Science.gov

Sample records for salinity gradients wetted

  1. Salinity gradient power: utilizing vapor pressure differences.

    PubMed

    Olsson, M; Wick, G L; Isaacs, J D

    1979-10-26

    By utilizing the vapor pressure difference between high-salinity and lowsalinity wvater, one can obtain power from the gradients of salinity. This scheme eliminates the major problems associated with conversion methods in which membranes are used. The method we tested gave higher conversion efficiencies than membrane methods. Furthermore, hardware and techniques being developed for ocean thermal energy conversion may be applied to this approach to salinity gradient energy conversion. PMID:17809370

  2. FINAL REPORT. RAPID MIGRATION OF RADIONUCLIDES LEAKED FROM HIGH-LEVEL WATER TANKS: A STUDY OF SALINITY GRADIENTS, WETTED PATH GEOMETRY AND WATER VAPOR TRANSPORT

    EPA Science Inventory

    The basis of this study was the hypothesis that the physical and chemical properties of hypersaline tank waste could lead to wetting front instability and fingered flow following a tank leak. Thus, the goal of this project was to develop an understanding of the impacts of the pro...

  3. Uranium Distribution along the Salinity Gradient

    NASA Astrophysics Data System (ADS)

    Yoon, C.; Yoon, H.; Seo, J.; Lee, J.; Chung, K.

    2006-12-01

    Uranium distribution has been examined in the estuarine waters of the Keum River, Korea. Water samples were collected along a salinity gradient, range from 0.2 to 31.5 psu. Dissolved uranium in the samples has been extracted by C-18 SPE cartridge after pre-treatment. Extraction of uranium by C-18 cartridge after complexation with APDC/DDDC shows about 90 % recovery. After concentration of sample onto C-18 cartridge, uranium complex has been sequentially extracted by 50 % and 100 % acetonitrile, respectively. Result shows good recovery efficiency at low pH (2.5 _ 3.0) during the pre-treatment of sample which was presumably related with destabilization of uranium-carbonate complex. In the estuary, uranium shows typical conservative behavior along the salinity gradient. The current result substantiates earlier reports that uranium is conservatively transported from the river to the ocean. Most of dissolved trace metals, except cadmium, decreased with increasing salinity in the estuary. Dissolved organic carbon also decreased along the salinity gradient. Copper was rapidly removed during the mixing with seawaters as a result of organic matter flocculation. Dissolved molybdenum, vanadium and uranium distribution in the estuary showed similarities that those concentration increase along the salinity gradient.

  4. Rapid Migration of Radionuclides Leaked from High-Level Water Tanks; A Study of Salinity Gradients, Wetted Path Geometry and Water Vapor Transport

    SciTech Connect

    Anderson l. Ward; Glendon W. Gee; John S. Selker; Clay Cooper

    2002-04-24

    The basis of this study was the hypothesis that the physical and chemical properties of hypersaline tank waste could lead to wetting from instability and fingered flow following a tank leak. Thus, the goal of this project was to develop an understanding of the impacts of the properties of hypersaline fluids on transport through the unsaturated zone beneath Hanford's Tank Farms. There were three specific objectives (i) to develop an improved conceptualization of hypersaline fluid transport in laboratory (ii) to identify the degree to which field conditions mimic the flow processes observed in the laboratory and (iii) to provide a validation data set to establish the degree to which the conceptual models, embodied in a numerical simulator, could explain the observed field behavior. As hypothesized, high ionic strength solutions entering homogeneous pre-wetted porous media formed unstable wetting fronts atypical of low ionic strength infiltration. In the field, this mechanism could for ce flow in vertical flow paths, 5-15 cm in width, bypassing much of the media and leading to waste penetration to greater depths than would be predicted by current conceptual models. Preferential flow may lead to highly accelerated transport through large homogeneous units, and must be included in any conservative analysis of tank waste losses through coarse-textured units. However, numerical description of fingered flow using current techniques has been unreliable, thereby precluding tank-scale 3-D simulation of these processes. A new approach based on nonzero, hysteretic contract angles and fluid-dependent liquid entry has been developed for the continuum scale modeling of fingered flow. This approach has been coupled with and adaptive-grid finite-difference solver to permit the prediction of finger formation and persistence form sub centimeter scales to the filed scale using both scalar and vector processors. Although laboratory experiments demonstrated that elevated surface tens ion

  5. Rapid Migration of Radionuclides Leaked from High-Level Water Tanks: A Study of Salinity Gradients, Wetted Path Geometry and Water Vapor Transport

    SciTech Connect

    Anderson L. Ward; Glendon W. Gee; John S. Selker; Caly Cooper

    2002-04-24

    The basis of this study was the hypothesis that the physical and chemical properties of hypersaline tank waste could lead to wetting from instability and fingered flow following a tank leak. Thus, the goal of this project was to develop an understanding of the impacts of the properties of hypersaline fluids on transport through the unsaturated zone beneath Hanford's Tank Farms. There were three specific objectives (i) to develop an improved conceptualization of hypersaline fluid transport in laboratory (ii) to identify the degree to which field conditions mimic the flow processes observed in the laboratory and (iii) to provide a validation data set to establish the degree to which the conceptual models, embodied in a numerical simulator, could explain the observed field behavior. As hypothesized, high ionic strength solutions entering homogeneous pre-wetted porous media formed unstable wetting fronts a typical of low ionic strength infiltration. In the field, this mechanism could force flow in vertical flow paths, 5-15 cm in width, bypassing much of the media and leading to waste penetration to greater depths than would be predicted by current conceptual models. Preferential flow may lead to highly accelerated transport through large homogeneous units, and must be included in any conservative analysis of tank waste losses through coarse-textured units. However, numerical description of fingered flow using current techniques has been unreliable, thereby precluding tank-scale 3-D simulation of these processes. A new approach based on nonzero, hysteretic contact angles and fluid-dependent liquid entry has been developed for the continuum scale modeling of fingered flow. This approach has been coupled with and adaptive-grid finite-difference solver to permit the prediction of finger formation and persistence form sub centimeter scales to the filed scale using both scalar and vector processors. Although laboratory experiments demonstrated that elevated surface tension

  6. Biodiversity patterns of soil ciliates along salinity gradients.

    PubMed

    Zhao, Feng; Xu, Kuidong

    2016-04-01

    We evaluated ciliate diversity in saline soils with a salinity range from 6.5 to 65 psu by the morphological method of the Ludox-quantitative protargol stain (QPS) and the molecular techniques of ciliate-specific clone library and denaturing gradient gel electrophoresis. No active ciliates could be detected with the Ludox-QPS method, while high molecular diversity of ciliates was found. The highest ciliate molecular diversity was obtained from the soil at salinity of 8.9 psu, moderate diversity was found at salinity of 6.5 psu, and the diversity sharply decreased at salinity of 50.5 psu. By contrast, the number of ciliate classes clearly decreased with increasing soil salinity: six, five, four and two classes from sites with salinity of 6.5 psu, 8.9 psu, 29.5 psu and 50.5 psu, respectively. Ciliate diversity pattern is different from that of bacteria, whose diversity is also high in extremely saline environments. Meanwhile, the composition of ciliate community was significantly different along salinity gradient. Colpodea and Oligohymenophorea were diverse in soils at salinity less than 29.5 psu, while absent in soils with salinity above 50.5 psu. BIOENV analysis indicated soil salinity and water content were the main factors regulating the distribution of ciliates in saline soils. PMID:26773903

  7. SOLPOND: a simulation program for salinity gradient solar ponds

    SciTech Connect

    Henderson, J.; Leboeuf, C.M.

    1980-01-01

    A computer simulation design tool was developed to simulate dynamic thermal performance for salinity gradient solar ponds. Dynamic programming techniques allow the user significant flexibility in analyzing pond performance under realistic load and weather conditions. Finite element techniques describe conduction heat transfer through the pond, earth, and edges. Results illustrate typical thermal performance of salinity gradient ponds. Sensitivity studies of salty pond thermal performance with respect to geometry, load, and optical transmission are included. Experimental validation of the program with an operating pond is also presented.

  8. Salinity-gradient vapor-pressure power conversion

    NASA Astrophysics Data System (ADS)

    Olsson, M. S.

    1982-03-01

    The interface between water bodies of different salinities represents a large unexploited source of energy. An energy conversion approach that does not require the use of membranes but uses the differences in vapor pressure between solutions is examined. The resource potential, source solutions, system components, and operating characteristics are evaluated and, where similar, compared to research and development on open-cycle OTEC (Ocean Thermal Energy Conversion). It is shown that salinity-gradient, vapor-pressure power generation is within reach of current technology.

  9. Annual growth patterns of baldcypress (Taxodium distichum) along salinity gradients

    USGS Publications Warehouse

    Thomas, Brenda L.; Doyle, Thomas W.; Krauss, Ken W.

    2015-01-01

    The effects of salinity on Taxodium distichum seedlings have been well documented, but few studies have examined mature trees in situ. We investigated the environmental drivers of T. distichum growth along a salinity gradient on the Waccamaw (South Carolina) and Savannah (Georgia) Rivers. On each river, T. distichum increment cores were collected from a healthy upstream site (Upper), a moderately degraded mid-reach site (Middle), and a highly degraded downstream site (Lower). Chronologies were successfully developed for Waccamaw Upper and Middle, and Savannah Middle. Correlations between standardized chronologies and environmental variables showed significant relationships between T. distichum growth and early growing season precipitation, temperature, and Palmer Drought Severity Index (PDSI). Savannah Middle chronology correlated most strongly with August river salinity levels. Both lower sites experienced suppression/release events likely in response to local anthropogenic impacts rather than regional environmental variables. The factors that affect T. distichum growth, including salinity, are strongly synergistic. As sea-level rise pushes the freshwater/saltwater interface inland, salinity becomes more limiting to T. distichum growth in tidal freshwater swamps; however, salinity impacts are exacerbated by locally imposed environmental modifications.

  10. Coastal Microbial Mat Diversity along a Natural Salinity Gradient

    PubMed Central

    Bolhuis, Henk; Fillinger, Lucas; Stal, Lucas J.

    2013-01-01

    The North Sea coast of the Dutch barrier island of Schiermonnikoog is covered by microbial mats that initiate a succession of plant communities that eventually results in the development of a densely vegetated salt marsh. The North Sea beach has a natural elevation running from the low water mark to the dunes resulting in gradients of environmental factors perpendicular to the beach. These gradients are due to the input of seawater at the low water mark and of freshwater from upwelling groundwater at the dunes and rainfall. The result is a natural and dynamic salinity gradient depending on the tide, rainfall and wind. We studied the microbial community composition in thirty three samples taken every ten meters along this natural salinity gradient by using denaturing gradient gel electrophoresis (DGGE) of rRNA gene fragments. We looked at representatives from each Domain of life (Bacteria, Archaea and Eukarya) and with a particular emphasis on Cyanobacteria. Analysis of the DGGE fingerprints together with pigment composition revealed three distinct microbial mat communities, a marine community dominated by diatoms as primary producers, an intermediate brackish community dominated by Cyanobacteria as primary producers and a freshwater community with Cyanobacteria and freshwater green algae. PMID:23704895

  11. Salinity gradient power: influences of temperature and nanopore size

    NASA Astrophysics Data System (ADS)

    Tseng, Shiojenn; Li, Yu-Ming; Lin, Chih-Yuan; Hsu, Jyh-Ping

    2016-01-01

    Salinity gradient power is a promising, challenging, and readily available renewable energy. Among various methods for harvesting this clean energy, nanofluidic reverse electrodialysis (NRED) is of great potential. Since ionic transport depends highly on the temperature, so is the efficiency of the associated power generated. Here, we conduct a theoretical analysis on the influences of temperature and nanopore size on NRED, focusing on the temperature and nanopore size. The results gathered reveal that the maximum power increases with increasing temperature, but the conversion efficiency depends weakly on temperature. In general, the smaller the nanopore radius or the longer the nanopore, the better the ion selectivity. These results provide desirable and necessary information for improving the performance of NRED as well as designing relevant units in renewable energy plants.

  12. Salinity gradient power: influences of temperature and nanopore size.

    PubMed

    Tseng, Shiojenn; Li, Yu-Ming; Lin, Chih-Yuan; Hsu, Jyh-Ping

    2016-01-28

    Salinity gradient power is a promising, challenging, and readily available renewable energy. Among various methods for harvesting this clean energy, nanofluidic reverse electrodialysis (NRED) is of great potential. Since ionic transport depends highly on the temperature, so is the efficiency of the associated power generated. Here, we conduct a theoretical analysis on the influences of temperature and nanopore size on NRED, focusing on the temperature and nanopore size. The results gathered reveal that the maximum power increases with increasing temperature, but the conversion efficiency depends weakly on temperature. In general, the smaller the nanopore radius or the longer the nanopore, the better the ion selectivity. These results provide desirable and necessary information for improving the performance of NRED as well as designing relevant units in renewable energy plants. PMID:26752789

  13. Salinity gradient solar pond technology applied to potash solution mining

    SciTech Connect

    Martell, J.A.; Aimone-Martin, C.T.

    2000-06-12

    A solution mining facility at the Eddy Potash Mine, Eddy County, New Mexico has been proposed that will utilize salinity gradient solar pond (SGSP) technology to supply industrial process thermal energy. The process will include underground dissolution of potassium chloride (KCl) from pillars and other reserves remaining after completion of primary room and pillar mining using recirculating solutions heated in the SGSP. Production of KCl will involve cold crystallization followed by a cooling pond stage, with the spent brine being recirculated in a closed loop back to the SGSP for reheating. This research uses SGSP as a renewable, clean energy source to optimize the entire mining process, minimize environmental wastes, provide a safe, more economical extraction process and reduce the need for conventional processing by crushing, grinding and flotation. The applications of SGSP technology will not only save energy in the extraction and beneficiation processes, but also will produce excess energy available for power generation, desalination, and auxiliary structure heating.

  14. Silver behaviour along the salinity gradient of the Gironde Estuary.

    PubMed

    Lanceleur, Laurent; Schäfer, Jörg; Blanc, Gérard; Coynel, Alexandra; Bossy, Cécile; Baudrimont, Magalie; Glé, Corine; Larrose, Aurélie; Renault, Sophie; Strady, Emilie

    2013-03-01

    Dissolved and particulate Ag concentrations (Ag(D) and Ag(P), respectively) were measured in surface water and suspended particulate matter (SPM) along the salinity gradient of the Gironde Estuary, South West France, during three cruises (2008-2009) covering contrasting hydrological conditions, i.e. two cruises during intermediate and one during high freshwater discharge (~740 and ~2,300 m(3)/s). Silver distribution reflected non-conservative behaviour with 60-70 % of Ag(P) in freshwater particles being desorbed by chlorocomplexation. The amount of Ag(P) desorbed was similar to the so-called reactive, potentially bioavailable Ag(P) fraction (60 ± 4 %) extracted from river SPM by 1 M HCl. Both Ag(P) (0.22 ± 0.05 mg/kg) and Ag(P)/Th(P) (0.025-0.028) in the residual fraction of fluvial and estuarine SPM were similar to those in SPM from the estuary mouth and in coastal sediments from the shelf off the Gironde Estuary, indicating that chlorocomplexation desorbs the reactive Ag(P). The data show that desorption of reactive Ag(P) mainly occurs inside the estuary during low and intermediate discharge, whereas expulsion of partially Ag(P)-depleted SPM (Ag(P)/Th(P) ~0.040) during the flood implies ongoing desorption in the coastal ocean, e.g. in the nearby oyster production areas (Marennes-Oléron Bay). The highest Ag(D) levels (6-8 ng/L) occurred in the mid-salinity range (15-20) of the Gironde Estuary and were decoupled from freshwater discharge. In the maximum turbidity zone, Ag(D) were at minimum, showing that high SPM concentrations (a) induce Ag(D) adsorption in estuarine freshwater and (b) counterbalance Ag(P) desorption in the low salinity range (1-3). Accordingly, Ag behaviour in turbid estuaries appears to be controlled by the balance between salinity and SPM levels. The first estimates of daily Ag(D) net fluxes for the Gironde Estuary (Boyle's method) showed relatively stable theoretical Ag(D) at zero salinity (Ag (D) (0) = 25-30 ng/L) for the contrasting

  15. Energy Conversion from Salinity Gradient Using Microchip with Nafion Membrane

    NASA Astrophysics Data System (ADS)

    Chang, Che-Rong; Yeh, Ching-Hua; Yeh, Hung-Chun; Yang, Ruey-Jen

    2016-06-01

    When a concentrated salt solution and a diluted salt solution are separated by an ion-selective membrane, cations and anions would diffuse at different rates depending on the ion selectivity of the membrane. The difference of positive and negative charges at both ends of the membrane would produce a potential, called the diffusion potential. Thus, electrical energy can be converted from the diffusion potential through reverse electrodialysis. This study demonstrated the fabrication of an energy conversion microchip using the standard micro-electromechanical technique, and utilizing Nafion junction as connecting membrane, which was fabricated by a surface patterned process. Through different salinity gradient of potassium chloride solutions, we experimentally investigated the diffusion potential and power generation from the microchip, and the highest value measured was 135 mV and 339 pW, respectively. Furthermore, when the electrolyte was in pH value of 3.8, 5.6, 10.3, the system exhibited best performance at pH value of 10.3; whereas, pH value of 3.8 yielded the worst.

  16. Mapping the Salinity Gradient in a Microfluidic Device with Schlieren Imaging

    PubMed Central

    Sun, Chen-li; Chen, Shao-Tuan; Hsiao, Po-Jen

    2015-01-01

    This work presents the use of the schlieren imaging to quantify the salinity gradients in a microfluidic device. By partially blocking the back focal plane of the objective lens, the schlieren microscope produces an image with patterns that correspond to spatial derivative of refractive index in the specimen. Since salinity variation leads to change in refractive index, the fluid mixing of an aqueous salt solution of a known concentration and water in a T-microchannel is used to establish the relation between salinity gradients and grayscale readouts. This relation is then employed to map the salinity gradients in the target microfluidic device from the grayscale readouts of the corresponding micro-schlieren image. For saline solution with salinity close to that of the seawater, the grayscale readouts vary linearly with the salinity gradient, and the regression line is independent of the flow condition and the salinity of the injected solution. It is shown that the schlieren technique is well suited to quantify the salinity gradients in microfluidic devices, for it provides a spatially resolved, non-invasive, full-field measurement. PMID:26007720

  17. Paper-based energy harvesting from salinity gradients.

    PubMed

    Chang, Hyung-Kwan; Choi, Eunpyo; Park, Jungyul

    2016-02-21

    Paper-based microfluidic devices have many advantages such as low cost, flexibility, light weight and easy disposability. Especially, since they can intrinsically generate capillary-driven flow (no pumps are needed), paper-based microfluidic devices are widely used in analytical or diagnostic platforms. Along with advancements in microfluidic paper-based analytical devices (μPADs), energy generation using paper materials has received significant attention. In this study, environment-friendly and flexible paper-based energy harvesting with a simple configuration is demonstrated by using the principle of reverse electrodialysis (RED). RED is a promising clean energy generation method, which converts Gibbs free energy into electricity by salinity gradients without discharging any pollutants. However, the power efficiency in a conventional RED device is limited by the essential requirement of active pumping for providing high and low concentration electrolytes. Capillary pumping from the proposed paper-based RED can save this waste of energy, and moreover, the flexible device is realized with cost effective materials and a simple fabrication step, and is environmentally friendly. By thoughtful analysis of voltage-current experiments and capillary flow rates in paper channels, the optimized channel width interfacing with a selective membrane is determined as 2 mm and the maximum power and power density are achieved as 55 nW and 275 nW cm(-2), respectively. 25.8% of the generated maximum power is successfully saved by realizing the pumpless RED system. This paper-based RED device can be integrated directly with μPADs as a practical application. PMID:26768119

  18. One-dimensional transient finite difference model of an operational salinity gradient solar pond

    NASA Technical Reports Server (NTRS)

    Hicks, Michael C.; Golding, Peter

    1992-01-01

    This paper describes the modeling approach used to simulate the transient behavior of a salinity gradient solar pond. A system of finite difference equations are used to generate the time dependent temperature and salinity profiles within the pond. The stability of the pond, as determined by the capacity of the resulting salinity profile to suppress thermal convection within the primary gradient region of the pond, is continually monitored and when necessary adjustments are made to the thickness of the gradient zone. Results of the model are then compared to measurements taken during two representative seasonal periods at the University of Texas at El Paso's (UTEP's) research solar pond.

  19. Applications of salinity gradient solar technologies in the Southwest -- An overview

    SciTech Connect

    Swift, A.H.P.; Lu, H.

    1996-12-31

    This paper is an overview of recent applications of salinity gradient solar technologies (SGST) in the Southwest and especially in the State of Texas. SGST is a generic title for using a salinity gradient in a body of water to suppress convection and collect solar energy for a desired application, for example, salinity gradient solar ponds. Following initial work in the early 1980s at the El Paso Solar Pond project and funding of the Texas Solar Pond Consortium by the State of Texas and the Bureau of Reclamation, several applications involving the use of salinity gradient solar technologies have emerged. These applications include a biomass waste to energy project using heat from a solar pond at Bruce Foods Corporation; an industrial process heat application for sodium sulfate mining near Seagraves, Texas; overwintering thermal refuges for mariculture in Palacios, Texas; a potential salt management project on the Brazos River near Abilene, Texas; and use of solar ponds for brine disposal at a water desalting project in a small colonia east of El Paso. This paper discusses salinity gradient solar technology requirements and the abundance of resources available in Texas and the Southwest which makes this an attractive location for the commercial development of salinity gradient projects. Barriers to development as well as catalysts are discussed before a brief overview of the projects listed above is provided.

  20. A wet/wet differential pressure sensor for measuring vertical hydraulic gradient

    SciTech Connect

    Fritz, Brad G.; Mackley, Rob D.

    2008-12-13

    This article describes a new tool for measuring vertical hydraulic gradient in the hyporheic zone. It is essentially an electronic version of an established differential pressure measurement technique.

  1. Population ecology of the gulf ribbed mussel across a salinity gradient: recruitment, growth and density

    USGS Publications Warehouse

    Honig, Aaron; Supan, John; LaPeyre, Megan K.

    2015-01-01

    Benthic intertidal bivalves play an essential role in estuarine ecosystems by contributing to habitat provision, water filtration, and promoting productivity. As such, changes that impact population distributions and persistence of local bivalve populations may have large ecosystem level consequences. Recruitment, growth, mortality, population size structure and density of the gulf coast ribbed mussel, Geukensia granosissima, were examined across a salinity gradient in southeastern Louisiana. Data were collected along 100-m transects at interior and edge marsh plots located at duplicate sites in upper (salinity ~4 psu), central (salinity ~8 psu) and lower (salinity ~15 psu) Barataria Bay, Louisiana, U.S.A. Growth, mortality and recruitment were measured in established plots from April through November 2012. Mussel densities were greatest within the middle bay (salinity ~8) regardless of flooding regime, but strongly associated with highest stem densities of Juncus roemerianus vegetation. Mussel recruitment, growth, size and survival were significantly higher at mid and high salinity marsh edge sites as compared to all interior marsh and low salinity sites. The observed patterns of density, growth and mortality in Barataria Bay may reflect detrital food resource availability, host vegetation community distribution along the salinity gradient, salinity tolerance of the mussel, and reduced predation at higher salinity edge sites.

  2. Towards a theory of ecotone resilience: coastal vegetation on a salinity gradient

    USGS Publications Warehouse

    Jiang, Jiang; Gao, Daozhou; DeAngelis, Donald L.

    2012-01-01

    Ecotones represent locations where vegetation change is likely to occur as a result of climate and other environmental changes. Using a model of an ecotone vulnerable to such future changes, we estimated the resilience of the ecotone to disturbances. The specific ecotone is that between two different vegetation types, salinity-tolerant and salinity-intolerant, along a gradient in groundwater salinity. In the case studied, each vegetation type, through soil feedback loops, promoted local soil salinity levels that favor itself in competition with the other type. Bifurcation analysis was used to study the system of equations for the two vegetation types and soil salinity. Alternative stable equilibria, one for salinity-tolerant and one for salinity intolerant vegetation, were shown to exist over a region of the groundwater salinity gradient, bounded by two bifurcation points. This region was shown to depend sensitively on parameters such as the rate of upward infiltration of salinity from groundwater into the soil due to evaporation. We showed also that increasing diffusion rates of vegetation can lead to shrinkage of the range between the two bifurcation points. Sharp ecotones are typical of salt-tolerant vegetation (mangroves) near the coastline and salt-intolerant vegetation inland, even though the underlying elevation and groundwater salinity change very gradually. A disturbance such as an input of salinity to the soil from a storm surge could upset this stable boundary, leading to a regime shift of salinity-tolerant vegetation inland. We showed, however, that, for our model as least, a simple pulse disturbance would not be sufficient; the salinity would have to be held at a high level, as a 'press', for some time. The approach used here should be generalizable to study the resilience of a variety of ecotones to disturbances.

  3. Resilience of estuarine phytoplankton and their temporal variability along salinity gradients during drought and hypersalinity

    NASA Astrophysics Data System (ADS)

    Nche-Fambo, F. A.; Scharler, U. M.; Tirok, K.

    2015-06-01

    In South African estuaries, there is no knowledge on the resilience and variability in phytoplankton communities under conditions of hypersalinity, extended droughts and reverse salinity gradients. Phytoplankton composition, abundance and biomass vary with changes in environmental variables and taxa richness declines specifically under hypersaline conditions. This research thus investigated the phytoplankton community composition, its resilience and variability under highly variable and extreme environmental conditions in an estuarine lake system (Lake St. Lucia, South Africa) over one year. The lake system was characterised by a reverse salinity gradient with hypersalinity furthest from the estuarine inlet during the study period. During this study, 78 taxa were recorded: 56 diatoms, eight green algae, one cryptophyte, seven cyanobacteria and six dinoflagellates. Taxon variability and resilience depended on their ability to tolerate high salinities. Consequently, the phytoplankton communities as well as total abundance and biomass differed along the salinity gradient and over time with salinity as the main determinant. Cyanobacteria were dominant in hypersaline conditions, dinoflagellates in marine-brackish salinities, green algae and cryptophytes in lower salinities (brackish) and diatoms were abundant in marine-brackish salinities but survived in hypersaline conditions. Total abundance and biomass ranged from 3.66 × 103 to 1.11 × 109 Cells/L and 1.21 × 106 to 1.46 × 1010 pgC/L respectively, with the highest values observed under hypersaline conditions. Therefore, even under highly variable, extreme environmental conditions and hypersalinity the phytoplankton community as a whole was resilient enough to maintain a relatively high biomass throughout the study period. The resilience of few dominant taxa, such as Cyanothece, Spirulina, Protoperidinium and Nitzschia and the dominance of other common genera such as Chlamydomonas, Chroomonas, Navicula, Gyrosigma

  4. Plant distributions along salinity and tidal gradients in Oregon tidal marshes

    EPA Science Inventory

    Accurately modeling climate change effects on tidal marshes in the Pacific Northwest requires understanding how plant assemblages and species are presently distributed along gradients of salinity and tidal inundation. We outline on-going field efforts by the EPA and USGS to dete...

  5. Life in the salinity gradient: Discovering mechanisms behind a new biodiversity pattern

    NASA Astrophysics Data System (ADS)

    Telesh, Irena; Schubert, Hendrik; Skarlato, Sergei

    2013-12-01

    A recently discovered paradoxical maximum of planktonic protistan species in the salinity gradient of the Baltic Sea revealed an inverse trend of species number/salinity relation in comparison to the previously accepted species-minimum model for macrozoobenthos. Here, we review long-term data on organisms of different size classes and ecological groups to show that eukaryotic and prokaryotic microbes in plankton demonstrate a maximum species richness in the challenging zone of the critical salinity 5-8, where the large-bodied bottom dwellers (macrozoobenthos, macroalgae and aquatic higher plants) experience large-scale salinity stress which leads to an impoverished diversity. We propose a new conceptual model to explain why the diversity of small, fast-developing, rapidly evolving unicellular plankton organisms benefits from relative vacancy of brackish-water ecological niches and impaired competitiveness therein. The ecotone theory, Hutchinson's Ecological Niche Concept, species-area relationships and the Intermediate Disturbance Hypothesis are considered as a theoretical framework for understanding extinctions, speciation and variations in the evolution rates of different aquatic species in ecosystems with the pronounced salinity gradient.

  6. Microbial Gene Abundance and Expression Patterns across a River to Ocean Salinity Gradient

    PubMed Central

    Fortunato, Caroline S.; Crump, Byron C.

    2015-01-01

    Microbial communities mediate the biogeochemical cycles that drive ecosystems, and it is important to understand how these communities are affected by changing environmental conditions, especially in complex coastal zones. As fresh and marine waters mix in estuaries and river plumes, the salinity, temperature, and nutrient gradients that are generated strongly influence bacterioplankton community structure, yet, a parallel change in functional diversity has not been described. Metagenomic and metatranscriptomic analyses were conducted on five water samples spanning the salinity gradient of the Columbia River coastal margin, including river, estuary, plume, and ocean, in August 2010. Samples were pre-filtered through 3 μm filters and collected on 0.2 μm filters, thus results were focused on changes among free-living microbial communities. Results from metagenomic 16S rRNA sequences showed taxonomically distinct bacterial communities in river, estuary, and coastal ocean. Despite the strong salinity gradient observed over sampling locations (0 to 33), the functional gene profiles in the metagenomes were very similar from river to ocean with an average similarity of 82%. The metatranscriptomes, however, had an average similarity of 31%. Although differences were few among the metagenomes, we observed a change from river to ocean in the abundance of genes encoding for catabolic pathways, osmoregulators, and metal transporters. Additionally, genes specifying both bacterial oxygenic and anoxygenic photosynthesis were abundant and expressed in the estuary and plume. Denitrification genes were found throughout the Columbia River coastal margin, and most highly expressed in the estuary. Across a river to ocean gradient, the free-living microbial community followed three different patterns of diversity: 1) the taxonomy of the community changed strongly with salinity, 2) metabolic potential was highly similar across samples, with few differences in functional gene abundance

  7. Microbial Gene Abundance and Expression Patterns across a River to Ocean Salinity Gradient.

    PubMed

    Fortunato, Caroline S; Crump, Byron C

    2015-01-01

    Microbial communities mediate the biogeochemical cycles that drive ecosystems, and it is important to understand how these communities are affected by changing environmental conditions, especially in complex coastal zones. As fresh and marine waters mix in estuaries and river plumes, the salinity, temperature, and nutrient gradients that are generated strongly influence bacterioplankton community structure, yet, a parallel change in functional diversity has not been described. Metagenomic and metatranscriptomic analyses were conducted on five water samples spanning the salinity gradient of the Columbia River coastal margin, including river, estuary, plume, and ocean, in August 2010. Samples were pre-filtered through 3 μm filters and collected on 0.2 μm filters, thus results were focused on changes among free-living microbial communities. Results from metagenomic 16S rRNA sequences showed taxonomically distinct bacterial communities in river, estuary, and coastal ocean. Despite the strong salinity gradient observed over sampling locations (0 to 33), the functional gene profiles in the metagenomes were very similar from river to ocean with an average similarity of 82%. The metatranscriptomes, however, had an average similarity of 31%. Although differences were few among the metagenomes, we observed a change from river to ocean in the abundance of genes encoding for catabolic pathways, osmoregulators, and metal transporters. Additionally, genes specifying both bacterial oxygenic and anoxygenic photosynthesis were abundant and expressed in the estuary and plume. Denitrification genes were found throughout the Columbia River coastal margin, and most highly expressed in the estuary. Across a river to ocean gradient, the free-living microbial community followed three different patterns of diversity: 1) the taxonomy of the community changed strongly with salinity, 2) metabolic potential was highly similar across samples, with few differences in functional gene abundance

  8. [Monitoring of soil salinization in Northern Tarim Basin, Xinjiang of China in dry and wet seasons based on remote sensing].

    PubMed

    Yao, Yuan; Ding, Jian-Li; Zhang, Fang; Wang, Gang; Jiang, Hong-Nan

    2013-11-01

    Soil salinization is one of the most important eco-environment problems in arid area, which can not only induce land degradation, inhibit vegetation growth, but also impede regional agricultural production. To accurately and quickly obtain the information of regional saline soils by using remote sensing data is critical to monitor soil salinization and prevent its further development. Taking the Weigan-Kuqa River Delta Oasis in the northern Tarim River Basin of Xinjiang as test object, and based on the remote sensing data from Landsat-TM images of April 15, 2011 and September 22, 2011, in combining with the measured data from field survey, this paper extracted the characteristic variables modified normalized difference water index (MNDWI), normalized difference vegetation index (NDVI), and the third principal component from K-L transformation (K-L-3). The decision tree method was adopted to establish the extraction models of soil salinization in the two key seasons (dry and wet seasons) of the study area, and the classification maps of soil salinization in the two seasons were drawn. The results showed that the decision tree method had a higher discrimination precision, being 87.2% in dry season and 85.3% in wet season, which was able to be used for effectively monitoring the dynamics of soil salinization and its spatial distribution, and to provide scientific basis for the comprehensive management of saline soils in arid area and the rational utilization of oasis land resources. PMID:24564152

  9. The Effect of Hydrodynamic Slip on Membrane-Based Salinity-Gradient-Driven Energy Harvesting.

    PubMed

    Rankin, Daniel Justin; Huang, David Mark

    2016-04-12

    The effect of hydrodynamic slip on salinity-gradient-driven power conversion by the process of reverse electrodialysis, in which the free energy of mixing of salt and fresh water across a nanoporous membrane is harnessed to drive an electric current in an external circuit, is investigated theoretically using a continuum fluid dynamics model. A general one-dimensional model is derived that decouples transport inside the membrane pores from the effects of electrical resistance at the pore ends, from which an analytical expression for the power conversion rate is obtained for a perfectly ion-selective membrane as a function of the slip length, surface charge density, membrane thickness, pore radius, and other membrane and electrolyte properties. The theoretical model agrees quantitatively with finite-element numerical calculations and predicts significant enhancements--up to several times--of salinity-gradient power conversion due to hydrodynamic slip for realistic systems. PMID:26991373

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

    NASA Astrophysics Data System (ADS)

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

    1987-01-01

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

  11. Soil water retention at varying matric potentials following repeated wetting with modestly saline-sodic water and subsequent air drying

    SciTech Connect

    Browning, L.S.; Hershberger, K.R.; Bauder, J.W.

    2007-07-01

    Coal bed natural gas (CBNG) development in the Powder River (PR) Basin produces modestly saline, highly sodic wastewater. This study assessed impacts of wetting four textural groups (0-11%, 12-22%, 23 -33%, and > 33% clay (g clay/100 g soil) x 100%))with simulated PR or CBNG water on water retention. Soils received the following treatments with each water quality: a single wetting event, five wetting and drying events, or five wetting and drying events followed by leaching with salt-free water. Treated samples were then resaturated with the final treatment water and equilibrated to -10, -33, -100, -500, or -1,500 kPa. At all potentials, soil water retention increased significantly with increasing clay content. Drought-prone soils lost water-holding capacity between saturation and field capacity with repeated wetting and drying, whereas finer textured soils withstood this treatment better and had increased water-retention capacity at lower matric potentials.

  12. Ecological traits of planktonic viruses and prokaryotes along a full-salinity gradient.

    PubMed

    Bettarel, Yvan; Bouvier, Thierry; Bouvier, Corinne; Carré, Claire; Desnues, Anne; Domaizon, Isabelle; Jacquet, Stéphan; Robin, Agnès; Sime-Ngando, Télesphore

    2011-05-01

    Virus-prokaryote interactions were investigated in four natural sites in Senegal (West Africa) covering a salinity gradient ranging from brackish (10‰) to near salt saturation (360‰). Both the viral and the prokaryote communities exhibited remarkable differences in their physiological, ecological and morphological traits along the gradient. Above 240‰ salinity, viral and prokaryotic abundance increased considerably with the emergence of (1) highly active square haloarchaea and of (2) viral particles with pleiomorphic morphologies (predominantly spindle, spherical and linear shaped). Viral life strategies also showed some salinity-driven dependence, switching from a prevalence of lytic to lysogenic modes of infection at the highest salinities. Interestingly, the fraction of lysogenized cells was positively correlated with the proportion of square cells. Overall, the extraordinary abundance of viruses in hypersaline systems (up to 6.8 × 10(8) virus-like particles per milliliter) appears to be partly explained by their high stability and specific ability to persist and proliferate in these apparently restrictive habitats. PMID:21255052

  13. An approach to the field study of hydraulic gradients in variable- salinity ground water

    USGS Publications Warehouse

    Hickey, J.J.

    1989-01-01

    A field study approach is proposed for reliably estimating hydraulic gradients in subregions within a region of variable-salinity ground water. It is based upon Hubbert's concept about the kind of density distributions that are required for ground water to have a potential. The approach consists of dividing a region of variable-salinity ground water into subregions with constant density, subregions with only vertical variations in density, and subregions with vertical and lateral variations in density before determining magnitude and direction of hydraulic gradients. The approach was applied to an unconfined coastal aquifer and also to a confined and layered coastal aquifer that is used for sub-surface injection. As the two applications show, the analysis of water levels and pressures from subregions with constant or approximately constant density and the analysis of pressures from subregions with only vertical variations in density provide simple and direct means for deducing the characteristics of hydraulic gradients within a region of variable-salinity ground water. -from Author

  14. High-performance ionic diode membrane for salinity gradient power generation.

    PubMed

    Gao, Jun; Guo, Wei; Feng, Dan; Wang, Huanting; Zhao, Dongyuan; Jiang, Lei

    2014-09-01

    Salinity difference between seawater and river water is a sustainable energy resource that catches eyes of the public and the investors in the background of energy crisis. To capture this energy, interdisciplinary efforts from chemistry, materials science, environmental science, and nanotechnology have been made to create efficient and economically viable energy conversion methods and materials. Beyond conventional membrane-based processes, technological breakthroughs in harvesting salinity gradient power from natural waters are expected to emerge from the novel fluidic transport phenomena on the nanoscale. A major challenge toward real-world applications is to extrapolate existing single-channel devices to macroscopic materials. Here, we report a membrane-scale nanofluidic device with asymmetric structure, chemical composition, and surface charge polarity, termed ionic diode membrane (IDM), for harvesting electric power from salinity gradient. The IDM comprises heterojunctions between mesoporous carbon (pore size ∼7 nm, negatively charged) and macroporous alumina (pore size ∼80 nm, positively charged). The meso-/macroporous membrane rectifies the ionic current with distinctly high ratio of ca. 450 and keeps on rectifying in high-concentration electrolytes, even in saturated solution. The selective and rectified ion transport furthermore sheds light on salinity-gradient power generation. By mixing artificial seawater and river water through the IDM, substantially high power density of up to 3.46 W/m(2) is discovered, which largely outperforms some commercial ion-exchange membranes. A theoretical model based on coupled Poisson and Nernst-Planck equations is established to quantitatively explain the experimental observations and get insights into the underlying mechanism. The macroscopic and asymmetric nanofluidic structure anticipates wide potentials for sustainable power generation, water purification, and desalination. PMID:25137214

  15. Macrofaunal communities in the habitats of intertidal marshes along the salinity gradient of the Schelde estuary

    NASA Astrophysics Data System (ADS)

    Hampel, Henrietta; Elliott, M.; Cattrijsse, A.

    2009-08-01

    The macrobenthos is important in benthic remineralization processes; it represents a trophic link and is also often used as a bio-indicator in monitoring programs. Variations of the environmental parameters strongly influence the structure of the macrobenthic communities in the marshes and since macrobenthos is the most important food item for marsh-visiting fish species in the Schelde, the variation in food resources can have a strong effect on the higher trophic level. The present study deals with the variation in macrobenthic communities in different habitats of intertidal marshes along the salinity gradient and the differences between the marsh creeks and the intertidal part of the estuary. The study measured density and species richness together with the biomass, and sampled a large intertidal channel and a smaller creek within five marshes along the salinity gradient of the Schelde estuary every six weeks between May and October in 2000. The small creeks had a smaller grain size and higher organic matter content than those in the large channel although the differences in the environmental parameters did not explain the different communities in the two habitats. Marshes had distinct macrobenthic communities but the abundance of macrofauna fluctuated along the estuary without an identifiable spatial trend. In contrast, the total biomass increased towards the euhaline area due to the domination of Nereis diversicolor. Diversity showed a significant positive correlation with the salinity. Comparison of the macrofaunal communities in the marsh with those on the intertidal flats of the estuary indicated similar trends in density, biomass and diversity along the salinity gradient. The density was similar in both habitats whereas biomass was much higher in the intertidal habitats of the estuary, partly due to the higher biomass of molluscs and annelids. Diversity indices were higher in the marsh, and the freshwater area had more species than in the estuary.

  16. Archaeal community diversity and abundance changes along a natural salinity gradient in estuarine sediments

    PubMed Central

    Webster, Gordon; O'Sullivan, Louise A.; Meng, Yiyu; Williams, Angharad S.; Sass, Andrea M.; Watkins, Andrew J.; Parkes, R. John; Weightman, Andrew J.

    2014-01-01

    Archaea are widespread in marine sediments, but their occurrence and relationship with natural salinity gradients in estuarine sediments is not well understood. This study investigated the abundance and diversity of Archaea in sediments at three sites [Brightlingsea (BR), Alresford (AR) and Hythe (HY)] along the Colne Estuary, using quantitative real-time PCR (qPCR) of 16S rRNA genes, DNA hybridization, Archaea 16S rRNA and mcrA gene phylogenetic analyses. Total archaeal 16S rRNA abundance in sediments were higher in the low-salinity brackish sediments from HY (2–8 × 107 16S rRNA gene copies cm−3) than the high-salinity marine sites from BR and AR (2 × 104–2 × 107 and 4 × 106–2 × 107 16S rRNA gene copies cm−3, respectively), although as a proportion of the total prokaryotes Archaea were higher at BR than at AR or HY. Phylogenetic analysis showed that members of the ‘Bathyarchaeota’ (MCG), Thaumarchaeota and methanogenic Euryarchaeota were the dominant groups of Archaea. The composition of Thaumarchaeota varied with salinity, as only ‘marine’ group I.1a was present in marine sediments (BR). Methanogen 16S rRNA genes from low-salinity sediments at HY were dominated by acetotrophic Methanosaeta and putatively hydrogentrophic Methanomicrobiales, whereas the marine site (BR) was dominated by mcrA genes belonging to methylotrophic Methanococcoides, versatile Methanosarcina and methanotrophic ANME-2a. Overall, the results indicate that salinity and associated factors play a role in controlling diversity and distribution of Archaea in estuarine sediments. PMID:25764553

  17. Biochemical adaptation of phytoplankton to salinity and nutrient gradients in a coastal solar saltern, Tunisia

    NASA Astrophysics Data System (ADS)

    Abid, Olfa; Sellami-Kammoun, Alya; Ayadi, Habib; Drira, Zaher; Bouain, Abderrahmen; Aleya, Lotfi

    2008-11-01

    The distribution of protein and carbohydrate concentrations of the particulate matter (size fraction: 0.45-160 μm) was studied, from 22 January 2003 to 02 December 2003, in three ponds of increasing salinity in the Sfax solar saltern (Tunisia). The coupling of N/P: DIN (DIN = NO 2- + NO 3- + NH 4+) to DIP (DIP = PO 43-) with P/C: protein/carbohydrates ratios along salinity gradient allowed the discrimination of three types of ecosystems. Pond A1 (mean salinity: 45.0 ± 5.4) having marine characteristics showed enhanced P/C ratios during a diatom bloom. N/P and P/C ratios were closely coupled throughout the sampling period, suggesting that the nutritional status is important in determining the seasonal change in the phytoplankton community in pond A1. In pond A16 (mean salinity: 78.7 ± 8.8), despite the high nitrate load, P/C ratios were overall lower than in pond A1. This may be explained by the fact that dinoflagellates, which were the most abundant phytoplankton in pond A16 might be strict heterotrophs and/or mixotrophs, and so they may have not contributed strongly to anabolic processes. Also, N/P and P/C ratios were uncoupled, suggesting that cells in pond A16 were stressed due to the increased salinity caused by water evaporation, and so cells synthesized reserve products such as carbohydrates. In pond M2 (mean salinity: 189.0 ± 13.8), P/C levels were higher than those recorded in either pond A1 or A16. N/P and P/C were more coupled than in pond A16. Species in the hypersaline pond seemed paradoxally less stressed than in pond A16, suggesting that salt-tolerant extremophile species overcome hypersaline constraints and react metabolically by synthesizing carbohydrates and proteins.

  18. Methane fluxes along a salinity gradient on a restored salt marsh, Harpswell, ME

    NASA Astrophysics Data System (ADS)

    Gunn, Cailene; Johnson, Beverly, ,, Dr.; Dostie, Phil; Bohlen, Curtis; Craig, Matthew

    2016-04-01

    This study functions as a pilot project to understand the relationship between salinity and methane emissions on a recently restored salt marsh in Casco Bay, Maine. Salt marshes are dynamic and highly productive ecosystems that provide a multitude of ecosystem services including nutrient filtration, storm-water buffering and carbon sequestration. These ecosystems are highly susceptible to anthropogenic alteration. The emplacement of causeways and narrow culverts, restricts tidal flow and leads to loss of healthy salinity gradients. Consequently, numerous salt marshes have experienced increases in freshwater vegetation growth as a result of coastal population expansion. Recent restoration efforts on Long Marsh, Harpswell, ME replaced a severely undersized culvert with a larger one in February, 2014. The salinity gradient has since been restored along much of the marsh, and freshwater vegetation that encroached on the marsh platform has died back. Vegetation and salinity are key indicators and drivers of CH4 emissions on salt marshes. Using static gas chambers, we quantified CH4 fluxes along two transects at five diverse sites ranging from healthy marsh (salinity of 27 to 31 psu) with Spartina vegetation, to regions invaded by Typha and other freshwater vegetation (salinity of 0 to 4 psu). Sampling was executed in the months of July, August and October. CH4 concentrations were determined using a gas chromatograph with a flame-ionization detector. Preliminary findings suggest reintroduction of healthy tidal flows into the marsh inhibits CH4 production, where the lowest fluxes with least variability were observed at the most saline sites with Spartina vegetation. The largest range of CH4 fluxes exhibited emissions from 0.75 μmol CH4/m2/hr to 518.4 μmol CH4/m2/hr at the Typha dominated sites from July to October. Fluxes at the saltwater and brackish regions were far less variable with ranges from 0.94 μmol CH4/m2/hr to 8.2 μmol CH4/m2/hr and 2.6 to 9.5 μmol CH4/m2

  19. Spatial distribution of subtidal Nematoda communities along the salinity gradient in southern European estuaries

    NASA Astrophysics Data System (ADS)

    Adão, Helena; Alves, Ana Sofia; Patrício, Joana; Neto, João Magalhães; Costa, Maria José; Marques, João Carlos

    2009-03-01

    This study investigated the spatial distribution of subtidal nematode communities along the salinity gradients of two Portuguese estuaries exposed to different degrees of anthropogenic stress: the Mira and the Mondego. The nematode communities were mainly composed of Sabatieria, Metachromadora, Daptonema, Anoplostoma, Sphaerolaimus and Terschellingia species, closely resembling the communities of Northern European estuaries. In both estuaries, nematode density and community composition followed the salinity gradient, naturally establishing three distinct estuarine sections: (i) freshwater and oligohaline - characterised by the presence of freshwater nematodes, low nematode density and diversity; (ii) mesohaline - dominated by Terschellingia, Sabatieria and Daptonema, with low total density and diversity; and (iii) polyhaline and euhaline - where nematodes reached the highest density and diversity, and Paracomesoma, Synonchiella, and Odontophora were dominant. Despite the similarities in community composition and total nematode density, the proportion of different nematode feeding types were remarkably different in the two estuaries. In Mira, selective deposit feeders were dominant in the oligohaline section, while non-selective deposit feeders were dominant in the other sections. On the contrary, in the Mondego estuary, epigrowth-feeders and omnivores/predators were dominant in the freshwater sections and in the euhaline sector of the southern arm. Differences observed along each estuarine gradient were much stronger than overall differences between the two estuaries. In the Mondego estuary, the influence of anthropogenic stressors seemed not to be relevant in determining the nematodes' spatial distribution patterns, therefore suggesting that mesoscale variability responded essentially to natural stressors, characteristic of estuarine gradients. Nevertheless, the proportion of the different feeding types was different between the two estuaries, indicating that the

  20. Microbial Biogeography along an Estuarine Salinity Gradient: Combined Influences of Bacterial Growth and Residence Time

    PubMed Central

    Crump, Byron C.; Hopkinson, Charles S.; Sogin, Mitchell L.; Hobbie, John E.

    2004-01-01

    Shifts in bacterioplankton community composition along the salinity gradient of the Parker River estuary and Plum Island Sound, in northeastern Massachusetts, were related to residence time and bacterial community doubling time in spring, summer, and fall seasons. Bacterial community composition was characterized with denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA. Average community doubling time was calculated from bacterial production ([14C]leucine incorporation) and bacterial abundance (direct counts). Freshwater and marine populations advected into the estuary represented a large fraction of the bacterioplankton community in all seasons. However, a unique estuarine community formed at intermediate salinities in summer and fall, when average doubling time was much shorter than water residence time, but not in spring, when doubling time was similar to residence time. Sequencing of DNA in DGGE bands demonstrated that most bands represented single phylotypes and that matching bands from different samples represented identical phylotypes. Most river and coastal ocean bacterioplankton were members of common freshwater and marine phylogenetic clusters within the phyla Proteobacteria, Bacteroidetes, and Actinobacteria. Estuarine bacterioplankton also belonged to these phyla but were related to clones and isolates from several different environments, including marine water columns, freshwater sediments, and soil. PMID:15006771

  1. Diversity of Pico- to Mesoplankton along the 2000 km Salinity Gradient of the Baltic Sea.

    PubMed

    Hu, Yue O O; Karlson, Bengt; Charvet, Sophie; Andersson, Anders F

    2016-01-01

    Microbial plankton form the productive base of both marine and freshwater ecosystems and are key drivers of global biogeochemical cycles of carbon and nutrients. Plankton diversity is immense with representations from all major phyla within the three domains of life. So far, plankton monitoring has mainly been based on microscopic identification, which has limited sensitivity and reproducibility, not least because of the numerical majority of plankton being unidentifiable under the light microscope. High-throughput sequencing of taxonomic marker genes offers a means to identify taxa inaccessible by traditional methods; thus, recent studies have unveiled an extensive previously unknown diversity of plankton. Here, we conducted ultra-deep Illumina sequencing (average 10(5) sequences/sample) of rRNA gene amplicons of surface water eukaryotic and bacterial plankton communities sampled in summer along a 2000 km transect following the salinity gradient of the Baltic Sea. Community composition was strongly correlated with salinity for both bacterial and eukaryotic plankton assemblages, highlighting the importance of salinity for structuring the biodiversity within this ecosystem. In contrast, no clear trends in alpha-diversity for bacterial or eukaryotic communities could be detected along the transect. The distribution of major planktonic taxa followed expected patterns as observed in monitoring programs, but groups novel to the Baltic Sea were also identified, such as relatives to the coccolithophore Emiliana huxleyi detected in the northern Baltic Sea. This study provides the first ultra-deep sequencing-based survey on eukaryotic and bacterial plankton biogeography in the Baltic Sea. PMID:27242706

  2. Diversity of Pico- to Mesoplankton along the 2000 km Salinity Gradient of the Baltic Sea

    PubMed Central

    Hu, Yue O. O.; Karlson, Bengt; Charvet, Sophie; Andersson, Anders F.

    2016-01-01

    Microbial plankton form the productive base of both marine and freshwater ecosystems and are key drivers of global biogeochemical cycles of carbon and nutrients. Plankton diversity is immense with representations from all major phyla within the three domains of life. So far, plankton monitoring has mainly been based on microscopic identification, which has limited sensitivity and reproducibility, not least because of the numerical majority of plankton being unidentifiable under the light microscope. High-throughput sequencing of taxonomic marker genes offers a means to identify taxa inaccessible by traditional methods; thus, recent studies have unveiled an extensive previously unknown diversity of plankton. Here, we conducted ultra-deep Illumina sequencing (average 105 sequences/sample) of rRNA gene amplicons of surface water eukaryotic and bacterial plankton communities sampled in summer along a 2000 km transect following the salinity gradient of the Baltic Sea. Community composition was strongly correlated with salinity for both bacterial and eukaryotic plankton assemblages, highlighting the importance of salinity for structuring the biodiversity within this ecosystem. In contrast, no clear trends in alpha-diversity for bacterial or eukaryotic communities could be detected along the transect. The distribution of major planktonic taxa followed expected patterns as observed in monitoring programs, but groups novel to the Baltic Sea were also identified, such as relatives to the coccolithophore Emiliana huxleyi detected in the northern Baltic Sea. This study provides the first ultra-deep sequencing-based survey on eukaryotic and bacterial plankton biogeography in the Baltic Sea. PMID:27242706

  3. Uranium geochemistry on the Amazon shelf: Chemical phase partitioning and cycling across a salinity gradient

    NASA Astrophysics Data System (ADS)

    Swarzenski, P. W.; McKee, B. A.; Booth, J. G.

    1995-01-01

    The size distribution of U was examined in surface waters of the Amazon shelf. Water samples were collected during a low discharge river stage across a broad salinity gradient (0.3-35.4%) and fractionated by planar filtration and tangential-flow ultrafiltration into (1) solution (Us, <10,000 MW; ˜1-10 nm), (2) colloidal (Uc 10,000 MW-0.4 μm), (3) dissolved (Ud, <0.4 μm), and (4) particulate (Up, >0.4 μm) phases. Concentrations of colloidal U comprise up to 92% of the dissolved U fraction at the river mouth and attain highest values (˜0.45 μg/L) in the productive, biogenic region of the Amazon shelf (salinities above ˜20%). Ud and Uc distributions are highly nonconservative relative to ideal dilution of river water and seawater, indicating extensive removal at salinities below ˜10%. The distribution of Us also shows some nonconservative behavior, yet removal, if any, is minimal. Saltwater-induced precipitation and aggregation of riverine colloidal material is most likely the dominant mechanism of U removal in the low salinity, terrigenous region of the Amazon shelf. There is evidence of a substantial colloidal U input (˜245% of the riverine Uc flux into surface waters above 5%. Such Uc enrichment most likely is the result of colloidal U-rich porewater diffusion/advection from the seabed and fluid muds or shelf-wide particle-colloid disaggregation. Removal of solution and dissolved phase U via a colloidal intermediate and Uc aggregation was examined in terms of coagulation theory. The highly reactive nature of all U phases on the Amazon shelf suggests that remobilization and fractionation of U may also occur in other river-influenced coastal environments.

  4. Shifts in the community structure and activity of anaerobic ammonium oxidation bacteria along an estuarine salinity gradient

    NASA Astrophysics Data System (ADS)

    Zheng, Yanling; Jiang, Xiaofen; Hou, Lijun; Liu, Min; Lin, Xianbiao; Gao, Juan; Li, Xiaofei; Yin, Guoyu; Yu, Chendi; Wang, Rong

    2016-06-01

    Anaerobic ammonium oxidation (anammox) is a major microbial pathway for nitrogen (N) removal in estuarine and coastal environments. However, understanding of anammox bacterial dynamics and associations with anammox activity remains scarce along estuarine salinity gradient. In this study, the diversity, abundance, and activity of anammox bacteria, and their potential contributions to total N2 production in the sediments along the salinity gradient (0.1-33.8) of the Yangtze estuarine and coastal zone, were studied using 16S rRNA gene clone library, quantitative polymerase chain reaction assay, and isotope-tracing technique. Phylogenetic analysis showed a significant change in anammox bacterial community structure along the salinity gradient (P < 0.01), with the dominant genus shifting from Brocadia in the freshwater region to Scalindua in the open ocean. Anammox bacterial abundance ranged from 3.67 × 105 to 8.22 × 107 copies 16S rRNA gene g-1 and related significantly with salinity (P < 0.05). The anammox activity varied between 0.08 and 6.46 nmol N g-1 h-1 and related closely with anammox bacterial abundance (P < 0.01). Contributions of anammox activity to total N loss were highly variable along the salinity gradient, ranging from 5 to 77% and were significantly negatively correlated with salinity (P < 0.01). Sediment organic matter was also recognized as an important factor in controlling the relative role of anammox to total N2 production in the Yangtze estuarine and coastal zone. Overall, our data demonstrated a biogeographical distribution of anammox bacterial diversity, abundance, and activity along the estuarine salinity gradient and suggested that salinity is a major environmental control on anammox process in the estuarine and coastal ecosystems.

  5. Genetic diversity of Saccharina latissima (Phaeophyceae) along a salinity gradient in the North Sea-Baltic Sea transition zone.

    PubMed

    Møller Nielsen, Mette; Paulino, Cristina; Neiva, João; Krause-Jensen, Dorte; Bruhn, Annette; Serrão, Ester A

    2016-08-01

    The North Sea-Baltic Sea transition zone constitutes a boundary area for the kelp species Saccharina latissima due to a strong salinity gradient operating in the area. Furthermore, the existence of S. latissima there, along Danish waters, is fairly patchy as hard bottom is scarce. In this study, patterns of genetic diversity of S. latissima populations were evaluated along the salinity gradient area of Danish waters (here designated brackish) and were compared to reference sites (here designated marine) outside the gradient area, using microsatellite markers. The results showed that the S. latissima populations were structured into two clusters corresponding to brackish versus marine sites, and that gene flow was reduced both between clusters and between populations within clusters. In addition, results provided empirical evidence that marginal populations of S. latissima in the salinity gradient area exhibited a distinct genetic structure when compared to marine ones. Brackish populations were less diverse, more related, and showed increased differentiation over distance compared to marine populations. The isolation of the brackish S. latissima populations within the salinity gradient area of Danish waters in conjunction with their general low genetic diversity makes these populations vulnerable to ongoing environmental and climate change, predicted to result in declining salinity in the Baltic Sea area that may alter the future distribution and performance of S. latissima in the area. PMID:27151230

  6. Ecohydrological Response of Trees to Leaf Wetness Gradients Under Wet and Dry Canopy Conditions in a Montane Tropical Forest

    NASA Astrophysics Data System (ADS)

    Aparecido, L. M. T.; Moore, G. W.; Miller, G. R.; Cahill, A. T.

    2014-12-01

    Wet canopy evaporation is a significant component of the water budget in rainforests. Frequent precipitation events followed by drying produce spatial and temporal variation in wet/dry forest canopy conditions that influence processes such as photosynthesis and growth. Upper canopies contribute a disproportionately large fraction of transpiration and carbon assimilation relative to lower canopy layers as exposed leaves dry more rapidly following each rain event. However, the partitioning between wet canopy evaporation and dry canopy transpiration has not been extensively studied in tropical forests. As part of a larger study in central Costa Rica aimed at improving land-surface modeling of evapotranspiration (ET) processes in tropical montane forests, we compared transpiration among trees with exposed and shaded crowns under both wet and dry canopy conditions. Transpiration was measured using 33 sap flow sensors in 20 trees (7 dominant and co-dominant, 8 mid-story, and 5 suppressed) in a mature forest stand surrounding a 40-m tower equipped with eddy covariance and micrometeorological sensors. During the wet month of July, leaves were dry 53% of the time in the upper canopy compared with only 16% of the time in the lower canopy. Dominant and co-dominant trees contributed 68% to total transpiration at this site (23% mid-story, 9% suppressed). Under dry conditions, sap flow rates of dominant and co-dominant trees were about double that of suppressed trees, while suppressed trees differed little between wet and dry days. On partially wet days, all trees had similar sap flow rates, regardless of canopy exposure, with rates nearly as low as days that were entirely wet. This behavior is due to rapid individual tree responses to the transition between wet and dry conditions, indicating that persistently wet tropical environments are uniquely adapted to short-term dryness. ET has important influence on precipitation in tropical forests through land-atmosphere interactions

  7. Thermodynamic and energy efficiency analysis of power generation from natural salinity gradients by pressure retarded osmosis.

    PubMed

    Yip, Ngai Yin; Elimelech, Menachem

    2012-05-01

    The Gibbs free energy of mixing dissipated when fresh river water flows into the sea can be harnessed for sustainable power generation. Pressure retarded osmosis (PRO) is one of the methods proposed to generate power from natural salinity gradients. In this study, we carry out a thermodynamic and energy efficiency analysis of PRO work extraction. First, we present a reversible thermodynamic model for PRO and verify that the theoretical maximum extractable work in a reversible PRO process is identical to the Gibbs free energy of mixing. Work extraction in an irreversible constant-pressure PRO process is then examined. We derive an expression for the maximum extractable work in a constant-pressure PRO process and show that it is less than the ideal work (i.e., Gibbs free energy of mixing) due to inefficiencies intrinsic to the process. These inherent inefficiencies are attributed to (i) frictional losses required to overcome hydraulic resistance and drive water permeation and (ii) unutilized energy due to the discontinuation of water permeation when the osmotic pressure difference becomes equal to the applied hydraulic pressure. The highest extractable work in constant-pressure PRO with a seawater draw solution and river water feed solution is 0.75 kWh/m(3) while the free energy of mixing is 0.81 kWh/m(3)-a thermodynamic extraction efficiency of 91.1%. Our analysis further reveals that the operational objective to achieve high power density in a practical PRO process is inconsistent with the goal of maximum energy extraction. This study demonstrates thermodynamic and energetic approaches for PRO and offers insights on actual energy accessible for utilization in PRO power generation through salinity gradients. PMID:22463483

  8. Ultrastructural and physiological responses of potato (Solanum tuberosum L.) plantlets to gradient saline stress

    PubMed Central

    Gao, Hui-Juan; Yang, Hong-Yu; Bai, Jiang-Ping; Liang, Xin-Yue; Lou, Yan; Zhang, Jun-Lian; Wang, Di; Zhang, Jin-Lin; Niu, Shu-Qi; Chen, Ying-Long

    2015-01-01

    Salinity is one of the major abiotic stresses that impacts plant growth and reduces the productivity of field crops. Compared to field plants, test tube plantlets offer a direct and fast approach to investigate the mechanism of salt tolerance. Here we examined the ultrastructural and physiological responses of potato (Solanum tuberosum L. c.v. “Longshu No. 3”) plantlets to gradient saline stress (0, 25, 50, 100, and 200 mM NaCl) with two consequent observations (2 and 6 weeks, respectively). The results showed that, with the increase of external NaCl concentration and the duration of treatments, (1) the number of chloroplasts and cell intercellular spaces markedly decreased, (2) cell walls were thickened and even ruptured, (3) mesophyll cells and chloroplasts were gradually damaged to a complete disorganization containing more starch, (4) leaf Na and Cl contents increased while leaf K content decreased, (5) leaf proline content and the activities of catalase (CAT) and superoxide dismutase (SOD) increased significantly, and (6) leaf malondialdehyde (MDA) content increased significantly and stomatal area and chlorophyll content decline were also detected. Severe salt stress (200 mM NaCl) inhibited plantlet growth. These results indicated that potato plantlets adapt to salt stress to some extent through accumulating osmoprotectants, such as proline, increasing the activities of antioxidant enzymes, such as CAT and SOD. The outcomes of this study provide ultrastructural and physiological insights into characterizing potential damages induced by salt stress for selecting salt-tolerant potato cultivars. PMID:25628634

  9. [Porewater Dissolved Methane in Cyperus malaccensis Marshes Along Salinity Gradient in the Minjiang River Estuary].

    PubMed

    Yang, Ping; Zhang, Zi-chuan; Du, Wei-ning; Huang, Jia-fang; Tong, Chuan

    2015-10-01

    Physicochemical properties of soil and dissolved methane concentrations of porewater in the sediments of the Cyperus malaccensis marshes along a salinity gradient in the Minjiang River estuary were evaluated, and the spatial-temporal characteristics and main impact factors were discussed. The average concentrations of dissolved methane in porewater were 331.18, 299.94 and 638.58 μmol x L(-1), respectively in the Shanyutan, Bianfuzhou and Xiayangzhou wetlands in summer. In the winter, they were 9.04, 266.67 and 322.68 μmol x L(-1), respectively. The dissolved methane concentration in porewater was higher in summer than those in winter (P < 0.05). Overall, the concentrations of dissolved methane in porewatdr showed an increasing trend from brackish to freshwater marshes. Multivariate statistics analysis showed that the concentrations of dissolved methane in porewater was positively correlated with soils temperature and DOC (P < 0.05), but negatively correlated with soils pH, salinity, and the concentrations of porewater SO4(2-) and Cl-. Spatial-temporal distribution of porewater dissolved methane in estuarine marshes represents a final result of multiple factors, including soil physicochemical properties and hydrodynamic condition. PMID:26841594

  10. Ultrastructural and physiological responses of potato (Solanum tuberosum L.) plantlets to gradient saline stress.

    PubMed

    Gao, Hui-Juan; Yang, Hong-Yu; Bai, Jiang-Ping; Liang, Xin-Yue; Lou, Yan; Zhang, Jun-Lian; Wang, Di; Zhang, Jin-Lin; Niu, Shu-Qi; Chen, Ying-Long

    2014-01-01

    Salinity is one of the major abiotic stresses that impacts plant growth and reduces the productivity of field crops. Compared to field plants, test tube plantlets offer a direct and fast approach to investigate the mechanism of salt tolerance. Here we examined the ultrastructural and physiological responses of potato (Solanum tuberosum L. c.v. "Longshu No. 3") plantlets to gradient saline stress (0, 25, 50, 100, and 200 mM NaCl) with two consequent observations (2 and 6 weeks, respectively). The results showed that, with the increase of external NaCl concentration and the duration of treatments, (1) the number of chloroplasts and cell intercellular spaces markedly decreased, (2) cell walls were thickened and even ruptured, (3) mesophyll cells and chloroplasts were gradually damaged to a complete disorganization containing more starch, (4) leaf Na and Cl contents increased while leaf K content decreased, (5) leaf proline content and the activities of catalase (CAT) and superoxide dismutase (SOD) increased significantly, and (6) leaf malondialdehyde (MDA) content increased significantly and stomatal area and chlorophyll content decline were also detected. Severe salt stress (200 mM NaCl) inhibited plantlet growth. These results indicated that potato plantlets adapt to salt stress to some extent through accumulating osmoprotectants, such as proline, increasing the activities of antioxidant enzymes, such as CAT and SOD. The outcomes of this study provide ultrastructural and physiological insights into characterizing potential damages induced by salt stress for selecting salt-tolerant potato cultivars. PMID:25628634

  11. Hydrodynamics, temperature/salinity variability and residence time in the Chilika lagoon during dry and wet period: Measurement and modeling

    NASA Astrophysics Data System (ADS)

    Mahanty, M. M.; Mohanty, P. K.; Pattnaik, A. K.; Panda, U. S.; Pradhan, S.; Samal, R. N.

    2016-08-01

    This paper investigated the hydrodynamics, spatio-temporal variability of temperature/salinity and the residence time of tracer concentrations in a largest brackish water coastal lagoon in Asia, namely the Chilika lagoon, India. An integrated approach combined the measurement and 2D hydrodynamic-advection/dispersion model is used to simulate circulation and temperature/salinity, and estimated the water residence time in lagoon under different forcing mechanisms, such as tide, wind and freshwater discharge during the dry and wet periods. Water circulation inside the lagoon is simulated when wind is included with the tide only forcing during dry period, and freshwater influx is included with the tide and wind forcing during wet period. Under the realistic forcing conditions, the computed temporal variability of water temperature and salinity are well correlated with the measurements in both the periods. The spatial variations of water temperature within the lagoon is influenced by the meteorological conditions, tide and freshwater influx as well as the shallowness of the lagoon, whereas the salinity is spatially controlled by the freshwater influx from the riverine system and seawater intrusion through the tidal inlets. The numerical model results show that in the Chilika lagoon tidal and river influx affect significantly the residence time spatially, and is site specific. The residence time varies from values of 4-5 days in the outer channel (OC) and 132 days at the northern sector (NS) in the main body of lagoon. The current study represents a first attempt to use a combined model approach, which is therefore, a useful tool to support the ecological implication of the lagoon ecosystem.

  12. Uranium geochemistry on the Amazon shelf: Chemical phase partitioning and cycling across a salinity gradient

    SciTech Connect

    Swarzenski, P.W.; McKee, B.A.; Booth, J.G.

    1995-01-01

    The size distribution of U was examined in surface waters of the Amazon shelf. Water samples were collected during a low discharge river stage across a broad salinity gradient (0.3-35.4%) and fractionated by planar filtration and tangential-flow ultrafiltration into (1) solution (U{sub s}, <10,000 MW; {approximately}1-10 nm), (2) colloidal (U{sub c}, 10,000 MW-0.4 {mu}m), (3) dissolved (U{sub d} <0.4 {mu}m), and (4) particulate (U{sub p} >0.4 {mu}m) phases. Concentrations of colloidal U comprise up to 92% of the dissolved U fraction at the river mouth and attain highest values ({approximately}0.45 {mu}g/L) in the productive, biogenic region of the Amazon shelf (salinities above {approximately}20%). U{sub d} and U{sub c} distributions are highly nonconservative relative to ideal dilution of river water and seawater, indicating extensive removal at salinities below {approximately}10%. The distribution of U{sub s} also shows some nonconservative behavior, yet removal, if any, is minimal. Saltwater-induced precipitation and aggregation of riverine colloidal material is most likely the dominant mechanism of U removal in the low salinity, terrigenous region of the Amazon shelf. There is evident of a substantial colloidal U input ({approximately}245% of the riverine U{sub c} flux) into surface waters above 5%. Such U{sub c} enrichment most likely is the result of colloidal U-rich porewater diffusion/advection from the seabed and fluid muds or shelf-wide particle-colloid disaggregation. Removal of solution and dissolved phase U via a colloidal intermediate and U{sub c} aggregation in terms of coagulation phase U via a colloidal intermediate and U{sub c} aggregation was examined in terms of coagulation theory. The high reactive nature of all U phases on the Amazon shelf suggests that remobilization and fractionation of U may also occur in other river-influenced coastal environments.

  13. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils.

    PubMed

    Lipson, David A; Raab, Theodore K; Parker, Melanie; Kelley, Scott T; Brislawn, Colin J; Jansson, Janet

    2015-08-01

    This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes, dominated by fermenters (Bacteroidetes and Firmicutes). PMID:26034016

  14. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

    SciTech Connect

    Lipson, David A.; Raab, Theodore K.; Parker, Melanie; Kelley, Scott T.; Brislawn, Colin J.; Jansson, Janet K.

    2015-08-01

    Summary This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes,

  15. Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

    SciTech Connect

    Lipson, David A.; Raab, Theodore K.; Parker, Melanie; Kelley, Scott T.; Brislawn, Colin J.; Jansson, Janet K.

    2015-07-21

    This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska, and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography, but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes, dominated by fermenters (Bacteroidetes and Firmicutes).

  16. Dietary flexibility in three representative waterbirds across salinity and depth gradients in salt ponds of San Francisco Bay

    USGS Publications Warehouse

    Takekawa, J.Y.; Miles, A.K.; Tsao-Melcer, D. C.; Schoellhamer, D.H.; Fregien, S.; Athearn, N.D.

    2009-01-01

    Salt evaporation ponds have existed in San Francisco Bay, California, for more than a century. In the past decade, most of the salt ponds have been retired from production and purchased for resource conservation with a focus on tidal marsh restoration. However, large numbers of waterbirds are found in salt ponds, especially during migration and wintering periods. The value of these hypersaline wetlands for waterbirds is not well understood, including how different avian foraging guilds use invertebrate prey resources at different salinities and depths. The aim of this study was to investigate the dietary flexibility of waterbirds by examining the population number and diet of three feeding guilds across a salinity and depth gradient in former salt ponds of the Napa-Sonoma Marshes. Although total invertebrate biomass and species richness were greater in low than high salinity salt ponds, waterbirds fed in ponds that ranged from low (20 g l-1) to very high salinities (250 g l -1). American avocets (surface sweeper) foraged in shallow areas at pond edges and consumed a wide range of prey types (8) including seeds at low salinity, but preferred brine flies at mid salinity (40-80 g l-1). Western sandpipers (prober) focused on exposed edges and shoal habitats and consumed only a few prey types (2-4) at both low and mid salinities. Suitable depths for foraging were greatest for ruddy ducks (diving benthivore) that consumed a wide variety of invertebrate taxa (5) at low salinity, but focused on fewer prey (3) at mid salinity. We found few brine shrimp, common in higher salinity waters, in the digestive tracts of any of these species. Dietary flexibility allows different guilds to use ponds across a range of salinities, but their foraging extent is limited by available water depths. ?? 2009 USGS, US Government.

  17. Particle-Associated Archaea Across a Salinity Gradient in the Tidally Influenced Broadkill River, DE

    NASA Astrophysics Data System (ADS)

    Biddle, J.; Yoshimura, K.

    2015-12-01

    Particulate matter in marine and aquatic systems has been shown to host microbial communities distinct from the free-living fraction, which is attributed to the concentration of nutrients and the presence of microhabitats within these particles. Some of these microhabitats include anoxic zones within the interior of the particles, allowing the presence of anaerobic microbes. While several studies have explored the bacterial community composition of particulate matter in marine, estuarine, and riverine systems, there have been fewer studies analyzing the archaeal community. As such, the implication of particle-associated anaerobic archaea in an oxygenated water column environment has not been fully explored. We investigated near shore particle-associated archaea to determine the extent to which the potential anaerobic habitat of particles has in allowing global distribution of anaerobic sediment associated archaea. In this study, the archaeal community structure of size-fractioned particles was analyzed for the presence of archaeal groups along a salinity gradient in the tidally influenced Broadkill River. Four freshwater to brackish stations were analyzed as well as one marine station. It was found that members of methanogen groups and the Miscellaneous Crenarchaeota Group were preferentially enriched on larger particles in fresh and brackish river water, but the community at the marine station was consistent between particle sizes with very few members of anaerobic sedimentary groups present. These results suggest that larger particles may have a greater potential for an anaerobic interior habitat and that in addition to salinity, particle composition may be a factor that dictates which archaeal groups can thrive. The presence of anaerobic sedimentary archaeal groups within larger particles also suggests the plausibility for entrained particulate matter as a transport and distribution mechanism for sedimentary archaeal groups throughout the ocean.

  18. Sensitivity to cadmium along a salinity gradient in populations of the periwinkle, Littorina littorea, using time-to-death analysis.

    PubMed

    De Wolf, Hans; Backeljau, Thierry; Blust, Ronny

    2004-02-25

    In this study, we assessed the combined effect of Cd concentration and salinity, on Cd uptake and mortality rate of Littorina littorea, collected along a salinity and pollution gradient in the Western Scheldt estuary (The Netherlands). Animals kept at their field salinity levels were exposed to three Cd concentrations (i.e. 10, 40 and 320 microM), while animals kept in 10 microM of Cd were subjected to five salinity treatments (i.e. 15, 20, 25, 30 and 35 per thousand). Mortality was recorded every 24h and Cd body burdens were measured with ICP-AES. Time-to-death data were analysed via Cox proportional hazard models, including the co-variates "site-Cd treatment" in the Cd experiment and "site-salinity treatment" in the salinity experiment. "Cd-treatment" and "field-salinity" affected mortality rates significantly in the Cd experiment, such that the mortality risk increased by 2.3 times when salinity was lowered from 35 to 15 per thousand, while it decreased by 19.7 times when Cd dropped from 320 to 10 microM. "Site" did not significantly affect the mortality risk in the salinity experiment but affected time-to-death via its interaction with the "salinity-treatment". Generally, mortality did not occur at a given threshold Cd tissue level, but changed over time and treatments, in function of the site. The results demonstrate the importance of the animals' environmental history and illustrate the usefulness of time-to-death analyses in ecotoxicological experiments. PMID:15129767

  19. Distinctive stable isotope ratios in important zooplankton species in relation to estuarine salinity gradients: Potential tracer of fish migration

    NASA Astrophysics Data System (ADS)

    Suzuki, Keita W.; Kasai, Akihide; Isoda, Takane; Nakayama, Kouji; Tanaka, Masaru

    2008-07-01

    To assess the potential of stable isotope ratios as an indicator of fish migration within estuaries, stable isotope ratios in important zooplankton species were analyzed in relation to estuarine salinity gradients. Gut contents from migratory juveniles of the euryhaline marine fish Lateolabrax japonicus were examined along the Chikugo River estuary of the Ariake Sea, which has the most developed estuarine turbidity maximum (ETM) in Japan. Early juveniles in March and April preyed primarily on two copepod species; Sinocalanus sinensis at lower salinities and Acartia omorii at higher salinities. Late juveniles (standard length > 40 mm) at lower salinities preyed exclusively on the mysid Acanthomysis longirostris until July and complementarily on the decapod Acetes japonicus in August. These prey species were collected along the estuary during the spring-summer seasons of 2003 and 2004, and their carbon and nitrogen stable isotope ratios ( δ13C and δ15N) were evaluated. The δ13C values of prey species were distinct from each other and were primarily depleted within and in close proximity to the ETM (salinity < 10); S. sinensis (-26.6‰) < Acanthomysis longirostris (-23.3‰) < Acartia omorii (-21.1‰) < Acetes japonicus (-18.5‰). The overall gradient of δ13C with salinity occurred for all prey species and showed minor temporal fluctuations, while it was not directly influenced by the δ13C values in particulate organic matter along the estuary. In contrast to δ13C, the δ15N values of prey species did not exhibit any clear relationship with salinity. The present study demonstrated that δ13C has the potential for application as a tracer of fish migration into lower salinity areas including the ETM.

  20. Methodology for the quantitative exploration for sites for salinity-gradient solar ponds

    SciTech Connect

    Sandoval, J.A.; Goodell, P.C.; Swift, A.

    1996-12-31

    Salinity-gradient solar pond (SGSP) energy production is one of the proven solar energy technologies, however only in several instances have these ponds yet proven to be economically competitive. Electricity generation, water desalination, medium grade industrial heat production, and hydrometallurgy have been successfully demonstrated, however, on the whole the technology is seeking a niche within which to thrive and develop. The present study provides a rational basis for the selection of new SGSP sites, and a methodology has been developed to consider the multitudinous variables necessary in such a decision. Twenty physical criteria are considered in SGSP site selection. Four value and seven cost criteria have been considered in the present study. Large values of F correlate with the more favorable SGSP sites. This methodology has been applied to over 100 sites in west Texas and eastern New Mexico. Sites tested include playa lakes, salt lakes, artificial lakes, and empty ground, located both near and distal from active industrial sites in the region. Distance to potential energy user is of great importance. Hydrometallurgical processes may benefit from a SGSP during sodium sulfate production. Salt is also such an important driver in the favorability index that certain industries result with high values. Notable are the nuclear waste storage facility at the WIPP site and the potash mining industry in the Potash Enclave, where salt is a waste product of their activities.

  1. Contribution of trace metals in structuring in situ macroinvertebrate community composition along a salinity gradient

    SciTech Connect

    Peeters, E.T.H.M.; Gardeniers, J.J.P.; Koelmans, A.A.

    2000-04-01

    Macroinvertebrates were studied along a salinity gradient in the North Sea Canal, The Netherlands, to quantify the effect of trace metals (cadmium, copper, lead, zinc) on community composition. In addition, two methods for assessing metal bioavailability (normalizing metal concentrations on organic carbon and on the smallest sediment fraction) were compared. Factor analyses showed that normalizing trace metals resulted in an improved separation of trace metals from ecological factors (depth, organic carbon, granulometry, and chloride). The variation in the macroinvertebrate data was partitioned into four sources using partial canonical correspondence analysis, with the partitions being purely ecological factors, purely trace metals, mutual ecological factors and trace metals, and unexplained. Partial canonical correspondence analysis applied to total and normalized trace metal concentrations gave similar results in terms of unexplained variances. However, normalization on organic carbon resulted in the highest percentage of variation explained by purely ecological factors and purely trace metals. Accounting for bioavailability thus improves the identification of factors affecting the in situ community structure. Ecological factors explained 45.4% and trace metals 8.6% of the variation in the macroinvertebrate community composition in the ecosystem of the North Sea Canal. These contributions were significant, and it is concluded that trace metals significantly affected the community composition in an environment with multiple stressors. Variance partitioning is recommended for incorporation in further risk assessment studies.

  2. Hidden persistence of salinity and productivity gradients shaping pelagic diversity in highly dynamic marine ecosystems.

    PubMed

    Hidalgo, M; Reglero, P; Álvarez-Berastegui, D; Torres, A P; Álvarez, I; Rodriguez, J M; Carbonell, A; Balbín, R; Alemany, F

    2015-03-01

    While large-scale patterns of pelagic marine diversity are generally well described, they remain elusive at regional-scale given the high temporal and spatial dynamics of biological and local oceanographic processes. We here evaluated whether the main drivers of pelagic diversity can be more pervasive than expected at regional scale, using a meroplankton community of a frontal system in the Western Mediterranean. We evidence that regional biodiversity in a highly dynamic ecosystem can be summarized attending to both static (bathymetric) and ephemeral (biological and hydrographical) environmental axes of seascape. This pattern can be observed irrespectively of the regional hydroclimatic scenario with distance to coast, salinity gradient and chlorophyll a concentration being the main and recurrent drivers. By contrast, their effect is overridden in common analyses given that different non-linear effects are buffered between years of contrasting scenarios, emerging the influence of secondary effects on diversity. We conclude that community studies may reveal hidden persistent processes when they take into account different functional effects related to hydroclimatic variability. A better understanding of regional dynamics of the pelagic realm will improve our capability to forecast future responses of plankton communities as well as impacts of climate change on marine biodiversity. PMID:25617678

  3. Diversity and geochemical structuring of bacterial communities along a salinity gradient in a carbonate aquifer subject to seawater intrusion.

    PubMed

    Héry, Marina; Volant, Aurélie; Garing, Charlotte; Luquot, Linda; Elbaz Poulichet, Françoise; Gouze, Philippe

    2014-12-01

    In aquifers subject to saline water intrusion, the mixing zone between freshwater and saltwater displays strong physico-chemical gradients. Although the microbial component of these specific environments has been largely disregarded, the contribution of micro-organisms to biogeochemical reactions impacting water geochemistry has previously been conjectured. The objective of this study was to characterize and compare bacterial community diversity and composition along a vertical saline gradient in a carbonate coastal aquifer using high throughput sequencing of 16S rRNA genes. At different depths of the mixing zone, stable geochemical and hydrological conditions were associated with autochthonous bacterial communities harboring clearly distinct structures. Diversity pattern did not follow the salinity gradient, although multivariate analysis indicated that salinity was one of the major drivers of bacterial community composition, with organic carbon, pH and CO2 partial pressure. Correlation analyses between the relative abundance of bacterial taxa and geochemical parameters suggested that rare taxa may contribute to biogeochemical processes taking place at the interface between freshwater and saltwater. Bacterial respiration or alternative metabolisms such as sulfide oxidation or organic acids production may be responsible for the acidification and the resulting induced calcite dissolution observed at a specific depth of the mixing zone. PMID:25348057

  4. Authigenic apatite and octacalcium phosphate formation due to adsorption-precipitation switching across estuarine salinity gradients

    NASA Astrophysics Data System (ADS)

    Oxmann, J. F.; Schwendenmann, L.

    2015-02-01

    Mechanisms governing phosphorus (P) speciation in coastal sediments remain largely unknown due to the diversity of coastal environments and poor analytical specificity for P phases. We investigated P speciation across salinity gradients comprising diverse ecosystems in a P-enriched estuary. To determine P load effects on P speciation we compared the high P site with a low P site. Octacalcium phosphate (OCP), authigenic apatite (carbonate fluorapatite, CFAP) and detrital apatite (fluorapatite) were quantitated in addition to Al/Fe-bound P (Al/Fe-P) and Ca-bound P (Ca-P). Gradients in sediment pH strongly affected P fractions across ecosystems and independent of the site-specific total P status. We found a pronounced switch from adsorbed Al/Fe-P to mineral Ca-P with decreasing acidity from land to sea. This switch occurred at near-neutral sediment pH and has possibly been enhanced by redox-driven phosphate desorption from iron oxyhydroxides. The seaward decline in Al/Fe-P was counterbalanced by the precipitation of Ca-P. Correspondingly, two location-dependent accumulation mechanisms occurred at the high P site due to the switch, leading to elevated Al/Fe-P at pH < 6.6 (landward; adsorption) and elevated Ca-P at pH > 6.6 (seaward; precipitation). Enhanced Ca-P precipitation by increased P loads was also evident from disproportional accumulation of metastable Ca-P (Ca-Pmeta) at the high P site. Here, sediments contained on average 6-fold higher Ca-Pmeta levels compared with the low P site, although these sediments contained only 2-fold more total Ca-P than the low P sediments. Phosphorus species distributions indicated that these elevated Ca-Pmeta levels resulted from transformation of fertilizer-derived Al/Fe-P to OCP and CFAP in nearshore areas. Formation of CFAP as well as its precursor, OCP, results in P retention in coastal zones and can thus lead to substantial inorganic P accumulation in response to anthropogenic P input.

  5. Electrochemical energy generation from natural and synthetic salinity gradients using reverse electrodialysis and capacitive mixing

    NASA Astrophysics Data System (ADS)

    Hatzell, Marta C.

    Salinity gradient energy (SGE) technologies are emerging systems designed to recover energy from engineered and natural mixing processes. Two electricity producing SGE systems are reverse electrodialysis (RED) and capacitive mixing (CapMix). RED captures mixing energy using a series of ion exchange membranes that drive electrochemical reactions at redox electrodes. CapMix utilizes polarizable electrodes to store charge in the surfaces electric double layer (EDL). Energy generation can then occur when the EDL is expanded and compressed in different concentration solutions. The use of themolytic salt solutions (e.g. ammonium bicarbonate--AmB) within a RED system is promising, as AmB can be regenerated using low-grade waste--heat (e.g. 40--60°C). One disadvantage to using AmB is the potential for gas bubbles (CO2, NH3) to form within the stack. Accumulation of bubbles can impede ion migration, and reduce system performance. The management and minimization of gaseous bubbles in RED flow fields is an important operational issue, and has not previously been addressed within RED literature. Flow field design with and without spacers in a RED stack was analyzed to determine how fluid flow and geometry effected the accumulation and removal of bubbles. In addition, the performance changes, in terms of power and resistance were measured in the presence of bubbles. Gaseous bubble accumulation was minimized using short vertically aligned channels, which resulted in a reduction in the amount of the membrane area which was restricted due to bubbles from ~20% to 7%. The stack power density improved by 12% when all gaseous bubbles were removed from the cell. AmB-RED systems can potentially produce hydrogen or electrical energy through altering the cathodic reaction. With a kinetically favorable cathodic reaction (oxygen reduction reaction), the projected electrical energy generated by a single pass AmB--RED system approached 78 Wh per m--3 (low concentrate). However, when RED was

  6. On the calculation of air-sea fluxes of CO2 in the presence of temperature and salinity gradients

    NASA Astrophysics Data System (ADS)

    Woolf, D. K.; Land, P. E.; Shutler, J. D.; Goddijn-Murphy, L. M.; Donlon, C. J.

    2016-02-01

    The presence of vertical temperature and salinity gradients in the upper ocean and the occurrence of variations in temperature and salinity on time scales from hours to many years complicate the calculation of the flux of carbon dioxide (CO2) across the sea surface. Temperature and salinity affect the interfacial concentration of aqueous CO2 primarily through their effect on solubility with lesser effects related to saturated vapor pressure and the relationship between fugacity and partial pressure. The effects of temperature and salinity profiles in the water column and changes in the aqueous concentration act primarily through the partitioning of the carbonate system. Climatological calculations of flux require attention to variability in the upper ocean and to the limited validity of assuming "constant chemistry" in transforming measurements to climatological values. Contrary to some recent analysis, it is shown that the effect on CO2 fluxes of a cool skin on the sea surface is large and ubiquitous. An opposing effect on calculated fluxes is related to the occurrence of warm layers near the surface; this effect can be locally large but will usually coincide with periods of low exchange. A salty skin and salinity anomalies in the upper ocean also affect CO2 flux calculations, though these haline effects are generally weaker than the thermal effects.

  7. Influence of a Salinity Gradient on the Vessel Characters of the Mangrove Species Rhizophora mucronata

    PubMed Central

    SCHMITZ, NELE; VERHEYDEN, ANOUK; BEECKMAN, HANS; KAIRO, JAMES GITUNDU; KOEDAM, NICO

    2006-01-01

    • Background and Aims Although mangroves have been extensively studied, little is known about their ecological wood anatomy. This investigation examined the potential use of vessel density as a proxy for soil water salinity in the mangrove species Rhizophora mucronata (Rhizophoraceae) from Kenya. • Methods In a time-standardized approach, 50 wood discs from trees growing in six salinity categories were investigated. Vessel densities, and tangential and radial diameters of rainy and dry season wood of one distinct year, at three positions on the stem discs, were measured. A repeated-measures ANOVA with the prevailing salinity was performed. • Key Results Vessel density showed a significant increase with salinity, supporting its use as a prospective measure of salinity. Interestingly, the negative salinity response of the radial diameter of vessels was less striking, and tangential diameter was constant under the varying environmental conditions. An effect of age or growth rate or the presence of vessel dimorphism could be excluded as the cause of the absence of any ecological trend. • Conclusions The clear trend in vessel density with salinity, together with the absence of a growth rate and age effect, validates the potential of vessel density as an environmental proxy. However, it can only be used as a relative measure of salinity given that other environmental variables such as inundation frequency have an additional influence on vessel density. With view to a reliable, absolute proxy, future research should focus on finding wood anatomical features correlated exclusively with soil water salinity or inundation frequency. The plasticity in vessel density with differing salinity suggests a role in the establishment of a safe water transport system. To confirm this hypothesis, the role of inter-vessel pits, their relationship to the rather constant vessel diameter and the underlying physiology and cell biology needs to be examined. PMID:17062590

  8. Uranium isotope dynamics across salinity and redox gradients in a coastal aquifer: implications for the oceanic uranium budget

    NASA Astrophysics Data System (ADS)

    Linhoff, B.; Charette, M. A.; Thompson, W. G.

    2014-12-01

    To balance the ocean's uranium budget it may be necessary to invoke submarine groundwater discharge as a major source for uranium. However, uranium removal from seawater has been observed in coastal aquifers where steep redox gradients at the seawater-freshwater mixing zone result in the reduction of soluble U(IV) to insoluble U(IV). We investigated uranium cycling in groundwater within a permeable sand subterranean estuary in Waquoit Bay, MA using major and trace element chemistry as well as ∂234U measurements. Groundwater and sediment samples were collected across the seawater-freshwater mixing zone. In the groundwater samples uranium does not behave conservatively. During mixing it is removed in the intermediate salinities (3-4 m; 2-12 salinity; 0.1 nM U) and enriched in higher salinities (4-6 m; 20-25 salinity; 32 nM) while in salinities >25, uranium is again removed (7-8 m; 8 nM). Geochemical modeling suggests that U is removed at the seawater-freshwater interface by adsorption to Mn-oxides (3-4 m) while in the deeper saline aquifer (7-8 m), U is removed through reduction from U(VI) to U(IV). Surprisingly, while ∂234U is above secular equilibrium in both the freshwater and seawater, within the intermediate salinities ∂234U is depleted below secular equilibrium (as much as ∂234U = -50). Sediment samples were subjected to a partial leach to extract surface-exchangeable U. This leach was analyzed for ∂234U and found to be highly depleted (∂234U -80 - -20). Based on the depleted ∂234U of the sediment leaches and groundwater, we hypothesize that the high U concentrations observed within the intermediate salinities likely have a sediment source. This also implies that U within this intermediate salinity zone must have a long residence time relative to groundwater-surface water exchange rates. This might be possible if redox boundaries and Mn-oxides act as a barrier to U in the intermediate salinities allowing U leached from sediments to accumulate

  9. Spatial patterns in community structure of motile epibenthic fauna in coastal habitats along the Skagerrak - Baltic salinity gradient

    NASA Astrophysics Data System (ADS)

    Nohrén, Emma; Pihl, Leif; Wennhage, Håkan

    2009-08-01

    Patterns in community structure and functioning of motile epibenthic fauna were investigated in shallow (0-1 m) sediment habitats along the Skagerrak-Baltic estuarine gradient (salinity range from 4 to 34). The study area was divided into five regions, reflecting different sea-basins along the 1260 km coastline, and fauna was collected at six sites within each region. Ten replicate samples of motile epibenthic fauna were taken randomly at each site with a portable drop trap (bottom area 1 m 2) in June and September in 2004. All together, 110 taxa were found, of which 45 had a marine and 65 a limnic origin. The marine species decreased along the salinity gradient while the limnic showed the opposite pattern. Number of species and abundance of epibenthic fauna exhibited considerable local and regional variation, with a trend of increase with decreasing salinity. Fauna biomass, on the other hand was significantly higher (six times) in the Skagerrak-Kattegat area compared to the Baltic. There was a significant difference in fauna composition among regions and season, but with high similarity within the five regions, which implies that management of such coastal habitats should preferably be based on scales of a region (ca. 100 km) or smaller. Predators were the dominant functional group in all coastal regions, with a species shift from Crustacea to Insecta along the salinity gradient and with gobid fish occurring in all regions. Grazers were the second most important group in the Skagerrak-Kattegat area, but planktovores were more important in two of the Baltic regions. The importance of shallow sediment bottoms as feeding and nursery grounds for coastal fish assemblages is discussed and compared throughout the investigated area.

  10. Soil Microbial Responses to Increased Moisture and Organic Resources along a Salinity Gradient in a Polar Desert

    PubMed Central

    Van Horn, David J.; Okie, Jordan G.; Buelow, Heather N.; Gooseff, Michael N.; Barrett, John E.

    2014-01-01

    Microbial communities in extreme environments often have low diversity and specialized physiologies suggesting a limited resistance to change. The McMurdo Dry Valleys (MDV) are a microbially dominated, extreme ecosystem currently undergoing climate change-induced disturbances, including the melting of massive buried ice, cutting through of permafrost by streams, and warming events. These processes are increasing moisture across the landscape, altering conditions for soil communities by mobilizing nutrients and salts and stimulating autotrophic carbon inputs to soils. The goal of this study was to determine the effects of resource addition (water/organic matter) on the composition and function of microbial communities in the MDV along a natural salinity gradient representing an additional gradient of stress in an already extreme environment. Soil respiration and the activity of carbon-acquiring extracellular enzymes increased significantly (P < 0.05) with the addition of resources at the low- and moderate-salinity sites but not the high-salinity site. The bacterial community composition was altered, with an increase in Proteobacteria and Firmicutes with water and organic matter additions at the low- and moderate-salinity sites and a near dominance of Firmicutes at the high-salinity site. Principal coordinate analyses of all samples using a phylogenetically informed distance matrix (UniFrac) demonstrated discrete clustering among sites (analysis of similarity [ANOSIM], P < 0.05 and R > 0.40) and among most treatments within sites. The results from this experimental work suggest that microbial communities in this environment will undergo rapid change in response to the altered resources resulting from climate change impacts occurring in this region. PMID:24610850

  11. Calcium phosphate formation due to pH-induced adsorption/precipitation switching along salinity gradients

    NASA Astrophysics Data System (ADS)

    Oxmann, J. F.; Schwendenmann, L.

    2014-07-01

    Mechanisms governing phosphorus (P) speciation in coastal sediments remain unknown due to the diversity of coastal environments and poor analytical specificity for P phases. We investigated P speciation along salinity gradients comprising diverse ecosystems in a P-enriched estuary. To determine P load effects on P speciation we compared the high P site with a P-unenriched site. To improve analytical specificity, octacalcium phosphate (OCP), authigenic apatite (carbonate fluorapatite; CFAP) and detrital apatite (fluorapatite) were quantitated in addition to Al/Fe-bound P (Al/Fe-P) and Ca-bound P (Ca-P). Sediment pH primarily affected P fractions across ecosystems and independent of the P status. Increasing pH caused a pronounced downstream transition from adsorbed Al/Fe-P to mineral Ca-P. Downstream decline in Al/Fe-P was counterbalanced by the precipitation of Ca-P. This marked upstream-to-downstream switch occurred at near-neutral sediment pH and was enhanced by increased P loads. Accordingly, the site comparison indicated two location-dependent accumulation mechanisms at the P-enriched site, which mainly resulted in elevated Al/Fe-P at pH < 6.6 (upstream; adsorption) and elevated Ca-P at pH > 6.6 (downstream; precipitation). Enhanced Ca-P precipitation by increased loads was also evident from disproportional accumulation of metastable Ca-P (Ca-PMmeta). The average Ca-Pmeta concentration was six-fold, whereas total Ca-P was only twofold higher at the P-enriched site compared to the P-unenriched site. Species concentrations showed that these largely elevated Ca-Pmeta levels resulted from transformation of fertilizer-derived Al/Fe-P to OCP and CFAP due to decreasing acidity from land to the sea. Formation of OCP and CFAP results in P retention in coastal zones, which may lead to substantial inorganic P accumulation by anthropogenic P input in near-shore sediments.

  12. Thin-film composite pressure retarded osmosis membranes for sustainable power generation from salinity gradients.

    PubMed

    Yip, Ngai Yin; Tiraferri, Alberto; Phillip, William A; Schiffman, Jessica D; Hoover, Laura A; Kim, Yu Chang; Elimelech, Menachem

    2011-05-15

    Pressure retarded osmosis has the potential to produce renewable energy from natural salinity gradients. This work presents the fabrication of thin-film composite membranes customized for high performance in pressure retarded osmosis. We also present the development of a theoretical model to predict the water flux in pressure retarded osmosis, from which we can predict the power density that can be achieved by a membrane. The model is the first to incorporate external concentration polarization, a performance limiting phenomenon that becomes significant for high-performance membranes. The fabricated membranes consist of a selective polyamide layer formed by interfacial polymerization on top of a polysulfone support layer made by phase separation. The highly porous support layer (structural parameter S = 349 μm), which minimizes internal concentration polarization, allows the transport properties of the active layer to be customized to enhance PRO performance. It is shown that a hand-cast membrane that balances permeability and selectivity (A = 5.81 L m(-2) h(-1) bar(-1), B = 0.88 L m(-2) h(-1)) is projected to achieve the highest potential peak power density of 10.0 W/m(2) for a river water feed solution and seawater draw solution. The outstanding performance of this membrane is attributed to the high water permeability of the active layer, coupled with a moderate salt permeability and the ability of the support layer to suppress the undesirable accumulation of leaked salt in the porous support. Membranes with greater selectivity (i.e., lower salt permeability, B = 0.16 L m(-2) h(-1)) suffered from a lower water permeability (A = 1.74 L m(-2) h(-1) bar(-1)) and would yield a lower peak power density of 6.1 W/m(2), while membranes with a higher permeability and lower selectivity (A = 7.55 L m(-2) h(-1) bar(-1), B = 5.45 L m(-2) h(-1)) performed poorly due to severe reverse salt permeation, resulting in a similar projected peak power density of 6.1 W/m(2). PMID

  13. Electrochemical energy generation from natural and synthetic salinity gradients using reverse electrodialysis and capacitive mixing

    NASA Astrophysics Data System (ADS)

    Hatzell, Marta C.

    Salinity gradient energy (SGE) technologies are emerging systems designed to recover energy from engineered and natural mixing processes. Two electricity producing SGE systems are reverse electrodialysis (RED) and capacitive mixing (CapMix). RED captures mixing energy using a series of ion exchange membranes that drive electrochemical reactions at redox electrodes. CapMix utilizes polarizable electrodes to store charge in the surfaces electric double layer (EDL). Energy generation can then occur when the EDL is expanded and compressed in different concentration solutions. The use of themolytic salt solutions (e.g. ammonium bicarbonate--AmB) within a RED system is promising, as AmB can be regenerated using low-grade waste--heat (e.g. 40--60°C). One disadvantage to using AmB is the potential for gas bubbles (CO2, NH3) to form within the stack. Accumulation of bubbles can impede ion migration, and reduce system performance. The management and minimization of gaseous bubbles in RED flow fields is an important operational issue, and has not previously been addressed within RED literature. Flow field design with and without spacers in a RED stack was analyzed to determine how fluid flow and geometry effected the accumulation and removal of bubbles. In addition, the performance changes, in terms of power and resistance were measured in the presence of bubbles. Gaseous bubble accumulation was minimized using short vertically aligned channels, which resulted in a reduction in the amount of the membrane area which was restricted due to bubbles from ~20% to 7%. The stack power density improved by 12% when all gaseous bubbles were removed from the cell. AmB-RED systems can potentially produce hydrogen or electrical energy through altering the cathodic reaction. With a kinetically favorable cathodic reaction (oxygen reduction reaction), the projected electrical energy generated by a single pass AmB--RED system approached 78 Wh per m--3 (low concentrate). However, when RED was

  14. Distribution of macroalgae and sediment chlorophyll A along salinity and elevation gradients in Oregon tidal marshes

    EPA Science Inventory

    Algae contribute to trophic and biogeochemical processes in tidal wetlands. We investigated patterns of sediment pigment content and macroalgal abundance and diversity in marshes in four Oregon estuaries representing a variety of vegetation types, salinity regimes, and tidal ele...

  15. Spatiotemporal Distribution of Metals along a Salinity Gradient in a River Estuary of the Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    He, S.; Xu, Y. J.

    2015-12-01

    Saltwater intrusion has become a significant problem for many coastal rivers due to global climate change and the continuous sea level rise. The flocculation of dissolved metals during estuarine mixing plays a critical role in self-purification of metals. A number of studies have investigated pH and salinity effects on metal mobility. Many of these studies were conducted in a laboratory setting. The reported field studies considered only few metals and their dynamics under marginal pH / salinity variation, typically over a short period of time. Since the spring of 2013, we have been conducting a study on spatiotemporal distribution of metals along a 90-km reach of the Calcasieu River estuary in the northern Gulf of Mexico. Monthly field trips were made to conduct in-situ measurements and collect water samples at six sites along the river. In addition, sediment samples from the riverbed surface were collected at the same sites four times to assess metal accumulation. Field measurements included water temperature, pH, salinity, and specific conductivity; Water samples were analyzed for concentration of a range of metals including Al, Ba, B, Cd, Ca, Cr, Cu, Fe, Pb, Li, Mg, Mn, Ni, P, K, Si, Ag, Na, Sr, Ti, V, and Zn. The estuarine river reach showed a wide range of salinity and pH (salinity: 0.04 - 21.78 ppt; pH: 6.2-8.1), strongly affected by river hydrology and tidal mixing. Concentration and spatial distribution of the metals in river water show response to flow regimes from the low (400 cfs) to the intermediate (400-2600 cfs) and high flows. This paper presents the dynamics of the metals under varying flow, pH and salinity gradients over the seasons and discusses a potential "intrusion" of metal accumulation in riverbed upstream as sea level rise persists.

  16. Environmental tolerances of rare and common mangroves along light and salinity gradients.

    PubMed

    Dangremond, Emily M; Feller, Ilka C; Sousa, Wayne P

    2015-12-01

    Although mangroves possess a variety of morphological and physiological adaptations for life in a stressful habitat, interspecific differences in survival and growth under different environmental conditions can shape their local and geographic distributions. Soil salinity and light are known to affect mangrove performance, often in an interactive fashion. It has also been hypothesized that mangroves are intrinsically shade intolerant due to the high physiological cost of coping with saline flooded soils. To evaluate the relationship between stress tolerance and species distributions, we compared responses of seedlings of three widespread mangrove species and one narrow endemic mangrove species in a factorial array of light levels and soil salinities in an outdoor laboratory experiment. The more narrowly distributed species was expected to exhibit a lower tolerance of potentially stressful conditions. Two of the widespread species, Avicennia germinans and Lumnitzera racemosa, survived and grew well at low-medium salinity, regardless of light level, but performed poorly at high salinity, particularly under high light. The third widespread species, Rhizophora mangle, responded less to variation in light and salinity. However, at high salinity, its relative growth rate was low at every light level and none of these plants flushed leaves. As predicted, the rare species, Pelliciera rhizophorae, was the most sensitive to environmental stressors, suffering especially high mortality and reduced growth and quantum yield under the combined conditions of high light and medium-high salinity. That it only thrives under shaded conditions represents an important exception to the prevailing belief that halophytes are intrinsically constrained to be shade intolerant. PMID:26267403

  17. Ecophysiological constraints of two invasive plant species under a saline gradient: Halophytes versus glycophytes

    NASA Astrophysics Data System (ADS)

    Duarte, B.; Santos, D.; Marques, J. C.; Caçador, I.

    2015-12-01

    Salt marsh environments are harsh environments where salinity comprises one of the most important species distribution shaping factor, presenting sediment salinities from 0 to 855 mM (0-50 ppt). Invasive species have often a high colonizing potential, due to its high plasticity and adaptation ability. Spartina patens is an invasive species already spread along several Mediterranean countries, like France and Spain. Cyperus longus is typically a freshwater species that has been spreading across the Mediterranean. In order to evaluate the ecophysiological fitness of these species, mesocosmos trials were performed subjecting both species to increasing realistic salinity levels and their photochemical and biochemical feedback was evaluated. Both species presented very different behaviours. S. patens appears to be insensitive to salt stress, mostly due to elevated proline concentrations in its leaves allowing it to maintain its osmotic balance, and thus preventing the damaging of its photochemical mechanisms. C. longus, on the other hand, was highly affected by elevated salt levels mostly due to the lack of osmotic balance driven by an incapacity to counteract the elevated ionic strength of the external medium by osmocompatible solutes. S. patens is physiologically highly adapted to saline environments and thus is capable to colonize all the marsh saline environments, while C. longus appears to be an opportunistic invader colonizing the marsh during periods of lower salinities typical from rainy seasons.

  18. Are there general spatial patterns of mangrove structure and composition along estuarine salinity gradients in Todos os Santos Bay?

    NASA Astrophysics Data System (ADS)

    Costa, Patrícia; Dórea, Antônio; Mariano-Neto, Eduardo; Barros, Francisco

    2015-12-01

    Species distribution and structural patterns of mangrove fringe forests along three tropical estuaries were evaluated in northeast of Brazil. Interstitial water salinity, percentage of fine sediments and organic matter content were investigated as explanatory variables. In all estuaries (Jaguaripe, Paraguaçu and Subaé estuaries), it was observed similar distribution patterns of four mangrove species and these patterns were mostly related with interstitial water salinity. Rhizophora mangle and Avicennia schaueriana tended to dominate sites under greater marine influence (lower estuary), while Avicennia germinans and Laguncularia racemosa dominated areas under greater freshwater influence (upper estuary), although the latter showed a wider distribution over these tropical estuarine gradients. Organic matter best explained canopy height and mean height. At higher salinities, there was practically no correlation between organic matter and density, but at lower salinity, organic matter was related to decreases in abundances. The described patterns can be related to interspecific differences in salt tolerance and competitive abilities and they are likely to be found at other tropical Atlantic estuaries. Future studies should investigate anthropic influences and causal processes in order to further improve the design of monitoring and restoration projects.

  19. Dynamics and fate of SOC in tidal marshes along a salinity gradient (Scheldt estuary, Belgium)

    NASA Astrophysics Data System (ADS)

    Van de Broek, Marijn; Temmermann, Stijn; Merckx, Roel; Wang, Zhengang; Govers, Gerard

    2016-04-01

    Coastal ecosystems have been attributed the potential to store large amounts of organic carbon (OC), often referred to as blue carbon, of which a considerable amount is stored in tidal marsh soils. Large uncertainties still exist with respect to the amount and controlling factors of soil organic carbon (SOC) stored in these ecosystems. Moreover, most research has focused on SOC dynamics of saltmarshes, while brackish and freshwater marshes are often even more productive and thus receive even larger organic carbon inputs. Therefore, in this study the OC dynamics of tidal marsh soils along an estuarine gradient are studied in order to contribute to our knowledge of 1) the stocks, 2) the controlling factors and 3) the fate of SOC in tidal marshes with different environmental characteristics. This research thus contributes to a better understanding of the potential of coastal environments to store organic carbon under future climatic changes. Soil and vegetation samples are collected in tidal salt-, brackish- and freshwater marshes in the Scheldt estuary (Belgium - The Netherlands). At each tidal marsh, three replicate soil cores up to 1.5m depth in 0.03m increments are collected at locations with both a low and a high elevation. These cores are analyzed for OC, stable C and N isotopes, bulk density and texture. Incubation experiments of topsoil samples were conducted and both aboveground and belowground biomass were collected. The results show that SOC stocks (range: 13,5 - 35,4 kg OC m-2), standing biomass (range: 2000 - 7930 g DW m-2) and potential soil respiration of CO2 (range: 0,03 - 0,12 % per unit OC per day) decrease with increasing salinity. This shows that both the amount of OC from local macrophytes and the quality of the organic matter are important factors controlling the SOC stocks. In addition, based on the analysis of stable C and N isotopes, it appears that when a significant fraction of SOC is derived from local macrophytes, higher SOC stocks are

  20. Local adaptation and oceanographic connectivity patterns explain genetic differentiation of a marine diatom across the North Sea–Baltic Sea salinity gradient

    PubMed Central

    Sjöqvist, C; Godhe, A; Jonsson, P R; Sundqvist, L; Kremp, A

    2015-01-01

    Drivers of population genetic structure are still poorly understood in marine micro-organisms. We exploited the North Sea–Baltic Sea transition for investigating the seascape genetics of a marine diatom, Skeletonema marinoi. Eight polymorphic microsatellite loci were analysed in 354 individuals from ten locations to analyse population structure of the species along a 1500-km-long salinity gradient ranging from 3 to 30 psu. To test for salinity adaptation, salinity reaction norms were determined for sets of strains originating from three different salinity regimes of the gradient. Modelled oceanographic connectivity was compared to directional relative migration by correlation analyses to examine oceanographic drivers. Population genetic analyses showed distinct genetic divergence of a low-salinity Baltic Sea population and a high-salinity North Sea population, coinciding with the most evident physical dispersal barrier in the area, the Danish Straits. Baltic Sea populations displayed reduced genetic diversity compared to North Sea populations. Growth optima of low salinity isolates were significantly lower than those of strains from higher native salinities, indicating local salinity adaptation. Although the North Sea–Baltic Sea transition was identified as a barrier to gene flow, migration between Baltic Sea and North Sea populations occurred. However, the presence of differentiated neutral markers on each side of the transition zone suggests that migrants are maladapted. It is concluded that local salinity adaptation, supported by oceanographic connectivity patterns creating an asymmetric migration pattern between the Baltic Sea and the North Sea, determines genetic differentiation patterns in the transition zone. PMID:25892181

  1. Molecular analysis of bacterial diversity in mudflats along the salinity gradient of an acidified tropical Bornean estuary (South East Asia)

    PubMed Central

    2014-01-01

    Background The Brunei River and Bay estuarine system (BES) in the northwest of Borneo is acidic and highly turbid. The system supports extensive intertidal mudflats and presents a potentially steep salinity and pH gradient along its length (45 km). Temporal variation in physical parameters is observed diurnally due to seawater flux during tidal forcing, and stochastically due to elevated freshwater inflow after rains, resulting in a salinity range between 0 and 34 psu. High velocity freshwater run-off from acid sulphate formations during monsoon seasons results in highly variable and acidic conditions (pH 4) at the upper reaches of the BES, whereas the pH is relatively stable (pH 8) at the seaward extremes, due to mixing with seawater from the South China Sea. At their surfaces, the BES mudflats present microbial ecosystems driven by oxygenic phototrophs. To study the effect of various physical parameters on the bacterial diversity of the BES mudflats, surface samples were collected from six sites stretching over 40 km for molecular and phylogentic analysis. Results The bacterial diversity at these sites was compared by community fingerprinting analysis using 16S rRNA gene based denaturing gradient gel electrophoresis and by 16S rRNA gene sequencing and phylogenetic analyses. Results revealed functionally conserved, diatom-driven microbial mudflat communities composed of mainly novel, uncultured species. Species composition was evaluated as 50-70% unique for each site along the BES. Clustering of the sequences commonly occurred and revealed that proteobacterial diversity was related to the salinity gradient. When considering all phyla, the diversity varied consistently with physical parameters (including anthropogenic) that are expected to influence microbial composition. Conclusion The BES mudflats were found to comprise the typical functional groups of microorganisms associated with photosynthetic carbon flux, sulfur cycling (Gamma- and Deltaproteobacteria

  2. Influence of natural organic matter fouling and osmotic backwash on pressure retarded osmosis energy production from natural salinity gradients.

    PubMed

    Yip, Ngai Yin; Elimelech, Menachem

    2013-01-01

    Pressure retarded osmosis (PRO) has the potential to produce clean, renewable energy from natural salinity gradients. However, membrane fouling can lead to diminished water flux productivity, thus reducing the extractable energy. This study investigates organic fouling and osmotic backwash cleaning in PRO and the resulting impact on projected power generation. Fabricated thin-film composite membranes were fouled with model river water containing natural organic matter. The water permeation carried foulants from the feed river water into the membrane porous support layer and caused severe water flux decline of ∼46%. Analysis of the water flux behavior revealed three phases in membrane support layer fouling. Initial foulants of the first fouling phase quickly adsorbed at the active-support layer interface and caused a significantly greater increase in hydraulic resistance than the subsequent second and third phase foulants. The water permeability of the fouled membranes was lowered by ∼39%, causing ∼26% decrease in projected power density. A brief, chemical-free osmotic backwash was demonstrated to be effective in removing foulants from the porous support layer, achieving ∼44% recovery in projected power density. The substantial performance recovery after cleaning was attributed to the partial restoration of the membrane water permeability. This study shows that membrane fouling detrimentally impacts energy production, and highlights the potential strategies to mitigate fouling in PRO power generation with natural salinity gradients. PMID:24099133

  3. The concept of ecological succession applied to phytoplankton over four consecutive years in five ponds featuring a salinity gradient

    NASA Astrophysics Data System (ADS)

    Khemakhem, Hajer; Elloumi, Jannet; Moussa, Mahmoud; Aleya, Lotfi; Ayadi, Habib

    2010-06-01

    The distribution of phytoplankton abundance, biomass and species composition coupled with environmental factors and metazooplankton was studied relatively intensively and over a period of four consecutive years in five ponds featuring a gradient of increasing salinity from near to that of sea water to a nine-fold concentration from 2000 to 2003. The results indicate that the physical characteristics of the water (temperature and salinity) were quite similar over the years. Nutrients, which were concentrated in pond A1, decreased with increases in salt concentration. The composition of the phytoplankton community showed strong seasonality. Diatoms dominated in the first ponds A1, A16 and C2-1, followed by dinoflagellates. Chlorophyceae dominated the phytoplankton community in the hypersaline ponds M2 and TS. Cyanobacteriae were relatively abundant in ponds M2 and TS. The highest phytoplankton density and biomass were found in the ponds with the highest salinity due to the proliferation of Dunaliella salina (Chlorophyta: Volvocales). The inter-annual study of phytoplankton succession in the Sfax solar salterns showed slight differences among the years of study due to the stability of the environmental conditions. Phytoplankton communities were permanently primitive, stage 1 - structured as they failed to build complexity because of salt stress which operates for longer and above any other variables. This reduced frequency of disturbance to the existing course of regulation, allowed the community to "mature" from its "primitive" state, rather than experience frequent structural setbacks.

  4. Seasonal forcing of image-analysed mesozooplankton community composition along the salinity gradient of the Guadalquivir estuary

    NASA Astrophysics Data System (ADS)

    Taglialatela, Simone; Ruiz, Javier; Prieto, Laura; Navarro, Gabriel

    2014-08-01

    The composition and distribution of the mesozooplankton was studied monthly from April 2008 to June 2009 in the Guadalquivir estuary using a fast image analysis technique as well as with traditional microscope counting. The mesozooplankton showed a very clear temporal and spatial pattern with peaks of abundance in late-Spring/early-Summer 2008 and Spring 2009 in the inner estuary. The abundances peaked at 135 × 103 ind. m-3. Calanipeda aquaedulcis was the most abundant species in the fresh and brackish waters (salinity between 0.5 and 7), accounting in many cases for up to 100% of the individuals. Acartia clausi instead was identified as the most abundant species in the middle part of the estuary (salinity between 10 and 30). Cyclopoida of the family Cyclopidae (possibly Acanthocyclops spp.) were occasionally abundant there as well as some species of freshwater Cladocera. At the mouth, the mesozooplanktonic community included appendicularians, chaetognaths, copepods and Cladocera. Canonical Correspondence Analysis (CCA) indicates that the changes observed in the taxonomic composition along the estuary were strictly correlated with the salinity gradient. Furthermore, no evidence of seasonal species substitution was observed in the Guadalquivir estuary, whereas a clear spatial displacement of C. aquaedulcis and A. clausi populations was observed after large discharges from the dam in Alcala del Rio.

  5. Factors affecting the hydrogen isotopic composition of dissolved organic matter along a salinity gradient

    NASA Astrophysics Data System (ADS)

    Debond, A. A.; Ziegler, S. E.; Fogel, M. L.; Morrill, P. L.; Bowden, R.

    2010-12-01

    The role of terrestrial dissolved organic matter (DOM) in regulating estuarine ecosystem processes is poorly understood, in part due to difficulties in tracking terrestrial DOM in marine environments. Analysis of multiple stable isotopes (C, N, S) is often required due to poor separation of the carbon isotope signatures of marine and terrestrial sources. However, hydrogen isotopes exhibit greater fractionation. Marine DOM sources have a hydrogen isotope signature of 0‰ while terrestrial DOM can have signatures of up to -270‰ at the poles. Some challenges must be addressed before hydrogen isotopes can be used to track terrestrial DOM in aquatic environments. Hydrogen isotopes may undergo exchange between water and organic matter, obscuring terrestrial signatures. Riverine discharge into marine environments introduces terrestrial DOM to water of different chemical and isotopic compositions which could influence the isotopic composition of the terrestrial DOM. We investigate the effects of changes in water isotopic composition on DOM by introducing terrestrial DOM to freshwaters of isotopic compositions up to +1000‰ for up to two months. We also use surface water samples along a salinity transect at the Salmonier Arm, Newfoundland, Canada to investigate the effects of changes in water mass conditions (pH, salinity and water isotopes) on terrestrial DOM. In addition to changes in water mass conditions, methods for isolating estuarine DOM may regulate affect its isotopic composition. Ultrafiltration (UF), a size-exclusion technique, has been shown to isolate and concentrate the largest proportion of DOM in estuarine environments. UF separates DOM into low molecular weight (LMW, <1kDa) and high molecular weight (HMW, >1kDa) fractions. However, under certain processing conditions, some LMW DOM can be retained. During desalting (diafiltration), LMW DOM continues to be removed from the concentrate, whereas HMW DOM is retained. The proportion of LMW DOM retained

  6. Application of kinetic model of bioaccumulation across a pH and salinity gradient for the prediction of cadmium uptake by the sediment dwelling Chironomidae

    SciTech Connect

    Bendell-Young, L.I.

    1999-05-01

    A kinetic model for the prediction of metal concentrations in aquatic organisms was applied for the prediction of cadmium concentrations in the sediment dwelling dipertan larvae, Chironomidae. Cadmium concentrations were determined in Chironomidae sampled along two distinct environmental gradients: (1) an acidity gradient (from pH 5.0--6.5) and (2) a salinity gradient. Comparison of predicted and observed values indicated that the kinetic model was successful in predicting concentrations in chironomids sampled along the acidity gradient but not the salinity gradient. Separation of routes of cadmium uptake into food and solute sources indicated that ingested sediment accounted for 60--100% of total invertebrate cadmium concentrations, however, the relative importance of water increased as a function of decreasing acidity and salinity. These results support the refinement of a kinetic model for predicting cadmium concentrations in sediment-living invertebrates, such as Chironomidae. By allowing for uptake from food and water the model highlighted the potential for routes of cadmium uptake to be pH and salinity dependent. For monitoring purposes, both vectors and the potential for the relative importance for each vector to change needs to be considered when assessing the degree of metal exposure to sediment ingesting invertebrates which inhabit systems with either a natural or anthropogenically induced garment in key water chemistry variables such as salinity or pH.

  7. Denitrifier Community Composition along a Nitrate and Salinity Gradient in a Coastal Aquifer

    PubMed Central

    Santoro, Alyson E.; Boehm, Alexandria B.; Francis, Christopher A.

    2006-01-01

    Nitrogen flux into the coastal environment via submarine groundwater discharge may be modulated by microbial processes such as denitrification, but the spatial scales at which microbial communities act and vary are not well understood. In this study, we examined the denitrifying community within the beach aquifer at Huntington Beach, California, where high-nitrate groundwater is a persistent feature. Nitrite reductase-encoding gene fragments (nirK and nirS), responsible for the key step in the denitrification pathway, were PCR amplified, cloned, and sequenced from DNAs extracted from aquifer sediments collected along a cross-shore transect, where groundwater ranged in salinity from 8 to 34 practical salinity units and in nitrate concentration from 0.5 to 330 μM. We found taxonomically rich and novel communities, with all nirK clones exhibiting <85% identity and nirS clones exhibiting <92% identity at the amino acid level to those of cultivated denitrifiers and other environmental clones in the database. Unique communities were found at each site, despite being located within 40 m of each other, suggesting that the spatial scale at which denitrifier diversity and community composition vary is small. Statistical analyses of nir sequences using the Monte Carlo-based program ∫-Libshuff confirmed that some populations were indeed distinct, although further sequencing would be required to fully characterize the highly diverse denitrifying communities at this site. PMID:16517659

  8. Characteristics of the ichthyofauna of a temperate microtidal estuary with a reverse salinity gradient, including inter-decadal comparisons.

    PubMed

    Veale, L; Tweedley, J R; Clarke, K R; Hallett, C S; Potter, I C

    2014-11-01

    Data on the fish fauna of the Leschenault Estuary on the lower west coast of Australia were collected and used as a model to elucidate the characteristics of permanently open estuaries with a reverse salinity gradient, which undergo seasonal changes similar to many other estuaries with Mediterranean climate. Focus was placed on determining (1) the relationships of the number of species, density, life cycle category and species composition of fishes with region (within estuary), season and year and salinity, (2) whether species are partitioned along the lengths of such systems and (3) the extent and significance of any inter-decadal changes in species composition. The analyses and interpretation involved using multi-factorial permutational multivariate analysis of variance (PERMANOVA) and analysis of similarity (ANOSIM) designs, and three new or recently published visualization tools, i.e. modified non-metric multidimensional scaling (nMDS) plots, coherent species curves and segmented bubble plots. The base, lower, upper and apex regions of the Leschenault Estuary, along which the salinity increased in each season except in winter when most rainfall occurs, were sampled seasonally for the 2 years between winter 2008 and autumn 2010. Estuarine residents contributed twice as many individuals, but less than half the number of species as marine taxa. While the numbers of marine species and estuarine residents declined between the base or lower and apex regions, the individuals of marine species dominated the catches in the base region and estuarine residents in the other three regions. Ichthyofaunal composition in each region underwent conspicuous annual cyclical changes, due to time-staggered differences in recruitment among species, and changed sequentially along the estuary, both paralleling salinity trends. Different groups of species characterized the fauna in the different regions and seasons, thereby partitioning resources among species. The ichthyofauna of the

  9. Variations in the release of silicate and orthophosphate along a salinity gradient: Do sediment composition and physical forcing have roles?

    NASA Astrophysics Data System (ADS)

    Paudel, Bhanu; Montagna, Paul A.; Adams, Leslie

    2015-05-01

    It was hypothesized that sediment composition, i.e. organic matters and minerals, and physical forcing can influence retention and release of silicate (SiO4) and orthophosphate (o-PO4) along salinity gradients. An experiment was performed to measure nutrient release by using treatments with and without sediment organic matter from the Guadalupe and Nueces Estuaries at five different salinities. The sample mixtures were shaken at intervals over the course of 48 h to simulate wind and river forcing. The release of silicate from sediments increased with time from 2 min to 48 h in all five salinities. The added orthophosphate concentration was adsorbed in most of the sediment containing organic matter and calcium-rich shells from both estuaries. From the sediments without organic matter, the release of orthophosphate was as high as 52 μmol/L. The sediment minerals quartz and calcite were abundant in both estuaries. The average quartz to corundum peak intensities ratio were 14.04 and 13.36 and the average calcite to corundum peak intensities ratio were 3.06 and 1.32 in the Guadalupe and Nueces Estuaries respectively. The average organic matter in the Guadalupe and Nueces estuaries were 10.67% and 13.39% respectively. The retention and release of orthophosphate from the sediments may have been caused by the bonding with organic matter and calcite in the sediments. These findings indicate that sediment composition was a significant contributor in the low dissolved orthophosphate concentration in the estuaries. The release of silicate from the sediments containing quartz, and organic matter, when shaken, indicate that the combined forcing of river and wind may have been maintaining the estuaries silicate concentrations.

  10. Optimizing biodiesel production in marine Chlamydomonas sp. JSC4 through metabolic profiling and an innovative salinity-gradient strategy

    PubMed Central

    2014-01-01

    Background Biodiesel production from marine microalgae has received much attention as microalgae can be cultivated on non-arable land without the use of potable water, and with the additional benefits of mitigating CO2 emissions and yielding biomass. However, there is still a lack of effective operational strategies to promote lipid accumulation in marine microalgae, which are suitable for making biodiesel since they are mainly composed of saturated and monounsaturated fatty acids. Moreover, the regulatory mechanisms involved in lipid biosynthesis in microalgae under environmental stress are not well understood. Results In this work, the combined effects of salinity and nitrogen depletion stresses on lipid accumulation of a newly isolated marine microalga, Chlamydomonas sp. JSC4, were explored. Metabolic intermediates were profiled over time to observe transient changes during the lipid accumulation triggered by the combination of the two stresses. An innovative cultivation strategy (denoted salinity-gradient operation) was also employed to markedly improve the lipid accumulation and lipid quality of the microalga, which attained an optimal lipid productivity of 223.2 mg L-1 d-1 and a lipid content of 59.4% per dry cell weight. This performance is significantly higher than reported in most related studies. Conclusions This work demonstrated the synergistic integration of biological and engineering technologies to develop a simple and effective strategy for the enhancement of oil production in marine microalgae. PMID:25002905

  11. Development of a Fully Coupled Transient Double-Diffusive Convective Model: Application to a Salinity-Gradient Solar Pond

    NASA Astrophysics Data System (ADS)

    Suarez, F.; Tyler, S. W.; Childress, A. E.

    2008-12-01

    A solar pond is a water body which is heated by absorption of solar radiation and which can provide long- term thermal storage for collected energy. To avoid large heat losses, convection must be suppressed close to the top of the pond. A salinity-gradient solar pond (SGSP) is an artificially stratified solar pond consisting of three thermally distinctive layers: the upper convective zone (UCZ), the non-convective zone (NCZ), and the lower convective zone (LCZ). The UCZ is a relatively thin layer of "cold" and "fresh" water. In the NCZ, the salt gradient suppresses convection within the pond, and thus, the NCZ acts as insulation for the LCZ. The LCZ is the layer where the salt concentration and temperature are the highest. The solar radiation that penetrates the pond's upper layers reaches the LCZ, which can approach temperatures greater than 90°C. Modeling the fluid dynamics of this system is difficult because it requires solution of a set of three second- order non-linear partial differential equations. In order to evaluate the thermal performance and stability of an SGSP, numerical simulation of both heat and mass are required but challenging as double-diffusive convection is likely to occur. Previous approaches have typically assumed no convective transport of solutes, which led to static salinity boundaries of the layers within the SGSP. A 2-D fully coupled numerical model that evaluates the transient performance of an SGSP is introduced. The model simulates the coupled momentum, heat, and mass transfer within the pond. The model can evaluate the influence of meteorological conditions on pond performance by properly describing the heat fluxes through the surface and the solar radiation absorption within the pond, which are typically not well included. Preliminary results show that in a one-week period, for a 1.0 m depth SGSP under summer conditions and without heat extraction, the thicknesses of the UCZ and LCZ increases from 0.1 to 0.2 m, and from 0.5 to 0

  12. Densely charged polyelectrolyte-stuffed nanochannel arrays for power generation from salinity gradient.

    PubMed

    Kwak, Su Hong; Kwon, Seung-Ryong; Baek, Seol; Lim, Seung-Min; Joo, Young-Chang; Chung, Taek Dong

    2016-01-01

    We devised anodized aluminium oxide (AAO) frame-supported polyelectrolytic ion-exchange membranes for the application of electrical power generation systems where salinity differences are present. A series of polyelectrolytic AAO membranes (PAMs) were fabricated as a function of concentration of monomers and cross-linkers. Of the ion-selective PAMs as made, the membranes from the most concentrated monomers and cross-linkers, C-PAM100 and A-PAM100, showed the highest area resistances and permselectivities (the resistances were 4.9 and 2.9 Ω · cm(2), the permseletivities for C-PAM100 and A-PAM100 were 99 and 89%, respectively). The measured resistances and permselectivities allowed the power density to be estimated for C-PAM100 and A-PAM100, 3.5 W/m(2), and experimentally obtained power density using a reverse electrodialysis (RED) stack was 17.3 mW/m(2). In addition, we investigated the influence of an AAO framework on a membrane resistance by comparing the PAMs with polyelectrolyte-stuffed capillaries, revealing that the resistance of the PAM has plenty of potential to be further reduced by optimizing the AAO pore spaces. PMID:27194475

  13. Densely charged polyelectrolyte-stuffed nanochannel arrays for power generation from salinity gradient

    NASA Astrophysics Data System (ADS)

    Kwak, Su Hong; Kwon, Seung-Ryong; Baek, Seol; Lim, Seung-Min; Joo, Young-Chang; Chung, Taek Dong

    2016-05-01

    We devised anodized aluminium oxide (AAO) frame-supported polyelectrolytic ion-exchange membranes for the application of electrical power generation systems where salinity differences are present. A series of polyelectrolytic AAO membranes (PAMs) were fabricated as a function of concentration of monomers and cross-linkers. Of the ion-selective PAMs as made, the membranes from the most concentrated monomers and cross-linkers, C-PAM100 and A-PAM100, showed the highest area resistances and permselectivities (the resistances were 4.9 and 2.9 Ω · cm2, the permseletivities for C-PAM100 and A-PAM100 were 99 and 89%, respectively). The measured resistances and permselectivities allowed the power density to be estimated for C-PAM100 and A-PAM100, 3.5 W/m2, and experimentally obtained power density using a reverse electrodialysis (RED) stack was 17.3 mW/m2. In addition, we investigated the influence of an AAO framework on a membrane resistance by comparing the PAMs with polyelectrolyte-stuffed capillaries, revealing that the resistance of the PAM has plenty of potential to be further reduced by optimizing the AAO pore spaces.

  14. Densely charged polyelectrolyte-stuffed nanochannel arrays for power generation from salinity gradient

    PubMed Central

    Kwak, Su Hong; Kwon, Seung-Ryong; Baek, Seol; Lim, Seung-Min; Joo, Young-Chang; Chung, Taek Dong

    2016-01-01

    We devised anodized aluminium oxide (AAO) frame-supported polyelectrolytic ion-exchange membranes for the application of electrical power generation systems where salinity differences are present. A series of polyelectrolytic AAO membranes (PAMs) were fabricated as a function of concentration of monomers and cross-linkers. Of the ion-selective PAMs as made, the membranes from the most concentrated monomers and cross-linkers, C-PAM100 and A-PAM100, showed the highest area resistances and permselectivities (the resistances were 4.9 and 2.9 Ω · cm2, the permseletivities for C-PAM100 and A-PAM100 were 99 and 89%, respectively). The measured resistances and permselectivities allowed the power density to be estimated for C-PAM100 and A-PAM100, 3.5 W/m2, and experimentally obtained power density using a reverse electrodialysis (RED) stack was 17.3 mW/m2. In addition, we investigated the influence of an AAO framework on a membrane resistance by comparing the PAMs with polyelectrolyte-stuffed capillaries, revealing that the resistance of the PAM has plenty of potential to be further reduced by optimizing the AAO pore spaces. PMID:27194475

  15. Tailor-made anion-exchange membranes for salinity gradient power generation using reverse electrodialysis.

    PubMed

    Guler, Enver; Zhang, Yali; Saakes, Michel; Nijmeijer, Kitty

    2012-11-01

    Reverse electrodialysis (RED) or blue energy is a non-polluting, sustainable technology for generating power from the mixing of solutions with different salinity, that is, seawater and river water. A concentrated salt solution (e.g., seawater) and a diluted salt solution (e.g., river water) are brought into contact through an alternating series of polymeric anion-exchange membranes (AEMs) and cation-exchange membranes (CEMs), which are either selective for anions or cations. Currently available ion-exchange membranes are not optimized for RED, whereas successful RED operation notably depends on the used ion-exchange membranes. We designed such ion-exchange membranes and for the first time we show the performance of tailor-made membranes in RED. More specifically, we focus on the development of AEMs because these are much more complex to prepare. Herein we propose a safe and more environmentally friendly method and use halogenated polyethers, such as polyepichlorohydrin (PECH) as the starting material. A tertiary diamine (1,4-diazabicyclo[2.2.2]octane, DABCO) was used to introduce the ion-exchange groups by amination and for simultaneous cross-linking of the polymer membrane. Area resistances of the series of membranes ranged from 0.82 to 2.05 Ω cm² and permselectivities from 87 to 90 %. For the first time we showed that tailor-made ion-exchange membranes can be applied in RED. Depending on the properties and especially membrane thickness, application of these membranes in RED resulted in a high power density of 1.27 W m⁻², which exceeds the power output obtained with the commercially available AMX membranes. This shows the potential of the design of ion-exchange membranes for a viable blue energy process. PMID:23109486

  16. Spatial patterns in soil biogeochemical process rates along a Louisiana wetland salinity gradient in the Barataria Bay estuarine system

    NASA Astrophysics Data System (ADS)

    Roberts, B. J.; Rich, M. W.; Sullivan, H. L.; Bledsoe, R.; Dawson, M.; Donnelly, B.; Marton, J. M.

    2014-12-01

    Louisiana has the highest rates of coastal wetland loss in the United States. In addition to being lost, Louisiana wetlands experience numerous other environmental stressors including changes in salinity regime (both increases from salt water intrusion and decreases from the creation of river diversions) and climate change induced changes in vegetation (e.g. the northward expansion of Avicennia germinans (black mangrove) into salt marshes). In this study, we examined how these changes might influence biogeochemical process rates important in regulating carbon balance and the cycling, retention, and removal of nutrients in Louisiana wetlands. Specifically, we measured net soil greenhouse gas fluxes and collected cores for the determination of rates of greenhouse gas production, denitrification potential, nitrification potential, iron reduction, and phosphorus sorption from surface (0-5cm) and subsurface (10-15cm) depths for three plots in each of 4 sites along the salinity gradient: a freshwater marsh site, a brackish (7 ppt) marsh site, a salt marsh (17 ppt), and a Avicennia germinans stand (17 ppt; adjacent to salt marsh site) in the Barataria Bay estuarine system. Most biogeochemical processes displayed similar spatial patterns with salt marsh rates being lower than rates in freshwater and/or brackish marsh sites and not having significantly different rates than in Avicennia germinans stands. Rates in surface soils were generally higher than in subsurface soils. These patterns were generally consistent with spatial patterns in soil properties with soil water content, organic matter quantity and quality, and extractable nutrients generally being higher in freshwater and brackish marsh sites than salt marsh and Avicennia germinans sites, especially in surface soils. These spatial patterns suggest that the ability of coastal wetlands to retain and remove nutrients might change significantly in response to future climate changes in the region and that these

  17. Salinity tolerance ecophysiology of Equisetum giganteum in South America: a study of 11 sites providing a natural gradient of salinity stress

    PubMed Central

    Husby, Chad E.; Delatorre, José; Oreste, Vittorio; Oberbauer, Steven F.; Palow, Danielle T.; Novara, Lázaro; Grau, Alfredo

    2011-01-01

    Background and aims The basic set of adaptations necessary for salinity tolerance in vascular plants remains unknown. Although much has been published on salinity stress, almost all studies deal with spermatophytes. Studies of salinity tolerance in pteridophytes are relatively rare but hold promise for revealing the fundamental adaptations that all salt-tolerant vascular plants may share. The most basal pteridophytes to exhibit salinity tolerance are members of the genus Equisetum, including the giant horsetail, Equisetum giganteum, the only pteridophyte to occur in salinity-affected regions of the Atacama Desert valleys of northern Chile. Here it can constitute a significant vegetation component, forming dense stands of shoots >4 m high. Methodology Physiological parameters (stomatal conductances; efficiency of photosystem II; sap osmotic potential) were measured in E. giganteum populations in northern Chile across a range of groundwater salinities at 11 sites. In addition, Na, K, electrical conductivity and total plant water potential were measured in the plants and groundwater from each site. Principal results Equisetum giganteum exhibits similar stomatal conductances and photochemical efficiencies of photosystem II across a wide range of groundwater salinities. It lowers cell sap osmotic potential with increasing salinity and produces positive root pressure, as evidenced by guttation, at the full range of salinities experienced in the Atacama Desert. Equisetum giganteum maintains low Na concentrations in its xylem fluid and cell sap when soil water Na is high. It also maintains high K/Na ratios in xylem fluid and cell sap when soil water has low K/Na ratios. Conclusions Equisetum giganteum is well adapted to salinity stress. Efficient K uptake and Na exclusion are important adaptations and closely similar to those of the facultative halophyte fern Acrostichum aureum. PMID:22476492

  18. Coral record of southeast Indian Ocean SST, SSH and salinity and their modulation by ENSO and the Western Pacific temperature gradient

    NASA Astrophysics Data System (ADS)

    Zinke, Jens; Hoell, Andrew; Lough, Janice M.; Feng, Ming; McCulloch, Malcolm T.

    2016-04-01

    Variability of southeastern Indian Ocean (SEIO) sea surface temperatures (SST), sea surface height (SSH) and salinities off Western Australia is a footprint of interannual and decadal climate variations in the tropical Indo-Pacific. La Niña events often result in a strengthened Leeuwin Current, high coastal sea levels, low salinities and unusually warm SSTs, now termed Ningaloo Niño events. The long-term teleconnections of the southeastern Indian Ocean (SEIO) with ENSO and the West Pacific Warm Pool are poorly understood. Here we demonstrate the role of Indo-Pacific coupling in modulating SST, SSH and salinity in the poorly studied SEIO, through a robust 215 year (1795-2010) geochemical coral proxy sea surface temperature (SST), SSH and salinity record. We show that higher SST and SSH accompanied by lower salinities in the SEIO are linked to the behaviour of ENSO and the Western Pacific Warm Pool on decadal to centennial timescales, and are most pronounced when an anomalously strong zonal SST gradient between the western and central Pacific co-occurs with strong La Niña's. Better understanding of the interplay between the zonal SST gradient in the western Pacific, ENSO phase and intrinsic Indian Ocean variability is expected to improve our ability to better predict unusual marine heat waves, sea level surges and important consequences for marine socio-ecological systems in the Future.

  19. Spatial pattern formation of coastal vegetation in response to external gradients and positive feedbacks affecting soil porewater salinity: A model study

    USGS Publications Warehouse

    Jiang, J.; DeAngelis, D.L.; Smith, T. J., III; Teh, S.Y.; Koh, H. L.

    2012-01-01

    Coastal vegetation of South Florida typically comprises salinity-tolerant mangroves bordering salinity-intolerant hardwood hammocks and fresh water marshes. Two primary ecological factors appear to influence the maintenance of mangrove/hammock ecotones against changes that might occur due to disturbances. One of these is a gradient in one or more environmental factors. The other is the action of positive feedback mechanisms, in which each vegetation community influences its local environment to favor itself, reinforcing the boundary between communities. The relative contributions of these two factors, however, can be hard to discern. A spatially explicit individual-based model of vegetation, coupled with a model of soil hydrology and salinity dynamics is presented here to simulate mangrove/hammock ecotones in the coastal margin habitats of South Florida. The model simulation results indicate that an environmental gradient of salinity, caused by tidal flux, is the key factor separating vegetation communities, while positive feedback involving the different interaction of each vegetation type with the vadose zone salinity increases the sharpness of boundaries, and maintains the ecological resilience of mangrove/hammock ecotones against small disturbances. Investigation of effects of precipitation on positive feedback indicates that the dry season, with its low precipitation, is the period of strongest positive feedback. ?? 2011 Springer Science+Business Media B.V. (outside the USA).

  20. Salt tolerance and osmotic adjustment of Spartina alterniflora (Poaceae) and the invasive M haplotype of Phragmites australis (Poaceae) along a salinity gradient

    USGS Publications Warehouse

    Vasquez, E.A.; Glenn, E.P.; Guntenspergen, G.R.; Brown, J.J.; Nelson, S.G.

    2006-01-01

    An invasive variety of Phragmites australis (Poaceae, common reed), the M haplotype, has been implicated in the spread of this species into North American salt marshes that are normally dominated by the salt marsh grass Spartina alterniflora (Poaceae, smooth cordgrass). In some European marshes, on the other hand, Spartina spp. derived from S. alterniflora have spread into brackish P. australis marshes. In both cases, the non-native grass is thought to degrade the habitat value of the marsh for wildlife, and it is important to understand the physiological processes that lead to these species replacements. We compared the growth, salt tolerance, and osmotic adjustment of M haplotype P. australis and S. alterniflora along a salinity gradient in greenhouse experiments. Spartina alterniflora produced new biomass up to 0.6 M NaCl, whereas P. australis did not grow well above 0.2 M NaCl. The greater salt tolerance of S. alterniflora compared with P. australis was due to its ability to use Na+ for osmotic adjustment in the shoots. On the other hand, at low salinities P. australis produced more shoots per gram of rhizome tissue than did S. alterniflora. This study illustrates how ecophysiological differences can shift the competitive advantage from one species to another along a stress gradient. Phragmites australis is spreading into North American coastal marshes that are experiencing reduced salinities, while Spartina spp. are spreading into northern European brackish marshes that are experiencing increased salinities as land use patterns change on the two continents.

  1. Decadal and lower frequency changes in the South Pacific Convergence Zone (SPCZ) salinity front gradient over the last 210 years and relationship to Pacific-wide climate

    NASA Astrophysics Data System (ADS)

    Linsley, B. K.; Dassie, E. P.; Wu, H. C.; Wellington, G. M.

    2010-12-01

    Along the southeastern edge of the SPCZ near 170°W and 15°-20°S a surface ocean salinity frontal zone exists that separates fresher water under the SPCZ from significantly saltier and cooler waters to the east in the South Pacific central gyre. Instrumental sea surface salinity (SSS) data from this region indicate that temporal variability in the SSS difference between Fiji and Tonga is closely coupled to the phase of ENSO. The SSS difference increases by 1.0 to 1.5 p.s.s. during La Niña events and decreases by a comparable magnitude to no difference (0.0 p.s.s.) during El Niño events. The cause of this gradient change is directly related to the position of the salinity front. During La Niña events the salinity front shifts SE as the S. Equatorial Current (SEC) weakens and the zone of maximum rainfall in the SPCZ moves over Fiji, making Fiji fresher than Tonga. During El Niño events, the SEC advects higher salinity water from the east and the SPCZ shifts NE making the SSS difference between Fiji and Tonga close to zero. Using replicated coral δ18O and SSS records over the last 50 years, (Dassie et al., 2010, this meeting) demonstrate that Porites corals from Fiji and Tonga accurately record interannual changes in this SSS difference across the salinity front. Here we evaluate decadal-scale and lower frequency changes in the coral δ18O difference between Fiji and Tonga using replicated Porites coral δ18O records from Fiji (Savusavu Bay, n=2; Vanua Balavu (200km E. of Savusavu Bay, n=2) and Tonga (n=2). Our previous work with coral δ18O records from the region indicates that interannual and lower frequency changes in δ18O are predominantly driven by changes in SSS (Linsley et al., 2006, G^3). Earlier evidence from instrumental salinity data and coral δ18O records indicate that the SPCZ has been expanding SE since the mid 19th century. Our new coral δ18O reconstruction of the SSS gradient provides more details and indicates a reduced or non

  2. Relative contributions of sea surface salinity and temperature to density gradient and tropical instability waves: implications to eddy-mean flow interaction

    NASA Astrophysics Data System (ADS)

    Hasson, Audrey; Lee, Tong

    2015-04-01

    With their relatively uniform spatial and temporal sampling, satellite observations have revolutionized the estimates of the spatial derivative fields of various oceanic parameters that are not possible to derive from in-situ measurements on a global scale with sufficient spatial resolutions. For examples, the spatial gradients of sea surface height measurements from altimetry provide information about surface geostrophic currents; those of wind stress make possible the estimates of wind stress curl and divergence; those of sea surface temperature and salinity allow detections of thermal and haline fronts. These spatial derivatives fields are critical to the studies of ocean circulation and air-sea interaction. In particular, the spatial gradients of satellite-derived sea surface temperature and salinity (SST and SSS) have provided an unprecedented opportunity to study density gradient that is important to energy conversion between the background ocean state and the fluctuating flow field such as eddies and waves through baroclinic instability. In this study, we examine eddy-mean flow interaction in tropical oceans by studying the relations between background density gradient and tropical instability wave (TIW) variability using various satellite-derived SSS and SST products. In the equatorial Pacific and Atlantic Oceans, SSS is found to have equal or larger contribution to the background meridional density gradient. This has important consequence to the density variance associated with the TIWs (a proxy for the extraction of available potential energy from the background ocean state to the TIWs). Not accounting for salinity effect would under-estimate the TIW-related density variance by at least a factor of three.

  3. Carbon isotope analysis of dissolved organic carbon in fresh and saline (NaCl) water via continuous flow cavity ring-down spectroscopy following wet chemical oxidation

    USGS Publications Warehouse

    Conaway, Christopher; Thomas, Randal B.; Saad, Nabil; Thordsen, James J.; Kharaka, Yousif K.

    2015-01-01

    This work examines the performance and limitations of a wet chemical oxidation carbon analyser interfaced with a cavity ring-down spectrometer (WCO-CRDS) in a continuous flow (CF) configuration for measuring δ13C of dissolved organic carbon (δ13C-DOC) in natural water samples. Low-chloride matrix (<5 g Cl/L) DOC solutions were analysed with as little as 2.5 mg C/L in a 9 mL aliquot with a precision of 0.5 ‰. In high-chloride matrix (10–100 g Cl/L) DOC solutions, bias towards lighter δ13C-DOC was observed because of incomplete oxidation despite using high-concentration oxidant, extended reaction time, or post-wet chemical oxidation gas-phase combustion. However, through a combination of dilution, chloride removal, and increasing the oxidant:sample ratio, high-salinity samples with sufficient DOC (>22.5 µg C/aliquot) may be analysed. The WCO-CRDS approach requires more total carbon (µg C/aliquot) than conventional CF-isotope ratio mass spectrometer, but is nonetheless applicable to a wide range of DOC concentration and water types, including brackish water, produced water, and basinal brines.

  4. Effects of imposed salinity gradients on dissimilatory arsenate reduction, sulfate reduction, and other microbial processes in sediments from two California soda lakes

    USGS Publications Warehouse

    Kulp, T.R.; Han, S.; Saltikov, C.W.; Lanoil, B.D.; Zargar, K.; Oremland, R.S.

    2007-01-01

    Salinity effects on microbial community structure and on potential rates of arsenate reduction, arsenite oxidation, sulfate reduction, denitrification, and methanogenesis were examined in sediment slurries from two California soda lakes. We conducted experiments with Mono Lake and Searles Lake sediments over a wide range of salt concentrations (25 to 346 g liter-1). With the exception of sulfate reduction, rates of all processes demonstrated an inverse relationship to total salinity. However, each of these processes persisted at low but detectable rates at salt saturation. Denaturing gradient gel electrophoresis analysis of partial 16S rRNA genes amplified from As(V) reduction slurries revealed that distinct microbial populations grew at low (25 to 50 g liter-1), intermediate (100 to 200 g liter-1), and high (>300 g liter-1) salinity. At intermediate and high salinities, a close relative of a cultivated As-respiring halophile was present. These results suggest that organisms adapted to more dilute conditions can remain viable at high salinity and rapidly repopulate the lake during periods of rising lake level. In contrast to As reduction, sulfate reduction in Mono Lake slurries was undetectable at salt saturation. Furthermore, sulfate reduction was excluded from Searles Lake sediments at any salinity despite the presence of abundant sulfate. Sulfate reduction occurred in Searles Lake sediment slurries only following inoculation with Mono Lake sediment, indicating the absence of sulfate-reducing flora. Experiments with borate-amended Mono Lake slurries suggest that the notably high (0.46 molal) concentration of borate in the Searles Lake brine was responsible for the exclusion of sulfate reducers from that ecosystem. Copyright ?? 2007, American Society for Microbiology. All Rights Reserved.

  5. Morphological and structural plasticity of grassland species in response to a gradient in saline-sodic soils.

    PubMed

    Huang, Y; Song, Y; Li, G; Drake, P L; Zheng, W; Li, Z; Zhou, D

    2015-11-01

    The abundance and distribution of species can be ascribed to both environmental heterogeneity and stress tolerance, with the latter measure sometimes associated with phenotypic plasticity. Although phenotypic plasticity varies predictably in response to common forms of stress, we lack a mechanistic understanding of the response of species to high saline-sodic soils. We compared the phenotypic plasticity of three pairs of high and low saline-sodic tolerant congeners from the families Poaceae (Leymus chinensis versus L. secalinus), Fabaceae (Lespedeza davurica versus L. bicolor) and Asteraceae (Artemisia mongolica versus A. sieversiana) in a controlled pot experiment in the Songnen grassland, China. The low tolerant species, L. secalinus and A. sieversiana exhibited higher plasticity in response to soil salinity and sodicity than their paired congeners. Highly tolerant species, L. chinensis and A. mongolica, had higher values for several important morphological traits, such as shoot length and total biomass under the high saline-sodic soil treatment than their paired congeners. In contrast, congeners from the family Fabaceae, L. davurica and L. bicolor, did not exhibit significantly different plasticity in response to soil salinity and sodicity. All species held a constant reproductive effort in response to saline-sodic soil stress. The different responses between low and high tolerant species offer an explanation for the distribution patterns of these species in the Songnen grassland. Highly tolerant species showed less morphological plasticity over a range of saline-sodic conditions than their paired congeners, which may manifest as an inability to compete with co-occurring species in locations where saline-sodic soils are absent. PMID:26177120

  6. Benthic foraminifera cultured over a large salinity gradient: first results and comparison with field data from the Baltic Sea.

    NASA Astrophysics Data System (ADS)

    Groeneveld, Jeroen; Filipsson, Helena L.; Austin, William E. N.; Darling, Kate; Quintana Krupinski, Nadine B.

    2015-04-01

    Some of the most significant challenges in paleoclimate research arise from the need to both understand and reduce the uncertainty associated with proxy methods for climate reconstructions. This is especially important for shelf and coastal environments where increasing numbers of high-resolution paleorecords are being generated. These challenges are further highlighted in connection with ECORD/IODP Expedition 347: Baltic Sea Paleoenvironments. This large-scale drilling operation took place in the Baltic Sea region during the autumn of 2013. At this time, there is a pressing need for proxy calibrations directly targeted at the brackish Baltic environment. Within the CONTEMPORARY project we are investigating different temperature and salinity proxy variables through a combination of field- and culture-based benthic foraminiferal samples, together with genetic characterization (genotyping) of the morphospecies. We have completed two field campaigns where we collected (living) foraminifera and water samples at several sites, ranging from fully marine to low salinity conditions. The core-top foraminifera have been analysed for trace metal/Ca, stable oxygen and carbon isotopes, and faunal composition. Living foraminifera collected from the sediment-water interface were cultured in sea water in two long-term experiments at different temperatures (5°C and 10°C) and at three different salinities (15, 25, and 35). The first experiment yielded a large number of reproduced and experimentally-grown Elphidium specimens. The second experiment resulted in growth but no reproduction. We will provide a summary of the experimentally grown material and discuss the challenges of generating new proxy calibrations for foraminiferal shell geochemistry in the Baltic Sea. Furthermore, specimens of Elphidium and Ammonia, found at two sampling sites (Anholt, Kattegat and Hanöbay) with differing salinities, were genotyped and the results indicate that the same genotype of Elphidium is

  7. Patterns of microbial diversity along a salinity gradient in the Guerrero Negro solar saltern, Baja CA Sur, Mexico

    PubMed Central

    Dillon, Jesse G.; Carlin, Mark; Gutierrez, Abraham; Nguyen, Vivian; McLain, Nathan

    2013-01-01

    The goal of this study was to use environmental sequencing of 16S rRNA and bop genes to compare the diversity of planktonic bacteria and archaea across ponds with increasing salinity in the Exportadora de Sal (ESSA) evaporative saltern in Guerrero Negro, Baja CA S., Mexico. We hypothesized that diverse communities of heterotrophic bacteria and archaea would be found in the ESSA ponds, but that bacterial diversity would decrease relative to archaea at the highest salinities. Archaeal 16S rRNA diversity was higher in Ponds 11 and 12 (370 and 380 g l−1 total salts, respectively) compared to Pond 9 (180 g l−1 total salts). Both Pond 11 and 12 communities had high representation (47 and 45% of clones, respectively) by Haloquadratum walsbyi-like (99% similarity) lineages. The archaeal community in Pond 9 was dominated (79%) by a single uncultured phylotype with 99% similarity to sequences recovered from the Sfax saltern in Tunisia. This pattern was mirrored in bop gene diversity with greater numbers of highly supported phylotypes including many Haloquadratum-like sequences from the two highest salinity ponds. In Pond 9, most bop sequences, were not closely related to sequences in databases. Bacterial 16S rRNA diversity was higher than archaeal in both Pond 9 and Pond 12 samples, but not Pond 11, where a non-Salinibacter lineage within the Bacteroidetes >98% similar to environmental clones recovered from Lake Tuz in Turkey and a saltern in Chula Vista, CA was most abundant (69% of community). This OTU was also the most abundant in Pond 12, but only represented 14% of clones in the more diverse pond. The most abundant OTU in Pond 9 (33% of community) was 99% similar to an uncultured gammaproteobacterial clone from the Salton Sea. Results suggest that the communities of saltern bacteria and archaea vary even in ponds with similar salinity and further investigation into the ecology of diverse, uncultured halophile communities is warranted. PMID:24391633

  8. Integrated Electrokinetics-Adsorption Remediation of Saline-Sodic Soils: Effects of Voltage Gradient and Contaminant Concentration on Soil Electrical Conductivity

    PubMed Central

    Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat

    2013-01-01

    In this study, an integrated in situ remediation technique which couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic clay soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the effects of voltage gradient, initial contaminant concentration, and polarity reversal rate on the soil electrical conductivity. Box-Behnken Design (BBD) was used for the experimental design and response surface methodology (RSM) was employed to model, optimize, and interpret the results obtained using Design-Expert version 8 platform. The total number of experiments conducted was 15 with voltage gradient, polarity reversal rate, and initial contaminant concentration as variables. The main target response discussed in this paper is the soil electrical conductivity due to its importance in electrokinetic remediation process. Responses obtained were fitted to quadratic models whose R2 ranges from 84.66% to 99.19% with insignificant lack of fit in each case. Among the investigated factors, voltage gradient and initial contaminant concentration were found to be the most significant influential factors. PMID:24459439

  9. Integrated electrokinetics-adsorption remediation of saline-sodic soils: effects of voltage gradient and contaminant concentration on soil electrical conductivity.

    PubMed

    Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat; Lukman, Salihu; Bukhari, Alaadin

    2013-01-01

    In this study, an integrated in situ remediation technique which couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic clay soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the effects of voltage gradient, initial contaminant concentration, and polarity reversal rate on the soil electrical conductivity. Box-Behnken Design (BBD) was used for the experimental design and response surface methodology (RSM) was employed to model, optimize, and interpret the results obtained using Design-Expert version 8 platform. The total number of experiments conducted was 15 with voltage gradient, polarity reversal rate, and initial contaminant concentration as variables. The main target response discussed in this paper is the soil electrical conductivity due to its importance in electrokinetic remediation process. Responses obtained were fitted to quadratic models whose R (2) ranges from 84.66% to 99.19% with insignificant lack of fit in each case. Among the investigated factors, voltage gradient and initial contaminant concentration were found to be the most significant influential factors. PMID:24459439

  10. Quantification of the impact of hydrology on agricultural production as a result of too dry, too wet or too saline conditions

    NASA Astrophysics Data System (ADS)

    Hack-ten Broeke, Mirjam J. D.; Kroes, Joop G.; Bartholomeus, Ruud P.; van Dam, Jos C.; de Wit, Allard J. W.; Supit, Iwan; Walvoort, Dennis J. J.; van Bakel, P. Jan T.; Ruijtenberg, Rob

    2016-08-01

    For calculating the effects of hydrological measures on agricultural production in the Netherlands a new comprehensive and climate proof method is being developed: WaterVision Agriculture (in Dutch: Waterwijzer Landbouw). End users have asked for a method that considers current and future climate, that can quantify the differences between years and also the effects of extreme weather events. Furthermore they would like a method that considers current farm management and that can distinguish three different causes of crop yield reduction: drought, saline conditions or too wet conditions causing oxygen shortage in the root zone. WaterVision Agriculture is based on the hydrological simulation model SWAP and the crop growth model WOFOST. SWAP simulates water transport in the unsaturated zone using meteorological data, boundary conditions (like groundwater level or drainage) and soil parameters. WOFOST simulates crop growth as a function of meteorological conditions and crop parameters. Using the combination of these process-based models we have derived a meta-model, i.e. a set of easily applicable simplified relations for assessing crop growth as a function of soil type and groundwater level. These relations are based on multiple model runs for at least 72 soil units and the possible groundwater regimes in the Netherlands. So far, we parameterized the model for the crops silage maize and grassland. For the assessment, the soil characteristics (soil water retention and hydraulic conductivity) are very important input parameters for all soil layers of these 72 soil units. These 72 soil units cover all soils in the Netherlands. This paper describes (i) the setup and examples of application of the process-based model SWAP-WOFOST, (ii) the development of the simplified relations based on this model and (iii) how WaterVision Agriculture can be used by farmers, regional government, water boards and others to assess crop yield reduction as a function of groundwater

  11. Trophic structure and avian communities across a salinity gradient in evaporation ponds of the San Francisco Bay estuary

    USGS Publications Warehouse

    Takekawa, J.Y.; Miles, A.K.; Schoellhamer, D.H.; Athearn, N.D.; Saiki, M.K.; Duffy, W.D.; Kleinschmidt, S.; Shellenbarger, G.G.; Jannusch, C.A.

    2006-01-01

    Commercial salt evaporation ponds comprise a large proportion of baylands adjacent to the San Francisco Bay, a highly urbanized estuary. In the past two centuries, more than 79% of the historic tidal wetlands in this estuary have been lost. Resource management agencies have acquired more than 10 000 ha of commercial salt ponds with plans to undertake one of the largest wetland restoration projects in North America. However, these plans have created debate about the ecological importance of salt ponds for migratory bird communities in western North America. Salt ponds are unique mesohaline (5–18 g l−1) to hyperhaline (> 40 g l−1) wetlands, but little is known of their ecological structure or value. Thus, we studied decommissioned salt ponds in the North Bay of the San Francisco Bay estuary from January 1999 through November 2001. We measured water quality parameters (salinity, DO, pH, temperature), nutrient concentrations, primary productivity, zooplankton, macroinvertebrates, fish, and birds across a range of salinities from 24 to 264 g l−1. Our studies documented how unique limnological characteristics of salt ponds were related to nutrient levels, primary productivity rates, invertebrate biomass and taxa richness, prey fish, and avian predator numbers. Salt ponds were shown to have unique trophic and physical attributes that supported large numbers of migratory birds. Therefore, managers should carefully weigh the benefits of increasing habitat for native tidal marsh species with the costs of losing these unique hypersaline systems.

  12. Trophic structure and avian communities across a salinity gradient in evaporation ponds of the San Francisco Bay estuary

    USGS Publications Warehouse

    Takekawa, J.Y.; Miles, A.K.; Schoellhamer, D.H.; Athearn, N.D.; Saiki, M.K.; Duffy, W.D.; Kleinschmidt, S.; Shellenbarger, G.G.; Jannusch, C.A.

    2006-01-01

    Commercial salt evaporation ponds comprise a large proportion of baylands adjacent to the San Francisco Bay, a highly urbanized estuary. In the past two centuries, more than 79% of the historic tidal wetlands in this estuary have been lost. Resource management agencies have acquired more than 10 000 ha of commercial salt ponds with plans to undertake one of the largest wetland restoration projects in North America. However, these plans have created debate about the ecological importance of salt ponds for migratory bird communities in western North America. Salt ponds are unique mesohaline (5-18 g l-1) to hyperhaline (> 40 g l-1) wetlands, but little is known of their ecological structure or value. Thus, we studied decommissioned salt ponds in the North Bay of the San Francisco Bay estuary from January 1999 through November 2001. We measured water quality parameters (salinity, DO, pH, temperature), nutrient concentrations, primary productivity, zooplankton, macroinvertebrates, fish, and birds across a range of salinities from 24 to 264 g l-1. Our studies documented how unique limnological characteristics of salt ponds were related to nutrient levels, primary productivity rates, invertebrate biomass and taxa richness, prey fish, and avian predator numbers. Salt ponds were shown to have unique trophic and physical attributes that supported large numbers of migratory birds. Therefore, managers should carefully weigh the benefits of increasing habitat for native tidal marsh species with the costs of losing these unique hypersaline systems. ?? Springer 2006.

  13. Ant Diversity and Distribution along Elevation Gradients in the Australian Wet Tropics: The Importance of Seasonal Moisture Stability.

    PubMed

    Nowrouzi, Somayeh; Andersen, Alan N; Macfadyen, Sarina; Staunton, Kyran M; VanDerWal, Jeremy; Robson, Simon K A

    2016-01-01

    The threat of anthropogenic climate change has seen a renewed focus on understanding contemporary patterns of species distribution. This is especially the case for the biota of tropical mountains, because tropical species often have particularly narrow elevational ranges and there are high levels of short-range endemism. Here we describe geographic patterns of ant diversity and distribution in the World Heritage-listed rainforests of the Australian Wet Tropics (AWT), revealing seasonal moisture stability to be an important environmental correlate of elevational patterns of species composition. We sampled ants in leaf litter, on the litter surface and on tree trunks at 26 sites from six subregions spanning five degrees of latitude and elevation ranges from 100-1,300 m. A total of 296 species from 63 genera were recorded. Species richness showed a slight peak at mid elevations, and did not vary significantly with latitude. Species composition varied substantially between subregions, and many species have highly localised distributions. There was very marked species turnover with elevation, with a particularly striking compositional disjunction between 600 m and 800 m at each subregion. This disjunction coincides with a strong environmental threshold of seasonal stability in moisture associated with cloud 'stripping'. Our study therefore provides further support for climatic stability as a potential mechanism underlying patterns of diversity. The average height of orographic cloud layers is predicted to rise under global warming, and associated shifts in seasonal moisture stability may exacerbate biotic change caused by rising temperature alone. PMID:27073848

  14. Ant Diversity and Distribution along Elevation Gradients in the Australian Wet Tropics: The Importance of Seasonal Moisture Stability

    PubMed Central

    Nowrouzi, Somayeh; Andersen, Alan N.; Macfadyen, Sarina; Staunton, Kyran M.; VanDerWal, Jeremy; Robson, Simon K. A.

    2016-01-01

    The threat of anthropogenic climate change has seen a renewed focus on understanding contemporary patterns of species distribution. This is especially the case for the biota of tropical mountains, because tropical species often have particularly narrow elevational ranges and there are high levels of short-range endemism. Here we describe geographic patterns of ant diversity and distribution in the World Heritage-listed rainforests of the Australian Wet Tropics (AWT), revealing seasonal moisture stability to be an important environmental correlate of elevational patterns of species composition. We sampled ants in leaf litter, on the litter surface and on tree trunks at 26 sites from six subregions spanning five degrees of latitude and elevation ranges from 100–1,300 m. A total of 296 species from 63 genera were recorded. Species richness showed a slight peak at mid elevations, and did not vary significantly with latitude. Species composition varied substantially between subregions, and many species have highly localised distributions. There was very marked species turnover with elevation, with a particularly striking compositional disjunction between 600 m and 800 m at each subregion. This disjunction coincides with a strong environmental threshold of seasonal stability in moisture associated with cloud ‘stripping’. Our study therefore provides further support for climatic stability as a potential mechanism underlying patterns of diversity. The average height of orographic cloud layers is predicted to rise under global warming, and associated shifts in seasonal moisture stability may exacerbate biotic change caused by rising temperature alone. PMID:27073848

  15. Intensive measurements of gas, water, and energy exchange between vegetation and troposphere during the MONTES Campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean basin

    EPA Science Inventory

    MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Wester...

  16. Boosting the voltage of a salinity-gradient-power electrochemical cell by means of complex-forming solutions

    NASA Astrophysics Data System (ADS)

    Marino, M.; Misuri, L.; Carati, A.; Brogioli, D.

    2014-07-01

    We report experiments on a concentration cell with zinc electrodes and ZnCl2 solutions at different concentrations, separated by a porous diaphragm. The cell is aimed at the conversion of the free energy associated to the concentration difference into electrical energy, for renewable and clean energy applications. Usually, the diffusion of the solute across the diaphragm constitutes a waste of free energy, which impairs the voltage generation of the concentration cell with respect to other well-known techniques that work quasi-reversibly, such as reverse electrodialysis or the "mixing entropy battery." Quite surprisingly, we find that the voltage produced by our concentration cell is significantly higher than the voltage obtained with the other quasi-reversible techniques. We show that the surplus voltage comes from the active transformation of the mixing free energy into electrical energy performed by the liquid junction, and we show the connection with the negative apparent transference number of the zinc ion. This fortunate consequence of using ZnCl2 solution is ultimately related to the formation of complexes. We present the results of a cell for power production, which has excellent performances with respect to known salinity-difference-power methods.

  17. Aerodynamic gradient measurements of the NH3-HNO3-NH4NO3 triad using a wet chemical instrument: an analysis of precision requirements and flux errors

    NASA Astrophysics Data System (ADS)

    Wolff, V.; Trebs, I.; Ammann, C.; Meixner, F. X.

    2010-02-01

    The aerodynamic gradient method is widely used for flux measurements of ammonia, nitric acid, particulate ammonium nitrate (the NH3-HNO3-NH4NO3 triad) and other water-soluble reactive trace compounds. The surface exchange flux is derived from a measured concentration difference and micrometeorological quantities (turbulent exchange coefficient). The significance of the measured concentration difference is crucial for the significant determination of surface exchange fluxes. Additionally, measurements of surface exchange fluxes of ammonia, nitric acid and ammonium nitrate are often strongly affected by phase changes between gaseous and particulate compounds of the triad, which make measurements of the four individual species (NH3, HNO3, NH4+, NO3- necessary for a correct interpretation of the measured concentration differences. We present here a rigorous analysis of results obtained with a multi-component, wet-chemical instrument, able to simultaneously measure gradients of both gaseous and particulate trace substances. Basis for our analysis are two field experiments, conducted above contrasting ecosystems (grassland, forest). Precision requirements of the instrument as well as errors of concentration differences and micrometeorological exchange parameters have been estimated, which, in turn, allows the establishment of thorough error estimates of the derived fluxes of NH3, HNO3, NH4+, and NO3-. Derived median flux errors for the grassland and forest field experiments were: 39% and 50% (NH3), 31% and 38% (HNO3), 62% and 57% (NH4+), and 47% and 68% (NO3-), respectively. Additionally, we provide the basis for using field data to characterize the instrument performance, as well as subsequent quantification of surface exchange fluxes and underlying mechanistic processes under realistic ambient measurement conditions.

  18. Aerodynamic gradient measurements of the NH3-HNO3-NH4NO3 triad using a wet chemical instrument: an analysis of precision requirements and flux errors

    NASA Astrophysics Data System (ADS)

    Wolff, V.; Trebs, I.; Ammann, C.; Meixner, F. X.

    2009-10-01

    The aerodynamic gradient method is widely used for flux measurements of ammonia, nitric acid, particulate ammonium nitrate (the NH3-HNO3-NH4NO3 triad) and other water-soluble reactive trace compounds. The surface exchange flux is derived from a measured concentration difference and micrometeorological quantities (turbulent exchange coefficient). The significance of the measured concentration difference is crucial for the significant determination of surface exchange fluxes. Additionally, measurements of surface exchange fluxes of ammonia, nitric acid and ammonium nitrate are often strongly affected by phase changes between gaseous and particulate compounds of the triad, which make measurements of the four individual species (NH3, HNO3, NH4+, NO3-) necessary for a correct interpretation of the measured concentration differences. We present here a rigorous analysis of results obtained with a multi-component, wet-chemical instrument, able to simultaneously measure gradients of both gaseous and particulate trace substances. Basis for our analysis are two field experiments, conducted above contrasting ecosystems (grassland, forest). Precision requirements of the instrument as well as errors of concentration differences and micrometeorological exchange parameters have been estimated, which, in turn, allows the establishment of thorough error estimates of the derived fluxes of NH3, HNO3, NH4+, and NO3-. Derived median flux errors for the grassland and forest field experiments were: 39 and 50% (NH3), 31 and 38% (HNO3), 62 and 57% (NH4+), and 47 and 68% (NO3-), respectively. Additionally, we provide the basis for using field data to characterize the instrument performance, as well as subsequent quantification of surface exchange fluxes and underlying mechanistic processes under realistic ambient measurement conditions.

  19. Seasonal Changes in Bacterial and Archaeal Gene Expression Patterns across Salinity Gradients in the Columbia River Coastal Margin

    PubMed Central

    Smith, Maria W.; Herfort, Lydie; Tyrol, Kaitlin; Suciu, Dominic; Campbell, Victoria; Crump, Byron C.; Peterson, Tawnya D.; Zuber, Peter; Baptista, Antonio M.; Simon, Holly M.

    2010-01-01

    Through their metabolic activities, microbial populations mediate the impact of high gradient regions on ecological function and productivity of the highly dynamic Columbia River coastal margin (CRCM). A 2226-probe oligonucleotide DNA microarray was developed to investigate expression patterns for microbial genes involved in nitrogen and carbon metabolism in the CRCM. Initial experiments with the environmental microarrays were directed toward validation of the platform and yielded high reproducibility in multiple tests. Bioinformatic and experimental validation also indicated that >85% of the microarray probes were specific for their corresponding target genes and for a few homologs within the same microbial family. The validated probe set was used to query gene expression responses by microbial assemblages to environmental variability. Sixty-four samples from the river, estuary, plume, and adjacent ocean were collected in different seasons and analyzed to correlate the measured variability in chemical, physical and biological water parameters to differences in global gene expression profiles. The method produced robust seasonal profiles corresponding to pre-freshet spring (April) and late summer (August). Overall relative gene expression was high in both seasons and was consistent with high microbial abundance measured by total RNA, heterotrophic bacterial production, and chlorophyll a. Both seasonal patterns involved large numbers of genes that were highly expressed relative to background, yet each produced very different gene expression profiles. April patterns revealed high differential gene expression in the coastal margin samples (estuary, plume and adjacent ocean) relative to freshwater, while little differential gene expression was observed along the river-to-ocean transition in August. Microbial gene expression profiles appeared to relate, in part, to seasonal differences in nutrient availability and potential resource competition. Furthermore, our results

  20. The role of effective leaf mixing length in the relationship between the δ18 O of stem cellulose and source water across a salinity gradient.

    PubMed

    Ellsworth, Patricia V; Ellsworth, Patrick Z; Anderson, William T; Sternberg, Leonel S L

    2013-01-01

    Previous mangrove tree ring studies attempted, unsuccessfully, to relate the δ(18) O of trunk cellulose (δ(18) O(CELL) ) to the δ(18) O of source water (δ(18) O(SW) ). Here, we tested whether biochemical fractionation associated with one of the oxygen in the cellulose glucose moiety or variation in leaf water oxygen isotope fractionation (Δ(LW) ) can interfere with the δ(18) O(SW) signal as it is recorded in the δ(18) O(CELL) of mangrove (saltwater) and hammock (freshwater) plants. We selected two transects experiencing a salinity gradient, located in the Florida Keys, USA. The δ(18) O(CELL) throughout both transects did not show the pattern expected based on that of the δ(18) O(SW) . We found that in one of the transects, biochemical fractionation interfered with the δ(18) O(SW) signal, while in the other transect Δ(LW) differed between mangrove and hammock plants. Observed differences in Δ(LW) between mangroves and hammocks were caused by a longer effective leaf mixing length (L) of the water pathway in mangrove leaves compared to those of hammock leaves. Changes in L could have caused the δ(18) O(CELL) to record not only variations in the δ(18) O(SW) but also in Δ(LW) making it impossible to isolate the δ(18) O(SW) signal. PMID:22716972

  1. Volatile halocarbons emissions through interaction of saltwater intrusion and terrestrial organic matter along a salinity gradient in coastal southeastern United States

    NASA Astrophysics Data System (ADS)

    Jiao, Y.; Wang, J. J.; Chow, A. T.; Rhew, R. C.

    2015-12-01

    Freshwater wetlands along the coast of southeastern United States can be subjected to inputs of halogens from seawater intrusion following long-term sea level rise. The interaction of halogens with organic-rich sediments can lead to the formation of organohalogens. In this study, we report field and laboratory emission rates of volatile halocarbons (methyl halides and chloroform) along a salinity gradient in coastal South Carolina, including freshwater forest, degraded oligohaline forest, and salt marsh. For chloroform, the oligohaline (intermediate) forest showed the largest mean emissions, compared to the freshwater forest and mesohaline saltmarsh. Soil cores were measured intact live, spread out live, intact dead, and spread out dead. Interestingly, the dead soil and live soil incubations showed no statistical difference in chloroform emissions, suggesting that their formation is predominately abiotic. For methyl chloride and methyl bromide, saltmarsh soils were sources while freshwater forest and degraded oligohaline forest soils were sinks. Sterilization of soils caused emissions rates to be higher, even converting sinks to sources, suggesting that live microorganisms and enzymes in the soils were sinks for the methyl halides, thereby masking the abiotic production rates. The simultaneous production and consumption of methyl halides in these soils is consistent with prior studies investigating the bidirectional fluxes of these compounds. Our study indicates that long-term sea level rise that turns freshwater forest wetlands to degraded forest wetlands or saltmarsh can significantly change the halocarbon biogeochemistry in southeastern United States.

  2. Highly robust thin-film composite pressure retarded osmosis (PRO) hollow fiber membranes with high power densities for renewable salinity-gradient energy generation.

    PubMed

    Han, Gang; Wang, Peng; Chung, Tai-Shung

    2013-07-16

    The practical application of pressure retarded osmosis (PRO) technology for renewable blue energy (i.e., osmotic power generation) from salinity gradient is being hindered by the absence of effective membranes. Compared to flat-sheet membranes, membranes with a hollow fiber configuration are of great interest due to their high packing density and spacer-free module fabrication. However, the development of PRO hollow fiber membranes is still in its infancy. This study aims to open up new perspectives and design strategies to molecularly construct highly robust thin film composite (TFC) PRO hollow fiber membranes with high power densities. The newly developed TFC PRO membranes consist of a selective polyamide skin formed on the lumen side of well-constructed Matrimid hollow fiber supports via interfacial polymerization. For the first time, laboratory PRO power generation tests demonstrate that the newly developed PRO hollow fiber membranes can withstand trans-membrane pressures up to 16 bar and exhibit a peak power density as high as 14 W/m(2) using seawater brine (1.0 M NaCl) as the draw solution and deionized water as the feed. We believe that the developed TFC PRO hollow fiber membranes have great potential for osmotic power harvesting. PMID:23772898

  3. RAPID MIGRATION OF RADIONUCLIDES LEAKED FROM HIGH-LEVEL WASTE TANKS: A STUDY OF SALINITY GRADIENTS, WETTED PATH GEOMETRY AND WATER VAPOR TRANSPORT

    EPA Science Inventory

    Of the 54 million gallons of radioactive and hazardous waste stored in mostly single-shelled, underground tanks (SST) at the Hanford Site, an estimated 1 million gallons have leaked into the vadose zone. It has long been assumed that leaked radionuclides did not travel far from ...

  4. Turbidity and salinity in a tropical northern Australian estuary and their influence on fish distribution

    NASA Astrophysics Data System (ADS)

    Cyrus, D. P.; Blaber, S. J. M.

    1992-12-01

    Turbidity and salinity and their influences on fish distribution were studied for two and a half years in the Embley Estuary in tropical northern Australia. Both turbidity and salinity varied significantly during the year but three clearly distinguishable seasonal patterns existed. These are referred to as the Wet, Early Dry and Late Dry Seasons. During each of these seasons distinct gradients of turbidity and salinity were present. The turbidity and salinity gradients were continuous with those in the adjacent marine environment of Albatross Bay. The levels and ranges of both factors were largely determined by the seasonal rainfall patterns in the catchment of the Embley River. The distribution and abundance of the 45 most common species was analysed in relation to turbidity, salinity and temperature patterns in the estuary. These data showed that fish densities within the estuary were related to turbidity and salinity but not temperature. There was a strong inverse relationship between turbidity and salinity. The Catch per Unit Effort (CPUE) of each species was determined in each of three broad ranges of turbidity and salinity. From this, patterns related to these two factors were found for 30 of the 45 species of fish.

  5. Salinization and Saline Environments

    NASA Astrophysics Data System (ADS)

    Vengosh, A.

    2003-12-01

    One of the most conspicuous phenomena of water-quality degradation, particularly in arid and semi-arid zones, is salinization of water and soil resources. Salinization is a long-term phenomenon, and during the last century many aquifers and river basins have become unsuitable for human consumption owing to high levels of salinity. Future exploitation of thousands of wells in the Middle East and in many other water-scarce regions in the world depends, to a large extent, on the degree and rate of salinization. Moreover, every year a large fraction of agricultural land is salinized and becomes unusable.Salinization is a global environmental phenomenon that affects many different aspects of our life (Williams, 2001a, b): changing the chemical composition of natural water resources (lakes, rivers, and groundwater), degrading the quality of water supply to the domestic and agriculture sectors, contribution to loss of biodiversity, taxonomic replacement by halotolerant species ( Williams, 2001a, b), loss of fertile soil, collapse of agricultural and fishery industries, changing of local climatic conditions, and creating severe health problems (e.g., the Aral Basin). The damage due to salinity in the Colorado River Basin alone, for example, ranges between 500 and 750 million per year and could exceed 1 billion per year if the salinity in the Imperial Dam increases from 700 mg L-1 to 900 mg L-1 (Bureau of Reclamation, 2003, USA). In Australia, accelerating soil salinization has become a massive environmental and economic disaster. Western Australia is "losing an area equal to one football oval an hour" due to spreading salinity ( Murphy, 1999). The annual cost for dryland salinity in Australia is estimated as AU700 million for lost land and AU$130 million for lost production ( Williams et al., 2002). In short, the salinization process has become pervasive.Salinity in water is usually defined by the chloride content (mg L-1) or total dissolved solids content (TDS, mg L-1or g

  6. Modified Whole Effluent Toxicity Test to Assess and Decouple Wastewater Effects from Environmental Gradients

    PubMed Central

    Sauco, Sebastián; Gómez, Julio; Barboza, Francisco R.; Lercari, Diego; Defeo, Omar

    2013-01-01

    Environmental gradients and wastewater discharges produce aggregated effects on marine populations, obscuring the detection of human impact. Classical assessment methods do not include environmental effects in toxicity tests designs, which could lead to incorrect conclusions. We proposed a modified Whole Effluent Toxicity test (mWET) that includes environmental gradients in addition to effluent dilutions, together with the application of Generalized Linear Mixed Models (GLMM) to assess and decouple those effects. We tested this approach, analyzing the lethal effects of wastewater on a marine sandy beach bivalve affected by an artificial canal freshwater discharge used for rice crops irrigation. To this end, we compared bivalve mortality between canal water dilutions (CWd) and salinity controls (SC: without canal water). CWd were prepared by diluting the water effluent (sampled during the pesticide application period) with artificial marine water. The salinity gradient was included in the design by achieving the same final salinities in both CWd and SC, allowing us to account for the effects of salinity by including this variable as a random factor in the GLMM. Our approach detected significantly higher mortalities in CWd, indicating potential toxic effects of the effluent discharge. mWET represents an improvement over the internationally standardized WET tests, since it considers environmental variability and uses appropriate statistical analyses. PMID:23755304

  7. Salinization and Saline Environments

    NASA Astrophysics Data System (ADS)

    Vengosh, A.

    2003-12-01

    One of the most conspicuous phenomena of water-quality degradation, particularly in arid and semi-arid zones, is salinization of water and soil resources. Salinization is a long-term phenomenon, and during the last century many aquifers and river basins have become unsuitable for human consumption owing to high levels of salinity. Future exploitation of thousands of wells in the Middle East and in many other water-scarce regions in the world depends, to a large extent, on the degree and rate of salinization. Moreover, every year a large fraction of agricultural land is salinized and becomes unusable.Salinization is a global environmental phenomenon that affects many different aspects of our life (Williams, 2001a, b): changing the chemical composition of natural water resources (lakes, rivers, and groundwater), degrading the quality of water supply to the domestic and agriculture sectors, contribution to loss of biodiversity, taxonomic replacement by halotolerant species ( Williams, 2001a, b), loss of fertile soil, collapse of agricultural and fishery industries, changing of local climatic conditions, and creating severe health problems (e.g., the Aral Basin). The damage due to salinity in the Colorado River Basin alone, for example, ranges between 500 and 750 million per year and could exceed 1 billion per year if the salinity in the Imperial Dam increases from 700 mg L-1 to 900 mg L-1 (Bureau of Reclamation, 2003, USA). In Australia, accelerating soil salinization has become a massive environmental and economic disaster. Western Australia is "losing an area equal to one football oval an hour" due to spreading salinity ( Murphy, 1999). The annual cost for dryland salinity in Australia is estimated as AU700 million for lost land and AU$130 million for lost production ( Williams et al., 2002). In short, the salinization process has become pervasive.Salinity in water is usually defined by the chloride content (mg L-1) or total dissolved solids content (TDS, mg L-1or g

  8. Do invaders always perform better? Comparing the response of native and invasive shrimps to temperature and salinity gradients in south-west Spain

    NASA Astrophysics Data System (ADS)

    Lejeusne, Christophe; Latchere, Oïhana; Petit, Nicolas; Rico, Ciro; Green, Andy J.

    2014-01-01

    Invasive species are often thought to benefit from climate change, outcompeting native species as temperatures increase. However, the physiological tolerance has been little explored as a potential mechanism explaining biological invasion success. In this study, we used empirical data from both invasive and native estuarine species as a case study to address the hypotheses that (1) invasive species show a better resistance to acute thermal stress, (2) invasive species present lower oxygen consumption rates owing to greater resistance to environmental stressors, and (3) native species have lower survival rates under chronic temperature and salinity stress. We conducted various comparative experiments on three sympatric and syntopic closely related shrimp species (one invasive Palaemon macrodactylus, and two natives Palaemon longirostris and Palaemonetes varians). We evaluated their critical temperature maxima, their oxygen consumption rates under different salinities and temperatures, and their survival rates under chronic salinity and temperature. We found that the invasive species was the most tolerant to rapid increase in temperature, and consistently consumed less oxygen over a broad range of temperatures and salinities. Palaemon macrodactylus also had lower mortality rates at high temperatures than P. longirostris. These results support previously reported differences in physiological tolerance between native and invasive species, with the invasive species always performing better. The consistently higher tolerance of the non-indigenous species to temperature variation suggests that climate change will increase the success of invaders.

  9. Measuring sap flow, and other plant physiological conditions across a soil salinity gradient in the lower Colorado River at Cibola National Wildlife Refuge: Vegetation and soil physiology linkages with microwave dielectric constant

    NASA Astrophysics Data System (ADS)

    McDonald, K. C.; Lasne, Y.; Schroeder, R.; Morino, K.; Hultine, K. R.; Nagler, P. L.

    2009-12-01

    We used ground measurements to examine stand structure and evapotranspiration of Tamarix in the Cibola National Wildlife Refuge (CNWR) on the Lower Colorado River. Three Tamarix study sites were established at different distances from the Colorado River on a river terrace in the CNWR. The sites were chosen from aerial photographs to represent typical dense stands of Tamarix within the CNWR. The sites were representative of differing saline environments, with each having ground water with distinct salt concentration levels. Wells were established at the site to establish depth to water and the salinity concentration within the ground water. We monitored xylem sap flow within each of the three stands. In addition we measured leaf area index to characterize canopy structure. We compared ET, foliage density, depth to water, and salinity among the Tamarix sites to examine stand-level variability driven by the variations in salinity. We supplemented these collections with measurements to characterize soil and vegetation microwave dielectric properties and their relationship to physiologic parameters. The dielectric properties of a material describe the interaction of an electric field with the material. Previous field experiments have demonstrated that varying degrees of correlation exist between vegetation dielectric properties and tree canopy water status. Temporal variation of the dielectric constant of woody plant tissue may result from changes in water status (e.g., water content) and chemical composition, albeit to varying degrees of sensitivity. The varying amount of ground water salinity at CNWR offers a unique opportunity to examine the relationship between vegetation and soil dielectric constant as related to vegetation ecophysiology. A field portable vector network analyzer is used to measure the microwave dielectric spectrum of the soil and vegetation Combined with measurements of vegetation xylem sap flux and soil chemistry, these measurements allow

  10. Determination of Bromine Stable Isotope Ratios from Saline Solutions by "Wet Plasma" MC-ICPMS Including a Comparison between High- and Low-Resolution Modes, and Three Introduction Systems.

    PubMed

    Louvat, Pascale; Bonifacie, Magali; Giunta, Thomas; Michel, Agnès; Coleman, Max

    2016-04-01

    We describe a novel method for measuring stable bromine isotope compositions in saline solutions such as seawater, brines, and formation waters. Bromine is extracted from the samples by ion exchange chromatography on anion exchange resin AG 1-X4 with NH4NO3 and measured by MC-ICP-MS in wet plasma conditions. Sample introduction through a small spray chamber provided good sensitivity and stability of the Br signal compared to direct injection (d-DIHEN) and desolvation (APEX). NH4NO3 media allowed fast (<3 min) washing of the system. Despite Ar2H(+) spectral interference on (81)Br(+), for the first time low-resolution mode (with appropriate tuning of Ar2H(+)/(81)Br(+) sensitivity) gave higher precision (81)Br/(79)Br measurements than high-resolution (HR), due to the narrowness of the (81)Br(+) plateau in HR mode and to slight mass drifting with time. Additionally, 1 μg Br is the lower amount needed for a triplicate determination of δ(81)Br by MC-ICP-MS, with reproducibility often < ± 0.1‰ (2 SD). Four HBr solutions were prepared by evaporation/condensation in order to obtain in-house reference solutions with 3‰ variations in δ(81)Br and to assess the reproducibility and accuracy of the method. Long-term (>3 years) reproducibility between ± 0.11 and ± 0.27‰ (2 SD) was obtained for the four HBr solutions, the international standard reference material NIST SRM 977 (δ(81)BrSMOB = -0.65 ± 1.1‰, 1 SD), and seawaters (synthetic and natural). The accuracy of the MC-ICP-MS method was validated by comparing the δ(81)Br obtained for these solutions with dual-inlet IRMS measurements on CH3Br gas. Finally, the method was successfully applied to 22 natural samples. PMID:26898343

  11. Spatial and Temporal Variability in Carbon Dioxide Fluxes at Three Coastal Marshes Along a Salinity Gradient in the Northern Gulf of Mexico: how Susceptible are Coastal Marshes in the Region to Future Wariming?

    NASA Astrophysics Data System (ADS)

    Mortazavi, B.; Wilson, B.; Kiene, R. P.

    2014-12-01

    Carbon gas fluxes in tidal marshes vary spatially and temporally because of vegetation cover, subsurface biogeochemical processes, and environmental forcing and predicting the impact of climate change on greenhouse gas fluxes from wetlands remains challenging. We examined how ecosystem carbon gas exchange varies along a salinity gradient (0-32 ppt) in three marshes along an estuary in the northern Gulf of Mexico, USA. Midday net ecosystem exchange (where a negative rate indicates net carbon assimilated through photosynthesis) was greatest at the most freshwater site (4.8 ± 0.3 μmol CO2 m-2 s-1), followed by the saline (2.8 ± 1.0 μmol CO2 m-2 s-1) and brackish (1.4 ± 0.6 μmol CO2 m-2 s-1) sites. However, net ecosystem exchange integrated diurnally revealed each marsh to be a net CO2 source to the atmosphere as a result of high ecosystem respiration with no significant difference across the fresh (105.5 ± 28.9 mmol CO2 m-2 d-1), brackish (100.1 ± 36.5 mmol CO2 m-2 d-1), and salt marsh (78.3 ± 28.6 mmol CO2 m-2 d-1) sites. The large loss of carbon from these ecosystems is suggested to be a contributing factor to the disappearances of marshes in the region. Fifty percent of coastal Alabama wetlands, for examples, have disappeared from 1780 to 1980, and between 1955 and 1979 the percent loss (29%) in the region has exceeded the national average by a factor of three. While future warming is not expected to impact carbon assimilation significantly, our warming simulations suggest that carbon loss in these ecosystems can be enhanced by 12 to 26%, potentially exasperating the loss of marshes in the region.

  12. [Wet work].

    PubMed

    Kieć-Swierczyńska, Marta; Chomiczewska, Dorota; Krecisz, Beata

    2010-01-01

    Wet work is one of the most important risk factors of occupational skin diseases. Exposure of hands to the wet environment for more than 2 hours daily, wearing moisture-proof protective gloves for a corresponding period of time or necessity to wash hands frequently lead to the disruption of epidermal stratum corneum, damage to skin barrier function and induction of irritant contact dermatitis. It may also promote penetration of allergens into the skin and increase the risk of sensitization to occupational allergens. Exposure to wet work plays a significant role in occupations, such as hairdressers and barbers, nurses and other health care workers, cleaning staff, food handlers and metalworkers. It is more common among women because many occupations involving wet work are female-dominated. The incidence of wet-work-induced occupational skin diseases can be reduced by taking appropriate preventive measures. These include identification of high-risk groups, education of workers, organization of work enabling to minimize the exposure to wet work, use of personal protective equipment and skin care after work. PMID:20437890

  13. Vapor Diffusion as a Mechanism for Moisture Redistribution in Unsaturated Flow Systems with Variable Salinity

    NASA Astrophysics Data System (ADS)

    Xu, T.; Pruess, K.

    2001-12-01

    Understanding movement of saline waste solutions is important for assessing the contaminant migration near leaking waste storage tanks in the unsaturated zone at the Hanford site (Washington, USA). Laboratory experiments presented by Selker and collaborators at AGU 2000 Fall Meeting have shown that vapor diffusion can be an important mechanism for redistributing moisture in unsaturated flow systems with salinity gradients. The effect arises from the dependence of vapor pressure on salinity. Vapor pressures of salt solutions generally decrease with salt concentration, which results in a vapor pressure gradient and induces vapor diffusion from low to high salt concentration regions. Vapor then condenses in the high concentration regions and increases the liquid water saturation there. We have performed numerical experiments to study this salinity-driven moisture redistribution. Systematic simulation studies use different values of thermal conductivity, permeability, and temperature, to illustrate conditions and parameters controlling these processes. Results indicate that significant effects occur rapidly (hours) over rather small spatial scales (mm to cm), requiring very fine space discretization. The rapid occurrence is consistent with laboratory experiments of Selker and collaborators that show that significant transport of water of pre-wetted sand into highly saline NaNO3 solution plumes takes place in a matter of hours. Heat conduction plays a very important role in this salinity-driven vapor diffusion by maintaining a nearly constant temperature. The smaller the permeability, the more water is transferred into the saline region. Effects of permeability on water flow are complicated by effects of capillary pressure and tortuosity. The salinity driven-fluid flow is more significant at higher temperature. This work was supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098 through Memorandum Purchase Order 248861-A-B2 between Pacific

  14. Microbial community analysis in the denitrification process of saline-wastewater by denaturing gradient gel electrophoresis of PCR-amplified 16S rDNA and the cultivation method.

    PubMed

    Yoshie, S; Noda, N; Miyano, T; Tsuneda, S; Hirata, A; Inamori, Y

    2001-01-01

    The metallurgic wastewater generated from the processes of recovering precious metals from industrial wastes contains high concentrations of nitrogen compounds and salts. Biological nitrogen removal from this wastewater was attempted using a circulating bioreactor system equipped with an anaerobic packed bed or an anaerobic fluidized bed. The denitrification capability of the system with the anaerobic packed bed was more stable than that of the system with the anaerobic fluidized bed. The NOx removal rate of the anaerobic packed bed was as high as 97%. Microbial community analysis by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA (rDNA) fragments and the cultivation method revealed that the community diversity varied in accordance with wastewater composition such as the level of salinity and so on. Phylogenetic analysis suggested that the taxonomic affiliation of the dominant species in the anaerobic reactors was to the gamma-Proteobacteria including Halomonadaceae species. The PCR-DGGE method as a non-cultivation method was found to be a powerful tool for analysis of the microbial community, because the cultivation method could detect only a fraction of the microbial species present in these systems. The genetic diversity of the isolated bacteria belonging to the gamma-Proteobacteria which reduced both nitrate and nitrite in the anaerobic packed bed was higher than that of the bacteria in the anaerobic fluidized bed. This suggested that a genetically diverse microbial community stabilized the denitrifying performance in the anaerobic packed bed. PMID:16233109

  15. Salinity Energy.

    ERIC Educational Resources Information Center

    Schmitt, Walter R.

    1987-01-01

    Discussed are the costs of deriving energy from the earth's natural reserves of salt. Argues that, as fossil fuel supplies become more depleted in the future, the environmental advantages of salinity power may prove to warrant its exploitation. (TW)

  16. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... locations if possible, or perish. In the freshwater zone, discharge operations in the upstream regions can... those organisms that are adapted to freshwater environments. It may also affect municipal water...

  17. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... locations if possible, or perish. In the freshwater zone, discharge operations in the upstream regions can... those organisms that are adapted to freshwater environments. It may also affect municipal water...

  18. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... locations if possible, or perish. In the freshwater zone, discharge operations in the upstream regions can... those organisms that are adapted to freshwater environments. It may also affect municipal water...

  19. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... locations if possible, or perish. In the freshwater zone, discharge operations in the upstream regions can... those organisms that are adapted to freshwater environments. It may also affect municipal water...

  20. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... locations if possible, or perish. In the freshwater zone, discharge operations in the upstream regions can... those organisms that are adapted to freshwater environments. It may also affect municipal water...

  1. [Ecophysiological adaptability of tropical water organisms to salinity changes].

    PubMed

    Chung, K S

    2001-03-01

    Physiological response of tropical organisms to salinity changes was studied for some marine, estuarine and freshwater fishes (Astyanax bimaculatus, Petenia karussii, Cyprinodon dearborni, and Oreochromis mossambicus), marine and freshwater crustaceans (Penaeus brasiliensis, Penaeus schmitti and Macrobrachium carcinus), and marine bivalves (Perna perna, Crassostrea rhizophorae, and Arca zebra) collected from Northeast Venezuela. They were acclimated for four weeks at various salinities, and (1) placed at high salinities to determine mean lethal salinity, (2) tested by increasing salinity 5@1000 per day to define upper lethal salinity tolerance limit, or (3) observed in a saline gradient tank to determine salinity preference. Acclimation level was the most significant factor. This phenomenon is important for tropical aquatic organisms in shallow waters, where they can adapt to high salinity during the dry season and cannot lose their acclimation level at low salinity during abrupt rain. For saline adaptation of tropical organisms, this behavior will contribute to their proliferation and distribution in fluctuating salinity environments. PMID:11795174

  2. Silver toxicity across salinity gradients: the role of dissolved silver chloride species (AgCl x ) in Atlantic killifish (Fundulus heteroclitus) and medaka (Oryzias latipes) early life-stage toxicity.

    PubMed

    Matson, Cole W; Bone, Audrey J; Auffan, Mélanie; Lindberg, T Ty; Arnold, Mariah C; Hsu-Kim, Heileen; Wiesner, Mark R; Di Giulio, Richard T

    2016-08-01

    The influence of salinity on Ag toxicity was investigated in Atlantic killifish (Fundulus heteroclitus) early life-stages. Embryo mortality was significantly reduced as salinity increased and Ag(+) was converted to AgCl(solid). However, as salinity continued to rise (>5 ‰), toxicity increased to a level at least as high as observed for Ag(+) in deionized water. Rather than correlating with Ag(+), Fundulus embryo toxicity was better explained (R(2) = 0.96) by total dissolved Ag (Ag(+), AgCl2 (-), AgCl3 (2-), AgCl4 (3-)). Complementary experiments were conducted with medaka (Oryzias latipes) embryos to determine if this pattern was consistent among evolutionarily divergent euryhaline species. Contrary to Fundulus data, medaka toxicity data were best explained by Ag(+) concentrations (R(2) = 0.94), suggesting that differing ionoregulatory physiology may drive observed differences. Fundulus larvae were also tested, and toxicity did increase at higher salinities, but did not track predicted silver speciation. Alternatively, toxicity began to increase only at salinities above the isosmotic point, suggesting that shifts in osmoregulatory strategy at higher salinities might be an important factor. Na(+) dysregulation was confirmed as the mechanism of toxicity in Ag-exposed Fundulus larvae at both low and high salinities. While Ag uptake was highest at low salinities for both Fundulus embryos and larvae, uptake was not predictive of toxicity. PMID:27170044

  3. Soil Fertility Gradient in the Restinga Ecosystem

    NASA Astrophysics Data System (ADS)

    América Castelar da Cunha, Joana; Casagrande, José Carlos; Soares, Marcio Roberto; Martins Bonilha, Rodolfo

    2013-04-01

    The restinga ecosystem (coastal plain vegetation) can be termed as a set of plant communities that suffer strong influenced by fluvial and marine factors and is characterized as an ecosystem of great biological diversity, therefore, represents areas of great importance in the context of ecological preservation. The degradation processes from many forms of anthropogenic disturbances that has taken place since the colonization of the country, made studies on the characterization and dynamics of soil fertility of these areas even more important in relation to the maintenance of its biodiversity and conservation. The sites studied were the Cardoso Island and Comprida Island, and in these, we analyzed four physiognomies, restinga, low restinga, dune and antedune (from continent to ocean). Chemical analyses were performed and soil salinity in these areas in depths 0-5; 0-10; 0-20; 20-40; 40-60 cm. In all soils the cationic exchange capacity was intimately associated with the concentration of soil organic matter, which makes this parameter essential to the maintenance of soil fertility of these areas; in more superficial layers (0-20 cm) there was an increase of pH and base saturation and decline of organic matter, aluminum saturation and cationic exchange capacity in the nearby sea, physiognomies what determines the existence of fertility gradient towards the continent-coast; restinga forests showed a chemical standard that is heavily marked by sandy texture, high degree of leaching, nutrient poverty, low base saturation, high saturation by aluminum and acidity, opposite conditions to soils of the dunes and antedunes, with the exception of sandy texture; despite the existence of a chemical gradient of fertility among the physiognomies studied it is possible to determine the soil acts more strongly as a physical support than as provider of fertility; as for salinity, soil collected in Cardoso Island did not present salinity in any depth, a fact which can be explained due

  4. Saline Sinus Rinse Recipe

    MedlinePlus

    ... Saline Sinus Rinse Recipe Share | Saline Sinus Rinse Recipe Saline sinus rinses can bring relief to patients ... at a fraction of the cost. Saline Rinse Recipe Ingredients 1. Pickling or canning salt-containing no ...

  5. Wetting in Color

    NASA Astrophysics Data System (ADS)

    Burgess, Ian Bruce

    Colorimetric litmus tests such as pH paper have enjoyed wide commercial success due to their inexpensive production and exceptional ease of use. However, expansion of colorimetry to new sensing paradigms is challenging because macroscopic color changes are seldom coupled to arbitrary differences in the physical/chemical properties of a system. In this thesis I present in detail the development of Wetting in Color Technology, focusing primarily on its application as an inexpensive and highly selective colorimetric indicator for organic liquids. The technology exploits chemically-encoded inverse-opal photonic crystals to control the infiltration of fluids to liquid-specific spatial patterns, projecting minute differences in liquids' wettability to macroscopically distinct, easy-to-visualize structural color patterns. It is shown experimentally and corroborated with theoretical modeling using percolation theory that the high selectivity of wetting, upon-which the sensitivity of the indicator relies, is caused by the highly symmetric structure of our large-area, defect-free SiO2 inverse-opals. The regular structure also produces a bright iridescent color, which disappears when infiltrated with liquid - naturally coupling the optical and fluidic responses. Surface modification protocols are developed, requiring only silanization and selective oxidation, to facilitate the deterministic design of an indicator that differentiates a broad range of liquids. The resulting tunable, built-in horizontal and vertical chemistry gradients allow the wettability threshold to be tailored to specific liquids across a continuous range, and make the readout rely only on countable color differences. As wetting is a generic fluidic phenomenon, Wetting in Color technology could be suitable for applications in authentication or identification of unknown liquids across a broad range of industries. However, the generic nature of the response also ensures chemical non-specificity. It is shown

  6. Hypertonic saline.

    PubMed

    Constable, P D

    1999-11-01

    A key feature in the successful resuscitation of dehydrated or endotoxemic ruminants is the total amount of sodium administered. Administration of small volumes of HS and HSD offer major advantages over large volumes of isotonic saline because HS and HSD do not require intravenous catheterization or periodic monitoring, and are therefore suitable for use in the field. Hypertonic saline and HSD exert their beneficial effect by rapidly increasing preload and transiently decreasing afterload. Contrary to early reports, HS and HSD decrease cardiac contractility and do not activate a pulmonary reflex. The osmolality of HS and HSD should be 2400 mOsm/L (7.2% NaCl solution, 8 times normal plasma osmolality). Use of HS and HSD solutions of different osmolality to 2400 mOsm/L should be avoided at all costs, as too low a tonicity removes the main advantages of HS (low cost, decreased infusion time), whereas too high a tonicity may cause rapid vasodilation and decreased cardiac contractility, resulting in death. Rapid administration (> 1 mL/kg-1/min-1) of HS (2400 mOsm/L) should be avoided, as the induced hypotension may be fatal when coupled with a transient decrease in cardiac contractility. For treating dehydrated adult ruminants, HS (2400 mOsm/L, 4-5 mL/kg i.v. over 4-5 minutes) should be administered through the jugular vein and the cow allowed to drink water. This means that 2 L of HS should be administered to adult cattle. HSD should be administered in conjunction with isotonic oral electrolyte solutions to all calves 8% or more dehydrated (eyes recessed > or = 4 mm into the orbit, cervical skin tent duration > 6 seconds) or calves with reduced cardiac output (fetlock temperature < 29 degrees C when housed at 10-24 degrees C). For treating dehydrated calves, HSD (2400 mOsm/L NaCl in 6% dextran-70, 4-5 mL/kg i.v. over 4-5 minutes) should be administered through the jugular vein and the calf allowed to suckle an isotonic oral electrolyte solution. This means that 120

  7. Practically Saline.

    PubMed

    Schroeder, Jonathan; O'Neal, Catherine; Jagneaux, Tonya

    2015-01-01

    Introduction. In December 2014, the Food and Drug Administration issued a recall of all Wallcur simulation products due to reports of their use in clinical practice. We present a case of septic shock and multiorgan failure after the accidental intravenous infusion of a nonsterile Wallcur simulation product. Case. The patient presented with symptoms of rigors and dyspnea occurring immediately after infusion of Wallcur Practi-0.9% saline. Initial laboratory evidence was consistent with severe septic shock and multiorgan dysfunction. His initial lactic acid level was 9 mmol/L (reference range = 0.5-2.2), and he had evidence of acute kidney injury and markers of disseminated intravascular coagulation. All 4 blood culture bottles isolated multidrug-resistant Empedobacter brevis. The patient recovered from his illness and was discharged with ciprofloxacin therapy per susceptibilities. Discussion. This patient represents the first described case of severe septic shock associated with the infusion of a Wallcur simulation product. Intravenous inoculation of a nonsterile fluid is rare and exposes the patient to unusual environmental organisms, toxins, or unsafe fluid characteristics such as tonicity. During course of treatment, we identified the possible culprit to be a multidrug-resistant isolate of Empedobacter brevis. We also discuss the systemic failures that led to this outbreak. PMID:26668812

  8. Saline Valley

    NASA Technical Reports Server (NTRS)

    2001-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1 Figure 2

    These images of the Saline Valley area, California, were acquired March 30, 2000 and cover a full ASTER scene (60 by 60 km). Each image displays data from a different spectral region, and illustrates the complementary nature of surface compositional information available as a function of wavelength. This image displays visible and near infrared bands 3, 2, and 1 in red, green, and blue (RGB). Vegetation appears red, snow and dry salt lakes are white, and exposed rocks are brown, gray, yellow and blue. Rock colors mainly reflect the presence of iron minerals, and variations in albedo. Figure 1 displays short wavelength infrared bands 4, 6, and 8 as RGB. In this wavelength region, clay, carbonate, and sulfate minerals have diagnostic absorption features, resulting in distinct colors on the image. For example, limestones are yellow-green, and purple areas are kaolinite-rich. Figure 2 displays thermal infrared bands 13, 12 and 10 as RGB. In this wavelength region, variations in quartz content appear as more or less red; carbonate rocks are green, and mafic volcanic rocks are purple. The image is located at 36.8 degrees north latitude and 117.7 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  9. Practically Saline

    PubMed Central

    Schroeder, Jonathan; O’Neal, Catherine; Jagneaux, Tonya

    2015-01-01

    Introduction. In December 2014, the Food and Drug Administration issued a recall of all Wallcur simulation products due to reports of their use in clinical practice. We present a case of septic shock and multiorgan failure after the accidental intravenous infusion of a nonsterile Wallcur simulation product. Case. The patient presented with symptoms of rigors and dyspnea occurring immediately after infusion of Wallcur Practi-0.9% saline. Initial laboratory evidence was consistent with severe septic shock and multiorgan dysfunction. His initial lactic acid level was 9 mmol/L (reference range = 0.5-2.2), and he had evidence of acute kidney injury and markers of disseminated intravascular coagulation. All 4 blood culture bottles isolated multidrug-resistant Empedobacter brevis. The patient recovered from his illness and was discharged with ciprofloxacin therapy per susceptibilities. Discussion. This patient represents the first described case of severe septic shock associated with the infusion of a Wallcur simulation product. Intravenous inoculation of a nonsterile fluid is rare and exposes the patient to unusual environmental organisms, toxins, or unsafe fluid characteristics such as tonicity. During course of treatment, we identified the possible culprit to be a multidrug-resistant isolate of Empedobacter brevis. We also discuss the systemic failures that led to this outbreak. PMID:26668812

  10. Salinity dominance on the Indian Ocean Eastern Gyral current

    NASA Astrophysics Data System (ADS)

    Menezes, Viviane V.; Phillips, Helen E.; Schiller, Andreas; Domingues, Catia M.; Bindoff, Nathaniel L.

    2013-11-01

    This study demonstrates the importance of salinity gradients to the formation of the Eastern Gyral Current (EGC) in the South Indian Ocean. The EGC flows eastward near 15∘S, opposite to the direction predicted by classical theories of wind-driven circulation and is a source of water for the Leeuwin Current. In the upper ocean, a strong salinity front exists between fresh water from the Indonesian Throughflow (ITF) in the South Equatorial Current (SEC) and salty subtropical waters. In that region, salinity overwhelms the temperature contribution to density gradients, generating eastward geostrophic shear and establishing the EGC. Without the salinity front the EGC cannot be maintained: If the salinity contribution is neglected in the calculation of geostrophic currents, the EGC vanishes. Our observational analysis associated with the fact that both Sverdrup and Ekman theories produce westward flows in the region strongly supports the idea that the EGC is a salinity-driven current.

  11. Enuresis (Bed-Wetting)

    MedlinePlus

    ... their development. Bed-wetting is more common among boys than girls. What causes bed-wetting? A number of things ... valves in boys or in the ureter in girls or boys Abnormalities in the spinal cord A small bladder ...

  12. On observing acoustic backscattering from salinity turbulence.

    PubMed

    Goodman, Louis; Sastre-Cordova, Marcos M

    2011-08-01

    It has been hypothesized that at sufficiently high levels of oceanic salinity turbulence it should be possible to observe acoustic backscattering. However, there have been limited in situ measurements to confirm this hypothesis. Using an autonomous underwater vehicle equipped with upward and downward looking 1.2 MHz acoustic Doppler current profilers and with turbulence and fine scale sensors, measurements were performed in a region of intense turbulence and a strong salinity gradient. The approach taken was to correlate variations in the backscattered acoustic intensity, I, with a theoretical acoustic backscattering cross section per volume for salinity turbulence, σ(s), to obtain an estimated scattering cross section per volume, σ(e). Results indicated that of order 50% of the observed region was characterized by salinity turbulence induced backscattering. PMID:21877785

  13. Reconstructing Past Ocean Salinity ((delta)18Owater)

    SciTech Connect

    Guilderson, T P; Pak, D K

    2005-11-23

    Temperature and salinity are two of the key properties of ocean water masses. The distribution of these two independent but related characteristics reflects the interplay of incoming solar radiation (insolation) and the uneven distribution of heat loss and gain by the ocean, with that of precipitation, evaporation, and the freezing and melting of ice. Temperature and salinity to a large extent, determine the density of a parcel of water. Small differences in temperature and salinity can increase or decrease the density of a water parcel, which can lead to convection. Once removed from the surface of the ocean where 'local' changes in temperature and salinity can occur, the water parcel retains its distinct relationship between (potential) temperature and salinity. We can take advantage of this 'conservative' behavior where changes only occur as a result of mixing processes, to track the movement of water in the deep ocean (Figure 1). The distribution of density in the ocean is directly related to horizontal pressure gradients and thus (geostrophic) ocean currents. During the Quaternary when we have had systematic growth and decay of large land based ice sheets, salinity has had to change. A quick scaling argument following that of Broecker and Peng [1982] is: the modern ocean has a mean salinity of 34.7 psu and is on average 3500m deep. During glacial maxima sea level was on the order of {approx}120m lower than present. Simply scaling the loss of freshwater (3-4%) requires an average increase in salinity a similar percentage or to {approx}35.9psu. Because much of the deep ocean is of similar temperature, small changes in salinity have a large impact on density, yielding a potentially different distribution of water masses and control of the density driven (thermohaline) ocean circulation. It is partly for this reason that reconstructions of past salinity are of interest to paleoceanographers.

  14. Wetting in electrolyte solutions.

    PubMed

    Ibagon, Ingrid; Bier, Markus; Dietrich, S

    2013-06-01

    Wetting of a charged substrate by an electrolyte solution is investigated by means of classical density functional theory applied to a lattice model. Within the present model the pure, i.e., salt-free solvent, for which all interactions are of the nearest-neighbor type only, exhibits a second-order wetting transition for all strengths of the substrate-particle and the particle-particle interactions for which the wetting transition temperature is nonzero. The influences of the substrate charge density and of the ionic strength on the wetting transition temperature and on the order of the wetting transition are studied. If the substrate is neutral, the addition of salt to the solvent changes neither the order nor the transition temperature of the wetting transition of the system. If the surface charge is nonzero, upon adding salt this continuous wetting transition changes to first-order within the wide range of substrate surface charge densities and ionic strengths studied here. As the substrate surface charge density is increased, at fixed ionic strength, the wetting transition temperature decreases and the prewetting line associated with the first-order wetting transition becomes longer. This decrease of the wetting transition temperature upon increasing the surface charge density becomes more pronounced by decreasing the ionic strength. PMID:23758391

  15. Measuring Salinity by Conductivity.

    ERIC Educational Resources Information Center

    Lapworth, C. J.

    1981-01-01

    Outlines procedures for constructing an instrument which uses an electrode and calibration methods to measure the salinity of waters in environments close to and affected by a saline estuary. (Author/DC)

  16. Origins of Wetting.

    PubMed

    Extrand, Charles W

    2016-08-01

    This feature article provides an overview of wetting phenomena. Much of the analysis done on wetting in the last 100 years assumes that the phenomena are determined by molecular interactions within the interfacial area between the liquid and solid. However, there is now ample evidence that wetting is controlled by interactions in the vicinity of the contact line where the liquid and solid meet. Recent experiments and modeling that demonstrate this are reviewed. PMID:27459085

  17. PREFACE: Dynamics of wetting Dynamics of wetting

    NASA Astrophysics Data System (ADS)

    Grest, Gary S.; Oshanin, Gleb; Webb, Edmund B., III

    2009-11-01

    Capillary phenomena associated with fluids wetting other condensed matter phases have drawn great scientific interest for hundreds of years; consider the recent bicentennial celebration of Thomas Young's paper on equilibrium contact angles, describing the geometric shape assumed near a three phase contact line in terms of the relevant surface energies of the constituent phases [1]. Indeed, nearly a century has passed since the seminal papers of Lucas and Washburn, describing dynamics of capillary imbibition [2, 3]. While it is generally appreciated that dynamics of fluid wetting processes are determined by the degree to which a system is out of capillary equilibrium, myriad complications exist that challenge the fundamental understanding of dynamic capillary phenomena. The topic has gathered much interest from recent Nobel laureate Pierre-Gilles de Gennes, who provided a seminal review of relevant dissipation mechanisms for fluid droplets spreading on solid surfaces [4] Although much about the dynamics of wetting has been revealed, much remains to be learned and intrinsic technological and fundamental interest in the topic drives continuing high levels of research activity. This is enabled partly by improved experimental capabilities for resolving wetting processes at increasingly finer temporal, spatial, and chemical resolution. Additionally, dynamic wetting research advances via higher fidelity computational modeling capabilities, which drive more highly refined theory development. The significance of this topic both fundamentally and technologically has resulted in a number of reviews of research activity in wetting dynamics. One recent example addresses the evaluation of existing wetting dynamics theories from an experimentalist's perspective [5]. A Current Opinion issue was recently dedicated to high temperature capillarity, including dynamics of high temperature spreading [6]. New educational tools have recently emerged for providing instruction in wetting

  18. Wetting and spreading

    NASA Astrophysics Data System (ADS)

    Bonn, Daniel; Eggers, Jens; Indekeu, Joseph; Meunier, Jacques; Rolley, Etienne

    2009-04-01

    Wetting phenomena are ubiquitous in nature and technology. A solid substrate exposed to the environment is almost invariably covered by a layer of fluid material. In this review, the surface forces that lead to wetting are considered, and the equilibrium surface coverage of a substrate in contact with a drop of liquid. Depending on the nature of the surface forces involved, different scenarios for wetting phase transitions are possible; recent progress allows us to relate the critical exponents directly to the nature of the surface forces which lead to the different wetting scenarios. Thermal fluctuation effects, which can be greatly enhanced for wetting of geometrically or chemically structured substrates, and are much stronger in colloidal suspensions, modify the adsorption singularities. Macroscopic descriptions and microscopic theories have been developed to understand and predict wetting behavior relevant to microfluidics and nanofluidics applications. Then the dynamics of wetting is examined. A drop, placed on a substrate which it wets, spreads out to form a film. Conversely, a nonwetted substrate previously covered by a film dewets upon an appropriate change of system parameters. The hydrodynamics of both wetting and dewetting is influenced by the presence of the three-phase contact line separating “wet” regions from those that are either dry or covered by a microscopic film only. Recent theoretical, experimental, and numerical progress in the description of moving contact line dynamics are reviewed, and its relation to the thermodynamics of wetting is explored. In addition, recent progress on rough surfaces is surveyed. The anchoring of contact lines and contact angle hysteresis are explored resulting from surface inhomogeneities. Further, new ways to mold wetting characteristics according to technological constraints are discussed, for example, the use of patterned surfaces, surfactants, or complex fluids.

  19. Wettability alteration of oil-wet carbonate by silica nanofluid.

    PubMed

    Al-Anssari, Sarmad; Barifcani, Ahmed; Wang, Shaobin; Maxim, Lebedev; Iglauer, Stefan

    2016-01-01

    Changing oil-wet surfaces toward higher water wettability is of key importance in subsurface engineering applications. This includes petroleum recovery from fractured limestone reservoirs, which are typically mixed or oil-wet, resulting in poor productivity as conventional waterflooding techniques are inefficient. A wettability change toward more water-wet would significantly improve oil displacement efficiency, and thus productivity. Another area where such a wettability shift would be highly beneficial is carbon geo-sequestration, where compressed CO2 is pumped underground for storage. It has recently been identified that more water-wet formations can store more CO2. We thus examined how silica based nanofluids can induce such a wettability shift on oil-wet and mixed-wet calcite substrates. We found that silica nanoparticles have an ability to alter the wettability of such calcite surfaces. Nanoparticle concentration and brine salinity had a significant effect on the wettability alteration efficiency, and an optimum salinity was identified, analogous to that one found for surfactant formulations. Mechanistically, most nanoparticles irreversibly adhered to the oil-wet calcite surface (as substantiated by SEM-EDS and AFM measurements). We conclude that such nanofluid formulations can be very effective as enhanced hydrocarbon recovery agents and can potentially be used for improving the efficiency of CO2 geo-storage. PMID:26414426

  20. Tolerance of Venerupis philippinarum to salinity: osmotic and metabolic aspects.

    PubMed

    Carregosa, Vanessa; Figueira, Etelvina; Gil, Ana M; Pereira, Sara; Pinto, Joana; Soares, Amadeu M V M; Freitas, Rosa

    2014-05-01

    In the last few decades, attention has been focused on the impacts of contamination in marine benthic populations, while the responses of aquatic organisms to natural alterations, namely changes in salinity, have received little attention. In fact, salinity is one of the dominant environmental factors affecting marine bivalves. The ebb and flood of the tide, combined with fresh water inputs from rivers or heavy rainy events, and with extremely dry and hot seasons, can dramatically alter water salinity. Therefore, the salinity of a certain environment can restrict the spatial distribution of a given population, which is especially important when assessing the spread of an invasive species into a new environment. In the present study, the main objective was to understand how clam Venerupis philippinarum copes with salinity changes and, hence biochemical and metabolomic alterations, taking place in individuals submitted to a wide range of salinities were investigated. The results showed that V. philippinarum presented high mortality at lower salinities (0 and 7 g/L) but tolerated high salinities (35 and 42 g/L). The quantification of ionic content revealed that, clams had the capacity to maintain ionic homeostasis along the salinity gradient, mainly changing the concentration of Na, but also with the influence of Mg and Ca. The results showed a decrease in protein content at lower salinities (0 to 21 g/L). Glycogen and glucose increased with increasing salinity gradient. (1)H Nuclear Magnetic Resonance (NMR) spectra of clam aqueous extracts revealed different metabolite profiles at 7, 28 and 42 g/L salinities, thus enabling metabolite changes to be measured in relation to salinity. PMID:24556070

  1. Low-salinity-induced surface sound channel in the western sea of Jeju Island during summer.

    PubMed

    Kim, Juho; Kim, Hansoo; Paeng, Dong-Guk; Bok, Tae-Hoon; Lee, Jongkil

    2015-03-01

    Surface salinity in the western sea of Jeju Island in Korea becomes low due to the inflow of the Chinese coastal waters during summer. One of the characteristics of low salinity water is the formation of a surface sound channel (SSC) due to the decrease in sound speed by salinity. However, a quantitative analysis between low salinity water and SSC has not been fully investigated yet. In this paper, a temperature-salinity (T-S) gradient diagram is introduced in order to assess SSC formation and its acoustic characteristics are also investigated through a case study of low salinity waters. Maximum angles of limiting rays were less than 4.6° and low frequency cutoffs were higher than 2.0 kHz for the SSCs formed in low salinity water. When the salinity gradients were large (>0.5 psu/m), a SSC was formed more efficiently than other cases whose salinity gradients were small. On the other hand, a SSC was not formed in spite of highly positive salinity gradients when the amount of temperature gradients was negatively high enough (<-0.5 °C/m). However, the acoustic energy transfer in the surface ducts was dependent on frequency and position of source. PMID:25786968

  2. Very, Very Fast Wetting

    NASA Technical Reports Server (NTRS)

    Jacqmin, David; Lee, Chi-Ming (Technical Monitor); Salzman, Jack (Technical Monitor)

    2001-01-01

    Just after formation, optical fibers are wetted stably with acrylate at capillary numbers routinely exceeding 1000. It is hypothesized that this is possible because of dissolution of air into the liquid coating. A lubrication/boundary integral analysis that includes gas diffusion and solubility is developed. It is applied using conservatively estimated solubility and diffusivity coefficients and solutions are found that are consistent with industry practice and with the hypothesis. The results also agree with the claim of Deneka, Kar & Mensah (1988) that the use of high solubility gases to bathe a wetting line allows significantly greater wetting speeds. The solutions indicate a maximum speed of wetting which increases with gas solubility and with reduction in wetting-channel diameter.

  3. Kinetics of Reactive Wetting

    SciTech Connect

    YOST, FREDERICK G.

    1999-09-09

    The importance of interfacial processes in materials joining has a long history. A significant amount of work has suggested that processes collateral to wetting can affect the extent of wetting and moderate or retard wetting rate. Even very small additions of a constituent, known to react with the substrate, cause pronounced improvement in wetting and are exploited in braze alloys, especially those used for joining to ceramics. The wide diversity of processes, such as diffusion, chemical reaction, and fluxing, and their possible combinations suggest that various rate laws should be expected for wetting kinetics depending on the controlling processes. These rate laws are expected to differ crucially from the standard fluid controlled wetting models found in the literature. Voitovitch et al. and Mortensen et al. have shown data that suggests diffusion control for some systems and reaction control for others. They also presented a model of wetting kinetics controlled by the diffusion of a constituent contained by the wetting fluid. In the following a model will be constructed for the wetting kinetics of a small droplet of metal containing a constituent that diffuses to the wetting line and chemically reacts with a flat, smooth substrate. The model is similar to that of Voitovitch et al. and Mortensen et al. but incorporates chemical reaction kinetics such that the result contains both diffusion and reaction kinetics. The model is constructed in the circular cylinder coordinate system, satisfies the diffusion equation under conditions of slow flow, and considers diffusion and reaction at the wetting line to be processes in series. This is done by solving the diffusion equation with proper initial and boundary conditions, computing the diffusive flux at the wetting line and equating this to both the convective flux and reaction flux. This procedure is similar to equating the current flowing in components of a series circuit. The wetting rate will be computed versus time

  4. Elucidating the mysteries of wetting.

    SciTech Connect

    Webb, Edmund Blackburn, III; Bourdon, Christopher Jay; Grillet, Anne Mary; Sackinger, Philip A.; Grest, Gary Stephen; Emerson, John Allen; Ash, Benjamin Jesse; Heine, David R.; Brooks, Carlton, F.; Gorby, Allen D.

    2005-11-01

    Nearly every manufacturing and many technologies central to Sandia's business involve physical processes controlled by interfacial wetting. Interfacial forces, e.g. conjoining/disjoining pressure, electrostatics, and capillary condensation, are ubiquitous and can surpass and even dominate bulk inertial or viscous effects on a continuum level. Moreover, the statics and dynamics of three-phase contact lines exhibit a wide range of complex behavior, such as contact angle hysteresis due to surface roughness, surface reaction, or compositional heterogeneities. These thermodynamically and kinetically driven interactions are essential to the development of new materials and processes. A detailed understanding was developed for the factors controlling wettability in multicomponent systems from computational modeling tools, and experimental diagnostics for systems, and processes dominated by interfacial effects. Wettability probed by dynamic advancing and receding contact angle measurements, ellipsometry, and direct determination of the capillary and disjoining forces. Molecular scale experiments determined the relationships between the fundamental interactions between molecular species and with the substrate. Atomistic simulations studied the equilibrium concentration profiles near the solid and vapor interfaces and tested the basic assumptions used in the continuum approaches. These simulations provide guidance in developing constitutive equations, which more accurately take into account the effects of surface induced phase separation and concentration gradients near the three-phase contact line. The development of these accurate models for dynamic multicomponent wetting allows improvement in science based engineering of manufacturing processes previously developed through costly trial and error by varying material formulation and geometry modification.

  5. Salinity Measurements During the Gulf Stream Experiment

    NASA Technical Reports Server (NTRS)

    LeVine, D. M.; Koblinsky, C.; Howden, S.; Goodberlet, M.

    2000-01-01

    The salinity of the open ocean is important for understanding ocean circulation, for understanding energy exchange with the atmosphere and for improving models to predict weather and climate. Passive microwave sensors at L-band (1.4 GHz) operating from aircraft have demonstrated that salinity can be measured with sufficient accuracy (1 psu) to be scientifically meaningful in coastal waters. However, measuring salinity in the open ocean presents unresolved issues largely because of the much greater accuracy (approx. 0.1 psu) required to be scientifically viable. In the summer of 1999 a series of measurements called, The Gulf Stream Experiment, were conducted as part of research at the Goddard Space Flight Center to test the potential for passive microwave remote sensing of salinity in the open ocean. The measurements consisted of a compliment of airborne microwave instruments (radiometers and scatterometer) and ships and drifters for surface truth. The study area was a 200 km by 100 km rectangle about 250 km east of Delaware Bay between the continental shelf waters and north wall of the Gulf Stream. The primary passive instruments were the ESTAR radiometer (L-band, H-pol) and the SLFMR radiometer (L-band, V-pol). In addition, the compliment of instruments on the aircraft included a C-band radiometer (ACMR), an ocean wave scatterometer (ROWS) and an infrared radiometer. A GPS backscatter experiment was also part of the package. These instruments were mounted on the NASA P-3 Orion aircraft. Surface salinity measurements were provided by the RN Cape Henlopen and MN Oleander (thermosalinographs) plus salinity and temperature sensors on three surface drifters deployed from the RN Cape Henopen. The primary experiment period was August 26-September 2, 1999. During this period the salinity field within the study area consisted of a gradient on the order of 2-3 psu in the vicinity of the shelf break and a warm core ring with a gradient of 1-2 psu. Detailed maps were made

  6. Kinetics of reactive wetting

    SciTech Connect

    Yost, F.G.

    2000-04-14

    The importance of interfacial processes in materials joining has a long history. A significant amount of work has suggested that processes collateral to wetting can affect the extent of wetting and moderate or retard wetting rate. Even very small additions of a constituent, known to react with the substrate, cause pronounced improvement in wetting and are exploited in braze alloys, especially those used for joining to ceramics. In the following a model will be constructed for the wetting kinetics of a small droplet of metal containing a constituent that diffuses to the wetting line and chemically reacts with a flat, smooth substrate. The model is similar to that of Voitovitch et al. and Mortensen et al. but incorporates chemical reaction kinetics such that the result contains both diffusion and reaction kinetics. The model is constructed in the circular cylinder coordinate system, satisfies the diffusion equation under conditions of slow flow, and considers diffusion and reaction at the wetting line to be processes in series. This is done by solving the diffusion equation with proper initial and boundary conditions, computing the diffusive flux at the wetting line, and equating this to both the convective flux and reaction flux. This procedure is similar to equating the current flowing in components of a series circuit. The wetting rate will be computed versus time for a variety of diffusion and reaction conditions. A transition is observed from nonlinear (diffusive) to linear (reactive) behavior as the control parameters (such as the diffusion coefficient) are modified. This is in agreement with experimental observations. The adequacy of the slow flow condition, used in this type of analysis, is discussed and an amended procedure is suggested.

  7. Irradiance gradients

    SciTech Connect

    Ward, G.J. Ecole Polytechnique Federale, Lausanne ); Heckbert, P.S. . School of Computer Science Technische Hogeschool Delft . Dept. of Technical Mathematics and Informatics)

    1992-04-01

    A new method for improving the accuracy of a diffuse interreflection calculation is introduced in a ray tracing context. The information from a hemispherical sampling of the luminous environment is interpreted in a new way to predict the change in irradiance as a function of position and surface orientation. The additional computation involved is modest and the benefit is substantial. An improved interpolation of irradiance resulting from the gradient calculation produces smoother, more accurate renderings. This result is achieved through better utilization of ray samples rather than additional samples or alternate sampling strategies. Thus, the technique is applicable to a variety of global illumination algorithms that use hemicubes or Monte Carlo sampling techniques.

  8. WET SOLIDS FLOW ENHANCEMENT

    SciTech Connect

    Hugo S. Caram; Natalie Foster

    1999-07-01

    The strain-stress behavior of a wet granular media was measured using a split Parfitt tensile tester. In all cases the stress increases linearly with distance until the maximum uniaxial tensile stress is reached. The stress then decreases exponentially with distance after this maximum is reached. The linear region indicates that wet solids behave elastically for stresses below the tensile stresses and can store significant elastic energy. The elastic deformation cannot be explained by analyzing the behavior of individual capillary bridges and requires accounting for the deformation of the solids particles. The elastic modulus of the wet granular material remains unexplained.

  9. WET SOLIDS FLOW ENHANCEMENT

    SciTech Connect

    Hugo S. Caram; Natalie Foster

    1998-03-30

    The strain-stress behavior of a wet granular media was measured using a split Parfitt tensile tester. In all cases the stress increases linearly with distance until the maximum uniaxial tensile stress is reached. The stress then decreases exponentially with distance after this maximum is reached. The linear region indicates that wet solids behave elastically for stresses below the tensile stresses and can store significant elastic energy. The elastic deformation cannot be explained by analyzing the behavior of individual capillary bridges and may require accounting for the deformation of the solids particles. The elastic modulus of the wet granular material remains unexplained.

  10. Haptic perception of wetness.

    PubMed

    Bergmann Tiest, Wouter M; Kosters, N Dolfine; Kappers, Astrid M L; Daanen, Hein A M

    2012-10-01

    In daily life, people interact with textiles of different degrees of wetness, but little is known about the mechanics of wetness perception. This paper describes an experiment with six conditions regarding haptic discrimination of the wetness of fabrics. Three materials were used: cotton wool, sponge-structured viscose and thin viscose. Two ways of touching were investigated: static touching, in which only thermal cues were available, and dynamic touching, in which additional mechanical cues were available. For dynamic touching, average Weber fractions for discrimination were around 0.3, whereas for static touching, they ranged from 0.34 to 0.63. The results show that people can make use of the additional mechanical cues to significantly improve their discrimination performance. There was no significant difference between Weber fractions for the three materials, showing that wetness can be judged as a separate perceptual quantity, independent of the material. PMID:22964056

  11. Intraguild predation may reinforce a species-environment gradient

    NASA Astrophysics Data System (ADS)

    MacNeil, Calum; Dick, Jaimie T. A.

    2012-05-01

    Species-environment gradients are ubiquitous in nature, with studies often partially explaining the replacement of species along such gradients by autecological factors such as differential physiological tolerances. However, lacking direct evidence, the majority of studies only infer some form of inter-specific interaction, often competition, as reinforcing these gradients. There is usually the further implication that environmental factors mediate asymmetries in the interaction. Recognising the lack of explicit experimental considerations of how key inter-specific interactions are modified by the environment, we chose a study system where we were able to bring the species in question into the laboratory and conduct experiments to test hypotheses about gradient-induced asymmetries in an inter-specific interaction. To this end, we tested the hypothesis that a species-salinity gradient may be reinforced by changes in the asymmetry of intraguild predation between two species of amphipod crustaceans with wide salinity tolerances. River and estuary surveys showed that Gammarus duebeni and Gammarus zaddachi have overlapping distributions, with both surviving and reproducing in salinities ranging from freshwater to fully marine. However, the former species is relatively more abundant in low salinities and the latter in higher salinities. In the laboratory, survival of both species was high in all salinities and cannibalism occurred at low frequencies. However, intraguild predation by males on moulted females was asymmetric in favour of G. duebeni at low salinities, this asymmetry completely reversing to favour G. zaddachi at higher salinities. Thus, we provide evidence that this species-environment gradient occurs due to overlapping physiological tolerances and salinity-driven shifts in the asymmetry of a key inter-specific interaction, intraguild predation.

  12. Salinity Management in Agriculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Existing guidelines and standards for reclamation of saline soils and management to control salinity exist but have not been updated for over 25 years. In the past few years a looming water scarcity has resulted in questioning of the long term future of irrigation projects in arid and semi arid regi...

  13. Measuring soil salinity.

    PubMed

    Hardie, Marcus; Doyle, Richard

    2012-01-01

    Soil salinity is a form of land degradation in which salts accumulate in the soil profile to an extent that plant growth or infrastructure are negatively affected. A range of both field and laboratory procedures exist for measuring soil salinity. In the field, soil salinity is usually inferred from apparent electrical conductivity (EC(a)) using a range of devices, depending on the required depth of analysis, or size of the survey area. Field measurements of EC(a) require calibration to the actual salt content by laboratory analysis. In the laboratory, soil salinity is usually assessed by determining either the total soluble salts by evaporation of a soil water extract (TSS), or by determining the electrical conductivity (EC) of either a 1:5 distilled water:soil dilution, or a saturated paste extract. Although procedures for measuring soil salinity appear relatively straightforward, differences in methodology have considerable influence on measured values and interpretation of results. PMID:22895776

  14. Remote sensing of salinity

    NASA Technical Reports Server (NTRS)

    Thomann, G. C.

    1975-01-01

    The complex dielectric constant of sea water is a function of salinity at 21 cm wavelength, and sea water salinity can be determined by a measurement of emissivity at 21 cm along with a measurement of thermodynamic temperature. Three aircraft and one helicopter experiments using two different 21 cm radiometers were conducted under different salinity and temperature conditions. Single or multiple ground truth measurements were used to calibrate the data in each experiment. It is inferred from these experiments that accuracies of 1 to 2%/OO are possible with a single surface calibration point necessary only every two hours if the following conditions are met--water temperatures above 20 C, salinities above 10%/OO, and level plane flight. More frequent calibration, constraint of the aircraft's orientation to the same as it was during calibration, and two point calibration (at a high and low salinity level) rather than single point calibration may give even better accuracies in some instances.

  15. Saline infusion sonohysterography.

    PubMed

    2004-01-01

    Saline infusion sonohysterography consists of ultrasonographic imaging of the uterus and uterocervical cavity, using real-time ultrasonography during injection of sterile saline into the uterus. When properly performed, saline infusion sonohysterography can provide information about the uterus and endometrium. The most common indication for sonohysterography is abnormal uterine bleeding. sonohysterography should not be performed in a woman who is pregnant or could be pregnant or in a woman with a pelvic infection or unexplained pelvic tenderness. Physicians who perform or supervise diagnostic saline infusion sonohysterograpy should have training, experience, and demonstrated competence in gynecologic ultrasonography and saline infusion sonohysterography. Portions of this document were developed jointly with the American College of Radiology and the American Institute of Ultrasound in Medicine. PMID:14968760

  16. Wetting transitions in two-, three-, and four-phase systems.

    PubMed

    Hejazi, Vahid; Nosonovsky, Michael

    2012-01-31

    We discuss wetting of rough surfaces with two-phase (solid-liquid), three-phase (solid-water-air and solid-oil-water), and four-phase (solid-oil-water-air) interfaces mimicking fish scales. We extend the traditional Wenzel and Cassie-Baxter models to these cases. We further present experimental observations of two-, three-, and four-phase systems in the case of metal-matrix composite solid surfaces immersed in water and in contact with oil. Experimental observations show that wetting transitions can occur in underwater oleophobic systems. We also discuss wetting transitions as phase transitions using the phase-field approach and show that a phenomenological gradient coefficient is responsible for wetting transition, energy barriers, and wetting/dewetting asymmetry (hysteresis). PMID:22054126

  17. Estimation of coastal density gradients

    NASA Astrophysics Data System (ADS)

    Howarth, M. J.; Palmer, M. R.; Polton, J. A.; O'Neill, C. K.

    2012-04-01

    Density gradients in coastal regions with significant freshwater input are large and variable and are a major control of nearshore circulation. However their measurement is difficult, especially where the gradients are largest close to the coast, with significant uncertainties because of a variety of factors - spatial and time scales are small, tidal currents are strong and water depths shallow. Whilst temperature measurements are relatively straightforward, measurements of salinity (the dominant control of spatial variability) can be less reliable in turbid coastal waters. Liverpool Bay has strong tidal mixing and receives fresh water principally from the Dee, Mersey, Ribble and Conwy estuaries, each with different catchment influences. Horizontal and vertical density gradients are variable both in space and time. The water column stratifies intermittently. A Coastal Observatory has been operational since 2002 with regular (quasi monthly) CTD surveys on a 9 km grid, an situ station, an instrumented ferry travelling between Birkenhead and Dublin and a shore-based HF radar system measuring surface currents and waves. These measurements are complementary, each having different space-time characteristics. For coastal gradients the ferry is particularly useful since measurements are made right from the mouth of Mersey. From measurements at the in situ site alone density gradients can only be estimated from the tidal excursion. A suite of coupled physical, wave and ecological models are run in association with these measurements. The models, here on a 1.8 km grid, enable detailed estimation of nearshore density gradients, provided appropriate river run-off data are available. Examples are presented of the density gradients estimated from the different measurements and models, together with accuracies and uncertainties, showing that systematic time series measurements within a few kilometres of the coast are a high priority. (Here gliders are an exciting prospect for

  18. Rain Impact Model V2.0 for Sea Surface Salinity: A Flag for Salinity Stratification

    NASA Astrophysics Data System (ADS)

    Santos-Garcia, A.

    2015-12-01

    The Central Florida Remote Sensing Laboratory has analyzed Aquarius (AQ) sea surface salinity (SSS) and ESA's Soil Moisture Ocean Salinity (SMOS) retrievals in the presence of rain and has developed a Rain Impact Model (RIM V2.0) that predicts transient near-surface salinity stratification based upon the corresponding rain accumulation over the previous 24 hours and the effect of the wind speed. For both of the satellite SSS measurements, a common reference for comparison is the Hybrid Coordinate Ocean Model (HYCOM) for ocean salinity, but there is a significant mismatch between the remote sensing sampling depth of approximately 0.01 m and the typical range of 5 m to 10 m of in situ instruments. Under normal ocean conditions the upper layer of the ocean is well mixed and there is an approximately uniform salinity for the first 10 m depth; therefore satellite measurements are good estimates of the bulk salinity. Conversely, under rainy conditions, there is a dilution of the near-surface salinity that mixed downward by diffusion and mechanical mixing of gravity waves, where the wind speed information play a significant role in the model. This transient phenomena, known as salinity stratification, significantly modifies the salinity gradient in the upper 1 m of the ocean; and therefore invalidates the usual assumption of well-mixed salinity. Generally, these salinity stratifications dissipate in less than a couple of hours and the upper layer becomes well mixed at a slightly fresher salinity. The Rain Impact Model V2.0 is based on the RIM V1.0, previously published, which includes the rain accumulation effect but ignores the variations on wind speed using a constant vertical diffusivity value. This research addresses the effects of rainfall on the AQ and SMOS SSS retrieval using a macro-scale Rain Impact Model (RIM) in regions of high convective rain. This model, based on the superposition of a one-dimension eddy diffusion (turbulent diffusion) model, relates sea

  19. Electroretinographic wet electrode.

    PubMed

    Carpi, Federico; Benini, Gabriella; Tomei, Franca; Figliuzzi, Rosa Maria; De Napoli, Alberto

    2009-10-01

    This paper presents the first systematic characterisation of a new electroretinographic (ERG) electrode, recently described. The new 'wet' electrode uses a conducting liquid as a distributed electrical interface between the eye and a solid electronic conductor; the latter detects the ERG potential without any direct contact with the ocular surface. This technique avoids the contact-induced discomfort of both corneal and conjunctival standard electrodes. The wet electrode was tested on 10 volunteers, in comparison with a conjunctival electrode (HK loop), as the most comfortable standard. It was also compared with a cutaneous (cup) electrode, which is even more comfortable, although not standard. Results showed the efficacy of the wet electrode for detecting morphologically accurate ERG responses, with amplitudes respectively analogous and higher of those measured by the conjunctival and cutaneous electrodes. Properties of wet electrodes include: no solid interface with the eye, no need for anaesthesia, intrinsic safety, mechanical and electrical stability against ocular movements, tolerance to misplacements and immunity to lacrimation. As a drawback, the liquid can still be a source of discomfort for some patients and it requires care against possible leakage. All these features suggest a possible use of wet electrodes as an additional tool for ERG procedures, although limited to tests of short duration. PMID:19501539

  20. Wet storage integrity update

    SciTech Connect

    Bailey, W.J.; Johnson, A.B. Jr.

    1983-09-01

    This report includes information from various studies performed under the Wet Storage Task of the Spent Fuel Integrity Project of the Commercial Spent Fuel Management (CSFM) Program at Pacific Northwest Laboratory. An overview of recent developments in the technology of wet storage of spent water reactor fuel is presented. Licensee Event Reports pertaining to spent fuel pools and the associated performance of spent fuel and storage components during wet storage are discussed. The current status of fuel that was examined under the CSFM Program is described. Assessments of the effect of boric acid in spent fuel pool water on the corrosion and stress corrosion cracking of stainless steel and the stress corrosion cracking of stainless steel piping containing stagnant water at spent fuel pools are discussed. A list of pertinent publications is included. 84 references, 21 figures, 11 tables.

  1. Doubled power density from salinity gradients at reduced intermembrane distance.

    PubMed

    Vermaas, David A; Saakes, Michel; Nijmeijer, Kitty

    2011-08-15

    The mixing of sea and river water can be used as a renewable energy source. The Gibbs free energy that is released when salt and fresh water mix can be captured in a process called reverse electrodialysis (RED). This research investigates the effect of the intermembrane distance and the feedwater flow rate in RED as a route to double the power density output. Intermembrane distances of 60, 100, 200, and 485 μm were experimentally investigated, using spacers to impose the intermembrane distance. The generated (gross) power densities (i.e., generated power per membrane area) are larger for smaller intermembrane distances. A maximum value of 2.2 W/m(2) is achieved, which is almost double the maximum power density reported in previous work. In addition, the energy efficiency is significantly higher for smaller intermembrane distances. New improvements need to focus on reducing the pressure drop required to pump the feedwater through the RED-device using a spacerless design. In that case power outputs of more than 4 W per m(2) of membrane area at small intermembrane distances are envisaged. PMID:21736348

  2. Electrical power generation from salinity gradients using pressure retarded osmosis

    SciTech Connect

    Emery, A.F.; Yourstone, W.H.

    1983-08-01

    The use of a pressure retarded osmosis system (PRO) to generate electricity form naturally available or artificially generated salt is described. Variations in overall system efficiency are analyzed in terms of freshwater and brine flow rates, fluid pressure levels, and membrane permeability. It is shown that the PRO system is economically competitive with other alternative energy systems.

  3. Electrical power generation from salinity gradients using pressure retarded osmosis

    NASA Astrophysics Data System (ADS)

    Emery, A. F.; Yourstone, W. H., Jr.

    The use of a pressure retarded osmosis system (PRO) to generate electricity from naturally available or artificially generated salt is described. Variations in overall system efficiency are analyzed in terms of freshwater and brine flow rates, fluid pressure levels, and membrane permeability. It is shown that the PRO system is economically competitive with other alternative energy systems.

  4. Water table salinization due to seawater intrusion

    NASA Astrophysics Data System (ADS)

    Badaruddin, Sugiarto; Werner, Adrian D.; Morgan, Leanne K.

    2015-10-01

    Seawater intrusion (SWI) is a significant threat to freshwater resources in coastal aquifers around the world. Previous studies have focused on SWI impacts involving salinization of the lower domain of coastal aquifers. However, under certain conditions, SWI may cause salinization of the entire saturated zone of the aquifer, leading to water table salinization (WTS) in unconfined aquifers by replacing freshwater within the upper region of the saturated zone with seawater, thereby posing a salinity threat to the overlying soil zone. There is presently limited guidance on the extent to which WTS may occur as a secondary impact of SWI. In this study, physical experiments and numerical modeling were used to explore WTS associated with SWI in various nontidal, unconfined coastal aquifer settings. Laboratory experiments and corresponding numerical simulations show that significant WTS can occur under active SWI (i.e., the freshwater hydraulic gradient slopes toward the land) because the cessation of freshwater discharge to the sea and the subsequent landward flow across the entire sea boundary eventually lead to water table salinities approaching seawater concentration. WTS during active SWI is larger under conditions of high hydraulic conductivity, rapid SWI, high dispersivity and for deeper aquifers. Numerical modeling of four published field cases demonstrates that rates of WTS of up to 60 m/yr are plausible. Under passive SWI (i.e., the hydraulic gradient slopes toward the sea), minor WTS may arise as a result of dispersive processes under certain conditions (i.e., high dispersivity and hydraulic conductivity, and low freshwater discharge). Our results show that WTS is probably widespread in coastal aquifers experiencing considerable groundwater decline sustained over several years, although further evidence is needed to identify WTS under field settings.

  5. SMOS salinity in the subtropical north Atlantic salinity maximum: Observation of the surface thermohaline horizontal structure and of its seasonal variability

    NASA Astrophysics Data System (ADS)

    Kolodziejczyk, Nicolas; Hernandez, Olga; Boutin, Jacqueline; Reverdin, Gilles

    2014-05-01

    The seasonal variability of the surface horizontal thermohaline structure is investigated in the subtropical and tropical north Atlantic Surface Salinity Maximum (SSM) at length scales from 5-10 km to more than 500 km. The near surface temperature and salinity data from merchant ship thermosalinograph (TSG) transects across the Atlantic, from ISAS product interpolated from Argo profiles, and a combination of SST from Tropical Microwave Imager (TMI) and SSS from the recently launched Soil Moisture and Ocean Salinity (SMOS) satellite, were used as complementary tools to compute the horizontal temperature, salinity and density gradients and the density ratio in the northern subtropical-tropical Atlantic. During late winter, in north-eastern SSM, the thermohaline compensation is observed for wavelengths from 5-10 km to more than 500 km. In spite of large and sharp surface thermohaline fronts a very weak density surface horizontal gradient is observed. In contrast, in the southern SSM, at large scale (>200 km) the density ratio is controlled by the salinity gradient and the horizontal density gradient is sharpened by a constructive contribution of opposite salinity and temperature gradients. During summer, the density ratio is dominated everywhere by the salinity gradient which enhances the horizontal surface density gradient in particular the south-western SSM, in the Amazon-Orinoco run off region. The first attempt in using SMOS SSS and TMI SST in order to retrieve the surface density ratio and horizontal density gradient is promising. We suggest that the surface density ratio and horizontal density gradient result from the straining and mixing of surface thermohaline properties that may play important roles in the deepening and re-stratification of the oceanic mixed layer.

  6. Ion uptake of marigold under saline growth conditions.

    PubMed

    Koksal, Nezihe; Alkan-Torun, Ayfer; Kulahlioglu, Ilknur; Ertargin, Ebru; Karalar, Eylul

    2016-01-01

    Salinity is one of most significant environmental stresses. Marigold is moderately tolerant to salinity stress. Therefore, in this study, the fresh weights of roots and shoots, rootFW/shootFW ratio, moisture content of shoots, micronutrient and macronutrient concentrations and ratios of K(+)/Na(+) and Ca(2+)/Na(+) in the roots and shoots of marigold were determined under salinity stress. Five salinity treatments (0, 50, 100, 150, and 200 mM NaCl) were maintained. In the current study, salinity affected the biomass of marigold. An increase of more than 100 mM in salt concentrations significantly reduced the shoot fresh weight. Increasing salinity stress increased the ratios of rootFW/shootFW, which were more significant under high salt levels (150 and 200 mM NaCl). Wet basis moisture contents of the shoots were reduced when salinity stress increased above 100 mM. In this study, salinity stress affected micronutrient and macronutrient uptake. Increases in the salt concentration and decreases in the concentration of Cu(2+) and Zn(2+) in the roots and Mn(2+) and Fe(2+) in the shoots were significant. Based on an increase in salinity stress, while the Ca(2+), Mg(2+), and Na(+) concentrations increased, the K(+) concentration decreased in the roots and shoots. Moreover, the K(+)/Na(+) and Ca(2+)/Na(+) ratios of the roots and shoots were significantly lower than those of the control in all of the salinity treatments. As a result, under increasing salinity stress, the Ca(2+), Mg(2+), K(+), and Na(+) uptakes in marigold were significant, revealing the effects of stress. PMID:26933637

  7. Sea Surface Salinity

    NASA Video Gallery

    The heat of the sun also forces evaporation at the ocean's surface, which puts water vapor into the atmosphere but leaves minerals and salts behind, keeping the ocean salty. The salinity of the oce...

  8. WET SOLIDS FLOW ENHANCEMENT

    SciTech Connect

    Hugo S. Caram; Natalie Foster

    1999-03-30

    The elastic modulus E of wet granular material was found to be of the order of 0.25 MPa, this value does not compare well with the value predicted for a cubic array of spheres under Hertzian contact were the predicted values were in the order of 250 MPa . The strain-stress behavior of a wet granular media was measured using a split Parfitt tensile tester. In all cases the stress increases linearly with distance until the maximum uniaxial tensile stress is reached. The stress then decreases exponentially with distance after this maximum is reached. The linear region indicates that wet solids behave elastically for stresses below the tensile stresses and can store significant elastic energy. The elastic deformation cannot be explained by analyzing the behavior of individual capillary bridges and requires accounting for the deformation of the solids particles. The elastic modulus of the wet granular material remains unexplained. New information was found to support the experimental finding and a first theory to explain the very small elastic modulus is presented. A new model based on the used of the finite element method is being developed.

  9. Wetting mechanisms of gel-based controlled-release fertilizers.

    PubMed

    Shavit, U; Reiss, M; Shaviv, A

    2003-02-14

    The release mechanism of gel-based controlled release fertilizers (CRFs) involves water penetration into dry mixtures of fertilizers and gel forming polymers. Water penetration provides an upper limit to the whole release process. Where wetting prediction is often based on models that describe the flow of the liquid phase, vapor motion may become significant when a sharp wetting front exists. In this study we examine the role of vapor and fluid flows in the wetting process of CRFs consisting of urea or KNO(3) mixed with polyacrylamide (PAM). Vapor adsorption isotherms were obtained for typical fertilizer-PAM mixtures. Wetting and release experiments were conducted by dividing the CRFs into regions alternately filled with a pure fertilizer and mixtures of PAM and fertilizer. The experiments were designed in such a way that when the wetting front reaches a mixtures interface, its motion depends on the gradient imposed by the difference in osmotic potential (OP). The coupled equations of vapor and liquid flow in initially dry conditions were solved numerically to demonstrate the conceptual understanding gained by the experiments. The results show that wetting front motion is affected by transport and adsorption of vapor. It was also shown that the release rate is different when wetting is governed by vapor flow or by liquid flow. The release pattern from a multi-regions device was consistent with the wetting pattern, demonstrating the possibility to tailor the release according to periods of peak demand. PMID:12586505

  10. PREFACE: Wetting: introductory note

    NASA Astrophysics Data System (ADS)

    Herminghaus, S.

    2005-03-01

    The discovery of wetting as a topic of physical science dates back two hundred years, to one of the many achievements of the eminent British scholar Thomas Young. He suggested a simple equation relating the contact angle between a liquid surface and a solid substrate to the interfacial tensions involved [1], γlg cos θ = γsg - γsl (1) In modern terms, γ denotes the excess free energy per unit area of the interface indicated by its indices, with l, g and s corresponding to the liquid, gas and solid, respectively [2]. After that, wetting seems to have been largely ignored by physicists for a long time. The discovery by Gabriel Lippmann that θ may be tuned over a wide range by electrochemical means [3], and some important papers about modifications of equation~(1) due to substrate inhomogeneities [4,5] are among the rare exceptions. This changed completely during the seventies, when condensed matter physics had become enthusiastic about critical phenomena, and was vividly inspired by the development of the renormalization group by Kenneth Wilson [6]. This had solved the long standing problem of how to treat fluctuations, and to understand the universal values of bulk critical exponents. By inspection of the critical exponents of the quantities involved in equation~(1), John W Cahn discovered what he called critical point wetting: for any liquid, there should be a well-defined transition to complete wetting (i.e., θ = 0) as the critical point of the liquid is approached along the coexistence curve [7]. His paper inspired an enormous amount of further work, and may be legitimately viewed as the entrance of wetting into the realm of modern physics. Most of the publications directly following Cahn's work were theoretical papers which elaborated on wetting in relation to critical phenomena. A vast amount of interesting, and in part quite unexpected, ramifications were discovered, such as the breakdown of universality in thin film systems [8]. Simultaneously, a number

  11. On gradient field theories: gradient magnetostatics and gradient elasticity

    NASA Astrophysics Data System (ADS)

    Lazar, Markus

    2014-09-01

    In this work, the fundamentals of gradient field theories are presented and reviewed. In particular, the theories of gradient magnetostatics and gradient elasticity are investigated and compared. For gradient magnetostatics, non-singular expressions for the magnetic vector gauge potential, the Biot-Savart law, the Lorentz force and the mutual interaction energy of two electric current loops are derived and discussed. For gradient elasticity, non-singular forms of all dislocation key formulas (Burgers equation, Mura equation, Peach-Koehler stress equation, Peach-Koehler force equation, and mutual interaction energy of two dislocation loops) are presented. In addition, similarities between an electric current loop and a dislocation loop are pointed out. The obtained fields for both gradient theories are non-singular due to a straightforward and self-consistent regularization.

  12. WET SOLIDS FLOW ENHANCEMENT

    SciTech Connect

    Unknown

    2001-03-25

    The yield locus, tensile strength and fracture mechanisms of wet granular materials were studied. The yield locus of a wet material was shifted to the left of that of the dry specimen by a constant value equal to the compressive isostatic stress due to pendular bridges. for materials with straight yield loci, the shift was computed from the uniaxial tensile strength, either measured in a tensile strength tester or calculated from the correlation, and the angle of internal friction of the material. The predicted shift in the yield loci due to different moisture contents compare well with the measured shift in the yield loci of glass beads, crushed limestone, super D catalyst and Leslie coal. Measurement of the void fraction during the shear testing was critical to obtain the correct tensile strength theoretically or experimentally.

  13. Wet chemistry instrument prototype

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A wet chemistry instrument prototype for detecting amino acids in planetary soil samples was developed. The importance of amino acids and their condensation products to the development of life forms is explained. The characteristics of the instrument and the tests which were conducted to determine the materials compatibility are described. Diagrams are provided to show the construction of the instrument. Data obtained from the performance tests are reported.

  14. Laser/Heterodyne Measurement of Temperature and Salinity

    NASA Technical Reports Server (NTRS)

    Jobson, D. J.; Fales, C. L.; Katzberg, S. J.

    1982-01-01

    Proposed visible-light laser/heterodyne receiver would remotely measure temperature and salinity of subsurface water. Operation is based on acoustic/optical scattering of light by sound waves. Application of this concept is foreseen in current research on energy conversion from ocean currents produced by thermal gradients and on future marine remote-sensing program.

  15. The quantitative influence of salinity on the apparent resistivity on a physical model upon salination

    SciTech Connect

    Khair, K.; Skokan, C.

    1996-11-01

    The excessive exploitation of groundwater aquifers leads to water table drawdown, and subsequently to the contamination of these aquifers by the intrusion of sea water or other hazardous sources. This worldwide environmental problem is becoming increasingly critical in coastal agricultural areas, where the fine grained materials develop a thick fringe zone. By evapo-transpiration the moisture of this zone pumps up the salt in the dry season, which cannot be efficiently washed away in the wet season. The current study investigates the possibility of an early detection of salination, through systematic observation of electrical resistivity in selected positions with fixed electrode arrays. A direct current electrical profiling system of Wenner configuration was tested in the laboratory using a physical model. The model was constructed of wood and plastic tilled with saturated sand and having a constant water flow of 1.6 l/mn. The model size is 148 by 85 cm for lateral dimensions and 25 cm of sand thickness, with a total porosity of 360%. Upon salination the salt was increasingly added to the system to reach a concentration of 32 g/l. Upon desalination salt water was replaced by fresh water to dilute the water in the system to a concentration of 0.25 g/l. The results show that the relationship between salinity and electrical resistivity is inversely proportional and characterized by linear logarithmic function; the velocity of water flow calculated by abrupt resistivity changes is lower than the hydraulic velocity; the resistivity values for low salinity upon desalination are much different (smaller) than those upon salination of equivalent salt concentrations: the relative change of resistivity upon salination and desalination involves almost equally all features of the tank that have distinctive resistivity values.

  16. Wet and dry bacterial spore densities determined by buoyant sedimentation.

    PubMed Central

    Tisa, L S; Koshikawa, T; Gerhardt, P

    1982-01-01

    The wet densities of various types of dormant bacterial spores and reference particles were determined by centrifugal buoyant sedimentation in density gradient solutions of three commercial media of high chemical density. With Metrizamide or Renografin, the wet density values for the spores and permeable Sephadex beads were higher than those obtained by a reference direct mass method, and some spore populations were separated into several density bands. With Percoll, all of the wet density values were about the same as those obtained by the direct mass method, and only single density bands resulted. The differences were due to the partial permeation of Metrizamide and Renografin, but not Percoll, into the spores and the permeable Sephadex beads. Consequently, the wet density of the entire spore was accurately represented only by the values obtained with the Percoll gradient and the direct mass method. The dry densities of the spores and particles were determined by gravity buoyant sedimentation in a gradient of two organic solvents, one of high and the other of low chemical density. All of the dry density values obtained by this method were about the same as those obtained by the direct mass method. PMID:6285824

  17. Phoenix's Wet Chemistry Lab

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This is an illustration of the analytical procedure of NASA's Phoenix Mars Lander's Wet Chemistry Lab (WCL) on board the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument. By dissolving small amounts of soil in water, WCL can determine the pH, the abundance of minerals such as magnesium and sodium cations or chloride, bromide and sulfate anions, as well as the conductivity and redox potential.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  18. Phoenix's Wet Chemistry Lab

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This is an illustration of soil analysis on NASA's Phoenix Mars Lander's Wet Chemistry Lab (WCL) on board the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument. By dissolving small amounts of soil in water, WCL will attempt to determine the pH, the abundance of minerals such as magnesium and sodium cations or chloride, bromide and sulfate anions, as well as the conductivity and redox potential.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  19. Optical wet steam monitor

    DOEpatents

    Maxey, L.C.; Simpson, M.L.

    1995-01-17

    A wet steam monitor determines steam particle size by using laser doppler velocimeter (LDV) device to produce backscatter light. The backscatter light signal is processed with a spectrum analyzer to produce a visibility waveform in the frequency domain. The visibility waveform includes a primary peak and a plurality of sidebands. The bandwidth of at least the primary frequency peak is correlated to particle size by either visually comparing the bandwidth to those of known particle sizes, or by digitizing the waveform and comparing the waveforms electronically. 4 figures.

  20. Optical wet steam monitor

    DOEpatents

    Maxey, Lonnie C.; Simpson, Marc L.

    1995-01-01

    A wet steam monitor determines steam particle size by using laser doppler velocimeter (LDV) device to produce backscatter light. The backscatter light signal is processed with a spectrum analyzer to produce a visibility waveform in the frequency domain. The visibility waveform includes a primary peak and a plurality of sidebands. The bandwidth of at least the primary frequency peak is correlated to particle size by either visually comparing the bandwidth to those of known particle sizes, or by digitizing the waveform and comparing the waveforms electronically.

  1. WET SOLIDS FLOW ENHANCEMENT

    SciTech Connect

    Hugo S. Caram; Natalie Foster

    1997-03-31

    The objective was to visualize the flow of granular materials in flat bottomed silo. This was done by for dry materials introducing mustard seeds and poppy seeds as tracer particles and imaging them using Nuclear Magnetic Resonance. The region sampled was a cylinder 25 mm in diameter and 40 mm in length. Eight slices containing 128*128 to 256*256 pixels were generated for each image. The size of the silo was limited by the size of the high resolution NMR imager available. Cross-sections of 150mm flat bottomed silos, with the tracer layers immobilized by a gel, showed similar qualitative patterns for both dry and wet granular solids.

  2. Wet-dog shake

    NASA Astrophysics Data System (ADS)

    Dickerson, Andrew; Mills, Zack; Hu, David

    2010-11-01

    The drying of wet fur is a critical to mammalian heat regulation. We investigate experimentally the ability of hirsute animals to rapidly oscillate their bodies to shed water droplets, nature's analogy to the spin cycle of a washing machine. High-speed videography and fur-particle tracking is employed to determine the angular position of the animal's shoulder skin as a function of time. We determine conditions for drop ejection by considering the balance of surface tension and centripetal forces on drops adhering to the animal. Particular attention is paid to rationalizing the relationship between animal size and oscillation frequency required to self-dry.

  3. Wet granular materials

    NASA Astrophysics Data System (ADS)

    Mitarai, Namiko; Nori, Franco

    2006-04-01

    Most studies on granular physics have focused on dry granular media, with no liquids between the grains. However, in geology and many real world applications (e.g. food processing, pharmaceuticals, ceramics, civil engineering, construction, and many industrial applications), liquid is present between the grains. This produces inter-grain cohesion and drastically modifies the mechanical properties of the granular media (e.g. the surface angle can be larger than 90 degrees). Here we present a review of the mechanical properties of wet granular media, with particular emphasis on the effect of cohesion. We also list several open problems that might motivate future studies in this exciting but mostly unexplored field.

  4. Tracking evolution of urban biogeochemical cycles: salinization of fresh water

    NASA Astrophysics Data System (ADS)

    Kaushal, S.; McDowell, W. H.; Wollheim, W. M.; Duan, S.; Gorman, J. K.; Haq, S.; Hohman, S.; Smith, R. M.; Mayer, P. M.

    2014-12-01

    The built environment often changes quickly in response to human activities, thus contributing to an evolution of stream chemistry over time. Depending upon development and management strategies, these changes can result in pulses and/or long-term trends. Here, we explore patterns of evolving salinization of fresh water over time, and we evaluate the potential water quality implications of fresh water salinization. We show that there has been global salinization of freshwater across urbanizing landscapes over a century. We also show that human-accelerated weathering in watersheds and river alkalinization can further influence regional rates of salinization (in addition to anthropogenic sources such as road salts, sewage leaks, etc.). Finally, we investigate how salinization of fresh water can impact stream sediment fluxes of carbon, nutrients, and sulfate in watersheds across a land use gradient at the Baltimore Long-Term Ecological Research (LTER) site. The impacts of salinization on mobilization and uptake of carbon, nutrients, and sulfate in streams warrant further consideration in water quality management strategies. Overall, we propose that salinization can be a "universal tracer" of watershed urbanization globally with major regional consequences for drinking water and evolution of biogeochemical cycles in freshwater ecosystems.

  5. Saline Systems highlights for 2006

    PubMed Central

    DasSarma, Shiladitya

    2007-01-01

    Saline Systems is a journal devoted to both basic and applied studies of saline and hypersaline environments and their biodiversity. Here, I review the reports and commentaries published in the journal in 2006, including some exploring the geochemistry of saline estuaries, lakes, and ponds, others on the ecology and molecular biology of the indigenous halophilic organisms, and still others addressing the environmental challenges facing saline environments. Several studies are relevant to applications in biotechnology and aquaculture. PMID:17244355

  6. PREFACE: Wetting: introductory note

    NASA Astrophysics Data System (ADS)

    Herminghaus, S.

    2005-03-01

    The discovery of wetting as a topic of physical science dates back two hundred years, to one of the many achievements of the eminent British scholar Thomas Young. He suggested a simple equation relating the contact angle between a liquid surface and a solid substrate to the interfacial tensions involved [1], γlg cos θ = γsg - γsl (1) In modern terms, γ denotes the excess free energy per unit area of the interface indicated by its indices, with l, g and s corresponding to the liquid, gas and solid, respectively [2]. After that, wetting seems to have been largely ignored by physicists for a long time. The discovery by Gabriel Lippmann that θ may be tuned over a wide range by electrochemical means [3], and some important papers about modifications of equation~(1) due to substrate inhomogeneities [4,5] are among the rare exceptions. This changed completely during the seventies, when condensed matter physics had become enthusiastic about critical phenomena, and was vividly inspired by the development of the renormalization group by Kenneth Wilson [6]. This had solved the long standing problem of how to treat fluctuations, and to understand the universal values of bulk critical exponents. By inspection of the critical exponents of the quantities involved in equation~(1), John W Cahn discovered what he called critical point wetting: for any liquid, there should be a well-defined transition to complete wetting (i.e., θ = 0) as the critical point of the liquid is approached along the coexistence curve [7]. His paper inspired an enormous amount of further work, and may be legitimately viewed as the entrance of wetting into the realm of modern physics. Most of the publications directly following Cahn's work were theoretical papers which elaborated on wetting in relation to critical phenomena. A vast amount of interesting, and in part quite unexpected, ramifications were discovered, such as the breakdown of universality in thin film systems [8]. Simultaneously, a number

  7. Irrigation and Soil Salinization in Mediterranean agro-ecosystem

    NASA Astrophysics Data System (ADS)

    Ortega, Angelo; Viola, Francesco; Valerio Noto, Leonardo; Mau, Yair; Porporato, Amilcare

    2015-04-01

    During the warm and dry growing season of Mediterranean climates, the availability of good quality water for primary production in agriculture tends to be limited. This aspect makes the use of saline and brackish water appealing, given the potential of natural flushing of the soils by deep percolation during the wet and colder dormant season. Thus the cyclic alternation between the two different phases in the cold and warm season gives rise to a delicate equilibrium that can lead to long term secondary salinization if the mean salt input from irrigation overpasses the average annual natural leakage amount. The main goal of this study is to evaluate the long term salt mass balance in the presence of irrigation and possible changes in seasonality. An elevated concentration of salt in the soil may in turn lead to both a decrease of its fertility and to osmotic stress reducing plant productivity. To this purpose, a stochastic soil and water balance salinity model is developed to quantify the balance between salt accumulation phases during the growing season and leaching phases during the wet season. We provide the numerical and the analytical representation of secondary long-term salinization process, highlighting the role of soil depth, plant and climate together with the impact of shifts in the seasonal vs. interannual rainfall fluctuations. An application to a test case in the Southern part of Sicily (ITALY) is also presented, highlighting the strong relationship between salt dynamics, water management and climatic conditions.

  8. Functional Tradeoffs Underpin Salinity-Driven Divergence in Microbial Community Composition

    PubMed Central

    Yooseph, Shibu; Ininbergs, Karolina; Goll, Johannes; Asplund-Samuelsson, Johannes; McCrow, John P.; Celepli, Narin; Allen, Lisa Zeigler; Ekman, Martin; Lucas, Andrew J.; Hagström, Åke; Thiagarajan, Mathangi; Brindefalk, Björn; Richter, Alexander R.; Andersson, Anders F.; Tenney, Aaron; Lundin, Daniel; Tovchigrechko, Andrey; Nylander, Johan A. A.; Brami, Daniel; Badger, Jonathan H.; Allen, Andrew E.; Rusch, Douglas B.; Hoffman, Jeff; Norrby, Erling; Friedman, Robert; Pinhassi, Jarone; Venter, J. Craig; Bergman, Birgitta

    2014-01-01

    Bacterial community composition and functional potential change subtly across gradients in the surface ocean. In contrast, while there are significant phylogenetic divergences between communities from freshwater and marine habitats, the underlying mechanisms to this phylogenetic structuring yet remain unknown. We hypothesized that the functional potential of natural bacterial communities is linked to this striking divide between microbiomes. To test this hypothesis, metagenomic sequencing of microbial communities along a 1,800 km transect in the Baltic Sea area, encompassing a continuous natural salinity gradient from limnic to fully marine conditions, was explored. Multivariate statistical analyses showed that salinity is the main determinant of dramatic changes in microbial community composition, but also of large scale changes in core metabolic functions of bacteria. Strikingly, genetically and metabolically different pathways for key metabolic processes, such as respiration, biosynthesis of quinones and isoprenoids, glycolysis and osmolyte transport, were differentially abundant at high and low salinities. These shifts in functional capacities were observed at multiple taxonomic levels and within dominant bacterial phyla, while bacteria, such as SAR11, were able to adapt to the entire salinity gradient. We propose that the large differences in central metabolism required at high and low salinities dictate the striking divide between freshwater and marine microbiomes, and that the ability to inhabit different salinity regimes evolved early during bacterial phylogenetic differentiation. These findings significantly advance our understanding of microbial distributions and stress the need to incorporate salinity in future climate change models that predict increased levels of precipitation and a reduction in salinity. PMID:24586863

  9. Functional tradeoffs underpin salinity-driven divergence in microbial community composition.

    PubMed

    Dupont, Chris L; Larsson, John; Yooseph, Shibu; Ininbergs, Karolina; Goll, Johannes; Asplund-Samuelsson, Johannes; McCrow, John P; Celepli, Narin; Allen, Lisa Zeigler; Ekman, Martin; Lucas, Andrew J; Hagström, Åke; Thiagarajan, Mathangi; Brindefalk, Björn; Richter, Alexander R; Andersson, Anders F; Tenney, Aaron; Lundin, Daniel; Tovchigrechko, Andrey; Nylander, Johan A A; Brami, Daniel; Badger, Jonathan H; Allen, Andrew E; Rusch, Douglas B; Hoffman, Jeff; Norrby, Erling; Friedman, Robert; Pinhassi, Jarone; Venter, J Craig; Bergman, Birgitta

    2014-01-01

    Bacterial community composition and functional potential change subtly across gradients in the surface ocean. In contrast, while there are significant phylogenetic divergences between communities from freshwater and marine habitats, the underlying mechanisms to this phylogenetic structuring yet remain unknown. We hypothesized that the functional potential of natural bacterial communities is linked to this striking divide between microbiomes. To test this hypothesis, metagenomic sequencing of microbial communities along a 1,800 km transect in the Baltic Sea area, encompassing a continuous natural salinity gradient from limnic to fully marine conditions, was explored. Multivariate statistical analyses showed that salinity is the main determinant of dramatic changes in microbial community composition, but also of large scale changes in core metabolic functions of bacteria. Strikingly, genetically and metabolically different pathways for key metabolic processes, such as respiration, biosynthesis of quinones and isoprenoids, glycolysis and osmolyte transport, were differentially abundant at high and low salinities. These shifts in functional capacities were observed at multiple taxonomic levels and within dominant bacterial phyla, while bacteria, such as SAR11, were able to adapt to the entire salinity gradient. We propose that the large differences in central metabolism required at high and low salinities dictate the striking divide between freshwater and marine microbiomes, and that the ability to inhabit different salinity regimes evolved early during bacterial phylogenetic differentiation. These findings significantly advance our understanding of microbial distributions and stress the need to incorporate salinity in future climate change models that predict increased levels of precipitation and a reduction in salinity. PMID:24586863

  10. Deposition and early hydrologic evolution of Westwater Canyon wet alluvial-fan system

    SciTech Connect

    Galloway, W.E.

    1980-01-01

    The Westwater Canyon Member is one of several large, low-gradient alluvial fans that compose the Morrison Formation in the Four Corners area. Morrison fans were deposited by major laterally migrating streams entering a broad basin bounded by highlands to the west and south. The Westwater Canyon sand framework consists of a downfan succession of 1) proximal braided channel, 2) straight bed-load channel, 3) sinuous mixed-load channel, and 4) distributary mixed-load-channel sand bodies. Regional sand distribution and facies patterns are highly digitate and radiate from a point source located northwest of Gallup, New Mexico. Early ground-water flow evolution within the Westwater Canyon fan aquifer system can be inferred by analogy with Quaternary wet-fan deposits and by the interpreted paragenetic sequence of diagenetic features present. Syndepositional flow was controlled by the downfan hydrodynamic gradient and the high horizontal and vertical transmissivity of the sand-rich fan aquifer. Dissolution and transport of soluble humate would be likely in earliest ground water, which was abundant, fresh, and slightly alkaline. With increasing confinement of the aquifer below less permeable tuffaceous Brushy Basin deposits and release of soluble constituents from volcanic ash, flow patterns stabilized, and relatively more saline, uranium-rich ground water permeated the aquifer. Uranium mineralization occurred during this early postdepositional, semiconfined flow phase. Development of overlying Dakota swamps suggests a shallow water table indicative of regional dischare or stagnation. In either event, only limited downward flux of acidic water is recorded by local, bleached, kaolinized zones where the Westwater Canyon directly underlies the Dakota swamps. Subsequent ground-water flow phases have further obscured primary alteration patterns and caused local oxidation and redistribution of uranium.

  11. Wet solids flow enhancemant

    SciTech Connect

    Caram, H.S.; Foster, N.; Wildman, D.J.

    1996-12-31

    WE used glass beads of different sizes as.a model system to study the flow enhancing properties of Octadecyltrichlorosilane (OTS). 0TS provides Si(CH{sub 2}){sub 17}CH{sub 3} groups that bind with the surface hydrox groups to make it hydrophobic. Experimental data showed, indeed, that surface hydrophobicity promotes the flow of wet granular materials. Mixtures of different percentage of silanized/unsilanized particles were prepared for tensile strength measurements. The tensile strength decreased as more silanized particles were added to the samples. The relationship between dimensionless tensile strength and void fraction followed the correlation found by Pierrat (1994). Contact angles were larger for the silanized particles, as compared with unsilanized ones.

  12. Wetting of cholesteric liquid crystals.

    PubMed

    Silvestre, Nuno M; Figueirinhas Pereira, Maria Carolina; Bernardino, Nelson R; Telo da Gama, Margarida M

    2016-02-01

    We investigate theoretically the wetting properties of cholesteric liquid crystals at a planar substrate. If the properties of substrate and of the interface are such that the cholesteric layers are not distorted, the wetting properties are similar to those of a nematic liquid crystal. If, on the other hand, the anchoring conditions force the distortion of the liquid crystal layers the wetting properties are altered, the free cholesteric-isotropic interface is non-planar and there is a layer of topological defects close to the substrate. These deformations can either promote or hinder the wetting of the substrate by a cholesteric, depending on the properties of the cholesteric liquid crystal. PMID:26920516

  13. Effects of salinity on leaf breakdown: Dryland salinity versus salinity from a coalmine.

    PubMed

    Sauer, Felix G; Bundschuh, Mirco; Zubrod, Jochen P; Schäfer, Ralf B; Thompson, Kristie; Kefford, Ben J

    2016-08-01

    Salinization of freshwater ecosystems as a result of human activities represents a global threat for ecosystems' integrity. Whether different sources of salinity with their differing ionic compositions lead to variable effects in ecosystem functioning is unknown. Therefore, the present study assessed the impact of dryland- (50μS/cm to 11,000μS/cm) and coalmine-induced (100μS/cm to 2400μS/cm) salinization on the leaf litter breakdown, with focus on microorganisms as main decomposer, in two catchments in New South Wales, Australia. The breakdown of Eucalyptus camaldulensis leaves decreased with increasing salinity by up to a factor of three. Coalmine salinity, which is characterised by a higher share of bicarbonates, had a slightly but consistently higher breakdown rate at a given salinity relative to dryland salinity, which is characterised by ionic proportions similar to sea water. Complementary laboratory experiments supported the stimulatory impact of sodium bicarbonates on leaf breakdown when compared to sodium chloride or artificial sea salt. Furthermore, microbial inoculum from a high salinity site (11,000μS/cm) yielded lower leaf breakdown at lower salinity relative to inoculum from a low salinity site (50μS/cm). Conversely, inoculum from the high salinity site was less sensitive towards increasing salinity levels relative to inoculum from the low salinity site. The effects of the different inoculum were the same regardless of salt source (sodium bicarbonate, sodium chloride and artificial sea salt). Finally, the microorganism-mediated leaf litter breakdown was most efficient at intermediate salinity levels (≈500μS/cm). The present study thus points to severe implications of increasing salinity intensities on the ecosystem function of leaf litter breakdown, while the underlying processes need further scrutiny. PMID:27393920

  14. Wet Winding Improves Coil Encapsulation

    NASA Technical Reports Server (NTRS)

    Hill, A. J.

    1987-01-01

    Wet-winding process encapsulates electrical coils more uniformily than conventional processes. Process requires no vacuum pump and adapts easily to existing winding machines. Encapsulant applied to each layer of wire as soon as added to coil. Wet-winding process eliminates voids, giving more uniformly encapsulated coil.

  15. Extensive wetting due to roughness

    SciTech Connect

    Yost, F.G.; Michael, J.R.; Eisenmann, E.T. . Center for Solder Science and Technology)

    1995-01-01

    Typically, a small mass of eutectic Sn-Pb solder wets a copper surface and flows radially outward to form a hemispherical shape with a contact angle of approx. 15--20 deg. When a similar mass of solder wets and thick electroless copper coated substrate, rapid radial flow commences and surprising new effects occur. Thick coats of electroless copper have a nodular surface structure and spreading on it does not subside until all solder is consumed. When the nodular structure is wetted by solder a coastline'' with many nearby islands'' are defined. Photos of regions at the wetting front were taken in the backscatter imaging mode of an SEM. These images show that solder wets the valleys between the surface nodules forming a delicate, lacy arrangement. The geometry of this coastal'' solder structure is described as fractal-like having a dimension D = 1.38 making it similar to drying fronts and cloud configurations. The importance of surface roughness in wetting phenomena is discussed in the light of an extensive history on the subject. It is shown that for spontaneous flow, assisted by roughness, the surface geometry must consist of local angles that are larger than the equilibrium contact angle. Kinetics of the wetting process are demonstrated by image analysis of wetted area taken from videotaped experiments. These experimental kinetics are shown to be similar in form to flow in open channel capillaries.

  16. Overview of SMOS Salinity

    NASA Astrophysics Data System (ADS)

    Nicolas, R.

    2014-12-01

    While it is well known that the ocean is one of the most important components of the climate system, with a heat capacity 1100 times greater than the atmosphere, the ocean is also the primary reservoir for freshwater transport to the atmosphere and largest component of the global water cycle. Two new satellite sensors, the ESA Soil Moisture and Ocean Salinity (SMOS) and the NASA Aquarius SAC-D missions are now providing the first space borne measurements of the sea surface salinity (SSS). In this talk, we will present examples demonstrating how SMOS-derived SSS data are being used to better characterize key land-ocean and atmosphere-ocean interaction processes that occur within the marine hydrological cycle. In particular, we shall illustrate how SMOS and its ocean mapping capability provides observations across the world's largest tropical ocean fresh pool regions and we will discuss intra-seasonal to interannual precipitation impacts as well as large-scale river runoff from the Amazon-Orinoco and Congo rivers and its offshore advection. Synergistic multi-satellite analyses of these new surface salinity data sets combined with sea surface temperature, dynamical height and currents from altimetry, surface wind, ocean color, rainfall estimates, and in situ observations will be shown to yield new freshwater budget and ocean circulation insight. Examples of SMOS capabilities of monitoring salt exchanges across the Gulf Stream through meso-scale eddies will be provided. SSS observations from the SMOS and Aquarius/SAC-D sensors are combined to examine the response of the upper ocean to tropical cyclone passage including the potential role that a freshwater-induced upper ocean barrier layer may play in modulating surface cooling and enthalpy flux in tropical cyclone track regions.

  17. Salinity driven oceanographic upwelling

    DOEpatents

    Johnson, David H.

    1986-01-01

    The salinity driven oceanographic upwelling is maintained in a mariculture device that includes a long main duct in the general shape of a cylinder having perforated cover plates at each end. The mariculture device is suspended vertically in the ocean such that one end of the main duct is in surface water and the other end in relatively deep water that is cold, nutrient rich and relatively fresh in comparison to the surface water which is relatively warm, relatively nutrient deficient and relatively saline. A plurality of elongated flow segregating tubes are disposed in the main duct and extend from the upper cover plate beyond the lower cover plate into a lower manifold plate. The lower manifold plate is spaced from the lower cover plate to define a deep water fluid flow path to the interior space of the main duct. Spacer tubes extend from the upper cover plate and communicate with the interior space of the main duct. The spacer tubes are received in an upper manifold plate spaced from the upper cover plate to define a surface water fluid flow path into the flow segregating tubes. A surface water-deep water counterflow is thus established with deep water flowing upwardly through the main duct interior for discharge beyond the upper manifold plate while surface water flows downwardly through the flow segregating tubes for discharge below the lower manifold plate. During such counterflow heat is transferred from the downflowing warm water to the upflowing cold water. The flow is maintained by the difference in density between the deep water and the surface water due to their differences in salinity. The upwelling of nutrient rich deep water is used for marifarming by fertilizing the nutrient deficient surface water.

  18. Salinity driven oceanographic upwelling

    DOEpatents

    Johnson, D.H.

    1984-08-30

    The salinity driven oceanographic upwelling is maintained in a mariculture device that includes a long main duct in the general shape of a cylinder having perforated cover plates at each end. The mariculture device is suspended vertically in the ocean such that one end of the main duct is in surface water and the other end in relatively deep water that is cold, nutrient rich and relatively fresh in comparison to the surface water which is relatively warm, relatively nutrient deficient and relatively saline. A plurality of elongated flow segregating tubes are disposed in the main duct and extend from the upper cover plate beyond the lower cover plate into a lower manifold plate. The lower manifold plate is spaced from the lower cover plate to define a deep water fluid flow path to the interior space of the main duct. Spacer tubes extend from the upper cover plate and communicate with the interior space of the main duct. The spacer tubes are received in an upper manifold plate spaced from the upper cover plate to define a surface water fluid flow path into the flow segregating tubes. A surface water-deep water counterflow is thus established with deep water flowing upwardly through the main duct interior for discharge beyond the upper manifold plate while surface water flows downwardly through the flow segregating tubes for discharge below the lower manifold plate. During such counterflow heat is transferred from the downflowing warm water to the upflowing cold water. The flow is maintained by the difference in density between the deep water and the surface water due to their differences in salinity. The upwelling of nutrient rich deep water is used for marifarming by fertilizing the nutrient deficient surface water. 1 fig.

  19. Characterization of deep wet etching of glass

    NASA Astrophysics Data System (ADS)

    Iliescu, Ciprian; Chen, Bangtao; Tay, Francis E. H.; Xu, Guolin; Miao, Jianmin

    2006-01-01

    This paper presents a characterization of wet etching of glass in HF-based solutions with a focus on etching rate, masking layers and quality of the generated surface. The first important factor that affects the deep wet etching process is the glass composition. The presence of oxides such as CaO, MgO or Al IIO 3 that give insoluble products after reaction with HF can generate rough surface and modify the etching rate. A second factor that influences especially the etch rate is the annealing process (560°C / 6 hours in N II environment). For annealed glass samples an increase of the etch rate with 50-60% was achieved. Another important factor is the concentration of the HF solution. For deep wet etching of Pyrex glass in hydrofluoric acid solution, different masking layers such as Cr/Au, PECVD amorphous silicon, LPCVD polysilicon and silicon carbide are analyzed. Detailed studies show that the stress in the masking layer is a critical factor for deep wet etching of glass. A low value of compressive stress is recommended. High value of tensile stress in the masking layer (200-300 MPa) can be an important factor in the generation of the pinholes. Another factor is the surface hydrophilicity. A hydrophobic surface of the masking layer will prevent the etching solution from flowing through the deposition defects (micro/nano channels or cracks) and the generation of pinholes is reduced. The stress gradient in the masking layer can also be an important factor in generation of the notching defects on the edges. Using these considerations a special multilayer masks Cr/Au/Photoresist (AZ7220) and amorphous silicon/silicon carbide/Photoresist were fabricated for deep wet etching of a 500 μm and 1mm-thick respectively Pyrex glass wafers. In both cases the etching was performed through wafer. From our knowledge these are the best results reported in the literature. The quality of the generated surface is another important factor in the fabrication process. We notice that the

  20. Underwater wet welding of steel

    SciTech Connect

    Ibarra, S.; Liu, S.; Olson, D.L.

    1995-05-01

    Underwater wet welding is conducted directly in water with the shielded metal arc (SMA) and flux cored arc (FCA) welding processes. Underwater wet welding has been demonstrated as an acceptable repair technique down to 100 meters (325 ft.) in depth, but wet welds have been attempted on carbon steel structures down to 200 meters (650 ft.). The primary purpose of this interpretive report is to document and evaluate current understanding of metallurgical behavior of underwater wet welds so that new welding consumables can be designed and new welding practices can be developed for fabrication and repair of high strength steel structures at greater depths. First the pyrometallurgical and physical metallurgy behaviors of underwater weldments are discussed. Second, modifications of the welding consumables and processes are suggested to enhance the ability to apply wet welding techniques.

  1. Does surface roughness amplify wetting?

    SciTech Connect

    Malijevský, Alexandr

    2014-11-14

    Any solid surface is intrinsically rough on the microscopic scale. In this paper, we study the effect of this roughness on the wetting properties of hydrophilic substrates. Macroscopic arguments, such as those leading to the well-known Wenzel's law, predict that surface roughness should amplify the wetting properties of such adsorbents. We use a fundamental measure density functional theory to demonstrate the opposite effect from roughness for microscopically corrugated surfaces, i.e., wetting is hindered. Based on three independent analyses we show that microscopic surface corrugation increases the wetting temperature or even makes the surface hydrophobic. Since for macroscopically corrugated surfaces the solid texture does indeed amplify wetting there must exist a crossover between two length-scale regimes that are distinguished by opposite response on surface roughening. This demonstrates how deceptive can be efforts to extend the thermodynamical laws beyond their macroscopic territory.

  2. Salinity and turbidity distributions in the Brisbane River estuary, Australia

    NASA Astrophysics Data System (ADS)

    Yu, Yingying; Zhang, Hong; Lemckert, Charles

    2014-11-01

    The Brisbane River estuary (BRE) in Australia not only plays a vital role in ecosystem health, but is also of importance for people who live nearby. Comprehensive investigations, both in the short- and long-term, into the salinity and turbidity distributions in the BRE were conducted. Firstly, the analysis of numerical results revealed that the longitudinal salinity varied at approximately 0.45 and 0.61 psu/h during neap and spring tides, respectively. The turbidity stayed at a higher level and was less impacted by tide in the upper estuary, however, the water cleared up while the tide changed from flood to ebb in the mid and lower estuary. The second investigation into the seasonal variations of salinity and turbidity in the BRE was conducted, using ten-year field measurement data. A fourth-order polynomial equation was proposed, describing the longitudinal variation in salinity dilution changes as the upstream distance in the BRE during the wet and dry seasons. From the observation, the mid and upper estuaries were vertically well-mixed during both seasons, but the lower BRE was stratified, particularly during the wet season. The estuary turbidity maximum (ETM) zone was about 10 km longer during the wet season than the dry season. Particular emphasis was given to the third investigation into the use of satellite remote sensing techniques for estimation of the turbidity level in the BRE. A linear relationship between satellite observed water reflectance and surface turbidity level in the BRE was validated with an R2 of 0.75. The application of satellite-observed water reflectance therefore provided a practical solution for estimating surface turbidity levels of estuarine rivers not only under normal weather conditions, but also during flood events. The results acquired from this study are valuable for further hydrological research in the BRE and particularly prominent for immediate assessment of flood impacts.

  3. Microwave radiometer measurement of tidally induced salinity changes off the Georgia coast

    NASA Technical Reports Server (NTRS)

    Kendall, B. M.; Blanton, J. O.

    1981-01-01

    A quasi-synoptic survey of tidally induced salinity changes off the Georgia coast was performed by using a L band microwave radiomater onboard a NASA aircraft. Salinity maps were obtained for ebb and flood conditions in order to define the salinity distributions near rivers and sounds and major changes that occur from ebb flow to flood flow. The Savannah River plume dominated the salinity regime and extended out from the Savannah River mouth about 12 km during ebb tidal conditions. The plume merged into a band of low salinity water extending along the Georgia-South Carolina coast which was produced by the many river sources of freshwater entering the coastal waters. The changes in salinity observed offshore of the river plume area were consistent with estimates of the changes that would occur over a typical tidal excursion perpendicular to the observed gradient.

  4. Influence of Microsprinkler Irrigation Amount on Water, Soil, and pH Profiles in a Coastal Saline Soil

    PubMed Central

    Chu, Linlin; Kang, Yaohu; Wan, Shuqin

    2014-01-01

    Microsprinkler irrigation is a potential method to alleviate soil salinization. After conducting a homogeneous, highly saline, clayey, and coastal soil from the Bohai Gulf in northern China in a column experiment, the results show that the depth of the wetting front increased as the water amount applied increased, low-salinity and low-SAR enlarged after irrigation and water redistribution, and the soil pH increased with an increase in irrigation amount. We concluded that a water amount of 207 mm could be used to reclaim the coastal saline soil in northern China. PMID:25147843

  5. Endoscopic ultrasound-guided fine needle aspiration: The wet suction technique.

    PubMed

    Villa, Nicolas A; Berzosa, Manuel; Wallace, Michael B; Raijman, Isaac

    2016-01-01

    Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has become a fundamental tool in obtaining cytopathological diagnosis of pancreatic tumors. When sampling solid lesions of the pancreas, the endosonographer can use two suction techniques to enhance tissue acquisition; the dry and the wet suction techniques. The standard dry suction technique relies on applying negative pressure suction on the proximal end of the needle after the stylet is removed with a pre-vacuum syringe. The wet suction technique relies on pre-flushing the needle with saline to replace the column of air with fluid followed by aspiration the proximal end by using a prefilled syringe with saline. A new modified wet suction technique (hybrid suction technique) relies on preloading the needle with saline, but having continuous negative pressure with a pre-vacuum syringe to avoid manual intermittent suction. Tissue acquisition can be enhanced by applying fluid dynamic principles to the current aspiration techniques, such as the column of water used in the needle of the wet technique. In this review, we will focus on EUS-FNA using the wet suction technique for sampling of pancreatic solid lesions. PMID:26879162

  6. Endoscopic ultrasound-guided fine needle aspiration: The wet suction technique

    PubMed Central

    Villa, Nicolas A.; Berzosa, Manuel; Wallace, Michael B.; Raijman, Isaac

    2016-01-01

    Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has become a fundamental tool in obtaining cytopathological diagnosis of pancreatic tumors. When sampling solid lesions of the pancreas, the endosonographer can use two suction techniques to enhance tissue acquisition; the dry and the wet suction techniques. The standard dry suction technique relies on applying negative pressure suction on the proximal end of the needle after the stylet is removed with a pre-vacuum syringe. The wet suction technique relies on pre-flushing the needle with saline to replace the column of air with fluid followed by aspiration the proximal end by using a prefilled syringe with saline. A new modified wet suction technique (hybrid suction technique) relies on preloading the needle with saline, but having continuous negative pressure with a pre-vacuum syringe to avoid manual intermittent suction. Tissue acquisition can be enhanced by applying fluid dynamic principles to the current aspiration techniques, such as the column of water used in the needle of the wet technique. In this review, we will focus on EUS-FNA using the wet suction technique for sampling of pancreatic solid lesions. PMID:26879162

  7. WET AND DRY SCRUBBERS FOR EMISSION CONTROL

    EPA Science Inventory

    Generally speaking, absorption equipment includes two major categories: Wet adsorption scrubbers (or wet scrubbers); Dry absorption scrubbers (or dry scrubbers).
    Wet scrubbers: As the name implies, wet scrubbers (also known as wet collectors) are devices which use a liquid fo...

  8. Relationships between groundwater, surface water, and soil salinity in Polder 32, Southwest Bangladesh

    NASA Astrophysics Data System (ADS)

    Fry, D. C.; Ayers, J. C.

    2014-12-01

    In the coastal areas of Southwest Bangladesh polders are surrounded by tidal channels filled with brackish water. In the wet season, farmers create openings in the embankments to irrigate rice paddies. In the dry season, farmers do the same to create saline shrimp ponds. Residents on Polder 32, located within the Ganges-Brahmaputra-Meghna delta system, practice these seasonal farming techniques. Soils in the area are entisols, being sediment recently deposited, and contain mostly silt-sized particles. Brackish water in brine shrimp ponds may deposit salt in the soil, causing soil salinization. However, saline connate groundwater could also be contributing to soil salinization. Groundwater, surface water (fresh water pond, rice paddy and tidal channel water) and soil samples have been analyzed via inductively coupled plasma optical emission spectroscopy, inductively coupled plasma mass spectroscopy and ion chromatography in an attempt to correlate salinity measurements with each other in order to determine major sources of soil salinity. Multiple parameters, including distances of samples from tidal channels, inland streams, shrimp ponds and tube wells were measured to see if spatial correlations exist. Similarly, values from wet and dry seasons were compared to quantify temporal variations. Salt content in many soil samples were found to be high enough to significantly decrease rice yields. Continued soil salinization can decrease these yields even more, leading to farmers not producing enough food to sustain their families.

  9. Proteomics, metabolomics, and ionomics perspectives of salinity tolerance in halophytes.

    PubMed

    Kumari, Asha; Das, Paromita; Parida, Asish Kumar; Agarwal, Pradeep K

    2015-01-01

    Halophytes are plants which naturally survive in saline environment. They account for ∼1% of the total flora of the world. They include both dicots and monocots and are distributed mainly in arid, semi-arid inlands and saline wet lands along the tropical and sub-tropical coasts. Salinity tolerance in halophytes depends on a set of ecological and physiological characteristics that allow them to grow and flourish in high saline conditions. The ability of halophytes to tolerate high salt is determined by the effective coordination between various physiological processes, metabolic pathways and protein or gene networks responsible for delivering salinity tolerance. The salinity responsive proteins belong to diverse functional classes such as photosynthesis, redox homeostasis; stress/defense, carbohydrate and energy metabolism, protein metabolism, signal transduction and membrane transport. The important metabolites which are involved in salt tolerance of halophytes are proline and proline analog (4-hydroxy-N-methyl proline), glycine betaine, pinitol, myo-inositol, mannitol, sorbitol, O-methylmucoinositol, and polyamines. In halophytes, the synthesis of specific proteins and osmotically active metabolites control ion and water flux and support scavenging of oxygen radicals under salt stress condition. The present review summarizes the salt tolerance mechanisms of halophytes by elucidating the recent studies that have focused on proteomic, metabolomic, and ionomic aspects of various halophytes in response to salinity. By integrating the information from halophytes and its comparison with glycophytes could give an overview of salt tolerance mechanisms in halophytes, thus laying down the pavement for development of salt tolerant crop plants through genetic modification and effective breeding strategies. PMID:26284080

  10. Therapeutic effects of compound hypertonic saline on rats with sepsis.

    PubMed

    Dong, Fang; Chen, Wei; Xu, Liang; Wang, Huabing; Lu, Huizhi

    2014-01-01

    Sepsis is one of the major causes of death and is the biggest obstacle preventing improvement of the success rate in curing critical illnesses. Currently, isotonic solutions are used in fluid resuscitation technique. Several studies have shown that hypertonic saline applied in hemorrhagic shock can rapidly increase the plasma osmotic pressure, facilitate the rapid return of interstitial fluid into the blood vessels, and restore the effective circulating blood volume. Here, we established a rat model of sepsis by using the cecal ligation and puncture approach. We found that intravenous injection of hypertonic saline dextran (7.5% NaCl/6% dextran) after cecal ligation and puncture can improve circulatory failure at the onset of sepsis. We found that the levels of tumor necrosis factor-α, interleukin-1β, interleukin-6 and intracellular adhesion molecule 1 levels in the lung tissue of cecal ligation and puncture rats treated with hypertonic saline dextran were significantly lower than the corresponding levels in the control group. We inferred that hypertonic saline dextran has a positive immunoregulatory effect and inhibits the overexpression of the inflammatory response in the treatment of sepsis. The percentage of neutrophils, lung myeloperoxidase activity, wet to dry weight ratio of lung tissues, histopathological changes in lung tissues, and indicators of arterial blood gas analysis was significantly better in the hypertonic saline dextran-treated group than in the other groups in this study. Hypertonic saline dextran-treated rats had significantly improved survival rates at 9 and 18 h compared to the control group. Our results suggest that hypertonic saline dextran plays a protective role in acute lung injury caused after cecal ligation and puncture. In conclusion, hypertonic/hyperoncotic solutions have beneficial therapeutic effects in the treatment of an animal model of sepsis. PMID:24983672

  11. Proteomics, metabolomics, and ionomics perspectives of salinity tolerance in halophytes

    PubMed Central

    Kumari, Asha; Das, Paromita; Parida, Asish Kumar; Agarwal, Pradeep K.

    2015-01-01

    Halophytes are plants which naturally survive in saline environment. They account for ∼1% of the total flora of the world. They include both dicots and monocots and are distributed mainly in arid, semi-arid inlands and saline wet lands along the tropical and sub-tropical coasts. Salinity tolerance in halophytes depends on a set of ecological and physiological characteristics that allow them to grow and flourish in high saline conditions. The ability of halophytes to tolerate high salt is determined by the effective coordination between various physiological processes, metabolic pathways and protein or gene networks responsible for delivering salinity tolerance. The salinity responsive proteins belong to diverse functional classes such as photosynthesis, redox homeostasis; stress/defense, carbohydrate and energy metabolism, protein metabolism, signal transduction and membrane transport. The important metabolites which are involved in salt tolerance of halophytes are proline and proline analog (4-hydroxy-N-methyl proline), glycine betaine, pinitol, myo-inositol, mannitol, sorbitol, O-methylmucoinositol, and polyamines. In halophytes, the synthesis of specific proteins and osmotically active metabolites control ion and water flux and support scavenging of oxygen radicals under salt stress condition. The present review summarizes the salt tolerance mechanisms of halophytes by elucidating the recent studies that have focused on proteomic, metabolomic, and ionomic aspects of various halophytes in response to salinity. By integrating the information from halophytes and its comparison with glycophytes could give an overview of salt tolerance mechanisms in halophytes, thus laying down the pavement for development of salt tolerant crop plants through genetic modification and effective breeding strategies. PMID:26284080

  12. Forced wetting and hydrodynamic assist

    NASA Astrophysics Data System (ADS)

    Blake, Terence D.; Fernandez-Toledano, Juan-Carlos; Doyen, Guillaume; De Coninck, Joël

    2015-11-01

    Wetting is a prerequisite for coating a uniform layer of liquid onto a solid. Wetting failure and air entrainment set the ultimate limit to coating speed. It is well known in the coating art that this limit can be postponed by manipulating the coating flow to generate what has been termed "hydrodynamic assist," but the underlying mechanism is unclear. Experiments have shown that the conditions that postpone air entrainment also reduce the apparent dynamic contact angle, suggesting a direct link, but how the flow might affect the contact angle remains to be established. Here, we use molecular dynamics to compare the outcome of steady forced wetting with previous results for the spontaneous spreading of liquid drops and apply the molecular-kinetic theory of dynamic wetting to rationalize our findings and place them on a quantitative footing. The forced wetting simulations reveal significant slip at the solid-liquid interface and details of the flow immediately adjacent to the moving contact line. Our results confirm that the local, microscopic contact angle is dependent not simply only on the velocity of wetting but also on the nature of the flow that drives it. In particular, they support an earlier suggestion that during forced wetting, an intense shear stress in the vicinity of the contact line can assist surface tension forces in promoting dynamic wetting, thus reducing the velocity-dependence of the contact angle. Hydrodynamic assist then appears as a natural consequence of wetting that emerges when the contact line is driven by a strong and highly confined flow. Our theoretical approach also provides a self-consistent model of molecular slip at the solid-liquid interface that enables its magnitude to be estimated from dynamic contact angle measurements. In addition, the model predicts how hydrodynamic assist and slip may be influenced by liquid viscosity and solid-liquid interactions.

  13. The effect of water salinity on wood breakdown in semiarid Mediterranean streams.

    PubMed

    Gómez, Rosa; Asencio, Antonia Dolores; Picón, José María; Del Campo, Rubén; Arce, María Isabel; del Mar Sánchez-Montoya, María; Suárez, María Luisa; Vidal-Abarca, María Rosario

    2016-01-15

    Saline streams occur naturally and they are distributed worldwide, particularly in arid and semiarid regions, but human activities have also increased their number in many parts of the world. Little attention has been paid to assess increasing salt effects on organic matter decomposition. The objectives of this study were to analyse wood breakdown rates and how salinity affects them in 14 streams that exemplify a natural salinity gradient. We also analysed the effect of this gradient on changes in wood chemical composition, fungal biomass and microbial activity. Our results showed low breakdown rates (0.0010-0.0032 d(-1)), but they fell within the same range as those reported in freshwater streams when a similar woody substrate was used. However, salinity had a negative effect on the breakdown rates and fungal biomass along the salinity gradient, and led to noticeable changes in wood composition. Water salinity did not affect microbial activity estimated using hydrolysis of fluorescein diacetate. Variation in breakdown rates and fungal biomass across streams was mediated mainly by salinity, and later by stream discharge. Despite the role of fungi in stick breakdown, the potential wood abrasion by salts must be analysed in detail to accurately understand the effect of increasing salinity on organic matter breakdown. Finally, our results indicate that increased salinity worldwide by human activities or by the global warming would imply organic matter breakdown and mineralisation slowing down, even in natural saline streams. However, because many variables are implicated, the final effect of climatic change on organic matter decomposition in streams is difficult to predict. PMID:26410723

  14. Structure and flow-induced variability of the subtidal salinity field in northern San Francisco Bay

    USGS Publications Warehouse

    Monismith, Stephen G.; Kimmerer, W.; Burau, J.R.; Stacey, M.T.

    2002-01-01

    The structure of the salinity field in northern San Francisco Bay and how it is affected by freshwater flow are discussed. Two datasets are examined: the first is 23 years of daily salinity data taken by the U.S. Bureau of Reclamation along the axis of northern San Francisco Bay: the second is a set of salinity transects taken by the U.S. Geological Survey between 1988 and 1993. Central to this paper is a measure of salinity intrusion. X2: the distance from the Golden Gate Bridge to where the bottom salinity is 2 psu. Using X2 to scale distance, the authors find that for most flow conditions, the mean salinity distribution of the estuary is nearly self-similar with a salinity gradient in the center 70% of the region between the Golden Gate and X2 that is proportional to X2-1. Analysis of covariability of Q and X2 showed a characteristics timescale of adjustment of the salinity field of approximately 2 weeks. The steady-state response deduced from the X2 time series implies that X2 is proportional to riverflow to the 1/7 power. This relation, which differs from the standard 1/3 power dependence that is derived theoretically assuming constant exchange coefficients, shows that the upstream salt flux associated with gravitational circulation is more sensitive to the longitudinal salinity gradient than theory supposes. This is attributed to the strengthening of stratification caused by the stronger longitudinal salinity gradient that accompanies larger river flows.

  15. Effects of temperature and conditioning on contact lens wetting angles.

    PubMed

    Knick, P D; Huff, J W

    1991-07-01

    Because wettability is not always examined under standard conditions, we investigated the temperature dependence of saline wettability on unconditioned and conditioned polymethylmethacrylate (PMMA), cellulose acetate butyrate (CAB), and three silicone acrylate lens materials. Sessile drop contact angles were measured in a humidity chamber at 23 degrees C and 34 degrees C using laser-assisted contact angle goniometry. In separate experiments, saline-stored and preconditioned lenses were examined either with or without rinsing. Sessile drop contact angles at 34 degrees C were within 2 degrees to 5 degrees of the room temperature values for both conditioned and unconditioned lenses, demonstrating a negligible temperature dependence. At both temperatures, the conditioned PMMA, CAB, silafocon A, and pasifocon C lenses wet slightly better, by 1 degree to 12 degrees, than unconditioned lenses. However, this increase was only significant with PMMA and silafocon A (P less than 0.05) and reversed when the preconditioned lenses were rinsed repeatedly in saline and reexamined. The results suggest that for these materials: 1) in vitro saline contact angles do not approach those seen on the eye, and this discrepancy can not be explained by temperature or conditioning; and 2) conditioning does not increase material wettability but merely forms a temporary hydrophilic interface that is more wettable than the lens material. PMID:1654228

  16. Growth responses of the mangrove Avicennia marina to salinity: development and function of shoot hydraulic systems require saline conditions

    PubMed Central

    Nguyen, Hoa T.; Stanton, Daniel E.; Schmitz, Nele; Farquhar, Graham D.; Ball, Marilyn C.

    2015-01-01

    Background and Aims Halophytic eudicots are characterized by enhanced growth under saline conditions. This study combines physiological and anatomical analyses to identify processes underlying growth responses of the mangrove Avicennia marina to salinities ranging from fresh- to seawater conditions. Methods Following pre-exhaustion of cotyledonary reserves under optimal conditions (i.e. 50 % seawater), seedlings of A. marina were grown hydroponically in dilutions of seawater amended with nutrients. Whole-plant growth characteristics were analysed in relation to dry mass accumulation and its allocation to different plant parts. Gas exchange characteristics and stable carbon isotopic composition of leaves were measured to evaluate water use in relation to carbon gain. Stem and leaf hydraulic anatomy were measured in relation to plant water use and growth. Key Results Avicennia marina seedlings failed to grow in 0–5 % seawater, whereas maximal growth occurred in 50–75 % seawater. Relative growth rates were affected by changes in leaf area ratio (LAR) and net assimilation rate (NAR) along the salinity gradient, with NAR generally being more important. Gas exchange characteristics followed the same trends as plant growth, with assimilation rates and stomatal conductance being greatest in leaves grown in 50–75 % seawater. However, water use efficiency was maintained nearly constant across all salinities, consistent with carbon isotopic signatures. Anatomical studies revealed variation in rates of development and composition of hydraulic tissues that were consistent with salinity-dependent patterns in water use and growth, including a structural explanation for low stomatal conductance and growth under low salinity. Conclusions The results identified stem and leaf transport systems as central to understanding the integrated growth responses to variation in salinity from fresh- to seawater conditions. Avicennia marina was revealed as an obligate halophyte

  17. Saline as the Sole Contrast Agent for Successful MRI-guided Epidural Injections

    SciTech Connect

    Deli, Martin; Mateiescu, Serban Busch, Martin; Becker, Jan Garmer, Marietta Groenemeyer, Dietrich

    2013-06-15

    Purpose. To assess the performance of sterile saline solution as the sole contrast agent for percutaneous magnetic resonance imaging (MRI)-guided epidural injections at 1.5 T. Methods. A retrospective analysis of two different techniques of MRI-guided epidural injections was performed with either gadolinium-enhanced saline solution or sterile saline solution for documentation of the epidural location of the needle tip. T1-weighted spoiled gradient echo (FLASH) images or T2-weighted single-shot turbo spin echo (HASTE) images visualized the test injectants. Methods were compared by technical success rate, image quality, table time, and rate of complications. Results. 105 MRI-guided epidural injections (12 of 105 with gadolinium-enhanced saline solution and 93 of 105 with sterile saline solution) were performed successfully and without complications. Visualization of sterile saline solution and gadolinium-enhanced saline solution was sufficient, good, or excellent in all 105 interventions. For either test injectant, quantitative image analysis demonstrated comparable high contrast-to-noise ratios of test injectants to adjacent body substances with reliable statistical significance levels (p < 0.001). The mean table time was 22 {+-} 9 min in the gadolinium-enhanced saline solution group and 22 {+-} 8 min in the saline solution group (p = 0.75). Conclusion. Sterile saline is suitable as the sole contrast agent for successful and safe percutaneous MRI-guided epidural drug delivery at 1.5 T.

  18. URBAN WET-WEATHER FLOWS

    EPA Science Inventory

    Provides the annual Urban Wet Weather Flow Literture Review for the calendar year 1998 conducted for the Water Environment Federation. It contains hundreds of citations covering the topics of characterization and effects, management, modeling, regulator policies and contol and t...

  19. Passive Microwave Measurements of Salinity: The Gulf Stream Experiment

    NASA Technical Reports Server (NTRS)

    LeVine, D. M.; Koblinsky, C.; Haken, M.; Howden, S.; Bingham, F.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    Passive microwave sensors at L-band (1.4 GHz) operating from aircraft have demonstrated that salinity can be measured with sufficient accuracy (I psu) to be scientifically meaningful in coastal waters. However, measuring salinity in the open ocean presents unresolved issues largely because of the much greater accuracy (approximately 0.2 psu) required of global maps to be scientifically viable. The development of a satellite microwave instrument to make global measurements of SSS (Sea Surface Salinity) is the focus of a joint JPL/GSFC/NASA ocean research program called Aquarius. In the summer of 1999 a series of measurements called, The Gulf Stream Experiment, were conducted as part of research at the Goddard Space Flight Center to test the potential for passive microwave remote sensing of salinity in the open ocean. The measurements consisted of airborne microwave instruments together with ships and drifters for surface truth. The study area was a 200 km by 100 km rectangle about 250 km east of Delaware Bay between the continental shelf waters and north wall of the Gulf Stream. The primary passive instruments were the ESTAR radiometer (L-band, H-pol) and the SLFMR radiometer (L-band, V-pol). In addition, the instruments on the aircraft included a C-band radiometer (ACMR), an ocean wave scatterometer (ROWS) and an infrared radiometer (for surface temperature). These instruments were mounted on the NASA P-3 Orion aircraft. Sea surface measurements consisted of thermosalinograph data provided by the R/V Cape Henlopen and the MN Oleander, and data from salinity and temperature sensors on three surface drifters deployed from the R/V Cape Henlopen. The primary experiment period was August 26-September 2, 1999. During this period the salinity field within the study area consisted of a gradient on the order of 2-3 psu in the vicinity of the shelf break and a warm core ring with a gradient of 1-2 psu. Detailed maps were made with the airborne sensors on August 28 and 29 and

  20. WET BEAVER ROADLESS AREA, ARIZONA.

    USGS Publications Warehouse

    Ulrich, George E.; Bielski, Alan M.

    1984-01-01

    On the basis of field studies there is little promise for the occurrence of mineral or energy resources in the Wet Beaver Roadless Area, Arizona. No significant concentrations of metals were indicated by geochemical sampling or aeromagnetic data within the area. Basaltic cinders and sandstone have been quarried for construction materials near the area but are readily available and more accessible outside the precipitous canyons of Wet Beaver Creek and its tributaries.

  1. Reentrant Wetting of Network Fluids

    NASA Astrophysics Data System (ADS)

    Bernardino, N. R.; Telo da Gama, M. M.

    2012-09-01

    We use a simple mesoscopic Landau-Safran theory of network fluids to show that a reentrant phase diagram, in the “empty liquid” regime, leads to nonmonotonic surface tension and reentrant wetting, as previously reported for binary mixtures. One of the wetting transitions is of the usual kind, but the low temperature transition may allow the display of the full range of fluctuation regimes predicted by renormalization group theory.

  2. Salinity and Bacterial Diversity: To What Extent Does the Concentration of Salt Affect the Bacterial Community in a Saline Soil?

    PubMed Central

    Canfora, Loredana; Bacci, Giovanni; Pinzari, Flavia; Lo Papa, Giuseppe; Dazzi, Carmelo; Benedetti, Anna

    2014-01-01

    In this study, the evaluation of soil characteristics was coupled with a pyrosequencing analysis of the V2-V3 16S rRNA gene region in order to investigate the bacterial community structure and diversity in the A horizon of a natural saline soil located in Sicily (Italy). The main aim of the research was to assess the organisation and diversity of microbial taxa using a spatial scale that revealed physical and chemical heterogeneity of the habitat under investigation. The results provided information on the type of distribution of different bacterial groups as a function of spatial gradients of soil salinity and pH. The analysis of bacterial 16S rRNA showed differences in bacterial composition and diversity due to a variable salt concentration in the soil. The bacterial community showed a statistically significant spatial variability. Some bacterial phyla appeared spread in the whole area, whatever the salinity gradient. It emerged therefore that a patchy saline soil can not contain just a single microbial community selected to withstand extreme osmotic phenomena, but many communities that can be variously correlated to one or more environmental parameters. Sequences have been deposited to the SRA database and can be accessed on ID Project PRJNA241061. PMID:25188357

  3. Flow convergence caused by a salinity minimum in a tidal channel

    USGS Publications Warehouse

    Warner, John C.; Schoellhamer, David H.; Burau, Jon R.; Schladow, S. Geoffrey

    2006-01-01

    Residence times of dissolved substances and sedimentation rates in tidal channels are affected by residual (tidally averaged) circulation patterns. One influence on these circulation patterns is the longitudinal density gradient. In most estuaries the longitudinal density gradient typically maintains a constant direction. However, a junction of tidal channels can create a local reversal (change in sign) of the density gradient. This can occur due to a difference in the phase of tidal currents in each channel. In San Francisco Bay, the phasing of the currents at the junction of Mare Island Strait and Carquinez Strait produces a local salinity minimum in Mare Island Strait. At the location of a local salinity minimum the longitudinal density gradient reverses direction. This paper presents four numerical models that were used to investigate the circulation caused by the salinity minimum: (1) A simple one-dimensional (1D) finite difference model demonstrates that a local salinity minimum is advected into Mare Island Strait from the junction with Carquinez Strait during flood tide. (2) A three-dimensional (3D) hydrodynamic finite element model is used to compute the tidally averaged circulation in a channel that contains a salinity minimum (a change in the sign of the longitudinal density gradient) and compares that to a channel that contains a longitudinal density gradient in a constant direction. The tidally averaged circulation produced by the salinity minimum is characterized by converging flow at the bed and diverging flow at the surface, whereas the circulation produced by the constant direction gradient is characterized by converging flow at the bed and downstream surface currents. These velocity fields are used to drive both a particle tracking and a sediment transport model. (3) A particle tracking model demonstrates a 30 percent increase in the residence time of neutrally buoyant particles transported through the salinity minimum, as compared to transport

  4. Tuning and predicting the wetting of nanoengineered material surface

    NASA Astrophysics Data System (ADS)

    Ramiasa-MacGregor, M.; Mierczynska, A.; Sedev, R.; Vasilev, K.

    2016-02-01

    The wetting of a material can be tuned by changing the roughness on its surface. Recent advances in the field of nanotechnology open exciting opportunities to control macroscopic wetting behaviour. Yet, the benchmark theories used to describe the wettability of macroscopically rough surfaces fail to fully describe the wetting behaviour of systems with topographical features at the nanoscale. To shed light on the events occurring at the nanoscale we have utilised model gradient substrata where surface nanotopography was tailored in a controlled and robust manner. The intrinsic wettability of the coatings was varied from hydrophilic to hydrophobic. The measured water contact angle could not be described by the classical theories. We developed an empirical model that effectively captures the experimental data, and further enables us to predict the wetting of surfaces with nanoscale roughness by considering the physical and chemical properties of the material. The fundamental insights presented here are important for the rational design of advanced materials having tailored surface nanotopography with predictable wettability.The wetting of a material can be tuned by changing the roughness on its surface. Recent advances in the field of nanotechnology open exciting opportunities to control macroscopic wetting behaviour. Yet, the benchmark theories used to describe the wettability of macroscopically rough surfaces fail to fully describe the wetting behaviour of systems with topographical features at the nanoscale. To shed light on the events occurring at the nanoscale we have utilised model gradient substrata where surface nanotopography was tailored in a controlled and robust manner. The intrinsic wettability of the coatings was varied from hydrophilic to hydrophobic. The measured water contact angle could not be described by the classical theories. We developed an empirical model that effectively captures the experimental data, and further enables us to predict the

  5. SETAC-U.S. EPA WET INITIATIVES: ALL WET AND NOTHING BUT WET

    EPA Science Inventory

    To ensure that sould scientific principles and sound science are applied to the challenging issues in t he Whole Effluent Toxicity (WET) process, the Society of Environmental Toxicology and Chemistry (SETAC) Foundation for Environmental Education was awarded a cooperative agreem...

  6. Interactive effects of chemical and biological controls on food-web composition in saline prairie lakes

    PubMed Central

    2012-01-01

    Salinity is restricting habitatability for many biota in prairie lakes due to limited physiological abilities to cope with increasing osmotic stress. Yet, it remains unclear how salinity effects vary among major taxonomic groups and what role other environmental parameters play in shaping food-web composition. To answer these questions, we sampled fish, zooplankton and littoral macroinvertebrates in 20 prairie lakes (Saskatchewan, Canada) characterized by large gradients in water chemistry and lake morphometry. We showed that salinity thresholds differed among major taxonomic groups, as most fishes were absent above salinities of 2 g L-1, while littoral macroinvertebrates were ubiquitous. Zooplankton occurred over the whole salinity range, but changed taxonomic composition as salinity increased. Subsequently, the complexity of fish community (diversity) was associated with large changes in invertebrate communities. The directional changes in invertebrate communities to smaller taxa indicated that complex fish assemblages resulted in higher predation pressure. Most likely, as the complexity of fish community decreased, controls of invertebrate assemblages shifted from predation to competition and ultimately to productivity in hypersaline lakes. Surprisingly, invertebrate predators did not thrive in the absence of fishes in these systems. Furthermore, the here identified salinity threshold for fishes was too low to be a result of osmotic stress. Hence, winterkill was likely an important factor eliminating fishes in low salinity lakes that had high productivity and shallow water depth. Ultimately, while salinity was crucial, intricate combinations of chemical and biological mechanisms also played a major role in controlling the assemblages of major taxonomic groups in prairie lakes. PMID:23186395

  7. Gradient Driven Fluctuations

    NASA Technical Reports Server (NTRS)

    Cannell, David

    2005-01-01

    We have worked with our collaborators at the University of Milan (Professor Marzio Giglio and his group-supported by ASI) to define the science required to measure gradient driven fluctuations in the microgravity environment. Such a study would provide an accurate test of the extent to which the theory of fluctuating hydrodynamics can be used to predict the properties of fluids maintained in a stressed, non-equilibrium state. As mentioned above, the results should also provide direct visual insight into the behavior of a variety of fluid systems containing gradients or interfaces, when placed in the microgravity environment. With support from the current grant, we have identified three key systems for detailed investigation. These three systems are: 1) A single-component fluid to be studied in the presence of a temperature gradient; 2) A mixture of two organic liquids to be studied both in the presence of a temperature gradient, which induces a steady-state concentration gradient, and with the temperature gradient removed, but while the concentration gradient is dying by means of diffusion; 3) Various pairs of liquids undergoing free diffusion, including a proteidbuffer solution and pairs of mixtures having different concentrations, to allow us to vary the differences in fluid properties in a controlled manner.

  8. Seasonal variation of methane flux from coastal saline rice field with the application of different organic manures

    NASA Astrophysics Data System (ADS)

    Datta, A.; Yeluripati, Jagadeesh B.; Nayak, D. R.; Mahata, K. R.; Santra, S. C.; Adhya, T. K.

    2013-02-01

    A field experiment was conducted in an irrigated saline rice field of Gadakujang (a fishing hamlet of coastal Odisha, India, ravaged by the super cyclone of 1999 and cyclone BOB02 of 2006), to study the effects of locally available organic and fresh green manure amendment to the saline soil on methane (CH4) emission during wet and dry seasons using the conventional closed chamber flux measurement method. In a first report of this kind, CH4 emission vis-à-vis yield improvement of rice with different locally available organic manure application from coastal saline rice field soil of Odisha, is reported. The study confirms that CH4 flux from the saline soil planted to rice is significantly lower than that of irrigated inland non-saline rice field during both wet and dry seasons. Cumulative seasonal CH4 flux from different treatments of the coastal saline rice field ranged between 119.51 and 263.60 kg ha-1 during the wet season and 15.35-100.88 kg ha-1 during the dry season. Lower CH4 emission during the dry season may be attributed to the increased soil salinity (EC1:2) that went up from 0.76 dS m-1 during the wet season to 3.96 dS m-1 during the dry season. Annual CH4 emission per Mg grain yield was significantly low from plots treated with locally available green manure Morning glory (Ipomoea lacunosa) (17.27) with significantly high rice grain yield. Study indicates that Morning glory may be used as a potential green manure to increase grain yield and reduced CH4 emission from the coastal saline rice ecosystems of the tropics.

  9. Surface structure determines dynamic wetting

    PubMed Central

    Wang, Jiayu; Do-Quang, Minh; Cannon, James J.; Yue, Feng; Suzuki, Yuji; Amberg, Gustav; Shiomi, Junichiro

    2015-01-01

    Liquid wetting of a surface is omnipresent in nature and the advance of micro-fabrication and assembly techniques in recent years offers increasing ability to control this phenomenon. Here, we identify how surface roughness influences the initial dynamic spreading of a partially wetting droplet by studying the spreading on a solid substrate patterned with microstructures just a few micrometers in size. We reveal that the roughness influence can be quantified in terms of a line friction coefficient for the energy dissipation rate at the contact line, and that this can be described in a simple formula in terms of the geometrical parameters of the roughness and the line-friction coefficient of the planar surface. We further identify a criterion to predict if the spreading will be controlled by this surface roughness or by liquid inertia. Our results point to the possibility of selectively controlling the wetting behavior by engineering the surface structure. PMID:25683872

  10. Wetting phenomena on rough substrates

    NASA Astrophysics Data System (ADS)

    Li, Hao; Kardar, Mehran

    1990-10-01

    We consider wetting phenomena in the vicinity of rough substrates. The quenched random geometry of the substrate is assumed to be a self-affine fractal with a roughness exponent of ζS. Asymptotic critical properties on approaching complete and critical wetting transitions are studied by combining the replica method with scaling and renormalization-group arguments. We find new critical behavior, controlled by a zero-temperature fixed point, when ζS exceeds the thermal roughness exponent of the emerging wetting layer. The possibility of an effective dimensional reduction due to randomness is considered. In two dimensions a number of exact results are obtained by using a many-body transfer-matrix technique.

  11. Using growth-based methods to determine direct effects of salinity on soil microbial communities

    NASA Astrophysics Data System (ADS)

    Rath, Kristin; Rousk, Johannes

    2015-04-01

    Soil salinization is a widespread agricultural problem and increasing salt concentrations in soils have been found to be correlated with decreased microbial activity. A central challenge in microbial ecology is to link environmental factors, such as salinity, to responses in the soil microbial community. That is, it can be difficult to distinguish direct from indirect effects. In order to determine direct salinity effects on the community we employed the ecotoxicological concept of Pollution-Induced Community Tolerance (PICT). This concept is built on the assumption that if salinity had an ecologically relevant effect on the community, it should have selected for more tolerant species and strains, resulting in an overall higher community tolerance to salt in communities from saline soils. Growth-based measures, such as the 3H-leucine incorporation into bacterial protein , provide sensitive tools to estimate community tolerance. They can also provide high temporal resolution in tracking changes in tolerance over time. In our study we used growth-based methods to investigate: i) at what levels of salt exposure and over which time scales salt tolerance can be induced in a non-saline soil, and (ii) if communities from high salinity sites have higher tolerance to salt exposure along natural salinity gradients. In the first part of the study, we exposed a non-saline soil to a range of salinities and monitored the development of community tolerance over time. We found that community tolerance to intermediate salinities up to around 30 mg NaCl per g soil can be induced at relatively short time scales of a few days, providing evidence that microbial communities can adapt rapidly to changes in environmental conditions. In the second part of the study we used soil samples originating from natural salinity gradients encompassing a wide range of salinity levels, with electrical conductivities ranging from 0.1 dS/m to >10 dS/m. We assessed community tolerance to salt by

  12. Squeezing wetting and nonwetting liquids.

    PubMed

    Samoilov, V N; Persson, B N J

    2004-01-22

    We present molecular-dynamics results for the squeezing of octane (C8H18) between two approaching solid elastic walls with different wetting properties. The interaction energy between the octane bead units and the solid walls is varied from a very small value (1 meV), corresponding to a nonwetting surface with a very large contact angle (nearly 180 degrees), to a high value (18.6 meV) corresponding to complete wetting. When at least one of the solid walls is wetted by octane we observe well defined molecular layers develop in the lubricant film when the thickness of the film is of the order of a few atomic diameters. An external squeezing-pressure induces discontinuous, thermally activated changes in the number n of lubricant layers (n-->n-1 layering transitions). With increasing interaction energy between the octane bead units and the solid walls, the transitions from n to n-1 layers occur at higher average pressure. This results from the increasing activation barrier to nucleate the squeeze-out with increasing lubricant-wall binding energy (per unit surface area) in the contact zone. Thus, strongly wetting lubricant fluids are better boundary lubricants than the less wetting ones, and this should result in less wear. We analyze in detail the effect of capillary bridge formation (in the wetting case) and droplets formation (in the nonwetting case) on the forces exerted by the lubricant on the walls. For the latter case small liquid droplets may be trapped at the interface, resulting in a repulsive force between the walls during squeezing, until the solid walls come into direct contact, where the wall-wall interaction may be initially attractive. This effect is made use of in some practical applications, and we give one illustration involving conditioners for hair care application. PMID:15268334

  13. Squeezing wetting and nonwetting liquids

    NASA Astrophysics Data System (ADS)

    Samoilov, V. N.; Persson, B. N. J.

    2004-01-01

    We present molecular-dynamics results for the squeezing of octane (C8H18) between two approaching solid elastic walls with different wetting properties. The interaction energy between the octane bead units and the solid walls is varied from a very small value (1 meV), corresponding to a nonwetting surface with a very large contact angle (nearly 180 degrees), to a high value (18.6 meV) corresponding to complete wetting. When at least one of the solid walls is wetted by octane we observe well defined molecular layers develop in the lubricant film when the thickness of the film is of the order of a few atomic diameters. An external squeezing-pressure induces discontinuous, thermally activated changes in the number n of lubricant layers (n→n-1 layering transitions). With increasing interaction energy between the octane bead units and the solid walls, the transitions from n to n-1 layers occur at higher average pressure. This results from the increasing activation barrier to nucleate the squeeze-out with increasing lubricant-wall binding energy (per unit surface area) in the contact zone. Thus, strongly wetting lubricant fluids are better boundary lubricants than the less wetting ones, and this should result in less wear. We analyze in detail the effect of capillary bridge formation (in the wetting case) and droplets formation (in the nonwetting case) on the forces exerted by the lubricant on the walls. For the latter case small liquid droplets may be trapped at the interface, resulting in a repulsive force between the walls during squeezing, until the solid walls come into direct contact, where the wall-wall interaction may be initially attractive. This effect is made use of in some practical applications, and we give one illustration involving conditioners for hair care application.

  14. Precipitation chemistry and wet deposition in a remote wet savanna site in West Africa: Djougou (Benin)

    NASA Astrophysics Data System (ADS)

    Akpo, A. B.; Galy-Lacaux, C.; Laouali, D.; Delon, C.; Liousse, C.; Adon, M.; Gardrat, E.; Mariscal, A.; Darakpa, C.

    2015-08-01

    , biomass burning and biofuel combustions. The second highest contribution is the calcium ion (13.3 μeq·L-1), characteristic of dust aerosols from terrigenous sources, Calcium contributes up to 46% of the precipitation chemistry in Djougou. Finally, these results are compared to those obtained for other selected African sites representative of other main natural ecosystems: dry savanna and forest. The study of the African ecosystem transect indicates a pH gradient with more acidic pH in the forested ecosystem. Nitrogenous contribution to the chemical composition of rain in Lamto, wet savanna, (24%) is equivalent to the one estimated in Djougou (24%). The last contribution concerns organic acidity, which represents 7% of total ionic content of precipitation at Djougou. The relative particulate contribution PC and the relative gaseous contribution GC are calculated using the mean chemical composition measured in Djougou for the studied period. The comparison with other African sites gives 40% and 43% PC in wet savannas of Lamto (Côte d'Ivoire) and Djougou (Benin) respectively, 20% PC in the equatorial forest of Zoetele (Cameroon) and 80% PC in dry savanna of Banizoumbou (Niger). The results shown here indicate the existence of a North-South gradients of organic, marine, terrigenous and nitrogenous contributions along the transect in West and Central Africa.

  15. Salinization alters fluxes of bioreactive elements from stream ecosystems across land use

    NASA Astrophysics Data System (ADS)

    Duan, S.; Kaushal, S. S.

    2015-12-01

    There has been increased salinization of fresh water over decades due to the use of road salt deicers, wastewater discharges, saltwater intrusion, human-accelerated weathering, and groundwater irrigation. Salinization can mobilize bioreactive elements (carbon, nitrogen, phosphorus, sulfur) chemically via ion exchange and/or biologically via influencing of microbial activity. However, the effects of salinization on coupled biogeochemical cycles are still not well understood. We investigated potential impacts of increased salinization on fluxes of bioreactive elements from stream ecosystems (sediments and riparian soils) to overlying stream water and evaluated the implications of percent urban land use on salinization effects. Two-day incubations of sediments and soils with stream and deionized water across three salt levels were conducted at eight routine monitoring stations across a land-use gradient at the Baltimore Ecosystem Study Long-Term Ecological Research (LTER) site in the Chesapeake Bay watershed. Results indicated (1) salinization typically increased sediment releases of labile dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), total dissolved Kjeldahl nitrogen (TKN) (ammonium + ammonia + dissolved organic nitrogen), and sediment transformations of nitrate; (2) salinization generally decreased DOC aromaticity and fluxes of soluble reactive phosphorus from both sediments and soils; (3) the effects of increased salinization on sediment releases of DOC and TKN and DOC quality increased with percentage watershed urbanization. Biogeochemical responses to salinization varied between sediments and riparian soils in releases of DOC and DIC, and nitrate transformations. The differential responses of riparian soils and sediments to increased salinization were likely due to differences in organic matter sources and composition. Our results suggest that short-term increases in salinization can cause releases of significant amounts of labile organic

  16. To wet or not to wet? Dispersion forces tip the balance for water ice on metals

    NASA Astrophysics Data System (ADS)

    Carrasco, Javier; Santra, Biswajit; Klimes, Jiri; Michaelides, Angelos

    2012-02-01

    For almost 30 years now, density functional theory (DFT) has been used to explore the molecular level details of water-metal interfaces. However, since the typical generalized gradient approximation exchange-correlation functionals used in these studies do not account for van der Waals (vdW) dispersion forces, the role dispersion plays in water adsorption remains unclear. Here, we tackle this issue head on applying a newly developed non-local functional [J. Klimes et al., J. Phys.: Condens. Matter 22, 022201 (2010)] to two of the most widely studied water-ice adsorption systems, namely water on Cu(110) and Ru(0001). We show that non-local correlations contribute substantially to the water-metal bond and that this is an important factor in governing the relative stabilities of wetting layers and 3D bulk ice [J. Carrasco et al., Phys. Rev. Lett. 106, 026101 (2011)]. Due to the greater polarizability of the substrate metal atoms, non-local correlations between water and the metal exceed those between water within ice. This sheds light on a long-standing problem, wherein common DFT exchange-correlation functionals incorrectly predict that none of the low temperature experimentally characterized ice-like wetting layers are thermodynamically stable.

  17. Capillary Trapping of CO2 in Oil Reservoirs: Observations in a Mixed-Wet Carbonate Rock.

    PubMed

    Al-Menhali, Ali S; Krevor, Samuel

    2016-03-01

    Early deployment of carbon dioxide storage is likely to focus on injection into mature oil reservoirs, most of which occur in carbonate rock units. Observations and modeling have shown how capillary trapping leads to the immobilization of CO2 in saline aquifers, enhancing the security and capacity of storage. There are, however, no observations of trapping in rocks with a mixed-wet-state characteristic of hydrocarbon-bearing carbonate reservoirs. Here, we found that residual trapping of supercritical CO2 in a limestone altered to a mixed-wet state with oil was significantly less than trapping in the unaltered rock. In unaltered samples, the trapping of CO2 and N2 were indistinguishable, with a maximum residual saturation of 24%. After the alteration of the wetting state, the trapping of N2 was reduced, with a maximum residual saturation of 19%. The trapping of CO2 was reduced even further, with a maximum residual saturation of 15%. Best-fit Land-model constants shifted from C = 1.73 in the water-wet rock to C = 2.82 for N2 and C = 4.11 for the CO2 in the mixed-wet rock. The results indicate that plume migration will be less constrained by capillary trapping for CO2 storage projects using oil fields compared with those for saline aquifers. PMID:26812184

  18. Laser textured surface gradients

    NASA Astrophysics Data System (ADS)

    Ta, Van Duong; Dunn, Andrew; Wasley, Thomas J.; Li, Ji; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Esenturk, Emre; Connaughton, Colm; Shephard, Jonathan D.

    2016-05-01

    This work demonstrates a novel technique for fabricating surfaces with roughness and wettability gradients and their subsequent applications for chemical sensors. Surface roughness gradients on brass sheets are obtained directly by nanosecond laser texturing. When these structured surfaces are exposed to air, their wettability decreases with time (up to 20 days) achieving both spatial and temporal wettability gradients. The surfaces are responsive to organic solvents. Contact angles of a series of dilute isopropanol solutions decay exponentially with concentration. In particular, a fall of 132° in contact angle is observed on a surface gradient, one order of magnitude higher than the 14° observed for the unprocessed surface, when the isopropanol concentration increased from 0 to 15.6 wt%. As the wettability changes gradually over the surface, contact angle also changes correspondingly. This effect offers multi-sensitivity at different zones on the surface and is useful for accurate measurement of chemical concentration.

  19. Performance of 115 kV fiberglass transmission crossarms in wet and salt fog environments

    SciTech Connect

    Shah, K.R.; Sarkinen, C.F.; Verma, V.

    1983-04-01

    This paper discusses 60 Hz-dielectric tests performed on 115 kV solid fiberglass transmission crossarm-insulator assemblies to evaluate their performance in wet and salt fog environments. Testing included the following variables: (1) wet and dry conditions, (2) new and used crossarms and insulators, (3) type and number of insulators, and (4) salt fog salinity. Analysis of test results shows that the surface coating of fiberglass insulation is susceptible to degradation in a salt fog environment. Once this coating is eroded and the glass fibers are exposed, carbonized tracking develops. The fiberglass crossarm thus loses its electrical strength.

  20. Effects of salinity on performance and microbial community structure of an anoxic-aerobic sequencing batch reactor.

    PubMed

    Wang, Zichao; Gao, Mengchun; Wang, Sen; Chang, Qingbo; Wang, Zhe

    2015-01-01

    The effects of salinity on the performance and microbial community structure of activated sludge were investigated in an anoxic-aerobic sequencing batch reactor (SBR). The removal efficiencies of chemical oxygen demand (COD) and [Formula: see text]-N decreased as the influent salinity increased from 0.5% to 6%. The specific oxygen utilization rate of activated sludge increased from 22.47 to 43.16 mg O2 g(-1) mixed liquid suspended solids (MLSS) h(-1) with the increase in salinity from 0.5% to 4% and subsequently decreased to 18.3 mg O2 g(-1) MLSS h(-1) at 6% salinity. The specific ammonium oxidation rate (SAOR) and specific nitrite oxidation rate (SNOR) decreased slowly at 0.5-1% salinity and then decreased rapidly with the increase in salinity from 1% to 6%. The SNOR diminished at a faster rate than the SAOR with the increase in salinity from 0.5% to 6%. The specific nitrate reduction rate (SNRR) decreased with the increase in salinity, whereas the SNRR was higher than the sum of SAOR and SNOR at 0.5-6% salinity. The denaturing gradient gel electrophoresis profiles revealed obvious changes in microbial community structure at different salinities. Some microbes were capable of tolerating up to 6% salinity in the SBR, such as Planomonospora sphaerica, Nitrosomonas sp. Is32, and Denitromonas sp. D2-1. PMID:25686658

  1. Inhibiting Wet Oxidation of Ammonia

    NASA Technical Reports Server (NTRS)

    Onisko, D. B. L.

    1985-01-01

    Simple modification of wet-oxidation process for treating organicwaste reduces loss of fixed nitrogen, potentially valuable byproduct of process. Addition of sufficient sulfuric acid to maintain reaction pH below 3 greatly reduces oxidation of ammonia to free nitrogen. No equipment modification required.

  2. Solidification of underwater wet welds

    SciTech Connect

    Pope, A.M.; Medeiros, R.C. de; Liu, S.

    1995-12-31

    It is well known that the shape of a weld pool can influence the microstructure and segregation pattern of the final solidified weld metal. Mechanical properties and susceptibility to defects are consequently affected by the solidification mode of the weld. In this work the solidification behavior of weld beads deposited in air and underwater wet welding using rutile electrodes were compared. The welds were deposited by gravity feed, on low carbon, manganese steel plates using similar welding conditions. Macroscopic observation of the weld craters showed that welds deposited in air presented an elliptical weld pool. The underwater wet welds, on the other hand, solidified with a tear drop shape. Although the welds differed in shape, their lengths were approximately the same. Microscopic examinations carried out on transverse, normal and longitudinal sections revealed a coarser columnar grain structure in the underwater welds. These results suggest that the tear-drop shaped pool induced solidification in a preferred orientation with segregation more likely in welds deposited under wet conditions. This change in weld pool geometry can be explained by the surface heat loss conditions that occur in a wet weld: slower when covered by the steam bubble and faster in the region in contact with water behind the pool.

  3. Alfalfa production using saline drainage water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A three year study investigated the use of saline (< 6 dS/m) drainage water for irrigation of salt tolerant alfalfa in the presence of shallow saline groundwater. The irrigation treatments included; irrigating twice between cuttings with non-saline water, 2) irrigating with moderately saline water...

  4. Prokaryotic Community Structure Driven by Salinity and Ionic Concentrations in Plateau Lakes of the Tibetan Plateau

    PubMed Central

    Zhong, Zhi-Ping; Liu, Ying; Miao, Li-Li; Wang, Fang; Chu, Li-Min; Wang, Jia-Li

    2016-01-01

    The prokaryotic community composition and diversity and the distribution patterns at various taxonomic levels across gradients of salinity and physiochemical properties in the surface waters of seven plateau lakes in the Qaidam Basin, Tibetan Plateau, were evaluated using Illumina MiSeq sequencing. These lakes included Lakes Keluke (salinity, <1 g/liter), Qing (salinity, 5.5 to 6.6 g/liter), Tuosu (salinity, 24 to 35 g/liter), Dasugan (salinity, 30 to 33 g/liter), Gahai (salinity, 92 to 96 g/liter), Xiaochaidan (salinity, 94 to 99 g/liter), and Gasikule (salinity, 317 to 344 g/liter). The communities were dominated by Bacteria in lakes with salinities of <100 g/liter and by Archaea in Lake Gasikule. The clades At12OctB3 and Salinibacter, previously reported only in hypersaline environments, were found in a hyposaline lake (salinity, 5.5 to 6.6 g/liter) at an abundance of ∼1.0%, indicating their ecological plasticity. Salinity and the concentrations of the chemical ions whose concentrations covary with salinity (Mg2+, K+, Cl−, Na+, SO42−, and Ca2+) were found to be the primary environmental factors that directly or indirectly determined the composition and diversity at the level of individual clades as well as entire prokaryotic communities. The distribution patterns of two phyla, five classes, five orders, five families, and three genera were well predicted by salinity. The variation of the prokaryotic community structure also significantly correlated with the dissolved oxygen concentration, pH, the total nitrogen concentration, and the PO43− concentration. Such correlations varied depending on the taxonomic level, demonstrating the importance of comprehensive correlation analyses at various taxonomic levels in evaluating the effects of environmental variable factors on prokaryotic community structures. Our findings clarify the distribution patterns of the prokaryotic community composition in plateau lakes at the levels of individual clades as well as whole

  5. Prokaryotic Community Structure Driven by Salinity and Ionic Concentrations in Plateau Lakes of the Tibetan Plateau.

    PubMed

    Zhong, Zhi-Ping; Liu, Ying; Miao, Li-Li; Wang, Fang; Chu, Li-Min; Wang, Jia-Li; Liu, Zhi-Pei

    2016-03-01

    The prokaryotic community composition and diversity and the distribution patterns at various taxonomic levels across gradients of salinity and physiochemical properties in the surface waters of seven plateau lakes in the Qaidam Basin, Tibetan Plateau, were evaluated using Illumina MiSeq sequencing. These lakes included Lakes Keluke (salinity, <1 g/liter), Qing (salinity, 5.5 to 6.6 g/liter), Tuosu (salinity, 24 to 35 g/liter), Dasugan (salinity, 30 to 33 g/liter), Gahai (salinity, 92 to 96 g/liter), Xiaochaidan (salinity, 94 to 99 g/liter), and Gasikule (salinity, 317 to 344 g/liter). The communities were dominated by Bacteria in lakes with salinities of <100 g/liter and by Archaea in Lake Gasikule. The clades At12OctB3 and Salinibacter, previously reported only in hypersaline environments, were found in a hyposaline lake (salinity, 5.5 to 6.6 g/liter) at an abundance of ∼1.0%, indicating their ecological plasticity. Salinity and the concentrations of the chemical ions whose concentrations covary with salinity (Mg(2+), K(+), Cl(-), Na(+), SO4 (2-), and Ca(2+)) were found to be the primary environmental factors that directly or indirectly determined the composition and diversity at the level of individual clades as well as entire prokaryotic communities. The distribution patterns of two phyla, five classes, five orders, five families, and three genera were well predicted by salinity. The variation of the prokaryotic community structure also significantly correlated with the dissolved oxygen concentration, pH, the total nitrogen concentration, and the PO4 (3-) concentration. Such correlations varied depending on the taxonomic level, demonstrating the importance of comprehensive correlation analyses at various taxonomic levels in evaluating the effects of environmental variable factors on prokaryotic community structures. Our findings clarify the distribution patterns of the prokaryotic community composition in plateau lakes at the levels of individual clades as

  6. Salinization Enhances Mobilization of Nutrients from Sediments to Streams

    NASA Astrophysics Data System (ADS)

    Haq, S.; Kaushal, S.; Hohman, S.; Coplin, J.; Duan, S.

    2015-12-01

    Many regions of the U.S. and elsewhere are experiencing increased salinization of freshwater due to the widespread application of road salts. Increased salinization has the potential to release stored nutrients from sediments, decrease biodiversity, and perturb water quality. We conducted laboratory experiments to investigate the potential effects of road salt (NaCl) on nutrient mobilization from sediments to stream water. Sediments and stream water were incubated from 2 urbanizing watersheds of the Chesapeake Bay in the Baltimore-Washington Metropolitan area. Stream sediment was incubated from 11 routinely monitored streams exhibiting a land use gradient within the Baltimore Ecosystem Study Long-Term Ecological Research (BES LTER) site and Anacostia River watershed. Our results indicate that salinization increased the release of soluble reactive phosphorus and total dissolved nitrogen at all sites. The release of dissolved organic carbon and dissolved inorganic carbon varied between sites, and these differential responses may be due to: stream sediment composition, organic matter content, and ambient water quality. The magnitude and frequency of road salt application may be amplified in the near future due to the interactive effects of climate variability and urbanization, and our research suggests this can have water quality and ecological implications for freshwater ecosystems. Further research is necessary to elucidate driving mechanisms of changes in sediment biogeochemical cycles in response to salinization and the temporal response of freshwater ecosystems.

  7. In situ determination of salinity by PGNAA.

    PubMed

    Borsaru, M; Smith, C; Merritt, J; Aizawa, T; Rojc, A

    2006-05-01

    Salinity is a very important environmental issue all around the world. In many cases salinity was produced from human activities like farming and mining. Different soluble salts contribute to salinity, however, NaCl is the most common salt producing salinity. This work deals with the application of the prompt gamma neutron activation analysis (PGNAA) technique for in situ determination of salinity. The technique is based on the measurement of chlorine, a component of the common salt, by PGNAA. PMID:16448819

  8. Soil salinity and sodicity in a shrimp farming coastal area of the Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Tho, Nguyen; Vromant, N.; Hung, Nguyen Thanh; Hens, L.

    2008-06-01

    Soil salinity and sodicity are environmental problems in the shrimp farming areas of the Cai Nuoc district, Ca Mau province, Vietnam. In 2000, farmers in the district switched en masse from rice cropping to shrimp culture. Due to recent failure in shrimp farming, many farmers wish to revert to a rotational system with rice in the wet season and shrimps in the dry season. So far, all their attempts to grow rice have failed. To assess soil salinity and sodicity, 25 boreholes in shrimp ponds were analysed in four consecutive seasons from 2002 to 2004. The results showed that soil salinity was quite serious (mean ECe 29.25 dS m-1), particularly in the dry season (mean ECe 33.44 dS m-1). In the wet season, significant amounts of salts still remained in the soil (mean ECe 24.65 dS m-1) and the highest soil salinity levels were found near the sea. Soil sodicity is also a problem in the district (exchangeable sodium percentage range 9.63-72.07%). Sodicity is mainly a phenomenon of topsoils and of soils near the sea. Both soil salinity and sodicity are regulated by seasonal rainfall patterns. They could together result in disastrous soil degradation in the Cai Nuoc district.

  9. Long Term Surface Salinity Measurements

    NASA Technical Reports Server (NTRS)

    Schmitt, Raymond W.; Brown, Neil L.

    2005-01-01

    Our long-term goal is to establish a reliable system for monitoring surface salinity around the global ocean. Salinity is a strong indicator of the freshwater cycle and has a great influence on upper ocean stratification. Global salinity measurements have potential to improve climate forecasts if an observation system can be developed. This project is developing a new internal field conductivity cell that can be protected from biological fouling for two years. Combined with a temperature sensor, this foul-proof cell can be deployed widely on surface drifters. A reliable in-situ network of surface salinity sensors will be an important adjunct to the salinity sensing satellite AQUARIUS to be deployed by NASA in 2009. A new internal-field conductivity cell has been developed by N Brown, along with new electronics. This sensor system has been combined with a temperature sensor to make a conductivity - temperature (UT) sensor suitable for deployment on drifters. The basic sensor concepts have been proven on a high resolution CTD. A simpler (lower cost) circuit has been built for this application. A protection mechanism for the conductivity cell that includes antifouling protection has also been designed and built. Mr. A.Walsh of our commercial partner E-Paint has designed and delivered time-release formulations of antifoulants for our application. Mr. G. Williams of partner Clearwater Instrumentation advised on power and communication issues and supplied surface drifters for testing.

  10. An investigation of thermocapillary effects on the wetting characteristics of a heated, capillary re-supplied, curved meniscus within a capillary pore

    SciTech Connect

    Pratt, D.M.; Hallinan, K.P.

    1996-12-31

    An investigation of thermocapillary effects on a heated, evaporating meniscus formed by a wetting liquid in a vertical capillary tube has been completed. Experiments were conducted to primarily observe how the wetting characteristics of the working fluid (pentane) are affected by the dynamics associated with the heating of and evaporation from a meniscus. The results have demonstrated that interfacial thermocapillary stresses arising from liquid-vapor interfacial temperature gradients can noticeably degrade the ability of the liquid to wet the pore.

  11. Natural and management influences on freshwater inflows and salinity in the San Francisco Estuary at monthly to interannual scales

    USGS Publications Warehouse

    Knowles, Noah

    2002-01-01

    Understanding the processes controlling the physics, chemistry, and biology of the San Francisco Estuary and their relation to climate variability is complicated by the combined influence on freshwater inflows of natural variability and upstream management. To distinguish these influences, alterations of estuarine inflow due to major reservoirs and freshwater pumping in the watershed were inferred from available data. Effects on salinity were estimated by using reconstructed estuarine inflows corresponding to differing levels of impairment to drive a numerical salinity model. Both natural and management inflow and salinity signals show strong interannual variability. Management effects raise salinities during the wet season, with maximum influence in spring. While year-to-year variations in all signals are very large, natural interannual variability can greatly exceed the range of management effects on salinity in the estuary.

  12. Ozone measurements in Amazonia: Dry season versus wet season

    SciTech Connect

    Kirchhoff, V.W.J.H. ); Da Silva, I.M.O. ); Browell, E.V. )

    1990-09-20

    Observations were made almost continuously at the surface, and in addition, 20 ozone profiles were obtained in the troposphere and stratosphere. These ozone measurements were part of a field expedition to the Brazilian Amazon region, the ABLE 2B mission, a joint American-Brazilian effort to measure local concentrations of several species relevant to atmospheric chemistry. The time period of this expedition was April-May 1987, during the local wet season. For the surface ozone data the measurement technique sued was UV absorption. Ozone profiles were obtained with electrochemical concentration cell sondes, launched on balloons. The major site of operation was set up near Manaus (3{degree}S, 60{degree}W). The results are presented and compared with a previous dry season experiment. Surface ozone mixing ratios show diurnal variations that have maxima in the daytime and minima at night. The diurnal maximum at noontime, considered very low (12 ppbv) in the dry season was even lower in this wet season period (6 ppbv). A significant difference can be seen between clearing and forest data, and between different height levels above the surface, showing the existence of a large positive gradient of ozone with height. The ozone profiles in the troposphere show that there is less ozone not only at the surface but in the whole troposphere, with the wet season average showing between 6 and 12 ppbv less ozone. This difference is much smaller in the stratosphere, where there is slightly more ozone in the region of the peak, during the wet season. An isolated shower or thunderstorm in the dry season could produce transient ozone variations (mixing ratio increases or decreases) that were not observed in the wet season.

  13. Amazon basin ozone and aerosol: Wet season observations

    SciTech Connect

    Gregory, G.L.; Browell, E.V.; Warren, L.S.; Hudgins, C.H. )

    1990-09-20

    The tropical environment is recognized as having a major impact on global tropospheric chemistry. The data show that the wet season Amazon Basin is an effective sink for ozone and a net source for aerosols. Mixed layer ozone at 150-m altitude averaged 8.5 ppbv compared to about 18 ppbv at 3-km altitude. In addition, a negative ozone gradient (decreasing value to the surface) was observed within the mixed layer. The averaged wet season mixed layer ozone was about 7 ppbv lower than observed during the dry season. This is attributed to the enhanced convective activity associated with the wet season and the change in mixed layer photochemistry from net ozone production (dry season) to a net destruction (wet season). The net sink characteristics of the wet season mixed layer are seen throughout the troposphere of the Amazon Basin in that ozone (3- to 4-km altitude) is typically 15-25 ppbv as compared to dry season values of 30-35 ppbv. In terms of the aerosol source characteristics of the Amazon Basin, mixed layer aerosols (0.1- to 0.4-{mu}m diameter) are a factor of 5-10 higher than observed in the troposphere with mixed layer values of 100-200 aerosols/cm{sup 3}. Analyses of both tropospheric and mixed layer aerosol samples show aerosols which are multisource. Tropospheric samples have size distributions which are trimodal and show modes at aerosol diameters which suggest the aerosols are (1) of lifetimes <1 hour, (2) of lifetimes of days, and (3) mechanically generated elements (e.g., wind-blow dust). Mixed layer data show two of the three modes with no mode which represent aerosols with lifetimes of days.

  14. Wetting dynamics of thin liquid films and drops under Marangoni and centrifugal forces.

    PubMed

    Mukhopadhyay, Shomeek; Behringer, Robert P

    2009-11-18

    This paper presents an experimental study on thin liquid drops and films under the combined action of centrifugal forces due to rotation and radial Marangoni forces due to a corresponding temperature gradient. We shall examine thinning of a given liquid layer both with and without rotation and also consider the onset of the fingering instability in a completely wetting liquid drop. In many of the experiments described here, we use an interferometric technique which provides key information on height profiles. For thick rotating films in the absence of a temperature gradient, when an initially thick layer of fluid is spun to angular velocities where the classical Newtonian solution is negative, the fluid never dewets for the case of a completely wetting fluid, but leaves a microscopic uniform wet layer in the center. Similar experiments with a radially inward temperature gradient reveal the evolution of a radial height profile given by h(r) = A(t)r(α), where A(t) decays logarithmically with time, and [Formula: see text]. In the case where there is no rotation, small centrally placed drops show novel retraction behavior under a sufficiently strong temperature gradient. Using the same interferometric arrangement, we observed the onset of the fingering instability of small drops placed at the center of the rotating substrate in the absence of a temperature gradient. At the onset of the instability, the height profile for small drops is more complex than previously assumed. PMID:21715887

  15. Salinity's Role in Tropical Atlantic Instability Waves: new knowledge from salinity remote sensing

    NASA Astrophysics Data System (ADS)

    (Tony) Lee, Tong; Lagerloef, Gary; Kao, Hsun-Ying; McPhaden, Michael; Willis, Joshua; Gierach, Michelle

    2014-05-01

    Tropical Atlantic instability waves (TIWs) play important roles in the dynamics of the tropical Atlantic Ocean and related climate variability. Previous studies based on satellite-derived sea surface temperature (SST) data and mooring observations suggest that these waves are the most energetic in the eastern equatorial Atlantic and during late (boreal) spring and early summer. Satellite remote sensing of sea surface salinity (SSS) from SMOS and Aquarius provides a unique vantage point to identify new features of these waves in terms of zonal and seasonal variability. Aquarius SSS data reveal that the TIWs remain energetic in the western equatorial Atlantic despite a much weaker SST signature. Surface perturbation potential energy (PPE), the source of the downward potential energy propagation associated with the TIWs, has a larger contribution by SST (than by SSS) in the east but is primarily due to SSS in the west. The co-variability between SSS and SST also has significant contribution to surface PPE across the basin. While surface PPE is large in late spring and early summer in the east, it is also large during late summer and early fall in the west. The latter is associated with the retroflection of the North Brazil Current into the North Equatorial Countercurrent in the west during these times, carrying with it the fresh water from the Amazon River outflow to set up a large meridional salinity (and thus density) gradient.

  16. Temperature, salinity, and density variability in the central Middle Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Castelao, Renato; Glenn, Scott; Schofield, Oscar

    2010-10-01

    Four years of sustained glider observations are used to compute the seasonal cycle of hydrographic fields in the central Middle Atlantic Bight (MAB). Results reveal a large phase lag in near bottom temperatures, with peak values occurring in September at the inner shelf, in October at the mid shelf, and in November at the outer shelf. Unlike the northern MAB, the seasonal cycle explains over 70% of the near-surface salinity variability. At the inner shelf and offshore near the bottom, however, most of the variance is due to pulses in river discharge and to shifts in the position of the shelfbreak front. Cross-shelf density gradients inshore of the 60-m isobath are dominated by salinity during winter and spring, with temperature contributing significantly from August to October. This is because bottom waters near the coast are warm due to the deepening of the thermocline during fall, but offshore waters are still influenced by the cold pool. The vertical stratification seasonal variability is also large. Early in the year, stratification is small and entirely due to salinity. By May, salinity still dominates vertical gradients near the coast, but temperature and salinity contribute equally to the density stratification offshore. During summer, stratification is dominated by temperature. Temperature interannual variability was small during the sampling period, but surface salinity was anomalously low by 1.2 psu in summer 2006. The anomaly was due to larger than average discharge from the Hudson River in early summer during a period of strong upwelling favorable winds.

  17. Gradient enhanced spectroscopy

    NASA Astrophysics Data System (ADS)

    van Zijl, Peter C.; Hurd, Ralph E.

    2011-12-01

    This paper provides a brief overview of the personal recollections of the authors regarding their contributions to the introduction of shielded gradient technology into NMR spectroscopy during the late 1980s and early 1990s. It provides some background into early probe design and details some of the early technical progress with the use of shielded magnetic field gradients for coherence selection in high resolution NMR and describes the developments at General Electric, the National Institutes of Health, Georgetown University and Johns Hopkins University School of Medicine that ultimately led to this technology becoming commonplace in modern NMR spectroscopy. Most of this early technical work was published in the Journal of Magnetic Resonance.

  18. High gradient superconducting quadrupoles

    SciTech Connect

    Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

    1987-07-01

    Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed.

  19. HIGH GRADIENT INDUCTION ACCELERATOR

    SciTech Connect

    Caporaso, G J; Sampayan, S; Chen, Y; Blackfield, D; Harris, J; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Nunnally, W; Paul, A; Poole, B; Rhodes, M; Sanders, D; Selenes, K; Sullivan, J; Wang, L; Watson, J

    2007-06-21

    A new type of compact induction accelerator is under development at the Lawrence Livermore National Laboratory that promises to increase the average accelerating gradient by at least an order of magnitude over that of existing induction machines. The machine is based on the use of high gradient vacuum insulators, advanced dielectric materials and switches and is stimulated by the desire for compact flash x-ray radiography sources. Research describing an extreme variant of this technology aimed at proton therapy for cancer will be described. Progress in applying this technology to several applications will be reviewed.

  20. Gradient tabu search.

    PubMed

    Stepanenko, Svetlana; Engels, Bernd

    2007-01-30

    This paper presents a modification of the tabu search called gradient tabu search (GTS). It uses analytical gradients for a fast minimization to the next local minimum and analytical diagonal elements of the Hessian to escape local minima. For an efficient blocking of already visited areas tabu regions and tabu directions are introduced into the tabu list (TL). Trials with various well-known test functions indicate that the GTS is a very promising approach to determine local and global minima of differentiable functions. Possible application areas could be optimization routines for force field parameters or conformational searches for large molecules. PMID:17186482

  1. Alkali burns from wet cement.

    PubMed Central

    Peters, W. J.

    1984-01-01

    When water is added to the dry materials of Portland cement calcium hydroxide is formed; the wet cement is caustic (with a pH as high as 12.9) and can produce third-degree alkali burns after 2 hours of contact. Unlike professional cement workers, amateurs are usually not aware of any danger and may stand or kneel in the cement for long periods. As illustrated in a case report, general physicians may recognize neither the seriousness of the injury in its early stages nor the significance of a history of prolonged contact with wet cement. All people working with cement should be warned about its dangers and advised to immediately wash and dry the skin if contact does occur. Images Fig. 1 PMID:6561052

  2. Double diffusive natural convection in solar ponds with nonlinear temperature and salinity profiles

    SciTech Connect

    Kirkpatrick, A.T.; Gordon, R.F.; Johnson, D.H.

    1986-08-01

    A solar pond can be used as a thermal energy source provided that convective instabilities do not occur. This paper experimentally examines the stability of a fluid layer with nonlinear salinity and temperature profiles. A nonlinear salt profile was set up in a fluid layer, and the water was heated by a solar radiation simulator. Three stability experiments were conducted. Instabilities occurred at the location of the weakest salinity gradient, and were confined to a thin region, as predicted by theory. A local length scale was used to produce a stability parameter, the ratio of thermal to solute Rayleigh numbers. It is shown that for nonconstant solute and temperature gradients, the appropriate length scale is based on the radius of curvature of the salinity distribution. With this choice of a length scale, good agreement was found between theory and experiment for the onset of an instability.

  3. Surface Modifications in Adhesion and Wetting

    NASA Astrophysics Data System (ADS)

    Longley, Jonathan

    Advances in surface modification are changing the world. Changing surface properties of bulk materials with nanometer scale coatings enables inventions ranging from the familiar non-stick frying pan to advanced composite aircraft. Nanometer or monolayer coatings used to modify a surface affect the macro-scale properties of a system; for example, composite adhesive joints between the fuselage and internal frame of Boeing's 787 Dreamliner play a vital role in the structural stability of the aircraft. This dissertation focuses on a collection of surface modification techniques that are used in the areas of adhesion and wetting. Adhesive joints are rapidly replacing the familiar bolt and rivet assemblies used by the aerospace and automotive industries. This transition is fueled by the incorporation of composite materials into aircraft and high performance road vehicles. Adhesive joints have several advantages over the traditional rivet, including, significant weight reduction and efficient stress transfer between bonded materials. As fuel costs continue to rise, the weight reduction is accelerating this transition. Traditional surface pretreatments designed to improve the adhesion of polymeric materials to metallic surfaces are extremely toxic. Replacement adhesive technologies must be compatible with the environment without sacrificing adhesive performance. Silane-coupling agents have emerged as ideal surface modifications for improving composite joint strength. As these coatings are generally applied as very thin layers (<50 nm), it is challenging to characterize their material properties for correlation to adhesive performance. We circumvent this problem by estimating the elastic modulus of the silane-based coatings using the buckling instability formed between two materials of a large elastic mismatch. The elastic modulus is found to effectively predict the joint strength of an epoxy/aluminum joint that has been reinforced with silane coupling agents. This buckling

  4. Competitive Wetting in Active Brazes

    SciTech Connect

    Chandross, Michael Evan

    2014-05-01

    We found that the wetting and spreading of molten filler materials (pure Al, pure Ag, and AgAl alloys) on a Kovar ™ (001) substrate was studied with molecular dynamics simulations. A suite of different simulations was used to understand the effects on spreading rates due to alloying as well as reactions with the substrate. Moreover, the important conclusion is that the presence of Al in the alloy enhances the spreading of Ag, while the Ag inhibits the spreading of Al.

  5. Phoenix's Wet Chemistry Laboratory Units

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image shows four Wet Chemistry Laboratory units, part of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument on board NASA's Phoenix Mars Lander. This image was taken before Phoenix's launch on August 4, 2007.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  6. Wetting hysteresis induced by nanodefects.

    PubMed

    Giacomello, Alberto; Schimmele, Lothar; Dietrich, Siegfried

    2016-01-19

    Wetting of actual surfaces involves diverse hysteretic phenomena stemming from ever-present imperfections. Here, we clarify the origin of wetting hysteresis for a liquid front advancing or receding across an isolated defect of nanometric size. Various kinds of chemical and topographical nanodefects, which represent salient features of actual heterogeneous surfaces, are investigated. The most probable wetting path across surface heterogeneities is identified by combining, within an innovative approach, microscopic classical density functional theory and the string method devised for the study of rare events. The computed rugged free-energy landscape demonstrates that hysteresis emerges as a consequence of metastable pinning of the liquid front at the defects; the barriers for thermally activated defect crossing, the pinning force, and hysteresis are quantified and related to the geometry and chemistry of the defects allowing for the occurrence of nanoscopic effects. The main result of our calculations is that even weak nanoscale defects, which are difficult to characterize in generic microfluidic experiments, can be the source of a plethora of hysteretical phenomena, including the pinning of nanobubbles. PMID:26721395

  7. Wetting hysteresis induced by nanodefects

    PubMed Central

    Giacomello, Alberto; Schimmele, Lothar; Dietrich, Siegfried

    2016-01-01

    Wetting of actual surfaces involves diverse hysteretic phenomena stemming from ever-present imperfections. Here, we clarify the origin of wetting hysteresis for a liquid front advancing or receding across an isolated defect of nanometric size. Various kinds of chemical and topographical nanodefects, which represent salient features of actual heterogeneous surfaces, are investigated. The most probable wetting path across surface heterogeneities is identified by combining, within an innovative approach, microscopic classical density functional theory and the string method devised for the study of rare events. The computed rugged free-energy landscape demonstrates that hysteresis emerges as a consequence of metastable pinning of the liquid front at the defects; the barriers for thermally activated defect crossing, the pinning force, and hysteresis are quantified and related to the geometry and chemistry of the defects allowing for the occurrence of nanoscopic effects. The main result of our calculations is that even weak nanoscale defects, which are difficult to characterize in generic microfluidic experiments, can be the source of a plethora of hysteretical phenomena, including the pinning of nanobubbles. PMID:26721395

  8. Different regimes of dynamic wetting

    NASA Astrophysics Data System (ADS)

    Gustav, Amberg; Wang, Jiayu; Do-Quang, Minh; Shiomi, Junichiro; Physiochemical fluid mechanics Team; Maruyama-Chiashi Laboratory Team

    2014-11-01

    Dynamic wetting, as observed when a droplet contacts a dry solid surface, is important in various engineering processes, such as printing, coating, and lubrication. Our overall aim is to investigate if and how the detailed properties of the solid surface influence the dynamics of wetting. Here we discuss how surface roughness influences the initial dynamic spreading of a partially wetting droplet by studying the spreading on a solid substrate patterned with microstructures just a few micrometers in size. This is complemented by matching numerical simulations. We present a parameter map, based on the properties of the liquid and the solid surface, which identifies qualitatively different spreading regimes, where the spreading speed is limited by either the liquid viscosity, the surface properties, or the liquid inertia. The peculiarities of the different spreading regimes are studied by detailed numerical simulations, in conjuction with experiments. This work was financially supported in part by, the Japan Society for the Promotion of Science (J.W. and J.S) and Swedish Governmental Agency for Innovation Systems (M.D.-Q. and G.A).

  9. Inhaled antibiotics: dry or wet?

    PubMed

    Tiddens, Harm A W M; Bos, Aukje C; Mouton, Johan W; Devadason, Sunalene; Janssens, Hettie M

    2014-11-01

    Dry powder inhalers (DPIs) delivering antibiotics for the suppressive treatment of Pseudomonas aeruginosa in cystic fibrosis patients were developed recently and are now increasingly replacing time-consuming nebuliser therapy. Noninferiority studies have shown that the efficacy of inhaled tobramycin delivered by DPI was similar to that of wet nebulisation. However, there are many differences between inhaled antibiotic therapy delivered by DPI and by nebuliser. The question is whether and to what extent inhalation technique and other patient-related factors affect the efficacy of antibiotics delivered by DPI compared with nebulisers. Health professionals should be aware of the differences between dry and wet aerosols, and of patient-related factors that can influence efficacy, in order to personalise treatment, to give appropriate instructions to patients and to better understand the response to the treatment after switching. In this review, key issues of aerosol therapy are discussed in relation to inhaled antibiotic therapy with the aim of optimising the use of both nebulised and DPI antibiotics by patients. An example of these issues is the relationship between airway generation, structural lung changes and local concentrations of the inhaled antibiotics. The pros and cons of dry and wet modes of delivery for inhaled antibiotics are discussed. PMID:25323242

  10. Wet decontamination-induced stratum corneum hydration--effects on the skin barrier function to diethylmalonate.

    PubMed

    Loke, W K; U, S H; Lau, S K; Lim, J S; Tay, G S; Koh, C H

    1999-01-01

    Decontamination of chemical agents from the skin uses both dry and wet decontamination processes. Recent studies have shown that wet decontamination frequently results in stratum corneum hydration. To evaluate the hydration effect of wet decontamination on the skin barrier function and hence on the decontamination efficiency, a series of comparative studies were carried out on human skin contaminated with the nerve agent simulant diethylmalonate, using decontamination media having different salinity and surfactants. The results showed that, compared to non-decontaminated skin, remnant diethylmalonate on decontaminated skin penetrated at an accelerated rate in the immediate 2 h following decontamination. This transient enhancement effect, ranging from 20 to 98%, was depended on the nature of the decontamination media used and was more obvious in skin samples that were decontaminated 1 h postexposure. All decontamination media exhibited this effect, with the greatest enhancement observed in the following order: anionic surfactant > cationic surfactant > non-ionic surfactant > deionized water > 0.9% saline > 9% saline. PMID:10439344

  11. Freshwater prokaryote and virus communities can adapt to a controlled increase in salinity through changes in their structure and interactions

    NASA Astrophysics Data System (ADS)

    Marine, Combe; Thierry, Bouvier; Olivier, Pringault; Emma, Rochelle-Newall; Corinne, Bouvier; Martin, Agis; The Thu, Pham; Jean-Pascal, Torreton; Van Thuoc, Chu; Bettarel, Yvan

    2013-11-01

    Little information exists on the ecological adaptive responses of riverine microorganisms to the salinity changes that typically occur in transitional waters. This study examined the precise effects of a gradual increase in salinity (+3 units per day for 12 days) on freshwater virus and prokaryote communities collected in the Red River Delta (northern Vietnam). The abundance, activity, morphology and diversity of both communities were examined along this simulated salinity gradient (0-36). Three main successive ecological stages were observed: (1) a continuous decline in prokaryotic and viral abundance from the start of the salinization process up to salinity 12-15 together with a strong decrease in the proportion of active cells, (2) a shift in both community compositions (salinity 9-15) and (3) a marked prevalence of lysogenic over lytic cycles up to salinity 21 followed by a collapse of both types of viral infection. Finally, after salinity 21, and up to seawater salinities (i.e. 36) the prokaryotic community showed multiple signs of recovery with their abundance and function even reaching initial levels. These results suggest that most of the physiological and phylogenetic changes that occurred within the salinity range 10-20 seemed to favor the installation of osmotically adapted prokaryotes accompanied by a specific cortege of viral parasites which might both be able to survive and even proliferate in saltwater conditions.

  12. 49 CFR 173.159 - Batteries, wet.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Batteries, wet. 173.159 Section 173.159... Batteries, wet. (a) Electric storage batteries, containing electrolyte acid or alkaline corrosive battery fluid (wet batteries), may not be packed with other materials except as provided in paragraphs (g)...

  13. 49 CFR 173.159 - Batteries, wet.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Batteries, wet. 173.159 Section 173.159... Batteries, wet. (a) Electric storage batteries, containing electrolyte acid or alkaline corrosive battery fluid (wet batteries), may not be packed with other materials except as provided in paragraphs (g)...

  14. 49 CFR 173.159 - Batteries, wet.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Batteries, wet. 173.159 Section 173.159... Batteries, wet. (a) Electric storage batteries, containing electrolyte acid or alkaline corrosive battery fluid (wet batteries), may not be packed with other materials except as provided in paragraphs (g)...

  15. 49 CFR 173.159 - Batteries, wet.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Batteries, wet. 173.159 Section 173.159... Batteries, wet. (a) Electric storage batteries, containing electrolyte acid or alkaline corrosive battery fluid (wet batteries), may not be packed with other materials except as provided in paragraphs (g)...

  16. Spacial Distribution of Salinity and the Mechanism of Saltwater Intrusion in the Modaomen Water Channel of Pear River Estuary

    NASA Astrophysics Data System (ADS)

    Liu, J. B.; Bao, Y.

    2011-09-01

    Modaomen channel is an important fresh water resource in Pearl River Delta. It has been impacted by saltwater intrusion frequently in the last decade. This has drawn more and more attention from scientists and engineers. The hydrodynamic mechanism of saltwater intrusion is still impercipient. In the present paper, hydrographs of velocity and salinity in the channel are analyzed based on field observations of velocity and salinity of upper, middle, and lower water layers at several stations along the Modaomen channel. It is found that the transport of salinity in Modaomen channel is obviously different from other estuaries. As the tidal range increases from neap to spring tide, the salinity in each water layer decreases unexpectedly. This peculiar phenomenon is attributed to the extraordinary flow process in the channel. When salinity value in each layer and vertical salinity gradient are lower during spring tide, no matter on rising or ebbing tide, the flow velocity monotonously decreases from water surface to the bottom, which is suggested by common sense. However, when salinity values and vertical salinity gradient are higher during neap tide, the flow velocity unexpectedly increases from water surface to the bottom during flood period, and flood duration of the bottom current is surprisingly as long as 15-18 hours. In addition, an inflexional velocity profile may remain amazingly for about 9 hours. This could be driven by the baroclinic pressure under the condition of tides, topography and upstream runoff discharge of this channel.

  17. Gradient Refractive Index Lenses.

    ERIC Educational Resources Information Center

    Morton, N.

    1984-01-01

    Describes the nature of gradient refractive index (GRIN) lenses, focusing on refraction in these materials, focal length of a thin Wood lens, and on manufacturing of such lenses. Indicates that GRIN lenses of small cross section are in limited production with applications suggested for optical communication and photocopying fields. (JN)

  18. Manipulating the Gradient

    ERIC Educational Resources Information Center

    Gaze, Eric C.

    2005-01-01

    We introduce a cooperative learning, group lab for a Calculus III course to facilitate comprehension of the gradient vector and directional derivative concepts. The lab is a hands-on experience allowing students to manipulate a tangent plane and empirically measure the effect of partial derivatives on the direction of optimal ascent. (Contains 7…

  19. Seed flotation and germination of salt marsh plants: The effects of stratification, salinity, and/or inundation regime

    USGS Publications Warehouse

    Elsey-Quirk, T.; Middleton, B.A.; Proffitt, C.E.

    2009-01-01

    We examined the effects of cold stratification and salinity on seed flotation of eight salt marsh species. Four of the eight species were tested for germination success under different stratification, salinity, and flooding conditions. Species were separated into two groups, four species received wet stratification and four dry stratification and fresh seeds of all species were tested for flotation and germination. Fresh seeds of seven out of eight species had flotation times independent of salinity, six of which had average flotation times of at least 50 d. Seeds of Spartina alterniflora and Spartina patens had the shortest flotation times, averaging 24 and 26 d, respectively. Following wet stratification, the flotation time of S. alterniflora seeds in higher salinity water (15 and 36 ppt) was reduced by over 75% and germination declined by more than 90%. Wet stratification reduced the flotation time of Distichlis spicata seeds in fresh water but increased seed germination from 2 to 16% in a fluctuating inundation regime. Fresh seeds of Iva frutescens and S. alternflora were capable of germination and therefore are non-dormant during dispersal. Fresh seeds of I. frutescens had similar germination to dry stratified seeds ranging 25-30%. Salinity reduced seed germination for all species except for S. alterniflora. A fluctuating inundation regime was important for seed germination of the low marsh species and for germination following cold stratification. The conditions that resulted in seeds sinking faster were similar to the conditions that resulted in higher germination for two of four species. ?? 2009 Elsevier B.V.

  20. Determining Salinity by Simple Means.

    ERIC Educational Resources Information Center

    Schlenker, Richard M.

    This paper describes the construction and use of a simple salinometer. The salinometer is composed, mainly, of a milliammeter and a battery and uses the measurement of current flow to determine the salinity of water. A complete list of materials is given, as are details of construction and operation of the equipment. The use of the salinometer in…

  1. Mycelial bacteria of saline soils

    NASA Astrophysics Data System (ADS)

    Zvyagintsev, D. G.; Zenova, G. M.; Oborotov, G. V.

    2008-10-01

    The actinomycetal complexes of saline soils comprise the representatives of the Streptomyces and Micromonospora genera, the number of which are hundreds and thousands of CFU/g soil. Complexes of mycelial bacteria in saline soils are poorer in terms of number (by 1-3 orders of magnitude) and taxonomic composition than the complexes of the zonal soil types. A specific feature of the actinomycetal complexes of saline soils is the predominance of halophilic, alkaliphilic, and haloalkaliphilic streptomycetes that well grow at pH 8-9 and concentrations of NaCl close to 5%. Actinomycetes in saline soils grow actively, and the length of their mycelium reaches 140 m in 1 gram of soil. The haloalkaliphilic streptomycetes grow fast and inhibit the formation of spores at pH 9 and high concentrations of salts (Na2SO4 and MgCl2, 5%) as compared to their behavior on a neutral medium with a salt concentration of 0.02%. They are characterized by the maximal radial growth rate of colonies on an alkaline medium with 5% NaCl.

  2. The Analysis of Characteristics in Dry and Wet Environments of Silicon Nanowire-Biosensor.

    PubMed

    Choi, Hyoun Mo; Shin, Dong Jae; Lee, Jung Han; Mo, Hyun-Sun; Park, Tae Jung; Park, Byung-Gook; Kim, Dong Myong; Choi, Sung-Jin; Kim, Dae Hwan; Park, Jisun

    2016-05-01

    Our study investigates differences in sensitivity of dry and wet environment in the field of biosensing experiment in detail and depth. The sensitivity of biosensing varies by means of surrounding conditions of silicon nanowire field effect transistor (SiNW FET). By examining charged polymer reaction in the silicon nanowire transistor (SiNW), we have discovered that the threshold voltage (V(T)) shift and change of subthreshold slope (SS) in wet environment are smaller than that of the air. Furthermore, we analyzed the sensitivity through modifying electrolyte concentration in the wet condition, and confirmed that V(T) shift increases in low concentration condition of phosphate buffered saline (PBS) due to the Debye length. We believe that the results we have found in this study would be the cornerstone in contributing to advanced biosensing experiment in the future. PMID:27483843

  3. Bulk Moisture and Salinity Sensor

    NASA Technical Reports Server (NTRS)

    Nurge, Mark; Monje, Oscar; Prenger, Jessica; Catechis, John

    2013-01-01

    Measurement and feedback control of nutrient solutions in plant root zones is critical to the development of healthy plants in both terrestrial and reduced-gravity environments. In addition to the water content, the amount of fertilizer in the nutrient solution is important to plant health. This typically requires a separate set of sensors to accomplish. A combination bulk moisture and salinity sensor has been designed, built, and tested with different nutrient solutions in several substrates. The substrates include glass beads, a clay-like substrate, and a nutrient-enriched substrate with the presence of plant roots. By measuring two key parameters, the sensor is able to monitor both the volumetric water content and salinity of the nutrient solution in bulk media. Many commercially available moisture sensors are point sensors, making localized measurements over a small volume at the point of insertion. Consequently, they are more prone to suffer from interferences with air bubbles, contact area of media, and root growth. This makes it difficult to get an accurate representation of true moisture content and distribution in the bulk media. Additionally, a network of point sensors is required, increasing the cabling, data acquisition, and calibration requirements. measure the dielectric properties of a material in the annular space of the vessel. Because the pore water in the media often has high salinity, a method to measure the media moisture content and salinity simultaneously was devised. Characterization of the frequency response for capacitance and conductance across the electrodes was completed for 2-mm glass bead media, 1- to 2-mm Turface (a clay like media), and 1- to 2-mm fertilized Turface with the presence of root mass. These measurements were then used to find empirical relationships among capacitance (C), the dissipation factor (D), the volumetric water content, and the pore water salinity.

  4. Coal combustion by wet oxidation

    SciTech Connect

    Bettinger, J.A.; Lamparter, R.A.; McDowell, D.C.

    1980-11-15

    The combustion of coal by wet oxidation was studied by the Center for Waste Management Programs, of Michigan Technological University. In wet oxidation a combustible material, such as coal, is reacted with oxygen in the presence of liquid water. The reaction is typically carried out in the range of 204/sup 0/C (400/sup 0/F) to 353/sup 0/C (650/sup 0/F) with sufficient pressure to maintain the water present in the liquid state, and provide the partial pressure of oxygen in the gas phase necessary to carry out the reaction. Experimental studies to explore the key reaction parameters of temperature, time, oxidant, catalyst, coal type, and mesh size were conducted by running batch tests in a one-gallon stirred autoclave. The factors exhibiting the greatest effect on the extent of reaction were temperature and residence time. The effect of temperature was studied from 204/sup 0/C (400/sup 0/F) to 260/sup 0/C (500/sup 0/F) with a residence time from 600 to 3600 seconds. From this data, the reaction activation energy of 2.7 x 10/sup 4/ calories per mole was determined for a high-volatile-A-Bituminous type coal. The reaction rate constant may be determined at any temperature from the activation energy using the Arrhenius equation. Additional data were generated on the effect of mesh size and different coal types. A sample of peat was also tested. Two catalysts were evaluated, and their effects on reaction rate presented in the report. In addition to the high temperature combustion, low temperature desulfurization is discussed. Desulfurization can improve low grade coal to be used in conventional combustion methods. It was found that 90% of the sulfur can be removed from the coal by wet oxidation with the carbon untouched. Further desulfurization studies are indicated.

  5. Wet Work and Barrier Function.

    PubMed

    Fartasch, Manigé

    2016-01-01

    Wet work defined as unprotected exposure to humid environments/water; high frequencies of hand washing procedures or prolonged glove occlusion is believed to cause irritant contact dermatitis in a variety of occupations. This review considers the recent studies on wet-work exposure and focuses on its influence on barrier function. There are different methods to study the effect of wet work on barrier function. On the one hand, occupational cohorts at risk can be monitored prospectively by skin bioengineering technology and clinical visual scoring systems; on the other hand, experimental test procedures with defined application of water, occlusion and detergents are performed in healthy volunteers. Both epidemiological studies and the results of experimental procedures are compared and discussed. A variety of epidemiological studies analyze occupational cohorts at risk. The measurement of transepidermal water loss, an indicator of the integrity of the epidermal barrier, and clinical inspection of the skin have shown that especially the frequencies of hand washing and water contact/contact to aqueous mixtures seem to be the main factors for the occurrence of barrier alterations. On the other hand, in a single cross-sectional study, prolonged glove wearing (e.g. occlusion for 6 h per shift in clean-room workers) without exposure to additional hazardous substances seemed not to affect the skin negatively. But regarding the effect of occlusion, there is experimental evidence that previously occluded skin challenged with sodium lauryl sulfate leads to an increased susceptibility to the irritant with an aggravation of the irritant reaction. These findings might have relevance for the real-life situation in so far as after occupational glove wearing, the skin is more susceptible to potential hazards to the skin even during leisure hours. PMID:26844906

  6. Effect of salinity on the toxicity of road dust in an estuarine amphipod Grandidierella japonica.

    PubMed

    Hiki, Kyoshiro; Nakajima, Fumiyuki

    2015-01-01

    Urban runoff can reach coastal aquatic environments; however, little is known about the effect of salinity on road runoff toxicity. The objective of this study is to investigate the toxicity of highway road dust over a salinity gradient from 5 to 35‰, in an estuarine benthic amphipod, Grandidierella japonica. Road dust toxicity was evaluated by assessing mortality after 10 days of exposure and short-term microbead ingestion activity of the amphipod. For all road dust samples considered, amphipod mortality increased with increasing salinity, whereas no significant difference in mortality was observed among test salinities in the reference river sediment. Ingestion activity during exposure to road dust decreased with increasing salinity. In fact, none of the individuals ingested any microbeads at salinity of 35‰. If assumed microbead ingestion is a proxy for feeding activity, high mortality at 35‰ could be attributed to aquatic exposure and not to dietary exposure. These findings suggest that road dust may have considerable impact on benthic organisms at high salinity levels. PMID:26360764

  7. Nitrogen removal properties in a continuous marine anammox bacteria reactor under rapid and extensive salinity changes.

    PubMed

    Wei, Qiaoyan; Kawagoshi, Yasunori; Huang, Xiaowu; Hong, Nian; Van Duc, Luong; Yamashita, Yuki; Hama, Takehide

    2016-04-01

    Salinity tolerance is one of the most important factors for the application of bioreactors to high-salinity wastewater. Although marine anammox bacteria (MAB) might be expected to tolerate higher salinities than freshwater anammox bacteria, there is little information on the effects of salinity on MAB activity. This study aimed to reveal the nitrogen removal properties in a continuous MAB reactor under conditions of rapid and extensive salinity changes. The reactor demonstrated stable nitrogen removal performance with a removal efficiency of over 85% under salinity conditions ranging from 0 to 50 g/L NaCl. The reactor performance was also well maintained, even though the salinity was rapidly changed from 30 to 50 g/L and from 30 to 0 g/L. Other evidence suggested that the seawater medium used contained components essential for effective MAB performance. Bacterial community analysis using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) showed that planctomycete UKU-1, the dominant MAB species in the inoculum, was the main contributor to anammox activity under all conditions. The PCR-DGGE using a universal bacterial primer set showed different DNA band patterns between the reactor biomass sample collected under conditions of 75 g/L NaCl and all other conditions (0, 30, 50 and freshwater-medium). All DNA sequences determined were very similar to those of bacterial species from marine environments, anaerobic environments, or wastewater-treatment facilities. PMID:26845464

  8. Wet/Dry Vacuum Cleaner

    NASA Technical Reports Server (NTRS)

    Reimers, Harold; Andampour, Jay; Kunitser, Craig; Thomas, Ike

    1995-01-01

    Vacuum cleaner collects and retains dust, wet debris, and liquids. Designed for housekeeping on Space Station Freedom, it functions equally well in normal Earth Gravity or in microgravity. Generates acoustic noise at comfortably low levels and includes circuitry that reduces electromagnetic interference to other electronic equipment. Draws materials into bag made of hydrophobic sheet with layers of hydrophilic super-absorbing pads at downstream end material. Hydrophilic material can gel many times its own weight of liquid. Blower also provides secondary airflow to cool its electronic components.

  9. A Wet Chemistry Laboratory Cell

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This picture of NASA's Phoenix Mars Lander's Wet Chemistry Laboratory (WCL) cell is labeled with components responsible for mixing Martian soil with water from Earth, adding chemicals and measuring the solution chemistry. WCL is part of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument suite on board the Phoenix lander.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  10. Projections of on-farm salinity in coastal Bangladesh.

    PubMed

    Clarke, D; Williams, S; Jahiruddin, M; Parks, K; Salehin, M

    2015-06-01

    This paper quantifies the expected impacts of climate change, climate variability and salinity accumulation on food production in coastal Bangladesh during the dry season. This forms part of a concerted series of actions on agriculture and salinity in Bangladesh under the UK funded Ecosystems for Poverty Alleviation programme and the British Council INSPIRE scheme. The work was undertaken by developing simulation models for soil water balances, dry season irrigation requirements and the effectiveness of the monsoon season rainfall at leaching accumulated salts. Simulations were run from 1981 to 2098 using historical climate data and a daily climate data set based on the Met Office Hadley Centre HadRM3P regional climate model. Results show that inter-seasonal and inter-annual variability are key factors that affect the viability of dry season vegetable crop growing. By the end of the 21(st) century the dry season is expected to be 2-3 weeks longer than now (2014). Monsoon rainfall amounts will remain the same or possibly slightly increase but it will occur over a slightly shorter wet season. Expectations of sea level rise and additional saline intrusion into groundwater aquifers mean that dry season irrigation water is likely to become more saline by the end of the 21(st) century. A study carried out at Barisal indicates that irrigating with water at up to 4 ppt can be sustainable. Once the dry season irrigation water quality goes above 5 ppt, the monsoon rainfall is no longer able to leach the dry season salt deposits so salt accumulation becomes significant and farm productivity will reduce by as a much as 50%, threatening the livelihoods of farmers in this region. PMID:25790459

  11. INTEGRATING DESALINATION AND AGRICULTURAL SALINITY CONTROL ALTERNATIVES

    EPA Science Inventory

    The cost-effectiveness relationships for various agricultural and desalination alternatives for controlling salinity in irrigation return flows are developed. Selection of optimal salinity management strategies on a river basin scale is described as a problem of integrating optim...

  12. Bigravity from gradient expansion

    NASA Astrophysics Data System (ADS)

    Yamashita, Yasuho; Tanaka, Takahiro

    2016-05-01

    We discuss how the ghost-free bigravity coupled with a single scalar field can be derived from a braneworld setup. We consider DGP two-brane model without radion stabilization. The bulk configuration is solved for given boundary metrics, and it is substituted back into the action to obtain the effective four-dimensional action. In order to obtain the ghost-free bigravity, we consider the gradient expansion in which the brane separation is supposed to be sufficiently small so that two boundary metrics are almost identical. The obtained effective theory is shown to be ghost free as expected, however, the interaction between two gravitons takes the Fierz-Pauli form at the leading order of the gradient expansion, even though we do not use the approximation of linear perturbation. We also find that the radion remains as a scalar field in the four-dimensional effective theory, but its coupling to the metrics is non-trivial.

  13. A simple and robust method for pre-wetting poly (lactic-co-glycolic) acid microspheres

    PubMed Central

    Wright, Bernice; Parmar, Nina; Bozec, Laurent; Aguayo, Sebastian D

    2015-01-01

    Poly (lactic-co-glycolic) acid microspheres are amenable to a number of biomedical procedures that support delivery of cells, drugs, peptides or genes. Hydrophilisation or wetting of poly (lactic-co-glycolic) acid are an important pre-requisites for attachment of cells and can be achieved via exposure to plasma oxygen or nitrogen, surface hydrolysis with NaOH or chloric acid, immersion in ethanol and water, or prolonged incubation in phosphate buffered saline or cell culture medium. The aim of this study is to develop a simple method for wetting poly (lactic-co-glycolic) acid microspheres for cell delivery applications. A one-step ethanol immersion process that involved addition of serum-supplemented medium and ethanol to PLGA microspheres over 30 min–24 h is described in the present study. This protocol presents a more efficient methodology than conventional two-step wetting procedures. Attachment of human skeletal myoblasts to poly (lactic-co-glycolic) acid microspheres was dependent on extent of wetting, changes in surface topography mediated by ethanol pre-wetting and serum protein adsorption. Ethanol, at 70% (v/v) and 100%, facilitated similar levels of wetting. Wetting with 35% (v/v) ethanol was only achieved after 24 h. Pre-wetting (over 3 h) with 70% (v/v) ethanol allowed significantly greater (p ≤ 0.01) serum protein adsorption to microspheres than wetting with 35% (v/v) ethanol. On serum protein-loaded microspheres, greater numbers of myoblasts attached to constructs wetted with 70% ethanol than those partially wetted with 35% (v/v) ethanol. Microspheres treated with 70% (v/v) ethanol presented a more rugose surface than those treated with 35% (v/v) ethanol, indicating that more efficient myoblast adhesion to the former may be at least partially attributed to differences in surface structure. We conclude that our novel protocol for pre-wetting poly (lactic-co-glycolic) acid microspheres that incorporates biochemical and structural features

  14. This technology is all wet

    SciTech Connect

    1996-09-01

    The wet oxidation technology developed by Conor Pacific Environmental Technologies Inc. (CPET; Vancouver, British Columbia) is designed to eliminate hazardous and nonhazardous organic contaminants from liquid effluent. The technology, which originated in Denmark, uses oxygen homogeneously dissolved in water to treat organic contaminants. According to the company, the process eliminates hazardous and nonhazardous contaminants without generating pollutant emissions, making it relatively easy to permit. CPET says wet oxidation eliminates some inorganic compounds, such as cyanides, and all hazardous and nonhazardous organic pollutants, including those found in petroleum products, aromatic solvents, tar compounds, pesticides and plasticizers. The process also handles relatively high concentrations of such contaminants as phenol, oil, and coal, tar and wood preservatives. The technology can achieve up to 99.9999% destruction efficiencies. The process is exothermic, generating its own heat, and allows energy to be recovered and recycled. Some heating is required at start-up, and heat exchangers are used to overcome heat build-up later in the process.

  15. Mars: Always Cold, Sometimes Wet?

    NASA Technical Reports Server (NTRS)

    Lee, Pascal; McKay, Christoper P.

    2003-01-01

    A synthesis of a diverse suite of observations of H2O-related landforms that are possible Mars analogs from terrestrial polar regions (Devon Island in the Arctic; the Dry Valleys of Antarctica) put into question any requirement for extended episode(s) of warm and wet climate in Mars past. Geologically transient episodes of localized H2O cycling, forced by exogenic impacts, enhanced endogenic heat flow, and/or orbit-driven short-term local environmental change under an otherwise cold, low pressure (=10(exp 2) mbar) global climate, may be sufficient to account for the martian surface's exposed record of aqueous activity. A Mars that was only sometimes locally warm and wet while remaining climatically cold throughout its history is consistent with results (difficulties) encountered in modeling efforts attempting to support warm martian climate hypotheses. Possible analogs from terrestrial cold climate regions for the recent gully features on Mars also illustrate how transient localized aqueous activity might, under specific circumstances, also occur on Mars under the present frigid global climatic regime.

  16. The effect of ionic strength on oil adhesion in sandstone – the search for the low salinity mechanism

    PubMed Central

    Hilner, E.; Andersson, M. P.; Hassenkam, T.; Matthiesen, J.; Salino, P. A.; Stipp, S. L. S.

    2015-01-01

    Core flood and field tests have demonstrated that decreasing injection water salinity increases oil recovery from sandstone reservoirs. However, the microscopic mechanism behind the effect is still under debate. One hypothesis is that as salinity decreases, expansion of the electrical double layer decreases attraction between organic molecules and pore surfaces. We have developed a method that uses atomic force microscopy (AFM) in chemical force mapping (CFM) mode to explore the relationship between wettability and salinity. We functionalised AFM tips with alkanes and used them to represent tiny nonpolar oil droplets. In repeated measurements, we brought our “oil” close to the surface of sand grains taken from core plugs and we measured the adhesion between the tip and sample. Adhesion was constant in high salinity solutions but below a threshold of 5,000 to 8,000 ppm, adhesion decreased as salinity decreased, rendering the surface less oil wet. The effect was consistent, reproducible and reversible. The threshold for the onset of low salinity response fits remarkably well with observations from core plug experiments and field tests. The results demonstrate that the electric double layer force always contributes at least in part to the low salinity effect, decreasing oil wettability when salinity is low. PMID:25899050

  17. The effect of ionic strength on oil adhesion in sandstone--the search for the low salinity mechanism.

    PubMed

    Hilner, E; Andersson, M P; Hassenkam, T; Matthiesen, J; Salino, P A; Stipp, S L S

    2015-01-01

    Core flood and field tests have demonstrated that decreasing injection water salinity increases oil recovery from sandstone reservoirs. However, the microscopic mechanism behind the effect is still under debate. One hypothesis is that as salinity decreases, expansion of the electrical double layer decreases attraction between organic molecules and pore surfaces. We have developed a method that uses atomic force microscopy (AFM) in chemical force mapping (CFM) mode to explore the relationship between wettability and salinity. We functionalised AFM tips with alkanes and used them to represent tiny nonpolar oil droplets. In repeated measurements, we brought our "oil" close to the surface of sand grains taken from core plugs and we measured the adhesion between the tip and sample. Adhesion was constant in high salinity solutions but below a threshold of 5,000 to 8,000 ppm, adhesion decreased as salinity decreased, rendering the surface less oil wet. The effect was consistent, reproducible and reversible. The threshold for the onset of low salinity response fits remarkably well with observations from core plug experiments and field tests. The results demonstrate that the electric double layer force always contributes at least in part to the low salinity effect, decreasing oil wettability when salinity is low. PMID:25899050

  18. Microscopic Structure of the Wetting Film at the Surface of Liquid Ga-Bi Alloys

    NASA Astrophysics Data System (ADS)

    Tostmann, H.; Dimasi, E.; Shpyrko, O. G.; Pershan, P. S.; Ocko, B. M.; Deutsch, M.

    2000-05-01

    X-ray reflectivity measurements of the binary liquid Ga-Bi alloy reveal a dramatically different surface structure above and below the monotectic temperature Tmono = 222 °C. A Gibbs-adsorbed Bi monolayer resides at the surface in both regimes. However, a 30 Å thick, Bi-rich wetting film intrudes between the Bi monolayer and the Ga-rich bulk for T>Tmono. The wetting film's internal structure, not hitherto measured, is determined with Å resolution, showing a concentration gradient not predicted by theory and a highly diffuse interface with the bulk phase.

  19. Microscopic structure of the wetting film at the surface of liquid Ga-Bi alloys

    PubMed

    Tostmann; DiMasi; Shpyrko; Pershan; Ocko; Deutsch

    2000-05-01

    X-ray reflectivity measurements of the binary liquid Ga-Bi alloy reveal a dramatically different surface structure above and below the monotectic temperature T(mono) = 222 degrees C. A Gibbs-adsorbed Bi monolayer resides at the surface in both regimes. However, a 30 A thick, Bi-rich wetting film intrudes between the Bi monolayer and the Ga-rich bulk for T>T(mono). The wetting film's internal structure, not hitherto measured, is determined with A resolution, showing a concentration gradient not predicted by theory and a highly diffuse interface with the bulk phase. PMID:10990692

  20. Microscopic Structure of the Wetting Film at the Surface of Liquid Ga-Bi Alloys

    SciTech Connect

    Tostmann, H.; DiMasi, E.; Shpyrko, O. G.; Pershan, P. S.; Ocko, B. M.; Deutsch, M.

    2000-05-08

    X-ray reflectivity measurements of the binary liquid Ga-Bi alloy reveal a dramatically different surface structure above and below the monotectic temperature T{sub mono}=222 degree sign C . A Gibbs-adsorbed Bi monolayer resides at the surface in both regimes. However, a 30 Angstrom thick, Bi-rich wetting film intrudes between the Bi monolayer and the Ga-rich bulk for T>T{sub mono} . The wetting film's internal structure, not hitherto measured, is determined with Angstrom resolution, showing a concentration gradient not predicted by theory and a highly diffuse interface with the bulk phase. (c) 2000 The American Physical Society.

  1. Assessing the emission sources of atmospheric mercury in wet deposition across Illinois.

    PubMed

    Gratz, Lynne E; Keeler, Gerald J; Morishita, Masako; Barres, James A; Dvonch, J Timothy

    2013-03-15

    From August 4, 2007 to August 31, 2009, we collected event-based precipitation samples for mercury (Hg) and trace element analyses at four sites in Illinois (IL), USA. The objectives of these measurements were to quantify Hg wet deposition across the state, and to assess the contributions to Hg in precipitation from major local and regional emission sources. Monitoring sites were located, from north to south, in Chicago, Peoria, Nilwood, and Carbondale, IL. Measurements from these four sites demonstrated that a clear spatial gradient in Hg wet deposition was not evident across the state. Each site received>10μgm(-2) of Hg wet deposition annually, and these observed values were comparable to annual Hg wet deposition measurements from other event-based precipitation monitoring sites in source-impacted areas of the Midwestern U.S. We applied the multivariate statistical receptor model, Positive Matrix Factorization (EPA PMF v3.0), to the measured Hg and trace element wet deposition amounts at the four sites. Results suggested that 50% to 74% of total Hg wet deposition at each site could be attributed to coal combustion emissions. The other source signatures identified in the precipitation compositions included cement manufacturing, mixed metal smelting/waste incineration, iron-steel production, and a phosphorus source. We also applied a hybrid receptor model, Quantitative Transport Bias Analysis (QTBA), to the Hg wet deposition datasets to identify the major source regions associated with the measured values. The calculated QTBA probability fields suggested that transport from urban/industrial areas, such as Chicago/Gary, St. Louis, and the Ohio River Valley, resulted in some of the highest estimated event-based Hg wet deposition amounts at the four sites (potential mass transfer of up to 0.32μgm(-2)). The combined application of PMF and QTBA supported the hypothesis that local and regional coal combustion was the largest source of Hg wet deposition in Illinois

  2. Salinity and Temperature Tolerance of the Nemertean Worm Carcinonemertes errans, an Egg Predator of the Dungeness Crab.

    PubMed

    Dunn, Paul H; Young, Craig M

    2015-04-01

    Estuaries can be harsh habitats for the marine animals that enter them, but they may also provide these species with sub-saline refuges from their parasites. The nemertean egg predator Carcinonemertes errans is known to occur less frequently and in smaller numbers on its host, the Dungeness crab Metacarcinus magister, when the hosts are found within estuaries. We examined the temperature and salinity tolerances of C. errans to determine if this observed distribution represents a true salinity refuge. We monitored the survival of juvenile and larval worms exposed to ecologically relevant salinities (5-30) and temperatures (8-20 °C) over the course of several days under laboratory conditions. Juvenile worms were unaffected by the experimental temperature levels and exhibited robustness to salinity treatments 25 and 30. However, significant mortality was seen at salinity treatments 20 and below. Larvae were less tolerant than juveniles to lowered salinity and were also somewhat more susceptible to the higher temperatures tested. Given that the Dungeness crab can tolerate forays into mesohaline (salinity 5-18) waters for several days at a time, our findings suggest that salinity gradients play an important role in creating a parasite refuge for this species within the estuaries of the Pacific Northwest. PMID:25920719

  3. Responses of growth, antioxidants and gene expression in smooth cordgrass (Spartina alterniflora) to various levels of salinity.

    PubMed

    Courtney, Abigail J; Xu, Jichen; Xu, Yan

    2016-02-01

    Salinity is a major environmental factor limiting the productivity and quality of crop plants. While most cereal crops are salt-sensitive, several halophytic grasses are able to maintain their growth under saline conditions. Elucidating the mechanisms for salinity responses in halophytic grasses would contribute to the breeding of salt-tolerant cereal and turf species belonging to the Poaceae family. Smooth cordgrass (Spartina alterniflora) is a dominant native halophytic grass in the Hackensack Meadowlands, the coastal salt marshes located in northeastern New Jersey. The goals of this study were to examine the growth pattern of S. alterniflora in a salinity gradient and identify an optimal range of salinity for its maximal growth. The regulation of its antioxidant system and gene expression under supraoptimal salinity conditions was also investigated. Our results showed that a salinity of 4 parts per thousand (ppt) (68 mM) was most favorable for the growth of S. alterniflora, followed by a non-salt environment. S. alterniflora responded to salts in the environment by regulating antioxidant enzyme activities and the expression of stress-induced proteins such as ALDH, HVA22 and PEPC. The plant may tolerate salinity up to the concentration of sea water, but any salinity above 12 ppt retarded its growth and altered the expression of genes encoding critical proteins. PMID:26760954

  4. Evaluating Battery-like Reactions to Harvest Energy from Salinity Differences using Ammonium Bicarbonate Salt Solutions.

    PubMed

    Kim, Taeyoung; Rahimi, Mohammad; Logan, Bruce E; Gorski, Christopher A

    2016-05-10

    Mixing entropy batteries (MEBs) are a new approach to generate electricity from salinity differences between two aqueous solutions. To date, MEBs have only been prepared from solutions containing chloride salts, owing to their relevance in natural salinity gradients created from seawater and freshwater. We hypothesized that MEBs could capture energy using ammonium bicarbonate (AmB), a thermolytic salt that can be used to convert waste heat into salinity gradients. We examined six battery electrode materials. Several of the electrodes were unstable in AmB solutions or failed to produce expected voltages. Of the electrode materials tested, a cell containing a manganese oxide electrode and a metallic lead electrode produced the highest power density (6.3 mW m(-2) ). However, this power density is still low relative to previously reported NaCl-based MEBs and heat recovery systems. This proof-of-concept study demonstrated that MEBs could indeed be used to generate electricity from AmB salinity gradients. PMID:27030080

  5. The Aquarius Salinity Retrieval Algorithm

    NASA Technical Reports Server (NTRS)

    Meissner, Thomas; Wentz, Frank; Hilburn, Kyle; Lagerloef, Gary; Le Vine, David

    2012-01-01

    The first part of this presentation gives an overview over the Aquarius salinity retrieval algorithm. The instrument calibration [2] converts Aquarius radiometer counts into antenna temperatures (TA). The salinity retrieval algorithm converts those TA into brightness temperatures (TB) at a flat ocean surface. As a first step, contributions arising from the intrusion of solar, lunar and galactic radiation are subtracted. The antenna pattern correction (APC) removes the effects of cross-polarization contamination and spillover. The Aquarius radiometer measures the 3rd Stokes parameter in addition to vertical (v) and horizontal (h) polarizations, which allows for an easy removal of ionospheric Faraday rotation. The atmospheric absorption at L-band is almost entirely due to molecular oxygen, which can be calculated based on auxiliary input fields from numerical weather prediction models and then successively removed from the TB. The final step in the TA to TB conversion is the correction for the roughness of the sea surface due to wind, which is addressed in more detail in section 3. The TB of the flat ocean surface can now be matched to a salinity value using a surface emission model that is based on a model for the dielectric constant of sea water [3], [4] and an auxiliary field for the sea surface temperature. In the current processing only v-pol TB are used for this last step.

  6. Surface-subsurface salinity distribution and exchange in a closed-basin prairie wetland

    NASA Astrophysics Data System (ADS)

    Heagle, Dru; Hayashi, Masaki; Kamp, Garth van der

    2013-01-01

    SummaryThe northern prairie region of North America has numerous closed-basin wetlands. Salinity (i.e. sulphate concentration) of these wetland ponds has a profound effect on their ecological function. Despite the apparent lack of surface and subsurface outflow from the closed basins, and strong evaporative enrichment due to the dry climate, many of the closed-basin wetlands maintain moderate salinity (1-10 g L-1 as total dissolved solids) instead of evolving into hyper-saline wetlands. The objective of this study is to characterize the surface and groundwater conditions of a typical saline wetland in Saskatchewan, Canada, quantify the surface and subsurface distribution of sulphate, and understand the processes controlling the wetland salinity. The analysis of sediment core samples and the electrical resistivity imaging of the wetland basin indicated a large mass (ca. 107 kg) of subsurface sulphate, most of which is in the form of gypsum. In comparison, the sulphate dissolved in pond water was only 0.13 × 106 kg at its maximum, indicating that only a small fraction of sulphate is in the pond water column at any given time. The analysis of a 19-year mass balance of the wetland pond showed that complex water-sediment exchange processes transfer sulphate from surface water to the underlying sediments during the drying phase of wetland, and transfer part of it back to surface water during the wetting phase. We hypothesize that this wet-dry cycle, repeated many times since the deglaciation of the region has allowed the subsurface sulphate to accumulate and maintained the moderate salinity of the wetland.

  7. Some Central Asian observatories for the WET

    NASA Astrophysics Data System (ADS)

    Meistas, E.

    1993-01-01

    The Mt. Maidanak Observatory, one of several observatories in the former Soviet Central Asia, is located at an important longitude to fill in the gap in the WET (Whole Earth Telescope) network. The Lithuanian astronomical station on Mt. Maidanak was successfully tested in May 1992 for future WET campaigns. In the September 1992 campaign it provided some useful data for the WET. In February 1993 the observatory was nationalized by the Uzbekistan government, and almost all astronomical activities there have stopped. The future use of this observatory for the WET campaigns is uncertain, but there are some signs that the situation is improving. We have examined the possibility of using other Central Asian observatories for the WET. A contact was established with the Fesenkov Astronomical Institute in Alma-Ata, and in October 1993 WET observations were made at the Assy-Turgen Observatory in Kazakhstan.

  8. Facile Fabrication of Gradient Surface Based on (meth)acrylate Copolymer Films

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Yang, H.; Wen, X.-F.; Cheng, J.; Xiong, J.

    2016-08-01

    This paper describes a simple and economic approach for fabrication of surface wettability gradient on poly(butyl acrylate - methyl methacrylate) [P (BA-MMA)] and poly(butyl acrylate - methyl methacrylate - 2-hydroxyethyl methacrylate) [P (BA-MMA-HEMA)] films. The (meth)acrylate copolymer [including P (BA-MMA) and P (BA-MMA-HEMA)] films are hydrolyzed in an aqueous solution of NaOH and the transformation of surface chemical composition is achieved by hydrolysis in NaOH solution. The gradient wetting properties are generated based on different functional groups on the P (BA-MMA) and P (BA-MMA-HEMA) films. The effects of both the surface chemical and surface topography on wetting of the (meth)acrylate copolymer film are discussed. Surface chemical composition along the materials length is determined by XPS, and surface topography properties of the obtained gradient surfaces are analyzed by FESEM and AFM. Water contact angle system (WCAs) results show that the P (BA-MMA-HEMA) films provide a larger slope of the gradient wetting than P (BA-MMA). Moreover, this work demonstrates that the gradient concentration of chemical composition on the poly(meth) acrylate films is owing to the hydrolysis processes of ester group, and the hydrolysis reactions that have negligible influence on the surface morphology of the poly(meth) acrylate films coated on the glass slide. The gradient wettability surfaces may find broad applications in the field of polymer coating due to the compatibility of (meth) acrylate polymer.

  9. Responses of estuarine circulation and salinity to the loss of intertidal flats – A modeling study

    SciTech Connect

    Yang, Zhaoqing; Wang, Taiping

    2015-08-25

    Intertidal flats in estuaries are coastal wetlands that provide critical marine habitats to support wide ranges of marine species. Over the last century many estuarine systems have experienced significant loss of intertidal flats due to anthropogenic impacts. This paper presents a modeling study conducted to investigate the responses of estuarine hydrodynamics to the loss of intertidal flats caused by anthropogenic actions in Whidbey Basin of Puget Sound on the northwest coast of North America. Changes in salinity intrusion limits in the estuaries, salinity stratification, and circulation in intertidal flats and estuaries were evaluated by comparing model results under the existing baseline condition and the no-flat condition. Model results showed that loss of intertidal flats results in an increase in salinity intrusion, stronger mixing, and a phase shift in salinity and velocity fields in the bay front areas. Model results also indicated that loss of intertidal flats enhances two-layer circulation, especially the bottom water intrusion. Loss of intertidal flats increases the mean salinity but reduces the salinity range in the subtidal flats over a tidal cycle because of increased mixing. Salinity intrusion limits extend upstream in all three major rivers discharging into Whidbey Basin when no intertidal flats are present. Changes in salinity intrusion and estuarine circulation patterns due to loss of intertidal flats affect the nearshore habitat and water quality in estuaries and potentially increase risk of coastal hazards, such as storm surge and coastal flooding. Furthermore, model results suggested the importance of including intertidal flats and the wetting-and-drying process in hydrodynamic simulations when intertidal flats are present in the model domain.

  10. Responses of estuarine circulation and salinity to the loss of intertidal flats – A modeling study

    DOE PAGESBeta

    Yang, Zhaoqing; Wang, Taiping

    2015-08-25

    Intertidal flats in estuaries are coastal wetlands that provide critical marine habitats to support wide ranges of marine species. Over the last century many estuarine systems have experienced significant loss of intertidal flats due to anthropogenic impacts. This paper presents a modeling study conducted to investigate the responses of estuarine hydrodynamics to the loss of intertidal flats caused by anthropogenic actions in Whidbey Basin of Puget Sound on the northwest coast of North America. Changes in salinity intrusion limits in the estuaries, salinity stratification, and circulation in intertidal flats and estuaries were evaluated by comparing model results under the existingmore » baseline condition and the no-flat condition. Model results showed that loss of intertidal flats results in an increase in salinity intrusion, stronger mixing, and a phase shift in salinity and velocity fields in the bay front areas. Model results also indicated that loss of intertidal flats enhances two-layer circulation, especially the bottom water intrusion. Loss of intertidal flats increases the mean salinity but reduces the salinity range in the subtidal flats over a tidal cycle because of increased mixing. Salinity intrusion limits extend upstream in all three major rivers discharging into Whidbey Basin when no intertidal flats are present. Changes in salinity intrusion and estuarine circulation patterns due to loss of intertidal flats affect the nearshore habitat and water quality in estuaries and potentially increase risk of coastal hazards, such as storm surge and coastal flooding. Furthermore, model results suggested the importance of including intertidal flats and the wetting-and-drying process in hydrodynamic simulations when intertidal flats are present in the model domain.« less

  11. Responses of estuarine circulation and salinity to the loss of intertidal flats - A modeling study

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoqing; Wang, Taiping

    2015-12-01

    Intertidal flats in estuaries are coastal wetlands that provide critical marine habitats to support wide ranges of marine species. Over the last century many estuarine systems have experienced significant loss of intertidal flats due to anthropogenic impacts. This paper presents a modeling study conducted to investigate the responses of estuarine hydrodynamics to the loss of intertidal flats in Whidbey Basin of Puget Sound on the northwest coast of North America. Changes in salinity intrusion limits in the estuaries, salinity stratification, and circulation in intertidal flats and estuaries were evaluated by comparing model results under the existing baseline condition and the no-flat condition. Model results showed that loss of intertidal flats results in an increase in salinity intrusion, stronger mixing, and a phase shift in salinity and velocity fields in the bay front areas. Model results also indicated that loss of intertidal flats enhances two-layer circulation, especially the bottom water intrusion. Loss of intertidal flats increases the mean salinity but reduces the salinity range in the subtidal flats over a tidal cycle because of increased mixing. Salinity intrusion limits extend upstream in all three major rivers discharging into Whidbey Basin when no intertidal flats are present. Changes in salinity intrusion and estuarine circulation patterns due to loss of intertidal flats affect the nearshore habitat and water quality in estuaries and potentially increase risk of coastal hazards, such as storm surge and coastal flooding. Lastly, model results suggested the importance of including intertidal flats and the wetting-and-drying process in hydrodynamic simulations when intertidal flats are present in the model domain.

  12. Spatial assessment of soil salinity in the Harran Plain using multiple kriging techniques.

    PubMed

    Bilgili, Ali V

    2013-01-01

    The Harran Plain is located in the southeastern part of Turkey and has recently been developed for irrigation agriculture. It already faces soil salinity problems causing major yield losses. Management of the problem is hindered by the lack of information on the extent and geography of the salinization problem. A survey was carried out to delineate the spatial distribution of salt-affected areas by randomly selecting 140 locations that were sampled at two depths (0 to 30 and 30 to 60 cm) and analyzed for soil salinity variables: soil electrical conductivity (EC), soluble cations (Ca(2+,) Mg(2+), Na(+), and K(+)), soluble anions (SO (4) (2-) , Cl(-)), exchangeable Na(+) (me 100 g(-1)) and exchangeable sodium percentage. Terrain attributes (slope, topographical wetness index) were extracted from the digital elevation model of the study area. Variogram analyses after log transformation and ordinary kriging (OK) were applied to map spatial patterns of soil salinity variables. Multivariate geostatistical methods-regression kriging (RK) and kriging with external drift (KED)-were used using elevation and soil electrical conductivity data as covariates. Performances of the three estimation methods (OK, RK, and KED) were compared using independent validation samples randomly selected from the main dataset. Soils were categorized into salinity classes using disjunctive kriging (DK) and ArcGIS, and classification accuracy was tested using the kappa statistic. Results showed that soil salinity variables all have skewed distribution and are poorly correlated with terrain indices but have strong correlations among each other. Up to 65 % improvement was obtained in the estimations of soil salinity variables using hybrid methods over OK with the best estimations obtained with RK using EC(0-30) as covariate. DK-ArcGIS successfully classified soil samples into different salinity groups with overall accuracy of 75 % and kappa of 0.55 (p < 0.001). PMID:22415846

  13. Capillary flow driven gradient generation in fluid stripes for biomaterial and biomedical applications

    NASA Astrophysics Data System (ADS)

    Hancock, Matthew; He, Jiankang; Piraino, Francesco; Camci-Unal, Gulden; Khademhosseini, Ali

    2011-11-01

    A simple and inexpensive bench-top method is presented employing passive mechanisms to generate centimeters-long gradients of molecules and particles in under a second with only a coated glass slide and a micropipette. By patterning hydrophilic regions on a substrate, a stripe of prepolymer solution is held in place on a glass slide by a hydrophobic boundary. Adding a droplet to one end of this ``pre-wet'' stripe causes a rapid capillary flow that spreads the droplet along the stripe to generate a gradient in the relative concentrations of the droplet and pre-wet solutions. Experiments and theoretical models characterize the flows and gradient profiles and their dependence on the fluid volumes, properties, and stripe geometry. A bench-top rapid prototyping method allows the user to design and fabricate the coated slides using only tape and hydrophobic spray. Gradient biomaterials are produced by crosslinking gradients of prepolymer solutions. Applications include producing a soluble drug gradient over cells in shear-protected microwells, generating a concentration gradient of cells encapsulated in three dimensions within a homogeneous biopolymer, and synthesizing a biomaterial with encapsulated cells exhibiting a gradient in cell spreading.

  14. Prokaryotic Community Diversity Along an Increasing Salt Gradient in a Soda Ash Concentration Pond.

    PubMed

    Simachew, Addis; Lanzén, Anders; Gessesse, Amare; Øvreås, Lise

    2016-02-01

    The effect of salinity on prokaryotic community diversity in Abijata-Shalla Soda Ash Concentration Pond system was investigated by using high-throughput 16S rRNA gene 454 pyrosequencing. Surface water and brine samples from five sites spanning a salinity range of 3.4 % (Lake Abijata) to 32 % (SP230F, crystallizer pond) were analyzed. Overall, 33 prokaryotic phyla were detected, and the dominant prokaryotic phyla accounted for more than 95 % of the reads consisting of Planctomycetes, Bacteroidetes, candidate division TM7, Deinococcus-Thermus, Firmicutes, Actinobacteria, Proteobacteria, and Euryarchaeota. Diversity indices indicated that operational taxonomic unit (OTU) richness decreases drastically with increasing salinity in the pond system. A total of 471 OTUs were found at 3.4 % salinity whereas 49 OTUs were detected in pond SP211 (25 % salinity), and only 19 OTUs in the crystallization pond at 32 % salinity (SP230F). Along the salinity gradient, archaeal community gradually replaced bacterial community. Thus, archaeal community accounted for 0.4 % in Lake Abijata while 99.0 % in pond SP230F. This study demonstrates that salinity appears to be the key environmental parameter in structuring the prokaryotic communities of haloalkaline environments. Further, it confirmed that the prokaryotic diversity in Lake Abijata is high and it harbors taxa with low or no phylogenetic similarities to existing prokaryotic taxa and thus represents novel microorganisms. PMID:26408190

  15. Continuous gravity gradient logging

    SciTech Connect

    Fitch, J.L.; Lyle, W.D. Jr.

    1986-07-29

    A method is described for conducting a gravimetry survey of an earth formation, comprising the steps of: (a) continuously traversing the earth formation with a gravity logging tool having a column of fluid within the tool, (b) measuring a first pressure difference along a first interval within the column of fluid, (c) measuring a second pressure difference along a second interval within the column of fluid, (d) differencing the first and second pressure differences to determine the gravity gradient along the earth formation between the first and second intervals.

  16. Impacts of groundwater extraction on salinization risk in a semi-arid floodplain

    NASA Astrophysics Data System (ADS)

    Alaghmand, S.; Beecham, S.; Hassanli, A.

    2013-12-01

    In the lower River Murray in Australia, a combination of a reduction in the frequency, duration and magnitude of natural floods, rising saline water tables in floodplains, and excessive evapotranspiration have led to an irrigation-induced groundwater mound forcing the naturally saline groundwater onto the floodplain. It is during the attenuation phase of floods that these large salt accumulations are likely to be mobilised and discharged into the river. This has been highlighted as the most significant risk in the Murray-Darling Basin and the South Australian Government and catchment management authorities have subsequently developed salt interception schemes (SIS). The aim of these schemes is to reduce the hydraulic gradient that drives the regional saline groundwater towards the River Murray. This paper investigates the interactions between a river (River Murray in South Australia) and a saline semi-arid floodplain (Clark's floodplain) that is significantly influenced by groundwater lowering due to a particular SIS. The results confirm that groundwater extraction maintains a lower water table and a higher amount of fresh river water flux to the saline floodplain aquifer. In terms of salinity, this may lead to less solute stored in the floodplain aquifer. This occurs through three mechanisms, namely extraction of the solute mass from the system, reducing the saline groundwater flux from the highland to the floodplain and changing the floodplain groundwater regime from a losing to a gaining one. It is shown that groundwater extraction is able to remove some of the solute stored in the unsaturated zone and this can mitigate the floodplain salinity risk. A conceptual model of the impact of groundwater extraction on floodplain salinization has been developed.

  17. Externally Wetted Ionic Liquid Thruster

    NASA Astrophysics Data System (ADS)

    Lozano, P.; Martinez-Sanchez, M.; Lopez-Urdiales, J. M.

    2004-10-01

    This paper presents initial developments of an electric propulsion system based on ionic liquid ion sources (ILIS). Propellants are ionic liquids, which are organic salts with two important characteristics; they remain in the liquid state at room temperature and have negligible vapor pressure, thus allowing their use in vacuum. The working principles of ILIS are similar to those of liquid metal ion sources (LMIS), in which a Taylor cone is electrostatically formed at the tip of an externally wetted needle while ions are emitted directly from its apex. ILIS have the advantage of being able to produce negative ions that have similar masses than their positive counterparts with similar current levels. This opens up the possibility of achieving plume electrical neutrality without electron emitters. The possible multiplexing of these emitters is discussed in terms of achievable thrust density for applications other than micro-propulsion.

  18. Thunderstorms Increase Mercury Wet Deposition.

    PubMed

    Holmes, Christopher D; Krishnamurthy, Nishanth P; Caffrey, Jane M; Landing, William M; Edgerton, Eric S; Knapp, Kenneth R; Nair, Udaysankar S

    2016-09-01

    Mercury (Hg) wet deposition, transfer from the atmosphere to Earth's surface by precipitation, in the United States is highest in locations and seasons with frequent deep convective thunderstorms, but it has never been demonstrated whether the connection is causal or simple coincidence. We use rainwater samples from over 800 individual precipitation events to show that thunderstorms increase Hg concentrations by 50% relative to weak convective or stratiform events of equal precipitation depth. Radar and satellite observations reveal that strong convection reaching the upper troposphere (where high atmospheric concentrations of soluble, oxidized mercury species (Hg(II)) are known to reside) produces the highest Hg concentrations in rain. As a result, precipitation meteorology, especially thunderstorm frequency and total rainfall, explains differences in Hg deposition between study sites located in the eastern United States. Assessing the fate of atmospheric mercury thus requires bridging the scales of global transport and convective precipitation. PMID:27464305

  19. Wet comet model: Rosetta redux

    NASA Astrophysics Data System (ADS)

    Sheldon, Robert B.

    2015-09-01

    The wet-comet model (WCM) of the structure and composition of comets was developed in 2005 to replace the "dirty-snowball" model (DSM) of Fred Whipple, because the first comet flybys of P/Halley "armada" revealed a very different landscape. Subsequent flybys of P/Borrelly, P/Wild-2, P/Hartley, P/Tempel-1 have confirmed and refined the model, so that we confidently predicted that the Rosetta mission would encounter a prolate, tumbling, concrete-encrusted, black comet: P/Churyumov-Gerasimenko. Unfortunately, the Philae lander team was preparing for a DSM and the anchors bounced off the concrete surface, but the orbiter has returned spec- tacular pictures of every crevice, which confirm and extend the WCM yet a sixth time. We report of what we predicted, what was observed, and several unexpected results from the ROSETTA mission.

  20. Directional wetting in anisotropic inverse opals.

    PubMed

    Phillips, Katherine R; Vogel, Nicolas; Burgess, Ian B; Perry, Carole C; Aizenberg, Joanna

    2014-07-01

    Porous materials display interesting transport phenomena due to restricted motion of fluids within the nano- to microscale voids. Here, we investigate how liquid wetting in highly ordered inverse opals is affected by anisotropy in pore geometry. We compare samples with different degrees of pore asphericity and find different wetting patterns depending on the pore shape. Highly anisotropic structures are infiltrated more easily than their isotropic counterparts. Further, the wetting of anisotropic inverse opals is directional, with liquids filling from the side more easily. This effect is supported by percolation simulations as well as direct observations of wetting using time-resolved optical microscopy. PMID:24941308

  1. A mesoscopic model for (de)wetting.

    PubMed

    Merabia, S; Pagonabarraga, I

    2006-06-01

    We present a mesoscopic model for simulating the dynamics of a non-volatile liquid on a solid substrate. The wetting properties of the solid can be tuned from complete wetting to total non-wetting. This model opens the way to study the dynamics of drops and liquid thin films at mesoscopic length scales of the order of the nanometer. As particular applications, we analyze the kinetics of spreading of a liquid drop wetting a solid substrate and the dewetting of a liquid film on a hydrophobic substrate. In all these cases, very good agreement is found between simulations and theoretical predictions. PMID:16775662

  2. Carbon nanotube fiber spun from wetted ribbon

    DOEpatents

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  3. Wet channel network extraction by integrating LiDAR intensity and elevation data

    NASA Astrophysics Data System (ADS)

    Hooshyar, Milad; Kim, Seoyoung; Wang, Dingbao; Medeiros, Stephen C.

    2015-12-01

    The temporal dynamics of stream networks are vitally important for understanding hydrologic processes including surface water and groundwater interaction and hydrograph recession. However, observations of wet channel networks are limited, especially in headwater catchments. Near-infrared LiDAR data provide an opportunity to map wet channel networks owing to the fine spatial resolution and strong absorption of light energy by water surfaces. A systematic method is developed to map wet channel networks by integrating elevation and signal intensity of ground returns. The signal intensity thresholds for identifying wet pixels are extracted from frequency distributions of intensity return within the convergent topography extent using a Gaussian mixture model. Moreover, the concept of edge in digital image processing, defined based on the intensity gradient, is utilized to enhance detection of small wet channels. The developed method is applied to the Lake Tahoe area based on eight LiDAR snapshots during recession periods in five watersheds. A power law relationship between streamflow and wetted channel length during recession periods is derived, and the scaling exponent (L∝Q0.44) is within the range of reported values from fieldwork in other regions.

  4. Capillarity and wetting of carbon dioxide and brine during drainage in Berea sandstone at reservoir conditions

    NASA Astrophysics Data System (ADS)

    Al-Menhali, Ali; Niu, Ben; Krevor, Samuel

    2015-10-01

    The wettability of CO2-brine-rock systems will have a major impact on the management of carbon sequestration in subsurface geological formations. Recent contact angle measurement studies have reported sensitivity in wetting behavior of this system to pressure, temperature, and brine salinity. We report observations of the impact of reservoir conditions on the capillary pressure characteristic curve and relative permeability of a single Berea sandstone during drainage—CO2 displacing brine—through effects on the wetting state. Eight reservoir condition drainage capillary pressure characteristic curves were measured using CO2 and brine in a single fired Berea sandstone at pressures (5-20 MPa), temperatures (25-50°C), and ionic strengths (0-5 mol kg-1 NaCl). A ninth measurement using a N2-water system provided a benchmark for capillarity with a strongly water wet system. The capillary pressure curves from each of the tests were found to be similar to the N2-water curve when scaled by the interfacial tension. Reservoir conditions were not found to have a significant impact on the capillary strength of the CO2-brine system during drainage through a variation in the wetting state. Two steady-state relative permeability measurements with CO2 and brine and one with N2 and brine similarly show little variation between conditions, consistent with the observation that the CO2-brine-sandstone system is water wetting and multiphase flow properties invariant across a wide range of reservoir conditions.

  5. Microbial response to salinity change in Lake Chaka, a hypersaline lake on Tibetan plateau.

    PubMed

    Jiang, Hongchen; Dong, Hailiang; Yu, Bingsong; Liu, Xinqi; Li, Yiliang; Ji, Shanshan; Zhang, Chuanlun L

    2007-10-01

    Previous investigations of the salinity effects on the microbial community composition have largely been limited to dynamic estuaries and coastal solar salterns. In this study, the effects of salinity and mineralogy on microbial community composition was studied by using a 900-cm sediment core collected from a stable, inland hypersaline lake, Lake Chaka, on the Tibetan Plateau, north-western China. This core, spanning a time of 17,000 years, was unique in that it possessed an entire range of salinity from freshwater clays and silty sands at the bottom to gypsum and glauberite in the middle, to halite at the top. Bacterial and archaeal communities were studied along the length of this core using an integrated approach combining mineralogy and geochemistry, molecular microbiology (16S rRNA gene analysis and quantitative polymerase chain reaction), cultivation and lipid biomarker analyses. Systematic changes in microbial community composition were correlated with the salinity gradient, but not with mineralogy. Bacterial community was dominated by the Firmicutes-related environmental sequences and known species (including sulfate-reducing bacteria) in the freshwater sediments at the bottom, but by halophilic and halotolerant Betaproteobacteria and Bacteroidetes in the hypersaline sediments at the top. Succession of proteobacterial groups along the salinity gradient, typically observed in free-living bacterial communities, was not observed in the sediment-associated community. Among Archaea, the Crenarchaeota were predominant in the bottom freshwater sediments, but the halophilic Halobacteriales of the Euryarchaeota was the most important group in the hypersaline sediments. Multiple isolates were obtained along the whole length of the core, and their salinity tolerance was consistent with the geochemical conditions. Iron-reducing bacteria were isolated in the freshwater sediments, which were capable of reducing structural Fe(III) in the Fe(III)-rich clay minerals

  6. PHOSPHOROUS AND NITROGEN LIMITATION OF PRIMARY PRODUCTION IN A SIMULATED ESTUARINE GRADIENT

    EPA Science Inventory

    The transition between phosphorus limitation of primary production in freshwater and nitrogen limitation in seawater was examined along an estuarine gradient simulated in 4 large 13 M3 enclosures connected in a series and containing pelagic and benthic subsystems. ominal saliniti...

  7. SMOS sea surface salinity maps of the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Gabarro, Carolina; Olmedo, Estrella; Turiel, Antonio; Ballabrera-Poy, Joaquim; Martinez, Justino; Portabella, Marcos

    2016-04-01

    Salinity and temperature gradients drive the thermohaline circulation of the oceans, and play a key role in the ocean-atmosphere coupling. The strong and direct interactions between the ocean and the cryosphere (primarily through sea ice and ice shelves) is also a key ingredient of the thermohaline circulation. The ESA's Soil Moisture and Ocean Salinity (SMOS) mission, launched in 2009, has the objective measuring soil moisture over the continents and sea surface salinity over the oceans. Although the mission was originally conceived for hydrological and oceanographic studies [1], SMOS is also making inroads in the cryospheric monitoring. SMOS carries an innovative L-band (1.4 GHz, or 21-cm wavelength), passive interferometric radiometer (the so-called MIRAS) that measures the electromagnetic radiation emitted by the Earth's surface, at about 50 km spatial resolution wide swath (1200-km), and with a 3-day revisit time at the equator, but a more frequent one at the poles. Although the SMOS radiometer operating frequency offers almost the maximum sensitivity of the brightness temperature (TB) to sea surface salinity (SSS) variations, this is rather low, , i.e.,: 90% of ocean SSS values span a range of brightness temperatures of only 5K at L-band. This sensitivity is particularly low in cold waters. This implies that the SSS retrieval requires high radiometric performance. Since the SMOS launch, SSS Level 3 maps have been distributed by several expert laboratories including the Barcelona Expert Centre (BEC). However, since the TB sensitivity to SSS decreases with decreasing sea surface temperature (SST), large retrieval errors had been reported when retrieving salinity values at latitudes above 50⁰N. Two new processing algorithms, recently developed at BEC, have led to a considerable improvement of the SMOS data, allowing for the first time to derive SSS maps in cold waters. The first one is to empirically characterize and correct the systematic biases with six

  8. Decline of surface temperature and salinity in the western tropical Pacific Ocean in the Holocene epoch.

    PubMed

    Stott, Lowell; Cannariato, Kevin; Thunell, Robert; Haug, Gerald H; Koutavas, Athanasios; Lund, Steve

    2004-09-01

    In the present-day climate, surface water salinities are low in the western tropical Pacific Ocean and increase towards the eastern part of the basin. The salinity of surface waters in the tropical Pacific Ocean is thought to be controlled by a combination of atmospheric convection, precipitation, evaporation and ocean dynamics, and on interannual timescales significant variability is associated with the El Niño/Southern Oscillation cycles. However, little is known about the variability of the coupled ocean-atmosphere system on timescales of centuries to millennia. Here we combine oxygen isotope and Mg/Ca data from foraminifers retrieved from three sediment cores in the western tropical Pacific Ocean to reconstruct Holocene sea surface temperatures and salinities in the region. We find a decrease in sea surface temperatures of approximately 0.5 degrees C over the past 10,000 yr, whereas sea surface salinities decreased by approximately 1.5 practical salinity units. Our data imply either that the Pacific basin as a whole has become progressively less salty or that the present salinity gradient along the Equator has developed relatively recently. PMID:15343330

  9. Salinity as a constraint on growth of oligohaline marsh macrophytes. I. Species variation in stress tolerance

    USGS Publications Warehouse

    Howard, R.J.; Mendelssohn, I.A.

    1999-01-01

    The effects of increased salinity on plant growth were examined in a greenhouse experiment with four species common to oligohaline marshes of the northern Gulf of Mexico: Eleocharis palustris, Panicum hemitomon, Sagittaria lancifolia, and Scirpus americanus. Effects of final salinity reached (6 or 12 g/L), salinity influx rate (3 d or 3 wk), and duration of exposure (1, 2, or 3 mo) were investigated. Sagittaria lancifolia was the first species to show visible signs of stress, with browning and curling of older leaf edges. The salt effect was delayed for 6-8 wk in P. hemitomon, but this species had the highest aboveground tissue mortality rate at 12 g/L as exposure continued. Final salt concentration affected all species to a greater degree than did salinity influx rate. No aboveground mortality occurred at 6 g/L, but growth suppression was apparent and varied with species. The magnitude of growth suppression in response to salinity increased for all species as the duration of exposure increased. Overall, we ranked the species as follows, in order from least to most salt tolerant: Panicum hemitomon < Sagittaria lancifolia < Eleocharis palustris < Scirpus americanus. This ranking reflects the field occurrence of these species along a gradient of increasing salinity in northern Gulf of Mexico coastal habitats from freshwater wetlands through oligohaline areas to mesohaline wetlands.

  10. Messinian Salinity Crisis and basin fluid flow

    NASA Astrophysics Data System (ADS)

    Bertoni, Claudia; Cartwight, Joe

    2014-05-01

    Syn- and post-depositional movement of fluids through sediments is one of the least understood aspects in the evolution of a basin. The conventional hydrostratigraphic view on marine sedimentary basins assumes that compactional and meteoric groundwater fluid circulation drives fluid movement and defines its timing. However, in the past few years, several examples of instantaneous and catastrophic release of fluids have been observed even through low-permeability sediments. A particularly complex case-study involves the presence of giant salt bodies in the depocentres of marine basins. Evaporites dramatically change the hydrostratigraphy and fluid-dynamics of the basin, and influence the P/T regimes, e.g. through changes in the geothermal gradient and in the compaction of underlying sediments. Our paper reviews the impact of the Messinian Salinity Crisis (MSC) and evaporites on fluid flow in the Mediterranean sub-basins. The analysis of geological and geophysical sub-surface data provides examples from this basin, and the comparison with analogues in other well-known evaporitic provinces. During the MSC, massive sea-level changes occurred in a relatively limited time interval, and affected the balance of fluid dynamics, e.g. with sudden release or unusual trapping of fluids. Fluid expulsion events are here analysed and classified in relation to the long and short-term effects of the MSC. Our main aim is to build a framework for the correct identification of the fluid flow-related events, and their genetic mechanisms. On basin margins, where evaporites are thin or absent, the sea-level changes associated with the MSC force a rapid basinward shift of the mixing zone of meteoric/gravity flow and saline/compactional flow, 100s-km away from its pre-MSC position. This phenomenon changes the geometry of converging flows, creates hydraulic traps for fluids, and triggers specific diagenetic reactions in pre-MSC deep marine sediments. In basin-centre settings, unloading and

  11. Shrinkage stress in concrete under dry-wet cycles: an example with concrete column

    NASA Astrophysics Data System (ADS)

    Gao, Yuan; Zhang, Jun; Luosun, Yiming

    2014-02-01

    This paper focuses on the simulation of shrinkage stress in concrete structures under dry-wet environments. In the modeling, an integrative model for autogenous and drying shrinkage predictions of concrete under dry-wet cycles is introduced first. Second, a model taking both cement hydration and moisture diffusion into account synchronously is used to calculate the distribution of interior humidity in concrete. Using the above two models, the distributions of shrinkage strain and stress in concrete columns made by normal and high strength concrete respectively under dry-wet cycles are calculated. The model results show that shrinkage gradient along the radial direction of the column from the center to outer surface increases with age as the outer circumference suffers to dry. The maximum and minimum shrinkage occur at the outer surface and the center of the column, respectively, under drying condition. As wetting starts, the shrinkage strain decreases with increase of interior humidity. The closer to the wetting face, the higher the humidity and the lower the shrinkage strain, as well as the lower the shrinkage stress. As results of the dry-wet cycles acting on the outer circumference of the column, cyclic stress status is developed within the area close to the outer surface of the column. The depth of the influencing zone of dry-wet cyclic action is influenced by concrete strength and dry-wet regime. For low strength concrete, relatively deeper influencing zone is expected compared with that of high strength concrete. The models are verified by concrete-steel composite ring tests and a good agreement between model and test results is found.

  12. Wet-Etch Figuring Optical Figuring by Controlled Application of Liquid Etchant

    SciTech Connect

    Britten, J

    2001-02-13

    WET-ETCH FIGURING (WEF) is an automated method of precisely figuring optical materials by the controlled application of aqueous etchant solution. This technology uses surface-tension-gradient-driven flow to confine and stabilize a wetted zone of an etchant solution or other aqueous processing fluid on the surface of an object. This wetted zone can be translated on the surface in a computer-controlled fashion for precise spatial control of the surface reactions occurring (e.g. chemical etching). WEF is particularly suitable for figuring very thin optical materials because it applies no thermal or mechanical stress to the material. Also, because the process is stress-free the workpiece can be monitored during figuring using interferometric metrology, and the measurements obtained can be used to control the figuring process in real-time--something that cannot be done with traditional figuring methods.

  13. Cavitation as a Mechanism to Enhance Wetting in a Mercury Thermal Convection Loop

    SciTech Connect

    Pawel, SJ

    2001-07-17

    Type 316L stainless steel was statically tested under cavitation conditions via an ultrasonic transducer externally mounted on a tube filled with ambient mercury. During the preliminary exposure (24 h, 20 kHz, 1.5 MPa), cavitation resulted in apparent wetting of the specimens by mercury as well as general surface roughening and wastage similar to erosion damage. Subsequently, a thermal convection loop identical to those used previously to study thermal gradient mass transfer was modified to include an externally-mounted donut-shaped transducer in order to similarly produce cavitation and wetting at temperatures prototypic of those expected in the SNS target. However, a series of attempts to develop cavitation and wetting on 316L specimens in the thermal convection loop was unsuccessful.

  14. Wet runways. [aircraft landing and directional control

    NASA Technical Reports Server (NTRS)

    Horne, W. B.

    1975-01-01

    Aircraft stopping and directional control performance on wet runways is discussed. The major elements affecting tire/ground traction developed by jet transport aircraft are identified and described in terms of atmospheric, pavement, tire, aircraft system and pilot performance factors or parameters. Research results are summarized, and means for improving or restoring tire traction/aircraft performance on wet runways are discussed.

  15. 7 CFR 29.2316 - Wet (W).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Wet (W). 29.2316 Section 29.2316 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2316 Wet...

  16. 7 CFR 29.3567 - Wet (W).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Wet (W). 29.3567 Section 29.3567 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3567 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  17. 7 CFR 29.2570 - Wet (W).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Wet (W). 29.2570 Section 29.2570 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2570 Wet (W). Any sound tobacco...

  18. 7 CFR 29.1083 - Wet (W).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Wet (W). 29.1083 Section 29.1083 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1083 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  19. 7 CFR 29.3077 - Wet (W).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Wet (W). 29.3077 Section 29.3077 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Wet (W). Any sound tobacco containing excessive moisture to the extent that it is in an unsafe...

  20. 7 CFR 29.3077 - Wet (W).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Wet (W). 29.3077 Section 29.3077 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Wet (W). Any sound tobacco containing excessive moisture to the extent that it is in an unsafe...

  1. 7 CFR 29.3567 - Wet (W).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Wet (W). 29.3567 Section 29.3567 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3567 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  2. 7 CFR 29.3077 - Wet (W).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.3077 Section 29.3077 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Wet (W). Any sound tobacco containing excessive moisture to the extent that it is in an unsafe...

  3. 7 CFR 29.3077 - Wet (W).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Wet (W). 29.3077 Section 29.3077 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Wet (W). Any sound tobacco containing excessive moisture to the extent that it is in an unsafe...

  4. 7 CFR 29.2316 - Wet (W).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Wet (W). 29.2316 Section 29.2316 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2316 Wet...

  5. 7 CFR 29.2316 - Wet (W).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Wet (W). 29.2316 Section 29.2316 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2316 Wet...

  6. 7 CFR 29.2570 - Wet (W).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Wet (W). 29.2570 Section 29.2570 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2570 Wet (W). Any sound tobacco...

  7. 7 CFR 29.2316 - Wet (W).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Wet (W). 29.2316 Section 29.2316 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2316 Wet...

  8. 7 CFR 29.3077 - Wet (W).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Wet (W). 29.3077 Section 29.3077 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Wet (W). Any sound tobacco containing excessive moisture to the extent that it is in an unsafe...

  9. 7 CFR 29.2316 - Wet (W).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.2316 Section 29.2316 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2316 Wet...

  10. 7 CFR 29.3567 - Wet (W).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Wet (W). 29.3567 Section 29.3567 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3567 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  11. 7 CFR 29.1083 - Wet (W).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Wet (W). 29.1083 Section 29.1083 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1083 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  12. 7 CFR 29.3567 - Wet (W).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Wet (W). 29.3567 Section 29.3567 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3567 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  13. 7 CFR 29.1083 - Wet (W).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Wet (W). 29.1083 Section 29.1083 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1083 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  14. 7 CFR 29.1083 - Wet (W).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Wet (W). 29.1083 Section 29.1083 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1083 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  15. 7 CFR 29.2570 - Wet (W).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.2570 Section 29.2570 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2570 Wet (W). Any sound tobacco...

  16. 7 CFR 29.3567 - Wet (W).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.3567 Section 29.3567 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3567 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  17. 7 CFR 29.1083 - Wet (W).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.1083 Section 29.1083 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1083 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  18. 7 CFR 29.2570 - Wet (W).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Wet (W). 29.2570 Section 29.2570 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2570 Wet (W). Any sound tobacco...

  19. 7 CFR 29.2570 - Wet (W).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Wet (W). 29.2570 Section 29.2570 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2570 Wet (W). Any sound tobacco...

  20. Non Linear Conjugate Gradient

    Energy Science and Technology Software Center (ESTSC)

    2006-11-17

    Software that simulates and inverts electromagnetic field data for subsurface electrical properties (electrical conductivity) of geological media. The software treats data produced by a time harmonic source field excitation arising from the following antenna geometery: loops and grounded bipoles, as well as point electric and magnetic dioples. The inversion process is carried out using a non-linear conjugate gradient optimization scheme, which minimizes the misfit between field data and model data using a least squares criteria.more » The software is an upgrade from the code NLCGCS_MP ver 1.0. The upgrade includes the following components: Incorporation of new 1 D field sourcing routines to more accurately simulate the 3D electromagnetic field for arbitrary geologic& media, treatment for generalized finite length transmitting antenna geometry (antennas with vertical and horizontal component directions). In addition, the software has been upgraded to treat transverse anisotropy in electrical conductivity.« less

  1. Tectorial Membrane Stiffness Gradients

    PubMed Central

    Richter, Claus-Peter; Emadi, Gulam; Getnick, Geoffrey; Quesnel, Alicia; Dallos, Peter

    2007-01-01

    The mammalian inner ear processes sound with high sensitivity and fine resolution over a wide frequency range. The underlying mechanism for this remarkable ability is the “cochlear amplifier”, which operates by modifying cochlear micromechanics. However, it is largely unknown how the cochlea implements this modification. Although gradual improvements in experimental techniques have yielded ever-better descriptions of gross basilar membrane vibration, the internal workings of the organ of Corti and of the tectorial membrane have resisted exploration. Although measurements of cochlear function in mice with a gene mutation for α-tectorin indicate the tectorial membrane's key role in the mechanoelectrical transformation by the inner ear, direct experimental data on the tectorial membrane's physical properties are limited, and only a few direct measurements on tectorial micromechanics are available. Using the hemicochlea, we are able to show that a tectorial membrane stiffness gradient exists along the cochlea, similar to that of the basilar membrane. In artificial perilymph (but with low calcium), the transversal and radial driving point stiffnesses change at a rate of –4.0 dB/mm and −4.9 dB/mm, respectively, along the length of the cochlear spiral. In artificial endolymph, the stiffness gradient for the transversal component was –3.4 dB/mm. Combined with the changes in tectorial membrane dimensions from base to apex, the radial stiffness changes would be able to provide a second frequency-place map in the cochlea. Young's modulus, which was obtained from measurements performed in the transversal direction, decreased by −2.6 dB/mm from base to apex. PMID:17496047

  2. Generalized conjugate gradient squared

    SciTech Connect

    Fokkema, D.R.; Sleijpen, G.L.G.

    1994-12-31

    In order to solve non-symmetric linear systems of equations, the Conjugate Gradient Squared (CGS) is a well-known and widely used iterative method. In practice the method converges fast, often twice as fast as the Bi-Conjugate Gradient method. This is what you may expect, since CGS uses the square of the BiCG polynomial. However, CGS may suffer from its erratic convergence behavior. The method may diverge or the approximate solution may be inaccurate. BiCGSTAB uses the BiCG polynomial and a product of linear factors in an attempt to smoothen the convergence. In many cases, this has proven to be very effective. Unfortunately, the convergence of BiCGSTAB may stall when a linear factor (nearly) degenerates. BiCGstab({ell}) is designed to overcome this degeneration of linear factors. It generalizes BiCGSTAB and uses both the BiCG polynomial and a product of higher order factors. Still, CGS may converge faster than BiCGSTAB or BiCGstab({ell}). So instead of using a product of linear or higher order factors, it may be worthwhile to look for other polynomials. Since the BiCG polynomial is based on a three term recursion, a natural choice would be a polynomial based on another three term recursion. Possibly, a suitable choice of recursion coefficients would result in method that converges faster or as fast as CGS, but less erratic. It turns out that an algorithm for such a method can easily be formulated. One particular choice for the recursion coefficients leads to CGS. Therefore one could call this algorithm generalized CGS. Another choice for the recursion coefficients leads to BiCGSTAB. It is therefore possible to mix linear factors and some polynomial based on a three term recursion. This way one may get the best of both worlds. The authors will report on their findings.

  3. Global Scale Variation in the Salinity Sensitivity of Riverine Macroinvertebrates: Eastern Australia, France, Israel and South Africa

    PubMed Central

    Kefford, Ben J.; Hickey, Graeme L.; Gasith, Avital; Ben-David, Elad; Dunlop, Jason E.; Palmer, Carolyn G.; Allan, Kaylene; Choy, Satish C.; Piscart, Christophe

    2012-01-01

    Salinity is a key abiotic property of inland waters; it has a major influence on biotic communities and is affected by many natural and anthropogenic processes. Salinity of inland waters tends to increase with aridity, and biota of inland waters may have evolved greater salt tolerance in more arid regions. Here we compare the sensitivity of stream macroinvertebrate species to salinity from a relatively wet region in France (Lorraine and Brittany) to that in three relatively arid regions eastern Australia (Victoria, Queensland and Tasmania), South Africa (south-east of the Eastern Cape Province) and Israel using the identical experimental method in all locations. The species whose salinity tolerance was tested, were somewhat more salt tolerant in eastern Australia and South Africa than France, with those in Israel being intermediate. However, by far the greatest source of variation in species sensitivity was between taxonomic groups (Order and Class) and not between the regions. We used a Bayesian statistical model to estimate the species sensitivity distributions (SSDs) for salinity in eastern Australia and France adjusting for the assemblages of species in these regions. The assemblage in France was slightly more salinity sensitive than that in eastern Australia. We therefore suggest that regional salinity sensitivity is therefore likely to depend most on the taxonomic composition of respective macroinvertebrate assemblages. On this basis it would be possible to screen rivers globally for risk from salinisation. PMID:22567097

  4. Chronic hypoxia and low salinity impair anti-predatory responses of the green-lipped mussel Perna viridis.

    PubMed

    Wang, Youji; Hu, Menghong; Cheung, S G; Shin, P K S; Lu, Weiqun; Li, Jiale

    2012-06-01

    The effects of chronic hypoxia and low salinity on anti-predatory responses of the green-lipped mussel Perna viridis were investigated. Dissolved oxygen concentrations ranged from hypoxic to normoxic (1.5 ± 0.3 mg l(-1), 3.0 ± 0.3 mg l(-1) and 6.0 ± 0.3 mg l(-1)), and salinities were selected within the variation during the wet season in Hong Kong coastal waters (15‰, 20‰, 25‰ and 30‰). The dissolved oxygen and salinity significantly affected some anti-predatory responses of mussel, including byssus production, shell thickness and shell weight, and the adductor diameter was only significantly affected by salinity. Besides, interactive effects of dissolved oxygen and salinity on the byssus production and shell thickness were also observed. In hypoxic and low salinity conditions, P. viridis produced fewer byssal threads, thinner shell and adductor muscle, indicating that hypoxia and low salinity are severe environmental stressors for self-defence of mussel, and their interactive effects further increase the predation risk. PMID:22405812

  5. Global scale variation in the salinity sensitivity of riverine macroinvertebrates: eastern Australia, France, Israel and South Africa.

    PubMed

    Kefford, Ben J; Hickey, Graeme L; Gasith, Avital; Ben-David, Elad; Dunlop, Jason E; Palmer, Carolyn G; Allan, Kaylene; Choy, Satish C; Piscart, Christophe

    2012-01-01

    Salinity is a key abiotic property of inland waters; it has a major influence on biotic communities and is affected by many natural and anthropogenic processes. Salinity of inland waters tends to increase with aridity, and biota of inland waters may have evolved greater salt tolerance in more arid regions. Here we compare the sensitivity of stream macroinvertebrate species to salinity from a relatively wet region in France (Lorraine and Brittany) to that in three relatively arid regions eastern Australia (Victoria, Queensland and Tasmania), South Africa (south-east of the Eastern Cape Province) and Israel using the identical experimental method in all locations. The species whose salinity tolerance was tested, were somewhat more salt tolerant in eastern Australia and South Africa than France, with those in Israel being intermediate. However, by far the greatest source of variation in species sensitivity was between taxonomic groups (Order and Class) and not between the regions. We used a bayesian statistical model to estimate the species sensitivity distributions (SSDs) for salinity in eastern Australia and France adjusting for the assemblages of species in these regions. The assemblage in France was slightly more salinity sensitive than that in eastern Australia. We therefore suggest that regional salinity sensitivity is therefore likely to depend most on the taxonomic composition of respective macroinvertebrate assemblages. On this basis it would be possible to screen rivers globally for risk from salinisation. PMID:22567097

  6. Composition and distribution of planktonic ciliates from ponds of different salinity in the solar saltwork of Sfax, Tunisia

    NASA Astrophysics Data System (ADS)

    Elloumi, Jannet; Carrias, Jean-François; Ayadi, Habib; Sime-Ngando, Télesphore; Boukhris, Mekki; Bouaïn, Abderrahmen

    2006-03-01

    The planktonic ciliated protozoa of 14 ponds of increasing salinity were investigated in the saline of Sfax, Tunisia. Taxa of the classes of Spirotrichea and Heterotrichea were the numerous ciliates. Abundance of the community ranged from 0.0 to 11.8 × 10 4 ciliates per litre. Values decrease significantly with salinity gradient, as species richness does. Based on the range of salinity over which ciliate taxa appeared, we distinguished three groups of ciliates. The first group is mainly composed of oligotrichs and choreotrichs that are commonly found in marine coastal waters. Small ciliates belonging to the order Prostomatida were found in a large range of salinity values, but their densities also decreased with salt concentration. In contrast, large-size species of heterotrichous ciliates were found in ponds with high salinity values only. In these ponds, the presence of prey appeared as an important factor in controlling the abundances of these halotolerant ciliates. Our data also suggest that Fabrea salina, a common halophile ciliate, acts as a competitor of the brine shrimp Artemia salina in the saline of Sfax. Salinity, prey availability, and the presence of competitors seem to be the main factors for the distribution of ciliate taxa in this hypersaline environment.

  7. Development of a Coastal Drought Index Using Salinity Data

    NASA Astrophysics Data System (ADS)

    Conrads, P. A.; Darby, L. S.

    2014-12-01

    The freshwater-saltwater interface in surface-water bodies along the coast is an important factor in the ecological and socio-economic dynamics of coastal communities. It influences community composition in freshwater and saltwater ecosystems, determines fisheries spawning habitat, and controls freshwater availability for municipal and industrial water intakes. These dynamics may be affected by coastal drought through changes in Vibrio bacteria impacts on shellfish harvesting and occurrence of wound infection, fish kills, harmful algal blooms, hypoxia, and beach closures. There are many definitions of drought, with most describing a decline in precipitation having negative impacts on water supply and agriculture. Four general types of drought are recognized: hydrological, agricultural, meteorological, and socio-economic. Indices have been developed for these drought types incorporating data such as rainfall, streamflow, soil moisture, groundwater levels, and snow pack. These indices were developed for upland areas and may not be appropriate for characterizing drought in coastal areas. Because of the uniqueness of drought impacts on coastal ecosystems, a need exists to develop a coastal drought index. The availability of real-time and historical salinity datasets provides an opportunity to develop a salinity-based coastal drought index. The challenge of characterizing salinity dynamics in response to drought is excluding responses attributable to occasional saltwater intrusion events. Our approach to develop a coastal drought index modified the Standardized Precipitation Index and applied it to sites in South Carolina and Georgia, USA. Coastal drought indices characterizing 1-, 3-, 6-, 9-, and12-month drought conditions were developed. Evaluation of the coastal drought index indicates that it can be used for different estuary types, for comparison between estuaries, and as an index for wet conditions (high freshwater inflow) in addition to drought conditions.

  8. Wet meadow ecosystems contribute the majority of overwinter soil respiration from snow-scoured alpine tundra

    NASA Astrophysics Data System (ADS)

    Knowles, John F.; Blanken, Peter D.; Williams, Mark W.

    2016-04-01

    We measured soil respiration across a soil moisture gradient ranging from dry to wet snow-scoured alpine tundra soils throughout three winters and two summers. In the absence of snow accumulation, soil moisture variability was principally determined by the combination of mesotopographical hydrological focusing and shallow subsurface permeability, which resulted in a patchwork of comingled ecosystem types along a single alpine ridge. To constrain the subsequent carbon cycling variability, we compared three measures of effective diffusivity and three methods to calculate gradient method soil respiration from four typical vegetation communities. Overwinter soil respiration was primarily restricted to wet meadow locations, and a conservative estimate of the rate of overwinter soil respiration from snow-scoured wet meadow tundra was 69-90% of the maximum carbon dioxide (CO2) respired by seasonally snow-covered soils within this same catchment. This was attributed to higher overwinter soil temperatures at wet meadow locations relative to fellfield, dry meadow, and moist meadow communities, which supported liquid water and heterotrophic respiration throughout the winter. These results were corroborated by eddy covariance-based measurements that demonstrated an average of 272 g C m-2 overwinter carbon loss during the study period. As a result, we updated a conceptual model of soil respiration versus snow cover to express the potential for soil respiration variability from snow-scoured alpine tundra.

  9. Thin wetting film lensless imaging

    NASA Astrophysics Data System (ADS)

    Allier, C. P.; Poher, V.; Coutard, J. G.; Hiernard, G.; Dinten, J. M.

    2011-03-01

    Lensless imaging has recently attracted a lot of attention as a compact, easy-to-use method to image or detect biological objects like cells, but failed at detecting micron size objects like bacteria that often do not scatter enough light. In order to detect single bacterium, we have developed a method based on a thin wetting film that produces a micro-lens effect. Compared with previously reported results, a large improvement in signal to noise ratio is obtained due to the presence of a micro-lens on top of each bacterium. In these conditions, standard CMOS sensors are able to detect single bacterium, e.g. E.coli, Bacillus subtilis and Bacillus thuringiensis, with a large signal to noise ratio. This paper presents our sensor optimization to enhance the SNR; improve the detection of sub-micron objects; and increase the imaging FOV, from 4.3 mm2 to 12 mm2 to 24 mm2, which allows the detection of bacteria contained in 0.5μl to 4μl to 10μl, respectively.

  10. Precursor films in wetting phenomena.

    PubMed

    Popescu, M N; Oshanin, G; Dietrich, S; Cazabat, A-M

    2012-06-20

    The spontaneous spreading of non-volatile liquid droplets on solid substrates poses a classic problem in the context of wetting phenomena. It is well known that the spreading of a macroscopic droplet is in many cases accompanied by a thin film of macroscopic lateral extent, the so-called precursor film, which emanates from the three-phase contact line region and spreads ahead of the latter with a much higher speed. Such films have been usually associated with liquid-on-solid systems, but in the last decade similar films have been reported to occur in solid-on-solid systems. While the situations in which the thickness of such films is of mesoscopic size are fairly well understood, an intriguing and yet to be fully understood aspect is the spreading of microscopic, i.e. molecularly thin, films. Here we review the available experimental observations of such films in various liquid-on-solid and solid-on-solid systems, as well as the corresponding theoretical models and studies aimed at understanding their formation and spreading dynamics. Recent developments and perspectives for future research are discussed. PMID:22627067

  11. Dynamic wetting at the nanoscale

    NASA Astrophysics Data System (ADS)

    Amberg, Gustav; Nakamura, Yoshinori; Carlson, Andreas; Shiomi, Junichiro

    2013-11-01

    Although the capillary spreading of a drop on a dry substrate is well studied, the physical mechanisms that govern the dynamics remain challenging. Here we study the dynamics of spreading of partially wetting nano-droplets, by combining molecular dynamics and continuum simulations. The latter accounts for all the relevant hydrodynamics, i.e. capillarity, inertia and viscous stresses. By coordinated continuum and molecular dynamics simulations, the macroscopic model parameters are extracted. For a Lennard-Jones fluid spreading on a planar surface, the liquid slip on the substrate is found to be crucial for the motion of the contact line. Evaluation of the different contributions to the energy transfer shows that the liquid slip generates dissipation of the same order as the bulk viscous dissipation or the energy transfer to kinetic energy. We also study the dynamics of spreading on a substrate with a periodic nanostructure. Here it is found that a nanostructure with a length scale commensurate with molecular size completely inhibits the liquid slip. This reduces the spreading speed by about 30%. This work is partially supported by the Japan Science and Technology Agency, CREST, the Swedish Research Council, the Japan Society for the Promotion of Science, and the Sasakawa foundation.

  12. Response of biotic communities to salinity changes in a Mediterranean hypersaline stream

    PubMed Central

    Velasco, Josefa; Millán, Andrés; Hernández, Juan; Gutiérrez, Cayetano; Abellán, Pedro; Sánchez, David; Ruiz, Mar

    2006-01-01

    Background This study investigates the relationship between salinity and biotic communities (primary producers and macroinvertebrates) in Rambla Salada, a Mediterranean hypersaline stream in SE Spain. Since the 1980's, the mean salinity of the stream has fallen from about 100 g L-1 to 35.5 g L-1, due to intensive irrigated agriculture in the watershed. Furthermore, large dilutions occur occasionally when the water irrigation channel suffers cracks. Results Along the salinity gradient studied (3.5 – 76.4 g L-1) Cladophora glomerata and Ruppia maritima biomass decreased with increasing salinity, while the biomass of epipelic algae increased. Diptera and Coleoptera species dominated the community both in disturbed as in re-established conditions. Most macroinvertebrates species found in Rambla Salada stream are euryhaline species with a broad range of salinity tolerance. Eight of them were recorded in natural hypersaline conditions (~100 g L-1) prior to important change in land use of the watershed: Ephydra flavipes, Stratyomis longicornis, Nebrioporus ceresyi, N. baeticus, Berosus hispanicus, Enochrus falcarius, Ochthebius cuprescens and Sigara selecta. However, other species recorded in the past, such as Ochthebius glaber, O. notabilis and Enochrus politus, were restricted to a hypersaline source or absent from Rambla Salada. The dilution of salinity to 3.5 – 6.8 gL-1 allowed the colonization of species with low salininty tolerance, such as Melanopsis praemorsa, Anax sp., Simulidae, Ceratopogonidae and Tanypodinae. The abundance of Ephydra flavipes and Ochthebius corrugatus showed a positive significant response to salinity, while Anax sp., Simulidae, S. selecta, N. ceresyi, N. baeticus, and B. hispanicus showed significant negative correlations. The number of total macroinvertebrate taxa, Diptera and Coleoptera species, number of families, Margalef's index and Shannon's diversity index decreased with increasing salinity. However, the rest of community

  13. Disentangling Diversity Patterns in Sandy Beaches along Environmental Gradients

    PubMed Central

    Barboza, Francisco R.; Gómez, Julio; Lercari, Diego; Defeo, Omar

    2012-01-01

    Species richness in sandy beaches is strongly affected by concurrent variations in morphodynamics and salinity. However, as in other ecosystems, different groups of species may exhibit contrasting patterns in response to these environmental variables, which would be obscured if only aggregate richness is considered. Deconstructing biodiversity, i.e. considering richness patterns separately for different groups of species according to their taxonomic affiliation, dispersal mode or mobility, could provide a more complete understanding about factors that drive species richness patterns. This study analyzed macroscale variations in species richness at 16 Uruguayan sandy beaches with different morphodynamics, distributed along the estuarine gradient generated by the Rio de la Plata over a 2 year period. Species richness estimates were deconstructed to discriminate among taxonomic groups, supralittoral and intertidal forms, and groups with different feeding habits and development modes. Species richness was lowest at intermediate salinities, increasing towards oceanic and inner estuarine conditions, mainly following the patterns shown for intertidal forms. Moreover, there was a differential tolerance to salinity changes according to the habitat occupied and development mode, which determines the degree of sensitivity of faunal groups to osmotic stress. Generalized (additive and linear) mixed models showed a clear increase of species richness towards dissipative beaches. All taxonomic categories exhibited the same trend, even though responses to grain size and beach slope were less marked for crustaceans and insects than for molluscs or polychaetes. However, supralittoral crustaceans exhibited the opposite trend. Feeding groups decreased from dissipative to reflective systems, deposit feeders being virtually absent in the latter. This deconstructive approach highlights the relevance of life history strategies in structuring communities, highlighting the relative

  14. Disentangling diversity patterns in sandy beaches along environmental gradients.

    PubMed

    Barboza, Francisco R; Gómez, Julio; Lercari, Diego; Defeo, Omar

    2012-01-01

    Species richness in sandy beaches is strongly affected by concurrent variations in morphodynamics and salinity. However, as in other ecosystems, different groups of species may exhibit contrasting patterns in response to these environmental variables, which would be obscured if only aggregate richness is considered. Deconstructing biodiversity, i.e. considering richness patterns separately for different groups of species according to their taxonomic affiliation, dispersal mode or mobility, could provide a more complete understanding about factors that drive species richness patterns. This study analyzed macroscale variations in species richness at 16 Uruguayan sandy beaches with different morphodynamics, distributed along the estuarine gradient generated by the Rio de la Plata over a 2 year period. Species richness estimates were deconstructed to discriminate among taxonomic groups, supralittoral and intertidal forms, and groups with different feeding habits and development modes. Species richness was lowest at intermediate salinities, increasing towards oceanic and inner estuarine conditions, mainly following the patterns shown for intertidal forms. Moreover, there was a differential tolerance to salinity changes according to the habitat occupied and development mode, which determines the degree of sensitivity of faunal groups to osmotic stress. Generalized (additive and linear) mixed models showed a clear increase of species richness towards dissipative beaches. All taxonomic categories exhibited the same trend, even though responses to grain size and beach slope were less marked for crustaceans and insects than for molluscs or polychaetes. However, supralittoral crustaceans exhibited the opposite trend. Feeding groups decreased from dissipative to reflective systems, deposit feeders being virtually absent in the latter. This deconstructive approach highlights the relevance of life history strategies in structuring communities, highlighting the relative

  15. Compositional gradients in photopolymer films utilizing kinetic driving forces

    NASA Astrophysics Data System (ADS)

    Cook, Clinton John

    Independent control of the surface and bulk properties is advantageous for many applications such as adhesives, release coatings, and antimicrobial films. Traditional methods for achieving independent control typically require multiple processing steps such as wet-on-wet or wet-on-dry coating methods. Independent control over the surface properties can achieved in a single step utilizing the temporal and spatial control inherent to photopolymerization. Specifically, a co-photopolymerization of monomers with different reactivities in the presence of a light gradient is capable of producing a polymer film with a surface chemistry that differs from the bulk chemistry. The light gradient, produced via the concentration of photoinitiator in the formulation, results in a reaction gradient through the film with the higher rates of reaction occurring in the high light intensity regions of the film. The preferentially reacting monomer adds at a greater rate in the high light intensity regions resulting in non-uniform consumption yielding a concentration gradient. Consequently, diffusion of the preferentially reacting monomer from the bulk to the surface of the film and a counter-diffusion of the other monomer from the surface to the bulk of the film occurs from the non-uniform monomer consumption thus producing a film with a concentration gradient through the depth of the film with the preferentially reacting monomer enriching the high light intensity regions. A variety of kinetic differences capable of producing a stratified film will be presented including inherent monomer reactivity, number of functional groups per monomer, oxygen inhibition, thiol-ene chemistry, and Norrish type two initiation. Additionally, parameters that control the degree of stratification, such as methods of varying polymerization rate and the light gradient, will be examined. Changes in surface properties (such as contact angle, surface hardness, adhesion) and bulk properties (such as mechanical

  16. Importance of plasticity and local adaptation for coping with changing salinity in coastal areas: a test case with barnacles in the Baltic Sea

    PubMed Central

    2014-01-01

    Background Salinity plays an important role in shaping coastal marine communities. Near-future climate predictions indicate that salinity will decrease in many shallow coastal areas due to increased precipitation; however, few studies have addressed this issue. The ability of ecosystems to cope with future changes will depend on species’ capacities to acclimatise or adapt to new environmental conditions. Here, we investigated the effects of a strong salinity gradient (the Baltic Sea system – Baltic, Kattegat, Skagerrak) on plasticity and adaptations in the euryhaline barnacle Balanus improvisus. We used a common-garden approach, where multiple batches of newly settled barnacles from each of three different geographical areas along the Skagerrak-Baltic salinity gradient were exposed to corresponding native salinities (6, 15 and 30 PSU), and phenotypic traits including mortality, growth, shell strength, condition index and reproductive maturity were recorded. Results We found that B. improvisus was highly euryhaline, but had highest growth and reproductive maturity at intermediate salinities. We also found that low salinity had negative effects on other fitness-related traits including initial growth and shell strength, although mortality was also lowest in low salinity. Overall, differences between populations in most measured traits were weak, indicating little local adaptation to salinity. Nonetheless, we observed some population-specific responses – notably that populations from high salinity grew stronger shells in their native salinity compared to the other populations, possibly indicating adaptation to differences in local predation pressure. Conclusions Our study shows that B. improvisus is an example of a true brackish-water species, and that plastic responses are more likely than evolutionary tracking in coping with future changes in coastal salinity. PMID:25038588

  17. Aquarius surface salinity and the Madden-Julian Oscillation: The role of salinity in surface layer density and potential energy

    NASA Astrophysics Data System (ADS)

    Guan, Bin; Lee, Tong; Halkides, Daria J.; Waliser, Duane E.

    2014-04-01

    Sea surface salinity (SSS) data from the Aquarius satellite are analyzed along with auxiliary data to investigate the SSS signature of the Madden-Julian Oscillation (MJO) in the equatorial Indian and Pacific Oceans, the effect of evaporation-minus-precipitation (E-P), the implication for the role of ocean dynamics, and the SSS influence on surface density and potential energy. MJO-related SSS changes are consistent with E-P forcing in the western Indian Ocean throughout the MJO cycle and in the central Indian Ocean during the wet phase of the MJO cycle. However, SSS changes cannot be explained by E-P in the central Indian Ocean during the dry phase and in the eastern Indian and western Pacific Oceans throughout the MJO cycle, implying the importance of ocean dynamics. SSS has an overall larger contribution to MJO-related surface density and potential energy anomalies than SST. It partially offsets the SST effect in the western-to-central Indian Ocean and reinforces the SST effect in the eastern Indian and western Pacific Oceans. Ocean modeling and assimilation need to properly account for salinity effects in order to correctly represent mixed layer variability associated with the MJO. Our results also clarify some discrepancy in previous studies about the E-P effect on MJO-related SSS variations.

  18. Estuarine turbidity, flushing, salinity, and circulation

    NASA Technical Reports Server (NTRS)

    Pritchard, D. W.

    1972-01-01

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

  19. Early life history responses of tidal wetland plants to sea-level rise and salinization in the Pacific Northwest

    EPA Science Inventory

    Climate change is likely to alter the spatial distribution of abiotic gradients in estuaries, potentially increasing stress in tidal wetland plants. Using field and lab manipulations, we examined inter-specific variation in responses to elevated salinity and inundation in the Ore...

  20. Separating natural and contaminant related gradients in estuarine macrobenthic community structure

    SciTech Connect

    Rakocinski, C.; Heard, R.; Walker, W.; Brown, S.; Gaston, G.; Summers, J.K.

    1995-12-31

    Using whole-community macrobenthic responses to assess pollution impacts in estuaries presents a difficult challenge due to dynamic natural conditions that may impose their own physical limitations on the biota. For example, the recognition of bioindicator taxa becomes confounded when correlations exist between gradients in natural environmental variables, such as salinity, and gradients in contaminants, such as trace metals. The authors used partial Canonical Correspondence Analysis (CCA) to separate natural and contaminant related gradients in macrobenthic community structure across 319 EMAP sites dispersed throughout the northern Gulf of Mexico. Residual variation in macrobenthic community structure was examined with respect to gradients in contaminant levels to identify responses by positive and negative bioindicator taxa. Gradients in concentrations of trace metals do not coincide completely with those in other chemical contaminants, and responses by characteristic bioindicator taxa reveal information regarding effects of specific contaminants. Several indigenous taxa serve as good negative bioindicators, whereas other opportunistic taxa serve as positive bioindicators of estuarine contamination.

  1. Fresh meteoric versus recirculated saline groundwater nutrient inputs into a subtropical estuary.

    PubMed

    Sadat-Noori, Mahmood; Santos, Isaac R; Tait, Douglas R; Maher, Damien T

    2016-10-01

    The role of groundwater in transporting nutrients to coastal aquatic systems has recently received considerable attention. However, the relative importance of fresh versus saline groundwater-derived nutrient inputs to estuaries and how these groundwater pathways may alter surface water N:P ratios remains poorly constrained. We performed detailed time series measurements of nutrients in a tidal estuary (Hat Head, NSW, Australia) and used radium to quantify the contribution of fresh and saline groundwater to total surface water estuarine exports under contrasting hydrological conditions (wet and dry season). Tidally integrated nutrient fluxes showed that the estuary was a source of nutrients to the coastal waters. Dissolved inorganic nitrogen (DIN) export was 7-fold higher than the average global areal flux rate for rivers likely due to the small catchment size, surrounding wetlands and high groundwater inputs. Fresh groundwater discharge was dominant in the wet season accounting for up to 45% of total dissolved nitrogen (TDN) and 48% of total dissolved phosphorus (TDP) estuarine exports. In the dry season, fresh and saline groundwater accounted for 21 and 33% of TDN export, respectively. The combined fresh and saline groundwater fluxes of NO3, PO4, NH4, DON, DOP, TDN and TDP were estimated to account for 66, 58, 55, 31, 21, 53 and 47% of surface water exports, respectively. Groundwater-derived nitrogen inputs to the estuary were responsible for a change in the surface water N:P ratio from typical N-limiting conditions to P-limiting as predicted by previous studies. This shows the importance of both fresh and saline groundwater as a source of nutrients for coastal productivity and nutrient budgets of coastal waters. PMID:27320738

  2. Soil Salinity Mapping Using Multitemporal Landsat Data

    NASA Astrophysics Data System (ADS)

    Azabdaftari, A.; Sunar, F.

    2016-06-01

    Soil salinity is one of the most important problems affecting many areas of the world. Saline soils present in agricultural areas reduce the annual yields of most crops. This research deals with the soil salinity mapping of Seyhan plate of Adana district in Turkey from the years 2009 to 2010, using remote sensing technology. In the analysis, multitemporal data acquired from LANDSAT 7-ETM+ satellite in four different dates (19 April 2009, 12 October 2009, 21 March 2010, 31 October 2010) are used. As a first step, preprocessing of Landsat images is applied. Several salinity indices such as NDSI (Normalized Difference Salinity Index), BI (Brightness Index) and SI (Salinity Index) are used besides some vegetation indices such as NDVI (Normalized Difference Vegetation Index), RVI (Ratio Vegetation Index), SAVI (Soil Adjusted Vegetation Index) and EVI (Enhamced Vegetation Index) for the soil salinity mapping of the study area. The field's electrical conductivity (EC) measurements done in 2009 and 2010, are used as a ground truth data for the correlation analysis with the original band values and different index image bands values. In the correlation analysis, two regression models, the simple linear regression (SLR) and multiple linear regression (MLR) are considered. According to the highest correlation obtained, the 21st March, 2010 dataset is chosen for production of the soil salinity map in the area. Finally, the efficiency of the remote sensing technology in the soil salinity mapping is outlined.

  3. Relating river discharges to salinity changes

    NASA Astrophysics Data System (ADS)

    Xie, X.; Liu, W. T.

    2014-12-01

    New river discharge data are brought together with spacebased sea surface salinity measurements by Aquarius and SMOS to demonstrate the role of river discharge in salinity changes near three river mouths: the Mississippi, the Ganges, and the Amazon. The characteristics of the seasonal cycle and the year-to-year changes of the river runoff are described. Various versions of the satellite salinity data are compared. The relative roles of river discharge, surface water flux, and horizontal advection in changing surface salinity in regions near the river mouths are examined. Satellite measurements of SSS clearly track movements of the fresh water from river discharges. Besides the river discharge, E-P plays an important role in the seasonal salinity variation near the Ganges and Irrawaddy River mouths. For the Mississippi and Amazon river mouths, central and eastern ITCZ, E-P contributes very little to the salinity seasonal change. In the central and eastern ITCZ, contribution of advection to the salinity tendency is clearly identified. Both salinity and salinity tendency are dominated by semi-annual cycle in the Atlantic ITCZ between 5ºN to 9ºN, whereas annual cycle dominates at other latitudes.

  4. Gradient boosting machines, a tutorial.

    PubMed

    Natekin, Alexey; Knoll, Alois

    2013-01-01

    Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods with a strong focus on machine learning aspects of modeling. A theoretical information is complemented with descriptive examples and illustrations which cover all the stages of the gradient boosting model design. Considerations on handling the model complexity are discussed. Three practical examples of gradient boosting applications are presented and comprehensively analyzed. PMID:24409142

  5. Gradient boosting machines, a tutorial

    PubMed Central

    Natekin, Alexey; Knoll, Alois

    2013-01-01

    Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods with a strong focus on machine learning aspects of modeling. A theoretical information is complemented with descriptive examples and illustrations which cover all the stages of the gradient boosting model design. Considerations on handling the model complexity are discussed. Three practical examples of gradient boosting applications are presented and comprehensively analyzed. PMID:24409142

  6. Salinity-induced hydrate dissociation: A mechanism for recent CH4 release on Mars

    SciTech Connect

    Madden, Megan Elwood; Ulrich, Shannon M; Onstott, Tullis; Phelps, Tommy Joe

    2007-01-01

    Recent observations of CH4 in the Martian atmosphere suggest that CH4 has been added relatively recently. Several mechanisms for recent CH4 release have been proposed including subsurface biological methanogenesis, abiogenic hydrothermal and/or volcanic activity, dissociation of CH4 hydrates, atmospheric photolysis, or addition of organics via bolide impact. This study examines the effects of increasing salinity on gas hydrate stability and compares estimates of the Martian geothermal gradient to CH4 and CO2 hydrate stability fields in the presence of high salinity brines. The results demonstrate that salinity increases alone result in a significant decrease in the predicted hydrate stability zone within the Martian subsurface and may be a driving force in CH4 hydrate destabilization. Active thermal and/or pressure fluctuations are not required in order for CH4 hydrates to be the source of atmospheric CH4.

  7. Transient simulations of large-scale hydrogeological processes causing temperature and salinity anomalies in the Tiberias Basin

    NASA Astrophysics Data System (ADS)

    Magri, Fabien; Inbar, Nimrod; Siebert, Christian; Rosenthal, Eliahu; Guttman, Joseph; Möller, Peter

    2015-01-01

    Hot and salty waters occur in the surroundings of the Lake Tiberias. Transient numerical simulations of thermally-driven flow without salinity effects show that mixed convection can explain the upsurge of thermal waters through permeable faults and the high temperature gradient in the Lower Yarmouk Gorge (LYG). It turns out that by including salinity effects, the flow patterns differ from those of a purely thermal regime because heavy brines dampen upward buoyant flow and convective cells. Accordingly, the fault permeability had to be increased to restore a good fit with the measured temperatures. This further supports the hypothesis that the high temperature gradient in the LYG is likely due to fractures or faults in that area. The thermohaline simulations also suggest that the derivatives of relic seawater brines are the major source of salinity. Deep brines leaching salt diapirs cannot reach the surface. However, the presence of local shallower salt bodies below the lake can potentially contribute to the salinity of the western spring and well waters, though in very small amount. This is in agreement with geochemical data according to which the major source of the brines of the Tiberias Basin represents seawater evaporation brines. Besides being of importance for understanding the hydrogeological processes that salinize Lake Tiberias, the presented simulations provide a real-case example illustrating large-scale fluid patterns due to only one source of buoyancy (heat) and those that are additionally coupled to salinity.

  8. Soil salinity detection from satellite image analysis: an integrated approach of salinity indices and field data.

    PubMed

    Morshed, Md Manjur; Islam, Md Tazmul; Jamil, Raihan

    2016-02-01

    This paper attempts to detect soil salinity from satellite image analysis using remote sensing and geographic information system. Salinity intrusion is a common problem for the coastal regions of the world. Traditional salinity detection techniques by field survey and sampling are time-consuming and expensive. Remote sensing and geographic information system offer economic and efficient salinity detection, monitoring, and mapping. To predict soil salinity, an integrated approach of salinity indices and field data was used to develop a multiple regression equation. The correlations between different indices and field data of soil salinity were calculated to find out the highly correlated indices. The best regression model was selected considering the high R (2) value, low P value, and low Akaike's Information Criterion. About 20% variation was observed between the field data and predicted EC from the satellite image analysis. The precision of this salinity detection technique depends on the accuracy and uniform distribution of field data. PMID:26815557

  9. Critical point wetting drop tower experiment

    NASA Technical Reports Server (NTRS)

    Kaukler, William F.

    1990-01-01

    The 100 m Drop Tower at NASA-Marshall was used to provide the step change in acceleration from 1.0 to 0.0005 g. An inter-fluid meniscus oscillates vertically within a cylindrical container when suddenly released from earth's gravity and taken into a microgravity environment. Oscillations damp out from energy dissipative mechanisms such as viscosity and interfacial friction. Damping of the oscillations by the later mechanism is affected by the nature of the interfacial junction between the fluid-fluid interface and the container wall. In earlier stages of the project, the meniscus shape which developed during microgravity conditions was applied to evaluations of wetting phenomena near the critical temperature. Variations in equilibrium contact angle against the container wall were expected to occur under critical wetting conditions. However, it became apparent that the meaningful phenomenon was the damping of interfacial oscillations. This latter concept makes up the bulk of this report. Perfluoromethyl cyclohexane and isopropanol in glass were the materials used for the experiment. The wetting condition of the fluids against the wall changes at the critical wetting transition temperature. This change in wetting causes a change in the damping characteristics of the interfacial excursions during oscillation and no measurable change in contact angle. The effect of contact line friction measured above and below the wetting transition temperature was to increase the period of vertical oscillation for the vapor-liquid interface when below the wetting transition temperature.

  10. Combined effects of cadmium and salinity on juvenile Takifugu obscurus: cadmium moderates salinity tolerance; salinity decreases the toxicity of cadmium

    PubMed Central

    Wang, Jun; Zhu, Xuexia; Huang, Xin; Gu, Lei; Chen, Yafen; Yang, Zhou

    2016-01-01

    Obscure puffer Takifugu obscurus, a species of anadromous fish, experiences several salinity changes in its lifetime. Cadmium (Cd) is a toxic heavy metal that can potentially induce oxidative stress in fish. The present study aimed to detect the combined effects of Cd (0, 5, 10, 20 and 50 mg L−1) and salinity (0, 15 and 30 ppt) on juvenile T. obscurus. Results showed the juveniles could survive well under different salinities; however, with Cd exposure, the survival rates significantly decreased at 0 and 30 ppt. At 15 ppt, tolerance to Cd increased. Cd exposure clearly induced oxidative stress, and the responses among different tissues were qualitatively similar. Salinity acted as a protective factor which could reduce the reactive oxygen species and malondialdehyde levels. In addition, salinity could enhance the antioxidant defense system, including superoxide dismutase, catalase and glutathione. Na+/K+–ATPase activity significantly decreased under Cd exposure in gill, kidney and intestine. These findings indicated that Cd could moderate the adaptability of juvenile T. obscurus to high salinity and low salinity played a protective role upon Cd exposure. Thus, the role of salinity should be considered when evaluating the effect of heavy metals on anadromous and estuarine fishes. PMID:27487764

  11. Combined effects of cadmium and salinity on juvenile Takifugu obscurus: cadmium moderates salinity tolerance; salinity decreases the toxicity of cadmium.

    PubMed

    Wang, Jun; Zhu, Xuexia; Huang, Xin; Gu, Lei; Chen, Yafen; Yang, Zhou

    2016-01-01

    Obscure puffer Takifugu obscurus, a species of anadromous fish, experiences several salinity changes in its lifetime. Cadmium (Cd) is a toxic heavy metal that can potentially induce oxidative stress in fish. The present study aimed to detect the combined effects of Cd (0, 5, 10, 20 and 50 mg L(-1)) and salinity (0, 15 and 30 ppt) on juvenile T. obscurus. Results showed the juveniles could survive well under different salinities; however, with Cd exposure, the survival rates significantly decreased at 0 and 30 ppt. At 15 ppt, tolerance to Cd increased. Cd exposure clearly induced oxidative stress, and the responses among different tissues were qualitatively similar. Salinity acted as a protective factor which could reduce the reactive oxygen species and malondialdehyde levels. In addition, salinity could enhance the antioxidant defense system, including superoxide dismutase, catalase and glutathione. Na(+)/K(+)-ATPase activity significantly decreased under Cd exposure in gill, kidney and intestine. These findings indicated that Cd could moderate the adaptability of juvenile T. obscurus to high salinity and low salinity played a protective role upon Cd exposure. Thus, the role of salinity should be considered when evaluating the effect of heavy metals on anadromous and estuarine fishes. PMID:27487764

  12. Gradients in analyzability.

    PubMed

    Grotstein, J S

    A discussion of "Some Communicative Properties of the Bipersonal Field" by Robert Langs, M.D. In response to Dr. Langs' delineation of the bipersonal field concept and his clinical elaboration of a triad of disorders which are graded into classifications of descending analyzability: Types A,B, and C fields. I confirm his thesis and endeavor to demonstrate some underlying foundations of his categorical assumptions, namely the conceptions of projective identification, of the intactness of the background object of primary identification, the conception of a dual-track theory of infantile development in order to delineate the parallel between the separated self and the continuation of primary identification, and the postulation of manic and schizoid types of narcissistic character disorders (Types B and C respectively). All of these conceptions are vicissitudes of the varying ways in which patients confront the depressive position of separation-individuation with rapprochement and, thereby, conform to a gradient in which symbolization interpretations can be utilized in analytic treatment. PMID:738806

  13. Aquarius Instrument and Salinity Retrieval

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.

    2011-01-01

    Aquarius has been designed to map the surface salinity field of the global ocean from space a parameter important for understanding ocean circulation and its relationship to climate and the global water cycle. Salinity is measured remotely from space by measuring the thermal emission from the ocean surface. This is done at the low frequency end of the microwave spectrum (e.g. 1.4 GHz) where the emission is sufficiently sensitive to changes in salinity to be detected with sophisticated radiometers. The goal is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean by providing maps on a monthly basis with a spatial resolution of 150 km and an accuracy of 0.2 psu. These are challenging requirements that have led to some unique features of the instrument. These include: a) The addition of a co-located scatterometer to help provide a correction for roughness; b) The addition of a polarimetric channel (third Stokes parameter) to the radiometer to help correct for Faraday rotation; c) Asun-synchronous orbit with a 6 pm ascending equatorial crossing to minimize Faraday rotation and with the antennas looking away from the sun toward the nighttime side to minimize contamination by radiation from the sun; and d) An antenna designed to limit side lobes in the direction of rays from the sun. In addition, achieving the accuracy goal of 0.2 psu requires averaging over one month and to do this requires a highly stable radiometer. Aquarius has three separate radiometers that image in pushbroom fashion with the three antenna beams looking across track. The antenna is a 2.5-m diameter, offset parabolic reflector with three feed horns and the three beams are arranged to image with the boresight aligned to look across track, roughly perpendicular to the spacecraft heading and pointing away from the Sun. The three beams point at angles of theta = 25.8 deg., 33.8 deg. and 40.3 deg. with respect to the spacecraft

  14. Wetting reversal in colloid-polymer systems.

    PubMed

    Blokhuis, Edgar M; Kuipers, Joris

    2010-05-01

    The wetting of a phase-separated colloid-polymer mixture in contact with a hard wall is analyzed using free volume theory in a Nakanishi-Fisher-type approach. We present results for the wetting phase diagram for several model approximations. Our analysis is compared with a previous analysis by Aarts [J. Chem. Phys. 120, 1973 (2004)]. We find that there is a crossover from wetting to drying at a threshold value for the colloid-polymer size ratio and that the transitions are close to the critical point and of second order in nature. PMID:20866234

  15. Effect of surface ionization on wetting layers

    NASA Technical Reports Server (NTRS)

    Kayser, R. F.

    1986-01-01

    A surface ionization model due to Langmuir is generalized to liquid mixtures of polar and nonpolar components in contact with ionizable substrates. When a predominantly nonpolar mixture is near a miscibility gap, thick wetting layers of the conjugate polar phase form on the substrate. Such charged layers can be much thicker than similar wetting layers stabilized by dispersion forces. This model may explain the 0.4- to 0.6-micron-thick wetting layers formed in stirred mixtures of nitromethane and carbon disulfide in contact with glass.

  16. Asbestos/NESHAP adequately wet guidance

    SciTech Connect

    Shafer, R.; Throwe, S.; Salgado, O.; Garlow, C.; Hoerath, E.

    1990-12-01

    The Asbestos NESHAP requires facility owners and/or operators involved in demolition and renovation activities to control emissions of particulate asbestos to the outside air because no safe concentration of airborne asbestos has ever been established. The primary method used to control asbestos emissions is to adequately wet the Asbestos Containing Material (ACM) with a wetting agent prior to, during and after demolition/renovation activities. The purpose of the document is to provide guidance to asbestos inspectors and the regulated community on how to determine if friable ACM is adequately wet as required by the Asbestos NESHAP.

  17. Salinity variations and chemical compositions of waters in the Frio Formation, Texas Gulf Coast. Annual report

    SciTech Connect

    Morton, R.A.; Garrett, C.M. Jr.; Posey, J.S.; Han, J.H.; Jirik, L.A.

    1981-11-01

    Waters produced from sandstone reservoirs of the deep Frio Formation exhibit spatial variations in chemical composition that roughly coincide with the major tectonic elements (Houston and Rio Grande Embayments, San Marcos Arch) and corresponding depositional systems (Houston and Norias deltas, Greta-Carancahua barrier/strandplain system) that were respectively active along the upper, lower, and middle Texas Coast during Frio deposition. Within an area, salinities are usually depth dependent, and primary trends closely correspond to pore pressure gradients and thermal gradients. Where data are available (mainly in Brazoria County) the increases in TDS and calcium with depth coincide with the zone of albitization, smectite-illite transition, and calcite decrease in shales. Waters have fairly uniform salinities when produced from the same sandstone reservoir within a fault block or adjacent fault blocks with minor displacement. In contrast, stratigraphically equivalent sandstones separated by faults with large displacement usually yield waters with substantially different salinities owing to the markedly different thermal and pressure gradients across the faults that act as barriers to fluid movement.

  18. Density Gradients in Chemistry Teaching

    ERIC Educational Resources Information Center

    Miller, P. J.

    1972-01-01

    Outlines experiments in which a density gradient might be used to advantage. A density gradient consists of a column of liquid, the composition and density of which varies along its length. The procedure can be used in analysis of solutions and mixtures and in density measures of solids. (Author/TS)

  19. Multilayer High-Gradient Insulators

    SciTech Connect

    Harris, J R

    2006-08-16

    Multilayer High-Gradient Insulators are vacuum insulating structures composed of thin, alternating layers of dielectric and metal. They are currently being developed for application to high-current accelerators and related pulsed power systems. This paper describes some of the High-Gradient Insulator research currently being conducted at Lawrence Livermore National Laboratory.

  20. Empirical equation estimates geothermal gradients

    SciTech Connect

    Kutasov, I.M. )

    1995-01-02

    An empirical equation can estimate geothermal (natural) temperature profiles in new exploration areas. These gradients are useful for cement slurry and mud design and for improving electrical and temperature log interpretation. Downhole circulating temperature logs and surface outlet temperatures are used for predicting the geothermal gradients.

  1. Wetting dynamics of thin liquid films and drops under Marangoni and centrifugal forces

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Shomeek; Behringer, Robert

    2009-11-01

    We present results from ongoing experimental studies on thin liquid drops and thin-films under the combined action of centrifugal forces due to rotation and radial Marangoni forces by using a temperature gradient. For thick rotating film in the absence of a temperature gradient, when an initially thick layer of fluid is spun to angular velocities where the classical Newtonian solution is negative, the fluid never dewets for the case of a completely wetting fluid, but leaves a microscopic uniform wet layer in the center. Similar experiments with a radially inward temperature gradient reveal the evolution of a radial height profile given by h(r) = A(t)r α, where A(t) decays logarithmically with time, and α = 0.8. In the case where there is no rotation, small centrally placed drops show novel retraction behavior under a sufficiently strong temperature gradient. This work includes collaboration with Lou Kondic (NJIT), Nebojsa Murisic (UCLA) and Rich Mclaughlin (UNC-Chapel Hill).

  2. Developing Pedotransfer Functions for Saline and Saline-Alkali Soils

    NASA Astrophysics Data System (ADS)

    Ramezani, Meysam; Ghanbarian-Alavijeh, Behzad; Liaghat, Abdolmajid

    2010-05-01

    Soil moisture curve is one of the soil hydraulic properities which its direct measurement is time consuming and expensive. Therefore, indirect methods such as developing pedotransfer functions have been used to predict this characteristic from soil readily available or easily measurable data. In this study, multiple linear regression method was used to develop point pedotransfer functions (PTFs) for saline and saline-alkali soils of Iran. For this purpose, 68 soil samples which their EC values were greater than 4 ds/m, and more than half of them had ESP values greater than 15% were selected. Using Jackknife method, the random splitting of data into the development and validation subsets was repeated 10 times. A ratio of 3:1 was used to split data into development and validation sets in each replication. In the SPSS software, parameters such as geometric standard deviation (δg), geometric mean diameter (dg), sodium adsorption ratio (SAR), electrical conductivity (EC), carbonate calcium (CaCO3), bulk density (BD), organic matter (OM), and clay and silt content were applied as the independent variables, and volumetric water content was determined at matric potentials of -10, -33, -100 , -300, -500, -1000, -1500 kPa. The derived PTFs were compared with the H3 model of Rosetta software for 10 splits of validation data set. Comparison of the mean RMSE and R2 values showed that the developed PTFs resulted in more accurate estimation than the Rosetta software at matric potentials of -100 , -300, -500, -1000, -1500 kPa. Whereas, Rosetta model resulted in slightly better estimation than derived PTFs at matric potentials of -10, -33 kPa. For the PTFs developed in this study, the RMSE and R2 values ranged from 0.12 to 0.35 (cm3.cm-3) and 0.64 to 0.83, respectively. While for the Rosetta model, RMSE and R2 values ranged from 0.22 to 0.33 (cm3.cm-3) and 0.37 to 0.74, respectively.

  3. Lattice Boltzmann modeling of directional wetting: comparing simulations to experiments.

    PubMed

    Jansen, H Patrick; Sotthewes, Kai; van Swigchem, Jeroen; Zandvliet, Harold J W; Kooij, E Stefan

    2013-07-01

    Lattice Boltzmann Modeling (LBM) simulations were performed on the dynamic behavior of liquid droplets on chemically striped patterned surfaces, ultimately with the aim to develop a predictive tool enabling reliable design of future experiments. The simulations accurately mimic experimental results, which have shown that water droplets on such surfaces adopt an elongated shape due to anisotropic preferential spreading. Details of the contact line motion such as advancing of the contact line in the direction perpendicular to the stripes exhibit pronounced similarities in experiments and simulations. The opposite of spreading, i.e., evaporation of water droplets, leads to a characteristic receding motion first in the direction parallel to the stripes, while the contact line remains pinned perpendicular to the stripes. Only when the aspect ratio is close to unity, the contact line also starts to recede in the perpendicular direction. Very similar behavior was observed in the LBM simulations. Finally, droplet movement can be induced by a gradient in surface wettability. LBM simulations show good semiquantitative agreement with experimental results of decanol droplets on a well-defined striped gradient, which move from high- to low-contact angle surfaces. Similarities and differences for all systems are described and discussed in terms of the predictive capabilities of LBM simulations to model direction wetting. PMID:23944550

  4. Salinity change impairs pipefish immune defence.

    PubMed

    Birrer, Simone C; Reusch, Thorsten B H; Roth, Olivia

    2012-12-01

    Global change is associated with fast and severe alterations of environmental conditions. Superimposed onto existing salinity variations in a semi-enclosed brackish water body such as the Baltic Sea, a decrease in salinity is predicted due to increased precipitation and freshwater inflow. Moreover, we predict that heavy precipitation events will accentuate salinity fluctuations near shore. Here, we investigated how the immune function of the broad-nosed pipefish (Syngnathus typhle), an ecologically important teleost with sex-role reversal, is influenced by experimentally altered salinities (control: 18 PSU, lowered: 6 PSU, increased: 30 PSU) upon infection with bacteria of the genus Vibrio. Salinity changes resulted in increased activity and proliferation of immune cells. However, upon Vibrio infection, individuals at low salinity were unable to mount specific immune response components, both in terms of monocyte and lymphocyte cell proliferation and immune gene expression compared to pipefish kept at ambient salinities. We interpret this as resource allocation trade-off, implying that resources needed for osmoregulation under salinity stress are lacking for subsequent activation of the immune defence upon infection. Our data suggest that composition of small coastal fish communities may change due to elevated environmental stress levels and the incorporated consequences thereof. PMID:22982326

  5. Investigations in Marine Chemistry: Salinity II.

    ERIC Educational Resources Information Center

    Schlenker, Richard M.

    Presented is a science activity in which the student investigates methods of calibration of a simple conductivity meter via a hands-on inquiry technique. Conductivity is mathematically compared to salinity using a point slope formula and graphical techniques. Sample solutions of unknown salinity are provided so that the students can sharpen their…

  6. Biodiversity gradient in the Baltic Sea: a comprehensive inventory of macrozoobenthos data

    NASA Astrophysics Data System (ADS)

    Zettler, Michael L.; Karlsson, Anna; Kontula, Tytti; Gruszka, Piotr; Laine, Ari O.; Herkül, Kristjan; Schiele, Kerstin S.; Maximov, Alexey; Haldin, Jannica

    2014-03-01

    In the Helsinki Commission Red List project 2009-2012, taxonomic and distributional data of benthic (macro) invertebrates were compiled by the present authors in a comprehensive checklist of the Baltic Sea fauna. Based on the most recent and comprehensive data, this paper presents the diversity patterns observed among benthic invertebrates in the Baltic Sea. As expected, the total number of species per sub-region generally declined along the salinity gradient from the Danish Straits to the northern Baltic Sea. This relationship is well known from the Baltic Sea and has resulted in a general assumption of an exponentially positive relationship between species richness and salinity for marine species, and a negative relationship for freshwater species. In 1934, Remane produced a diagram to describe the hypothetical distribution of benthic invertebrate diversity along a marine-freshwater salinity gradient. Our results clearly indicated the validity of this theory for the macrozoobenthic diversity pattern within the Baltic Sea. Categorisation of sub-regions according to species composition showed both separation and grouping of some sub-regions and a strong alignment of similarity patterns of zoobenthic species composition along the salinity gradient.

  7. Gradient elution in capillary electrochromatography

    SciTech Connect

    Anex, D.; Rakestraw, D.J.; Yan, Chao; Dadoo, R.; Zare, R.N.

    1997-08-01

    In analogy to pressure-driven gradient techniques in high-performance liquid chromatography, a system has been developed for delivering electroosmotically-driven solvent gradients for capillary electrochromatography (CEC). Dynamic gradients with sub-mL/min flow rates are generated by merging two electroosmotic flows that are regulated by computer-controlled voltages. These flows are delivered by two fused-silica capillary arms attached to a T-connector, where they mix and then flow into a capillary column that has been electrokinetically packed with 3-mm reversed-phase particles. The inlet of one capillary arm is placed in a solution reservoir containing one mobile phase and the inlet of the other is placed in a second reservoir containing a second mobile phase. Two independent computer-controlled programmable high-voltage power supplies (0-50 kV)--one providing an increasing ramp and the other providing a decreasing ramp--are used to apply variable high-voltage potentials to the mobile phase reservoirs to regulate the electroosmotic flow in each arm. The ratio of the electroosmotic flow rates between the two arms is changed with time according to the computer-controlled voltages to deliver the required gradient profile to the separation column. Experiments were performed to confirm the composition of the mobile phase during a gradient run and to determine the change of the composition in response to the programmed voltage profile. To demonstrate the performance of electroosmotically-driven gradient elution in CEC, a mixture of 16 polycyclic aromatic hydrocarbons (PAHs) was separated in less than 90 minutes. This gradient technique is expected to be well-suited for generating not only solvent gradients in CEC, but also other types of gradients such as pH- and ionic-strength gradients in capillary electrokinetic separations and analyses.

  8. Photoresponsive superhydrophobic surfaces for effective wetting control.

    PubMed

    Pan, Shuaijun; Guo, Rui; Xu, Weijian

    2014-12-01

    Dynamically tuning the surface wettability has long been a scientific challenge, but of great importance in surface science. Robust superhydrophobic surfaces, displaying switchable and tunable extreme wetting behaviors, are successfully developed by spraying photoresponsive hydrophobic nanoparticles onto various substrates. The surface wettability can be intelligently adjusted by applying irradiation with UV or visible light, which is assumed to initiate large conformation changes of azobenzene units at the coating surface, resulting in distinct surface energy change and thus controlled wetting behaviors. The underlying wetting mechanism about the resulting surfaces is systematically investigated and supported by the estimation of water contact angles using newly rewritten Cassie-Baxter and Wenzel relations and also by the evaluation of solid surface free energy adopting the Owens-Wendt approach. The methodology proposed may provide a novel way of tuning surface wettability and investigating the wetting transition mechanism and also promote applications in self-cleaning and smart fluid control. PMID:25322263

  9. Snow wetness measurements for melt forecasting

    NASA Technical Reports Server (NTRS)

    Linlor, W. I.; Clapp, F. D.; Meier, M. F.; Smith, J. L.

    1975-01-01

    A microwave technique for directly measuring snow pack wetness in remote installations is described. The technique, which uses satellite telemetry for data gathering, is based on the attenuation of a microwave beam in transmission through snow.

  10. Wetting transparency of graphene in water

    NASA Astrophysics Data System (ADS)

    Driskill, Joshua; Vanzo, Davide; Bratko, Dusan; Luzar, Alenka

    2014-11-01

    Measurements of contact angle on graphene sheets show a notable dependence on the nature of the underlying substrate, a phenomenon termed wetting transparency. Our molecular modeling studies reveal analogous transparency in case of submerged graphene fragments in water. A combined effect of attractive dispersion forces, angle correlations between aqueous dipoles, and repulsion due to the hydrogen-bond-induced orientation bias in polarized hydration layers acting across graphene sheet, enhances apparent adhesion of water to graphene. We show wetting free energy of a fully wetted graphene platelet to be about 8 mNm-1 lower than for graphene wetted only on one side, which gives close to 10° reduction in contact angle. This difference has potential implications for predictions of water absorption vs. desorption, phase behavior of water in aqueous nanoconfinements, solvent-induced interactions among graphitic nanoparticle and concomitant stability in aqueous dispersions, and can influence permeability of porous materials such as carbon nanotubes by water and aqueous solutions.

  11. National Ignition Facility wet weather construction plan

    SciTech Connect

    Kugler, A N

    1998-01-01

    This report presents a wet weather construction plan for the National Ignition Facility (NIF) construction project. Construction of the NIF commenced in mid- 1997, and excavation of the site was completed in the fall. Preparations for placing concrete foundations began in the fall, and above normal rainfall is expected over the tinter. Heavy rainfall in late November impacted foundation construction, and a wet weather construction plan was determined to be needed. This wet weather constiction plan recommends a strategy, techniques and management practices to prepare and protect the site corn wet weather effects and allow construction work to proceed. It is intended that information in this plan be incorporated in the Stormwater Pollution Prevention Plan (SWPPP) as warranted.

  12. ESTIMATING URBAN WET-WEATHER POLLUTANT LOADING

    EPA Science Inventory

    This paper presents procedures for estimating pollutant loads in urban watersheds emanating from wet-weather flow discharge. Equations for pollutant loading estimates will focus on the effects of wastewater characteristics, sewer flow carrying velocity, and sewer-solids depositi...

  13. Reducing the atmospheric impact of wet slaking

    SciTech Connect

    B.D. Zubitskii; G.V. Ushakov; B.G. Tryasunov; A.G.Ushakov

    2009-05-15

    Means of reducing the atmospheric emissions due to the wet slaking of coke are considered. One option, investigated here, is to remove residual active silt and organic compounds from the biologically purified wastewater sent for slaking, by coagulation and flocculation.

  14. Chlorine Disinfection of Wet Weather Managed Flows

    EPA Science Inventory

    Blending is a practice used in the wastewater industry to deal with wet weather events when the hydraulic capacity of the treatment facility could be compromised. Blending consists of primary wastewater treatment plant effluent, partially bypassing secondary treatment, and then ...

  15. Critical point wetting drop tower experiment

    NASA Technical Reports Server (NTRS)

    Kaukler, W. F.; Tcherneshoff, L. M.; Straits, S. R.

    1984-01-01

    Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.

  16. Wetting of a chemically heterogeneous surface

    SciTech Connect

    Frink, L.J.; Salinger, A.G.

    1999-03-01

    Theories for inhomogeneous fluids have focused in recent years on wetting, capillary condensation, and solvation forces for model systems where the surface(s) is(are) smooth homogeneous parallel plates, cylinders, or spherical drops. Unfortunately natural systems are more likely to be heterogeneous both in surface shape and surface chemistry. In this paper we discuss the consequences of chemical heterogeneity on wetting. Specifically, a two-dimensional (2D) implementation of a nonlocal density-functional theory is solved for a striped surface model. Both the strength and range of the heterogeneity are varied. Contact angles are calculated, and phase transitions (both the wetting transition and a local layering transition) are located. The wetting properties of the surface are shown to be strongly dependent on the nature of the surface heterogeneity. In addition highly ordered nanoscopic phases are found, and the operational limits for formation of ordered or crystalline phases of nanoscopic extent are discussed. {copyright} {ital 1999 American Institute of Physics.}

  17. 7 CFR 51.491 - Wet slip.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... time of packing in which the stem scar is abnormally large, excessively wet and slippery, yields to slight pressure, and is frequently accompanied by fresh radial growth cracks at the edge of the stem scar....

  18. A WET TALE: TOXICITY OF COMPLEX EFFLUENTS

    EPA Science Inventory

    This course covers standards, regulations, policy, guidance and technical aspects of implementing the whole effluent toxicity program. The curriculum incorporates rationale and information on WET test requirements from USEPA documents, such as the Technical Support Document for W...

  19. Wetting behavior of alternative solder alloys

    SciTech Connect

    Hosking, F.M.; Vianco, P.T.; Hernandez, C.L.; Rejent, J.A.

    1993-07-01

    Recent economic and environmental issues have stimulated interest in solder alloys other than the traditional Sn-Pb eutectic or near eutectic composition. Preliminary evaluations suggest that several of these alloys approach the baseline properties (wetting, mechanical, thermal, and electrical) of the Sn-Pb solders. Final alloy acceptance will require major revisions to existing industrial and military soldering specifications. Bulk alloy and solder joint properties are consequently being investigated to validate their producibility and reliability. The work reported in this paper examines the wetting behavior of several of the more promising commercial alloys on copper substrates. Solder wettability was determined by the meniscometer and wetting balance techniques. The wetting results suggest that several of the alternative solders would satisfy pretinning and surface mount soldering applications. Their use on plated through hole technology might be more difficult since the alloys generally did not spread or flow as well as the 60Sn-40Pb solder.

  20. Gradient zone boundary control in salt gradient solar ponds

    DOEpatents

    Hull, John R.

    1984-01-01

    A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

  1. Complete wetting of graphene by biological lipids

    NASA Astrophysics Data System (ADS)

    Luan, Binquan; Huynh, Tien; Zhou, Ruhong

    2016-03-01

    Graphene nanosheets have been demonstrated to extract large amounts of lipid molecules directly out of the cell membrane of bacteria and thus cause serious damage to the cell's integrity. This interesting phenomenon, however, is so far not well understood theoretically. Here through extensive molecular dynamics simulations and theoretical analyses, we show that this phenomenon can be categorized as a complete wetting of graphene by membrane lipids in water. A wetting-based theory was utilized to associate the free energy change during the microscopic extraction of a lipid with the spreading parameter for the macroscopic wetting. With a customized thermodynamic cycle for detailed energetics, we show that the dispersive adhesion between graphene and lipids plays a dominant role during this extraction as manifested by the curved graphene. Our simulation results suggest that biological lipids can completely wet the concave, flat or even convex (with a small curvature) surface of a graphene sheet.Graphene nanosheets have been demonstrated to extract large amounts of lipid molecules directly out of the cell membrane of bacteria and thus cause serious damage to the cell's integrity. This interesting phenomenon, however, is so far not well understood theoretically. Here through extensive molecular dynamics simulations and theoretical analyses, we show that this phenomenon can be categorized as a complete wetting of graphene by membrane lipids in water. A wetting-based theory was utilized to associate the free energy change during the microscopic extraction of a lipid with the spreading parameter for the macroscopic wetting. With a customized thermodynamic cycle for detailed energetics, we show that the dispersive adhesion between graphene and lipids plays a dominant role during this extraction as manifested by the curved graphene. Our simulation results suggest that biological lipids can completely wet the concave, flat or even convex (with a small curvature) surface of a

  2. The influence of salinity on tropical Atlantic instability waves

    NASA Astrophysics Data System (ADS)

    Lee, Tong; Lagerloef, Gary; Kao, Hsun-Ying; McPhaden, Michael J.; Willis, Joshua; Gierach, Michelle M.

    2014-12-01

    Sea surface salinity (SSS) data derived from the Aquarius/SAC-D satellite mission are analyzed along with other satellite and in situ data to assess Aquarius' capability to detect tropical instability waves (TIWs) and eddies in the tropical Atlantic Ocean and to investigate the influence that SSS has on the variability. Aquarius data show that the magnitude of SSS anomalies associated with the Atlantic TIWs is ±0.25 practical salinity unit, which is weaker than those in the Pacific by 50%. In the central equatorial Atlantic, SSS contribution to the mean meridional density gradient is similar to sea surface temperature (SST) contribution. Consequently, SSS is important to TIW-related surface density anomalies and perturbation potential energy (PPE). In this region, SSS influences surface PPE significantly through the direct effect and the indirect effect associated with SSS-SST covariability. Ignoring SSS effects would underestimate TIW-related PPE by approximately three times in the surface layer. SSS also regulates the seasonality of the TIWs. The boreal-spring peak of the PPE due to SSS leads that due to SST by about one month. Therefore, SSS not only affects the spatial structure, but the seasonal variability of the TIWs in the equatorial Atlantic. In the northeast Atlantic near the Amazon outflow and the North Brazil Current retroflection region and in the southeast Atlantic near the Congo River outflow, SSS accounts for 80-90% of the contribution to mean meridional density gradient. Not accounting for SSS effect would underestimate surface PPE in these regions by a factor of 10 and 4, respectively.

  3. Leaf wetness distribution within a potato crop

    NASA Astrophysics Data System (ADS)

    Heusinkveld, B. G.

    2010-07-01

    The Netherlands has a mild maritime climate and therefore the major interest in leaf wetness is associated with foliar plant diseases. During moist micrometeorological conditions (i.e. dew, fog, rain), foliar fungal diseases may develop quickly and thereby destroy a crop quickly. Potato crop monocultures covering several hectares are especially vulnerable to such diseases. Therefore understanding and predicting leaf wetness in potato crops is crucial in crop disease control strategies. A field experiment was carried out in a large homogeneous potato crop in the Netherlands during the growing season of 2008. Two innovative sensor networks were installed as a 3 by 3 grid at 3 heights covering an area of about 2 hectares within two larger potato crops. One crop was located on a sandy soil and one crop on a sandy peat soil. In most cases leaf wetting starts in the top layer and then progresses downward. Leaf drying takes place in the same order after sunrise. A canopy dew simulation model was applied to simulate spatial leaf wetness distribution. The dew model is based on an energy balance model. The model can be run using information on the above-canopy wind speed, air temperature, humidity, net radiation and within canopy air temperature, humidity and soil moisture content and temperature conditions. Rainfall was accounted for by applying an interception model. The results of the dew model agreed well with the leaf wetness sensors if all local conditions were considered. The measurements show that the spatial correlation of leaf wetness decreases downward.

  4. Patterns of groundwater salinity changes in a deep continental-oceanic transect off the southeastern Atlantic coast of the U.S.A.

    USGS Publications Warehouse

    Manheim, F. T.; Paull, C.K.

    1981-01-01

    Investigations of formation-fluid salinities in a transect from western Georgia to the edge of the Blake Plateau off the coast of Georgia show surprisingly similar hydrochemical features offshore and onshore. A fresh-brackish wedge of groundwater ( 100 g/kg) occur in Lower Cretaceous (?) strata. These strata have a pronounced evaporitic (anhydritic) character in the offshore segment. Strong salinity gradients in interstitial waters signify buried evaporite deposits at drill sites beneath the Blake Plateau. ?? 1981.

  5. Thermodynamic, energy efficiency, and power density analysis of reverse electrodialysis power generation with natural salinity gradients.

    PubMed

    Yip, Ngai Yin; Vermaas, David A; Nijmeijer, Kitty; Elimelech, Menachem

    2014-05-01

    Reverse electrodialysis (RED) can harness the Gibbs free energy of mixing when fresh river water flows into the sea for sustainable power generation. In this study, we carry out a thermodynamic and energy efficiency analysis of RED power generation, and assess the membrane power density. First, we present a reversible thermodynamic model for RED and verify that the theoretical maximum extractable work in a reversible RED process is identical to the Gibbs free energy of mixing. Work extraction in an irreversible process with maximized power density using a constant-resistance load is then examined to assess the energy conversion efficiency and power density. With equal volumes of seawater and river water, energy conversion efficiency of ∼ 33-44% can be obtained in RED, while the rest is lost through dissipation in the internal resistance of the ion-exchange membrane stack. We show that imperfections in the selectivity of typical ion exchange membranes (namely, co-ion transport, osmosis, and electro-osmosis) can detrimentally lower efficiency by up to 26%, with co-ion leakage being the dominant effect. Further inspection of the power density profile during RED revealed inherent ineffectiveness toward the end of the process. By judicious early discontinuation of the controlled mixing process, the overall power density performance can be considerably enhanced by up to 7-fold, without significant compromise to the energy efficiency. Additionally, membrane resistance was found to be an important factor in determining the power densities attainable. Lastly, the performance of an RED stack was examined for different membrane conductivities and intermembrane distances simulating high performance membranes and stack design. By thoughtful selection of the operating parameters, an efficiency of ∼ 37% and an overall gross power density of 3.5 W/m(2) represent the maximum performance that can potentially be achieved in a seawater-river water RED system with low-resistance ion exchange membranes (0.5 Ω cm(2)) at very small spacing intervals (50 μm). PMID:24697542

  6. Porous carbon-coated graphite electrodes for energy production from salinity gradient using reverse electrodialysis

    NASA Astrophysics Data System (ADS)

    Lee, Su-Yoon; Jeong, Ye-Jin; Chae, So-Ryong; Yeon, Kyeong-Ho; Lee, Yunkyu; Kim, Chan-Soo; Jeong, Nam-Jo; Park, Jin-Soo

    2016-04-01

    Performance of graphite foil electrodes coated by porous carbon black (i.e., Vulcan) was investigated in comparison with metal electrodes for reverse electrodialysis (RED) application. The electrode slurry that was used for fabrication of the porous carbon-coated graphite foil is composed of 7.2 wt% of carbon black (Vulcan X-72), 0.8 wt% of a polymer binder (polyvinylidene fluoride, PVdF), and 92.0 wt% of a mixing solvent (dimethylacetamide, DMAc). Cyclic voltammograms of both the porous carbon (i.e., Vulcan)-coated graphite foil electrode and the graphite foil electrode without Vulcan showed good reversibility in the hexacyanoferrate(III) (i.e., Fe(CN)63-) and hexacyanoferrate(II) (i.e., Fe(CN)64-) redox couple and 1 M Na2SO4 at room temperature. However, anodic and cathodic current of the Vulcan-coated graphite foil electrode was much higher than those of the graphite foil electrode. Using a bench-scale RED stack, the current-voltage polarization curve of the Vulcan-coated graphite electrode was compared to that of metal electrodes such as iridium (Ir) and platinum (Pt). From the results, it was confirmed that resistance of four different electrodes increased with the following order: the Vulcan-coated graphite foil

  7. Preliminary design of an osmotic-type salinity-gradient energy converter: Phase 2

    NASA Astrophysics Data System (ADS)

    1982-06-01

    The preliminary design is presented of a 50 kW/sub e/ closed cycle osmotic pressure power system using a saturated solar pond as the unmixer for the mixed brine with 7.7% potassium alum solution on one side and 52% potassium alum solution on the other side of the semipermeable membrane. Included are: system description with flow diagram, general arrangement, general pipe routing between equipment drawings and component performance specifications; siting restrictions; environmental considerations; pretreatment; membrane characteristics; preliminary system capital, operating and maintenance costs; and recommendations. It was found that the area requirement for a saturated solar pond is less than one tenth of that required for a solar evaporation pond. The pretreatment cost was found to be much less in this case because the system is closed. Finally, the use of a saturated solar pond greatly increases the potential number of sites available for a practical osmotic pressure power system.

  8. KEITH LAKE HABITAT IMPROVEMENT STRUCTURES AND SALINITY GRADIENT MODEL MX964017

    EPA Science Inventory

    The Keith Lake / Salt Bayou system of wetlands is an important site for over-wintering waterfowl and for the protection of other fauna and flora in the region. Hydraulically-connected shallow lakes such as Keith Lake, along with small bayous, form a large wetland complex. Histor...

  9. Heat extraction from salinity-gradient solar ponds using heat pipe heat exchangers

    SciTech Connect

    Tundee, Sura; Terdtoon, Pradit; Sakulchangsatjatai, Phrut; Singh, Randeep; Akbarzadeh, Aliakbar

    2010-09-15

    This paper presents the results of experimental and theoretical analysis on the heat extraction process from solar pond by using the heat pipe heat exchanger. In order to conduct research work, a small scale experimental solar pond with an area of 7.0 m{sup 2} and a depth of 1.5 m was built at Khon Kaen in North-Eastern Thailand (16 27'N102 E). Heat was successfully extracted from the lower convective zone (LCZ) of the solar pond by using a heat pipe heat exchanger made from 60 copper tubes with 21 mm inside diameter and 22 mm outside diameter. The length of the evaporator and condenser section was 800 mm and 200 mm respectively. R134a was used as the heat transfer fluid in the experiment. The theoretical model was formulated for the solar pond heat extraction on the basis of the energy conservation equations and by using the solar radiation data for the above location. Numerical methods were used to solve the modeling equations. In the analysis, the performance of heat exchanger is investigated by varying the velocity of inlet air used to extract heat from the condenser end of the heat pipe heat exchanger (HPHE). Air velocity was found to have a significant influence on the effectiveness of heat pipe heat exchanger. In the present investigation, there was an increase in effectiveness by 43% as the air velocity was decreased from 5 m/s to 1 m/s. The results obtained from the theoretical model showed good agreement with the experimental data. (author)

  10. Distribution of vascular plants and macroalgae along salinity and elevation gradients in Oregon tidal marshes

    EPA Science Inventory

    Sea level rise due to global climate change may affect the spatial distribution of plants and macroalgae within tidal estuaries. We present preliminary results from on-going research in Oregon to determine how these potential abiotic drives correlate with the presence or absence...

  11. Performance limiting effects in power generation from salinity gradients by pressure retarded osmosis.

    PubMed

    Yip, Ngai Yin; Elimelech, Menachem

    2011-12-01

    Pressure retarded osmosis has the potential to utilize the free energy of mixing when fresh river water flows into the sea for clean and renewable power generation. Here, we present a systematic investigation of the performance limiting phenomena in pressure retarded osmosis--external concentration polarization, internal concentration polarization, and reverse draw salt flux--and offer insights on the design criteria of a high performance pressure retarded osmosis power generation system. Thin-film composite polyamide membranes were chemically modified to produce a range of membrane transport properties, and the water and salt permeabilities were characterized to determine the underlying permeability-selectivity trade-off relationship. We show that power density is constrained by the trade-off between permeability and selectivity of the membrane active layer. This behavior is attributed to the opposing influence of the beneficial effect of membrane water permeability and the detrimental impact of reverse salt flux coupled with internal concentration polarization. Our analysis reveals the intricate influence of active and support layer properties on power density and demonstrates that membrane performance is maximized by tailoring the water and salt permeabilities to the structural parameters. An analytical parameter that quantifies the relative influence of each performance limiting phenomena is employed to identify the dominant effect restricting productivity. External concentration polarization is shown to be the main factor limiting performance at high power densities. Enhancement of the hydrodynamic flow conditions in the membrane feed channel reduces external concentration polarization and thus, yields improved power density. However, doing so will also incur additional operating costs due to the accompanying hydraulic pressure loss. This study demonstrates that by thoughtful selection of the membrane properties and hydrodynamic conditions, the detrimental effects that limit productivity in a pressure retarded osmosis power generation process can be methodically minimized to achieve high performance. PMID:22022858

  12. The Importance of Allochthonous Subsidies to an Estuarine Food Web along a Salinity Gradient

    EPA Science Inventory

    Estuarine food webs function within a heterogeneous mosaic and are supported by a mix of primary producers from both local and distant sources. Processes governing the exchange and consumption of organic matter (OM), however, are poorly understood. To study the contribution of ...

  13. Leaf litter decomposition rates increase with rising mean annual temperature in Hawaiian tropical montane wet forests

    PubMed Central

    Bothwell, Lori D.; Giardina, Christian P.; Litton, Creighton M.

    2014-01-01

    Decomposing litter in forest ecosystems supplies nutrients to plants, carbon to heterotrophic soil microorganisms and is a large source of CO2 to the atmosphere. Despite its essential role in carbon and nutrient cycling, the temperature sensitivity of leaf litter decay in tropical forest ecosystems remains poorly resolved, especially in tropical montane wet forests where the warming trend may be amplified compared to tropical wet forests at lower elevations. We quantified leaf litter decomposition rates along a highly constrained 5.2 °C mean annual temperature (MAT) gradient in tropical montane wet forests on the Island of Hawaii. Dominant vegetation, substrate type and age, soil moisture, and disturbance history are all nearly constant across this gradient, allowing us to isolate the effect of rising MAT on leaf litter decomposition and nutrient release. Leaf litter decomposition rates were a positive linear function of MAT, causing the residence time of leaf litter on the forest floor to decline by ∼31 days for each 1 °C increase in MAT. Our estimate of the Q10 temperature coefficient for leaf litter decomposition was 2.17, within the commonly reported range for heterotrophic organic matter decomposition (1.5–2.5) across a broad range of ecosystems. The percentage of leaf litter nitrogen (N) remaining after six months declined linearly with increasing MAT from ∼88% of initial N at the coolest site to ∼74% at the warmest site. The lack of net N immobilization during all three litter collection periods at all MAT plots indicates that N was not limiting to leaf litter decomposition, regardless of temperature. These results suggest that leaf litter decay in tropical montane wet forests may be more sensitive to rising MAT than in tropical lowland wet forests, and that increased rates of N release from decomposing litter could delay or prevent progressive N limitation to net primary productivity with climate warming. PMID:25493213

  14. Florida Current surface temperature and salinity variability during the last millennium

    NASA Astrophysics Data System (ADS)

    Lund, David C.; Curry, William

    2006-06-01

    The salinity and temperature of the Florida Current are key parameters affecting the transport of heat into the North Atlantic, yet little is known about their variability on centennial timescales. Here we report replicated, high-resolution foraminiferal records of Florida Current surface hydrography for the last millennium from two coring sites, Dry Tortugas and the Great Bahama Bank. The oxygen isotopic composition of Florida Current surface water (δ18Ow) near Dry Tortugas increased 0.4‰ during the course of the Little Ice Age (LIA) (˜1200-1850 A.D.), equivalent to a salinity increase of 0.8-1.5. On the Great Bahama Bank, where surface waters are influenced by the North Atlantic subtropical gyre, δ18Ow increased by 0.3‰ during the last 200 years. Although a portion (˜0.1‰) of this shift may be an artifact of anthropogenically driven changes in surface water ΣCO2, the remaining δ18Ow signal implies a 0.4-1 increase in salinity after 200 years B.P. The simplest explanation of the δ18Ow data is southward migration of the Atlantic Hadley circulation during the LIA. Scaling of the δ18Ow records to salinity using the modern low-latitude δ18Ow-S slope produces an unrealistic reversal in the salinity gradient between the two sites. Only if δ18Ow is scaled to salinity using a high-latitude δ18Ow-S slope can the records be reconciled. Variable atmospheric 14C paralleled Dry Tortugas δ18Ow, suggesting that solar irradiance paced centennial-scale migration of the Inter-Tropical Convergence Zone and changes in Florida Current salinity during the last millennium.

  15. Observed interannual variability of near-surface salinity in the Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Pant, Vimlesh; Girishkumar, M. S.; Udaya Bhaskar, T. V. S.; Ravichandran, M.; Papa, Fabrice; Thangaprakash, V. P.

    2015-05-01

    An in situ gridded data of salinity, comprising Argo and CTD profiles, has been used to study the interannual variability of near-surface salinity (within 30 m from sea surface) in the Bay of Bengal (BoB) during the years 2005-2013. In addition to the broad agreement with earlier studies on the north-to-south gradient of surface salinity and general features of seasonal variability of salinity, the data also revealed few episodes of enhanced freshening in the BoB. The observations showed distinct anomalous low salinity (< 2 psu) waters in the northern BoB during June-February of the years 2006-2007 (Y67), 2011-2012 (Y12), and 2012-2013 (Y23). The anomalous freshening during these years showed similar life cycle, such as, it starts in the northern BoB during July-September of current summer and extends up to February-March of next winter with a southward propagation. Analysis showed that the oceanic and atmospheric conditions associated with positive Indian Ocean Dipole (pIOD) lead to these freshening events, and IOD rather than El Niño/Southern Oscillation (ENSO) controls the interannual variability of salinity in the BoB. The mixed layer salt budget analysis indicated the dominant role of local fresh water flux (horizontal advection) on the observed salinity tendency during summer (winter) monsoon season. Enhanced precipitation associated with pIOD lead to enhanced freshening in northern BoB during June-September, which remained to this region with prevailing summer monsoon circulation. The weakening or absence of southward east India coastal current (EICC) during October-December of these freshening years trapped anomalous freshwater in the northern BoB.

  16. Identifying sources and controlling factors of arsenic release in saline groundwater aquifers

    NASA Astrophysics Data System (ADS)

    Liu, C.-W.; Lu, K.-L.; Kao, Y.-H.; Wang, C.-J.; Maji, S.-K.; Lee, J.-F.

    2013-08-01

    An integrated hydrogeochemical study is carried out to realize the occurrence of arsenic (As) in a saline aquifer. Saline groundwater was mostly concentrated in the uppermost aquifer and non-saline water was in the lower aquifer in the study area. High As concentrations were found in both uppermost and lower aquifers. No correlation among salination, well depth and As concentration was observed. Both reducing and oxidizing forms of Fe oxyhydroxides were identified in the magnetic fractions, which were concentrated by high gradient magnetic separation (HGMS) technique, revealing that the redox cycling of Fe occurred in the subsurface. High levels of Fe, HCO3-, DOC and NH4+ concentrations accompanying alkaline pH in the As-rich groundwater were consistent with the mechanism triggered by the microbial-mediated reductive dissolution of Fe oxyhydroxides. A threshold value of 50 μg L-1. As concentration was used as an indicator for identification of active proceeding reductive dissolution of As-bearing Fe oxyhydroxides in the saline aquifer. Desorption behaviors of As were relevant to its valence in the sediments and the co-existence of anions. Experimental and numerical results showed that additions of Cl- and SO42-, which represented the main anions of saline water, had minor effect on leaching sedimentary As. Although bicarbonate addition resulted in less As desorption than that of phosphate on a molar basis, the contribution of bicarbonate to the total release of As was greater than phosphate due to the much higher concentration of bicarbonate in groundwater and the associated microbial mediation. Collectively, the chemical effect of saline water on the As-release to groundwater is mild in the coastal aquifer.

  17. Identifying sources and controlling factors of arsenic release in saline groundwater aquifers

    NASA Astrophysics Data System (ADS)

    Liu, C.-W.; Lu, K.-L.; Kao, Y.-H.; Wang, C.-J.; Maji, S.-K.; Lee, J.-F.

    2014-03-01

    An integrated hydrogeochemical study was carried out to realize the occurrence of arsenic (As) in a saline aquifer. Saline groundwater was mostly concentrated in the uppermost aquifer, and non-saline water was in the lower aquifer in the study area. High As concentrations were found in both the uppermost and lower aquifers. No correlation among salinity, well depth and As concentration was observed. Various forms of Fe oxyhydroxides were identified in the magnetic fractions, which were concentrated by high gradient magnetic separation (HGMS) technique, revealing that the redox cycling of Fe occurred in the subsurface. High levels of Fe, HCO3-, DOC and NH4+ concentrations accompanying alkaline pH in the As-rich groundwater were consistent with the mechanism triggered by the microbially mediated reductive dissolution of Fe oxyhydroxides. A proposed threshold value of 50μg L-1 As concentration was used as an indicator for identification of active proceeding reductive dissolution of As-bearing Fe oxyhydroxides in the saline aquifer. Desorption behaviors of As were relevant to its valence in the sediments and the co-existence of anions. Experimental and numerical results showed that additions of Cl- and SO42-, which represent the main anions of saline water, had minor effect on leaching sedimentary As. Although bicarbonate addition resulted in less As desorption than that of phosphate on a molar basis, the contribution of bicarbonate to the total release of As was greater than phosphate due to the much higher concentration of bicarbonate in shallow groundwater and the associated microbial mediation. Collectively, the chemical effect of saline water on the As release to groundwater is mild in the coastal aquifer.

  18. Combining Step Gradients and Linear Gradients in Density.

    PubMed

    Kumar, Ashok A; Walz, Jenna A; Gonidec, Mathieu; Mace, Charles R; Whitesides, George M

    2015-06-16

    Combining aqueous multiphase systems (AMPS) and magnetic levitation (MagLev) provides a method to produce hybrid gradients in apparent density. AMPS—solutions of different polymers, salts, or surfactants that spontaneously separate into immiscible but predominantly aqueous phases—offer thermodynamically stable steps in density that can be tuned by the concentration of solutes. MagLev—the levitation of diamagnetic objects in a paramagnetic fluid within a magnetic field gradient—can be arranged to provide a near-linear gradient in effective density where the height of a levitating object above the surface of the magnet corresponds to its density; the strength of the gradient in effective density can be tuned by the choice of paramagnetic salt and its concentrations and by the strength and gradient in the magnetic field. Including paramagnetic salts (e.g., MnSO4 or MnCl2) in AMPS, and placing them in a magnetic field gradient, enables their use as media for MagLev. The potential to create large steps in density with AMPS allows separations of objects across a range of densities. The gradients produced by MagLev provide resolution over a continuous range of densities. By combining these approaches, mixtures of objects with large differences in density can be separated and analyzed simultaneously. Using MagLev to add an effective gradient in density also enables tuning the range of densities captured at an interface of an AMPS by simply changing the position of the container in the magnetic field. Further, by creating AMPS in which phases have different concentrations of paramagnetic ions, the phases can provide different resolutions in density. These results suggest that combining steps in density with gradients in density can enable new classes of separations based on density. PMID:25978093

  19. High field gradient particle accelerator

    DOEpatents

    Nation, John A.; Greenwald, Shlomo

    1989-01-01

    A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle.

  20. High field gradient particle accelerator

    DOEpatents

    Nation, J.A.; Greenwald, S.

    1989-05-30

    A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications is disclosed. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle. 10 figs.

  1. Impacts of climate variability on wetland salinization in the North American Prairies

    NASA Astrophysics Data System (ADS)

    Nachshon, U.; Ireson, A.; van der Kamp, G.; Davies, S. R.; Wheater, H. S.

    2013-11-01

    The glaciated plains of the North American continent, also known as the "prairies", are a complex hydrological system characterized by hummocky terrain, where wetlands, containing seasonal or semi-permanent ponds, occupy the numerous topographic depressions. The prairie subsoil and many of its water bodies contain high salt concentrations, in particular sulfate salts, which are continuously cycled within the closed drainage basins. The period between 2000 and 2012 was characterized by an unusual degree of climatic variability, including severe floods and droughts, and this had a marked effect on the spatial distribution, water levels and chemical composition of wetland ponds. Understanding the geochemical and hydrological processes under changing environmental conditions is needed in order to better understand the risk and mitigate the impacts of future soil and water salinization. Here we explore salt dynamics in the prairies using field observations from St. Denis, Saskatchewan, taken over the last 40 yr. Measurements include meteorological data, soil salinity, groundwater levels and pond water volume, salinity, and chemical composition. The record includes periods of exceptional snow (1997, 2007) and periods of exception rainfall (2010, 2012), both of which resulted in unusually high pond water levels. However, severe salinization only occurred in response to extreme summer rainfall. We hypothesize that since rainfall and snowmelt activate different hydrological pathways, they have markedly different impacts on salinization. We propose that a wet condition associated with high snowmelt conditions does not pose a strong threat to salinization, which has important implications for agricultural planning. Whilst this hypothesis is consistent with our conceptual understanding of the system, it needs to be tested further at a range of field sites in the prairies.

  2. Train-borne Measurements of Enhanced Wet Season Methane Emissions in Northern Australia - Implications for Australian Tropical Wetland Emissions

    NASA Astrophysics Data System (ADS)

    Deutscher, N. M.; Griffith, D. W.; Paton-Walsh, C.

    2008-12-01

    We present the first transect measurements of CH4, CO2, CO and N2O taken on the Ghan railway travelling on a N-S transect of the Australian continent between Adelaide (34.9°S, 138.6°E) and Darwin (12.5°S, 130.9°E). The Ghan crosses Australia from the mainly agricultural mid-latitude south through the arid interior to the wet-dry tropical savannah south of and around Darwin. In the 2008 wet season (February) we observed a significant latitudinal gradient of CH4 increasing towards the north. The same pattern was observed in the late 2008 wet season (March-April), with a smaller latitudinal gradient. These will be compared with a dry season transect, to be undertaken in September/October 2008. The Air Pollution Model (TAPM), a regional scale prognostic meteorological model, is used to estimate the surface methane source strength required to explain the observed latitudinal gradient in CH4 in the wet season, and investigate the source type. Fluxes from cattle and termites together contribute up to 25% of the enhancements seen, leaving wetlands as the major source of wet season methane in the Australian tropics. Wetlands are the largest natural source of methane to the atmosphere, and tropical wetlands are responsible for the majority of the interannual variation in methane source strength. We attempt to quantify the annual methane flux contributed by anaerobic organic breakdown due to wet- season flooding in tropical Northern Territory.

  3. A laboratory superconducting high gradient magnetic separator

    SciTech Connect

    Yan, L.G.; Yu, Y.J.; Wang, Z.K.; Kao, Z.Y.; Ye, Z.X.; Xue, C.L.; Ye, P.; Cheng, Y.L.; Li, X.M.; Kong, Q.M.

    1989-03-01

    In order to know the effectiveness of high gradient magnetic separation for Kaolin clay purification and coal desulfurization in China and to develop suitable technology, a superconducting HGMS facility has been constructed and put into operation at the Institute of Electrical Engineering of Chinese Academy of Sciences. The working separation chamber is 80mm in diameter and 400mm in length. the magnet is wound with 0.75 and 0.5 mm in diameter NbTi superconducting composite. The winding is compact and wax-filled. The test proves that the magnet can operate at 5T. Special attention has been paid in the design and construction of the magnet cryostat in order for it to work as long as possible. In the wet beneficiation mode, there are two separation systems available, one is the upward pumping feeding system and another is with the downward gravity feeding. The rate of flow and the linear velocity are 0-0.5L/s and 0-100 cm/s respectively. The preliminary sample test results for Kaolin clay purification and coal desulfurization show the good feasibility of magnetic separation.

  4. The effect of salinity on oviposition and egg hatching in Culicoides variipennis sonorensis (Diptera: Ceratopogonidae).

    PubMed

    Linley, J R

    1986-03-01

    The preferences of Culicoides variipennis sonorensis females for oviposition on different salinities were tested in experiments using small wells in a 4 x 4 latin square array. The mean numbers of eggs deposited on wet surfaces on salinites of 0.0, 9.9, 19.0 and 34.0O/OO, were 1212, 659, 287, and 0, respectively. Within a higher range, salinites of 19.0, 23.0, 28.0 and 34.0O/OO yielded mean numbers laid of 110, 3, 6 and 0, respectively. The overall relationship could be reasonably well described by linear regression, implying, under experimental conditions, a decline of 458 eggs laid for every 10O/OO increase in salinity. Eggs laid directly onto salinities up to 19.0O/OO survived and hatched equally well; at 34O/OO, however, no eggs became tanned and none hatched. In contrast, when eggs were laid onto fresh water, then transferred to different salinities 24 hr later, they survived and hatched even at 34O/OO. PMID:3507474

  5. River salinity on a mega-delta, an unstructured grid model approach.

    NASA Astrophysics Data System (ADS)

    Bricheno, Lucy; Saiful Islam, Akm; Wolf, Judith

    2014-05-01

    With an average freshwater discharge of around 40,000 m3/s the BGM (Brahmaputra Ganges and Meghna) river system has the third largest discharge worldwide. The BGM river delta is a low-lying fertile area covering over 100,000 km2 mainly in India and Bangladesh. Approximately two-thirds of the Bangladesh people work in agriculture and these local livelihoods depend on freshwater sources directly linked to river salinity. The finite volume coastal ocean model (FVCOM) has been applied to the BGM delta in order to simulate river salinity under present and future climate conditions. Forced by a combination of regional climate model predictions, and a basin-wide river catchment model, the 3D baroclinic delta model can determine river salinity under the current climate, and make predictions for future wet and dry years. The river salinity demonstrates a strong seasonal and tidal cycle, making it important for the model to be able to capture a wide range of timescales. The unstructured mesh approach used in FVCOM is required to properly represent the delta's structure; a complex network of interconnected river channels. The model extends 250 km inland in order to capture the full extent of the tidal influence and grid resolutions of 10s of metres are required to represent narrow inland river channels. The use of FVCOM to simulate flows so far inland is a novel challenge, which also requires knowledge of the shape and cross-section of the river channels.

  6. Jurassic Lake T'oo'dichi': a large alkaline, saline lake, Morrison Formation, eastern Colorado Plateau

    USGS Publications Warehouse

    Turner, C.E.; Fishman, N.S.

    1991-01-01

    Recognition of alkaline, saline-lake deposits in the Morrison Formation significantly alters interpretations of depositional environments of this formation, and it also has important implications for paleoclimatic interpretation. Late Jurassic climate was apparently much more arid than had previously been thought. In fact, sedimentologic evidence suggests that the lake basin was typically dry for extended periods and enjoyed only brief wet intervals. This conclusion has important consequences for environmental interpretation of the habitat that was favorable for large herbivorous dinosaurs, which thrived in the Late Jurassic. -from Authors

  7. Parameter-exploring policy gradients.

    PubMed

    Sehnke, Frank; Osendorfer, Christian; Rückstiess, Thomas; Graves, Alex; Peters, Jan; Schmidhuber, Jürgen

    2010-05-01

    We present a model-free reinforcement learning method for partially observable Markov decision problems. Our method estimates a likelihood gradient by sampling directly in parameter space, which leads to lower variance gradient estimates than obtained by regular policy gradient methods. We show that for several complex control tasks, including robust standing with a humanoid robot, this method outperforms well-known algorithms from the fields of standard policy gradients, finite difference methods and population based heuristics. We also show that the improvement is largest when the parameter samples are drawn symmetrically. Lastly we analyse the importance of the individual components of our method by incrementally incorporating them into the other algorithms, and measuring the gain in performance after each step. PMID:20061118

  8. Spatial gradient tuning in metamaterials

    NASA Astrophysics Data System (ADS)

    Driscoll, Tom; Goldflam, Michael; Jokerst, Nan; Basov, Dimitri; Smith, David

    2011-03-01

    Gradient Index (GRIN) metamaterials have been used to create devices inspired by, but often surpassing the potential of, conventional GRIN optics. The unit-cell nature of metamaterials presents the opportunity to exert much greater control over spatial gradients than is possible in natural materials. This is true not only during the design phase but also offers the potential for real-time reconfiguration of the metamaterial gradient. This ability fits nicely into the picture of transformation-optics, in which spatial gradients can enable an impressive suite of innovative devices. We discuss methods to exert control over metamaterial response, focusing on our recent demonstrations using Vanadium Dioxide. We give special attention to role of memristance and mem-capacitance observed in Vanadium Dioxide, which simplify the demands of stimuli and addressing, as well as intersecting metamaterials with the field of memory-materials.

  9. The hydrography of the Mozambique Channel from six years of continuous temperature, salinity, and velocity observations

    NASA Astrophysics Data System (ADS)

    Ullgren, J. E.; van Aken, H. M.; Ridderinkhof, H.; de Ruijter, W. P. M.

    2012-11-01

    Temperature, salinity and velocity data are presented, along with the estimated volume transport, from seven full-length deep sea moorings placed across the narrowest part of the Mozambique Channel, southwest Indian Ocean, during the period November 2003 to December 2009. The dominant water mass in the upper layer is Sub-Tropical Surface Water (STSW) which overlies South Indian Central Water (SICW), and is normally capped by fresher Tropical Surface Water (TSW). Upper ocean salinity increased through 2005 as a result of saline STSW taking up a relatively larger part of the upper layer, at the expense of TSW. Upper waters are on average warmer and lighter in the central Channel than on the sides. Throughout the upper 1.5 km of the water column there is large hydrographic variability, short-term as well as interannual, and in particular at frequencies (four to seven cycles per year) associated with the southward passage of anticyclonic Mozambique Channel eddies. The eddies have a strong T-S signal, in the upper and central waters as well as on the intermediate level, as the eddies usually carry saline Red Sea Water (RSW) in their core. While the interannual frequency band displays an east-west gradient with higher temperature variance on the western side, the eddy frequency band shows highest variance in the centre of the Channel, where the eddy band contains about 40% of the total isopycnal hydrographic variability. Throughout the >6 years of measurements, the frequency and characteristics of eddies vary between periods, both in terms of strength and vertical structure of eddy T-S signals. These changes contribute to the interannual variability of water mass properties: an increase in central water salinity to a maximum in late 2007 coincided with a period of unusually frequent eddies with strong salinity signals. The warmest and most saline deep water is found within the northward flowing Mozambique Undercurrent, on the western side of the Channel. The Undercurrent

  10. Ionic composition of wet precipitation in the Petra Region, Jordan

    NASA Astrophysics Data System (ADS)

    Al-Khashman, Omar A.

    2005-11-01

    The results of chemical analysis of precipitation samples collected in Petra between October 2002 and May 2004 are presented. All samples were analyzed for major cations (NH 4+, Na +, K +, Ca 2+ and Mg 2+), major anions (Cl -, NO 3-, HCO 3- and SO 42-), conductivity and pH. The daily sample pH values ranged from 5.71 to 8.15 with an average value of 6.85 ± 0.5. Rainwater quality is characterized by low salinity and neutralized pH. Generally, the pH is high due to dust in the atmosphere, which contains a large fraction of calcite. Factor analysis was used to identify the factors that affect the presence of ions in wet precipitation; these factors permitted the identification of three source groups, namely crustal dust, sea-salt spray and combustion products. In general, the results of the present study suggest that the atmospheric composition in the Petra region is strongly influenced by natural sources rather than anthropogenic sources.

  11. Treatment of hydraulic fracturing wastewater by wet air oxidation.

    PubMed

    Wang, Wei; Yan, Xiuyi; Zhou, Jinghui; Ma, Jiuli

    2016-01-01

    Wastewater produced by hydraulic fracturing for oil and gas production is characterized by high salinity and high chemical oxygen demand (COD). We applied a combination of flocculation and wet air oxidation technology to optimize the reduction of COD in the treatment of hydraulic fracturing wastewater. The experiments used different values of flocculant, coagulant, and oxidizing agent added to the wastewater, as well as different reaction times and treatment temperatures. The use of flocculants for the pretreatment of fracturing wastewater was shown to improve treatment efficiency. The addition of 500 mg/L of polyaluminum chloride (PAC) and 20 mg/L of anionic polyacrylamide (APAM) during pretreatment resulted in a COD removal ratio of 8.2% and reduced the suspended solid concentration of fracturing wastewater to 150 mg/L. For a solution of pretreated fracturing wastewater with 12 mL of added H2O2, the COD was reduced to 104 mg/L when reacted at 300 °C for 75 min, and reduced to 127 mg/L when reacted at the same temperature for 45 min while using a 1 L autoclave. An optimal combination of these parameters produced treated wastewater that met the GB 8978-1996 'Integrated Wastewater Discharge Standard' level I emission standard. PMID:26942530

  12. Functionalization of micromodels with kaolinite for investigation of low salinity oil-recovery processes.

    PubMed

    Song, Wen; Kovscek, Anthony R

    2015-08-21

    Sandstone formations are ubiquitous in both aquifers and petroleum reservoirs, of which clay is a major constituent. The release of clay particles from pore surfaces as a result of reduced injection fluid salinity can greatly modify the recovery of hydrocarbons from subsurface formations by shifting the wettability properties of the rock. In this paper we demonstrate a microfluidic approach whereby kaolinite is deposited into a two-dimensional microfluidic network (micromodel) to enable direct pore-scale, real-time visualization of fluid-solid interactions with representative pore-geometry and realistic surface interactions between the reservoir fluids and the formation rock. Structural characterization of deposited kaolinite particles agrees well with natural modes of occurrence in Berea sandstones; hence, the clay deposition method developed in this work is validated. Specifically, more than 90% of the deposited clay particles formed pore-lining structures and the remainder formed pore bridging structures. Further, regions of highly concentrated clay deposition likely leading to so-called Dalmatian wetting properties were found throughout the micromodel. Two post-deposition treatments are described whereby clay is adhered to the silicon surface reversibly and irreversibly resulting in microfluidic systems that are amenable to studies on (i) the fundamental mechanisms governing the increased oil recovery during low salinity waterfloods and (ii) the effect of a mixed-wet surface on oil recovery, respectively. The reversibly functionalized platform is used to determine the conditions at which stably adhered clay particles detach. Specifically, injection brine salinity below 6000 ppm of NaCl induced kaolinite particle release from the silicon surface. Furthermore, when applied to an aged system with crude oil, the low salinity waterflood recovered an additional 14% of the original oil in place compared to waterflooding with the formation brine. PMID:26151880

  13. The Comparative Osmoregulatory Ability of Two Water Beetle Genera Whose Species Span the Fresh-Hypersaline Gradient in Inland Waters (Coleoptera: Dytiscidae, Hydrophilidae)

    PubMed Central

    Pallarés, Susana; Arribas, Paula; Bilton, David T.; Millán, Andrés; Velasco, Josefa

    2015-01-01

    A better knowledge of the physiological basis of salinity tolerance is essential to understanding the ecology and evolutionary history of organisms that have colonized inland saline waters. Coleoptera are amongst the most diverse macroinvertebrates in inland waters, including saline habitats; however, the osmoregulatory strategies they employ to deal with osmotic stress remain unexplored. Survival and haemolymph osmotic concentration at different salinities were examined in adults of eight aquatic beetle species which inhabit different parts of the fresh—hypersaline gradient. Studied species belong to two unrelated genera which have invaded saline waters independently from freshwater ancestors; Nebrioporus (Dytiscidae) and Enochrus (Hydrophilidae). Their osmoregulatory strategy (osmoconformity or osmoregulation) was identified and osmotic capacity (the osmotic gradient between the animal’s haemolymph and the external medium) was compared between species pairs co-habiting similar salinities in nature. We show that osmoregulatory capacity, rather than osmoconformity, has evolved independently in these different lineages. All species hyperegulated their haemolymph osmotic concentration in diluted waters; those living in fresh or low-salinity waters were unable to hyporegulate and survive in hyperosmotic media (> 340 mosmol kg-1). In contrast, the species which inhabit the hypo-hypersaline habitats were effective hyporegulators, maintaining their haemolymph osmolality within narrow limits (ca. 300 mosmol kg-1) across a wide range of external concentrations. The hypersaline species N. ceresyi and E. jesusarribasi tolerated conductivities up to 140 and 180 mS cm-1, respectively, and maintained osmotic gradients over 3500 mosmol kg-1, comparable to those of the most effective insect osmoregulators known to date. Syntopic species of both genera showed similar osmotic capacities and in general, osmotic responses correlated well with upper salinity levels occupied by

  14. The comparative osmoregulatory ability of two water beetle genera whose species span the fresh-hypersaline gradient in inland waters (Coleoptera: Dytiscidae, Hydrophilidae).

    PubMed

    Pallarés, Susana; Arribas, Paula; Bilton, David T; Millán, Andrés; Velasco, Josefa

    2015-01-01

    A better knowledge of the physiological basis of salinity tolerance is essential to understanding the ecology and evolutionary history of organisms that have colonized inland saline waters. Coleoptera are amongst the most diverse macroinvertebrates in inland waters, including saline habitats; however, the osmoregulatory strategies they employ to deal with osmotic stress remain unexplored. Survival and haemolymph osmotic concentration at different salinities were examined in adults of eight aquatic beetle species which inhabit different parts of the fresh-hypersaline gradient. Studied species belong to two unrelated genera which have invaded saline waters independently from freshwater ancestors; Nebrioporus (Dytiscidae) and Enochrus (Hydrophilidae). Their osmoregulatory strategy (osmoconformity or osmoregulation) was identified and osmotic capacity (the osmotic gradient between the animal's haemolymph and the external medium) was compared between species pairs co-habiting similar salinities in nature. We show that osmoregulatory capacity, rather than osmoconformity, has evolved independently in these different lineages. All species hyperegulated their haemolymph osmotic concentration in diluted waters; those living in fresh or low-salinity waters were unable to hyporegulate and survive in hyperosmotic media (> 340 mosmol kg(-1)). In contrast, the species which inhabit the hypo-hypersaline habitats were effective hyporegulators, maintaining their haemolymph osmolality within narrow limits (ca. 300 mosmol kg(-1)) across a wide range of external concentrations. The hypersaline species N. ceresyi and E. jesusarribasi tolerated conductivities up to 140 and 180 mS cm(-1), respectively, and maintained osmotic gradients over 3500 mosmol kg(-1), comparable to those of the most effective insect osmoregulators known to date. Syntopic species of both genera showed similar osmotic capacities and in general, osmotic responses correlated well with upper salinity levels occupied by

  15. Do laboratory salinity tolerances of freshwater animals correspond with their field salinity?

    PubMed

    Kefford, Ben J; Papas, Phil J; Metzeling, Leon; Nugegoda, Dayanthi

    2004-06-01

    The degree to which laboratory derived measures of salinity tolerance reflect the field distributions of freshwater biota is uncertain. In this paper we compare laboratory-derived acute salinity tolerance (LC(50) values) of freshwater macroinvertebrates (range 5.5-76 mS/cm) and fish (range 2.7-82 mS/cm) from southeastern Australia with the salinity from which they have been collected in the field. Only 4% of the macroinvertebrates were collected at salinity levels substantially higher than their 72-h LC(50) obtained from directly transferring animals from low salinity water to the water they were tested (direct transfer LC(50)). This LC(50) value was correlated with the maximum salinity at which a species had been collected. For common macroinvertebrates, the maximum field salinity was approximated by the direct transfer 72-h LC(50). For adult freshwater fish, 21% of species were collected at salinities substantially greater than their acute direct transfer LC(50) and there was a weak relationship between these two variables. Although there was a weak correlation between the direct transfer LC(50) of early life stages of freshwater fish and the maximum field salinity, 58% of the field distribution were in higher than their LC(50) values. In contrast, LC(50) determined from experiments that acclimated adult fish to higher salinity (slow acclimation) provided a better indication of the field distribution: with only one fish species (7%) being in conflict with their maximum field salinity and a strong positive relationship between these variables. This study shows that laboratory measures of acute salinity tolerance can reflect the maximum salinity that macroinvertebrate and fish species inhabit and are consistent with some anecdotal observations from other studies. PMID:15016457

  16. Generalized gradient and contour program

    USGS Publications Warehouse

    Hellman, Marshall Strong

    1972-01-01

    This program computes estimates of gradients, prepares contour maps, and plots various sets of data provided by the user on the CalComp plotters. The gradients represent the maximum rates of change of a real variable Z=f(X,Y) with respect to the twodimensional rectangle on which the function is defined. The contours are lines of equal Z values. The program also plots special line data sets provided by the user.

  17. 7 CFR 51.1582 - Soft rot or wet breakdown.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Soft rot or wet breakdown. 51.1582 Section 51.1582... Soft rot or wet breakdown. Soft rot or wet breakdown means any soft, mushy, or leaky condition of the tissue such as slimy soft rot, leak, or wet breakdown following freezing injury, scald, or other injury....

  18. 7 CFR 51.1563 - Soft rot or wet breakdown.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Soft rot or wet breakdown. 51.1563 Section 51.1563....1563 Soft rot or wet breakdown. Soft rot or wet breakdown means any soft, mushy, or leaky condition of the tissue such as slimy soft rot, leak, or wet breakdown following freezing injury....

  19. 7 CFR 51.1582 - Soft rot or wet breakdown.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Soft rot or wet breakdown. 51.1582 Section 51.1582... Soft rot or wet breakdown. Soft rot or wet breakdown means any soft, mushy, or leaky condition of the tissue such as slimy soft rot, leak, or wet breakdown following freezing injury, scald, or other injury....

  20. 7 CFR 51.1563 - Soft rot or wet breakdown.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Soft rot or wet breakdown. 51.1563 Section 51.1563....1563 Soft rot or wet breakdown. Soft rot or wet breakdown means any soft, mushy, or leaky condition of the tissue such as slimy soft rot, leak, or wet breakdown following freezing injury....

  1. Can I Stop Myself From Having a Wet Dream?

    MedlinePlus

    ... Can I Stop Myself From Having a Wet Dream? KidsHealth > For Teens > Can I Stop Myself From Having a Wet Dream? Print A A A Text Size Can I stop myself from having a wet dream? – Tom* You really can't stop wet dreams, ...

  2. Design consideration for wet welded joints

    SciTech Connect

    Szelagowski, P.; Osthus, V.; Petershagen, H.; Pohl, R.; Lafaye, G.

    1996-12-01

    Wet welding has become a joining technique that under certain circumstances can provide results which cannot be distinguished between wet or dry production and the achievable mechanical quality is comparable to dry atmospheric welds. Wet welding is not a process which can be applied easily and which can be properly handled by untrained diver welders. Wet welding is more than any other kind of welding process or procedure a joining technique that requires the full job-concentration and -knowledge of an excellent trained and skilled diver welder throughout the whole production time, who is 100% identifying himself with his task. Furthermore he must be fully aware of the production requirements and possible metallurgical/environmental reactions and outcomes. He must be able to be fully concentrated on the process performance throughout his total work shift. In short: he must be an outstanding expert in his field. The following paper will highlight these subjects and show the necessity of their exact observation to achieve excellent quality in wet welding.

  3. Advanced tests of wet welded joints

    SciTech Connect

    Pachniuk, I.; Petershagen, H.; Pohl, R.; Szelagowski, P.; Drews, O.

    1994-12-31

    Wet Welding has in former times only been applied to secondary structural components. Nowadays wet welding has become an upcoming repair process due to high process flexibility, its low investment costs and its high versatility. Even the quality of the wet welded joints has been improved remarkably due to intensive and concentrated development activities. However, especially in the North Sea regions owners of offshore structures and classifying authorities still hesitate to recognize the process as a reliable alternative to dry hyperbaric welding repair methods. It therefore requires further activities especially in the field of data development for life prediction of such repaired components. Advanced testing methods are necessary, additional design criteria are to be developed and achievable weldment quality data are to be included in acknowledged and approved standards and recommendations to improve the credibility of the process and to solve the problem of quality assurance for wet welded joints. A comprehensive project, sponsored by the European Community under the Thermie Programme, is in progress to develop new testing procedures to generate the required data and design criteria for the future application of the wet welding process to main components of offshore structures. It is the aim of the project to establish additional fitness for purpose data for this process.

  4. Wetting and particle adsorption in nanoflows

    NASA Astrophysics Data System (ADS)

    Drazer, German; Khusid, Boris; Koplik, Joel; Acrivos, Andreas

    2005-01-01

    Molecular dynamics simulations are used to study the behavior of closely fitting spherical and ellipsoidal particles moving through a fluid-filled cylinder at nanometer scales. The particle, the cylinder wall, and the fluid solvent are all treated as atomic systems, and special attention is given to the effects of varying the wetting properties of the fluid. Although the modification of the solid-fluid interaction leads to significant changes in the microstructure of the fluid, its transport properties are found to be the same as in bulk. Independently of the shape and the relative size of the particle, we find two distinct regimes as a function of the degree of wetting, with a sharp transition between them. In the case of a highly wetting suspending fluid, the particle moves through the cylinder with an average axial velocity in agreement with that obtained from the solution of the continuum Stokes equations. In contrast, in the case of less-wetting fluids, only the early time motion of the particle is consistent with continuum dynamics. At later times, the particle is eventually adsorbed onto the wall and subsequently executes an intermittent stick-slip motion. We show that van der Waals forces are the dominant contribution to the particle adsorption phenomenon and that depletion forces are weak enough to allow, in the highly wetting situation, an initially adsorbed particle to spontaneously desorb.

  5. Filling and wetting transitions at grooved substrates.

    PubMed

    Malijevský, Alexandr

    2013-11-01

    The wetting and filling properties of a fluid adsorbed on a solid grooved substrate are studied by means of a microscopic density functional theory. The grooved substrates are modelled using a solid slab, interacting with the fluid particles via long-range dispersion forces, to which a one-dimensional array of infinitely long rectangular grooves is sculpted. By investigating the effect of the groove periodicity and the width of the grooves and the ridges, a rich variety of different wetting morphologies is found. In particular, we show that for a saturated ambient gas, the adsorbent can occur in one of four wetting states characterized by (i) empty grooves, (ii) filled grooves, (iii) a formation of mesoscopic hemispherical caps (iv) a macroscopically wet surface. The character of the transition between particular regimes, that also extend off-coexistence, sensitively depends on the model geometry. The temperature at which the system becomes completely wet is considerably higher than that for a flat wall. PMID:24067670

  6. Wetting films on chemically patterned surfaces.

    PubMed

    Karakashev, Stoyan I; Stöckelhuber, Klaus W; Tsekov, Roumen

    2011-11-15

    The behavior of thin wetting films on chemically patterned surfaces was investigated. The patterning was performed by means of imprinting of micro-grid on methylated glass surface with UV-light (λ=184.8 nm). Thus imprinted image of the grid contained hydrophilic cells and hydrophobic bars on the glass surface. For this aim three different patterns of grids were utilized with small, medium and large size of cells. The experiment showed that the drainage of the wetting aqueous films was not affected by the type of surface patterning. However, after film rupturing in the cases of small and medium cells of the patterned grid the liquid from the wetting film underwent fast self-organization in form of regularly ordered droplets covering completely the cells of the grid. The droplets reduced significantly their size upon time due to evaporation. In the cases of the largest cell grid, a wet spot on the place of the imprinted grid was formed after film rupturing. This wet spot disassembled slowly in time. In addition, formation of a periodical zigzag three-phase contact line (TPCL) was observed. This is a first study from the planned series of studies on this topic. PMID:21875710

  7. Dynamic wetting on anisotropic patterned surfaces

    NASA Astrophysics Data System (ADS)

    Do-Quang, Minh; Wang, Jiayu; Nita, Satoshi; Shiomi, Junichiro; Amberg, Gustav; Physiochemical fluid mechanics Team; Maruyama-Chiashi Laboratory Team

    2014-11-01

    Dynamic wetting, as occurs when a droplet of a wetting liquid is brought in contact with a dry solid, is important in various engineering processes, such as printing, coating, and lubrication. Our overall aim is to investigate if and how the detailed properties of the solid surface influence the dynamics of wetting. We have recently quantified the hindering effect of fairly isotropic micron-sized patterns on the substrate. Here we will study highly anisotropic surfaces, such as parallel grooves, either perpendicular or parallel to an advancing contact line. This is done by detailed phase field simulations and experiments on structured silicon surfaces. The dynamic wetting behavior of drops on the grooved surfaces is governed by the combined interplay of the wetting line friction and the internal viscous dissipation. Influence of roughness is quantified in terms of the energy dissipation rate at the contact line using the experiment-simulation combined analysis. The energy dissipation of the contact line at the different part of the groove will be discussed. The performance of the model is assessed by comparing its predictions with the experimental data. This work was financially supported in part by, the Japan Society for the Promotion of Science (J.W., S.N., and J.S) and Swedish Governmental Agency for Innovation Systems (M.D.-Q. and G.A).

  8. Membrane-based wet electrostatic precipitation

    SciTech Connect

    David J. Bayless; Liming Shi; Gregory Kremer; Ben J. Stuart; James Reynolds; John Caine

    2005-06-01

    Emissions of fine particulate matter, PM2.5, in both primary and secondary form, are difficult to capture in typical dry electrostatic precipitators (ESPs). Wet (or waterbased) ESPs are well suited for collection of acid aerosols and fine particulates because of greater corona power and virtually no re-entrainment. However, field disruptions because of spraying (misting) of water, formation of dry spots (channeling), and collector surface corrosion limit the applicability of current wet ESPs in the control of secondary PM2.5. Researchers at Ohio University have patented novel membrane collection surfaces to address these problems. Water-based cleaning in membrane collectors made of corrosion-resistant fibers is facilitated by capillary action between the fibers, maintaining an even distribution of water. This paper presents collection efficiency results of lab-scale and pilot-scale testing at First Energy's Bruce Mansfield Plant for the membrane-based wet ESP. The data indicate that a membrane wet ESP was more effective at collecting fine particulates, acid aerosols, and oxidized mercury than the metal-plate wet ESP, even with {approximately}15% less collecting area. 15 refs., 7 figs., 6 tabs.

  9. Andreas Acrivos Dissertation Award: Onset of Dynamic Wetting Failure - The Mechanics of High-Speed Fluid Displacement

    NASA Astrophysics Data System (ADS)

    Vandre, Eric

    2014-11-01

    Dynamic wetting is crucial to processes where a liquid displaces another fluid along a solid surface, such as the deposition of a coating liquid onto a moving substrate. Dynamic wetting fails when process speed exceeds some critical value, leading to incomplete fluid displacement and transient phenomena that impact a variety of applications, such as microfluidic devices, oil-recovery systems, and splashing droplets. Liquid coating processes are particularly sensitive to wetting failure, which can induce air entrainment and other catastrophic coating defects. Despite the industrial incentives for careful control of wetting behavior, the hydrodynamic factors that influence the transition to wetting failure remain poorly understood from empirical and theoretical perspectives. This work investigates the fundamentals of wetting failure in a variety of systems that are relevant to industrial coating flows. A hydrodynamic model is developed where an advancing fluid displaces a receding fluid along a smooth, moving substrate. Numerical solutions predict the onset of wetting failure at a critical substrate speed, which coincides with a turning point in the steady-state solution path for a given set of system parameters. Flow-field analysis reveals a physical mechanism where wetting failure results when capillary forces can no longer support the pressure gradients necessary to steadily displace the receding fluid. Novel experimental systems are used to measure the substrate speeds and meniscus shapes associated with the onset of air entrainment during wetting failure. Using high-speed visualization techniques, air entrainment is identified by the elongation of triangular air films with system-dependent size. Air films become unstable to thickness perturbations and ultimately rupture, leading to the entrainment of air bubbles. Meniscus confinement in a narrow gap between the substrate and a stationary plate is shown to delay air entrainment to higher speeds for a variety of

  10. Aquarius Observations of Sea Surface Salinity

    NASA Video Gallery

    This visualization shows changes in global sea surface salinity, as measured by NASA’s Aquarius instrument aboard the Aquarius/SAC-D spacecraft, from December 2011 through December 2012. Red repr...

  11. Cold saline is more effective than room temperature saline in inducing paresthesia during axillary block.

    PubMed

    Rodríguez, J; Carceller, J; Bárcena, M; Pedraza, I; Calvo, B; Alvarez, J

    1995-08-01

    Confirmation of the perivascular position of the needle by the injection of cold saline may be helpful to the perivascular technique, since the elicitation of a paresthesia indicates the correct positioning of the needle. In this prospective, randomized study of 48 patients, we found a 100% incidence of successful block with saline at 8-11 degrees C compared to 75% in a control group with saline at room temperature. The paresthesia induced by cold saline appears to be due to thermic stimulation and not to mechanical nerve compression by the saline entering the axillary space. A more frequent rate of correct positioning of the needle was found in the group with cold saline. PMID:7618724

  12. Orthogonal, three-component, alkanethiol-based surface-chemical gradients on gold.

    PubMed

    Beurer, Eva; Venkataraman, Nagaiyanallur V; Rossi, Antonella; Bachmann, Florian; Engeli, Roman; Spencer, Nicholas D

    2010-06-01

    An orthogonal surface-chemical gradient composed of self-assembled monolayers on gold has been prepared by successive, controlled immersions in orthogonal directions into dilute solutions of dodecanethiol and perfluorododecanethiol. The resulting two-component orthogonal gradient in surface coverage was backfilled with 11-mercaptoundecanol, leading to a two-directional, three-component surface-chemical gradient. Water and hexadecane show distinctly different wetting behaviors on the gradient surface because of the differences in the hydrophobic and oleophobic natures of the three different constituents. These results are correlated with the chemical composition maps of the surface obtained by X-ray photoelectron spectroscopy. The homogeneity and the ordering of the self-assembled monolayer were investigated by dynamic water contact angle measurements and polarization-modulation infrared reflection-absorption spectroscopy. PMID:20166727

  13. Next generation low cost wet FGD system

    SciTech Connect

    Klingspor, J.S.; Bresowar, G.E.; Gray, D.E.

    1995-12-31

    Limestone based wet flue gas desulfurization (FGD) has been the dominating control technology since the introduction of the clean air act and is projected to be the preferred FGD technology for the foreseeable future. Following the introduction of wet FGD systems in the late `60s, the technology quickly reached maturity with only incremental improvements during recent years. However, deregulation, emission trading, and market forces have demanded significant improvements in capital and operating costs, performance, environmental impact, ease of retrofit and cycle time. In response to market demands, ABB has developed a new generation wet FGD system, named LS-2, based on the traditional open spray tower technology. The development of the LS-2 system has progressed methodically within the ABB R&D community within the last three years and is currently being demonstrated at Ohio Edison`s Niles station.

  14. Wet powder seal for gas containment

    DOEpatents

    Stang, L.G.

    1979-08-29

    A gas seal is formed by a compact layer of an insoluble powder and liquid filling the fine interstices of that layer. The smaller the particle size of the selected powder, such as sand or talc, the finer will be the interstices or capillary spaces in the layer and the greater will be the resulting sealing capacity, i.e., the gas pressure differential which the wet powder layer can withstand. Such wet powder seal is useful in constructing underground gas reservoirs or storage cavities for nuclear wastes as well as stopping leaks in gas mains buried under ground or situated under water. The sealing capacity of the wet powder seal can be augmented by the hydrostatic head of a liquid body established over the seal.

  15. Wet powder seal for gas containment

    DOEpatents

    Stang, Louis G.

    1982-01-01

    A gas seal is formed by a compact layer of an insoluble powder and liquid filling the fine interstices of that layer. The smaller the particle size of the selected powder, such as sand or talc, the finer will be the interstices or capillary spaces in the layer and the greater will be the resulting sealing capacity, i.e., the gas pressure differential which the wet powder layer can withstand. Such wet powder seal is useful in constructing underground gas reservoirs or storage cavities for nuclear wastes as well as stopping leaks in gas mains buried under ground or situated under water. The sealing capacity of the wet powder seal can be augmented by the hydrostatic head of a liquid body established over the seal.

  16. Sea Surface Salinity : Research Challenges and Opportunities

    NASA Technical Reports Server (NTRS)

    Halpern, David; Lagerloef, Gary; Font, Jordi

    2012-01-01

    Sea surface salinity (SSS) can be important in regulating sea surface temperature (SST). Two technological breakthrough satellite SSS missions, Aquarius and Soil Moisture and Ocean Salinity (SMOS), are currently producing high-quality SSS data. This paper provides an overview of the importance of SSS for weather and climate applications and describes the Aquarius and SMOS missions. The newness of adequately sampled SSS data prompted a first-time at-sea field campaign devoted to improved understanding of SSS variations.

  17. Treating nahcolite containing formations and saline zones

    DOEpatents

    Vinegar, Harold J

    2013-06-11

    A method for treating a nahcolite containing subsurface formation includes removing water from a saline zone in or near the formation. The removed water is heated using a steam and electricity cogeneration facility. The heated water is provided to the nahcolite containing formation. A fluid is produced from the nahcolite containing formation. The fluid includes at least some dissolved nahcolite. At least some of the fluid is provided to the saline zone.

  18. Grain boundary wetness of partially molten dunite

    NASA Astrophysics Data System (ADS)

    Mu, Shangshang; Faul, Ulrich H.

    2016-05-01

    Samples of Fo90 olivine and basaltic melt were annealed at a range of temperatures and a pressure of 1 GPa in a piston cylinder apparatus from 1 to 336 h. Post-run samples have melt contents from 0.3 to 6.8 % and mean grain sizes from 4.3 to 84.5 μm. Grain boundary wetness, a measure of the intergranular melt distribution, was determined by analyzing scanning electron microscope images with sufficiently high resolution to detect thin layers wetting grain boundaries, as well as small triple junctions. The measurements show that grain boundary wetness increases with increasing melt content to values well above those predicted by the idealized isotropic equilibrium model for a finite dihedral angle. Additionally, the melt geometry changes with grain size, with grain boundary wetness increasing with increasing grain size at fixed melt content. Grain boundary wetness and dihedral angle of samples annealed at a range of temperatures, but constant melt content does not depend on temperature. These observations emphasize that the dihedral angle alone is not adequate to characterize the melt distribution in partially molten rocks, as the idealized isotropic model does not account for the influence of grain growth. Diffusion creep viscosities calculated from the measured wetness reflect the grain size and melt content dependence. Accordingly, experimentally measured viscosities at small grain sizes underestimate the effect of melt to weaken partially molten rocks for coarser grain sizes. The presence of melt in the mantle may therefore enhance diffusion creep relative to dislocation creep.

  19. Anisotropic wetting properties on a precision-ground micro-V-grooved Si surface related to their micro-characterized variables

    NASA Astrophysics Data System (ADS)

    Li, P.; Xie, J.; Cheng, J.; Wu, K. K.

    2014-07-01

    Micro-characterized variables are proposed to precisely characterize a micro-V-grooved Si surface through the 3D measured topography rather than the designed one. In this study, level and gradient micro-grooved surfaces with depth of 25-80 µm were precisely and smoothly fabricated using a new micro-grinding process rather than laser machining and chemical etching. The objective is to investigate how these accurate micro-characterized variables systematically influence anisotropic wetting and droplet self-movement on such regular micro-structured surfaces without surface chemical modification. First, the anisotropic wetting, droplet sliding, pinning effect and droplet impact were experimentally investigated; then, theoretical anisotropic wetting models were constructed to predict and design the anisotropic wetting. The experiments show that the level micro-V-grooved surface produces the anisotropic wetting and pinning effects. It not only approximates superhydrophobicity but also produces high surface free energy. Moreover, the gradient micro-V-grooved surface with large pitch may lead to much easier droplet sliding than the level one along the micro-groove. The droplet self-movement trend increases with increasing the micro-groove gradient and micro-V-groove ratio. The micro-groove pitch and depth also influence the droplet impact. Theoretical analyses show that the wetting anisotropy and the droplet anisotropy both reach their largest value and disappear for a sharp micro-groove top when the micro-V-groove ratio is equal to 0.70 and 2.58, respectively, which may change the wetting between the composite state and the non-composite state. It is confirmed that the wetting behavior may be designed and predicted by the accurate micro-characterized variables of a regular micro-structured surface.

  20. Controllable underwater anisotropic oil-wetting

    SciTech Connect

    Yong, Jiale; Chen, Feng Yang, Qing; Farooq, Umar; Bian, Hao; Du, Guangqing; Hou, Xun

    2014-08-18

    This Letter demonstrates a simple method to achieve underwater anisotropic oil-wetting using silicon surfaces with a microgroove array produced by femtosecond laser ablation. The oil contact angles along the direction perpendicular to the grooves are consistently larger than those parallel to the microgroove arrays in water because the oil droplet is restricted by the energy barrier that exists between the non-irradiated domain and the trapped water in the laser-ablated microgrooves. This underwater anisotropic oil-wetting is able to be controlled, and the anisotropy can be tuned from 0° to ∼20° by adjusting the period of the microgroove arrays.