate change. The effects of natural hypoxia in this coastal zone can be dramatic especially for pelagic and benthic species not adapted to endure conditions of low dissolved oxygen. PMID:28715447

  11. Occurrence and levels of glyphosate and AMPA in shallow lakes from the Pampean and Patagonian regions of Argentina.

    Science.gov (United States)

    Castro Berman, M; Marino, D J G; Quiroga, María Victoria; Zagarese, Horacio

    2018-06-01

    Glyphosate (N-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide used to kill weeds that compete with commercial crops. In Argentina, the use of glyphosate-based herbicides increased dramatically (up to ∼200,000 tons on 2012) since the introduction of glyphosate-resistant crops, such as transgenic soy and resistant corn, and the adoption of non-till practices in the 1990's. Sallow lakes within the Pampa region may be potentially impacted by continuous herbicide usage. We surveyed 52 shallow lakes from the Pampa region (Buenos Aires Province, Argentina) to assess the occurrence and concentrations of glyphosate and its main degradation product (AMPA). For comparison, we also sampled 24 shallow lakes from an area with no agricultural use of glyphosate (Northern Patagonia). Glyphosate and AMPA were analyzed by UPLC-MS/MS ESI (±) in lake water, suspended particulate matter (SPM), and sediment samples. Within the Pampa region, glyphosate residues were detected in >40% of samples. Glyphosate residues were detected more frequently in sediment and surface water than in SPM samples. The mean (maximum) concentrations of glyphosate were 2.11 (4.52) μg l -1 for surface water; 0.10 (0.13) μg l -1 for SPM and 10.47 (20.34) μg kg -1 for sediment samples, respectively. Whereas, mean (maximum) concentrations of AMPA were 0.84 and (0.90) μg l -1 for surface water; 0.07 (0.07) μg l -1 for SPM; and 22.53 (32.89) μg kg -1 for sediment samples. The herbicide was not detected in samples from the Patagonian region. To our knowledge, this is the first study reporting the occurrence and concentrations of the herbicide in freshwater lakes of Argentina. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. High-frequency CSMT (HFCSMT) survey system for fine resistivity structures in the shallow subsurface; Hyoso hiteiko seimitsu sokutei sochi (HFCSMT) no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Handa, S [Saga University, Saga (Japan); Kinoshita, T; Kozato, T [Construction Project Consultant Co. Ltd., Osaka (Japan)

    1997-10-22

    HFCSMT system has been developed to enhance resolution in CSMT technology. The system covers a frequency band of 1.4kHz-106kHz for transmission, and measurement is performed using 16 frequencies. The transmitter power amplifier operating on a 12V cell is capable of a maximum output of approximately 3A, and the signals can be received at points several 100s of meters away. As for the selection of frequencies, synchronization is ensured for the receiver set no matter what instant the measuring process is commenced, the process being fully automated including the gain control. Phase and amplification values obtained for the electric and magnetic fields are subjected to A/D conversion. The data are stored in the microcomputer memory as apparent resistivity and phase data, and are forwarded to the host computer upon termination of the measuring process. Since both analog processing and digital processing are used, the measurement process is over in approximately 96 seconds. This system is being tested in various fields of technology. 1 fig.

  13. Nanodiamond finding in the hyblean shallow mantle xenoliths.

    Science.gov (United States)

    Simakov, S K; Kouchi, A; Mel'nik, N N; Scribano, V; Kimura, Y; Hama, T; Suzuki, N; Saito, H; Yoshizawa, T

    2015-06-01

    Most of Earth's diamonds are connected with deep-seated mantle rocks; however, in recent years, μm-sized diamonds have been found in shallower metamorphic rocks, and the process of shallow-seated diamond formation has become a hotly debated topic. Nanodiamonds occur mainly in chondrite meteorites associated with organic matter and water. They can be synthesized in the stability field of graphite from organic compounds under hydrothermal conditions. Similar physicochemical conditions occur in serpentinite-hosted hydrothermal systems. Herein, we report the first finding of nanodiamonds, primarily of 6 and 10 nm, in Hyblean asphaltene-bearing serpentinite xenoliths (Sicily, Italy). The discovery was made by electron microscopy observations coupled with Raman spectroscopy analyses. The finding reveals new aspects of carbon speciation and diamond formation in shallow crustal settings. Nanodiamonds can grow during the hydrothermal alteration of ultramafic rocks, as well as during the lithogenesis of sediments bearing organic matter.

  14. Effects of carbohydrate source for maintaining a high C:N ratio and fish driven re-suspension on pond ecology and production in periphyton-based freshwater prawn culture systems

    NARCIS (Netherlands)

    Asaduzzaman, M.; Wahab, M.A.; Verdegem, M.C.J.; Adhikary, R.K.; Rahman, S.M.S.; Azim, M.E.; Verreth, J.A.J.

    2010-01-01

    The present research investigated the effect of carbohydrate (CH) source for maintaining a high C:N ratio, and tilapia driven bioturbation on pond ecology, production and economical performances in C/N controlled periphyton-based (C/N-CP) freshwater prawn ponds. Two carbohydrate sources (high-cost

  15. Comparative economic performance and carbon footprint of two farming models for producing atlantic salmon (salmo salar): Land-based closed containment system in freshwater and open pen in seawater

    Science.gov (United States)

    Ocean net pen production of Atlantic salmon is approaching 2 million metric tons (MT) annually and has proven to be cost- and energy- efficient. Recently, with technology improvements, freshwater aquaculture of Atlantic salmon from eggs to harvestable size of 4 -5 kg in land-based closed containmen...

  16. Bifurcations of optimal vector fields in the shallow lake model

    NARCIS (Netherlands)

    Kiseleva, T.; Wagener, F.O.O.

    2010-01-01

    The solution structure of the set of optimal solutions of the shallow lake problem, a problem of optimal pollution management, is studied as we vary the values of the system parameters: the natural resilience, the relative importance of the resource for social welfare and the future discount rate.

  17. Bifurcations of optimal vector fields in the shallow lake model

    NARCIS (Netherlands)

    Kiseleva, T.; Wagener, F.

    2009-01-01

    The solution structure of the set of optimal solutions of the shallow lake problem, a problem of optimal pollution management, is studied as we vary the values of the system parameters: the natural resilience, the relative importance of the resource for social welfare and the future discount rate.

  18. Identifying bio-physical, social and political challenges to catchment governance for sustainable freshwater fisheries in West Africa: Systems overview through scenario development in the SUSFISH project.

    Science.gov (United States)

    Sendzimir, Jan; Slezak, Gabriele; Melcher, Andreas

    2015-04-01

    Chronic and episodic water scarcity prompted construction of 1400 reservoirs in Burkina Faso since 1950, greatly expanding fisheries production. These fisheries provided an increasingly important protein source for a population that has risen 600% since 1920, but production has plateaued, and dramatic declines in adult fish size suggest these fisheries are not sustainable. The SUSFISH project joined Austrian and Burkinabe scientists to increase local capacities to manage fisheries sustainably. SUSFISH has successfully increased capacity to monitor fish populations, identify endangered species, and use specific fish and macroinvertebrate species as bio-indicators of water and habitat quality as well as anthropogenic pressures. But projects to support sustainable development in Africa have a long history of failure if only based on transfer of technology and theory based on bio-physical sciences. This paper describes the processes and products of knowledge elicitation, scenario development and systems analysis to identify barriers and bridges to long-term sustainable fisheries development that arise from bio-physical, social, political and cultural causes, and, especially, interactions between them. Lessons learned and important on-going research questions are identified for both the natural and social sciences as they apply to managing catchments at multiple scales of governance, from local to national.

  19. Steady flow in shallow channel bends

    OpenAIRE

    De Vriend, H.J.

    1981-01-01

    Making use of a mathematical model solving the complete NavierStokes equations for steady flow in coiled rectangular pipes, fully-developed laminar flow in shallow curved channels is analysed physically and mathematically. Transverse convection of momentum by the secondary flow is shown to cause important deformations of the main velocity distribution. The model is also used to investigate simplified computation methods for shallow channels. The usual 'shallow water approximation' is shown to...

  20. Comparison of Shallow Survey 2012 Multibeam Datasets

    Science.gov (United States)

    Ramirez, T. M.

    2012-12-01

    The purpose of the Shallow Survey common dataset is a comparison of the different technologies utilized for data acquisition in the shallow survey marine environment. The common dataset consists of a series of surveys conducted over a common area of seabed using a variety of systems. It provides equipment manufacturers the opportunity to showcase their latest systems while giving hydrographic researchers and scientists a chance to test their latest algorithms on the dataset so that rigorous comparisons can be made. Five companies collected data for the Common Dataset in the Wellington Harbor area in New Zealand between May 2010 and May 2011; including Kongsberg, Reson, R2Sonic, GeoAcoustics, and Applied Acoustics. The Wellington harbor and surrounding coastal area was selected since it has a number of well-defined features, including the HMNZS South Seas and HMNZS Wellington wrecks, an armored seawall constructed of Tetrapods and Akmons, aquifers, wharves and marinas. The seabed inside the harbor basin is largely fine-grained sediment, with gravel and reefs around the coast. The area outside the harbor on the southern coast is an active environment, with moving sand and exposed reefs. A marine reserve is also in this area. For consistency between datasets, the coastal research vessel R/V Ikatere and crew were used for all surveys conducted for the common dataset. Using Triton's Perspective processing software multibeam datasets collected for the Shallow Survey were processed for detail analysis. Datasets from each sonar manufacturer were processed using the CUBE algorithm developed by the Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM/JHC). Each dataset was gridded at 0.5 and 1.0 meter resolutions for cross comparison and compliance with International Hydrographic Organization (IHO) requirements. Detailed comparisons were made of equipment specifications (transmit frequency, number of beams, beam width), data density, total uncertainty, and

  1. High organic inputs explain shallow and deep SOC storage in a long-term agroforestry system – combining experimental and modeling approaches

    Directory of Open Access Journals (Sweden)

    R. Cardinael

    2018-01-01

    Full Text Available Agroforestry is an increasingly popular farming system enabling agricultural diversification and providing several ecosystem services. In agroforestry systems, soil organic carbon (SOC stocks are generally increased, but it is difficult to disentangle the different factors responsible for this storage. Organic carbon (OC inputs to the soil may be larger, but SOC decomposition rates may be modified owing to microclimate, physical protection, or priming effect from roots, especially at depth. We used an 18-year-old silvoarable system associating hybrid walnut trees (Juglans regia  ×  nigra and durum wheat (Triticum turgidum L. subsp. durum and an adjacent agricultural control plot to quantify all OC inputs to the soil – leaf litter, tree fine root senescence, crop residues, and tree row herbaceous vegetation – and measured SOC stocks down to 2 m of depth at varying distances from the trees. We then proposed a model that simulates SOC dynamics in agroforestry accounting for both the whole soil profile and the lateral spatial heterogeneity. The model was calibrated to the control plot only. Measured OC inputs to soil were increased by about 40 % (+ 1.11 t C ha−1 yr−1 down to 2 m of depth in the agroforestry plot compared to the control, resulting in an additional SOC stock of 6.3 t C ha−1 down to 1 m of depth. However, most of the SOC storage occurred in the first 30 cm of soil and in the tree rows. The model was strongly validated, properly describing the measured SOC stocks and distribution with depth in agroforestry tree rows and alleys. It showed that the increased inputs of fresh biomass to soil explained the observed additional SOC storage in the agroforestry plot. Moreover, only a priming effect variant of the model was able to capture the depth distribution of SOC stocks, suggesting the priming effect as a possible mechanism driving deep SOC dynamics. This result questions the potential of soils to

  2. High organic inputs explain shallow and deep SOC storage in a long-term agroforestry system - combining experimental and modeling approaches

    Science.gov (United States)

    Cardinael, Rémi; Guenet, Bertrand; Chevallier, Tiphaine; Dupraz, Christian; Cozzi, Thomas; Chenu, Claire

    2018-01-01

    Agroforestry is an increasingly popular farming system enabling agricultural diversification and providing several ecosystem services. In agroforestry systems, soil organic carbon (SOC) stocks are generally increased, but it is difficult to disentangle the different factors responsible for this storage. Organic carbon (OC) inputs to the soil may be larger, but SOC decomposition rates may be modified owing to microclimate, physical protection, or priming effect from roots, especially at depth. We used an 18-year-old silvoarable system associating hybrid walnut trees (Juglans regia × nigra) and durum wheat (Triticum turgidum L. subsp. durum) and an adjacent agricultural control plot to quantify all OC inputs to the soil - leaf litter, tree fine root senescence, crop residues, and tree row herbaceous vegetation - and measured SOC stocks down to 2 m of depth at varying distances from the trees. We then proposed a model that simulates SOC dynamics in agroforestry accounting for both the whole soil profile and the lateral spatial heterogeneity. The model was calibrated to the control plot only. Measured OC inputs to soil were increased by about 40 % (+ 1.11 t C ha-1 yr-1) down to 2 m of depth in the agroforestry plot compared to the control, resulting in an additional SOC stock of 6.3 t C ha-1 down to 1 m of depth. However, most of the SOC storage occurred in the first 30 cm of soil and in the tree rows. The model was strongly validated, properly describing the measured SOC stocks and distribution with depth in agroforestry tree rows and alleys. It showed that the increased inputs of fresh biomass to soil explained the observed additional SOC storage in the agroforestry plot. Moreover, only a priming effect variant of the model was able to capture the depth distribution of SOC stocks, suggesting the priming effect as a possible mechanism driving deep SOC dynamics. This result questions the potential of soils to store large amounts of carbon, especially at depth. Deep

  3. Shallow-land-burial handbook

    International Nuclear Information System (INIS)

    Boegly, W.J. Jr.; Davis, E.C.

    1981-01-01

    The initial draft of the Shallow-Land Burial Handbook has been prepared and submitted to the DOE Low-Level Waste Management Program for review and comment. The Handbook informs the reader of the current way in which low-level wastes are being handled, outlines the legal and institutional problems that would be involved in developing and licensing such a facility, and describes in some detail the considerations and data needs for siting, designing, operating, and closing such a facility. The initial draft is not a Handbook that provides answers to all questions, nor insures that following the steps detailed in the Handbook guarantees that the facility will be licensed. It does illustrate the types of actions that must be considered and the types of information required to achieve successful operations

  4. Combined ecological risks of nitrogen and phosphorus in European freshwaters

    International Nuclear Information System (INIS)

    Azevedo, Ligia B.; Zelm, Rosalie van; Leuven, Rob S.E.W.; Hendriks, A. Jan; Huijbregts, Mark A.J.

    2015-01-01

    Eutrophication is a key water quality issue triggered by increasing nitrogen (N) and phosphorus (P) levels and potentially posing risks to freshwater biota. We predicted the probability that an invertebrate species within a community assemblage becomes absent due to nutrient stress as the ecological risk (ER) for European lakes and streams subjected to N and P pollution from 1985 to 2011. The ER was calculated as a function of species-specific tolerances to NO 3 − and total P concentrations and water quality monitoring data. Lake and stream ER averaged 50% in the last monitored year (i.e. 2011) and we observed a decrease by 22% and 38% in lake and stream ER (respectively) of river basins since 1985. Additionally, the ER from N stress surpassed that of P in both freshwater systems. The ER can be applied to identify river basins most subjected to eutrophication risks and the main drivers of impacts. - Highlights: • Ecological risk was estimated as response additions of N and P. • The risk posed by N stress is higher than that by P in European freshwaters. • Ecological risks have remained unchanged in most European river basins. - Quantifying the ecological risk of invertebrate losses due to N and P pollution

  5. INVESTIGATION ON BIODIVERSITY AND CONSERVATION OF FRESHWATER FISHES IN INDONESIA

    Directory of Open Access Journals (Sweden)

    Sudarto Sudarto

    2012-12-01

    Full Text Available Indonesia is one of the richest regions in the world in terms of biodiversity. However, recent evidence has shown that tropical forests destruction has maintained at a high rate over the last few years in this country. At the same time, living resources in Indonesian freshwater ecosystems are important: this country ranks at number seven in terms of production of inland capture fisheries with 323,150 tonnes in 2008. Freshwater fishes represent 42% of the total estimated ichthyofauna, concentrated in 0.01% of the total water covered environment. This environment is closer to human activities, making it critically vulnerable to adverse impacts. Furthermore, there has been some recent debates on the general sustainability of fisheries and aquaculture production systems. This research was focused on initiating a multi-scale study of fish biodiversity in freshwater environments. Two specific actions have been started. A review based on the analyses of the existing scientific literature and of databases on fish taxonomy and distributions. In parallel to this work, a global analysis of the distribution of fish diversity in Indonesia was undertaken. This work aims at identifying the major features of this resource as well as its current and future threats.

  6. Magnetic resonance imaging of live freshwater mussels (Unionidae)

    Science.gov (United States)

    Michael, Holliman F.; Davis, Denise; Bogan, Arthur E.; Kwak, Thomas J.; Cope, W. Gregory; Levine, Jay F.

    2008-01-01

    We examined the soft tissues of live freshwater mussels, Eastern elliptio Elliptio complanata, via magnetic resonance imaging (MRI), acquiring data with a widely available human whole-body MRI system. Anatomical features depicted in the profile images included the foot, stomach, intestine, anterior and posterior adductor muscles, and pericardial cavity. Noteworthy observations on soft tissue morphology included a concentration of lipids at the most posterior aspect of the foot, the presence of hemolymph-filled fissures in the posterior adductor muscle, the presence of a relatively large hemolymph-filled sinus adjacent to the posterior adductor muscle (at the ventral-anterior aspect), and segmentation of the intestine (a diagnostic description not reported previously in Unionidae). Relatively little is known about the basic biology and ecological physiology of freshwater mussels. Traditional approaches for studying anatomy and tissue processes, and for measuring sub-lethal physiological stress, are destructive or invasive. Our study, the first to evaluate freshwater mussel soft tissues by MRI, clarifies the body plan of unionid mussels and demonstrates the efficacy of this technology for in vivoevaluation of the structure, function, and integrity of mussel soft tissues.

  7. Effects of salinity on freshwater fishes in coastal plain drainages in the southeastern U.S.

    Science.gov (United States)

    Peterson, Mark S.; Meador, Michael R.

    1994-01-01

    This review focuses on the influence of salinity on freshwater fishes in coastal rivers and estuaries of the southeastern U.S. Influences of salinity on freshwater fish species can be explained partly through responses evidenced by behavior, physiology, growth, reproduction, and food habits during all aspects of life history. Factors influencing the rate of salinity change affect the community structure and dynamics of freshwater fishes in brackish environments. Our understanding of the relation between salinity and the life history of freshwater fishes is limited because little ecological research has been conducted in low-salinity habitats that we consider an “interface” between freshwater streams and the estuary proper. Much of the available data are descriptive in nature and describe best general patterns, but more specific studies are required to better determine the influence of salinity on freshwater fishes. Improved understanding of the influence of human-induced changes on the productivity and viability of these important systems will require a new research focus.

  8. Longevity of shallow subsurface drip irrigation tubing under three tillage practices

    Science.gov (United States)

    Shallow Sub-Surface drip irrigation (S3DI) has drip tubing buried about 2-in below the soil surface. It is unknown how long drip tubing would be viable at this shallow soil depth using strip- or no-tillage systems. The objectives were to determine drip tube longevity, resultant crop yield, and parti...

  9. Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system.

    Science.gov (United States)

    Calosi, Piero; Rastrick, Samuel P S; Lombardi, Chiara; de Guzman, Heidi J; Davidson, Laura; Jahnke, Marlene; Giangrande, Adriana; Hardege, Jörg D; Schulze, Anja; Spicer, John I; Gambi, Maria-Cristina

    2013-01-01

    Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO2. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO2, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO2. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification.

  10. The Marianas-San Marcos vein system: characteristics of a shallow low sulfidation epithermal Au-Ag deposit in the Cerro Negro district, Deseado Massif, Patagonia, Argentina

    Science.gov (United States)

    Vidal, Conrado Permuy; Guido, Diego M.; Jovic, Sebastián M.; Bodnar, Robert J.; Moncada, Daniel; Melgarejo, Joan Carles; Hames, Willis

    2016-08-01

    The Cerro Negro district, within the Argentinian Deseado Massif province, has become one of the most significant recent epithermal discoveries, with estimated reserves plus resources of ˜6.7 Moz Au equivalent. The Marianas-San Marcos vein system contains about 70 % of the Au-Ag resources in the district. Mineralization consists of Upper Jurassic (155 Ma) epithermal Au- and Ag-rich veins of low to intermediate sulfidation style, hosted in and genetically related to Jurassic intermediate composition volcanic rocks (159-156 Ma). Veins have a complex infill history, represented by ten stages with clear crosscutting relationships that can be summarized in four main episodes: a low volume, metal-rich initial episode (E1), an extended banded quartz episode with minor mineralization (E2), a barren waning stage episode (E3), and a silver-rich late tectonic-hydrothermal episode (E4). The first three episodes are interpreted to have formed at the same time and probably from fluids of similar composition: a 290-230 °C fluid dominated by meteoric and volcanic waters (-3‰ to -0‰ δ18Owater), with geothermal features. The last tectonic-hydrothermal mineralization episode (E4), interpreted to have formed at lower temperatures, could be related to this late tectonic and hydrothermal activity.

  11. 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

  12. Physical processes and sedimentation on a broad, shallow bank

    Science.gov (United States)

    Murray, S. P.; Hsu, S. A.; Roberts, H. H.; Owens, E. H.; Crout, R. L.

    1982-02-01

    An integrated study of the meteorology, physical oceanography, sedimentationand coastal morphology on the broad, shallow Miskito Bank off the eastern coast of Nicaragua has uncovered systematic interrelationships between driving forces. Bank geometry and sedimentologic environments on the Bank. Extremely high rainfall results from an interaction between meteorological processes over the Bank and topographic effects along the coast. Both acoustic and radio sounding of the lower atmosphere have documented the feedback between convective plumes, inversion layers and the incessant rainfall, which brings three times more freshwater and 15 times more sediment down to a unit length of coast than on the U.S. Atlantic shore. The resultant brackish, turbid coastal water moves as a highly organized band of water parallel to the coast. Seaward of this coastal boundary layer, offshore water from the Caribbean Current rides up on the Bank and provides an environment ideal for carbonate production. A zone of fine-grained terrigenous sediment underlying the coastal boundary current merges abruptly into a smooth carbonate plain covering most of the surface of the Bank. These central Bank carbonates are composed primarily of the disintegration products of prolific calcareous green algae. A trend of high relief, luxuriant coral reef growth is aligned along the steep dropoff at the Bank edge, a zone of observed upwelling of cooler and saltier basin water. A threefold southerly increase in wave energy at the shoreline due to the decreasing width of the shallow shelf results in wave-dominated coastal morphologies in the south compared to fluvial domination in the north and a systematic change from straight, linear bars and beaches in the north to rhythmic topography in the south.

  13. Shallow rainwater lenses in deltaic areas with saline seepage

    Directory of Open Access Journals (Sweden)

    P. G. B. de Louw

    2011-12-01

    Full Text Available In deltaic areas with saline seepage, freshwater availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence and size. Our findings are based on different types of field measurements and detailed numerical groundwater models applied in the south-western delta of the Netherlands. By combining the applied techniques we could extrapolate measurements at point scale (groundwater sampling, temperature and electrical soil conductivity (TEC-probe measurements, electrical cone penetration tests (ECPT to field scale (continuous vertical electrical soundings (CVES, electromagnetic survey with EM31, and even to regional scale using helicopter-borne electromagnetic measurements (HEM. The measurements show a gradual mixing zone between infiltrating fresh rainwater and upward flowing saline groundwater. The mixing zone is best characterized by the depth of the centre of the mixing zone Dmix, where the salinity is half that of seepage water, and the bottom of the mixing zone Bmix, with a salinity equal to that of the seepage water (Cl-conc. 10 to 16 g l−1. Dmix is found at very shallow depth in the confining top layer, on average at 1.7 m below ground level (b.g.l., while Bmix lies about 2.5 m b.g.l. The model results show that the constantly alternating upward and downward flow at low velocities in the confining layer is the main mechanism of mixing between rainwater and saline seepage and determines the position and extent of the mixing zone (Dmix and Bmix. Recharge, seepage flux, and drainage depth are the controlling factors.

  14. Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers.

    Science.gov (United States)

    Little, Mark G; Jackson, Robert B

    2010-12-01

    Carbon Capture and Storage may use deep saline aquifers for CO(2) sequestration, but small CO(2) leakage could pose a risk to overlying fresh groundwater. We performed laboratory incubations of CO(2) infiltration under oxidizing conditions for >300 days on samples from four freshwater aquifers to 1) understand how CO(2) leakage affects freshwater quality; 2) develop selection criteria for deep sequestration sites based on inorganic metal contamination caused by CO(2) leaks to shallow aquifers; and 3) identify geochemical signatures for early detection criteria. After exposure to CO(2), water pH declines of 1-2 units were apparent in all aquifer samples. CO(2) caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude. Potentially dangerous uranium and barium increased throughout the entire experiment in some samples. Solid-phase metal mobility, carbonate buffering capacity, and redox state in the shallow overlying aquifers influence the impact of CO(2) leakage and should be considered when selecting deep geosequestration sites. Manganese, iron, calcium, and pH could be used as geochemical markers of a CO(2) leak, as their concentrations increase within 2 weeks of exposure to CO(2).

  15. Environmental influence on cyanobacteria abundance and microcystin toxin production in a shallow temperate lake.

    Science.gov (United States)

    Lee, Tammy A; Rollwagen-Bollens, Gretchen; Bollens, Stephen M; Faber-Hammond, Joshua J

    2015-04-01

    The increasing frequency of harmful cyanobacterial blooms in freshwater systems is a commonly recognized problem due to detrimental effects on water quality. Vancouver Lake, a shallow, tidally influenced lake in the flood plain of the Columbia River within the city of Vancouver, WA, USA, has experienced numerous summertime cyanobacterial blooms, dominated by Aphanizomenon sp. and Anabaena sp. Cyanobacteria abundance and toxin (microcystin) levels have been monitored in this popular urban lake for several years; however, no previous studies have identified which cyanobacteria species produce toxins, nor analyzed how changes in environmental variables contribute to the fluctuations in toxic cyanobacteria populations. We used a suite of molecular techniques to analyze water samples from Vancouver Lake over two summer bloom cycles (2009 and 2010). Both intracellular and extracellular microcystin concentrations were measured using an ELISA kit. Intracellular microcystin concentrations exceeded WHO guidelines for recreational waters several times throughout the sampling period. PCR results demonstrated that Microcystis sp. was the sole microcystin-producing cyanobacteria species present in Vancouver Lake, although Microcystis sp. was rarely detected in microscopical counts. qPCR results indicated that the majority of the Microcystis sp. population contained the toxin-producing gene (mcyE), although Microcystis sp. abundance rarely exceeded 1 percent of overall cyanobacteria abundance. Non-metric multidimensional scaling (NMDS) revealed that PO4-P was the main environmental variable influencing the abundance of toxic and non-toxic cyanobacteria, as well as intracellular microcystin concentrations. Our study underscores the importance of using molecular genetic techniques, in addition to traditional microscopy, to assess the importance of less conspicuous species in the dynamics of harmful algal blooms. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Shallow Water Optical Water Quality Buoy

    Science.gov (United States)

    Bostater, Charles

    1998-01-01

    This NASA grant was funded as a result of an unsolicited proposal submission to Kennedy Space Center. The proposal proposed the development and testing of a shallow water optical water quality buoy. The buoy is meant to work in shallow aquatic systems (ponds, rivers, lagoons, and semi-enclosed water areas where strong wind wave action is not a major environmental During the project period of three years, a demonstration of the buoy was conducted. The last demonstration during the project period was held in November, 1996 when the buoy was demonstrated as being totally operational with no tethered communications line. During the last year of the project the buoy was made to be solar operated by large gel cell batteries. Fund limitations did not permit the batteries in metal enclosures as hoped for higher wind conditions, however the system used to date has worked continuously for in- situ operation of over 18 months continuous deployment. The system needs to have maintenance and somewhat continuous operational attention since various components have limited lifetime ages. For example, within the last six months the onboard computer has had to be repaired as it did approximately 6 months after deployment. The spectrograph had to be repaired and costs for repairs was covered by KB Science since no ftmds were available for this purpose after the grant expired. Most recently the computer web page server failed and it is currently being repaired by KB Science. In addition, the cell phone operation is currently being ftmded by Dr. Bostater in order to maintain the system's operation. The above points need to be made to allow NASA to understand that like any sophisticated measuring system in a lab or in the field, necessary funding and maintenance is needed to insure the system's operational state and to obtain quality factor. The proposal stated that the project was based upon the integration of a proprietary and confidential sensor and probe design that was developed by

  17. Acoustic MIMO communications in a very shallow water channel

    Science.gov (United States)

    Zhou, Yuehai; Cao, Xiuling; Tong, Feng

    2015-12-01

    Underwater acoustic channels pose significant difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple input multiple output (MIMO) technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area (for example, a depth less than 10 m). In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers (DFE) is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.

  18. Hydrogeologic assessment of shallow clastic and carbonate rock aquifers in Hendry and Collier counties, southwestern Florida

    Science.gov (United States)

    Brown, C. Erwin; Krulikas, R.K.; Brendle, D.L.

    1996-01-01

    Direct-current electrical resistivity data were collected from 109 vertical electrical sounding sites in Hendry and Collier Counties, southwestern Florida. Selected direct-current electrical resistivity surveys, together with available borehole geologic and geophysical data, were used to determine the approximate areal extent of the shallow clastic aquifers composed of thick sands and carbonate lithologies. Results indicated that a complex pattern of shallow sands, clays, and carbonate lithologies occur throughout the area. Buried channel sands were found as deep as 50 meters below land surface in some places. The channels contain unconsolidated fine- to medium-grained quartz sand interbedded with sandy limestone, shell fragments, and gray-green sandy clay. Both surface and borehole geophysical techniques with lithologic data were necessary to approximately locate and define layers that might behave as confining layers and to locate and define the extent of any buried sand aquifers. The borehole geophysical data were used to analyze the zones of higher resistivity. Direct-current electrical resistivity data indicated the approximate location of certain layer boundaries. The conjunctive use of natural gamma and short- and long-normal resistivity logs was helpful in determining lithologic effects. Geohydrologic sections were prepared to identify potential locations of buried channels and carbonates containing freshwater. Buried channel sands and carbonate rock sections were identified in the subsurface that potentially may contain freshwater supplies.

  19. Analysis of data from test-well sites along the downdip limit of freshwater in the Edwards Aquifer, San Antonio, Texas, 1985-87

    Science.gov (United States)

    Groschen, G.E.

    1994-01-01

    Many researchers have studied the downdip limit of freshwater in the Edwards aquifer or various aspects of the saline-water zone and its relation to the freshwater zone. These studies were summarized and used to synthesize a consistent hydrologic and geochemical framework from which to interpret data from field studies. The concept derived from the previous work on the downdip limit of the freshwater zone is that fresh recharge water entered the aquifer and developed a vast flow system controlled by barrier faults. Some recharge water flows into the saline-water zone rather than toward major freshwater discharge points. The water that enters the salinewater zone continues to dissolve gypsum and dolomite, and calcite precipitates out of the water. This process of dedolomitization has helped to develop the large secondary porosity of the freshwater zone as the downdip limit of the freshwater zone progressively moved downdip in recent geologic time.

  20. Global imprint of historical connectivity on freshwater fish biodiversity.

    Science.gov (United States)

    Dias, Murilo S; Oberdorff, Thierry; Hugueny, Bernard; Leprieur, Fabien; Jézéquel, Céline; Cornu, Jean-François; Brosse, Sébastien; Grenouillet, Gael; Tedesco, Pablo A

    2014-09-01

    The relative importance of contemporary and historical processes is central for understanding biodiversity patterns. While several studies show that past conditions can partly explain the current biodiversity patterns, the role of history remains elusive. We reconstructed palaeo-drainage basins under lower sea level conditions (Last Glacial Maximum) to test whether the historical connectivity between basins left an imprint on the global patterns of freshwater fish biodiversity. After controlling for contemporary and past environmental conditions, we found that palaeo-connected basins displayed greater species richness but lower levels of endemism and beta diversity than did palaeo-disconnected basins. Palaeo-connected basins exhibited shallower distance decay of compositional similarity, suggesting that palaeo-river connections favoured the exchange of fish species. Finally, we found that a longer period of palaeo-connection resulted in lower levels of beta diversity. These findings reveal the first unambiguous results of the role played by history in explaining the global contemporary patterns of biodiversity. © 2014 John Wiley & Sons Ltd/CNRS.

  1. Sulfate reduction in freshwater peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Oequist, M.

    1996-12-31

    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{sub 4}{sup 2-} concentrations in the three profiles were of equal magnitude and ranged from 50 to 150 {mu}M. 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 {mu}M h{sup -1} while in B and C they were 1 and 0.05 {mu}M h{sup -1}, respectively. Methane production rates, however, were more uniform across the three nutrient regimes. Maximum rates in A (ca. 1.5 {mu}g d{sup -1} g{sup -1}) were found 10 cm below the water table, in B (ca. 1.0 {mu}g d{sup -1} g{sup -1}) in the vicinity of the water table, and in C (0.75 {mu}g d{sup -1} g{sup -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{sup -2} d{sup -1}, while the estimates for sulfate reduction were 26.4, 2.5, and 0.1 mmol m{sup -2} d{sup -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

  2. CROATIAN FRESHWATER FISHERIES IN 1997

    Directory of Open Access Journals (Sweden)

    Mirko Turk

    1998-10-01

    Full Text Available Data on the production and fish catch according to species, on the surface of the fish ponds, on the means of fish catching and on the distribution of the production and the catch in 1997 is presented. The surface area used for production of fish has decreased for 836 ha or 8.40%. The total fish amount was bigger for 477 tons, or 10,52%. The feeding coefficient is 2.6 kg decreased 35% for in comparison to the bigger compared to the previous year. The amount of the fertilizer used is bigger for 37.30%. The fry carp growing ponds make up 6.50% of the total fish pond surfaces, the young carp ponds 22.04/0, and the ponds with consumption fish 70.31%. The total amount in the carp ponds was 446 kg/ha, and in the trout ponds it was 160.8 tons/ha. The most produced fish species is the carp with 79.32%, followed by the trout with 11.50%, the herbivorous fish with 4.25%, while all the other fish species make up 4.93% of the entire production. In the structure of herbivorous fish the grass carp is leading with 69,23%, followed by the big head carp with 29.74% and the silver carp with 1.03%. Compared to the previous year the production of the carp, grass carp and tench is increased. Fish catch in open waters has decreased by 5.53% in comparison to the previous year. In the production and catch of the total freshwater fish, carp made up 75.34%, herbivorous fish made up 3.89%, trout 10.66%, sheat fish, pike perch and pike 2.70% and all other fish species 7.41%. As far as the distribution of production and catch of fish is concerned, 52,80% were sold on the market, 37.94% were used for reproduction (stocking the fish farms, mortality was 1.43%, and for personal use (sports fishing 7.83%. The number of fisheries workers has decreased for 8.17%, and the production per worker is bigger for 22.25%, compared to the previous year. Average production per worker was 7.17% tons of fish.

  3. CROATIAN FRESHWATER FISHERIES IN 1996.

    Directory of Open Access Journals (Sweden)

    Mirko Turk

    1997-07-01

    Full Text Available Data on the production and fish catch according to species, on the surface of the fish ponds, on the means of fish catching and on the distribution of the production and the catch in 1996 is presented. The surface area used for production of fish has decreased by 1357 ha or 11.99%. The total fish amount has decreased by 1,921.00 tons or 29.76%. The feeding coefficient is 4 kg (33.33% bigger compared to the previous year. The amount of the fertilizer used has decreased by 18.79%. The fry carp growing ponds make up 5.99% of the total fish pond surfaces, the young carp ponds 21.13%, and the ponds with consumption fish 71.53%. The total fish amount in the carp ponds was 376 kg/ha, and in the trout ponds it was 146.6 tons/ha. The most produced fish species is the carp with 82.21 %, followed by the trout with 8.57%, the herbivorous fish with 4.78%, while all the other fish species make up 4.44% of the entire production. In the structure of herbivorous fish the grass carp is leading with 64,28%, followed by the big head carp with 26.02% and the silver carp with 9.70%. Compared to the previous year the production of the trout and tench has somewhat increased, while the production of all the other species of fish has decreased. Fish catch in open waters has increased by 19.23% in comparison to the previous year. In the production and catch of the total freshwater fish, carp made up 77.46%, the herbivorous fish made up 4.32%, trout 4.32%, sheat fish, pike perch and pike 2.99% and all other fish species 7.36%. As far as the distribution of production and catch is concerned, 46.91% were sold on the market, 39.19% were used for reproduction (stocking the fish farms, mortalities were 6.23%, and for personal use (sports fishing 7.67% was used. The number of fisheries workers has decreased by 17.75%, and the production per worker has also decreased by 26.62%, compared to the previous year. Average production per worker was 5.87 tons of fish.

  4. 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

  5. Strategies towards an optimized use of the shallow geothermal potential

    Science.gov (United States)

    Schelenz, S.; Firmbach, L.; Kalbacher, T.; Goerke, U.; Kolditz, O.; Dietrich, P.; Vienken, T.

    2013-12-01

    Thermal use of the shallow subsurface for heat generation, cooling and thermal energy storage is increasingly gaining importance in reconsideration of future energy supplies, e.g. in the course of German energy transition, with application shifting from isolated to intensive use. The planning and dimensioning of (geo-)thermal applications is strongly influenced by the availability of exploration data. Hence, reliable site-specific dimensioning of systems for the thermal use of the shallow subsurface will contribute to an increase in resource efficiency, cost reduction during installation and operation, as well as reduction of environmental impacts and prevention of resource over-exploitation. Despite large cumulative investments that are being made for the utilization of the shallow thermal potential, thermal energy is in many cases exploited without prior on-site exploration and investigation of the local geothermal potential, due to the lack of adequate and cost-efficient exploration techniques. We will present new strategies for an optimized utilization of urban thermal potential, showcased at a currently developed residential neighborhood with high demand for shallow geothermal applications, based on a) enhanced site characterization and b) simulation of different site specific application scenarios. For enhanced site characterization, surface geophysics and vertical high resolution direct push-profiling were combined for reliable determination of aquifer structure and aquifer parameterization. Based on the site characterization, different site specific geothermal application scenarios, including different system types and system configurations, were simulated using OpenGeoSys to guarantee an environmental and economic sustainable thermal use of the shallow subsurface.

  6. Shallow Carbon Sequestration Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Pendergrass, Gary; Fraley, David; Alter, William; Bodenhamer, Steven

    2013-09-30

    The potential for carbon sequestration at relatively shallow depths was investigated at four power plant sites in Missouri. Exploratory boreholes were cored through the Davis Shale confining layer into the St. Francois aquifer (Lamotte Sandstone and Bonneterre Formation). Precambrian basement contact ranged from 654.4 meters at the John Twitty Energy Center in Southwest Missouri to over 1100 meters near the Sioux Power Plant in St. Charles County. Investigations at the John Twitty Energy Center included 3D seismic reflection surveys, downhole geophysical logging and pressure testing, and laboratory analysis of rock core and water samples. Plans to perform injectivity tests at the John Twitty Energy Center, using food grade CO{sub 2}, had to be abandoned when the isolated aquifer was found to have very low dissolved solids content. Investigations at the Sioux Plant and Thomas Hill Energy Center in Randolph County found suitably saline conditions in the St. Francois. A fourth borehole in Platte County was discontinued before reaching the aquifer. Laboratory analyses of rock core and water samples indicate that the St. Charles and Randolph County sites could have storage potentials worthy of further study. The report suggests additional Missouri areas for further investigation as well.

  7. 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...

  8. A physically based model of global freshwater surface temperature

    Science.gov (United States)

    van Beek, Ludovicus P. H.; Eikelboom, Tessa; van Vliet, Michelle T. H.; Bierkens, Marc F. P.

    2012-09-01

    Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through their tolerance to parasites and diseases. Models used to predict surface water temperature range between physically based deterministic models and statistical approaches. Here we present the initial results of a physically based deterministic model of global freshwater surface temperature. The model adds a surface water energy balance to river discharge modeled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff, and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by shortwave and longwave radiation and sensible and latent heat fluxes. Also included are ice formation and its effect on heat storage and river hydraulics. We use the coupled surface water and energy balance model to simulate global freshwater surface temperature at daily time steps with a spatial resolution of 0.5° on a regular grid for the period 1976-2000. We opt to parameterize the model with globally available data and apply it without calibration in order to preserve its physical basis with the outlook of evaluating the effects of atmospheric warming on freshwater surface temperature. We validate our simulation results with daily temperature data from rivers and lakes (U.S. Geological Survey (USGS), limited to the USA) and compare mean monthly temperatures with those recorded in the Global Environment Monitoring System (GEMS) data set. Results show that the model is able to capture the mean monthly surface temperature for the majority of the GEMS stations, while the interannual variability as derived from the USGS and NOAA data was captured reasonably well. Results are poorest for

  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. Source, Use, and Disposition of Freshwater in Puerto Rico, 2005

    Science.gov (United States)

    Molina-Rivera, Wanda L.

    2010-01-01

    Water diverted from streams and pumped from wells constitutes the main sources of water for the 78 municipios of the Commonwealth of Puerto Rico. A better understanding is needed about water-use patterns, particularly about the amount of water used, where and how this water is used and disposed, and how human activities impact water resources. Irrigation practices, indoor and outdoor household uses, industrial uses, and commercial and mining withdrawals affect reservoirs, streams, and aquifers. Accurate and accessible water information for Puerto Rico is critical to ensure that water managers have the ability to protect and conserve this natural resource. The population of Puerto Rico increased 15 percent, from 3.4 million in 1985 to 3.9 million people 2005 and resulted in an increased demand for freshwater, mostly for the public-supply water use category. Almost 99 percent of the residents in Puerto Rico were served by public-supply water systems in 2005. One of the major challenges that water managers confront is the need to provide sufficient freshwater availability in the densely populated areas. Public-supply water is provided by the Puerto Rico Aqueducts and Sewers Authority (PRASA) and by non-PRASA systems. Non-PRASA systems refer to community-operated water systems (water systems that serve a rural or suburban housing area).

  11. 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....

  12. Predicting freshwater habitat integrity using land-use surrogates

    CSIR Research Space (South Africa)

    Amis, MA

    2007-04-01

    Full Text Available Freshwater biodiversity is globally threatened due to human disturbances, but freshwater ecosystems have been accorded less protection than their terrestrial and marine counterparts. Few criteria exist for assessing the habitat integrity of rivers...

  13. 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

  14. Organic carbon input in shallow groundwater at Aspo, southeastern Sweden

    International Nuclear Information System (INIS)

    Wallin, B.

    1993-01-01

    The variation in carbon and oxygen isotopes in calcite fissure fillings and dissolved carbonate from shallow groundwaters has been examined at Aspo, southeastern Sweden. The shallow water lens is refilled by meteoric water and is considered as an open system. The σ 13 C-signatures of the dissolved carbonate fall within a narrow range of -15.8 to -17.4 per-thousand, indicative of organic an organic carbon source. The low σ 13 C-values suggest that input of soil-CO 2 is the dominating carbon source for the system. σ 13 C and σ 18 O-values in the calcite fissure fillings show a wide range in values with a possible two end-member mixing of early post glacial atmospheric CO 2 dominated system to a present day soil-CO 2 dominating carbon source

  15. Geomorphological mapping of shallow landslides using UAVs

    Science.gov (United States)

    Fiorucci, Federica; Giordan, Daniele; Dutto, Furio; Rossi, Mauro; Guzzetti, Fausto

    2015-04-01

    The mapping of event shallow landslides is a critical activity, due to the large number of phenomena, mostly with small dimension, affecting extensive areas. This is commonly done through aerial photo-interpretation or through field surveys. Nowadays, landslide maps can be realized exploiting other methods/technologies: (i) airborne LiDARs, (ii) stereoscopic satellite images, and (iii) unmanned aerial vehicles (UAVs). In addition to the landslide maps, these methods/technologies allow the generation of updated Digital Terrain Models (DTM). In December 2013, in the Collazzone area (Umbria, Central Italy), an intense rainfall event triggered a large number of shallow landslides. To map the landslides occurred in the area, we exploited data and images obtained through (A) an airborne LiDAR survey, (B) a remote controlled optocopter (equipped with a Canon EOS M) survey, and (C) a stereoscopic satellite WorldView II MS. To evaluate the mapping accuracy of these methods, we select two landslides and we mapped them using a GPS RTK instrumentation. We consider the GPS survey as the benchmark being the most accurate system. The results of the comparison allow to highlight pros and cons of the methods/technologies used. LiDAR can be considered the most accurate system and in addition it allows the extraction and the classification of the digital surface models from the surveyed point cloud. Conversely, LiDAR requires additional time for the flight planning, and specific data analysis user capabilities. The analysis of the satellite WorldView II MS images facilitates the landslide mapping over large areas, but at the expenses of a minor resolution to detect the smaller landslides and their boundaries. UAVs can be considered the cheapest and fastest solution for the acquisition of high resolution ortho-photographs on limited areas, and the best solution for a multi-temporal analysis of specific landslide phenomena. Limitations are due to (i) the needs of optimal climatic

  16. Shallow land burial technology: humid

    International Nuclear Information System (INIS)

    Davis, E.C.; Yeh, G.T.

    1984-01-01

    Applying engineered modifications to present shallow land burial (SLB) practices is one method of ensuring safe operation and improving overall disposal-site performance. Two such engineered modifications, trench lining and grouting, are being demonstrated and evaluated at the Oak Ridge National Laboratory (ORNL) Engineered Test Facility (ETF), using nine 28-m 3 experimental trenches containing compacted low-level waste (LLW). Concurrent to this field demonstration experiment, two finite-element hydrologic models have been developed to model water movement and solute transport at a waste disposal site. This paper covers progress made in these two areas during FY 1984. Though the economic analysis of the two trench treatments favored Hypalon lining (lining costs were 33% lower at this demonstration scale), results of field experiments examining waste hydrologic isolation favored the cement-bentonite grout treatment. Data from water pump-out and water pump-in tests, combined with observed intratrench water-level fluctuations, suggest that the original goal of constructing watertight liners in three experimental trenches was not achieved. In addition, trench-cover subsidence of approx. 2% of the total trench depth has been measured over two of the three lined trenches but has not occurred over any of the three grouted or three control (untreated) trenches. The evaluation of the two trench treatments is continuing. However, results indicate that the cement-bentonite treatment, implemented at a cost of $160/m 3 of grout, provides a degree of waste isolation not afforded by the lined and control trenches and should be considered for use at SLB sites with water-related problems. 11 references, 6 figures, 2 tables

  17. Shallow Land Burial Technology - Humid

    International Nuclear Information System (INIS)

    Davis, E.C.; Spalding, B.P.; Lee, S.Y.

    1983-01-01

    The Shallow Land Burial Technology - Humid Project is being conducted for the Department of Energy Low-Level Waste Management Program with the objective of identifying and demonstrating improved technology for disposing of low-level solid waste in humid environments. Two improved disposal techniques are currently being evaluated using nine demonstration trenches at the Engineered Test Facility (ETF). The first is use of a cement-bentonite grout applied as a waste backfill material prior to trench closure and covering. The second is complete hydrologic isolation of waste by emplacement in a trench that is lined on all four sides, top and bottom using synthetic impermeable lining material. An economic analysis of the trench grouting and lining demonstration favored the trench lining operation ($1055/demonstration trench) over trench grouting ($1585/demonstration trench), with the cost differential becoming even greater (as much as a factor of 6 in favor of lining for typical ORNL trenches) as trench dimensions increase and trench volumes exceed those of the demonstration trenches. In addition to the evaluation of trench grouting and lining, major effort has centered on characterization of the ETF site. Though only a part of the overall study, characterization is an extremely important component of the site selection process; it is during these activities that potential problems, which may obviate the site from further consideration, are found. Characterization of the ETF has included studies of regional and site-specific geology, the physical and chemical properties of the soils in which the demonstration trenches are located, and hydrology of the small watershed of which the ETF is a part. 12 references, 6 figures, 2 tables

  18. CROATIAN FRESHWATER FISHERIES IN 1994

    Directory of Open Access Journals (Sweden)

    Mirko Turk

    1995-09-01

    Full Text Available Data on the production and catch of fish according to species, on the surface of the fish ponds, on the means of fish catching and on the distribution of the product and catch in 1994 is presented. The surface area used for production of fish has decreased by 274 ha or 2,51%. The total amount of fish has decreased by 1.263 tons or 14,78%. The highest production of fish was reached by the fish farm Donji Miholjac with 1.231 kg/ha. The feeding coefficient is 3,10 kg. Only on one fish farm was the feeding coefficient less than 2.0 kg (1,40 and on two large farms this coefficient was greater than 5,00 kg. The main fish food is still wheat followed by corn. The amount of fertilizer used was decreased by 14,40%. The fry carp growing ponds make up 0,92% of the surface area of the entire fish farm, the young carp ponds 21,77% and the culturing ponds for consumption fish 76,55%. The total amount of fish in the carp ponds was 660 kg/ha, and in the trout ponds it was 123.4 tons/ha. The carp is the highest produced fish with 80, 35%, then the herbivorous fish with 5,65 and all other fish make up 14% of the total production. In the structure of herbivorous fish the grass carp is leading with 54, 70%, followed by the big head carp with 25,54% and the silver carp with 19,76%. In comparison with the previous year the production of "all other fish- has significantly increased (287%, and sheat fish 18,90%, while the production of trench has decreased (71%. Fish catch in open waters has increased by 20,57% in comparison to the previous year. Carp made up 78,07% of the total production and catch of freshwater fish, the herbivorous fish made up 5,40%, trout 4,38%, the sheat fish, pike perch and pike 2,86% and all other fish species 9,28%. As far as the distribution of production and catch, 51,60% were sold on the market, 37,54% were used for reproduction (stocking the fish farms , mortalities were 6,35% and for personal use (sports fishing 4,50% was used. The number

  19. Improved protocols to accelerate the assembly of DNA barcode reference libraries for freshwater zooplankton.

    Science.gov (United States)

    Elías-Gutiérrez, Manuel; Valdez-Moreno, Martha; Topan, Janet; Young, Monica R; Cohuo-Colli, José Angel

    2018-03-01

    Currently, freshwater zooplankton sampling and identification methodologies have remained virtually unchanged since they were first established in the beginning of the XX century. One major contributing factor to this slow progress is the limited success of modern genetic methodologies, such as DNA barcoding, in several of the main groups. This study demonstrates improved protocols which enable the rapid assessment of most animal taxa inhabiting any freshwater system by combining the use of light traps, careful fixation at low temperatures using ethanol, and zooplankton-specific primers. We DNA-barcoded 2,136 specimens from a diverse array of taxonomic assemblages (rotifers, mollusks, mites, crustaceans, insects, and fishes) from several Canadian and Mexican lakes with an average sequence success rate of 85.3%. In total, 325 Barcode Index Numbers (BINs) were detected with only three BINs (two cladocerans and one copepod) shared between Canada and Mexico, suggesting a much narrower distribution range of freshwater zooplankton than previously thought. This study is the first to broadly explore the metazoan biodiversity of freshwater systems with DNA barcodes to construct a reference library that represents the first step for future programs which aim to monitor ecosystem health, track invasive species, or improve knowledge of the ecology and distribution of freshwater zooplankton.

  20. Environmental isotope signatures of the largest freshwater lake in Kerala

    International Nuclear Information System (INIS)

    Unnikrishnan Warrier, C.

    2007-01-01

    Sasthamkotta lake, the largest freshwater lake in Kerala, serves as a source for drinking water for more than half a million people. Environmental 137 Cs analysis done on undisturbed sediment core samples reveals that the recent rate of sedimentation is not uniform in the lake. The useful life of lake is estimated as about 800 years. The δD and δ 18 O values of the lake waters indicate that the lake is well mixed with a slight variation horizontally. The stable isotope studies on well waters from the catchment indicate hydraulic communication with the lake and lake groundwater system is flow-through type. Analytical model also supports this view. (author)

  1. 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.

  2. 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

  3. 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 ...

  4. Effects of pollution on freshwater fish

    International Nuclear Information System (INIS)

    McKim, J.M.; Christensen, G.M.; Tucker, J.H.; Benoit, D.A.; Lewis, M.J.

    1974-01-01

    Various aspects of pollution effects on fishes are reviewed under the following headings: methodology; water quality; pesticide pollutants; industrial pollutants; domestic pollutants; radioactive pollutants; and other pollutants. A table is presented to show acute and chronic toxicity of inorganic and organic pollutants to freshwater fish. (U.S.)

  5. 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)

  6. 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

  7. 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.

  8. 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 ...

  9. 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 t...

  10. Macrophytes: Freshwater Forests of Lakes and Rivers.

    Science.gov (United States)

    McDermid, Karla J.; Naiman, Robert J.

    1983-01-01

    Physical, chemical, and biological effects on macrophytes (aquatic plants) on the freshwater ecosystem are discussed. Research questions and issues related to these organisms are also discussed, including adaptations for survival in a wet environment, ecological consequences of large-scale macrophyte eradication, seasonal changes in plant…

  11. River and wetland classifications for freshwater conservation ...

    African Journals Online (AJOL)

    River and wetland classifications for freshwater conservation planning in KwaZulu-Natal, South Africa. ... regional- or provincial-scale conservation planning. The hierarchical structure of the classifications provides scope for finer resolution, by the addition of further levels, for application at a sub-regional or municipal scale.

  12. 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

  13. 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

  14. 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

  15. 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, ...

  16. Shallow water equations: viscous solutions and inviscid limit

    Science.gov (United States)

    Chen, Gui-Qiang; Perepelitsa, Mikhail

    2012-12-01

    We establish the inviscid limit of the viscous shallow water equations to the Saint-Venant system. For the viscous equations, the viscosity terms are more degenerate when the shallow water is close to the bottom, in comparison with the classical Navier-Stokes equations for barotropic gases; thus, the analysis in our earlier work for the classical Navier-Stokes equations does not apply directly, which require new estimates to deal with the additional degeneracy. We first introduce a notion of entropy solutions to the viscous shallow water equations and develop an approach to establish the global existence of such solutions and their uniform energy-type estimates with respect to the viscosity coefficient. These uniform estimates yield the existence of measure-valued solutions to the Saint-Venant system generated by the viscous solutions. Based on the uniform energy-type estimates and the features of the Saint-Venant system, we further establish that the entropy dissipation measures of the viscous solutions for weak entropy-entropy flux pairs, generated by compactly supported C 2 test-functions, are confined in a compact set in H -1, which yields that the measure-valued solutions are confined by the Tartar-Murat commutator relation. Then, the reduction theorem established in Chen and Perepelitsa [5] for the measure-valued solutions with unbounded support leads to the convergence of the viscous solutions to a finite-energy entropy solution of the Saint-Venant system with finite-energy initial data, which is relative with respect to the different end-states of the bottom topography of the shallow water at infinity. The analysis also applies to the inviscid limit problem for the Saint-Venant system in the presence of friction.

  17. Transient Localization in Shallow Water Environments

    National Research Council Canada - National Science Library

    Brune, Joachim

    1998-01-01

    .... A full-wave PE model is used to produce broadband replicas. Both model-generated synthetic signals, which provide baseline results, and measured pulses in a shallow water environment are analyzed...

  18. Hydrogeological Characteristics of Groundwater Yield in Shallow ...

    African Journals Online (AJOL)

    Hydrogeological Characteristics of Groundwater Yield in Shallow Wells of the ... of Water Resources and Lower Niger River Basin Development Authority in Ilorin. ... moment correlation, multiple and stepwise multiple regression analysis.

  19. Is evaporative colling important for shallow clouds?

    Science.gov (United States)

    Gentine, P.; Park, S. B.; Davini, P.; D'Andrea, F.

    2017-12-01

    We here investigate and test using large-eddy simulations the hypothesis that evaporative cooling might not be crucial for shallow clouds. Results from various Shallow convection and stratocumulus LES experiments show that the influence of evaporative cooling is secondary compared to turbulent mixing, which dominates the buoyancy reversal. In shallow cumulus subising shells are not due to evaporative cooling but rather reflect a vortical structure, with a postive buoyancy anomaly in the core due to condensation. Disabling evaporative cooling has negligible impact on this vortical structure and on buoyancy reversal. Similarly in non-precipitating stratocumuli evaporative cooling is negeligible copmared to other factors, especially turbulent mixing and pressure effects. These results emphasize that it may not be critical to icnlude evaporative cooling in parameterizations of shallow clouds and that it does not alter entrainment.

  20. Some problematic shallow-marine structures

    NARCIS (Netherlands)

    Manten, A.A.

    The lowermost Devonian beds in Gotland (Sweden) were deposited in a very shallow marine environment, close to the coast. In these beds three structures were observed, whose mode of formation cannot be explained by the author.

  1. Shallow moonquakes - How they compare with earthquakes

    Science.gov (United States)

    Nakamura, Y.

    1980-01-01

    Of three types of moonquakes strong enough to be detectable at large distances - deep moonquakes, meteoroid impacts and shallow moonquakes - only shallow moonquakes are similar in nature to earthquakes. A comparison of various characteristics of moonquakes with those of earthquakes indeed shows a remarkable similarity between shallow moonquakes and intraplate earthquakes: (1) their occurrences are not controlled by tides; (2) they appear to occur in locations where there is evidence of structural weaknesses; (3) the relative abundances of small and large quakes (b-values) are similar, suggesting similar mechanisms; and (4) even the levels of activity may be close. The shallow moonquakes may be quite comparable in nature to intraplate earthquakes, and they may be of similar origin.

  2. Microphytobenthos and benthic macroalgae determine sediment organic matter composition in shallow photic sediments

    NARCIS (Netherlands)

    Hardison, A.K.; Canuel, E.A/; Anderson, I.C.; Tobias, C.R.; Veuger, B.; Waters, M.N.

    2013-01-01

    Microphytobenthos and benthic macroalgae play an important role in system metabolism within shallow coastal bays. However, their independent and interactive influences on sediment organic matter (SOM) are not well understood. We investigated the influence of macroalgae and microphytobenthos on SOM

  3. Shape up or ship out: migratory behaviour predicts morphology across spatial scale in a freshwater fish.

    Science.gov (United States)

    Chapman, Ben B; Hulthén, Kaj; Brönmark, Christer; Nilsson, P Anders; Skov, Christian; Hansson, Lars-Anders; Brodersen, Jakob

    2015-09-01

    1. Migration is a widespread phenomenon, with powerful ecological and evolutionary consequences. Morphological adaptations to reduce the energetic costs associated with migratory transport are commonly documented for migratory species. However, few studies have investigated whether variation in body morphology can be explained by variation in migratory strategy within a species. 2. We address this question in roach Rutilus rutilus, a partially migratory freshwater fish that migrates from lakes into streams during winter. We both compare body shape between populations that differ in migratory opportunity (open vs. closed lakes), and between individuals from a single population that vary in migratory propensity (migrants and residents from a partially migratory population). Following hydrodynamic theory, we posit that migrants should have a more shallow body depth, to reduce the costs associated with migrating into streams with higher flow conditions than the lakes the residents occupy all year round. 3. We find evidence both across and within populations to support our prediction, with individuals from open lakes and migrants from the partially migratory population having a more slender, shallow-bodied morphology than fish from closed lakes and all-year residents. 4. Our data suggest that a shallow body morphology is beneficial to migratory individuals and our study is one of the first to link migratory strategy and intraspecific variation in body shape. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

  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. Justification of Shallow-Water Theory

    Science.gov (United States)

    Ostapenko, V. V.

    2018-01-01

    The basic conservation laws of shallow-water theory are derived from multidimensional mass and momentum integral conservation laws describing the plane-parallel flow of an ideal incompressible fluid above the horizontal bottom. This conclusion is based on the concept of hydrostatic approximation, which generalizes the concept of long-wavelength approximation and is used for justifying the applicability of the shallow-water theory in the simulation of wave flows of fluid with hydraulic bores.

  6. Temporal-spatial variations and influencing factors of nitrogen in the shallow groundwater of the nearshore vegetable field of Erhai Lake, China.

    Science.gov (United States)

    Chen, Anqiang; Lei, Baokun; Hu, Wanli; Wang, Hongyuan; Zhai, Limei; Mao, Yanting; Fu, Bin; Zhang, Dan

    2018-02-01

    Nitrogen export from the nearshore vegetable field of Erhai Lake seriously threatens the water quality of Erhai Lake, which is the second largest highland freshwater lake in Yunnan Province, China. Among the nitrogen flows into Erhai Lake, shallow groundwater migration is a major pathway. The nitrogen variation and influencing factors in the shallow groundwater of the nearshore vegetable field of Erhai Lake are not well documented. A 2-year field experiment was conducted to determine the concentrations of nitrogen species in the shallow groundwater and their influencing factors in the nearshore vegetable field of Erhai Lake. The results showed that concentrations of TN, NO 3 - -N, and NO 2 - -N gradually increased with increasing elevation and distance from Erhai Lake, but the opposite was observed for NH 4 + -N in the shallow groundwater. The concentrations of nitrogen species in the rainy season were greater than those in the dry season. NO 3 - -N accounted for more than 79% of total nitrogen in shallow groundwater. Redundancy analysis showed that more than 70% of the temporal and spatial variations of nitrogen concentrations in the shallow groundwater were explained by shallow groundwater depth, and only approximately 10% of variation was explained by the factors of soil porosity, silt clay content of soil, and NH 4 + -N and NO 3 - -N concentrations of soil (p shallow groundwater depth had more notable effects on nitrogen concentrations in the shallow groundwater than other factors. This result will strongly support the need for further research regarding the management practices for reducing nitrogen concentrations in shallow groundwater.

  7. Application of solar roof shallow pool at individual residental buildings

    OpenAIRE

    Gavrilović Dragan J.

    2011-01-01

    The paper discusses the possibility of applying shallow roof pools of water on the basis of passive solar water capture functioning as thermal batteries and thermal "regulators" in a "hot - cold" mode with individual residential buildings. With this application, the utilization of the existing functionality of the building roof area would improve and open up the possibility of achieving better overall bio-climate individual object. By using this system, a flat roof impassable "terrace" ...

  8. Oil spills into freshwater environments-literature review of fate and effects

    International Nuclear Information System (INIS)

    Taylor, E.; Owens, E.; Craig, A.; Steen, A.; Fritz, D.

    1993-01-01

    A literature search (1984--1992) was performed to summarize the environmental and human health effects of inlands spills. Over 100 major spills that affected freshwater environments were reported through the Emergency Response Notification System (ERNS) in 1991--1992 alone. Spills from pipelines outnumber all other sources combined. The oil types involved are about equally distributed between non-persistent oils and crude. Small rivers, streams, and creeks are the habitats into which most freshwater spills occur. Cleanup of stranded oil, rather than protection or recovery of floating oil, is the norm in most situations because stranding on river and lake banks often occurs before response is possible. The prediction of spill movement commonly is simpler for freshwater spills because freshwater bodies are relatively small and commonly have strong uni-directional flow; however, fast flow in rivers and streams and turnover in cooling lakes serve to distribute oil throughout the water column. Impacts to the environment, through food web structures or groundwater, may persist for months following a spill but seldom persist for years, unlike marine coastal impacts. Chronic impacts of oil spills into freshwater are rarely documented and these impacts are difficult to separate from effects of other hydrocarbons in the environment

  9. Effects of acidification on olfactory-mediated behaviour in freshwater and marine ecosystems: a synthesis.

    Science.gov (United States)

    Leduc, Antoine O H C; Munday, Philip L; Brown, Grant E; Ferrari, Maud C O

    2013-01-01

    For many aquatic organisms, olfactory-mediated behaviour is essential to the maintenance of numerous fitness-enhancing activities, including foraging, reproduction and predator avoidance. Studies in both freshwater and marine ecosystems have demonstrated significant impacts of anthropogenic acidification on olfactory abilities of fish and macroinvertebrates, leading to impaired behavioural responses, with potentially far-reaching consequences to population dynamics and community structure. Whereas the ecological impacts of impaired olfactory-mediated behaviour may be similar between freshwater and marine ecosystems, the underlying mechanisms are quite distinct. In acidified freshwater, molecular change to chemical cues along with reduced olfaction sensitivity appear to be the primary causes of olfactory-mediated behavioural impairment. By contrast, experiments simulating future ocean acidification suggest that interference of high CO2 with brain neurotransmitter function is the primary cause for olfactory-mediated behavioural impairment in fish. Different physico-chemical characteristics between marine and freshwater systems are probably responsible for these distinct mechanisms of impairment, which, under globally rising CO2 levels, may lead to strikingly different consequences to olfaction. While fluctuations in pH may occur in both freshwater and marine ecosystems, marine habitat will remain alkaline despite future ocean acidification caused by globally rising CO2 levels. In this synthesis, we argue that ecosystem-specific mechanisms affecting olfaction need to be considered for effective management and conservation practices.

  10. Use of geomorphic, hydrologic, and nitrogen mass balance data to model ecosystem nitrate retention in tidal freshwater wetlands

    OpenAIRE

    E. D. Seldomridge; K. L. Prestegaard

    2012-01-01

    Geomorphic characteristics have been used as scaling parameters to predict water and other fluxes in many systems. In this study, we combined geomorphic analysis with in-situ mass balance studies of nitrate retention (NR) to evaluate which geomorphic scaling parameters best predicted NR in a tidal freshwater wetland ecosystem. Geomorphic characteristics were measured for 267 individual marshes that constitute the freshwater tidal wetland ecosystem of the Patuxent River...

  11. Extreme diel dissolved oxygen and carbon cycles in shallow vegetated lakes.

    Science.gov (United States)

    Andersen, Mikkel R; Kragh, Theis; Sand-Jensen, Kaj

    2017-09-13

    A common perception in limnology is that shallow lakes are homogeneously mixed owing to their small water volume. However, this perception is largely gained by downscaling knowledge from large lakes to their smaller counterparts. Here we show that shallow vegetated lakes (less than 0.6 m), in fact, undergo recurring daytime stratification and nocturnal mixing accompanied by extreme chemical variations during summer. Dense submerged vegetation effectively attenuates light and turbulence generating separation between warm surface waters and much colder bottom waters. Photosynthesis in surface waters produces oxygen accumulation and CO 2 depletion, whereas respiration in dark bottom waters causes anoxia and CO 2 accumulation. High daytime pH in surface waters promotes precipitation of CaCO 3 which is re-dissolved in bottom waters. Nocturnal convective mixing re-introduces oxygen into bottom waters for aerobic respiration and regenerated inorganic carbon into surface waters, which supports intense photosynthesis. Our results reconfigure the basic understanding of local environmental gradients in shallow lakes, one of the most abundant freshwater habitats globally. © 2017 The Author(s).

  12. CDOM fluorescence as a proxy of DOC concentration in natural waters: a comparison of four contrasting tropical systems.

    Science.gov (United States)

    Rochelle-Newall, E; Hulot, F D; Janeau, J L; Merroune, A

    2014-01-01

    Chromophoric dissolved organic matter (CDOM) fluorescence or absorption is often proposed as a rapid alternative to chemical methods for the estimation of bulk dissolved organic carbon (DOC) concentration in natural waters. However, the robustness of this method across a wide range of systems remains to be shown. We measured CDOM fluorescence and DOC concentration in four tropical freshwater and coastal environments (estuary and coastal, tropical shallow lakes, water from the freshwater lens of two small islands, and soil leachates). We found that although this method can provide an estimation of DOC concentration in sites with low variability in DOC and CDOM sources in systems where the variability of DOC and CDOM sources are high, this method should not be used as it will lead to errors in the estimation of the bulk DOC concentration.

  13. Oxygen Isotope Composition of Nitrate Produced by Freshwater Nitrification

    Science.gov (United States)

    Boshers, D.; Granger, J.; Bohlke, J. K.

    2016-12-01

    Measurements of the naturally occurring nitrogen and oxygen stable isotope ratios of nitrate (NO3-), δ15N and δ18O, can be used to determine the source, dispersal, and fate of natural and contaminant NO3- in aquatic environments. To this end, it is necessary to know the extent to which NO3- isotopologues are modified by biological reactions, as heavy and light isotopes have different reaction rates. The purpose of this study was to determine the influence of the δ18O of ambient water on the isotope composition of NO3- produced during nitrification, the biological oxidation of ammonium (NH4+) to nitrite (NO2-) and then NO3-, which is poorly constrained in freshwater systems. To determine the δ18O of NO3- produced by nitrification in freshwater, we collected water from a stream in New England, which we amended with NH4+ and with increments of 18O-enriched water, to monitor the isotope composition of NO3- produced by a natural consortium of nitrifiers. Added NH4+ was completely oxidized to NO3- over 26 days. The final δ18O of nitrified NO3- revealed sensitivity to the δ18O of water mediated by (a) isotopic equilibration between water and NO2- and (b) kinetic isotope fractionation during O-atom incorporation from water into NO2- and NO3-. Our results concur with nitrifying culture experiments that have demonstrated analogous sensitivity of the δ18O of nitrified NO3- to equilibrium and kinetic O isotope effects (Buchwald et al. 2012), as well as show that these dynamics need to be considered to interpret NO3- isotope distribution in freshwater environments.

  14. The Implications of Ranaviruses to European farmed and wild freshwater fish

    DEFF Research Database (Denmark)

    Jensen, Ann Britt Bang

    The present thesis explores the implications of ranaviruses to European farmed and wild freshwater fish. The work presented was carried out as a part of the EU project “Risk assessment of new and emerging systemic iridoviral diseases for European fish and aquatic ecosystems” which was initiated...... in 2005 as a reaction to the speculation that ranaviruses might pose a serious threat to both farmed and wild-living freshwater fish and amphibians within the European community. In the present thesis, the purpose is to determine the implications of ranaviruses to European freshwater farmed and wild...... describing the risk of introduction and spread of exotic ranaviruses in European wild and farmed aquatic ecosystems Objectives 1 and 2 have been addressed by experimental trials involving bath challenges of both European farmed and wild fish species and ornamental fish species. The results showed that some...

  15. Predicting the 137Cs Contamination of Freshwater Fish in Hong Kong

    International Nuclear Information System (INIS)

    Poon, C.B.; Au, S.M.

    1999-01-01

    A predictive method for estimating the 137 Cs contamination of freshwater fish in Hong Kong after an acute deposition is presented. This method applies a published aquatic model to the freshwater fish culture ponds in Hong Kong. The predicted transfer coefficient, in terms of peak concentration in fish (wet weight) per unit deposition, is found to be generally lower than those observed in some European and UK lakes after the Chernobyl accident. While the water-fish concentration factor is undoubtedly an important factor, some unique features of the local freshwater fish culture systems, such as the absence of further radioactivity input from catchment to the fish ponds after deposition, and high removal of radioactivity by sedimentation, also play significant roles. Sensitivity of model parameters and uncertainties of prediction are also studied. This predictive model can serve as a useful tool in emergency planning and in countermeasure implementation during a nuclear emergency in Hong Kong. (author)

  16. Comparative evaluation of effects of ozonated and chlorinated thermal discharges on estuarine and freshwater organisms

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, C.R.; Sugam, R.; Meldrim, J.W.; Holmstrom, E.R.; Balog, G.E.

    1980-08-01

    As a part of a program at PSE and G designed to examine the feasibility of ozonation as an alternative to chlorination for control of biofouling in once-through cooling systems, the biological effects of ozonated and chlorinated thermal discharges were evaluated with estuarine and freshwater organisms. Mortality at salinities between 0.5 to 2.5 ppt with mummichog and white perch indicated greater toxicity for chlorine while the alewife, spottail shiner, rainbow trout and white perch in freshwater were more sensitive to ozone. Behavioral and physograhic results were consistent with those observed in toxicity studies. Initial cough response and avoidance concentrations of mummicog and white perch in estuarine waters were lower when exposed to chlorine than to ozone. In freshwater, blueback herring, alewife, rainbow trout, spottail shiner, banded killifish, and white perch avoided lower concentrations of ozone than chlorine.

  17. Selection of spatial scale for assessing impacts of groundwater-based water supply on freshwater resources

    DEFF Research Database (Denmark)

    Hybel, Anne-Marie; Godskesen, Berit; Rygaard, Martin

    2015-01-01

    used in this study: the Withdrawal-To-Availability ratio (WTA) and the Water Stress Index (WSI). Results were calculated for three groundwater based Danish urban water supplies (Esbjerg, Aarhus, and Copenhagen). The assessment was carried out at three spatial levels: (1) the groundwater body level, (2......) the river basin level, and (3) the regional level. The assessments showed that Copenhagen's water supply had the highest impact on the freshwater resource per cubic meter of water abstracted, with a WSI of 1.75 at Level 1. The WSI values were 1.64 for Aarhus's and 0.81 for Esbjerg's water supply. Spatial......Indicators of the impact on freshwater resources are becoming increasingly important in the evaluation of urban water systems. To reveal the importance of spatial resolution, we investigated how the choice of catchment scale influenced the freshwater impact assessment. Two different indicators were...

  18. Hydrochemistry in surface water and shallow groundwater. Site descriptive modelling SDM-Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Troejbom, Mats (Mopelikan, Norrtaelje (SE)); Soederbaeck, Bjoern (Swedish Nuclear Fuel and Waste Management Co., Stockholm (SE)); Johansson, Per-Olof (Artesia Grundvattenkonsult AB, Taeby (SE))

    2007-10-15

    mineral has a central role in the forming of today's hydrochemistry in surface systems, and probably also on the composition of the dilute, non-brackish, groundwater in the upper parts of the fractured bedrock. The rich supply of calcium and the high alkalinity affects the structure of the whole ecosystem, for example by forming the oligotrophic hardwater lakes which are characteristic for the area. One major issue in the report is if there can be found any indications on deep groundwater discharge in the surface system. According to observations in surface water and shallow groundwater, and to the hydrological/hydrochemical conceptual model, there is probably no ongoing deep discharge into the freshwater surface system. In restricted areas there are, however, indications that relict marine remnants, which also includes deep saline signatures, prevail in the groundwater at relatively shallow depths in the Quaternary deposits, but not reach the surface due to the downwards directed groundwater flow pattern that generally prevail in the area. This hydrochemical pattern could according to the conceptual model probably be explained by influence from marine remnants formed under a previous hydrological regime and these signatures are preserved because of stagnant conditions in some areas

  19. Hydrochemistry in surface water and shallow groundwater. Site descriptive modelling SDM-Site Forsmark

    International Nuclear Information System (INIS)

    Troejbom, Mats; Soederbaeck, Bjoern; Johansson, Per-Olof

    2007-10-01

    mineral has a central role in the forming of today's hydrochemistry in surface systems, and probably also on the composition of the dilute, non-brackish, groundwater in the upper parts of the fractured bedrock. The rich supply of calcium and the high alkalinity affects the structure of the whole ecosystem, for example by forming the oligotrophic hardwater lakes which are characteristic for the area. One major issue in the report is if there can be found any indications on deep groundwater discharge in the surface system. According to observations in surface water and shallow groundwater, and to the hydrological/hydrochemical conceptual model, there is probably no ongoing deep discharge into the freshwater surface system. In restricted areas there are, however, indications that relict marine remnants, which also includes deep saline signatures, prevail in the groundwater at relatively shallow depths in the Quaternary deposits, but not reach the surface due to the downwards directed groundwater flow pattern that generally prevail in the area. This hydrochemical pattern could according to the conceptual model probably be explained by influence from marine remnants formed under a previous hydrological regime and these signatures are preserved because of stagnant conditions in some areas

  20. Temporal Variability of Microplastic Concentrations in Freshwater Streams

    Science.gov (United States)

    Watkins, L.; Walter, M. T.

    2016-12-01

    Plastic pollution, specifically the size fraction less than 5mm known as microplastics, is an emerging contaminant in waterways worldwide. The ability of microplastics to adsorb and transport contaminants and microbes, as well as be ingested by organisms, makes them a concern in both freshwater and marine ecosystems. Recent efforts to determine the extent of microplastic pollution are increasingly focused on freshwater systems, but most studies have reported concentrations at a single time-point; few have begun to uncover how plastic concentrations in riverine systems may change through time. We hypothesize the time of day and season of sampling influences the concentrations of microplastics in water samples and more specifically, that daytime stormflow samples contain the highest microplastic concentrations due to maximized runoff and wastewater discharge. In order to test this hypothesis, we sampled in two similar streams in Ithaca, New York using a 333µm mesh net deployed within the thalweg. Repeat samples were collected to identify diurnal patterns as well as monthly variation. Samples were processed in the laboratory following the NOAA wet peroxide oxidation protocol. This work improves our ability to interpret existing single-time-point survey results by providing information on how microplastic concentrations change over time and whether concentrations in existing stream studies are likely representative of their location. Additionally, these results will inform future studies by providing insight into representative sample timing and capturing temporal trends for the purposes of modeling and of developing regulations for microplastic pollution.

  1. Review of Ghana's water resources: the quality and management with particular focus on freshwater resources

    Science.gov (United States)

    Yeleliere, E.; Cobbina, S. J.; Duwiejuah, A. B.

    2018-06-01

    Freshwater resources are continually decreasing in quality and quantity. Approximately, 1% of this freshwater is accessible in lakes, river channels and underground for domestic use. The study reviewed literature on water resources with focus on freshwater, the quality of our freshwater in terms of physical, chemical and biological variables, the main mechanisms of management, and the challenges associated with these mechanisms as well as blending integrated water management with the indigenous or traditional management of water resources for sustainable development and peaceful co-existence. Also the review offered potent recommendations for policy makers to consider sustainable management of freshwater resources. A total of 95 articles were downloaded from Google scholar in water-related issues. The search took place from June to September 2017, and research articles from 1998 to 2018 were reviewed. Basically Ghana is made up of three discharge or outlet systems, namely the Coastal River Systems which is the least and Volta constituting the largest and with the South-Western been the intermediate. Also, freshwater resources usage can be put into two main categories, namely ex situ (withdrawal use) and in situ or in-stream use, and could also be referred to as the consumptive and non-consumptive use, respectively. With the exception of localised pollution engineered by illegal mining and other nuisance perpetuated by indigenes, the quality of water (surface and groundwater) in Ghana is generally better. The review outlined high microbial contamination of water as almost all surface waters are contaminated with either E. coli, faecal coliforms or total coliforms or all. However, these contaminations were more prevalent in surface water than groundwater.

  2. Ancient tombs in China and shallow ground burial of solid low-intermediate level radioactive wastes

    International Nuclear Information System (INIS)

    Huang Yawen; Gu Cunli

    1987-01-01

    Having reviewed the experiences with ancient tombs in China, particularly the experiences with tomb siting, configuration of tombs, backfilling materials, civil engineering techniques, sealing techniques, drainage system, antiseptic techniques, a comparison between the ancient tombs and the shallow ground burial of solid radioactive wastes is made. The authors believe that the brilliant achievements of ancient tombs in China in keeping ancient corpses and funeral objects are a historical evidence for safety of shallow ground burial of radioactive wastes, and that the main experiences with the ancient tombs may be useful to shallow ground burial of solid radioactive wastes

  3. Ancient tombs in China and shallow land disposal of low-intermediate level radioactive wastes

    International Nuclear Information System (INIS)

    Huang, Y.; Gu, C.

    1987-01-01

    The paper summerises the experiences of ancient tombs in China on tomb siting, configuration of tombs, backfilling materials, civil engineering techniques, sealing (or airlight) techniques, drainage system, antiseptic techniques and so on based upon site investigation. Comparison between ancient tombs in China and shallow land disposal of radioactive wastes has been made. The authors point out that the brilliant achievements of ancient tombs in China in keeping ancient corpses and funeral objects is a historical evidence for safety of shallow land disposal of radioactive wastes, and that the main experiences of ancient tombs can be used for reference to shallow land disposal of radioactive wastes

  4. Mapping of reed in shallow bays. SFR-Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Stroemgren, Maarten; Lindgren, Fredrik (Umeaa Univ. (Sweden))

    2011-03-15

    The regolith-lake development model (RLDM) describes the development of shallow bays to lakes and the infilling of lakes in the Forsmark area during an interglacial. The sensitivity analysis has shown the need for an update of the infill procedure in the RLDM. Data from the mapping of reed in shallow bays in the Forsmark area will be used to improve the infill procedure of an updated RLDM. The field work was performed in August 26-31, 2010. The mapping of reed was done in 124 points. In these points, coordinates and water depth were mapped using an echo sounder and a DGPS. Quaternary deposits and the thickness of soft sediments were mapped using an earth probe. Measurement points were delivered in ESRI shape format with coordinates in RT90 2.5 gon W and altitudes in the RHB70 system for storage in SKB's GIS data base

  5. Typhoon damage on a shallow mesophotic reef in Okinawa, Japan

    Directory of Open Access Journals (Sweden)

    Kristine N. White

    2013-09-01

    Full Text Available Little is known about effects of large storm systems on mesophotic reefs. This study reports on how Typhoon 17 (Jelawat affected Ryugu Reef on Okinawa-jima, Japan in September 2012. Benthic communities were surveyed before and after the typhoon using line intercept transect method. Comparison of the benthic assemblages showed highly significant differences in coral coverage at depths of 25–32 m before and after Typhoon 17. A large deep stand of Pachyseris foliosa was apparently less resistant to the storm than the shallower high diversity area of this reef. Contradictory to common perception, this research shows that large foliose corals at deeper depths are just as susceptible to typhoon damage as shallower branching corals. However, descriptive functional group analyses resulted in only minor changes after the disturbance, suggesting the high likelihood of recovery and the high resilience capacity of this mesophotic reef.

  6. Assessment of multi-trophic changes in a shallow boreal lake simultaneously exposed to climate change and aerial deposition of contaminants from the Athabasca Oil Sands Region, Canada.

    Science.gov (United States)

    Summers, Jamie C; Kurek, Joshua; Rühland, Kathleen M; Neville, Erin E; Smol, John P

    2017-08-15

    The Athabasca Oil Sands Region (AOSR) has been intensely developed for industrial bitumen extraction and upgrading since the 1980s. A paucity of environmental monitoring prior to development raises questions about baseline conditions in freshwater systems in the region and ecological responses to industrial activities. Further, climatic changes prompt questions about the relative roles of climate and industry in shaping aquatic ecosystems through time. We use aquatic bioindicators from multiple trophic levels, concentrations of petrogenic contaminants (dibenzothiophenes), and spectrally-inferred chlorophyll-a preserved in well-dated sediments of a closed-basin, shallow lake ~50km away from the main area of industry, in conjunction with climate observations, to assess how the biotic assemblages of a typical AOSR lake have changed during the past ~75years. We examine the contributions of the area's stressors in structuring aquatic communities. Increases in sedimentary measures of petrogenic contaminants provide clear evidence of aerial contaminant deposition from local industry since its establishment, while climate records demonstrate consistent warming and a recent period of reduced precipitation. Quantitative comparisons of biological assemblages from before and after the establishment of regional industry find significant (pshallow systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Freshwater biodiversity and aquatic insect diversification.

    Science.gov (United States)

    Dijkstra, Klaas-Douwe B; Monaghan, Michael T; Pauls, Steffen U

    2014-01-01

    Inland waters cover less than 1% of Earth's surface but harbor more than 6% of all insect species: Nearly 100,000 species from 12 orders spend one or more life stages in freshwater. Little is known about how this remarkable diversity arose, although allopatric speciation and ecological adaptation are thought to be primary mechanisms. Freshwater habitats are highly susceptible to environmental change and exhibit marked ecological gradients. Standing waters appear to harbor more dispersive species than running waters, but there is little understanding of how this fundamental ecological difference has affected diversification. In contrast to the lack of evolutionary studies, the ecology and habitat preferences of aquatic insects have been intensively studied, in part because of their widespread use as bioindicators. The combination of phylogenetics with the extensive ecological data provides a promising avenue for future research, making aquatic insects highly suitable models for the study of ecological diversification.

  8. 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.

  9. Freshwater use in livestock production—To be used for food crops or livestock feed?

    NARCIS (Netherlands)

    Ran, Ylva; Middelaar, van Corina E.; Lannerstad, Mats; Herrero, Mario; Boer, de Imke J.M.

    2017-01-01

    Current approaches to estimate freshwater use in livestock production systems generally fail to consider the competition for water resources with alternative uses, such as production of food crops food or other ecosystem services. This article presents a new method to account for the competition for

  10. Comparison of analytical techniques for dynamic trace metal speciation in natural freshwaters.

    NARCIS (Netherlands)

    Sigg, Laura; Black, Frank; Buffle, Jacques; Cao, Jun; Cleven, Rob; Davison, William; Galceran, Josep; Gunkel, Peggy; Kalis, Erwin; Kistler, David; Martin, Michel; Noël, Stéphane; Nur, Yusuf; Odzak, Niksa; Puy, Jaume; Riemsdijk, Willem van; Temminghoff, Erwin; Tercier-Waeber, Mary-Lou; Toepperwien, Stefanie; Town, Raewyn M; Unsworth, Emily R; Warnken, Kent W; Weng, Liping; Xue, Hanbin; Zhang, Hao

    2006-01-01

    Several techniques for speciation analysis of Cu, Zn, Cd, Pb, and Ni are used in freshwater systems and compared with respect to their performance and to the metal species detected. The analytical techniques comprise the following: (i) diffusion gradients in thin-film gels (DGT); (ii) gel integrated

  11. Freshwater savings from marine protein consumption

    International Nuclear Information System (INIS)

    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 km 3  yr −1 of water is used for human food production. Replacing marine protein with terrestrial protein would require an additional 350 km 3  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. (paper)

  12. Even Shallower Exploration with Airborne Electromagnetics

    Science.gov (United States)

    Auken, E.; Christiansen, A. V.; Kirkegaard, C.; Nyboe, N. S.; Sørensen, K.

    2015-12-01

    Airborne electromagnetics (EM) is in many ways undergoing the same type rapid technological development as seen in the telecommunication industry. These developments are driven by a steadily increasing demand for exploration of minerals, groundwater and geotechnical targets. The latter two areas demand shallow and accurate resolution of the near surface geology in terms of both resistivity and spatial delineation of the sedimentary layers. Airborne EM systems measure the grounds electromagnetic response when subject to either a continuous discrete sinusoidal transmitter signal (frequency domain) or by measuring the decay of currents induced in the ground by rapid transmission of transient pulses (time domain). In the last decade almost all new developments of both instrument hardware and data processing techniques has focused around time domain systems. Here we present a concept for measuring the time domain response even before the transient transmitter current has been turned off. Our approach relies on a combination of new instrument hardware and novel modeling algorithms. The newly developed hardware allows for measuring the instruments complete transfer function which is convolved with the synthetic earth response in the inversion algorithm. The effect is that earth response data measured while the transmitter current is turned off can be included in the inversion, significantly increasing the amount of available information. We demonstrate the technique using both synthetic and field data. The synthetic examples provide insight on the physics during the turn off process and the field examples document the robustness of the method. Geological near surface structures can now be resolved to a degree that is unprecedented to the best of our knowledge, making airborne EM even more attractive and cost-effective for exploration of water and minerals that are crucial for the function of our societies.

  13. Metal pollution across the upper delta plain wetlands and its adjacent shallow sea wetland, northeast of China: implications for the filtration functions of wetlands.

    Science.gov (United States)

    Liu, Jin; Ye, Siyuan; Yuan, Hongming; Ding, Xigui; Zhao, Guangming; Yang, Shixiong; He, Lei; Wang, Jin; Pei, Shaofeng; Huang, Xiaoyu

    2018-02-01

    Grain size and concentrations of organic carbon (Corg) and particulate metals (PMs) As, Cd, Cr, Cu, Hg, Pb, Zn, Al, Fe, and Mn of 373 surface sediment samples, salinities in 67 surface water samples, were analyzed in various environments, including the upper delta plain wetlands (UDPW), its adjacent shallow sea wetland (SSW) in the Liaodong Bay, and river channels that are running through the Liaohe Delta, to evaluate the spatial distribution, transportation environmental dynamics of metals, and the provenance of metal pollution and assess the filtration functions of wetlands. The concentrations of PMs for UDPW were generally higher by a factor of ~ 10-22% compared with its analogues in SSW, suggesting the accumulation of PMs within the UDPW indicates that the UDPW systems are efficiently physical and chemical traps for PMs of anthropogenic sources by retaining and storing pollutants flowing into the sea. However, there was sever sewage irrigation-induced Cd pollution with a geo-accumulation index of 0.62-3.11 in an area of ~ 86 km 2 of the adjacent shallow sea wetland, where large amount wetlands were historically moved for agriculture in the UDPW. Remarkably, the distributions of PMs were controlled by salinity-induced desorption and re-adsorption mechanisms and significantly dispersed the contamination coverage by the three-dimensional hydrodynamic and sedimentation processes that dominated by inputs of freshwater and ocean dynamics including NE-SW tidal currents and NE-E longshore drifts in the SSW of the Liaodong Bay. A high agreement between the UDPW and the SSW datasets in principal component analysis essentially reflects that the characteristics of PM sources in the SSW were actually inherited from that in the UDPW, with a much closer relationship among metals, organic matter, and fine particulates in SSW than that of UDPW, which was judged by their correlation coefficient range of 0.406-0.919 in SSW against those of 0.042-0.654 in UDPW.

  14. Pesticides in Brazilian freshwaters: a critical review.

    Science.gov (United States)

    Albuquerque, A F; Ribeiro, J S; Kummrow, F; Nogueira, A J A; Montagner, C C; Umbuzeiro, G A

    2016-07-13

    The widespread use of pesticides in agriculture can lead to water contamination and cause adverse effects on non-target organisms. Brazil has been the world's top pesticide market consumer since 2008, with 381 approved pesticides for crop use. This study provides a comprehensive literature review on the occurrence of pesticide residues in Brazilian freshwaters. We searched for information in official agency records and peer-reviewed scientific literature. Risk quotients were calculated to assess the potential risk posed to aquatic life by the individual pesticides based on their levels of water contamination. Studies about the occurrence of pesticides in freshwaters in Brazil are scarce and concentrated in few sampling sites in 5 of the 27 states. Herbicides (21) accounted for the majority of the substances investigated, followed by fungicides (11), insecticides (10) and plant growth regulators (1). Insecticides are the class of major concern. Brazil would benefit from the implementation of a nationwide pesticide freshwater monitoring program to support preventive, remediation and enforcement actions.

  15. 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.

  16. Contribution of conservation genetics in assessing neotropical freshwater fish biodiversity

    Directory of Open Access Journals (Sweden)

    NM. Piorski

    Full Text Available Human activities have a considerable impact on hydrographic systems and fish fauna. The present review on conservation genetics of neotropical freshwater fish reveals that DNA analyses have been promoting increased knowledge on the genetic structure of fish species and their response to environmental changes. This knowledge is fundamental to the management of wild fish populations and the establishment of Evolutionary Significant Units capable of conserving genetic integrity. While population structuring can occur even in long-distance migratory fish, isolated populations can show reduced genetic variation and be at greater risk of extinction. Phylogeography and phylogeny have been powerful tools in understanding the evolution of fish populations, species and communities in distinct neotropic environments. Captive fish can be used to introduce new individuals and genes into the wild and their benefits and disadvantages can be monitored through genetic analysis. Understanding how fish biodiversity in neotropical freshwaters is generated and maintained is highly important, as these habitats are transformed by human development and fish communities are increasingly exploited as food sources to sustain a growing human population.

  17. The Impacts of Modern Warfare on Freshwater Ecosystems

    Science.gov (United States)

    Francis, Robert A.

    2011-11-01

    There is increasing recognition and concern regarding the impacts of modern industrial warfare on the environment. Freshwater ecosystems are perhaps the most vulnerable to warfare-related impacts, which is of concern given that they provide so many essential environmental resources and services to society. Despite this, there has been little work to establish and quantify the types of impacts (both negative and positive) that warfare may have on such systems. This paper firstly highlights why rivers and lakes may be susceptible to warfare-related impacts, before synthesizing the available literature to explore the following main themes: intensification of wartime resource acquisition, use of water as an offensive or defensive weapon, direct and indirect effects of explosive ordnance, increased pollution, introduction of invasive alien species, and positive ecological impacts. This is then followed by a discussion of the implications of such impacts in relation to future warfare, including a consideration of the efficacy of existing legal instruments to protect the environment during conflict, and the trend for war to become more localized and `informal', and therefore less regulated. Finally, the paper identifies key research foci for understanding and mitigating the effects of warfare on freshwater ecosystems.